Technologies for Hazardous Waste Management Contents

CHAPTER 5 Technologies for Hazardous Waste Management Contents

Page Page Summary Findings ...... 139 Options for Reduction of Waste Streams Waste Reduction Alternatives , .. ...,, . . . . 139 for VCM Manufacture ...... 144 Hazard Reduction Alternatives: Treatment 25. End-product Substitution for Reduction and Disposal ...... 139 of Hazardous Waste ...... 145 Ocean Use . . + ...... 140 26. Commercially Applied Recovery Uncontrolled Sites...... 140 Technologies ...... 147 27. Description of Technologies Currently Introduction ...... 140 Used for Recovery of Materials ...... 149 Waste Reduction Alternatives ...... 141 28. Recovery/Recycling Technologies Being Introduction ...... 141 Developed ...... 151 Source Segregation ...... 142 29 Conventional Biological Treatment Process Modification ...... 143 Methods ...... 153 End-Product Substitution ...... 144 30 Industries With Experience in Applying Recovery and Recycling ...... 146 Biotechnology to Waste Management . . 153 Economic Factors ...... 148 31 Comparison of Some Hazard Reduction Emerging Technologies for Technologies ...... 157 Waste Reduction...... 151 32. Comparison of Thermal Treatment Technologies for Hazard Reduction . . . ● 163 Hazard Reduction Alternatives: Treatment 33. Engineered Components of Landfills: and Disposal ● *************O.***.*** ● 156 Their Function and Potential Causes Introduction ...... 156 of Failure ...... 177 Summary Comparison ...... 156 34. Comparison of Quoted Prices for Nine Treatment Technologies ...... 158 Major Hazardous Waste Firms in 1981 , 196 Biological Treatment...... 174 35. Incineration v. Treatment: Range of Landfills ...... 174 Estimated Post-RCRA Charges for Surface Impoundments...... 186 Selected Waste Types.. , ...... 197 Underground Injection Wells ...... 189 36. Unit Costs Charged for Services at Comparative Unit Costs for Commercial Facilities ...... 197 Selective Technologies...... 195 37. Data Required To Identify and Evaluate Ocean Disposal and Dispersal ...... 198 Uncontrolled Sites...... 207 Current Usage ● ..***. ● O..**** ...... 198 38. Advantages and Disadvantages of Legislative Background...... 199 Control Technologies ...... 210 Controversy Over Ocean Use for 39. Types of Remedial Action Employed Hazardous Wastes ...... 200 at a Sample of Uncontrolled Sites .*.,* 211 Future Research and Data Needs ...... 203 Technical Regulatory Issues ...... 204 List of Flgures Uncontrolled Sites ● ** ** .***0*0***.O*QQO 205 Issues Concerning Effectiveness ...... 205 Figure No. Page Site Identification and Evaluation ., ....., 207 7. Relative Time Required for Implementation of Reduction Methods . 112 Appendix 5A.-Case Examples of Process 8. Injection Liquid Incineration, ...... 165 Modifications ● *******************e** 213 9, Molten Salt Destruction: Process Diagram 171 10. Generalized Depiction of a Hazardous Waste Landfill Meeting Minimum List of Tables Federal Design Criteria...... ,...... 176 Table No. 11. Potential Failure Mechanisms for Covers 180 22.A Comparison of the Four Reduction 12. Schematic of Single arid Double Synthetic Methods ...,.., ..***,** ,.s.,,.. ● .*, 142 Liner Design .*...** ...*,*** ,..0.... ● 186 23. Process Modification to the Mercury CeIl 144 13. Schematic of Typical Completion Method 24. Advantages and Disadvantage of process for a DeepWaste Injection Well ...... 190 CHAPTER 5 Technologies for Hazardous Waste Management

Summary Findings

Waste Reduction Alternatives not very popular at present, since generators must assume all liability in transferring Source segregation is the easiest and most waste. Also, small firms do not generate economical method of reducing the volume enough waste to make it attractive for re- of hazardous waste. This method of hazard- cycling, ous waste reduction has been implemented in many cases, particularly by large in- Hazard Reduction Alternatives: dustrial firms. Many opportunities still exist for further application. Any change in Treatment and Disposal management practices should include the ● Many waste treatment technologies can pro- encouragement of source segregation. vide permanent, immediate, and very high ● Through a desire to reduce manufacturing degrees of hazard reduction. In contrast, the costs by using more efficient methods, indus- long-term effectiveness of land-based dispos- try has implemented various process modifi- al technologies relies on continued mainte- cations. Although a manufacturing process nance and integrity of engineered structures often may be used in several plants, each and proper operation. For wastes which are facility has slightly different operating condi- toxic, mobile, persistent, and bioaccumula- tions and designs. Thus, a modification re- tive, and which are amenable to treatment, sulting in hazardous waste reduction may hazard reduction by treatment is generally not be applicable industrywide. Also, propri- preferable to land disposal. In general, how- etary concerns inhibit information transfer. ever, costs for land disposal are comparable to, or lower than, unit costs for thermal or ● Product substitutes generally have been developed to improve performance. Hazardous chemical treatment. waste reduction has been a side-benefit, not ● For waste disposal, advanced landfill de- a primary objective. In the long term, end- signs, surface impoundments, and injection product substitution could reduce or elimi- wells are likely to perform better than their nate some hazardous wastes. Because many earlier counterparts. However, there is insuf- different groups are affected by these substi- ficient experience with these more advanced tutions, there are limitations to implementa- designs to predict their performance. Site- tion. and waste-specific factors and continued maintenance of final covers and well plugs ● With regard to recovery and recycling ap- will be important. The ability to evaluate the proaches to waste reduction, if extensive re- effectiveness of these disposal technologies covery is not required prior to recycling a waste constituent, in-plant operations are could be improved through better instrumen- relatively easy. Commercial recovery bene- tation of these facilities. Currently, their per- fits are few for medium-sized generators. No formance evaluation relies heavily on moni- investment is required, but liability remains toring the indirect effects of their failure by, with the generator. Commercial recovery for example, detecting aquifer contamination. has certain problems as a profitmaking en- ● In comparing waste treatment to disposal terprise. The operator is dependent on sup- alternatives, the degrees of permanent haz- pliers’ waste as raw material; contamination ard reduction immediately achievable with and consistency in composition of a waste treatment technologies are overwhelming at- are difficult to control. Waste exchanges are tributes in comparison to land-based dispos-

739 140 ● Technologies and Management Strategies for Hazardous Waste Control

al. However, comparison of these technol- information for decisions concerning most ogies at the very high destruction levels they toxic hazardous wastes and most locations. achieve is difficult. Difficulties include: mon- This is a serious problem since there may itoring methods and detection limits, knowl- be increasing interest in using the oceans as edge about the formation of toxic products the costs of land disposal increase and if pub- of incomplete combustion, and diversity in lic opposition to siting new treatment facil- performance capabilities among the differ- ities continues. ent treatments. Uncontrolled Sites ● Chemical, physical, and biological batch- type treatment processes can be used to re- ● A major problem is that the National Contin- duce waste generation or to recover valuable gency Plan under the Comprehensive Envi- waste-stream constituents. In marked con- ronmental, Response, Compensation, and trast to both incineration and land disposal, Liability Act (CERCLA) does not provide these processes allow checking treatment specific standards, such as concentration residuals before any discharge to the envi- limits for certain toxic substances, to estab- ronment, In general, processes which offer lish the extent of cleanup. There are con- this important added reliability are few, but cerns that cleanups may not provide protec- waste-specific processes are emerging. Re- tion of health and environment over the long search and development efforts could en- term. courage the timely emergence of more of this type process applicable to future haz- ● The long-term effectiveness of remedial tech- ardous wastes. nologies is uncertain. A history of effectiveness has not yet been accumulated. Many Ocean Use remedial technologies consist of waste containment approaches which require long- ● For some acids and very dilute other hazard- term operation and maintenance, In recent ous wastes, dumping in- ocean locations may remedial actions, removal of wastes and con- offer acceptable levels of risk for both the taminants, such as soil, accounted for 40 per- ocean environment and human health. How- cent of the cases; such removed materials ever, there is generally inadequate scientific were usually land disposed.

Introduction

The purpose of this chapter is to describe the tion recognizes that where technically and eco- variety of technical options for hazardous nomically feasible, it is better to reduce the waste management. The technical detail is lim- generation of waste than to incur the costs and ited to that needed for examining policy op- risks of managing hazardous waste. Waste tions and regulatory needs. Still, there are reduction technologies include segregation of many technologies, and their potential roles in waste components, process modifications, end- hazardous waste management are diverse. product substitutions, recycling or recovery Thus, there are many technical aspects related operations, and various emerging technologies. to policy and regulation issues. The reader in- Many waste reduction technologies are close- terested in the details of the technologies rely linked to manufacturing and involve propri- viewed here is encouraged to read beyond this etary information. Therefore, there is less de- policy-oriented discussion. tailed information in this section than in others. The first group of technologies discussed are Much of the chapter discusses technologies those which reduce waste volume. This distinc- that reduce the hazard from the waste gener- Ch. 5— Technologies for Hazardous Waste Management • 141 ated. These are grouped as: 1) those treatments cussion of containment technologies includes: that permanently eliminate the hazardous 1) landfilling, 2) surface impoundments, 3) deep- character of the material, and 2) those dispos- well injection, and 4) chemical stabilization. al approaches that contain or immobilize the hazardous constituents. Use of the oceans is considered a technical option for some wastes. A number of regula- There are several treatments involving high tory and policy issues emerge concerning temperature that decompose materials into ocean use and are discussed. harmless constituents, Incineration is the obvious example, but there are several existing and The final section of this chapter concerns un- emerging “destruction” technologies that are controlled hazardous waste sites from which distinguished in this category. In addition to releases of hazardous materials is probable or gross decomposition of the waste material, has already occurred. Such sites are often aban- there are emerging chemical technologies doned and are no more than open dumps. The which detoxify by limited molecular rearrange- sites are addressed by CERCLA. The technical ment and recover valuable materials for reuse. aspects of identifying, assessing, and remediat- Whether by destruction or detoxification, these ing uncontrolled sites are reviewed in this sec- technologies permanently eliminate the hazard tion. There has been limited engineering expe- of the material. rience with cleaning up uncontrolled sites. Containment chiefly involves land disposal Many technologies that are applicable to the techniques, but chemical “pretreatment” meth- same waste compete in the marketplace. The ods for stabilization on a molecular level are initial discussion in the section on hazard rapidly emerging, Combining these methods of- reduction treatment and disposal technologies fers added reliability, and sectors of industry compares the costs of comparative technolo- appear to be adopting that approach. The dis- gies in some detail.

Waste Reduction Alternatives

Introduction million over 4 years.1 Other firms have established corporate task forces to investigate solu- Four methods are available to reduce the tions to their hazardous waste management amount of waste that is generated: problems, One solution has been recycling and 1. source segregation or separation, recovery of waste generated by one plant for 2. process modification, use as a raw material at another corporate- 3. end-product substitution, and owned facility. Such an approach not only 4. material recovery and recycling. reduces waste, but lowers operating costs. Often, more than one of these approaches is Significant reductions in the volume of waste used, simultaneously or sequentially. generated can be accomplished through source segregation, process modification, end-product Reduction of the amount of waste generated substitution, or recovery and recycle. No one at the source is not a new concept. Several in- method or individual technology can be se- dustrial firms have established in-house incen- lected as the ultimate solution to volume reduc- tive programs to accomplish this. One example tion. As shown in figure 7, three of the meth- is the 3P program—Pollution Prevention Pays— ods, i.e., source segregation, process modifica- of the 3M Corp. Through the reduction of waste and development of new substitute prod- IM. G. Royston, Pollution Prevention Pays (New York: Perga- ucts for hazardous materials, 3M has saved $20 mon Press, 1979). 142 ● Technologies and Management Strategies for Hazardous Waste Control

Figure 7.—Relative Time Required for each of the four approaches is given in table Implementation of Reduction Methods 22. Because of proprietary concerns and lack Source separation of industrywide data, the amount of waste 4 * reduction that has already occurred and the u 2 Process modification potential for further reduction is difficult to % + P evaluate. A 1981 study by California con- E cluded that new industrial plants will produce : Recycling/recovery .— - only half the amount of hazardous waste cur- z * < rently produced. Other estimates for potential End-product substitution waste production range from 30 to 80 percent.3 2 - * Waste reduction efforts, however, are more dif- 1 I I I J o 1 2 3 4 5 ficult in existing plants. (Relative units) Source Segregation Time ~ SOURCE. Off Ice of Technology Assessment Source segregation is the simplest and probably the least costly method of reduction. This tions, and recovery and recycling can be imple- approach prevents contamination of large vol- mented on a relatively short- to medium-term 2“Future Hazardous Waste Generation in California,” Depart- basis by individual generators. End-product ment of Health Services, Oct. 1, 1982. substitution is a longer term effort. A compari- 3Joanna D. Underwood, Executive Director, Inform, The New son of the advantages and disadvantages of York Times, Dec. 27, 1982.

Table 22.—A Comparison of the Four Reduction Methods

Advantages Disadvantages Source segregation or separation I) Easy to implement; usually low investment 1) Still have some waste to manage 2) Short-term solution Process modification 1) Potentially reduce both hazard and volume 1) Requires R&D effort; capital investment 2) Moderate-term solution 2) Usually does not have industrywide impact 3) Potential savings in production costs End product substltuflon 1) Potentially industrywide impact—large 1) Relatively long-term solutions volume, hazard reduction 2) Many sectors affected 3) Usually a side benefit of product improvement 4) May require change in consumer habits 5) Major investments required—need growing market Recovery/recycling ● /n-p/ant 1) Moderate-term solution 1) May require capital investment 2) Potential savings in manufacturing costs 2) May not have wide impact 3) Reduced liability compared to commercial recovery or waste exchange ● Commercial recovery (offsite) 1) No capital investment required for 1) Liability not transferred to operator generator 2) If privately owned, must make profit and return investment 2) Economy of scale for small waste 3) Requires permitting generators 4) Some history of poor management 5) Must establish long-term sources of waste and markets 6) Requires uniformity in composition ● Waste exchange 1) Transportation costs only 1) Liability not transferred 2) Requires uniformity in composition of waste 3) Requires long-term relationships—two-party involvement SOURCE: Office of Technology Assessment. Ch. 5— Technologies for Hazardous Waste Management • 143

umes of nonhazardous waste by removal of have reduced hazardous wastes, the reduction hazardous constituents to forma concentrated usually was not the primary goal of the modifi- hazardous waste, For example, metal-finishing cations. However, as hazardous waste manage- rinse water is rendered nonhazardous by sepa- ment costs increase, waste reduction will be- ration of toxic metals. The water then can be come a more important primary goal. disposed through municipal/industrial sewage Three case examples were studied to analyze systems. incentives and impacts for process modifica- However, there are disincentives, particular- tions for hazardous waste reduction. The fol- ly for small firms wishing to implement source lowing factors are important: segregation. For example, an electroplating ● A typical process includes several steps. firm may, for economic reasons, mix wastes Although a change in one step may be containing cyanides and toxic metals with a small relative to the entire process, the waste that contains organics. The waste stream combination of several changes often rep- is sent to the municipal treatment system. The resents significant reductions in cost, municipal system can degrade the organics, water use, or volume of waste. but the metals and cyanide accumulate in the ● A change in any step can be made inde- sludge, which is disposed as a nonhazardous pendently and is evaluated to determine solid waste in a sanitary landfill. As long as the the impact on product, process efficiency, firm dilutes the cyanide and metals concentra- costs, labor, and raw materials. tions to acceptable limits for municipal dispos- ● Generally, process modifications are plant- al, it is in compliance with the Environmental or process-specific, and they cannot be ap- Protection Agency’s (EPA) regulations. If the plied industrywide. firm calculates the costs of recovering the ● A successful process change requires a cyanide onsite, the cost may be more than the - detailed knowledge of the process as well fees paid to the municipal treatment facility. as a knowledge of alternative materials Thus, there is no economic incentive for source and processing techniques. Successful im- segregation, which would yield a hazardous plementation requires the cooperative ef- waste, although the public would benefit if forts of material and equipment suppliers source segregation were practiced. Alternative- and in-house engineering staffs. ly, accumulation of such sludges can lead to significant levels of toxic material in sanitary Three process changes are discussed in detail landfills. Municipal treatment facilities are fi- in the appendix to this chapter and are briefly nanced with tax dollars, In this example, the summarized below: public is, in essence, subsidizing industrial waste disposal, Moreover, to carry out source 1. Chlor-alkali industry .-Significant proc- segregation, a firm may have to invest in new ess developments in the chlor-alkali indus- equipment. try (which produces, e.g., chlorine and caustic soda) have resulted in reduction of Process Modification major types of hazardous waste through modifications to the mercury electrolysis Process modifications are, in general, made cell. The effects on waste generation are on a continuous basis in existing plants to in- summarized in table 23. The modifications crease production efficiencies, to make product were not developed exclusively to reduce improvements, and to reduce manufacturing hazardous waste, but were initiated pri- costs, These modifications may be relatively marily to increase process efficiency and small changes in operational methods, such as reduce production costs. a change in temperature, in pressure, or in raw 2. Vinyl chloride (plastics) production.— material composition, or may involve major Several process options are available for changes such as use of new processes or new handling waste from the production of equipment. Although process modifications vinyl chloride monomers (VCMs). Five al- 144 . Technologies and Management Strategies for Hazardous Waste Control

Table 23.—Process Modifications to the Mercury Cell

Modification Effect on waste stream Reason for modification Diaphragm cell Elimination of mercury Preferred use of natural salt contaminated waters brines as raw material Dimensionally stable anode Elimination of chlorinated Increased efficiency hydrocarbon waste Membrane cell Elimination of asbestos Reduce energy costs; higher diaphragm,- waste quality product SOURCE Off Ice of Technology Assessment

ternatives are illustrated in table 24. All sludge, the effluent can be discharged di- five have been demonstrated on a commer- rectly to a municipal wastewater treatment cial scale. In most cases, the incineration facility, saving several million dollars in options (either recycling or add-on treat- capital investment. ment) would be selected over chlorinolysis and catalytic fluidized bed reactors. Chlo- End-Product Substitution rinolysis has limited application because of the lack of available markets for the end End-product substitution is the replacement products. If further refinements could be of hazardous waste-intensive products (i.e., in- made to the catalytic process, such as dustrial products the manufacture of which in- higher concentration of hydrogen chloride volves significant hazardous waste) by a new (HCl) in the gas stream which would allow product, the manufacture of which would elim- it to be used with all oxychlorination inate or reduce the generation of hazardous plants, its use could be expanded. waste. Such waste may arise from the ultimate disposal of the product (e.g., asbestos products) 3. Metal-finishing industry .-Several modifications in metal cleaning and plating or during the manufacturing process (e.g., cad- processes have enabled the metal-finishing mium plating). industry to eliminate requirements for on- Table 25 illustrates six examples of end-prod- site owned and operated wastewater treat- uct substitution, each representing a different ment facilities. By changing these proc- type of problem. General problems include the esses to eliminate formation of hazardous following:

Table 24.—Advantages and Disadvantages of Process Options for Reduction of Waste Streams for VCM Manufacture

Treatment option Type Advantages Disadvantages High-efficiency incineration of Add-on treatment 1. Relatively simple operation 1. Second process required to vent gas only 2. Relatively low capital handle liquid waste stream investment High-efficiency incineration Add-on treatment 1. Relatively simple operation 1. Loss of HCI without HCI recovery 2. Relatively low capital investment High-efficiency incineration Recycling 1. Heat recovery 1. Exit gas requires scrubbing with HCI recovery 2. Recover both gaseous and 2. Requires thorough operator liquid components training 3. High reliability 3. Auxiliary fuel requirements Chlorinolysis Modification of 1. Carbon tetrachloride generated 1. High temperatures and process pressures required 2. High capital investment costs 3. Weakening market for carbon tetrachloride Catalytic fluidized bed reactor Recycling 1. Low temperature 1. Limited to oxychlorination 2. Direct recycle of exit gas (no plants treatment required) SOURCE Office of Technology Assessment, Ch. 5— Technologies for Hazardous Waste Management ● 145

Table 25.—End-Product Substitutes for Reduction of Hazardous Waste

Ratio of waste:a Ratio of waste:a Product Use original product Available substitute substitute product Asbestos Pipe 1.09 Iron 0.1 phenols, cyanides, Clay 0.05 fluorides PVC 0.04 VCM manufacture + 1.0 PVC pipe Friction products 1.0+ manufacturing Glass fiber o (brake linings) waste Steel wool Mineral wools Carbon fiber Sintered metals Cement Insulation 1.0+ manufacturing Glass fiber 0.2 Cellulose fiber PCBs Electrical transformers 1.0 Oil-filled transformers 0 Open-air-cooled 0 transformers Cadmium Electroplating 0.29 Zinc electroplating 0.06 Creosote treated wood Piling Concrete, steel 0.0 (reduced hazard) Chlorofluorocarbons Industrial solvents 70/81 =0.9 Methyl chloroform; 0.9 (reduced hazard) methylene chloride DDT Pesticide 1.0+ manufacturing Other chemical (reduced hazard) waste pesticides 1.0+ manufacturing waste aQuantity of hazardous waste generated/unit of product SOURCE Office of Technology Assessment

Not all of the available substitutes avoid For example, increased use of microwave the production of hazardous waste. For ovens has increased the demand for paper and example, in replacing asbestos pipe, the Styrofoam packaging to replace aluminum. use of iron as a substitute in pipe manu- Most end-product substitutions aimed at re- facturing generates waste with phenols and duced generation of hazardous waste, how- cyanides; and also, during the manufacture ever, do not have such advantages. The only of polyvinyl chloride (PVC) pipe, a hazard- benefit may be reduction of potential adverse ous vinyl chloride monomer is emitted.4 effects on human health or the environment, Substitution may not be possible in all Unless the greater risks and costs of hazardous situations. For example, although a sub- waste management are fully internalized by stantial reduction in quantity of hazardous waste generators, other incentives may be waste generated is achieved by using clay needed to accomplish end-product substitution. pipes, clay is not always a satisfactory re- 5 In addition to the approach in chapter 3, op- placement for asbestos. tion III, end-product substitution may be en- Generally, development of substitutes is moti- couraged by: vated by some advantage, either to a user, (e.g., 1. regulations, in improved reliability, lower cost, or easier 2. limitation of raw materials, operation), or to the manufacturer (e. g., re- 3. tax incentives, duced production costs). A change in consum- 4. Federal procurement practices, and er behavior also may cause product changes. 5. consumer education. — ...— — 4Sterling-Hobe Corp., Alternatives for Reducing Hazardous Regulations have been used to prohibit spe- Waste Generation Using End-Product Substitution,prepared for cific compounds. For example, bans on certain Materials Program, OTA, 1982. 5Ibid. pesticides such as dichlorodiphenyltrichloro- 146 . Technologies and Management Strategies for Hazardous Waste Control ethane (DDT) have resulted in development fected by end-product substitution include im- and use of other chemicals. Legislative prohibi- porters of raw materials, exporters of the orig- tion of specific chemicals, such as polychlori- inal product, and related equipment manufac- nated biphenyls (PCBs), is another option. turers. Limiting the supply of raw materials required Generally, a product substitution offers a cost for manufacture is another method of encour- advantage over the original product, which aging end-product substitution. For example, counters market development expenditures. limiting either the importation or domestic Potential savings can be achieved by the intro- mining of asbestos might encourage substitu- duction of product substitutes-e. g., increased tion of asbestos products. A model for this demand may require increased production, method is the marketing-order system of the thus reducing the cost per unit. Incentives or U.S. Department of Agriculture, used to per- the removal of disincentives, however, maybe mit the cultivation of only specified quantities necessary to increase product demand by a suf- of selected crops. Using similar strategies, a ficient margin to give the substitute a more raw material like asbestos could be controlled competitive marketplace position, by selling shares of a specified quantity of the A significant factor in the introduction of a market permitted to be mined or imported. substitute product is the stage of growth for ex- Tax incentives are another means to force isting markets. For example, if the market for end-product substitution. Excise taxes on prod- asbestos brake lining is declining or growing ucts operate as disincentives to consume and at a very slow rate, or if large capital invest- have been implemented in the past (e.g., taxes ments are required for development of a substi- on alcohol, cigarettes and gasoline). This type tute lining, introduction of a substitute may not of taxation might be incorporated to encourage be economically practical. The availability of product substitution. The design and accept- raw materials also affects the desirability of ance of a workable, easily monitored tax sys- substitutes. If the original product is dependent tem, however, might be difficult to develop. on limited supplies of raw materials, substitutes will be accepted more rapidly. Federal procurement practices and product specifications can have significant influence on industrial markets. Changes in military procurement were proposed in 1975 to allow for Recovery and Recycling substitution of cadmium-plating by other materials. A change in product specifications to per- Recovery of hazardous materials from proc- mit this substitution would affect not only the ess effluent followed by recycling provides an quantity of cadmium required for military use, excellent method of reducing the volume of but also might impact nonmilitary applications. hazardous waste. These are not new industrial practices. Recovery and recycling often are A public more aware of the hazard associ- used together, but technically the terms are dif- ated with production of specific products ferent. Recovery involves the separation of a might be inclined to shift buying habits away substance from a mixture. Recycling is the use from them. of such a material recovered from a process Larger Economic Contexts. -If a substitution re- effluent. Several components may be recovered quires a complete shift in industrial markets from a process effluent and can be recycled or (e.g., if a product manufactured with asbestos discarded. For example, a waste composed of is replaced by one made with cement), the im- several organic materials might be processed pact may be large—both manufacturers and by solvent distillation to recover halogenated suppliers may be affected. In addition, users organic solvents for recycling; the discarded will be impacted according to the relative mer- residue of mixed organics might be burned for its of the products. Other sectors potentially af- process heat. Ch. 5— Technologies for Hazardous Waste Management ● 147

