Nasa Cr-2526 Energy Recovery from Solid Waste

NASA CONTRACTOR NASA CR-2526 REPORT

OS u-» CM

ENERGY RECOVERY FROM SOLID WASTE Volume 2 - Technical Report

C. J. Huang and Charles Da/ton

Prepared by UNIVERSITY OF HOUSTON Houston, Texas 77004 for Lyndon B. Johnson Space Center - 't»-w ~

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION • WASHINGTON, D. C. • APRIL 1975 1 . Report No. 2. Government Accession No. 3. Recipient's' Catalog No. NASACR-2526 4. Title end Subtitle 6. Rupert Dura - April • 1975 ". ENERGY RECOVERY FROM SOLID WASTE, 6. Performing Organization Code VOLUME 2 Technical Report .

7. Author(i) 8. Performing Organization Report No. C. J. Huang, Director ' Charles Dalton, Associate Director S-443 10. Work Unit No.: , 9. Performing Organization Nime tnd Addresi University of "Houston — -•-•-• 11. Contract or Grant No. ., Houston, 'Texas' 77004 ! NOT- 44- 005- 114 13. Type of Report and Period Covered 12. Sponsoring Agency Nime and Address Final Report 1974 National Aeronautics and Space Administration Lyndon B. Johnson Space Center 14. Sponsoring Agency Coos Houston, Texas 77058 16. Supplementary Notes

Prepared as Final Report of the 1974 NASA/ASEE Systems Design Institute

18. Abstract

A systems analysis of energy recovery from solid waste demonstrates the'feasibility of several current processes for converting solid waste to an energy form. The problem is considered from a broad point of view. The social, legal, environmental, and political factors are considered in depth with recommendations made in regard to new legislation and policy. Biodegradation and thermal decomposition are the two areas of disposal that are considered with emphasis on thermal decomposition. A technical and economic evaluation of a number of available and developing energy-recovery processes is given. Based on present technical capabilities, use of prepared solid waste as a fuel supplemental to coal seems to.be the most economic process by which to recover energy from solid waste. . Markets are considered In detail with suggestions given for improving market .conditions and for developing market stability. A decision procedure is given to aid a'community in deciding on its options In dealing with solid waste. A new pyrolysls process is suggested. An application of the methods of this study are applied to Houston, Texas.

17. Key Words (Suggested by Author(s)) . -,-...'. 18. Distribution Statement ' Energy Recovery • STAR Subject Category: . . '• ' Resource Recovery 44 (Energy Production and Conversion) ' Solid Waste 'Garbage ,

19. Security dasslf. (of this report) 20. Security dealt, (of this page) 21. No. of Pages 22. Price' Unclassified UnclaBstfied 242 . $7. 50 .

'For sale by the National Technical Information Service, Springfield, Virginia 22151

lilt 74) 'AUTHORS

Dr. George Edward Antunes University of Houston Dr. Ronald Lad Carmichael University of Missouri at Rolla Dr. Tsong-how Chang University of Wisconsin, Milwaukee Dr. Shang-I Cheng Cooper Union Dr. Gary Max Halter Texas ASM University Dr. Joel Joseph Heberte; Rice. University Dr. Francis Wilford Holm Texas A & M University Dr. Edwin Carl Kettenbrink, Jr. University of Texas of the Permian Basin Dr. James Lowell Kuester Arizona State University Dr. Loren Daniel Lutes Rice; University Dr. Dupree Maples Louisiana State University Dr. Arthur Christian Meyers University of Colorado Dr. Shankaranarayana R. N. Rao Prairie View A & M University Dr. Armando Riesco II University of Puerto Rico Dr. Fredrick Wallace Swift University of Missouri at Rolla Dr. Michael L. Steib .- ., - . . University of Houston Dr. William Danny Turner Texas A & I University Dr. Lambert John Van Poolen Calvin College Dr. Henry Allen Wiebe University of Missouri at Rolla

;. EDITORS: Lambert Van Poolen George Antunes Ronald Carmichael Fred Swift" • Dan. Turner- TABLE OF CONTENTS

CHAPTER TITLE PAGE 1, INTRODUCTION 1.1 The Solid Waste Problem . 1 1.'2 Why Energy and Resource Recovery from Solid Waste? 1 1.3 Parameters of the Study • 1 1.4 The Approach Followed 1 2, SOCIAL ASPECTS OF SOLID WASTE MANAGEMENT 2.1 Introduction - 5 2.2 Factors Deterring Change 6 .1 Cost '6 ..2 Maintenance of Political Stability . 7 .3 Industrial Interest Groups 7 2.3 Environmental and Other Factors Motivating Change 7 .1 Land Dumping 8 .2 Ocean Dumping . . 9 .3 Regulations Relevant to Solid Waste 10 .4 Anticipated Environmental Regulations 12 .5 Environmental Regulations Significant to Energy Generation from Solid Waste 12 2.4 Federal Policies Affecting Energy and Resource Recovery from Solid Waste 14 .1 Freight Rate Policies for Virgin and Secondary Materials 15 .2 Federal Tax Policies for Virgin Materials 15 .3 Federal Policies Regulating Natural Gas 16 .4 Federal Procurement Policies and the Secondary Materials Market 17 .5 Federal Policies Encouraging Development of Recovery Technology 17 2.5 State and Local Legal and Political Problems Affecting Energy and. Resource Recovery from Solid Waste . 19 .1 New and Unproven Technologies 20 .2 Noncrisis Attitudes of Citizens and City Officials 20 .3 Problems in Developing Area-Wide Organizations for Energy and Resource Recovery • 20 .4 Lack of Planning in Selection of Disposal Sites 22 ""'•-• .5 Potential Problems in Exclusive Franchises 22 .6 Legal Liabilities for Products Produced from MMR 22 .7 . Financial and Contractual Options Open to Local Governments 23 2.6 . Product Design Legislation to Reduce Waste at Source 24 .1 Background 24 .2 Recapping Rubber Tires 24 .3 Nonrefillable Bottles 25 .4 Bimetallic Cans 26 .5 Low-Volume Potentially Hazardous Material -26 2.7 Summary of Social Aspects of Solid Waste Management 27 2.8 Recommendations 29 3, TECHNICAL ASPECTS OF ENERGY RECOVERY FROM SOLID WASTE 3.1 . Introduction 34 ".1 Sani'tary Landfill 34 .2 Pre-Conversion Processing Routes 35 .3 Energy Conversion Alternatives 36 .4 Process Economic Data Sheets 38 3.2 Pre-Processing .Techniques •• 39 .1 General Considerations . 39 .2 Size Reduction Techniques . • 40 .3 Separation Techniques 44 .4 . Separation and Size Reduction As A Terminal Process 50 3.3 Incineration Process 57 .1 Introduction 57 .2 Description of Incinerator Process 59 .3 Incineration System Alternatives Selected for Further Analysis 67 .4 Summary of Incineration Systems 93

iii CHAPTER AT:IT'LE PAGE 3.4 Pyrolysis Process - ;•" -- - 93 .1 Introduction? 'ist&': -• • • ' .5: -:V *s - • - ' ' • ' 93 .2 General Considerations •.•<... 93 .3 . Description of Process . •<< - .•, . . 96 .4 Further Analysis of Selected Pyrolysis-System Alternatives . 110 .5 • Summary of Pyrolysis Alternatives • .-•' - • -• 130. .6 A Study of a Proposed Pyrolysis Process 133 3.5 Biodegradation Processes • ''' . 137 .1 Introduction 137 .2 Composting . 137 .3 Methane Production Process 148 .4 Biochemical Process 155 .5 Critical Assessment of Biodegradation System Alternatives 158 .6 Summary 160 3.6 Summary 160 4, MARKETS 4.1 Introduction . 170 - 4-. 2 Marketable Products 170 .'1 • Material Recovered Before Conversion . 170 .2 Products Derived from Conversion Processes . . . 170 .3- Conversion Byproducts 170 4.3 "Factors Related to Current Market Conditions !171 "Y1-- Freight Rate Policies . 171 .2 Federal Tax Policies for Virgin Materials 171 .3' Federal Policies Regulating Natural Gas 171 .4 Federal Procurement Policies 172 v.5< Social Attitudes 172 4.4 Products Suitable for Current Markets 172 • .1 Product Description 172 .2 ' Market Demand 174 .3 Market Prices . 176 4.5 Potentially Promising Markets 179 416 Markets to be Developed 179 • .1 Research and Development 179 4.7 Trends and Developments • 180 .1 Some Recent Trends 180 .2 Contract Agreements 182 .3 Market Locations • 182 4.8 Conclusion • • 182 5. A DECISION PROCEDURE 5.1 Introduction . 187 .1 Justification 187 .2 Philosophy 187 .3 Outline of Procedure 188 5.2 Development of Selection Criteria 188 .1 Introduction. 188 ..2 Economic and Cost Related Characteristics 188 .3 Qualitative Characteristics 190 .4 Outline of Considerations 190 .5 Discussion of Tradeoffs 191 5.3 Selection of Feasible Options . 191 .1 Preliminary Selection Criteria 191 .2 Technical Options Available 192 .3 Screening • 192 5.4. Analysis of Feasible Systems 192 .1 Introduction 192 .2 Evaluation Techniques 193 5.5 Final Decision 200 .1 Use of Recommendations from Decision Procedure 200 .2 Responsibility for Final Decision . 203 .3 Examples of Decision Structures 203 5.6 Summary 205

iv CHAPTER TITLE EASE APPENDICES A. Results of Pre-Bngineering Design on the HAAS Process 206 B. Houston Application 216 * C. Institute Staff 225 D. Contributors and Consultants 230 B. Vendor List : 233 GLOSSARY 238 LIST OF FIGURES ... . :, .. , ,-..-.:...... ' . '. Figure,,.?- .1. . . ConventionaloMethods of Refuse Disposal ....,_ 3- 2 Refuse Pre-Conversion Processing Routes 3- 3 Refuse Incineration Routes, with^nergy- Recovery • 3- 4 . Py.rolysis-'Ofi'Refuse ..,.;-..' . . 3- 5 f-Biodegradatipn. of Refuse -• . s- - . •' ' . . 3- 6 Process Cost Sheet / .•...,.'..,.-. •- 3- 7 Resource Recovery Data Sheet • .'. 3-,.8-v^:;: Vertical Shaft JJammermi 11, ._ • f- .,••,., • , 3- 9 \.i Vr^Hor.izontaljjghjaft .Hairanermili • ,-.,.- 3-10 Primary Shredding Energy .Consumption for Mixed.Municipal Refuse,; 3-11 %i,»; .--piskj Mill,. Schematic , '» - •. •?, .. '\: • . >. . . ' 3-12 Wet Pulper ^Schematic 3-13 Schematic of Rasp Mill 3-14 Cage Disintegrator'Schematic ,.•-.:«:;• • - - . • -;,. - • ...... -, .\ 3-15 Suspended-.type Permanent Magnetic Separator, • . . " _' 3-16 Pulley-type Permanent Magnetic Separator 3-17 Capital Cost of Magnetic Separators as a Function of Capacity 3-18 Capital Cost of Magnetic-Separators as: a Function-of - Belt Width. .--,,&•• 3-19 Zig-Zag.Air Classifier > ..> ...... v "' 3-20 Horizontal Air Classifier ...'.. . '. 3-21 Vertical Air Classifier - ,-• - . 3-22 Sortex Air Classifier -.f ,-.....-,.. 3-23 Vane/rotational Air Classifiers -._-,,-'.'• : .. * . 3-24 Cross Flow Air Classifier ..*..,' . • . • -- . . 3-25 Impulse Type Air Classifier 3-26 Schematic Diagram of an Optical Separator .. 3-27 Types of Iner.tial Separators ,-.<•• . . . -. ^ 3-28 Schematic of Pulley-type Eddy-Current Separator 3-29 Principle of High Voltage Electristatic Separator 3-30 > CapitalV Cos.t of Sutton, Steele,, andr Steele Stpners. . .,*, ,.-,'-• : 3r31- -, EcoTFue'l?*J...I: .Process Flow Diagram. . . • '. . . . • •• x ••--••• 3-32 Eco-Fuel II Process Flow Diagram 3-33 Basic Flow Diagram for Black-Clawson Process 3-34 Composition Limits for Self-Burning of Refuse 3-35 Flow Diagram for the Chicago Northwest Incinerator 3-36 Refuse Flow Diagram for the Nashville Incinerator Facility 3-37 CPU-400 System Schematic 3-38 Schematic of Munich North Plant, Block I 3-39 Schematic of Munich North Plant, Block II 3-40 Schematic of Stuttgart Plants 3-41 Schematic of Pre-Conversion Plant for St. Louis Supplemental Fuel Project 3-42 Schematic of Refuse Firing Facilities of St. Louis Supplemental Fuel • Plant 3-43 Schematic of Water-Wall Incinerator at Saugus, Mass. 3-44 Variation of Gross Cost/Ton for St. Louis Supplemental Fuel Project 3-45 Variation in Net Cost/Ton for St. Louis Supplemental Fuel Project 3-46 Sensitivity of Supplemental Fuel Process Net Cost/Ton to Fuel and Metal Credits 3-47 Effects of Time, Temperature, and Particle Size on Pyrolysis Product Distributions 3-48 Schematic of Garrett Pyrolysis Process 3-49 Battelle Vertical Shaft Reactor Schematic 3-50 Proposed Battelle Process Pyrolysis Plant Schematic 3-51 Flow Diagram of Georgia Tech Pyrolysis System 3-52 Flow Diagram of URDC Pyrolysis Process 3-53 Flow Diagram of Union Carbide Process 3-54 Barber-Coleman Pyrolysis System Flow Sheet 3-55 Montsanto Landgard Pyrolysis System Flow Sheet 3-56 Rust Engineering Pyrolysis Process Schematic 3-57 Schematic of West Virginia University Pyrolysis Process 3-58 Battelle Molten Salt Laboratory Reactor Schematic 3-59 Battelle Molten Salt Process Schematic 3-60 Bureau of Mines Pyrolysis Process Schematic 3-61 NYU Apparatus Schematic 3-62 University of California Pyrolysis Unit 3-63 Union Carbide Reactor

vi Figure 3-64 Flow Sheet of the HAAS Process 3-65 Variation in Refuse/Sludge Moisture Content . ' • , 3-66 Usable Sewage Sludge as a Function of Moisture 3-67 Typical and Comparative Temperature Profile* Obtained from Composting Municipal Refuse t > 3-68 Composting Time vs. Initial C/N Ratio 3-69 pH vs. Compost Age Curve for Johnson City Windrow Process 3-70 Schematic Flow Diagram for Fairfield-Hardy Coopost Systea 3-71 Schematic of Fairfield-Hardy Digester 3-72 Compost Cost Data - 3-73 Block Diagram of the Pheffer-Dynatech Anerobic Digestion System 3-74 Variation of Methane Price Needed with Municipality Location 3-75 Gas Production from an Experimental Sanitary Landfill 3-76 Pilot-Plant Flow Sheet for Production of Single Cell Protein

Figure 4- 1 Costs of Labor and Equipment; Recent Trends 4- 2 Prices of Coal, and Iron and Steel} Recent Trends

Figure 5- 1 Block Diagram of Decision Process 5- 2 Decision Procedure 5- 3 Process Cost Sheet : 5- 4 Resource Recovery Data 5- 5 Cash Expenditure Summary 5- 6 Cost Analysis Sheet 5- 7 Desirability Score Example 5- 8 Weighting Work Sheet 5- 9 Desirability Score Work Sheet 5-10 Overall Systems Evaluation Example

Figure A- 1 HAAS Material Balance for a 1136 Metric Ton Per Day Plant A- 2 NAAS Energy Balance for a Capacity 1136 Metric Ton Per Day Plant

vfl LIST OF TABLES

Table 2- 1 National Primary and Secondary Ambient Air Quality Standards 2- 2 Standards of Performance for New Stationary Sources 2- 3 Summary of Estimates of Tax Benefits, 1970 2- 4 Some Energy Recovery Systems Under Construction 2- 5 Some Demonstration Projects of Significance 2- 6 Social and Political Factors • 2- 7 Environmental Factors 2- 8 Legal Factors 2- 9 Summary of Legal, Environmental, Political, Social, and Economic Factors

Table 3- 1 Total Capital Requirements for a Close-in Sanitary Landfill 3- 2 Total Capital Requirements for a Remote Sanitary Landfill 3- 3 Typical Composition of Mixed Municipal Refuse 3- 4 Solid Waste Shredding Operations 3- 5. Characteristics of the Osborne Dry Separator 3- 6 Size Distribution of Gareett Secondary Shredded Solid Waste 3- 7 Calculated Amount of Materials Recycled per 8-hour Day 3- 6 Economic Data-Black Clawson Process 3- 9 Typical Incineration Plants with Energy Recovery ,_ 3-10' Representative Supplemental Fuel Plants 3-11 General Electric's Steam Demand for the Saugus Plant 3-12 Cost Data on Saugus, Mass. Water-Wall Incinerator 3-13 Economic Data-CPU-400 System 3-14 Economic DatarSt. Louis Supplemental Fuel System , ' • •» 3-15 Economic Data-St. Louis Supplemental Fuel System 3-16 Economic Data-St. Louis Supplemental Fuel System .3-17 Economic Data-St. Louis Supplemental Fuel System 3-18 Standardized Costs per Ton for the Horner-Shefren Supplementary Fuel Process 3-19 Properties of Eco-Fuel™ I 3-20 ; Properties of Eco-Fuel™ II . 3-21 Process Cost Sheet 3-22 Reactor Type Characteristics 3-2 3a Pyrolysis Reactor Classifications (Metric Units) 3-2 3b Pyrolysis Reactor Classifications (English Units) 3-24 Pyrolysis Process Groupings 3-25 Union Carbide Fuel Gas Composition ' 3-26 Economic Data-Union Carbide System 3-27 Monsanto Landgard Prototype Performance Results 3-28 Economic Data-Monsanto Landgard System • . 3-29 Recoverable Products and Energy-Garrett Pyrplysis Process 3-30 Physical and Chemical Properties of Oil Fractions 3-31 Garrett Pyrolysis Gas Composition 3-32 Garrett Pyrolysis Char Composition 3-33 Economic Data-Garrett Pyrolysis Process 3-34 Composition of Dry Pyrolysis Gas from the West Virginia University Process 3-35 Economic Data-West Virginia University Process 3-36 Economic Analysis of the NAAS Process 3-37 Typical Composting Processes 3-38 Elements in 42-Day-Old Compost at Johnson City 3-39 Municipal Solid Waste Composting Plants in the United States (1973) 3-40 Estimates of Capital Costs, Energy, and Labor Requirements for Fairfield- Hardy Compost Systems 3-41 Economic Data-Fairfield-Hardy Compost System 3-42 Economic Data-Pfeffer-Dynatech Methane Gas System 3-43 Landfill Gas Composition

Table - 1 Summary of Estimate of Tax Benefits, 1970 - 2 Gaseous Fuel Analysis . - 3 Wastepaper Utilization in Paper and Paperboard - 4 Wastepaper Availability (Recoverable Grades, 1970) - 5 Beer and Soft Drink Fillings and Container Consumption, 1967-1970 in Million Units - 6 Glass Production and Purchased Gullet Consumption, 1967 - 7 Variation of Natural Gas Prices

vtH Table 5- 1 Weight Determination Example for One Period 5- 2 Desirability Factors

Table A- 1 List of Equipment for the NAAS Process A- 2 Purchased Equipment Investment for NAAS Process A- 3 Major Operating Variables of the NAAS Process A- 4 Plant Fixed Cost A- 5 Utility Requirements and Costs for the NAAS Process A- 6 Operating Costs for the NAAS Process A- 7 Economic Balance of the NAAS Process - 5 Cases

Table B- 1 Weighting of the Desirability Vector for Houston 1974 B- 2 Weighted Scores B- 3 Weighted Scores B- 4 Averages of the Sums of the Weighted Scores B- 5 Cost-Score Analysis for a 1000 TPD in Houston B- 6 Overall View with a Different Set of Opinions B- 7 Assumptions in Cost Analysis B- 8 Available Energy Recovery Processes from Municipal Solid Wastes

ix Chapter 1 Introduction

B/ODEQRADAT70 INCINERATION? 1,1 THE SOLID WASTE PROBLEM before such recovery can be practiced widely, -efficiently, and economically. It is estimated that the amount of The investigation in this report is an solid waste generated daily in this country attempt to help-solve some of these averages between 1.18 and 1.81 kilograms problems. (2.6 to 4 pounds) for each person. The exact estimate within this range depends on the authority quoted. Even at the lower 1,3 PARAMETERS OF THE STUDY estimate, the total mass of material to be handled is overwhelming and the average per person, as well as the total, is in- Emphasis in this study is primarily creasing. The material comes from many on energy recovery from solid waste. How- sources and with a great diversity of ever, it is virtually impossible to con- physical form and chemical composition. sider energy recovery techniques without also considering the recovery of materials. Contributing to the problem is the In many instances, both types of recovery fact that, concurrent with the steadily will be necessary for an economically increasing mass of solid waste for dis- viable process. In general, however, posal, traditional methods of disposal are resource recovery is given somewhat less becoming less and less acceptable socially emphasis in this study. and environmentally, or economically, practical. The reasons are many and include The collection of solid waste is con- a complex interaction of political, environ- sidered to be outside the scope of this mental, legal, social, economic, and tech- study and is not treated in any detail. nical considerations. There are several reasons^for this. First, much excellent work already has been done Disposal of solid waste is one of the on the collection problem. Second, the most difficult and frustrating problems need for collection is not unique to energy facing municipal authorities. and resource recovery; it still must be done for traditional disposal practices, and collection methods will not differ too 1,2 WHY ENERGY AND RESOURCE RECOVERY FROM much in either case. Third, as a nation- oULlL) WHO It. wide average, the collection of solid waste costs about $45 per ton and represents about 80 percent of the total for For many decades our concern with present traditional disposal costs. How- solid waste has concentrated on disposal. ever, current trends in disposal costs are The attitude has been: Get rid of it— such that collection undoubtedly will somehow, somewhere. Only recently have present a much smaller proportion of total we begun to focus attention on its utili- solid waste handling costs in the future. zation. A growing awareness is developing The design group concluded, therefore, that we as a nation are consuming our non- that it was best to restrict the study renewable metal, mineral, and energy re- efforts to the recovery technologies. sources at a rate faster than population growth. A logical result of this awareness Solid waste, as treated in this study, is the realization that solid waste is in consists of what generally is known as itself a resource; we are discarding via Mixed Municipal Refuse (MMR). It is what the garbage can a high proportion of our the municipality normally picks up at the primary resources. curb of residences and from commercial and institutional buildings. The combination of the growing unac- ceptabllity of traditional disposal methods Sewage treatment and the handling of along with the need to conserve the nation's industrial wastes are specifically excluded resources has spurred efforts to exploit from this study. solid waste. Initially, efforts were concerned with recovering materials; ferrous and nonferrous metals, glass, and paper. 1,1 THE APPROACH FOLLOWED The current energy, shortage helped stimulate a further awareness that the" high percentage of organic material including In carrying out the study, we have solid paper in solid waste represents an attempted first to identify the variou s energy resource. More recent utilization nontechnical aspects of the solid waste efforts, therefore, have included the de- problem: political, environmental, legal, velopment of ways to recover effectively social, and economic. Solutions are sug- the energy resources inherent in solid gested for at least some of these problems. was te. It is recognized that the dividing line between nontechnical and technical problems Although it makes good sense to re- sometimes is vague, and we have attempted cover energy and materials from solid to show the interactions between the two. waste, many problems remain to be solved Insofar as possible, we have tried the different processes — including their to identify all of the publicly known social, environmental, and related con- techniques or processes for recovering siderations — on as nearly an equitable energy or materials from solid waste. basis as possible. Where data do not exist At least 30 processes exist for the con- or are proprietary, we have exercised our version and recovery of energy products best engineering judgment when making esti- and these can be categorized broadly as mates. incineration, pyrolysis, or biodegradation processes. Numerous variations are Along with this activity, a concept possible within each broad category. for a new pyrolysis process was developed and is suggested for further research. Energy products may :be in the form of solft-ds, liquids,8or gases — or energy Various aspects of the marketing may be' recovered more directly as hot situation and other utilization factors water or steam. Some processes recover relating to the different energy and re- combinations of these several types of covered products are analyzed and dis- energy. The form, or forms, of energy cussed. and other products recovered depend on the type of process, its operating con- As the study progressed, it became ditions, and economic factors. evident that no single conversion process was superior to all others as an answer to All levels of technical develop- the solid was.te problem under all condition ment' are represented by the many dif- The choice of appropriate conversion proces ferent processes available. Some are for energy resource recovery is highly sen- still in the R & D stage and some are sitive to the local situation. The study in pilot plant testing. In some instan- group therefore developed, and describes in ces commercial-scale facilities are this report, a decision model employing the under construction, and several commer- systems approach. It believes that this cial-scale units are completed and in model will be helpful to municipal authori- operation-. ties in selecting from among the many alternatives available the best route to These various levels of development follow — energy recovery, materials .re- and the, different capacities involved make covery, or both — and the conversion pro- comparative evaluations difficult. How- cess best suited to their particular local ever, we have attempted to compare the situations. technical and economic characteristics of

2 Chapter 2 Social Aspects of

Solid Waste Managemen' f~\ ' ^^iF f t

INCINERATION? Page Intentionally Left Blank 2-1 INTRODUCTION and over 70 percent of incinerators have had pollution problems (refs. 2-2, 2-3). Thus, Louie Welch, former mayor of Houston, the use of sanitary landfill or incineration Texas, once said "Everyone wants us to pick does not necessarily mean that refuse is up his garbage, but no one wants us to put disposed of in an environmentally sound it down". This sentence succinctly summar- manner. izes the solid waste problem facing Ameri- can cities. In a climate of public opinion The responsibility for refuse collec- which is frequently hostile, and at best tion and disposal generally rests with the apathetic, municipal governments must cope municipality, .although counties often have with the dual problem of solid waste collec- responsibility, for unincorporated areas. tion and disposal. The average citizen is In some instances, states have disposal res- primarily concerned with collection. He is ponsibility (Connecticut; Vermont, Wiscon- unconcerned with disposal unless the dis- sin) ; or the responsibility lies with a posal site is near his home. This leaves regional authority. the city officials with the near impossible task of finding an acceptable disposal Cities must change the way in which method. they dispose of Mixed Municipal Refuse (MMR). A disposal system must be "economi- A recent survey .(ref. 2-1) by the Na- cal" and not pollute air or water, but most tional League of Cities (NLC) emphasizes of all it must be a method of disposal this lack of concern on the part of citi- which does not create political difficul- zens and the ambivalent attitudes of muni- ties. cipal officials. The survey found that both mayors and city councilmen ranked re- There has been much discussion on fuse and solid waste as the most important utilizing the energy content of MMR and on of 28 major urban problems. However, when recovering potentially useful materials from these problems were grouped into 8 substan- refuse. But trash disposal is low on the tive categories, environmental concerns agenda of both decision-makers and the gen- (which includes solid waste management) eral public. The public usually does not ranked 5th. Thus, solid waste management have much knowledge about public policy as a general priority is not high on the issues, nor is the average person interested average municipal agenda. The NLC survey in public policy. The problem of solid also attempted to gauge the perceptions waste disposal is no exception. Those data of municipal officials about citizen pri- which are available indicate the perception orities by.asking officials the question, by municipal officials to be correct; solid "What'do citizens frequently complain waste is of little concern to the general about?" The 14 different problems men- public. An Illinois survey found over 70 tioned ranged from dog and other pet con- percent of that state's residents to be trol problems (most frequently mentioned) satisfied with present collection and dis- to fire protection (least frequently men- posal methods. To the extent that respon- tioned) , but solid waste was not even named dents perceived problems, they dealt exclu- as an area of citizen concern. sively with collection, e.g./ noise, bent or damaged trash cans, and odor (ref. 2-4). The primary reason why solid waste has become such a large problem for most A national sample of American house- cities is that Americans are generating wives found that a third of those inter- more and more garbage each year. At the viewed were unaware of what happened to present time each person in the U. S. their trash once it was removed from their generates about 1.18 kilograms (2.6 pounds) premises. Over two thirds of those inter- of solid waste per day. While Americans viewed reported never having considered the are producing more and more solid waste, costs of solid .waste collection and disposal constraints are being placed upon disposal prior to the interview (ref. 2-5). methods. For a number of reasons, the solid In the past, open dumping and burning waste concerns of public officials are also was the method of disposal used by most primarily in the area of collection: communities. However, regulations restricting air and water pollution have led 1. Most of the cost of solid waste to the closing of many open dumps. Sani- management (over 80 percent) is in collec- tary landfill and incineration have become tion. Currently, less than 20 percent of the two environmentally acceptable waste a city's solid waste management budget is disposal methods. Two points must be con- for disposal, although this proportion can sidered with respect to landfills and in- be expected to increase sharply as existing cineration. First, most of the municipal landfills are exhausted. solid waste in the United States is disposed of in open dumps. Over 80 percent 2. For health, aesthetic, and politi- of municipal refuse is simply dumped. cal reasons, garbage must be collected on a Approximately 8 percent is incinerated, and regular basis without interruption. The only 6 percent is put in sanitary landfill decision-maker is concerned with scheduling, (ref. 2-2). Second, many sanitary landfills dispatching, and system reliability in

5." collection services. Just getting the men The city of Houston was forced to abandon and trucks out and the insuring that the a large resource recovery and compost sys- garbage is collected occupies most of the tem because of.the opposition of nearby re- energies of municipal solid waste offi- sidents who complained about odor, litter, cials. and traffic problems. When residents began lying down at the facility entrance to bar 3.- The mass public is primarily con- the admittance of compactor trucks, the cerned with collection. Almost all of the city was forced to close the plant after contacts between the public and municipal only 6 weeks of operation. The closing re- solid waste managers involve collection sulted in a $2^ million loss by the City to problems. A public official who is re- the company which had contracted with the sponsive to his constituency finds himself City to build and operate the facility. responding primarily to collection difficulties. The only interest the mass 2,2 FACTORS DETERRING CHANGE public has in disposal is making sure that disposal (primarily landfill) does not take 2.2,1 COST place in his neighborhood. The collection and disposal of munici- 4. The preoccupation of both public pal refuse is a regular and constant re- officials and the mass public with the day- sponsibility. Furthermore, it is a respon- to-day problems of collection is one rea- sibility ordinarily assumed by local govern- son why so little effort goes into innova- ments, and as such is the object of public tions in disposal or in long range planning. interest and scrutiny with respect to the cost of collection and disposal service. Additional factors tending to discou- Public opinion generally favors the least rage planning and innovation are uncertain- expensive acceptable mode of municipal ty about: service provision. The political problem facing cities is deciding which method of 1.. System cost: The Houston Texas, disposal is publicly acceptable. However, Holmes Road incinerator cost over $6 million as will be discussed later, reliably esti- and was shut down after only a few years of mating the costs of alternative disposal . operation because of frequent equipment and systems is also something of a problem. air pollution problems. The cost of disposal at the facility during its final Aesthetic, public health, and environ- year of operation was about $29 per metric mental considerations have resulted in the ton ($26 per ton) in operating costs alone. banning of open dumping. Although inexpensive, open dumping is unacceptable. 2. System reliability: Garbage is Gradually, communities are being brought collected regularly, and must be dealt with into compliance, switching from open dumps on. a continuing basis. Many innovative to landfills or incineration. These latter disposal systems have been proposed (e.g. two disposal methods are more expensive : pyrolysis, anaerobic digestion, resource than open dumping, but do not have the so- recovery, etc. ) but they are yet of un- cial and environmental liabilities of known reliability. The fact that MMR must dumping. The costs of landfill and in- be disposed of continually puts a political cineration are rising in most areas as land- premium on system reliability. A city fills must be located in more remote lo- cannot suspend garbage services for a few cations and as existing incinerators must days or.weeks while repairs are effected be modified to meet current air quality on some exotic new disposal system. standards. In spite of this, landfill is generally less expensive in most locales 3. Public acceptance: Long range than any other acceptable disposal system-. planning and innovation depends on public cooperation. The location of future dis- Many new disposal systems have been posal sites is an important aspect of long proposed which would incorporate energy range planning. However, the selection of and resource recovery from municipal re- disposal sites is inherently a political fuse. However, there are no "hard" cost process. Planners may choose a disposal estimates for these processes, and ex- site on a number of important criteria, perts often disagree as to probable costs. e.g. geological suitability or geographic Those cost data which are available indi- proximity. But if a landfill site cannot cate that, in general, new disposal tech- be used because of political pressure from nology will be more expensive than land- neighborhood residents, then such planning fill or incineration without energy re- is useless. Neighborhood opposition can covery. Most communities will resist con- often be reduced by making commitments for version to new disposal systems, and will future park and recreational utilization of continue to landfill or incinerate until completed landfills, but this must be done the new technologies have more favorable on an ad hoc basis at the time a new dis- proven cost and operating reliability. posal site is brought into service. However, it should be kept in mind that disposal system costs are extremely lo- Innovative disposal systems are also cation dependent. A community which has subject to the vagaries of public acceptance. high landfill costs, high energy costs, and good local markets for secondary re- handle every aspect of production from the sources may find a new disposal system growing of trees through the final fabri- •(e.g. resource recovery and pyrolysis) to cation of finished paper products. Because be the least expensive alternative. This of this, pulp and paper mills tend .to be can only be determined by a careful analy- located near the areas where trees are sis of the needs and resources of each in- grown. A change in solid-waste practices dividual community. In general, however, such as the source separation and recycling until the economic superiority of a new of paper is impeded by that pattern of capi- disposal system can be clearly demonstra- tal investment because paper and pulp mills ted, decision makers will have little choice are somewhat distant from the urban areas but to continue existing disposal practices. which would be the main source of recycled paper. 2,2,2 MAINTENANCE OF POLITICAL STABILITY We must also consider the lobbying effort of many industries. As is discussed in another portion of this report, current Politics is the authoritative allo- practices are motivated by such political cation of valuables. Political decisions decisions as depletion allowances, capital are generally evaluated in terms of the gains tax provisions, differential trans- marginal advantages and costs to the mem- portation rates, etc. Representatives of bers of the political system. For that various industries may lobby against change reason a"ny change in an existing policy in order to preserve existing patterns of changes the distribution of costs and bene- industrial organization and investment. For fits, disrupts the political equilibrium of example, it is not implausible to expect the the'status quo, and awakens an otherwise Glass Container Manufacturers Institute to disinterested public. This is particularly oppose national deposit container legisla- true of policies which affect people's tion which would shift beverages from dis- everyday

The time-honored method of disposing in some cases because no other economi- of municipal solid waste was simply to cally or politically acceptable alternative haul it a short distance .from town and exist. Although open dumps are not di- dump it.on the ground. There, it may have rectly affected by Federal regulations, the remained in the open air, or it may have EPA has vigorously supported efforts to .been burned, or mixed with soil in a land- establish land-disposal regulations on the fill. Current waste-disposal practices state, county, and municipal level. Mis- are not much different; about 80 percent of sion 5000, a Federally sponsored publicity all municipal refuse is still, put into the campaign of the late 1960's, had as a goal ground. This method always p'resents the the closure of 5000 open dumps. The drive potential of pollution to both air and had some success, and open dumps have be- water. However, carefully planned and come more socially unacceptable. However, managed landfill sites can significantly without uniformly strong land-disposal re- reduce this potential hazard (ref. 2-3). gulations backed by enforcement, open dumps will be difficult to eliminate com- The two methods of land disposal in pletely because they are the cheapest dis- common use are open dumps and sanitary land- posal method. fills. Open dumps pose many pollution ' i. problems and deserve the name "environ- Sanitary landfills represent an im-v~ mental insult" which has frequently been provement over open dumps, although pla-• applied. Trash in open dumps is usually gued by the same potential hazards asJ burned, either accidentally or intention- open dumps. However, if site selection, ally. In any case, the burning contributes based on geologic and hydrologic criteria, to air pollution arid frequently violates is coupled with sound 'engineering prac- Federal and local air quality standards. tices , pollution may be kept to a mini- Open dumps provide a perfect home and mum (ref. 2-3). In a sanitary landfill, breeding place for disease-carrying ani- waste is spread.in thin layers and com- ' mal and insect pests (ref. 2-6). Examples pacted and covered with a layer of soil. of at least 22 human diseases, including This process is repeated as many times as hepatitis, have been linked to improper the area to be filled permits. Although waste-disposal methods (ref. 2-7) . the operation of any landfill will be influenced to some extent by the quantity Production of methane gas through and composition of refuse to be filled, 'an the decomposition of organic waste is an earth cover of at least 15.2 centimeters additional hazard, particularly if the (6 inches) of compacted soil should be gas is allowed to accumulate. More re- provided at the end of each day of opera- cently, the possible commercial exploita- tion. This cover will aid in rodent and tion of methane from landfills may turn insect control as well as help eliminate this liability into an asset (see discus- odor and blowing refuse. Unfortunately, sion elsewhere in this report on the NRG too many sanitary landfills are more cos- NuFUEL Company methane recovery program) metic than sanitary. (ref. 2-8). For a landfill to be truly sanitary Surface water can be directly pol- it must not pollute water supplies now or luted by runoff from open dumps of organic in the future. Pollution of surface water and inorganic material. If the bottom of by runoff is relatively easy to control by the dump extends below the local ground- proper design and by artificial drainage water table, internal leachate can also with leachate removal if necessary (ref. pollute subsurface water (ref. 2-9). Odor 2-3). Subsurface water pollution may be and wind-blown paper from open dumps are more difficult to control; frequently, it more of a nuisance than a serious pollu- is not apparent from surface evidence tion problem. However, these latter may (ref. 2-11). The pollution of subsurface be a major concern to residents of the sur- waters by material landfilled in an im- rounding area. properly located site may not occur until many years in the future. A recent ex- If open dumps are so undesirable, why ample of human poisoning in Minnesota in then do they continue to be the single 1972 occurred after several people drank most common important method for disposal well water which had finally become con- of municipal solid waste? Land disposal, taminated by arsenic wastes buried 30 per se, is not regulated in most' parts years before on nearby land (ref. 2-12). of the United States. Where regulations do exist they are frequently not strongly In addition to proper site selection, enforced (ref. 2-10). In most areas, how- .a successful sanitary landfill needs con- ever, open dumps are directly or indi- tinuous maintenance, including the moni- rectly illegal because of air and water toring of pollutant levels of leachate, pollution regulations as well as local even after the site.is completely filled. sanitation laws (ref. 2-11),. In spite of Subsurface water pollution will result if this, offending open dumps cannot be closed landfill substrata are permeable and the groundwater table is low. lethal material. For example, anaerobic bacteria can convert inorganic mercury Leachate is produced within a land- into more toxic methyl mercury (ref. 2-12). fill whenever water, from any source, re- Other materials generally considered safe acts with refuse. All landfills produce can also present a pollution hazard. "In- some leachate (ref. 2-13) . The compo- ert" incinerator residue is usually land- sition and strength of the leachate will filled. This material consists of metal depend on a number of complex factors, oxides incorporated in- a vitreous frit including the composition of refuse in (ref. 2-16). These metal oxides may be re- landfill, the amount of infiltrated water, moved when they come in contact with aci'dic and the length of time infiltrated waste leachate in a landfill. However, it will is in contact with refuse. The pollution take more time to leach this material than potential of a landfill depends on the mo- organic refuse. bility of contaminants and the accessi- bility of leachate to the groundwater re- Many existing landfill sites were se- servoir. In part, pollution potential may lected because of low real estate values be partially dependent on climate. Land- or political considerations rather than ap- fills in areas with high rainfall are more propriate geological criteria. Improperly likely to pollute than those in dryer areas. located sites will require remedial modi- In fact, landfills in very dry areas pre- fication to comply with existing and future sent almost no pollution hazard because regulations. Ideally, the substrata of a all infiltrated water is either absorbed landfill should have a low permeability and by refuse or is held as soil moisture high water-holding capacity and should be which ultimately evaporates. as far from an aquifer as possible. Clay- rich substrata usually make very secure Leachate from landfills contains sites for sanitary landfills. In many both organic and chemical contaminants. areas, intense competition for land among Organic material consists of suspended agricultural producers, suburban developers, material and bacteria. Sandy and silty and other interests has driven up land soils will retard the movement of organic prices and led to the utilization of aban- material, and often filter them from per- doned sand and gravel pits for disposal colating leachate (ref. 2-14). Chemical sites. This method is less expensive since contaminants, because they are in solu- land values are usually lower and exca- tion, usually travel faster and further vation costs are eliminated. Unfortunately, .than biological contaminants. The major these sites are likely to pollute subsur- decomposition products of refuse are car- face waters because of the high permea- bon dioxide and methane. Methane, since bility of sands and because of the frequent it is insoluble in water, does not con- direct communication of this type sandy tribute to water pollution. Much of the substrata with local shallow aquifers. carbon dioxide may be dissolved in the water which has infiltrated the landfill. The pollution problems associated This resulting weak carbonic acid can then with land disposal are severe and should react with carbonates, sulfates, chlorides, lead us to discontinue the use of this and silicates present in both the refuse method of waste disposal, except in certain and enclosing soil and rock units. At limited instances. However, in high den- best, this process of higher mineraliza- sity population areas, more pragmatic .tion can lead to increased water hardness. reasons such as land shortages or exces- At worst, this process may result in the sive land costs may provide the motivation introduction of toxic metal compounds in- to explore new disposal methods. Land- to subsurface waters. filling consumes about 2 acres of land per year for each 10,000 people when the com- What harmful chemical materials are pacted refuse in the fill is 2.1 meters commonly found in municipal waste? There (7 feet) deep (ref. 2-14). At this rate, is always a possibility that small quan- a city with a population of one million tities of very hazardous exotic material people will use 100 acres of landfill a will get into the municipal waste stream. year. This quantity of land is frequently Household chemicals for cleaning and gar- just not available in areas surrounding dening, pigments, and solvents are fre- the nations' larger cities. Or if land is quently toxic and found in small quantities available, it frequently has geologic and in refuse. Toxic substances may also be hydrologic parameters which make it unsuit- produced during the bacterial degrada- able for land disposal. tion of food wastes, especially from meat and fish (ref. 2-15). Chemical and biochemical reactions within a landfill are 2.3.2 OCEAN DUMPING complex and this is an area that requires more research. However, we do know that the decomposition of refuse is continually Ocean dumping has been used for many releasing intermediate products which are years as a disposal method for a wide va- soluble and toxic, whereas the primary pro- riety of industrial, military, and munici- duct was not. Organic activity can also pal wastes (ref. 2-17). Although municipal increase the toxicity level of originally waste made up the smallest amount of material that was ocean clumped, the total to air and water pollution as well as to tonnage continued to grow in the late 1960's general environmental deterioration. and early 1970's. Due to increased restrictions on air and fresh water pollu- Prior to 1960, there were few laws tion and because of scarcity of new land- dealing specifically with the preservation fill sites, cities found sea .disposal in- of the environment (ref. 2-20). However, creasingly more attractive for both econo- even then some of the nation's streams and mic and practical reasons. By 1971, a num- lakes had become unfit for recreation and ber of major seaboard cities (New York, San were unable to support many desirable forms Francisco, Boston, and Philadelphia) had of fish and plant life. Public awareness either initiated or had shown interest in of pollution came first in the area of various schemes for sea disposal of both water and air pollution. One of the first loose and baled garbage. Disposal costs environmental regulations was the Atomic were cheap, averaging approximately $3.00 Energy Act of 1954 which regulates the per ton (ref. 2-18), and in most areas re- safe disposal and storage of radioactive gulations were not restrictive as long as wastes. In 1955, a study of air pollution disposal practices did not produce ocean or was initiated at the Federal level by a beach blight. In most cases, the overall ef- $1 million appropriation to the Public fect of garbage to the marine environment Health Service. The following year, the and its biota was not considered. Federal Water Pollution Control Act was, passed authorizing a 5 year, $250 million Ocean dumping regulations were adminis- dollar program to aid in the construction tered by a wide range of Federal, state, of municipal sewage treatment plants. . and local agencies with little or no atten- These laws represent the only major pieces tion given to long-range planning (ref. 2- of environmental legislation of the 1950's. 18). Frequently, regulations were not comprehensive and little interagency coordina- Environmental legislation in'the . ". tion took place, resulting in overlapping early 1960's continued to emphasize air .' duplication, and confusion. As a conse- and water pollution. In general, these , quence, little reliable data exist today on laws were regulatory, although most of the total amount -and types of materials them also provided research, and grant dumped in the oceans before 1972. monies. In 1960, the Surgeon General began a study of air pollution by automo- Widespread ocean dumping ceased with biles which resulted in 1968 in the first the passage of the Marine Protection, Re- automobile emission standards. search, and Sanctuaries Act of 1972. This law prohibits.ocean dumping into the terri- In 1961, the Federal Water Pollution torial waters of the United States of any Control Act was extensively amended;'en- agent of warfare (radioactive, chemical, or forcement was placed under the direction., biological), high-level radioactive wastes, of the Surgeon General. Funding was in-' or any other material, except as authorized creased to $100 million dollars a year and by Federal permit issued by the EPA or by regulations extended to include navigable the Corp of Engineers for dredged spoil. as well as interstate waters. The emphasis Before granting any permits for ocean on pollutant-free air was continued by the dumping, the EPA must evaluate "appro- passage of the Clean Air Act of 1963. priate locations and methods of disposal This law provided the first federal abate- or recycling, including land-based alter- ment procedure in cases of interstate air natives, and the probable .impact (of such pollution, and provided additional money use) upon considerations .affecting the for research and technical assistance. public interest". The prohibition on ocean The Clean Air Act of 1965 revamped and dumping does not affect a large percentage expanded the air quality programs and es- of the nation's municipal solid waste. It tablished additional emission standards. does displace large volumes of industrial In 1966 and 1967 the Clean Air Act was wastes for landr-disposal sites, which in again amended and its funding for research turn increases pressure for new technology and grant programs was greatly expanded. in solid waste-disposal. The 1967 amendments are of particular importance because they provided air quality control criteria, air quality control re- 2.3.3 REGULATIONS RELEVANT TO SOLID WASTE gions, and a mechanism for Federal action if states failed to act.

Increased post World ,War II production A major piece of water pollution le- and consumption have resulted in an alarming gislation. The Water Quality Act, was also growth in the nation's solid waste. In passed in 1965. This act created the Fe- 1973 the United States Conference of Mayors deral Water Pollution Control Administra- of the National League of. Cities (ref. 2-19) tion and placed its administration under estimated that the volume of solid waste the Department of Interior. Most important, generated in cities had doubled in the pre- the act authorized mandatory standards for ceeding 20 years. This increasing amount interstate water quality. The Clean Water of solid waste has significantly contributed Restoration Act of 1966 authorized a massive

10 increase in Federal funds to clean up the The Clean Air Act of 1970, as amended, nation's waters. The bill provided money provided new air pollution abatement regu- for the study of estuary systems and it relations and has had a great effect on in- Amoved funding ceilings for communities dustry. The act established national pri- seeking aid in bringing water supplies up mary and secondary ambient air quality to Federal standards. standards for 10 specific .pollutants from any source, as well as setting more strin- Near the end of 1969, Congress enacted gent standards of performance for new sta- the National Environmental Policy Act (NEPA) tionary sources. Of particular signifi- which created the Council on Environmental cance to the area of solid-waste disposal Quality, a three-man executive advisory were the standards for new incinerators and board appointed by the president. The Coun- fossil-fuel fired steam generators. cil- was charged with responsibilities in four areas: 1) determining the condition The Federal Water Pollution Control of the country's environment, 2) developing Act (FWPCA) of 1970, as amended, provided new .environmental policies and programs, even more powerful water pollution regula- 3) coordinating all Federal environmental tions. The bill directed the EPA to es- programs between various agencies, and 4) tablish criteria and procedures for the insuring that all activities of the Federal adoption of Federal water quality stan- government take environmental considera- dards necessary to "protect the public tions into account. The performance of health or welfare". Initially the act re- this last function of the Council was as- quired the States to adopt waters-quality sured by regulations requiring all Federal standards and a plan of enforcement which agencies to prepare detailed environmental was consistent with criteria of the Fede- impact statements on "proposals for legis- ral act for interstate waters within their lation and other major Federal actions sig- jurisdiction. nificantly affecting the quality of the human environment", if deemed appropriate by The FWPCA amendments of 1972 extend the EPA. This requirement also applied to effluent limits beyond that required for •Federally funded demonstration projects and human health and welfare and will have ma- to contractors of the Federal government. jor implications. Essentially, the act If the EPA's preliminary determination was provides that by 1983 "the discharge of any that the proposed action was neither "highly pollutants by any person shall be unlawful". controversial" or had no "significant en- Pollutants are defined in the act as "dred- vironments effects", a "negative declaration" ged spoil, solid waste, incinerator resi- could be filed, stating that the agency due, sewage, garbage, sewage sludge, muni- would not prepare an environmental impact tions, chemical wastes, biological materials, statement. Public pressure has changed this radioactive materials, heat, wrecked or dis- decision in specific instances. Several carded equipment, rock, sand, cellar dirt, lawsuits brought by the local environmental and industrial, municipal and agriculture groups against the Federal Power Commission wastes". The act provides that publicly- have forced the preparation of environmental owned treatment plants will achieve this impact statements for proposed conventional effluent limitation by July 1, 1977, and power plants for which the EPA had filed an that other than publicly owned treatment earlier negative declaration. plants will achieve the limitations by July 1, 1983. The regulations further Congressional interest in solid waste state that the Administrator of the EPA lagged behind the concern for -abatement of must require the "best practicable control air and water pollution. It was not until technology currently available" to achieve 1965 that Congress passed the Solid Waste the 1977 limitations. Attainment of the Disposal Act. This law and amendments by 1983 limitations required "the application the Resource Recovery Act of 1970. initiated of the best technology economically achiev- Federal action in this rapidly growing pro- able which would result in reasonable problem area. Unlike Federal air and water gress toward the national goal of elimina- quality legislation, this law was not regu- ting the discharge of all pollutants". latory. Instead, it provided funding for research, development, and demonstration The wording of the law is sufficiently programs concerned with resource and energy vague as to raise questions as to what con- recovery from solid-waste. The Act set, as stitutes a "zero discharge" and to what ex- a national goal, the development of "new tent the regulations would be enforced. It and improved methods of collection, separa- is, however, strong enough that spokesman tion, recovery, and recycling of solid for industry have objected that the costs waste, and the environmentally safe dis- involved would be excessive. The Council posal of nonrecoverable residues". In- on Environmental Quality has estimated the itially the implementation of the Solid cost of this program from 1971 to 1980 Waste Disposal Act was a joint venture of would be $287.1 billion. Nelson Rockefeller the Departments of Interior and Health, Ed- has estimated the cost for zero discharge cation and Welfare. With the establishment in New York alone would be over $225 bil- of the U.S. Environmental Protection Agency lion dollars and in excess of 2 trillion (EPA) in December of 1970, the administra- dollars for the entire country (ref. 2-21). tion of this act and the Resource Recovery Act passed to the EPA.

11 2,3,4 ANTICIPATED ENVIRONMENTAL REGULATIONS of leachate on local surface water sys- , terns and plant and animal life. Vigorous enforcement of standards, where they exist, The EPA believes that-existing air and is rare and usually there are no rules water pollution laws are adequate. The which apply uniformly to both public and Clean Air Act of 1970, 'the Federal Water private operators. To be successful, all Pollution Control Act of 1970, and the Ma- land disposal sites must be controlled by rine Protection Research and Sanctuaries strong regulations backed by enforcement Act of 1972 and. amendments to each pro- powers. If strong nationwide regulations vided, if not the actual standards, the are not enacted, the problem will not be enabling mechanism to deal with emissions solved; it will be merely shifted from lo- of hazardous material into the air and cality to locality as individual units of surface waters from point- sources. How- government pass more environmentally de- ever, Federal, state, and local regulation manding standards. of the land disposal of-wastes may be charac- terized as either inadequate, incomplete, Going beyond standards for new land- or nonexistent. The lack-of land disposal fills, proposed legislation may require re- regulations coupled with increasingly more medial maintenance for polluting landfills stringent air and water pollution standards which have long been abandoned. In the fu- has increased the pressure on land dispo- ture, leachate may have to be removed from sal sites to accept more and varied wastes. the ground and sent through a water treat- This situation encourages the use of land ment plant, and offending solids dug up/ •; as the ultimate sink for harmful materials and removed. The final costs of todayVs which must be removed from air and water. supposedly cheap landfills may be paid In the absence of adequate controls, eco- some years hence. . nomic considerations have favored cheap disposal methods which are frequently the All currently known methods of energy most environmentally unacceptable, such as recovery, recycling, or disposal of solid.' landfills, injection wells, and surface waste produce at least some residue which- holding ponds. These practices are under- must be landfilled. For this reason,-an- taken at the risk of poisoning groundwater ticipated future uniform, environmentally; aquifers and adjacent bodies of surface sound land disposal methods should be con- water.* . - . sidered when planning any waste management system. Because of this problem, the EPA is seeking the authority to regulate land disposal, particularly the .disposal of ex- 2,3,5 ENVIRONMENTAL REGULATIONS SIGNIFICANT tremely toxic wastes. This proposed Hazar- TO ENERGY GENERATION FROM SOLID dous Waste Act of. 1973. would regulate the WASTE : transportation, storage,.recycling, detoxification and/or ultimate disposal of non- radioactive toxic wastes as a Federal- Any existing or proposed installation state partnership. While the proposed designed to recover energy from solid waste legislation would initially.affect waste will have to meet state-Federal air and . materials not ordinarily found in municipal water quality standards applying to any in- refuse, the EPA believes that the disposal dustrial plant. ' If the energy generating of municipal solid waste must also be con- process represents a hybrid between conven- trolled. Hazardous wastes'must be diverted tional systems and new "energy recovery from the normal municipal waste stream and from refuse technology", it may be subject treated under controlled conditions to in- to additional or unique combinations of ex- sure that no irreparable damage is done to isting regulations. the nation's health and environment. All energy generating sources, exis- In addition to the legislation al- ting or new, must at least meet Federal ready proposed, the EPA hopes to establish, primary and secondary ambient air quality within the next few years, minimum stan- standards regardless of their location. dards for the sanitary.landfill of non- Absolute minimum air quality standards will hazardous wastes. These standards would depend on the locality of an individual serve as a guide for legislation at the installation, since states are empowered to state level (ref. 2-22). Although some establish air quality regulations which are areas do have landfill standards, un- more stringent than the Federal standards. fortunately too many are based on aesthe- "Ambient air" refers to that portion of the tic considerations rather than pollution atmosphere which is external to buildings, hazards (ref. 2-11). Standards should be and jjo which the public has access. The based on the engineering properties of Federal act defines "primary ambient air enclosing rock and soil units, with a care- quality standards" as that quality which ful consideration of .the long-term effects is necessary with an adequate margin of safety, to protect public, health. It is "Numerous documented case studies are cited usually established as an annual average in the 1974 Report to Congress on Disposal weight of pollutant per unit volume of air, of Hazardous Wastes (ref; 2-12). per unit of time, or as maximum concentration

12 which may be exceeded not more than a set defined by Section 60 of the Clean Air number of times per year. "Secondary am- Act of 1970 as amended. Any facility bient air quality standards" are defined which is modified to change its method as the levels of air quality necessary to of operation is also considered by the protect the public welfare from known or Act to be a new 'stationary source. For anticipated adverse effects of a pollutant. most types of industrial..installations These are usually established as the maxi- this regulation does.not impose more strin- mum number of short-term high-concentration gent air quality standards unless the in- emissions which are allowable without ad- stallation is a new fossil-fuel fired verse effects on public health. Their pur- steam generator.,- incinerator, portland pose is to allow for occasional accidental cement plant,_nitric acid plant or sul- or emergency emissions within a system. furic acid plant. Both sets of standards are subject to revision at anytime by the EPA if additional Coal-fired steam boilers modified to information deems it necessary to protect burn both refuse and coal, such as the public health. prototype system operated by Union Elec- tric in St. Loui's, 'are considered new sta- 'The Clean Air Act of 1970 as amended tionary sources under the provisions of has established standards for 6 specific Section 60 of the Act mentioned above. pollutants which might be expected in emis- The St. Louis prototype, even though it sions from either an incinerator or py- is an EPA demonstration project, has en- rolysis plant. They are: sulfur oxides countered regulation problems because EPA (measured as sulfur dioxide), particulate has not yet decided if the hybrid system matter, carbon monoxide, photochemical oxi- should be classified 'as a new fossil- dents, hydrocarbons, and nitrogen dioxide) fuel fired steam generator or as a new in- (see Table 2-1 for details). Later amend- cinerator (ref. 2-24). Air quality stan- ments have set emission standards for dards are more stringent for new incine- other hazardous air pollutants, i.e. as- rators (see Table 2-2) than for new steam bestos, mercury, and beryllium, which boilers. The decision in this matter will would.not ordinarily be emitted from have a significant -'impact on the operating plants generating energy from refuse. Ad- costs of such plants. A final ruling ditional emission standards for other ma- clarifying this situation is required be- terials, i.e. hydrogen chlorides, other fore we would expect to see any additional acids, chlorine gas, flourides, polynuclear conversion of coal-fired to coal-refuse- organic compounds of a number of heavy me- fired boilers. tals which might be present in municipal 'refuse in quantities sufficient cause prob- Although the Clean Air Act specifi- lems, have been suggested, but have not yet cally defines more stringent emission stan- been promulgated (ref. 2-23). dards for new incinerators, no mention is made of pyrolysis plants. "Incinerator" If a new stationary source (defined as is defined as "any furnace used in the any new installation which emits any air process of burning solid waste for the' •pollutant) is planned, it must be designed primary purpose of reducing the volume of to meet "Federal emission standards of waste by removing combustible matter". performance of new stationary source" as This language might be interpreted to

TABLE 2-1 . NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS Levels not to exceed Pollutant Primary standard Secondary Standard Comments Sulfur Oxides 80 micrograms/m 60 micrograms/m Annual arithmetic mean , (measured as (0.03 pptn) (0.02 ppm) sulfur dioxide) 365 inter ogr eras /m3 260 raicrograms/nr Maximum 24 hour concentration not to be exceeded more than once (0.14 ppm) (0.1 ppm) per year. 1,300 micrograros/m Maximum 3 hour concentration not to be 'exceeded more than once per year. Particulate 75 raicrograras/m 60 microgroms/m . Annual geometric mean * Matter 260 micro grams /or 150 micrograms/m Maximum 24 hour concentration not to be exceeded more than once per year. ' l Carbon 10 railligrams/m3 Same as primary Maximum 8 hour concentration not to be 'exceeded more then once Monoxide (9 ppm) per year. . 40 milligrams/or Same as primary Maximum 1 hour concentration not to be exceeded more than once (35 ppm) per year. Photochemical 160 micrograms/m Same as primary Maximum 1 hour concentration not to be exceeded more than once .* Ox id ant a (0.08) per year. Hydrocarbons 160 micro grains An Same as primary Maximum 3 hour concentration (from 6 to 9 a.m.) not to be (0.24 ppm) exceeded more than once per year. Nitrogen 100 micrograms/m Same as primary Annual arithmetic mean 90.05 ppm)

Source: Reference 2-23.

*Reference methods for determining pollutant levels are described In detail In appendices to Part 50 o£ The Clean Air Act of 1970.

13 TABLE 2-2 STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES

Fossil-Fuel Fired Incinerators Steam Generators

Paticulate Must not exceed 0.10 Ibs. per Must not exceed into the Material million B.t.u. heat input atmosphere in excess of 0.08 g (0.043 g per 106j) maximum / s.c.f. (0.10 g./m9) correct- 2 hour average ed to 12% CO, maximum 2 hour average.

Visible Not greater than 20% None stated. Emmissions opacity, except that 40% opacity shall be permissible for more than.2 minutes in any hour..

Source: Part 60, The Clean Air Act of 1970 include pyrolysis plants, which produce gas, stringent than Federal regulations. 'Lo- oil or char by the incomplete combustion cal safety standards should be assessed of municipal solid waste. Since large- during the design phase of any new in- scale pyrolysis of solid waste is a rela- stallation. tively new technology (see Chapter 3), any installation would be new, and re- Certain aspects of worker safety and quired pollution control devices could health peculiar to the refuse disposal be incorporated into the initial system industry (i.e. the microbiological quality design. This would probably be much of air in .the work environment) do not simpler than upgrading pollution controls appear to be covered in existing regu- on a modified existing system, as was relations (ref. 2-25). Alvarez (ref. 2-26) quired on the modified Union Electric coal- has suggested that it is time for the refuse-fired steam boilers. waste-disposal industry to take a critical look at itself with respect to exis- All current state and Federal water ting OSHA regulations and proposed stan- quality regulations must be met by an dards . He believes that OSHA may target existing or proposed plant which gene- the industry for increased inspections and rates energy from solid waste.. No unique regulations because of the high injury water quality regulations are anticipated rate of municipal employees involved in for this type of operation. However, all the disposal of solid waste. plants must be able to attain a "zero discharge" of pollutants into any body of surface water by 1977 or 1983, depending 2.4 on whether the plant is publicly or privately owned. Internal environmental standards must also be considered for any existing A number of Federal laws and regu- or new energy or resource recovery system. lations discourage energy and resource These standards mainly concern the safety recovery from municipal solid waste. and health of employees. Virtually all While such policies do not prevent energy refuse disposal or refuse conversion in- , and resource recovery, they do give ad- stallations are subject to compliance vantages to the use of virgin resources with the rules and regulations of the which discourage the use of products made Occupational Safety and Health Act of from secondary materials. Examples of 1970 (OSHA). This Act covers a wide range these policies include freight rates for of industrial activities and regulates secondary materials, depletion allowances, general housekeeping, floor openings, rules of capital amortization, and Federal means of egress, noise, temperature, policies fixing the price of natural gas. personal safety equipment, sanitary facilities, and electrical safeguards. The Although it is unclear exactly how OSHA regulations, like most pieces of en- and to what degree policies such as these vironmental legislation, require that discourage energy and resource recovery, states adopt the Federal standards or they would seem to have sufficient im- • submit for Federal approval a plan of pact to warrant careful consideration. their own. State regulations may be more Each is examined in some detail below.

14 2A1 FREIGHT RATE POLICIES FOR VIRGIN sensitive to freight charges AND SECONDARY MATERIALS (ref. 2-27). The general conclusions of the EPA in It is not possible at present-to de- this matter are as follows: monstrate that higher freight rates cause an actual decrease in the amount of se- 1. Freight rates are higher for some condary materials; the cost of shipment secondary materials. Rail rates are higher is much higher than for equivalent vir- for scrap iron, glass cullet and reclaimed gin materials. It is difficult to pin- rubber and ocean rates higher for waste- point any one factor as responsible for paper . these differences in freight rates. Rate- makers allegedly take into account a num- 2. Freight rates represent a substan- ber of variables when establishing the tial fraction of the cost of using many cost of services. For example, such fac- secondary materials (scrap iron, waste- tors as weight, insurance costs, liability paper, glass cullet, and scrap rubber). to damage, combustibility, susceptibility to theft, ease of loading, excessive 3. While there is some potential for weight and length, and frequency of ship- discrimination, there is no direct evidence ment must be considered. The higher costs to indicate that higher freight rates re- for secondary materials, when compared sult in a reduction of recycling. with virgin materials, may be due to one or more of the above factors. Thus, 4. Further study is needed to de- higher freight rates do not by themselves termine the extent to which there is dis- .constitute proof of discrimination. Se- crimination against secondary materials. . condary materials may simply have distinctly different transportation characteristics which result in higher trans- 2.4.2 FEDERAL TAX POLICIES FOR VIRGIN portation costs. MATERIALS 'If, however, one compares the cost of shipment to the revenue generated A number of Federal tax policies give from virgin and secondary materials, benefits to industries engaged in the ex- "some interesting patterns develop. Iron traction of virgin materials. These poli- ore, when compared to steel and iron cies were originally established in 1926 scrap, contribute less revenue; wood to encourage the development of domestic pulp, when compared to waste paper, con- natural resources which were thought es- tributes more; glass sand, compared with sential for national defense. At the pre- glass cullet, contributes less; aluminum sent time, such Federal tax policies ap- ingots compared with scrap aluminum con- ply only to the extraction of natural or tribute more. When natural and synthetic virgin resources, and not to the same ma- rubber are compared with scrap and re- terial recovered from secondary sources. claimed rubber, scrap contributes less Thus, aluminum refined from natural ores and reclaimed contributes more than na- is covered by this policy but aluminum tural and synthetic rubber. recovered from solid waste is not. Ex- amples of these policies are discussed The EPA has attempted to determine next. freight rates as a percent of delivered price of virgin and secondary materials. It reports that: 2.4.2.1 DEPLETION ALLOWANCES For secondary materials of lower value, such as scrap iron, The depletion allowances on the ex- wastepaper, glass cullet, and traction of virgin minerals allow, an af- scrap rubber, the freight rate fected industry two options. It may opt is a substantial fraction of to deduct for tax purposes a portion of the overall delivered cost. For the investment cost of acquiring the mine- these materials, a significant ral deposit from the yearly gross income. adjustment of freight rates This is called cost depletion and is equi- could cause a significant price valent to methods of capital depreciation change; and, if the demand is used in other industries. On the other elastic, a corresponding change hand, the industry may opt to deduct each in consumption. These materials year a fixed percentage of gross income would be affected most severely generated. This is called a percentage by a discriminatory rate struc- depletion. The percentage allowed varies ture. For secondary materials according to the industry. In the pe- of higher value, such as alumi- troleum industry, the percentage depletion num and reclaimed rubber, the allowance is 22 percent a year. Clearly, freight rate is a smaller frac- a firm which may claim a tax deduction for , tion of cost, and consumption a portion of its gross income enjoys an would be expected to be less advantage over firms which may only claim deductions for actual capital costs.

15 2.4.2.2 EXPENSING CAPITAL EXPENDITURES 2.4.2.5 IMPACT OF TAX ADVANTAGES

In most nonmineral industries, capi- The four Federal policies (depletion tal improvements are not deducted from allowances, expensing capital expenditures, yearly income, but added to capital as- capital gains treatment, and foreign tax sets and recovered through yearly depre- credits) are examples of favorable treat- ciations. The mineral industries, how- ment of minerals industries. The question ever, enjoys a special rule. They may de- which must be answered is the extent to duct from current income the entire cost which these policies encourage investment of development of assets in the year the in virgin materials and discourage use of cost was incurred. This allows them to secondary materials. recover a major portion of invested capital even before the investment reaches The EPA in its Second Report to Con- the production stage. gress (ref. 2-27) attempts to estimate the total tax benefits from these four sources on a dollar per ton basis and total dollars. 2.3.2.3 CAPITAL GAINS TREATMENT These estimates are displayed below in Ta- ble 2-3. In most industries, any capital gains While these estimates do not determine received from._sale of property is subject the degree to which Federal tax policies to a maximum rate of 48 percent income tax. encourage investments in virgin material In the minerals industries, however, the and discourage investment in secondary ma- capital gains tax is reduced from the nor- terials they do point out the competitive mal 48 percent. The amount of capital advantage enjoyed by the virgin materials gains tax reduction varies according to industries. If the use of secondary ma- the industry. In the case of the timber terials is to be encouraged some conside'ra- industry, the tax is reduced to 30 per- tion must be given to equalizing this com- cent. Similar reductions are found in petitive advantage. other industries. FEDERAL POLICIES REGULATING NATURAL 2.4.2.4 FOREIGN TAX ALLOWANCES GAS

Industries doing business in foreign The Federal Power Commission (FPC)-; .countries can receive special tax conces-. regulates the transportation of natural gas sions under one of several programs. These in interstate commerce as well as "the sale special tax concessions have encouraged in- in interstate commerce of natural gas -for vestments in foreign mineral industries. resale for ultimate public consumption for Such tax concessions make foreign produced domestic, commercial, industrial or any minerals more competitive with domestic other use-, and. . .natural gas companies minerals. •> engaged in such transportation or sale"

TABLE 2-3 SUMMARY OF ESTIMATES OF TAX BENEFITS, 1970*

Total value Product Unit Value (millions of dollars)

Paper $0.899 per 907 kg (short ton) 37.75 Petroleum $0.350 per 0.159m3 (barrel) 1,350.00 Natural Gas $O.O-22 per 28.3m3 (10s ft3) 450.00 Iron Ore $0.748 per 1016kg (long ton) 96.64 Coal $0.142 per 1016 kg (long ton) 80.59 Bauxite (used for • aluminum) $1.496 per 1016 kg (long ton) 20.96 Sand (used for glass) $0.082 per 1016 kg (long ton) 0.86

•Adapted from: EPA, Second Report to Congress (ref. 2-27, p.33).

16 (ref. 2-28). This regulation covers about FPC policy requires utilities to give 60 to 70 percent of all natural gas con- priority to residential customers; ser- sumed in the United States. Gas produced vice to industrial customers may be cur- and consumed wholly within a producing tailed. Pyrolysis gas, as an intrastate state is not subject to the FPC regula- commodity, is not subject to this con- tion, while gas shipped to another state straint. is covered by this FPC regulation. One additional regulation should be The FPC regulatory power could af- mentioned. In some states the price of fect solid-waste energy recovery systems natural gas is set either by a state in two ways. First, the FPC has juris- agency or by cities through exclusive diction over the transmission of electri- franchises. In Texas, for example, cities cal energy in interstate commerce. Any set the price of natural gas sold to cus- organization which interconnects with a tomers within the city. In some cases the "public utility" transmitting electrical price established by city governments is energy into interstate commerce may come about equal to Federal price. Thus, in under the jurisdiction of the FPC. Thus, some cases even natural gas producing if a pyrolysis plant produces a gas, and states may have unnaturally low prices sells that gas to an electrical genera- which could affect the price of pyroly- ting system which comes under the juris- sis gas produced from an energy recovery diction of the FPC, that pyrolysis plant system. may also be subject to the FPC regulations (ref. 2-29). Additionally, if the pyrolysis gas were simply shipped into FEDERAL PROCUREMENT POLICIES AND interstate commerce rather than sold to THE SECONDARY MATERIALS MARKET an electrical utility, the pyrolysis .producing plant might be subject to FPC regulations. Since no large refuse py- One of the largest problems to over- rolysis plants have ever been built, come in recycling is that of market un- regulations in this area are uncertain. certainty. Market values of salvage- able goods and materials fluctuate greatly. The second FPC influence relates to Since the Federal Government is the single its price setting power. For a number of largest consumer of many products it has years, the FPC has set the price of na- been suggested that Federal procurement of tural gas shipped into interstate commerce recycled materials could be used to estab- at 34«. per 1.055 x 109 joules (106 BTU) . lish a stable market for products produced Recently, this price was raised to 46C from secondary materials. This has been pe"r 1.055 x 109 joules (106 BTU) on new done with paper products and rubber tires. production. This Federal policy may have an effect upon the price of any fuel gas The EPA has studied the effect of produced by the pyrolysis of solid waste. existing procurement policies and potential Federal policies on market demand This effect could take one of two" for secondary materials. They conclude forms. First, natural gas produced and that while the Federal Government is the used within a state (intrastate) is not single largest consumer of many products regulated by Federal price fixing policy it does not constitute, by itself, a suf- and the price of such natural gas•in pro- ficient portion of the market to create a ducing states has risen well above the demand for recycled materials (ref. 2-27) . -interstate Federal ceiling. In these State and local governments and other con- states, gas produced by pyrolysis prob- sumers must join the Federal government in 'ably could be competitively priced with the effort to create a market for re- natural gas. Second, in nonnatural gas covered resources. producing states, the price would be fixed by Federal regulation and pyrolysis gas Additional research funds to improve might not be competitive with the rela- recovery techniques and develop uses for tively cheap pipeline gas. However, in secondary materials could be provided by nonproducing states the supply of natural the EPA and other government agencies. gas has become increasingly uncertain and In Fiscal Year 1973, only four such grants often scarce because many suppliers are were issued by the EPA's Resource Recovery reluctant to sell at the Federal ceiling Technology program. Such research funding price. Thus, it is possible that pyroly- might have an effect similar to Federally sis gas might be priced above the FPC funded research to improve agricultural ceiling and remain competitive. Demand productivity. Long term benefits from re- for interstate natural gas exceeds avail- source conservation would provide the eco- able supplies. Many industries may ac- nomic justification for such expenditures. cept a higher priced pyrolysis gas in place of the lower priced, but unavailable, natural gas. Another competitive advan- 2.4.5 FEDERAL POLICIES ENCOURAGING "tage of pyrolysis gas is the possibility DEVELOPMENT OF RECOVERY TECHNOLOGY of contractually guaranteed supply. If a temporary shortage of natural gas occurs,

17 Until recently the technology related 2. Wet pulping to produce a to energy recovery from municipal solid fuel supplement with'poten- waste has been limited primarily to steam tial for fiber recovery. recovery through incineration. Twelve such systems are known to exist at the 3. Pyrolysis to produce 'gas or present time, four of which are newly liquid fuel. developed (ref. 2-27, p. 28). The primary drawback to steam recovery is the 4. Incineration to produce gas difficulty of marketing and transporting for turbine electrical gene- the product. In many cities, there is ration. simply no market for steam. 5. Biodegradation to produce Because of the market problems as- methane gas. sociated with steam, several new technologies are being developed to produce 6. Biochemical conversion to disposal systems which will generate produce glucose. more saleable products. Examples of these new technologies are discussed Today at least 18 cities have energy in detail elsewhere in this report and recovery systems under construction and 20 will not be discussed here.- They can be other municipalities are known to be evalu- placed into the following general cate- ating such systems (ref. 2-27, p. 41). gories : Six of these systems under construc- 1. Shredded waste as a fuel tion have been in part, stimulated by EPA supplement. Demonstration Grants (ref. 2-30). These are. summarized in Table 2-4.

TABLE 2-4 SOME ENERGY RECOVERY-SYSTEMS UNDER CONSTRUCTION

Funds City Process Federal Local

1. St. Louis, Shredded waste as Missouri coal supplement $2,580,026 $1,380,518

2. Wilmington, Shredded waste as a Delaware fuel substitute or as compost 9,000,000 4,760,000

3. Franklin, Ohio Wet pulping for material recovery 2,100,000 1,000,000

4. San Diego Pyrolysis to produce County, Calif. fuel oil 2,962,710 2,050,000

5, Baltimore, Md. Pyrolysis to produce gas to generate steam 6,000,000 6,177,000

6. Lowell, Mass. Incineration residue separation 2,384,000 793,000

Source: EPA, Second Report to Congress (ref. 2-27, pp. 91-97)

18 In addition to these programs, the physical conditions (e.g. low cost EPA also has funded several other demon- landfill sites) and unique local political stration projects of some significance. conditions may prevent the tapping of such These are summarized in Table 2-5. capital markets unless some additional Fe- deral fiscal incentives are provided. There is little doubt that these EPA grants have helped advance the "state of the art" of energy and resource recovery. 2.5 Further grants will probably be forthcoming under two bills presently being considered by Congress (ref. 2-31). While private capital markets may Disposal of municipal refuse has for provide the necessary resources to de- many years been the primary responsibility velop further energy recovery systems, of local governments. In the past, dis- the technical and economic uncertainty, posal was solved by open dumping and/or the lack of management and operational burning, but these processes caused health expertise at the local level, local and air pollution problems which forced

TABLE 2-5 SOME DEMONSTRATION PROJECTS OF SIGNIFICANCE

Project Process Funds

1. Combustion Power Incineration to produce $6,000,00.0 Co., Menlo, Calif. gas for turbine generation

2. Franklin Institute, Ballistic separator to 135,000 Philadelphia, Pennsylvania mechanically separate shredded refuse to recover paper fiber

3. Vanderbilt University High-energy electro- 435,481 magnetic separator to separate nonferrous metals

Source: EPA, Second Report to Congress (ref. 2-27, p. 98)

19 cities to turn to sanitary landfills and unproven technologies. In such areas incineration as alternate processes. both citizens and city officials do not More recently, Federal air pollution view solid waste as a problem of crisis standards and rising costs have forced proportions. If a city can continue to some local governments to abandon in- landfill for as low as $2.50 per 907 kil- cineration as a method of disposal. logram' (ton), suggestions for energy re- Other state and Federal standards are covery systems with estimated costs as closing landfills. Increasingly there low as even $4.00 per 907 killogram'(ton) is debate in Congress and elsewhere re- would be politically unacceptable. Until garding future hazards from existing some crisis develops (such as new environ- landfills. Additional regulations, mental standards on landfills which in- such as those proposed in the EPA's Re- crease the costs), cities will not view port to Congress on the Disposal of energy recovery as a viable option. Hazardous Wastes (ref. 2-12), may force the closing of other landfills. Another point of view frequently advanced is as follows: "Even though energy Thus, the present and possible future and resource recovery cost more, it is the closing of landfills and some incinera- 'right1 thing to do from an environmental tors are but two factors which are for- standpoint and it saves our limited re- cing, city governments to give attention sources". Although many persons would to the recovery of resources from mixed agree with that opinion it is difficult municipal refuse through either energy to sell politically. The average citizen generation or recycling. However, be- and some members of the scientific and '• fore either of these options becomes ac- technical community are as yet unconvinced ceptable to many local governments a that resources are limited. Until the number of very important political prob- limited nature of nonrenewable resources lems must be faced. This section examines becomes more widely accepted, energy and those problems. . resource recovery systems which cost more than conventional landfill methods will not be politically viable. In the mean- 2.5,1 NEW AND UNPROVEN TECHNOLOGIES time, any change in disposal technology will most probably result from pollution regulations and short run economic pres- Some city officials have expressed sures. reluctance to invest in multi-million dollar disposal plants of unproven technology and reliability. Reliability 2,5,3 PROBLEMS IN DEVELOPING AREA-WIDE seems to be the most important factor. ORGANIZATIONS FOR ENERGY AND The amount of refuse generated in a city RESOURCE RECOVERY is relatively constant, and any solid .waste disposal system must meet the "garbage" problem on a day-to-day basis. A 2.5.3.1 ECONOMIES OF SCALE NEEDED city cannot.stop collecting garbage for a week or two in order to iron out equipment problems. . • • . • Studies by the EPA and others have indicated that ift order' to have an ef- Additional reluctance has been ex- ficient .energy recovery plant at least pressed by city officials regarding the 453 metric ton/day (500 ton/day) of MMR lack of management and operational ex- must be processed (ref. 2-27, p. 39).' perience necessary for such disposal At the rate of 1.7 killograms (4 Ib.) plants. With technologies yet 'unproven per person per day* it would require a the skills necessary for operation are city with a population of 250,000 to also uncertain. .•-::.. •. • . • generate'453 metric tons. Only about : 20 percent of the total population lives Many city officials seem to be taking in cities containing populations of a "wait and see" attitude. If some of 250,000 or more, a total of 56 such ci- the processes being developed under EPA ties. There are 125 Standard Metropoli- Demonstration.Grants prove successful, . tan Statistical Areas (SMSA's) which ac- this reluctance 'will 'be overcome. How- count for 62 percent of the total U. S. ever, for'the present these new disposal population and have sufficient population technologies are' viewed with some skep- to generate the 453 metric ton/day of MMR ticism. . •'..'•'••',.• • ' .- •'.' heeded for efficient energy recovery. This means that in 69 SMSA's containing 42 -percent of the population, area-wide 2,5,2 NoNCRisisJnriTUDE OF CITIZENS AND CITY OFFICIALS *A1though each person in a household produces an average of 2.8 Ib. per ;l In areas where landfill is ,a ,rela- ;, . day of MMR,"total MMR, including com- tively cheap method of disposing of splid, mercial solid -waste, averages 1.7 killo- waste,' city officials are especially re- :grams (4 Ib.) per-person.per day. luctant to spend millions of dollars on

20 cooperation among the various governments special districts which could achieve in the regional waste shed would be ne- the minimum 453 metric ton/day necessary cessary for efficient energy and resource for efficient solid waste'are good. recovery. 2.5.3.3 POLITICAL PROBLEMS AFTER CREATION 2.5.3.2 POLITICAL PROBLEMS OF REOR- OF AREA-WIDE AGENCIES GANIZATION The potential political problems for Almost all SMSA's in the United States metropolitan area-wide disposal agencies have many units of government. They are lie not in creating such agencies but in "fragmented" into many small jurisdic- the decisions such an agency must make. tions, with no one unit responsible for Disposal site selection will remain a the entire metropolitan area. difficult problem and perhaps increase as proposals for large energy and resource The job of bringing these units to- recovery plants are forthcoming. However, gether to discuss an area-wide problem is, finding one or two sites for large ca- in itself, difficult; reaching agreement pacity disposal plants may be easier than is often impossible. Studies of inter- finding small landfill sites. governmental cooperatives indicate' that an agreement is most often achieved when Fledgling metropolitan disposal agen- (1) the issue has low controversey (such cies will undoubtedly experience a myriad as street numbering consistency), (2) of additional political conflicts. A there is little immediate financial cost dispute between Monroe County, New York, (such as mutual agreement pacts for ex- and local private haulers is a good exam- change of fire equipment in emergen- ple. Monroe County passed an ordinance cies) or (3) the issue has reached cri- requiring all solid waste collected in sis proportions (such as planning for the county to be dumped only at desig- an area-wide transportation system) nated disposal sites (ref. 2-33). This (ref. 2-32). To date, most coopera- was done in order to obtain the volume tive agreements by governments in metro- of solid waste needed to make the county- politan areas tend to be informal rather wide disposal facility profitable. Ob- than formal. This informality allows jections to this county ordinance have •local governments to withdraw at any been raised in a lawsuit by private col- time, thus reducing the usefulness of lectors and a disposal site operator. such agreements. Formal agreements are These private firms have been licensed often contractual in nature, subject to by the municipalities in the county under re-negotiation, and by no means per- the home rule ordinance power. Normally, manent . home rule ordinance power cannot be superceded by other governmental units in the The degree to which communities'in state. The private haulers contend that a small metropolitan area cooperate is the county has superceded the home rule also affected by the social, partisan, ordinance powers of cities by passing an and policy differences between communi- ordinance requiring dumping only at desig- ties in the 'area. If the communities nated areas. The county contends that differ in socio-economic status, have the municipalities have only licensed col- strong partisan differences, or pursue lection, not disposal, and that the home differing municipal policies, then the rule provision or the state constitution difficulty of reaching agreement is is not superceded. The case is pending in increased. court (ref. 2-34). Finally, the degree of cooperation Local decision makers should consider is also affected by the type of issue. this type of conflict as a potential prob- Local governments may cooperate on is- lem which might develop from the creation sues such as area-wide water and sewage of an area-wide disposal authority. Or- systems, but be unwilling to create an dinances or other laws restricting disposal area-wide school or police system. to designated areas should be carefully written and potential conflicts with muni- To what degree will local govern- cipalities and private haulers negotiated ments in a metropolitan area be willing in advance. to cooperate to create area-wide solid- waste management systems? A recent In the past, solid waste has not been study by the Advisory Commission on In- viewed as a resource but as a liability. tergovernmental Relations (ACIR) indi- In the future, solid waste may be viewed cates that area-wide cooperation on solid as a resource. If so, it will no longer waste disposal is quite promising. The be a "free good" which people pay to have issue, according to the ACIR, has no ad- removed, but a valuable resource which can verse social implications and a relatively be owned and sold. When this happens con- low inter-city conflict potential (ref. flicts will arise between government agen- 2-32). Thus, prospects for area-wide cies and private interests over the ownership of municipal garbage.