Materials are amenable to recovery and re- 2. Commercial (offsite) recovery can be used cycling if they are easily separated from proc- for those wastes combined from several ess effluent because of physical and/or chem- processes or produced in relatively small ical differences. For example, inorganic salts quantities by several manufacturers. Com- can be concentrated from aqueous streams by mercial recovery means that an agent evaporation, Mixtures of organic liquids can other than the generator of the waste is be separated by distillation. Solids can be sepa- handling collection and recovery. These rated from aqueous solutions through filtration. recovery systems may be owned and oper- Further examples of waste streams that are eas- ated by, or simply serve, several waste gen- ily adaptable to recovery and recycling are erators, thereby offering an advantage of listed in table 26, economy of scale. In most cases commercial recovery systems are owned and oper- Recovery and recycling operations can be ated by independent companies, and are divided into three categories: particularly important for small waste gen- 1. In-plant recycling is performed by the erators. In commercial recovery, responsi- waste (or potential waste) generator, and bility for the waste and compliance with is defined as recovery and recycling of raw regulations and manifest systems remains materials, process streams, or byproducts that of the generator until recovery and for the purpose of prevention or elimina- recycling is completed. tion of hazardous waste. (Energy recovery 3. Material exchanges (often referred to as without materials recovery is not included “waste” exchanges) are a means to allow in this discussion of in-plant recycling, raw materials users to identify waste gen- but is discussed later in this chapter as a erators producing a material that could be treatment of wastes.) If several products used. Waste exchanges are listing mecha- are produced at one plant by various proc- nisms only and do not include collection, esses, materials from the effluents of one handling, or processing, Although benefits process may become raw materials for occur by elimination of disposal and treat- another through in-plant recycling. An ex- ment costs for a waste as well as receipt ample is the recovery of relatively dilute of cash value for a waste, responsibility for sulfuric acid, which is then used to neu- meeting purchaser specifications remains tralize an alkaline waste, In-plant recy- with the generator, * cling offers several benefits to the manufacturer, including savings in raw materi- Standard technologies developed that can be adapted for recovery of raw materials or by- als, energy requirements, and disposal or products may be grouped in three general cate- treatment costs, In addition, by reducing or eliminating the amount of waste generated, the plant owner may be exempted *For a discussion of the problems being encountered with using waste exchanges for hazardous waste see “Industrial from some or all RCRA (Resource Conser- Waste Exchange: A Mechanism for Saving Energy and Money,” vation and Recovery Act) regulations, Argonne National Laboratory, July 1982,

Table 26.—Commercially Applied Recovery Technologies

Generic waste Typical source of effluent Recovery technologies Solids in aqueous suspension Salt/soda ash liming operations Filtration Heavy metals Metal hydroxides from metal-plating waste; Electrolysis sludge from steel-pickling operations Organic liquids Petrochemicals/mixed alcohol Distillation Inorganic aqueous solution Concentration of inorganic salts/acids Evaporation Separate phase solids, grease/oil Tannery waste/petroleum waste Sedimentation/skimming Chrome salt solutions Chromium-plating solutions/tanning solutions Reduction Metals; phosphate sulfates Steel-pickling operations Precipitation SOURCE Off Ice of Technology Assessment 148 . Technologies and Management Strategies for Hazardous Waste Control gories. Physical separation includes gravity dation, however, appear to have current com- settling, filtration, flotation, flocculation, and mercial application in hazardous waste man- centrifugation. These operations take advan- agement. tage of differences in particle size and density, Table 28 illustrates some technologies cur- Component separation technologies distin- rently being investigated for application to guish constituents by differences in electrical waste recovery and recycle. An expanded discharge, boiling point, or miscibility. Examples cussion of emerging new technologies, specif- include ion exchange, reverse osmosis, elec- ically in phase separation is provided in the trolysis, adsorption, evaporation, distillation, following section of this chapter. and solvent extraction. Chemical transformation requires chemical reactions to remove specific chemical constituents. Examples in- Economic Factors clude precipitation, electrodialysis, and oxida- These factors include: tion-reduction reactions. These technologies are reviewed in table 27. 1. research and development required prior to implementation of a technology; A typical recovery and recycling system usu- 2. capital investment required for new raw ally uses several technologies in series. There- material, or additional equipment; i.e., re- fore, what may appear as a complex process covery and recycle equipment, control actually is a combination of simple operations. equipment, and additional instrumenta- For example, recylcing steel-pickling liquors tion; may involve precipitation, gravity settling, and 3. energy requirements and the potential for flotation. Precipitation transforms a compo- energy recovery; nent of high volubility to an insoluble substance 4. improvements in process efficiency; that is more easily separated by gravity settling, 5. market potential for recycled material, a coarse separation technique, and flotation, either in-house or commercially, and antic- a finishing separation method, Integration of ipated revenues; process equipment can introduce some com- 6. management costs for hazardous waste be- plexity, The auxiliary handling equipment (e.g., fore use of recovery and recycle technol- piping, pumps, controls, and monitoring de- ogy; vices that are required to provide continuous 7. waste management cost increases, result- treatment from one phase to another) can be ing from recovery/recycling, i.e., addition- extensive. A detailed description of the real manpower, insurance needs, and poten- cycling and recovery of pickling liquors from tial liability; and the steel industry is provided in the appendix 8. the value of improved public relations of at the end of this chapter, a firm. Recovery and recycling technologies applied Because of the number of processing steps in- to waste vary in their stages of development. volved, recovery and recycling can be more ex- Physical separation techniques are the most pensive than treatment and disposal methods. commonly used and least expensive. The sepa- Earned revenue for recovered materials, how- ration efficiency of these techniques is not as ever, may counter the cost of recovery. high as more complex systems, and therefore the type of waste to which it is applied is lim- Many market and economic uncertainties ited. Complex component separations (e.g., re- must be considered in an evaluation of pro- verse osmosis) are being investigated for appli- posed technology changes. For example, if de- cation to hazardous waste. These generally are regulation of oil and natural gas results in an expensive operations and have not been imple- increase in energy costs, additional energy re- mented commercially for hazardous waste requirements, and/or credits earned for energy duction. Chemical transformation methods are recovery from a process could be affected. The also expensive. Precipitation and thermal oxi- uncertainty of continued availability of a nec- Table 27.—Description of Technologies Currently Used for Recovery of Materials — . . . Technology/description stage of development Economics Types of waste streams Separation efficiency Industrial applications Physical separation: Gravity settling: Tanks, ponds provide hold-up Commonly used in Relatively inexpensive; Slurrries with separate phase Limited to solids (large industrial wastewater time allowing solids to wastewater dependent on particle size solids, such as metal particles) that settle quickly treatment first step settle; grease skimmed to treatment and settling rate hydroxide (less than 2 hours) overflow to another vessel Filtration: Collection devices such as Commonly used Labor intensive: relatively Aqueous solutions with finely Good for relatively large Tannery water screens, cloth, or other; inexpensive; energy divided solids; gelatinous particles liquid passes and solids required for pumping sludge are retained on porous media Flotation: Air bubbled through Iiquid to Commercial Relatively inexpensive Aqueous solutions with finely Good for finely divided solids Refinery (oil/water mixtures); collect finely divided solids application divided solids paper waste; mineral that rise to the surface industry with the bubbles Flocculation: Agent added to aggregate Commercial practice Relatively inexpensive Aqueous solutions with finely Good for finely divided solids Refinery; paper waste; mine solids together which are divided solids industry easily settled Centrifugation: Spinning of liquids and Practiced commer- Competitive with filtration Liquid/liquid or liquid/solid Fairly high (90°/0) Paints centrifugal force causes cially for small- separation, i.e., oil/water; separation by different scale systems resins; pigments from densities lacquers Component separation Distillation: Successfully boiling off of Commercial practice Energy intensive Organic Iiquids Very high separations Solvent separations;

0 materials at different achievable (99 + /0 chemical and petroleum temperatures (based on concentrations) of several industry different boiling points) components Evaporation: Solvent recovery by boiling Commercial practice in Energy intensive Organic/inorganic aqueous Very high separations of Rinse waters from metal- off the solvent many industries streams; slurries, sludges, single, evaporated plating waste i.e., caustic soda component achievable ion exchange: Waste stream passed through Not common for HW Relatively high costs Heavy metals aqueous Fairly high Metal-plating solutions resin bed, ionic materials solutions; cyanide removed selectively removed by resins similar to resin adsorption. Ionic exchange materials must be regenerated Ultrafiltration: Separation of molecules by Some commercial Relatively high Heavy metal aqueous Fairly high Metal-coating applications size using membrane application solutions Reverse osmosis: Separation of dissolved Not common: growing Relatively high Heavy metals; organics, Good for concentrations Not used Industrially materials from liquid number of applications inorganic aqueous solutions less than 300 ppm through a membrane as secondary treatment process such as metal-plating pharmaceuticals Table 27.—Description of Technologies Currently Used for Recovery of Materials—Continued

Technology/description Stage of development Economics Types of waste streams Separation efficiency Industrial applications Electrolysis: Separation of positively/ Commercial technology; Dependent on concentrations Heavy metals; ions from Good Metal plating negatively charged not applied to recovery aqueous solutions; copper materials by application of of hazardous materials recovery electric current Carbon/resin absorption: Dissolved materials Proven for thermal Relatively costly thermal Organics/inorganics from Good, overall effectiveness Phenolics selectively absorbed in regeneration of regeneration; energy aqueous solutions with low dependent on carbon or resins. carbon; less practical intensive concentrations, i.e., phenols regeneration method Absorbents must be for recovery of regenerated adsorbate Solvent extraction: Solvent used to selectively Commonly used in Relatively high costs for Organic liquids, phenols, acids Fairly high loss of solvent Recovery of dyes dissolve solid or extract industrial processing solvent may contribute to liquid from waste hazardous waste problem Chemical transformation: Precipitation: Chemical reaction causes Common Relatively high costs Lime slurries Good Metal-plating wastewater formation of solids which treatment settle Electrodialysis: Separation based on Commercial technol- Moderately expensive Separation/concentration of Fairly high Separation of acids and differential rates of ogy, not commer- ions from aqueous streams; metallic solutions diffusion through cial for hazardous application to chromium membranes. Electrical material recovery recovery current applied to enhance ionic movement Chlorinolysis: Pyrolysis in atmosphere of Commercially used in Insufficient U.S. market for Chlorocarbon waste Good Carbon tetrachloride excess chlorine West Germany carbon tetrachloride manufacturing Reduction: Oxidative state of chemical Commercially applied Inexpensive Metals, mercury in dilute Good Chrome-plating solutions changed through chemical to chromium; may streams and tanning operations reaction need additional treatment Chemical dechlorination: Reagents selectively attack Common Moderately expensive PCB-contaminated oils High Transformer oils carbon-chlorine bonds Thermal oxidation: Thermal conversion of Extensively practiced Relatively high Chlorinated organic liquids; Fairly high Recovery of sulfur, HCI components silver aGood implies 50 to 8O percent efficiency, fairly high implies 80 percent, and very high Implies 90 percent SOURCE: Office of Technology Assessment. Ch. 5— Technologies for Hazardous Waste Management ● 151

Table 28.—Recovery/Recycling Technologies Being Developed

Technology Development needs Potential application Ion exchange Commercial process for other Chromium recovery; metal applications (desalinization), plating waste applications to metal recovery under development. Not economic at present due to investment requirements Adsorption R&D on new resins and Organic liquids with or without regeneration methods metal contamination; pesticides Electrolysis Cathode/anode, material Metallic/ionic solution development for membranes Extract ion Reduction in loss of acid or Extraction of metals with acids solvent in process Reverse osmosis Membrane materials, operating Salt solutions conditions optimized, demonstration of process Evaporation Efficiency improvement/ Fluorides from aluminum demonstration of process smelting operation Reduction Efficient collection techniques Mercury Chemical Equipment development for Halogenated organics dehalogenation applications to halogenated waste other than PCB oils SOURCE Off Ice of Technology Assessment

essary raw material could influence a decision broader scale. Recycling within the corporate for recovery of materials from waste streams. framework is gaining greater attention as a cost Uncertainties in interest rates may discourage reduction tool with an added benefit of reduc- investment and could thus increase a required ing public health risks. rate-of-return projected for a new project. Changes in allowable rates of capital equipment depreciation also may affect costs signif- Emerging Technologies for Waste Reduction icantly. Although the effects are more difficult to pre- In addition, changes in RCRA regulations for dict, some technological developments have alternative management options (e.g., landfill- potential for the reduction of hazardous waste, ing, ocean dumping, and deep-well injection) For example, developments in the electronics affect disposal costs. Stricter regulations or industry have provided instrumentation and prohibitions of certain disposal practices for control systems that have greater accuracy particular wastes could increase the attractive- than was possible just a few years ago. These ness of recycling and recovery operations. systems provide more precise control of proc- However, if hazardous wastes are stored for ess variables, which can result in higher effi- longer than 90 days, current regulations re- ciency and fewer system upsets, and a reduc- quire permits for that facility. If large quantities tion in hazardous waste. The application and of a waste must accumulate (for economic rea- improvements of instrumentation and control sons) prior to recycling or recovery, the per- systems vary with each process. Thus, as new mit requirement may discourage onsite re- plants are constructed and fitted with new cycling, technologies, smaller quantities of hazardous Previously, recovery and recycling was con- waste will be generated. The technologies that sidered as an in-plant operation only; i.e., mate- are discussed in this section have a direct im- rial was recovered and recycled within one pact on the volume and hazard level of waste plant. Currently, larger corporations are begin- currently generated through one or more of the ning to evaluate recovery opportunities on a reduction methods discussed earlier. 152 ● Technologies and Management Strategies for Hazardous Waste Control

Segregation Technology .—New developments in The major cost in a membrane separation segregation technology can increase recovery system is the engineering and development and recycling of hazardous waste. Notably, work required to apply the system to a particu- membrane segregation techniques have sub- lar process. Equipment costs are secondary; stantially improved, Membrane separation has membranes generally account for only 10 per- been used to achieve filtration, concentration, cent of system costs. However, membranes and purification. However, large-scale applica- must be replaced periodically and sales of re- tions, such as those required in pollution con- placement membranes are important to mem- trol have been inhibited by two factors: 1) re- brane production firms. Currently the largest placement costs associated with membrane use profit items are for high-volume flow situations and 2) technical difficulties inherent in produc- (e.g., water purification) or for high-value prod- ing large uniform surface areas of uniform uct applications (e. g., pharmaceutical produc- quality. Because of the inherent advantages of tions). Over 20 companies cover the membrane membrane separation over more conventional market; the largest company is Millipore with separation techniques like distillation or evapo- 1980 total sales of $255 million. ration, further development of membrane sep- The predicted market growth rate for mem- aration for large-scale commercial applications brane segregations is healthy, generally 10 to is attractive. These advantages include lower 20 percent annually of the present membrane energy requirements resulting in reduced oper- market ($600 million to $950 million). Chlor- ating costs and a simpler, more compact sys- alkali membrane electrodialysis cells for the tem that generally leads to reduced capital production of chlorine and sodium hydroxide costs. Commercial applications exist for all but lead the projected application areas in hazard- coupled transport designs, which are still at the ous waste with growth rates of 25 to 40 per- laboratory stage. All of these illustrated systems cent of the present market ($10 million to $15 have possible application for reduction of haz- million), The recovery of chromic acid from ardous waste. However, microfiltration, ultra- electroplating solutions by coupled transport filtration, reverse osmosis, and electrodialysis also has direct application for the reduction of processes have more immediate application, hazardous waste. Other uses include ultrafiltra- Dialysis has been used on only a small scale; tion of electrocoat-painting process waste and the high flow systems generally typical of haz- waste water recovery by reverse osmosis. The ardous waste treatments make its use imprac- use of membrane segregation systems in pre- tical. Gas separations by membranes do not treatment of hazardous waste probably is the have immediate application to hazardous waste largest application for the near future. use. The development of new materials for both membranes and supporting fabrics and the use of new layering techniques (e. g., composite Biotchnology.-Conventional biological treat- membranes) have led to improved permeability ments have been used in industrial waste treat- and selectivity, higher fluxes, better stability, ment systems for many years (see tables 29 and and a reduced need for prefiltering and staged 30). Recent advances in the understanding of separations. biological processes have led to the develop- Improved reliability is the most important ment of new biological tools, increasing the op- factor in advancement of membrane separa- portunities for biotechnology applications in tions technology. New types of membranes many areas, including the treatment of dilute have demonstrated improved performance, hazardous waste. The potential impacts of Thin-film composites that can be used in these advancements on waste treatment tech- reverse osmosis, coupled transport, and elec- niques, process modifications, and end-product trolytic membranes have direct application to substitutes are discussed here. the recovery and reduction of hazardous mate- Biotechnology has direct application to waste rials from a processing stream. treatment systems to degrade and/or detoxify Ch. 5— Technologies for Hazardous Waste Management • 153

Table 29.—Conventional Biological Treatment Methods

Aerobic (A) Treatment method anaerobic (N) Waste applications Limitations Activated sludge A Aliphatics, aromatics, petrochemicals, Volatilization of toxics; sludge disposal steel making, pulp and paper industries and stabilization required Aerated lagoons A Soluble organics, pulp and paper, Low efficiency due to anaerobic zones; petrochemicals seasonal variations; requires sludge disposal Trickling filters A Suspended solids, soluble organics Sludge disposal required Biocontactors A Soluble organics Used as secondary treatment Packed bed reactors A Vitrification and soluble organics Used as secondary treatment Stabilization ponds A&N Concentrated organic waste Inefficient; long retention times, not applicable to aromatics; sludge removal and disposal required Anaerobic digestion N Nonaromatic hydrocarbons; high-solids; Long retention times required; inefficient methane generation on aromatics Land farming/spreading A Petrochemicals, refinery waste, sludge Leaching and runoff occur; seasonal fluctuations; requires long retention times Comporting A Sludges Volatilization of gases, leaching, runoff occur; long retention time; disposal of residuals Aerobic—requires presence of oxygen for cell growth Anaerobic—requ!res absence of oxygen for cell growth SOURCE Off Ice of Technology Assessment

Table 30.–lndustries With Experience in Applying Biotechnology to Waste Management

Industry Effluent stream Major contaminants Steel Coke-oven gas scrubbing NH3, sulfides, cyanides, phenols operation Petroleum refining Primary distillation process Sludges containing hydrocarbons Organic chemical Intermediate organic Phenols, halogenated hydrocarbons, manufacture chemicals and byproducts polymers, tars, cyanide, sulfated hydrocarbons, ammonium compounds Pharmaceutical manufacture Recovery and purification Alcohols, ketones, benzene, xylene, solvent streams toluene, organic residues Pulp and paper Washing operations Phenols, organic sulfur compounds, oils, Iignins, cellulose Textile Wash waters, deep discharges Dyes, surfactants, solvents SOURCE Office of Technology Assessment chemicals. Development of new microbial 5. ability to concentrate nondegradable constrains can be used to improve: stituents. 1. degradation of recalcitrant compounds, Compounds thought to be recalcitrant, (e.g., 2. tolerance of severe or frequently changing toluene, benzene, and halogenated compounds) operating conditions, have been shown to be biodegradable by iso- 3. multicompound destruction, lated strains. Strain improvement in these 4. rates of degradation, and species through genetic manipulations has lead 154 . Technologies and Management Strategies for Hazardous Waste Control

to improved degradation rates. Opportunities directed toward development of crops that can exist for applications of this technology in tolerate the presence of metal without incorpo- remedial situations—i.e., cleanup at spills or rating these toxic elements in plant tissue. Fi- abandoned sites.67 The improvement of con- nally, research is being conducted concerning ventional biological systems through the devel- the use of plants in a manner similar to micro- opment of specific microbial strains (“super- organisms to degrade high concentrations of bugs”) capable of degrading multiple com- hazardous constituents. pounds has been proposed. However, this ap- Changes in process design incorporating ad- proach faces engineering difficulties, and de- vances in biological treatment systems may velopment of collections of organisms work- result in less hazardous waste, The developing together might be preferable. ment of organisms capable of degrading specif- Development of biological pretreatment sys- ic recalcitrant materials may encourage source tems for waste streams has some potential for separation, treatment, and recycling of process those wastes that contain one or two recalci- streams that are now mixed with other waste trant compounds. A pretreatment system de- streams and disposed. The replacement of signed to remove a specific toxic compound chemical synthesis processes with biological could reduce the shock effects on a conven- processes may result in the reduction of haz- tional treatment process. In some cases, a pre- ardous waste. Two methods of increasing the treatment system may be used with other non- rate of chemical reactions are through higher biological treatment methods (i.e., incineration) temperatures and catalysts. One type of cata- to remove toxic compounds that may not be lyst is biological products (enzymes) that inher- handled in the primary treatment system or to ently require milder, less toxic conditions than make them more readily treated by the primary do other catalytic materials. system. In other cases, pretreatment might Historically, many biological processes (fer- render a waste nonhazardous altogether. mentations) have been replaced by chemical One area of research in advanced plant ge- synthesis. Genetic engineering offers oppor- netics is in the use of plants to accumulate tunities to improve biological process through metals and toxic compounds from contami- reduced side reactions, higher product concen- nated soils. Current research is direct to four trations, and more direct routes; thus, genetic areas. The first involves use of plants to de- engineering offers a means of partially rever- crease the metal content of contaminated soils, sing this trend. The development of new proc- through increased rates of metal uptake. Plants ess approaches would require new reactor de- then could be used to decontaminate soils signs to take advantage of higher biological re- through concentration of compounds in the action rates and concentrations. plant fiber. The plants then would be harvested Biotechnology also could lead to substitution and disposed. The second area of development of a less or nonhazardous material for a hazard- focuses on direct metal uptake in nonedible ous material, particularly in the agricultural portions of the plant. For example, the develop- field. One of the primary thrusts of plant gen- ment of a grain crop like wheat that could ac- etics is the development of disease-resistant cumulate metal from soil in the nonusable parts plants, thus reducing the need for commercial of the plant would allow commercial use of products such as fungicides. Genetic engineer- contaminated land. A third area of research is ing to introduce nitrogen-fixation capabilities G. T. Thibault and N. W. Elliott, “Biological Detoxification within plants could reduce the use of chemical of Hazardous Organic Chemical Spills, ” in Control of Hazard- ous Material Spills, Conference Proceedings (Nashville, Term.: fertilizers and potentially reduce hazardous Vanderbilt University, 1980), pp. 398402. waste generated in the manufacture of those ‘G. C. Walton and D. Dobbs, “Biodegradation of Hazardous chemicals. However, two problems must be re- Materials in Spill Situations, “ in Control of Hazardous Material Spills Conference Proceedings [Nashville, Term.: Vanderbilt solved before large-scale applications: 1) the University, 1980), pp. 2345. genetic engineering involved in nitrogen fixa- Ch. 5— Technologies for Hazardous Waste Management ● 155 tion is complex and not readily achieved, and made public its method, Sunohio and Acurex Z) the overall energy balance of internal nitro- Inc. have developed proprietary reagents, mod- gen-fixation may reduce growth rates and crop ified the process, and commercialized their yield. processes with mobile units. These processes reduce the concentration of PCB in transform- Major Concerns for Biotechnology.–Although er oil, which may be 50 to 5,000 parts per mil- genetic engineering has some promising appli- lion (ppm) to less than 2 ppm. The Sunohio cations in the treatment of hazardous waste PCBX process is used for direct recycling of streams, several issues need to be addressed the transformer oil back into transformers, prior to widespread commercialization of the 8 while the oil from the Acurex process is used technology: 9 as a clean fuel in boilers. ● The factors for scale-up from laboratory Although, the development of these proc- tests to not industrial applications have esses was initially aimed at PCB-laden oils of been completely developed. Limited field moderate concentration (50 to 500 ppm), their tests have shown degradation rates in the chemistry is generic in that it attacks the car- field may be much slower than laboratory bon-halogen bonds under mild conditions, rates where pure cultures are tested in Thus, they are potentially applicable to pesti- pure compounds. cides and other halogenated organic wastes as ● Basic biochemical degradation mecha- well as wastes with higher concentrations of nisms are not well understood, The poten- PCBs. The PCBX process has been applied to tial exists for the formation of other haz- pesticides and other halogenated waste with ardous compounds through small environ- detoxification observed, but without published mental changes or system upsets and, numerical results or further developments.10 without this basic understanding, chemi- Acurex claims it has commercially treated oil cal pathways cannot be anticipated. with a PCB concentration of 7,000 ppm. In ● The potential exists for release of hazard- tests performed by Battelle Columbus Labora- ous compounds into the environment tories for Acurex, its process reduced dioxin through incomplete degradation or system concentration in transformer oil from 380 parts failure. per trillion (ppt) to 40 ± 20 ppt. Acurex and ● There is a possibility of adverse effects re- the Energy Power Research Institute have sulting fro-m the release of “engineered” tested the effectiveness of the process in the into the environment. organisms laboratory on capacitors which contain 100 The potential benefits of applied genetics to percent PCB (40 to 50 percent chlorine, by hazardous waste probably outweigh these fac- weight). The next step is construction of a tors. Although these factors must be addressed, mobile commercial-scale facility which would they should motivate rather than overshadow shred, batch process, and test the capacitor research in this area. material .11 Chemical Dechlorination With Resource Recovery.– The Sunohio (first to have a chemical dechlo- In the late 1970’s private efforts were under- rination process approved by EPA) has five taken to find a reagent that would selectively units in operation. Acurex has four mobile attack the carbon-chlorine bond under mild units in operation at this time and at least two conditions, and thus chemically strip chlorine other companies currently market similar from PCB-type chemicals forming a salt and chemical PCB destruction services. Acurex, an inert sludge. Goodyear Tire & Rubber Co. @Alternatives to the Land Disposal of Hazardous Wastes, Gov- W. p. pirages, L. M. Curran, and J. S. Hirschhorn, “Biotech- ernor’s Office of Appropriate Technology, California, 1981, nology in Hazardous Waste Management: Major Issues, ” paper Klscar Norman, developer of the PCBX process, personal presented at The Impact of Applied Genetics on Pollution Con- communication, January 1983. trol symposium sponsored by the University of Notre Dame and llLeo Weitzman, Acurex Corp., personal communication, Hooker Chemical Co., South Bend, Ind., May 24-26, 1982. January 1983. 156 . Technologies and Management Strategies for Hazardous Waste Control

Sunohio, and licensees have been selling their As an alternative to incineration, these chem- PCB services for over a year. Acurex and The ical processes offer the advantages of no air Franklin Institute plan to commercialize their emissions, no products of incomplete combus- processes for spill sites involving halogenated tion, reduced transportation risks, and the re- organics. 12 cycling of a valuable material or the recovery of its fuel value. Further, as with many chem- l=harles Rogers, Office of Research and Development, Indus- ical processes, there is t-he opportunity to di- and Environmental Research Laboratory (IERL), Environ- trial rectly check the degree of destruction before mental Protection Agency, Cincinnati, Ohio, personal, com- . . . . munication, January 1983. any product is discharged or used.

Hazard Reduction Alternatives: Treatment and Disposal

Introduction human and environmental exposure to waste. In this category, the major techniques are land- The previous section discussed technologies fills, surface impoundments, and underground to reduce the volume of waste generated. This injection wells. section analyzes technologies that reduce the hazard of waste. These include treatment and This discussion begins with a comparison of disposal technologies. These two groupings the treatment and disposal technologies and of technologies contrast distinctly in that it ends with a cost comparison. These discus- is preferable to permanently reduce risks to sions focus on the competitive aspects of the human health and the environment by waste numerous hazard reduction technologies. treatments that destroy or permanently re- However, choosing among these technical al- duce the hazardous character of the material, ternatives involves consideration of many fac- than to rely on long-term containment in tors, some of which are neither strictly tech- land-based disposal structures. nical or economic. Choices by waste generators and facility operators also depend on Federal In the United States, as much as 80 percent and State regulatory programs already in place, (by volume) of the hazardous waste generated those planned for the future, and on percep- is land disposed (see ch. 4). Of these wastes, tions by firms and individuals of existing regu- a significant portion could be treated rather latory burdens may exist for a specific waste, than land disposed for greater hazard reduc- technology, and location. tion. In California, for example, wastes which are toxic, mobile, persistent and bioaccumulative comprise about 29 percent of the hazard- Summary Comparison ous waste disposed of offsite.13 14 For the purpose of an overview, qualitative Following a brief summary comparison, this comparisons among technologies can be made. section reviews over 15 treatment technologies. Based on principle considerations relevant Many of these eliminate the hazardous char- across all technologies, the diverse range of acter of the waste. Technologies in the next hazard reduction technologies can be com- group discussed are disposal alternatives. Their pared as presented in table 31. The table sum- effectiveness relies on containing the waste to marizes the important aspects of the above prevent, or to minimize, releases of waste and issues for each generic grouping of technologies included. Individual technologies are WMifbmia Department of Health Services, “Initial Statement considered in more detail in the following dis- of Reaaona for Proposed Regulations (R-32 -82),” Aug. 18, 1982, cussions on treatment and disposal technol- p. 23. WaIifomia Department of Health Services, “Current Hazard- ogies. For simplicity, the technologies are ous Waste Generation,” Aug. 31, 1982, p. 6. grouped generically, and only a limited number Ch. 5— Technologies for Hazardous Waste Management ● 157

Table 31 .—Comparison of Some Hazard Reduction Technologies

Treatment Disposal Emerging- Landfills and Incineration and other high.temperature Impoundments Injection wells thermal destruction decomposition a Chemical stabilization Effectiveness How well It Low for volatiles, High, based on theory, High, based on field tests, Very high, commercial High for many metals, contains or destroys questionable for Iiquids but limited field data except little data on scale tests based on lab tests hazardous based on lab and field available specific constituents characteristics tests Reliability issues: Siting, construction, and Site history and geology, Long experience with Limited experience Some inorganics still operation well depth, construction design Mobile units, onsite soluble Uncertainities Iong-term and operation Monitoring uncertainties treatment avoids Uncertain Ieachate test, integrity of cells and with respect to high hauling risks surrogate for weathering cover, Iiner life less degree of DRE, Operational simplicity than life of toxic waste surrogate measures, PICs, incinerability Envirornmental media Surface and ground water Surface and ground water Air Air None Iikely most affected Least compatible Liner reactive, highly toxic, Reactive, corrosive, Highly toxic and refractory Possibly none Organics waste: b mobile, persistent, highly toxic, mobile, organics, high heavy and bioaccumulative and persistent metals concentration Costs LOW, Mod, High L-M L M-H (Coincin = L) M-H M Resource recovery potential None None Energy and some acids Energy and some metals Possible building material — . a Molte n sal t,high.temperature fluid wall, and plasma arc treatments b Waste for which this method may be less effective for reducing exposure, relative to other technologies Waste listed do not necessarily denote common usage SOURCE Office of Technology Assessment of groups are compared, The principal consid- cause they provide faster and/or cheaper erations used for comparison are the following: performance information, A disadvantage Effectiveness.—This does not refer to the of surrogate measures is that there may not intended end result of human health and be reliable correlation between the surro- environmental protection, but to the capa- gate measurement and the nature of any bility of a technology to meet its specific releases to the environment. technical objective. For example, the effec- The reliability of a technology should tiveness of chemical dechlorination is de- also be judged on the degree of process termined by how completely chlorine is re- and discharge control available. This removed. In contrast, the effectiveness of fers to the ability to: 1) maintain proper landfills is determined by the extent to operating conditions for the process, and which containment or isolation is achieved. 2) correct undesirable releases. Process Reliability .—This is the consistency over control requires that information about time with which a technology’s objective performance be fed back to correct the is met, Evaluation of reliability requires process. Control systems vary categorical- consideration of available data based on ly with respect to two important time vari- theory, laboratory-scale studies, and com- ables: mercial experience. 1. the length of time required for infor- A prominent factor affecting the relative mation to be fed back into the system reliability of a technology is the adequacy (e.g., time for surrogate sampling and of substitute performance measures. Veri- analysis, plus time for corrective ad- fication that a process is performing as de- justments to have the desired effect); signed is not always possible and, when and possible, verification to a high level of con- 2. the length of time for release of dam- fidence may require days or weeks to com- aging amounts of insufficiently treated plete and may not be useful for timely ad- materials in the event of a treatment justments. In some cases, key process vari- upset. ables can be used as substitute measures In the case of landfills, once ground water for the effectiveness of the technology. monitoring has detected a leak, damaging Substitute measures are used either be- discharges could have already occurred. 158 . Technologies and Management Strategies for Hazardous Waste Control

If detection systems are embedded in the down the hazardous wastes into nonhazardous liner, then detection of a system failure is constituents. * Most of these treatments use quicker and more reliable, and it offers high temperatures to decompose waste. Some more opportunity for correction. Landfill- of the promising emerging technologies cause ing and incineration are examples where decomposition by high-energy radiation and/or these time factors are important. In con- electron bombardment. There are several im- trast, batch treatment processes, as dis- portant attributes of high-temperature destruc- cussed in the preceding section on “Waste tion technologies which make them attractive Reduction,” offer the distinct opportunity for hazardous waste management: to contain and check any release, and re- ● the hazard reduction achieved is perma- treat it if needed, so that actual releases nent; of hazardous constituents are prevented. ● they are broadly applicable to waste Other chemical and biological treatments mixes; most organics, for example, may are flow-through processes, with different rates of flow-through. These treatments be converted into nonhazardous combus- vary in their opportunity for discharge cor- tion products; and ● the volume of waste that must ultimately rection. Generally, processes used in waste - segregation and recycling offer this kind be land disposed is greatly reduced, of reliability. In addition, with some of these treatments, ● Environmental media most affected.— there is a possibility of recovering energy and/ This refers to the environmental media or materials.** However, potential recovery of contaminated in the event that the technol- energy and materials is not the primary focus ogy fails. of this discussion. ● Least compatible waste.—Some technologies are more effective than others in pre- Incineration is the predominant treatment venting releases of hazardous constituents technology used to decompose waste. The term when applied to particular types of waste. “incineration” has been given a specific meaning in Federal regulations, where it denotes a ● Costs.—Costs vary more widely among generic groups of technologies than within particular subclass of thermal treatments, and these groups. Table 31 presents general- draft Federal regulations may give specific ized relative costs among these groups. meaning to the additional terms “industrial The final section of this chapter gives some boiler” and “industrial furnace.” Although the unit management cost details. Federal definitions affect the manner in which a facility is regulated, unless specifically noted, ● Resource recovery potential.—Treatments that detoxify and recover materials for re- —— ● Treatments can also be used to segregate specific waste con- cycling are discussed under “Waste Re- stituents, or to mitigate their characteristics of ignitability, cor- duction.” However, some materials, as rosiveness, or reactivity. Most of these are referred to as “indus- well as energy, can be recovered with trial unit processes, ” and their use is usually embedded in larger treatment schemes. A lengthy listing will not be reproduced here. some of the technologies reviewed in this Many were described in the preceding section on “Waste Reduc- section. To the extent that materials and tion Technologies. ” The interested reader is also referred to any fuels are recovered and used, the genera- industrial unit operations manual. Another source is “Chemical, Physical, Biological (CPB) Treatment of Hazardous Wastes, ” Ed- tion of other hazardous wastes maybe re- ward J. Martin, Timothy Oppelt, and Benjamin Smith, Office duced. Potential releases of hazardous of Solid Waste, U.S. Environmental Protection Agency, pre- constituents from recovery and recycling sented at the Fifth United States-Japan Governmental Conference operations must also be considered, of Solid Waste Management, Tokyo, Japan, Sept. 28, 1982. ● *For example, the Chemical Manufacturers Association claims that a significant portion of the hydrochloric acid produced in the United States and some sulfuric acid come from Treatment Technologies incineration of chlorinated organics through wet-scrubbing of the stack gases. (CMA, personal communication, December In this section, treatment technologies refers 1982.) Also, there is clear potential for metals recovery with the to those techniques which decompose or break emerging high-temperature technologies. Ch. 5—Technologies for Hazardous Waste Management ● 159

“combustion” or “incineration” are used in of these facilities may eventually be permitted this report to refer to the generic processes of as RCRA hazardous waste incinerators. A far interest, and do not necessarily mean specific greater, although unknown, number of facili- facility designs or regulatory categories. ties may be combusting hazardous waste prin- cipally in order to recover their heating value. Applicable Wastes Under current regulations, these facilities Liquid wastes are generally more easily in- would not be permitted as hazardous waste incinerators.” Under future regulations they cinerated than sludge or waste in granular form, because they can be injected easily into may become subject to performance standards similar to those in effect for incinerators, be the combustion chamber in a manner which enhances mixing and turbulence. Wastes with prohibited from burning certain types of ignit- heterogeneous physical characteristics and able hazardous waste, or be subject to some intermediate level of regulation. containerized or drummed wastes are difficult to feed into a combustion chamber. The rotary To regulate incinerators, EPA has decided kiln is designed for sludge-like, granular and to use performance standards rather than some containerized waste. Recently, a new specification of design standards. The current firm has emerged (Continental Fibre Drum) regulations specify three performance stand- which manufactures combustible fiber drums ards for hazardous waste incineration. 18 These for waste containers. These fiber drums of or- standards are described below: ganic waste can be incinerated in specially 1. A 99.99 percent destruction and removal designed rotary kilns. efficiency (DRE) standard for each prin- Elemental metals, of course, cannot be de- cipal organic hazardous constituent graded. Waste which contain excessive levels (POHC) designated in the waste feed. (This of volatile metals may not be suitable for incin- is the most difficult part of the standard eration. Under the high-temperature conditions to meet.) The DRE is calculated by the fol- in an incinerator, some metals are volatilized lowing mass balance formula: or carried out on particulate. Oxides of metals DRE = (1 – Wout/Win) X 100 percent, can generally be collected electrostatically. where: However, some volatilized forms cannot be Win = the mass feed rate of 1 POHC electrically charged, resisting electrostatical in the waste stream going into the collection. These include metallic mercury, incinerator, and arsenic, antimony, and cadmium, and very Wout = the mass-emission rate of the small particles.15 (Particles having insufficient same POHC in the exhaust prior to surface area also can’t be adequately charged release to the atmosphere. and collected, ) Wet second-stage electrostatic 2. Incinerators that emit more than 4 lb of precipitators are designed for removing these hydrogen chloride per hour must achieve forms of volatized metals, but they are expen- a removal efficiency of at least 99 percent. sive and not in widespread use. High-pressure (All commercial scrubbers tested by EPA drop-emission controllers have also been effec- have met this performance requirement.) tive, but their use is declining. 3. Incinerators cannot emit more than 180 milligrams (mg) of particulate matter per Technical Issues dry standard cubic meter of stack gas. This There are approximately 350 liquid injection standard is intended to control the emis- and rotary kiln incinerators currently in ser- sions of metals carried out in the exhaust vice for hazardous waste destruction.18 Most gas on particulate matter. (Recent tests in- 15 dicate that this standard may be more diffi- Frank Whitmore, Versar, inc., persona} communication, cult to achieve than was earlier thought.19) August 1982. Gene Crumpler, Office of Solid Waste, Hazardous and Indus- “Ibid. 18 trial Waste Division, Environmental Protection Agency, personal 40 CFR, Sec. 264.343. communication, January 1983. 19Wrumpler, op. cit. 160 . Technologies and Management Strategies for Hazardous Waste Control

There are instances in which the incinerator Waste treatments with reliable high-destruc- performance standards do not fully apply. tion efficiencies offer attractive alternatives to First, the regulations do not apply to facilities land disposal for mobile, toxic, persistent, and that burn waste primarily for its fuel value. To bioaccumulative wastes. However, these treat- date, energy recovery of the heat value of waste ment technologies are not free of technical streams qualifies for the regulatory exemp- issues. The first three issues noted below relate tion.20 Second, facilities burning waste that are directly to policy and regulation, and the re- considered hazardous because of characteris- maining three issues summarize sources of tics of ignitability, corrosiveness, and reactivity technical uncertainty with respect to the very are eligible for exemptions from the perform- small concentrations of remaining substances. ance standards. Of the three, the exemption for Improvements in policy and regulatory control energy recovery applies to a greater volume of should recognize these technical issues: hazardous waste. Finally, incinerators operat- ● Significant sources of toxic combustion ing at sea are not governed by RCRA but rather by the Marine Protection, Research, and products, emitted to the air, are not being controlled with the same rigor as are Sanctuaries Act of 1972. Regulations under this RCRA incinerators. These include emis- act do not require scrubbing of the incinerator sions from facilities inside the property exhaust gas. In the future, EPA may require boundaries of refineries and other chem- that incinerator ships operating in close prox- ical processing plant sites. In addition, imity to each other scrub their exhaust gases. “boilers” can receive and burn any ignit- With regard to combustion processes, the able hazardous waste which has beneficial most important design characteristics are the fuel value (see discussion on “Boilers”). “three Ts:” Draft regulations governing boilers are currently being developed under RCRA 1. maintenance of adequate temperatures and very limited reporting requirements within the chamber, are brand new. Under the Clean Air Act, 2. adequate turbulence (mixing) of waste there is only very limited implementation feed and fuel with oxygen to assure even governing the remaining facilities. Stand- and complete combustion, and ards have been set for only four sub- 3. adequate residence times in the high-tem- stances, and apply to only a small class of perature zones to allow volatilization of facilities. the waste materials and reaction to com- ● There are some problems with the tech- pletion of these gases. nology-based DRE performance stand- Finally, the DRE capability of these technol- ards. EPA uses the technology-based per- ogies generally varies widely depending on the formance standard for practicality, and waste type to which it is applied, Chlorine or for its technology-forcing potential. How- other halogens in the waste tend to extinguish ever, the performance standard overly sim- combustion; so, in general, these wastes tend plifies the environmental comparisons to be more difficult to destroy. An important among alternatives. related misconception is that the more toxic Complete knowledge about the trans- compounds are the more difficult they are to port, fate, and toxic effects of each waste burn. Toxic dioxins and PCBs are popular ex- compound from each facility is unobtain- amples of highly halogenated wastes which are able. Thus, some simplified regulatory tool both highly toxic and difficult to destroy, but is needed. However, the most important these should not imply a rule. Discussion of and known factors should be included in waste “incinerability” is included below. regulatory decisions. Notably, these could include: the toxicity of the waste, the load 2040 CFR, sec. 261.2 (c)(2]. to the facility (the waste feed concentra- Ch. 5— Technologies for Hazardous Waste Management ● 161

tion and size of the facility), and popula- more volatile compounds. Methods for tion potentially affected. Future regula- concentrating the exhaust gas in order to tions, however, could endeavor to shape obtain the sample especially for volatile the manner in which competing technol- compounds are still evolving, The newness ogies are chosen in a more environmental- of these tests suggests there may be a wide ly meaningful way (see ch. 6), variety in the precision capabilities among Finally, the 99.99 percent DRE may be the laboratories which analyze DRE test viewed as a “forcing” standard with re- results. spect to some high-temperature technolo- ● The measurements currently used in dai- gies, but emerging high-temperature tech- ly monitoring of performance cannot re- nologies (notably plasma arc) may offer liably represent DRE at the 99.99 percent much greater and more reliable DREs. level. For recordkeeping and enforcement, Rather than forcing, it may discourage the air and waste feed rates along with gas wide use of more capable technologies, temperature are used as indirect measures ● Strengthening regulations with respect to for DRE. For facilities already equipped the technical uncertainties below will re- with carbon monoxide meters (and for all quire deliberate research efforts in addi- Phase II regulated incinerators), carbon tion to anticipated permitting tests. Test monoxide concentration in the stack gas data for wastes that are difficult to burn is also included. Also, waste/fuel mix and are lacking. The current incinerator per- waste/fuel ratio can have a great effect on formance standard is based on EPA sur- DRE. Thus, these ratios are noted in the veys from the mid-1970’s which involved permits. However, it is difficult to specify easier to burn wastes, higher fuel to waste acceptable ranges of mixes based on test feed ratios than in current use, and smaller burn information. The idea behind the spe- than commercial-scale reactors, EPA is cifications is that as long as actual values currently testing or observing test burns of these parameters remain within pre- for many of the technologies described, scribed limits during operation, the de- using compounds found to be representa- sired DRE is being achieved. These meas- tive of very difficult to burn toxic waste. ures are chosen not only because they are Most of these data are still being evaluated; easily and routinely monitored, but also be- few results have become available. In the cause there is a theoretical basis for using next few years, a great deal of test burn them to indicate combustion efficiency. data will be generated regarding existing However, all these measures are only in- facilities and given wastes. In addition, the directly related to the compounds of con- cost of test burn is often $20,000 to $50,000. cern. For example, carbon monoxide is a These costs burden both EPA research and very stable and easily monitored product private industry. Such data will help per- of incomplete combustion (PIC). Thus, it mit writers, but these data will have lim- is often used as a sensitive indicator for ited use in resolving many of the technical combustion efficiency in energy applica- uncertainties described below. tions. However, its relationship to other ● Implementation of the current perform- combustion products and to remaining ance standards relies on industrywide concentrations of POHCs is very indirect use of monitoring technology operating and uncertain, at the limits of its capability. In DRE Most experts agree that the development analyses, the fourth nine is often referred of a way to accurately measure DRE con- to as guesswork; standardized stack gas currently with treatment process, would sampling protocols for organic hazardous eliminate much of the technical uncertain- constituents are still being developed, This ties surrounding incineration, To this end, is particularly true with respect to organics EPA is studying devices which monitor carried on particulate matter and to the total organic carbon, and the National 162 . Technologies and Management Strategies for Hazardous Waste Control

Bureau of Standards (NBS) is studying var- Some compounds, known to be very diffi- ious combinations of available monitoring cult to incinerate, also occur as PICs from techniques.21 It is not likely that a single combusting mixtures of compounds thought technique can be developed in the near to be more easily burned. Our ability to term to monitor the whole range of com- monitor these compounds has only recent- pounds of concern, but the development ly made such observations possible, and of a combination of devices to do the job there are many high-temperature kinetic holds promise, However, these techniques reactions not fully understood. Unless spe- will still have problems. This will include: cifically analyzed, a selected PIC would go cost; some reliance on correlations to sur- undetected. While additional testing of in- rogate measures; and, in the case of the dividual combustion facilities will demon- NBS approach, the possible introduction strate specific DRE capabilities, these ob- of corrosive tracer compounds. servations are not likely to improve our ● There is sharp disagreement in the scien- fundamental understanding of PIC forma- tific and regulatory community about the tion. In particular, with the cost of test use of waste “incinerability.” This con- burns with POHC monitoring so high, cept is a regulatory creation, not a physical some more basic research on PIC forma- attribute of any material. The idea behind tion would be appropriate. Current EPA incinerability is that as long as the least in- research and development, however, is cinerable waste (i.e., the most difficult to focused in support of near-term permitting burn waste) is destroyed to the required ex- activities. tent, all other waste would be destroyed to an even greater extent. Thus, waste “in- Review of Selected High-Temperature cinerability, " in addition to waste concen- Treatment Technologies tration, is used to select a limited number of waste constituents for monitoring in a There are a variety of treatment technologies involving high temperatures which have, or test burn. Problems with this approach result largely from lack of basic informa- will likely have, important roles in hazardous waste management. Most of these technologies tion about measures for incinerability. involve combustion, but some are more accu- This presents uncertainty in the selection of those POHCs to be monitored in the rately described as destruction by infrared or waste feed and stack gas. Heat combustion ultraviolet radiation. is the informational surrogate currently Discussion below focuses on the distinguish- used because it is readily determined. ing principles, the reliability and effectiveness, However, this measure relates poorly to and the current and projected use of these tech- waste incinerability. Chlorine and other nologies, Unless otherwise noted, DRE values halogens in the waste tend to extinguish were measured in accordance with EPA testing combustion, but simple halogen content procedures. Table 32 summarizes the advan- give poor indication of incinerability. tages, disadvantages, and status of these tech- Autoignition temperature is closely related nologies. to incinerability, but for most hazardous 1. Liquid injection incineration.—With compounds, it has not been measured. Bet- liquid injection, freely flowing wastes are atom- ter predictors of incinerability could be developed. One scheme, proposed by NBS, ized by passage through a carefully designed nozzle (see fig. 8). It is important that the would use a combination of factors, but it needs to be tested. droplets are small enough to allow the waste to completely vaporize and go through all the ● There is a lack of basic understanding subsequent stages of combustion while they about how stable toxic PICs are formed. reside in the high-temperature zones of the in- 21 W. Schaub, National Bureau of Standards, personal commu- cinerator. Residence times in such incinerators nication, January 1983, are short, so nozzles especially, as well as other Ch. 5—Technologies for Hazardous Waste Management • 163

Table 32.—Comparison of Thermal Treatment Technologies for Hazard Reduction -. . Advantages of design features Disadvantages or,. design , features. Status for hazardous waste treatment Currently available incinerator deslgns: Liquid injection Incineration Can be designed to burn a wide range of Limited to destruction of pumpable waste Estimated that 219 liquid injection pumpable waste. Often used in conjunction (viscosity of less than 10,000 SSI). Usually incinerators are in service, making this with other Incinerator systems as a designed to burn specific waste streams. the most widely used incinerator design. secondary afterburner for combustion of Smaller units sometimes have problems volatilized constituents Hot refractory with clogging of injection nozzle. minimizes cool boundary layer at walls. HCI recovery possible. Rotary kilns: Can accommodate great variety of waste Rotary kilns are expensive. Economy of scale Estimated that 42 rotary kilns are in service feeds” solids, sludges, Iiquids, some bulk means regional locations, thus, waste under interim status. Rotary kiln design is waste contained in fiber drums Rotation must be hauled, increasing spill risks. often centerpiece of integrated commercial of combustion chamber enhances mixing treatment facilities. First noninterim of waste by exposing fresh surfaces for RCRA permit for a rotary kiln incinerator oxidation. (IT Corp.) is currently under review. Cement kilns: Attractive for destruction of harder-to-burn Burning of chlorinated waste limited by Cement kilns are currently in use for waste waste, due to very high residence times, operating requirements, and appears to destruction, but exact number is unknown. good mixing, and high temperatures increase particulate generation. Could National kiln capacity is estimated at 41.5 Alkaline environment neutralizes chlorine require retrofitting of pollution control million tonnes/yr. Currently mostly equipment and of instrumentation for nonhalogenated solvents are burned. monitoring to bring existing facilities to comparable level. Ash may be hazardous residual. Boilers (usually a Iiquid Injection design)’ Energy value recovery, fuel conservation Cool gas layer at walls result from heat Boilers are currently used for waste disposal. Availability on sites of waste generators removal This constrains design to high- Number of boiler facilities is unknown, reduces spill risks during hauling efficiency combustion within the flame quantity of wastes combusted has been zone, Nozzle maintenance and waste feed roughly estimated at between 17.3 to 20 stability can be critical. Where HCI is million tonnes/yr. recovered, high temperatures must be avoided. (High temperatures are good for DRE.) Metal parts corrode where halogenated waste are burned. Applications of currently availabie designs: Multiple hearth Passage of waste onto progressively hotter Tiered hearths usually have some relatively Technology is available; widely used for hearths can provide for long residence cold spots which inhibit even and complete coal and municipal waste combustion. times for sludges Design provides good combustion. Opportunity for some gas to fuel efficiency. Able to handle wide short circuit and escape without adequate variety of sludges residence time. Not suitable for waste streams which produce fusible ash when combusted Units have high maintenance requirements due to moving parts in high- temperature zone. Fluidized-bed incinerators: Turbulence of bed enhances uniform heat Limited capacity in service. Large economy Estimated that nine fluidized-bed transfer and combustion of waste. Mass of scale incinerators are in service. Catalytic bed of bed is large relative to the mass of may be developed. injected waste. At-sea incineration: shipboard (usually liquid injection incinerator): Minimum scrubbing of exhaust gases Not suitable for waste that are shock Limited burns of organochlorine and PCB required by regulations on assumption that sensitive, capable of spontaneous were conducted at sea in mid-1970. PCB ocean water provides sufficient combustion, or chemically or thermally test burns conducted by Chemical Waste neutralization and dilution. This could unstable, due to the extra handling and Management, Inc., in January 1982 are provide economic advantages over land- hazard of shipboard environment. Potential under review by EPA. New ships under based incineration methods Also, for accidental release of waste held in construction by At Sea Incineration, Inc. incineration occurs away from human storage (capacities vary from between populations Shipboard incinerators have 4,000 to 8,000 tonnes). greater combustion rates, e.g., 10 tonnes/hr. At-sea incineration: oil drilling platform-based: Same as above, except relative stability of Requires development of storage facilities. Proposal for platform incinerator currently platform reduces some of the complexity Potential for accidental release of waste under review by EPA. in designing to accommodate rolling held in storage. motion of the ship. 164 . Technologies and Management Strategies for Hazardous Waste Control