21 2,5.4 LACK OF PLANNING IN SELECTION A 'third advantage would be to pro- OF DISPOSAL SITES vide for solid-waste disposal sites before they are needed. Generally, most local governments do not begin to search for All solid waste disposal systems re- new sites until a crisis is reached. Long- quire land utilization. Regardless of range planning would avoid such crisis'de- the method of disposal used, the process cisions which are often not the best of all of disposal site selection has become in- possible decisions. creasingly difficult for a number of reasons, not the least of which is citizen Finally, if planning for solid waste protest. While all citizens want their, management disposal becomes an accepted solid waste picked up, few want the city part of the planning process, it would to put it down anywhere near their home. make it easier for an area-wide solid In the past the problem of site selec- waste management agency to develop and tion (generally for landfills or dumps) function. was solved by locating' such facilities in low-income areas. In recent years residents of low-income areas have begun to ob- 2,5,5 POTENTIAL PROBLEMS IN EXCLUSIVE ject to the location of disposal sites in FRANCHISES their neighborhood. At least part of the problem of citi- While exclusive franchises do not zen protest could be solved if solid necessarily create a significant problem waste disposal site selection were in- to pyrolysis energy recovery, they are- a cluded as a normal part of a comprehen-. problem which local decision makers should sive land use plan. Proposals for dis- consider during the planning stage. posal sites near residential neighbor- hoods may be viewed as a threat to pro- Traditionally state governments have perty values, a potential, health or en- allowed cities to grant franchises (con- vironmental hazard,, or a possible source tracts) to service corporations. These of danger due to increased truck traffic franchises may grant a company the exclu- in the area. If, however, the citizen " sive right to distribute a product such as were aware before he purchased his house natural gas, electricity, telephone, etc. of future planned disposal sites near to all residents of the city. While not his home he would have little recourse all franchises are exclusive, public util- for protest. ity franchises generally have this character. In addition to reducing citizen protest over site selection, there are a If a municipality grants an exclu- number of other advantages to including' sive franchise to a public utility, the solid-waste disposal sites as a- part of city government may decide to furnish its the comprehensive planning process. San- own services without conflicting with the ford M. Brown has suggested the following franchise. However, if a city decides to advantages (ref. 2-35): ; provide services to others, it may conflict with an exclusive franchise. Thus, First, disposal sites could be viewed if a municipality were to produce a py- as a "positive" land use rather than as-a rolysis gas from municipal refuse and sell nonconforming use. This might develop in- that gas to customers normally served by to a zoning category for solid-waste dis- a' natural gas public utility, the city posal. Brown suggested the following could be in conflict with the exclusive zoning categories: Solid-Waste Proces- franchise. It might then be necessary for sing-1 (SWP-1) to include recycling cen- a city contemplating such a system to re- 'ters, transfer stations, truck storage, negotiate the franchise with the natural truck repair and central storage areas; gas public utility. SWP-2 to.include composting plants, com- , mercial incinerators,'"'sanitary landfills; SWP-3 to include industrial incinerators, 2.5.6 LEGAL LIABILIT FOR PRODUCTS industrial landfills, municipal incinera- PRODUCED FROM tors, modified landfills; and SWP-4 to include hazardous waste disposal. A local government engaged in the Second, modified' landfilling sites conversion of MMR to some usable product (necessary even if energy recovery is will have to consider the problem of tort used) can be viewed as temporary only, ' liability. Local governments in the United with later conversion to recreation ; States traditionally have a limited tort areas. ,This would provide cities with liability when engaged in proprietary fun- an interim landfill.land use program. ctions such as operating public utilities. Areas that are not immediately useful Pyrolysis or resource recovery plants as recreation areas' could be landfilled would fall in this category. When engaged first and convertedTlater. in governmental activities, such as police

22 or fire protection, there is normally Lower capital costs result from items little or no tort liability because ci- 2, 3, and 4 above. Income tax exemp- ties are acting on behalf of the state. tions will lower operating costs. Re- duced zoning problems and exemption As an example of this problem, as- from state and local regulation may make sume that a local government produced the problem of site selection somewhat a pyrolysis gas, and sold that gas to easier than that faced by privately- an electrical generating company. In owned facilities. the burning of that gas by the electrical company some toxic substance was dis- There are also important disadvan- charged into the atmosphere causing death tages to public ownership of energy and or injury to individuals. Who would be resource recovery systems. One problem liable for this injury? Would the muni- is that no property tax revenue will be cipality (which produced the gas) or the derived from the facility. Local deci- electrical company (which burned the gas) sion makers will have to determine if be liable; or would they share joint lia- the loss of income from property taxes bility? Would this be covered under nor- can be offset by the decreased capital mal product production liabilities? A and operating costs which accrue from report by C. W. Morck, Jr. indicates that public ownership. in most states answers to these questions -are uncertain (ref. 2-36). Another disadvantage of public ownership is that local governments may Due to the heterogeneous nature of find it difficult to attract the personnel MMR, the risk of producing toxic sub- necessary to operate highly technical equip- stances in energy and resource recovery ment. Managerial problems associated with systems is plausible, and municipal of- the operation of such a system may be dif- ficials writing contracts for the sale of ficult for cities to overcome. products should consider this.* Customers may be reluctant to purchase such products Disadvantages to private ownership ' unless the local government retains some also exist. One disadvantage is related liability. to time limitations on contracts. Local governments are usually limited by state' law or local charters to contracts not to 2.5.7 FINANCIAL AND CONTRACTUAL OPTIONS exceed an established number of years. OPEN TO LOCAL GOVERNMENTS Five years is a common limit. Longer contracts are possible, but voter approval is often required. A private company may be A number of technical options are reluctant to invest millions of dollars in available to local governments wishing an energy and resource recovery plant if to engage in energy, and resource recovery it could be guaranteed a contract of no from MMR. In addition to the problem of more than five years. Obtaining voter ap- selecting the best technical option avail- proval for contracts of longer than five able to meet their needs, decision makers years may create problems for local of- must also consider the financial and con- ficials. However, such voter approval tractual options available. These options for long-term contracts may be no more relate to the question of public versus pri- difficult than obtaining voter approval vate ownership. Should municipalities own for capital bonds needed to construct pub- the recovery system or contract with a pri- licly owned systems. vately owned system on a fixed fee per ton basis? There are a number of advantages Another disadvantage of private ow- to public ownership. These include: nership is that it is difficult for a city to develop a solid-waste plan extending be- 1. Exemption from Federal and yond the time limits of a contract. Maxi- state income.taxes mizing planning time by entering into long- term contracts may lead to other problems. 2. Tax free bonds .• Solid-waste problems may change significantly in a very few years. Cities bound 3. Lower interest rates on bonds by a long-term contract may be unable to respond effectively to changing conditions. 4. Sales tax exemption on equipment purchases In addition to private or public ownership of refuse processing.facilities, 5. Fewer zoning problems cities in some states are allowed to issue publicly backed capital bonds for pri- 6. Exemptions from some state re- vately owned facilities. Under this op- gulations affecting site lo- tion, the local government raises needed cation capital by issuing revenue bonds backed by the credit of a private company. Such *For a more detailed discussion of bonds used to enjoy the normal.low inter- the possible dangerous substances which est rate and tax exempt status accorded could be produced from MMR see Section all state and municipal bonds. The pri- 2.3 of this report. vate company would repay the local unit

23 of government which in turn would repay will be preserved. (4) Energy demands the bonds. Ownership of the recovery sys- will be reduced because recycling is less tem plant would remain with the private energy intensive than virgin material pro- company and thus would be subject to production (ref. 2-27). perty taxes. Such a project would enjoy lower capital costs and produce property' £ We turn now to a discussion of two* tax revenue. At the same time the city types of legislation. First, we consider would be freed of the problems of manage- legislation to reduce, the amount of ma- ment and operation of the system. Due to terial in the municipal refuse stream. a recent ruling by the Internal Revenue In this category we will-discuss the re- Service, this option is not presently capping of tires and returnable bottles. available to cities. However, legis- Second, we examine legislation designed lation has been introduced into Congress to alter the composition of municipal re- which would change this IRS ruling. fuse and facilitate resource recovery. • In this category we consider bimetallic cans and low-volume potentially hazardous 2.6 .LEGISLATION TO REDUCE material. • • -• • 2:6.2 RECAPPING RUBBER TIRES 2.6.1 BACKGROUND In 1971 approximately 250 million The economy of the 20th century United car, truck and motorcycle tires were taken States has been an economy of affluence. - out of service in the United States.' • Of The nation was blessed with an abundance those tires, 46 million (2.8 percent) of resources and an entreprenurial spirit were recycled by rubber reclaimers, 2 which led to an exceptional capacity to million (0.8 percent) were consumed by produce and acquire goods. Changing pat- tire splitters, and 195 million (78 per- terns of consumption which equate increased cent) were dumped (ref. 2-27). consumption of goods with increased self- worth have made the solid waste problem ' Rubber tires are very difficult to more difficult each year. This, in turn, dispose of properly. They are not bio- has been compounded by the growth in the degradable. Whole tires cannot be ef- nation's population. Not only are people fectively compacted and buried in sani- consuming (and discarding) more now than ' tary landfills. When tires are landfilled they ever have, but there are more people they tend to work their way to the surface consuming more goods. and pop out of the landfill. Because of this, 'tires are often simply piled up in In less affluent times possessions large heaps at dumps, a practice which is were cherished, maintained, and handed not 'only unsightly, but'also provides down from generation to generation. Now breeding places for flies, mosquitos and the emphasis is on newness, novelty, and rodents. Tires can be shredded and then convenience. Our culture is :one which landfilled or mixed with other refuse favors trivial or useless products (e.g. and burned.* However, the high costs electric hog dog cookers), products which of shredding have tended to discourage ' are easily broken (e.g. most'plastic toys), both. . • products designed to be used and discarded (e.g. many ball point pens), products Much of the current tire disposal with designed obsolescence (e.g. American problem could be alleviated if tires were automobiles) and products which, when bro- retreaded rather than discarded. However, ken, are almost impossible to repair (e.g. as a percent of new tire shipments, re- many small domestic appliances). Two fac- treads have been declining.' In 1968 only tors would seem to indicate the need for 1-7 percent of automobile tires and 28 per- change in traditional .American values. cent of truck tires were retreaded. There First, energy and many^materials are be- are a number of reasons why a larger -pro- coming increasingly scarce and expensive. protion of tires are not retreaded.** Re- Second, solid-waste disposal costs are treaded tires have a poor public image. rising rapidly. For these reasons, legis- Retreads, regardless of quality, are per- lation is needed on product design so that ceived by many persons to be inherently (1) the.volume of material entering the inferior to new tires. This view may be waste stream is reduced by maximizing the. useful life of produc.ts and eliminating ~*Tires cannot be burned by themselves the manufacture of trivial products and in existing incinerators because-of air excess packaging, an4.~.(2) material en- pollution problems and because the fumes tering the waste stream can be easily re-, corrode and damage furnace walls. covered for reuse or recycling. Several types of savings will accrue from these **For a discussion of these points changes: (1) Collection, costs will be in more detail see 'Reuse and Solid Waste somewhat reduced. (.2) Disposal costs will Management, by Pettigrew, et al, (ref. be reduced. (3) Scarce material -stockpiles 2-37>.

.24 reinforced by some poor customer ex- site to dump site, reducing discarded perience from the 1940's and 1950's be- tires to shipable form. According to fore the retreading industry reached Smerglia (ref. 2-38) , some work is under its present level of sophistication, way on a mobile cryogenic destruction sys- or by the large number of separated tem for tires, but this is still in the tire treads which litter many interstate development phase and is not yet economi- highways. Retreaders generally try to cally proven. retread only the best grade of tires. Lower cost, lower quality new tires are eliminated rather than retreaded. How- 2,6.3 NONREFILLABLE BOTTLES ever, most new tire manufacturers make a bottom-of-the-line tire which sells in the same price range. Faced with a Although glass constitutes no more choice between a nationally advertised than 6 to 10 percent (by weight) of the and distributed bottom-of-the-line new municipal waste stream, discarded beve- tire and a brandless retread, consumers rage bottles pose'a serious litter prob- generally select the new tire, although lem (ref. 2-39). This is particularly the retread would be superior in quality. true of the nonrefillable types which have grown yearly in popularity with the Another problem limiting retreading beverage container industry since the is the fact that only about 35 percent 1960's. Because there is no monetary in- of discarded passenger tires are suit- centive for individual users to accumu- able for retreading. Most consumers al- late and return, or for scavengers to col- low their tires to become too worn be- lect nonrefillable bottles, many are dis- fore replacing them. Impact with road posed of in a haphazard and uncontrolled hazards and driving on underinflated manner along public roadsides. In 1969, tires also damage the tire carcass and the EPA estimated that 2.2 billion bottles render it useless for retreading. In- littered the nation's roadside.* Of these, creased consumer interest in using re- the majority were the nonrefillable types. treaded tires and better tire care habits Because glass does not decompose, road- would substantially reduce the number of side litter by bottles is cumulative. Lit- tires discarded each year. ter is also expensive to remove. In 1972 it cost an average of $45.00 per ton to . From a technical standpoint, the collect street litter (ref. 2-41). It has main impediments to high quality re- been estimated that, to collect a six- treading are variations in the type of pack of discarded beer bottles, a state rubber used in tire manufacture and size must spend $1.95, more than the full pack differences in the carcass and new tread. price itself! Both cause problems in achieving a permanent bond in retreads... • Government stan- Much of the litter problem is due to dards on the composition of rubber used the annual use of bottles. In the last de- in tires may be of some help. The prob- cade the use of glass beverage containers lem of tire sizing is somewhat more dif- has grown faster than either beverage con- ficult to resolve by regulation. Tires sumption or population, with the use of have a tendency to "grow" as much as 7 "throw-away" bottles growing much faster percent of original tire width after a than the returnable types (ref. 2-42). period of road use. This means that every The public may consider nonrefillable tire must be measured prior to retreading glass beverage bottles more a problem of and retreaders must maintain a very large litter and visual blight than an actual inventory of different size curing rims waste of resources. However, an exami- and other materials. nation of glass production figures for 1967 reveals that a significant, percen- If the problem of economically shred- tage of the (I. S. annual production was ding discarded tires can be solved, those discarded via the "throw-away" beverage tires which are unfit for retreading may bottle (ref. 2-39) . Over 33 percent of be used in the rubber reclaiming industry. all the glass produced in the country in Energy savings of up to 35 percent are 1967 went into the manufacture of bever- possible when reclaimed rubber is substi- age containers, the vast majority of which tuted for virgin materials in rubber fab- were discarded after just one use. Al- ricating (ref. 2-37). The key to increased though the raw materials of glass (quartz rubber reclaiming lies in finding a low sand, soda ash, and limestone) are abun- cost way to fragment or shred discarded dant and low cost, discarding this much tires. It is not practical to ship whole, glass annually represents a significant discarded tires; the volume to weight net energy loss. Annual replacement of ratio is too high. If tires can be frag- these throw-away bottles by an equivalent mented, then it becomes economical to quantity of new glass also contributes a ship the rubber. The picture is compli- significant amount of pollution. The EPA cated by the fact that discarded tires are collecting at a large number of dis- *For a detailed discussion of the persed dumping locations. A successful composition of highway litter, see re- shredder will have to be taken from dump ference 2-40.

25 (ref. 2-27) estimates that the production The top of the can is fabricated from of a ton of new glass requires 16 x 109 aluminum. These cans are not suitable joule (15.2 x 10e BTU) of energy and pro- for recycling because there is no eco- duces 174 killograms (384 Ib)-of mining nomically feasible way to separate the -wastes and 12.6 killograms (27.8 Ib) of. aluminum from the ferrous materials which air pollution, are gathered magnetically in most resource o. recovery systems. The aluminum is an un- J,o -Why has the use of the environmen- desirable contaminant in scrap iron and tally less desirable nonrefillable bottle steel and must be removed if the recovered continued to grow while the refillable iron and steel is to be recycled. The bottle could significantly reduce this State of Oregon has solved this problem problem? The answer lies in the profit by legislation prohibiting bimetallic, incentive in the glass container industry. beverage containers. If resource re- Nonrefillable glass beverage bottles recovery of ferrous metals from MMR is to present a huge potential market for glass become feasible on a wide scale, Federal manufacturers. This market has become in- legislation may be required to keep the creasingly more important in recent years bimetallic can out of the municipal solid as plastics and other material continue to waste stream. . be extensively substituted for containers which had traditionally been made of glass. ..Presumably, glass manufacturers would op- 2.6.5 LOW-VOLUME POTENTIALLY HAZARDOUS. pose the reduction or elimination of non- MATERIAL .refillable bottles which now account for much of the annual production of glass . container products. . A number of materials of great po-- tential danger to human health are rou- • : Three major methods have either been tinely dumped into the municipal waste initiated or proposed to control the lit- stream. Even though these substances oc- ter and waste associated with nonreturn- cur in small quantities, we cannot .afford able bottles. They are: (1) a mandatory to neglect them, particularly when -some deposit on all beverage containers, (2) are known to cause fatalities in labora- . the banning of nonrefillable beverage con- tory animals in relatively small amounts. tainers, and (3) a "litter tax" collected Certain plastics and fluorocarbon compounds, on each individual beverage container. as well as pesticides and their containers, Several states (Oregon and Vermont) and fall into this category. Existing and pro- •., -a number of cities have passed laws which posed legislation provides for special dis- require a deposit on all beverage con- posal treatment of the latter (ref. 2-44). . tainers, refillable as well as throw-away. Initial data on the Oregon, experiment sug- One of the greatest problems in this gest a marked decrease in litter due to area is the lack of sufficient data on the leverage bottles (ref. 2-43). The EPA toxicity levels of many of these materials. has extrapolated the data obtained from In most cases the reactions of these ha- these initial experiments. It estimates zardous materials during incineration and that Federal legislation requiring a 5C pyrolysis are unknown. deposit on all beverage containers would result in a 60 percent reduction of lit- Polyvinyl chloride plastics (PVC) „ ter (ref. 2-27). Resource and energy are representative of this particularly .savings would be significant. This type troublesome class of materials, and PVC of deposit would encourage the return of is a problem which has attracted consider- nonrefillable containers as well as the able public attention recently. It has refillable type. This, could be expected been claimed that this material releases to bring pressure on manufacturers for phosgene and hydrogen chloride on burning the complete elimination of nonrefill- (ref. 2-45). Experimental studies (ref. -able bottles. Repeated, handling of re- 2-46) find no evidence of phosgene, only £ fillable bottles.(with an average life . hydrogen chloride which has been implicated 'u" of 10-15 trips) is a labor intensive ac- as a major contributor of incinerator cor- tivity and would cost more than the one rosion. Presumably this material would be time distribution of nonrefillable bot- equally troublesome to a pyrolysis system. .tles. However, the net energy savings Based on these problems, suggestions have and reduced litter cleanup costs asso- been made to ban the use of PVC. A partial ciated with refillable bottles more than! solution to this problem is the research offset these increased labor costs. which is attempting to find PVC additives which would neutralize the hydrochloric acid as soon as it is formed during com- 2.6.4 BIMETALLIC CANS bustion. More, recent evidence now suggests that vinyl chloride may be a powerful car- cinogenic agent (ref. 2-47). If true, this Bimetallic cans, pose some serious is sufficient grounds for completely ban- problems for resource recovery from MMR. ning PVC. These are primarily, the familiar steel bodied "pop top" beverage containers. The dangers of such low volume potentially hazardous material in municipal

26 waste should be carefully studied. If Wider dissemination of this information shown to be dangerous, these materials could be expected to encourage energy, should be removed from the municipal recovery from refuse if the economics of waste stream by either restricting their such- a procedure are competitive with, use and disposal, or by a complete ban. current practices. Possibly, local en-- vironmental groups might serve as a means to disseminate this information. However, 2,7 ASPECTS OF SOLID any innovative system could be expected to encounter opposition if it poses the threat of additional cost or a change in lifestyle (e.g. source separation, changes-.in In this chapter we have explored the convenience packaging). . social, political, environmental, and legal aspects of solid waste which we be- Municipal refuse is usually a low lieve- would either encourage or discourage priority item with local decision makers; the implementation of energy generation their main concern is also the short- and'resource recovery. term problem of collection and disposal." In most cities, collection alone is a big Social and Political: enough job. Local-officials frequently do not have the time, funding, or manpower 'The social and political factors for long-range planning unless a local dis- which encourage or discourage energy and posal crisis exists. In addition, unless resource recovery are summarized in Table a crisis exists, any change from existing 2-6. Social attitudes and political prob- disposal methods may present an immediate lems are intimately interrelated and both political liability to elected officials. arek closely tied to cost factors. Citi- zen's ^attitudes are closely associated Although insufficient information with their degree of knowledge of the exists to generalize about local decision probleiQ of solid waste (which is in part makers' attitudes toward energy and re- ' locality dependent). Ordinarily, citi- source recovery from refuse, we have zens -do not think much about garbage un- found that local decision makers and less, of course, a collector's strike waste managers do demand certain require- finds them with a surplus of this com- ' ments of any 'waste-disposal system. First, modity. The average citizen's concern and most important, a disposal system with garbage ends at the curb. A nation- must be reliable and of proven technology. wide 'survey of metropolitan housewives Unproven processes co'uld only be expected revealed that over 30 percent of them to be implemented as pilot plants'in areas did not have any idea what happened to with acute disposal problems, and then their solid waste after it was collected. only as supplements to existing methods. Second, any disposal method (including energy recovery systems) must not cost TABLE 2-6 substantially more than current practices. SOCIAL AND POLITICAL FACTORS Environmental: ' • - ' - Encouraging Discouraging The environmental factors which en-- 1. Energy and • 1. Citizen attitude toward courage or discourage energy and resource resource solid waste problem — recovery are summarized in Table 2-7. En- shortages as noncrisis. vironmental constraints in the form of Fe- a solution » deral, state, and local regulations pro- to solid 2. Maintenance of politic vide a significant and immediate moti- waste dis- cal stability vating force to clean up our environment. posal - The underlying rationale for most environ- 3. Lack of comprehensive mental legislation has been a concern for 2. Concern on planning in 'selection public health. • Environmental regulations part of some s seek to minimize' or. eliminate the potential citizens re- •4. Resistance to change in health hazards that have been directly at- garding li- lifestyle, source sepa- tributed to pollution. mited re- ration, separate col- sources lection, disposal bot- Many past and some current waste dis- tles, changes in con- posal practices such: as open dumps, open 3. Pressure' venience packaging burning, and "unsanitary" sanitary land- from en- fills have made significant contributions vironmental 5. Reluctance to pay in- to air and water pollution. Present and groups < creased costs of al- pending regulations and restrictions of ternate disposal systems these methods, as well as air and water quality standards, all demand change from "dirty" waste disposal practices for muni- Although most citizens now believe cipalities and industrial concerns. The that we do have,an energy shortage—few legal constraints'to:~clean up our environ- are aware that technology exists to re- ment and the realization of a real energy cover energy from their own garbage. shortage are expected to be factors which

27 will encourage the development and implementation of processes to recover energy TABLE 2-8 'from solid waste. Any proposed instal- LEGAL FACTORS lation to recover energy from solid waste Encouraging will have to meet the same state and Fe- Discouraging deral air and water quality standards for 1. Federal de- 1. Federal freight rate emissions as any other industrial plant. monstration policies If the energy generating process repre- grants. 2. Natural gas regulations sents a hybrid between conventional sys- 3. Federal tax policies tems and new "energy from refuse tech- 2. Federal pro- 4. Tax free status of mu- nology" it may be subject to additional curement- , nicipal bonds used in or unique combinations of existing regu- Tpoligies' public/private systems lations . 5. Metropolitan area wide 3. Federal con- disposal systems needed siderations for efficient operation TABLE 2-7 fo'r; policy 6. Short term municipal ENVIRONMENTAL FACTORS changes in: contracts A. Freight 7. Exclusive franchises Encouraging Discouraging rates''. 8. Product liability as an B. Tax.poli- unknown 1. Present Restrictions Lack of en- cies •' 9. Lack of product design on landfills forcement of C. Tax sta- legislation to alter present air, ' tus of composition of solid 2. Ocean dumping re- water, land- bonds waste and encourage strictions-present fill standards le- resource recovery and pending Citizen atti- Federal freight rate policies have 3. Air and water stan- tude of un- long been known to discriminate against dards-present and limited re- certain categories of recycled material pending sources with respect to virgin materials. These policies are currently under review by 4. Limited nature of Public ig- the ICC, and those found to discriminate resources norance of against recycled materials will be con- environmental sidered for change. 5. Potential public problems health hazards of The secondary materials industry has current practices begun to lobby for more equitable policies in the areas of depletion allowances and special capital gains treatment which have long been extended to producers of Legal: certain, nonrenewable virgin resources. Policy changes advantageous to the se- The legal factors which encourage condary materials industry in both of or discourage energy and resource re- these areas 'of major concern, would be covery are summarized in Table 2-8. expected top stimulate indirectly the im- Among the legal considerations which plementation of more energy recovery an energy recovery plant should con- from refuse., sider are the problems associated with the ownership, marketing, and freight On, .the other hand, there are a num- rates of recycled resources. The eco- ber of Federal governmental factors which nomic viability of most proposed proces- tend 'to discourage energy and resource re- ses depends on the extraction of at least covery. The Federally fixed price of in- some secondary materials. In fact, it terstate natural gas may force any refuse- may be the credits for these recycled derived fuel to compete at an unnaturally goods that will make an energy recovery low price. (State and local fuel price system competitive with current waste setting may also have this same affect). disposal practices. Federal.tax policies which give advantages to virgin raw materials over recycled raw Federal interest in energy and re- materials will also have a detrimental ef- source recovery dates back to the enact- fect if not changed. ment of the Solid Waste Disposal Act of 1965, as amended by the Resource Recovery A recent ruling by the Internal Reve- Act of 1970. These laws established as nue Service that interest from municipal national goals the development of better bonds used by public/private partnership technology for the recovery of secondary systems are not income tax free may make materials and energy from solid waste. financing of proposed installations more More importantly, they provide Federal difficult. A number of local policies funding for demonstration grants and and laws also discourage energy and re- implement preferential Federal procure- source recovery. Among them are the ment policies for some goods manufactured following: from recycled resources. 28 1. The need to create area-wide dis- 3. Impose an excise tax on all vir- posal authority systems in order to supply gin resources used to encourage use of se- the 453 metric ton per day of refuse re- condary materials. quired tor efficient and economically practical energy recovery systems. 4. Implement governmental standards on product design and product reliability 2. Short-term contract limitations of products. (usually 5 years) imposed by many city charters may prevent the long-term ar- 5. Adopt deposit (Oregon) legisla- rangements required by many industries. tion for the beverage industry. 3. Exclusive franchises already 6. Establish disposability stan- granted by municipalities which may ham- dards for products. All products proper the sale of recovered resources. duced should have a disposal method. For certain products (e.g. automobiles, do- 4. Unknown legal status of product mestic appliances) it may be necessary to liability for products produced from re- set disposal taxes or bonds which would fuse may hamper the sales of these pro- be included in the original retail price ducts to industry. of the product. Table 2-9 summarizes our judgment as 7. Provide Federal grants-in-aid to the status of various disposal systems to communities to help establish solid with respect to the more important vari- waste management systems. ables which municipal decision makers must consider in accessing any disposal system. 8. Implement all present environmental standards relating to air, water, and landfills. Implementation of these 2,8 RECOMMENDATIONS standards would encourage the adoption of energy and resource recovery systems. To encourage resource and energy recovery from solid waste, we offer the following recommendations for change in existing policies. 1. Eliminate tax and freight rate advantages presently given virgin materials in order to make secondary materials more competitive and help conserve limited natural resources. 2. Subsidize research on resource recovery from solid waste.

TABLE 2-9 SUMMARY OF LEGAL, ENVIRONMENTAL, POLITICAL, SOCIAL, AND ECONOMIC FACTORS

AVAILABLE DISPOSAL ENVIRONMEN- POLITICALLY SOCIALLY CURRENT TECH- SOLUTIONS LEGAL TIALLY SOUND ACCEPTABLE ACCEPTABLE ECONOMICAL NICAL RELIABILITY

OPEN DUMPING NO NO NO NO YES HIGH

OPEN BURNING NO NO NO NO YES HIGH

OCEAN DUMPING By permit NO NO NO YES HIGH only "DIRTY" INCINERATION NO NO NO NO YES ' HIGH

POLLUX ION- FREE YES YES ? YES NO MEDIUM INCINERATION

SANITARY LANDFILLS YES May not be Not in many Many problems in Yes, in most HIGH soon. areas. site selection. areas. RESOURCE RECOVERY Yes with* YES Yes with Yes, with ? ? reservations low costs BIODE GRADATION- Y s with* YES , Site selection No, if ? ? COMPOSTING r servations problems odor problem

ENERGY RECOVERY Y s with* YES Only when Yes, with site ? ? r servationa economical selection problem SOURCE SEPARATION AND/ Y a with** YES No, potential No lifestyle YES Volume re- OR SEPARATE COLLECTIONS r servations campaign issue changes are covered not necessary reliable

*Before any resource or energy recovery system can become economically competitive with virgin materials Industries, a number of Federal Lows regulating freight rates and tax advantages must be changed. With solid fuel supplements for use in steam-fired generators a decision is needed regarding new versus old facilities from the EPA.

*"*Legal questions over who owns the resources separated at source: private haulers or city government.

29 SELECTED REFERENCES 2-14 Brown, L. F., Jr.; Fisher, W. L.; and Molina, J. P., Jr.: Evaluation of Sanitary Landfill Sites. Texas 2- 1 Bancroft, R.: America's Mayors Coastal Zone—Geologic and Engineer- and Councilman: Their Problems ing Criteria. Geological Circular and Frustrations. Nation's Cities, 72-3,.. Bureau Of Economic Geology, April, 1974, pp. 14-23. The University of Texas at Austin, 1972. 2- 2 Michich, A.; Klee, A.; and Britton, P.: National Survey of Solid Waste 2-15 Rail Transport of Solid Waste. Ap- Practice. Public Health Service pendix B - Background Information: Publication No. 1867, U. S. Dept. Control Measures for Public Health of H.E.W. and Environmental Control. NTIS-PB- 222 709, pp. 126-143. 2- 3 Brunner, D. R.; and Keller, D. J.: Sanitary Landfill-Design and Opera- 2-16 Kenahan, C. B. et al; Composition tion. (SW-65ts), EPA, 1972.- and Characteristics of Municipal 'In- cinerator Residues. U. S. Bureau 2- 4 Illinois Report Probes Citizen's of Mines, R. I. 7204, 1968. Attitudes on-Refuse Problems. So- lid Waste Management, Feb., 1974, 2-17 Smith, D. D.; and Brown, R. P.: An pp. 19t". Inventory of Marine Disposal of .( Solid Wastes. Proc. of National 2-5 Staff of National Analysts, Inc.: Industrial Solid Wastes Management Housewives Attitudes Toward Solid Conference, University of Houston Waste Disposal. EPA-R5-72-003. and Bureau of Solid Waste Manage- ment, March 24-26, 1970. 2- 6 .Hanks, T. G. : Solid Waste/Disease Relationship? A Literature Survey. 2-18 Gunnerson, C. G.: An Appraisal of Public Health Service Publications Marine Disposal of Solid Wastes off No. 999-UIH-6, 1967. the West Coast: A Preliminary Re- view and Results of a Survey. Paper 2- 7 Boggs, J. C.: Resource Recovery: presented at the 15th annual meeting The Now Dimensions in Solid Waste of the Institute of Environmental Management for the 1970's. Paper Sciences (Anaheim, Calif.) April 23, presented at National Industrial 1969, reprinted and distributed by Solid Wastes Management Conference, EPA. ' University of Houston and Bureau of Solid Waste Management, March 2-19 Cities and the Nation's Disposal 24-26, 1970. Crisis. Paper presented at the United States Conference of Mayors, 2- 8 Staff of the NRG NuFuel Co.: Sani- National League of Cities, March,. tary Landfill Methane Recovery Pro- 1973. . gram, company brochure, 1974. 2-20 Caseyj Bobs Recent Trends in Na- 2- 9 Schneider, W. J. : . Hydrologic Im- tional Legislation—For the .Total plications of Solid-Waste Disposal. Protection of the Environment. U.S.G.S. Circular ,601-F, 1970. Proc. of National Industrial Solid Wastes Management Conference. . Uni- 2-10 Hughes, G. M.; Landon, R. A.; and'. versity of Houston and Bureau of Faruolden, R. N.: Hydrogeology of Solid Waste Management, March 24-26, Solid Waste Disposal Sites in North- 1970, pp. 458-461. eastern Illinois.;1 (SW-12d), EPA, 1971. .,; . ' 2-21 VanVoorhis, F. S.: Environmental . Issues and the Communications Gap. 2-il DeGeare, T.: Thfe,'.New EPA Sanitary Resource Recovery, vol. 1, no. 2 Landfill Guidelines. A paper in: April/May/June, 1974. pp. 26-29. Sanitary Landfilling Conference, compiled by J. E. Delaney, (SW-5p), 2-22 Darnay, A.: Keynote address at In- EPA, 1973, pp. 76-80. ternational Waste Equipment of Tech- nology Exposition, National Solid 2-12 Staff of EPA: Report to Congress, Wastes Management Assn. (Houston, Disposal of Hazardous Wastes. Texas) June 25, 1974. (SW-115), Washington, D.C., 1974. 2-23 Baum, B; and Parker, C. H.: Plas- 2-13 Fungaroli, A. A.: Pollution of Sub- tics Waste Disposal Practices in surface Water by Sanitary Landfills. Landfill, Incineration, Pyrolysis, Vol. 1. (SW-12 rg), EPA, 1971. and Recycle. DeBell & Richardson,

30 Inc., Prepared for Manufacturing Contract Report to EPA (Washington, Chemists Association (Washington, D. C.), 1971. D.C.) 1972. 2-38 Smerglia, J. M.: Address before 2-24 Rosenbaum, C.: U. E. Trash Pilot 1973 Annual Meeting, ASME (Detroit), Plant Triples Air Dirt in Tests. Nov. 14, 1973. St. Louis Post-Dispatch, March 18, 1974, Section 1-12B. 2-39 Darnay, A.; and Franklin, W. E.: Salvage Markets for Materials in 2-25 Glysson, E. A.; Schleyer, C. A.; and Solid Wastes. Midwest Research Leonard, D.: The Microbiological Inst., 1972. (Condensation pre- Quality of the Air in an Incinerator pared by EPA as publ. no. SW-29 Environment. Paper in Resource Re- c.l in 1973.) covery thru Incineration, Proc. of 1974 National Incinerator Conference, 2-40 Bingham, T. H.; and Mulligan, P. R.: ASME (New York), May 12-15, 1974, The Beverage Container Problem; An- pp. 87-98. alysis and Recommendations. USGPO (Washington, D. C.), 1972. 2-26. Alvarez, R. J.: OSHA and Its Impli- .. cations for Incinerator Plants. 2-41 McFarland, J. M.; Brink, D. L.; Paper in Resource Recovery thru Glassey, C. R.; Klein, S. A.; • Incineration, Proc. of 1974 National • McGauhey, P. H.; arid Golueke, C. Incinerator Conference, ASME (New G.: Comprehensive Studies of Solid York), May 12-15, 1974, pp. 99-108. Wastes Managements. SERL Report No. 72-3, College of Engineering and 2-27 Staff of Environmental Protection School of Public Health, Univ. of Agency: Second Report to Congress, Calif. Berkely, 1972. Resource Recovery and Source Reduc- tion. (SW-122), Washington, D. C., 2-42 Claussen,. E. L.: Environmental Im- 1974. pacts of Packaging. No. 332, EPA, 1973. 2-28 Section l(b), Natural Gas Act, 1938, - as amended. 2-43 Claussen, E. L.: Oregon's Bottle Bill: The First Six Months. No. 325, 2-29 FPC vs Florida Power & Light Co. 404 EPA, 1973. U.S. 453, Jan. 12, 1972. 2-44 Staff of EPA: Pesticides and Con- 2-30 Section 208 of the Solid Waste Dis- tainers; Acceptance, Disposal, and posal Act, 1973, as amended. Storage—Proposed Rulemaking and Is- suance of Procedures. Federal Regis- 2-31 Senate Bills 3549 and 3560, 93rd ter, Vol. 38) no. 99, Part II (Wash- .Congress. ington, D. C.), May 23, 1973, pp. 13622-13626.. 2-32 Staff of Advisory Commission on Intergovernmental Relations: Re- 2-45 Heimburg, R. W.: Environmental Ef- gional Decision Making; New Strate- . fects of the Incineration of Plas- gies for Substate Districts. Vol. 1, tics . In Chemical Engineering Ap- A-43, 1974. plications in Solid Waste Treatment, Guy E. Weismantel, ed. A.I.Ch.E. 2-33 Solid Waste Management Law County of Symposium Series 122, vol. 68, 1972, Monroe, State of New York, Motion No, pp. 21-27. 47 of 1973, Effective Aug. 17, 1973. 2-46 Boettner, E. A.-; and Ball, G. L. : 2-34 Monroe" Livingston Sanitary Landfill, Combustion Products of Plastics and Inc., et al, v/s County of Monroe, their Contribution to Incinerator State of New York,' New York State Problems. Chemical Engineering Ap- Supreme Court, 1974. plications in Solid Waste Treatment, Guy E. Weismantel, ed., A.I.Ch.E. 2-35 Brown, S. M., Jr.: Advanced Planning Symposium Series 122, vol. 68, 1972, Critical in Establishing Effective pp. 13-20. ;- Land Use Management. Solid Waste Management, May, 1974, pp. 62-66. 2-47 Stellman, "J. M.; and Daum, S. M.: Work is Hazardous to Your Health. 2-36 Morck, C. W., Jr.: Legal Liabilities Vintage Books, 1973. for Contract Waste Disposal. Paper in Resource Recovery thru Incinera- tion, Proc. of 1974 National Incin- erator Conference, ASME (New York), May 12-15, 1974, pp. 237-243.

2-37 Pettigrew, R. J.; et. al.: Rubber Reuse and Solid Waste Management.

31 Page Intentionally Left Blank Chapter 3 Technical Aspects of Energy Recovery from Solid Waste

B'ODEQRADAT/0 INCINERATION?

COMPOST? ^ 3,1 INTRODUCTION open dumping, sanitary landfill, and incineration. There are many 'disadvantages associated with each of these alternatives, The use of solid waste as an energy and many of these have been discussed pre- source could provide a small percentage of viously. • - this country's total energy demand. Based on an energy content of solid waste of Not one of these methods is totally approximately 1.165 x 107 joule/kilogram acceptable as a solution to the solid (5000 Btu/pound) the energy from solid waste problem. Sanitary landfills are waste could provide a fuel equivalent to generally the cheapest means of disposing 25 percent of our annual consumption of of the solid waste. Consequently, systems natural gas or about 2 percent of our which recover energy from solid waste are current fossil fuel consumption (ref. 3- often compared to sanitary landfill costs 1). . On a more local basis, the energy and will probably have to compete econo- from a community's solid waste could be mically with landfill disposal methods to used to provide up to 20 percent of that be considered by many communities. The community's electrical power requirements. following is a discussion of sanitary land- Locally, the recovery of energy from solid fills and the economics of this waste dis- waste appears to contribute a significant posal method. These data may be used for amount to the total energy picture, but comparison with the costs of energy re- for many communities, the energy recovery covery systems discussed in later sections. will be a secondary advantage. The primary Incineration costs are discussed in the advantage will be the virtual elimination Midwest Institute Report,, (ref. 3-2), and of the solid waste disposal problem. will not be discussed in detail in this report. Energy recovery from solid waste is a relatively new concept, precipitated by the shortage of sanitary landfills in 3,1,1 SANITARY LANDFILL highly populated areas, by public concern over the location and presence of landfills, and to a lesser extent, by the Sanitary landfills receive the bulk recent energy crisis. The traditional dis- of the refuse generated in this country. posal methods are shown schematically in Close-in sites are usually the cheapest Figure 3-1. The three methods shown are means of disposal of Mixed Municipal

SOURCE PRE CONVERSION CONVERSION POST CONVERSION RAW FINAL MATERIAL PROCESSING PROCESSES PROCESSING PRODUCTS DISPOSITION

FIGURE 3-1 CONVENTIONAL METHODS OF REFUSE DISPOSAL

34 Refuse (MMR), but land is becoming less TABLE 3-2 -(Continued) available for disposal sites in large metropolitan areas. This means that remote disposal areas must be found. Re- Fixed Investment mote sites make the disposal cost of the MMR greater because of increased trans- Site Improvements ' $ 300,000 portation and time. The economics of a Structures 100,000 close-in and a remote sanitary landfill Equipment 350,000 are given in Tables 3-1 and 3-2 (ref. Transfer Station 1,000,000 3T2). Miscellaneous 200,000 Total Fixed TABLE 3-1 Investment • $1,950,000 TOTAL CAPITAL REQUIREMENTS FOR n CLOSE-IN SANITARY LANDFILL Recoverable Investment 907 METRIC TON/DAY (1000 TON/DAY) RAW WASTE INPUT CAPACITY Land $ 300,000 Working Capital 200,000 Amortized Investment • .Total Recoverable • i Investment $ 500,000 Engineering, R & D $ 114,000 Startup 83,000 Total Capital Requirement $2,817,000 Total Amortized Total Capital Requirement at: Investment $ 197,000 227 metric ton/day (250 Fixed Investment ton/day) Capacity $ 772,000 454 metric ton/day (500 Site Improvements $ 300,000 ton/day) Capacity $1,475,000 Structures ' 100,000 1814 metric ton/day (2000 Equipment i 350,000 ton/day) Capacity $5,380,000 Miscellaneous 200,000 *Landfill site located 100 miles from Total Fixed central refuse generation point. Investment $ 950,000 Recoverable Investment It may be seen that the disposal costs associated with a sanitary landfill vary Land $1,200,000 with the capacity. The disposal costs, Working Capital 125,000 however, range from $3.10/metrie ton ($2.8I/ ton) for 227 metric ton/day (250 ton/day) Total Recoverable capacity to $2.65/metric ton ($2.41/ton) Investment $1,325,000 for an 1814 metric ton/day (2000 ton/day) capacity, for the close-in disposal site. Total Capital Requirement $2,472,000 The costs for the remote landfill are Total Capital Requirement at: somewhat higher, ranging from $6.87/metric ton ($6.25/ton)to $6.25/metric ton ($5.67/ 227 metric ton/day (250 ton), depending on the capacity. These ton/day) Capacity $ 678,000 cost estimates for sanitary'landfill dis- 454 metric ton/day (500 posal are taken from reference 3-2, and ton/day) Capacity $1,295,000 may be considered typical costs. Local 1814 metric ton/day (2000 land, labor, and transportation costs could ton/day) Capacity $4,725,000 cause some deviation from these economic data.

TABLE 3-^2 TOTAL CAPITAL REQUIREMENTS FOR 3,1.2 PRE-CONVERSION PROCESSING ROUTES REMOTE SANITARY LANDFILL* 907 METRIC TON/DAY (1000 TON/DAY) RAW WAStE INPUT CAPACITY As an alternative to landfill or incineration of the raw refuse, some processing could be performed, either for the pur- Amortized Investment pose of materials recovery or simply for 'the purpose of rendering the refuse more Engineering, R & D $ 234,000 acceptable for sanitary landfill. If addi- Startup 133,000 tional separation, drying, and grinding steps are performed, a solid fuel could be Total Amortized obtained. These various routes are shown Investment $ 367,000 in Figure 3-2.

35 SOURCE PRE- CONVERSION CONVERSION POST-CONVERSION RAW FINAL MATERIAL PROCESSING PROCESSES PROCESSING PRODUCTS DISPOSITION

SIZE REDUCTION (VARIOUS PROCESSES)

SEPARATION (VARIOUS PROCESSES)

ADDITIONAL GRINDING AND DRYING STEPS FIGURE 3-2 PRE-CONVERSION PROCESSING ROUTES

Resource recovery systems are front- in 1972 (ref. 3-1). end or pre-conversion process systems which will recover metals, glass, and The newer incineration processes, with other useful materials. After recovery, energy recovery, are better designed and the remaining products in the MMR could should improve on all of the above negative either be landfilled or incinerated. characteristics of incinerators. Figure 3-3 is a schematic illustration of the possible incineration routes for energy recovery. 3,1,3 ENERGY CONVERSION ALTERNATIVES In general, they are direct incineration of refuse alone, and the use of refuse as a supplemental fuel. Materials recovery can If energy from refuse is desired, occur before or after the conversion pro- several conversion alternatives are cess, depending on the resources desired. available. The broad categories are:- A number of products are possible from the incineration conversion process, the most' 1. incineration important probably being steam. 2. pyrolysis- 3. biodegradation • 3.1.3.2 PYROLYSIS Each of these methods is:'discussed in the following sections.. Pyrolysis is defined as destructive 3.1.3.1 INCINERATION WITH ENERGY distillation, or thermal decomposition, with- RECOVERY out complete combustion. Figure 3-4 is a schematic illustration of pyrolysis conversion processes. Pyrolysis products may Incineration of refuse in this consist of storeable gaseous, liquid, or country, historically,1 has been plagued solid fuels, and resource recovery may with problems. The incinerators -polluted occur before or after the conversion process, the atmosphere with gaseous and solid again depending on the resources desired. participates, obnoxious odors, and unburned refuse; were expensive to operate; and were generally not accepted by the 3.1.3.3 BIODEGRADATION OF REFUSE public. Only a relatively small number (less than 200) of municipal incinerators Biodegradation conversion routes are ' were still in operation in the U. S. shown schematically in Figure 3-5. The two

36 ; INCINERATION RAW FINAL SOURCE PRE-CONVERSION CONVERSION POST CONVERSION PRODUCTS DISPOSITION MATERIAL PROCESSING PROCESSES PROCESSING

IF NO PRE-CONVERSION SEPARATION

FIGURE 3-3 REFUSE INCINERATION ROUTES WITH ENERGY RECOVERY

PYROLYSIS SOURCE PRE-CONVERSION CONVERSION POST-CONVERSION RAW FINAL MATERIAL PROCESSING PROCESSES PROCESSING PRODUCTS DISPOSITION

, FIGURE 3-4 PYROLYSIS OF REFUSE

37 BIODEGRADATION SOURCE PRE-CONVERSION CONVERSION POST-CONVERSION RAW FINAL MATERIAL PROCESSING PROCESSES PROCESSING PRODUCTS DISPOSITION

GAS (CH4) [| (ENERGY)

USEFUL" , .MATERIALS,/

FIGURE 3-5 BIODEGRADATION OF REFUSE broad categories are biochemical and biolo- son of the debits and credits that are gical conversion, and several products are associated with .each process. As a first possible, including gases, liquids, and step toward making uniform comparisons solids. and to give the reader a better apprecia- tion of the costs involved, Figures 3-6 and 3-7 have been developed which show the 3,1.4 PROCESS ECONOMIC DATA SHEETS major components of the costs and credits for available options. These tables reflect the various sources of data, and no A critical factor to be considered in attempt has been made to verify the calcu- the selection of any conversion process for lations, translate to a common year base, energy recovery is the economic aspect of common city, or other factors which would that system. A review of currently avail- alter the actual numbers. able information demonstrates the difficulty in obtaining reliable cost estimates for Figure 3-6 will be used to compile any of the energy recovery waste disposal the cost data in two major categories: methods. From a financial standpoint, the 1) capital cost and 2) operating costs. most important consideration to the con- Using this technique, all the costs which sumer is how much it will cost to dispose are primarily associated with the origi- of his solid waste? this cost can ultimately nation of the project are itemized under be translated into "dollars per ton". It capital costs, while continuing costs should be pointed out that the technology which occur on an annual basis are itemized of converting solid waste to usable energy under operating costs. A comment column is relatively new and currently there are is provided to allow a limited explanation few full production plants in operation in of the data to be given on the form itself. the United States. Hard financial figures are therefore available, and estimates It should be noted that all capital which are given necessitate many assump- costs are "totals" and must be amortized tions which are discussed elsewhere in or expensed before an economic study can this report. properly be made. The methods of cost presentation used The form shown in Figure 3-7 is used in the literature describing the disposal to collect information on the potential systems are almost as numerous as the income generated by the sale of energy and number of different processes; therefore, resources recovered from solid waste. The it is difficult to make a uniform compari- comment column is provided to allow a

38 Process Name: Data Source:' Capacity-in Tons/Day:

DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt Processing Eqrat Postprocessing . Eqmt Utilities Building & Roads Site Preparation Ehgr. & R & D Plant Startup Working Capital Misc.:

TOTAL

OPERATING COSTS ($ PER YR] Maint. Material Maint. Labor Dir. Labor Dir. Materials Overhead Utilities Taxes Insurance Interest Disposal of Residue Payroll Benefits Fuel Misc.:

TOTAL

CREDITS ASSUMED ($ PER YR)

FIGURE 3-6 PROCESS COST SHEET limited explanation of the data to be given Mixed Municipal Refuse (MMR) from its on the form itself.- Space is provided in source up to the stage where it is ready the left hand column of the form to intro- for conversion processing. In this reduce additional labels that more adequately port, however, the collection aspects describe a particular resource credit. The of MMR are not considered. total income per yjar at the bottom of the form should be transferred to the last line The content of MMR varies daily in of the Process Cost Sheet. a given location, -and even varies in different localities of the country. Re- fuse generally contains some moisture, and the rainy season drastically increases 3,2 PRE-PROCESSING TECHNIQUES the total refuse tonnage to be collected. Table 3-3 contains a "typical" composition of MMR, which may be used to deter- 3,2,1 GENERAL CONSIDERATIONS mine the amount .of .potential resources that may be recovered from refuse (ref. Generally speaking, pre-processing 3-D . includes all the steps of handling the Process Name:'

Data Source': Capacity in Tons/Day:

DOLLARS/YR. COMMENT

Fuel: Liquid Gas Solid Power: Steam Electricity Hot Water Magnetic Metals Nonmagnetic Metals • f Glass Ash Paper Other :

TOTAL ($ PER YR.)

FIGURE 3-7 RESOURCE RECOVERY DATA SHEET

TABLE 3-3 Standards Handbook H44. A 45 metric ton TYPICAL COMPOSITION OF (50-ton) capacity truck scale is quite MIXED MUNICIPAL REFUSE sufficient for the purpose. There are many manufacturing companies dealing in Percent by truck scales on the market. The approxi- Waste Component Weight mate cost of installing such a unit may. be about $38,000. The services of one Paper 33.0 person is sufficient to operate the scale Glass 8.0 and to maintain the records. Ferrous metals 7.6 Plastics, leather, rubber, textiles, wood 6.4 3,2,2 SIZE REDUCTION TECHNIQUES Garbage and yard wastes 15.6 Miscellaneous (ash, dirt, etc.) 1.8 The use of size reduction equipment Total Dry Weight 73.0 (i.e. hammermills; shredders, grinders, Moisture 27.0 etc.) is gaining acceptance as a prelimi- Total. 100.0 nary operation in processing solid waste. Two decades of experience and published data concerning the characteristics of It should be noted from Table 3-3 shredded refuse are emerging because of that the refuse typically contains a large the changing economic picture and environ- amount of moisture. Thus the amount of re- mental concerns associated with traditional sources actually present and recoverable, solid waste disposal philosophy. either in the form of materials or energy, is typically 70 to 80 percent of the as- Benefits of shredding can be realized received tonnage. by almost any kind of follow up process whether it is energy recovery, material Pre-processing should include a truck recovery, or landfill. Initially, shred- scale to weigh the material received for ding of refuse was used as an attempt to processing. The equipment itself includes increase combustion efficiencies for in- a concrete weighing platform, a weighing cineration processes and for the purpose device, and a recording mechanism. Appli- of composting wastes. Although incinera- cable accuracy and tolerance requirements tion and composting have only obtained can be found in the National Bureau of limited success (to be discussed in later

40 sections of this report) the following ad- problem with landfill, is sub- vantages of shredding have been noted as a stantially reduced. result of these operations: Since there are definite benefits 1. volume of refuse is reduced by that result from size reduction operations, about 50 percent/ it would be helpful to consider the various 2. refuse is more predictable and kinds of size reduction equipment. homogeneous, 3. refuse is more rapidly stabilized, 4. conveyor movement, magnetic 3.2.2.1 SHREDDERS separation, and air classification operations are enhanced, 5. danger from explosives reaching The term "shredder" will be used in later processes is virtually this report to describe such equipment as: eliminated, pulverizers, hammermills, crushers, 6. reduces scavenger population shredders, etc. These kinds of equipment (rat, gulls, etc.) at land- represent more than 90 percent of the fill sites, size reduction equipment in operation 7. eliminates obnoxious odors processing municipal refuse. To further usually encountered at dumps, illustrate the kinds of equipment cate- 8. provides more surface area for gorized as shredders, a list of manufac- thermal processes such as py- turers is presented in the appendix. rolysis or incineration, 9. shredded nonrecognizable waste Size reduction operations on mixed is considered more acceptable municipal refuse are carried on in 25 for land disposal, states (ref. 3-3) . Considerable amounts 10. blowing debris is less of a of data are available on shredding costs, problem because of the dense maintenance, and characteristics of interlocking characteristics shredded refuse. Table 3-4 lists shred- of shredded trash, and, ding operations in the United States that 11. fire potential, a definite handle mixed municipal refuse.

TABLE 3-4 SOLID WASTE SHREDDING OPERATIONS (REF, 3-3) Metric Ton/Hr Ton/Hour Shredder Location Capacity Capacity Shaft Type Los Gatos, Calif. 27 30 1969 Horizontal Menlo Park, Calif. 3 3 1973 Vertical Mountainview, Calif. 14 15 1974 Vertical San Diego, Calif. 36 40 1970 Horizontal Alamosa, Colo. 14 15 1972 Vertical Chaffee County, Colo. 14 15 1974 Vertical Pueblo, Colo. 36 40 1974 Vertical Milford, Conn. 45 50 1972 Vertical New Britain, Conn. 45 50 1975 Horizontal New London, Conn. 72 80 1972 Horizontal New Castle, Del. 90 100 1972 Horizontal Pompano Beach, Fla. 14 15 1972 Vertical Atlanta, Geo. 67 75 1975 Horizontal DeKalb County, Geo. 45 50 1973. Vertical Chicago, 111. 72 80 1970 Horizontal Chicago, 111. 27 30 1971 Horizontal Chicago, 111. 67 75 1975 Horizontal Pleasant Hill, Iowa 18 20 1973 Horizontal Baltimore, Md. 45 50 1974 Horizontal Marlboro, Mas s. 27 30 1973 Horizontal St. Louis, Mo. 67 75 1971 Horizontal Great Falls, Mont. 31 35 1973 Vertical Monmouth County, N. J. 45 50 1974 Vertical Elmira, N. Y. 36 40 1973 Horizontal New York, N. Y. 36 40 1969 Horizontal Guilford County, N. C. 45 50 1974 Vertical Columbus, Ohio 54 60 1974 Horizontal Willoughby, Ohio 22 25 1975 Vertical Portland, Oreg. 18 20 1973 Horizontal Altoona, Pa. 14 15 1966 Horizontal Harrisburg, Pa. 72 80 1970 Horizontal

41 TABLE 3-4 (CONTINUED)

Metric Ton/Hr Ton/Hour .Shredder Location Capacity Capacity Shaft Type LeHigh County, Pa. 36 40 Vertical Providence,.R. I. . 45 50 Vertical Charleston, S. C. 72. 80 Vertical Georgetown, S. C. 18 20 Vertical Williamsburg, S. C. 18 20 Vertical Galveston, Tex. 22 25 Vertical Houston, Tex. 36 40 Horizontal Norfolk, Va. 27 30 Horizontal Cowlitz County, Wash. 45 50 Horizontal Longview, Wash. 45 50 Horizontal Appleton, Wis. 45 50 Horizontal Racine, Wis. 22 24 Horizontal Madison, Wis. 22 25 Horizontal & Vertical

3.2.2.2 PRIMARY SHREDDERS The disadvantages of a flail mill are primarily ^centered around the fact that it is a new concept as applied to MMR. The first size reduction operation The flail mill along with classification performed on mixed municipal refuse is re- equipment and secondary shredders will ferred .to as primary shredding. Past ex- have to be evaluated in full scale opera- perience with primary shredders have re- tion. sulted in observations such as: reliability has been low, maintenance is expensive Vertical and horizontal shaft primary and time consuming, and reliability has shredders that process MMR can be charac- been low. These observations, however, terized as hammermills (see Figures 3-8 have to be put in proper perspective. and 3-9) . Both types reduce the size of ' First, shredding mixed refuse should never be expected to be accomplished without substantial costs and routine maintenance. To sustain impact conditions necessary to sever (or crush) articles ranging from paper, plastics, and fabrics to metal, rubber, and construction debris, requires high power consumption.. Cutting or impact edges will have' to be routinely replaced or rebuilt which requires a regular maintenance program. Three types of primary shredders are considered in this report: (1) vertical shaft shredders, (2) horizontal shaft shredders, and (3) flail mills. Flail mills are being evaluated as a process to liberate items in MMR without appreciable size reduction. A flail mill would allow the recovery :of magnetic items (by magnetic separation after the flail '•CONVEYOR mill) and thereby reduce the difficulty FIGURE 3-8 and cost of secondary shredding. VERTICAL SHAFT HAMMERMILL The multi-jointed arms of a flail the input MMR to a uniform and relatively mill will self relieve arid allow hard homogenous output product. The basic dif- objects to pass through without rework. ferences between vertical and horizontal Since a flail mill passes all input shaft hammermills are: materials quickly without repeated im- pacts, the capital costs,- the main- 1. A vertical shaft unit must reduce tenance costs, and the operating costs all objects to a size which can are less than for primary shredders. In be discharged through grates re- addition, a more uniform impacting sit- sulting in a more uniform and uation permits operation at maximum homogenous product. capacity without large variations in load.

42 INPUT Gainesville, Florida, report that if the complete plant is amortized (the administrative cost included), the total size reduction operation would cost approximately $4.41 per metric ton of refuse processed. This does not include the disposal cost for the shredded refuse.

3.2.2.3 SECONDARY SHREDDERS

Secondary shredders consist of equipment such as wet pulpers, disk mills, pulverizers, grinders, hammermills, and cage disintegrators. The task of secondary shredding also employs a tearing, impacting, FIGURE 3-9 or pulverizing action. Again, it should HORIZONTAL SHAFT HAMMERMILL be expected (and not underestimated) that frequent hammer or cutting edge maintenance is required. Electrical power requirements 2. A horizontal shaft hammermill will be high to sustain impacting condi- can more easily reject objects tions; however, the more uniform product that are not easily shredded. as received from the primary shredder should reduce the electrical power overload condi- performance data for primary shredders tions that frequently occur in primary can be found in the literature in ref. 3-4, shredding, some of the equipment most 3-5, 3-6, 3-7, and Figure 3-10 indicates frequently used in secondary shredding operations are shown in Figures 3-11, 3-12, 3-13. and 3-14 (ref. 3-8). 10 a 14 CLEARANCE

-ALUS-CHAM8ERS. ESTIMATED RATINGS 11974) . O-WIUJAMS SHREDDER AT GAINSVILLE. FLA. < 1974) OTOLLEMACHE AT MADISON, wis. 11973) X-HAMMERMILL INC. ESTIMATED RATINGS 11972) I | I I I I 0123496

NOMINAL OUTPUT MRTICLE SIZE (ifldm)

FIGURE 3-10 PRIMARY SHREDDING ENERGY CONSUMPTION FOR MIXED MUNICIPAL REFUSE FIGURE 3-11 DISK MILL SCHEMATIC the energy requirements for size reduction operations on solid wastes. The exponential Disk mills are high speed machines con- increase in energy required for smaller sisting of disks that rotate in opposite particle output size is expected for hammer- directions. Refuse, processed by a primary mills of comparable capacities. The units shredder so that the particle size is less shown represent a capacity to handle 30 than 5 centimeters, is fed axially into metric tons per hour. the disk mill and is reduced in size to a fine particle. The output particle size Cost data for shredding facilities is controlled by the clearance between disks. that Deceive MMR and process it to a Pulpable materials are most easily processed nominal output particle size of .2.5 centi- by disk mills and separation operations meter^ are available for both horizontal prior to this type of mill would be neces- and vertical hammermills (ref. 3-4 and 3-5). sary. Two facilities, Madison, Wisconsin and

43 Rasp mills are massive machines that usually run at speeds less than 10 RPM. The input to a rasp mill requires very little (if any) separation since items that resist this size reduction operation can be rejected easily. The output product from a rasp mill is usually larger than 3 centimeters. Cage disintegrators have multiple cages that rotate in opposite directions at high speeds. The output product can be re- INPUT. REJECTS duced to 1 centimeter or less (fine powders). Selective input is required for cage disintegrators, and friable materials are •handled best.

k OUTPUT 3,2,3 SEPARATION TECHNIQUES

FIGURE 3-12 One of the important steps in preparing WET PULPER SCHEMATIC MMR for any processing is segregation of the MMR according to its main component categories. In most cases an efficient separation process achieves most of the material recovery contemplated in the process. At LOW RPM present, many types of separation processes are in use in various industries. It is only a question of adopting these units for handling MMR. In the last few years many INPUT of the manufacturers have tried to adopt their products for this special use. The following are some of the major techniques of separation that are being practiced in the various types of industries: Hand sorting REJECT Screens Magnetic separators Air classifiers Optical sorting Inertial separation Eddy current separation High-density electrostatic FIGURE 3-13 separation SCHEMATIC OF RASP MILL Miscellaneous separation methods

3.2.3.1 HAND SORTING

Hand sorting is perhaps the most effective and least complicated separation process. CAGE BARS It needs almost no equipment other than belt conveyors. The drawbacks are the human elements involved. Further, the soaring labor cost adds to these drawbacks making the process the least economical when large quantities of MMR are involved. Hand removal of bulky items from the belt conveyor is sometimes un- 'avoidable, as bulky materials and rags clog the equipment and force shut downs. A report based on the operation of the Lone Star Organics, Inc., plant at Houston, Texas, states that one person can pick about .450 to .680 metric tons (0.5 to OUTPUT 0.75 tons) per hour of newsprint, card- FIGURE 3-W board, etc., from the mixed waste (ref. CAGE DISINTEGRATOR.SCHEMATIC 3-8). This corresponds to 1.5 to 2.2

44 man-rhours per metric ton and the separation tumbling action provides necessary agita- cost may vary from $3.90 to $5.50 per metric tion and self'cleaning action for clogged ton depending on labor costs. openings of the screen. Trommel screens of 4.5 metric ton/hour (50 ton/hour) Another type of hand sorting that can capacity cost approximately $8,000. be adopted is separation at the source. This is a very effective and economical method for material recovery, if there is 3.2.3.3 MAGNETIC SEPARATION cooperation from the public. The separation can be classified according to newsprint, glass bottles, and cans. As these materials The separation of magnetic materials have to be picked up separately, however, (primarily ferrous) from heterogenous the cost of collection will increase. On industrial.mixtures by magnetic separation the other hand, the volume of remaining is practiced quite widely. There are refuse will be reduced considerably. The several companies who specialize in the total economics of the operation depend manufacturing and marketing of such equip- on the market value of the recovered ment with special application to MMR. materials. The success of the program is limited to small educated communities Efficient separation of magnetic close to the market of the recovered materials from.MMR depends on the degree materials. These conclusions are to some of size reduction and to the extent the extent confirmed by sample studies con- ferrous materials are physically separated ducted by SCS Engineers of California from nonferrous materials. Figures 3-15 under the sponsorship of EPA's Resources and 3-16 are schematic illustrations of Recovery Division of the Office of the Solid Waste Management Programs (ref. 3- 9 and 3-10).

3.2.3.2 SCREENING

In most processes, the physical dimensions and the size of feed inlet determine the size range of the feed material. Therefore, it is not only necessary to reduce the size of the MMR but also to separate it according to the sizes. This is best accomplished by screening. One process can eliminate both larger and smaller than the required range of size limitations. Screening is not new to the industrial manufacturers, and there are many types of screens available on the market. The vibrating rectangular or circular set of screens is most common. The agitation of material is maintained FIGURE 3-15 by mechanical vibration. SUSPENDED-TYPE PERMANENT MAGNETIC SEPARATOR The capacity of screens vary from 9.8 metric ton/hour to 98 metric ton/ hour per square meter (1 to 8 ton/hour per square foot) of screen area depending on the type of conventional mineral material. This does not include solid waste as one of the materials used in arriving at the above data. The lower values are for materials such as fertilizer and cake sizing. As solid waste is still more irregular and nonhomogenous, a lower value than 9.8 metric ton/hour per square meter may be assumed for purposes of designing the screen sizes. With MMR, clogging of the screen openings is a problem, especially if the refuse is wet. Reference 3-8 can be used to determine approximate screen sizes for different applications. Rotating inclined cylindrical screens such as Trommel screens are sometimes used FIGURE 3-16 instead of vibrating flat screens. The PULLEY-TYPE PERMANENT MAGNETIC SEPARATOR

45 magnetic separators. They 'can be made of ton/day) plant will cost around $15,000 either permanent magnets or electro-mag- to $20,000.* ' ! nets. The graphs in Figures 3-17 and 3- 18 illustrate the relationship of capital cost of magnetic separation as a function 3.2.3.4 AIR CLASSIFICATION of capacity of the plant and belt width. Except at very low capacities, the cost is proportional to the capacity and is In general terms, air classification more economical at higher capacities. can bis described as classification of materials according to their density. Separa- tion is accomplished by a jet of air. The shredded material is fed into a moving air current which results in the fluidi- zation of the material. Light density material such as paper, fine particles, film, and foil are carried up and out of the classifier, whereas heavy material such as metals and glass drop down. There are various types of air classifiers depending on the type of chute and the direction of air-flow. .They are illustrated in Figures 3-19 to 3-25. The SUSPENDED PERMANENT UAgNITIC SEPARATOR (ERIE1) I I I 1000 3000 CAPACITY -tt-

25 BO T8 IOO IZ3 ISO CAPACITY, TONS PER MR. (ASSUMING BULK DENSITY Of 2SLS. PER

CYCLONE FIGURE 3-17 FOR CAPITAL COST OF MAGNETIC SEPARATORS DE-ENTRAPMENT AS A FUNCTION OF CAPACITY

LIGHT FRACTION BELT WIDTH, em OPTIONAL 75 AIR LOCK FEEDER

4000

HEAVY FRACTION FIGURE 3-19 • 3000 ZIG-ZAG AIR CLASSIFIER

2000

OPTIONAL (REF. S-8) AIRLOCK FEEDER

CONVEYOR 20 50 40 BELT WIDTH, inch.. -..'.-. .<.".; r-LIGHT FIGURE 3-18 CAPITAL COST OF MAGNETIC SEPARATORS AS A FUNCTION OF BELT WIDTH

As belt width is always proportional to the capacity of the plant, the cost is also proportional to the.belt width. Broader belts are more economical than narrow ones. These conclusions are based on data provided by the Eriez Manufacturing Company (Eriez Magnetics). in the report by N..L. Drobny and FIGURE 3-20 others (ref. 3-8). A magnetic separa- HORIZONTAL AIR CLASSIFIER tor system for a 54 metric ton/day (60 •From catalogs and information furnished by Eriez Magnetics Company, Erie, Pennsylvania 16512.

46 AIR \ AIR /* LIGHT FRACTION

HEAVY FRACTION HEAVY FRACTION FIGURE 3-21 FIGURE 3-21 VERTICAL AIR CLASSIFIER CROSS FLOW AIR CLASSIFIER

SHREDDED MSW

LIGHT FRACTION

AIR

HEAVY FRACTION HEAVY FRACTION

FIGURE 3-22 FIGURE 3-25 SORTEX AIR CLASSIFIER IMPULSE TYPE AIR CLASSIFIER

Zig-Zag air classifier made by Scientific Air Separators, Inc., Denver, Colorado, was used in a laboratory study made by the Stanford Research Institute, Irvine, California. At present, no large-scale performance data on air classifiers are available (ref. 3-11).

The horizontal air classifier has been tried by the U. S. Bureau of Mines in Salt Lake City on shredded automobiles. The vertical type of air classifier manufactured by Rader Pneumatics, Inc., KEY Memphis, Tennessee, is being commercially used to separate nails from wood chips at 1 SHREADEO REFUSE IN a pulp mill (109 metric ton or 120 ton 2 AIR IN capacity). Other examples of vertical 3 LIGHT FRACTION OUT air classifiers are those manufactured by 4 HEAVY FRACTION OUT Sortex Company, Lowell, Michigan, a- unit of which is being used in the Black- FIGURE 3-23 Clawson resource recovery demonstration VANE/ROTATIONAL AIR CLASSIFIER plant at Franklin, Ohio.(ref. 3-11).

47 The cyclone type of air classifier has 3.2.3.5 OPTICAL SORTING been used commercially by Reynolds Aluminum Company at its pyrolysis aluminum recovery operation at Bellwood, Virginia, smelting Optical sorting machines make use plant to recover aluminum from paper- of light-reflection properties of material mounted foil. The cross flow type of air and separate particles on the basis of classifier is commercially used in junk color. This has been quite successful in automobile shredder facilities for clean- agricultural and food processing industries. ing shredded metals. The impulse type of Figure 3-26 illustrates diagramatically air classifier manufactured by Williams Shredder Company is commercially used to recover fabrics and other light material from shredded automobile bodies. The laboratory size test on solid waste made at the St. Louis processing plant for the Horner-Shifren project gave 2 to 39 percent input as heavy fractions using Williams air classifiers. Application of air classifiers for separating shredded cans from shredded municipal PHOTOCELL-^fl solid waste has been suggested by Swindell, - Dressier Company. The rotational type of air classifier, manufactured by Buell Engineering Company, Lebanon, Pennsyl- vania, has been commercially used in. potash, limestone, phosphate, and alumina hydrate separation.

N ',. The Osborne dry separator is a PRODUCT PRODUCT mechanical device for separating presized NO. 2 NO. I material of different specific gravities FIGURE 3-26 by the pulsation of a stream of air SCHEMATIC DIAGRAM OF through a bed of the material. It was AN OPTICAL SEPARATOR used-in San Fernando and is reported successful in removing glass and other the operating principle of a unit manu- similar material from compost. Some of factured by Sortex Company of North the operation details are given in America. To ensure proper operation, Table 3-5. all light sources and optical components are kept clear of dust particles by a low- TABLE 3-5 pressure air'curtain. Sortex produces CHARACTERISTICS OF THE OSBORNE three models ranging up to 45,350 kilogram/ DRY SEPARATOR hour (50 tons/hour) capacity. Particle size may vary from 6.2 milometers (0.25 Size: inches) to 152.4 milometers (6 inches) Length (7 ft. 7 in.) 2.6 m for optimum efficiency. The 45350 kilogram/ Width (5 ft. 0 in.) 1.5 m hour machine costs about $61,000 (ref. 3- Height (7 ft. 3 in.) 2.5 m 8). Feed rate based on composed municipal solid waste: 1.4 metric ton/hr Another form of optical sorting was (l>i tons oer hr.) developed by Battelle Memorial Institute Particle size: for the removal of dark impurities from - Maximum: rock salt and combines a thermoadhesive Inorganic fraction (3/10 in.) 4.8 mm process with optical phenomena (ref. 3-12, Organic fraction (1 in.) 2.54 cm 3-13). So far, this has been applied for Minimum: solid waste processing only on testing Inorganic (1/64. in.) 0.4 mm Battelle basis (ref. 3-14) and has high potential estimates for the recovery of rubber and plastics. Organic (3/16 in.) 4.8 mm Battelle estimates Separation: 3.2.3.6 INERTIAL SEPARATION 90 to 95 percent of the glass, sand, metals, and other heavy fractions are removed from the finished The material is separated in this composts process on the basis of air resistance Cost: and density of the particles. Figure 3- $25,000.00 approximately. 27 from ref. 3-8 illustrates different

48 NET REPULSIVE FORCE

BALLISTIC SEPARATOR CHANGING MAGNETIC FLUX

ORGANIC PARTICLES

INCLINED-CONVEYOR SEPARATOR INCLINED-PLATE

MATERIAL FEED

HEAVY AND LIGHT AND RESILIENT INELASTIC HEAVY AND LIGHT AND RESILIENT INELASTIC PARTICLES PARTICLES FIGURE 3-28 FIGURE 3-27 SCHEMATIC OF PULLEY-TYPE TYPES OF INERT IAL SEPARATORS EDDY CURRENT SEPARATOR types of inertial separation principles, retain charge, adhere to an oppositely Inertial separation has not been success- charged drum, while the conductors drop fully applied to the separation of solid" off immediately. As separation is size waste. sensitive, the process will have to be repeated for different size fractions at several stages. Figure 3-29 (from ref. 3,2.3.7 EDDY-CURRENT SEPARATION

The separation of the nonmagnetic conductive materials (copper, aluminum, and zinc)'from the solid waste has been REVOLVING tried by using eddy-current phenomena. CHARGED It has still to be developed to become ELECTRODE technically promising (ref. 3-15) . This device consists of a drum with a series of magnets around its interior WIPER surface. By rotating the drum, a changing flux is produced in the magnetic field induced outside the drum. WIPER When nonmagnetic conductive material is placed in the changing field, eddy- GROUNDED REVOLVING currents develop in the material and a SPLITTER repulsive force is generated. If this CONVEYOR ROLL force is sufficiently strong, it will deflect the material and effect separa- CHARGED ELECTRODE SELECTIVELY PULLS tion. However, the repulsive forces developed, to a great extent, depending MATERIAL BEYOND FLOW SPLITTER on the size, shape, and surface irregu- FIGURE 3-29 larities of the material. The principle PRINCIPLE OF HIGH VOLTAGE is illustrated in-Figure 3-28. ELECTROSTATIC SEPARATOR

3.2.3.8 HIGH-INTENSITY, ELECTROSTATIC 3-10) illustrates the principle of electro- SEPARATION static separators. The equipment manufactured by the Dings Company and the Carpco Company have been used in the food and High-intensity, electrostatic separa- mineral processing industries, but testing tors are used to separate glass and alumi- with MMR has been restricted to the labora- num in the residue left after processing tory. These tests, however, have been municipal solid waste. Feed material is quite encouraging (ref. 3-10) . The engineer- exposed to an electric charge. The ing feasibility study of Materials' Recovery materials accept the charge, but the con- System by the National Center for Resource ductors retain the charge only for a Recovery, Inc., has reported that the cost short while. The nonconductors, which of the electrostatic separator .to handle

49 about 1814 kilogram/hour (2 ton/hour) is $25,000 at 1972 prices (ref. 3-10).

3.2.3.9 OTHER TYPES OF SEPARATORS 90O ISOO 2TOO 360O 490O 540O

Some other types of separation methods used in the field of separation technology are jigs, stoners, heavy-media separation, etc. Most of these methods make use of the varying densities for their separation. They are sometimes classified as wet methods. Flotation methods can be adopted for separating light organic material, from heavier inorganic material. Such a type of separation may be economical for bior degradation processes, as no drying of the feed material is needed for that process.

Flotation methods are also used for FIGURE 3-30 the separation of light metals such as CAPITAL COST OF SUTTON, aluminum from denser material such as glass. STEELE, AND STEELE STONERS As high-density liquids are used in such processes, they are classified as heavy- media separators. By changing the density 3.2.4 SEPARATION AND SIZE REDUCTION As of the liquid, material of one density in A TERMINAL PROCESS the mix can be made to float and another denser material in the mix can be made to sink. In some processes, this procedure 3.2.4.1 GENERAL is used to separate aluminum from glass in the residue of MMR. Froth Flotation, a proprietory method using the same princi- Some combination of the various sepa- ples as discussed above, is used for glass ration and size reduction techniques, de- recovery (ref. 3-16). scribed previously, almost always is required in preparing MMR for further pro- Jigging, Wilfley tables, and sweating cessing by incineration, pyi:olysis, or are some other methods used in the mining biodegradation methods in the conversion industry to extract minerals from their and recovery of energy products and re- ores. At present, these methods are not sources. Because of this initial position suitable for application to extraction in the overall conversion system, such com- of metals from solid wastes. binations of separation and size reduction steps often are referred to as "front-end" Another way of separating materials systems or processes. on the basis of variations in specific gravity is stoners. A stoner is basically There can be a number of reasons a dry vibrating table that operates by (these are discussed in Chapter 5) why passing a current of air upward through an a municipality may not wish to, or is not inclined screen. Feed enters the inclined able to, consider further conversion of screen from the top end. By proper in- MMR by incineration, pyrolysis, or other stallation of baffles and by control of means. In such instances, the utiliza- position of inlet of feed, material of tion of a front-end process as a terminal different categories can be separated. process in its own right may be one of the Sutton, Steele, .and Steele stoners used in systems alternatives to be considered in the Houston plant (Lone Star Organics, solving a solid waste problem. Inc.) cost about $10,000 each and the cost of screening equipment used along with Several systems alternatives involving it was another $8,000. . Power require- separation and/or size reduction as terminal ment is hardly 0.8225 Watts/kilograms (1 processes are available for consideration horsepower/ton) per hour. Figure 3-30 by municipal authorities. Proceeding shows the relationship between cost and from the simple to the complex, these may capacity of stoners, according to Sutton, be categorized as follows: Steele, and Steele Company (ref. 3-8).

50 1. Size reduction alone. cess; which produces a dried, pulverized fuel somewhat similar to Eco-FuelFM. The process of size reduction (by Both Eco-Fuel™ and the Garrett front- any of several methods) may reduce the end system are described from the physical volume of MMR by up to 50 percent terminal process viewpoint in the of its original bulk. This is an important sections immediately following. advantage if landfill is the ultimate des- tination of the MMR and if landfill sites are scarce, expensive, or a considerable distance from collection points. This is 3.2.4.2 ECO-FUEL™ AS A TERMINAL SYSTEM an expensive way of achieving a single (ref. 3-17) advantage in many situations; however, *it is comparatively easy to make a simple economic comparison to see if the decreased Combustion Equipment Association, landfill disposal costs of the reduced Inc. of New York, has developed a front- volume offsets the size reduction process- end system that is principally oriented ing costs. toward energy recovery. The output product from this system is called Eco-Fuel™ 2. Size reduction with separation of which is a marketable solid fuel. The materials resources. first generation front-end system produced a fuel called Eco-Fuel™I. A flow dia- If after fragmentation of the MMR, gram of the Eco-Fuel I system is shown separation steps are added for the re- in Figure 3-31. covery of significant amounts of constituent resources (metals, glass, paper, etc.), then further advantages are gained. Credits are obtained for the recycled materials. The reduction in physical volume of the residue destined for landfill is greater than for size reduction alone. The Black- Clawson process will be discussed in more detail in a later section as an example of a resource recovery plant. 3. Size reduction and separation with recovery of materials, resources and an energy product. MMR may be fragmented and valuable materials resources separated and recovered. The residue, which contains a high percentage of organic material, may be dried and further pulverized if needed. The resultant product has a heating value on the order of 1.74 x 107 joules/kilogram (7,500 Btu/pound) and represents about 60 percent, by mass, of the original MMR. This dried, . pulverized product can be burned as a fuel in suitably designed facilities, used in an incinerator with or without supplemental fuel, or comprise the feed stock INERTS. FERROUS MOISTURE for a pyrolysis process. 14% METAL 13% 6% The advantages of this third category of alternative are threefold: FIGURE 3S31 ECCO-FUELO ™ I 1. An even greater reduction in the PROCESS FLOW DIAGRAM volume of residue going to landfill as compared with the previous two categories, The Eco-Fuel™ I process consisted 2. Credits for recycled materials, of two stages of shredding, the first and, stage being a flail mill discussed pre- 3. Credits from either local use viously, and two stages of classification or sale of the energy product. and drying to produce a controlled moisture, low-ash shredded fuel. In this process The Eco-Fuel™ production process is solid waste is picked up from the storage one example of this category of systems al- area by a front-end loader and delivered ternative. Another is the Garrett process. to a conveyor system that feeds the pri- In actual fact, the complete Garrett pro- mary shredder. After shredding, the cess is a pyrolysis process; however, its material is dried and classified to front-end portion is a well-designed pro- separate the heavier non-combustible frac-

51 tion from the lighter combustible fraction. 3.2.4.3 GARRET FRONT-END PROCESS The lighter fraction undergoes further size reduction and classification (a mechanical separator) to remove more of the non-com- The Garrett front-end process is de- bustibles. The resulting product is Eco- signed to recover from the mixed municipal FuelTM i. refuse nearly all the glass and ferrous metals, and to convert the organic into The Eco-Puel™ II system has been a dry solid fuel which may be used for modified to obtain more efficient size pyrolysis or incineration. This process reduction and drying in an attempt to involves coarse shredding of the raw, wet obtain a pulverized fuel that contains refuse; air-classification to remove most less moisture and thereby yields a higher of the inorganics; drying of the organics heating value. In this process, solid to a moisture content of 3 percent by . waste is shredded by a flail mill and con- weight; and secondary crushing to a nominal veyed to a magnetic separator for ferrous -28 mesh. Ferrous metals are magnetically metal removal. The separated fraction is reclaimed from the classifier rejects and classified and the fine particles (mostly a sand-sized, mixed-color glass cullet of inerts) are removed, the oversized parr +99.7 percent purity is recovered from the tides are reshredded, and the balance is remaining inorganics by selective crushing sent to the secondary size reduction and screening followed by a proprietary operation. In the secondary size reduc- Froth Flotation process. The preparation tion operation, a chemical is added to of the material for the process involves o.ct as a catalyst and aid in the size the following sequential major operations. reduction operation. Finally, the product 'is screened and classified to yield Primary Shredding; The mixed munici- Eco-Puel™ IT. The final size of the Eco- pal refuse is shredded to about 2.5 centi- Fuel™ II can vary to as small as 100 meters (1 inch) size. In most cases, the mesh, depending on the type of burner reduction to 2.5 centimeters (1 inch) size used in the incineration process. Further involves two or three stages of shredding. developmental tests will be conducted to determine optimum particle size for Primary Air Classification» The incineration, according to Ken Rogers of shredded material is next subjected to CEA, Inc., in a telephone conversation air classification by a simple zig-zag on 6 August 1974. Since the fuel is in unit. . Air classifiers of about 0.61 meters solid form, it is easily stored and trans- by 0.61 meters (2 feet by 2 feet) fitted ported. More information on the incinera- directly to the discharge chute of the tion characteristics, of Eco-Fuel™ TI will end shredder are quite effective. be given later in the Incineration section. (See figure 3-32) Drying; The average moisture content of MMR la about 25 percent. The shredding and air classification reduces the moisture MMR content to some extent. If the moisture content has not been reduced to below 5 PRIMAR* Y percent as needed for the pyrolysis process, SHREDDING then the air-classified organic matter t OVERSIZE must be dried. MAGNETIC MATERIAL SEPARATION Screening; Two-deck screening using 0.61 centimeters (% inch) and #14 mesh, • can eliminate nearly 85 percent of the SCREENING FINE MATERIAL inert material. The fines are subjected to a propriet- CHEMICA* L ary froth flotation for' recovery of glass. TREATMENT A secondary screening follows to ensure 1 that the fines are 90 to 95 percent free SIZE REDUCTION of inorganic material. Milling; The undersize of 0.63 oenti- SCREENIN* G meter (*inch) from screening contains almost 95 percent glass, which is ground in two stages. After first grinding all +8 AI*R HEAT mesh material which contains mostly plas- CLASSIFICATION TREATMENT tics and rubber is recovered. In the second stage of finer grinding, the material FE!mous SOLID INERTS which is finer than 32 mesh and coarser METAL FUEL 8-12% than 200 mesh is subjected to Froth Flota- 6 8% 52-96% tion. ,TM .FIGURE 3-32 ECO-FUELAl II PROCESS FLOW DIAGRAM

52 Froth Flotation; This is a. propriet- Figure 3-33 shows the basic flow ary separation process which claims select- sheet for the combined solid waste and ive flotation with selective reagents. sewage treatment plants. The solid waste The material is magnetically cleaned to plant uses the secondary clarifier effluent remove any remaining ferrous metal. The for'process and scrubber water. The remaining product is pure, sand-sized, solid waste processing produces 189 liter/ mixed-color glass that can be used direct- minute (50 gallon/minute) of waste water ly by glass manufacturers. which is treated by the water treatment plant. The remaining fraction of the MMR Secondary Shredding; The organic is mixed with sewage sludge, primary and -material to be fed into the pyrolysis unit secondary, and incinerated in the fluid needs fine shredding. It should have bed reactor. The scrubber output water, gradation consistancy of at least about containing suspended ash, is mixed with 70 percent smaller than 24 size mesh. A the industrial waste water. The water- typical size distribution of prepared suspended ash works as a settling agent material for the Garrett process is in the industrial clarifier, and the plants shown in Table 3-6. These data are from can use common utilities and service facili- a pilot study conducted by the County of ties. After processing, with 95 percent San Diego, California. effective volume reduction by recovery and incineration, the 5 percent that remains is TABLE 3-6 organic, non-toxic, and inert. This can SIZE DISTRIBUTION OF GARRETT then be safely landfilled. SECONDARY SHREDDED SOLID WASTE Organic Portion Only Size Cummulative The fluid bed reactor is approximately wt. % Wt. % 7.32 meters (24 feet) in diameter and 9.14 Tyler Mesh Microns Retained Retained meters (30 feet) high. The bottom plate is perforated and is covered with approximately i* inch 6350 6.0 6.0 1.21 meters (4 feet of sand. The sand is 16 991 21.0 27.0 suspended by air blown up through the per- 20 833 3.9 30.9 forated, plate. For cold start of the fur- 32 495 19.1 50.0 nace, the sand is preheated to 649°C (1,200° F) by oil burners. This requires 9.45 x 48 295 11.7 61.7 3 80 175 9.1 70.8 10 liters of fuel. The finely chopped 100 147 4.8 75.6 solid waste is introduced into the hot 150 104 4.6 80.2 fluidized bed and contact heating by the 200 74 4.9 85.1 sand causes complete combustion. The com- Minus 200 Minus 74 14.9 100.0 bustion products have a reactor exit temperature of 816°C (1,500°?) and are water Note: Solid waste ground to this size cooled and washed to remove the fly ash. is of a matted, fibrous nature. Screen size is not an accurate The plant that processea the reactor measure of particle length or feed is a preprocessing and recovery system. width particularly above 20 mesh MMR is fed into a hydropulper where the where considerable "balling" is pulpable and friable materials are size apparent, (ref. 3-18) reduced so as to pass through the 1.91 3.2.4.4 BLACK CLAWSON PROCESS centimeter (0.75 inch) diameter openings in the hydropulper extraction plate. This The Black Clawson Company developed is slurried to 3 percent to 3.5 percent for the city of Franklin, Ohio, a solid and pumped into typical paper milling waste disposal and reclamation system based operations. The hydropulper continuously primarily on a system of fiber recovery ejects nonpulpable materials which are through hydropulping (ref. 3-19). predominately ferrous metals. The system also centrifugally removes The slurry is next treated in a liquid metal and glass, and dewaters and burns cyclone to remove larger particles. This the remaining material in a fluid bed reject is 80 percent glass and 20 percent reactor. aluminum, other metals, and dirt. Next the non-fiberous organics such as plastic In the preliminary design study it was and leather are removed by a screen of 3.2 discovered that sewage sludge could be mix- millimeter (1/8 inch) mesh;.. The material ed with the separation residue and disposed that passes through this screen is now of by incineration. The sewage sludge can diluted to a 0.5 percent consistency and be in either a raw, activated, or digested passed through an average 1.59 millimeter state and no longer needs coagulents for (1/16 inch) mesh paper mill screen which dewatering. The remaining fraction of the removes the remaining non-papermaking MMR, after metal and glass removal and fibers. Fbllowing this, fine sand and fiber recovery, provides sufficient heat- fine fibers are removed by centrifugal ing value to burn the sewage sludge in the cleaners. The remaining acceptable fluid bed reactor.

53 INDUSTRIAL CLARIFIER' SOIL-STABILIZATION DISTRIBUTION CHAMBER INDUSTRIAL AERATION BASINS WASTE WATER ,1 N0.'1 NO. 2 ! -NO. 3 i MUNICIPAL & X WASTE WATER JUNCTION CHAMBER

MUNICIPAL' CLARIFIER SCRUBBER WATER BLEED .'.PROCESS WATER BLEED PROCESS WATER

HYORAPULPER LIQUID ~ ..CYCLONE PRESS MUNICIPAL w BED VENTURl REACTOR SCRUBBER WASTE WATER TO TREATMENT ftANT

FIGURE 3-33 BASIC FLOW DIAGRAM FOR BLACK CLAWSON PROCESS material is dewatered, given a controled in Franklin, 'Ohio. : The Black Clawson mild caustic treatment, dewatered again, process came on line with 136 metric ton/ and finally baled. day (150 ton/day) plant in 1972 and added a • ( resource recovery operation for aluminum All the rejected non-recyclable and glass in early 1974. .Because of this, material, chiefly organic, is mixed with the report data from the two latest reports, sewage sludge. The mixture is dewatered EPA's Second Report to Congress (1974), to 40 percent solids and" used as furnace . (ref. 3-20) and Schulz, et.al. (ref. 3-21) feed. 1973 are perhaps most reliable. The process costs from these sources are given in The plant is designed for a nominal Table 3-8 for various plant sizes. The capacity of 136 metric ton (150 ton) resource recovery data are also listed in 24 hour day. It now runs for an average Table 3-8. The analysis of EPA data for the of 8 hours/day. The calculated amount of 454 metric ton/day operation with resource materials recycled in* an 8 hour day are recovery and source reduction gives a net given in Table"3-7. of $9.75 per metric ton ($8.83 per ton) for TABLE 3-7 processing Franklin, Ohio's waste. An CALCULATED AMOUNT OF.MATERIALS analysis of Schulz's data for the same size RECYCLED PER 8-HOUR DAY plant, gives a slightly different disposal cost. . ' Metric Ton/8 • Tons/8 Scaling the plant size up to 1814 , .. hour day hr day metric ton/day (2,000 ton/day) using Schulz's data gives a similar cost per ton Paper Fiber 7.26 to 9.07 8 to 10 for disposal of Franklin's solid waste. Ferrous Metal 4 to 5 , 4 to 5 . In this case scale size produces a metric Glass (crushed) . 2 to 3 2 to 3 ton cost of $8.50 ($7.70 per ton). Thus increasing plant size by a factor of 4, The economics of the Black Clawson produces no significant savings either on process are based on the market conditions process costs or on resource recovery.

54 TABLE 3-8 (A) ECONOMIC DATA-BLACK CLAWSON PROCESS PROCESS COST SHEET

Process Name; Hydraposal/Fiber Claim System of Black Clawson Data Source: EPA's Second Report:to Congress-1974 (ref. 3-20) Capacity in Tons/Day: 454 Metric Tons (500 tons) DOLLARS COMMENTS CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt (a) (a) No details given Processing Eqmt on cost break . • Postprocessing Eqmt down Utilities- (b) (b) Actual Plant in Building & Roads operation is 136 Site Preparation metric tons/day Engr. & R & D (150 ton/day) Plant Startup Working Capital Misc. :

TOTAL 8,300,000

OPERATING COSTS ($ PER YR) Maint. Material (c) (c) Assume 300 day/ Maint. Labor ' year operation Dir. Labor Dir. Materials Overhead Utilities l,500,000(d (d) Operation and Taxes maintenance Insurance Interest Disposal of Residue Payroll Benefits Fuel Misc. :

TOTAL 1,500,000

CREDITS ASSUMED ($ PER YR) 975,000 i DOLLARS/YR. COMMENT

Fuel: Liquid None (a) Based on 165,000 Gas metric tons/yr Solid (150,000 tons/yr) Power: . None Steam (b) Fe 9 $14.90/mt Electricity ton ($13.50/ton) Hot Water (a) Magnetic Metals 127,500(b) (c) AL § $220/mt Nonmagnetic Metals 120,000(c) ton ($200/ton) Glass 75,000(d) Ash (d) $13.20/mt ton Paper 562,500(e) ($12/ton) Other:sewage sludge 90,000 disposal (e) $27.60/mt ton ($25/ton)

TOTAL ($ PER YR.) 975,000

55 TABLE 3-8(B) ECONOMIC DATA-BLACK CLAWSON PROCESS Process Name; Hydraposal/Fibre Claim System of Black-Clawson Data Source: Schulz Report {ref.' 3-^21) Capacity in Tons/Day: 1814 Metric tons (2000 tons) DOLLARS COMMENTS CAPITAL COSTS (TOT. $) Land (a) (a) No detail given Preprocessing Eqmt . Processing Eqmt Postprocessing Eqmt Utilities (b) (b) Actual plant Building & Roads operating at Site Preparation 150 ton/day Engr. & R & D Plant Startup Working Capital Misc.:

TOTAL 36,000,000 . .

OPERATING COSTS ($ PER YR] Maint. Material (c) (c) Assume 300 da/ Maint . Labor yr operation Dir. Labor Dir. Materials Overhead 6,180,000 Utilities Taxes Insurance Interest Disposal of Residue 300,000 (d) $.55/metric ton Payroll Benefits (d) of residue ($0. Fuel 50/ton) charge Misc . :

TOTAL 6,480,000 ^

CREDITS ASSUMED ($ PER YR) 4,998,000 :DOLLARS/YR. COMMENT

Fuel: Liquid None (a) 1.19 x 10s Gas Joules/metric Solid ton at $2.78/109 Power: joules (300 KWH/ Steam ton at $.01/KWH) Electricity 1,800,000 (a) Hot Water Magnetic Metals 450,000 (b) (b) $11IOC/metric Nonmagnetic Metals 672,000 (c) ton ($10.00/ton) Glass 240,000 (d) (c) $221/metric ton Ash (200/ton) Paper 1,836,000 Other: (d) $11.00/metric ton ($10.00/ton)

TOTAL ($ PER YR.) 4,998,000

56 Each source and plant size, regard- .Modern energy recovery incinerator plants less of the different assumptions, yields are more acceptable today and are expected about the same cost of disposal, namely to meet most local, state, and federal air $8.00-S10.00 per metric ton of refuse. It pollution standards (ref. 3-22). should be noted that these figures can still vary with the resource recovery •: In this section, a number of incinera- credits obtained. For both sources, the. -tion processes will be discussed. The ratio of operating costs to revenue is particular systems are: about the same, i.e., ranging from 1.9 to about 2.6. The feasibility of applica- 1. Typical water-wall incinerators for tion of the Black Clawson process must steam generation. depend heavily on the actual credit ob- 2. C. P. U. 400 'system for electrical tained in a specific area for the recover- power generation. ed materials. Particular attention must 3. Supplemental fuel systems for steam be paid to the market for paper.and paper generation. pulp. 4. Direct incineration of prepared refuse in boilers for steam generation. Schulz, in his report, gives a credit for steam. Without this rather large A cursory technical description of the credit, his operating cost/revenue ratio above incineration processes will be fol- goes from 1.92 to 3.01. The justification lowed by a detailed description of one of this credit is questionable since the typical process selected from each of the only reasonable use for the steam in the above four incineration areas. The detail- Franklin, Ohio, case appears to be in the ed description will also include economic sewage disposal plant. In other locations data. the steam market may be different. Also, the EPA's projection of the costs should be better since its figures are based on 3.3.1.1 COMPOSITION LIMITS FOR SELF- a longer operating time under actual 136 BURNING REFUSE metric ton (150 ton) day operating conditions. It should be noted that the present recovery system still produces about 10 Many persons believe that municipal tons of solid residuals per 100 tons of refuse can be burned only by the use of MMR delivered to the plant. These resi-« additional coal, oil, or gas. This has duals must be landfilled at this time in rarely been the case. Many incinerators Franklin. The use of the residue for are equipped with auxiliary oil or gas aggregate should be considered as a burners to keep the system warm when no possible additional credit to reduce the refuse is being fired, for initial igni- cost of landfill. tion of wet refuse, or to dispose of waste oils collected separately from the refuse. Von Roll of Zurich'; Switzerland, as pointed out by Leatham (ref. 3-23) present the 3,3 INCINERATION PROCESSES following three-coordinate chart, Figure 3-34, to illustrate the wide range of refuse which can be burned without auxili- 3.3,1 INTRODUCTION ary fuel. . .

The solid waste problem and' the energy shortage have focused the attention of engineers on possible methods of 90 energy recovery from solid waste. Since certain areas of Europe have been producing steam from the firing of refuse for many years, it is only natural that some of our current technology is patterned after European practice. . The primary reason for incineration of refuse is volume reduction. .A typical incineration process might reduce the volume of refuse by 92 percent, while reducing the weight by 80 percent. The residue from thermal reduction pro- 10 20 3O 40 50 6O 70 80 90 cesses is inert, and may be landfilled % COMBUSTIBLE REFUSE WILL BURN WITHOUT AUXILIARY or used, in some cases, as a building FUEL WHEN AVERAGE COMPOSITION FALLS material. Incinerators built prior to INTO SHADED AREA 1968 were not well designed by today's technological standards and were generally FIGURE 3-34 viewed unfavorably by the public. COMPOSITION LIMITS FOR SELF BURNING OF REFUSE

57 The. amount of heat that MMR will pro- spaced steel tubes weeded together, with duce, when burned, depends upon its ash water or steam circulated through the tubes content, its moisture content, and the to extract heat from the combustion zone. nature of the combustible components. In- The decision as to heat recovery economics creased use of wastes from packaging and is governed primarily by the nature of-the the decreased amounts of furnace or stove local fuel market, including availability, ashes has caused a continual increase in price, and demand patterns. the heating value of refuse worldwide. It takes about three pounds of refuse to The water-walled furnace with integral equal a pound of presently available boiler, superheater, and economizer (in a bituminous coal in the production of steam. later pass) or the refractory lined furnace The non-uniformity of refuse plus relative- with a waste-heat type of boiler mounted ly high ash and moisture content results in the outlet flue can be used for energy in a furnace and boiler efficiency of recovery. In any event, the design of about 65 percent in the best of modern the grate, furnace, and heat exchange sur- incinerators; whereas gas, coal, and oil faces must consider the special character- fired units are capable of performing istics of refuse as a fuel. .Heat release at efficiencies greater than 80 percent. per square foot of grate will be considerably less than for coal even though the weight and volume of fuel may be much 3.3.1.2 STOKERS greater. Furnace temperatures must be maintained within the range of 760°C (1400°F) to 982°C (1800°F) to insure destruction of In Europe thick fuel bed burning is all odors without fusing fly ash to walls universally practiced. The stoker hopper or tubes (ref. 3-24, 3-25). is fed by a traveling crane with a grapple. During the last 12 years, as reviewed by Astrom, et.at., (ref. 3-24), and Roberts, 3.3.1.4 PARTICULATE EMISSION et.al., (ref. 3-25) a few manufacturers have developed grate designs that have managed to obtain a strong foothold in the The flue gases contain solid and gas- European market. They are all based on a eous pollutants. The concentrations vary moving grate, but the movement varies in from one plant to another as presented by type. Normally complete incineration Jeffers and Nuss (ref. 3-1). The dust is only obtainable with a moving grate, content, entering the precipitator varies sinpe a regular movement of the fuel bed from 3.43 x 10"3 to 1.72 x 10"2 kilogram/ is not possible on a stationary grate due meter3 (1.5 to 7.5 grains/SCF) As a ,to the varying size of waste pieces and mean value, normally, 8 x 10~3 kilograms/ varying density of the refuse. meter3 (3.5 grains/scf) is used. The Von Roll system uses a sloping The sulfur oxides content is usually grate stoker. This stoker is composed of small compared to gases from oil or coal three separated grates independently burning because of the low sulphur content 'driven. The speed of each grate, as well in refuse. A major part of sulfur oxides as the combustion air distribution, can may be from auxiliary fired fuel. Massey, '.be controlled to insure satisfactory com- et.al., (ref. 3-26) indicated that munici- bustion. The three grates are sloped at pal refuse sulfur content has been measured approximately 15 degrees downward. The as 0.12 percent of the ultimate analysis, middle section, on which most of the burn- as compared with up to 3 percent sulfur in ing, takes place, is equipped with mobile coals used for power generation. knives which stir the burning bed to achieve complete combustion. The first Formation of hydrochloric acid can section is the drying grate. The second become a technical environmental problem. and third are, respectively, the burning With a PVC-content of 2 percent, the flue grate and finishing grate. This type of gases contain 690 PPM HC1 and a 12 percent "stoker is a forward acting grate. C02 level. No regulations currently exist concerning allowable HC1 emissions. HC1 The Martin system has a reverse re- can be removed by scrubbing the gases in ciprocating stoker which functions similar water. However, it is not easily separated to a forward acting grate. This grate de- from water and can cause a water pollution sign is used in Europe and North America. problem. , . Particulate Emission Control Devices 3.3.1.3 FURNACE AND HEAT EXCHANGE EQUIPMENT There are four basic types of particulate collection devices, discussed by Jack- son, (ref. 3-22) and White (ref. 3-27). The furnace can be water-walled. This is an effective means of heat recovery which -Mechanical Collectors -Wet Scrubbers utilizes furnace walls made of closely -Electrostatic Precipitators -Fabric Filters

58 Mechanical Collectors 3.3.1.5 ENERGY OUTPUT AND USE These devices use centrifugal forces to separate particulates from gas streams. Some of the new incinerator plants are The gas is introduced tangentially which designed with energy output. This energy causes the particulates to be separated^ is in the form of steam or electricity. from the gas stream. Mechanical collec- The steam output holds primary significance tors are selective with respect to particle in systems such as the supplemental fuel size and density. These collectors can be boiler and the direct fired refuse boiler. expected to exhibit 75 to 80 percent col- The steam can be sold to nearby users for lection efficiencies on suspension-fired such purposes, as heating, cooling, equip- systems. ment testing, and electric power generation. Of all the resources that can be Wet Scrubbers obtained from refuse, including recycled materials, steam is probably ,the most . These devices wet the particulates valuable, if a market is available. entrained in the flue gas. The size and weight of the particle is effectively in- Part of the steam generated .'can be creased by this wetting, so they can then used for plant power. Steam is normally be mechanically separated. Scrubber per- used in the plant for the undergrate formance depends on the turbulence of the heater, sootblowers, building heat, and gas, liquid droplet-size, and the amount the turbine drive for the shredder. The of scrubber liquid used. Although capable remaining steam is available for export of much higher collection efficiency, ' and sale. scrubbers require higher power inputs than mechanical collectors. The wet scrubber Another approach to utilizing the '... requires about the same physical space as energy of refuse is to use products 'of., a mechanical collector, but the associated combustion to power a normally gas-driven water-and ash-handling equipment can re- turbine generator. The advantage of'a quire additional space of 2 or 3 times the turbine generator is that the turbines.can scrubber space requirements. be put on and off line rather rapidly. . The CPU-400 is a system of this type which Fabric Filters will be discussed later. ' The stack gas is passed through a filter cake of collected ash deposited on the fabric envelope. The collection 3,3,2 DESCRIPTION OF INCINERATOR .PROCESSES efficiency of fabric filters is 99 percent or greater. -Simplicity and good perford- 3.3.2.1 TYPICAL INCINERATION PLANTS WITH inance make these systems attractive, while ENERGY RECOVERY space requirements and pressure drop are serious disadvantages. The operational' costs of this collection system are high. Most modern heat recovery incinerators use a water-walled furnace, the combustion Electrostatic Precipitators gases exchange heat in the boiler section, superheaters and economizer, causing a gas These collectors use high intensity temperature reduction from 1371°C (2500°F) electrical fields to separate particu- to 232°C (450°F) (ref."3-26). The gases lates electrostatically from flue gases. then enter the electrostatic"precipitatpr Although relatively insensitive to particle for removal of the particulate matter with- size variation, precipitators depend on in prescribed 'limits. ' The boiler is not, particle resistivities that are consistent only a steam generator, but also is an with effective operation. White (ref. 3- efficient means to"cool the' furnace gases. 27) has indicated that fly ash resistivi- 2 This acts to prolong 'the life of the fur- ties below 10' ohm-cm are considered nace. Only energy recovery systems will' good for electrostatic precipitation. be discussed, and Table .3-9 contains technical data on five selected energy recovery Single-stage electrostatic precipita- plants. tors will remove up to 99.5 percent of entrained fly ash.' Space requirements are similar to those for fabric filter 3.3.2.1.1 Description of Water-Wall collectors. The operating cost for Incineration Plants electrostatic precipitators is low. The performance for precipitators is a function of the particle velocity within the Montreal, Canada Incinerator collection unit. This velocity determines the overall size and cost of the precipi- A 1088 metric ton/day (1200 ton/day) tator, as stated by ref. 3-25 . plant began operating in .1971 at Montreal

59 TABLE 3-9 TYPICAL INCINERATION PLANTS .WIT H nENERGY RECOVERY

OUTPUT DATE OF FLOW RATE TEMP PRESSURE START METRIC TPD SEPARATION kg/hr xlO'j "C N/m2 xlO'6 LOCATION UP STOKER TPD TECHNIQUE Ib/hr xlO •*T Psig USAGE COMMENTS REFS.

Montreal 4x272 Electric- 45 260 1.55 Heating 10-15* of 3-24 Canada 1971 Von Roll 4x300 Static 100 500 225 $ input -ash 3-28 Precipi- Auxiliar) 8 scrap tator Power metal

Chicago 4x363 Electric- 200 204 1.7 Recovered 3-24 Northwest 1972 Martin 4x400 Static 440 400 250 Limited Magnetic 3-28 Incinerator Precipi- Metals tator

Harriaburg 2x326 Electric- 63 232 1.7 Auxiliar) Pennsylvania ' 1972 Martin 2x136" Static TsT 416" 216" Power 3-29 Preclpi- tator

Nashville Late 2x226 Wet 99 185 1.03 Auxiliary Tennessee 1974 Von Roll 2x350 Scrubbers 2l8 SAT iso- Coolant, $16.5 • Dry SoT Steam Million 3-30 Cyclone SAT . Saugus 4x272 Electric 102 .427 4.3 Power 3-1 Massachusetts 1975 Von Roll 2x360 Static 2lT 556" Precipi- tator

(ref. 3-28). The plant's 4 boiler units, A Research-Cottrell electrostatic using grate technology supplied by Von precipitor is used to remove over 95 Roll of Switzerland, generate a total of percent of the dust entrained by the gases. 4.5 x 104 kilogram/hour (100,000 pound/ Each of the four precipitators handles hour) of steam. The capital cost of the 2830 cubic meters (100,000 cubic feet) per incinerator was $15 million, and the re- minute of 250°C (482°F) gas on a contin- fuse processing cost is estimated at uous basis. It will reduce the dust to . $7.70/metric ton ($7.00/ton),.including about 0.17 kilograms/lOOOkilograms (0.17 amortization of capital costs and operat- pound/1,000 pounds) of gas. This value ing costs. The refuse disposal cost is is below the limits set by the U. S. Feder- expected to decrease further once markets al Incinerator Guidelines. are found for all the steam. Although the Montreal Von Roll incin- The refuse flow is the same as erator was the first on the North American Figure 3-35. The-grate itself consists Continent, the design had been used in of three distinct sections: Europe since 1954. The plant included successive refinements in the art of burn- 1. a predrying grate, ing refuse and generating steam simultan- 2. the main incineration area, eously. and 3. a complete burning grate. Chicago Northwest Incinerator . The heat transfer equipment includes a radiant section, a convection section, A 1451 metric ton/day (1600 ton/day) a superheater, and an economizer. The waterwall incinerator began full-scale refuse combustion chamber is of ample operation in 1971 (ref. 3-28). Part of volume to maintain a satisfactory tempera- the 199,584 kilogram/hour (440,000 pound/ ture, without excess heat that might hour) of steam generated is used to cause the refuse cake to melt. Com- . operate the plant, with the remainder a- bustion-chamber temperatures must not • vailable for sale. The plant uses Euro- exceed 10388C (1900eF). pean developed Martin stoker system.

60 The flow diagram for the Chicago In- The four incinerator units each cinerator Plant is shown in Figure 3-35. handle 363 metric tons (400 tons) of refuse per day, and produce approximately 2 x 105 kilograms (4.4 x 10s pounds) of steam per hour. A portion of the steam is used inplant to drive turbines for pump and blower operation. The balance of the steam is available for sale. Since no market was created initially, most of the steam is condensed in air-cooled condensers. After the combustion gases have passed through the boiler section they are reduced to a temperature of approximately 2328C (450°F). The gases are then introduced into an electrostatic precipitator which collects the particulate matter still con- .tained in the gas stream, providing a final particulate concentration of 1.14 x -TO LANDFILL 10~* kilograms/meter^ (0.05 grains/cubic feet) of gas emitted from the stack. To ELECTROSTATIC allow for a high collection efficiency the BOILER PRECIPITATOR gas velocity must be less than .91 meter/ second (3 feet/second). Once the dust FIGURE 3-35 particles have collected on the collector FLOW DIAGRAM FOR THE plates, the plates are cleaned automatical- CHICAGO NORTHWEST INCINERATOR ly by a regular rapping action. The fly ash is then conveyed to the ash discharger. The refuse is taken from the storage pit • The capital costs of the Chicago North- and fed to the feed hopper. The feed west Incinerator was $23,000,000 in 1970 chute has a shut-off gate which is used dollars. The operating cost was estimated to prevent air intake to the system during at $5/ton at start-up. No sale has been shutdown. The feed chute also automati- developed for the steam. cally feeds refuse into the incinerator. The main component of the plant is Harrisburg, Pennsylvania Incinerator the incinerator, which has a reverse- reciprocating stoker. The stoker grate As Harrisburg's population increased is inclined at an angle of 26 degrees, the solid waste problems mounted; consi- developing a- normal downward flow of the deration was being given to all the avail- refuse. The reverse-acting grate pushes able disposal methods, with particular the refuse back up the inclined slope, emphasis on a properly engineered sanitary creating a mixing action. Air passes landfill. The search for a new landfill through the grates, supplying oxygen to site met with failure; however, it was the refuse which results in maximum burn- decided that incineration offered the only out in the shortest length of grates. dependable, long-range solution to the solid waste problem (ref. 3-29). The Martin Grate Incinerator is designed to make use of the high temperature The Harrisburg incinerator consists created in combustion. The combustion basically of two refuse burning systems, gases are directed up over the stoker area each of which includes a charging hopper toward the incoming refuse, where they dry and chute, a multi-pass furnaceTboiler, and help ignite the new refuse. a waterwall furnace, an electrostatic precipitator, and the necessary connecting The combustion gases then pass through pieces. the boiler section of the plant. The boiler, approximately 12.2 meters (40 feet) In many respects the Harrisburg in height, is constructed of membrane water- Incinerator is similar to the Chicago walled tubes with extruded fins. The use Incinerator, with the flow diagram shown of refractory is limited to a height of in Figure 3-35. There are, however, some 4.6 meters (15 feet)above the grate. This features of the Harrisburg incinerator refractory section prevents corrosion of that are different and will be discussed the water-walls when burning plastics. here. The boiler provides for a maximum amount of heat recovery, and allows for the col- One such feature is the 45 metric ton lection of fly ash. The fly ash collected (50 ton) capacity weighing station, which is automatically fed to the ash discharger is electronically operated to eliminate where it is mixed with other residue and the need for an attendant. The payload trucked to a landfill site. of the vehicle is recorded automatically

61 arid a printout is provided that is used to charge for the use of the incinerator. Another feature of the incinerator is the hammermill shredder that is located below the tipping,floor level at the end of the storage pit. The oversized wastes are fed to the shredder through/ a hopper at. the tipping floor level either by Handling manually, by dumping from a 'truck, or:by using the overhead cranes. The bulky wastes' are "reduced to fragments of not more thah;,six inches in any dimension, REFUSE FEED INCINERATOR after which they are conveyed to the STORAGE PIT HOPPER storage pit for burning with the other CRATES refuse. ' * The shredder is driven by a 1491 BOILER MECHANICAL kilowatt (2,000/horsepower) steam turbine. DUST BANK SCRUBBERS This is a .'relatively untested method of COLLECTOR - driving-the shredde'r, which has greatly reduced electric demands of the plant. FIGURE 3-36 The performance of the shredding operation REFUSE FLOW DIAGRAM FOR THE has been satisfactory. NASHVILLE INCINERATOR To control the air flow through the condenser and 'subcooler bays, variable solid waste from transfer stations is pitch fans were used. The pitch of the dumped in the storage pit. The capacity fans is regulated by inlet conditions to of the pit is 6500 cubic meters (8500 cubic the subcooler and condensate. yards), enough storage for four days' operation. Wastes move down the hopper Two electrostatic precipitators onto a reciprocating type grate for igni- are used to control the particulate matter tion, combustion, and burnout with residue in the stack emissions. The precipitators and non-combustibles discharged into the we're designed to operate at a gas tempera- ash disposal trailer. Combustion gases ture of 274"C (525°F) and gas velocities pass through the main boiler bank, mechani- not to exceed 1.07 meters (3.5 feet) per cal separators and then the -three-stage second. The average efficiency for the scrubbing system. The system reduces- the precipitators was tested and determined particulate and gaseous pollutants to the to be 95 percent. state and federal emission level. Wet scrubbers will be used so that Nashville, Tennessee Incinerator gaseous pollutants as well as particulates can be removed. The overall emission The Nashville Thermal Transfer Corpora- levels are estimated to be considerably tion was chartered under the laws of Ten- lower than that which would be produced by nessee in May, 1970 (ref. 3-30). This tax- the many small plants which it replaces. exempt corporation was'authorized to issue tax exempt revenue bonds, construct, own, and operate the solid waste incineration Saugus, Massachusetts Incinerator facility and distribution system in downtown Nashville. The planned incinerator A $31 million plant is being built system will cost $16.5 million. The plant by Reaco, Inc. that will burn garbage and will incinerate solid waste and provide provide steam to the General Electric Plant the capabilities to heat "and cool buildings in Lynn, Massachusetts. The plant, will located in downtown Nashville area. process about 1090 metric tons (1200 tons) of refuse per day, as presented by reference Plans call for the initial phase of 3-1. the system to be completed by late 1974, which will include an incinerator capable The plant is the United States' of burning about 653 metric tons (720 largest Von Roll incinerator and should tons) per day of solid waste, and provide begin operation in 1975. The overall plant heat and chilled water to 27 downtown is very similar to the Montreal incinera- buildings, 12 of them state office build- tor, and the refuse flow diagram is essen- ings. The incinerator system has production tially the same as Figure 3-35. The Saugus capacity of 1.7 x^'lO1^ joules/hour (13,500 incinerator uses a water-wall chamber and tons) of refrigeration and 99,000 kilograms inclined grates in the combustion zone. (218,000 pounds) of steam per hour. The plant will produce as much as 159,000 kilograms (350,000 pounds) of steam an The refuse flow through the incinera- hour. The steam will be piped across the tor facility is shown in Figure 3-36. The Saugus River to the General Electric Com-

62 pany at a gage pressure of 4.3 x metric ton (70 €on) a day pilot plant has newton/meter^ (625 psi) and between 418°C been constructed and is in operation. The,,, (785-°F) and 441°C (825°F). system consists of rather complete front- '.- end processing, where magnetic materials, A few special features were included glass, stone, and aluminum are separated. in the design of the plant. It will permit The refuse,entering the combustor is the future expansion at both ends. The concrete lighter fraction of the air classified storage pit will accommodate about 6 times stream. See Figure 3-37 for a schematic the daily refuse load, 6077 metric tons of the system;(ref. 3-31). (6700 tons) in case operations are inters i- rupted. The system will include standby The combustor is a fluidized bed, with oil burners in the main boilers as sand as. the heat transfer medium. Combus- well as oil-fired standby boilers to tion gases plus molten aluminum and ash assure continuous steam production. exit the fluidized bed and are cleaned by a series of cyclone separators. These Fly ash will be controlled with two gases are then expanded through, a gas electrostatic precipitators. Its opera- turbine/compressor system. tions will surpass all environmental requirements, and the plant will neither intake The two-stage turbine drives a com- from nor discharge to the Saugus River. A pressor, which provides the pressure for more detailed discussion of the Saugus in- the fluidized bed. The second stage of cinerator will follow in paragraph 3.3.3.1. the turbine drives'an electrical generator, which provides electrical power as the system output. 3.3.2.1.2 Combustion Power Company's CPU- 400 System Energy Conversion Problems have occurred with the gas System cleanup, with the fluidized bed, with the rate of refuse feed control, and with aluminum deposits on the turbine blades. The CPU-400 system for disposing of The system is still in the development municipal refuse is under development by stages, and additional work is being done . Combustion Power. Company. A 63.5

AIR [CONVEYORS |-»HSHREDOER | ^ DENSITY CLASSIFIER REFUSE HEAVY LIGHT PACKER STREAM STREAM TRUCK MAGNETIC SEPARATOR

MAGNETIC I NONMAGNETIC MATERIALS MATERIALS CYCLONE SEPARATOR

ALUMINUM SEPARATION E |STORAGE | NONFERROUS NONALUMINUM MIXED METALS

3 RD 2 NO 1 ST FLUIDIZED BED SEPARATOR SEPARATOR SEPARATOR EXHAUST COMBUSTOR TT 1 GASES NF NJ/ 'r i RESIDUE RESIDUE RESIDUE FILTERED COMPR EXHAUST AIR I AIR GASES

COMPRESSOR

,..FIGURE 3-37 CPU-400 SYSTEM SCHEMATIC

63 to improve overall system performance. See generated. Ferrous metals are separated paragraph 3.3.3.2 for a more detailed dis- from the water-quenched residue by magnetic cussion of the CPU-400 process. separation. A schematic of the plant : operation is shown in Figure 3-38. 3.3.2.2 SUPPLEMENTAL FUEL INCINERATION ELECTROSTATIC CASES TO | PRECIPITATORS ATMOSPHERE Although the practice of recovering energy from the 'firing of' refuse in in- COMMON HEAT EXCHANGE cinerators or steam-generating boilers is I EQUIPMENT a relatively new concept in the United States, it is a fairly old.'policy in.. REFUSE COAL ^ SIDE SIDE Europe. A number of refuse-fired plants ' REFUGE FEED ^ are in operation throughout the European COAI countries, and three German plants built PULVERIZERS within the last decade will serve ,33 proto- CRATE' type European plants for "the supplemental j. ' fuel discussion. The data is taken from Roberts, et.al., (ref. 3-25). Each of these plants has a different means of firing the refuse -for energy recovery. Table 3-10 lists representative supplemental fuel plants. .' '.' . Munich North'Plant, Block/..! ' . . . FIGURE 3-38 This Munich plant uses refuse as a SCHEMATIC OF MUNICH supplementary fuel with coal,.but the NORTH PLANT, BLOCK I burning takes place in two separate chambers. « The refuse is fired on a Martin Grate in one chamber, while pulverized Munich North Plant, Block II coal is fired in the second chamber. A common tube wall separates the two chambers This plant differs from the Block. I and the combustion gases from both fir- plant in that only one firing chamber is ings combine at the top arid pass through used, with the refuse and coal burned in the same superheater, economizer, and the same furnace. The.pulverized coal is cleanup equipment. injected pneumatically into the-chamber and burns directly over the grate, contain- Capacity of the plant is 599 metric . ing the refuse. The refuse firing rate ton/day (660 ton/day) of refuse, which of 961 metric ton/day (1060 ton/day) is provides approximately 40 percent of the almost twice that of the Munich Block I total system heat input. Steam, at a gage plant, but the refuse input represents pressure of 1.79 x 107 Newton/meter2 (2600 only 20 percent of the total heat input. psig] , 540»C (1004»F), at a rate ofi9.072 x 104 kilograms (200,000 pounds) per hour is The steam conditions are the same

TABLE 3-10 REPRESENTATIVE SUPPLEMENTAL FUEL PLANTS

REFUSE CAPACITY, METRIC AUXILIARY LOCATION DATE TON/DAY TON/DAY 'FUEL COMMENTS MUNICH NORTH I 1965, 660 599 COAL TWO SEPARATE CHAMBERS STUTTGART 1966 1000 907 . OIL TWO SEPARATE i CHAMBERS MUNICH NORTH II 1967 1060 961 . , COAL ONE CHAMBER

ST. LOUIS 1972 2 x 300 2 x 272 COAL UTILITY BOILER

64 for the two Munich plants; however, the The steam generation rate for each flow rate of 3.63 x 105 kilograms (800,000 boiler is 9.28 x 10< kilograms (204,600 pounds) per hour is proportionally higher pounds) per hour at a gage pressure of 7 for the Block II plant. The heating value 6.37 x 106 newtons/meter* (925 psi) and of the coal/refuse system is higher because" a temperature of 525°C (977°F). The boiler of the smaller percentage of refuse fired, is designed to deliver the required flow which will yield a higher thermal effici- rate with refuse only, oil only, or with ency. This will account for some of the both oil and refuse. The design refuse increased efficiency in the system. The firing rate is approximately 18 metric firing configuration apparently is also ton/hour (20 ton/hour) on the Martin grate more efficient. and 20 metric ton/hour (22 ton/hour) on the roller grate. The common gases, again go through the common heat exchange stages and gas Fly ash is controlled by an electro- cleanup. Ferrous metal is recovered from stastatic precipitator, and ferrous metal the quenched residue. is removed from the cooled residue by i magnetic separation. Although the firing is different, the combination burning of coal and refuse The overall thermal efficiency of in one chamber at a ratio of 20 percent the oil-fired boilers alone approaches 90 refuse and 80 percent coal (by heating percent. If the designed refuse rate is value) is very similar to the St. Louis fired with the oil, the thermal of effi- supplemental fuel project. A schematic ciency drops to approximately 70 percent, of the Block II plant is shown in Figure and would be even lower if the refuse were 3-39. fired alone. However, the credits associated with the energy derived from the refuse more than offset the loss in overall thermal efficiency. A schematic of the Stuttgart plant is shown in Figure 3-40.

FIGURE 3-39 SCHEMATIC OF MUNICH NORTH PLANT, BLOCK II

Stuttgart Plant The Stuttgart plant is similar to the Munich North, Block I plant in that two separate chambers are used, each sharing a common tube wall. The Stuttgart plant, however, burns oil in the second chamber instead of coal. The combustion gases from the refuse and the oil enter a common convection chamber and have a common cleanup system. There are two units at the Stuttgart plant, each firing refuse in one chamber . and oil in the other. There is a difference in the grates, however. One is equipped FIGURE 30 with a Martin grate while the other is SCHEMATIC OF STUTTGART PLANT equipped with a roller grate.

65 St. Louis Supplemental Fuel Project The city of St. Louis, the Union Elec- tric Company, and the EPA started a project in 1972 to burn refuse as a supplemental fuel in one of the St. Louis area power plants. Refuse is shredded, has the magnetic materials removed, and is air classified to remove further the heavy and noncombustible materials. The lighted com- ,ft M|-HRECEIVING fflnl—HPNEUMATIC PIPELINEV bustibles, shredded to 3.8 centimeters PREPARED REFUSE (1.5 inch) nominal 'size, are transported PACKER TRUCK from the preparation facility by truck to Union Electric's Meramec Plant. The prepared refuse is fed pneumatically into the modified boilers, where it is burned in suspension with pulverized coal. Schematics of the supple- • mental fuel processing and firing -(METERING CONVEYOR^* facilities are shown in Figures 3-41 and 3-42 (41PNEUMATIC FEEDERS (4) PNEUMATIC PIPELINES Several technical problems have been encountered in the burning of the refuse. They include: TO NOZZLEmS IN BOILER FIGURE 3-42 1. Erosion in the piping of the SCHEMATIC OF REF.USE FIRING FACILITIES pneumatic -conveying system. AT ST, LOUIS SUPPLEMENTAL FUEL PLANT

BURNABLE REFUSE PACKER TRUCK FIGURE 3-41 SCHEMATIC OF PRE-CONVERSION PLANT FOR ST, LOUIS SUPPLEMENTAL FUEL PROJECT

66 2. Poor combustion of the fuel. stages. The plant will process municipal,;• sewage sludge. The combustible" portion 3. Increased bottom ash. of the refuse will be prepared as a supplemental fuel in an oil-fired boiler or con- 4. Corrosion problems with the verted to compost,- depending on the market. pneumatic refuse feeder The heavy materials plus .selected indus- • system. trial waste will be pyrolyzed,.-arid the . ••.; energy from the pyrolysis gases will be .: Addition of a new air classification system used to dry the sewage sludge. Aluminum in the pre-processing stage Is expected to and glass, are expected to be recovered .-<••. improve the overall system performance and from the pyrolysis residue. Ferrous ma-.; !. help reduce some of the above technical terials will also be 'removed ,by-magnetic; problems (ref. 3-32). A more detailed dis- separation. - .-.•'. I cussion of the St. Louis supplemental fuel '. . '• ' • . -~'T project is given in paragraph 3.3.3.3. The municipal refuse will be shredded initially to a 15.2 - 20.3 centimeter (6 - 8 inch) particle size. -This stream will, • Future Suiipplemental Fuel Projects be air cl-assified,,into .a .light (mostly com-_ (Taken from EPA''A's s 2ndd :Report to Congress bustibles) fraction and a heavy fraction ••• reference 3-20) (mostly metals, wood, rocks, etc'.). The-. , light fraction will be further shredded to. As mentioned in the EPA's second re- 2.5 to 5 centimeters (1 to 2 inch) particle port to Congress, a number of communities size and will be used primarily as a have committed themselves to a policy of supplemental fuel in oil-fired boilers. burning refuse as a supplemental fuel in If a boiler was designed originally to be- conventional boilers. The proposed plans fired with either coal or oil, there will., are in various stages of completion, and be both bottom ash handling equipment the following.is a description of the • and particulate control equipment such as planned supplemental fuel projects. electrostatic precipitators. Ames, Iowa - The city is considering using The system as conceived will process shredded solid waste as a supplemental fuel 454 metric tons (500 tons) of municipal in a utility boiler. A pre-processing refuse, 13.6 metric tons (15 ton's)' of"' system is expected to be operational in industrial waste, and 209 metric tons late 1974. (230 tons) of sewage sludge per day. The plant is expected to be in operation in Albany, New York - The city has made a 1977 commitment to Burn refuse as a supplemental fuel. Market studies are currently Memphis, Tennessee - A 1361 metric ton underway to determine the potential users (1500 ton) per day plant is being proposed for the recovered products and steam.' The at a cost of $8 million, which will pro- system is expected to be' operational in duce a supplemental fuel to be fired in 1977. : steam boilers. The present concept includes a front end system which will separate Monroe County, New York - Approximately ferrous metal, aluminum, and glass. $9 million .dollars have been? appropriated by the state of New York as its share of The combustible portion of the refuse a project to burn refuse as fuel in a will be prepared for firing with coal in Rochester Gas and Electric Utility boiler. a TVA boiler. The savings in coal costs Plans are also being made to extract would be approximately $750,000 per year paper for resale in the refuse preconver- at current energy costs. Another $1 mil- sion stages. lion potentially could be received from the sale of the recovered metal and glass New York, New York - Two projects are al- (ref. 3-1). ready underway in the supplemental fuel area in New York city. One project, in the engineering design stage, is to refit 3,3.3 INCINERATION SYSTEM ALTERNATIVES a Consolidated Edison boiler to handle SELECTED FOR"FURTHER ANALYSIS shredded refuse as a supplemental fuel. The other project for which dollars have been appropriated is a feasibility study 3.3.3.1 WATER-WALL INCINERATOR - SAUGUS, for the design of a new utility boiler MASS. FACILITY' that will burn 50 percent refuse as a solid fuel. The state has appropriated $21 million for its share of the supple- 3.3.3.1.1 Technical Description mental fuel projects. Wilmington, Delaware - A cooperative pro- The Saugus plant is being constructed gram between the Federal government and on a site adjacent to the Salem Turnpike the state of Delaware for a resource re- just south of theSaugus River. It is de- covery plant is in the initial design signed to burn 1008 metric tons (1200 tons)

67 of refuse daily from 16 communities around road fill or a construction material. Saugus, Massachusetts, with a combined population of about 500,000 (ref. 3-1 and The Saugus plant output is steam. 3-28). Refuse-fired steam boilers convert the combustion heat into steam. The steam is Generally speaking, the refuse- used to generate electrical power at a energy plant shown in Figure 3-43 operates nearby General Electric plant. in the following manner. Refuse arrives in trucks which proceed first to a weighing Flue gases and fly ash created during area, where they are placed on scales to combustion are .captured during the process. determine the quantity of incoming refuse. The refuse-fired boilers cool the gases From there, the trucks go to a refuse hand- as they produce steam. The gases then flow ling building where the-refuse is trans- through electrostatic precipitators, where ferred to a large-capacity storage pit. the particulate matter is removed. The Bulky objects are fragmented by a hammer- cleaned gases are then released to the mill. The air within the refuse handling atmosphere through the stack. building is drawn .off and used as combustion air, which prevents the escape of odors from the plant. Plant Description From the storage pit, refuse is trans- The Saugus plant is unique in two ferred by traveling overhead cranes to the ways: It is the largest Von Roll refuse bpiler feed hopper. It then goes to the burning, steam-generating incinerator to combustion chamber which contains a stair- be constructed in this country, and it is -dike grate system. Three inclined, recip- privately financed. rocating grates dry, tumble, and break up the refuse to insure complete combustion. The refuse storage pit will have a normal capacity (from the bottom of the Combustion temperatures ranging from pit to the reception area floor) of 2476 871-to 982°C (1600 to 1800"F) consume most metric tons (2730 tons). This amount of of the refuse, as well as odors, within refuse will operate the incinerators for the*combustion chamber. .Of primary impor- approximately 2.3 days. This storage is tance, refuse is the only fuel required. necessary since the plant will be.required to provide steam at times when no refuse The ash residue, equal to about one- is being received. Maximum storage will tenth the'original refuse volume, is quench- be 6077 metric tons (6700 tons), enough ed in recycled water. It may be sold for storage for approximately 5.6 days of

TO STACK

FIGURE 3-43 SCHEMATIC OF WATER-WALL INCINERATOR AT SAUGUS, MASSACHUSETTS

68 '.operation. Plant Operation \ The building that houses the refuse The refuse trucks, upon entering the pit and charging floor also contains a plant, will be weighed and directed to the shre'dder for bulky items and two overhead unloading area. Two floor-men will weigh cranes. The shredder is surrounded by and direct trucks to and from the unloading concrete walls for noise suppression. The area. Two floor-men will weigh and direct shredder has a horizontal drive shaft and trucks to and from the unloading bays at is equipped with a reversible force feed the edge of the refuse storage pit. The mechanism. The shredder will have a capa- floormen will work one ten hour shift, five city of 18 to 23 metric tons (20 to 25 tons) days per week. All open trucks will con- per hour. A steam spray system provides tain mostly bulky materials. These trucks fire protection for the shredder. will be directed to the pit area near the shredder. Two cranes with air-conditioned cabs will lift refuse from the refuse storage One of the two cranes will be utilized pit to the incinerator feed hoppers and to load the incinerator hoppers, three shifts will' feed bulky items into the shredder. per day. The other crane will feed bulky Each crane has a rated capacity of 11.8 items into the shredder and move refuse in metric tons (13 tons). It is anticipated the pit so that the crane that is operated that one crane will operate full time. The 24 hours per day can reduce its retrieving refuse building will also house the feed time. hoppers, furnances, force draft fans, shops, and service area. The refuse in the feed hopper will serve as a seal to the incinerator and Each unit will be equipped with three prevent flame flashbacks. Should the re- oil burners. These burners will be used fuse level in the feed hopper reach the un- when the refuse does not have sufficient safe level, a warning sound will be given heating value to generate the necessary the crane operator. heat. When operating on No. 6 fuel oil and refuse or on fuel oil alone, the plant The refuse from the feed hoppers will '•' can produce 1.81 x 105 kilograms (400,000 be fed down onto the grates of each inciner- pounds) of steam per hour. ator. As the refuse moves down the first inclined grate, the refuse will be dried The plant is equipped with two and combustion will be initiated. The electrostatic precipitators. The precipi- refuse will then drop, as the result of •.-'.• tators were designed to remove particulate reciprocating grate motion, onto the second matter from the stack gases at an efficiency grate, where most of the combustion takes of 97.5 percent. The stack is 54..3 meters place. The refuse then drops onto the (178 feet) above ground. Ash and dust third grate where complete burnout will from the boilers and precipitators are con- occur. The ash remaining after burnout and. veyed to the 'ash conveyors serving the the ash which falls through the grates, will incinerators. be collected in hoppers that will' discharge onto the ash quench conveyor. The plant has two 5.4 x 10^ kilograms (120,000 pounds) per hour oil fired boilers. Primary combustion air required for These oil fired back-up boilers can generate combustion will be supplied to the underside steam at the same pressure and temperature of the grates. The air intake will be as the incinerator boilers. The back-up located in the refuse building. This boilers will be used only when the incinera- arrangement will allow offensive odor to tor boilers cannot meet steam demands. be pulled into the incinerator and destroyed. These two boilers will have a common stack that is 3 meters (ten feet) above the The incinerators are designed to operate highest roof in the plant. with 100 percent excess air to insure control of the flue gas temperature between A steel bridge across the Saugus 871-1093°C (1600-2000°P). The secondary River connects the steam generating plant air required for temperature control is with the General Electric power-plant. supplied to the furnace above the grate. This bridge will transfer steam to the G. The secondary air will help complete com- E. plant and condensate, fuel oil, and bustion. utility power to the Saugus Plant. The total electrical power requirements for the The flue gases upon leaving the furnace incineration plant is 3000 kilowatts. will pass through the superheater, generator section and economizer, and then to precipi- An office building is constructed at tators. The total steam production is ex- the Saugus Plant. This building has a pected to average approximately 1.36 x 10^ reception area, administrative offices and kilograms (300,000 pounds) per hour. Approx- meeting room. A parking lot for 40 cars imately 6.8 x 103 kilograms (15,000 pounds) is provided at the plant. per hour will be required for plant auxi-

69 liaries at Saugus. plant has a high capital cost are: General Electric's Steam Requirements 1. Construction of a utility bridge across the Saugus River between The General Electric Company has re- the plant and the General Electric quested that steam be provided at a gage power plant. pressure of 4.48 x 106 newton/meter2 (650 psi) and at a temperature of 441°C (825°F1. 2. There are two back-up boiler units The steam demand is not constant over a which are used for firing oil 24 hour period, but varies from a minimum only when the supply of refuse of 9.1 x 104 kilograms/hour (200,000. is not sufficient to produce the pounds/hour) to a maximum of 1.8 x 105 required steam required by Gen- kilograms/hour (400,000 pounds/hour). eral Electric. Hourly rates and the percentage of time they are required, as established by 3. The plant has a large storage . General Eelctric, are shown in Table 3-11. capacity for the refuse, and has room for expansion to handle up to 2180 metric tons' (2400 tons). TABLE 3-11 GENERAL ELECTRIC S STEAM DEMAND FROM THE SAUGUS PLANT TABLE 3-12 COST DATA ON SAUGUS, MASS,, WATER-WALL INCINERATOR DEMAND COST ANALYSIS KG/HR LB/HR PERCENT OP TIME Assumptions: 181,440 400,000 5 Average Daily Refuse Burned: 158,760 350,000 10 1092 Metric tons (1200tpd) 136,080 300,000 50 Average Annual Refuse Burned} 90,720 200,000 35 382,200 metric tons (420,000 tons) (350 days of 24 hours each) ' TOTAL 100 Steam Generation from Refuse Only: 1129 million kilograms (2486.4 million Ibs.) Net Steam Production per Year: 3.3.3.1.2 Economic Data 1072 million kilograms (2362 million Ibs.) (5% of the steam is used in plant) The Von Roll waterwall incineration Steam is sold to General Electric at' process with steam recovery from the solid $1.50 per 454 kilograms ($1.50 per waste requires a large amount of capital lOOOlbs.) and has high'operating costs. What follows Financing is private with: is a cost breakdown of such a process 70% debt at rate of 8% currently under construction at Saugus, 30% equity at rate of 20% ; Mass. The reported total cost is Plant life: 20 years $31,000,000 for the plant at an operating capacity of about 1090 metric tons (1200 Annual capital recovery factor at effective tons) per day. rate of: (8%)(.70) + (20%)(.30) - 11.6% is 0.133 A cost analysis of the Saugust plant is presented in Table 3-12. The cost Annual Cost: estimates were made primarily from two Capital (0.133)(30,417,000) = 4,055,460 sources. One of which is an EPA report operating (exclude interest) 1,855,000 prepared by Metcalf and Eddy, Inc. in Total Annual Cost $5,910,460 1972, (ref. 3-33). In this report seven alternative options were proposed and Gross Annual Cost - Annual Revenue = evaluated for a plant capacity of either Net Annual Cost 348 or 555/metric tons of refuse per day At Steam Price of $1.50 per 454 (384-612 tons per day). The other source kilograms ($1.50/1000 Ibs): of information is a talk presented by S. $2,367,460 E. Stanrod of the Rust Engineering Company at the U. S.: Japan Energy Conservation Gross Cost per ton of Refuse = (5,910,460)/ Seminar in San Antonio, Texas, 1974 (ref. (420,000) = $15.50/metric ton 3-34). All cost estimates are 1975 ($14.07/ton) dollars using the Engineering News Record Index of 1375. Net Cost per ton of Refuse = $6.16/metric ton ($5.59/ton) Comment Some possible reasons that the Saugus

70 TABLE 3-12 (CONTINUED) PROCESS NAME: Saugus Waterwall Incineration Plant DATA SOURCE: References 3-33 and 3-34 CAPACITY IN TONS/DAY: 1092 metric tons (1200 tpd)

DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land Not available All estimates based on ENR Index Preprocessing Eqmt. $ 1,310,000 1375 (100 for the year of 1921), Processing Eqmt 13,390,000 and included 10% allowance for Postprocessing Eqmt 85,000 general conditions. Utilities 1,438,000 Building & Roads 4,701,000 Detail estimates, given by Metcalf Site Preparation . 1,375,000 & Eddy, Inc. for a 350 metric tons , Engr. ,&, R & D 5,608,000 per day boiler plant (385 tpd), Plant 'Startup Included were used. Working Capital 1,000,000 Misc.: Crossing bridge 1,375,000 Others 123,000 TOTAL $30,417,000

OPERATING COSTS ($ PER YR.) . Maint. Material $ 144,000 (1) Assume credits from scrap ;Maint. Labor 69,000 metals and other materials Dir. .Labor 478,000 will pay for the disposal of Dir. Materials 78,000 residues. Overhead 143,000 Utilities 345,000 (2) Fuel cost is not considered Taxes 1%% of fixed capt. 451,000 because: Insurance %% of capt. 147,000 a) quantity needed will depend Interest 1,703,000(3) on the shortage of refuse, Disposal of Residue (1) and Payroll Benefits Not available b) credit from steam generated Fuel (2) when burning fuel oil will Misc.: not be considered either. TOTAL $ 3,558,000 (3) Assume 70% debt at 8% rate, and 30% equity at 20% rate. Thus the interest paid annual- (8%)(70%)($30,417,000)= $1,703,000

CREDITS ASSUMED ($ PER YR.) $ 3,543,000 see "Resource Recovery Data"

Fuel: Steam production at 1200 tpd, Liquid 134,000 kilograms/hr Gas (296,000 Ibs/hr) or Solid 1129 million kilograms/yr Power: (2486.4 million Ibs/yr) Steam $ 3,543,000 Electricity 5% of the steam is consumed in Hot Water plant. Magnetic Metals t Nonmagnetic Metals Net steam production: 1072 mil- Glass lion kilograms/yr. (2362 million Ash Ibs/yr) Paper Other: Sold to General Electric at $1.50 kilograms ($1.50 per 1000 Ibs), the net revenue of steam is estimated at $3,543,000 annually.

TOTAL($ PER YR.) $ 3,543,000

71 3.3.3.2 CPU-400 ENERGY CONVERSION SYSTEM bustor in the system is a pressurized, fluidized bed using sand as the heat transfer medium. Auxiliary oil is burned 3.3.3*2.1 Technical Description initially to heat the sand, but the combustion process sustains itself once the I bed is heated. The prepared refuse is The CPU-400 is a solid waste disposal pneumatically fed into the combustor, system which converts the energy in the where the sand is in suspension from the refuse to electrical power. The system buoyant effects of the compressor air. uses a fluidized bed incinerator as the The temperature within the bed is appro- combustor and a gas turbine-generator to ximately 761°C (1400°F) . produce the electrical power. The CPU-400 process has been demonstrated by a pilot The combustor is a vertical shaft plant with a capacity of 63.5 metric ton/ bed, 6.7 meters (22 feet) high and appro- day (70 ton/per day). A schematic of the ximately 2.4 meters (7 feet) inside dia- CPU-400 process is shown in Figure 3-37. meter. The combustion area itself is The prototype plant would be of modular lined with firebrick, and Kawool insula- design, each unit having a capacity of tion separates the firebrick from the approximately 136 metric ton/day (150 sides of the vessel. The starter bed is ton/day). The following is a brief af 16 mesh sand and is 0.6 meter (2 feet) description of the CPU-400 system as dis- deep. cussed in references 3-2, 3-31, 3-35, 3- 36, arid 3-37. Particle separators — Since the gas stream contains particles of sand as well Pre-Processing . as ash and other particulates, a rigorous cleanup system must be employed before Incoming packer trucks deposit the the gas can be expanded through the tur- refuse in the receiving area where front bine. The pilot plant has three particle end loaders push it to the shredder con- separators, and it is assumed that the veyors. The shredders will be sized to prototype plant will also have to employ handle a greater capacity of refuse than a similar cleanup system. will normally be required in the system operation, so this gives a redundant The first separator is designed to feature-to the shredding process. The remove the larger particles of sand and shredders are a vertical axis type, with aluminum, plus some ash. Some of the the prototype plant expected to use two aluminum is in the molten condition, and 74.6 killowatts (100 horsepower) shredders some care has to be taken to prevent the for each combustor module. aluminum particles from impinging on the sides of the cyclone separator and form- The shredded material is then con- ing an aluminum oxide deposit. The first veyed to an air density separator, where separator is approximately 2.4 meters the heavy and light materials are separat- (7 feet) in diameter. ed. Typically, the lighter fraction is 83 percent of the refuse stream and con- The second and third cyclone separa- sists of the light combustibles plus tors are designed for removal of the ash about 15 percent inert materials, such as and smaller particles in the gas stream. metal foil and sand. The heavy stream There are 48 tubes, 15 centimeters (6 contains about 25 percent combustibles inches) in diameter, in the second separa- along with the inert material and metals. tor and 100 tubes, 9 centimeters (3% inches) in diameter in the third. Both The light stream is conveyed pneu- separators empty into a common ash hopper, matically to the storage bin. Two eye. and pneumatic vibrators are used to keep clones separate the dust-laden air from the ash flowing into the hopper. the refuse, which is stored until ready for the combustor. The clean-up stages are very critical to correct operation of the CPU-400 The heavy fraction is then processed system. The maximum particle size enter- for removal of the saleable materials. A ing the turbine should be much less than magnetic separator removes the magnetic 5 microns to prevent erosion of the tur- materials (primarily ferrous); glass and bine blades. Performance curves given in stone are then removed, so the final Chapman and Wocasek (ref. 3-31) indicate stream ideally should consist of aluminum that the cyclone separators are capable and other metals. Aluminum is removed of removing the larger particles,- but for sale, and the remaining metals may plugging of the tubes has been a problem also be sold. The aluminum is separated during model testing. Assuming the cy^ by a newly developed process using dry clone separators perform as designed, the electromagnetic separators. expected turbine blade life would be a minimum of two years. Power Generation System Turbine-Generator Subsystem — This Fluidized bed combustor — The com- subsystem consists primarily of the

72 turbine-compressor and electrical power concept for solid waste disposal and generator. Cleaned air from the combustor energy recovery. The basic principles be- enters the gas turbine at a temperature of hind the system are sound—a good front- " approximately 761°C (1400°F). The energy end processing system for materials re- derived from the gas in expanding through covery and efficient material classifica- the turbine drives a compressor, which protion, a high heat transfer combustor in vides the pressurized air for the flui- the fluidized bed, and a saleable end pro- dized bed'combustor. The pilot plant uses duct, electricity. The system is fully a two-stage gas turbine, with the second automated for good process control and stage driving the 1000 killowatt generator. produces few pollutants. The pilot plant operates at a gage pressure of 2.55 x 105 newton/meter2 (37 psig) Unfortunately, the system to date has while the prototype units are scheduled not performed as expected. The original for a gage pressure of 9 x 105 newtons/ design of the fluidized bed was poor and meter2 (130 psig) operation. This higher had to be redesigned. The gas cleanup pressure should increase the operating system has to remove particulates to stand- efficiency and the electrical output per ards far more stringent than EPA require- ton of, refuse incinerated. ments for-proper operation of the turbine, and the cleanup must be accomplished at Automatic^ Control System — The CPU- high temperatures. The gas cleanup levels 400 employs a process control computer for required are beyond the .current state of controlling the refuse feed throughout the art in cyclone separators, both for the the system. Precise incineration control particulates and for the molten aluminum is required to maintain the turbine inlet in the gas stream. The molten aluminum temperature within specified limits. eventually solidifies as aluminum oxide Manual control of the system is also pro- and causes these solid deposits throughout vided. The process computer also contains the system. Deposits on the turbine blades a mass data unit for storage of data and can also cause a decrease in operating life various input-output devices and subsystems. of the turbine. More developmental work is required on the gas cleanup system, and Pilot Plant System Performance — Ex- it is possible that the stream cannot be tens iv¥~te^FIn^~Kais~5een~~con3ucted~6n the cleaned sufficiently for sustained opera- fluidized bed by itself, and separate test- tion of the turbine, (ref. 3-31) ing has been conducted on the turbine- generator system using auxiliary air. The Another potential problem area is the pilot plant, however, has been operated as fluidized bed combustor. Although the a complete system only for limited periods technology of fluidized beds is well known of time. from the petrochemical industry, there is a very basic difference in the consistency At startup, auxiliary oil is burned of the feed. The output from municipal to bring the system up to temperature. The refuse, even after shredding and air; classi- turbine combustor is also fired using fication, is a heterogeneous mixture of diesel oil, and the turbine-generator sys- paper, aluminum, cardboard, and other light tem is operated separately and brought up substances. This fact could lead to prob- nearly to full power on the auxiliary lems in maintaining the fluid nature of system. Air from the compressor is then the bed. If proper operating temperatures diverted into the fluidized bed. The and velocities within the bed are not main- whole system is then stabilized at operat- tained, large "chunks" could be formed in ing temperature, pressure, and power out- the bed, and ultimately the bed itself put before switching over to the fluidized could solidify. (ref. 3-31) bed operation. The system startup requires approximately five hours. As pointed out by Schulz (ref. 3-21) generating electrical power on site The pilot plant was operated for a escalates the capital costs and requires a short period (48 hours) at low pressure balanced operation of two unrelated func- during the acceptance test, but no power tions - refuse incineration and electrical was generated. During the acceptance power generation. A high pressure fluidized test the incinerator system was controlled bed is also a complicating factor. automatically and operated within 17°C (30°P) of the selected temperature.-The In summary, the CPU-400 pilptjplant combustion efficiency was greater than 99 to date has not demonstrated sufficient• percent. The solid waste feed rate during overall system reliability to justify the test was 18.6 kilograms (41 pounds) building a prototype plant. per minute. A typical high pressure test with 45.4 kilograms (100 pounds) per minute 3.3.3.2.2 Economic Data for CPU-400 of refuse is expected to generate approxi- System mately 1000 kilowatts of electrical power. The three sources of data used here concerning the C.P.U. process are Chapman Technical Evaluation of CPU-400 Process and Wocasek, (ref. 3-31) Schulz et.al. (ref. 3-21), and Midwest Re'search Institute The CPU-400 system is an advanced Report (ref. 3-28).

73 The data presented from reference 3- in Roberts, Sommerlad, et.al., (ref. 3-25). .31 are shown in Table 3-13 and are based One of the final recommendations by Vaughan on a presumed 544 metric ton/day (600 was that metal temperatures be kept less ton/day), 3 power module CPU system. It than 204"C (400°F), which will not be is assumed that the electric power gives possible in the energy recovery systems. a credit of 8 mills per kilowatt hour. Long term tests will be required to assess Here the economics of considering the fully the impact of the corrosion caused by CPU 400 for handling MMR is possibly dis- PVC, because the rate of corrosion is torted by crediting it for handling apparently not a linear function of PVC sewage solids. In the economic data, the content or temperature; further, the rate process is given a large credit for sewage of corrosion decreases with time. This sludge disposal. means that short term corrosion tests cannot be extrapolated with any degree of The data presented from the Midwest accuracy to determine long-term corrosion. Research Institute Report are based on a Vaughan also discusses the corrosive 907 metric ton/day (1000 ton/day) 365 days resistance of several different types of per year system. It is assumed that the stainless steel, some of which are much electric power gives a credit of;6.5 less susceptible to corrosion caused by mills per kilowatt hour. PVC content in refuse. European incinerators have been burning refuse for years with no appreciable corrosion experienced, 3.3.3.3 ST. LOUIS SUPPLEMENTAL FUEL although the PVC content in the refuse is probably less than .the U.S., on the average. Since the refuse is burned with the coal 3.3.3.3.1 Technical Description in St. Louis, the detrimental corrosive effects should be less. Additional information on corrosion is included in Astrom, After a thorough review of the exist- (ref. 3-24, and Fernandes and Shenk (ref. ing boiler facilities owned and operated 3-39). ,by the Union' Electric Company in the St. Louis area, Horner and Shifrin, Inc., Another potential problem involves Consulting Engineers, recommended modifi- hydrochloric acid (HC1) . If hydrogen cation of two of the existing boilers at chloride reacts with water, either in the Meramec Plant. The facility uses water-quenching systems or in systems where coal burning boilers, each equipped with the gas is allowed to cool down below the four coal pulverizers with a capacity of dew point of water, then hydrochloric acid 1.88 x 104 kilograms/hour (41,500 pounds/ will be formed. This acid is highly reac- hour). The coal is fed to the 30.48 tive and will be extremely corrosive to the centimeter (12 inch) burners by a rotary- structural steel and pipes in the system. type coal feeder. Other polymeric materials could also contribute harmful corrosive gases in the Each boiler had to be modified to incineration process. If, electrostatic accommodate the refuse, which was shredded precipitators only are used and if the to a size of 2.54 to 5.08 centimeters (1 gas temperature is kept above 177°C (350°F) to 2 inches). Refer to Figure 3-42 for the HC1 acid attack will not be a problem. the refuse firing system schematic. The This point is discussed in Aubin (ref. Meramec plant was equipped to burn natural 3-40) . gas, so the natural gas burners were modified to accept the prepared refuse. Pneu- matic conveyers are used to blow the refuse Pollution - The Union Electric plant into the boiler, where it'is burned in was already equipped with pollution control suspension with the coal. • devices - electrostatic precipitators, for particulate removal. Although more parti- Technical Implications of Burning Refuse culates will probably result from the supplemental burning of refuse, the total Corrosion - The potential corrosive impact is not known at this time. Both effects of burning refuse in a boiler is particulate and gas emission tests were known, and the modified boiler has not been run by the EPA in late 1973, and the preliminary results did not disclose any in operation long enough for a .full evalua- serious problems.- The results are re- tion. Experience from pure incineration ported by Sutterfield (ref. 3-41). While shows that the burning of refuse is poten- the refuse may contribute to additional tially more corrosive than the burning of particulates, the amount of gaseous po fossil fuels. Polyvinyl chloride (PVC) is pollutants could be reduced from the refuse one of the possible constituents of refuse as a fuel. Consider SOX, for example. that could be extremely corrosive. The The amount of sulphur present in the coal results of a PVC corrosion investigation burned in St. Louis sometimes exceeds 2 in incinerators is summarized by Vaughan, percent. This contributes greatly to the et.al. (ref. 3-38) and is also discussed amount of SOX pollution. The amount of

74 TABLE 3-13 (A) . • ECONOMIC DATA - CPU-nOO SYSTEM PROCESS COST SHEET PROCESS NAME: CPU-400 with Material Recovery DATA SOURCE: Reference 3-31 CAPACITY IN TONS/DAY: 544 Metric tons (600tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt $ 700,000 Material Recovery Processing Eqmt Postprocessing Eqmt Utilities Building & Roads Site Preparation 8,400,000 Erigr. & R & D Plant Startup Working Capital Misc.:

TOTAL $9,100,000

OPERATING.COSTS ($ PER YR Maint. Material Maint. Labor Dir. Labor Dir. Materials Overhead Utilities Taxes Insurance Interest Disposal of Residue Payroll Benefits Fuel 880,000 Operating costs with- Misc.: 100,000 >ut Material recovery Material recovery Operating costs TOTAL $ 980,000

CREDITS ASSUMED ($ PER YR) $1,650,000

DOLLARS/YR. COMMENT

Fuel: Liquid Gas Solid Power: Steam Electricity $ 760,000 Hot Water Magnetic Metals 340,000 Nonmagnetic Metals 320,000 Aluminmm 200,000 Glass 90,000 Other $120,000 Ash Glass, includes sand Paper Other: 140,000 Sewage sludge credit TOTAL ($ PER YR.) $1,650,000

75 . TABLE 3-13 (B)

PROCESS NAME: CPU-400 Without Material Recovery DATA SOURCE: Reference 3-31 CAPACITY IN TONS/DAY: -544-Metric tons (600 tons)

DOLLARS COMMENTS I

CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt Processing Eqmt Postprocessing Eqmt Utilities ; Building & Roads Site Preparation Engr. & R & D Plant Startup - . Working Capital Misc.: •

TOTAL $8,400,000

OPERATING COSTS ($ PER YR) Sewage Sludge Disposal Credit: Maint. Material $ 400,000 A population generating 179,000 Maint. Labor . 400,000 metric tons/yr (197,000 ton/yr) of Dir. Labor solid waste will generage .about 5079 Dir. Materials .' metric tons per year of sewage Overhead .. . solids. .(5600 tons) Utilities . . 80,000 Income @ $28/dry metric ton of sewage Taxes . - solids is $140,000. Electrical Insurance Income Credit: Interest 95 x 106 kw.hr./yr. @ 8 millsAw.hr. Disposal of Residue Payroll Benefits Fuel Misc.:

TOTAL $ 880,000

$ 140,000 Sludge Disposal Credit CREDITS ASSUMED ($ PER YR) 760,000 Electrical Income .