Table 32.—Comparison of Thermal Treatment Technologies for Hazard Reduction—Continued

Advantages of design features Disadvantages of design features Status for hazardous waste treatment Pyrolysis: Air pollution control needs minimum: air- Greater potential for PIC formation. For Commercially available but in limited use. starved combustion avoids volatilization some wastes produce a tar which is hard of any inorganic compounds. These and to dispose of. Potentially high fuel heavy metals go into insoluble solid char. maintenance cost. Waste-specific designs Potentially high capacity. only. Emerging thermal treatment technologies: Molten salt: Molten salts act as catalysts and efficient Commercial-scale applications face potential Technology has been successful at pilot heat transfer medium. Self-sustaining for problems with regeneration or disposal of plant scale, and IS commercially available. some wastes. Reduces energy use and ash-contaminated salt. Not suitable for reduces maintenance costs. Units are high ash wastes. Chamber corrosion can compact; potentially portable. Minimal air be a problem. Avoiding reaction vessel pollution control needs; some combustion corrosion may imply tradeoff with DRE. products, e.g., ash and acidic gases are retained in the melt. High-temperature fluid wall: Waste is efficiently destroyed as it passes To date, core diameters (3”, 6", and 12”) and Other applications tested; e.g., coal through cylinder and is exposed to radiant cylinder length (72 limit throughput gasification, pyrolysis of metal-bearing heat temperatures of about 4,000° F. capacity. Scale-up may be difficult due to refuse and hexachlorobenzene. Test Cylinder is electrically heated; heat is thermal stress on core. Potentially high burns on toxic gases in December 1962. transferred to waste through inert gas costs for electrical heating. blanket, which protects cylinder wall. Mobile units possible. Plasma arc: Very high energy radiation (at 50,000° F) Limited throughput. High use of NaOH for Limited U.S. testing, but commercialization in breaks chemical bonds directly, without scrubbers. July 1963 expected. No scale-up needed. series of chemical reactions. Extreme DREs possible, with no or little chance of PICs, Simple operation, very low energy costs, mobile units planned. Wet oxidation: Applicable to aqueous waste too dilute for Not applicable to highly chlorinated organics, Commercially used as pretreatment to incineration and too toxic for biological and some wastes need further treatment. biological wastewater treatment plant. treatment. Lower temperatures required, Bench-scale studies with catalyst for and energy released by some wastes can nonchlorinated organics. produce self-sustaining reaction. No air emissions. Super critical water: Applicable to chlorinated aqueous waste Probable high economy of scale. Energy Bench-scale success (99.99°/0 DRE) for which are too dilute to incinerate. Takes needs may increase on scale-up. DDT, PCBs, and hexachlorobenzene. advantage of excellent solvent properties of water above critical point for organic compounds. injected oxygen decomposes

smaller organic molecules to CO2 and water.— No air emissions. SOURCE: Off Ice of Technology Assessment, compiled from references 12 through 29. features, must be designed for specified waste many different liquid waste mixes: motor and stream characteristics such as viscosity. Cer- industrial oils, emulsions, solvents, lacquers, tain waste must be preheated. Nonclogging and organic chemicals of all kinds including nozzles are available, but all nozzles must be relatively hard-to-destroy pesticides and chemi- carefully maintained. One of the chief costs is cal warfare agents. maintenance of refractory walls. Incinerator Liquid injection incinerators, together with design is a complex, but advanced field. Many rotary kilns (see below) form the current basis distinguishing design features are currently of the hazardous waste incineration industry. proprietary; especially nozzle designs and re- These technologies have been used for the pur- fractory composition. pose of destroying industrial waste for many Injection incinerator designs, especially noz- years. In the mid-1970’s EPA testing and data zle design, tend to be waste-specific. However, reviews of these facilities provided the basis individual designs exist for the destruction of for the current interim performance standard Ch. 5— Technologies for Hazardous Waste Management ● 165

Figure 8.— Injection Liquid Incineration

Scrubbed gases Liquid waste A

Dispersion stack 0 Storage Fumes Precooler \ M!!!n- / Cooling Waste scrubber conditioning ‘+t~ m.I Support fuel if required Atomizing gas

} b-. combustion- air- ~ { I v,.VVdlW Venturi scrubber

Makeup water

/ %Residue Water treatmentb

SOURCE D A Hitchcock, "Solid Waste Disposal Incineration, ” Chemical Engineering, May 21, 1979 of 99.99 percent DRE for incineration of haz- inders range in size from about 3 ft in diameter ardous materials. by about 8 or 10 ft long, up to 15 or 20 ft in diameter by about 30 ft long. Rotary kilns oper- EPA has recently begun testing incinerators ate between temperature extremes of approxi- to better understand the DRE capabilities for mately 1,500º and 3,000° F, depending on loca- the most difficult-to-burn waste. Analysis is not tion measured along the kiln. They range in yet complete, but preliminary indications both 23 capacity from 1 to 8 tons of waste per hour. confirm the 99.99 percent capabilities, and underscore the sensitivities of individual in- The primary advantage of rotary kilns is their cinerators to operational and waste feed vari- ability to burn waste in any physical form and ables.22 with a variety of feed mechanisms. Many large companies that use chemicals (such as Dow 2. Rotary kilns.—These can handle a wider Chemical Co., 3M Corp., and Eastman Kodak) physical variety of burnable waste feeds—sol- incinerate onsite with their own rotary kilns. ids and sludge, as well as free liquids and gases. For flexibility, this is often in combination with A rotating cylinder tumbles and uncovers the injection incinerators. Similarly, large waste waste, assuring uniform heat transfer. The cyl- management service firms (Ensco and Rollins

22 Environmental Services) operate large rotary Timothy Oppelt, and various other personal communications, Environmental Protection Agency, Office of Research and Devel- kilns as part of their integrated treatment cen- opment, IERL, Cincinnati, Ohio, December 1982 and January 1983. 23lbid. 166 ● Technologies and Management Strategies for Hazardous Waste Control ters. Others are in commercial operation ter than 99.99 percent destruction.28 The Cali- throughout the United States and Europe.24 fornia Air Resources Board recently recommended the use of cement kilns to destroy PCB 3. Cement kilns.—These are a special type 29 waste. EPA has recently completed a careful- of rotary kiln. Liquid organic waste are cofired ly controlled test on the most difficult to burn with the base fuel in the kiln flame. The very waste at the San Juan Cement Co. in Duablo, thorough mixing and very long residence times Puerto Rico. The results of this test are still make possible more complete combustion of being evaluated. even difficult to burn organic waste. Tempera- tures in the kiln range between 2,600° and Some hazardous wastes are currently being 0 3,000° F (1,400 and 1,650° C). Also, the alka- burned in cement kilns under the energy re- line environment in the kiln neutralizes all of covery exclusion, but, these have been general- the hydrochloric acid produced from the burn- ly nonhalogenated solvents or waste oils, rather ing of chlorinated waste. Most ash and nonvol- than the most toxic and/or difficult to burn atile heavy metals are incorporated into the compounds, for which they may be well suited. clinker (product of the kiln) and eventually into Since 1979 the General Portland Co. of Pauld- the cement product. Heavy metals incorpo- ing, Ohio, has been burning 12,500 tons per rated into the clinker may present either real year of nonhalogenated waste solvents as a or perceived risks (toxicological and structural), supplemental fuel. 25 but little is known about such concerns. A There is theoretically no limit on the fuel-to- portion (perhaps 10 percent) of the ash and waste-feed ratio; as long as the waste mix has metals carry over into the kiln dust that is col- sufficient heating value, a kiln could be fired lected in the system’s air-pollution control sys- solely on waste feed. Idled kilns could be used tem. Some of this material is recycled to the 26 27 as hazardous waste facilities. Local public con- kiln, the balance is generally landfilled. cerns, notably over spills during hauling, have Five controlled test burns for chlorinated presented the major obstacle to such incinera- waste have been documented in wet process tor use, but commercial interest apparently is cement kilns in Canada, Sweden, Norway, and still strong. so Much will depend on how new most recently, the United States. The foreign regulations affect land disposal use. results have tended to confirm the theoretical 4. Boilers.—Ignitable waste with sufficient predictions —that 99.99 percent or better can heating value are coincinerated with a primary be achieved for chlorinated hydrocarbons. fuel in some types of boilers. The boiler con- However, these studies lack strong documenta- verts as much as possible of the heat of com- tion of control protocols. In the Swedish re- bustion of the fuel mix into energy used for pro- sults, representative concentrations of very dif- ducing steam. Different types of boilers have ficult to burn waste were destroyed beyond the been designed to burn different types of fuels. limits of monitoring technology, indicating bet- Boilers burn lump coal, pulverized coal, No. 2 oil, No. 6 oil, and natural gas.31 The predom- 24Technologies for the Treatment and Destruction of Organic Wastes as Alternatives to Land Disposal, State of California, Air 28Robert Olexsey, “Alternative Thermal Destruction Processes Resources Board, August 1982. for Hazardous Wastes,” Environmental Protection Agency, Of- 25Myron W. Black, “Impact of Use of Waste Fuels Upon Ce- ficee of Research and Development, May 1982. ment Manufacturing, ” paper presented at the First International ‘ ” An Air Resources Board Policy Regarding incineration as Conference on Industrial and Hazardous Wastes, Toronto, On- an Acceptable Technology for PCB Disposal, ” State of Califor- tario, Canada, October 1982. nia, Air Resources Board, December 1981. 26Doug]as L. Hazelwood and Francis J. Smith, et al., “Assess- 30Myron W. Black, “Problems in Siting of Hazardous Waste ment of Waste Fuel Use in Cement Kilns, ” prepared by A. T. Disposal Facilities–The Peerless Experience,” paper presented Kearney and the Portland Cement Association for the Office of at a conference on Control of Hazardous Material Spills, 1978. Research and Development, EPA, contract No. 68-03-2586, 3lEnvironmental Protection Agency, Office of Research and March 1981. Development, “Technical Overview of the Concept of Dispos- 27Aternatives to the Land Disposal of Hazardous Wastes, op. ing of Hazardous Waste in Industrial Boilers, ” contract No. cit. 68-3-2567. October 1981. Ch. 5— Technologies for Hazardous Waste Management ● 167 inant application to hazardous waste involves Evaluating the actual hazardous waste de- boilers of the kind that would normally burn struction capabilities of various boilers has No. 2 fuel oil. only just begun by EPA. Only three tests were complete at the time of this report; seven more These boilers are similar to liquid injection are planned. Tests to date have been conducted incinerators, but there are important differ- primarily with nonhalogenated, high heating ences with respect to the high destruction effi- value solvents and other nonhalogenated mate- ciencies desirable for hazardous waste: 1) they rials. These tests have demonstrated DREs gen- have purposefully cooled walls, and 2) at least erally in the 99.9 percent area. Subsequent test- some of the walls and other parts exposed to ing will be directed toward waste that are con- the combustion products are often metallic in- sidered to be more difficult to destroy than stead of refractory. The reason that the walls 34 those tested up to this point. Testing at coop- of the boiler must be cooled is to make use of erating boiler facilities is expected to confirm the heating energy from the product gas. In the that boilers of a wide variety of sizes and types combustion chamber, this results in a relatively can achieve hazardous waste destruction effi- cool area (a thermal boundary layer) through ciencies comparable to those achieved by in- which combustion products might pass. cineration for some common waste fuels. In- The metallic surfaces avoid some expensive dustry cooperation will be needed, though, for refractory maintenance but the bare metal sur- field testing of those difficult-to-burn and the faces are susceptible to corrosion where halo- more toxic wastes marginally useful as fuels. genated organic waste are burned. For this rea- Actual waste destruction achieved through son industrial boiler owners, concerned for the coincineration probably has more to do with life of their equipment, probably limit their use how and why the boiler is operated, and with of such waste. However, there is a growing in- knowledge of the waste feed contents, than dustrial trend toward recovery of hydrochloric with the type and size of boiler. Destruction acid from the stack gas. * 32 Acid recovery re- by combustion for toxic organic compounds quires that stack gas temperatures greater than requires very complete, efficient combustion. 1,2000 C be avoided, since this condition shifts Thus, in a boiler, the objective of getting usable the chemical equilibrium toward free chlorine. heat out of the fuel mix is similar to that of For hazardous waste destruction, however, achieving high destruction of toxic organic higher temperatures are better. waste. However, the marginal benefits of For these reasons, efficient boilers must be achieving incremental degrees of destruction designed so that hydrocarbon destruction oc- may be valued differently by different users. curs mostly in the flame zone with very little For example, it may cost less at very large reaction occurring after the flame zone. As is boilers (e.g., those at utilities and large indus- the case with incinerators, boiler design is well trial facilities) to save fuel costs through in- advanced, and many designs are proprietary. creased combustion efficiency than at smaller High fuel efficiency designs may recirculate boilers. Thus, utility boilers are probably de- the flame envelope back into itself to enhance signed and operated for stringent fuel efficien- the formation of the series of reactions neces- cy by an economic motivation that may parallel sary for complete combustion. Other designs the rigorous incinerator performance standard may involve staged injections with varying in its effect for DREs. Although there would waste-to-fuel ratios .33 be an economic advantage for these facilities ——— — to burn waste fuels, many would not be able ● Currently a significant amount, perhaps over ✔ percent of to find reliable and sufficient supplies. On the the U.S. hydrochloric acid, is produced from stack gas scrub- other hand, the objective with many industrial bers. Half of this is from boilers and half from incinerators. 32James Karl, Dow Chemical Co., persona] communication, boilers is to deliver an optimal amount of heat January 1983. 33Elmer Monroe, Du Pont Chemical Co., personal communication, December 1982. 34Olexsey, op. cit. 168 ● Technologies and Management Strategies for Hazardous Waste Control over time. Thus, achieving 100-percent com- could also benefit from the fuel value of the bustion efficiency is not desirable if it takes 2 same waste used as auxiliary fuel in boilers. days to achieve this goal, Incinerators have as 5. Multiple hearth incinerators.—These use their direct goal the destruction of the fuel a vertical incinerator cylinder with multiple compound which is not so in boilers. horizontal cross-sectional floors or levels where Excluding the very largest utility and indus- waste cascades from the top floor to the next trial boilers, there are about 40,000 large (10 and so on, steadily moving downward as the million to 250 million Btu/hr) industrial boilers wastes are burned. These units are used pri- and about 800,000 small- to medium-sized insti- marily for incineration of sludges, particularly tutional, commercial, and industrial boilers na- those from municipal sewage sludge treatment tionwide. 35 It is expected that most of the in- and, to a much lesser extent, certain special- dustrial boilers having firing capacities less ized industrial sludges of generally a low-haz- than 10 million Btu/hr may not readily lend ard nature. They are used almost exclusively themselves to coincineration. so at industrial plants incinerating their sludges on their own plant site for the latter cases.39 Finally, there are about 14 million residen- Such incinerators are not well suited for most tial, single-home boilers which could burn haz- 37 hazardous waste for two reasons: they exhibit These small boilers could have ardous waste. relatively cold spots, and the waste is intro- adverse health effects on small, localized areas. duced relatively close to the top of the unit. In addition, any fuels blended with organics Because hot exhaust gases also exit from the and illegally burned, in apartment houses or top, there is the potential for certain volatile institutional boilers, for example, should be waste components to short-circuit or “U-turn” expected to reduce the lives of these boilers near the top of the incinerator and exit to the through corrosion. atmosphere without spending an adequate time To assess the role that boilers currently play in the hot zone to be destroyed. This may be in hazardous waste management nationwide, improved by having a separate afterburner it is necessary to know what compounds are chamber, but this option does not appear to being burned, in which facilities, and with have become accepted in the hazardous waste what DREs. Without reporting requirements field. 40 for coincineration, information is seriously At least one brief test of a typical multiple lacking. Currently, boilers may be burning hearth furnace was conducted in the early twice the volume of ignitable hazardous waste 1970’s, in which the sewage was “seeded” with that is being incinerated. Except for those from a small quantity of pesticide material. Although petroleum refining, all were discharged to the the pesticide was not detected in the exhaust, environment until environmental, handling, or the researchers became aware of the short-cir- increasing primary fuel costs encouraged their 38 culating and residence-time problems and did use as a fuel. Of the entire spectrum of burn- not pursue the application of multiple hearths able waste, those having the highest Btu con- to hazardous wastes any. tent are attracted to boilers. This may have economic effects on regulated incineration, 6. Fluidized bed combusters.-This is a rela- because some hazardous waste incinerators tively new and advanced combuster design being applied in many areas. It achieves rapid 35M, TurgeOn, Office of Solid Waste, Industrial and Hazardous Waste Division, EPA, persona] communication, January 1983. and thorough heat transfer to the injected fuel Olexsey, op. cit. and waste, and combustion occurs rapidly. Air 37c. c. Shih and A, M. Takata, TRW, Inc., “Emissions Assess- forced up through a perforated plate, maintains ment of Conventional Stational Combustion Systems: Summary

Report” prepared for the Office of Research and Development, 39 EPA, September 1981. Alternatives to the Land Disposal of Hazardous Wastes, op. 38EPA “Technical overview of the Concept of Disposing of cit. Hazardous Wastes in Industrial Boilers, ” op. cit. 40Oppelt, op. cit. Ch. 5— Technologies for Hazardous Waste Management ● 169

a turbulent motion in a bed of very hot inert scrubber requirement. ) Free from the need to granules. The granules provide for direct con- attach scrubbers, marine incinerator designers duction-type heat transfer to the injected waste. can maximize combustion efficiency in ways These units are compact in design and simple that land-based incinerators cannot.45 Incinera- to operate relative to incinerators. Another ad- tors based on oil drilling platforms would fur- vantage is that the bed itself acts as a scrubber ther be freed from accommodating rolling ship for certain gases and particulate. Its role in motion. hazardous waste may be limited to small and Various EPA monitoring of test commercial specialized cases due to difficulties in handling burns of PCBs and government burns of herbi- of ash and residuals, low throughput capacity 41 cide Agent Orange and mixed organochlorines and limited range of applicable waste feeds. in the mid and late 1970’s confirmed the There are presently only about zoo such com- 99.99 + percent destruction capability for busters in the United States, used chiefly for liquid injection incineration used at sea.46 Cur- municipal and similar sludges. About nine are rent technology exists only for liquids. Rotary used for hazardous waste.42 Existing fluidized kilns could be adapted to ships and more read- bed combusters are sparsely distributed and ily to oil drilling platforms. relatively small. Future applications of fluid- There exists considerable controversy about ized bed technology to hazardous waste is like- the test burns recently conducted for PCBs de- ly to occur at new facilities built specifically struction onboard the M.T. Volcanus. Data re- for this purpose rather than at existing munici- sults are not yet available. Major concerns are pal facilities. whether the land and marine alternatives rep- Recent EPA testing at the Union Chemical resent the same environmental risk and if the Co., Union, Me., is still being evaluated. Early performance standards are evenly applied. test results are mixed with regard to 99.99 per- EPA’s view is that they represent roughly the cent destruction.43 The simplicity of this tech- same risk.47 Regarding the performance stand- nology and its ease of operation seem to indi- ards, it should be recognized that the scrubbing cate high reliability for achieving those levels the exhaust gas of land-based incinerators may of destruction and wastes for which it will be providing the fourth nine in their DRE per- prove to be applicable. A catalytic, lower formance. Thus, an at-sea DRE of 99.9 percent temperature fluidized bed technology is being may be more similar to the land-based DRE of developed which may have lower energy costs, 99.99 percent than it may appear. The contribu- and may be more applicable to hazardous tion of scrubbers to DRE values are not well waste destruction.44 However, incompatibil- known. ities between catalysts proposed on various Additional concerns about incineration at hazardous waste may present problems to over- sea include: stack gas monitoring, which is dif- come. ficult enough on land and perhaps more soon 7. Incineration at sea.—This is simply incin- a ship at sea, and the risk of accidents near erator technology used at sea, but without stack shore or at sea, The ecological effects of a spill gas scrubbers. (The buffering capacity of the of Agent Orange on phytoplankton productiv- sea and sea air is the reason for the lack of a ity could be substantial.48 Storage facilities necessary for drilling platform-based incinera- 4lAlternatives to the Land Disposal of Hazardous Wastes, op. cit. 42Proctor and Red fern, Ltd., and Weston Designers Consult- 45K. Kamlet, National Wildlife Federation, mean Dumping of ants, “Generic Process Technologies Studies” (Ontario, Canada: Industrial Wastes, B. H, Ketchum, et al. (cd.) (New York: Plenum Ontario Waste Management Corp., System Development Proj- Publishing Corp., 1981). ect, August 1982). 46D. Oberacker, Office of Research and Development, IERL, 43J. Miliken, Environmental Protection Agency, personal com- Environmental Protection Agency, Cincinnati, Ohio, personal munication, November 1982. communication, December 1982. ‘R. Kuhl, Energy Inc., Idaho Falls, Idaho, personal communi- “Ibid. cation, January 1983. 48Kamlet, op. cit. 170 . Technologies and Management Strategies for Hazardous Waste Control tion may involve still higher spill risks. Public Pyrolysis has been used by the Federal Gov- opposition to hazardous waste sites applies also ernment to destroy chemical warfare agents to storage of waste at ports. and kepone-laden sludge and by the private sector to dispose of rubber scrap, pharmaceuti- Other High Temperature Industrial Processes cal bio-sludge, and organic chlorine sludges. Most recently, pilot plant test burns on chlori- Other types of applicable combustion proc- nated solvents from a metal-cleaning plant esses including metallurgical furnaces, brick have been destroyed with 99.99 percent de- and lime kilns, and glass furnaces, are exam- 52 struction. ples of existing industrial technologies which might be investigated as potential hazardous Broader application would await much more waste destruction alternatives.49 There is no equipment development and testing. Among reporting of such uses that may be occurring, the potential problems with pyrolysis are: and no DRE data have been collected. The ben- ● Greater potential for toxic and refractory eficial use exclusion may apply to many of such 50 PICs formation than with combustion in practices. However, objectives of such proc- air. The reducing atmosphere produces esses are not necessarily complementary or larger amounts of these compounds, and supportive of high DRE. The technical poten- they may pass through the off-gas after- tial for hazardous waste destruction and need burner. for regulation of such practice needs investi- ● Production of an aqueous tar that maybe gation. difficult to dispose in either a landfill or Emerging Thermal Destruction Technologies an incinerator. ● Substantial quantities of auxiliary fuel may Undue importance should not be placed on be required to sustain temperature in the the distinction between current and emerging afterburner. 53 technologies, The intent is merely to distin- Commercially, high throughput (up to 6,500 guish between technologies currently “on the lb/hr) and required air pollution control re- shelf” and those less commercially developed quirements may be key future benefits. How- for hazardous waste applications. ever, maintenance costs due to moving parts, Pyrolysis. -This occurs in an oxygen deficit and the need for well-trained operators may be atmosphere, generally at temperatures from relatively high.54 1,000° to 1,7000 F. Pyrolysis facilities consist Molten Salt Reactors.–These achieve rapid of two stages: a pyrolyzing chamber, and a heating and thorough mixing of the waste in fume incinerator. The latter is needed to com- a fluid heat-conducting medium. Liquid, solid, bust the volatilized organics and carbon mon- or gaseous wastes are fed into a molten bath oxide produced from the preceding air-starved of salts (sodium carbonate or calcium carbon- combustion. The fume incinerator operates at ate). Solids must be sized to 1/4- or l/8-inch 1,800° to 3,000°F. The pyrolytic air-starved pieces in order to be fed into the bed. The bed combustion avoids volatilization of any inor- must be initially preheated to 1,500° to 1,800° ganic components and provides that inorgan- F. Provided that the waste feed has a heating ics, including any heavy metals, are formed value of at least 4,000 Btu/lb, the heat from into an insoluble easily handled solid char combustion maintains the bed temperature, residue. Thus, air pollution control needs are 51 and the combustion reactions occur with near minimized. completion in the bed instead of beyond it. The 49PEDCO Environmental Services, Inc., “Feasibility of Destroy- sodium carbonate in the bed affects neutraliza- ing Hazardous Wastes in High Temperature Industrial Proc- esses,” for the Office of Research and Development, IERL, EPA, Cincinnati, Ohio, May 1982. 52Oppelt, op. cit. 5040 CFR, sec. 261 (c)(2). 51 53Ibid. Alternatives tO the Land Disposal of Hazardous Wastes, op. 54Technologies of the Treatment and Destruction of Organic cit. Wastes as Alternatives to Land Disposal, op. cit. Ch. 5— Technologies for Hazardous Waste Management ● 171 tion of hydrogen chloride and scrubbing of the sel corrosion is accelerated by temperature, product gases. Thus, the bed is responsible for reducing conditions (less than sufficient oxy- decomposition of the waste, removal of the gen), and the presence of sulfur. Traditionally, waste residual, and some off-gas scrubbing. A MSD reaction vessels have been refractory bag house for particulate completes air pollu- lined, presenting operational and maintenance tion control and the removal system.55 (See costs similar to those of conventional incinera- fig. 9.) tors. Rockwell International offers an MSD system with a proprietary steel alloy reactor ves- In EPA tests, a pilot scale unit (200 lb/hr) sel, This vessel is warranted for 1 year if the destroyed hexachlorobenzene with DRE’s ex- system is operated within specified ranges of ceeding 6 to 8-9’s (99.9999-percent to 99.999999- temperature, excess air, and melt sulfur con- percent destruction and removal) and chlor- 57 56 tent. dane with DREs exceeding 6 to 7-9’s. Rock- well International also claims 99.999-percent Ash as well as metal, phosphorous, halogen, destruction efficiencies* from private tests on and arsenic salts build up in the bed and must malathion and trichloroethane. be removed, In the case of highly chlorinated waste (50 percent or more) the rate at which Reactor vessel corrosion has impeded devel- salt must be removed approaches the rate of opment of molten salt destruction (MSD). Ves- waste feed, Both the salt replacement (or regen- 56Ibid. eration) and residual disposal determine eco- 56S. Y. Yosim, et al., Energy Systems Group, Rockwell Inter- nomic viability for a given application. In pro- national, “Molten Salt Destruction of PCB and Chlordane, ” EPA contract No. 68-03-3014, Task 21, final draft, January 1983. * Not DRE; small amounts removed in bed salts and baghouse “J, Johanson, Rockwell International, Inc., personal commu- treatment were not measured. nication, January 1983.