TOTAL $ 900,000

76 TABLE 3-13 (c) PROCESS NAME: CPU-400 DATA SOURCE: Reference 3-28 . CAPACITY IN TONS/DAY: 907 metric tons/day (1000 ton/day) 365 days/yr.) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt Processing Eqmt Postprocessing Eqmt Utilities Building & Roads Site Preparation . Engr. & R & D - . > - Plant Startup " Working Capital Misc.:

'TOTAL $9,306,000 Jith materials recovery OPERATING COSTS ($ PER YR) • Maint. Material Maint. Labor Dir. Labor Dir. Materials Overhead Utilities Taxes Insurance Interest Disposal of Residue Payroll Benefits Fuel Misc.:

TOTAL $1,176,000

CREDITS ASSUMED ($ PER YR) $2,106,000

DOLLARS/YR. COMMENT

Fuel! Liquid Gas Solid Power i Steam Electricity $1,007,000 Hot Water 256,000 Magnetic Metals -548,000 Aluminum: $365,000; Nonmagnetic Metals Other: $183,000 Glass 131,000 Ash 164,000 Includes sand Paper O.ther: . TOTAL ($ PER YR.) $2,106,000

77 TABLE 3-13 (D)

PROCESS NAME: CPU-400 DATA SOURCE: Reference 3-21 CAPACITY IN TONS/DAY: 907 metric ton/day (1000 ton/day)

DOLLARS COMMENTS'

CAPITAL COSTS (TOT. S) Land Preprocessing Eqrat Processing Eqmt Postprocessing Eqmt Utilities Building & Roads Site Preparation Engr. & R & D Plant Startup Working Capital Misc. t

TOTAL $17,000,000

OPERATING COSTS ($ PER YR] Refuse Preparation Maint. Material 365 x 1000 x 4.43 - Maint. Labor $1,616,950 Dir. Labor Combustion Process Dir. Materials 365 x 1000 x 3.53 =• Overhead $1,288,450 Utilities Materials Recovery Taxes 365 x 1000 x 1.10 = Insurance $401,500 Interest Disposal of Residue 365 x 1000 x .70 = Disposal of Residue $ 255,500 Payroll Benefits $255,500 Fuel Misc.: other 3,306,900 TOTAL: $3,562,400

TOTAL $ 3,562,400

CREDITS ASSUMED ($ PER YR) $ 1,697,250|

DOLLARS/YR. COMMENT

Fuel: Liquid Gas Solid Power: Steam Electricity $1,368,750 365 x 1000 x 3.75 Hot Water 255,500 365 x 1000 x .70 Magnetic Metals Nonmagnetic Metals Glass 63,999 365 x 1000 x .20 Ash (Glass or Vitreous Paper Frit) Other: TOTAL ($ PER YR.) $1,697,250

78 sulphur in refuse is extremely small, with Refuse Processing a maximum content usually considered 0.2 percent (ref. 3-42). Burning refuse with The refuse is processed at a facility coal, therefore, should reduce the overall several miles from the Meramec plant and SOX stack emissions. The highly variable transported by truck to.the power plant. nature of refuse makes it difficult to *• A number of changes and modifications have predict the additional amounts of CO and been made since the initial installation, NOX that will result, but if good combus- the most notable being the addition of an tion is achieved in the boiler, then the . air density classifier. The processing resulting CO and NOX emissions should not described herein is the plant operation as differ greatly from that of burning coal the beginning of 1974. only. There are no emission standards at present for HC1 and some of the other The schematic of the pre-conversion gases which may result from burning re- plant is shown in Figure 3-41. The raw fuse, and some further consideration refuse from packer trucks is discharged should be given to these possible pol- in the refuse receiving building, where lutants. front-end loaders push the refuse to a rece'iving belt conveyor. The receiving Ash Content - The content of both the conveyor has a variable speed to control fly ash and the bottom ash will change as the rate of feed to the shredder. a result of burning refuse as a supplemental fuel. The refuse will probably The refuse is dropped to a feeder contain some non-combustibles which will where it is shredded by a hammermill to a drop through unburned. The amount of nominal 3.8 centimeter (1*5 inch) size. bottom ash has increased the volume of After shredding the refuse is now conveyed residue, but the facilities are adequate to a surge bin, which controls the rate to handle the increase. Better burning is • of feed to the air density separator (ADS). now achieved since the air density classi- The ADS was added to'separate the lighter, fier has been added to the refuse process- ; combustible material from the heavier ing. fraction since only the lighter fraction will go to the boiler to be burned, this The fly ash is collected by electro- . will improve the overall burning charac- static precipitators and sold to a cement teristics of the supplemental fuel and manufacturer. The firing of the refuse reduce the amount of bottom ash and resi- with the coal has not changed the quality due. The pipe wear problem should also of the ash substantially, and it is still decrease somewhat and the air classifica- being sold to the cement manufacturer. tion should provide better pneumatic transport of the fuel. The coal" bottom ash was previously used by the Missouri State Highway Depart- The heavy fraction is now conveyed ment on snow-covered roads. The burning • to a magnetic separator to separate the of refuse has. changed the bottom ash, as 1 magnetic and non-magnetic materials. At it now contains large amounts of unburned the present time the magnetic materials wood, metal, and other particles. The • are sold, and the non-magnetic residue is bottom ash is now unacceptable for appli- • land-filled. cation on roads. The air classification system which has been added at the refuse The lighter refuse and conveying air processing station is expected to improve are now run through a ..cyclone separator the overall combustion in the boiler and which separates the two. The refuse drops reduce the amount of unburned materials to a conveyor, where it is conveyed to a in the bottom ash. storage bin. The air is discharged to the atmosphere. Erosion Effects - One of the biggest problems encountered in the handling of the The refuse is unloaded from the stor- refuse has been the erosion or abrasion of age bin by means of a twin screw unloader. the pneumatic pipes carrying the refuse Large packer trucks'then transport the to the boilers. The abrasion has been shredded and air classified refuse to the particularly bad in the pipe turns and Meramec power plant. elbows. The transfer pipes are made of mild steel, and this problem could ap- • Technical Evaluation parently be corrected by installing stain- The firing of prepared refuse as a less stell elbows and pipes. To date, supplemental fuel in.a coal-fired boiler however, the replacement pipes have has only been a partial success to date. apparently also been mild steel, according The original concept o'f 272 metric ton/day to Sutterfield (ref. 3-41). (300 ton/day) of refuse.has currently been reduced to 181 metric ton/day (200 A very good reference on the St. Louis ton/day) and this latter amount has not been project is included in an EPA report by sustained for a long period of time. Some Lowe (ref. 3-43). of the problems have been attributed to

79 the front-end or pre-conversion system, process is one of the lowest of all pro- while other problems have been with the cesses considered in this report. firing facility itself. Exhaustive environmental tests have not yet been con- This section presents Process Cost ducted; therefore, the environmental im- Sheets for all data sources used. A net pact has not been fully evaluated. Speci- cost per ton has been computed for each fic problems at the processing plant are process configuration. These sources do discussed by Sutterfield (ref. 3-41) and provide a very good estimate for the costs include everything from conveyor belt of a Horner-Shifrin type process. One problems to housekeeping problems. The should nevertheless be careful when study- type of problems encountered have caused ing the data reproduced in this section excessive delays and a great deal of since all data sources use different assump- down time, but the problems are not in- tions. For example, some sources consider surmountable from the technological view- the costs of residue disposal, while others point. They represent typical problems do not. Some sources use cost data in 1969 which might be encountered in start-up dollars while others have them in 1972 of any complex plant. dollars. There are many other assumptions that differ from source to source, but the The problems at the firing facility most important of these are summarized in have been connected primarily with the the pages that follow. pneumatic transport of the prepared refuse. Problems with the air lock mechanism and erosion of the pipes, parti- .Comments on Table 3-14 cularly in the elbows and turning sections, have caused some down time. The air The cost data given in the following lock problems have been greatly reduced Process Cost Sheets are estimated costs by the addition of the air density separa- for the Horner-Shifrin Supplementary fuel tion system at the refuse processing plant, process as applied to the St. Louis, and the pipe erosion could be reduced by Missouri, metropolitan area. The source 'abrasion-resistant pipes. The problems, for this data is an EPA report prepared by again, are not technologically insurmount- Horner and Shifrin (ref. 3-32). able. As mentioned earlier, the environ- •mental impact has not been fully determined, The following are cost parameters which but present technology is sufficient to were used in reference 3-32. clean up the exhaust gases, if the existing system is not adequate. Interest rate, % 5 As discussed in Schulz, et.al. (ref. Useful life assumed, 3-21) the use of prepared refuse as a years supplemental fuel is a viable method of energy recovery and refuse disposal in Land Costs, $/acre No___t specified_____ coal fired boilers. Gas or oil-fired joule¥ boilers would have to be modified at con- Heating value of refuse 1.2 x 1010metric ton siderable capital expense to add bottom Btu ash handling facilities and emission con- (10 x 1Q6 ton) trol devices. Although the cost of the supplemental fuel varies from location to Residue disposal costs, location, depending on local energy $/ton Not considered credits and the value of the recovered resources, supplemental'fuel incineration Waste residues to be in coal-fired, boilers is one of the landfilled, % of cheapest methods of refuse disposal, input refuse Not considered competing quite favorably with cheap landfill disposal. Net credit given for recovery of metal $/ton Not considered 3.3.3.3.2 Economic Analysis Recovery rate for metal, % of input Not considered The Horner Shifrin supplementary fuel Net credit for use of process is one of the conversion processes waste as supp. fuel. $0.285/109 joules requiring a small capital investment per daily ton of capacity; this is on the ($0.30/106 Btu) order of $7000 - $8000 per daily ton. The capital investment only requires some re- Fraction of input refuse latively minor modifications to existing that is converted to boilers, so that they may accept prepared suppl. fuel .9845 refuse for burning along with some other fuel, usually coal. . As will be seen This report assumes that the process- later, the estimated cost per ton for this ing plant will be within 25 miles of the

80 power plants where refuse will be burned This report does not give the approxi- as supplementary fuel. mate distance between the refuse processing plant and the utility company which will This study was made assuming that use the prepared refuse as supplementary the milled refuse, particle size of appro- fuel. It is assumed, however, in the re- ximately 2.54 centimeter (1 inch), would port, that refuse, as supplementary fuel, replace approximately 10% of the heat value would likely not be more than 10 to 15 of the pulverized coal used in suspension- percent of a utility's requirement. fired boilers. The Midwest Research Institute Report Since in this report cost estimates is based on a municipally-owned and operat- are given for various configurations ed facility which operates 300 days per ranging in capacity between 444 metric ton/ year and 24 hours per day. Although a 907 day (490 ton/day) and 1333 metric ton/day metric ton (1000 ton) per day plant was (1470 ton/day), the above comments will used as the basis for the economic analysis, not be repeated for all those Process scale factors were developed for each major Cost Sheets which were obtained under the system component thus enabling investments, same assumptions. For computations on costs, and revenues to be projected for the net cost/ton for all of the configura- facilities with daily capacities of 227 tions please refer to the discussion (250), 454(500), and 1814 (2000) tons. following all the Process Cost and Resource Recovery sheets. It should be indicated here that this source amortized what they refer to as "Amortized Investment" (Engineering R & D, Comments on Table 3-15 and Plant Startup Capital Costs) at 5% over 5 years. It would have been more The Midwest Research Institute Report desirable to spread this investment over of February, 1973, titled Resource Recovery; the 20 year useful life at 5% and not The State of Technology (ref.3-2), per- over 5 years, since this would better re- formed an economic analysis of fuel reflect the true equivalent annual costs. covery systems such as the Horner-Shifrin process. Although the report contains a detailed explanation of the assumptions Comments on Table 3-16 made in the development of their costs, the most important of these are summarized The following report by Schulz (ref. below: 3-21) computes costs for a Horner- Shifrin . 1406 metric ton (1550 ton/per day) The following are cost parameters plant in New York City. which were used in this report (ref. 3-2): Transportation costs or distances are Interest rate, % 5% not given in this report. It is assumed that the- prepared fefuse, burned in sus- Useful life assumed, pension - fired utility boilers will years 20 supply 10 to 20 percent of the total fuel requirements at the boiler installation. Land Costs', $/acre Not specified The plant is assumed to be in operation 365 days/year. Heating value of refuse , BTU/ton NS The following are cost parameters which were used in this report: Waste residues to be landfilled, % of Interest rate, % 6.5 input refuse NS Useful life assumed, Net Credit given for years 15 recovery of metal $13.23/metric ton Land Costs, $/acre Not specified ($12/ton) joules Heating value of refuse 9.06 x 109 metric ton Recovery rate for metal, Btu % of input 6.8% 7.8 x 106 Ton Net credit for use of Residue disposal costs $5.51/metric ton waste as supp. fuel $0.237/109 joules ($5/ton) ($0.25/106 Btu) Waste residues to be Fraction of input refuse landfilled, % of that is converted to input refuse 20 suppl. fuel NS

81 TABLE 3-14 (A) ECONOMIC DATA-ST. LOUIS SUPPLEMENTAL FUEL SYSTEM (REF. 3-32) PROCESS COST SHEET PROCESS NAME: Horner-Shifrin Supplementary Fuel DATA SOURCE: Reference 3-32 CAPACITY IN TONS/DAY: 444 metric tons (490 TPD) per day (one shift, one processing unit) DOLLARS COMMENTS 115,552 metric tons (127,400 138,590 metric tons (152,800 TPY) TPY) Operating 5 days/wk Operating 6 days/wk CAPITAL COSTS (TOT. $) Land $ 150/000 Preprocessing Eqmt 277,000 Processing Eqmt 1,743,000 Postprocessing Eqmt Not specified Utilities NS Building & Roads 886,000 Site Preparation 39,000 Engr. & R & D 252,000 Assumes:. Plant Startup NS •Financing by means of gen- Working Capital NS eral obligation bonds, with Misc.: Landfill Site 125,000 a 20 year term, and an annual Construction Contingencies 281,500 interest rate of 5% Escalation to 1973 Costs 811,500 TOTAL $4,565,000 $4,565,000 OPERATING COSTS ($ PER YR) *Capital costs are 1969 Maint. Material $ 93,400 figures which are projected Maint. LaborX to a 1973 base. Dir. LaborX 193,500 Dir. Materials 89,200 Overhead 4,700 *Operating Expenses for 6 Utilities 45,200 day operation are projected Taxes NS from the 5 day operation Insurance NS total figure. Interest NS Disposal of Residue NS Payroll Benefits NS Fuel NS Misc.: Depreciation 7,000 Truck Operating Expense 35,000 Administration 20,000 TOTAL $ 488,000 ? 586,000 CREDITS ASSUMED ($ PER YR) $353,340 $ 424,OOlT NOTE:Using the assumptions made in this report, a net cost per metric ton was computed, and it is $3.93 and $3.46 for the 5 day and the 6 day operation respectively.

~~ DOLLARS/YR COMMENT 5 days/week 6 days/week

Liquid Gas Solid Power: Steam Electricity Hot Water Magnetic Metals Nonmagnetic Metals Glass Ash Ppper Other: Heating value of Refuse* $ 353,340 $ 424,008 TOTAL ($ PER YR.) ?353,340 I424,008 •Based on 453 tons/day of refuse as supplementary fuel at $3.31/metric ton ($3.00/ton)

82 TA&LE 3-14 (B) PROCESS NAMEi Horner-Shifrin Supplementary Fuel DATA SOURCE: Reference 3-32 CAPACITY IN TONS/DAY: 889 metric tons (980 tons) per day (two shifts, one processing unit) DOLLARS COMMENTS 231,104 metric tons (254,800 |277,324 metric tons (305,760TPY) TPY) 5 days/week ~ 6 days/week CAPITAL COSTS (TOT. 5) Land $ 150,000 Preprocessing Eqmt 411,000 Assumes: Processing Eqmt 2,019,000 . •Financing by means of Postprocessing Eqmt Not Specified general obligation bonds, Utilities NS with a 20 year term, and Building & Roads 934,000 an annual interest rate Site Preparation 44,000 of 5% Engr. & R & D 285,500 Plant Startup Working Capital . Misc.: Landfill Site Construction Contingencies 316,000 Escalation to 1973 Costs 926,500 TOTAL 95,211,000 $5,211,000 OPERATING COSTS (5 PER } Ma int. Material $ 171,800 ^Capital costs are 1969 Maint. Labor) figures which .are projected Dir. Labor) 387,000 to a 1973 base. Dir. Materials 136,400 Overhead 9,300 *0perating expenses for 6 Utilities 90,400 day operation are projected Taxes NS from the 5 day operation Insurance NS total figure. Interest NS Disposal of Residue NS Payroll Benefits NS Fuel NS Misc.: Depreciation 7,000 Truck Operating Expense 70,000 Administration 25,000 TOTAL ? 896,900 $r,t)75,o

83 TABLE 3-14 (C) PROCESS NAME: Horner-Shifrin Supplementary Fuel DATA SOURCE: Reference 3-32 CAPACITY IN TONS/DAY: 889 metric tons (980 TPD) (one shift, two processing units)

DOLLARS 1 COMMENTS 231,104 metric tons (254,800 277,324 metric tons (305,760 TPY TPY) 5 days/week 6 days/week CAPITAL COSTS (TOT. 91 Land v $ 200,000 Preprocessing Eqmt 499,000 Processing Eqmt 3,419,000 Postprocessing Eqmt Not Specified Assumes: Utilities NS "Financing by means of Building & Roads 1,493,000 general obligation bonds, Site Preparation 90,000 with a 20 year term, and Engr. & R & D 474,500 an annual -interest rate Plant Startup NS of 5% Working Capital NS Misc.: Landfill Site 175,000 Construction Contingencies 525,000 Escalation to 1973 costs 1,485,500 TOTAL $8,361,000 $8,361,000 OPERATING COSTS ($ PER YR) Maint. Material $ 171,800 •"Capital costs are 1969 - Maint. Labor) figures which are projected Dir. Labor ) 334,300 to a 1973 base. Dir. Materials 171,400 Overhead 9,300 "Operating expenses for 6 Utilities 90,400 day operation are projected Taxes NS from the 5 day operation Insurance NS total figure. Interest NS Disposal of Residue NS Payroll Benefits NS . Fuel NS Misc.t Depreciation 13,000 Truck Operating Expense 70,000 Administration 25,000 TOTAL 9 885,200 $1,060,000 CREDITS ASSUMED (? PER YR) 706,680 848.016 - NOTEiUsing the assumptions made in this report, a net cost per ton was computed, and it is $3.66 ($3.33) and $3.18 ($2.89) for the 5 day and the 6 day operation respectively.

DOLLARS/YR. COMMENT 5 days/weak 6 days/week Fuel i Liquid Gas Solid Poweri Steam Electricity Hot Water Magnetic Metals Nonmagnetic Metals Glass Ash Paper Other: .Heating value of refuse* $ 706,680 $ 848,016 TOTAL.($ PER YR.) ? 706,680 $ 848,016 TPD of refuse as supplementary fuel $3.30/metric ton (53.00/ton).

84 TABLE 3-14 (D)

PROCESS NAME: Horner-shiffin Supplementary Fuel DATA SOURCE: Reference 3-32 CAPACITY IN TONS/DAY: 1333 metric tons (1470 TPD) (two shifts, two processing units) DOLLARS COMMENTS 346,655 metric tons (382,200 415,986 metric tons (458,640 TPY) TPY) 5 days/week 6 days/week CAPITAL COSTS (TOT. 91 Land $ 200,000 Preprocessing Eqmt ' 589,000 Processing Eqmt 3,567,000 Assumes: Postprocessing Eqmt Not specified •Financing by means of gen- Utilities NS eral obligation bonds, with Building 6 Roads 1,557,000 a 20 year year term, and an Site Preparation 95,000 annual interest rate of 5%. Engr. & R & D 491,500 Plant Startup NS Working Capital NS Miso.t Landfill Site 175,000 Construction Contingencies 546,500 Escalation to 1973 Costs 1,559,000 TOTAL 98,780,000 $8,780,000 OPERATING COSTS (5 PER YR) Maint. Material $ 250,000 'Capital costs are 1969 Maint. Labor) figures which are projected Dir. Labor ) 549,000 to a 1973 base. •Dir. Materials 200,400 Overhead 14,000 ^Operating expenses for 6 Utilities 135,600 day operation are projected Taxes NS from the 5 day operation Insurance NS total figure. Interest NS Disposal of Residue NS Payroll Benefits NS Fuel NS Misc.i Depreciation 13,000 Truck Operating Expense 105,000 Administration 30,000 TOTAL 81,304,777 1,565,000 CREDITS ASSUMED ($ PER YR) ,060,020 1,272.024 NOTE i Using the assumptions made in this report, a net cost per «ton was computed, ana it is $2.73 ($2,48) and $2.39 ($2.17) for the 5 day and the 6 day operation respectively.

DOLLARS/YR COMMENT 5 days/week 6 days/week Fuel i Liquid Gas Solid Power: Steam Electricity Hot Water Magnetic Metals Nonmagnetic Metals Glass Ash Paper Other: Heating value of supplementary fuel* $1,060,020 $1,272,029 TOTAL ($ PER YR.) $1,060,020 91,272,024 "1359 TPD of refuse as supp .etnentary fuel at §3.30/metric ton ($3.QO/ton) .

85 TABLE 3-14

PROCESS NAME: Homer-Shifrin Supplementary Fuel DATA SOURCE: Reference 3-32 CAPACITY IN TONS/DAY: 1333 metric tons (1470 TPD)(one shift, three processing units)

DOLLARS . COMMENTS 346,655 metric tons, (382,200 415,986 metric tons (458,640 TPY) TPY) 5 days/week 6 days/week CAPITAL COSTS (TOT. ?) Land i $ 250,000 Preprocessing Egmt 721,000 Assumes; Processing Egmt 4,926,000 •Financing by means of Postprocessing Egmt Not specified general obligation bonds, Utilities NS with a 20 year term, and Building & Roads 2,265,000 an annual interest rate1 Site Preparation 135,000 of 5%. Engr. & R & D 593,500 Plant Startup . NS Working Capital NS Misc.: Landfill Site 200,000 Construction Contingencies 769,500 Escalation to 1973 Costs 2,128,000 : ••. ' 'TOTAL $11,988,000 $11,988,000 ^OPERATING COSTS (9 PER YR) . Maint. Material $ 260,200 "Capital costs are 1969 Maint. Labor) figures which are projected Dir.' Labor ) . 445,400 to a 1973 base. Dir. Materials 283,100 Overhead '• 14,000 "Operating expenses for 6 Utilities 135,600 day operation are projected ... Taxes ' • NS from the 5 day operation ' Insurance NS total figure. Interest . • NS Disposal of Residue. NS Payroll Benefits NS Fuel NS Misc.:- Depreciation 24,000 Truck Operating-Expense.' 140,000 Administration 35,000 TOTAL $1,337,300 $1,605,000 CREDITS ASSUMED ($ PER YR) $1,060,020 $1,272,024 NOTE: Using the assumptions made In this report, a net cost per ton was computed and it is $3.57 ($3.24) and $3.41 ($2.82) for the 5 day and the 6 day operation respectively. DOLLARS/YR. COMMENT 5 days/week 6 days/week Fuel: • - -• ..-..- Liquid '. Gas Solid Power: ' Steam Electricity Hot Water Magnetic Metals Nonmagnetic Metals < . Glass Ash \ Paper , Other: Heating Value of Refuse* : $1,060,020 $1,272,024 TOTAL ($ PER YR.) $1,060,020 $1,272,024 »T359 TPD of refuse;;as supplementarirvy fuelfuer- S3$3.30/metri. c ton ($3.00/ton)

86 TABLE 3-15 ECONOMIC DATA-ST, LOUIS SUPPLEMENTAL FUEL SYSTEM PROCESS COST SHEET PROCESS NAME: Horner-Shifrin Supplementary Fuel DATA SOURCE: Reference 3-2 CAPACITY IN TONS/DAY: 907 metric tons (1000 TPD)

DOLLARS COMMENTS

CAPITAL COSTS (TOT. ?) ! Land $ 300,000(1) *Assumes a municipally Preprocessing Eqmt 2,760,000(2) owned and operated Processing Eqmt • Not Specified facility. Postprocessing Eqmt NS Utilities NS • Building & Roads NS Site Preparation (Included above) Engr. & R & D 744,000(3) Plant Startup 133,000(3) Working Capital 200,000(1) • Misc. : Auxiliary & Suppt. Facilities 3,440,000(2) TOTAL $7,577,000 OPERATING COSTS ($ PER YR) (1) Not amortized: they are Maint. Material Not Specified treated as recoverable Ma int. Labor NS investment; only inter- • Dir . Labor NS est at the rate of 5% Dir. Materials NS annually is charged to Overhead NS operating cost (under - Utilities NS interest) . Taxes .Insurance 31,00— 0 (2) Amortized over 20 years Interest 25,000(1) at 5% per year. ; Disposal of Residue Not considered Payroll Benefits NS (3) Amortized over 5 years Fuel at 5% per year. Misc. : Administrative & Gen. 62,000 (4) Only global amounts • Operating Costs 798,000(4) given. '•_ Fixed Costs 116,000(4) ', TOTAL $1,032,000 CREDITS ASSUMED ($ PER YR) . $ 920,00 . NOTE: Using the assumptions made in th s report, a net cost per ton was computed and it is $2.99 ($2.71). The corresponding net cost per ton for the 227 (250), 454 (500), and 1814 (2000) capacity plants are $6.27 ($5.69), $4.45 ($4.04), and $1.79 ($1.62), respectively. • ' ~: DOLLARS/YR. COMMENT Fuel: , Liquid Gas Solid Power: Steam Electricity Hot Water Magnetic Metals *Ferrous- $ 245,000 Nonmagnetic metals Glass Ash Paper Other: Heating value of refuse** 675,000 TOTAL ($ PER YR.) *6.8% of 272,000 metric tons (300,000 tons), eachQ$13.23/metric ton ($12/ton) ***2.82 5 x 1015 joules (2.7 x 10" Btu) at $0.237/10* joules ($0.25/106 Btu)

87 TABLE 3-16 ECONOMIC DATA-ST. LOUIS SUPPLEMENTAL FUEL SYSTEM PROCESS COST SHEET

PROCESS NAME: Horner-Shifrin Supplementary Fuel DATA SOURCE: Reference 3-21 CAPACITY IN TONS/DAY: 1406 metric tons (1550 TPD)

DOLLARS COMMENTS CAPITAL COSTS (TOT1. §) Land Preprocessing Eqrat Processing. Eqmt Postprocessing Eqmt Utilities Building & Roads Site Preparation Engr. & R s D Plant Startup Working Capital Misc.: TOTAL ?9,300,OOP OPERATING COSTS (5 PER YR) Maint. Material Mafint. Labor Dir. Materials Overhead Utilities Taxes Insurance. Interest Disposal of Residue Payroll Benefits . , Fuel Refuse preparation $2,670,340 Misc.: Combustion process 752,448 Materials recovery . 147,095 ,.. Transfer & storage 594,038 Disposal of 20% residue 565,750 TOTAL ?4,729,6TT CREDITS ASSUMED (5 PER YR) $2,987,160 NOTE: Using the assumptions made in this report a net cost per ton was computed and it is $5.33 ($4.83).

DOLLARS ' COMMENTS Fuels Liquid Gas Solid Power: Steam Electricity Hot Water - . Magnetic Metals Ferrous* $ 339,450 Nonmagnetic Metals Glass Ash Paper Other: Heating value of refuse** 2,647,710 TOTAL ($ PER YR) $2,987,167 *$ll/metric ton ($10/ton) of metal metal recovered is 6% of input **$0.57/109 joules ($0.60/106 Btu)

88 Net credit given for re- operating and maintenance costs assuming covery of metal, $/ton 260 days, of operation per year. of metal $ll/metrio ton Computations for the estimated net ($10/ton) cost/ton may be found in the appendix section. Recovery rate for metal, % of input Standardized Gross and Net Cost/Ton for Net credit for use of The Horner Shifrin Supplementary Fuel waste as suppl. fuel $0.57/109 joules -Process . . ($0.60/106 Btu) As can be seen from the Process Cost ! Sheets, shown in Tables 3-14 to 3-17, there Fraction of input refuse is significant variability in the costs that is converted to quoted in various sources for a Horner- suppl. fuel Not specified Shifrin supplementary fuel processing plant of fixed capacity. It can be noted in other -sections of this report that this is Comments on Table 3-17" also the case for all of the other processes reported herein. Much of. the EPA's Second Report to Congress variance found in these cost figures is (ref. 3-20) does not specify what inter- mainly, due to the different assumptions est rate.is used nor what useful life is. used in the reports; parameters such as assumed. This source does not specify' heating value of refuse, net credits what type of ownership is assumed. given for recovered energy and products and interest rate used in the computations. The following are* cost parameters All have a great effect on the final com- which were used in this report: puted value of net cost per ton. Interest rate, % Not specified To be able to appreciate the true variability among the cost data given Useful life assumed, years MS earlier it becomes necessary to standard- ize, in some fashion, the parameters under Land costs, $/acre • NS which the net cost per ton figures are computed. Heating value of refuse $1.10 x 1Q10: Consider as an 'example, the Horner- joules/metric ton Shifri'n supplementary fuel process.. It is felt that the following basic parameters (9.5 x 106 Btu/ should'be applied to all data sources. ton) ... 1. Processing plant is wholly owned._ by the municipality. Residue disposal costs, 2. Ferrous metal, which is assumed $/ton NS recovered at the rate of 6 percent of input refuse, is sold at Waste residues to be a net price of $33/metric ton landfilled, % of ($30/ton) of metal. input refuse 13 3. Supplementary fuel (70 percent of input refuse) is sold to a Net Credit given for re- utility company at a net price of covery of metal, $/ton $0.32/109 joules (SO. 34 per mil- metal $18.75/metric ton lion BTU) . 4. Supplementary fuel is assumed to ($17/ton) have a heating value of 1.05 x ., 1010 joules/metric ton (9 x 106 Recovery rate for metal, BTU/ton). % of input 5.88 5. It is assumed that input refuse, as received, has 12 percent mois-; Net credit for use of ture, that 70 percent is converted waste as supp. fuel, : to supplementary fuel and that 6 $/million BTU percent is metal; there is thus ._ 12.percent of the input refuse Fraction of input re- which is landfilled at an assumed fuse that is con.- cost of $3.30/metric ton ($3/ton) verted to suppl. to the municipality. fuel 80 6. Plant life is assumed to be 20 years. The data for this source is based on 7. All dollar figures are 1974 1971 actual costs and estimated 1972 estimates.

89 TABLE 3-17 ST, LOUIS SUPPLEMENTAL FUEL SYSTEM PROCESS COST SHEET

PROCESS NAME: Horner-Shifrin Supplementary Fuel"' DATA SOURCE: Reference 3-20 CAPACITY IN TONS/DAY: 590 metric tons per day (650 TPD)

DOLLARS COMMENTS CAPITAL COSTS (TOT. 5) Land • Preprocessing Eqmt Processing Eqmt Postprocessing Eqm- Utilities Building & Roads . Site. Preparation Engr. & R s D Plant Startup Working Capital Misc.: TOTAL $2,394,000 OPERATING COSTS ($ PER YR) Maint. Material Maint. Labor Dir. Labor Dir. Materials Overhead Utilities Taxes Insurance Interest Disposal of Residue Payroll Benefits . Fuel Misc.: TOTAL $ 618,007 CREDITS ASSUMEDt? PER YR) 169,000 NOTE: Using the assumptions made in th s report a net cost per ton was computed anoit is $4.41 ($4.00).

DOLLARS COMMENTS Fuel: Liquid Gas Solid Power: Steam Electricity :~- Hot Water Magnetic Metals $ 169,000 Nonmagnetic Metals Glass Ash Paper Other: TOTAL ($ PER YR.) $ 169, OW

90 net cost per ton to the val.ues of the cre- 8. Investment is financed at an dits assumed. Even though the Figures pre- annual net rate of 8 percent. sented earlier, Figures 3-44 and 3-45, Using the above parameters, the gross do show wide expected ranges in both the and the net costs per ton were recomputed gross and net costs per ton, they do not for all data sources considered under the show the. sensitivity of the net cost per _. Horner-Shifrin supplementary fuel process; ton to the values of the credits received.; the standardized costs are shown in for both the recovered metals and the ;! Figures 3-44 and 3-45, and are presented supplementary fuel. in" tabular formrin Table 3-18. Assuming a gross cost of $8,.27/metric-f ton ($7.50/ton) for a 907 metric ton. (1000'. ton) Rorner-Shifrin supplementary .fuel .pro-j cessing plant operating 26.0 days per year, .; a graph may be prepared which depicts the < METRIC TONS/DAY sensitivity of the net cost per ton of'the I zoo 400 600 BOO 1000 '1200- 1400 process to the values of the credits given f for both metals and supplementary fuel. • II Figure 3-46 has been prepared under .the { 10 following additional assumptions: ." GROSS s 1. Heating value of prepared, , refuse | COST 8 is 9.3 x 109 joules/metric tioti $/TON 7 s 6 »> (8 x 10 Btu/ton). •r METRIC 8 The effective-ferrous metal .re-: " TON covery rate is 6 percent of the REF. 3-32 REF. 3-20 3 input refuse. '•.... REF. 372 2 Supplementary fuel is 70 percent I of the input refuse. 200 4OO GOO 800 IOOO 1200 I40O 1600

TONS/DAY FIGURE NET METAL CREDITS < I/METRIC TON) ... VARIATION IN GROSS COST PER TON 3 4 5 6 7 8 ' 9 .10 F10LBES N KRENTHESES FOR ST, LOUIS SUPPLEMENTAL FUEL PROJECT ARE 1/TON.OTHERS $/ METRIC TOM

METRIC TONS/DAY

200 400 600 800 IOOO 1200 I4OO

9 - 8 7 NET 6 COST 2 3 4 S 6 7 8 $/TON 9 »' . METRIC NET METAL CREDOS ($/TON OF METAL) 4 TON REF 3-32 _ « REF. 3-20 FIGURE 3-46 . . , o REF 3-2 . SENSITIVITY OF NET COST/TON I (FOR 1000 TON/DAY SUPPLEMENTARY FUEL PROCESS) 200 400 600 BOO IOOO 1200 I40O 1600 TO FUEL & METAL CREDITS , , „, 1

FIGURE 3-45 Figure 3-4.6 shows how, for different.' I VARIATION IN NET COST PER TON combinations of fuel and metal credits, the' FOR ST, LOUIS SUPPLEMENTAL FUEL PROJECT net cost per ton of a Horner-Shifrin 907 . • metric ton (1000 ton) .per-day plant varies.? Figures 3-44 and 3-45 give some idea as The parallel lines "correspond'to different--" to the general trends and ranges that can be assumed credit - combinations, all of which observed when plotting both the "standardized yield the same net cost'per ton. As can be gross costs per ton, and the net costs per seen, the Horner-Shifrin supplementary fuel ton. A set of estimated lower and upper process could easily compete with landfill bounds on the costs per ton gives a range of in areas of the country where:_ costs in which the true estimated Values are 1. Landfill costs are high, expected to fall. 2. There are high attainable fuel and metal credits or, where a Sensitivity of Net Cost/Ton to Credits combination of both is present. Assume cf " ~ If a city has some idea as to what One very important question that should possible credits it can obtain from the be investigated in the sensitivity of the

91 TABLE 3-18 STANDARDIZED COSTS PER TON FOR THE HORNER SHIFRIN SUPPLEMENTARY FUEL PROCESS Gross Cost . Net Cost 5 per 9 per Metric metric metric. Source Tons (TPD) • ton $ per ton ton $ per ton Horner-Shifrin report to the EPA (EPA-SW-36D-73)(ref. 3-32) 444 (490) $9.04 ($8.20) $4.74 ($4.30) Horner-Shifrin report to the EPA (EPA-SW-36D-73)(ref. 3-32) 444 (490) 8.27 ( 7.50) 3.97 ( 3.60) EPA1 s second report to Congress (ref. 3-20) 560 (650) 6.73 ( 6.10) 2.32 ( 2.10) Horner-Shifrin report to the EPA '. -(EPA-SW-36D-73) (ref. 3-32) 889 (980) 6.84 ( 6.20) 2.54 ( 2.30) Horner-Shifrin report to the EPA (BPA-SW-36D-73) (ref. 3-32) 889 <980) 6.50 ( 5.90) 2.09 ( 1.90) Horner-Shifrin report to the EPA (EPA-SW-36D-73) (ref. 3-32) 889 (980) 8.27 ( 7.50) 3.97 ( 3.60) Horner-Shifrin report to the EPA (EPA-SW-36D-73) (ref. 3-32) 889 (980) 7.61 ( 6.90) 3.31 ( 3.00) Midwest Research Institute i Resource Recovery i State of Technology (ref. 3-2) 907 (1000) 8.05 ( 7.30) 3.75 ( 3.40) Horner-Shifrin Report to the EPA (EPA-SW-36D-73) (ref . 3-32) 1333 (1470) 7.06 ( 6.40) 2.76 ( 2.50) Horner Shifrin Report to the EPA (EPA-SW-36D-73) (ref. 3-32) ' 1333 (1470) 6.62 ( 6.00} 2.21 ( 2.00) Horner Shifrin Report to the EPA (EPA-SW-36D-73) (ref. 3-32) . 1333 (1470) 8.16 ( 7.40) 3.86 ( 3.50)

Horner Shifrin Report to the 'EPA ' \ (EPA-SW-36D-73) (ref. 3-32) 1333 (1470 7.50 ( 6.80) 3.20 ( 2.90)

selling of recovered ferrous metal scrap million Btu)(after considering the pre- and from the sale of the prepared suple- paration, handling and transportation costs mentary fuel, figure 3-46 could then be of delivering the prepared refuse to the used to estimate the city's net cost per utility), it would be more economical for ton. Comparing this net cost with their the city to change to a supplementary fuel current landfill costs, the,city could conversion process of the Horner-Shifrin have a very good idea as to the possible type rather than continue to landfill. economic advantages (or disadvantages) of changing from landfill to a Horner- Shifrin supplementary fuel process. Summarizing, it can be said that the net cost per ton in a supplementary fuel pro- Assume, for example, the case of a cess is sensitive to both the fuel credits city in which current landfill costs are and the metal credits, and it is more sensi- $4.41/metric ton ($4/ton). Further assume tive to the fuel credits. The recent increases that recovered ferrous metal can be sold in the prices of coal and other fuels, coupled .for $18.74/metric ton ($17/ton) but that with the increased costs of landfilling in the cost of handling and transporting the most urban centers will have a very positive recovered metal to the buyer are $17.09/ effect on the competitiveness of the metric ton ($15.50 per ton): the net supplemental fuel processes similar to metal credit is $1.65/metric ton ($1.50. Horner-Shifrin. This should be of great per ton). If the city can sell the pre- interest to the more densely populated pared refuse to a utility company for at areas such as the Metropolitan Statistical least a net $0.51/109 joules. ($0.54 per areas (SMSA's) which have utility companies

92 burning fuel that can be combined with This pre-processing includes shredding, prepared mixed municipal refuse. As to separation, and drying, leaving a combustible how soon this process becomes economically fraction with a relatively high heating feasible in these large urban centers, value fref. 3-17). this will depend on: The first generation fuel made by 1. Whatever limitations are identi- Combustion Equipment Associates (CEA), fied in the plants undergoing Eco-Fuel™ I, has physical and general tests (for example; corrosion properties as noted in Table 3-19. The and pollution problems in the moisture content averaged 10 percent, and St. Louis plant), 78.5 percent of the solid fuel was combustible. The sulphur content varied 2. Whatever markets are found between 0.1 and 0.2 percent, which means • primarily for supplementary that the off gases would be low in SOX. fuel, and secondarily for the ferrous and non-ferrous metals. The fly ash resulting from the burning of refuse is expected to be equivalent to •3. The costs of other conversion that of coal. Electrostatic precipita- process options, including tjors or fabric filters could therefore landfill. be used to collect these particulates. Double vortex (DV) burners are recom- Cities interested in studying the mended for the firing of the Eco-Fuel™ I. possibilities of the Horner-Shifrin There appears to be good mixing of the supplementary fuel process should obtain solid fuel and combustion air in a com- information from the EPA on the experi- mercial boiler; thus the concentration ments that have been, and are being con- of CO is low, less than 8 parts per -• ducted in St. Louis. A forthcoming re- million. The NOX emissions from the port by Gordian Associates Incorporated, burning of Eco-Fuel™ are expected to be to be published by the EPA, and titled less than that of burning coal (ref. 3- Where the Boilers Are; A Survey; of 17) Electric Utility Boilers with Poten'tial capacity for Burning Solid Waste as a Fuel One of the disadvantages of Eco-Fuel™ should also provide valuable information I was its low bulk density. CEA sub- to cities desiring to look closer into sequently developed Eco-Fuel™ II, which this energy conversion approach to the has a higher bulk density and requires problem of solid waste. no special handling. The second generation solid fuel is chemically treated 3.3.3.4 SOLID FUEL INCINERATION - Eco-Fuel™ and undergoes a superior separation system. The organic fraction can be 3.3.3.4.1 Technical Description processed into a very fine powder. The overall characteristics of Eco-Fuel™ n The flow diagrams for the production are expected to be superior to Eco- of both Eco-Fuel11™™ I and Eco-Fuel1™™ II wewerie Fuel™ I. discussed previously in section 3.2.4.2. TABLE 3-19 _ PROPERTIES OF ECO-FUEL™ I (REF, 3-17) Estimated Composition Estimated cnemicai Analysis Percent by weight Percent by weight Component (as fired) Component (as fired) 'aper 45.0 Carbon 39.6 food 9.3 Hydrogen 5.3 leather 0.7 Oxygen 32.3 1.2 Nitrogen 0.9 Lubber 11.5 M.CISU1C|1 a n 4> i I"»Q9 2.7 Ash 2.7 Sulphur 0.1 - 0.2 textiles 0.1 - 0.2 'ood Wastes 10.3 Chloride 1 1\ f\ 13.1 Water ID .0 'ard Wastes 100.0 inerts 5.0 loisture 10.0 100.0 Generalized Properties Component Percent by Weight (as fired) 78.5 Higher Heating Value 1.6x108 2°£$.(6900 Btu/lb) Combustibles 11.5 Particle size 1.25 cm or less (V or less) Ash Bulk density 112-160 kg/m3 (7-10 lb/ft-») Moisture 10.0 Storage life Indefinite 100.0 Approximate Ash Fusion Temp. 1200-1425°C ** ' (2200-2600°F) Pounds air/pound-fuel 6.0

93 A summary of the properties of 1. Direct incineration of ,refuse with Eco-Fuel™ II is,given in Table 3-20. steam generation. ' ,".; The heating value of the'refuse fuel has 2. Direct incineration with electri- been increased 10 to 20 percent over cal power generation. that of Eco-Fuel™.I. ' Ih'.'fine powder 3. Supplemental -fuel incineration form the fuel is easily transported, with'steam -generation. and should provide good burning charac- 4. Direct incineration of refuse as teristics when burned in the DV furnance. . a prepared solid•fuel for steam generation. , CEA has a contract with the State of Connecticut to provide a resource recovery The profit potential of operating a. and Eco-Fuel™ II preparation plant, as solid waste system with energy recovery well as facilities for the firing of re- depends oh a number of variables including: fuse to produce steam. The facilities are expected'to be in operation in 1976. plant capital cost In the meantime, additional research will plant operation and maintenance be conducted'by CEA at their Brockton, cost ' Massachusetts, plant to determine optimum present solid waste disposal cost particle size for the solid fuel refuse local price of energy burning. local market for energy energy conversion efficiency. TABLE 3-20 . - PROPERTIES OF ECO.-FUEL™, 11 Local credits for energy and resource will be one of the prime factors in the Particle size: ''6.6-cm to 100 mesh economics of a system recovering energy (-1/4 inch td '-100 inesh) from MMR.. Higher Heating Value: 1.74-1.86 X • . . > - • One point that has not been strongly (7500-8000 Btu/lb) emphasized is the..quality.of personnel Moisture Content: less than 2% by required to operate a large scale energy weight recovery system. The incinerator plants Storage life: indefinite 3 j are complex and require the services of Bulk density: 480 kg/m (30 lb/ft ) trained operators and skilled workers. A Handling Properties: free flowing powder wellrdesigned system staffed with inadequately trained personnel will not be successful.

3.3.3.4.2 Economic Data for Eco-Fuel™ II •3,4- PYROLYSIS PROCESSES The economic data for Eco-Fuel™ II was received by telephone from Ken Rogers of Combustion-Equipment /Associates, Inc., 3,'4,1 INTRODUCTION of New York. He stressed the importance j;' Pyrolysis 'is defined as thermal de- of the concept that costs and credits composition without complete combustion. depend on local conditions and local market If a storable fuel ds .desired, either gas, prices. He gave cost and credit ranges liquid, or solid, pyrolysis offers a viable which are generally expected 'in the Con- option with a minimum amount of landfill necticut project' (ref. '3-44) . The figures and pollution control problems. The pro- presented in- the process" cost 'sheet and cess technology, however, has not been resource recovery data are estimated from widely demonstrated on a commercial scale these ranges. , •-••••?' and thus there is considerable confusion regarding vendor technical and economic These cost estimates might be some- claims. ' what high because they are based on a plant capacity of 1814 metric ton/day !' In this section, general considerations (2000 ton/day), while the normal operating will be presented, (reaction and reactor capacity is a nominal 907 metric ton/day types, process variables, heating methods, (1000 ton/day). feed conditions and product distribution) followed by a brief description of reported pyrolysis processes. .Selected processes 3,3,4 SUMMARY OF INCINERATION SYSTEMS will then be analyzed in greater detail. A summary and suggestions for further re- 'search will conclude the section. Several poasib/fe^ ^applications of 'incineration with;energy recovery-have been examined to determine performance and cost. These have included: 3,4,2 GENERAL CONSIDERATIONS

94 PROCESS COST SHEET

PROCESS NAME: Eco Fuel™ II , ,,„» DATA SOURCE: Ken Rogers of CEA Inc., New York (telephone conversatxon on 8/6/74) CAPACITY IN TONS/DAY: 1814 metric (2000) COMMENTS

CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt Processing Eqmt Postprocessing Eqrat Utilities Building & Roads Site Preparation Engr. & R & D Plant Startup Working. Capital Misc.:

TOTAL 20,000,000

OPERATING COSTS ($ PER YR 907 Metric ton/day Maint. Material operation (1000 Maint. Labor ton/day opera- Dir. Labor tion) Dir. Materials Overhead • Utilities This cost ranges fron Taxes 2,000,000 to Insurance • 2,500,000 Interest Disposal of Residue Payroll Benefits Fuel Misc.:

TOTAL 2,250,000 COMMENT 907 Metric ton/day Fuel: operation (1000 ton/ Liquid day operation) Gas Solid 1,875,000 This credit ranges Power: from 1,500,000 to Steam 2,250,000 as the Electricity Fuel credit varies Hot Water from $6 to $9 per Magnetic Metals ton Nonmagnetic Metals Glass 625,000 This varies from Ash $500,000.to $750,000 Paper Other:

TOTAL ($ PER YR.) I 2,500,000* *0n a $/ton basis this represents a net cost of $ll/metric ton ($10/ton) for refuse disposal. This net price is highly dependent on the value of energy credits and recovered resources and is probably a conservative number. The net disposal cost in Connecticut could be less than $5.51/metric ton ($5/ton) under optimum operating conditions'!

95 3.4.2.1 CHEMICAL REACTIONS The fluidized bed reactor consists of a bed of solid particles (e.g., sand) suspended by an upward flowing gas stream. Pyrolysis is a complex process of For pyrolysis applications, the" solid simultaneous and consecutive chemical particles are heated (same vessel or ex- reactions. While a complete description ternal vessel with circulation) and serve of the specific reaction types-occurring as the heat source for the pyrolysis re- has not been determined, it is generally actions. A chemical reaction involving believed that reactions such as cross the solid particles may occur (e.g. dolo- •linking, isomerization, de-oxygehatioh";' mite MgO.CaCO3 + C02 [exothermic]). Tfie de-nitrogenation, etc. do occur. The major advantage over other reactor types reactive portion of the solid waste is is improved heat transfer and temperature composed primarily of cellulosic material. control. The primary drawbacks include An empirical formula has been proposed erosion and carry over problems associated for MMR by Burton and Bailie (ref. 3-45): with the solid particles, gas velocity C30H48°19N0.5S0.05- Tne decomposition of control and solids transfer and separation the cellulosic material starts.-to occur problems. • at about 180°C (360-eF)-; producing a mixture of solids, liquid and gas, the proportions and composition depending on 3.4.2.3 PROCESS VARIABLES reactor conditions and environment (ref. 3-46).. The key reactor1-control variable is the temperature of pyrolysis. The yield 3.4.2.2 REACTOR TYPES and composition of products can be significantly altered by'-manipulation of the reactor temperature'profile. Thus at Several basic reactor .types' have been high temperatures 16000-C (3000"F), the used for pyrolysis reactions. The most reactor products consist primarily of gas common can be 'classified as follows: : and slag phases. The gas consists of (1) shaft, (2) rotary kiln, and (3) fluid- low-molecular weight hydrocarbons and ized bed. other gases such as H2, CO, C02, etc. The slag consists of a fused mass of solid Shaft reactors (horizontal and vertical) residue. As the temperature is lowered, are conceptually the simplest and lowest in the gas phase becomes richer in higher capital cost. In the vertical type, the molecular weight hydrocarbons and a liquid feed material is fed into the top of the phase may'also be present. The solid reactor and settles into the reactor under residue phase also becomes more hetero- its own weight. Generate'd pyrolysis gases genous at lower temperatures. pass upward thru the shaft and are removed from the top. Typical feed mechanisms include screw conveyors, rotary devices and 3.4.2.4 HEATING METHODS rams. A residue discharge device and gas.-' . takeoff manifold must be provided. The horizontal shaft type incorporates a feed Pyrolysis reactions are generally con- conveyor system.(e.gvmechanical, molten bed) sidered endothermic and require a heat thru the reactor housing. .Refuse is thus source. Two distinct heating methods are continuously pyrolyzed from the conveyor used, direct and indirect. In this report, system. Feed and discharge-problems'are • a; "direct" method refers to a procedure minimized but reliability of conveyors at whereby' heat is supplied to the reaction elevated temperatures can be a problem. mixture by partial combustion of refuse Both types of vessels are constructed of and/or supplementary fuel within the metal capable of withstanding high tempera- pyrolysis reactor. Oxygen must be supplied tures 260-1650-C (500-3000°F) or are lined and the reactor product gas contains a with a refractory material. significant amount of C02 and H20, with resulting reduced heating value. The rotary kiln is a 'cylinder rotated upon suitable bearings 'and usually slightly If air is used as the oxygen source, inclined to the horizontal. Typical the environmental problems of NOX forma- length/diameter ratios are in the range tion must be considered, as well as the of 4 to 10. Feed material is charged into- further dilution of the pyrolysis gas by one end of the kiln and'-progresses thru • • large .amounts of N2- "Indirect" heating the kiln by means of rotation and slope of methods refer to methods in which the pri- the cylinder to the opposite end where it •' mary heating zone is separated from the is discharged. Feed and discharge mechanisms pyrolysis vessel. This separation can be must be provided. The metal cylinder is achieved by a heat conduction barrier normally lined with a refractory brick. (wall) or by transfer of a separate medium The rotary kiln has mixing advantages over between the combustion and pyrolysis vessels the shaft type reactor but the sealing of (e.g., sand, molten bed). Wall heat trans- the rotating cylinder from the stationary fer methods are generally unacceptable in feed and discharge ports can be a problem. solid waste applications due to large re-

96 sistances such as refractory linings, slag general, a dried, finely shredded feed coatings, and corrosion problems. The use with solid inorganics removed is most de- of a separate medium is desirable from a sirable from a reaction viewpoint. heat transfer 'viewpoint but can present major problems with regard to solids transfer and separation. . Indirect methods are 3.4.2.6 PRODUCT DISTRIBUTION generally less efficient than direct methods but avoid the problems of excessive C02 and H2O formation (reduced heat- The pyrolysis reactor output can con- ing value) and high NOX and N2 content. sist of liquid, solid and gas phases. The composition and amounts of each phase will The general relationships of reactor be dictated primarily by: type and heating method to operation simplicity and high heating rates are shown in 1. the amount of preprocessing (se- Table 3-22. Thus, for example, a rotary paration and sizing), kiln system with indirect heating via a 2. reactor temperature and residence circulating solid medium would be expected time, to have excellent heat transfer character- 3. heating method (direct or indirect) istics but severe solids handling and separation operational problems. The virtues of different product distributions is a utilization consideration that is discussed in Chapter 4 of this report. 3.4.2.5 FEED CONDITIONS A general indication of the effect of residence time, temperature and particle size on product distribution is shown in Pyrolysis reactors have been designed Figure 3-47. For example, for a given to handle a variety of refuse feed condi- reactor temperature and particle size a tions. Thus some systems will accept decrease in particle size will tend to raw municipal refuse while others may re- increase gas production and decrease quire some pre-conversion, such as size solid and liquid fuel production. The reduction or separation of different types relationships are very complex and inter- of inorganic material. Conceptually, a related and are not well understood. system that is designed to handle a raw feed can also accept a preprocessed feed. The preprocessing decisions are sometimes 3.4,3 DESCRIPTION OF PROCESSES dictated by inorganic product-utilization considerations but also have a direct effect on required reactor equipment such Table 3-23 lists twenty-four pyrolysis as feed and discharge devices etc. In projects in progress or completed. The

TABLE 3-22 REACTOR TYPE CHARACTERISTICS

INDIRECT HEATING WALLTRANSFER CIRC. MEDIUM DIRECT HEATING HIGH HIGH OPERATIONAL HIGH OPERATIONAL HEATING OPERATIONAL HEATING SIMPLICITY HEATING RATE SIMPLICITY RATE SIMPLICITY RATE Vert. Shaft Horizon. Shaft NONE NONE Rotary Kiln + Fluid. Bed NONE NONE

NOTE: 1. A plus (+) entry indicates a virtue while a minus (-) entry indicates a detriment. 2. A NONE entry indicates that no process development has been reported in that category. 3. No entry implies neither a virtue nor a detriment.

97 major headings are:

1. heating method, 2. product distribution, 3. feed conditions, 4. reactor temperature, 5. status, 6. references.

RESIDENCE PART TIME SIZE Lack of entry within a major heading im- (I MIN.- Z6O*- ISSO'C 0.025 -15 cm. I HRJ SOO-3OOO*F plies that information is not available. OAS FUEL All of the commercial status processes S.73ilO'-2.24«IO' JOULES/M* (100-600 BTU/SCF listed are in the design, construction (CO, COj.Hj. HYDROCARBONS) or startup phase. LIQUID FUEL 2.33 % I07 - 2.56 1I07 JOULES/ K<3 (10,000-11,000 8TU/LB) (QR6ANIC REFUSE) I OXYGENATED. UNSATURATED 3.4.3.1 VERTICAL SHAFT REACTORS HYDROCARBONS)

SOLID FUEL 1.398 « I07- 2.097 « I07 JOULES/ KG (6OOO-9000 BTU/LB) 3.4.3.1.1 (CARBON, ASH) Garrett. (ref. 3-18, 3-21, 3-22, 3- FIGURE 3-47 28, 3-47, 3-50, 3-51) The Garrett Re- EFFECTS OF TIME, TEMPERATURE, AND PARTICLE search and Development Company (central SIZE,ON PYROLYSIS PRODUCT DISTRIBUTIONS research organization for the Occidental PYROLYSIS REACTOTABLER 3-23CLASSIFICATIONA S (METRIC UNITS;

HEATING PRODUCT DISTRIBUTION FEED CONDITIONS STATUS METHOD PROCESS DIR. INDIR. SOLID LIQUID GAS SIZE SEP- REACTOR RES. Metric Tons/Day REFERENCES Joules/ Joules/ Joules/ RAW RED. ARA- TEMP Pilot Coiuui kgxIO-? kgxlO"7 m' TION °C Plant VERTICAL SHAFT Garrett X 2.20 2.44 2.04 X X 482 3.6 180 3-18, -21, -22, -28 -47, -50, -51 Battelle X .64 X 982 1.8 3-22, -28, -47, -54 -55 Ga. Tech. X 2.32 3.02 .74 X 399 23 3-53 URDC X .56 X 1427 109 3-26, -47, -48 Torrax X .56 X 1650 68 3-26, -28, -47, -48 -52 Union Carbide X 1.113 . X 1650 4.6 180 3-28, -47, -48, -49 HORIZONTAL SHAFT Kemp X X X X X 593 4.6 3-47 Barber- Colman X 1.86 X X 649 .91 3-56 • ROTARY KILN Monsanto X 0.57 .48 X 982 32 907 3-21, -22, -28, -47 -60, -61, -62. Devco X X X X X •538 109 1360 Pr iv . Comm . Rust Eng X 1.68 677 236 3-57, -58, -59 Pan Am Res. X X 1093 X 3-8, -63, -64 FLUID. BED W. Virginia X 1.68 X X 760 X 3-65, -66, -67, -68 A.D. Little X X X X X 3-70 Coors X .56 X X 760 .91 3-69 , .. OTHER Battelle X 982 X 3-71 Hercules X X 3-28, -72 Bur. Mines X 1.86 X X 982 X 3-22, -28, -73, -74 -75 NYU x • 927 X 3-76, -77 use X X Priv. Comm. Anti. Poll. Syst X 3-78 Univ. Calif. X X X 3-79 Wallace-Atkins X .70 3.71 1.86 871 X 3-80 Res. Scl. X X 982 1.8 3-47

98 PYROLYSIS REACTOTABLER 3-23CLASSIFICATIONB S (ENGLISH UNITS)

PRODUCT DISTRIBUTION PEED CONDITIONS STATUS HEATING SOLiD LIQUID GAS SEP- REACTOR PILOT METHOD (BTU/ (BTU/ (BTU/ SIZE ARA- TEMP PLT COMM DIR. INDIE. Ib) Ib) ft3) RAW RED. TION oc RES. (TPD) (TPD) REFERENCES

VERTICAL SHAFT Garret t X 9,700 10,500 550 X X 900 4 200 3-18, -21, -22, -2 8, -47, -50, -51

Battelle X X 170 X 1800 2 3-22, -28, -47, -54, -55

Ga. Tech. X 10,000 13,000 200 X 750 25 3-53

URDC X 150 X 2600 120 3-26, -47, -48

Torrax X 150 X 3000 75 3-26, -28, -47, -48, -52

Union Carbide X 300 X 3000 5 200 3-28,-47,-48/-49

HORIZONTAL SHAFT

Kemp X X X X X 1100 5 3-47

Barbcr-Colman ..X 500 X X 1200 1 3-56

ROTARY KILN Monsanto X - 2,500 130 X '1800 35 1000' 3-21, -22, -28, -47, --60, -61, -62 Devco X X X X X 1000 120 1500 Priv. Comra.

Rust Eng X 450' 1250 260 3-57, -58, -59

Pan Am Res. X X 200 X 3-8, -63, -64

FLUID. BED

W. Virginia X 450 X X 1400 X 3-65, -66, -67, -68

A. D. Little X X X X X 3-70

Coors X 150 X X 1400 1 3-69

OTHER '

Battelle X 1800 X 3-71 .

Hercules X X 3-28, -72 Bur . Mines X 500 X X 1800 X •; 3-22,-28,-73,-74,-75 HYU X 1700 . X 3-76, -77 use X X Priv. ComnT.

Anti Poll. Syst. X 3-78

Univ. Calif. X X X 3-79"

Wallace-Atkins X 3,000 16,000 500 1600 X 3-80 ' ."•"': Res. Sci. X X 1800 2 3-47

Petroleum Corporation) has modified a coal conversion process to convert m&nicipal refuse to synthetic fuel oil (Figure 3-48). A 1180 metric ton/day (200 ton/day) demonstration plant is GAS TO being built for San Diego County, PURIFICATION California. The process involves exten- AND RECYCLE sive preparation, consisting of the WATER TO following steps: PURIFICATION AND DISPOSAL 1. primary shredding of the raw refuse to approximately 5 centi-' . meters (2 in.), 2. air classification to remove most JNRECOVERED of the inorganics, SOLIDS - 3. drying to about 3 percent mois- TO DISPOSAL ETK ture, METALS 4. screening of the dry material to further reduce the inorganic con- FIGURE 3-48 tent (less that 4 percent by SCHEMATIC OF GARRETT PYROLYSIS PROCESS weight),

99 5. recovery of magnetic metals and perature: drying, pyrolysis, and char glass, and gasification. Ash is discharged from the 6. secondary shredding of the or- reactor via an airlock. Experiments have ganics to about 2 mesh. been conducted with shredded, unsegregated refuse at a feed rate of approximately 80 The organic material is then fed to a kilograms/hour (180 pounds/hour) and py- vertical shaft pyrolysis reactor at a rolysis temperatures of 700-10008C (1300- reactor temperature of about 480°C (900°F) 1800'F). A 136 metric ton/day (150 ton/day) yielding products consisting of char, oil, plant for the city of Kennewick, Washington gas and water phases. An indirect heating has been proposed. Figure 3-50 is a method is used. Under optimum liquefaca- schematic of the proposed Battelle process tion conditions, oil yields of about 40 pyrolysis plant. percent by weight are obtianed. The gas and part of the char is used on site for process heat. A more detailed analysis of this process will be presented in section 3.4.4.3.

3.4.3.1.2 Battelle - Northwest (Vertical Shaft). -(Ref. 3-22, 3-28, 3-47, 3-54, 3-55) Battelle has conducted research on two different systems for converting municipal refuse to marketable products: (1) vertical shaft with direct heat, and (2) molten salt vertical reactor. ** The vertical shaft process reactor is illustrated in Figure 3-49. The reactor

AIRLOCK FEEDER

PRODUCT OASES

ASH RECEIVER

"lOO'C — 500"C FIGURE 3-49 BATTELLE.VERTICAL SHAFT dimensions are 3.66 meters (12 feet) in length and 0.91 meters (3 feet) in diameter. A refractory lining is used. Solid waste is transferred into the top of the reactor through an air lock device and passes downward through the reactor while an air- FIGURE 3-50 steam mixture, and product, gases pass up PROPOSED BATTELLE PROCESS through the reactor. The solid waste PYROLYSIS PLANT SCHEMATIC passes through zones of increasing tem-

100 3.4.3.1.3 Georgia Institute of Technology MMR as a feed material will definitely re- (Ref. 3^53) duce the usefulness of the char as a solid fuel due to the quantities of inert materials included, even after screening to re- A low temperature vertical shaft py- move larger pieces of metal and glass. The rolysis system has been developed by the char could be used to produce activated Engineering Experiment Station of Georgia charcoal, or could be used to produce a Institute of Technology (see figure 3-51). fuel gas by the water-gas reaction or other means for gasifying coal. The low sulfur content would remain as an advantage.

3.4.3.1.4 URDC (Ref. 3-26, 3-47,. 3-48.) PYROLYTIC OFF-GASES The system developed by the Urban Research and Development Corporation (URDC) EXHAUST uses combustion with preheated air of the char from pyrolysis to produce heat for the pyrolysis of MMR (Figure 3-52).

CONDENSIBLE ORGANIC MATERIAL

COMBUSTION GASES

FIGURE 3-51 ST4CK REFUSE PYROLYSIS OAS J FLOW DIAGRAM OF /\ L COMBUST AIR GEORGIA TECH PYROLYSIS SYSTEM Most of the development work has been done HOT AIR using agriculture or wood wastes, but some testing has also been done with municipal , , L HEAT AIR refuse. Actually only the heavy fraction UENCH SCRUB of municipal refuse was used in the tests, — ° SLAT EXCHANGER which may present more operating difficulty than typical MMR. The process has.been operated with partial oxidation with air (without preheating) in the reaction chamber, FIGURE 3-52 and with the reactor temperature limited to FLOW DIAGRAM OF URDC PYROLYSIS PROCESS 400°to 500°C (750° to 930°F). Use of such low temperatures reduces or removes the requirements for insulation of the reactor, As raw MMR falls through the vertical shaft and reduces mechanical and materials de- it is dried. The organic portion is pyrolyzed, sign problems. Also, the low temperatures with the char and inorganics falling to used allow the possibility of pos-reactor the combustion zone at the bottom. The recovery of most metals and glass, since high temperature 1100" -1400«C (2000--26000 they will not be melted in the reactor F) in the combustion zone converts inor- and metal oxidation will be minimized. The ganics to an inert slag. The low heating low temperature pyrolysis favors the pro- value pyrolysis gas 3.7 to 6.0 x 106 joules/ duction of large amounts of char and small meter3 (100 to 160 Btu/ft3) is burned to amounts of gas. The gas (low heating value preheat the combustion air. Limited data due to partial oxidation with air) has is available from operation of a 22 metric been used for drying the feed material and ton/day (24 ton/day) pilot plant (located powering an internal combustion engine for in Roncari Industries, Inc. quarries) which operation of mechanical equipment. began operation in 1969, and even less data is available from the 110 metric ton/day The char produced has a high heating (120 ton/day) pilot plant started up in value and low ash production when the feed 1973. material contains little inert material, as in some agricultural and wood wastes. It should be noted that -the presence Experiments with mixing the liquid fuel of large amounts of nitrogen (from the products and the char seem to indicate that combustion air) in the pyrolysis gas this procedure minimizes fuel handling virtually eliminates the possibility of up- problems and-produces a fuel comparable to grading any excess gas to pipeline quality very low sulphur bituminous coal. Use of by water shift and methanation. Excess

101 gas could, however, be used in specially 3.4.3.1.6 Union Carbide (Ref. 3-28, 3- designed furnaces. 47, 3-48, 3-49) .

3.4.3.1.5 Torrax (Ref. 3-26, 3-28, 3- The Union Carbide Corporation has de- " . 47, 3-48, 3-52) veloped a slagging temperature pyrolysis system, called the Purox System, which utilizes nearly pure oxygen for the com- Torrax Systems, Inc., has operated bustion of the pyrolysis char (see figure (since 1969) a 68 metric ton/day (75 ton/ 3-53) . The vertical shaft reactor vised day) slagging-temperature pilot plant is similar in operation to the systems ".' (an EPA demonstration project) in Erie using preheated air, but preheating is hot County, N. Y. The process is quite similar required when pure oxygen is used. The to the URDC system. The major, diference major advantage of using pure oxygen is in operation of the two systems is that the fact that the pyrolysis gas is virtually Torrax, in the pilot plant operation, free of nitrogen. The heating value of burns natural gas to preheat the air, then the pyrolysis is still only about 11 x 10^ recovers energy by burning the pyrolysis joules/meter3 (300 Btu/ft3), compared to gas to produce usable steam. Operating about 37 x 106 joules/m3 (1000 Btu/ff3) experience has included generation of for natural gas. The primary combustible 10,500 to 11,500 kilogram/hour (23,000 to components of the pyrolysis are hydrogen 25,000 pound/hour) of steam while consum- and carbon monoxide. Water shift reaction, ing MMR at a rate of 1.8 metric ton/hour carbon dioxide removal, and methanation (2 ton/hour). Having completed the EPA could be used, if desired, to convert this demonstration project, Torrax, in commercial gas to natural gas quality methane. On- installations, plans to offer options of site production of the oxygen for the burning about 15 percent of the pyrolysis Purox process is estimated to require ap- gas for burning in a nearby utility system proximately one-third of the energy avail- boiler. Torrax asserts that the net able in the pyrolysis gas. This could be energy recovery after deducting that used accomplished by on-site generation of in preheating air is as high as 8.7 to 9.3 electricity or by purchase of electricity x 109 joules/metric ton (7.5 to 8 x 106 if all the pyrolysis gas could be sold. Btu/^ton) of MMR, representing approximately A more detailed analysis of this process 80 percent of the energy contained in the will be presented later in section 3.4.4.1. raw'MMR. This energy data was obtained from Mr. John Stola, Operations Manager, Torrax Systems, Inc., North Tonauanda, N.Y. July, 1974.

REFUSE NEUTRALIZING FEED OFF GAS AGENT FUEL GAS OIL WATER VAPOR ELECTROSTATIC OFF GAS PRECIPITATOR OIL J OXYGEN-

MOLTEN METAL NEUTRALIZED a GLASS ORGANIC SALTS IN SOLUTION WATER_ QUENCH

GRANULATED METAL a GLASS FIGURE 3-53 FLOW DIAGRAM OF UNION CARBIDE PROCESS

102 3.4.3.2 HORIZONTAL SHAFT process flow sheet). The refuse is first fed to a metal detector where large chunks greater than 15 centimeters (6 in.) are 3.4.3.2.1 Kemp Waste Converter (Ref. 3-47) removed. The remaining material is then shredded to about 5 centimeters (2 in.) before being fed to the reactor via an air A conveyor belt is used to carry the lock. The pilot plant reactor has a capa- feed material through the reactor developed city of about 700 kilogram/day (1500 pound/ by the -Kemp Corporation. Indirect heating day) and has dimensions of 1.8 meters (6 is used to pyrolyze the organic material feet) length with a rectangular cross sec- and .produce solid, liquid and gaseous fuels. tion of 25.4 centimeters (10 in.) depth and For shredded MMR the pyrolysis temperature 45.7 centimeters (18 in.) width. would be in the range 430° to 600°C (800° to 1100°F). if desired, metals and glass . The refuse "floats" on the molten lead .can be recovered from the char after py- surface which is circulated via a gas lift rolysis at this low temperature. Experience pump. The lead bath is heated from the top to date has been with a 4.5 metric ton/day by standard radiant tube burners located (5 ton/day) pilot plant. Engineering de- in the vapor space. The refuse is pyrolyzed sign has been completed for -a soon to be from the lead surfacte at a temperature of constructed 180 metric ton/day (200 ton/day) about 650°C (1200°F) , producing a gas with commercial plant in Long Beach, 'California. a target heating value of about 1.8 to This commercial plant, however, will deal 2.6 x 10' joules/meter3 (500-700 Btu/SCF) . with nonmetallic waste from an automobile About one-fourth of the gas will be used salvage operation rather than with MMR. in the "gas lift" system. The remainder of the gas would be available for sale.

3.4.3.2.2 Barber-Colman

REFUSE PREPARATION EXHAUST

REFUSE LAFTER_ L BURNER STORAGE AIR LOCK FEED GAS _ GAS .FURNACE. .GAS. AUGER QUENCH SCRUBBER EXHAUSTER METER

WASTE _, -STEAMJ HEAT BOILER DISCHARGE CHAR CHAR COOLING - STORAGE AUGER SAMPLE TO ANALYSIS

LIQUOR TOGAS DRAIN FROM QUENCH QUENCH 8 SCRUBBER

SETTLING BASIN

CIRCULATING PUMP

• GAS TO "AIR-LIFT" PUMP-*-

FIGURE 3-54 BARBER-COLMAN PYROLYSIS SYSTEM FLOW SHEET

103 that remain on the surface are removed by prior to truck transport from the site. means of a. mechanical rake device at the opposite end of the reactor from the refuse Heavy material is conveyed from the feed part. Some low pressure steam is bottom of the flotation separator to a generated in the process. magnetic separator for removal of ferrous materials. Recovered metals are deposited either in a storage area, or directly into 3.4.3.3 ROTARY KILN a railroad car or truck. The-balance of the heavy material, now called a glassy aggregate, passes through screening equip- 3.4.3.3.1 Monsanto (Ref. 3-21, 3-22, 3- ment and is then stored on-site. This 28, 3-47, 3-60, 3-61, 3-62) glassy aggregate can be used in.building asphalt roads. The Monsanto "Landgard" process Pyrolysis gases are drawn from the (Figure 3-55) has been tailored to meet kiln into a refractory-lined afterburner, where they are mixed with air and burned. The afterburner • prevents discharge of combustible gases to the atmosphere and subjects the gases to temperatures high enough for destruction of odors. Hot combustion gases from the gas purifier pass through water tube boilers, where heat is exchanged to produce steam. The steam will be used for heating and air conditioning of buildings in downtown Baltimore. Exit gases from the boilers are further cooled and cleaned of particulate matter as they pass through a water spray scrubbing .tower. Scrubbed gases then enter an induced draft fan .which moves the gases through the entire system. To AFTER-BURNEf J- AIR suppress formation of a steam plume, the . 1 gases are passed through a dehumidifier in WASTE HEAT WATEf • STEAM - BOILER which part of the water is removed and recycled, and then the gases are discharged 1 WATE R GAS to the atmosphere. SCRUBBER 1 Normally, all water leaving the system GLASSY , AGGREGATE will be carried out with the residue, or evaporated from the scrubber. All process WET water is cleaned and recycled. Further CHAR details on this process will be presented in section 3.4.4.2. I 3.4.3.3.2 Devco Management, Inc. FIGURE 3-55 The largest system for MMR pyrolysis MONSANTO LANDGARD PYROLYSIS SYSTEM presently being constructed is the Devco plant in Brooklyn, New York. This 1360 the needs of the city of Baltimore where a metric ton/day (1500 ton/day), consists of 910 metric ton/day (1000 ton/day) plant is five parallel 272 metric ton/day (300 ton/ under construction. Shredded waste 10 day) modules. The system is basically centimeters (4 in.) in size is conveyed similar to the Monsanto systeim Probably to a storage system from which it is the most notable differences in the Devco continuously fed into a refractory-lined System are lower temperatures, less than rotary kiln. A fired fuel (oil) and 540°C (1000°F) and less preprocessing. air stream are fed into the opposite end Rather than shredding, Devco uses a proof the kiln. Countercurrent flows of prietary "selective pulverizer" which breaks up low tensile strength items in a gases and solids expose the refuse feed to low energy process. The differences in progressively higher temperatures, 1000°C preprocessing and in processing temperature (1800°F) maximum, as it passes thru the kiln, require Devco to use a somewhat larger so that first drying and then pyrolysis rotary kiln than Monsanto would use for occurs. Hot residue is discharged from the same processing rate. the kiln into a waterfilled quench tank. A conveyor then elevates the residue into The Devco system provides steam (from a flotation separator. Light material combustion of the pyrolysis gas) and char, floats off as a carbon char slurry, which which can be fired with pulverized coal, is thickened and filtered to remove the as salable products. The saturated steam water, then conveyed to a storage pile is produced at a rate of about 1.5 kilograms

104 per kilogram of MMR and has an absolute developed a pyrolysis system called the pressure of 2.8 x 10° newtons/meter2 (400 "Lantz converter". Little information is pound/in2), whereas the char is produced available. Mixed municipal refuse is fed at a rate of about 6 percent by weight of continuously through a hanunermill-to a the MMR feed. This char has a heating rotating stainless steel drum. External value of about 2.3 x 106 joulesAilogram heating is used to heat the reactor to (10,000 Btu/pound) and produces less than about 1100°C (2000°F). Natural gas is 10 percent ash when burned. used as fuel for startup. Pyrolysis gases are then recycled to the burners during normal operation. Excess gas (about 30 3.4.3.3.3 Rust Engineering (Ref. 3-57, percent) is flared, and there is char 3-58, 3-59) recovery.

. Rust Engineering, a division of 3.4.3.4 FLUIDIZED BED Wheelabrator - Frye, has been awarded part of a $10-million contract by the Metropoli- tan Sewer Board of the Twin Cities (Minne- 3.4.3.4.1 West Virginia University (Ref. apolis-St. Paul) for the design and con- 3-65, 3-66, 3-67, 3-68) struction of a pyrolysis plant. The process is still in the design and development stages. The basic process (Figure 3-56) Research on combustion and pyrolysis in fluidized beds at West Virginia Univer- sity has led to a proposal for a two bed system for the pyrolysis of MMR (see Figure 3-57). The inert bed material (sand) would be circulated between the separate combustion and pyrolysis beds, carrying combustion heat to the pyrolysis bed and pyrolysis char to the combustion bed. _SLUDGE Since air is excluded from the pyrolysis bed, the pyrolysis gas produced is relatively free of undesirable nitrogen. Such gas, with a heating value between 1.5 and 1.85 x 10' joules/meter3 (400-500 Btu/SCF), is probably dir.ectly marketable to certain utility or industrial customers, and it also has the potential to be upgraded to pipeline quality methane. Temperatures of approximately 1000°C (1800°F) in the combustion bed and 760°C (1400°F) in the pyrolysis bed have been recommended. A portion of the pyrolysis gas is cleaned (probably after cooling) and recirculated FIGURE 3-56 by blowers as the fluidizing gas in the RUST ENGINEERING PYROLYSIS PROCESS SCHEMATIC pyrolysis chanber. Preheated air for combustion of the char is used to fluidize the combustion bed. Further details on is a method of decomposing sludge in combina- the process will be presented in section tion with solid refuse to recover carbon and 3.4.4.4. fuel gas. The refuse is shredded, classified and dried and fed to the pyrolysis reactor where it is mixed with treated 3.4.3.4.2 A. D. Little (Ref. 3-70) sewage sludge. Fuel gas from the reactor is recycled while char is used to incinerate other sludge or is activated and used in A variation of the West Virginia Uni- sewage treatment. An externally heated versity Process has been proposed by rotary kiln reactor will be used. Antici- Arthur D. Little, Inc. and Combustion Equip- pated capacity is about 326 metric ton/day ment Associates, Inc. The most notable (360 ton/day), (28 percent sewage sludge change proposed is substitution of dolomite and 72 percent refuse). for sand as the material in the fluidized beds. Use of dolomite significantly changes the heat transfer characteristics due to 3.4.3.3.4 Pan American Resources (Ref. the carbon dioxide acceptor reaction. In 3-8, 3-63, 3-64) the combustion reactor the dolomite (MgO-CaC03) will absorb heat and release its carbon dioxide to the exhaust gases, The Haste Conversion Systems Division then this calcined (or regenerated) dolo- of Pan American Resources, Inc. * has mite (MgO-CaO) will pass to the pyrolysis reactor. In the lower temperature and •Pan American Resources, Inc. has terminated reducing atmosphere of the pyrolysis operations.

105 PRODUCT FUEL GAS COMBUSTION (TO SALE) 1 COMBUSTION r EFFLUENT- GAS_ (TO REFUSE DRYER) ' GAS CLEANUP - ' AND STACK) -

(SHREDDED, CLASSIFIED AND DRIED)

1• .. ,„ _ HtCYCLtL) SAND

ASH AND 1 " AGGLOMERATES '"'•..• ' (TO SALE OR^ LANDFILL). FIGURE 3-57 SCHEMATIC OF WEST VIRGINIA UNIVERSITY PYROLYSIS PROCESS jreactor the dolomite will.accept carbon 3.4.3.4.3 Coors (Ref. 3-69) dioxide and release heat. ' Because of this carbon dioxide acceptor reaction, the heat needed in the pyrolysis reactor can be Coors (Golden, Colorado) is conducting supplied with a smaller quantity of dolo*- pilot plant work with the goal of generating mite than sand. ..Also the removal of car- gas from municipal refuse to fire process bon dioxide from the pyrolysis gas via steam boilers. A 0.91 metric ton/day (1 the acceptor process .will improve the ton/day) fluidized bed system has been heating value of the gas somewhat. This tested with 5 centimeter (2 in.) shredding improvement in heating value would not and air classification pre-processing. A exceed 15 percent, however, since the West screw conveyor is used to feed the reactor. Virginia University pyrolysis gas contains The vessel is tapered with a 0.9 meter (3 only 15 percent carbon dioxide. feet) maximum diameter. Both indirect heating (superheated steam in tubes) and Another distinguishing characteristic direct heating (partial oxidation in the of the A. D. Little proposal concerns the same vessel) have been explored with the preprocessing of the MMR. They have pro- latter favored at the present time due to posed processing the MMR to Eco-FuelTM operationsl simplicity. The resultant (paragraph 3.2.4.2) before.feeding it to lowered gas heating value is not consider- the pyrolyzer. Such extensive pre-con- ed a major problem since the product is version processing should minimize dif- not transported but burned on site. Normal ficulties within the reactors. pyrolysis temperature is about 760°C (1400° P) at a gage pressure of about 7 x 104 No experimental work has apparently newtons/meter* (10 psi). been done using the'carbon dioxide acceptor process for refuse pyrolysis. The extensive preprocessing of the MMR, however, 3.4.3.5 Other Pyrolysis Work makes the procedure rather similar to coal gasification. A carbon dioxide acceptor coal gasification pilot plant which pro- A significant amount of pyrolysis work duces 4.2 x 104 cubic meters (1.5 x 106 on municipal refuse does not conveniently SCF) of gas per day is in operation in fall into the four reactor categories Rapid City, South Dakota. previously listed. Also, several systems

106 have been inadequately described in the 3.4.3.5.1 Battelle - N. H. (Molten Salt) literature - some under the guise of (Ref. 3-71) "proprietary information". Several others are strictly research scale in nature. Typically, these projects investigate The Battelle molten salt process (Fig- system subcomponents only and utilize ure 3-58) research has been conducted in a research scale equipment. An example of 10 centimeter (4 inch) diameter Inconel the research type e

FEED HOPPER BALL VALVES MOLTEN SALT REACTOR WET HEAT TAPE /J?™ LAGGED f METER STEAM GENERATOR '•—-'"TO GAS N CHROMATOGRAPH

CONDENSER

BACK PRESSURE WATER PROPORTIONING CONDENSATE REGULATOR RESERVOIR RUMP RECEIVER FIGURE 3-58 BATTELLE MOLTEN SALT LABORATORY REACTOR SCHEMATIC

FIGURE 3-59 BATTELLE MOLTEN SALT PROCESS SCHEMATIC

107 3.4.3.5.2 Hercules (Ref. 3-28, 3-72) containing 23 to 45 kilograms (50 to 100 pounds) of refuse, is placed in an electric heating mantle. Products of pyrolysis flow Hercules, Inc., and a subsidiary thru a product recovery train where tar, company, Black, Crow and Eidsness, Inc., heavy oils, lighter oil, aqueous products have done the preliminary design for a and mists are removed. Alkali and acid waste reclamation system for the State of wash towers remove gaseous products such as Delaware. This 454 metric ton/day (500 ammonia, hydrogen sulfide, carbon dioxide ton/day) system will concentrate on pro- and hydrogen chloride. The remaining gases duction of humus (see Sec. 3.5.2 for des- are measured and sampled after freezing cription of similar processes), but pyroly- out any remaining light oils. The pyrolysis sis will be used for reduction of material reactor is 46 centimeters (18 inches) in which cannot be composted. Initial study diameter and 66 centimeters (26 inches) deep of the pyrolysis system involved fuel gas and is constructed of steel. A series of production from an indirectly heated experimental runs has been conducted with fluidized bed reactor. Subsequently, various feed compositions and pyrolysis however, it was decided to concentrate temperatures. on char production using a Herreshoff furnace similar to the type sometimes used ta produce charcoal. The Herreshoff fur- 3.4.3.5.4 New York University (Ref. 3-76, nace is a collection of circular hearths 3-77) contained in a vertical shaft. Rotating arms.are used to move the feed across any hearth to a port where it falls to the E. R. Kaiser, while employed at New next hearth. Black, Crow and Eidsness York University* conducted pyrolysis re- personnel have reportedly performed ex- search with municipal refuse. A.schematic periments using both the fluidized bed of the apparatus is shown in Figure 3-61. and the Herreshoff furnace for pyrolysis, The equipment consisted of a stainless but the results and details of operation steel reactor and series of cold traps. involving the heating method are not publicly The reactor was operated in a batch mode, 'available. with a capacity of 100 grams of refuse (shredded and dried) per run. The reactor was then externally heated to about 930°C 3.4.3.5.3 Bureau of Mines (Ref. 3-22, 3-28,(1700°F). Product distribution was studied 3-73, 3-74, 3-75) as a function of heating rate.

The Bureau of Mines process is an adap- tation of a coal gasification unit. Work "The Engineering School at NYU has been to date has been conducted in small-scale dissolved and pyrolysis research is no batch processes (Figure 3-60). The reactor, longer being conducted.

LEGEND

I. THERMOCOUPLE 9. CARBON DIOXIDE AND H2S SCRUBBER Z. ELECTRIC FURNACE 10. CAUSTIC PUMP 1 RETORT 11. LAROE WET-TEST METER 4TAR TRAP 12. DRYING TUBE 5. TUBULAR CONDENSER II LIGHT OIL CONDENSER EXCESS OAS x S. 6. ELECTROSTATIC PREOPITATOR 14 SMALL WET-TEST METER IS FLARED/ \ 7 AMMONIA SCRUBBER 15. GAS SAMPLE HOLDER SAMPLE COCK FOR 2S AND NH3 TESTS

fflhfflhffl> ELEi

WATER rt>-®J®—14-1 OJt^ r-xv-xy—,

=P T^

r t: NaOH NaOH T w

DRAINS FIGURE 3-60 BUREAU OF MINES PYROLYSIS PROCESS SCHEMATIC

108 3.4.3.5.6 Anti-Pollution Systems (Ref. 3- 78) Some research has been performed by Anti-Pollution Systems, Inc., regarding the use of a molten salt bath for pyrolysis of refuse. No results of this research are publicly available, and no commercial plants have been constructed for pyrolyzing MMR. Small commercial plants 9 to 23 metric ton/day (10 to 25 ton/day) have been sold for hospital refuse and scrap yard refuse. 3.4.3.5.7 Univ. of California (Ref. 3-79) The pyrolysis reactor in the University of California studies (Figure 3-62 consists of a vertical cylinder constructed from a owr oum yog mo 30.5 centimeter (12 inch) section of 7.6 T•I Kt/mrIIU. WTTLta rwf Tl IM/WLT TRW centimeter (3 inch) diameter schedule 40, T> stainless steel pipe. Electrical heating was used. Shredded refuse was fed into the reactor via a screw conveyor and the product gases and residues were collected and FIGURE 3-61 analyzed. The effect of temperature (900«- NYU APPARATUS SCHEMATIC 1000'C or 1650"-1830'F) on product distribution was studied. 3.4.3.5.5 Univ. of Southern Calif. 3.4.3.5.8 Wallace - Atkins (Ref. 3-80) The Department of Environmental The Wallace-Atkins Oil Corporation Engineering at U.S.C. is in the early process includes a pyrolysis reactor stages of a study of pyrolysis of a mixed (horizontal shaft), electrolytic cell and sewage sludge - municipal refuse stream. fuel cell. The bacterial fuel cell is used The small, research scale reactor is to produce both electricity and methane electrically heated. Temperature and from organic waste. The electricity then residence time are being manipulated in ionizes water into hydrogen and oxygen in a parametric study to determine the an electrolytic cell. Hydrogen, refuse and effects on product distribution. methane are then fed to the pyrolysis reactor

QEAR REDUCTION MOTOR

TEMPERATURE VARIABLE TEMP MERCURY VACUUM RECORDER CONTROL MANOMETER PUMP FIGURE 3^62 UNIVERSITY OF CALIFORNIA PYROLYSIS UNIT

109 ' to produce oil, gas and solid fuel. Pro- of pilot plants and contracts to construct cess details are lacking. The company is commercial plants, and also on'the amount negotiating with several sources to build of technical information available in the a demonstration plant. published literature. Table 3-2.4 presents a classification 3.4.3.5.9 Resource Sciences (Ref. 3-47) of the various pyrolysis systems studied according to whether they use"direct or indirect heating, the .heat transfer method The Resource Sciences* resource re- for indirect heating, the pyrolysis tempera- covery system pilot plant reactor consists ture used and the type of reactor used. of an electrically wrapped horizontal cylin- Note that there is no column for slagging- der of 46 centimeters (18 inch) diameter temperature indirect heating systems since and 3.8 meters (12.5 feet) length.. Pilot direct heating is the only practical way plant capacity.is 2.1 metric ton/day (2.3 ' of achieving the temperatures greater than ton/day). Gases and char are recovered 1200°C (2200«F) for slagging. The pyrolysis while liquids are recirculated and injected systems largely fall into distinct groups . with the refuse. within the table, and an effort was made to select for further study a representative of each major group. 3.4.3.6 SELECTION OF PROCESSES FOR FURTHER ANALYSIS. As pointed out in Sec. 3.4.1.2, a vertical .shaft is the.simplest reactor type. Two systems of this type have been chosen It was deemed desirable to choose a for further study. The Union Carbide ,. small number of pyrolysis systems for more Purox process represents a system with detailed study than was possible for all direct heating and slagging of residue. the systems discussed previously. Several Construction of the 180 metric ton/day (200 bases were used in this selection procedure. ton/day), commercial Union Carbide plant- One goal was to select one representative in Charleston, West Virginia represents from each major technical category, where the highest stage of development of a plant sufficient information was available. In of this type. The Garrett process repre- choosing between technically similar pro- sents a vertical shaft with indirect heating. cesses, emphasis was placed on the stage Again, a contract has been signed for con- of development as evidenced by operation struction of a commercial plant—the. 180 metric ton/day (200 ton/day) plant in San. Diego, California. , . •Resource Sciences has terminated operations.

TABLE 3-2M PYROLYSIS PROCESS GROUPINGS

DIRECT HEATING INDIRECT HEATING (nonslagging221 ) REACTOR TYPE NONSLAGGINCT SLAGGING WALL TRANSFER CIRC. MEDIUDIlM Vert. Shaft Ga. Tech. URDC Garrett Battelle Torrax Un. Carbide

Horizon. Shaft Kemp Barber-CoIman

Rotary Kiln Monsanto Rust Devco Pan. Am. Res.

Fluid. Bed Coors West Va. Univ. A. D. Little

110 Several systems are being developed 'using indirect heating and the improved control of material flow provided by a horizontal shaft. None of these systems, to date, have received a contract to construct a commercial scale plant. Also, relatively little technical information is available for them. For these reasons none of the horizontal shaft systems have REFUSE been •'recommended for further consideration FEED HOPPER 'in this study.

Two separate systems using direct FEEDLOCK •heating at nonslagging temperatures in 'rotary kilns have received contracts to construct commercial units. A 1350 metric ton/day (1500-ton/day) Devco plant is SHAFT OFF GAS being constructed in Brooklyn, New York. FURNACE Also, a 910 metric ton/day (1000 ton/day) Monsanto Landgard plant is being constructed in Baltimore, Maryland. Of these two rotary kiln systems the Monsanto system was chosen for further study on the basis OXYGEN of availability of published technical information. This difference in the avail- COMBUSTION MOLTEN ability of information can at least par- ZONE. MATERIAL tially be attributed to the fact that the use of EPA funds for the Baltimore plant WATER QUENCH brings into .the public domain information which might otherwise be proprietary. FIGURE 3-63 As with horizontal shafts, none of the UNION CARBIDE REACTOR fluidized bed pyrolysis systems have been developed to a commercial scale. In fact the fluidized beds have not yet been de- depth is maintained between 0.9 and 2.1 veloped to full pilot plants using MMR. meters (3 and 7 feet). Thus the "batch- Considerable- information is available on type" feed system does not interfere with the research conducted by Bailie at West continuous processing in the reactor. Virginia University. Also available are independent studies of the.projected eco- It has been found that the tempera- nomics of commercial scale operations ture gradient with height is much greater using the dual fluidized bed West Virginia in the Union Carbide reactor than in the process. " Based on this information reactors of systems using preheated air. this fluidized bed process was recommended Essentially all of the drying, pyrolysis for further study. and combustion of the MMR occurs in the lower 0.9 meter (3 feet) of the Union Carbide reactor. The temperature at the FURTHER ANALYSIS OF SELECTED PYRO- 0.9 meter (3 foot) level is typically LYSIS SYSTEM ALTERNATIVES about 120°C (250°F) with temperatures between 1100° and 1650°C (2000°-3000°F), at the base of the reactor. This high 3.4.4.1 UNION CARBIDE PROCESS temperature gradient presumably is due to the high heat transfer rates of oxygen- fuel flames, as compared to air-fuel flames. 3.4.4.1.1 Technical Description (Ref. 3- One advantage of the high temperature 28, 3-47, 3-48, 3-49) .gradient is the fact that only the lowest portion of the reactor needs be lined with a' refractory material, with an uncooled Figure 3-63 presents a more detailed metal shaft being acceptable for the upper schematic of the reactor for the Union portion. Carbide system, shown schematically in Figure 3-53. Handling of the MMR is mini- Another advantage of the high tempera- mal. A crane is used to lift MMR from a ture gradient in the reactor is the fact dumping pit and drop it into the feed that the Union Carbide pyrolysis gas leaves hopper, from which it falls by gravity the reactor at about 93°C (200°F), compared through the two-seal airlock and into the to 315° to 430°C (600"-8000F) in the Torrax reactor. Experiments have shown that the system (ref. 3-52). The lower temperature . continuous pyrolysis and oxidation processes gas is much more convenient for handling are unaffected by the amount of feed main the gas clean-up train. Also, the 93°C terial in the reactor so long as the bed (200°F) temperature results in relatively

111 little loss in sensible heat of. the gas. TABLE 3-25 UNION CARBIDE FUEL Table 3-25 gives the composition of GAS COMPOSITION the Union Carbide pyrolysis gas after removal of water vapor and condensible hydrocarbons. Before passing through the '• CONSTITUENTS VOLUME % electrostatic precipitator and the condenser the gas contains about 28 percent . CO 47 water and 3 percent condensible hydro- H2 33 carbons and flyash. Since the material C02 14 removed by the electrostatic precipitor CH4 4 is recycled to the high temperature zone C2HX 1 of the reactor the liquid hydrocarbons N2 1 are cracked or combusted so that liquid loir fuel is not an end product. One of the most desirable characteristics of the pyrolysis gas is its low nitrogen content, It should perhaps be noted that after as contrasted with the gas of any system conversion to the Union Carbide system the using direct heating with air as the URDC air preheater and some of the insula- oxidant. Nitrogen in a fuel gas is, of tion and refractory material of the URDC course, undesirable not only as a dilut- reactor would not be needed. ant, but also as a source of NOX pollution when~ the gas is burned. Even though the The pollution problems of the process fuel gas is virtually nitrogen free and are considered to be very minimal. The onfy contains 14 percent diluting carbon only effluents from the plant are the fuel dioxide, it still has a heating value of gas, the inert slag, and clean water con- only about 1.06 x 10? joules/meter^ (286 densed from the fuel gas. Further, the Btu/SCF), since its primary constituents fuel gas is quite "clean" (low NOX and are carbon monoxide and hydrogen, both SOX, in particular) and should present no with low heating values. This is in special pollution problems when burned. . contract to gases from lower temperature The primary social concern relating to pyrolysis which usually cpntain greater installation of a Union Carbide plant in a amounts of methane and heavier hydrocar*- • community is apt to be related to the poten- bons. The gross energy reclamation from tial safety hazard of producing and using MMR by the Union Carbide process is a- pure oxygen. bout 8 x 109 joules/metric ton (7x106 Btu/ton) of MMR, but the oxygen production requires approximately one-third of this 3.4.4.1.2 Economic Data energy. The net energy reclamation is only about 5.3 x 10^ joules/metric ton (4.7 x 10° Btu/ton). Assuming an energy The economic data given in the follow- content of approximately 11.5 x 10 ing Process Cost Data and Resource Recovery joules/metric ton (107 Btu/ton), the Data forms, Table 3-26, are taken from ref. Union Carbide process yields a net 3-2 and 3-21. thermal efficiency of between 45 and 50 percent. The economic data for the 1814 metric ton/day (2000 ton/day) plant is based on The only usable byproduct (in addi- 365 days per year operation. The credits tion to the fuel gas) produced by this received are primarily from fuel gas at process is aggregate or frit (approxi- $0.71/109 joules ($0.75/106 Btu). The mately 28 percent by weight of the MMR) pyrolysis gas is assumed to have a heating resulting from quenching of the slag. value of approximately 1.12 x 10? joule/ Presently available technology does not meter3 (300 Btu/SCF). Considerable addi- seem to favor reclamation of usable tional treatment would be needed before it metals or glass from this slag. Of could be used as pipeline gas in interstate course it would be possible to add pre- commerce; however, local sales should be reactor processing for material re- possible. Fused metal and glass frit is covery if justified by economic or recovered at the rate of 20 tons per 100 other reasons.1 • tons of' MMR and is credited at the rate of $2.00 per ton. No credit is given for Something of an amalgamation of the metal recovery in this process (ref. 3-21). processes of Union Carbide and URDC has been proposed by Hamilton Standard (ref. The economic data for the 907 metric 3-81). They suggested a staged develop- ton/day (1000 ton/day) plant is based on ment wherein a URDC system with heated 300 days/year operation. Credit for the air for oxidation would be constructed sale of gas is given at $0.47/10^ joules initially. Then at any subsequent time (S.50/106 Btu). It is estimated that 75 when the cost was justified an oxygen percent of the assumed 1.049 x 107 joules/ separation plant could be added, convert- kilogram (4500 Btu/pound) heating value of ing the system to the Union Carbide process. refuse is recovered. Labor costs are

112 TABLE 3-26 ECONOMIC DATA-UNION CARBIDE SYSTEM PROCESS COST SHEET PROCESS NAME: Union Carbide DATA SOURCE: Reference 3-21 CAPACITY IN TONS/DAY: 1814 metric tons (2000 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt . Processing Eqmt Postprocessing Eqmt Utilities Building. & Roads Site Preparation Engr. & R & D Plant Startup Working Capital Misc.:

TOTAL $24,400,000

OPERATING COSTS .($ PER YR) Maint. Material Maint. Labor Dir. Labor Dir. Materials Overhead Utilities Taxes Insurance Interest Disposal of Residue Payroll Benefits Fuel Misc. :

ased on 365 Days/Yr TOTAL $ 3,255,800 peratio..

CREDITS ASSUMED ($ PER YR) $ 4,015,000 DOLLARS/YR. COMMENT

Fuel: Liquid Gas $ 3,723,000 Solid Power: Steam Electricity Hot Water Magnetic Metals Nonmagnetic Metals 292,000 Based on $2.2I/ Glass metric ton ($2/ton) Ash Paper Other:

TOTAL ($ PER YR.) $ 4,015,000

,113 TABLE 3-26 (CONTINUED) PROCESS NAME: Union Carbide DATA SOURCE: Reference 3-2 CAPACITY IN TONS/DAY: 9f07 metric tons (1000 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land 150,000 Preprocessing Eqmt ) Processing Eqmt ) Postprocessing Eqmt) 9,450,000 Utilities ) Building & Roads ) Site Preparation 150,000 Engr. & R & D 450,000 Plant Startup 214,000 Working Capital 320,000 Misc.:

TOTAL $10,734,000

OPERATING COSTS ($ PER YR Maint. Material Maint. Labor ) Dir. Labor ) $ 623,000 @ $5/hr Dir. Materials 45,000 Overhead 171,000 Utilities 425,000 Taxes Insurance Interest Disposal of Residue Payroll Benefits 187,000 @ 30% of Labor Fuel Misc.:

TOTAL $ 1,451,000

CREDITS ASSUMED ($ PER YR 1,200,000

DOLLARS/YR. COMMENT

Fuel: Liquid Gas $1,020,000 @ $0.47/109 joules Solid ($.50 per MM Btu) Power: 1.12 x 107 J/SCM Steam Approximately (300 Electricity Btu/SCF) Hot Water Magnetic Metals Nonmagnetic Metals Glass •180,000 $3.31/metric ton Ash ($3 per ton) Paper Other:

TOTAL ($ PER YR.) $1,200,000

114 calculated at $5.00 per hour and payroll atmosphere and subjects them to temperatures benefits at 30 percent of labor (ref. 3-2) high enough to destroy odors. Hot combustion gases from the gas 3.4.4.2 MONSANTO PROCESS purifier pass through water tube boilers where heat is exchanged to produce steam. Exit gases from the boilers are further 3.4.4.2.1 Technical Description (Ref. cooled and cleaned of particulate matter 3-;21, 3-22, 3-28, 3-47, 3-60, as they pass through a water spray scrubbing 3-61, 3-62) tower. Provisions are included to allow gases exiting from the gas purifier to completely or partially bypass the boilers Monsanto's Landgard process is a two- and enter the scrubber tower directly. stage combustion, pyrolysis system using supplemental .fuel (see figure 3-55 for. Scrubbed gases then enter an induced the process flow sheet). A waste heat draft fan which provides the motive force recovery boiler can be added to produce for moving the gases through the entire steam. In the Landgard process, refuse system. Gases exiting the induced draft is delivered to the disposal plant in fan are saturated with water. To suppress packer trucks. The refuse is stored on formation of a steam plume, the gases are a concrete pad, reclaimed with front-end passed through a dehumidifier in which they loaders and fed directly to either of two are cooled (by ambient air) as part of the 907 metric ton/day (1000 ton/day) horizon- water is removed and recycled. Cooled tal shaft hammermills which reduce the process gases are then combined with heated refuse to 7.6-10 centimeters (3-4 inches) ambient air just prior to discharge from and which will be operated on an 8-hour the dehumidifier. shift. Provision has been made for a third shredder. After shredding, the Solids are removed from the scrubber refuse is conveyed to storage. From here by diverting part of the recirculated the shredded refuse is fed continuously water to a thickener. Underflow from the to the refractory lined rotary kiln. thickener is transferred to the quench tank, while the clarified overflow steam Pyrolysis takes place in the kiln at is recycled to the scrubber. 6508-980°C (1200"-1800I>P) , with air and fuel added at the discharge end of the Normally all the water leaving this kiln. A counter current flow of gases system would be discharged with the resi- and solids exposes the feed to progressive- due, or evaporated from the scrubber. An ly higher temperatures as it passes through occasional process upset may allow too the kiln, so that drying first occurs much water into the system and make it followed by pyrolysis. The finished re- necessary to purge the excess. This purge sidue is exposed to the highest temperature stream will be discharged to the sanitary just before it is discharged from the kiln. sewer at a maximum flow of 285 liter/ The kiln has been designed to expose solid minute (75 gallon/minute). particles uniformily to high temperatures before they are discharged to maximize the A total of 27 liters (7.1 gallons) of pyrolysis reaction. No. 2 fuel is used per 0.91 metric ton (1 ton) of refuse; 88 percent of the fuel The hot residue at 980°C (1800°F) is is fed to the pyrolyzer and 12 percent to discharged from the kiln into a water-filled the gas purifier. Forty percent of the quench tank from which a conveyor elevates ' air required for stoichiometric combustion the wet residue into a flotation separator. of the refuse is fed to the kiln. Light material floats off as a carbon char slurry and is thickened and filtered to The yield of products from 0.91 metric remove the water. Clarified water and fil- ton (1 ton) of refuse is as follows: trate are recycled for reuse. Carbon char is conveyed to a storage pile prior to truck 1. Steam - About 220 kilograms (4800 transport to a landfill. Heavy material is pounds) of saturated, low-pressure, conveyed from the bottom of the flotation low-temperature steam. In Balti- separator to a magnetic separator for more, this steam is valued at removal of iron, which is either deposited SI.80/1000 kilogram ($0.81/1000 in a storage area or is deposited directly pounds). Assuming the steam con- into a rail car or truck. The balance of tains 2.5 x 106 joules/kilogram the heavy material, glassy aggregate, (1100 Btu/pound), the total amount passes through screening equipment and is of recovered heat is about 6.1 x then stored on-site. 1010 joule/metric ton (1 x 10? Btu/ton) and the 27 liters (7.1 Pyrolysis gases at 6508C (1200°F) are gallons) of fuel oil another 1 x drawn from the kiln into a refractory lined 109 joule (1 x 100 Btu), the gas purifier where they are mixed with air overall thermal efficiency is and fuel and burned. The gas purifier pre- 48 percent. vents discharge of combustible gases to the

115 2. Ferrous Scrap - Ferrous scrap TABLE 3-27 (CONTINUED) valued at S7.6/metric ton ($7/ ton) can be recovered at a rate' KILN OFF-GAS ANALYSES of about 5-7 percent of MMR weight. '' (Based on 27 (Vol. percent Dry Basis) Sample Runs) 3. Glassy Aggregate - About 155 Nitrogen 69.3 kilograms (340 pounds) of glassy Carbon Dioxide 11.4 aggregate, which is suitable for Carbon Monoxide 6.6 use as clean fill, or possibly as Hydrogen 6.6 a filler in building materials, Methane 2.8 and valued at $2.2/metrie ton . Ethylene 1.7 ($2/ton), will be produced. Oxygen 1.6 4. Char - About 72 kilograms (160 pounds) (on a dry basis) of char RESIDUE ANALYSIS .' is produced. The char is 46 per- (Wt. percent Dry Basis) cent glass and ash, 50 percent carbon, 3.5 percent volatiles and Proximate Analysis Ultimate AnalysiLysis 0.2 percent sulfur. Its heating Volatiles5.5 Metal (Fa) TTT value is about 1.6 x 10' joules/ Fixed Carbon 12.5 Glass + Ash 60 kilogram (7000 Btu/pound). The Inerts 82.0 Carbon 14 char produced at Baltimore is Sulfur 0 50 percent water, is assumed to Hydrogen 0 have no value, and will be land- Nitrogen 0.2 filled. Oxygen 2.7 , Monsanto has operated a 32 metric ton/ Higher Heating Value .570 x 107 joules/kg day (35 ton/day) pilot plant for two years. (2500 Btu/lb)(metai-fre Typical analyses of feed and products are pH - 12.0 given in, Table 3-27. Its 910 metric ton/ day (1000 ton/day) demonstration plant in Water soluble solids 2 percent Baltimore is scheduled for start-up in Fall, 1974.' AS the technology is rela- Putresciblea 0.1 percent (Enviro-Chetn Anar/ tively well developed, start-up should pro- lytical Method based on stand- ceed relatively smoothly. If residue ard 5 day BOD test) recovery is desired, a big area of uncertainty is likely to be the quality and quantity of the glassy aggregate and char EFFLUENT GAS ANALYSIS and their market values, Difficulties (Vol. percent Dry Basis) may also be encountered with the disposal Nitrogen .79.2 of water in the scrubbing and back end Carbon Dioxide 8.0 treatment circuits. Oxygen 12.8 Average analysis of effluent gas pollutants TABLE 3-27 was: MONSANTO LANDQARD Particulate 6.2 x 10-5 Kg/m3 PROTOTYPE PERFORMANCE RESULTS (0.027 grains/SCF dry gas)

FEED ANALYSIS (AS RECEIVED) CARBON CHAR PROPERTIES , (Wt. percent) Properties of the Carbon Char are: Proximate Analysis Ultimate Analysis Moisture 65 Percent by Wt. Moisture20.8 .Metal (Fe) 7.0 Volatiles 44.8 Glass + Ash 19.3 Dry Basis Wt. Percent Fixed Carbon 8.1 Water 20.8 Volatile . 4.0 Inerts 26.3 Carbon 25.1 Carbon 50.0 Sulfur 0.3 Ash (Ash & Glass) 45.8 Hydrogen 3.0 Sulfur 0.2 Nitrogen 0.4 Total 100.0 Oxygen 24.1 Bulk Density 320 - 800 kg/m3 Higher Heating Value (Wet Basis 1.067 x (20 - 50 lbs/ft3) 10' joulesAg (4600 Btu/lb) Absorption Activity 430 m/g

116 TABLE 3-27 (CONTINUED) The final cost table relating to the Monsanto system was taken from a study done for Monroe County, Rochester, N.Y. in 1971,. Size No detail costs were given, but the 1971 figures indicate a cost of $12.67/metric U.S. Mesh Percent Retained ton ($11.49/ton), but this does not pro- +T5 23 vide for any credits for recovered products. -18 + 50 40 -50 + 100 12 -100 + 230 9 3.4.4.3 GARRETT PROCESS -230 14 3.4.4.3.1 Technical Description (Ref. 3- Ferrous Metal Properties 18, 3-21, 3-22, 3-28, 3-47, 3- -50, 3-51) •••••;_• Iron 98.85 Percent by Wt. Impurities 1.15 Percent by Wt. The process of the Garrett Research and Development Company, the research or- Glassy Aggregate Properties ganization supporting the Occidental Petroleum Corporation, was developed as Bulk Density 1442 „„,._ , a spin-off of its coal-conversion research. (90 lbs/Ft3) See Figure,3-48 for the flow schematic. The process incorporates the following Composition Wt. Percent features! Glass 53 Ferrous Metal 3 1. an extensive pretreatment and Non-Ferrous Metal 2 drying system, Carbon 2 2. rapid heating and pyrolysis Rook S Miso. 28 (short residence time), 3. condensation of gaseous pyrolysts products to yield a hydrocarbon 3.4.4.2.2 Economic Data vapor fraction, a hydro-liquid fraction, and water, 4. most likely, recycling of solid Projected economic cost studies as products to facilitate heat reported in Schulz, et.al., (ref. 3-21). transfer. The referenced report contains a detailed explanation of the assumptions and some A pilot facility with a capacity of about of these are noted below: 3.6 metric ton/day (4 ton/day) has been in operation at Garrett, and results pre- Interest rate 6.5% sented below are based on the performance Useful life assumed 15 years of this plant. Environmental Impact Stack emissions and solid Garrett is presently constructing a residue 181 metric ton/day (200 ton/day) demonstra- Net credit given for tion plant for the pyrolysis of refuse for recovery of metal $1I/metric ton San Diego County under'an EPA grant. In ($10/ton) this process, refuse from packer trucks is Land Cost Not specified dumped into a pit and reclaimed with a Waste Residue 118 metric ton/ strip loader. The refuse is discharged day (130 onto a conveyor with facilities for hand- ton/day) sorting material of value and material too heavy to shre'd. The refuse is then fed to This report does not specify any trans- a primary shredder and cut up into pieces portation cost associated with the ferrous of about 2.5 centimeters (1 inch). metals recovered, but current plans indicate that they will be transported from The shredded material is classified Baltimore to St. Louis, Missouri. in three stages, using, first, a zig-zag air classifier which reduces the inor- The next two sets of data are updates ganics in the light fraction to about 10 to reflect increasing energy costs. These percent and, second, using a two-deck costs were received from EPA in a June, screen with 0.63 centimeters (0.25 inch) 1974, telephone conversation with Mr. David and 14-mesh openings to reduce the in- Sussman, EPA Project Monitor for Landgard. organics in the light fraction to about 2 percent. Finally, the light fraction Amortized interest rate 6% is dried in a rotary drier to about 3 Useful life 20 years percent moisture after the air classifier Cost of 06 fuel oil $0.07/liter but before the screen classifier operation. ($11.00/barrel) The clean organic fraction is then shredded

117 TABLE 3-28 (A) ECONOMIC DATA-MONSANTO LANDGARD SYSTEM .PROCESS NAME: Monsanto Landgard DATA SOURCE: Reference 3-21 CAPACITY IN TONS/DXY: 907 metric tons,. (1000 tons) DOLLARS COMMENTS CAPITAL COSTS (TOT. $) Land •» Preprocessing Eqmt Processing Eqmt Postprocessing Eqmt Utilities 14,700,000 Building & Roads Site Preparation Engr. & R & D Plant Startup Working Capital Misc.:

TOTAL 14,700,000

OPERATING COSTS ($ PER YR) Maint. Material Maint. Labor. - Dir. Labor pir. Materials Overhead j Utilities; Taxes • ' Insurance, Interest 2,418,000 ased on $8 .87/metric Disposal of Residue ;on x 907 metric ton/ Payroll- Benefits ay x 300 days/year Fuel -• ' - Based on $8.06/ton • Misc.: Disposal of 1000 tons/day x 300 Water Residue 195,000 ays/year) TOTAL 2,613,000

• CREDITS ASSUMED ($ PER .YR $4.22/metric ton ($3.83/ton) DOLLARS/YR. COMMENT

Fuel: Liquid Gas Solid Power: ; Steam 1,164,000 Electricity . Hot Water Magnetic Metals 210,000 Nonmagnetic Metals Glass . 75.,000 Vitreous Frit Ash Paper Other:

TOTAL ($-PER YR.) 1,449,000

118 TABLE 3-28 (B)

PROCESS NAME: Monsanto Landgard DATA SOURCE: January, 1973, estimates obtained from David Sussman of EPA in June, 1974. (telephone conversation DAPACITY IN TONS/DAY: 907- metric tons (1000 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land. Preprocessing Eqmt . Processing Eqmt Postprocessing Eqmt Utilities Building & Roads Site Preparation Engr. & R & D 14,742,000 Plant Startup Working Capital Misc.: 126,000

TOTAL 14,868,000

OPERATING COSTS ($ PER YR] Maint. Material 552,000 Maint. Labor Dir. Labor 306,000 Dir. Materials 93,000 Water and Chemicals Overhead Utilities • 318,000 Electricity Taxes Insurance Interest Disposal of Residue 54,000 Char removal Payroll Benefits Fuel Misc.: 267,000

TOTAL 1,590,000

CREDITS ASSUMED ($ PER YR) 1 DOLLARS/YR. COMMENT

Fuel: Liquid Gas Solid Power: Steam 1,167,000 Electricity Hot Water Magnetic Metals 132,000 Nonmagnetic Metals Glass 102,000 Ash Paper Other:

TOTAL ($ PER YR.) 1,401,000

119 TABLE 3-28 (C) PROCESS NAME: Monsanto Landgard DATA SOURCE: February, 1974 estimates obtained from David Sussman of EPA in a telephone conversation, June, 1974.. CAPACITY IN TOTS/DAY: 907.metric tons (1000 tons) DOLLARS COMMENTS CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt Processing Eqmt Postprocessing Eqmt Utilities 14,742,000 Building 6 Roads Site Preparation Engr. & R & 0 Plant Startup Working Capital Misc.: 120,000 Use 6% & 20 yrs to TOTAL 14,862,000 amortise)

OPERATING COSTS ($ PER YR Maint. Material 570,000 Maint. Labor Dir. Labor 330,000 Dir. Materials 90,000 ater & Chemicals Overhead Utilities 390,000 lectricity Taxes . Insurance Interest Disposal of Residue 60,000 har Removal Payroll Benefits Fuel 600,000 Misc.:

TOTAL 2,040,000

CREDITS ASSUMED ($ PER YR ($7.20/ton), DOLLARS/YR. COMMENT

Fuel i Liquid Gas Solid

Power: . 'S--- Steam 3,450,000 •' Electricity Hot Water Magnetic Metals 300,000. Nonmagnetic Metals Glass 120,000 Ash Paper Other:

TOTAL, <($ PER YR.) 3,870,000

120 TABLE 3-28 (D)

PROCESS NAME: Monsanto Langard DATA SOURCE: Reference 3-82 >bi- CAPACITY IN TONS/DAY: 907 metric tons (1000 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt . Processing Eqmt ' Postprocessing Eqmt Utilities Building 6 Roads Site Preparation Engr. & R & D Plant Startup Working Capital Misc.:

TOTAL

OPERATING COSTS ($ PER YR Maint. Material Maint. Labor .: - . Dir. Labor •Dir. Materials Overhead Utilities Taxes Insurance Interest Disposal of Residue 8.82/metric 'ton Payroll Benefits- • $8.00/ton) .plus a- Fuel mortization of plant Misc.: nd site yields 12.67/metric ton C$11.49/ton) gross TOTAL disposal cost.

CREDITS ASSUMED ($ PER YR

to about 28 mesh size. The overall power However, it is quite likely that the system requirements are about 82 kilowatt'per is very similar to that described in the metric ton (100 horsepower per ton), patent literature for the coal gasifica- equally split between the two stages. tion version of their pyrolysis process (ref. 3-83). In this process, hot recycled The finely shredded refuse is flash- char is transported into the reactor bot- pyrolyzed at about 480»C (900°F). The tom by recycled - gas. Upon contact with the pyrolysis products pass through a cyclone hot char,"the refuse is rapidly heated to for char removal and are cooled using a its decomposition temperature as it is direct-contact water condenser. The oil' blown at high Velocity through the reactor. is removed as a liquid and the moderate Residence times of 0.1 to 3 seconds are heating value gas, 1.9-2.2 x 107 joule/ 3 3 claimed. The reactor products consist of meter , (500-600 Btu/feet ) is recycled volatized hydrocarbons and char solids. for process heat. An unspecified portion The gas is separated from the solids by of the char is also used for process heat. means of a device such as a cyclone or The waste water, containing a variety electrostatic precipitator. The solids are of organic compounds, must also be treated then conveyed by means of an air stream prior to disposal. through a heater where the air partially oxidizes the and heats it to an Garrett has not revealed the reactor -elevated temperature. Alternately, the heat transfer method used in their process. char may be heated by utilizing a shell

121- and tube heat exchanger. The heated recovered are the ferrous metals and glass. char is then passed thru another gas- No data are given on the quality of the solid separator twice after which it ferrous metals. The glass fraction is is picked up by the gas recycle stream reportedly of high purity; it is color- and conveyed to the reactor. mixed and of sand size. Test melts with this material have shown none of the de- The heavy inorganic fraction from fects commonly reported when using re- the air classifier and screen is further claimed glass. A more detailed descrip- "-. screened to recover organics, which are tion of the Garrett preconversion system then recycled to the process. The ferrous has previously been presented in section metals are recovered magnetically, with 3.2.4.3. the remaining inorganics fed to a wet classifier in which the very fine particles .The quantities of gas, liquid, and (mostly silica) -are removed. The washed char produced may vary considerably with material is then sent to a flotation unit • feed sample and process conditions, as and a relatively pure glass fraction is judged by the range of product mix report- recovered: .It is not clear how the non- ed by Garrett, even in a single article. ferrous metals are recovered, if'at all, The data in Table 3-29 represents one • in the Garrett Process. estimate of the product mix. The products which can ultimately be The physical .and chemical properties recovered using this process are shown in of the oil fraction and that of a typical Table 3-29. Presently,.the only inorganics No'. 6 are shown in Table 3-30. The py-

TABLE 3-29 RECOVERABLE PRODUCTS AND ENERGY - GARRETT PYROLYSIS PROCESS Recoverable Products As Received Estimated Recovered Composition Recovery Products (% by wt) (% by wt)

A. Inorganic Products Magnetic Metals 6-8 95 5.7 - 7.6 Non-magnetic Metals 1-2 95 0.9 - 1.9 «»• Glass • - . . 6-10 80 4.8 - 8.0 Dirt & Debris 2-4 B. Organic Products 50-60 Pyrolytic Oil 40 20 - 24 Pyrolytic Char 30 15 - 18 Pyrolytic Gas 20 10 - 12 •Moisture , 10 10 - 10 Recoverable Energy Joule/metric ton Btu/ton Joule/metric ton" Btu/ton Energy Available 11.64 x 10,000,000 11.64 x 10,000,000 Energy in Product Pyrolytic Oil 4.89 x 109 4,200,000 5.85 x 109 5,040,000 Pyrolytic .Char 3.14 x 109 2,700,000 3.77 x 109 3,240,000 ' Pyrolytic Gas 0.86 x 109 _ !49'999 •1.03 x 109 888,000 8.89 x 109 7,640,000 10.65 x 9,168,000 Energy Consumed in Process 100% of Pyrolytic Gas 0.86 x 109 .. 740,000 1.04 x 109 888,000 25% of Pyrolytic Char 0.79 x 109 675,000 0.94 x 109 '810,000 1.65 x 109 1,415,000 1.98 x 109 1,698,000

Net Energy Produced -•? •' Pyrolytic Oil 4.89 x 109 4,200,000 5.87 x 109 5,040,000 Pyrolytic Char 2.36 x 109 2,025,000 2.83 x 109 2,430,000 7.25 x 1.09 6,225,000 8.70 x 109 7,470,000

122. TABLE 3-30 PHYSICAL AND CHEMICAL PROPERTIES OF OIL FRACTIONS

Mo. 6 Pyrolytic Oil. ";,.,6 Carbon Percent by Weight 85.7 57.5 Hydrogen' Percent by Weight 10.5 .-7.6 ..; , ..^-r Sulfur Percent by Weight 0.5-3.5 0.1-0.3c - . .*•*. Chlorine Percent by Weight • 0.3 • : .-ij Ash Percent by Weight 0.01-0.5 . 0.2-0.4? >- ..^. Nitrogen Percent by Weight • - 0.9--. -L- Oxygen • Percent by Weight 2:0 . 33.4 • :...;>, Energy 4.24 x 10? .jou 2.45 x 10? joulesAg, (18,200 Btu/lb) . > (10; 500-Btu/lbh»am Specific Gravity 0.98- ' . •/ 1-.3. ,. '-a Viscosity SSU @ 88"C (190°F) 340 - 3,150.- .-: -.-..?-

rolytic .oil is acidic and may require TABLE 3-32 - treatment to permit storage in steel tanks. GARRETT PYROLYSIS Its ash content may dictate the need for CHAR COMPOSITION a cleanup system. Burners may require revision before this oil can be fired. Constituent Weighig t % The gas has a heating value of about Carbon 45 . 1..9-2.2 x 10? joule/meterJ (500-600 Btu/ Hydrogen 3.9 foot^), and its composition '(on a mole Nitrogen 1.1 basis) is given in Table 3-31. Sulfur 0.3,Afl Ash 31.8 Chlorine . 0.2 TABLE 3-31 Oxygen (by difference) 13.9 GARRETT PYROLYSIS GAS COMPOSITION product, the oil fraction:' - .*••,-••- •*. Gas; Mol. % Carbon Monoxide 42.0 1. Possible treatment to adjust the Carbon Dioxide 27.0 pH to permit storage in-steel Hydrogen 10.5 equipment; Methane , 5.9 2. The need for air pollution-con-.'? Ethane -, 4.5 trol equipment because of the Cs-Cy Hydrocarbons 8.9 high ash content of the oil; Methyl Chloride 0.1 3. The ability to burn this oil;in Water < 0.1 gas/oil boilers using standard burners. This gas is presently consumed in the process, but it could be burned for the re- Development work is also required on covery of heat. the process for recovering non-ferrous • ;' metals. Garrett has reported no work in The char is a high-ash, low-heating this area to date. .ns The principal area of/uncertainty in the Garrett process is the pyrolysis step. Much more information is required on" 3.4.4.3.2 Economic Data the yield and composition of the three products. It appears that all pyrolysis work to date has been done using material The economic data given in the follow- from the Black-Clawson plant'in Franklin, ing Process Cost Data and Resource Re- Ohio. (See Section 3.2.4.4 for a dis- covery forms are taken from the Schulz, cussion of Black-Clawson process.) et.al., report (ref. 3-21) from the MRI report (ref. 3-2) and from Mallan and There are also several potential Finney (ref. 3-51). problems concerning the most important

123 In ref. 3-21 the economic data is metal and glass. Clogging of the grate in based on 365 days per year operation. One Bailie's experimental unit, which had no of the major differences between the eco- inert removal capability, occurred quite nomic data presented here and that pre- predictably due to build-up of glass and sented in other sources is the amount of "sticky" metal. This clogging was, no credit given for resources recovered. The doubt, accentuated in the experimental magnetic metals are credited at $1.00/ unit by the fact that the grate was main- metric ton ($10.00 per ton) with 6.6 tons tained at a temperature above the melting of metal recovered per- 100 tons of MMR. point of some steels. This hot grate Glass cullet is.credited at $5.5I/metrie was the result of a hot gas flow to heat ton ($5.00/ton) with 5.6 tons recovered per the reactor (rather than a hot sand flow) 100 tons of MMR. Schulz questions whether and should not occur in an operational the byproduct credit for glass cullet will plant. Without the hot grate there may offset the incremental processing cost not be clogging from steel, but the 800°C necessary to obtain it. Energy credits (1500°F) sand temperature in the pyrolysis are given at $0.10/liter ($15.35/barrel) reactor can certainly be expected to cause of oil. This appears high in light of the problems from melting glass and aluminum. fact that the oil contains only 2.45 x 10' Thus, design of the "sand cleanup" unit joules/kilogram (10,500 Btu/pound) roughly on the schematic diagram (Figure 3-57) may 60 percent of the heating value of #6 be quite difficult, and certainly will be fuel oil. Waste disposal is assumed to tied to the degree of preprocessing given cost $5.5I/metrie ton ($5.00/ton) with 12.8 the MMR prior to pyrolysis. The Stanford tons of waste per 100 tons of MMR. Table Research Institute study (ref. 3-68) re- 3-30(a) gives the economic data for the commended shredding the MMR to 2.5 centi- study prepared for the city of New Yorrk in meter (1 inch) maximum particle size, 1973. then using air classification. They estimated that the air classifier could be The economic data given in ref. 3-2 adjusted such that the lighter fraction assumes 300 days of operation and credits would contain all the organics and about for the liquid oil, ferrous metals, and 25 percent of the inorganics. This lighter glass. The economics of various plant fraction, which would then be pyrolyzed, sizes are also given ranging from 227 metric would contain about 8 percent inert material, ton (250 ton) capacity to 1814. metric ton largely glass. Although this is much (2000 ton) capacity. Table 3-30 (b) gives better than the 26 percent inert content the MRI estimates. which might be typical of MMR (or the 40 percent reported by Bailie in his tests), Mallan.^and Finney (ref. 3-51) base the potential problems with this glassy their costs 'on 350 day/year and 24 hour/day inert material in the reactors can hardly operation. Shredding is estimated at $1.76/ be ignored. metric ton ($1.60/ton) and all gas produced is burned on site for process heat. Table 3-34 gives an analysis of the Table 3-30(c) lists the estimates of ref. dried pyrolysis gas from the WVU process. 3-51. The absence of nitrogen as a dilutant and the significant content of hydrocarbons give the gas a reasonably good heating 3.4.4.4 WEST VIRGINIA UNIVERSITY (BAILIE) value of about 1.65 x 10' joules/meter3 PROCESS (440 Btu/SCF). This gas should be quite valuable to many markets such as utility boilers provided transportation distances 3.4.4.4.1 .Technical Description (Ref. 3- are relatively small. The gas could be up- 65, 3-66, 3-67, 3-68) graded to pipeline quality by a water- shift reaction, carbon dioxide removal, and methanation, if justified by transpor- Because of the lack of operational data tation costs or by unwillingness of poten- from a complete pilot plant many questions tial customers to install special burners concerning the West Virginia University for direct use of the moderate heating (WVU) process are yet unanswered. One may value gas. anticipate that the greatest difficulties will probably be associated with moving From the numbers in Table 3-34 one the hot sand between the two reactor cham- finds that the predicted energy recovery bers and with removal of ash and other inert of the WVU process is about 9.6 x 10' material from the sand. Of course the joules/metric ton (8 x 106 Btu/ton) for chemical industry has had considerable ex- dry MMR. Assuming on energy content of perience with fluidized beds, but they 11.6 x 109 joule/metric ton (10 x 106 Btu/ have not used such a heterogeneous feed ton) of refuse, the thermal efficiency is material with such a content of inert very high. If the refuse moisture content solids as will be the case with MMR. is 25 percent, a thermal efficiency greater than 60 percent is obtained in the process. One result of Bailie's tests with raw In addition to this substantial energy re- MMR was the fact that preprocessing is covery some recovery of materials could necessary to remove at least some of the easily be added to the system. Since

124 TABLE 3-33 (A) ECONOMIC DATA-6ARRETT PYROLYSIS PROCESS PROCESS COST SHEET PROCESS NAME: Garrett DATA SOURCE: Schulz report, ref. 3-21 CAPACITY IN TONS/DAY: 1814 metric tons (2000 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt Processing Eqmt Postprocessing Eqmt Utilities- Building & Roads Site Preparation Engr. & R & D Plant Startup Working Capital Misc.:

TOTAL $28,000,000

OPERATING COSTS ($ PER YR) Maint. Material Maint. Labor Dir. Labor Dir. Materials Overhead Utilities Taxes Insurance Interest Disposal of Residue $ 553,000 Payroll Benefits Fuel Misc.:

TOTAL $ 7,420,000

CREDITS ASSUMED ($ PER YR) $ 3,108,000 DOLLARS/YR. COMMENT

Fuels Liquid $2,450,000 Oil at $0.10/liter Gas (Oil & $15.35/bbl or Solid 3.50 x 2000 x 350) Power s Steam Electricity Hot Water High purity metals Magnetic Metals 462,000 $ll/metric ton ($10/ Nonmagnetic Metals ton or .66 x 2000 x Glass 196,000 350) Ash Paper Glass at $5.51/ Other.: metric ton ($5/ton or 28 x 2,000 x 350)

TOTAL ($ PER YR.) $3,108,000

125 TABLE.3-33 (B) PROCESS COST SHEET PROCESS NAME: Garrett DATA SOURCE: MRI Report, *ef. 3-2 CAPACITY IN TONS/DAY: 227 metric tons (25.0 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land '. • Preprocessing Eqmt . Processing Eqmt Postprocessing Eqmt Utilities Building & Roads Site Preparation Engr. & R & D ; Plant Startup Working Capital Misc.:

TOTAL $4,200,000

OPERATING COSTS ($ PER YR! ; Maint. Material Maint. Labor Dir. Labor Dir. Materials : Overhead Utilities Taxes Insurance Interest Disposal of Residue Payroll Benefits Fuel Misc.:

TOTAL $ 657,000

CREDITS ASSUMED ($ PER YR) $ 404,250 DOLLARS/YR. COMMENT

'Fuel: Liquid $ 306,000 Gas Solid Power: Steam Electricity. Hot Water Magnetic Metals 50,250 Nonmagnetic Metals Glass .48,000 .Ash Paper Other:

TOTAL ($ PER YR.) $ 404,250

126 TABLE 3-33 (B) (CONTINUED) PROCESS COST SHEET PROCESS NAME: Garrett DATA SOURCE: MRI Report, ref. 3-2 CAPACITY IN TONS/DAY: 453 metric tons (500 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt . Processing Eqmt Postprocessing Eqmt Utilities Building & Roads Site Preparation Engr. & R & D Plant Startup Working Capital Misc.:

TOTAL $7,200,000

OPERATING COSTS ($ PER YR Maint. Material Maint. Labor Dir. Labor Dir. Materials -, Overhead Utilities Taxes Insurance Interest Disposal of Residue Payroll Benefits Fuel Misc.: *

TOTAL 1,444,500

CREDITS ASSUMED ($ PER YR)|$ '808,,500 | DOLLARS/YR. COMMENT

Fuel: Liquid $ 612,000 Gas Solid Power: Steam Electricity Hot Water Magnetic Metals 100,500 Nonmagnetic Metals Glass 96,000 Ash Paper Other:

TOTAL ($ PER YR.) $ 808,500.

127 • TABLE :3-33 (B) (CONTINUED) PROCESS COST SHEET PROCESS NAME: Garrett DATA SOURCE: CAPACITY IN TONS/DAY: 907 metric tons (1000 tons) '• DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) „ Land Preprocessing Eqmt Processing Eqmt Postprocessing Eqmt Utilities Building & Roads $12,300,000 Site Preparation Engr. S R & D Plant Startup Working Capital Misc.:

TOTAL $12,300,000

OPERATING COSTS ($ PER YR Maint. Material Maint. Labor Dir. Labor Dir. Materials Overhead Utilities $ 3,888,000 Taxes Insurance . Interest Disposal of Residue Payroll Benefits Fuel Misc.:

TOTAL $ 3,888,000

CREDITS ASSUMED ($ PER'YR) $• 1,617,00<>| DOLLARS/YR. COMMENT

Fuel: Liquid $1,224,000 Gas Solid Power: Steam Electricity • Hot Water Magnetic Metals 201,000 Nonmagnetic Metals Glass 192,000 Ash Paper Other:

TOTAL ($ PER YR.) $1,617,000

128 TABLE 3-33 (B) (CONTINUED) PROCESS COST SHEET PROCESS NAME: Garrett DATA SOURCE: MRI Report, ref. 3-2 CAPACITY IN TONS/DAY: 1814 metric tons (2000 tons) DOLLARS COMMENTS

< CAPITAL COSTS (TOT. $) Land Preprocessing Eqmt Processing Eqmt Postprocessing Eqmt Utilities $21,200,000 Building 6 Roads Site Preparation Engr. & R & D Plant Startup Working Capital Misc.:

TOTAL $21,200,000

OPERATING COSTS ($ PER YR Maint. Material Maint. Labor Dir. Labor Dir. Materials Overhead Utilities Taxes $ 3,342,000 Based on 24 hour per Insurance day and 300 day per Interest year operation. Disposal of Residue Payroll Benefits Fuel Misc . :

" TOTAL $ 3,342,000

CREDITS ASSUMED ($ PER YR) $ 3,342,000. .'''-".'-'• DOLLARS/YR. COMMENT .

Fuel: Liquid . Gas $2,448,000 Solid Power: ', Steam Electricity Hot Water Magnetic Metals 402,000 Nonmagnetic Metals - • Glass 384,000 Ash Paper Other :

TOTAL ($ PER YR.) $3,234,000

129 TABLE 3-33 (C) PROCESS COST SHEET PROCESS NAME: Garrett DATA SOURCE: Mallan & Finney (Ref. 3-51 CAPACITY IN TONS/DAY: 1814 metric tons (2000 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land Land not estimated Preprocessing Eqmt ) Processing Eqmt • ) $14,000,000 Postprocessing Eqmt) Utilities Building & Roads Site Preparation Engr. 6 R 6 D Plant Startup Working Capital Misc.: 400,000

TOTAL $14,400,000

OPERATING COSTS ($ PER YR) Maint. Material ) Maint. Labor ) Dir. Labor ) Dir. Materials ) $ 2,704,780 Overhead ) Utilities ) Taxes ) 'his no. will be Insurance ). $168,000 unless a Interest satisfactory method Disposal of Residue 84,000 of reclaiming non- Payroll Benefits 'errous metal is Fuel developed. Misc.: Auxiliary fuel generated by pyrolysis TOTAL $ 2,788,780 process .

CREDITS ASSUMED (§ PER YR) 4,004,000 DOLLARS/YR. COMMENT

Fuel: Liquid $ 2,450,000 Highly viscous oil- Gas may be some problem Solid 161,000 in finding market. Power: Steam Electricity Hot Water Magnetic Metals 931,000 Nonmagnetic Metals Glass 546,000 Ash Paper Other:

TOTAL ($ PER YR.) $ 4,004,000

130 TABLE 3-34 Assumptions included in the study: COMPOSITION OF DRY PVROLYSIS GAS FROM THE WEST VIRGINIA Plant-life 20 years UNIVERSITY PROCESS Interest rate , 6% . .- Construction period 2 years Credit for refuse. • ;§4.'40/metr'ic ton CO ($4.00/ton) C0 2 3,4.5 SUMMARY OF PYROLYSIS ALTERNATIVES H2

CH4 Because of the relative newness of the field of refuse pyrolysis it is very C2 unsaturates difficult to make definitive statements regarding^the-'desirability of various C2H6 systems. In particular, there is the possibility that some process which is Cj unsaturates now at the conceptual or experimental stage may become,in the-future clearly preferable CjHg to the systems which have presently been demonstrated. On the other hand, some pro- "Total cess which appears to be very promising at the conceptual or experimental stage may Gross heating value 1.65 x 107 J/SCM become technically or economically in- . (443 Btu/SCF) feasible when construction of a commercial plant is attempted. Since at least five Yield of gas per unit of commercial plants for pyrolysis of MMR are £ried refuse 0.58 SCM/kg currently under construction it can be ex- (9.3 SCF/lb) pected that some of the data necessary for informed decision making will become available within the next few years. These shredding is required for the process, five plants,' though, only represent four little expense would be incurred by adding types of processes, whereas Table 3-24, magnetic separation to recover most of for example, contains sixteen -possible the ferrous metals. The desirability (but not.necessarily feasible) combinations of adding units to recover glass and/or of reactor types of heating conditions, aluminum from the heavy fraction resulting with example processes listed for nine of from the air classifier would depend these combinations. Thus, there are many greatly on market prices for the re- types of processes which may be feasible, covered materials. but for which operating data may not be available for. some time. 3.4.4.4.2 Economic Data Anyone faced with making an immediate choice of a pyrolysis- process for some commercial 'application would surely be very Several independent economic evalua- interested in data from successful pilot tions of the-fluidized bed have been made, plant operations. Table 3-23 shows at a but the results of.the Stanford report glance that the largest scale pilot opera- (ref. 3-68) will be the only one presented. tions have been limited ,to two types of The wvy process is only a small experimental processes: vertical'shaft'and rotary setup, and scaling up from laboratory size kiln, both with direct heating. More to a 907 metric -ton/day (1000 ton/day) limited scale pilot plants have demonstrated commercial plant involves considerable vertical and horizontal shafts with in- economic uncertainties. Additional eco- direct heating and a fluidized bed. Ob- nomic data may be found in ref. 3-67. viously the data from the larger scale pilot plants can be extrapolated more re- Cost figures for both the two reactor liably to commercial plant operation. and single reactor systems are summarized in Table 3-35 and represent costs and cre- Aside from the basic problem of pre- dits for construction and operation of a dicting the results of operation of various 907 metric ton/day (1000 ton/day).facility. types of commercial plants, one will be As noted, the single reactor system has a most interest in the relative economics higher initial capital cost, primarily due of the various alternatives. These eco- to pre and post processing equipment. It nomics will depend greatly on the local also produces a lower quality gas, making markets for various fuels and/or reclaimed it less desirable. materials, as well as on the processes considered. ' ?•''

131 TABLE 3-35 (A) ECONOMIC DATA-WEST VIRGINIA UNIVERSITY PROCESS PROCESS COST SHEET PROCESS NAME: Fluidized Bed - West Virginia (2 reactor) DATA SOURCE: Stanford Research Institute Report, ref 3-68 CAPACITY IN TONS/DAY: 907 metric tons (1000 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land $ 100,000 Preprocessing Eqmt . 3,100,000 . ' 1 Processing Eqmt 4,000,000 1 Postprocessing Eqmt 1,600,000 Utilities' 1,400,000 Building & Roads 500,000 Site Preparation Engr. & R & D Plant Startup 500,000 Working Capital 500,000 Misc . :

TOTAL $11,700,000

OPERATING COSTS ($ PER YR) Maint. Material $ 290,000 Maint. Labor ) Dir. Labor ) 990,000 Dir. Materials Overhead Utilities 500,000 Taxes ) Insurance ) 200,000 Interest 960,000 Disposal of Residue Payroll Benefits Fuel Misc.:

TOTAL $ 2,940,000

CREDITS, ASSUMED (S .PERUYR) $ 1,227,648| DOLLARS/YR. COMMENT

Fuel: Based on 320 days. Liquid $0.47/109 joules Gas $1,227,648 ($0.50/106 Btu) , Solid Power: Steam 5.2 x 105 SCM/day Electricity (18.4 x 106 SCF/day) Hp,t Water Magnetic Metals Heating value of Nonmagnetic. Metals 1.55 x 10' joule/SCM Glass . (417 Btu/SCF) Ash Paper Other:

TOTAL ($ PER YR.) $1,227,648

132 TABLE 3-35 (B) PROCESS COST SHEET - -— ..»s.i. VirginiA, a (single reactor) «,,« Research Institute" Report - ref. 3-68 CAPACITY IN TONS/DAY: 907 metric tons (1000 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land $ 100,000 Preprocessing Eqmt 3,100,000 Processing Eqmt ' 3,400,000 Postprocessing Eqmt 3,000,000 •• Utilities 1,400,000 Building & Roads 500,000 Site Preparation Engr. 6 R & D Plant. Startup 500,000 Working Capital . 500,000 Misc.:

TOTAL $12,500,000

OPERATING COSTS ($ PER YR] Maint. Material $ 290,000 Maint. Labor 900,000 Dir. Labor Dir. Materials Overhead Utilities 850,000 Taxes 230,000 Insurance 1,020,000 Interest Disposal of Residue Payroll Benefits Fuel Misc. :

TOTAL $ 3,290,000

CREDITS ASSUMED ($ PER YR) $ 1,790,000 DOLLARS/YR. COMMENT

Fuel: Liquid Gas $ 611,500 Based on 320 days/yr Solid $0.47/109 joules Power: ($0.50/106 Btu) Steam Electricity. 7.73 x 105 SCM/day Hot Water 6 Magnetic Metals (27.3 x 10 SCF/day) Nonmagnetic Metals 6 Glass 5.2 x 10 joule/SCM Ash (140 Btu/SCF) Paper / O.ther:/

TOTAL ($ PER YR.) $ 611,500

133 The fuel product from th'e processes (a) The Union Carbide Purox Process (see that have been tested in the four largest section 3.4.4.1) has the merits of sim- pilot plants (those greater than 31 metric plicity and the disposal of solid waste tons (35 tons) per day) is a low heating without any preprocessing. However, the value gas containing much nitrogen, since equivalent of about one-third of the energy these processes use air for the oxidant recovered by the process is needed to pro- in direct heating. It seems unlikely that duce its oxygen requirement. Thus, from it will ever be economical to transport the standpoint of energy conservation, it this gas any significant distance, but it is less attractive than some other processes, is usable in boilers located near the Moreover, broad acceptance by municipali- source. In the high temperature vertical ties may be doubtful due to the fear of the shaft processes (URDC and Torrax) no pre- hazard from handling pure oxygen. Use of processing is required for the reactor, oxygen at high temperatures also eliminates but it could be added if justified by the potential of recovering some valuable markets for the byproducts. Since some metals in the refuse. preprocessing is required for the rotary kiln processes (Monsanto and Devco), some (b) The Monsanto Lahdgard Process (see byproduct reclamation may be included at section 3.4.4.2) also has the merit of sim- small additional cost. The Union Car- plicity. However, its product is a low bide process is basically similar to the heating value gas 4.48 x 106 joule/SCM other high temperature vertical shaft pro- (120 Btu/SCF) which has limited applica- cesses, but the use of pure oxygen as the bility. oxidant improves the quality of the fuel gas. The quality of the raw Union Carbide (c) The Occidental Petroleum Garrett gas could still not justify transportation Process (see section 3.4.4.3 and ref. 3-84) very far, but it could be upgraded to has the merit of producing a liquid fuel methane by known chemical procedures if along .with some gas with heating value up desired. Also, the very small amount of to 2.61 x 107 joule/SCM (700 Btu/SCF). nitrogen in the Union Carbide gas mini- Its drawbacks are: mizes one of the potential air pollution 1. very fine shredding is needed; problems of the other direct heat processes. 2. large quantities of char are A disadvantage of the Union Carbide process produced; and is the hazard associated with separation 3. the liquid has high viscosity and use of pure oxygen. and acid content. This latter product is a burden rather than Processes using indirect heating'also a credit unless economical uses are found. avoid the problems of nitrogen in the fuel gas (Kemp, Barber-CoIman, Rust, WVU, A.D. (d) West Virginia University Fluid Bed Little). This lack of nitrogen along with Process has the ability.to produce a simple the moderate temperatures used in these product gas of medium heating value 1149- processes give fuel gases with improved 1.87 x 10' joule/SCM (400-500 Btu/SCF) heating value, as well as potential for without the use of pure oxygen. However, methanation. The still lower temperature the capability of moving high density processes concentrate on production of solid components into and out of the reac- liquid fuel (Garrett) or char (Georgia tors is currently lacking. For this reason, Tech). All of these processes require extensive shredding and air classification preprocessing of MMR, so are quite compa- are needed. tible with byproduct reclamation. A pyrolysis process which can circum- Again, it.should be emphasized that vent the drawbacks of other processes and the local markets for various forms of which can be economically operated without fuel and for various byproducts can be adding much financial burden to municipali- expected to be the controlling factors ties is desirable. in economic comparisons. 3.4.6.2 DESCRIPTION OF THE NAAS PROCESS 3,4,6 STUDY OF A PROPOSED YROLYSIS PROCESS After careful consideration of all aspects of the problem, with emphasis on 3.4.6.1 WHY IS ANOTHER PYROLYSIS maximizing energy recovery, a process re- PROCESS NEEDED? ferred to as the NAAS process is discussed in subsequent sections. Figure 3-64 is a schematic of the NAAS process. • With many pyrolysis techniques available, why should we search for more? The The principal equipment of the process reason is that all pyrolysis processes in consists of two rotary kilns, one serving advanced stages of development have some as a pyrolyzer and the other as a combustor. drawbacks along with their merits. For A continuous stream of dolomite circulates example: between them. The combustor is situated

134 STEAM

REFUSE

DRYER ±r-jJ I •• I SCREW CONVEYOR SUPERHEATED STEAM

-»• GAS FLOW ^ SOLID OR LIQUID FLOW Ms- METALLIC ALUMINUM FIGURE 3-64 THE FLOW SHEET OF THE NAAS PROCESS

above the pyrolyzer and the dolomite moves by a screw conveyor where meets with hot from the former to the latter by means of dolomite ~ at about 980°C (180°F) — gravity and screw conveyors. The circu- coming from the combustor. The direct lation Is completed by using a bucket contact between dolomite and organics pro- elevator to return the dolomite to the duces a gas containing about 15 percent CQ^ cpmbustor. 27 percent CO,'42 percent K^t & percent CH4, and 8 percent higher hydrocarbons. Two separators are inserted in the After pyrolysis, the residue char and car- loop. One separates slag and fly ash from bon from the coal react with steam vapor the burned dolomite, the other classifies to form water gas. The reaction heat is metallic aluminum from a mixture of dolo- supplied by the heat generated by absorp- mite and char. tion of C02 by dolomite. The metallic aluminum is now in molten form and is se- The front-end preparation installa- parated from dolomite and char by a spe- tion consists of one shredder- and one cially-designed separator. The remaining magnetic separator. The gas purifica- solid mixture is cooled down by using it tion systems are conventional. The screw to preheat low-pressure steam in a drum- conveyors also serve as seals to keep flue type preheater. The solid mixture now is gas separated from pyrolysis gas. at about 372°C (700°F) and is moved into a bucket elevator which carries the dolomite After nugh shredding to 3 to 10 centi- and char mixture into the entrance of a meters (1 to 4 inches) the Municipal Solid combustor, where the char is completely Waste (MSW) passes through a magnetic burned by a preheated air stream. separator where ferrous metals are removed. The organics and the remaining inorganics The heat contents of flue gas and are mixed with some low-grade pulverized product gas leaving the dryers are recover- coal by a screw conveyor. If the refuse ed by a waste heat boiler where low-pres- contains very much moisture, two dryers sure steam is generated to satisfy the will be needed. One dryer is heated by need of the :water-gas reaction. flue gas and the other by pyrolysis gas. The dried MSW is fed into the pyrolyzer The heat contents of flue gas and pro-

135 duct gas leaving the dryers are recovered pressures of all three gases are negligible by a waste heat boiler where low-pressure when they are in contact with metallic steam is generated to satisfy the need of aluminum. Therefore, the feasibility of the water-gas reaction. aluminum' recovery depends on the rate of reaction. According to Van Horn (ref. 3-85) The pyrolysis gas is further cooled the rate of oxidation of aluminum is about down and purified in a Venturi scrubber 0.16 grams per square meter per hour at and the flue gas is scrubbed by mono- 760°C (1400°F). Moreover, with the addition ethanol amine for C02 purification. of traces (0.001 percent) of beryllium, . the oxidation can be totally stopped (ref. The heat of combustion is transferred 3-86). Therefore, it is highly probable into the pyrolyzer in the forms of the . that the major part of the metallic alumi- sensible heat of dolomite and the heat of num in the MSW can be recovered. Whether decomposition of CaC03 to CaO and C02. The /the addition' of this amount of beryllium dolomite, free from char, is fed into a will affect the usage of aluminum for making specially-designed separator where.slag and • cans or other food containers should be fly ash are separated from the dolomite studied. stream-., without taking it from the processing system. The separating medium is cold air. The preheated air from the separator is fed 3.4.6.5 ECONOMICS OF THE NAAS PROCESS into a combustor or after burner. The main air is preheated by a preheater or by a two-rotary-tunnel system with the cir- A hypothetical NAAS plant to handle culation of sands between them. A conven- 1,134 metric tons (1,250 tons) per day of tional tubular heat exchanger can also be raw (wet) MSW has been designed and the used. individual equipment sized. Equipment prices were estimated or obtained by telephone calls to manufacturers. The economic 3.4.6.3 CONTROL OF OPERATION AND MAINTENANCE analyses, with assumptions given, for five operating conditions are shown in Table 3- 36. The encouraging economics shown in this The entire NAAS plant should be con- table are due to the following: trolled by digital mini-computers in order to cope with the fluctuating nature of MSW 1. The quantity of salable gas is feed rate and to minimize the need for increased because of the gasifi- municipalities to employ high caliber tech- cation of the char produced to- nical personnel. • gether with the carbon in the coal fed into the system. All moving parts except blowers and water pumps are driven by D.C. current. The 2. About 80 percent of the metallic speeds of all D.C. motors are interrelated aluminum present is recovered, to each other such that the overall process- which contributes to a considering rate is kept uniform with the MSW feed able reduction of net operating rate to achieve complete, gasifications and costs. combustion. The processing rate can be varied from zero (if repairs are being made) 3. Utility usage is low. up to maximum production capacity. The gas and air blowers are controlled by by- passing a part of the flows. 3.4.6.6 AN EXPECTED TECHNICAL PROBLEM AND A POSSIBLE SOLUTION 3.4.6.C4 POSSIBILITY OF ALUMINUM RECOVERY Entrainment of dolomite in the outgoing gas and solids streams is a possibility. Metallic aluminum is the second most The gas velocities of flue gas from the valuable resource in MSW. If it can be combustor and the product gas from the recovered with no additional cost or energy pyrolyzer are in the ranges of 0.8 to 1.1 consumption, about 95% of the energy expend- meter/second (2.5 to 3.5 feet/second). ed in producing virgin aluminum can be re- The gas streams will carry some dolomite covered indirectly. with them, but when the gases are cooled in the dryers the velocities are reduced In the NAAS process metallic aluminum to about 0.3 meter/second (1 foot/second). is melted in the pyrolyzer where a reducing Some of the entrained dolomite will drop atmosphere is maintained. However, ques- out at the lower velocity. Dolomite collect- tions arise as to whether metallic aluminum ed in the dryers is fed back to the pyroly- •at about 660°C (1220°F) can be oxidized by zer by screw conveyors. The entrained CO, C02, and water vapor. Thermodynamic dolomite is further collected in the multi- calculations show that at 'room temperature cyclones. Some very fine sized dolomite and 760°C (1400°F) the equilibrium partial will be carried through the waste heat

136 TABLE 3-36 ECONOMIC ANALYSIS OF THE NAAS PROCESS

A. DESIGNED CAPACITY: 1134 METRIC TON/DAY (1250 TON/DAY) B. TOTAL INVESTMENT: $12,467,500 (BASED ON M & S INDEX OF 360) C. ANNUAL GROSS PROFIT ASSUMPTIONS MADE:

PRODUCT GAS AT 50.71/109 joules ($0.75/million Btu) ALUMINUM AT $331/METRIC TON. ($300/TON) PRICE OF 98% PURE O>2 $8.82/METRIC TON ($8/TON) CAPITAL COST AT 10% INTEREST RATE AND 20 YEARS LIFE BREAKEVEN ON HANDLING OTHER PRODUCTS

Gross Cost $/dry Operating Condition (Profit) metric ton $/dry ton 1. 100% capacity without C02 sale ($ 321,000) +$1.00 +$0.90 2. 75% capacity without CO2 sale $ 528,900 -$1.76 -$1.60 3. 50% capacity without C02 sale $1,335,300 -$4.47 -$4.05

4. 100% capacity with C02 sale ($1,256,680) +$4.20 +$3.81 5. 50% capacity with C02 sale $ 864,760 -$2.88 -$2.61

boiler and air preheater and will be collect- gas with consequent improvement ed in the scrubbers from which it can be re- of process economics. This re- "•. covered periodically. suits from using the heat of - , absorption of C02 from the pyroly- If the dolomite carried out by slag sis gas by the dolomite to promote and fly ash because of incomplete separation gasification of residue char and is higher than can be endured economically, carbonized low-grade coal. The it should be recovered by a hydraulic classi- heat content of low-grade coal is fier. thus converted to valuable clean energy. 3.4.6.7 MAIN FEATURES OF THE NAAS PROCESS 4. Capital investment will not be excessive. No expensive air pollution control equipment is re- Assuming that the potential mechanical quired. problems of the proposed process such as leakage from rotary kilns, movement of 5. Flue gas from the NAAS process solids at elevated temperatures, and mini- will be sulfur-free, with very mization of dolomite loss are solved, the low sulfur content. This is be- NAAS process would be expected to do the cause dolomite is a powerful sul- following: fur removal agent. If recovered, sulfur may be sold to lower the 1. Recover metallic aluminum without net operating cost of the process. extensive shredding and power con s umpt ion. 3.4.6.8 POLITICAL, ENVIRONMENTAL, LEGAL, 2. Produce a gas with a relatively AND SOCIAL IMPLICATIONS OF THE high heating value — about 1.85 x NAAS PROCESS 10' joule/SCM (500 Btu/SCF) — which can be used'as a fuel for a power plant or a gas turbine. When laws and regulations which pro- This comes about because of separa- vide incentives for recycling resources, tion of combustion and pyrolysis such as equal treatment on transportation and lowering the CO2 content by rates for recycled and virgin materials, absorption with dolomite. are established, there would be moe potential markets for ferrous and nonferrous 3. Increase the quantity of product metals recovered from the NAAS process.

137 These materials would then have higher anaerobic degradation processes, degrada- 'prices. tion takes place in an oxygen deficient environment. Biochemical conversion processes If all byproducts can be sold, which accomplish either refuse reduction -or con- is a possibility, there would be no need version of cellulose and in many applica-: for landfill. If there is no market for tions both aspects are utilized. some of the products, they could be landfilled, without causing any land pollution Having defined biodegradation and list- problems. Air pollution would be minimal ed the major biological conditions under because both product gas and flue gas are which this type of refuse reduction occurs, scrubbed with water, removing particuiate the question of perspective and applicabi- matter. lity must also be considered. The use of a rotary kiln as a combust- Biodegradation has been the normal or permits good control of temperature mechanism for the removal of the solid with no local overheating expected. . There- wastes produced by living organisms-' since fore, the NOX content of the flue gas . the beginning of the biosphere. During all should meet EPA regulations as do most but the smallest segment of man's evolution, other pyrolysis processes.. he has been born, lived, died, and was buried among the waste products of his No difficulty with water pollution is society. In hunting societies, the wastes expected because the scrubbing water is are simply discarded at the point of origin. .recycled and its salt content is recovered. In agricultural societies, they are placed The NAAS process involves no danger with in the adjacent fields. In man's early hazardous materials and good acceptance cities, he did essentially the same thing, by municipalities is expected if the pro- producing the city mounds found in the cess is available. Middle-East. This method was used throughout the middle ages in Europe. It. was only with the advent of paved streets in 3.4.6.9 DECISION MAKING FOR CITY OFFICIALS Europe that there was some fixed surface IN RELATION TO THE NAAS PROCESS to clean down to. The banishing of swine from the city streets at about the same time removed the scavengers which consumed If a city is in urgent need of solving the waste. Thus street sweepers and refuse a solid-waste disposal problem, it should collectors started at about the same time. not consider the NAAS process because this is, at present, only a conceptual design; Along with the industrial' age came a no experimental verification has been done. change in the composition of the refuse. Previously, because of cost and economic For long range planning, however, the level, the refuse was mainly garbage, offal, NAAS process should be considered along and manure. With increasing technology, with other alternatives, because it does cellulose in the form of paper and clothing appear to have merits not possessed by.some began to appear in the refuse. With in- of the other pyrolysis processes. creasing industrialization, glass and finally metal also appeared in appreciable amounts,, along with increasing amounts of 3.5 BIODEGRADATION PROCESSES cellulose. These later changes have been mainly within the twentieth century. How- ever, man still views MMR as the type of . 3.5,1 INTRODUCTION refuse found in a pre-industrial world which means that biodegradation is usually the Among the possible processes available process that comes to mind as the best methoi for the reduction and/or conversion of MMR of solid waste disposal. (mixed municipal refuse) are those which fall under the general heading of biodegra- • Biodegradation is the process that pro- dation. Biodegradation can be defined as duces the least negative impact on the -bio- the reduction of refuse'by the use of sphere. However, MMR with its present-com- organic methods. The organic methods are position and daily production, puts definite divided into two general categories. The limitations on the regions where biological first is the direct reduction of the processes can be used to convert solid refuse by biological organisms which in- waste into energy. The limiting aspects of cludes aerobic and anaerobic conversion. different biodegradation processes as well The second is the reduction of the as the advantages will become more explicit refuse by biochemical methods. This •as the different categories of biological second is the reduction of the refuse by reduction are discussed. biochemical methods. This includes chemical preprocessing, and/or the use of enzymes. These enzymes are either "the metabolic waste 3.5.2 COMPOSTING products or the selected extractions from specific species of protozoa or fungi. In

138. The earliest methods of organic solid require a constant high moisture environ- waste conversion were in .the general cate- ment generally between 50 and 70 percent, gory of rotting. Where the conditions were without submersion. If the water percent- proper, this decay would produce a humus age is too great, there will be insufficient as an end product. This process is known air in the spaces between pieces of the as composting and is a biological degra- refuse. Under these condition's, the aerobic dation of organic materials. Since this microorganisms will either die or trans- report is considering energy recovery from form themselves into a dormant state in MMR, the emphasis in this chapter will be order to survive the lack of oxygen. Also, on the composting of residential and in- if the moisture levels are too large, dustrial waste found in MMR. It might be nutrients are lost in the leachate and noted that properly designed, built, and anaerobic microorganisms will begin to managed composting systems will also replace the aerobic microorganisms. The process raw or partially digested sewage degree of replacement accelerates with in- sludge into pathologically safe humus creasing moisture content. On the other -. products. hand, if the compost becomes too dry, the decomposition process will first slow down Let us now consider the small compost with increasing dryness and at some mois- pile in some detail. The most important ture percentage cease completely. Other aspect for the success of any composting factors important to the rate of decomposi- system is the proper decomposition of the tion are ambient climatic conditions, size organic waste which is induced by numerous of compost pile and composition of refuse. microorganisms. These include various The climatic effects are inversely propor- types of bacteria, fungi, actinomycetes, tional to the size and mass of the compost- and protozoa. The small compost pile, ing volume and the amount of protection where the surroundings are in a normal eco- provided. logical state, will have animals that speed up the physical decay. Examples of these The question of the need for inoculums small invertebrates are mites, millipedes, to start the composting process has been insects, and earthworms. In larger commer- debated for many years. Folk wisdom and cial processes, these minute pests will earlier work implied that the use of a usually be missing since the volume of the starter would accelerate the process and compost is large compared to its interface produce better humus. Typical inoculums surface with an ecologically balanced were animal manure, special bacteria cul- • surrounding environment. tures, or soil. Golueke, Card, and Mc'Gauhey (ref. 3-88) conducted a critical evaluation The compost pile is exactly what its of the effects of inoculum use in the name implies. It can be placed in a heap, composting process. Using the typical a pit, or any other shape. The optimum inoculums, the research showed that for pile dimensions are 0.91 meters (3 feet) identical composting systems, the commence- to 1.52 meters (5 feet) high and may vary ment time for active degradation, tempera- from 0.91 meters (3 feet) to 3.04 meters ture rise times and stability, and required (10 feet) wide. These piles may be any time to produce humus was essentially length desired. When the length is greater identical for all inoculated and control than the width, the compost pile is called systems. a windrow. The organic fraction of the -MMR or the waste is the.major energy source Two major conclusions can be drawn consumed by the decomposer organisms. The from this research. One, the time needed organic materials most easily composted to compost MMR is independent of bacterial • include: garbage, leaves, grass clippings, enrichment. Thus, no injections of micro- sawdust, manure, organic meal, dried blood, organisms are required. Two, by use of and organic sludge. It should be noted, other materials in MMR, either during com- Zanoni (ref. 3-87) that these constitute posting or afterwards, the composition and the majority of rubbish and food waste fertilization values of. the humus can be components in typical MMR. Generally a varied within certain limits. These two pH range from 6-to 8 is required for optimum conclusions taken together imply that one microbial decomposition rates and humus can combine MMR with other organic wastes quality, especailly for aerobic composting. and still produce pathologically acceptable An anaerobic composting sys'tem is also humus or compost. The types of organic possible but the pH values are slightly waste that can be added to MMR include lower (higher.acidity). Anaerobic decom- animal manure, offal, sewage sludge, and position as a process will not be discussed industrial grade biological wastes. with respect to specific composting systems but will be discussed in the section on When the aerobic decomposition processes methane production. begin to occur,, the microorganisms release fairly large amounts of energy in the form Since the decomposer organisms are of heat. Because of the insulative pro- microorganisms, the moisture requirements perties of the MMR or refuse, the volume of are fairly stringent. These microorganisms the composting material begins to warm

139 up. Very little heat is lost from the com- must be balanced in some manner in order to post pile by either convection or conduction, maximize the tons/day processed and accel- ' the major heat losses, except at the surface, erate decomposition time. The proper bal- are by radiation. This rise in temperature ande of quantity and quality will determine means that the composting process is pro- the total volume of composting material gressing properly. The temperature rise which must be involved in the decomposi- also provides empirical evidence that the tion process from start to finish, i.e., carbon to nitroge.n ratio is within the pro- from MMR input to humus output. per range of values and signifies the rapid growth and multiplication of the microorganism population. 3.5.2.1 COMPOSTING PROCESSES In some specialized composting systems-,- the temperature rise takes less than 24 In order to discuss some of the com- hours, but 48 hours would be more typical. posting processes, the basic characteristics As the temperature rises to 45°C (112°F) of the input material must be discussed the population levels of thermophilic first. Namely, what is the composition of microorganisms rise rapidly. These thermo- the feed, here MMR, which is uniquely pert- philic, or heat loving microorganisms, inent to biological methods? This will be multiply rapidly while the mesophilic forms followed by a discussion of the basic com- die off. The thermophilic bacteria, fungi, posting processes. Third, an economic and actinomycetes thus become the major analysis of certain specific United States decomposer organisms. In a temperature based composting operations will be con- range of 45°C (112°F) to 65eC (150-F), the sidered. The closing section will discuss population of thermophilic microorganisms the specific problems of composting and may be more than 10" microorganisms per suggestions for further study. kilogram of the organic fraction of the refuse. Since the temperature pattern is Solid Waste and Preprocessing essentially the measure of the efficiency of the aerobic thermophilic decomposer Before considering any biodegradation organisms, it is used to determine the state process as the possible solution for a of the decomposition process. waste product, the composition of this waste product must be analyzed. The or- If the composting material is raised ganic composition analysis must consider to 65eC (150»P) and held there for a suf- both the quantity and quality of the MMR'.. " ficient length of time, the germs and Not only must there be a significant per- parasitic microbes will be destroyed. The centage of organic material in the MMR, but obvious problem is that the surface of the nutritional value which includes carbo- the compost will have the temperature of hydrates, fats, and proteins must be ade- the ambient surroundings. Since the temp- quate. Also, if the carbon to nitrogen erature profile must be continuous in the ratio is not within the proper range of compost, there will be material in the values, the rate of biological decomposi- surface region which will not reach 65°C tion will be reduced. (150°F) in a static compost process. Thus, one must redistribute the material, placing ' An analysis of published MMR composi- the outer surface layer in the center. tion, previously tabulated in Table 3-3 -' and many other references is not the total' The composting process is complete and refuse story. The percentage of specific the resulting compost or humus material is components vary not only with geographic ready for use when the temperature within location, but also with season and economic the pile returns to the ambient value. level. As Wiley and Kochtitzky note (ref. When this happens, the humus will have 3-89) the increases in the per capita three main characteristics. One, it will volume of MMR produced are much greater be finely divided and crumbly if the in- than the increase in weight, which means put refuse was ground. Two, it will be that the MMR is becoming more bulky and dark in color. Three, the carbon to less dense. The greatest increase in MMR nitrogen ratio will range from a low value production has been in the area of low of 10 to 1 to a high value of 20 to 1. density organic combustibles. The increase is primarily in the form of paper and This section has discussed the com- plastics. This increase is coupled with posting process with respect to an already a reduction in. the.volume of garbage and existing prototype,operation which is known trash. In other words the calorific as the compost pile. When commercial com- value of MMR has increased continually, posting operations are considered, the but this has been coupled with a decrease biophysics of the organic microorganism in the nutrient content. The decreasing part of the individual process will always microorganistic nutritional value has two be the same as the simple compost pile. distinct effects on the composting pro- The mechanical systems will serve only two cess . One, the composting operation will purposes - one to speed up the process and take longer to complete with respect to two, to improve the quality of the resulting breaking down the cellulose. And two, product. Obviously, these two purposes the humus produced will be of lower quality.