Figure 9.—Molten Salt Destruction: Process Diagram

Gas vent Soot blower

drop box Interior wail: - - refractory or bare metal

Solids 1! feed )x( ? 4 Baghouse particulate Molten salt L destructor El

SOURCE Adapted from S. Y Yosim, et al , Energy Systems Group, Rockwell International, “Molten Salt Destruction of HCB and Chlordane,” EPA contract No 68-03-3014, Task 21, final draft, January 1963 172 ● Technologies and Management Strategies for Hazardous Waste Control posed commercial ventures, sodium chloride burned hexachlorobenzene with 99.9999 per- residue would be landfilled and calcium chlor- cent DRE in a 10 ton per day unit.62 A commer- ide would be sold as road salt or injected deep cial-scale unit (20 to 50 tons per day) is operated well. se as a production unit by a licensee in Texas, which has agreed to allow Thagard to continue The process is intended to compete with ro- hazardous waste destruction demonstration tary kilns and may find application for a broad 63 burns there. In December 1982, California market of wastes that are too dilute to inciner- and EPA conducted demonstration burns of ate economically. However, water in the waste some gases that are difficult to destroy ther- feed, as with any incineration technology, uses mally—1,1,1-trichloroethane, carbon tetra- up energy in evaporation, Due to the extreme- ® chloride, dimethyl chloride, Freon 12 , and ly high DREs demonstrated in pilot scale tests, hexachlorobenzene. Results are currently being the process is expected to be very attractive for assessed. destroying the highly toxic organic mixtures and chemical warfare agents, which currently Further scaleup may be needed to provide present serious disposal problems, Rockwell commercial throughput, and this will involve International is in final negotiations with two larger ceramic cores. The effects of thermal commercial ventures in California and Canada. stresses on the life of the cores present the ma- Commercial-scale units offered are 225 and jor untested concern for scale up. 2,000 lb/hour.59 Near-term commercialization of the Thagard High Temperature Fluid-Wall Reactors.—In these reactor is planned. During 1983, a Miami in- reactors, energy is transferred to the waste by vestment firm is expected to underwrite the radiation (rather than by conduction and con- development of a mobile reactor, reducing vection as in the above processes), A porous breakdown and setup time from several weeks central cylinder is protected from thermal or to only a few days. This will facilitate the col- chemical destruction by a layer of inert gas. lection of test burn performance at potential The gas is transparent to radiation, and the applications sites.64 Also, Southern California cylinder is heated by radiation from surround- Edison Inc. is considering the process for fu- ing electrodes to 3,000° to 4,000° F. The refrac- ture destruction of PCB-laden soil and for sta- tory cylinder reradiates this energy internally bilization of a variety of its heavy metal-bearing to the passing waste.60 The important result is liquid waste. The utility is also interested in very rapid and thorough heating of the waste selling byproducts of carbon black from the stream for complete combustion or generation. process.65 The speed of the heating presents little oppor- In addition to its potential mobility resulting tunity for the formation of intermediate prod- from its compact design the only air pollution ucts for incomplete combustion that present control need for the fluid wall reactor may be concerns in conventional incineration proc- a bag house to control particulate. The processes. Also, process control is good since the ess is not expected to be economically competi- radiation is directly driven by electricity. tive with conventional incineration, but will be A bench-scale reactor (¼ lb/min) has de- applicable especially to contaminated soils and stroyed PCBs in contaminated soil (1 percent silts. 61 by weight) with 99.9999 percent DRE. In addi- Plasma-Arc Reactors. tion, the Thagard Research Corp., which con- —These use very high energy free electrons to break bonds between ducted the tests, claims that it has privately molecules. A plasma is an ionized gas (an elec- L B@ Ibid. 1 B@ Ibid. 62Ibid. 60Technologies for the Treatment and Destruction of Organic 63Ibid. Wastes as Alternatives to Land Disposal, op. cit. 64Ibid. 61E. Matovitch, Thagard Research Corp., personal communica- 65E. Faeder, Southern California Edison Power CO., personal tion, January 1983. communication, January 1983. Ch. 5— Technologies for Hazardous Waste Management ● 173 trically conductive gas consisting of charged to add large quantities of air as in incineration, and neutral particles). Temperatures in the potentially contaminated gas emissions are plasma are in excess of 50,0000 F—any gaseous avoided. The reactions take place at tempera- organic compounds exposed to plasma are al- tures of 430° to 660° F (and pressures of 1,000 most instantly destroyed. Plasma arc, when ap- to 2,000 psi). For many applicable waste feeds, plied to waste disposal, can be considered to the oxidation reaction resulting produces be an energy conversion and transfer device. enough heat to sustain the process, or even to The electrical energy input is transformed into produce low pressure steam as an energy by- a plasma, As the activated components of the product. The oxidation reactions typically plasma decay, their energy is transferred to achieve 80 percent complete decomposition to waste materials exposed to the plasma, The carbon dioxide and water, and partial decom- wastes are then atomized, ionized, and finally position to low molecular weight organic acids destroyed as they interact with the decaying of the remaining waste feed.70 Currently, the plasma species. There is less opportunity for process remains commercially applicable to the formation of toxic PICs. Most of the de- aqueous organic waste streams which are too struction occurs without progression of reac- dilute for incineration, yet too toxic for biolog- tions which could form them.66 ical treatment, Private tests conducted for the Canadian Still in development are catalytic modifica- Government have demonstrated 99.9999999 tions to the wet oxidation process, aimed at percent (i.e., 9-9’s) destruction on pure trans- the more stable highly chlorinated organics. former fluid (58 percent chlorine by weight).67 Bench-scale tests conducted by I. T. Envirosci- Depending on the waste, the gas produced has ence have demonstrated that a bromide-nitrate a significant fuel value.68 A high degree of proc- catalyst promotes completeness of oxidation. ess control and operational simplicity are addi- Should this process achieve destructions simi- tional advantages. For halogenated waste (a lar to those of incineration, its lack of air emis- major market target), the gases would have to sions, and the ease of using performance moni- be scrubbed but the scrubbers needed are very toring would be advantageous.71 small. Super Critical Water. —At temperatures and The process is in the public domain and near- pressures greater than 374° C and 218 atm, ing commercialization. The developer plans to water becomes an excellent solvent for organic market mostly small, self-contained, mobile compounds and can break large organic mole- units, Costs are intended to be competitive with cules down into molecules of low molecular incineration. 69 The first commercial applica- weight. 72 In a system patented by Modar, Inc., tion is planned to be in operation in July 1983. injected oxygen completely oxidizes the lower molecular weight molecules to carbon dioxide Wet Oxidation .-Proven in commercial applica- and water. DDT, PCBs and hexachlorbenzene tion, wet oxidation processes can destroy reli- have been destroyed with efficiencies exceed- waste (e. g., cya- 73 ably nonhalogenated organic ing 99.99 percent in bench-scale testing. Costs nides, phenols, mercaptans, and nonhalogen- 74 are expected to be highly dependent on scale. ated pesticides). The oxidation reactions are If high-destruction efficiency is maintained fundamentally the same as in combustion but occur in liquid state. Since it is not necessary ‘OP. Shaefer, Zimpro, Inc., personal communication, November 1982. 710ppelt, op. cit. 66 C. C. Lee, Office of Research and Development, IERL, Envi- 72M, Modell, “Destruction of Hazardous Waste Using Super- ronmental Protection Agency, personal communication, January critical Water, ” paper delivered at the 8th Annual Research Sym- 1983. posium on Land Disposal, Incineration, and Treatment of Haz- 67Plasma Research Inc., unpublished test results, January 1983. ardous Wastes (Fort Mitchell, Ky.: Environmental Protection 68Alternatives to the Land Disposal of Hazardous Wastes, op. Agency, Mar, 8, 1982). cit, 73Ibid. wT. Barton, Plasma Research Inc., personal communication, “Alternatives to the Land Disposal of Hazardous Wastes, op. January 1983. cit. 174 • Technologies and Management Strategies for Hazardous Waste Control through scaleup, this could be an attractive from a dilute waste stream does not necessarily alternative to incineration. provide any benefit in terms of increased protection of health. If this separation and concen- Biological Treatment tration treatment allows the waste constituent to be recovered or, alternatively, makes a de- Conventional biological treatments use natu- struction technology viable, the treatment has rally occurring organisms to degrade or re- been beneficial. move hazardous constituents. In contrast, biotechnology uses bacteria which have been Residuals from hazardous waste treatments selected from nature, acclimated to particular are discharged to surface waters, to publicly substrates, and mutated through methods such owned wastewater treatment works (POTWs) as exposure to ultraviolet light for fixation of or are sent to landfills or land treatment dis- the adapted characteristics. Many toxic sub- posal, To the extent that the treatments consid- stances cannot be degraded biologically, al- ered below can reduce the toxic characteristics though they may be effectively removed from of wastes through destructive or degradative a waste stream this way. Types of conventional reactions, they are similar in their effect to ther- biological techniques, waste stream applica- mal destruction technologies. To the extent that tions, and their limitations are listed in table they are able to mitigate specific hazard char- 29. These techniques have found widespread acteristics, they render the wastes nonhazard- use for treatment of municipal and industrial ous. And, to the extent that they reduce the wastes to prevent the formation of odorous mobility of the waste, they reduce the interac- gases, to destroy infectious micro-organisms, tion of land-disposed wastes with the environ- to remove nutrients for aquatic flora, and to ment. remove or destroy some toxic compounds. Sev- Many references exist describing unit physi- eral biological techniques may be used as a cal, chemical, and biological processes and series of steps to treat a waste, including end- how they may be combined. This discussion ing with landfarming (also called land spread- will not attempt to duplicate any such descrip- ing or land treatment]. The latter refers to the tive listings. Table 30 lists the established ap- deposit of a waste, or some sludge or residue plications. Selection of one or several processes from a treatment, onto land or injected some depends on such factors as waste feed concen- small distance beneath the surface. Naturally tration, desired output concentration, the ef- occurring organisms in the soil degrade the fects of other components in the feed, through- waste, usually organic, and periodic plowing put capacity, costs, and specific treatment may be necessary to ensure adequate oxygen objectives. levels for degradation. The physical, chemical, or biological proc- Landfills esses that can be used to eliminate or reduce Landfilling is the burial of waste in excavated the hazardous attributes of wastes exist in as trenches or cells. The waste may be in bulk many forms as those processes used to manu- form or containerized. In the early 1970’s, land- facture the original material. All of these treat- fills specifically designed to contain industrial ments produce waste residuals; usually a liquid waste were constructed. * Experience with the and a solid waste. The hazardous characteris- operation and construction of these more ad- tics of these waste residuals must be evaluated vanced landfills has been an evolutionary proc- in terms of the objective desired for their final ess, and is ongoing. disposition or recovery. Without such an objective it is difficult to evaluate the benefit, either Over time, fractions of the waste can be re- economic or environmental, of applying the leased from the landfill, either as leachate or treatment process. These treatments can result ● In 1972, Chemtrol announced the opening of the reportedly in merely changing the form or location of the first landfill designed to securely contain hazardous industrial waste. For example, concentrating organics waste. Ch. 5— Technologies for Hazardous Waste Management ● 175 as volatilized gases. The objective of landfill- the drainage layer instead of permeating the ing design is to reduce the frequency of occur- liner. Beds constructed of graded sizes of rence of releases so that the rate of release does gravel and sand are sometimes used as inter- not impair water or air resources. * Liquids mediate drainage layers to speed internal are able to leak through compacted clays or dewatering. synthetic lining materials. Reducing the potential for migration of toxic constituents from a Applicable Wastes landfill requires minimizing the production of Virtually any waste can be physically liquids and controlling the movement of those buried in a landfill; however, landfills are least that inevitably form. effective at controlling the migration of waste Liquids can enter a landfill in several ways: constituents which are volatile and soluble. Landfilled wastes that are toxic, persistent, • by disposal of free liquid waste, soluble, and volatile are most likely to pre- • by evolution from sludges and semisolids, sent a risk of human exposure. Federal regula- ● from precipitation infiltrating through the tions outline pretreatment requirements for cover into the landfill cell, and wastes which are ignitable, reactive, and/or • from lateral movement of ground water in- corrosive* but do not address characteristics filtrating through the sides or the bottom of persistence, toxicity, volatility, or volubility. of the cell. Current Use and Evaluation.–It is estimated that No one disputes the presence of liquids in 270 landfills are currently in use for hazardous a landfill; the objective of good landfill design waste disposal. (See ch. 4 for discussion of fa- is to control their movement. Flow of liquids cility data,) These facilities are among those through soil and solid waste occurs in response which may apply for RCRA authorization as to gravity and soil moisture conditions. When hazardous waste disposal facilities. the moisture content within a landfill exceeds field capacity, liquids move under saturated Existing landfills are constructed and oper- flow, and percolate to the bottom, Liquid move- ated with varying degrees of sophistication. ment under saturated conditions is determined Numerical information on the distribution of by the hydraulic force driving the liquid, and landfills that incorporate particular control fea- the hydraulic conductivity of the liner material. tures is not available. It is likely, however, that Hydraulic force can result in discharge through many existing facilities do not have any sort a liner, of constructed bottom liner nor any leachate or gas collection systems.75 Often, existing facil- Landfills can be designed to reduce migra- ities were sited with little regard to local hydro- tion, but there is no standard design. Advanced geology. The degree of sophistication of exist- designs would have at least the following fea- ing landfill facilities ranges from those that tures: a bottom liner, a leachate collection and have minimal control features and accept virtu- recovery system, and a final top cover. ally any waste, to those which combine a favor- Figure 10 depicts a landfill with these engi- able site location with waste pretreatment or neered features. Taken together, these features a restrictive waste policy, engineered control are intended to make it physically easier for features, leak detection, and ground water water to run off the surface cover instead of monitoring programs. Landfills also vary in infiltrating it and to collect leachate through capacity. Most are small (burying less than —— “Criteria for determining “impairment” of ground water are currently defined by a statistically significant increase over back- “More detail on regulatory requirements are discussed in the ground levels, or exceeding established limits, See discussion subsequent section titled “Technical Regulatory Issues, ” see also on ground water monitoring requirements, ch. 7. No criteria cur- ch. 7. rently exist for impairment of air resources; research is under- 75Environmental Protection Agency, Final EIS, Subtitle C, way to determine the magnitude and potential severity of gaseous Resource Conservation and Recovery Act of 1976, app. D, emissions. SW-189c. 1980. 176 . Technologies and Management Strategies for Hazardous Waste Control

Figure 10.—Generalized Depiction of a Hazardous Waste Landfill Meeting Minimum Federal Design Criteria

Final cover with sloping surface Bulk Drummed for surface drainage, vegetative solid waste Leachate 6-12 “ cover, middle drainage layer and waste and collection Intermediate low permeability bottom layer solidified 2! sump pipe cover # ml. #A--- / Separator berms

~-~ /

NOTE: This Is not a prescriptive or exact depiction of a landfill design, or Is It necessarily representative of all hazardous waste Iandfills. Alternative designs are allowed. See also figure 12 for detail on single and double liner design, S O U R C E: Off Ice of Technology Assessment, adapted from Draft RCRA Guidance Document, Landfill Design, Liner Systems and Final Cover, July 1982, and USEPA Draft SW-867, SW-869, SW-870, Municipal Environmental Research Laboratory, Cincinnati, Ohio, September 1980.

16,500 tons per facility in 1981).76 Smaller land- testing practiced by the operator, and the fills may tend to use less sophisticated control level of quality control over site operations. measures. Engineered Control Features Long-term landfill performance is determined by: A landfill has three primary engineered control features: a bottom liner(s), a leachate col- ● reliability the leachate collection the of lection system, and a cover. The bottom liner(s) system and the longevity of liner(s), and retard the migration of liquids and leachate top cover; from the landfill cells. Bottom liners are con- ● the hydrogeological characteristics of the structed of compacted clay, a clay and soil mix- site; ture, or synthetic material—often synthetic ● the characteristics of the waste prior to membranes. Leachate is collected through a disposal; and series of pipes buried in a drainage bed placed ● daily operations at the site–e.g., the liq- above the bottom liner. A. mechanical pump uids management strategy at the site, the raises the leachate through standpipes to the 76Westat, Part A Universe Telephone Verification Contract No. surface. The final cover reduces infiltration of 68-01-6322, Nov. 11, 1982. precipitation into the closed landfill. Intermedi- Ch. 5— Technologies for Hazardous Waste Management ● 177 ate covers can be applied for the same purpose or exchange of charged chemical species with during operation of the landfill. Table 33 sum- the clay particles.” marizes function and failure mechanisms for All liners exhibit some measure of hydrau- each of these components. lic conductivity; that is, they allow passage 1. Bottom liners.—The function of a liner of liquid under hydraulic pressure. * Based on placed beneath a landfill is to retard the migra- laboratory and field testing, typical ranges of tion of leachate from the landfill so that it can conductivity are approximately 10-11 to 10-14 be collected and removed. For synthetic liners, m/see for synthetic membranes, and 1O-g to retarding migration is dependent on their char- —— -— acteristic low permeability and compatibility “See for example, M. Lewis, “Attenuation of Polybrominated with a wide spectrum of wastes. For some com- Biphenyls and Hexachlorobenzene by Earth Materials” (Wash- pacted clay liners, migration of leachate is re- ington, D. C.: Environmental Protection Agency, No. 600/S2-81- 191, December 1981); and L, Page, A. A. Elseewi, and J. P. Mar- tarded both by their low permeability and by tin, “Capacity of Soils for Hazardous Inorganic Substances” the capacity of clays to decrease the concen- (Riverside, Calif.: University of California, August 1977). tration of certain waste constituents in the *For low permeability synthetics, the rate of fluid passage is difficult to measure because it is so close to passage in the vapor leachate through a variety of chemical reac- phase, Synthetics are tested under pressure, and their permeabil- tions—e.g., precipitation, filtration, adsorption, ity is back-calculated.

Table 33.— Engineered Components of Landfills: Their Function and Potential Causes of Failure

Function Potential causes of failure cover To prevent infiltration of precipitation into landfill cells. ● After maintenance ends, cap integrity can be threatened by The cover is constructed with low permeability desiccation, deep rooted vegetation, animals, and human activity. synthetic and/or clay material and with graded ● Wet/dry and freeze/thaw cycles, causing cracking and increased slopes to enhance the diversion of water. infiltration. ● Erosion; causing exposure of cover material to sunlight, which can cause polymeric liners to shrink, break, or become brittle. ● Differential settling of the cover, caused by shifting, settling, or release of the landfill contents over time. Settling can cause cracking or localized depressions in the cover, allowing pending and increased infiltration. Leachate collection and recovery system: To reduce hydrostatic pressure on the bottom liner, . Clogging of drainage layers or collection pipes. and reduce the potential for flow of Ieachate ● Crushing of collection pipes due to weight of overlying waste through the liner. ● Pump failures. Leachate is collected from the bottom of the landfill cells or trenches through a series of connected drainage pipes buried within a permeable drainage layer. The collection Ieachate is raised to the surface by a mechanical pump. Bottom Iiner To reduce the rate of Ieachate migration to the subsoil. . Faulty installation, damage during or after installation. ● Deformation and creep of the liner on the sloping walls of the landfill. ● Differential settling, most likely to where landfill is poorly sited or subgrade is faulty. Structural failure of the liner in response to hydrostatic pressure. Degradation of liner material resulting from high strength chemical Ieachate or microbial action. ● Swelling of polymeric liners, resulting in loss of strength and puncture resistance. ● Chemical extraction of plasticizers from polymer liners. SOURCE Office of Technology Assessment 178 ● Technologies and Management Strategies for Hazardous Waste Control

10-11 m/see for clay liners.78 The units of meas- material used, they may respond by stretching ure for hydraulic conductivity involve a thick- or tearing. In the past, liners were often in- ness component. Thus, although an intact syn- stalled by contracting firms which had minimal thetic material has a very low conductivity, technical expertise and little motivation to be they are very thin. * In comparison, clay liners assiduous in their installation practices. More often range in thickness from several feet to recently, manufacturers of synthetic liners and several yards. designers of clay liners are combining the sale of their products with actual installation, in All liner materials are subject to breaches in order to maximize performance of their prod- their physical integrity. With the exception of uct and protect business.80 Certification of obvious chemical incompatibilities that can proper liner installation is not currently re- rapidly deteriorate a liner, these failures can quired by EPA, but it is required by several be a more important factor in increasing the states.81 rate at which liquids can migrate than the inherent conductivity of the liner. Two major Liners are also subject to damage after instal- sources of structural failure for all liners are lation. One source of damage is vehicular traf- incorrect installation and damage during or fic at the site–e.g., the heavy equipment used shortly after installation. to spread sand and gravel directly on top of the liner to place the drainage layer for collection Proper installation of any liner requires con- of leachate. Synthetic liners are vulnerable to siderable technical expertise. For clay liners, localized tears and punctures. Clay liners can the moisture content of the clay prior to com- also be damaged after installation—e.g., slump- paction and the method of compaction are crit- ing of the clay can occur on side slopes.82 Once ical factors. For example, varying the water a liner has been covered by the drainage layer, content in a clay prior to compaction can result it is impossible to visually inspect it for dam- in differences of two orders of magnitude in age. the permeability of the clay.79 For synthetic liners, proper welding of the seams joining the Chemical reactions between liner and leach- panels of the liner and avoiding damage to the ate can significantly increase liner permeabil- dimensional stability of the membrane fabric ity.83 84 85 For example, organic or inorganic are critical. Damage to liner fabric stability can acids may solubilize certain minerals within occur while stretching synthetic liners over the clays and a variety of organic liquids dissolve large areas involved in landfills. For example, the monomers within PVC lines. a single large panel of synthetic material may 2 Laboratory tests can identify obvious chem- cover 20,000 ft feet and weigh 10,000 lb. ical incompatibilities between a liner material Preparation of the soil under the liner is criti- and an expected leachate, and can also project cal to the performance of all liners. Proper general wear characteristics. (Table 5A-1 in preparation is necessary to prevent local defor- app. 5A summarizes the findings of such tests.) mational stresses. Clay liners are likely to respond to deformational stress by shearing. De- OOR. Kresic, Midwest Accounts Manager for Schlegel Lining pending on the characteristics of the synthetic Technology, Inc., Ohio, personal communication, November 1982. oID. Lennett, Environment~ Defense Fund, persomd communi- 78ED. J. Folkes, Fifth Canadian Geotechnical Colloquium, “Con- cation, December 1982. trol of Contaminant Migration by the Use of Liners, ” National ~EnvironmentaI Protection Agency, Lining of Waste hnpound Research Council of Canada, April 1982. ment and Disposal Facilities, SW-870, ch. 4 “Failure Mecha- ☛ Synthetic membranes are produced in thicknesses ranging nisms,” September 1980. from 0.5 millimeters (20 roils) to 2.5 milimeter (100 roils). J. P. ~Ibid. Giroud and J, S. Goldstein, “Geomembrane Liner Design,” Waste ‘H. E. Haxo, “Interaction of Selected Liner Materials With Age, September 1982. Various Hazardous Wastes” (Cincinnati, Ohio: Environmental 79David E. Daniel, “problems in Predicting the permeability Protection Agency (NTIS No. 600/9410-010)). of Compacted Clay Liners, ” Symposium on Uranium Mill Tail- ‘D. Anderson, “Does Landfill Lestchate Make Clay Liners ings Management, Colorado State University, Geothermal Engi- More Permeable?” Civil Engineering-–ASCE, September 1982, neering Program, Ft. Collins, Colo., October 1981. pp. 66-69. Ch. 5— Technologies for Hazardous Waste Management ● 179