140 The quality of the compost produced Breidenbach (ref. 3-90). Each system depends directly on the amount of prepro- consists of a preprocessing and/or post- cessing and/or post processing done to the processing system coupled with a digester. MMR. The attempted composting of raw MMR The digester may consist of. either windrows, would lead to a product which could be pits, trenches, cells, tanks, multistoried called semi-rotted refuse. The obvious or multidecked towers or buildings, drums, problems due to constituents such as bulk, or bins. Some processes combine more than non-organics, and containers would lead to one of these digester types. The usual an incomplete decomposition. Thus the MMR combination is a special digester combined needs to be shredded first for uniform and with storage area for curing which usually reproducible composting. takes place in either a windrow or bin. The basic differences between the 16 typi- The ideal preprocessing system for cal processes are given in Table 3-37. composting would remove all glass, ferrous Rather than discussing each process sepa* metal, aluminum, non-ferrous metal, rately, the basic characteristics of all plastics, leather, and rubber. Even though municipal composting systems will be con- the plastics, leather, and rubber are tech- sidered. The operation of a modern com- nically organic, they effectively resist posting plant can be broken down into five degradation long enough to insure they will sequential steps. These steps are: pre- come through the composting process time paration, digestion, curing, finishing or with little disintegration. The remaining upgrading, and storing. material should be shredded so that it passes through a 2.54 centimeter (1 inch) The preparation or preprocessing con- mesh screen. sists of receiving, sorting, separation, grinding, and adding sewage sludge. The In actual fact, the shredded MMR will actual aspects, the possible ordering of contain at least plastics, leather, and the preprocessing and the types of equipment rubber. Also the shredded and separated used are discussed elsewhere in this report. MMR usually will still contain small a- Here we will only state the required size, mounts of metal and glass. The amount of moisture, .and carbon to nitrogen ratio the metal and glass remaining is inversely which, in general, the organic fraction of proportional to the fineness of shredding the MMR should have when it enters the and the complexity or completeness of the digestion stage. separation system. Most shredding processes produce enough heat to dry the MMR. Since the moisture content of ground But, since the composting process requires refuse must be maintained within a specific a moisture level of 50 to 70 percent, the range for proper digestion, raw or digested wet separation techniques can be used on sewage can be added to provide the extra MMR being prepared for biological decompo- moisture. However, the incoming refuse sition. Because of the fact that some per- has different moisture values•depending upon centage of the non-decomposable materials, seasonal variations in composition and such as plastic, remain in the preprocessed daily weather conditions. This means that MMR, the optimum shredding size is reduced. with respect to moisture content, the In fact the larger the percentage of amount of sewage sludge added will vary plastic, glass, and metal the separation from day to day. Figure 3-65 shows what system passes through, the smaller the shredding size should be. The quality of the humus produced by 100 composting is inversely proportional to si Refuia-iludge exceedi 60% the quantity of plastics, rubber, and 5 moUturo (wet weight ) leather included. Humus with appreciable UJ 95 amounts of any of these undesirable products has fewer uses and thus smaller markets. J* ini Refute-iludge le» thon 60% 6 < molitur* ( wet weight ) -J O 90 3.5.2.2 REVIEW OP THE MAJOR COMPOSTING PROCESSES

A complete survey of the different composting processes used in the various countries of the world indicate there are BO ( ref. 5-90) approximately 30 composting systems which are identified by either the names of the 10 30 50 inventors or by some proprietary name. ZO PERCENT MOISTURE CONTENT OF INCOMING Table 3-37 lists the more typical REFUSE (WET WEIGHT) composting processes. The 16 processes FIGURE 3-55 listed in the table cover the major charac- VARIATION IN REFUSE/SLUDGE teristics of all 30 processes, and are from MOISTURE CONTENT

141 TABLE 3-37 TYPICAL COMPOSTING PROCESSES

Process Name General Description Location

1. Bangalore (Indore) Trench in ground, .6m to 1m (2 to 3 Common in India ft.) deep. Material placed in alternate layers of refuse, night soil, earth, straw, etc. No grinding. Turned by hand as often as possible. Detention time of 120 to 180 days. 2. Caspari (briguetting) Ground material is compressed into Schweinfurt, Germany blocks and stacked for 30 to 40 days. Aeration by natural diffusion and air flow through stacks. Curing follows initial composting. Blocks are later ground. 3. Dano Biostabilizer Rotating drum, slightly inclined Predominately in from the horizontal, 2.7m to 3.7m Europe (9 ft. to 12 ft.) in diameter, up to 45.7m (150 ft.) long. One to 5 days digestion followed by win?* drowing. No grinding. Forced aeration into drum. 4. Earp-Thomas Silo type with 8 decks stacked Heidelberq, Germany; vertically. Ground refuse is Turgi, Switzerland; moved downward from deck to deck Verona and Palermo, by ploughs. Air passes upward Italy; Thessaloniki, through the silo. Uses a patented Greece inoculum. Digestion (2 to 3 days) followed by windrowing. 5. Fairfield-Hardy Circular tank. Vertical screws,' Altoona, Pennsylvania, mounted on two rotating radial and San Juan, Puerto arms, keep ground material agitated. Rico Forced aeration through tank bottom and holes in screws. Detention time of 5 days. 6. Fermascreen Hexagonal drum, three sides of which Epsom, England are screens. Refuse is ground. Batch loaded. Screens are sealed for initial composting. Aeration occurs when drum is rotated with screens open. Detention time of 4 days. 7. Frazer-Eweson Ground refuse placed in vertical bin None in operation having 4 or 5 perforated decks and special arms to force composting material through perforations. Air is forced through bin. Detention time of 4 to 5 days. 8. Jersey (also known Structure with 6 floors, each equip- Jersey, Channel Islands, as the John Thompson ped to dump ground refuse onto the Great Britain, and system) next lower floor. Aeration effected Bangkok, Thailand by dropping from floor to floor. Dentention time of 6 days. 9. Metrowaste Open tanks, 6m (20ft) wide, 3m (10 Houston, Texas and ft) deep, 61m (200ft) to 122m (400 Gainesville, Florida ft)-long. Refuse ground. Equipped to give one or two turnings.during digestion period (7days). Air is forced through perforations in bottom of tank. 142 TABLE 3-37 (CONTINUED)

Process Name General Description Location

10. Naturizer or Five 2.7m (9 ft) wide steel conveyor St. Petersburg, International belts arranged to pass material from Florida belt to belt. Each belt is an insulated cell. Air passes upward through digester. Detention time of 5 days. 11. Riker Four-story bins with clam-shell None in operation" floors. Ground refuse is dropped from floor.to floor. Forced air aeration. Detention time of 20 to 28 days. 12. T. A. Crane Two cells consisting of three Kobe, Japan horizontal decks. Horizontal ribbon screws extending the length of each deck recirculate ground refuse from deck to deck. Air is introduced in bottom of cells. Composting followed by curing in a bin. 13.® Tollemache Similar to the Metrowaste digesters. Spain; Southern. Rhodesia 14. Triga Towers or silos called "Hygienisa- Dinard, Plaisir, and tors". In sets of 4 towers. Re- Versailles, France; fuse is ground. Forced air Moscow, U.S.S.R.; aeration. Detention time of 4 Buenos Aires, days. Argentina 15. Windrowing (Normal, Open windrows, with a "haystack" Mobile, Alabama; aerobic process). cross-section. Refuse is ground. Boulder, Colorado; Aeration by turning windrows. Johnson City, Tennes- Detention time depends upon num- see; Europe; Israel; ber of turnings and other factors. and elsewhere 16. van Maanen process Unground refuse in open piles, 120 Wijster and Mierlo, to 180 days. Turned once by grab the Netherlands crane for aeration. SOURCE:Breidenbach, ref. 3-90. happens when MMR is not uniform with carried out either in open windrows or respect to water content. The figure shows enclosures. In most modern composting the percent of moisture allowable in the plants, the aerobic process is used sludge for the same population base for rather than the anaerobic. There are both MMR and sewage production. Let us three major reasons for this: time of consider another aspect of the sewage process, temperature, and order problems. sludge problem. If the sludge is not de- The aerobic decomposition microorganisms watered, and one wants to maintain a 60 require free oxygen to decompose the percent water content in the sewage sludge waste. The speed of decomposition is and refuse mixture, then all the sewage oxygen dependent. Too little oxygen and sludge produced will not be usable for com- the process may either slow down or go posting. The quantitative aspects of this anaerobic. Thus, in the forced digestion analysis are shown in Figure 3-66. The systems, oxygen must be introduced by forced only solution to this dilema is to either draft or agitation. Windrow systems get have a complete separate sewage treatment oxygen by turning. The forced digestion plant or provide facilities for partially system reduces the windrow composting time dewatering the sewage sludge. of approximately six weeks to around five to seven days. In the aerobic systems, the The second stage of the process is the temperature reaches 60°C (140°F) to 70°C digestion or decomposition phase. This is (160°F) or higher. This level of heat in

143 problems in the windrow method are from 100 either cooler outer regions or pockets of the windrow where the oxygen has been exhausted and anaerobic decomposition is talcing place. U CO With all the variables, proper mois- ? < ture, particle size, and sufficient oxygen 96 being maintained at constant proper values, O I- the time required for digestion will depend 2 X on the initial carbon to nitrogen ratio. o This is most critical for the processes I- uj 94 which use a short active decomposition time. Figure 3-68 shows the length of time 92 needed for composting as a function of the initial C/N ratio. The dotted line serves

90 8 1.0

POPULATION GENERATING SLUDGE RATIO : POPULATION GENERATING REFUSE FIGURE 3-66 USABLE SEWAGE SLUDGE AS A FUNCTION OF MOISTURE the processing and finishing (Figure 3-67, from ref. 3-90) destroys the pathogenic organisms, weed seeds, fly ova, etc.

(REF 3-90)

II I I I I I I I I I I I I I I I I I I I I 5 10 15 20 NUMBER OF DAYS REQUIRED FOR COMPOSTING

FIGURE 3-68 rRANGE OF TEMPERATURES IN ENCLOSED DIGESTER(GAINESVILLE) COMPOSTING TIME VS AVERAGE INITIAL C/N RATIO — -EMPERATURES IN COMPOSTING - IN WINDROWS (JOHNSON CITY) only to show the trend. Studies have shown that under optimum conditions, with an initial C/N ratio of 30 to 35, active decomposition processes produce humus in 2 to 5 days. The high C/N ratios are due -RANGE OF TEMPERATURES IN WINDROW to the large amounts of carbon in MMR DURING CURING AFTER REMOVAL FROM DIGESTER (GAINESVILLE) which are not readily available since they are in the form of cellulose and lignin. Reference 3-91 contains additional information on C/N ratios and the effects on 345 AGE IN WEEKS anerobic decomposition.

FIGURE 3-67 The pH of MMR turns out to be unimport- TYPICAL AND COMPARATIVE ant as an actual process control. However, TEMPERATURE PROFILES OBTAINED FROM the pH values are good indicators of the COMPOSTING MUNICIPAL REFUSE process parameters and the type of decomposition microorganisms present. To illustrate this, let us consider a specific This should be compared with the anaerobic example, namely the Johnson City windrow system, where temperatures are only about process. The pH vs compost age curve for 38°C (100°F) to 55eC (130°F) which means the Johnson City windrow process is shown pathogens may survive. Also anaerobic in Figure 3-69. The initial pH of refuse decomposition produces foul odors. In at Johnson City is usually between 5 and 7. aerobic decomposition, decomposition pro- Since the refuse is, on the average, at gresses rapidly without excessively un- least three days old when it arrives at pleasant odors. The major odor and pest the plant, the initial pH drops. This is 144 decomposer or digestion stage. The previous discussion of the general composting process is applicable to all the aerobic composting processes listed in 9.0 Table 3-37. However, even'though the process seems fairly simple and straightfor- ward, the history of composting in the 8.0 United States has been anything but a success. A number of municipalities that have tried the composting method of energy 7.0 and resource recovery are listed in Table 3-39. It is immediately noted that all but two of the MMR composting plants in 6.0 the United States are closed. It would seem that there is obviously something wrong with composting as practiced in this 5.0 country, even though composting offers some advantages where it is used to solve specific problems or fit certain circum- stances. AGE IN WEEKS FIGURE 3-69 The Fairfield-Hardy composting pro- PH VS. COMPOST AGE CURVE FOR cess is used in Altoona, Pennsylvania, JOHNSON CITY WINDROW PROCESS and it is the longest continuously operating composting plant in the United States. The economics of this plant and process because of the conditions under which the are fairly representative for all acceler- MMR is stored before collection. Garbage ated decomposition systems and will be containers and piles are fairly air tight, discussed in detail in the next section. thus acid forming anaerobic decay has started. , The first step of this process is for the acid producing microorganisms 3.5.2.3 FAIRFIELD-HARDY to turn the material acidic. If the systems went completely acid anaerobic, the pH could drop to around 4.5. At the end The Fairfield Engineering Company de- of one or two days when the aerobic micro- veloped and applied the Fairfield-Hardy organisms have taken over the decomposition composting system to the refuse problem process, the pH goes up to 8 and stays at of Altoona, Pennsylvania. This plant, this value throughout the composting pro- which has been operating for many years, cess. processes approximately 23 metric tons (25 tons) of separated refuse per day with The time of curing depends on how a maximum capacity of 41 metric ton/day the humus is to be used. At the end of (45 ton/day). The waste material processed the curing process'the temperature has by the plant includes a portion of the dropped to the ambient level and the mois- garbage collected by the city. Altoona is ture level has fallen by evaporative drying. unique in the fact that it still has se- Thus curing depends on three things: the parate garbage and refuse collection. It state of the compost on leaving the diges- should be noted that a mechanical compost- ter or decomposer state; the method used; ing plant for a city with a population of and the final use for the humus. 200,000 would require 3.24 x 104 - 4.05 x 104 square meters (8-10 acres) while a Finishing of the humus depends upon comparable windrow plant would require at the process used to produce it and the least 2.42 x 105 square meters (60 acres). ultimate use of the compost. Thus finishing can consist of screening to remove Figure 3-70 shows a schematic of the glass, metal, or plastic; grinding to Altoona plant. Since garbage and rubbish reduce size, pelletizing or blending; and/ are collected separately, no initial hand or enrichment. sorting is required. This means that the delivered separated MMR is fed directly An example of the elemental composi- into a Williams hammermill. After this tion of finished humus is given in Table initial grinding, secondary grinding is 3-38. This particular table is for 42 day performed in a hydropulper. Sewage sludge old compost from the Johnson City windrow- solids are added to the hydropulper to ing process. Cured compost from any of enrich the MMR and to increase the water the aerobic processes would have comparable content for the decomposer in micro- percentages. The important fact to note organisms. After the hydropulper, the is the insignificant change in the final now slurried ground refuse passes through composition of the compost due to the a bar screen which is used to remove metal addition of sewage sludge before the cans, plastics and other non-decomposable

145 TABLE 3-38 ELEMENTS IN 42-DAY-OLD COMPOST AT JOHNSON CITY

Percent dry weight (average) Containing sludge Range Element Without sludge (all samples)

Carbon 33.07 32.89 26.23 - 37.53 Nitrogen 0.94 0.91 0.85 - 1.07 Potassium 0.28 0.33 0.25 - 0.40 Sodium 0.42 0.41 0.36 - 0.51 Calcium 1.41 1.91 0.75 - 3.11 Phosphorus 0.28 0.22 0.20 - 0.34 Magnesium 1.56 1.92 0.83 - 2.52 Iron 1.07 1.10 0.55 - 1.68 Aluminum 1.19 1.15 ,0.32 - 2.67 Copper < 0.05- < 0.03 Manganese < 0.05 < 0.05 Nickel < 0.01 < 0.01 Zinc < 0.005 < 0.005 Boron < 0.0005 < 0.0005 Mercury not detected not detected Lead not detected not detected *Ref. 3-90.

TABLE 3-39 /nnw MUNICIPAL SOLID WASTE COMPOSTING PLANTS IN THE UNITED STATES (1973)

Capacity metric Capacity Type Began Location Company Process ton /day ton/day Waste operating Status

Altoona, Altoona FAM, Inc. Fairfield- 41 45 Garbage , 1951 Operating Pennsylvania Hardy paper

Boulder, Harry Gorby Windrow 91 100 Mixed 1965 Closed (1971) Colorado refuse

Gainesville, Gainesville Municipal Metrowaste 136 150 Mixed re- 1968 Closed (1971) Florida Waste Conversion Conversion fuse, di- Authority gested sludge

Houston, Texas Metropolitan Waste Metrowaste 327 360 Mixed re- 1966 Closed (1970) Conversion Corp. Conversion fuse, raw sludge

Houston, Texas United Compost Snell 272 300 Mixed re- 1966 Closed (1966) Services, Inc. fuse

Johnson City, Joint USPHS-TVA Windrow •' 47 52 Mixed re- 1967 Closed (1970) Tennessee fuse , raw sludge

Largo, Florida Peninsular Organics, Metrowaste 45 50 Mixed re- 1963 Closed (1967) Inc. Conversion fuse, digested sludge

Norman, International Naturizer 32 35 Mixed 1959 Closed (1964) Oklahoma Disposal Corp. refuse

Mobile, City of Mobile Windrow 272 300 Mixed re- 1966 Closed (1971) Alabama fuse, digested sludge 146 TABLE 3-39 (CONTINUED)

Capacity metric Capacity Type Began Location Company Process ton/day ton/day Waste operating Status

New York, Ecology, Inc. Varro 136 150 Mixed 1971 Operating New York refuse

Phoenix, Arizona Bio- Dano 272 300 Mixed 1963 Closed (1965) Arizona chemical Co. refuse

Sacramento Co., Dano of America, Dano 36 40 Mixed 1956 Closed (1963) California Inc. refuse

San Fernando, International Naturizer 63 70 Mixed 1963 Closed (1964) California Disposal Corp. . refuse

San Juan, • Fairfield Fairfield- 136 150 Mixed 1969 Closed (1972) Puerto Rico Engineering Co. Hardy refuse

Springfield, Springfield Organic Frazer- 18 20 Garbage 1954 Closed (1962) Massachusetts Fertilizer Co. Eweson 1961

St. Petersburg, Westinghouse Corp. ' Naturizer 95 105 Mixed 1966 Closed (1971) Florida refuse

Williamston, City of Riker 3.6 Garbage, 1955 Closed (1962) • Michigan Williams ton raw sludge, corn cobs

Wilmington, Good Riddance, Windrow 18 20 Mixed 1963 Closed (1965) Ohio Inc. refuse

materials. A screw press is used to reduce and dried. After drying, the compost is the moisture content of the shredded separated screened and bagged. refuse to approximately 58 percent before going into the digester. The system has relatively high operating costs, especially with respect to the The Fairfield-Hardy digester is shown digester. The rotating bridge with the in Figure 3-71. It should be noted that the augers for agitation must run continuously. material is fed into the digester from the A second major disadvantage is that the top around the outer cylindrical wall of only way to expand the plant is to build the digester. After the material has been another complete digestion tank. loaded into the digester, air is blown through the perforated bottom plate. This Table 3-40 provides an estimate of keeps the mixture in an aerobic state. The the capital costs, energy, and labor composting material is agitated by means needed to build and run different size of a number of augers. The augers are plants. In each case, the digester is attached to a rotating bridge arm. These designed for the total plant capacity. augers on the rotating arm do three things: one, blend the new wet pulp into older The economic aspects of the Fairfield- compost material; two, continually mix, Hardy composting process are fairly repre- aerate and turn over the material; and sentative of the majority of aerobic three, move the material toward the center processes. Since there are very few plants of the digester for removal by the stand- in actual operation, (see Glysson, et.al., pipe. ref. 3-92) the cost data available in the literature is somewhat limited and dated. After an average or nominal period An example of this is the 1968 Johnson, of 5 days of the digestion process the City data (ref. 3-90). Table 3-41 presents compost has moved to the middle of the tank the process cost for the Fairfield-Hardy and is removed. The material is then composting process and gives the credits windrowed for about 3 weeks for curing. available for resource recovery (ref. 3-28). After the curing is complete, it is moisten- From the preliminary analysis of other ed with a starch suspension, granulated, composting processes, it is believed that

147 I ALTERNATE DRY GRINDING PROCESS METAL WASHER AND MAGNETIC SEPARATOR

INORGANIC MATERIAL TO SALVAGE OR TO STORAGE LANDFILL WET PULPING C RIN9 PROCESS CONTROL FAIRFIELO-HARDY " T1Tllun PANEL DIGESTER • PELLETIZINO BAGGING PAN

(r«f. 3-6)

BAGGING

FIGURE 3-70 SCHEMATIC FLOW DIAGRAM FOR FAIRFI ELD-HARDY COMPOST SYSTEM

LE8END published data for similar but lower capa- (I) and (2) food conveyors city systems (Figure 3-72). However, in (3) ratatlne. brMgt «Mh (4) VtOMplpt for (9)dl

METRIC TONS/DAY 100 200 300 400 900 600 TOO 600 900 1000

Q DATA FROM REF 3-8 O DATA FROM REF S-Z8

FIGURE 3-71 SCHEMATIC OF FAIRFIELD-HARDY DIGESTER these cost figures are representative of the oost < structure of composting systems in general. An analysis of cost data shows that while one process might use less power, it usually uses either more labor or land investment. 100 200 300 400 SCO 600 TOO 800 900 1000 1100 REFUSE TONS/DAY The $6.92/metric ton ($6.28/ton) cost of refuse disposal for the 907 metric FIGURE 3-72 ton/day (1000 ton/day) composting system COMPOST COST DATA seems to agree fairly well with earlier

148 TABLE 3-40 ESTIMATES OF CAPITAL COSTS, ENERGY; AND LABOR REQUIREMENTS FOR FAIRFIELD-HARDY COMPOST SYSTEMS Capacity metric Capacity Capital cost Power requirements Labor require- ton/day (tons/day) (dollars) kw hp ments (men)

i 91 100 1,370,000 694 930 11 182 200 2,000,000 1186 1590 18 272 300 2,510,000 1365 1830 25 363 400 3,210,000 1910 2560 30 *ref. 3-8

this case, if no market were found for market can be created to make the opera- the humus, the cost for processing MMR tion economically feasible. would only go from $6.92 to $8.58/metric ton ($6.28 to $7.78/ton). This additional cost might have to be paid by the com- 3,5,3 METHANE PRODUCTION PROCESS munity where all other options are much more expensive. Under proper- economic subsidies, the humus could be given away Ideally, all solid waste would be or even landfilled. A discussion of the recycled or converted into useful products specifics of a particular market will be with high marketability. One such product given in the Appendix. is methane and the following discussion of methane production will follow this .In most cases, the compost plants general outline: introduction, small have remained open only as long as a steady systems, industrial and MMR systems, and- commercial market existed for the compost a .recovery system for sanitary landfills. or a subsidy or grant artificially supported the operation. A major problem has been -the humus market in larger metropolitan 3.5'. 3.1 GENERAL INTRODUCTION. areas. The problem is simply.that the volume of humus exceeds the compost market. ' The general introductory comments on However, no detailed analysis has been the theoretical considerations of methane done on developing a market for the com- production are based,mainly on refs. 3-93, post as a replacement for peat moss. With 3-94, and 3-95. proper preparation, advertisement, and pricing policies, the material might be The anaerobic decomposition of any able to compete with peat moss. An ex- complex organic substance is basically ample of this.is the processed sewage a two-stage process. The first stage sludge from the Milwaukee Metropolitan consists of the breakdown of the complex Sewage District which is sold as a lawn organic materials, in MMR by acid formation fertilizer under the name of Milorganite. bacteria into organic acids with the pro- The community might not provide a total duction of C02. These organic acids in market for the humus produced, but the pro- the second stage are acted on by bacteria fit from the retail sale of packaged known as methane formers to produce CH^ humus can be used to dispose of the remain- and C02. der. Let us consider a specific example. Most major population areas are shipping In the reduction of organic material centers. Therefore, grain is moved into by anaerobic digestion, the organic com- these regions on the railroads in either plexes are acted upon by a group of hoppers or box cars from the grain belts. floccules and anaerobic bacteria known Suppose the additional humus is shipped as acid formers. The organic fraction of to the grain belt in the empty hoppers the MMR consists of proteins, carbohy- or box cars. Here the humus could be drates and fats. This material undergoes sold to farmers for some price determined the acid fermentation which converts 35 by the nutrient value of the elements in percent of the material into shortchain the humus. This price could be set at organic acids. This consists of 15 per- - in economically viable level. The loss cent being converted into propionic acid on this operation would be matched against and 20 percent being converted into acetic the profit from the retail bagged humus acid. The other 65 percent of the organic sales in the urban area. A detailed material is converted into alcohols, market analysis of this suggestion needs aldehydes, and long-chain fatty acids. to be done in order to determine if the These percentages are not exact and depend

149 TABLE 3-41 ECONOMIC DATA-FAIRFIELD-HARDY COMPOST SYSTEM PROCESS COST SHEET PROCESS NAME: Similar to Fairfield-Hardy Compost DATA SOURCE: Ref. 3-28 CAPACITY IN TONS/DAY: 907 metric tons (1000 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land 5 400,000a a Includes site Preprocessing Eqmt 1,730,000 improvements . Processing Eqmt .5,500,000 Postprocessing Eqmt 940,000 Utilities No detail Building & Roads No detail Site Preparation b b See land cost Engr. & R & D 1,748,000 Plant Startup 153,000 Working Capital ' 229,000 Misc.: 6,400, OOOc c Auxiliary and support facilities . . TOTAL 517,100,000 • ;

OPERATING .COSTS ($ PER YR] d d Assumes 300 Maint. Material ' day /year Maint. Labor Dir. Labor Dir. Materials Overhead Utilities $'l,132,000e e Total operating Taxes . -. . cost • • ' Insurance . Interest Disposal of Residue .-. Payroll Benefits Fuel - Misc.: i

TOTAL $'1,133,000

CREDITS ASSUMED ($ PER YR) 1,103,000 COMMENT Fuel: Liquid . , Gas Solid NONE Power: Steam -, Electricity Hot Water NONE Magnetic Metals, $ 245,000 a a No credit $/ton NonmagnetiC' Metals 240,000 ,. detail given Glass 168,000 Ash Paper - Other:-. . Humus 450,000

TOTAL ($ PER YR.) $1,103,000

150 on the composition of the MMR. we can determine a theoretical methane value.

C H + The initial stage of methane produc- 30 48°19 (30-48/4-19/2) H20 -»• tion or the acid-fermentation is essentially a constant BOD (biological oxygen (30/2-48/8-1-19/4) CO2 + (30/2+48/8-19/4) CH4c demand) stage because the organic mole- 1 Jut cules are only rearranged. Thus, in the Since this calculation is approximate, the., general case, the energy production by this • results can be given as: step is very low and the microorganism C30«48°19 + 8.5 H2O * 7.3 C02 + 22.7 CH4 growth is also low. Since most of the energy produced is used by the bacteria This means that if you consider 1 metric for growth, there is minimal energy li- ton of MMR, with an assumed organic con- berated from the system. The first stage, tent of 50 percent, the amount of water does not stabilize the solid waste, but needed for the reaction is 112 kilograms it is essential for the second stage by (246.6 pounds), and the methane fermenta- converting the organic material to a form, tion will produce 210.5 kilograms (464 usable by the methane producing bacteria. pounds) of C02 and 298.7 kilograms (658.5 pounds) of CH4. Since the slurry must be The second stage takes place when approximately 60 percent water for the anaerobic methane forming bacteria act methane bacteria, the water added per ton, .upon the short chain organic acids. In assuming 24 percent initial moisture con- this stage, the short chain organic acids, tent, is approximately 200 kilograms (440 undergo methane fermentation with C02 acting pounds) per metric ton. Obviously the sys- as a hydrogen acceptor and being reduced tem will not .in general convert all the to CHj. The methane formed, being inorganic material in MMR to methane. Not soluble, in water, escapes from the system only does the methane production depend and can be used for a fuel. The production upon the composition of the waste, but on and loss of methane cause the stabilization a number of other environmental conditions. o'f the organic material. Since methane These conditions are temperature, reducing has a high energy content, most of the environment pH, nutrients, and nontoxic energy of the system goes into methane gas conditions. and not into the production of large amounts of cell mass and solids. Each One of the most important operational cubic meter of methane produced at stand- parameters is the temperature in the reac- ard temperature and pressure removes 2.9 tion vessel. Increasing temperature will kilograms of COD or BOD (1000 cubic feet increase the rate of reaction. There are, of CH4 at standard temperature -and pres- depending on the methane bacteria present, sure removes 178 pounds COD or BOD). two optimum temperature ranges. Mesophilic bacteria produces methane in the tempera- The methane'producing bacteria con- ture range from 30°C (86°F) to 37.5-C sist of several different groups. Each (100°F) while thermophilic bacteria produce group has the ability to ferment only methane in the temperature range from 49"C specific compounds. Therefore, the bac- (120°F) to 51°C (124°p). The reaction terial mixture in a methane producing • .rates are much higher f&r thermophilic pro- system should include a number of differ- cesses, but energy in the form of heating ent groups. When considering retention must be introduced into the system in times of solids, the rate of bacteria order to maintain these temperatures. production becomes important. For periods of 10 to 15 days of retention time, the The introduction of even small amounts rate of reduction is limited by methane of oxygen into the system will change it fermentation. For systems where the re- from a reducing environment and destroy tention time is longer than 15 days, the the methane formers since they are strict rate limiting aspect is then the hydrolysis anaerobes. Like most organisms, methane of organic solids. bacteria prefer pH values in the range of around 7.0. The actual range of optimum The actual destruction of organic pH values are 6.6 to 7:6, and below 6.2 material in MMR is directly related to the the acid conditions are quite toxic to production of methane. An equation has methane bacteria, even though the acid been developed to predict the theoretical forming bacteria will continue to grow. quantity of methane from the chemical compo- The C/N ratio values are similar to those sition of the waste. for aerobic bacteria, and again sewage sludge can be used to provide nutrient CnHaOb + (n - a/4 - b/2) H20 -- and nitrogen enrichment. The final requirement is that the system is free from (n/2 - a/8 + b/4) C02 + (n/2 + a/8 - b/4)CH4 toxic materials either in the form of inorganic salts or toxic organic compounds. This is a major problem in the case of MMR. Since a typical empirical chemical formula for the organic portion of MMR is given by: 3.5.3.2 SMALL SCALE METHANE PRODUCTION

151 Examples of small scale methane pro- 3.5.3.4 PFEFFER-DYNATECH ANAEROBIC duction are seen in the work of Singh (ref. DIGESTION 3-9), Fry and Merrill (ref. 3-97) and in articles in magazines such as the Mother Earth News (ref. 3-98, 3-99, 3-100, and The anaerobic digestion process deve- 3-101). While these are quite informative loped by Pfeffer (ref. 3-95) and Wise, et.al. with respect to the methane production (ref. 3-102) considers the reclamation of process, the application of these systems energy from organic refuse by the product'ion to MMR are limited. The use of these small of methane. The methane production ->rocess systems should be considered for'isolated also produces fairly large amounts o. carbon regions', third world countries, or regions dioxide. Separation of the C02 from the without energy resources. CO2 - CH4 mixture of gas produced by the digester, gives a burnable fuel gas grade One should also note that the same product. Since the predominant organic sanitary and zoning laws which control or component of MMR is cellulose, the stoichio- prohibit outside toilets, septic tanks, metry is : .individual wells, and trash burning in municipal regions would also, in most C6H10°5 + H2° * 3C02 + 3CH4 locations, presently apply to the backyard methane generator. Anaerobic digestion as described by the above equation decomposes 1 kilogram of MMR into 0.41 cubic meters of CH (1 pound 3.5.3.3 INDUSTRIAL AND MMR METHANE of MMR into 6.65 cubic feet of CH4) at PRODUCTION SYSTEMS standard conditions. The CH4 will be accompanied by an equal volume of COj, ie., 1 kilogram of MMR will also produce The large scale production of methane 0.41 cubic meters of C02- can be considered with respect to two material sources. These are the industrial The process can be described best by system and the municipal waste collection use of Figure 3-73. This figure shows, system. By industrial waste, we mean not by means of a block diagram, the major only that from industrial complexes in the components of the Pfeffer-Dynatech anaerobic petrochemical sense, but also from food system. Methane gas production from MMR processing plants and agribusinesses. The can be divided into four distinct and agribusiness category includes chicken separate operations. These consist of MMR brooder houses and cattle feed lots. handling, digestion, gas treatment, and effluent disposal. There are a number of feed lot operations either considering or entering the The MMR, handling consists of taking area of methane production from cattle the solid waste as delivered to the plant, manure. The general biological reduction and shredding it by means of dry primary process is obvious and has been outlined shredders. This reduces the maximum MMR previously. Where one has a separate particle size to a range.from 7.6 centi- sewage system for a specific waste, the meters (3 'inches) to 15 centimeters (6 special processing of this waste for inches). A magnetic separator removes maximum recovery value should be con-, ferrous metals followed by a Trommel screen sidered. An example of a system where to remove .the fine grit. The waste stream methane production is applicable is can then be passed through a hydropulper Omaha, Nebraska. In Omaha, there are 18 and then cyclone separators to reduce the major feed lots, and they are on a special size and remove nonferrous metals and glass. sewer for their wastes. Here the special The second possibility is an air classifier or separate processing of cattle manure for glass and nonferrous metal removal fol- would be the best economic approach. lowed by a second dry shredder. The final ideal particle size is less than 2.5 centimeters (1 inch). The remaining fraction--of With respect to methane production the MMR stream, the organic matter, is then from MMR, we will consider the Pfeffer- slurried with aqueous nutrients, pH control Dynatech anaerobic digestion system. additives in the form of lime, and hydrogen Even though a working plant prototype sulfide control additives in the form of system is not now in existence, the system ferrous salts. This mixture is then fed is well .researched and is based on proven into the digester. systems which produce methane from sewage sludge. The Pfeffer-Dynatech system is The proposed system consists of a num- essentially similar to all of the other pro- ber of separate large digester tanks. Each posed methane production systems. In its tank is maintained at constant pressure by basic aspects it is a scaled up version of a floating cover. The circular tanks are Singh's backyard system with the obvious constantly stirred to maintain an approxi- changes for the plant size and the use of mate constant density of suspension and MMR as the feed. thus uniform digestion. The digestion

152 TROMMEL AIR . SCREEN CLASSIFIER

RESOURCE RECOVERY TO TREATMENT

FIGURE 3-73 BLOCK DIAGRAM OF THE PFEFFER - DYNATECH ANEROBIC DIGESTION SYSTEM process is carried out in two steps. Power $2.78/10* ($0.01/KWH) First the -solids are solubilized by enzy- joules matic action. Second, these soluble products are digested by the microorganisms •steam $.95/109 ($l;00/million to produce CH4, CO->, and small amounts joules BTU) of other gases such as H2&. The cleanup of the gas to remove the acid fraction . cooling, $5.30/106 ($0.02/thousand would utilize natural gas technology. water liters. gallons) - The effluent production by the process, especially if it is continuous, produces, lime $27-.56/ ($25.00/ton) a problem. Even though the biological -. metric ton mass could be reclaimed'and recirculated into the digester, large amounts of labor $5.6 3/man-hour water must be cleaned up and disposed •: (28 men) of continuously. The other problem is , to dispose of the remaining digested supervision $6.63/man-hour solidsv (4 men) The economics of the Pfeffer-Dynatech disposal costs: system are based on the experimental work of Pfeffer and the scaled up pilot plant, Incineration $33/metric ($30/ton dry data by the Dynatech corporation. The of dewater?- ton solids) process costs and the resource recovery . ed cake data are itemized in Table 3-42. The -.- pilot plant information has been scaled landfill of $1.38/met- ($1.25 ton) up to the 907 metric ton/day (1000 ton/day) inorganics ric.ton information given in these tables. The following pertinent details are condensed sewage treat- $5.30/106 ($0.02/thou- from ref, 3-102. ment of .. liters-. sand gallons) • water 1. The estimates will vary with conditions at a particular time and place. However, a base-line model for operating 2. An estimate is made of the selling costs is .developed. This model uses the price of the methane to achieve a 15 percent following unit cost estimates: return on the equity for a-private investor

153 TABLE 3-42 ECONOMIC DATA-PFEFFER-DYNATECH METHANE GAS SYSTEM PROCESS COST SHEET

PROCESS NAME: Pfeffer-Dynatech Anaerobic Digestion DATA SOURCE: Dynatech Report (Ref. 3-102 CAPACITY IN TONS/DAY: 907. metric tons (1000 tons) DOLLARS COMMENTS

CAPITAL COSTS (TOT. $) Land (a) (a) Not included Preprocessing Eqrat 1,879,300 Processing Egmt 2,620,693 Postprocessing Egmt 3,062,218 Utilities ' Building & Roads 500, 000 (b (b) Building only Site Preparation Engr. & R & D 502,947 .Plant Startup 75,403 (c) Contingencies Working Capital 48,066 (d) Interest during Misc.: 2,342,058(c) construction 2,191,688(d) (e) Expense & profit 1,760,316(6) - contractor TOTAL 320,246(f! (f) Plant equipment TOTAL 15,302,935 OPERATING COSTS ($ PER YR] Maint. Material 194,817 Maint. Labor 187,008 Dir'. Labor 249,344 Dir. Materials 82,815 Overhead 319,264 Utilities 356,818 Taxes (Local) 350,670 Insurance Interest ' Disposal of Residue 1,969,424 Payroll Benefits Fuel Misc . :

TOTAL 3,770,16,0

CREDITS ASSUMED ($ PER YR) 5.714.791 " " " DOLLARS/YR. COMMENT

Fuel: (a) Not calculated Liquid • in report-calcu-*- Gas Methane l,240,000(a) la t ion done . Solid based on 330 day Power : yr and $.935/109 Steam joules ($.987/ Electricity 106 Btu-report Hot Water figure) Magnetic Metals 343,195(b) (b) 18.70/metric ton Nonmagnetic Metals (c) (17.00/ton Glass (c) (c) Glass & non fer- Ash rous metals as- Paper (d) sumed landfillin Other: Sewage sludge 618,502(e) (d) Light organics Disposal credit 3,513,094(f) landfilling (e) $55.00/metric to (50/ton) TOTAL ($ PER YR.) 5,714,791 (f) City pays 11. 70/ metric ton s (10.65/ton)

154 A standard gas utility method is disposal, graphs such as Figure 3-74 employed assuming:

period of depreciation 20 years DOLLAR PRICE/METRIC TON OF REFUSE REGION IS depreciation method 5% on total capi- WILLING TO Htl R>H DISPOSAL - • • • . tal-straight 9 to it .12 O.'M a line federal income tax rate 48% percent interest on debt 9% • debt/equity ratio 75%/25%

The cost model allows recovery credits only for ferrous metals as the inorganics are assumed landfilled. The other credits are for .disposal of municipal sewage sludge and the refuse itself. Credits are as follows: ' . ferrous metal 18.74/metric ton (S17.00/ton ' disposal of sewage sludge 55.13/metric ton ($50.00/ton) disposal of municipal . " I 2 3 4 » » 7 8 9 10 M 12 15 !«• IS wastes 11.74/metric ton DOLLAR PRICE/TO" OF REFUSE REGION IS WILLING ($10.65/ton) .10 PAY FOR DISPOSAL

The calculation of the methane selling price FIGURE 3-74 is ae follows: VARIATION OF METHANE PRICE NEEDED WITH 10* . . MUNICIPALITY LOCATION Joules 10° Btu of of Methane Methane might be developed. The'needed selling contribution of price of methane is shown vs. the price capital costs $1.52 *$1.602) per ton a municipality is willing to pay for contribution of oper. •refuse disposal. . Based on this example costs $1.49 ($1.573) graph, a community willing to pay $8.82/ penalties: metric ton ($8.00/ton) for refuse disposal filter cake disposal $1.53 ($1.610) would necessitate the private investor waste water treatment .$ .01 ($0.010) selling his methane at $1.61/109 joules inorganic waste ($1.70/106 Btu). If the;current or near disposal $ .09 ($0.100) term price of. natural gas in this area is total costs ?4.64 (§4.895) only $0.95/109 joules ($1.00/106 Btu), the feasibility of this disposal system credits: is clearly questionable. scrap iron $ .28 ($0.300) sewage sludge 4. Since carbon dioxide is also pro- disposal $ .51 ($0.540) duced, the-credit.situation could be im- municipal waste proved if a suitable market were available. disposal $2.91 ($3.070) The plant theoretically produces 227 total credits ?3.70 (?3.910) metric ton/day (250 ton/day) of carbon The selling price of the methane is dioxide and 86 metric ton/day (95 ton/day) then the difference between costs and credits of methane. Chemical companies are currently or $.94/10? joules ($0.985/10° Btu). paying about $8.821 metric ton ($8.00 per ton) .for 98% carbon dioxide with no sulfur 3. Any variation in the cost or cre- content. If the carbon dioxide is then dit items would change the selling price. purified to 99.9%> it may be sold for up The report indicates that the selling price .to $149/metric ton. ($1-35.00/ton) . This of methane needed is most sensitive to the added credit, depending on the purity of credit received for solid waste disposal. carbon dioxide, would shift the graph down In reality, this credit will also vary to the left indicating a lowered selling widely from place to place. A wide spec- price for methane. ,. , * trum of waste disposal costs are experienced across the country from 2.21/metric ton 5. Another set of credits may be ($2.00/ton) in a landfill to as high as obtained by adding other resource recovery $28.66/metric ton ($26.00/ton) in an 'equipment for the recovery of aluminum and incinerator. , glass. 4. To help.a local region decide on the feasibility of this system for waste 6. A lower cost structure would also be

155 obtained if public financing is used. the increase of gas production with time. Also an analysis of the gas content with , ., 7. The energy needs for the system time, Table 3-43 shows that the organic are about 35 percent of the methane pro- material progressively goes to an anaerobic duced. A tradeoff analysis must be made condition. This production of methane, concerning use of the methane or purchase which can last over a period of 10 years of power. for a 106 cubic feet/day landfill, is a major problem with respect to all sanitary 8. It is noted that the costs in this landfills. report are for a hypothetical 907 metric ton/day (1000 ton/day) system. The system itself is only .in the bench scale stage. TABLE 3-43 The Dynatech researchers, however, have LANDFILL GAS COMPOSITION* made attempts to achieve reliable figures based on current equipment prices and Time interval since Average percent accounting procedures. Start of cell completion by volume (months) N2 C02 CHj" 3.5.3.5 METHANE RECOVERY PROM SANITARY 0-3 5.2 88 5 LANDFILLS (ref. 3-103) 3-6 3.8 76 21 6-12 0.4 65 29 12-18 1.1 52 40 Let us now consider some of the prob- 18-24 0.4 53 47 lems of sanitary landfill and a possible • 24-30 0.2 52 48 solution to these. Two specific problems 30-36 1.3 46 51 to consider are the volume in landfill and 36-42 0.9 50 47 the production of gases by the MMR in the 42-48 0.4 51 48 landfill. The solution proposed is a modification on a system developed by NRG Nu Fuel Company of Newport Beach, Califor- nia. In this suggested proposal, the two The final solution involves consider- problem solutions are interrelated. ing both of these problems. The remaining fraction of the MMR which is mainly organic The first problem is that of landfill is mixed with some small amount of dried volume needed for MMR. The suggested solu- sewage sludge and compacted in a specially- tion to this problem is to use a prepro- prepared sanitary landfill. In this land- cessing system which will remove ferrous fill, some form of leachate barrier, plastic ^metal, glass, aluminum, and some newspaper. asphalt, etc., is placed in the bottom and A Black-Clawson type recovery system could along the sides. The landfill is then be used which could reduce the volume by filled with compacted, enriched, and separat- approximately 2/3. The remaining portion ed MMR. During the construction of the would be mainly organic. landfill, radial distribution tiles and vertical well shafts are constructed, keep- If one considers the history of gas ing the system closed, as necessary. Thus production in the compacted cell of a when the sanitary landfill is completed, a sanitary landfill, Figure 3-75, one notices system of gas collection wells with radial access is already in place. The landfill is then sealed with an air and water tight cover. Moisture' levels in the sanitary landfill are then raised to optimum levels by pumping water into the gas wells. The sanitary landfill is allowed to become a large anaerobic digester producing C0| and CH4. Since both of these gases are now recoverable and salable, markets should be available. After the proc.ess of biological degradation is complete, approximately 10 years or more, there are two possible uses for the site. The wells can be sealed and the land surface recovered for use, or the humus can be dug out and used for soil conditioning. In the latter case, the sanitary landfill site can be used again. This proposed system deserves further study. (REF 3- 103} 100 ZOO 900 400 BOO 600 TOO SOD 3,5,4 BIOCHEMICAL PROCESSES ELAPSED TIME SINCE CELL CONSTRUCTION (DAYS) FIGURE 3-75 GAS PRODUCTION -FROM AN Biochemical processing by definition EXPERIMENTAL SANITARY LANDFILL means that the characteristic chemical

156 aspects of specific biological organisms problems with respect to the lack of re- are employed to process and thus convert search using MMR may be grouped into two organic material. The biological organisms basic categories. The first category in- considered here will always be microorgan- cludes those processes which were developed isms usually in the form of bacteria, pro- for specially selected material and for tozoa, or fungi. These microorganisms are which the authors now suggest MMR as -an processing the organic material for their acceptable substitute. In these cases, own metabolic needs. This means that either further experimental studies must be done their waste products must be useful 6r:~the in order to verify these claims. The process must be modified to collect useable second category includes those processes and useful byproducts. which are designed to reduce a specific material. The consideration should be on The application of biochemical pro- the optimum use of the feed material. In cessing to the MMR problem means that highly other words,- are there other uses for the complex technology is applied to the solid material which require less total energy waste problem. The use of this technology consumption and are more economically is applied to the solid waste problem. viable than the proposed new 'use? The The use of this technology requires the following sections will consider one speci- use of explicit equipment and sometimes fic example of each type. sizable power demands inherent in the process. Another problem with biochemical The major emphasis in biochemical pro- systems is the type of feed they are de- cessing has been in the area of the conver- signed to accept. Industrial grade pro- sion of organic solid wastes into yeast or cess feed is usually highly homogeneous fungal protein as illustrated by the works and controllable with respect to the com- of Mailer.(ref. 3-104) and Rogers, et.al. position. However, MMR is highly hetero- (ref. 3-105). These studies are based on geneous and virtually uncontrollable with the existing and viable yeast dependent respect to composition. This leads to industries such as brewing. The studies • an obvious conflict with respect to pro- done so far consider pilot plants or com- cessing methods. puter modeling of plant processes. The next major problem with respect As Schulz notes (ref. 3-21), complete to biochemical processing of MMR is that economic feasibility data will not be of toxic materials. Metallic salts, - available until studies are done on the organic cyanide compounds, and industrial use of MMR as the cellulose source for feed solvents are examples of the toxic sub- to an integrated hydrolysis and/or fermen- stance which can poison a biological tation plant. The research done so far system. Since biochemical systems are has been on the production of ethanol by generally expensive, the value of the the anaerobic digestion of MMR by yeast or final product must of necessity be suf- the aerobic culture of yeast as a protein ficient to recover some of this cost. source for the use as a supplement in . ; Thus most biochemical processes are livestock feed. being developed to produce a food source. Because of FDA regulations the food is The first potential market is the fed only to domestic livestock. This yeast conversion of MMR cellulose to a li- means that the toxic material can do quid fuel, namely ethonol. This has his- one of two things. First, the poisonous torically been the method used to produce material can kill the microorganisms ethanol. However, since World War II, and/or poison the plant. Since most of ethylene from the petrochemical industry the biochemical processes are either'con- has been the product used for the produc- tinuous or semi-batch, this poisoning tion of ethanol. If the total MMR of could significantly affect the system. 1.8 x 10s metric ton/year (2 x 108 ton/year) Second, the toxic materials, in low were ultimately converted to ethanol, the levels, might be metabolized or absorbed total yield would be 1.82 x 1010 liters by the microorganisms. As the toxic (4.8 x 109 gallons) of ethanol. If the material moves up the food chain, the economics are viable, the market can easily classical cumulative effect will take absorb this amount of additional ethanol. place. This could lead to lethal dosages However, the price of the fermented ethanol in the ultimate consumer with similar production is not competetive with existing effects. Two major examples of this prices. would be pesticides such as DDT and heavy metals such as lead. Now that problems The production of protein from yeast inherent to the biochemical processing of has been of considerable interest for a MMR have been discussed, let us consider number of years, but the quality and the the other major problem with this approach. cost of the sugar needed for fermentation have made this method of protein production Studies done to date have been conduct- uneconomical. Considerations of MMR as ed on a small scale using laboratory equip- a possible nutrient source have led to a ment or using experimental input as a number of studies. substitute for MMR. Each of these prob- . The isolation of a specific yeast lems can be considered in some detail. The strain, the Torula strain, .

157 which will .consume both pentose and hexose, Callihan and Dunlap:(ref. 3-106). The pur- makes the reduction of MMR to protein pos- pose of the study was tot take previous sible. The two sugars are end products laboratory data and apply these results to of'cellulose hydrolysis. Even though a pilot plant. From this pilot plant, both yeast protein is currently produced on a sizing and economic studies could be done to continuous industrial scale in Europe and determine the expected characteristics for Japan, the substrate used is. not MMR. The a full-sized industrial plant. 7 lack of actual studies and pilot plants on the production of yeast protein from MMR is The pilot plant was designed so--that the major stumbling block to full scale use the fermentation operation could be carried of:this method. out using both batch and continuous flow production. The general flow sheet for the \;''The yeast produced as a protein supple- pilot plant is .given in Figure 3-76. The ment ;for animal feed would'have to compete plant's equipment is grouped into five with both' fishmeal and soybean meal. At distinct operational aspects: cellulose the' current' prices for these two commodi- handling, treatment, sterilization,•fermenta- ties, 'yeast protein is still more expensive, tion, and cell harvesting. even with the inexpensive cellulose source that MMR provides. ' In the initial processing step, the .size of the material is reduced. This is To show both some of the problems and done using a five bladed knife grinder fit- the promise, we will consider two specific ted with a 0.32 centimeter (1/8 inch) sizing ''processes. One, the production of pro- screen. This unit has a capacity of ,.136 tein from bagasse. Arid two, the production kilogram/hour (300 pound/hour) to 181 kilo- .of-glucose from cellulose. gram/hour (400 pound/hour). The chopped cellulose is then blown into a hopper and passed to the second stage. 3.5.4,1' PROTEIN PRODUCTION The second stage consists of a slurry . tank to undergo alkali contracting. .-.The The'production-of single cell protein temperature range is controllable from by use of a -specially designed chemical ambient room temperature to the boiling microbial plant applied to bagasse has been point of water 100°C (212°F). The slurry .studied by a group under the direction of is then dewatered by separating the.liquids

WATER OR RECYCLED LIQUOR •joii

GRINDER

FLOCCULENT MIXER/SETTLER

-.' LIQUOR TO : USE OR EVAPORATIVE AND - RECYCLE, CHILLED-WATER COOLERS

DRYER

(ref. 3-106)

DRY- CELL PRODUCT

FIGURE 3-76 PILOT-PLANT FLOW SHEET FOR PRODUCTION OF SINGLE CELL PROTEIN •I. • 158 and solids. The cellulose solids are research is that being done by the U.S. then passed through an oxidation oven Army at Natick Laboratories by Mandels, before being mixed with nutrients. Spano, Reese, and others. The enzymatic hydrolysis of cellulose is based on the The third stage consists of sterili- use of a biological catalyst. In the case ,-zation of the cellulose, followed by of this work, cellulose enzymes are used ..cooling before injection into the fer- to hydrolyze cellulose to glucose. mentation tank. The heart of the system is the fermentation tanks which contain Since the enzyme is produced by fungus - the microoganisms, in this case cellulose such as trichoderma viride for their own • .•utilizing bacteria such as cellulomonas, food production, the enzyme must be. ex- which turn the feed into protein. tracted from the fungus, or it will also consume the sugar. Because the hydolysis The rest of the plant is used to process is biological, it is low tempera- separate out the insoluable fraction and ture . Also the separate use of the enzyme to recover the dried cell product. In protects the fungi from toxic poisoning this plant this is single cell protein. by MMR. The group is doing work with a The pilot plant was specifically de- rapidly growing.mutant form of trichoderma signed to process sugarcane, bagasse. viride. In general, enzyme hydrolysis For this specific type of feed the plants require relatively high fixed capital operating economics of this size plant costs with respect to acid hydrolysis. -can be considered. An input of 48 metric ton/day (53 ton/day) will produce 15 Detailed studies of preprocessing, metric ton/day (16.7 ton/day) of protein sizing, and feed composition on the conver- and 9 metric ton/day of cattle feed. sion time from cellulose to glucose need This means that every metric ton (1.103 to be made for many different types of materials and especially for MMR. Hopefully to'n) of bagasse can be converted into 0.31 metric ton (0.35 ton) of protein and 0.19 the description of the pilot test plant metric ton (0.21 ton) of cattle feed. For a will soon be readily available in the 27 day month, a 453.5 metric ton/month plant published literature. The results of the corresponds to a 16.8 metric ton/day detailed studies of materials, especially (18.5 ton/day)'operation. Also a 907 MMR, will enable a determination to be metric ton/month (1000 ton/month) plant made of the range of applicability for corresponds to a 33.6 metric ton/day enzymatic cellulose hydrolysis. (37.0 ton/day) operation. The pilot plant study operating costs, as reported Since enzymatic hydrolysis is still by the MRI Report, Vol. II, (ref. 3-28) in the developmental stage, much more are given as $0.284/kilogram ($0.129/ research'needs to be done. Also further pound) for 16.8 metric tons/day and research should be done on mutant micro- $0.235Ailogram ($0.1065/pound) for 33.6 organisms or mixtures of these designed metric tons/day for the protein product. specifically to convert the organic portion Since plant expenses are not broken down of MMR more efficiently to useful products. between actual running plant and in- strumented pilot plant, the scaling factor is.not known. In addition to the 3,5,5 CRITICAL ASSESSMENT OF BIODEGRADATION economics of the operation there are SYSTEM ALTERNATIVES some other fundamental questions which must be answered. The separate sections on composting, The first problem with this process methane production, and bioconversion in- is that it is designed and developed clude suggestions:'on additional areas of specifically for bagasse. If this study either from a technical or an eco- system were to be considered for the nomic perspective. In this section, biochemical conversion of MMR, extensive certain critical assessments of the biode- modifications would need to be made, gradation system alternatives will be primarily in the preprocessing front-end made. The major considerations will be system. This energy and equipment cost with respect to the state of the art and coupled with the low production yield of the inherent advantages and disadvantages protein would not make this process of the particular methods. References 3- economically viable in the forseeable 110 and.3-111 contain additional informa- future. tion related to the overall solid waste management problem. 3.5.4.2 GLUCOSE PRODUCTION . (Ref. 3-107, 3-108, 3-109) 3.5.5.1 COMPOSTING

The conversion of cellulose to glucose• In composting, overall general studies and-thus to other materials also offers such as that done by McGauhey (ref. 3-112) a possible method of recovering energy . are available. Even though these studies from cellulose and waste paper fractions are not always either inclusive or specific, of MMR. An example of this type of certain general trends with respect to

159 composting systems can be identified. Eval- increase the speed of decomposition. If uation of the status of composting research mutant or special bacteria mixtures could and the history of composting raises cer- be developed, then the shortened time for -_ tain questions. The basic question to be stabilization of organic waste would make asked is whether the composting process is the inoculation of MMR economically more • at the present time a viable solution to- viable. the MMR problem. Since the microorganisms in anaerobic Research money is still being spent on decomposition attack the material from some developing methods for composting rate point on the surface, the size of decompos- acceleration using forced air systems. The able material is directly proportional to earlier research in Europe and the United the decomposition. . Therefore, the surface States raises questions as to the long area per unit volume must be maximized. term economic viability of such systems. This means that the material should be as Also because of previous work, the areas finely.ground as economically possible. -. .of viable composting research should be This fine grinding and separation in the limited primarily to other possible bio- preprocessing of the MMR or other material . degradation systems and/or microorganisms increases the cost of methane production which can enhance the process with respect greatly. to either speed, breakdown efficiency or final quality of the organic product. The advantage of methane production Full-size experimental-plants need funding facilities is that they can replace part if appropriate engineering-studies are to • of. the sewage treatment facilities. This be done. These studies could also in- is because sewage sludge is the optimum . elude possible alternative subsystems. C/N ratio enricher for the separated <.The use of full size plants would allow ground organic portion of MMR. The problem a study of actual operating problems over is that the final decomposed material is . , extended plant use. The composting still greater than 40 percent moisture and plants can be scaled to .any needed size, must be either used for liquid fertilizer .since there are no inherent limits imposed or dewatered and the effluent purfied. by the biophysics. All limits are deter- Since the methane process is, for economic mined by economic and social parameters. reasons, done at the lower temperature Thus only limited research is needed with range from 30"C (86«F) to 37.5-C (100'F) , respect to plant sizing economics. the liquid fertilizer.must be sterilized first if applied where pathogens would be Research on new alternatives is dangerous. cpossible. Because of the unique composi- ttion of MMR, the study of possible inoculum Since no extensive pilot plants have -.development using mutations of composting been constructed, no economic data or -bacteria should be considered. Also de- engineering data exist on the use of methane signing of plastics and synthetic materials digesters for the stabilization of MMR. for easier biological decomposition should More research using actual pilot plants be investigated specifically with respect needs to be done. Introductory pilot plant to microorganism breakdown by either aerobic studies by Stanford University Bhow that a or anaerobic digestion. large percentage of organic fraction is. non-decomposable. Also, those parts of the MMR which float on the slurry and resist 3.5.5.2 METHANE PRODUCTION agitational mixing do not decompose as readily as the same material would if sub- merged. Thus the laboratory studies used The production of methane from MMR is to predict the volume of solids remaining always the result of the anaerobic decompo- seem to be too low when plant size is • sition of the organic fraction of the solid scaled up. The size of the complete MMR 'waste. Since the methane bacteria require volume that would be processed at any one an oxygen deficient or reducing atmosphere, time for a large urban area dictates that the methane production process requires an the plants be tested first as part of an •isolated air tight environment in which to integrated MMR disposal network, or in ferment the MMR. areas with smaller populations. Because of the high energy content of The most promising area of application the CH4, only small amounts of the energy is the processing of specialized types of goes into producing more microorganisms. organic waste such as animal manure or food Therefore, at least-15 days minimum time wastes. Here the technology is readily is required in order to reduce an appreciable applicable and the environmental regulations percentage of organic material to methane. are making these applications necessary. Methods of increasing the growth rate of Plants developed for processing these homo- the microorganisms would shorten this time.. geneous organic waste products should pro- Research thus needs to be done on the vide the engineering data needed to deter- development of mutant anaerobic methane mine areas where further research efforts forming bacteria- or groups of bacteria to are required.

160 Application of the sanitary landfill cellulose fibers. The remaining' organic concept to produce a large natural methane portion can then be composted to produce generator, where applicable, has the best humus. Compared to true landfill costs, cost benefit ratio since it does not have this system may be more economical in some to compete with existing landfill costs. areas. The comparison of composting costs Also the recovered methane is essentually to incineration or pyrolysis must be on an free when compared with current landfill individual basis for each community. For cost accounting. small communities in metropolitan areas with populations of 50,000 or less, composting could offer potential economic advantages. 3.5.5.3 BIOCHEMICAL PROCESSES For larger cities .and regions composting does not appear trf be an attractive method of disposing of solid waste. At the present time, biochemical processes are still mainly in the research Methane production has not yet been and engineering laboratory stage. They applied to the MMR of a community. Because provide, with respect to MMR, interesting of the volume of the waste produced by a curiosities which suggest further study large metropolitan area in a single day, the to determine if they have economically first applications of methane production valid applications to the solid waste will probably be limited to smaller communi- disposal problem. ties, limited regions within a community, or specialized forms of agribusiness with The area that looks most promising for their animal and plant wastes. the- application of biochemical processes is the conversion of either low grade •Biochemical processes have their most homogeneous waste or potentially dangerous promising and most current applications in waste into more useful forms. In the case the area of hazardous waste disposal. The of low grade waste, this conversion turns area of most need is the detoxification of the waste into a more valuable product. organic poisons or organometallic compounds. The conversion of dangerous waste is Application of biochemical processing on a governed by safety factors and the need to commercial level to MMR depends on further deactivate dangerous materials into biolo- research and development. gically benign substances or substances which are easier to dispose. In summary, biodegradation systems are not today readily applicable or economically The biochemical conversion of solid viable to solve the MMR problems of the waste to more valuable food or fuel pro- major metropolitan regions. Application,of ducts will have to compete with all other biodegradation methods to areas with smaller conversion methods. In this competition populations, in certain specialized situa- for material, the future energy and food tions, could be economically viable. This needs will determine how a particular pro- is because 'the most applicable method, . duct is accepted and its cost. The composting, has a cost/unit mass price acceptance of biological process solutions which is essentially independent of the to the energy problem will still cause size of the operation. This is in contrast competition for specialized organic waste to incineration and pyrolysis, which must between methane production and biochemical have access to minimum regional solid waste processes. production levels to be economically viable. The results of research now in progress and future research are going to 3,6 SUMMARY determine the ultimate application and economic viability of biochemical processes. A large number of technical options with energy recovery are currently available 3,5,6 SUMMARY for use by a community. A number of other processes are in full-scale developmental stages, and information on their operations The previous section contains the should start becoming available within the critical assessment of the status and next 1-2 years. Communities facing a criti- potential of the different biodegradation cal refuse disposal problem and who must systems. In this section, the current therefore make an immediate decision on a applicability of. the different biodegra- solid waste disposal method should lean dation methods will be considered. toward proven technology. Composting, which has had a fairly Incineration consistent history of failure still has many unresolved difficulties. The most Water-wall incinerators for energy re- promising aspect is the front-end resource covery have the greatest total operating recovery of metal, glass, and some of the experience and can be considered a proven

161 process. For them to be economical, operate as cheaply as the present economics however, a market must be available for predict, then pyrolysis processes will com- the steam generated, and the steam selling pete favorably with remote landfill dis- . price should be keyed to equivalent energy posal costs, as well as recover energy. costs to allow for increases in the cost of energy. Pyrolysis, in general, offers the op* portunity for producing either a solid, '' The use of refuse as.a supplemental liquid, or gas, with most of the processes fuel (as in the St. Louis project) looks producing a gas; however, the heating very encouraging. The results are incom- value of the gas is generally much lower than plete in St. Louis, and more evaluation is •pipeline gas. This requires the gas'to be certainly necessary, particularly for com- burned on site (or at a nearby plant); bustion efficiency and emission controls. therefore, in the planning stages provisions The economics of this process appear to will have to be made for the utilization make it the cheapest of all methods con- of the product gas at or near the pyrolysis sidered in this report for energy recovery facility. The Garrett process produces a from MMR. Very good data should be available liquid fuel, which may be stored or trans- within the next 12 months. ported. An uncertainty currently exists as to the potential corrosive nature of the The use of sophisticated front-end fuel. systems to prepare refuse as a solid fuel for direct incineration has several ad- Although pyrolysis technology is not vantages. The fuel is in solid form, is fully developed, this means of energy re- easily stored or transported, has a rela- covery from MMR will eventually prove to tively high heating value, and may be be the most versatile. Four distinctly pneumatically injected into a boiler for different reactor processes are available, suspension-firing. Prepared solid fuels with variations in heating methods existing such as Eco-Fuel*M II have not been pro-, within those four categories. A wide choice cessed on a large scale basis, so proof front-end systems is also available. If duction or firing reliability has not a particular community does not have a mar- been established. The particle size, for ket for recycled materials, then a pyrolysis instance, for greatest firing efficiency process like Union Carbide's Purox system for a given boiler has not been deter- might be selected. On the other extreme is mined. This method of energy recovery from the Garrett front-end system which would MMR is at least a year away from demonstrat- allow for recovery of both ferrous and non- ed feasibility on a prototype plant. A ferrous metals as well as glass. Local solid fuel from prepared refuse could -be markets for energy and recovered resources very economical in areas where the energy will ultimately dictate the choice of the costs are high and sanitary landfills are system to be selected and the economics of not a viable option to the solid waste that system. disposal problem. NAAS Pyrolysis Process The generation of electricity directly from incineration of refuse, as in the CPU- The pyrolysis concept discussed in sec- 400 system, is still in the pilot plant tion 3.4.6 offers a number of advantages stage. Too many unsolved problems have' and appears to have good economic potential. been encountered thus far, and the system NAAS is a conceptual design only, however, has not yet reached the prototype stage of and experimental work is needed to- determine development. the feasibility of the system. The rotary kilns offer operational simplicity, and the Pyrolysis use of indirect heating of the refuse by dolomite should give a high heat transfer Many different pyrolysis processes rate and produce a fuel gas of moderate heat- are currently available for energy re- ing value. The major uncertainties in the covery from solid waste. Several of the system are the complexities of transporting processes have been demonstrated on large- and cleaning the hot solid stream and the scale pilot plants (greater than 32 metric aluminum recovery. Further research on the tons (35 tons per day), and at least five NAAS process is recommended. pyrolysis plants are being built on a commercial basis. Much more data should be- Biodegradation and Resource Recovery Systems come available within a year, particularly from Baltimore's Monsanto Landgard plant Composting is perhaps the most proven and .from Union Carbide's Purox plant. The technology of any of the energy/resource economics will be a particularly important recovery systems analyzed in this report. factor to consider in the new pyrolysis Unfortunately, composting plants have been plants. The current economic data, by the least successful, with only one or two necessity, has to be scaled up from small plants currently still in operation. Com- pilot plants and involves a number of posting offers moderate volume reduction, unknowns. If the plants can, in fact. and may be a feasible solid waste disposal

162 method for smaller communities, but it Resource recovery systems, similar to does not appear to be a viable method for the Black-Clawson process or the front-end large municipalities. systemsfof a number of energy recovery processes, involve proven-. technology for Methane recovery from solid waste recovery of magnetic materials and glass. in existing landfills is currently Recovery of nonmagnetic nfetals, especially possible, and the possibility exists for aluminum, and color-sorted glas's involve future methane recovery from specially advanced technology, which has not demon- designed sanitary landfills. The latter strated on a large-scale commercial basis. method is unproven and involves long- Any community interested in resource/re- range planning. Biochemical processes covery must always be cognizant of the are feasible now for disposal of certain markets for the recycled materials. industrial wastes, but the application to refuse disposal is still in the conception- al and research stages.

163 SELECTED REFERENCES at Solid Waste Resource Conference, by Battelle Memorial Institute, Co- lumbus, Ohio; May 13, 1971. 3- 1 Jeffera, E. L.; and Nuss, R. H.: So- lid Waste as an Energy Source. Rpt. 3-15 Morey, B.; and Rudy, s.: Aluminum D2-118534-1, Boeing Aerospace Com- Recovery From Municipal Trash by pany > February 4, 1974. Linear Induction Motors. 103rd An- nual Meeting of American Institute 3- 2 Resource Recovery—The State of of Mining, Metallurgical and Petro- Technology. Midwest Research In- leum Engineers, Dallas, Texas, Feb. stitute .Report. (NTIS NO. PB 214 24-28, 1974. 149)., February 1973i 3-16 Cummings, J. P.: Glass Recovery From 3- 3 Solid Waste Shredding Growing in Municipal Trash by Froth Flotation. Importance. Waste Age Magazine, Proceedings of the Third Mineral Waste May/June 1974, pp.- 30-36. Utilization Symposium, Chicago, Il- linois, March 14-16,' 1972. 3- 4 Seven Year Experiment. Solid Waste Management, Feb., 1974, pp. 16-58. 3-17 Solid Waste Resource Recovery Plant. Bulletin by Combustion Equipment As- 3- 5 Rof, J. A.: Refuse Shredders. sociates, Inc., and Arthur D. Little, Waste,Age Magazine, May/June 1974, Inc. pp. 58-66; . 3-18 Bauer, H. F., et. al.: Technical Re- 3- 6 Hammermill, Inc.: Refuse Appli- port on the Garrett Pyrolysis Pro- cations Calculations. May 8, 1972. cess for Recycling Municipal Solid Waste. (EPA grant rpt: PL91-512) 3- 7 Allis-Ghalmers: Refuse Shredder Garrett Research and Development Cor- Specifications. Model KH 12/18, poration Report No. 72-022 A & B, Bulletin 3355371. Dec. 1972. 3- 8 Drobhy, N. L.; Hull; H. E.; and 3-19 Stump, P. L.: Solid Waste Demon- Testin, R. F.: Recovery and Uti- stration Projects. EPA SW-4p, 1972. lization of Municipal Solid Waste. Report SW-10C, Battelle Memorial 3-20 U. S. Environmental Protection Institute, Columbus Laboratories, Agency: Second Report to Congress; 1971. (EPA PH 86-67-265), Columbus Resource Recovery and Source Re- Laboratories,.1971. duction, Publication SW-122, 1974. 3-9 Stearns, R. P.; and Davis, R. H.: 3-21 Schulz, H. W.; Neamatalla, M.; Tong, The Economics of Separate Refuse G.; and Young, M.: Pollution-Free Collection. Waste Age, May/June System for the Economic Utilization 1974, pp. 6-15. of Municipal Solid Waste for the City of New York. Phase I - A Critical 3-10 Materials Recovery System—An En- Assessment of Advanced Technology, gineering Feasibility Study. Na- Columbia University, June 15, 1973. tional Center for-Resource Recovery, Inc., Washington, D. C., December 3-22 Jackson, F. R.: Energy from Solid 1972. Waste. Noyes Data Corp., Park Ridge, N. J., (1974) . 3-11 Boettcher, R. A.: Air Classification of Solid Wastes. Publication SW-30C, 3-23 Leatham, H., Jr.: A "Powerful" Solu- Stanford Research Institute, Irvine, tion to the Solid Waste- Problem. Bul- California, 1972. (Federal Solid letin by Commonwealth Associates, Inc., Waste Management Program PH 86-68- Jackson, Michigan. 157) . ; 3-24 Astrom, L.; Kranebitter, F.; Stran- 3-12 Brison, R. J.} and Tangel, 0. F,: dell, O.; and Harris, D. W.: A Com- Development of a Thermoadhesive Me- parative Study of European and North thod for Dry Separation of Minerals. American Steam Producing Incinera- . Mining Engineering. Aug. 1960, tors. Proceedings of the 1974- Na- pp. 913-917. tional Incinerator Conference, May 12-15, pp. 255-266. 3-13 Bleimeister, W; C.;-and Brison, R. J.: Benefaction Application of the Gravi- 3-25 Roberts, R. M.; Sommerlad, R. E.; and tational Inertial Classifier. Mi- Konopka, A. P.; et. al.: Systems . ning Engineering. Aug. 1960, pp. Evaluation of Refuse as a Low Sulphur 918-921. Fuel, Vol. II. EPA Contract No. CPA 22-69-22. NTIS Report PB 209-272 3-14 Rydor, R. J.; and Abrahams, J. H., November, 1971. Jr.: Separation of Glass from Municipal Refuse. Paper presented

164 3-26 Massey, D.; Kelly, W. E.; Landis, E. 3-38 Vaughan, D. A.; Miller, P. D.; and K.; .and McKinley, M. D.: Urban Re- Boyd, W. K.: Fireside Corrosion in fuse Incinerator Design and Opera- Municipal Incinerators versus PVC tion: State of the Art. U. S. Bu- Content of the Refuse. Proceedings reau of Mines (HER Report No. 133- of 1974 National Incinerator Con- •-. .119), Bureau of Engineering Research, ference, May, 1974, pp., 179-189. .-, .University of Alabama, June 1971. 3-39 Fernandes, J. H.; and Shenk, R. C.: 3-27 White, H. J.: Industrial Electro- The Place of Incineration in Re- static Precipitation. Addison Wesely source Recovery of Solid Waste. Publishing Co., Reading, Mass., 1963. Proceedings of the 1974 National In- cinerator Conference, Miami, Florida; 3-28 -Resource Recovery Processes for May 12-15, 1974, pp. 1-10. Mixed Municipal Solid Wastes - Part II - Catalogue of Processes, Mid- 3-40 Aubin, H.: The New Quebec Metro In- west Research Institute Final Re- cinerator. Proceedings of the 1974 port - Project 3634D, December, National.Incinerator Conference, • ...-.- 1972. Miami, Florida; May 12-15, 1974, p. 205. 3-29 Pepperman, C. M.: The Harrisburg Incinerator: A System Approach. . 3-41 Sutterfield, G. W.: Refuse as a Proceedings of the 1974 National Supplementary Fuel for'Power Plants. Incinerator Conference, May 12-15, Interim EPA Progress Report, Nov., pp. 247-253. 1973 to March, 1974, July, 1974. 3-30. Wilson, M. J.: A Chronology of the • 3-42 Steel Products News Bureau. Ameri- Nashville, Tennessee Incinerator can Iron and Steel Institute Bulle- with Heat Recovery and the Com- tin, New York; March 8, 1973. patible Central Heating and Cooling Facility. Proceedings of the 1974 3-43 Low, Robert A.: Energy Recovery National Incinerator Conference, from Waste-Solid Waste as Supple- May 12-15, pp. 213-221.. mentary Fuel in Power Plant- Boilers. EPA Report SW-36d. ii, 1973. 3-31 Chapman, R. S.; and Wocasek, F. R.: . . CPU-400 Solid-Waste-Fired Gas Tur- 3-44 Winners Named for Construction and bine Development. Proceedings of Operation of $80,000,000 Resource the 1974 National Incinerator Con- . Recovery Plants in.Connecticut. Re- ference, May 1974, pp. 347-357. - source Recovery, Apr./May/June, 1974, pp. 8-9. 3-32 Horner and Shifrin, Inc.: Solid Waste as Fuel for Power Plants. 3-45 Burton/ R.' S.; and Bailie, R. C.: - NTIS Report No. PB-220 316, 1973. Fluid Bed Pyrolysis of Solid Waste Materials. Combustion, Feb. 1974, 3-33 Generation, of Steam from Solid pp. 13-18. ' • Wastes, Metcalf and Eddy, Inc., EPA Report PB-214 166, 1972. 3-46 Aldrich, D. C.: Kinetics of Cellu- lose Pyrolysis. PhD Dissertation. 3-34 Standrod, S. E., Jr.: The RESCO MIT, Feb. 1974. North Shore Facility. Presented at the U. S./Japan Energy Conserva- 3-47 "OSWMP/PDD Issue Paper - Pyrolysis tion Seminar, sponsored by the South- of Solid Waste" Office of Solid west Research Institute, San An- Management Program, Environmental tonio, Texas, Feb. 1974. Protection Agency, July 1972. 3-35 Bulletin, Combustion Power Company, 3-48 "A Proposed Plan of Solid Waste Inc., 1346 Willow Road, Menlo Park, Management for Connecticut," pre- California, 1972. pared by General Electric, 1973. 3-36 Bulletin: The CPU-400 Pilot Plant. 3-49 Anderson, J. E.: The Oxygen Refuse Combustion Power Company, Inc., Converter - A System for Producing 1346 Willow Road, Menlo Park, Cali- Fuel Gas, Oil, Molten Metal and Slag fornia, December, 1972. from Refuse. Proceedings of the ASME 1974 National Incinerator Con- 3-37 Bobco, D. L.: Proposed Analysis of ference, pp. 337-346. . Economic and Environmental Feasi- bility of Utilizing Reclamated So- 3-50 Finney, C. S.; and Garrett, D.E.: lid Waste as a Fuel Source for The Flash Pyrolysis of Solid Wastes. Production of Electricity. Re- 66th Annual AIChE Meeting Philadelphia, port M71-31, The Mitre Corporation, Pa., Nov. 1973. (Garrett Research and June, 1971. Development Corporation Rpt. No. 73- 021). . ;

165 3-51 Mallan, G. M.; and Finney, C. S.: 3-64 Wilson, D. G., ed.: The Treat- New Techniques in the Pyrolysis of ment and Management of Urban Solid Solid Wastes. 73rd Nat'l AIChE Waste. Technomic Publishing Co., Meeting, Minneapolis, Aug, 1972. Inc., Westport, Conn., 1972, p. 140. (Garrett Research and Development Corporation Report No. 72-035). 3-65 Bailie, R. C.; and Ishida, M.: Gasification of Solid Waste Ma- 3-52 Stola, J.; and Chatterjee, K.: An terials in Fluidized Beds. Chemi- Advanced Process for the Thermal cal Engineering Applications in Reduction of Solid Waste. Con- Solid Waste Treatment, AIChE Sym- tained in "Solid Waste Demonstration posium Series 122, Vol. 68, 1972, Projects— Proc. of a Symposium," pp. 73-80. EPA Publ. SW-4p, 1972, pp. 109-127. 3-66 Bailie, R. C.; and Burton, R. S., 3-53 Knight, J. A.; Tatom, J. W.; Bowen, Ill: Fluid Bed Reactors in Solid M. D.; Colcord, A. R.; and Elston, Waste Treatment. Chemical Engi- L..W.: Pyrolytic Conversion of neering Applications in Solid Waste Agricultural Wastes to Fuels. Pre- Treatment, AIChE Symposium Series sented at the Annual Meeting of the 122, Vol. 68, 1972, pp. 140-151. American Society of Agricultural Engineers, Stillwater, Oklahoma, 3-67 Bailie, R. C.: High Energy Gas June 1974. from Refuse Using Fluidized Beds. West Virginia Univ., Final Report 3-54 Hammond, V. L.; et al: Energy from to EPA on Grant 5-R01-EC-00399-03- Forest Residuals by Gasification of EUH, Aug. 1972. Wood Wastes. Pulp & Paper, February, 1974. 3-68 Pyrolysis of Solid Waste: A Tech- nical and Economic Assessment. Stan- 3-55 Hammond, V. L.: Pyrolysis-Incinera- ford Research Institute Report for tion Process for Solid Waste Dis- West Virginia University, Sept. 1972. posal. Final Report, Battelle Northwest Laboratories, Grant No. 3-69 Sterba, J. D.: Garbage Pile Turned 1, G06-EC-00329 (EPA), December, to Fuel. Washington (D.C.) Star- 1972. News, page A-3, Saturday, .Nov. 24, 1973. 3-56 Pyrolysis Study of Fuel from Solid Waste. Preliminary Document by 3-70 Pyrolysis - Production of Gaseous Barber-Colman against NASA Contra*ct Fuel from Solid Waste. A technical Number NAS 914305, Aug. 1, 1974. proposal submitted to NASA, JSC, in response to request for Proposal 3-57 Solid Waste: Most of It Still Goes 9-BC731-38-4-86P, by Arthur D. Little, to.the Dump. Engineering News Re- Inc. and Combustion Equipment Asso- cord, Nov. 22, 1973, pp. 22-25. ciates, Inc., April, 1974. 3-58 Solids Recycling Takes Shape in 3-71 Hammond, V. L.; and Mudge, L. K.:' Twin Cities. Engineering News Re- Feasibility Study of Use of Molten cord, March 21, 1974, pp. 51-52. Salt Technology for Pyrolysis of Solid Waste. Final Report, Con- 3-59 Storck, W. J.: Sludge is Beautiful tract No. 68-03-0145, Battelle North- in the Twin Cities. Water & Wastes west .Laboratories for EPA, April, Engineering, July 1974, pp. 43-45. 1974. 3-60 Linaweaver, F. P.: Baltimore Tries 3-72 Nichols Herreshoff Multiple Hearth Pyrolysis. The American City, May, Furnaces. Bulletin No. 233, Nichols 1974. Engineering and Research Corp., New York. 3-61 Bielski, E. T.; and Ellenberger, . A. C. J.: Landgard for Solid Waste. 3-73 Sanner, W. S. et al.: Conversion Proceedings of the 1974 National In- of Municipal and Industrial Refuse cinerator Conference, Miami, May 1974, into Useful Materials by Pyrolysis. pp. 331-336. Bureau of Mines Report No. 7428 (1970) . 3-62 Landgard System for Resource Re- . covery and Solid Waste Disposal. 3-74 Schlesinger, M. D., et al.: Pyroly- Monsanto Enviro-Chem Systems, Inc., sis of Waste Materials from Urban & Bulletin, March, 1974. Rural Sources. Proceedings of the Third Mineral Waste Utilization Sym- 3-63 Boegly, W. J. et al: MIUS Tech- posium, Chicago, March 1972. nology Evaluation - Solid Wastes. ORNL-HUD-MIUS-9 Report, Oak Ridge 3-75 Feldmann, H. F.: Pipeline Gas from National Laboratory, Jan. 1973, Solid Wastes. AIChE Symposium Series p. 70. G8 (122) , 1972, pp. 125.-131.

166 3-76 Kaiser, E. R.; and Friedman, S. Applied Microbiology, Vol. 2, . B.: The Pyrolysis of Refuse Com- No. 1, January 1954, pp. 45-53. ponents. Combustion, May, 1968, pp. 31-36. 3-89 Wiley, J. S.; and Kochtitzky, O. W. : Composting Developments in the United 3-77 Rosen, B. H.; Evans, R. G.; Cara- States. Compost Science, Vol. 6, belli, P.; and Zaborowski, R. B.: No. 2, Summer 1965, pp. 5-9. Economic Evaluation of a Commercial Site Refuse Pyrolysis Plant. Pro- 3-90 Breidenbach, A. W., Director; Staff ceedings of National Industrial of the Federal Solid Waste Manage- Solid Wastes Management Conference, ment Research Office, Environmental University of Houston, May 1970, Protection Agency: Composting of pp. 393-406. Municipal Solid Wastes in the United States. EPA SW-47r, G. P. O., 1971. 3-78 Lessing, L.: The Salt of the Earth Joins the War on Pollution. Fortune, 3-91 Sanders, F. A.; and Bloodgood, D. July 1973, pp. 138-147. E.: The Effect of Nitrogen-to-Carbon Ratio on Anaerobic Decomposition. 3-79 McFarland, J. M., et al.: Comprehen- Journal of the Water Pollution Con- sive Studies of Solid Wastes Manage- trol Federation, Vol. 37, No. 12, ment. Final Report, UCB-Eng-2907, December 1965, pp. 1741-1752. USPHS 2RO 1 EC 00260-05, SERL Rpt. No. 72-3, May 1972. 3-92 Glysson, E. A. et al.: The Problem of Solid-Waste Disposal. College of 3-80 Ricci, L.: Garbage Routes to Me- Engineering, University of Michigan, thane. Chemical Engineering, May Ann Arbor, Michigan, 1972. 27, 1974, pp. 58-60. 3-93 Pfeffer, J. T.; Leiter, M.; and Wor- 3-81 Pyrolysis - Production of a Gaseous lund, J. R.: Population Dynamics in Fuel from Solid Waste, Vol. I. A Anaerobic Digestion. Journal of the Technical Proposal submitted to NASA, . Water Pollution Control Federation, JSC in response to request for Pro- Vol. 39, No. 8, August 1967, pp. 1305- posal 9-BC731-38-4-86P by Hamilton 1322. Standard, NASA Contract No. NAS-9- 14306, April, 1974. 3-94 Dogue, R. R.; McKinney, R. E.; and Pfeffer, J. I.: Solids Retention in 3-82 Solid Waste Disposal Plans for Mon- Anaerobic Waste Treatment Systems. roe County. Vol. I, II, III. Ro- Journal of the Water Pollution Con- chester Engineering Society, Roches- trol Federation, Vol. 42, No. 2, ter, New York, April, 1972. Part 2, February 1970, pp. R29-R46; 3-83 Garrett, D. E.; and Sass, A. S., 3-95 Pfeffer, J. T.: Reclamation of assignors to Occidental Petroleum Energy from Organic Refuse. (Grant Corp., U. S. Patent No. 3,698,882, No. EPA-R-800776) Department of Civil Oct. 17, 1972. Continuous Phase for Engineering, University of Illinois, the Conversion of Carbonaceous Solids April 1973. into Pipeline gas. 3-96 Singh, R. B.: Bio-Gas Plant, Gen- 3-84 Oxygen Plant Will Produce Fuel Oil erating Methane from Organic Wastes. From Refuse. Oil and Gas Journal, Gobar Gas Research Station, Ajitmal, March 19, 1973. Etawah (V. P.) India, 1971. 3-85 VanHorn, K. R., ed.: Aluminum Fab- 3-97 Fry, L. J.; and Merrill, R.: Methane rication and Finishing. Vol. III. Digesters for Fuel Gas and Fertilizer. American Society of Metals, Metals The New Alchemy Institute-West, Santa Park, Ohio, p. 3. Barbara, California, 1973. 3-86 Cronch, C. N.; and Sleppy, W. C.: 3-98 Gobar Gas; Methane Power in India. Oxidation of High Purity Aluminum The Mother Earth News, No. 12, No- and 505- Al-Mg Alloy at Elevated vember 1971, pp. 28-31. Temperature. J. .of Electro, Chem. Soc., Vol. 108, 1961, pp. 322-327. 3-99 Mother's Methane Maker; A test unit designed by Ram Bux Singh. The Mother 3-87 Zanoni, A. E.: Potential for Ground Earth News, No. 18, November 1972, Water Pollution from the Land Dis- pp. 12-13. posal of Solid Wastes. CRC Critical- Reviews in Environmental Control, 3-100 The Plowboy Interview; Ram Bux Singh. Vol. 3, No. 3, May 1973, pp. 225-260. The Mother Earth News, No. 18, No- vember 1972, pp. 6-11. 3-88 Golueke, C. G.; Card, B. J.; and McGauhey, P. H.: A Critical Evalua- 3-101 The Plowboy Interview; L. John Fry. tion of Inocutums in Composting. The Mother Earth News, No. 23, Sep- tember 1973, pp. 6-12. 167 3-102 Wise, D. L., et al.: Fuel Gas Pro- 3-107 Reese, E. T.: A Microbiological duction from Solid Waste. Report Process Report, Enzymatic Hydroly- No. 1151, NSF Contract C-827, Dy- sis of Cellulose. Applied Micro- natech Corp., Cambridge, Mass., biology, Vol. 4, No Number, 1956, January 1974. pp. 39-45. 3-103 Brunner, D. R.; and Keller, D. J.: 3-108 Brandt, D.; Hontz, L.; and Mandels, Sanitary Landfill Design and M.: Engineering Aspects of the En- Operation. EPA SW-65ts, G.P.O., zymatic Conversion of Waste Cellu- 1972. lose to Glucose. AIChE Symposium Series, Vol. 69, No. 133, pp. 127- 3-104 Meller, P. H.: Conversion of 133. Organic Solid Wastes Into Yeast; an Economic Evaluation. H. E. W.— 3-109 Reese, E. T.; Mandels, M.; and Weiss, P. H. S. Publication No. 1909, A. H.: Cellulose as a Novel Energy G.P.O., 1969. Source. Advances in Biochemical Engineering, Volume 2 (Springer-? 3-105 Rogers, C. J.; Coleman, E.; Spino, Verlag, 1972), pp. 181-200. D. P.; and Purcell, T. C.: Pro- duction of Fungal Protein from 3-110 Hagerty, D. J.; Pavoni, J. L.; Cellulose and Waste Cellulosics. and Heer, J. E., Jr.: Solid Waste Environmental Science and Tech- Management. Van Nostrand Reinhold nology, Vol. 6, No. 8, August Company, 1973. 1972, pp. 715-718. 3-111 Golueke, C. G.: Critical Review of 3-106 Callihan, C. D,; and Dunlap, C. E.: the Literature on Solid Waste Manage- Construction of a Chemical-Micro- ment. CRC Critical Reviews in En- bial Pilot Plant for Production of vironmental Control, Vol. 3, No. 3, Single-Cell Protein from Cellulosic May 1973, pp. 2,61-301. Wastes. Contract No. PH 86-68-152, Department of Chemical Engineering, 3-112 McGauhey, P. H.: American Compos- Louisiana State University, EPA SW- ting Concepts. EPA SW-2r, G.P.O., 24c, G.P.O., 1971. 1971. .

168 Chapter 4 Markets

B'ODEGRADATIO INCINERATION? 4.1 INTRODUCTION 4,2 MARKETABLE PRODUCTS

Since market considerations are the It is difficult to imagine that all primary determinants of the economic viabil- components of a solid waste disposal system ity of energy and resource recovery systems, can be effectively utilized, it is, how- it is imperative that a community carefully ever, an ideal goal and this section will negotiate the sale of process outputs. In list some of the products that result from a discussion of secondary material markets, the solid waste stream including material Darnay (ref. 4-1) states: recovered during pre-and post processing. It is recognized that Some products and by- "An axiom in the salvage industry is products cannot be used in their present that "scrap is not sold, it is bought." state, but additional processing might make The skilled secondary materials dealer •them marketable. This of course, is depen- is a skilled buyer. Because he sells dent upon technical and economic consider- a substitute for raw materials, he ations . cannot control his selling price. It is determined by demand, which in turn is influenced by avail- 4,2,1 MATERIAL RECOVERED BEFORE CONVERSION ability and cost of virgin resources.

Demand and price fluctuate; the The following list of products is rep- dealer sometimes may be forced to tap resentative of those that can be reclaimed every conceivable source to satisfy prior to any conversion: demand. At other times, he must "turn off" his poorer sources. If ferrous metals necessary, he will buy from his best glass sources to protect them during periods paper products (newsprint, card- when demand is low, in order to retain board) them as sources when demand is again plastics high. nonferrous metals (aluminum, zinc, lead, copper) The successful dealer keeps his inventories low, buying at the appropriate price. He avoids long-range 4.2,2 PRODUCTS DERIVED FROM CONVERSION commitments to buy (especially from poor sources) and to sell (unless PROCESSES the sales price is negotiated high enough or is pegged just above a These are the most common products published market price). The skilled resulting from incineration or pyrolysis. dealer "rides the market", buying These appear in varying amounts and qualities only what he can sell, selling every- depending on the process, and include: thing he buys, and keeping a safe margin between his buying and selling fuel gas prices." fuel oil solid fuel As noted in Chapter 3, process outputs char are very dissimilar and it is not enough to methane be assured that all output products can be power sold. Demand and price fluctuate, and daily electric changes can be noted in the secondary mate- steam rial markets. A fact finding group may evaluate the cost of a disposal system based on a current price of $17/metric ton for recovered ferrous metal, only to discover that 4.2.3 CONVERSION BYPRODUCTS the price has dropped to $5/metric ton by the time the plant is built and on line. The Ideally^ there would be no pollutants extreme fluctuation in the price of recycled and no residue to be landfilled after the newspaper is another good example of the un-- solid waste had been processed. Currently certanity which must be considered when try- research is being conducted to see if by- ing to estimate credits in the economics products can be used in construction mate- analysis. Finding product markets and nego- rials or soil conditioners. Typical of tiating guaranteed prices may be the key to conversion byproducts are: keeping incineration and pyrolysis costs within acceptable limits. frit fiber and humus This chapter examines the products of fly ash energy and resource recovery systems and C0 focuses on the economic value, marketing 2 problems, and future prospects for these compost products. slag, glass stone, dirt residue '

170 4.3,2 FEDERAL TAX POLICIES FOR VIRGIN 4.3 :LATED TO CURRENT MARKET MATERIALS

As discussed in Chapter 2, there are Several Federal tax policies give "-'bene- a number 'of Federal laws and regulations or fits to industries engaged in the recovery -___ policies that discourage the sale of energy of virgin materials. At the present time, and'resources recovered from municipal such Federal tax policies apply only to re- solid waste. While such policies do not covery of natural or virgin resources and prohibit such sales they do give advantages not to the same material recovered from to the use of virgin resources and thus dis- secondary sources. courage the use of products manufactured from secondary materials. Examples of these The EPA in its Second Report to 'policies are freight rates for secondary Congress estimated the total tax benefits materials, depletion allowances and rules from preferential treatment in the areas of of capital amortization, and federal depletion allowances, capital gains tax policies fixing the price of natural gas. treatment, expensing of capital improvements for tax purposes, and foreign tax allowances. Certain practices by-a segment of the These estimates are displayed.below in Table public sector cause local fluctuations in 4-1 and are discussed in Chapter 2. market prices and demand. For example, 'paper drives by church or civic groups can saturate a local used-paper buyer to the TABLE 4-1 extent that regular-used-paper suppliers SUMMARY OF ESTIMATE OF TAX BENEFITS, 1970 have little or no immediate market. Even if the market still exists, the price Total Value could have been driven so low by the (millions "paper-drive" that the regular.used-paper Product Unit Value Of dollars) suppliers operate at a loss. Paper $0.899 per kg (short ton) 35 .75 Petroleum SO. 350 per 0.159 m 4.3.1 FREIGHT RATE POLICIES (barrel) 1,350 .00 Natural gas $0.022 per 28.3 m9 (103 ft3) 450 .00 While it is not currently possible to Iron ore $0.748 per 1016 kg demonstrate that the higher freight rates (long ton) 96 .64 cause an actual decrease in the amount of Coal $0.142 per 1016 kg secondary materials recycled, it can be (long ton) 80 .59 demonstrated- that certain secondary ma- Bauxite (used terials cost more to .ship than virgin for aluminum) $1.496 per ioie kg materials. A 1974 publication (ref. 4-2) ( long ton) 20 .96 of the EPA discusses the problem and Sand (used presents the following conclusions: for glass) $0.082 per 1016 kg (long ton) 0.86 Source:EPA Second Report to Congress (ref. 4-2) p.33 1. Freight rates are higher for some secondary materials such as rail These estimates point out the compet- rates for scrap iron, glass cullet, itive advantage enjoyed by the virgin mate- reclaimed rubber and ocean rates rials industries. for wastepaper. •2. Freight rates represent a sub- 4.3.3 FEDERAL POLICIES REGULATING NATURAL stantial fraction of the cost of GAS using many secondary materials. 3. . While there is some potential for The Federal Power commission regulates discrimination, there is no direct the transportation of natural gas in inter- evidence to indicate that higher state commerce as well as the sale in inter- freight rates"result in a reduc- state commerce of natural gas for resale tion of recycling. for ultimate public consumption for domestic, commercial, industrial or any other use, 4. Further study is needed to deter- and natural gas companies engaged in such mine the extent to which there is transportation or sale (ref. 43). Thus, if discrimination against secondary a pyrolysis plant produced a gas which was materials. to an electrical generating system which

171 'comes under the jurisdiction of the FPC, items at the household level. If source that pyrolysis plant might also be subject separation were practiced, front end to FPC regulations and be forced to price systems would be unnecessary, and resource its gas at an artifically low price, recovery would be much less expensive. (ref. 4-4) . This would naturally reduce the Second, consumers 'tend 'to avoid 'purchasing financial attractiveness of energy re- products made from nonvirgin material. A covery through pyrolysis. prime example of this is the reluctance to use table napkins made from recycled paper Even if the pyrolysis plant were not taken from garbage. under FPC jurisdiction, it could be forced to-sell its gas at a low price in order to compete with natural gas priced according PRODUCTS SUITABLE FOR CURRENT MARKETS to FPC regulations. For a number of years the FPC has set the price of natural gas shipped into interstate commerce at 32C/109 Resource recovery is recognized as an joules (34$ per million BTU's). Recently, important aspect of solid waste management this price was raised to 43C/109 joules and the recovery process can be structured (46C per million BTU's) on new produc- so that resources can'be recovered before, tion. Pyrolysis gas might be priced above during, or after the actual processing of the FPC ceiling and remain competitive. the solid waste. The nature of the products This is because demand for interstate recovered is dependent on the stage in the natural gas exceeds available supplies. process at which recovery takes place. Many industries may accept a higher priced Table 3-3 shows the typical composition of pyrolysis gas in place of the lower priced, MMR but it should be noted that many of but unavailable, natural gas. An addi- these materials cannot be marketed without tional competitive advantage of pyrolysis some type of processing. Many products gas is the possibility of contractually which are immediately.saleable are re- "guaranteed supply. If a shortage of covered before processing. natural gas occurs, FPC policy requires utilities to give priority to residen- ,tial customers and service to industrial 4,4,1 PRODUCT DESCRIPTION ^customers may be curtailed. Pyrolysis gas, as an interstate commodity, is not subject to this constraint. Although approximately a quarter of the tonnage of paper, major metals, glass, textiles and rubber consumed in recent 1,3,4 FEDERAL PROCUREMENT POLICIES years in the U. S. has been acquired through recycling operations, most of it has been salvaged from manufacturers and businesses, One of the largest problems to over- where large amounts of relatively clean and come in recycling is that of market un- homogeneous wastes accumulate. Very little certainty. Since the Federal Government is currently being salvaged from municipal is the single largest consumer of many refuse (ref. 4-5). products it has been suggested that Federal procurement of recycled materials The technical feasibility of recover-, could be used to establish a stable market ing various materials from the municipal for products manufactured from secondary waste stream has been well demonstrated in materials. This has been done with paper the past even though the reclamation of' products and automobile and truck tires. salvage material becomes more difficult The EPA has concluded, however, that while when it is mixed with garbage and other the Federal government is the single refuse. According to the EPA, (ref..4-6) largest consumer of many products it does " had currently-known technology not constitute, by itself, a sufficient been applied in 19.72 to residential demand to create a stable market for re- and commercial solid wastes in metro- cycled materials. State and local govern- politan areas, almost 14 million tons ments and other consumers must join the of steel, aluminum and glass could Federal government in,the effort.to create potentially have been, recovered and a market for recovered resources, substituted for their virgin material (ref. 4-2). counterparts". 4.4.1.1 FERROUS METALS ^ 4,3,5 SOCIAL ATTITUDES Ferrous metals account for roughly 7 percent of the municipal waste stream. The social attitudes of consumers After the large bulky items have been re- also have a great influence on the market- moved and after the rest of the incoming ability of recovered resources. These refuse has been shredded, the .ferrous attitudes, which are discussed in detail metal is usually extracted magenetically. in Chapter 2, are briefly summarized here. The first of these is reluctance of con- It is estimated that 60 to 80 percent sumers to undertake separation of disposable of the recoverable ferrous metals is in the

172 .form of steel" cans which are, in reality, a 4.4.1.3 GLASS composite of tin-plated steel and possibly lead, organic coatings and aluminum. The Glass makes up about 10 percent by composite can fraction contains approx- weight of municipal solid refuse. Glass ' imately 92 percent steel, 0,4 percent tin, scrap, which is called cullet, is a de- 1.5 percent lead, 3.7 percent aluminum and sirable input material for the glass 1.8 percent organic coatings. It is these industry because it liquefies at a lower nonferrous residuals that often make temperature than the other raw materials. "can scrap" a "bad scrap", The use of cullet in the glass industry (ref. 4-7). has the effect of reducing fuel consumption and air pollution emissions, and it helps to extend the life of fumance 4.4..1.2 .PAPER linings. Thus, the use of glass cullet can be economically advantageous and could reduce costs $2 to $3 per metric ton of input Paper, the largest single component (ref. 4-1). of municipal waste, is one of the most important manufactured materials in the Technology currently exists for extract- United States. Paper products can be ing and color-sorting glass from municipal classified into three broad categories; solid waste but it is not yet in large scale paper, paperboard, and construction paper. use. As part of a larger demonstration project in Franklin, Ohio, the EPA is inves- Waste paper, which can be used as tigating the feasibility of recovering glass a raw material in the same way as wood as a byproduct from an aluminum recovery pulp, is classified as either bulk or system. Preliminary results from this high grades. Bulk grades are used in project indicate that the expected economics sizeable quantities in paperboard and of the joint recovery of aluminum and glass construction products. High grades are is attractive, even after considering the high quality fibers which can be directly additional investment for color-sorting the substituted for woodpulp. About 80 per- recovered glass (ref. 4-1). cent of recycled waste paper falls into one.of three•bulk grades: 4.4.1.4 PLASTICS, RUBBER and OTHERS 1. news: .old newspapers recovered in residences Plastic is one of the most difficult 2. corrugated: .old corruguated materials to extract from municipal solid •boxes discarded in commercial waste, and no plastic recovery now takes establishments place from municipal solid waste. The heat content of plastics approximates that 3. mixed: unsorted papers of the of coal, and consequently plastics have lowest quality which is -generated great heating value in energy recovery in office buildup and printing systems. Unfortunately, burning plastics plants. in the presence of moisture produces hydrochloric acid vapors. These vapors High grade wastepaper is of two types; are very corrosive and pose an equipment pulp substitute and de-inked. Pulp substi- maintenance problem as well as an air tute consists of high quality fibers de- pollution problem. rived from paper-converting plants and tab cards from data-processing centers. De- Most of the rubber in mixed municipal inked wastepaper is usually bleachad paper refuse is either in the form of tires or recovered in printing plants. such products as soles and heels on foot- wear. Reclamation of rubber from mixed Two factors enter recovery of paper refuse appears impractical at this time, and paper products. First, approximately especially because of the technical seven-eights of all paper products can limitations in its recovery. For a more be recovered. Examples of unrecover- extensive discussion of problems and ables are library materials and tissue prospects for plastics and rubber tires, products in sewage systems. Second, see the discussion in Chapter 2. recycled paper is not as good as new after recycling. Each time that paper goes through a recycle, its fibers become 4.4.1.5 FUEL OIL and GAS shorter and more frayed. The result is a product that -has lesser use than the virgin product. Even if strength is . One of the most common products re- not a factor, color of the recycled sulting from a pyrolysis process is fuel paper could influence its use. Slick oil. The major marketing obstacle is the magazines yield as much ink and clay as reluctance of the petrochemical industry recovered fibers in a recycling process. to use gases or liquids produced by a The disposal problems of recycling can waste-disposal system as a feedstock. also be a problem. Discussions with representatives of the

173 petrochemical' industry indicate that pri- Materials recovered for recycling vately owned chemical companies are not are often relatively valuable but interested because of impurities and fluctu- only IF a market exists for the grade and quality of product derived ation in chemical composition. from the recovery system. s'ince there has not yet been a major" attempt to produce and market these products, This section examines the demand and dis-. this judgement is conjectural. It is also cusses source causes -for- low 'demand "for -•" worth noting that even if this conjecture some of the specific products. is correct, it does not rule out the sale of combustible liquids or gases to chemical companies for use as a fuel. 4.4.2.1 TIN CANS Table 4-2 shows a comparison of gases from two different processes and Table The three principal markets for 3-30 gives a comparison of no. 6 fuel oil salvaged tin cans are:- the detinning industry, the steel industry and the and typical pyrolytic oil. copper precipitation industry; the detinning industry could be considered an intermediate processor since it extracts the ' TABLE 4-2 tin from the cans and sells the ferrous GASEOUS FUEL ANALYSIS. scrap to the steel industry. The largest use of recovered cans today is for precipitation iron -in the copper precipita- • Gas Monsanto Garrett tion industry. As mentioned earlier, cans usually do not meet the quality scrap Nitrogen 69.3% — • ' requirements in either the 'detinning and steel industry. There are also constraints Carbon Dioxide 11.4% 27.0% on the use of tin cans in the precipitation process; the most important are: .'__•' Carbon Monoxide 6.6% 42.0% • 1 1. the increasing aluminum content Hydrogen 6.6% 10.5% • of the cans, which causes problems in the precipitation Methane 2.8% 5.9% process, and Oxygen 1.6% 2. 'the high shipping costs usually — required, since the mines are Ethylene 1.7% ' located in Arizona, Utah, — Montana, Nevada and New Mexico. Ethane — • : 4.5% The demand for iron in the copper C3 to Hydro- precipitation industry is expected to carbons 8.9% double over the next 15 years but this ' market is judged by the EPA to be of limited overall importance. (ref. 4-7). A 2 MARKET DEMAND Less than 4 percent of the copper ore in the U. S. is refined by the type of As noted earlier, viable markets and process which uses precipitation iron. market prices hold the economic key to the future of many of the suggested processes. The market for salvaged cans in the Darnay (ref. 4-1) observes: detinning industry has been limited by problems caused by contaminants, primarily The product quality of the re- aluminum. Although aluminum could be source recovery systems is dependent removed by further processing, this would upon the components of the municipal increase costs and would make aluminum , waste input/ and usually the products removal uneconomical for the detinning compete in the low-quality end of the industry. The detinning industry is not markets for which they are suitable. a large one and currently processes a This is a key factor that must be neglible quantity of salvaged cans; more .- considered in looking at economic of these cans could be absorbed by the viability of recovery process. present demand were they available from However, each product of the re- municipalities. source recovery processes has a unique relationship to its poten- Steelmaking is yet another potential tial market considering its use for tin cans. The greatest difficulty quality. For example, electricity • with the use of tin cans in steelmaking can be a relatively valuable is their tin, aluminum and lead residuals; energy product in some situa- these contaminants can cause damage to the tions but has very marginal com- refractory lining of the meling furnace. mercial values in others. With the advent of electric furnaces in

174 the steel industry, greater quantities of Recovery of paper stock from mixed recycled cans will be used because of the municipal refuse is currently practiced electric furnaces' capability of produ- to a small extent, and is mostly done by cing steel from a charge of 98 percent hand sorting at the processing plant. It scrap. Detinned steel scrap can be is estimated that between 1/2 to 3/4 metric used in steelmaking since the detinning tons per hour can be hand sorted by one process removes contaminants and im- man; thus separation time is on the order proves the .quality of the steel. of 1.3 to 2 man-hours per metric ton (ref. 4-11). 4.4.2.2 PAPER Wastepaper is generally marketed through paper brokers. As shown in section 4.4.3, the prices that brokers are Table 4-3 illustrates how wastepaper willing to pay vary greatly in both geo- was utilized in 1970 in the manufacture of graphical location and time. paper. Approximately 40 percent of the paper recycled today is acquired from paper converters .while about 60 percent 4.4.2.3 GLASS is .recovered from residential and commercial sources. As might be expected, corrugated and mixed bulk comes mostly Table 4-5 shows how the use of nonre- from commercial sources with residences turnable glass containers has increased in providing over 80 percent of the news or recent years. This has a very significant bulk waste paper grade (ref. 4-1). effect on the amount of glass that eventually will find its way to the solid- Although there are some mechanical waste stream. Even with this significant processing systems capable of recovering increase in production. Table 4-6 shows wastepaper from mixed municipal refuse, that cullet consumption has been very very little paper recovery takes place slight. using such systems'. These systems are still undergoing tests and require fur- There are several constraints on the ther development before they can be prac- use of cullet in the glass industry which tically used. could help explain the low fraction of purchased cullet in the above table. Even though wastepaper recycling of old newspapers, corrugated paper and of- 1. Cullet must be clean and free fice paper.was 6.7 million metric tons of metallic contaminants, es- in 1970 (ref. 4-7) it is estimated that pecially aluminum and iron. recycling of these bulk grades could be greatly improved, especially within the 2. Cullet must be crushed into large urban centers as indicated in pieces of size 1 inch or Table 4-4.

TABLE 4-3 WASTEPAPER UTILIZATION IN PAPER AND PAPERBOARD

Type of waste consumed Total U . S • Total Type of paper paper wastepaper Pulp substitutes Mixed Corrugated production consumption Newspaper and high-grade paper paper de inked paper

Total for all grades and molded pulp (103 tons) 53,329 12,021 2,639 2 , 238 4,080 3,067 Total paper (103 tons) : 23,409 2,228 33 455 108 1,632 Newsprint 3,345 371 371 .' Printing, writing, and related 11,023 736 — . 73—6 — Tissue 3,595 971 7 —76 , 69 819 Other 5,446 • 150 26 8 39 77 Total paperboard (103 tons) : 25,465 8,330 1,766 1,473 . 3,779 1,312 Unbleached kxraft and solid bleached 15,036 285 48 8 162 67 Semi chemical 3,460 754 42 28 622 62 Combination 6,969 7,291 1,676 1,437 2,995 1,183 Construction paper and board, molded pulp, and other (103 tons) : 4,455 1,463 840 307 193 123 Distribution (percent) 100.0 22.0 18.6 33.9 25.5 —

175 TABLE 4-4 WASTEPAPER AVAILABILITY (RECOVERABLE GRADES, 1970)

Paper (103 tons) - * Recoverable Maximum (75 Minimum (30 percent of percent of that that Additional Discarded to Generated generated generated increment Type of paper Consumed waste stream Recovered in SMSA's in SMSA's in SMSA's recoverable Newspaper 9.8 9.7 2.2 7.4 5.5 3.7 1.5- 3 .3 (22.4 percent) Corrugated 13.3 13 .2 2.6 . 10.0 7.5 5.0 2.4- 4 .9 (20.0 percent) Mixed and high grade (primary office papers) 11.1 9.1 2.6 8.3 6.2 4.2 1.6- 3 .6 (23.6 percent) Total 34.2 32 .0 7.4 25 .7 19 .2 12 .9 5.5-11.8

smaller, and must be color aluminum recovery system which has not sorted (flint, amber, or yet been fully demonstrated. green). The establishment of many can-recla- Although residential waste glass is mation centers throughout the country, fairly clean, it is often contaminated and coupled with the high prices currently mixed with other waste thus making it being paid for this metal scrap explains more difficult to recover; this plus the why aluminum recovery is being considered fact that.it must be color sorted severe- in most of the recovery systems currently ly inhibits the recycled glass market. under development. Scrap processors in this country still handled approximately Summarizing, then, clean and color- 70 percent of the aluminum scrap sold in sorted scrap glass is a valuable and de- 1970 (ref. 4-12). sirable raw material for the glass industry, and because of the potential demand for this type of cullet, it is MARKET PRICES a marketable product. At present, though, the available recovery technology for glass from solid waste is Prices which can be obtained for most not sufficiently developed to make re- secondary products are extremely variable. covery of clean and color-sorted glass Since the production of garbage is a large economically desirable. continuous and on-going process, the solid- waste disposal industry cannot respond quickly enough, nor store its commodity 4.4.2.4 ALUMINUM long enough to take advantage of optimum price levels. Without government support, it must make guaranteed long-term contracts Most large aluminum companies in to stay competitive. Current market prices this country are now involved in aluminum are discussed with respect to specific can recycling, and have sponsored a num- products. ber of aluminum recycling centers and recovery programs. These recovery programs have been mostly based on voluntary citi- 4.4.3.1 PAPER PRODUCTS zen collection and delivery to a specific site. Although there is, as of this moment, no well developed process for re- Prices for wastepaper are very time claiming aluminum from the municipal and location dependent. Wastepaper prices waste, the EPA is investigating (in the fluctuate widely and operating in this mar- EPA-sponsored Franklin, Ohio project) an ket requires skill and knowledge of the

176 TABLE 4-5 BEER AND SOFT DRINK F:ILLINGS AND CONTAINER CONSUMPTION, I/O IN MILLION UNITS (Ref. 4-1)

1967 1968 1969 1970

Soft drink: Glass closures 32,715 31,046 36,133 35,349 Metal cans 7,290 10,028 11,764 12,856 Glass container shipments: Returnable 1,913 1,747 1,640 1,603 Nonreturn able 3,586 4,644 6,457 8,360 Total fillings 40,005 41,074 47,897 48,205

Market share % : Metal cans 18.2 24.4 24.5 26.6 Returnable bottlesi 72.8 64.3 62.0 56.1 Nonreturnable bottles 9.0 11.3 13.5 17.3

Avg. no. trips, returnable bottles 16 15 14 n.a.

Beer: Glass closures 17,003 16,092 17,834 17,747 Metal cans 13,769 15,342 16,708 18,864 Glass container shipments: Returnable bottles 624 475 480 350 Nonreturnable 5,784 5,985 6,876 7,248 Total fillings 30,772 31,434 34,542 36,611

Market share% : Metal cans 44.7 48.8 48.4 51.5 Returnable bottles 36.5 32.2 31.7 28.7 Nonreturnable bottles 18.8 19.0 19.9 19.8

Avg. no. trips, returnable bottles 19 20 20 n.a.

TABLE 4-6 GLASS PRODUCTION AND PURCHASED GULLET CONSUMPTION, 1967

(See Ref. 4-1) Purchased cullet Production consumption Purchased Industry segment in 1,000 tons in 1,000 tons cullet, percent Containers 8,950 100 1.1 Flat glass 2,150 244 11.3 Pressed and blown 1,720 256 14.9 Total 12,820 600 4.7

. 177 relationships between demand, prices and to continue rising and additional credits inventories. In 1967 in New York, for may be realized from the sile of aluminum example, clean bulk newsprint commanded recovered from municipal waste. prices of §16-$17 per metric ton ($15- $16 per ton) (ref. 4-11), while the same item in Los Angeles, five years later, 4.4.3.4 GAS AND FUEL OIL was $14 per metric ton ($13 per ton), and $30 per metric ton ($27 per ton) in the Philadelphia area. The 1972 average U. Another contributing factor to the S. price for clean bulk newsprint was on large price variations is the difference the order of $22 per metric ton ($20 per in composition of recovered products that ton). Prices for clean newsprint in 1974 the different processes produce. For ex- in the Houston area have been on the or- ample, gas compositions vary in attractive- der of $33-$44 per metric ton ($30-$40 ness to potential customers (see Table 4-2). per ton) although in recent months prices have dropped to $4.4 per metric ton ($4 Typical natural gas prices for various per ton). In fact, at this market low locations are present in Table 4-7. (in Houston), purchases of any kind were only from those suppliers who had established themselves as dependable future TABLE 4-7 sources. Minimum guaranteed prices of VARIATION OF NATURAL GAS PRICES about $27 per metric ton ($25 per ton) have been reported in the west coast area in long term contracts. Current Location $/2.83 x 103m3 cardboard prices in the Houston area are ($/l,000 ft8)* in the range of $22-$33 per metric ton ($20-$30 per ton). Houston $ .25 Denver .29 4.4.3.2 GLASS Minneapolis .46 The basic raw materials for the manu- Seattle .44 facturing of glass containers cost between $16 and $20 per metric ton of glass pro- Washington, D.C. 1.06 duced. Since the substitution of cullet saves processing plants $2 - $3 per metric New York .87 ton of input, cullet can sell for $18 - $23 per metric ton and still be competi- *1000 cu. ft. contains approximately 106 Btu tive with virgin raw materials (ref. 4-12). According to Anchor Hocking in Houston, the current price paid for clean, color- sorted glass in this area is about $20 These prices have increased substan- per metric ton. tially in recent months. As in the case of all secondary pro- As of August, 1974, the price in Hous- ducts, the economics of glass recovery ton has risen to $.32/10* Joules ($.34/106 from solid waste is very much dependent Btu) while the price in the northeastern on the proximity of the markets. The part of the country, specifically Connec- prices quoted earlier are net prices at ticut, has risen to $2.12/109 Joules ($2.40/ the site, and thus transportation costs 10s Btu)-1 must also be taken into account when considering the economics of glass .re- Purchasers will have to assess the covery . suitability of the pyrolysis oil to arrive at a price they are willing to pay. In the case of the Garrett oil, one of the 4.4.3.3 main considerations is the high viscosity of the oil. It is anticipated that prices for this oil may range from 2$ per liter Since most recoverable aluminum from" ($3.00 per barrel) to a possible high of solid waste is in the form of cans, it is 6* per liter ($10.00 per barrel) in special reasonable to use the prices paid at vol- situations. untary redemption centers as the price for.aluminum scrap; in 1972 this price was $181 per metric ton (ref. 4-12). In 4.4.3.5 FERROUS METAL August, 1974, aluminum reclamation centers in Houston were paying 33C/kilogram (30C/pound) for aluminum cans, or $272 The copper precipitation industry pays per metric ton - fob at the reclamation center. This gives some indication of 'Telephone conversation with Ken how time dependent these prices can be. Rodgers of Combustion Equipment Associates, However, aluminum prices are expected August 6, 1974.

178 the highest price for ferrous metals, Various potential markets for spe- on the order of $50 to $65 per 907 kilo- cific chemicals exist. The ability to gram ($50 to $65 per ton) at the mine take advantage of some of these markets with a maximum of $75 per 9-07 kilogram will depend on the need of local industries. ($75 per ton) (ref. 4-11). This high Other markets, however, are tied to the price is explained by the fact that the needs of the municipalities. The use of demand is far from the large urban cen- CC>2 in the tertiary treatment of sewage is ters which are the places where "produc- a good example of municipal usage. tion" of the ferrous metal scrap is concentrated. Most of the mines are lo- A fuel derived from MMR may be utilized cated in various points in Arizona, Mon- by electric utilities which can either use tana, Nevada, and Utah. Freight charges the fuel directly or use steam generated from urban areas to these places are at the disposal plant. The possibility of quite high, and this accounts for an supplying steam to a district heating net- important part of the total cost of the work also exists. An important considera- scrap metal at the mine. tion when selling steam is the distance the steam must be piped. Low energy con- Recovered ferrous cans which.cannot tent can place severe limitations on this be economically transported to copper distance. mines may find a market as No. 2 bundle scrap (ref. 4-12), or as a feedstock to A major impediment to the direct the detinning industry. According to • marketing of the fuel gases produced by Iron Age, the composite average price many pyrolysis processes is their low Btu paid in 1972 for No. 2 bundles in Pit- content. In the case of the liquid fuel tsburgh, Chicago, and Philadelphia was produced by the Garrett process, a major $25.46 per 907 kilogram ($25.46 per ton) drawback is its high viscosity and poten- (ref. 4-14). The detinning industry tially corrosive nature which can greatly paid, in 1967, an average of $21.59 per • increase its handling expense. 907 kilogram ($21.59 per ton) for tin plated scrap delivered at their plants A potential market for the carbon char tref. 4-1). produced by pyrolysis disposal is in waste water treatment, where it can be substituted for commercial activated carbon. 4,5 POTENTIALLY PROMISING MARKETS With respect to the vitrious frit which is frequently a pyrolysis residue, the most promising market appears to be in the pro- In addition to industrial demand, duction of asphalt. other factors play a role in secondary material markets. The secondary materials industry is inadequately capi- 4.6 MARKETS TO BE DEVELOPED talized and poorly organized. An. in- flux of new capital technology, and managerial skills is needed to improve the There are two basic approaches to mar- productivity of the secondary materials keting products: industry. (1) try to capture a share of As discussed in Chapter 2, many exisiting markets from simi- federal tax and transportation rate poli- lar type products, or. cies work to the disadvantage of secondary material dealers. Changes in these po- (2) create a need for an available licies are long overdue, and would have product where none currently an"important revitalizing influence on exists. the entire industry. Finally, procurement policies at all levels of govern- The gas and oils produced from the ment which give preferential treatment pyrolytic process, for instance, are pro- to products utilizing secondary mate- ducts which must compete for a share of the rials would help to stabilize secondary energy market. On the other hand, research materials markets and promote resource conducted at the University of Missouri at recovery. These factors should facili- Rolla indicates that a market might be de- tate a more positive cycle where stable veloped for recycled glass in the produc- demand encourages the kind of investment tion of glasphalt. in resource recovery which will ensure a stable supply of secondary material. The There are numerous marketing problems general availability of supplies of secon- to be solved in both methods if a success- dary materials will in turn encourage new ful solution is expected in the solid waste industrial utilization of these resources. handling problem. As implied many times in this report, most products are of marginal economic 4,6,1 RESEARCH AND DEVELOPMENT value but much can be done to improve this situation. Some specific examples are given below. Research is needed to help in making

179 and marketing products that result from permitted in dumping, incineration, and solid waste systems. Some possibilities sanitary landfills. As a result, the are briefly discussed below. cost of these alternatives remained low. Land for dumps and landfills has been Research on recycled glass has al- easily available, and the cost of trans- ready been mentioned and some of the more porting refuse to these locations has not promising secondary products which use been .excessive compared to the cost of scrap glass are slurry seal street.pa- available alternatives. With the enor- ving (ref. 4-15), glasphalt (ref. 4-16), mous growth of urban centers however, new bricks (ref. 4-17), insulated wall disposal sites have become difficult to panels (ref. 4-18), glass rubble buil- find. Land costs have increased and avail- ding panels, glass wool, terrazzo type able sites are more distant from the waste flooring (ref. 4-19), foamed glass buil- source. This has been compounded by in- ding materials (ref. 4-20), ceramic creased transportation costs. To control building tiles (ref. 4-21), cement and the costs of traditional disposal methods concrete (ref. 4-22) . certain reforms have been implemented. An example is the creation of transfer sta- One manufacturer has developed a tions- in many large urban centers. More process for making high tolerance bricks important, however, is the fact that ri- which can use almost any reasonable ag- sing .costs have.forced local governments gregate, including glass.recovered be- to search for new solutions to the waste- fore or after an energy conversion pro- disposal problem. cess, frit, residue, slag stone and residue dirt (ref. 4-23). These bricks are Public pressure to alleviate some of more costly to make, but since they are the environmental liabilities of current high tolerance, the added manufacturing methods of solid waste disposal has forced cost is more than offset by labor saving research in new methods. Governmental agen- in laying the bricks. They can be laid cies at all levels have also become in- viith a glue rather than mortar. This creasingly aware of the negative environ- takes less labor, less time, less skill, mental aspects, of incineration, open dump- and it creates a stronger wall because ing, and sanitary landfilling. All of this tne mortar, which is. the weakest part has resulted in new laws and increased pres- of a brick wall, is replaced by a stron- sure for government to seek better solutions ger adhesive. to the problem of waste disposal. Insulated wall panels and glass In summary, alternatives to dumping rubble building panels, might use from and incineration were not considered in the 13 - 94 percent reclaimed glass and past because: demolition rubble including scrap brick and stone. Mineral wool insulation now 1. Land for disposal sites was uses up to one percent reclaimed glass. . . cheap.and easy to find. This could be increased to about 50 percent to make a glass wool insulation. 2. Transportation distances for , hauling refuse to incinera-.. It is possible to make terrazzo type tion, open dumps or landfills flooring using'reclaimed glass rather were relatively short. than marble chips and research is being conducted in this area. 3. There was little pressure from the public for legisla- Finally, research on scrap plastics tive regulation to pollution (refs. 4-24, 4-25, 4-26), fibers and and environmental quality. humus recovered from solid waste may develop saleable products which can be This situation has changed and we now made from materials recovered from so- find ourselves with a variety of new ap- lid 'waste. proaches to the solid-waste disposal problem. These are in various stages of development, testing and implementation. At 4,7 TRENDS AND DEVELOPMENTS present many private companies are trying to sell municipal waste conversion 'systems to cities. The economic success of most of Before discussing what the future these conversion systems depends on the sale holds for markets and utilization, let us of a mix of products, byproducts and energy. first note the conditions and events re- The success of most of the conversion sys- sponsible for our present situation. Up tems available in the market today will to the present, solid waste disposal has also be affected by any future legislative consisted of either open dumping, sanitary restrictions. landfilling, or crude incineration. The primary virtue of these disposal methods is their apparent low cost. ,7,1 SOME RECENT TRENDS Until recently, laws have been quite flexible as to the pollution levels Previous;sections of this .report have

180 shown approximate net costs per metric Most, if not all, of the conversion ton for various conversion processes. processes currently available have net In locations where landfilling or in- costs per metric ton.which are very sensi- cineration are very economical as well tive to the credits received from energy as feasible, some of the new conversion production and recovered materials. There processes may not compete favorably. is no doubt, after looking at Figures'4-1 There are areas however, where, due to and 4-2 (both with the same scale) that '* local, state or Federal laws, the tra- the coal and iron price curves in Figure ; ditional approaches are not feasible, 4-2 have much steeper slopes than equip- and other areas where they may be feas- ment and labor cost curves in Figure 4-1. ible but extremely costly. In these The price of coal has been recently in- instances it may be less expensive to creasing at an extremely rapid rate. All use one of the processes discussed in available evidence indicates that the pri- Chapter 3. These processes have not yet ces of most fuels will be increasing received wide acceptance because the an- sharply in the years ahead. ticipated revenue from.the sale of recovered energy and.materials is not sufficient to make the.net cost per metric ton competitive with existing disposal methods. This picture is changing rapidly for two reasons: PRICES OF COAL, AND IRON 8 STEEL: RECENT TRENDS 1. The market for most energy 200 products and recyclable 190 materials is becoming more 180 attractive, and 170 e IRON S STEEL ISO o COAL 2. Laws and policies by lo- 150 cal, state and Federal gov- 140 . ernments are making energy 130 and resource recovery more 120 attractive. 110 While it is true that most commodity 100 .and service prices are increasing, not 90 all are increasing at the same rate. For 1969 1968.1969 1970 1971 1972 example, labor and equipment both constitute a major fraction of the capital and "SOURCE'. STATISTICAL ABSTRACT OF THE U.S., I9TJ operating costs of almost all energy and resource recovery systems. Figure 4-1 shows how the costs of equipment and la- FIGURE 4-2 bor have been recently changing. As PRICES OF COAL, AND IRON AND STEELJ seen in Eigure 4-1, costs for labor and RECENT TRENDS equipment are increasing} costs of equipment and machinery, however, have shown a greater increase than labor costs. It was pointed out in Chapter 3 that of all conversion processes studied in this, report, the supplementary fuel method seems to hold the greatest promise since it is highly competitive with all 200 known and existing waste disposal methods. 190 In the supplementary fuel process, the net ISO e AVERAGE WEEKLY EARNINGS IN 1967 DOLLARS cost per ton is highly sensitive to the 170 IN PRIVATE MANUFACTURING INDUSTRIES credit received by burning prepared re- a WHOLESALE PRICE INDEX FOR EQUIPMENT fuse as fuel. In most oases the value per 160 AND MACHINERY ISO million BTU of prepared refuse will approxi- MO mate that of coal. ISO If the prices of coal, iron and steel, 120 together with those of labor and equipment . 110 continue changing according to a. pattern no similar to that of recent years, many re- 90 fuse conversion processes will become competitive with landfill and other traditional I96S 1968 1969 1970 1971 1972 disposal approaches. . Other important developments will also SOURCE: STATISTICAL ABSTRACTS OF THE US., 1973 encourage the recycling of secondary materials and the recovery of energy from FIGURE 4-1 solid waste; this will in turn make their COSTS OF LABOR AND EQUIPMENT,1 markets much more attractive than what they RECENT TRENDS are at present. The more important of these developments are: 181 1. National policy, as expressed bind itself; 5 years is a common li- in the Solid Waste Disposal mit. Act of 1965, is to encourage recycling 'and to promote the effective |"utilization" of 4,7,3 MARKET LOCATIONS solid waste.

2. Pending legislation points The economic viability of incinera- '• to more and-better use of tion or pyrolysis is dependent upon the the available -resources in availability of local markets. Since the municipal waste stream. many of the outputs from municipal solid- \ '. waste systems are of low quality, they 3. Costs of traditional waste are only marginally attractive, even when disposal approaches will con- transportation distances are small. When tinue to increase sharply. markets are distant, the economic benefits disappear because the transportation costs 4. "New technology-will-'improve begin to override any possible monetary the feasibility of recovering gain. • ••: energy and materials from * -municipal solid waste. 4,8 CONCLUSION 5. Research and development is creating new products which • can be made- from materials At the present time there is no re- recovered from solid waste. liable market for many products produced from solid waste (ref. 4-27). However, future developments may lead to improved 4.7,2 CONTRACT AGREEMENTS markets for such products. For example, energy prices have increased in the past few years and substantial evidence exists • Long-term contracts are an integral to indicate that they will continue to part of solid-waste disposal systems. increase as the world demand for energy Since all of the processes are capital increases. Research and development for intensive, long-term contracts are essen- new products utilizing solid waste, ma- •tial, riot only to keep the operation eco- terials is presently being conducted and nomical, but in order to obtain financing encouraged by Federal government grants.' as well. Of course, long-term contracts Proposed legislation in the form of the can be detrimental if they are not care- Hazardous Waste Disposal Act (ref. 2-28) •fully negotiated. 'Resource Recovery, and increasing landfill costs, may make * -Inc.-in Houston has a 20 year contract landfills impossible in many cities. to sell-scrap metal for $20/ton. It is This should encourage trends toward energy likely that if this same contract were ne- and resource recovery. Additional legis- gotiated today a price of $30/ton could lative proposals are being formulated to be obtained. With increasing scarcity of study the effects of federal policies such resources, this upward trend is likely to as freight rate and tax incentives for continue. virgin materials on the secondary materials markets. If legislation is forthcoming to The~ classic -example 'of a need to find provide .tax incentives for secondary ma- adequate markets and secure contracts is terials recovery, this should encourage the the Chicago Northwest Incinerator. It development of.markets. Legislation on air currently produces 'steam, but the steam standards for incinerators is closing this is not used, and, therefore no revenue option for many cities and encouraging re- credits can be taken for this energy. At source recovery systems. ' ,: present, the steam is condensed and dumped into Lake Michigan.- "" .. . The following suggestions concerning markets are made to any municipality con- At the other end of the spectrum, the sidering an energy and resource recovery Baltimore Gas & Electric Co. has agreed to plant. buy all the steam produced by the Balti- more Landgard system. • Furthermore, under 1. Location of the plant should be the terms of the contract, the price re- close to the energy product use, and, if ceived increases 'as. 'the price -of oil goes possible, close to purchasers of other re- up. This arrangement' has proven bene- covered materials. ficial to buyer and seller -'alike. 2. Location of the energy conversion ' A possible limitation is the restric- plant should also be related to the MMR tion of the contractual powers of muni- source to minimize transportation charges cipalities. As discussed in Chapter 2, for collection. A,- many cities have restrictions in their charters setting a limit on the maximum 3. Long-term estimates should be made number of years the city can contractually concerning local markets for as many as

182 possible of the materials to be re- Finney presented to American Insti- covered. Long-term contracts are often tute of Chemical Engineers 73rd Na- possible. tional Meeting, August, 1972. 4. Larger municipal areas might 4-11 Drobny, N. L.; Hall, H. E.; and Tes- investigate the possibility of encour- kin, R. P.: Recovery and Utilization aging the manufacturing of products of Municipal Solid Waste, Report SW- which utilize materials recovered from 10c prepared for the Environmental solid waste. . This would-help create Protection Agency Solid Waste Manage- markets for the recycled materials. ment Office by Battelle Memorial In- stitute, Columbus Laboratories, 1971. 5. Municipalities should con- 'sider themselves as a potential market 4-12 Materials Recovery Systems: An En- for the energy and secondary resources gineering Feasibility Study by the recovered from MMR. National Center for Resource Recovery, .Inc., Washington, D.C. December 1972. • SELECTED REFERENCES 4-13 Solid Waate as an Energy Source, Re- port No. D2-118534-1 by Boeing Aero- space Co., Houston, Texas, February 4- 1 Darnay, Arsen; and Franklin, Wil- 1974. ham E.; Salvage markets for materials in solid wastes; Report 4-14 Iron Age, January 4, 1973, Volume 211. prepared for the Environmental Protection Agency, Solid Waste 4-15 Road to Future Paved with Garbage. Management Program by Midwest Re- Machine Design, Vol. 43, November 1971, search Institute, Report SW-29c, p. 40. 1972. 4-16 Unrefined Waste Glass Seen O.K. for 4- 2 Staff of Environmental Protection Glasphalt. Publication Works, Vol. Agency: Second Report to Con- 104, January 1973, p. 104. gress, Resource Recovery and Source Reduction. (SW-122), Washington, 4-17 Anon.: Bricks from Recycled Wastes D.C., 1974. Used in Home Construction. American Concrete Institute Journal, Vol. 69, 4- 3 Section l(b), Natural Gas Act, August 1972, p. 14. 1938, as amended. 4-18 Anon.: The Commercial Potentials of 4- 4 FPC vs Florida Power & Light Co. Glass Wool Insulation. The National 404 U. S. 453, Jan. 12, 1972. Research.Institute; published by The Glass Container Manufacturers 4- 5 Solid Waste Management Series Pub- Institute, Inc., Washington D.C. lication, U. S. Environmental Pro- tection Agency: Recycling and the 4-19 Anon: The Commercial Potential of. Consumer, Report 8SW-117, 1974. Terrazzo with Glass Aggregate. The ' Midwest Research Institute; published 4- 6 Lowe, Robert A.: Energy Conver- by The Glass Container Manufacturers sion Through Improved Solid Waste Institute, Inc., Washington D.C. Management, Report SW-36d. ii, U. S. Environmental Protection 4-20 Anon: The Commercial Potential of Agency, 1973. Foamed Glass Construction Materials made with Waste Glass and.Animal 4- 7 Solid Waste Management Publication, Excreta. The Midwest Research In- . U. S. Environmental Protection stitute; published by The Glass Con- Agency: Second Report to Congress, tainer Manufacturers Institute, Inc., Resource Recovery and Source Reduc- Washington, D.C. tion, Report #SW-122, 1974. 4-21 Anon: The Commercial Potential of 4- 8 Supplied by Mr. E. A. Stewart, Mana- Ceramic Tile made with Waste Glass ger, Landyard Systems, Monsanto En- and Animal Excreta. The Midwest Re- viro-Chem Systems, Inc., St. Louis, search Institute; published by The Missouri. Glass Container Manufacturers Insti- tute, Inc., Washington, D.c. 4- 9 New Techniques in the Pyrolysis of Solid Wastes by G. Mallan & C. 4-22 W. Gutt: Aggregates from Waste Ma- Finney of Garrett Research & Develop- terials, Chemistry-and Industry, ment Co., Paper presented to Ameri- June 3, 1972, pp. 439-447. can Institute p-f Chemical Engineers, 73rd National Meeting, August 1972. 4-23 Anon: New Process*Turns Wastes into Bricks, Chemical and Engineering 4-10 New Techniques in the Pyrolysis of News, Vol. 49, September 13, 1971, Solid Wastes by G. Mallan & C. pp. 49-50. 183 4-24 B. Baum; and C. H. Parker: "Future of Plastic Disposal," Society of Petroleum Engineers -Journal, Vol. 29, May 1973, pp. 41-45.

4-25 D. R. Paul; and others: "Potential for Refuse of Plastics Recovered from Solid Wastes," Polymer Engineering & Science, Vol. 12, May 1972, pp. 157-166. 4-26 Japan 1971: .Coping With a Down- turn, Plastics, Vol. 49, January 1972, pp. 66-68. 4-27 Arsen Darnay: "Recycling Assessment and Prospects for Success," U. S. Environmental Protection Agency, 1972. 4-28 U. S. Environmental Protection Agency, "Report to Congress, Disposal of Hazardous Wastes," (SW-115), Washington, D. C., 1974.

184 Chapter 5 A Decision Procedure

INCINERATION? Page Intentionally Left Blank 5,1 INTRODUCTION TO DECISION PROCEDURE accounted for, however. This is the problem of markets.. Many cities, dissatisfied 5,1,1 JUSTIFICATION with landfills and incineration turned to composting as a socially and environment- A brief examination of the history of ally acceptable alternative. In 1972, 18 solid-waste disposal practices illustrates plants were reported in the United States the need for an interdisciplinary approach (Glysson, ref. 5-1). However, only two to decision making in this area. were reported operating at that time. When the compost market disappeared, most Until the 1960's, most communities, of the operations were no longer economic- using only a least cost criterion for waste ally viable. disposal, practiced ooen dumping. About 80-85 percent of the country7s waste went The conclusion from this brief his- into unsanitary open dumps (Glysson, ref. torical sketch is that regions still con- 5-1). Enough people, environmentally concerned with cost must now integrate into cerned in the 1960's, encouraged legislation their decision process social, political, prohibiting open dumps. Examples of such environmetal, legal, and market considera- laws are Michigan Public Law 87 (1965) and tions . the Texas Refuse Dumping Law (1963). Fed- eral policy promoting the closing of open There is evidence today that communi- dumps, i.e., Mission 5000 in the 1960's, ties are becoming aware of the need for an also motivated better land disposal methods- interdisciplinary approach to solid waste sanitary landfills. decision making. Many communities then turned to either Along these lines, a rather unique incineration to reduce the amount of resi- seminar was held for consulting engineers due going to a landfill or used the sanitary in Buffalo, New York, during June, 1974. landfill alone. However, as soon as the The following quote is from the introductory incinerators were built many were shut down address by Gordon Eastwood who is respon- because they could not economically meet sible for Solid Waste Management Programs particulate and gaseous emission standards in New York State. It illustrates the set forth in the Federal Clean Air Act of growing sensitivity of public officials to 1965. the need for broad input into solid waste disposal decisions. In the late 1960's, then, communities were faced with not only economic but also "... we will address such issues environmental and legal constraints when as market, legal, administrative, deciding where to dispose of municipal financing, contractual, site loca- waste. tion, municipal vs. private ownership, economics, feed stock guaran- Also, to compound the difficulty for tees, legislative and others which municipal officials there arose problems hinder implementation of resource with sanitary landfills. These problems recovery programs. -The consulting were not economic or environmental but so- engineer has worked closely with cial and political in nature. As local municipalities and their agents in areas sought more landfill sites people planning and implementing many nearby protested. When officials of Monroe environmental programs. This ef- County, New York, sought places to landfill fort should continue. However, the garbage of Rochester, no other town in present approaches to solid waste the county would accept the waste (Glysson, management strongly suggest that ref. 5-1, cross, ref. 5-2). Cases of this these firms evaluate their resource problem can be found almost daily in local recovery staffing to consider and newspapers. For example, citizens of Lime- include other talents than the stone County, Texas, prevented very recent- professional engineer." (ref. 5-5) ly the location of an industrial landfill in their area (ref. 5-3). 5,1,2 PHILOSOPHY Another example of landfill problems Many communities have considered the is the controversy between the city of Grand difficult history of incineration, land- Rapids, Michigan and Kent County (ref. 5-4). fill, and composting solutions, and are The dispute is over who should pay transpor- moving toward solutions which maximize tation costs which exceeded contract figures resource and energy recovery - the focus when the city's refuse was trucked to a of this report. A study of the Rochester, county landfill. This 13 a political and New York, waste disposal problem by a legal problem. volunteer group.from the Rochester Engineer- ing Society contains the following quote: Political and social acceptability must then be added to economic and environmental "The Environmental Management concerns in order to make successful solid Council believes that there is only waste disposal decisions. one long range solution that is environmentally acceptable and that Yet another consideration must be solution'is based upon recycling.

187 Landfill is not an acceptable together as preliminary selection criteria long-range solution ..." to screen all technical options avail- (ref. 5-6) able. This process should yield options feasible for the community. For example, This approach is now being implemented a locale that decides to allow no emissions, . in.Monroe County after an extensive mar- however benign, into the air will elimi- ket survey related to end use of recovered nate from detailed consideration .any such ..materials including refuse fuel for a processes that produce emissions. As local utility boiler (ref. 5-7). The basic another example, the absence of a fiber point is that any solution considering board market may eliminate other processes resource or energy recovery must consider in the early screening phase. viable markets. This preliminary screening process Along with market data a full analysis reduces the number of technical options to must be made of the local social and poli- those compatible with the community. These tical climate-. Good planning will hope- in turn are evaluated in more detail. Eco- fully avoid citizen and institutional nomic analyses and desirability evaluation resistance to solutions. techniques are then used to see which option of those feasible best fits the heeds The philosophy of the following de- of the community. cision process is simply that the decision maker must consider markets and social data : This information is then given to the and only then consider technical options final decision makers - a city council, for compatibility. (This does not imply county commission, waste disposal authority that social and market data cannot be or legislature for their use in making a reconsidered in light of the subsequent final selection. . technical option analysis.) The tendency in the past has been to take a current The procedure given below is designed technical option and try to "shoehorn" it to help local officials account for all the into the community. In short, the techni- important dimensions of the solid waste cal options for solid waste disposal should problem in making successful decisions. fit the community not vice versa. The process is an attempt to integrate material in previous chapters relating to 5,1,3 OUTLINE OF PROCEDURE social .data, technical options, and market information into a procedure useful to lo- The following sections give in detail cal communities. the steps of the proposed decision process to be carried out by local officials or 5,2 DEVELOPMENT OF SELECTION CRITERIA their agents. A brief introductory outline is given here. 5.2.1 INTRODUCTION A schematic outline of the process is This section presents first of all a ,,given in Figure 5-1. (A more detailed dia- discussion of the more important factors gram is Figure 5-2 in section 5.4.) to be considered by decision makers when deciding upon a local disposal method. The discussion ends with an outline of factors PHYSICAL a TIO4- POLITICAL MAJJJJT. '"Kff \ INVIftONMSNTftL I MCAL DATA for the convenience of the reader. These factors may be used in the preliminary 1 1 screening process (section 5.3) and in the PNILIMINARY ilLICTION CKITENU j more detailed analysis of the systems still under consideration after the screening process (section 5.4). 5.2.2 ECONOMIC AND COST RELATED CHARACTERISTICS The following is a discussion of characteristics which relate to economics directly or indire.ctly. These character- FIGURE 5-1 istics can be used in forming selection BLOCK DIAGRAM OF DECISION PROCESS criteria. The four blocks across the top emphasize the data collection areas related to waste 5.2.2.1 CAPITAL COST disposal in a community. Refuse amounts, An estimate of capital cost including location of waste generators, political equipment, land and working capital gives institutions, social culture, economic an idea of which systems might be compa- bases, laws, geology, weather and many tible with the financing potential of a others must be determined (see section community. Usually, higher capital costs 5.2). From these data, decision criteria mean more desirable features. This is an for that particular community are deve- important tradeoff to be considered in the loped. These criteria are then put selection process.

188 5.2.2.2 FLEXIBILITY be considered. The cost of "down time" is also important. Systems have different amounts and types of flexibility.. Most of these 5.2.2.7 OPERATING COSTS systems are built for twenty year periods. The need for flexibility or ease of al- Operating costs are maintenance over- teration could be due to a number of vari- head, direct labor and materials, utilities, able factors. Capacity needs might change taxes, insurance, interest, disposal of in the future. Composition of MMR might residue, fringe benefits, fuel, administra- change. Laws concerning the environment tion, plus miscellaneous expenses. These and recovered products may change. The are not unrelated to qualitative factors; value of the energy products and recycled for example, the use of more employees than materials may change. Political struc-. necessary may be a political decision or tures and social attitudes might change. the demand by the community culture to re- Technical developments, not known today, cycle may result in more maintenance. may be so beneficial in the future as to Further, managing many small units rather warrant equipment alterations. As popula- than one large unit might be offset by tion centers shift the location of the savings in transportation of refuse to the system may need changing-. ' operation. On the other hand, economies of scale might be more important. Possibi- 5.2.2.3 RELIABILITY AND MAINTAINABILITY lities of modular planning should be considered. If modules are added when more Corrosion, abrasion, high tempera- capacity is needed,- the original cost is tures, and normal wear and tear lead to lower and capital cost is expended as breakdowns which in turn leaves the MMR needed. Also, higher labor costs could unprocessed. Ease of repairing the sys- be offset by better equipment reliability tem and the availability of parts and and good employee training. The possibility service seem all important at such times. of strikes and unionization should be taken A short.repair time is important. Built into account. Difficulty of operation, and in redundancy could help by saving the vulnerability to misuse or mishandling system from a complete halt. Some sys- would be less important with more expen- tems may have more MMR storage capabili- sive skilled labor. ties than others. A landfill "next door" is often recommended to accomodate the The relationships between these var- refuse if breakdowns occur. ious qualitative factors and costs should be carefully considered. A good under- 5.2.2.4 STANDARDS standing of the tradeoffs involved will result in good decisions. Local pollution control standards, EPA standards, public health regulations 5.2.2.8 SALE OF RECOVERED RESOURCES and OSHA safety standards must be met by any system considered. Future standards The type of resources recovered, the and the legal information in Chapter 2 form in which they are recovered, the should be considered. availability of markets, the effect on the market prices of the added resources sup- 5.2.2.5 CONSTRUCTION AND START-UP TIME plied, the reliability demanded by potential customers, the reliability expected Design, installation and start-up from the conversion process, the possibility time intervals need to be considered in of creating new markets, transportation light of when the system is needed. possibilities including traffic conditions, roads, access to rail spurs, all affect the • In many areas, disposal problems are estimates of present and expected future in the crisis stage. Monroe County in New credits from the sale of resources reco- York has run out of landfill sites and vered and energy products manufactured. needs to install a new system right away. Even so, the projected start-up date for Prices incorporated into long term a resource recove'ry system is 1977 (ref. contracts would possibly be lower than 5-7). In contrast, the Houston, Texas prices quoted in present markets. Long area has enough landfill sites for the term contracts could be demanded by those near future. Here the start-up time for a financing the proposed system. Even with- new system is not critical. Houston can out this demand, the security of long term afford to let technology develop more contracts should be considered. while Monroe County cannot. 5.2.2.9 WASTE DISPOSAL CREDITS OR DEBITS 5.2.2.6 MAINTENANCE COSTS If a system can handle industrial The cost of maintaining equipment, waste, sewage, or sewage sludge, this sys- buildings, and grounds should be considered. tem should receive financial credits. On Preventive maintenance programs, the num- the other hand if it produces sewage or ber of employees and degree of personnel other waste this disposal cost should be a training required for maintenance should debit.

189 5.2'J?2.10 PHYSICAL CHARACTERISTICS tax needs Local land availability, hydrology, Environmental concerns topography, drainage, geology, weather, resources recovered wind direction, pest and odor control energy recovered considerations, 'special "characteristics of EPA Standards local utilities, traffic patterns, highway local pollution standards networks; zones, financing, all may be important considerations; . MARKETS AND ECONOMICS 5.2.3 QUALITATIVE CHARACTERISTICS Capital investment equipment Certain aspects, such as good resource land cost recovery, environmental considerations be- amount of land yond those -required by law and political working capital , . " . and social contingencies, may be important building to communities- 'These are often not planning , . adequately reflected economically directly economic life . '-' or indirectly. •"' For reasons which • are not economical, certain forms of energy or Operating costs certain materials recovered might be favor- maintenance "•ed. 'A system which has a large safety mar- overhead . , gin concerning -unknown future environmental direct labor . ' impact could be favored. Certain polluting materials fact'drs might be considered more important utilities than others. Air, water, noise,''an attrac- taxes tive appearance, or smell might be parti- insurance cularly important. interest . .. ".: disposal of residue Attitudes of 'existing managers of fringe benefits - . solid'waste in the'-area and the image sys- fuel costs tems offer £o observers could affect the administration . choice of a waste disposal system. transportation 5.2.4 OUTLINE OF CONS ITERATIONS Plant siting relation to markets ' - The 'following outline-organizes 'the relation to solid waste source considerations mentioned in the'previous physical constraints .. 'discussion according to the data blocks relation.to social attitudes in Figure 5-1. This outline furnishes a list of selection-criteria subjects. Markets of recovered energy availability : ; ,.• 9 '••••'•' •<••>•.' REFUSE DATA form of recovered energy ."„.. ... reliability of supply and demand Type new market possibilities Amount ' -••••' ": • • '• • transportation .. , .. . Composition market price fluctuations .' Seasonal variability' contract possibilities . -t . ,. Special wastes Waste generation locations Markets of by-products . _Pro"jected'r'ate of generation availability form of products .. . ,'.•:". • SOCIAL, LEGAL, ENVIRONMENTAL reliability required . ': ,. . AND POLITICAL DATA research and development current and needed OSHA Standards •' • transportation , :' ••'.' ; .'• * ' '• "' price fluctuations Political institutions contract possibilities , .. • who makes decisions *••'• regional authority ' Sensitivity to price of products .. ... scrap markets .. Public acceptance '•-"• • "• ' local conditions credibility t contracts ' 'existence of definite and apparent need (crisis?) PHYSICAL AND TECHNICAL DATA '•• ; aesthetic considerations image • '•'' Residue disposal pest control land - .. odor • • - • • ' - '• • , transportation '•• past history0- • community culture •

190 Installation time study time operating costs. In addition, built-in construction redundancy might increase installation start up time. There are, -indeed, many of these time limits on existing method of interrelationships. disposal If all of the characteristics men- Adaptability tioned were to be considered with their capacity needs relationship to each other, the result future MMR composition changes would be an overwhelming and confusing future legal changes collection of ideas. The next two sections market changes contain a suggested way to simplify the political and social changes decision process and gain useful informa- technical developments tion. location desirability changes mode of operation 5,3 SELECTION OF FEASIBLE OPTIONS Capacity expansion 5,3,1 PRELIMINARY SELECTION CRITERIA modular units When a particular community needs a . ease of expansion new waste disposal system it should consider all the options available. Many Labor requirements of these options are, however, not feasible skill requirements for one reason or another in particular vulnerability of system to misuse locations. Hence, to analyze in detail Plant siting all the systems available would be unne-_. land availability cessary and also costly. hydrology To determine the feasible options,, topography a community can first of all consider the drainage previously given check list and determine geology which factors are to be used as prelimin- weather ary selection criteria subjects. The wind direction community must then put the germane num- pest control bers or qualifications on these factors. traffic As an example, the following is a list of criteria which a hypothetical community Conversion technology might use in screening all the technical status of development options available. In order for the pro- data available cess to be eligible for further considera- overall technical reliability tion it must fulfill each requirement be-, operating experience low such as: 1. Because of a long term contract Maintainability and repairability already held with the city, it must handle costs the oily waste from Acey Industry. equipment building 2. System must handle 1000 metric grounds tons of -MMR/day at the time of installa- preventive maintenance program tion and be expandable to 2000 metric personnel requirements tons/day by 1985. '. T Redundancy and storage 3. System must meet all EPA stan- . reliability of disposal reliability of production dards thru 1985 as to air, land, and water reliability demanded by markets pollution. : / reliability demanded by social 4. Major breakdowns should occur no attitudes more than twice a year. When, the plant reliability demanded by managers shuts down, operation should be restored 5,2,5 DISCUSSION OF TRADEOFFS within 24 hours. 5. The net operating cost per ton of There are relationships between the MMR must not exceed $8.50 assuming public different criteria mentioned which .suggest that to increase a system's desirability financing at 8 percent interest. in one area might be to decrease it in an- - 6. System should recover at time of other. Another common and obvious example installation 90 percent of the tin cans a is the relationship between capital cost and 50 percent of .the aluminum - the only and maintenance costs. Often, if one is markets available at this time. higher the other is lower for similar systems. Built-in redundancy, flexibility, 7. Total landfill requirements must and short installation time are desirable not exceed 20,000 square meters per year features which would generally increase at depths determined by a geological capital cost and might even increase survey in each potential area.

191 8. To reduce collection costs, system criteria. In the preliminary selection should be installed in two modules in dif- criteria example given, an option that ferent geographical locations. ' meets all 10 criteria is eligible for further detailed analysis. 9. Sites should be within"18 kilo- deters of the city center-and be agreed up- •Recognizing the difficulty in obtain- on by citizen referendum within a radius ing options that meet all these criteria a of 4 kilometers of the site. community may wish to-divide the criteria into two categories. These would be: 10. System should have had running experience for 2 years at a capacity of at '1. Criteria that must be absolutely .'least 500 metric tons per day. met - no negotiation possible. Again re- ferring to the example cited previously, , '••" • This list is only an illustration. 'items No. 1, 2, 3, and 9 might fall into The reasons for the various concerns and ;this category. numbers relate to the_ individual community.. - Even after the various op'tions have been'. 2. Criteria that may not have to be checked for these criteria it may turn o,ut absolutely met - some.negotiation possible. that one or more of the criteria can be The balance of the items in the example, changed allowing more options to be feas- i.e.. No. 4, 5, 6, 7, 8, and 10 might fall ible and eligible for-further investiga- into this category. tion. This preliminary selection process may Preliminary selection criteria them- be; done several times with alternate selves might vary in number from just a sets of criteria. This selection process bare minimum of two or three important is meant to be very flexible incorporating factors, to an exhaustive list covering new information and insights where pos- all aspects of the problem. The number sible. of criteria chosen results from a tradeoff analysis between: The output from this process is then a list of feasible processes available for 1. too few considerations making further analysis to determine which is the selection meaningless and, .optimum solution for the community. This screening process is shown on the left 2. too many considerations making'- side of Figure 5-2 located in the next .selection impossible and.cpstly. section. 5.3.2 TECHNICAL OPTioNS^AvAiLABL'E ,',-•. ;.. 5.4 ANALYSIS OF FEASIBLE SYSTEMS Another input to the selection of 5.4,1 INTRODUCTION feasible options is the number and kind of technical options available. Before a The analysis of feasible systems is community can adequately-use any plan,'it concerned with the final selection of a should be technically .viable. .. Unless "a waste-disposal system. This analysis takes community can get substantial financial place after the initial screening 'process assistance to embark oh an experimental has narrowed the choice of systems to project, it is preferable .to screen out those which will meet the major require- those options which are "in the development, ments of a community. stage. !•'..- • The analysis.of feasible options con- Among possible' options, those which siders both qualitative'and quantitative produce energy fall basically into .the factors. Analysis of the qualitative fac- following categories: tors involves the assignment of weights to various factors-such as the adaptability 1. incineration \, of the system, its public acceptance-, and 2. pyrolysis '.'... its installation time. The ability of a 3. biodegradation. : system to achieve a certain factor and the factor's weight are used to provide'a Each of these types. have";their attendant score - an indication of system desire- advantages and disadvantages which are ability. All quantifiable costs associated discussed in Chapter 3. J''It should be .with the project are subjected to a tra- noted that water wall 'incineration .is the ditional economic analysis. These two only energy recovery method currently well numerical inputs are then used by a deci- developed. . . sion' maker as a guide in selecting the final process. The overall procecedure is 5.3.3 SCREENING . , shown in Figure 5-2. It is a more detailed a version of Figure 5-1. This section deals, Once the selec.tibn criteria have been" however, only with the material after the developed and a lit^pf .'available options feasible options have been determined. made, the next step.'.is ..to see whether First of all,'a suggested economic analy- or not each option can achieve all the sis is given, Then, the determination of

192 I FEASIBILITY ( CAPITAL | FACTORS I OPERATING COST| I COMMUNITY I I ANNUAL COST I PROCESSES iNEEDS a WANTS! I CREDITS I NOT FEASIBLE /DECISION\ / MAKEtJAiy^Rn • FEASIBILITY COST SCREENING ANALYSIS

•4 DECISION j

PROCESS DESIRABILITY ATTRIBUTES EVALUATION

p. ^ I DESIRABILITY FACTORS j 0 / ~7\ I FACTOR SCORES | P i OPT. A I \ FACTOR WEIGHTS ^\ WEIGHTING 0 i DATA / N COMMITTEE S AND STUDY TEAM

FIGURE 5-2 DECISION PROCEDURE desirability is given. The Cost Analysis Sheet is designed to accommodate either private or municipal 5,4.2 EVALUATION TECHNIQUES ownership of a community's disposal system. A private owner will pay income taxes 5.4.2.1 ECONOMIC ANALYSIS and also completes Columns 2, 5, and 6, on the form. It.will be financially advan- Sound estimates of both the initial tageous for the private owner to use an capital expenditures and the yearly opera- accelerated form of depreciation and claim ting costs and revenues provide the foun- the maximum amount of depreciation possi- dation for a valid economic analysis. The ble in the early years of his investment. forms shown in Figure 5-3 and Figure 5-4 are provided as a means of summarizing The economic analysis is a standard these estimates.. The forms shown in Fi- technique called the Present Worth Analy- gure 5-5 and Figure 5-6 provide the for- sis found in engineering economy books. mat for the economic analysis. The sum of all the present worth amounts in Column 9 yields the total present worth The net annual cost for a given system of the cash flows associated' with the dis- can be determined by adding the annual posal system under consideration. The capital cost to the annual operating cost system having the largest positive value and subtracting the annual credits or re- as its present worth is the most finan- venues. This dollar amount is divided by cially desirable system. •the metric tons per year handled to obtain a dollar per metric ton cost. The data Another standard economic analysis is for this calculation are listed in Figure the Equivalent Annual Cost Analysis. Pro- 5-3 and Figure 5-4. To obtain the annual vision for carrying out this analysis has capital cost the interest rate and economic been made on the bottom of the Cost Analy- life period must be established. An en- sis Sheet. gineering economy book such as reference 5-8, may be consulted for the appropriate 5.4.2.2 DESIRABILITY ANALYSIS capital recovery factor. Introduction. To be thorough in ana- For the economic analysis, data esti- lysis, the feasible processes must each be mated for each year of operation are trans- evaluated in terms of not only economic ferred to the Cost Analysis Sheet (Figure but also social, environmental and politi- 5-6) from the Process Cost Sheet (Figure 5-3), cal factors that are pertinent to the

193 CAPITAL COSTS (TOT. $) DOLLARS/YR- COMMENT Land Preprocessing Egmt Processing Eqmt Postprocessing Egmt Utilities Building & Roads Site Preparation Engr. & R & D Plant Startup Working Capital Misc.:

TOTAL

OPERATING.COSTS ($ PER YR! Maint. Material Maint. Labor Dir. Labor. Dir. Materials Overhead Utilities Taxes Insurance Interest Disposal of Residue Payroll Benefits Fuel Misc.:

TOTAL

CREDITS ASSUMED ($ PER YR)

FIGURE 5-3 PROCESS COST SHEET

DOLLARS/YR. COMMENT

Fuel: Liquid Gas Solid Power: Steam Electricity Hot Water Magnetic Metals Nonmagnetic Metals Glass Ash Paper Other:

TOTAL ($ PER YR.)