However, laboratory data cannot directly pre- treated and discharged or redisposed in the dict performance under actual field conditions. landfill. 89 Laboratory tests are conducted on only a small The levels of leachate within a landfill will sample of the liner material; this presents prob- change with time in response to infiltration, lems for estimating field permeability y of clays. pumping, and recharge rates, High leachate Calculations of liner permeability based on levels must be reduced by pumping in order field measurements demonstrate that labora- to reduce hydraulic pressure on the bottom tory estimates are frequently too low. Develop- 90 liner. In general, doubling the height of the ment of improved field techniques are under- 86 87 ponded liquid doubles the force driving the way. Also, laboratory tests cannot account 91 leachate through the liner. Information from for possible damage in the physical integrity commercial landfill facilities show that liquids of the liner material resulting from installation, levels can reach over 10 ft. If the system is operation, and long-term wear in the potential- working properly, the leachate can easily be ly harsh service environment of a landfill. This 92 pumped out. Conversely, pumping can be may compound problems in projecting the hampered by technical difficulties such as the service life of synthetic liners. * inability of the cover to prevent further infiltra- Further, testing for chemical compatibility tion. In such cases, reducing leachate levels requires prediction of expected leachate char- can take months to years.93 acteristics over time. This is difficult for land- After land filling operations end, leachate is fills accepting a variety of waste types. Some required to be pumped out during the post- landfill facilities segregate waste into cells to closure period “until leachate is no longer de- make leachate prediction simpler and more re- 94 tected.” Failures in the collection system liable. which impede leachate flow to the pump might 2. Leachate collection system.—Leachate be misinterpreted as the end of leachate genera- collection systems are a series of perforated tion. Some failures, such as poor leachate trans- drainage pipes buried at the lowest points with- mission through the filter beds or collapse of in a landfill. These pipes are designed to col- the drainage pipes, are both difficult to detect lect liquids which flow under the influence of and to repair. gravity to the low points, Once the collected 3. Cover.–After operations at the landfill liquids reach a predetermined level, they are 88 have ceased, the final cover is installed, The pumped to the surface. Overall, the system function of the final cover is to reduce the in- operates much like a sump pump in a house- filtration of water and to provide a physical hold. Liquids that are recovered are tested for barrier over the waste. To do this, it must re- their hazardous characteristics. If the liquids main structurally sound over time. Covers can are determined to be hazardous (under the be constructed of layers of synthetic mem- RCRA criteria for hazardous waste), they are branes, clays, and soil. Leachate standpipes pierce the cover in order to project into the 86D. E. Daniel, “Predicting Hydraulic Conductivity of Clay Liners” (Austin, Tex,: University of Texas, Department of Civil landfill cells, Soil is placed over the cover, and Engineering, 1982). vegetation is established to stabilize the soil. E7R. E. O] Son and f), E, Daniel, ‘‘Field and Laboratory Measure ment of the Permeability of Saturated and Partially Saturated Fine Grained Soils” (Austin, Tex.: University of Texas, Depart- ~EnVirOnMental protection Agency, hlanagernen ~ Of HaZard- ment of Civil Engineering, june 1979), ous Leachate, SW-871, September 1980, ● For example, manufacturers of synthetic lining material war- ‘EPA, op. cit., SW-870, 1980, sec, 5,6, ranty their product for a specified time period [e. g., 10 to 30 91 D, Daniel, persona] communication, October 1982. years) against material defects in compounds and workmanship 9zB. S1 monsen, vice president, IT CO rp., and P. Va rdy, Vice which would affect performance, However, the warranty can President of Waste Management, Inc., personal communication, be voided if the liner material shall have been exposed to harm- December 1982. ful chemicals, abused by machinery, equipment or persons, or ‘3P. N. Skinner, “Performance Difficulties of ‘Secure’ Land- if installation is Inadequate, fills in Chemical Waste and Available Mitigation Measures, ” WK. Malinowski, CECOS International, New York, personal American Society of Chemical Engineers, October 1980. communication, August 1982. s447 FR 32,366, July 26, 1982. 180 ● Technologies and Management Strategies for Hazardous Waste Control

Covers are subject to a number of failure Figure 11 .—Potential Failure Mechanisms for Covers mechanisms (see table 33). Some of these, such as erosion or piercing of the cover by plant roots, can be reduced through proper and continued maintenance and repair of the site. * However, if maintenance ends, the integrity of the cover will be threatened by ubiquitous weathering processes, such as desiccation, ero- A) Cracking of cap sion, and freeze/thaw cycles. Deep-rooted vege- due to settlement tation, burrowing animals, and human activity can also cause damage. Depending on the site location and pretreatment of the waste, the risk of leachate migration caused by infiltration through the cover may be reduced before the facility operator’s maintenance responsibility ends. These factors are critical, since the cover is the primary line of defense against waste migration after the post-closure period. B) Collapse of cap into open voids Other potential sources of cover damage cannot be prevented by simple maintenance. Fore- most among these are subsidence damage and deterioration of synthetic membranes over time. Subsidence refers to the settling of the waste and the cover; subsidence damage has been identified by EPA as one of the most critical factors resulting in poor landfill perform- 95 C) Pending of water ance. Figure 11 depicts a cover designed with in depressions a gently sloping crown to facilitate runoff, and examples of cover failure. Ideally, the crown should be designed and constructed to com- pensate for estimated long-term subsidence. However, there are several factors which make this difficult.96 Comparatively uniform subsidence might be expected to occur for landfills containing one D) Cracking of cap form of waste (i.e., a monofill). Many landfills, due to desiccation however, contain a variety of wastes, both containerized and in bulk. Bulk liquids and sludges 4 ● Under current regulations, the landfill operator is required to maintain the site for 30 years after closure. If the facility operator has met the requirements for monitoring and closure, the Post-Closure Liability Fund established under CERCLA can be used to pay the costs of monitoring, care, and maintenance of the site thereafter, and if funds are available. See ch. 7; also Public Law 98-510, sec. 107(k)(l). 95G, Dietrich, former Director of EPA’s Office of Solid Waste, E) Proper design in testimony at the Mar. 11, 1982 public hearing on containerized SOURCE. “Shallow Land Burial of Low-Level Radioactive Waste, David Daniel, liquids in landfills. AM, ASCE Journal of Geotechnical Engineering Division, January 96Skinner, op. cit., pp. 17, 20-23. 1983, Ch. 5— Technologies for Hazardous Waste Management ● 181

provide little internal structural support. Va- to locate leak sources are being developed.l00 porization may also be a problem. Containers Exhuming the waste is costly and potentially do provide short-term support, but they deterio- dangerous. Alternatively, pumping leachate rate, often within a few years. The rate of con- can reduce the volume of leachate available for tainer deterioration is difficult to predict; it migration. Generally, leachate is removed by depends on site- and waste-specific factors. It pumping from the collection system above the may not be possible to compact a mixed waste liner. OTA found little information on leak landfill sufficiently, e.g., compaction compar- detection systems designed as secondary leach- able to preparation of a building foundation. ate removal systems, although this seems a Further, the internal structure of the landfill promising area for future engineering design. cells is constructed of compacted support If infiltration through the cover is determined walls, which retain their original height while to be the cause of migration, the cover can be the wastes within settle. Cracking around the repaired (subsequent repairs may be neces- perimeter of the cover has resulted.” Finally, sary). The more complex and sophisticated the the extraction of collected leachate produces design of the cover, the more difficult and cost- void spaces and exacerbates settling. ly it is to repair. Cover repair may require care- Some of these subsidence concerns are being fully peeling back each protective layer until addressed by landfill operators. For example, each is found to be sound. Cover repair gener- some commercial facilities place drummed ally requires partial reconstruction of gas col- waste on its side, a position providing less lection and cover drainage systems, recompac- structural support, in order to hasten the col- tion of soil layers, and revegetation of the sur- lapse and settling of the buried drums.98 This face soil, These procedures generally require reduces future subsidence by enhancing the work done by hand. Depending on the geo- structural stability of the landfill prior to install- graphic location of the landfill, repair opera- ing the final cover. Other facilities prohibit tions can be precluded during wet weather; the burial of liquids and emphasize treatment to same conditions that exacerbate further dam- enhance structural stability. *Q age.101 Ultimately corrective actions at landfills may rely primarily on mitigating the effects Correction of Failure Mechanisms.—The failure (e.g., cleansing ground water, diverting con- mechanisms described can enhance the migra- taminated plumes) of the failure rather than tion of waste constituents. The ability to cor- correcting the cause of the failure. rect potential failures is critical to landfill performance. Hydrological Characteristics of the Site Detection of excessive contamination from leachate migration, either through a leak-detec- Site hydrology encompasses the properties, distribution, and circulation of water on the tion system or external ground water monitor- land surface, in the soil and underlying rocks, ing, requires corrective action. Repairing the and in the atmosphere. Hydrological informa- source of the leak is generally not possible. tion includes data on the interrelated effects Liner repair requires: 1) locating the source of of geological and climatic characteristics on the leak, and 2) exhuming the waste. The first the properties and circulation of water. Over is difficult, although remote sensing techniques geologic time, these processes have shaped the ‘7P. Varty, Vice President, Waste Management Inc., personal communication, January 1983. 100 A comparison of these techniques has been prepared by BaFor example, Waste Management Inc. and SCA Chemical Wailer, Muriel Jennings, and J. L. Davis, “Assessment of Tech- Waste Services, Inc. nologies To Detect Landfill Liner Failures, ” in proceedings of w]. Greco, Divisional Vice President, Government and Industry the Eighth Annual Research Symposium, EPA 600/9-82-002, Affairs, Browing-Ferris Industries, personal communication, March 1982. June 1982. 101 Skinner, op. cit. 182 . Technologies and Management Strategies for Hazardous Waste Control environment within which the landfill must A variety of treatments can be used to im- operate. prove the structural stability and reduce the There are two key site characteristics critical mobility of landfilled waste. These techniques to the design and operation of landfills: general convert waste into a solid with greater struc- climatic characteristics that determine the tural integrity, Stabilized or solidified waste amount of leachate generated and the charac- are less likely to leach from a land disposal teristics of the underlying geology that deter- site than are untreated waste—even though mine the potential for liquids to migrate and the physical and chemical characteristics of the consequent risk of migration from the site, the constituents of the waste may not be The potential for leachate generation and mi- changed by the process. Stabilization/solidifi- gration can vary markedly depending on the cation usually involves the addition of materi- characteristics of the site, An engineered land- als that ensure that the hazardous constituents fill sited over many feet of native low-perme- are maintained in their least soluble form. ability clays, resting on unfractured bedrock, Stabilization/solidification processes can be and in an area where evaporation historically categorized as follows:105 106 exceeds precipitation is less likely to impair ground water, In contrast, an engineered land- ● Cement-based process.—The wastes are fill relying solely on a synthetic liner, sited on stirred in water and mixed directly with unconsolidated dredged fill material, overlying cement. The suspended particles are incor- fractured bedrock, and in an area where pre- porated into the hardened concrete. cipitation historically exceeds evaporation, is ● Pozzolanic process.–The wastes are more likely to result in migration of excess mixed with fine-grained silicicous (poz- leachate. zolanic) material and water to produce a concrete-like solid. The most common ma- EPA has established criteria for siting low- terials used are fly ash, ground blast-fur- level radioactive waste landfills, which state nace slag, and cement-kiln dust. that “locations for radioactive waste disposal ● Thermoplastic techniques.-The waste is should be chosen so as to avoid adverse envi- dried, heated, and dispersed through a ronmental and human health impacts and heated plastic structure. The mixture is wherever practicable to enhance isolation over 102 then cooled to solidify the mass. time.’’ Current interim final regulations for ● Organic polymer techniques.-The wastes hazardous waste disposal have only incentives are mixed with a pre-polymer in a batch (in terms of reduced monitoring requirements) process with a catalyst. Mixing is termi- for landfills sited in areas with exceptionally nated before a polymer is formed and the protective natural hydrology. No outright re- spongy resin-mixture is transferred to a strictions exist for sites with poor hydrological 103 waste receptacle. Solid particles are features. trapped in this spongy mass. ● Surface encapsulation.—The wastes are Characteristics of the Waste Prior to Disposal pressed or bonded together and enclosed A wide variety of wastes are currently land- in a coating or jacket of inert material. filled, Certain waste characteristics and dis- The type of waste most amenable to stabiliza- posal methods make waste containment diffi- tion, solidification, and encapsulation tech- cult, For example, landfilling bulk liquid waste niques are inorganic materials in aqueous solu- plays an important role in site destabilization, tions or suspensions that contain appreciable One researcher notes that disposal of waste liq- 104 amounts of metals or inorganic salts (e.g., uid has “changed little in the last 30 years.’’ metal-finishing waste). Metal ions in these res- I02R. Abrams, “Comments to U.S. Environmental Protection Agency Regarding Proposed Amendments to 40 CFR 265: Spe- cial Requirements for Liquid Waste, ” 1982. 105state of California, 0p. cit. 10sFR vo]. 47, July 26, 1982. l~Martin, Oppelt, and smith, “Chemical, Physical, Biological ~04Anderson, op. cit. Treatment of Hazardous Wastes,” September 1982. Ch. 5— Technologies for Hazardous Waste Management ● 183

idues are held as relatively insoluble ions in a tribution is used to its best effect. Examples of crystalline lattice. such actions are: Waste containing more than 10 to 20 percent 1. some facilities emphasize land burial of organic substances are generally not good can- waste treatment residuals which are gener- didates for this treatment method. Their di- ally less toxic and mobile, than untreated verse properties interfere with the physical and waste; chemical processes that are important in bind- 2. some facility owners and/or operators ing the waste materials together. Some solidify- have sought out especially protective hy- ing reagents may never harden if the waste drological settings for construction of contains inhibiting materials. Silicate and ce- landfills; ment reactions can be slowed by organics or 3. some facilities segregate wastes with simi- by certain metals. Organic polymers can be lar characteristics. This facilitates leachate broken down by solvents, strong oxidizers, prediction and testing for liner compara- strong acids, or by exposure to sunlight. bility; 4. several waste handlers have established a Solidification pretreatment provides extra strict prohibition against burial of liquids, environmental protection in land disposal of in bulk or in containers; treatable residues. For specific wastes, certain 5. some manufacturers of synthetic lining chemical stabilization treatments so thoroughly materials provide compatibility testing and immobilize toxic constituents in EPA approved installation with the sale of their product tests that they have been tentatively removed sale; from hazardous waste regulation. ’”’ Usually, 6. some firms are researching methods to in- however, some metal cations remain somewhat corporate the natural attenuation capacity mobile. In addition, there are considerable ob- of clays in their liner designs. That is, they jections to EPA’s leaching test as a stimulation attempt to correlate expected leachate of landfill conditions. characteristics to the attenuative capacity Some of the stabilization processes result in of the clay so that the leachate that even- products that have compression strengths simi- tually passes through meets specific water lar to cement or concrete. The durability of quality criteria; and stabilized waste to wet/dry and freeze/thaw 7. some landfill design firms are prospective- cycles, however, has generally not been good. ly designing land-fills to make corrective Stabilization/solidification processes generally actions easier—e. g., to facilitate installa- improve the physical handling characteristics tion of a grout curtain to reduce lateral of the waste, enhance structural integrity of the migration of ground water of contami- landfill, and eliminate the “free-liquid” status nated leachate plumes. of the waste. Mixing waste with various absorbents can also remove the free-liquid status, Evaluation of Current Landfill Performance but generally leaves the toxic constituents more Releases should be minimized, but there are soluble and mobile than the chemical stabiliza- substantial differences in philosophy about tion methods. what this “minimization goal” means. The Current Landfill Practice EPA narrative performance standard for landfills, states that landfill liners should prevent Many improvements in landfill operation migration of leachate for the operating life of have occurred since passage of RCRA Further- the fill (i.e., the landfill system should be 100 more, waste handlers, landfill designers, and percent effective in its control of leachate) and liner manufacturers are taking steps to ensure that migration should be minimized there- their specific facility, product, or service con- 108 —. after. This criteria fails to recognize that, 107F. Kelley, Stablex Corp., and H. Busby, Chemfix Corp., personal communication, November 1982. 108FR VOl. 47, July 26, 1982, p. 32314. 184 ● Technologies and Management Strategies for Hazardous Waste Control because of the potential failures discussed, pabilities of each of the control features of a complete prevention of migration even during landfill, and 2) greater use should be made the operating life is probably unattainable. In of waste treatments which increase waste sta- fact, RCRA standards for ground water qual- bility as well as reduce long-term mobility of ity recognize that complete prevention may not waste constituents. be necessary. These standards for contaminant EPA is conducting additional analyses of fail- levels in ground water will be the criteria 111 ures that have occurred at existing sites. against which landfill performance will be Such analyses invariably indicate that poor per- judged. Critics argue that evidence of contami- formance can be attributed to poor operating nation is a poor criterion because it may not practice, design, or maintenance. Operation of be detected, could be widespread before it is any facility will always be subject to error or detected, and aquifer cleanup is expensive and misjudgment; this underscores the importance may be unachievable (see also “Technical Reg- of site and waste characteristics, the necessity ulatory Issues”). of designing for both reliable indicators of po- The first generation of landfills designed spe- tential failure, and corrective action capability. cifically for disposal of hazardous waste are There is room to improve in ‘both of these areas. now in the ground.109 Quantitative data on their The performance standards and minimum current effectiveness is limited. Data provided design requirements for new landfills are based by a study of four landfills in New Jersey, on the experience gained in recent years. How- which had leak-detection systems installed, ever, as noted frequently in the preamble to showed they began collecting between 45 to 75 110 EPA’s land disposal regulations, there is lim- gal/day within months of their construction. ited experience and operating data for landfills Although controversial, this study concluded (or closed surface impoundments). This lack that the collection of liquids was due to failure of information hampers the development of of the primary liners. No landfills have been 112 closed long enough to test the effectiveness of performance design guidance. Laboratory and field testing of liners and covers is under- long-term maintenance or corrective actions. way. Little is being done to monitor actual fa- There is little quantitative evidence on which to project landfill performance, especially over cility performance; yet it is unlikely that our current experience is adequate to anticipate all the long term. future difficulties. Without better information Future evaluations of landfill performance on actual facility performance, it will be diffi- will depend on monitoring. The external cult to evaluate landfills constructed according ground-water monitoring currently required to minimum design requirements, or to evalu- may not be sufficient (see ch. 7). In comparison ate alternative landfill designs, There are tech- to external monitoring, however, leak-detection nical methods available to improve our infor- systems embedded within a double liner may mation base. provide more reliable information on potential resource degradation and human exposure. In-situ instrumentation for systematically gathering data on the following performance By examining how landfills work, their fail- indices has been suggested:113 ure mechanisms, and available corrective measures, OTA’S review of landfill perform- 1. leachate accumulation at sites other than ance resulted in two principle findings: 1) un- manholes; certainty remains about the performance ca- 111William L. Murphy Rohrer, Senior Environmental Scientist, Pope-Reid Associates, Inc., personal communication, January 109A. L. Kruger, “Alternatives to Landfilling Wastes” (Prince- 1983. ton, N. J.: Princeton University, Department of Chemical Engi- 112Comments to EPA regarding proposed rules, “Docket 3004, neering, Ph.D. Thesis, February 1982). Permitting Standards for Land Disposal Facilities,” prepared by 110Peter Montague, “Hazardous Waste Landfills: Some Lessons the New York State Attorney General, Robert Abrams, Nov. 9, From New Jersey, Civil Engineering-ASCE, September 1982, pp. 1982. 53-56, and more detailed unpublished draft. 113Ibid., p. 4. Ch. 5— Technologies for Hazardous Waste Management ● 185 —

2. stress/strain characteristics of synthetic tion of leachate into the liner during the oper- membranes; ating life of the facility. This could favor the 3. settlement of individual lifts inside the selection of synthetic membrane liners, since cells; they can absorb de minimis quantities of 114 4. leachate delivery to leachate collection leachate. This preference tends to isolate the system; capability of a liner from the rest of the engi- 5. differential and areal settlement of the neered landfill system, its environmental set- cap; ting, and the persistence and toxicity of the 6. seasonal moisture contents of the cap; waste it contains. 7. erosion rates of cap soils; Furthermore, this preference could inhibit a. actual cap infiltration rates; the comparative evaluation of clay and synthet- 9. three-dimensional chemical conditions ic liners, and overlooks uncertainties about the inside the cells, especially in the vicinity long-term limitations of any liner material. A of the liner face; more farsighted approach might require the 10. gas evolution rates in particular cells; and use of both a synthetic and a compacted clay 11. contaminant transport phenomena in soil liner. The synthetic liner would be used to col- liner. lect the more concentrated leachate likely to be produced during the operating life of the Technical Regulatory Issues facility. This would protect the clay liner from The current regulatory framework will affect the concentrated leachate constituents which the future use, operation, and design of land- can increase the permeability of the clay liner, fills. Liability requirements may encourage cer- thus enhancing the long-term integrity of the tain industry sectors to employ alternative clay liner backup.115 treatment technology or waste reduction activ- Restrictions on Waste Being Landfilled.–In July I ities. f implemented, requirements to demon- 1982, detailed rules were issued defining strate financial responsibility for future correc- wastes allowable for landfilling. Treatments tive action may be an even greater incentive are required to mitigate waste characteristics (see also ch. 7). of ignitability, reactivity, and corrosiveness. In- Current regulations will require upgrading compatible wastes cannot be placed in the the design of new facilities to include the use same landfill cell. These requirements should of liners, guidelines for waste pretreatment, greatly reduce the hazards of fires, explosions, leachate collection systems, and covers. Exist- and generation of toxic fumes. There are no ing portions of facilities are broadly exempted restrictions against landfilling highly toxic, per- from retrofitting that do not have the minimal sistent waste and no treatments are required control features of a liner or collection system. to mitigate a waste constituent’s toxicity or mobility.116 Containerized liquids cannot be The current regulations will influence the landfilled unless the liquids are rendered not construction and operation of landfills. Key free flowing. Many treatments that can modify regulatory points with likely impacts on future the free liquid form do not immobilize toxic use of landfills are: constituents. The regulations allow the disposal ● a preference for the use of artificial liners; of free waste liquids into landfills with syn- ● minimal restrictions on the waste allowed thetic liners and leachate collection systems. to be landfilled; and Siting Restriction.—The current regulations ● minimal restrictions on the siting of land- contain only minimal siting restrictions. For fills.

Influence on Liner Selection.–The current regulations state that liner materials for new hazardous waste landfills should not allow migra- 186 ● Technologies and Management Strategies for Hazardous Waste Control example, they suggest that new landfills should ards, and monitoring programs more demand- not be sited within a 100-year flood plain, but ing than Federal requirements, including the that if they are, they should be designed to use of a double liner.119 117 withstand such a flood. Many believe that For landfilling, the regulations establish the restrictions should be imposed on sites based minimum design requirements for landfill on proximity to natural features such as major liner system and methods for leachate monitor- supplies of ground water used for drinking, ing—i.e., one bottom liner* and external moni- designated sole-source aquifers, aquifer re- 118 toring via ground-water wells for detecting and charge areas, sink holes, and wetlands. Such assessing the effect of leachate migration (see site characteristics are not addressed by the fig. 12). The reliability of this design is inferior regulations. to a double liner with a leak-detection system. Technology Forcing. —Although EPA is promot- There is an incentive to promote the use of this ing the use of some technologies in their most more advanced design, through granting an ini- advanced form, less reliable landfilling designs tial waiver of the ground-water monitoring are allowed. Incinerator performance stand- program, ards have been set close to the limits of their known technical capabilities. Meeting these re- Surface Impoundments quirements for routine incineration at many existing facilities will require improvements in Surface impoundments are depressions in engineering design and operation of the facil- the ground used to store, treat, or dispose of ity. However, owners and operators of many a variety of industrial wastes. They have a vari- existing landfills have already instituted volun- ety of names: lagoons, treatment basins, pits, tary or State-mandated operating, design stand- 117Ibld,, pp. 32, 290. 119Burmaster, op. Cit. l18David Burmaster, “Review of Land Disposal Regulations, ” *As discussed above, the single liner is likely to be a mem- paper submitted to OTA Materials Program, November 1982. brane liner.