FIGURE 5-4 RESOURCE RECOVERY DATA

194 Capital.Costs

19 19 19 19 Total Land Building Equipment Site Preparation Plant Start Up Working Capital Other:

TOTAL

Operating Costs

Residue Year Material Labor Fuel Utilities Disposal Other Total 19 19" 19" 19" 19" 19" 19" 19" 19" 19" 19" 19~ 19" 19~ 19" 19 19" 19" 19" 19"

TOTAL

FIGURE 5-5 CASH EXPENDITURE SUMMARY community. It should be noted that while weights are then used together with desir- similar factors may have been used earlier ability measures'to arrive at an overall for feasibility screening, they are used weighted measure of process desirability. more qualitatively in the desirability analysis. The evaluation technique is presented in the following sections. After des- Every feasible process will not satis- cribing some basic ideas that are used in fy completely all of the economic, social, structuring the technique, a step by step environmental and political desires of a procedure is given. community. For the purpose of deciding which feasible process is to be selected, The evaluation procedure is not de- each should be evaluated as to how desira- signed to produce a final decision. In- ble it is with respect to the set of fac- stead, it is a procedure by which due tors- considered. These factors are called consideration of many relevant factors is desirability factors. To each of the fac- systematically taken into account for all tors for each process, a measure of the the selected feasible systems. Further- desirability may be given. Since all facr more, it is a method to reduce the bulk of tors are not likely to be equally impor- information down to a few summarized mea- tant to the community, there is a need of sures which are comparable between dif- assigning weights to these factors. These ferent processes. Since these measures

195 8 9 Total Amt. Present ' Subject to Tot. Op. Taxable Income Net Cash Worth Present. Year Dep. Dep.Amt. .Cost Revenue Income Tax Flow Factor Worth

19 19' 19" 19" 19" 19" 19" 19" 19" 19" 19" 19" 19" 19" 19" 19" 19" 19" 19" 19"

TOTAL CAPITAL RECOVERY FACTOR EQUIVALENT ANNUAL COST

FIGURE 5-6 COST ANALYSIS SHEET describe the overall characteristics of solving problems involving qualitative fac- each process'to the community, they will tors have been mostly confined to an analy- serve along with the economic analysis as sis at one point in time. However, a pro- a-useful aid for the decision maker(s) in cess, once selected, is expected to operate making a final selection. satisfactorily for many years; therefore the desirability score for a particular To determine the factors in the desir-. process should be obtained for the expected ability evaluation, a committee should be operational life. An attempt is made to formed of members representing various . allow for multi-period evaluation in the views and interests in the community's solid proposed procedure. waste management program. Before evaluation, relative, weights are assigned to each Process Outline. The mathematical mo- of;the desirability.factors.. In order to del uied~roF~the~^ro"posed desirability eva- assign weights that.reflect the composite luation procedure is a simple linear, non- true opinion of the community, the factors interactive model with equally spaced time should be well understood by each committee intervals. An overall weighted score (u) member and weighted without regard to any for the desirability of a process is given particular process. . by, Although many desirability factors are 0 = (1/(T)(I))Z ZW.(t) Z x. .(t) interrelated, they will be evaluated as independent factors one at a time. In order to arrive at an overall measure of the de- where 1=1, 2, I - the number of sirability, it -is.- necessary to evaluate Study Team Analysts, each; factor based on some common unit. A (0 to 1) measure is used to rate all the . j = 1, 2, J - the number of de- factors such that a highly desirable factor sirability factors is given a score very close to 1 and a high- (see Table 5-1) ly undesirable factor is given a score close to 0. This is.also done for certain . t = 1, 2, T - the number of quantifiable f actors-.which qualitatively periods under study, fit into the desirability analysis, e.g., high capital cost.may.be undesirable. x. .(t) is the desirability score of the jth factor for period t 1 Decision analysis techniques for

196 evaluated by analyst i (see ratio between this factor and the one im- Figure 5-7), and mediately below it in the list. In the example, f, is judged twice as important ..,. W.(t) is the previously mentioned th as f.A , f.& is one-tenth as importan. - - • t as f,j ,• ''• 'committee's weight assigned to the j f. is two and one-half times as important i factor for period t and is obtained as f., and f. is one and three-tenths as'-'- by averaging the committee members' important as t,/ !1 assigned weights, w. . (t), k=l,2, . j ,* 4. After assigning ratios,'they are. . K, where K is the number of mem- entered in the second column and their cor- ; bers on the Weighting Committee. responding raw weights can be computed by first letting the last factor be the base When a relatively small number of weight of 1, and using the formula • ' factors, say less than 5, is to be evaluated, their weights can be easily assigned 0^ „ ^ vQ-tJ.1 V by simple methods such as ranking.. The J ,kK = 3,K JTl,K so called DARE method proposed by Klee beginning with j - J-l and ending with J=l. (ref. 5-9) appears to be a simple and yet These are shown in the third column. (Note powerful technique for assigning weights that Q5 k is defined as 1.) to a large number of factors. It is a modified version of the Pair Comparison Examples of the Q's computed are shown method. By assigning a weight ratio to a below: factor compared only with the next one in the list,the number of comparisons is Q - (1.3)(1.0) - 1.30 drastically reduced. This is certainly an 4 advantage. and C ), = (0.1)(3.25) = 0.33

The method of assigning weights 5. Compute the weights, w. . (t), by (w. (t)) is described below with an ex- 3 J »v * dividing the raw weights by 'the '', sum of ample. It is to be done by each Weight all the raw weights. The last column now Committee member - "K" in number. contains the weights which' will be used to arrive at the average weights (W.(t)) - a 1. Given a set of desirability fac- weight for each factor for each period of tors f., j=l,2,. . . J, list the factors study. (J=5 in the example) in any arbitrary order as shown in the first column of Table 5-1. Once.the weights of the desirability factors are determined, the desirability . TABLE 5-1 score x, . (t) of each process with respect WEIGHT DETERMINATION EXAMPLE to each factor and period must be deter- FOR ONE PERIOD mined by the "I" Study Team Analysts. The scoring method proposed here requires in- Factor Ratio 'Raw Weight dependent evaluation of each process with Weight respect to each desirability factor. fj Rj,* QJ,K Wj,k Actual evaluation using the proposed f .2.0 0.66 0.10 method is done by scoring a value between l 0 and 1, according to the analyst's judg- f2 0.1 0.33 0.05 ment on how well the process satisfies the f 2.5 3.25 - 0.50 community desirability factors one at a 3 time. To facilitate the evaluation pro- £ 1-3 1.30 0.20 4 . . > cedure, it is helpful to specify for each f 1.0 1.00 0.15 factor the characteristics which are the 5 most desirable and the least desirable to 6.54 1.00 the community concerned (see Table 5-2). When evaluations are made for multi- 2. Starting from the top of the list, ple periods, a convenient way for the ana- assign a ratio, R, k representing the lyst to use a form such as the one shown k committee member's judgment of the im- • in Figure 5-7. • portance of the first factor compared to The crosses in'the form illustrate a the second factor in the list. sample raw score done by one analyst for the present time and for a 20 year study 3. Continue assigning ratios to all considering 1 year periods; In the model the other factors one at a time in the or- presented, these scores are weighted by der they are listed, except the last one multiplying each'by a corresponding set of which is assigned a ratio of 1 (R~ j.) • The yearly weights - (W.(t)). For a prelimin- ratio assigned to a factor is an importance ary analysis without weights, a score

197 FOR PROCESS "A" BY i* ANALYST NOW PERIOD * 1 YEAR ( 23456789 10 II 12 13 14 15 16 17 18 19 2O MOST DESIRABLE I

PUBLIC ACCEPTANCE l/i = LEAST DESIRABLE 0 -*,.PA<0) t—xliPA(5)

FIGURE 5-7 DESIRABILITY SCORE EXAMPLE could be obtained by dividing 21 (T) , the The Committee Members should number of scores, into the sum of the 21 have general agreement as to raw scores. For the above illustrative the meaning and interpretation example', the unweighted score is 9.5/21 = of each of the factors chosen, "\45 for the public acceptance of the process being evaluated. Such a score could b. decide the total number of mean that, in the opinion of the analyst, years for which evaluations the process should be changed in order to are to be made. This is a increase the community acceptance. difficult task since it in- i volves projecting events in- When each of the feasible processes to the uncertain future. How- is evaluated with respect to all the fac- ever, it is considered very tors by each analyst in the team, the in- important as it tends to force put data generation is complete. Compu- each member to look beyond tations of the weighted scores (u) for each the present. process can be performed using the mathematical model presented earlier. c. decide the number of periods, or the time intervals within Process Elaboration. The following the study life. For example, material is an elaboration of the process a study life of 20 years with previously presented. A list of possible 5 equal time intervals in ad- desirability factors is given. Also a dition to the present means a step by step process is outlined. A form total of 6 evaluations, one designed for use by the Weighting Committee for the present and one for and a form designed for use by the Study each four year interval. Team Analysts in their desirability scoring of the feasible processes are pre- 2. Each Committee member should weigh sented. each desirability factor according to his or her judgment as to its While each community should have its relative importance for each of Decision Committee determine the important the periods in the study life. A desirability factors for weighting and weighting sheet shown in Figure evaluation, a recommended list of factors 5-8 is designed for assigning the has been selected as shown in Table 5-2. paired weight ratios , (R.3, .K - re- These are based .on' the outline of important fer to Table 5-1). The method has factors presented in Section 5.2.4. Note been explained previously. Com- that the most and least desirable levels putation of average weights of each factor are also specified in the (W.(t)) must then be done for each table. It is believed that a slight addition to or subtraction from the list period. will be adequate enough for most locales. Also noted is the fact that the exact 3. Analysts of the Study Team should meaning of each factor might vary with the meet to familiarize themselves community. with the list of desirability factors selected by the Weighting The step by step process is as follows: Committee. Understanding of the factors is most important in- or- 1. The Weighting Committee meets to: der to achieve good performance in evaluation. Discussions are a. list desirability factors, with encouraged at this point to clari- reference to those shown in fy what each factor represents. Table 5-1, to be used for evaluating feasible processes. 4. Each Study Team Analyst indepen-

198 TABLE 5-2 DESIRABILITY FACTORS

FACTOR MOST DESIRABLE LEAST DESIRABLE 1. market of recovered energy guaranteed by contract new market needs to be created 2. market of by-products guaranteed by contract new market needs to be created 3. residue disposal none . 50% or more and/or special disposal 4. environment no pollutants may not meet some standards 5. health and safety completely safe potential hazards in plant, to' public installation time will meet schedule likely to delay beyond required date capital investment . minimal and/or easily financed almost impossible to finance 8. operating cost low high 9. management simple or sub-contracted difficult to manage plants and labor 10. adaptability adaptable to any new cannot be modified technology 11. public acceptance attractive to public strong resistance from public 12. capacity expansion fully expandable no room for expansion 13. input requirement any composition of re- operation stops if input is fuse/fuel inadequate 14. labor requirement few and unskilled many and highly skilled 15. plant siting no restrictions only one possible site 16. conversion technology well developed and experimental commercialized 17. maintainability and done without stopping prolonged shutdowns frequently repairability production 18. resource and energy complete recovery of en- low thermal efficiency and recovery ergy and resources nothing recovered 19. back-up and storage continuous operation no back-up, no storage assured 20. market price fluctuation minimal affect extremely sensitive dently evaluates each factor for according to the overall weighted each period, -one process at a time. scores. This list together with Adequate time is allowed for ob- the results of the economic ana- taining relevant information lysis discussed in Section about the process in order to 5.4.2.1 are now submitted to the evaluate the factors. If a pro- decision makers for their use in cess is very desirable with res- making a final selection. pect to a factor .a score closer to 1 is given. A process very unde- Post-Evaluation Analysis. It is ap- sirable with respect to a factor parent .that most municipal officials are is given a score close to 0. A particularly concerned with the net unit scoring sheet is designed for this cost of refuse disposal. This information purpose (Figure 5-9). A cross is from, the economic analysis can be used a- marked in the box corresponding to long with the desirability score to judge the analyst's score of desirability the merits of a particular process with for the time period considered. respect to the other feasible processes. The decision maker may decide on the basis 5. Compute weighted scores (o) for all of the two pieces of information, cost and the processes evaluated. This can score, provided to him for each process. be done by an ad hoc group or a Since the cost estimates are subject to computer. variation because of market uncertainties, it will be more informative to the decision 6. List the processes rank-ordered makers if some kind of sensitivity analy-

199 Weighting Committee Member (k) Date DESIRABILITY FACTORS PAIRED WEIGHT RATIOS FOR EACH PERIOD j,k Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1. market of recovered energy 2. market of by-products 3. residue disposal 4. environment 5. health and safety 6. installation time 7. capital investment 8. operating cost 9. management 10. adaptability 11. public acceptance 12. capacity expansion 13..input requirement 14. labor requirement 15. plant siting 16. conversion technology 17. maintainability & repairability 18. resource and energy recovery 19. back-up and storage 20. market price fluctuation

FIGURE 5-8 WEIGHTING WORK SHEET sis is presented. One simple method is 5.5 FINAL DECISION given as an example below. : 5.5.1 USE OF RECOMMENDATIONS FROM Figure 5-10 is an example presentation DECISION PROCEDURE of results of the evaluation of six alternative waste disposal processes includ- The results of the decision procedure ing systems for energy and resource recovery. will be a list of technical options which Their weighted scores (u) and net cost per have been screened to make sure each meets metric ton of refuse disposal are listed in minimum community criteria and then analy- the second and third columns respectively. zed in more detail for economics and de- The last column shows the expected cost, sirability. It is unlikely that any op- ranges due to market uncertainties. This tion will unanimously be accepted by all information may also be plotted as shown politicians or members of the general pub- in the graph. From the illustrations, it lic. Neither will it be an optimum tech- is readily seen that at least processes C nical solution since, the technology in this and F should probably be eliminated from area continues to evolve. further consideration. Process C has a very large cost range, which may be an in- The advantages and disadvantages re- dication that the process :is either still sulting from the implementation of each in its very early development stage, or option should be explicitly enumerated. the market for its products is highly un- Those making the final decision must eva- certain, or both. Process F may be a much luate this information and make judgments better developed process but it is ex- based on their own value preferences. penxive. Consider, for example, a disposal There are available many other mea- solution which produces a very marketable sures which attempt to combine the cost product, has no residue to be landfilled, with desirability score- to arrive at a sin- but which has a higher total cost per ton gle measure for each process. Examples than an alternative disposal solution re- are cost-benefit ratio studies or cost- quiring a landfilled residue. Since the effectiveness analyses. They are not dis- future outlook for landfill is uncertain cussed in this report. due to possible legislation restricting or

200 Alternative Option _Analyst Date

DESIRABILITY FACTORS SCORES - BY PERIOD NOW I 2 3 4 5 6 7 8 9 10 II 13 13 14 15 16 17 18 19 ZO 1. Market of recovered energy

2. Market of by-products

3. Residue disposal

O 4. Environment I

5. Health and safety

6. Installation time

7. Capital investment

8. Operating cost

9. Management

10. Adaptability

FIGURE.5-9 DESIRABILITY SCORE WORK SHEET

201 NOW I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 IS 17 18 19 20 11. Public acceptance

12. Capacity expansion

13. , Input requirement

14. Labor -requirement

15. Plant siting

16. Conversion, .technology . i ^^

17. Maintainability and repairabilityi—

18. Resource and energy recovery i zzz

19. Back-up and storage

.20. Market price fluctuation

FIGURE 5-9 (CONTINUED)

202 disposal squarely on local governmental units. A .62 5.29 *~ 8 Since these governmental units, in B .41 3.00 I 7 turn, are responsible to the people, the people themselves are ultimately responsi- C .79 8.40 ble for good waste disposal; In today's I'' society, people must be supportive of waste 0 disposal systems which not only maintain a • healthful environment for themselves, but E which also ensures a livable environment

F for future generations. 0.1 0.2 0.3 O.4 05 0.6 07 0.8 03 • . ' OVERALL SCORE An example of direct citizen partici- - pation in solid waste decisions is the FIGURE 5-10 previously cited study of the Rochester, OVERALL:SYSTEMS EVALUATION EXAMPLE New York, solid waste problem done by vo- lunteers from the Rochester Engineering banning landfill all together., the decision Society (ref. 5-6). In'a related example may be to opt for the higher cost system. the county in which Rochester is located The decision procedure is not intended has a Solid Waste Management Advisory to provide the decision maker with a de- . Council which includes persons represent- finitive answer; rather it is a guide to ing the general public (ref. 5-11). ensure that all relevant variables are ta- In summary, the responsibility for ken into account. -The intent is to have waste disposal falls on the governmental the information as to cost and desirability units responsible for overall public available to the decision maker. But such health. The ultimate responsibility how- information does not itself constitute a ever, lies with the general public who, in decision. producing the waste, must not only allow it to be picked up but must also assure 5,5,2 RESPONSIBILITY FOR FINAL DECISION that it is properly put down. Who is responsible for the final de- : cision about solid-waste disposal methods? _ 5,5.3 EXAMPLES OF DECISION STRUCTURES Many states have recently legislated The material in Chapter 2 outlining regional structures'-for determining -and the social aspects points.out that, aside implementing waste disposal methods. We from well publicized pressure from ecolo- will consider, briefly, plans in New York, gists, the main motivation for good waste Texas, and Connecticut. ' The political disposal has been the public health of a boundary and reference for each plan stu- community. died is given below: In discussing.duties of.municipalities a political .scientist (Phillips, Connecticut - entire state (ref. 5-12) ref. 5-10), points out that: New York - one county (ref. 5-11) "Refuse disposal has such 'an ob- Texas - three counties (ref. 5-13) viously close relationship with public health that cities must make In Connecticut and Texas the Waste provision for it and must take steps to see that householders, industrial- Disposal Authority was set up by the state ists, business enterprises and others legislature while in New York it was done comply with regulations or suffer - by the county government. penalties for noncompliance." (p. 594) The following' are 'some pertinent de- In the. same reference it is noted that tails of each system considering primarily in 1951 the American Public Health Associa- overall responsibility and final decision tion suggested that community health pro- authority. grams should, among other things, include: Connecticut. The Connecticut Resource " . . .direct supervision and regula- Recovery Authority '(CRRA). has been set up tion of many activities, such as pro- as a regional waste authority for the en- tection of food, water, and milk tire state. The CRRA is responsible for: supplies, control of nuisances, re- "1. The planning, design, construc- gulation of housing, inspection of tion, financing, management, hospitals and other health facili- ownership, operation and mainten- ties, disposal of wastes, . . . . " ance of the solid waste disposal, (p.530)(underlining for .emphasis). volume reduction and resources recovery and support facilities It is concern for public health that considered necessary, desirable or places the responsibility for waste appropriate to carry out the state

203 plan. difficulty of finding a socially acceptable new landfill site, the County undertook the 2. The provision of solid waste following steps: management services to municipalities, regions and persons; the 1. an extensive market survey was made recovery .of resources from solid to determine what resource and wastes; and the production of energy materials could be sold in sufficient revenues from such the local .area, services to permit CRRA to operate on a self-sustaining basis. 2. recommendations were made to the Department of Public Works as to 3. The utilization of private indus- which materials could be feasibly try to contract for system de- recovered, velopment, management and operation, and for other services. 3. engineering firms were consulted as to the ease with which such . 4. Assistance in the development of systems could be implemented, industries and commercial enterprises in Connecticut, based upon 4. proposals from four firms were then resource recovery, recycling and evaluated by an interdisciplinary reuse. committee drawn from the Public Works Department, consulting en- 5. Assistance with and coordination gineers, the Rochester Engineering of local efforts directed toward Society, environmental groups, the source separation and recycling. county legislature, a private Re- fuse Collectors Association, en- 6. Planning, research and develop- gineering schools, and local in- ment, management and operation dustries, of the state's systems and facilities for solid waste-manage- 5. a disposal system recommendation ment in order to permit continuing was made to the county government, improvement for lowering operating and other costs." 6. bids were let by the county for - (ref. 5-12) construction and equipment. • The authority is also empowered to Texas. The Gulf Coast Waste Authority, appoint advisory councils perhaps with set up by the state legislature, is a three citizen representation. The authority county waste disposal authority which in- must report quarterly to'the Governor and cludes Harris County (Houston). Its basic annually to the General Assembly of responsibility in areas of solid waste is Connecticut. quoted from Texas law. New York. Monroe County passed a "The authority shall establish minimum solid waste disposal.act affecting the en- standards of operation for all aspects tire county, including the City of Roches- of solid waste handling, including, ter. The purpose of the act is to: but not limited to storage, collection, incineration, sanitary landfill, or "enhance and improve the disposal and composting." (ref. 5-13) transporting of solid waste by establishing and enforcing standards, These standards are to be made public before regulations, rules and procedure . ." implementation. The Texas Air Control (ref. 5-11). 'Board and the Texas State Department of Health also must be consulted. This county-wide program authorizes the Department of Public Works to super- Master plans for waste disposal must be vise disposal in the county while the submitted to the Texas Water Quality Board county manager is empowered to enforce for approval. the provisions of the law. The act also provides for a council of In addition to the citizens and health mayors from the various cities affected. officer previously mentioned, the Advisory The mayors in turn elect the board of dir- Council has members from the county legis- ectors of the waste authority. lature, Department of Public Works and local businessmen dealing with refuse. One Thus, decisions concerning waste dis- of its duties is to make recommendations posal are made (or at least monitored) by to the Department of Public Works and the state and local governmental bodies charged County Legislature for the improvement and 'with public health concerns. implementation of solid waste management programs. Hopefully, these decisions reflect the needs and desires of the public represented Conversations with officials of Monroe by the various decision making bodies. County revealed that because of the

204 5,6 SUMMARY REFERENCES Many communities have experienced con- 5- 1 Glysson, E. A., et al: The Problem of siderable difficulty in using landfill, Solid Waste Disposal. College of En- incineration, and composting for waste gineering, University of Michigan, Ann disposal purposes. Because .of this, there Arbor, Michigan, 1972. is a trend toward using sophisticated waste disposal systems which maximize resource 5- 2 Gross, M. S.: A Unique Citizen En- and energy recovery. The act of selecting gineer Effort Associated with Solid a particular system for a community is Waste Disposal. ASME paper 73-DE-29, complex. A proper choice cannot be made paper presented at Design Engineering without a thorough investigation of many Conference and Show, Philadelphia, factors such as the political, legal, so- pa., April, 1973. cial and environmental implications of the choice. These implications must be 5- 3 Midway.Drops Limestone County Disposal considered simultaneously along with the Project. Houston Chronicle, July 30, more traditional economic and technical 1974. operating factors. A new dimension that also must be considered when energy pro- 5- 4 City Asks Kent Help on Refuse Hauls. duction 'and resource recovery are under- Grand Rapids (Mich.) Press, Jan. 18, taken is an analysis of markets. 1973. Evaluation of all factors can be en- 5- 5 Eastwood, D. G.: Opening Address at hanced by following a formal procedure, • the City of Buffalo Resource Recovery such as that recommended in section 5.4. Seminar. Buffalo, New Vork, June, This procedure, which separately considers 1974. economic and desirability factors is designed to ensure that the relative advan- 5- 6 Solid Waste Disposal Plans for Monroe tages and disadvantages of all systems are County. Vol. I, II, and III. systematically determined. The output of Rochester Engineering Society, Roches- the procedure is one or more cost indica- ter, New York, April, 1972. tors and an index of system desirability. These, when put together, provide a tool 5- 7 Request for Proposal - Monroe County, for the decision maker to help judge the New York. Resource Recovery Project, relative merits of the system candidates. Rochester, New York, April, 1974. (An example of the use of the procedure is given for Houston, Texas, in Appendix B.) 5- 8 Grant, E. L., and Ireson, W. G.: Principles of Engineering Economy. A note of caution should be given re- Fifth ed., Ronald Press, 1970. garding the'decision procedure. Even though the various factors are considered 5- 9 Klee, A. J.: The Role of Decision independent, in reality they are not. (A Models in the Evaluation of Competing brief discussion of some of these inter- Environmental Health Alternatives. dependencies is given in section 5.2.) Management Science, Vol. 18, no. 2, To include these relationships in a deci- Oct. 1971. sion model is difficult indeed. The decision maker(s) must keep this in mind when 5-10 Phillips, J. C.: Municipal Government using the procedure. Also, the overall and Administration in America. perspective must be maintained. For exam- Macmillan, 1960. ple a particular process may not be screened out even though it does not meet some pre- 5-11 Solid Waste Management Law of the liminary criteria but yet has other cha- County of Monroe, State of New York, racteristics which will yield a high de- Motion No. 47 of 1973. Legislature sirability score. It is assumed that the of Monroe County, Aug., 1973. "human" aspect of the decision process will be concerned with factor relationships 5-12 A Proposed Plan of Solid Waste Manage- and an overall perspective not obvious in ment for Connecticut. General Elec- the procedure itself. tric and State of Connecticut Depart- ment of Environmental Protection, June, In the final analysis, the ultimate 1973. decision must be made by the governmental unit charged with the responsibility for 5-13 Article 7621-d. Texas Civil Statutes waste disposal. The decision on how to as Amended, 1973. handle this disposal must be made with an overriding concern for all aspects of public health and welfare. The decision procedure outlined in this chapter, used in- telligently, should help ensure that such is the case in a local community.

205 APPENDIX A

RESULTS OF PRE-ENGINEERING DESIGN ON THE NAAS PROCESS

,206 Pag^Intentionally Left Blank RESULTS OF PRE-ENGINEERING DESIGN ON THE NAAS PROCESS

1. MATERIAL AND ENERGY BALANCES Input (metric tons/day) A pre-engineering design has been com- Moisture 227.0 pleted on a NAAS process plant having a capacity of 1136 metric tons (1250 tons) per Organics 708.0 day. Thg material and energy balances were based on the following refuse composition Inorganics 201.0 (ref. A-l): Moisture 20 percent, organics . 64 percent, inorganics 16 percent. Since Subtotal Municipal Solid the NAAS process uses a pyrolysis tempera- Waste Feed ture in the range of 760° - 871°C (1400° to 1600°F) , it will produce a product gas with Coal a composition similar to that of the pyrolysis gas produced by the West Virginia Air pilot scale fluid-bed reactor (ref. A-2): Total Feed to the NAAS Plant 1767.0 Mole % with Gas Mole % CO7 free Output (metric tons/day)

C02 14.7 0 Pyrolysis gas CO 27.1 31.7 H2 41.7 48.9 Water Gas CH, 7.7 9.0 0.1 0.1 Subtotal Product Gas C2H6 C2H4 7.7 9.0 C3H8 0.4 0.54 Aluminum' 0.6 0.66 Ferrous Metals The refuse feed was assumed to have the following composition (ref. A-3): Slag (a) The ultimate analysis is given by: Subtotal Inorganic Output 205.8 Element Wt % NHa 0.4

C 55.84 H2S 1.4 H 6.92 0 37.01 Flue Gas N 0.04 C02 337.0 S 0.17 02 26.0 which corresponds to the following typical structural formula N2 436.0

C30H45°15N0.02S0.03 Subtotal Flue Gas (b). Composition of Inorganics: Moisture Component Wt % Total Output From the Plant

Glass 38.4 FIGURE A-l Rock and Dirt ' 28.9 NAAS MATERIAL BALANCE FOR A .Ferrous Metals 26.9 1136 - METRIC TON PER DAY PLANT Aluminum 3.9 Non ferrous metals 1.9 The material balance was carried out on the following assumptions: (1) Maximum Operat- ing Capacity is 1136 metric tons per day, (2) The efficiency of ferrous metal and aluminum recovery is 80 percent, (3) The heating value of the low grade coal used is 2.33 x 107 joules/kilogram (10,000 Btu/lb) (4) The coal has an ash content of 12 weight percent. The overall material balance is shown in Figure A-l and an overall energy balance is shown in Figure A-2.

208 Input (joules/day) The overall energy balance of the plant was based upon the assumption,that MMR has a . Heating Value of 1136 metric ton/day is heating value of 1.5 x 10 joules/dry kilo- 1.37 x 1013 (20% Moisture) gram (6500 Btu/dry lb.). (13,000 x 106 Btu/day) 2. SIZING OF THE INDIVIDUAL EQUIPMENT Heating value of 58 metric tons/day coal Kinetics data for pyrolysis of organic 1.35 x 1012 refuse are available (refs. A-4 and A-5). However, the kinetic data for the water-gas (1,280 x 106 Btu/day) reaction and the reaction between the lime and carbon dioxide in the literature are ; not accurate enough for detailed engineering design. In designing the major NAAS equip- Total energy Input 15.05 x 1012 ment (pyrolyzer, combustor and dryers), the 'limiting factor is the exit-gas velocity (14,280 x 106 Btu/day) 'rather than the residence time, since in a rotary kiln, the residence time can be Output (joules/day) ' varied over a very wide range by adjusting the inclination and the rotating speed of Heating Value of 523 metric tons Product the kiln. But if the exit-gas velocity, Gas 1.20 x 1013 from a rotary kiln is too high, the entrainment of dolomite will be excessive, which (11,370 x 106 Btu/day) will in turn result in unfavorable economics due to dolomite replacement and excessive Heat Loss 3.05 x 1012 cleanup needed. In this design, the maximum gas velocities from all major equipment (2,980 x 106 Btu/day) are kept below 1.0 meter/sec (about 3 feet per sec). The dimensions, power required, and Total energy Output 15.05 x 1012 construction materials for all individual equipment of the NAAS process plant are (14,280 x 106 Btu/day) : listed in Table A-l. Their purchase prices are listed in Table A-2. The major operating variables of the process are listed in •Table A-3. Approximate efficiency equals 3. ECONOMIC ANALYSIS OF THE NAAS PROCESS 1.200 x 1013 ' 1.505 x 101-" X 100 80% The analysis is based on the following assumptions: FIGURE A-2 a. The equipment costs are based on NAAS ENERGY BALANCE FOR A CAPACITY 1974 prices with a Marshall-Steven equip- 1136 METRIC TON PER DAY PLANT ment Cost Index of 360. b. The capital is borrowed at an in- The process produces 472 metric ton (519 terest rate of 10 percent a year, and the ton) per day of pyrolysis gas with a heat- equipment has an average life of 20 years. ing value of about 1.58 x 107 joules/ Standard cubic meter (SCM) (530 Btu/SCF) c. Carbon dioxide with a purity of when it is free from C02 and 51 metric ton 98 percent is worth $8.80/metric ton. of water-gas with a heating value of about 9.9 x 106 joules/SCM (330 Btu/SCF). The d. The price of the product gas is total volume of the mixed gas produced is $0.71/109 joules ($0.75/106 Btu). 8.04 x 105 SCM/day (22.74 x 106 SCF/day). The product has-an average heating value of e. Recovered metallic aluminum is 1.49 x 107 joules/SCM (500 Btu/SCF), an worth $330/metric ton. average molecular weight of 13.3, and an average composition of: f. The credits for ferrous metals, glass, and slag is assumed equal to the Gas Mole % costs of handling them. CO 34.3 As shown in Table A-4, the total invest- 49.0 ment is $12,467,500. Other pertinent cap- 7.7 ital costs are listed in Table A-4. The fraction 7.9 annual utility costs estimated are.in c5.-fraction 1.1 Table A-5 and the annual operating costs 100.0 estimated are in Table A-6. The economics of five operation cases are tabulated in Table A-7.

209 TABLE A-l LIST OF EQUIPMENT FOR THE NAAS PROCESS

Power Name Quan- Capacity Dia. Lgth. Construction Material Reg*d Remarks tity (m) (m) (KWl Shredder 2 46 metric Carbon steel 500 For rough ton/hr shredding only- Magnetic 46 metric Separator 1 ton/hr Carbon steel frame 6 Dryers 2 5.5 • 9.2 • 12 _, - Partly austenitic Pyrolyzer ' 1 5.5 18.3 steel lined 20 Combustor 1 -5.5 15 15 Belt 46 metric Conveyors 2-3 ton/hr 5-6 Maximum Screw 92 metric Stellite-25 screw temp Conveyors 3 ton/hr Austenitic casing 12 970«C Austenitic steel Screw 92 metric screw, Ferrite Maximum temp Conveyors 1 ton/hr . steel casing 760" C Ferrite steel Maximum ser- Screw 46 metric screw, Mild steel vice temp Conveyors 4 ton/hr casing 6 371° C Carbon steel casing, Bucket 92 metric 310 SS chains and Conveyor 1 ton/hr buckets 12 46 metric Max service Slag & Acid -. ton/hr Stellite-25 screw 6 temp 970° C. Remover 1 Total solids Austenitic steel Needs to be casing developed Needs to be de- 100 metric Austenitic steel moving veloped, Max Aluminum ton/hr parts, Ferrite steel service temp Separator 1 Total solids casing 12 815° C Steam 100 metric Austenitic Steel mov- Preheater 1 ton/hr ing parts, Ferrite 12 Needs to be Total solids steel casing developed Max Press Air 3.58 x ' 6.96 x 104 Blower 1 104 m3/hr Carbon steel 530 N/m2 Max Press Gas 3.2 x 10 6.96 x 104 Blower m3/hr 304 Stainless steel 580 N/m2 Press, drop Flue Gas 3.58 x 104 1.38 x 104 Multi- m3/hr at N/m2 cyclone 1 149° C . • Carbon steel Product Gas 3.20 x 104 Press . drop Multi- m3/hr at 2.07 x 10* cyclone 1 371° C Carbon steel N/m2 9.1 metric Gives steam Waste heat ton/hr at 3.45 x 10s Boiler . . Carbon steel N/m2 Cooling tower 1 9.46 m3/hr Air 2.18 x Carbon steel shell Preheater 1010J/hr 310 SS tubes 16 161 m2

210 TABLE A-l (CONTINUED) Power Name Quan- Capacity Dia. Lgth. Construction Material Req'd Remarks tity (m) (m) (KW) Pump 1 13.3 raVmin Carbon steel 20 Pump 1 13.3 m3/min 310 Stainless steel 20 Venturi Water rate With pumps Scrubber 1 7.6 m3^nin 304 Stainless steel and motor Ash Hopper 1 1 13 Carbon steel Slag Hopper 1 1 3 Carbon steel Dolomite Hopper 1 1.5 33 Carbon steel Feed Hopper 1 2 4 Carbon steel Shredded Feed Hopper 1 17 7 Carbon steel

.. TABLE. A-2 . PURCHASED EQUIPMENT INVESTMENT FO.R NAAS PROCESS (Designed Capacity 1250 metric ton/day of MMR)

A. Feed preparation 2 Shredders (for rough shredding only) 120,000 Magnetic Separator 21,000 Sub-Total 141,000 B. Solid Transfer Belt Conveyors 50,000 3 High temperature screw conveyors 60,000 2 Medium temperature screw conveyors 20,000 4 Low temperature screw conveyors 16,000 1 Bucket elevator 9,000 Sub-Total 155,000 C. Gas Transfer Air Blower 140,000 Gas Blower 200,000 Sub-Total 340,000 D.- Drying, Pyrolyzing, and Combustion 2 Dryers 400,000 i COmbustor 500,000 1 Pyrolyzer 700,000 Sub-Total 1,600,000 Solid Separation Slag and ash remover 30,000 Aluminum separator 52,000 Steam preheater 15,000 Sub-Total' 97,000

211 TABLE A-2 (CONTINUED)

Heat Recovery Waste Heat boiler 25,000 Air Preheater 24,000 Cooling Tower 39,000 Sub-Total 88,000 G. Storage 340,000 H. Miscellaneous D. C. Rectifier 15,000 2 Multicyclones 40,000 Concrete Pad 27,000 Front-end loader 38,000 Sub-Total 120,000 I. Gas Purifying System 250,000

Purchased equipment Grand Total $3,131,000

TABLE A-3 TABLE A-4 MAJOR OPERATING VARIABLES OF . THE NAAS PROCESS • • • PLANT FIXED COST (1135 METRIC TON/DAY) Direct Fixed Cost Circulating rate 909-1100 metric Purchased equipment >$ 3,131,000 of dolomite ton/day Purchased equipment installation 1,565,500 Inlet temperature Instrument and Control 500,000 of the pyrolyzer 850e-960« C Piping (installed) 800,000 Electrical (installed) 570,000 Outlet temperature Building (including of the pyrolyzer 740"-760« C services) 990,000 Yard improvement 279,000 Inlet temperature Service, facilities of the combustor (installed) 900,000 (solid phase) 340°-350» C Land 130,000 Sub-Total $ 8,865,500 Outlet temperature of the combustor Indirect Fixed Costs (solid phase) 950'-960« C Engineering and Steam flow in pyrolyzer 71 metric ton/day Supervision 1,000,000 at 670e-680e C Construction Expenses 1,240,000 Contractors' Fee 262,000 Saturated Steam pressure 2.1 x 10s - , Contingency and Start-Up 1,000,000 in waste heat boiler 3.4 x 10s N/m2 Sub-Total 3,502,000 (30 - 50 psi) Working Capital 100,000 Total Investment $12,467,500

212 TABLE A-5 UTILITY REQUIREMENIQI36S ANMETRID COSTC TON/DAYS FOR TH) E NAAS PROCESS

UTILITY QUANTITY ANNUAL COST Steam Self -producing None Cooling Water 1.33 m3/nin. $ 13,800 Electric Power 2000 KW 40,000 Total Annual Utility Cost $ 53,800

TABLE A-6 OPERATING COSTS FOR THE NAAS PROCESS (1136 METRIC TON/DAY OF MMR)

ITEM QUANTITY DOLLARS/YEAR

A. Direct Production Costs 1. Raw materials Low-grade coal 58 metric ton/day $ 126,720 Dolomite makeup 2 metric ton/day 52,800 2. Operating labor 7 persons/shift 336,000 3. Direct supervision and clerical labor 67,200 '• * 4. Utilities • ; 53,800 5. Maintenance and repair 260,000 6. Operating supplies 65,000 7. Laboratory charges 50,400 Sub-Total 51,011,920 B. Indirect Fixed Charges 1. Capital Cost Amortization (10% interest, 20 yr. life) 1,440,000 2. Interest 10,000 3. Local Taxes 250,000 4. Insurance 91,000 Sub-Total I1,791,000 C. Plant Overhead $ 398,000 Total Annual Operating Cost $ 3,200,920

213 TABLE A~7- ECONOMIC BALANCE OF THE NAAS PROCESS - 5 CASES (1136 METRIC TON/DAY)

Case A: Operating' a"t" '100 percent capacity with no CO; sale 1. Income ' Dollars/year a. Product gas sale $ 2,813,300 ' b. Aluminum Wale 693,000 * 'Total Income $ 3,506,300 2. Operating 'Costs' '• " Dollars/year a. Fixed^CbVts "; $ 2,966,900'

b. Variable Costs ( , . 243,320 Total Costs S 3,210,2-20 . 3. Gross Annual Profit or $ 296,080 $0.99/dry metric ton Case B; Operating at 100% capacity with CO, sale 1. Income ' ' ' Dollars/year ••• • .,- <• a. Product gas sale $ 2,813,300 b. Aluminum sale 693,000

c. C02 sale 980,000 Total Income $ 4,486,300 2. Operating Costs* $ 3,229,620 3. Annual Gross Profit or $ 1,256,680 $4.19/dry metric ton •

Case C; Operating at 50% capacity with no CO? sale 1. Income . Dollars/year fj -- • . •i a. Gas sale . $ 1,406,700 b. Aluminum sale ' 346,500 . • Total Income. $ 1,753,200 2. Operating Costs $ 3,088,510 3. .Annual Loss or , . •$ 1,335,310. $4.46/dry metric ton

* A capital cost of $250,000 for the additional gas purification equipment is added to the fixed cost.

214

\I TABLE. A-7 (CONTINUED)

Case D: Operating at 50% capacity with CO7 sale 1. Income ' ... Dollars/year a. Gas sale $ 1,406,700 b. Aluminum sale 346,500

c. CO2 sale 490,000 Total Income $ 2,243,300 2. Operating Costs $ 3,107,960

V J 3. Annual Loss or $ 684,760 $2.87/dry metric ton Case E; Operating at 75% capacity without CO^ sale 1. Income Dollars/year a. Gas sale $ 2,100,000 b. Aluminum sale $ 520.000_ Total Income $ 2,620,000 2. Operating Costs $ 3,148,900 3. Annual Loss or $ 528,900 $1.76/dry metric ton

REFERENCES

A-l Boegly, W. J., Jr.; Hayes, V. 0.; Hise, E. C.; Compere, A. L.; and Griffith, W. L.: Mius Technology Evaluation—Solid Waste Collection and Disposal. ORNL-HUD-MIUS-9, Sept., 1973, p. A-l. A-2 Albert, S. B.; Scheeline, H.;"Louks, B.; Ferguson, F. A.; and Harynowski, C.: Pyrolysis of Solid Wastes, A Technical and Economic Assessment. Standford Research Institute, (SRI Project ECC - 1886), Sept., 1972. A-3 Material Recovery System,. Engineering Feasibility Study. National Center for Resource Recovery, Inc., Washing- ton, D. C., Dec., 1972, pp. 3-27. A-4 Bailie, R. C.: High Energy Gas From Refuse Using Fluidized Beds. Final report to EPA, (Grant'Number 5R01 EC 00399-03 EUH) , Aug. 1, 19-72. A-5 Aldrich, D. C.: Kinetics of Cellu- lose Pyrolysis. Ph.D. Thesis, MIT, Part I, 1974.

215 .. APPENDIX B HOUSTON APPLICATION

216 Page Intentionally Left Blank HOUSTON APPLICATION

INTRODUCTION Houston is already a large industrial port, and has an economy which includes market potentials for all the pro- The application of the ideas of this ducts of systems which, convert solid-waste report to Houston, Texas, serves as an ex- to energy (ref. B-2). The choice, there- ample of how the concepts of converting fore, of an energy converting process does solid waste to energy might relate to a not need, to depend heavily on what is pro- particular city. This application is based duced. However, some products may be more on assumptions rather than a thorough study easily marketed than others. Information of Houston. as to the markets' ability to gain letters of intent, contracts and manufacturing alterations, and public attitudes furnish - PRELIMINARY SELECTION CRITERIA needed facts about market feasibility. Presently, Houston is involved in the For purposes of-this example, the pre- initial stages of'using newly constructed liminary screening process (see Figure 5-2) miniature incinerators which have no energy •is eliminated. Those-processes for further producing capacity (ref. B-l). These Con- detailed analysis are those in Table B-2. sumat mini incinerators are to be located In reality some of these are not feasible throughout the city at four or five sites. in the Houston area but are included because of the availability of technical and economic information (see Chapter 3). ASSUMPTIONS FOR APPLICATION TO HOUSTON Houston is a rapidly growing city in . land area, population, and industry. Solid- Assumptions are made which concern waste disposal is, at the present time, the aspects of Houston's future relating handled by private enterprises. In the re- to systems of converting solid-waste to cent past, the city has experienced failure energy in Houston. These assumptions are in a few experiments with solid-waste dis- made to facilitate a proposed answer to posal (ref. B-l). A compost plant was the question, "What technical option should closed due to a limited market and public the City of Houston use to convert solid- protest. Pollution complaints plagued waste to energy?" The proposed answer de- both of these experiments. Both were pends on the assumptions below and, thus, • extremely costly. Law suits and embar- reasons for the assumptions are given. rassment were involved. Also there has Three of the assumptions are made solely been difficulty in locating 'new landfill on the grounds that they facilitate a pro- sites. Private enterprise, .in disposing posed answer. These relate to cooperation of the waste, relieved the city of the of officials, both private and public. problem for the moment. It is also noted This cooperation is assumed, without evi- that the private firms and the City per se dence. each collect about one half of the MMR - 3300 metric ton daily from Houston. Throughout these assumptions, an attitude of cooperation by all involved par- - - Browning and Ferris, with a subsi- ties is assumed. Many of the assumptions diary , Resource Recovery, landfills and • could be checked by polls, attitudinal • idoes a limited amount of recycling. About checks, attempts at obtaining contracts, three quarters of the city's solid-waste and letters of intent and negotiations is landfilled and about one quarter is left with-those potentially involved. '.•• at the Resource Recovery plant located near the ship channel and near the industries The list of assumptions' follows: . which surround the channel. The basis for each assumption is stated . Certain areas of Houston elect to con- just after the assumption when appropriate. tract with the private sector for a higher level of pickup service than the City of- List of Assumptions: (Late 1970*s) -,,:;fers. They pay the private firms, and receive a refund from.the City. If there . 1. By the late 1970's, landfill will ,o-was a drastic fluctuation in the number of not be an acceptable means of disposing of customers taking part in such an arrange- solid-waste in Houston. (In the last five ment, then the Department of Solid-Waste years there have been no new landfill sites Management of the City would experience due to political, social and environmental either a strain in refuse collection ca- reasons.) (See Chapter 2) pabilities or a strain in the budget (ref. B-l), depending on the direction of the 2. Due to recent failures with com- fluctuation. i posting and incinerators in Houston, there ,i will be a resistance to any major innova- Thus, Houston seems to require a solid- tion in solid-waste handling. waste disposal system which is highly de- „.. pendable and flexible.

218 3. The City of Houston will be in a during the period 1980 — 2000. (See position to make use of aggregates, such Chapter 4) as glasphalt for paving, from the late . ; 1970 'a through the late 1990's.- (See Chap- 14. The City of Houston will be ter -4, Research and Development.) willing to shift its present tendency to use mini-incinerators to a plan which in- »• 4. The utility companies will be in cludes energy and material recovery from, .-.a position to use gaseous or solid fuel solid-waste. This assumption is made -from MMR. They will be willing to do so. without evidence. • This assumption is made without evidence. .5. Browning and Ferris and Resource DECISION-MAKING DATA Recovery, Inc.-will be willing to coordinate their facility for shredding solid- waste and extracting ferrous metals with The following material is the'result a program of recovering energy from solid- of doing the economic and desirability - waste (ref. B-3). Again, this assumption analysis as indicated in Figure 5-2. The is made without evidence. details of this process are in Chapter 5. The major difference in the Houston- ap- •:• -6. .The MMR composition in Houston plication is that it was done- for only one will be very near the typical in the U. time period (the present) while the more S. (ref. B-2). general model in Chapter 5 is for any number of periods. . • .:..-- 7. No system which contaminates the air will be acceptable. Land and water The following tables are the result. contamination will need to be minimal. of the analysis for the "now" time period. Today's pollution problem in Houston suggests this .assumption. Also, EPA regula- Table B-l, represents the results of tions are an obvious constraint. work by a 5 man (K=5) Weighting Committee. This is the procedure given in Table 5-1• 8. By the early 1980's manufacturing and attendant exploration. companies could be in existence to-use materials recovered from solid-waste, if Once the weights were established, such materials are made available. (See 2 Study Team Analysts scored, using-Figure Chapter 4) 5-9, the desirability of each process in , light of the 7 (J=7) desirability factors. 9. -Houston will be able to own and The scoring results X (i,j) of analyst No. 1 finance an energy conversion system at .8 are in Table B-2 and No. 2 in Table B-3. percent interest over a 20 year period. . The weighted-scores from each analyst are given in column 1 of each table and are. .10. Paper, ferrous metals, glass and averaged to achieve-.the score (u) for aluminum will continue to be marketable in each process given in Table B-4.? Houston scrap markets. Throughout the fore- seeable future, Houston will continue to •'Table B-5 combines-a--cost analysis, export scrap. • There will be continued with the score information of Table B-4. growth of industry near the ship.channel. Table B-5 also includes a figure which There will continue to be a large inte- pictures the cost along with the cost ran- grated :steel operation in Houston, glass ges and the overall weighted scoresi The container producers near and in Houston, cost ranges depend on ranges in the market paperboard mill and manufacturers of buil- values of products of the energy conver- ' ding products all which can utilize ma- • sion systems as noted in the assumptions/ terials recovered from solid-waste. Alumi- in cost analysis for.Table B-5 and B-6. num reclamation in Houston will continue. Table B-6 is also an analysis independent Copper mines in the Southwest United States, of the decision model. All of the weights, near enough to Houston to use its steel scores, and evaluating words used in the cans, will' continue to do so for copper decision model of Chapter 5 are based on precipitation (ref. B-2). opinions and judgment. 11. It is likely that transportation The assumptions -used in the cost analy- costs for scrap will become lower. (See sis are listed in Table B-7. The energy Chapter 2) recovery processes in application are listed in Table B-8. 12. There is a good chance that front end separation technology will improve and become more economical. Also the tech- DECISION-MODEL RESULTS nology of maintaining and operating an energy conversion system will probably improve and become more economical. This The application of the decision-model is based on.analyses in Chapter 3. : techniques of Chapter 5 to the City of Houston has yielded the'following ranking: 13. Energy prices will probably increase more rapidly than operating costs (1) St. Louis supplemental fuel process

219 TABLE B-l WEIGHTING OF THE DESIRABILITY VECTOR FOR HOUSTON 1974

August 12, 1974

Weighting Committee AVER- Members RAO HALTER DALTON KUESTER Van POOLEN AGE Desirability . Factors R K W R K W R K W R K W R K W w-t Market 1.5 3.0 .24 1.0 20 .22 1.5 1.28 .13 1.0 8 .21 1.5 3.38 .35 0.23 Capital Investment 1.0 2.0 .15 1.0 20 .22 .5 .85 .08 1.0 8 .21 1.5 2.25 .23 0.18 Operating Cost • 1.0 2.0 .15 1.0 20 .22 .75 1.69 .17 1.0 8 .21 2.0 1.5 .16 0.18 Public Acceptance 2.0 2.0 .15 5.0 20 .22 1.5 2.25 .22 4.0 8 .21 3.0 .75 .08 0.18 Plant Siting .5 1.0 .08 4.0 8 .09 1.0 1.5 .15 .5 2 .05 .5 .25 .03 0.08 Conversion Technology 2.0 2.0 .15 2.0 2 .02 1.5 1.5 .15 4.0 4 .10 .5 .5 .05 0.09 Maintainability 1.0 1.0 .08 1.0 1 .01 1.0 1.0 .10 1.0 1 .03 1.0 1.0 .10 0.06 13 91 10.0"? 3? 9.63 1.00

TABLE B-2 WEIGHTED SCORES

PROCESS BLACK- ftemst- NZBT UNION ECO CPU- HEIGHTS COMPOBTIHG CLAHBOS DYNATECH VIRGINIA MONSAUTO CARBIDE FUEL 400 •Raw Scon MARKETS 0.23 6. 1 1.0 1.0 0.9 0.7 0.4 0.9 0.8 1.0 o.e 0.3 V Keight«d Scon 0. 23 2.30 2.30 2.07 1.61 0.92 2.07 1.84 2.30 1.84 0.69' CAPITAL INVESTMENT 0.18 0. 5 0.2 0.4 0.5 0.5 6.5 0.9 0.4 0.8 0.8 0.4 "1.2 0.90 0.36 0.72 0.90 0.90 0.90 1.62 0.72 1.44 1.44 0..72 OPERATING COST 0.18 0. 4 0.4 0.3 0.4 0.9 0.4,- 0.5 0.3 0.9 0.7 0.7 "1,3 0. 72 0.72 0.54 0.72 1.62 0.72 0.90 0.54 1.62 1.26 1.26 PUBLIC ACCEPTANCE 0.18 0« 0.90 1.08 0.90 0.90 1.08 0.72 1.44 1.44 1.80 1.44 1.44 PLANT SITING 0.08 0. 3 0.6 . 0.4 0.5 ' 0-.6 0.5 0.6 0.7 o.e 0.9 0.6 "1,5 0. 24 0.48 0.32 0.40 0.48 0.40 0.48 0.56 0.64 0.72 0-.48 CONVERSION TECHNOLOGY 0.09 1.0 0.8 0.1 0.1 0.6 0.9 0.8 0.8 0.1 0.9 1.0 X1.6 0. 90 • 0.72 • 0.09' 0.09 •0.54 0.81 0.72 0.72 0.09 o.ei 0.90 •MAINTAINABILITY - • -• t RELIABILITY 0.06 0. 9 0.7 ., . 0.8 . 0.4 •0.4 0.6 0.3 0.7 0.4 0.6 ' 0.6 "1,7 0.34 0.42 0.48 0.24 0.24 0.36 0.30 0.42 6.24 0.36 0.36 SUM 0? WEIGHTED SCORES 0. 443 0.608 0.535 0.532 0.647 0.483 0.733 0.624 0.813 0.787 0.585

220 TABLE B-3 WEIGHTED SCORES

PROCESS Buuac- PFBTPBR- .VEST ONION ECO CPO- WEIGHTS COMPOSTING CLAKSON OYNATSCa VIRGINIA CARRETT MONSANTO CARBID1I FUEL 400 ST. LOUIS VON ROLL MARKETS 0.23 0 ." *« 0. .™ o 0.5 0 .46 1.84 • 1.15 1.38 0.92 1.38 1.61 1.61 1.15 2.07 1,.38 1 '"" CAPITAL ^ - : INVESTMENT 0.18 0 .8 0 .2 . 0.7' 0:7 0.7 0.6 0.9 0.3 o'.e 1.0 "o".5" X2.2 1.44 0 .36 1.26 - 1.26 1.26 1.08 1.62 ' 0.54 1.44 1.80 . ' 0 .90 OPERATING COST 0.18 0 .8 . 0.2~ 0.7' 0.7 7 0.6 0.9 0.3 1.0 0 .5 °- o;.s *!,) 1.44 0 .36 ' ' l.« . • 1.26 1.26 1.08 1.62 . 0.54 l.<4 1.80 0,.90 PUBLIC r ACCEPTANCE 0.18 0 .3 0 .6 0.6. 0.6 0.6 . 0.6 0.2 0.6 0.6 0.6 0 .6 X 2.4 0.54 1..08 ' i.o.e 1.08 ' 1.06 1.08 0.36 1.08 1.08 1.08 .1..08 Q g PLANT SITING 0.08 > • 0 0 X 2,S ' 0.32 0 .64 . 0.40" 0.48. 0.48. . .'.0.48 . 0.48 . : 0-64 0.72 O.S6 _v_,0 .72 ' CONVERSION ! r -, TECHNOLOGY, 0.09 0 .9 .5 0.3 0.4 0.4 0.6 0.5 , 0.7 0.4 0.7 . 0 .9 X 0 2,6 0 .81 0 .45 . 0.27- 0'. 36 0.36 0.54 0.45 ' . 0.63 0.36 0.63 0 .81 * MAINTAINABILITY •< : • AND RELIABILITY 0.06 0.9 0,.7- 0.8 • • 0.4 0.6 / 0.5 0.7 0.4 0.6 0 .6 X . 0:4 2,7 0 .54 0 .42 0.48 0.24 0.24 0.36 0.30 ; 0.42 0.24 0.36 0 .36 _ ! /' . SUM OF WEIGHTED SCORES 0 .555 0.,515 0.590.' 0.606 . 0.560' 0.600 0.644 , 0.546 0.643 • 0.830 " 0,.618

TABLE B-4

Average Overall Desirability Process Weighted Score Rank for each Process

1. Composting 0.499 .11 2. Black Clawson 0.562 9 3. Pfeffer Dynatech 0.563 8 4. West Virginia 0.569 6 5. Garrett 0.604 4 6. Monsanto 0.542 10 7. Union Carbide 0.699 3 8. CPU-400 0.728 2 9. St. Louis Sup Fuel 0.808 . 1 10. Von Roll 0.600 5 11. Eco Fuel II 0.585 7

221 TABLE B-5innn COST - SCORE ANALYSIS FOR A 1000 TPD IN HOUSTON

COST - SCORE ANALYSIS FOR A 1000 TPD IN HOUSTON

OVER NET NET ALL COST COST RANGE NO. PROCESS NAME SCORE I/ TON B / TON 12 1 COMPOSTING .50 4.60 385 - 6.43 2 BLACK - CLAWSON 56 770 697-12.70 3 PFEFFER DYNATECH 56 8.97 6.72-10.48 10 4 W. VIRGINIA UNIV. .57 9.70 8.68- 9.82 5 GARRETT .60 4.90 2.37-7.13 NET COST 6 MONSANTO .54 7.30 4.42-8.82 7 UNION CARBIDE .70 5.50 3.71 - 5.75 $8 T 8 2.92-6.49 T/"\M CPU -400 .73 4.18 TON 9 ST. LOUIS 81 3.80 3.12-5.75 10 VON ROLL .60 9.70 6.90-1026 II ECO FUEL:n < 59 4.00-10.00 6

.4 .5 .6 .7 .8

TABLE. B-6 OVERALL WEIGHTED SCORE

O> tt> O) (<•> (i) (»> ( ) (•) <»> U0> ill) FAHFIELD- BLACK- PFEFFEB- FACTORS RAKDT CLAHSO* DrKATHECH FLUIDIZED CARRETT FACTOBS nONSAVTO CARB IX ST. LOTH VOX ROLL UET PVLPDIC AXACBOBIC BED nmoLYsii PYROLYS IS PYRO YStS CPU-400 SL'PPL. FITL I .\CNEPWT ION tM FI>:I

• («) CAPITAL INVESTMENT (•) CAPITAL IMESTMEN1 SU.U2.000 11,1 1,000 14, 000,000 6,*10,000 13,200.000 ro.ooo.oco 8 * >*° tOM tb) OKIATUG 0»T, Ma^Jfcl.

(c) GROSS MIT COST, I/TOM 10.40 11.20 io ! CMT, I/TOII •COST, tm» (() uruse CONSUMED (TONS) TEA*LY 100,000 100.000 100,000 lOfl.OOO 300.000 (f) REFUSE COH1UWO (TOM) «A«LY 100.000 100,000 324.000 2*0.000 3*0.000

(i) utina TO BE oil POSED 61 7Z (|) REStDUt TO BI DISPOSED n MIKIKAL ' «J, 12. ia T (h) MARttT UD . POOH .•AD GOOD GOOD (STEAH) GOOD VERV (STEAM) (STEAH) uxw

<1) BMVDOKKEJRAL • POOR * POOB POO GOOD FA IB ENVlROWeWAL COOO COCO FAIR POOR two two

H1ALIH & SAFETY POO* POOR POOR COOO COOO (J) HEALTH 6 SAFETY COOO POOR GOOD COOO COOO UVB

(k) PUBLIC AC01PTAUCC BAD BM> GOOD GOOD (k) PUILIC ACCZPTAHCE GOOD FAIR GOOD CCOD FAIr C4H»D

(l) PLAHT •nine LIHITID FA 11 POOR GOOD GOOD FAIR COOO GOOD VERY LTD. LIHITFt FAIR

GOOD UHCERTAIK FA IK n FAIR GOOD l»00

(n> MIMTEKUICI & REPAIR GOOD COOO GOOD EXTEKIIVE (n) HAintKAJICE t IE PAIR BOVTIIZ KM.TIXE HEAVY POOR ax» COOO

(p SEienivrrr TO nice CHAMCC PA I* HICH NOMUL . .LITTLE HIGH (p) SENSITIVITY TO PRICE CHANCE FAIR S«ALL FAIR MJRJ1AL FAIR UICU

(q CAFAciTi npttatc* tirutcutx L1JHTEB HODULM SQM |q) CkTMni UTAIOIOM BUILD KEV WILD KEU BMC LMITID EXPAMtULE B^LD^KEH (r INPUT REQUIROCNT FLEXIBLE FLEXIBLE FLEXIBLE FIXED FIXED (T) INPUT REqUIBIHENT . LIMITED LIMITED LIMITED ruiiitx FLEXIBLE NOT AFPL.

SKILLED SKILLED (•) LABOB REQUIBEtCHT SKILLED SKILLED SKILLED EEXI- • K1LUB SKILUD _ SKILLED (t BACK-UP 4 STQRACi GOOD PAW SOME (t) BACK-UP k BTOBACE NO BACK-UP u>o IOHE fflO*.. SOM (TOR. SOKt STOR. SOW (TOR. (QIC StOR.

222 TABLE B-7 ASSUMPTIONS IN COST ANALYSIS (FOR TABLES B-5 & B-6 COST ANALYSIS)

. 1. City owns and operates the facility • 2. 1000 tpD Capacity 3. 20 year life 4. 8% annual cost of money 5. land cost: $50,000/acre 6. labor cost: $4.50/hr. . 7. tin cans:- $30/ton 8.- Aluminum: $300/ton 9. 'Paper: $25/ton . . 10. Glass: $20/ton 11. Steam: $.50/1000 Ibs. 12. Knergy: $.34 million BTU 13. Residue disposal: $3.00/ton 14. Electricity: $.008/KWH

TABLE B-8 AVAILABLE ENERGY RECOVERY PROCESSES FROM MUNICIPAL SOLID WASTES

Supplementary Fuel Process (10% refuse) Von Roll Incineration Process (Saugus, Mass, type) CPU-400 Process Union Carbide Purox Process Monsanto Landgard Process Garrett Process West Virginia University Fluidized Bed Process Aerobic Composting Process Anaerobic Composting Process NRG Sanitary Landfill (with methane) MMR Biochemical Process

(2) CPU-400 process score in Table B-5 do not agree with the (3) Union Carbide pyrolysis process rankings which could be obtained from con- (4) Garrett pyrolysis process sideration of just net cost in dollars per (5) Von Roll type incineration based ' ton. For example, both Garrett and Von on overall score Roll had an overall score of 0.6 with dollars per ton values of 4.90 and 9.70 re- Note that the rankings based on overall spectively. The Fairfield-Hardy Composting

223 process had' a relatively low net cost but come stricter, and as the availability ranked last in overall score because of of energy becomes more important, the the past history of composting in Houston. concept of energy recovery from solid- waste will become more profitable. Market The CPU-400 rank of second in over- adjustments to the concept of utilizing all score is based on desirability in all materials recovered from solid-waste would factors except technical reliability. The naturally follow improved capabilities to performance (see Chapter 3) remains a extract aluminum and glass, as well as fer- question mark due to- some unsolved tech- rous metals and paper, from MMR. As the nical problems . technology to extract these materials improves and the need for raw materials in- The following comments are made as creases, the concept of recovering materials suggestions to the City of Houston in and energy from solid-waste will become more using energy recovery processes in the beneficial. handling of its solid-waste. 1. Use the already shredded MMR from SELECTED REFERENCES the Resource Recovery Plant to make Sup- plementary Fuel for use with coal in utility power plants. Browning Ferris B-l Where Innovation Harmonizes with a Industries, is considering this idea (ref . Boom Town Tune. Solid Waste Manage- B-3) . More shredding equipment could be ment, May 1974, p. 26. added, the process would take advantage of already existing equipment and could B-2 Darnay, A.; and Franklin, W. E.: be expanded. Salvage Markets for Materials in Solid Waste. EPA 1972, pp. 121-124. 2. Use the MMR handling equipment of the Holmes Road Incinerator to load MMR B-3 City Joins Forces with Industry at into a pyrolysis unit. This would utilize Reconversion Center. Solid Waste existing roads, storage, building and Management, May 1974, p. 95. grounds, lifting equipment, and it would take advantage of the previously arranged location of the old incinerator. This incinerator is not functional, and the City of Houston is considering dismantling it for salvage and scrap. ',- ;ViO'.f These two suggestions, the informa-, '..- tion in the Tables and the assumptions about the City of Houston, all seem to indicate that the St . Louis supplemental fuel concept should be considered for Houston, Texas. The supplemental fuel concept could be gradually integrated into Houston's present solid-waste management program. The growth of its use in Houston could depend on both the growth of Houston and the user's familiarity with the concept and. ability to handle the solid fuel effectively. Implementation of this idea would include engineering studies of potential user facilities, negotiations for contracts, arrangements with Resource Recovery Inc. to coordinate existing shredding equipment, and decisions concerning ownership, management and sharing of expenses between the public and private sectors. .To some extent, Houston seems to be gradually leaning in this direction. Browning Ferris Industries is considering the market potential of a solid fuel made from solid-waste.

FUTURE BENEFITS

As land becomes more expensive, as pollution and landfill regulations be-

••224 APPENDIX C INSTITUTE

225 Page Intentionally Left Blank INSTITUTE STAFF 1974 NASA/ASEE ENGINEERING SYSTEMS DESIGN INSTITUTE UNIVERSITY OF HOUSTON - RICE UNIVERSITY JOHNSON SPACE CENTER PARTICIPATING FELLOWS

George E. Antunes BA, Gonzaga University Associate Professor MA, Northwestern University Political Science PhD, Northwestern University University of Houston Houston, Texas 77004 Tsong-how Chang BSME, National Taiwan University, China Assistant Professor MSIE, West Virginia University Systems-Design Department PhD, University of Wisconsin, Madison University of Wisconsin Milwaukee, Wisconsin 53201 Shang-I Cheng BSChE, National Chekiang University, China Professor MSChE, University of Florida Chemical Engineering PhD, University of Florida The Cooper Union New York, New York 10003 Gary M. Halter BA, Midwestern University Assistant Professor MA, Midwestern University Political Science PhD, University of Maryland Texas A & M University College Station, Texas 77840 Joel Hebert BS, Louisiana Tech Assistant Professor MS, Ohio State University Mechanical Engineering PhD, Southern Methodist University Rice University Houston, Texas 77002 Francis W. Holm BS, Missouri University Assistant Professor MS, Missouri University Mechanical Engineering PhD, Kansas State University Texas A & M University College Station, Texas 77840 Edwin C. Kettenbrink, Jr. BS, University of Missouri - Rolla Assistant Professor MS, University of Missouri - Rolla Earth Science PhD, University of Iowa University of Texas of the Permian Basin Odessa, Texas 79762 James L. Kuester BSChE, University of Texas Associate Professor MSChE, Texas ASM University Chemical Engineering PhD, Texas A & M University Arizona State University Tempe, Arizona 85281 Loren D. Lutes BS, University of Nebraska Associate Professor MS, University of Nebraska Civil Engineering PhD, California Institute of Technology Rice University Houston, Texas 77002

227 Dupree Maples J '• - BS, Mississippi State University Associate Professor MS, Mississippi State University Mechanical Engineering PhD, Oklahoma State University Louisiana State University Baton Rouge, Louisiana 70815 Arthur C. Meyers III BS, Saint* Louis University Instructor - Natural Science/Technology MS, Saint Louis University Environmental Design College '- ' PhD,' Saint Louis University University of Colorado V Boulder, Colorado 80302 ' R. N. S. Rao BE, University of Mysore Professor of Civil Engineering and ' -:' ME,-Roorkee University Chairman of Department MS, University of Connecticut Prairie View A & M University PhD, Rutgers University Prairie View, Texas 77445 •• Armando Riesco II BSIE, University of Florida Assistant Professor ~*V '- MSIE;-University of Florida Industrial Engineering PhD,' University of Florida University of Puerto Rico Mayaguez, Puerto Rico 00708 A' • '' Michael Lee Steib BA, University of Texas Assistant Professor MA, University of Texas Mathematics PhD, University of Texas University of Houston " • .":/,. Houston, Texas 77004 ' *'"' Fredrick W. Swift BSAE, University of Notre Dame Assistant Professor MSMH, University of Alabama Engineering Management '••'"• •' PhD, Oklahoma State University University of Missouri - Rolla Rolla, Missouri 65401 W. D. Turner BSME ,'•• University of Texas Associate Professor • • • '• MSME,'University of Texas Department of Civil and Mechanical .PhD, University of Oklahoma Engineering Texas A & I University Kingsvilie, Texas 78363 .Lambert John Van Poolen BS, Calvin College Associate Professor BSME, Illinois Institute of Technology Engineering Department MSME, Illinois Institute of Technology Calvin College PhD, Illinois Institute of Technology Grand Rapids, Michigan 49506 (P. E. State of Illinois) Henry A. Wiebe BSIE, University of Missouri - Columbia Assistant Professor MSIE, University of Missouri -Columbia 'Engineering Management Dept. PhD, University of Arkansas University of Missouri - Rolla Rolla, Missouri 65401

STUDY MANAGER

Ronald L. Carmichael BS, Missouri School of Mines and Professor Metallurgy Engineering Management MS, Missouri School of Mines and University of Missouri - Rolla Metallurgy Rolla, Missouri 65401 ScD, Colorado School of Mines

228 . ADMINISTRATION

DIRECTOR

Dr. C. J. Huang Professor Chemical Engineering University of Houston Houston, Texas 77004

ASSOCIATE DIRECTOR

Dr. Charles Dalton Associate Professor Mechanical Engineering University of Houston Houston, Texas 77004

NASA ADVISOR

Mr. Terry Reese Urban Systems Project Office NASA Johnson Space Center Houston, Texas 77058

ASSISTANT DIRECTOR

Dr. Derek Dyson Associate Professor Chemical Engineering Rice University Houston, Texas 77002

229 Intentionally Left Blank CONTRIBUTORS AND CONSULTANTS

The following individuals gave for- The following is a list of people mal or informal seminars related to-either contacted by mail or phone that have been the topic studied or to the problem of very helpful in our achieving a' meaningful system design and group interaction. Their report. Their efforts are acknowledged efforts are hereby acknowledged and greatly and greatly appreciated. appreciated. Mr. Howard Christensen Dr. David G. Wilson Director of Solid Waste Disposal Professor of Mechanical Engineering Monroe County Massachusetts Institute of Technology Rochester, New York Cambridge, Massachusetts Mr. Gordon Eastwood Dr. Helmut Schultz New York State Dept. of Conservation Professor of Chemical Engineering Albany, New York Columbia University New York City, N. Y. Dr. Eugene Nesselson Director of Research Dr. Richard C. Bailie Waste Management, Inc. Professor of Chemical Engineering Oakbrook, Illinois West Virginia University Morgantown, West Virginia Dr. D. L. Wise Dynatech R/D Co. Dr. Walter Jones Cambridge, Massachusetts Professor of Aeronautical Systems University of West Florida Mr. Milton Gross Pensacola, Florida Eastman Kodak Co. Rochester, New York Mr. Harold E. Benson Urban Systems Project Office Mr. Gerald T, Vaughn NASA/JSC Resource Recovery, Inc. Houston, Texas Houston, Texas Dr. John R. Howell Mr. Robert Dyer Professor of Mechanical Engineering Gulf Coast Waste Disposal Authority University of Houston Clear Lake City, Texas Houston, Texas Dr. Warren Bush Ms. Marie Dalton Shell Development Co. Instructor, Division of Business Deer Park, Texas College of the Mainland Texas City, Texas Dr. Sze-Foo Chien Texaco Mr. Michael Edwards Bellaire, Texas Battelle - Columbus Laboratories Columbus, Ohio Mr. John D. Doyle Monroe County Dept. of Law 'Mr. Philip Beltz Rochester, New York Battelle - Columbus Laboratories Columbus, Ohio Mr. B. Jack McDaniel, P.E. Director Mr. Leo A. Spano City of Houston U. S. Army Dept. of Solid Waste Management Natick Labs Houston, Texas Natick, Massachusetts Mr. Edsel Stewart Mr. Tom Tassinari Mansanto U. S. Army St. Louis, Missouri Natick Labs Natick, Massachusetts Mr. Ken Rogers Combustion Equipment Associates Mr. Charles Benham New York, New York U. S. Navy China Lake Labs China Lake, California

232 APPENDIX E VENDOR LIST

233 Page Intentionally Left Blank VENDOR LIST

The following are contacts for further Tol lemache, Ltd. information regarding equipment and pro- London, England cesses mentioned in this report. The listing of a particular manufacturer does Williams Patent Crusher & Pulverizer Co. not imply endorsement. The list is not in- 804 St. Louis Avenue tended to be exhaustive. St. Louis, Missouri 63102

SHREDDING EQUIPMENT SEPARATION EQUIPMENT

Allis-Chalmers Mfg. Co. Arnold Engineering Company 1000 W. College Avenue .P. O. Box G Appleton, Wisconsin 54911 Chicago, Illinois 60690 American Pulverizer and Crusher Co. Barnes Drill Company 1249 Macklind 818 Chestnut Street St. Louis, Missouri 63110 Rockford, Illinois 61101 Bryant-Poff, Inc. E. E. Baur Combustion Engineering Co. Coatsville, Indiana 46121 1717 Sheridon Avenue Springfield, Ohio 45505 Buffalo Hammermill Corporation 1243 McKinley Parkway Checker Industries Corporation Buffalo, New York Suite 413-A 61 Bigelow Square Buhler Brothers Pittsburg, Pennsylvania 15219 Ontario, Canada Commercial Filters Division Carborundum Company The Corborundum Company Box 380 State Road Hagerstown, Maryland 21740 32 West Lebanon, Indiana 46052 Gruendler Crusher & Pulverizer Co. 2915 North Market Street Cyclonics, Inc. St. Louis, Missouri 63106 85 South Avenue Natick, Massachusetts 01760 Hammermills, Inc. 625C Avenue, N. W. Denver Equipment Company Cedar Rapids, Iowa 52405 1400 17th Street Denver, Colorado 80217 The Heil Co. 3000 Montana Street Dings Company Milwaukee, Wisconsin 53201 4740 W. Electric Avenue Milwaukee, Wisconsin 53246 Jeffrey Manufacturing Co. 813 N. Fourth Street Electro Deburring Co., Inc. Columbus, Ohio 43216 11014 W. Becher Street Milwaukee, Wisconsin 53227 The Marksman Corporation P. O. Box 6406 Envirex, Inc. Corpus Christ!, Texas 78411 A Rexnord Company 1901 S. Prairie Avenue Newell Manufacturing Company Waukesha, Wisconsin 53186 726 Probandt San Antonio, Texas 78204 Eriez Magnetics Asbury Road at Airport Pennsylvania Crusher Corporation Erie, Pennsylvania 16512 P. O. Box 100 Broomall, Pennsylvania 19008 The Exolon Company 950 E. Niagara Street Saturn Manufacturing, Inc. Tonawanda, New York 14150 P. O. Box 336 Wilsonville, Oregon 97070 Feeder Corporation of America 4429-T James Place Titan Engineering, Inc. Melrose Park, Illinois 60160 323 South LaSalle Street Indianapolis, Indiana 46201

235 FMC Corporation Rampe Manufacturing Company 111 E. Wacker Drive. 14918 Woodworth Avenue Chicago, Illinois 60601 Cleveland, Ohio 43609 S. G. Frantz Company, Inc. Simpson Orville Company P. O. Box 1138 1234 Knowlton Street 60 East Darrah Lane Cincinnati, Ohio 45223 Trenton, New Jersey 08606 Stearns, Inc. W. W. Grinder Corporation 6001 S. General Avenue 2955 N. Market Street Cudehy, Wisconsin 53110 Wichita, Kansas 67219, Sweco, Inc. Gyromatic Manufacturing•Company 6033-35 E. Bandini Blvd. 1717-A Elmhurst Road :••••.?•'; , ••-.--,• Los Angeles, California! 90040 •'' Elk Grove Village, Illinois 60007 Triple S Dynamics Sutton-Overstrom, Inc. Hoffman Air & Filtration 1029 S. Haskell Division of Clarkson Industries, Inc. Dallas, Texas 75223 ,2 Thompson Road P. O. Box 214 Eastwood Station Universal Vibrating Screen Co. Syracuse, New York 13206 P. 0. Box 1097 Racine, Wisconsin 53401 Indiana General Division 405 Elm Van Straatron Chemical Company Valparaiso, Indiana 46383 630 W. Washington Boulevard Chicago, Illinois 60606 Jacobson Machine Works, Inc. 2477 Nevada Avenue. N: WEMCO Minneapolis, Minnesota 55427 A Division of Envirotech P. 0. Box 15619 Jobmaster Corporation Sacramento, California 95813 9010 T. Liberty Road^ Randallstown, Maryland 21133 Wheelabrator-Frye, Inc. Materials Cleaning Systems Division Kason Corporation 451 S. Bynkit Street Peddie Building Mishawaka, Indiana 46544 231 Johnson Avenue] ;'...... Newark, New Jersey 07108 Winston Manufacturing Corporation P. 0. Box 640 T Magnetic Corporation of America Bellaire, Texas 77401 179 W. Bear Hill Road Waltham, Massachusetts 02154 PYROLYSIS PROCESS AND EQUIPMENT Magnetool 1051 Naughton . Troy, Michigan 48084 Adolph Coors Co. Golden, Colorado Metal Katcher Co. Cherokee Station Anti Pollution Systems P. 0. Box 5277 Pleasantville, New Jersey Louisville, Kentucky 40205 Arthur D. Little, Inc. Midwestern Industries, Inc. Acorn Park 915 Oberlin Trail S. W. Cambridge, Massachusetts 02140 Marsillon, Ohio 44646 Barber-Colman Co. Ohio Magnetics Resource Recovery Systems Division Division of Magnetics International, Inc. 1882 McGaw Avenue 5398 Dunham Road Irvine, California 92705 Maple Heights, Ohio 44137 Battelle Pacific Northwest Laboratories Pennsylvania Separator Company, Inc. Energy and Waste Section P; O. Box 340-T Battelle Blvd. Brookville, Pennsylvania 15825 Richland, Washington 99352 Permag Magnetics Corporation Black, Crow and Eidsness, Inc. 2960 South Avenue 7211 N. W. llth Place Toledo, Ohio 43609 Gainesville, Florida 32602

236 Bureau of Mines, Energy Research Center Combustion Equipment Associates, Inc. 4800 Forbes Avenue 555 Madison Avenue Pittsburgh, Pennsylvania 15213 New York, New York 10022 Devco Management, Inc. 410 Park Avenue INCINERATION EQUIPMENT New York, New York 10022 Garrett Research and Development Company, Inc. Wheelabrator-Frye, Inc. • 1855 Carrion Road 299 Park Avenue La Verne, California 91750 New York, New York 10017 Georgia Institute of Technology Engineering Experiment Station BIOCHEMICAL GLUCOSE PROCESS Atlanta, Georgia . . Hamilton Standard . - • Mr. Leo A. Spano "-•'•' : Division of United Aircraft Corporation Pollution Abatement Division .Windsor.Locks, Connecticut U. S. Army Natick Labs Kansas Street . '• Kemp Reduction Corporation Natick, Massachusetts 01760 2410 Anacapa Santa Barbara, California 93105 PRODUCTION BY ANAEROBIC DIGESTION- Monsanto Enviro-Chem Systems, Inc. 800 N. Lindbergh Blvd. St. Louis, Missouri 63166 Dr. John Pfeffer Rust Engineering Co. Department of Civil Engineering P. O. Box 101 The University of Illinois Birmingham, Alabama 35201 Urbana, Illinois 61801 Torrax Systems, Inc. Dr. D. L. Wise North Tonawanda, New York Cynatech R/D Company A Division of Dynatech Corporation Union Carbide Corporation, Linde Division 99 Erie Street 270 Park Avenue Cambridge, Massachusetts 02139 New York, New York 10017 University of California FIBER RECOVERY EQUIPMENT Sanitary Engineering Research Laboratory Berkeley, California Black Clawson Company University of Southern California 606 Clark Street Department of Environmental Engineering Middletown, Ohio 45042 Los Angeles, California Urban Research and Development Corporation COMPOSTING EQUIPMENT East Granby, Connecticut Wallace Atkins Oil. Corporation Fairfield Engineering Company 2001 Kirby Drive, Suite 906 Marion, Ohio 58466 P. 0. Box 13377 Houston, Texas 77019 West Virginia University Chemical Engineering Department Morgantown, West Virginia ELECTRICITY FROM REFUSE BY TURBINE MEANS

Combustion Power Company 1346 Willow Road Menlo Park, California 94025

FUEL FROM REFUSE PROCESS

237 APPENDIX F GLOSSARY

238 GLOSSARY

Aggregate — hard, inert material of Garbage — includes all putrescible animal graduate fragments for mixing with or vegetable waste resulting from the cementing material to form concrete, preparation, cooking and serving of pavement, etc. food, or the storage and sale of produce Ash — inert particles resulting from combustion Groundwater table — the level of under- ground water used for wells and springs Bimetallic can — a metal container with a body of one metal and at least one Hummus — a dark complex, variable material end of a different metal resulting from partial decomposition of plant or animal matter and forming Biodegradation — decomposition resulting the organic part of the soil from bacterial action Incineration — the process of complete com- Byproduct — a useful process output which bustion is not the primary product Leachate — water which has percolated Char — a solid, carbonaceous product re- through a sanitary landfill sulting from incomplete combustion of the original material MMR •— Mixed Municipal Refuse Clinker— a fused, vitreous product of Mesh — openings in a screen or sieve for complete combustion sizing solid particles. Expressed as the size of the opening (e. g. 1/4- Compost — a mixture consisting (usually) inch) or as the number of openings largely of decayed organic matter and per linear inch of screen (e. g. 28- used for conditioning or fertilizing mesh). land NLC -- National League of Cities Gullet — scrap glass used as part of the feed material in making new glass. Natural gas — gas formed in the ground by To be useful, it must be clean and natural processes free of metallic contaminants, color sorted, and crushed into pieces 2.54 'OSHA ~ Occupational Safety and Health Ad- centimeter (1 inch) or smaller ministration. Also used to refer to the Occupational Safety and Health Act EPA — Environmental Protection Agency of 1970. Fluidized-bed — a bed of solid particles Pre-processing — see Front-end system suspended by an upward flowing gas stream Particulate matter — finely divided particles Fly ash — finely divided ash and other particulate matter carried up the Pollutant -- any type of discharge which stack or chimney of a combustion de- produces undesired environmental con- vice ditions Fossil fuel —-any naturally occurring fuel Product gas — any gas manufactured by an formed by natural processes acting on artificial process organic matter over geologic periods of time, e. g. peat, coal, petroleum, Pulp — wood or paper fibers in a water natural gas slurry used in paper making Frit — the calcined or fused materials Pyrolysis — destructive distillation, or which are the solid output of a py- thermal decomposition, process with- rolysis process out complete combustion Front-end system — all of the steps in Pyrolyzer — reaction vessel in which py- handling MMR from source to the stage rolysis takes place where it is ready for conversion processing by incineration, pyrolysis, PVC — polyvinyl chloride or biodegradation. Also referred to as pre-processing or pre-conversion Recycling — refers to separation and reprocessing. use (possibly with processing) of various components of MMR FWPCA — Federal Water Pollution Control Act of 1970 Refuse — includes all putrescible and

239 nonputrescible solid wastes, including Solid waste— includes all manner of use- garbage, rubbish, rubble, trash, small less, unwanted, or discarded solid or dead animals, ashes, tree limbs, yard semisolid domestic, commercial, indus- clippings, grass cuttings, yard clean- trial, institutional, construction and ings, leaves, solid commercial and demolition waste materials, except hu- industrial wastes, but not including man or rendering wastes • body wastes, junk motor vehicles, special bulky wastes, dirt, or rocks Solid waste management — the purposeful and systematic control of the trans- Residue — material of little or no value portation, storage, separation, pro- remaining after a combustion, conver- cessing, recovery, recycling, and dis- sion, or similar process has been com- posal of solid waste pleted Supplemental fuel — a fuel used to supple- Rubbish — includes all nonputrescible so- ment a primary fuel lid wastes, consisting of both combustible and noncombustible wastes in- Surface water — water existing with its cluding but not limited to, paper, surface exposed to the atmosphere ashes, plastics, cardboard, tin cans, yard clippings, wood, glass, rags, Trade off — sacrificing all or part of discarded clothes or wearing apparel one advantage in order to gain, or of any kind, or any other discarded 'increase, another advantage object or thing, not exceeding three feet in length Trash — includes solid wastes such as ashes, tree limbs, yard clippings, Sanitary landfill — a disposal method in etc., excessive amounts of paper, which solid waste has been buried un- cans, bottles, or other household der at least 6 inches of compacted rubbish and all other things of a soil cover similar nature Scrap — manufactured articles or parts Water-wall — a wall in a combustion de- rejected or discarded and useful only vice made of closely spaced steel as a material for reprocessing tubes welded together with water or steam circulated through the tubes Secondary material — a material that is to extract heat from the combustion utilized in place of a primary or raw ' zone material in manufacturing a product ..'.' Virgin material — a material made from Sensitivity — the extent to which one unused natural resources • variable factor changes when a related factor is changed by one unit

240 ACKNOWLEDGMENTS

241 ACKNOWLEDGMENTS

The 1974 NASA/ASEE Design Institute Fellows are grateful to the following people and organizations for their input to our study: The National Aeronautics and Space Administration for their support of the program and Terry Reese and Barbara Eandi of the Johnson Space Center for their technical assistance and administrative assistance respectively. Dr. Helmut Schulz of Columbia University who provided an invaluable amount of information during a day with us. Browning and Ferris, Inc. who provided us with information and a field trip. Solid Waste Manage- ment, Inc. who arranged for us to attend the NSWMA meeting in Houston. Mr. Jack McDaniel of the City of Houston who provided information and a field trip. Ms. Marie Dalton who introduced us to the concepts of team building which helped us over some rough-spots during the study. Dr. Richard Bailie of West Virginia University who provided much useful information during his day with us. Ms. Pherris Miller who provided invaluable service in handling typing and preparation of our final report.

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