Figure 12.—Schematic of Single and Double Synthetic Liner Design Landfills—double liner Landfills—single liner —

\ Drainage, layer Liners F f Leak detection system between liners -Ground water “1 1 monitoring well i I b 070 Liner Unsaturated zone “\ 1 Leachate collection . and removal system ~ ‘\ ‘,,

I D Ground water ~1 I I This is the new minimum requirement for newly If two synthetic liners and a leak-detection system are constructed landfills: a single liner (probably a synthetic used as- shown above, no ground water monitoring is membrane), a Ieachate collection system, and ground initally required under the new regulations. water monitoring wells. SOURCE: Civil Engineering–ASCE, January 1983 Ch. 5— Technologies for Hazardous Waste Management • 187 —. —.. .—. — — ...... and ponds.120 These depressions can be natural, especially true for unlined impoundments. In- man-made, lined, or unlined. They can be sev- vestimations at some unlined “evaporation eral feet in diameter or hundreds of acres in ponds” have shown that seepage accounted for size. more of the reduction in volume than did evaporation. 125 In general, these release pathways Applicability are addressed by Federal regulations (see also “Technical Regulatory Issues”). The majority of wastes put into surface impoundments come from four industrial groups: There is an expected rate of leakage even paper and allied products, petroleum and coal through intact liners. Some liquids are chem- products, primary metals, and chemicals and ically aggressive to liners, increasing the rate allied products.121 These wastes are generally of movement through the liner. Leakage occurs impounded as hulk liquids or sludges. in much the same manner described in the pre- vi s section for landfills. The rate of leakage Surface impoundments are used either to ou generally depends on the same factors (see dis- treat or store industrial wastes. For treatment, cussion of liners in the “Landfill” section). For surface impoundments are widely used for de- impoundments, one primary difference is that watering sludges, neutralizing and separating there is always a hydraulic gradient acting on waste constituents, and biodegrading waste the liner. An additional concern is how long waters. Storage simply refers to temporary the wastes are held in the impoundment before holding. Although estimates of capacity vary, their hazardous characteristics have been miti- national estimates indicate that there are ap- gated, proximately 1,100 surface impoundments used for hazardous waste, covering a total area of Some organic liquids currently being held in close to 29 million yd2 [see ch. 4). impoundments are volatile. Volatilization for many organic chemicals can occur at normal Evaluation atmospheric temperatures and pressures. This has recently led to investigations of the poten- Surface impoundments have allowed release tial magnitude and severity of organic air emis- of hazardous waste constituents through cata- s ions. strophic failure, leachate migration, and volatilization of organics. Impoundments are more There is little field data to indicate the mag- subject to catastrophic failure than landfills nitude of air emissions from surface impound- because they tend to contain more bulk liquid. ments, Most of the information available is Evidence of surface- and ground-water con- from mathematical models that estimate an tamination resulting from impoundments is emissions rate from the many factors influenc- well documented.122 This has occurred from ing volatilization, These include the concentra- sudden releases; e.g., by overtopping the sides, tion of organics in the waste, their vapor pres- dike failures, or rupture of the liner due to in- sures and solubilities, environmental factors adequate subgrade preparation, or sinkhole such as air and water temperature, wind veloc- formation. 123 124 In addition, slow leakage can ity, and the surface area of the impound- contaminate soil and ground water, This is ment,126 127

—— . — 1zS&5’[lrfa~e lmp~[ln dn]en is and 7’heir Ii fffx:t

Many of the models were designed to repre- control, Because of this lack, there is a tenden- sent other environmental transport phenome- cy toward qualitative approaches to liner de- non, e.g., evaporation from oceans or lake ba- sign. It is often assumed, for example, that sins, and have been adapted for application to liners are either impermeable or of such low organic emissions. Consequently, estimates of permeability that further analyses are not re- emissions derived from these models must be quired. The end result can be failure of the liner to perform as intended. viewed with caution. Nonetheless, the models estimate a significant rate of emissions. For ex- Similarly: ample, emissions from a 1/4-acre impound- . . . in engineering, past practice has frequent- merit, ” holding 100 mg/l benzene and 100 mg/l ly meant to assume that fine grained soils are chloroform, are estimated to be almost 45 lb/hr effectively ‘‘impervious" and to forego at- of benzene and 39 lb/hr of chloroform. 128 This tempts to measure their coefficient of perme- rate of emissions would decline but continue ability y. until a covering was installed. Further model The regulatory incentive for installation of development work, including validation sam- 129 double liners with leak-detection systems ap- pling, is underway. plies also to impoundments. However, in contrast to leak-detection systems currently used Technical Regulatory Issues with landfills, OTA found that detection sys- The effectiveness of the interim final regula- tems placed beneath the primary liner of an im- tions lies in how well they improve the per- poundment can be used to routinely remove formance of surface impoundments over past the liquids from between the liners. This re- practices. The Federal regulations require that duces the hydraulic pressure from the second- new impoundments have a liner, and establish ary liner. In some cases, this kind of leachate the minimum design and performance stand- detection and removal system are already used ard; i.e., a single liner intended to meet the nar- to remove the liquids expected to migrate rative performance criteria stating that the through the primary liner.133 Ground water at liner must “prevent any migration” of waste sites which are especially vulnerable to con- constituents out of the impoundment during tamination would be better protected by this its active life.130 Although these requirements system. Instead, the regulations allow the use for liners will reduce leakage, the literal nar- of a single liner, and rely on. an external rative standard is probably technically infeasi- ground-water monitoring net to detect waste ble. Lining materials have long been used to constituents in excess of ground water stand- reduce seepage and economic losses of stored ards. liquids, however the use of liners for pollution As with landfills, a broad exemption from the control is comparatively new. A great deal of requirement for any liner is allowed for exist- R&D in liner technology will be required to ing impoundments. Development of remote- meet these standards. Two researchers state 131 132 sensing techniques to detect leakage at existing the issue well: sites has recently begun.134 EPA is also inves- There is a lack of formalized design proce- tigating techniques for retrofitting synthetic dures to accomplish the objective of pollution liners at existing impoundments.135 Combining these efforts with information about the char- *With a depth of 3.5 meters, ambient temperatures of 25” C, and wind speeds of about one-tenth mph. —.— -. — l*81bid,, p. 81, 1 Sspeter vardy, waste Management 1 nc., personal com mun lca - Itestek,e lames, project officer, Municipal Environmental Re- tion, January 1983. search Laboratory, personal communication, January 1982, IJ~Waller and Davis, op. cit., in proceedings of the Eight An- 130FR 32,357, July 26, 1982. nual Research Symposium, EPA 600/9-82-002, March 1982. ljl Folkes, op. cit. lj~John W. Cooper and David Schultz, “Development and Dem- I UR, E, O]son and D. E. Daniel, “ f’ield and Laboratory h~eas- onstration of Systems to Retrofit Existing I,iquid Surface Im- urement of the Permeability of Saturated and Partially Saturated poundment Facilities With Synthetic Membrane, ” in Manage- Fine-G rained Soils, ” Geotechnical Engineering Report CR 80-5, ment of Uncontrolled Hazardous Waste Sites, conference pro- Department of Civil Engineering, University of Texas, June 1979, ceedings, Washington, D. C., December 1982, Ch. 5— Technologies for Hazardous Waste Management ● 189 acteristics of the site and the waste could re- ifornia has suggested both limits on the amount duce reliance on detection monitoring and re- of volatile organic material that can be land- medial action. disposed and limiting the time certain wastes can be stored in impoundments as air quality Federal regulations also require that im- 137 control measures. poundment dikes be designed and constructed to prevent massive failure. In the past, massive dike failure has been linked to damage caused Underground Injection Wells by leakage from the impoundment. The regula- Injection of liquid waste into subsurface rock tory criteria requires that liner leakage be con- formations is a technology that uses porous sidered in the design and construction of struc- sedimentary strata to hold liquid waste. The turally sound dikes. To the extent that new pores of all porous rock formations contain liq- dikes meet this requirement, sudden releases uids, gases, or both. The gas or liquid is con- from impoundments should be reduced. In ad- tained within the strata under pressure caused dition, new impoundments are to be designed by overlying rocks. Internal pressures within to withstand certain storm and flooding events, strata can vary significantly, depending on the However, as with landfills, siting requirements porosity of the formation, its depth, and other are minimal, Furthermore, existing sites are ex- physical and chemical factors. Essentially, empted from having to upgrade dikes and underground injection entails drilling a well berms. In some cases, exempted impound- to the depth required to intersect an appropri- ments may pose substantial risk of sudden ate geologic formation (known as the injection releases, zone) and pumping the liquid waste in with Many of the regulatory requirements pertain pressure sufficient to displace the native fluids, to closure and post-closure responsibilities. At but not so great as to cause fracturing of the closure, impoundment operators have two op- strata or excessive migration of the waste. For- tions: to remove all remaining wastes and con- mations suitable for waste injection should 138 taminated lining material for disposal at an ap- meet the following criteria: proved RCRA facility or decontaminate, or ● it should not have value as a resource— solidify/stabilize, the remaining waste so that e.g., as a source of drinking water, hydro- it can structurally support a final cover, I f this carbons, or geothermal energy; second opt ion is taken, the impoundment is ● it must have sufficient porosity and vol- essentially closed like a landfill, and similar ume to be able to accept the anticipated monitoring and maintenance responsibilities amount of liquids; apply. Long-term uncertainties related to liner ● it should be sealed both above and below life and cover integrity are similar to those dis- by formations with sufficient strength, cussed in the landfill section. Issues concern- thickness, and impermeability to prevent ing lack of criteria for what constitutes ade- migration of the waste from the disposal quate “stabilization” of the waste are similar zone; and to those discussed in landfill pretreatment re- ● it should be located in an area with little quirements. seismic activity to minimize both the risk EPA is beginning to investigate the potential of earthquake damage to the well and trig- for air quality degradation resulting from im- gering of seismic events. pounded volatile organics and is planning re- There is no standard injection-well design search to identify appropriate regulation in this because design requirements are influenced by area. Some States, notably New York and Cal- 136 ———-—— ifornia, are also investigating this issue. Cal- 1 ~ ‘st ate of ~a ] i f~rn 1 a A 1 r Resources ~ oa d, ‘‘ SUggeSted ~on- ——. — tro] Measure To Reduc;e organic Compound Emissions Associ- 1 ~’rhom~s “r, sh~n, s~n Ior Resea rc, h SC wnhst, N~w’ York st~t~ ated With ;’olati]e C)rga n 1(; t$~aste Disposal, ” August I !)82, 13CID0 n [4, W rner a n~ [)epartrnent of Enirlrtjnmental [~onservat}on, personal (;ommunl- a J ajr H. I.eh r, .5-U bsurface waS~~J$’a ter ln - (,at ion, December 1982 )ection (Berkele~,, Cafi[: Premier Press, 1981), pp. 124-127. 190 ● Technologies and Management Strategies for Hazardous Waste Control

site-specific geology. Figure 13 illustrates the injection zone; its endpoint is the point of design of an injection well that might be used waste discharge. The injection tubing is sealed for hazardous waste disposal, As shown in the off from the intermediate casing, creating an- figure, the well is constructed with three con- nular space between the injection tubing and centric casings: the exterior surface casing, the the casing, The annulus is filled with fluid con- intermediate protection casing, and the injec- taining corrosion inhibitors to protect the cas- tion tubing. The exterior surface casing is de- ing and tubing metal. The fluid is pressurized signed to protect freshwater in the aquifers between the sealing at the base of the well and through which the well passes and to protect the well head assembly .139 140 Since the pressure the well exterior from corrosion. The casing within the annulus is known, monitoring the extends below the base of aquifers containing pressure during the operation of the well can potable water and is cemented along its full be a method of checking the integrity of the in- length. Similarly, the intermediate protection jection system. Anomalous drops in pressure casing extends down and through the top of indicate a leak, either in the injection tubing the injection zone and is cemented along its or in the outer casing.141 full length. The waste is actually transported When injection operations cease, the well is through the injection tubing, the innermost cas- plugged. Proper plugging is necessary to maining. The tubing also extends into the top of the tain the existing pressure in the injection zone, to prevent mixing of fluids from different geologic strata, and to prevent flow of liquids from Figure 13.—Schematic of Typical Completion the pressurized zone to the surface.142 Method for a Deep Waste Injection Well

~~Injected waste< Applicability~~

~~I lmpervious shale Injection wells are capable of accepting a~~

Ground level wide range of waste liquids, The primary char- I y: i acteristics of a liquid that limit the applicability Cement Freshwater sand of injection well disposal are: high suspended A solids content, high viscosity, and chemical in- /l — compatibility with either the formation or for- Steel casing shutting impervious shale mation fluids. Before injecting a waste, its off all freshwater zones cemented chemical characteristics must be compared from bottom to surface with the mineral characteristics of the formation and the native fluids within the injection Cement — 143 Salt water sandstone zone to determine their compatibility. Chem- Steel casing ical pretreatment of the waste can sometimes cemented, — bottom make them more compatible with a specific in- to surface Impervious shale jection zone formation. Examples of waste that can be disposed via injection wells are:144

Corrosion resistant ● tubing dilute or concentrated acid or alkaline solutions; ● Impervious shale solutions containing metals; ● inorganic solutions; Annulus sealed - October 1982. with packer 139Waste Age, 40 JM 1 Ray “W. Amstutz, “Deep-Well Disposal: A Valuable Natural Disposal J Salt water sandstone Resource, ” in Toxic and Hazardous Waste Disposal, Robert formation — Pojasek (cd,), vol. 4, Ann Arbor Science, 1980. 1 E 141Warner and Lehr, op. cit., p. 29!i. 1 lmpervious shale 1421 bid., p, 320. 14sIbidt, pp. 159-177. SOURCE: R. B. Pojasek, Toxic and Hazardous Waste Disposal, vol. 4, Ann Arbor 144Amstutz, op. cit., p. 285. Science, 1980. Ch. 5— Technologies for Hazardous Waste Management ● 191

• hydrocarbons, including chlorinated hy- deepest formation containing, within one-quar- drocarbons; ter mile of the well bore, a drinking water • solvents; and source. Class IV wells are those used to inject • organic solutions with high biochemical hazardous liquids into or above a formation or chemical oxygen demand. which, within one-quarter mile of the well bore, contains a drinking water source. Industries using injection wells for waste disposal are listed below in approximate order of Based on preliminary validation surveys of predominance: 145 hazardous waste facility notification requirements, EPA estimates that 159 wells are cur- lndustry type Percent Chemical and allied products . . . . . 49 rently in use for disposal of hazardous industri- Petroleum refining...... 20 al liquids; this figure presumably includes both Sanitary service ...... 9 Class I and IV (see ch. 4). Earlier inventories Oil and gas extraction ...... 6 generally indicate a greater number of disposal Primary metals ...... 6 wells, Better information may become available All others . . . . 10 when all States report their intentions to develop programs under the Safe Drinking Water Current Use Act. ’47 The total rate of discharge for wells dis- Estimates of the total number of injection posing of industrial waste is large, One source wells currently in use are not in agreement. estimates that, based on volume, disposal of Some variance is due to the definition of injec- hazardous waste through injection wells was tion wells used in conducting well inventories. the predominant disposal method in 1981. An Uniform Federal definitions for classifying in- estimated 3.6 billion gallons were injected that jection wells became final in February 1982. year. 148 Information about the hazardous char- Wells are now categorized into five classes:146 acteristics of these wastes is not available. 1. Class I wells include those used for dispos- The majority of injection wells are located al of municipal or industrial waste liquids in States with a long history of oil and gas ex- and nuclear waste storage and disposal ploration. The geology in these areas is often wells that discharge below the deepest well-suited for waste disposal zones; moreover, underground source of drinking water; the geological characteristics are well docu- 2. Class II wells are those used for oil and gas mented because of petroleum exploration. For production; example, EPA Region VI contains almost 60 3. Class III wells include mining, geothermal, percent of the covered disposal wells inven- and other special process wells; toried in 1975.149 The majority of these wells 4. Class IV wells are those which inject haz- (about 58 percent) inject waste into compara- ardous waste into or above an under- tively deep stratum—e.g., at depths between ground source of drinking water; and 2,000 to 6,000 ft (600 to 1,800 m). In general, 5. Class V wells include all others (e.g., irriga- disposal into formations at greater depth are tion return flows) not in Classes I through unlikely to contaminate surface or near-surface Iv. water. About 30 percent inject waste into formations less than 2,000 ft (305 m). The receiv- Thus, wells used to dispose of federally defined hazardous liquid waste can fall into one ing formations are approximately equally distributed between sand, sandstone, and carbon- of two classifications, Class I or Class IV. The 150 ate rocks. Strata with this type of lithology distinction lies not in the characteristics of the .— waste injected, but in the discharge point rela- ‘47 Jentai Yang, Office of Drinking Water, EPA, personal com- tive to an underground source of drinking wa- munication, January 1983. 14a~art A (J n ik~~rse Telephone Verification, CO nt ra~t NO . ter. Class I wells discharge waste beneath the 68-01-6322, prepared by Westat, Inc., for EPA, November 1982, p. 3.

~~145W arner and Lehr, op. cit., p. 5. 14eWarner and Lehr, op. cit., p. 3. 14e47 FR 4992, Feb. 3, 1982. ‘so Ibid., pp. 5-7. 192 . Technologies and Management Strategies for Hazardous Waste Control~~

can be water-bearing. Whether they are consid- Class IV wells which discharge waste into or ered underground sources of drinking water above formations which, within one-quarter depends on the quality and quantity of the mile of the discharge point, are sources of water they contain and how economically ac- drinking water. The exact number and location cessible they are. All three factors vary across of these wells is not known.152 Federal policy the Nation. requiring closure of wells discharging into a drinking water source is just beginning to go Effectiveness as a Disposal Technology into effect, There is still no Federal policy for wells injecting above a drinking water source Technologies for constructing and operating (see “Technical Regulatory Issues”). wells for waste disposal is well established; much has been transferred from that used for Leakage and migration of waste to a poten- oil and gas exploration. The ability of injection tial water source can result from inadequate wells to keep waste isolated in the injection confining beds, or unexpected fracturing of a zone depends on many site-specific factors, in- confining bed (pathways 2 and 3 above). Tech- cluding the well design and expertise of the niques currently used for surveying the hydro- operator. If a failure occurs, the consequent geology of a site prior to construction minimize risk depends on the site geology, characteristics unintentional breaches of the confining beds. of the waste injected, the extent of the failure, However, if such breaches occur, they can gen- detection of the failure, and whether correc- erally be detected during the operating life of tive action is feasible and undertaken. The fol- the well by monitoring of well-fluid pressures. lowing list of potential contamination path- There are corrective actions available that can ways resulting from faulty construction, opera- potentially reduce the likelihood of contamination, and/or deterioration of the well are briefly tion resulting from these kinds of failure, but discussed below:151 they generally rely on changing the hydraulic gradient within the affected aquifer, Experi- 1. injection into or above potable aquifers, ence with these techniques is limited. Their use 2. leakage through inadequate confining is not always possible nor completely effec- beds, tive.153 3. leakage through confining beds due to unplanned hydraulic fracturing, Pathway 4 describes contamination of a pot- 4. displacement of saline water into a potable able water source with naturally occurring sa- aquifer, line water that does not meet drinking water 5. migration of injected liquids into the pot- standards. This could occur if the pressure able water zone of the same aquifer, buildup resulting from waste injection within 6. injection of hazardous liquid into a saline the receiving zone is sufficient to displace the aquifer eventually classified as a potable native fluids into a potable water source. It water source, should be possible to minimize this kind of con- 7. upward migration of waste liquid from the tamination through careful surveying and se- receiving zone along the outside of the lection of the injection zone, well casing, The quality of water contained within an 8. escape into potable aquifers due to well- aquifer can vary considerably within a single bore failure, and water-bearing stratum. It is not unusual for the 9. vertical migration and leakage through dissolved solids concentration within an aqui- abandoned or closed wells in the vicinity. fer to increase from the top to the bottom of Some existing disposal wells probably threat- an aquifer. Thus, water drawn from one loca- en contamination of drinking water sources tion may meet drinking water criteria, while through the first pathway listed. These are the 152Yang, op. cit. l~lDavid W. Mi]]er (cd.), Waste Disposal Effects on Ground l~swl]]lam Thompson, Senior Scientist, Geraghty & Miller, Inc., Water (Berkeley, Ca]if.: Premier Press, 1980), p. 366. personal communication, Novembe: 1982. Ch. 5— Technologies for Hazardous Waste Management ● 193

The contamination pathway described as pathway 9, upward migration of waste through abandoned or closed wells, is particularly in- sidious because regions where waste injection is widely practiced also have a long history of energy exploration and development. Depend- ing on the site geology, these wells provide vertical connections from deeper formations to near surface or surface formations. Many of these wells were drilled before plugging of abandoned wells was required. Often, their locations are not known and some may no longer be evident at the ground surface. One source estimates that there may be more than 1 million unplugged wells unlocated in North America. 159 To address this concern, current Federal regulations require potential disposers to calculate the subsurface area expected to be affected by the pressure of waste injection. Be- fore new waste injection can begin, the operator is required to survey and to plug existing wells within this area .160 Similarly, Federal regulations require that new wells must be plugged at closure to maintain pressure within the injection zone. There are no specific Federal requirements for well abandonment, because the procedures used depend on the well construction and site hydro- geology. Proposed plugging methods are evaluated by individual State-permitting author- ities. Wells are plugged by selectively cement- ing sections throughout its length. There is no technical concensus over the placement of well plugs; their location and extensiveness are determined by State requirements and cost considerations.l61 Some States require that plugs be set over the entire length of the injection zone, and extend 50 to 100 ft into the overlying confining beds. In some wells, injection can occur over hundreds to a thousand feet of formation. In addition, plugs are generally set above and below each aquifer that the well passes through.l62

ISQR, Allen Freeze and John A, (;herry”, []roIJ~] (~w’a tt?r ( E:II~l(’- wood Cliffs, N ,J,: Prentice Hall, Inc., 1979), p. 455. looq ~ (; ~’ ~ 1 ~ (j. 6 and 146.7. 161’’ Technical hlanua] Inje(:tion L$’ell Abandon merit,” op. (:It., p 6. l~zlbld ., pp. 5, 6. 194 ● Technologies and Management Strategies for Hazardous Waste Control

Although there is considerable documenta- pling from the receiving formation has the dis- tion of well abandonment in the oil and gas in- advantage of providing additional routes for dustry, there is less information regarding contaminant migration.168 Monitoring wells potential problems with waste disposal well can also be constructed to sample from the con- abandonment. 163 164 In 1973, the State of Michi- fining beds or from aquifers above the injec- gan surveyed 20 abandoned wells to determine tion zone. The usefulness of such wells may the adequacy of the plugs. The wells were re- be limited by site-specific factors. There are drilled to verify the position and condition of cases, however, where monitoring wells sam- the cement plugs. Some plugs were never pling immediately above a confining bed have found; others had deteriorated and were soft.165 detected contamination from leakage which More advanced well-plugging techniques was not detected by monitoring well pressures. should improve this record. Installation of ef- Also, the injection well itself can be adapted fective plugs requires careful planning and to monitor overlying aquifers.169 State require- considerable operator skill.166 There is little ex- ments for types and locations of monitoring perience with abandonment of waste disposal wells vary. wells on which to evaluate the long-term integ- Federal standards for Class I wells require rity of well plugs. that operators report “the type, number and There is currently little information about location of wells” used to monitor pressures contamination incidents resulting from injec- and migration of fluids into underground tion well practices for all classes of wells. sources of drinking water, the frequency of Moreover, it is sometimes difficult to correlate sampling, and the parameters measured (40 a particular contamination incident with a spe- CFR 146.13). These requirements are just now cific well disposal practice. Past documenta- going into effect for States with approved pro- tion of contamination has been attributed to grams. Currently, much of the direct sampling a variety of injection well operations. For ex- for contamination is conducted through water ample, one survey conducted by the State of wells that are part of the facilities water sup- Texas between the years 1967 and 1975 re- ply system or which are near an injection viewed 800 wells that had been used for oil and site. 170 gas production. The wells were located by reports of water wells becoming contaminated Technical Regulatory Issues with brackish water, of wells flowing at the All classes of injection wells are regulated by ground surface, or by field investigations.’” the Underground Injection Control (UIC) pro- Research is underway to better define the cor- gram under the Safe Drinking Water Act relation between ground and surface water (SDWA). Wells which inject liquid hazardous contamination related to injection wells. waste are regulated under both SDWA and In addition to monitoring pressures within RCRA. Because of this overlapping jurisdic- the well, there are several types of monitoring tion, injection-well facilities that are in com- wells that can provide information on the ef- pliance with a UIC permit and which meet gen- fects of waste injection. Constructing monitor- eral requirements for notification, manifesting ing wells in the receiving formation is the only of waste, annual reporting, and closure certifi- direct method of detecting the rate and direc- cation, will be considered to have a RCRA per- tion of waste liquid movement. However, sam- mit (F. R. 47, July 26, 1982, 322:81). Requirements for financial responsibility, post-closure care

103 and corrective action responsibility have not 1 bid., p. 1. Ieiwarner and Lehr, op. cit., p. 321. yet been specified. ‘f’’’ ’Technical Manual: Injection Well Abandonment, ” op. cit., p. 9. 16e Ibid., p. 8. le~warner and Lehr, op. cit., pp. 310-311. l~7Kerr S. Thornhil], Environmental Laboratories, Ada, o~a., 1@sIbid., p, 312. personal communication, January 1983. 170 Thornhill, op. cit. Ch. 5— Technologies for Hazardous Waste Management ● 195

Further, the development of UIC standards Comparative Unit Costs for is not complete, Specifically, there are no Selective Technologies standards for Class IV wells that inject wastes above a drinking water source (F. R., ibid.). There is little consistent information avail- States with approved programs are required to able about the costs necessary to achieve a eliminate waste disposal through a Class IV given level of control by waste treatment and well injecting into a drinking water source disposal practices. This is due to a variety of within 6 months of receiving approval. To date, factors: 1) lack of consensus about what con- only nine States have approved UIC programs, stitutes comparable levels of control across although several more are currently being re- technology alternatives, 2) the regulatory un- 7 viewed. 1 1 certainties of the evolving Federal program, 3) cost information that is generally specific to Corrective measures are required if a failure an application of a particular technology to a occurs during the operating life of the well. particular waste, and 4) the dynamic nature of UIC regulations require the installation and use costs as industry gains experience in respond- of continuous recording devices to monitor in- ing to the regulatory requirements. jection pressure, annular pressure, waste volume, and flow rate.172 In addition, the well Almost all the studies that evaluated costs for must be tested for mechanical integrity through different treatment and disposal alternatives a temperature or noise log test at least once considered the effect of the new RCRA regula- every 5 years. ’73 If a significant leak is detected, tions. Although tentative, given the lack of ex- the well casing must be repaired or replaced.174 perience of the interim final relations, virtu- Closure of the well must be certified. ally all the studies point out two trends: In general, waste disposal through properly 1. the post-closure, liability, and corrective constructed and operated injection wells into action requirements will have a greater ef- deep formations below the lowest drinking wa- fect on land-based disposal options relative ter source are much less likely to contaminate to treatment or incineration, and surface or shallow aquifers than are landfills 2. the costs for anv treatment option is af- and surface impoundments. There do not ap- fected by the waste type. Costs are most pear to be requirements for corrective action sensitive to waste characteristics for chem- for damage that might occur after well closure ical and thermal destruction and less sensi- comparable to the requirements imposed on tive for landfills. land-based disposal under RCRA. The Post- While cost data are scarce and only roughly Closure Liability Trust Fund Act will provide comparable in general, those that reflect differ- funding for site maintenance and care, as well ences in waste form are even fewer. For exam- as a source of compensation for personal and ple, fee schedules for commercial facilities that property damage. However, it is unclear how provide several treatment steps and final dis- the tax will be calculated for liquid waste in- posal are frequently determined after testing jected into disposal wells.’” The statutory lan- samples of the prospective waste stream, Ra- guage specifies that the tax be levied at a rate ther, most of the economic studies completed of $2.13 per dry weight ton of hazardous waste to date have focused on the incremental cost delivered to an RCRA permitted facility. increases—e.g., in administration, recordkeeping, security, personnel—required by RCRA regulations. Another very important economic ‘“’Yang, op. cit. lever that has been studied in detail is the ef- ‘“’40 CFR 146.13. fect of the liability requirements on the deci- ‘7)40 CFR 146.8 and 146.13. ] 74 Yang, op. cit. sions made by treatment and disposal facility “sEric Nagle, Environmental Law Institute, personal commu- operators, This is because the liability and in- nication, N’overnber 1982. surance requirements reflect, to a limited ex- 196 ● Technologies and Management Strategies for Hazardous Waste Control

tent, the perceived sudden and non-sudden disposal facilities because these are prices risks associated with types of waste treatment charged to return an investment on a com- or disposal, facility designs, and operating mercial service. practices. 3. The cost figures reported in the California Air Resources Board study are based on This section presents a brief comparison of surveys of commercial and onsite facility technology costs. All unit cost figures should operators. be considered as approximate. Their usefulness is in general comparison. Costs were derived Table 34 presents costs by type of waste man- from three sources; all have limitations: agement used and general description of waste type. Table 35 presents a limited comparison 1. The Commerce study figures are based on of unit costs for treatment v. incineration for treatment costs in the Great Lakes Region selected waste types, Table 36 presents a lim- only. Unit costs are based on surveys of ited comparison of landfill and thermal de- actual charges levied for wastes from three struction costs and illustrates the effect of industry sectors. The surveys requested waste form and waste type on these costs. that the respondents factor their expecta- tions of the increased costs of the interim As illustrated in table 36, the cost for com- status, not interim final, Federal require- mercial landfill service ranges from between ments. $55 to $240/tonne. This range covers the gamut 2. The EPA study, completed under contract from low-risk bulk waste to more hazardous by Booz, Allen & Hamilton, reports unit drummed waste. These designations of hazard- costs based on a survey of the nine largest ous characteristics are based largely on quali- commercial facilities. In 1980, these facil- tative assessments. By compariscln, the range ities treated an estimated 51 percent of the of costs for commercial incineration is $53 to total national waste stream which was $791/tonne. This range of costs also reflects the handled offsite, estimated at 3.7 million relative technical ease of destroying compar- tons. The unit costs reported may be slight- atively clean combustible liquids as contrasted ly overstated relative to the costs incurred with highly toxic refractory solids and drummed by a generator with onsite treatment and wastes.

~~Table 34.—Comparison of Quoted Prices for Nine Major Hazardous Waste Firms in 1981a~~

Type of Type or form $/tonne D waste management of waste Price 1981 1981 Landfill Drummed $0.64-$0.91/gal $168-$240 ($35-$50/55 gal drum) Bulk $0.19-$0.28/gal $55-$83 Land treatment All $0.02-$0.09/gal $5-24 Incineration clean Relatively clean liquids, $(0,05)c-$0.20/gal $(13) ’-$53 high-Btu value Liquids $0.20-$0.90/gal $53-$237 Solids, highly toxic liquids $1.50-$3.00/gal $395-$791 Chemical treatment Acids/alkalines $0.08-$0.35/gal $21-$92 Cyanides, heavy metals, $0.25-$3.00/gal $66-$791 highly toxic waste Resource recovery All $0.25-$1 .00/gal $66-$264 Deep well injection Oily wastewater $0.06-$0.1 5/gal $16-$40 Toxic rinse water $0.50-$1 .00/gal $132-$264 Transportation $0.15/ton mile alntewiews were conducted in May of 1980 and February of1%2 bFactor~ “~ed t. conve~ gallon5 and tons into tonnes are descr!bed in the appendix Csome cement kilns and light aggregate manufacturers are now Payi n9 for waste SOURCE Booz, Allen & Hamilton, Inc Ch. 5— Technologies for Hazardous Waste Management ● 197

Tab e 35. —Incineration v. Treatment: Range of range, e.g., generally between about $100 to Estimated Post. RCRA Charges for $400 per tonne, although specific costs can be Selected Waste Types much greater or much lower. In particular, Costs per tonne OTA found that emerging thermal destruction techniques may be less expensive than conven- Incineration— Treatment Waste oils ... . $94 $40 tional incineration techniques [see “Emerging Paint sludges . . . 453 94 Thermal Destruction Technologies”). Nonchlorinated solvents 94 61 Chlorinated solvents 206 161 Available information on waste disposal Cyanides ...... — 211 297 clearly indicates that land-based disposal is cur- NOTE Cost estimates are based on surveys of commercial treatment and InCI n erator fac I I It Ies I n the G ieat Lakes reg( ons Costs reported ref Iect the surveyed rently the predominant waste disposal method. Industries estimates of their charges based on comphance w(!h RCRA regulatory requ I rements for /r?ter/rn S(atus factl it Ies No s pec I flc I n format Ion provided abou f Landfill costs are generally less than costs for typ@ of process o, Incinerator used or charac terts IICS o f wasfe res Idl)als treatment and incineration and there continues SOURCE Off Ice of Technology Assessment from liazardo. ~s Waste Management In f he Great Lakes Region Depart mer; t of Corn merce Septern ber 1982 to be great debate about whether these lower costs include all the costs of landfilling. Some of the cost differences depend on factors such In cases where a waste can be easily detoxi- as the capital required to implement technol- fied, or energy value recovered, unit costs for ogy, whether it is being operated for commer- treatment or incineration can be lower than cial or private purposes, and personnel require- unit costs for landfilling. At the low end of the ments, These are all factors affecting the cost cost range, unit costs for particular wastes can of any technology option. be roughly comparable. It is at the high end of More specifically, the essence of the debate the spectrum where unit costs diverge greatly concerns the extent to which the still unfolding between the landfill and the incineration alter- Federal regulatory policy affects market deci- native, For example, incineration of solid or sions for selection of waste technology. The drummed waste costs in the range of about current Federal program requires that all facil- $400 to $800 per tonne as compared with about ity operators demonstrate financial assurance $170 to $240 per tonne for landfill disposal. for closure and post-closure care, and that they Midrange unit costs for land disposal of un- carry liability insurance, The estimated costs differentiated bulk waste and roughly desig- of these requirements for specific facility types nated waste hazard classes range from about are discussed in chapter 7. Note that the costs $55 to $83 per tonne. These costs are compar- to meet these requirements are expected to be able to the unit costs for various waste treat- greater for landfills and surface impoundments ment processes (table 35), which range from than for incinerator facilities. Some contend about $34 to $260 per tonne, depending on the that current Federal policy favors the land dis- waste type. Unit costs for thermal destruction posal alternative; others that the financial as- of waste fall generally at the upper middle surance requirements and the insurance re-

~~Table 36. —Unit Costs Charged for Services at Commercial Facilities~~

Landgill . $/tonne Incineration $/tonne Form. Drum $168-$240 Drummed $120-$400 Bulk : : : : : : : : : : : : $55-$83 Liquids ., . . ., $53-$400 Type Acids/alkalis ., $13-$120 Relatively clean liquids with high-Btu value $(13) a -$53 Odorous wasteb , ... 30 Liquids ... . ., $53-.$237 Low risk hazardous waste $13-$29 Solids and/or highly toxic Iiquids. $395-$791 (e g., 011 and gas drilling muds) Hazardous ., ., ., . . $30-$80 Extremely hazardous, ... , $50-$140 aHazard Cfeslgrlatlon based on Call fOrnla’s Class lflcatlon system

bsome cement kilns and Ilght aggregate manufacturers pay for these comparatively clean, high ener9Y value wastes SOURCE Off Ice of Technology Assessment, compiled from Booz, Allen & Hamilton, quoted prices from ntne major waste management firms, 1981 and from the California Alr Resources Board, Augusl 1982 198 ● Technologies and Management Strategies for Hazardous Waste Control quirements are sufficient to correct imbalances facility operator than the financial or liability between current and future costs for facility insurance requirements currently in place. operators, Demonstration of financial capability for corrective action that may be necessary It should be noted that transportation costs in the future at landfills and surface impound- to waste management facilities can be quite ments is not currently required by the Federal substantial, with long distances increasing di- regulatory program, although the issue is being rect costs by as much as 50 to 100 percent. In considered. Corrective action costs are esti- some locations, there may be no near alterna- mated to be greater than the present value cost tives to land disposal, and the added cost for of either financial assurance for post-closure transportation makes land disposal even more maintenance or liability insurance. Moreover, attractive economically. Also, the smaller the these corrective action costs are annual ex- quantity of waste handled, the greater the per penditures. Actual field data about the time re- unit treatment or disposal costs. There are, quired to mitigate contamination to an aquifer however, new commercial enterprises aimed are limited, but estimates are generally on the particularly at the small generator market, and order of many years. Thus, demonstration by various techniques can be used to reduce han- a facility operator of financial capability to mit- dling costs, including using trucks that deliver igate potential ground-water contamination chemical feedstocks to pick up carefully la- could have a greater economic effect on the beled and separated hazardous waste.

~~Ocean Disposal and Dispersal~~

Early in the 1970’s, concern was expressed agement, if there are assurances that ocean re- about the rapidly increasing quantity and vari- sources, especially fish, are protected from de- ety of material that was being disposed in struction or from being made toxic to humans. oceans. During hearings on the Marine Protec- Certain types of wastes may be better suited tion, Research and Sanctuaries Act of 1972 for ocean disposal than others. For the most (MPRA) testimony before Congress empha- part, however, current scientific information sized the fragile nature of the marine environ- will not resolve uncertainties. ment and our lack of knowledge about effects of ocean waste disposal on human health and Current Usage ocean organisms. With passage of MPRA, the ocean was given the status of a “last resert” After passage of MPRA, control over ocean disposal option, to be considered only after disposal became apparent by decreases in the other alternatives had been exhausted. volume (5 million tons in 1973 to 3 million in 1980) and decreases in approved disposal per- Ten years later, controversy about the appro- mits (332 in 1973 to 26 in 1.980). Currently, priate level of ocean protection and use contin- ocean disposal in the United States involves the ues. A new understanding of potential environ- following types of material: mental risk resulting from land disposal practices has led some to reconsider the ocean as 1. The disposal of material produced by a disposal medium. Interest in using oceans for dredging activities necessary to keep the 176 hazardous waste management has increased Nation’s ports and harbors operating. as the volume of waste, land disposal costs, and Under regulations established by the U.S. opposition to land disposal sites have in- Army Corps of Engineers, dredge spoils creased. Even some dedicated proponents of *7’ Lee Martine, “Ocean Dumping A Time to Reappraise?” ocean protection acknowledge that the ocean Issue Brief No. Ib81088, prepared for the Library of Congress, has a role, albeit limited, in waste disposal man- Congressional Research Service, 1982. Ch. 5— Technologies for Hazardous Waste Management ● 199

are transported by ship or barge to sites ocean disposal permits that existed in approved by EPA. These materials ac- 1973, only 13 remained in April 1979.179 count for an estimated 80 to 90 percent of Acids can be considered as suitable waste all U.S. waste deposited in the ocean and for ocean disposal since they can be neu- for the most part would not be considered tralized through the large buffering capac- hazardous under the RCRA definition. In ity in the marine environment. The mode 1981, it was estimated that only 5 percent of discharge, from a barge or vessel, is de- of this type of material would be consid- signed to maximize the initial dispersion ered hazardous using bioassay techniques.177 and dilution in seawater; there is usually 2. Sewage sludge produced by municipal little density difference between the waste secondary treatment plants. In New York plume and the surrounding surface water and New Jersey, sludge waste is trans- after the initial few seconds. Acid wastes ported daily by ship or barge to an EPA- are almost immediately neutralized by sea- approved site in the New York Bight. The water. volume of waste disposed in the Atlantic 5. Marine incineration of toxic waste aboard Ocean has increased. These wastes could specially designed vessels. This is not contain variable quantities of toxic constit- really ocean disposal, but rather thermal uents and pathogens that would pose haz- destruction of organic material at sea. ards to the marine environment and public Within the United States, experience has health. been limited primarily to experimental 3 The discharge of municipal waste and “burns” involving organic chloride waste, l80 some industrial waste through pipelines Agent Orange, and, most recently, PCBS. to ocean outfalls. This activity is regulated Constraints on this method are discussed by EPA under the Federal Water Pollution in the previous section on thermal destruc- Control Act of 1972 (FWPCA). Waste dis- tion. posal through ocean outfalls is a practice used in Boston, on the west coast, in Legislative Background Hawaii, and in Alaska. Along the southern California coast, for example, 30 outfalls The belief that ocean dumping was threaten- discharge an estimated 4.5 billion liters of ing both the value of the marine environment sewage and sewage sludge daily. ]76 As of and human health led to national and interna- January 1981, there were 232 land-based tional measures to limit, if not prevent, the con- dischargers whose outfalls entered the ter- tinued use of the ocean for disposal of waste. ritorial sea and beyond; 74 of these were Such measures included: from industrial sources. This material can 1. MPRA; pose hazards. 2. the Convention of the Prevention of 4, The disposal of acids. This activity occurs Marine Pollution by Dumping of Wastes at three EPA-approved sites off the east and Other Matter, known as the London coast and Puerto Rico. Due largely to ef- Dumping Convention, ratified by the forts to recycle acids, the volume of this United States in 1974; and industrial waste decreased by 49 percent 3. FWPC, which regulates waste discharges between 1973 and 1979. Of 150 industrial within territorial seas.

179 P W, Anderson and R. T. Dewling, “Industrial Ocean Dump- “’National Advisory Committee on Oceans and Atmosphere, ing in EPA Region II—Regulatory Aspects, ” in Ocean Dumping “The Role of the Ocean in a Waste Management Strategy, ” A of]ndustrial Wastes, B. H. Ketchum, D. R. Kester, and P, K. Park Special Report to the President and Congress (Washington, D. C.: (eds.) (New York: Plenum Press, 1981). U.S. Government Printing office, 1981). 100K, S, Kam]et, “ocean Disposal of organoch]orine WaSteS ‘“A. J, Mearns, “Ecological Effects of Ocean Sewage Outfalls: hy At-Sea Incineration, “ in &ean Dumping of Industrial Wastes, Observations and Lessons,” OCEANUS, vol. 24, No. 1, 1981, pp. B. H. Ketchum, D. R. Kester, and P. K. Park (eds.) (New York: 44-54. Plenum Press, 1981). 200 ● Technologies and Management Strategies for Hazardous Waste Contro!

The EPA has responsibility to regulate ocean In 1977, congressional concern centered on disposal so as: the progress being made in phasing out the dumping of sewage sludge in the ocean. Thus, . . . to prevent or strictly limit the dumping amendments adopted that year gave legislative into ocean waters of any materials which would adversely affect human health, welfare, force to EPA’s regulatory effort to impose an or amenities, or the marine environment, eco- absolute ban on all ocean disposal of sewage logical systems, or economic potentialities sludge after December 31, 1981. The regula- [Public Law 92-532). tions implementing this ban were challenged, however, by New York City, which sought an The disposal of certain specific wastes (includ- extension of its interim permit to dispose of ing nuclear materials and most biological and sludge in the New York Bight. The U.S. District chemical warfare agents) is prohibited, and Court for the Southern District of New York ocean disposal of other types of waste may be ruled in favor of New York City. The Court re- considered only after all alternatives have been quired EPA to give New York City an oppor- exhausted. Although the Army Corps of Engi- tunity to present evidence indicating that dis- neers has the responsibility for disposal of posal of its waste in the New York Bight had dredge spoils, EPA was given the authority to “relatively inconsequential effects” and that approve all disposal sites, including ocean, land disposal of this material might prove far land, and wetlands.l8l more harmful to the environment and human EPA is directed to establish criteria for re- health.182 EPA was required to consider “all view of ocean-disposal permit applications. In statutory factors relevant to a reasoned deter- establishing or reviewing these criteria, the mination, ” including the costs and dangers of EPA Administrator is required to consider at land-based disposal. EPA did not appeal the least nine factors specified in MPRA, six are decision and is now in the process of develop- related to the effects on human health and the ing new regulations to replace those that were environment, two relate to the availability and invalidated by the Court, effects of alternative methods of disposal, and one designates appropriate ocean sites. Controversy Over Ocean Use for Hazardous Wastes The system established by EPA provides four classes of ocean disposal permits: Arguments in Favor of Increased Ocean Disposal Experience and research data obtained over 1. general permits for the disposal of relative- the past 10 years and still being accumulated ly innocuous waste; contribute to the debate regarding appropriate 2. special permits for waste that would not use of oceans in waste management. Argu- “unreasonably degrade” the marine envi- ments in favor of greater use conclude that the ronment, as determined by the types and marine environment has the capacity to assimi- concentrations of constituents present; late hazardous constituents. The assimilative 3. interim permits, generally conditioned on capacity may be defined as the amount of a an agreement to phase out the particular particular material that can be contained dumping activity; and within a body of seawater without producing 4. emergency and research permits. an unacceptable impact on living organisms Only when reviewing interim permit requests or nonliving resources. will EPA take into account the need for dis- A recent scientific assessment supporting posal of a specific waste and the limitation of this conclusion was reported by the Regional land-based alternatives. Seas Program of the United Nations Environ- mental Program.l83 The results of the 4-year ‘*z Ibid. Ialwl]]lam L, Lahey, “ocean Dumping of Sewage Sludge: The lmWebster Bayard, “World’s Oceans Became Cleaner Over the Tide Turns from Protection to Management, ” Harvard Environ- Last Decade, Study Shows,” The New York Times, Nov. 7, 1982, mental Law Review, VO]. 6, No. 2, 1982, pp. 395431. p. 26. Ch. 5— Technologies for Hazardous Waste Management • 201 study suggest that oceans are able to assimilate tern conditions (e.g., oxygen depletion), and ac- toxic substances in most areas without extreme cumulation of persistent chemicals in marine disturbance of the ecosystem. In addition, a sediment. In contrast, a site 106 miles offshore number of scientists report that the ocean has from New York City does have dispersion a self-cleansing ability that would enable it to capabilities. Disposal of sewage sludge at this absorb waste without unacceptable conse- site might enable natural biological and chemi- quences. 184 cal processes to incorporate sludge without detrimental effects. There is evidence that, in some instances, the marine environment can recover within a few These somewhat positive experiences with years from pollution previously perceived as the disposition of constituent fate and their ef- heavy. 185 186 Studies of the outfalls in coastal fects have bolstered the cause for greater use areas suggest that short-term effects of sewage of the ocean in waste management. However, on marine plant and animal communities do these experiences, for the most part, have lit- occur, However, over the long-term these com- tle relevance to most hazardous waste. Some munities appear to have the ability to recover. scientists argue that effective plans can be For example, when discharge was initiated at developed for disposal of highly toxic sub- the Orange County outfall in 1972 (at a depth stances without endangering public health.l89 of 60 m], it took a full year for fish and benthic It is argued that information on marine pollu- infaunal communities to show adverse effects. tion gained during the past 30 years provides Conversely, after cessation of 15 years of con- a basis for developing models that can be used tinuous discharge at another site (a depth of to determine the assimilative capacity of coast- 20 m): al waters. Supporters contend that, as more information accumulates about life processes in ... the infauna changed from deposit-feeding- the ocean, it should be possible to identify dominated communities to the normal, suspension-feeding-dominated communities pollution problems and formulate remedial ac- within three to six months. Copper concentrations. tions in sediments returned to background within a year; trawl catches of bottom fish also Arguments Against Increased Ocean Disposal decreased, relative to background, within one 187 While few would maintain that oceans should to two years of discharge termination. be completely excluded from waste disposal, similar recovery was evident at the sewage there are arguments against increased use of sludge site previously used by the City of Phila- the marine environment in waste management. 188 delphia. Two years after disposal was ter- The ocean’s status as a global commons minated: makes it more vulnerable to misuse. The “not . . . bacteria and virus levels had declined suffi- in my backyard” attitude that works to block ciently for the Food and Drug Administration siting of land-based waste facilities does not ex- to lift restrictions on shellfishing. ist for the ocean, Economics also emphasize this vulnerability. While prodisposal forces cite Such responses, however, depend on the the growing differential between land and physical, biological, and chemical characteris- ocean disposal, it is pointed out that there is tics of the sites, For example, sites in the New virtually no cost for an ocean site itself; thus York Bight have poor dispersion capability, that option will always be cheaper than land- high susceptibility to deterioration of ecosys- based alternatives. — ‘lwI,ahey, op. cit. The suggestion that managers now have ade- 1n5Mea r ns, op. cit. quate data and reliable models to predict and 1~W. Bascom, “The Effects of Waste Disposal on the Coastal Waters of Southern California, ” Environ. Sci. & Techn., vol. 16, understand the effects of dumping in the ocean No. 4, 1982, pp. 226A-236A, —— ‘“’ Mearns, op. cit. 16UE. D. Goldberg, “The Oceans as Waste Space: The Argu- ‘ Oa!.a hey, op. cit. merit, ” OCEANUS, vol. 24, No. 1, 1981, pp. 2-9. 202 ● Technologies and Management Strategies for Hazardous Waste Control

also is disputed. The argument that current There is a belief that the assimilative capacity data show that impacts of disposal are less than concept is already failing.192 Assessments of anticipated 10 years ago is criticized on the single-constituent effects will not provide suffi- basis that research efforts have not been sufficient information; there are hazardous constit- ciently sophisticated to provide sound evi- uents existing in various forms being released dence. in combination at different locations. A solution suggested by critics would be to develop The usefulness of existing models for assimi- closed systems that would eliminate any relative capacity is also questioned. Such models lease of hazardous compounds from any dis- attempt to describe the ocean’s ability to posal medium to the environnment. With this achieve acceptable levels of concentration and approach: distribution of hazardous substances. A number of weaknesses have been noted:190 ,.. the costs of managing, including recovering or storing or detoxifying wastes, are appro- 1, the lack of empirical data, limiting efforts priately assigned to the products of the indus- to estimate appropriate concentrations of try, not diffused as a general cost onto the pub- hazardous contaminants; lic at large.le3 2. the lack of information on long-term fate Proponents of continued strict limits on of constituents and effects on the marine ocean disposal do not suggest that the oceans environment; should be inviolate. The value of multimedia 3. only single constituents are considered, ig- management is recognized, but initial compari- noring any synergistic effects and thus, sons of the environmental merits of the various possibly underestimating damage to the options are necessary. Once the medium of environment; and choice is determined, other relevant factors, in- 4. uncertainties about the relationship be- cluding economics and technological feasibil- tween amounts of waste deposited and the ity, should be considered. There is clearly more environmental response; unanticipated de- support for using the oceans for the less haz- layed responses can result in serious un- ardous, biodegradable (and less controversial) derestimation of environmental impacts. waste than for substances such as PCBS, It has been suggested that the assimilative Effective management of ocean-disposal ac- capacity concept is useful as an organizing 191 tivities should be preceded by a thorough un- principle. If it is used to focus research and derstanding of the fundamental biological, monitoring on relevant questions, the concept chemical, and physical processes in the marine is beneficial. It can also be valuable in defin- environment. While such understanding has ing the lower limits of accepted environmental improved significantly during the past 10 concentrations in the marine environment. years, particularly for deep-ocean waters, lit- Critics argue, however, that assimilative tle or nothing is known about the long-term fate model assessments cannot, now or at any of these wastes “or the capacity of these pelagic time soon, serve as a sufficient basis for pre- oceanic regions to assimilate wastes without dicting the hazard potential of persistent sub- 194 detrimental effects. “ particularly, there is a stances in the marine environment. A particularly important criticism is that such model- ing may not reveal delayed concentrations of IWG. M. Woodwell, “Waste Disposal: Time for a New Ap- preach, ” adapted from remarks made before joint meetings of toxic substances in surprising places and the American Geophysical Society and the American Society ways. for Limnology and Oceanography, San Antonio, Tex., Feb. 17, 1982. ~O~Ibid. IWLahey, op. cit. 194D. R, Kester, B. H , Ketchum, and p’. K park [eds, ), “~uture 191K. S, Kamlet, “The Oceans as Waste Space: The Rebuttal, ” Prospects of Ocean Dumping?” in tiean Dumping of lndustria) OCEANUS, VO]. 24, No. 1, 1981, pp. 10-17. Wastes (New York: Plenum Press, 1981), pp. 505-517. Ch. 5— Technologies for Hazardous Waste Management ● 203 need to improve the assessment of the biologi- assessing biological effects of contami- cal effects of pollutants in the marine environ- nants on fish, crustaceans, polychaetes, ment. Current information, therefore, shifts and mollusks. the burden to potential users of the ocean to 3. Biochemical measurements, such as repro- document and defend such use. ductive biochemistry, hormone metabo- lism, and blood-chemical analyses. Future Research and Data Needs 4. Ecological assessments—the most direct and comprehensive approach to determin- This reassessment of the ocean’s potential for ing effects of constituent, but difficult to waste disposal comes at a time when there are implement. growing limitations on and increasing problems with land-based methods. More recent Several programs are available for obtaining legislation than MPRA–i.e., SWDA and RCRA these types of data and include EPA’s dis- —have imposed new and stringent regulation charge permit program (characterized as a on land-based disposal of waste. Well-publi- load-assessment approach), the baseline studies cized incidents such as the Love Canal have program of the Bureau of Land Management caused public acceptance of landfills and other (trend-assessment approach to identifying im- waste disposal facilities near residential areas pacts], and the National Marine Fisheries Serv- to plummet. It is recognized that the high prob- ice strategy to assess the “health” of fisheries ability that land-disposal activities might de- resources on the basis of periodic environmen- cline during the 1980’s, may increase interests tal measurements of selected parameters. l95 in ocean-waste disposal . A Federal program Past experience in “crisis response” may pro- is needed that would emphasize research and vide useful information for considering ocean monitoring before allowing disposal of the disposal of hazardous waste.l96 Identification most hazardous waste in various oceanic envi- of common factors in environmental crises ronments. concerning mercury poisoning and contamina- Because of the high value placed on marine tion by DDT, PCB, and Kepone, if recognized biota as a resource, “the biological conse- and considered in future monitoring strategies, quences of ocean dumping are generally re- could lead to earlier warning of adverse im- garded as establishing the acceptable limits of pacts from ocean disposal. In each of these ex- waste disposal in the marine environ merit.” amples, there was a lack of understanding of Thus, determining what biological parameters the movement of the contaminant in the ma- should be measured is seen as a major sc ientif- rine environment and of sensitive organisms ic problem. The International Council for the or critical factors leading to the observed im- Exploration of the Seas identified four classes pact. Thus, future monitoring should be de- of data needs: signed to consider fate of constituents and to identify the sensitive points in the ecosystem 1. Bioassay measurements, ranging from defor each constituent of concern. termination of lethal concentrations for Certain types of waste maybe better suited particular organisms to changes in growth 97 rates brought about by various concentra- for ocean disposal than others. * Water and tions of a waste. Where possible, more ex- air are dispersal media, whereas land is a tensive tests should address synergistic ef- containment medium. Waste management fects of multiple contaminants. should consider whether a persistent toxic 2. Physiological techniques for measurement material is best disposed in a dispersal or a of growth, scope for growth, and feeding containment medium. For persistent synthetic rates—considered the best techniques for ‘W Kester, op. cit. — ‘“K. S. Kamlet, “Cons!ramts on the Ocean Uurnping of Hazard- 1Q5 Nat 10 Ila ] A~\. i SC) rY, (Jorn rn ltte~ o n Oceans and Atmosphere, ous Wastes, ” prepared for presentation at the Northeast Confer- 1981, 0~ Cit. ence on Hazardous Waste, Ocean Citj, NJ,, 1982. 204 . Technologies and Management Strategies for Hazardous Waste Control

chemicals, such as PCBS, Kepone, and DDT, are made which may tie us into a long-term isolation and containment or destruction to the commitment, it would be best to: fullest extent possible may be preferred to 1. test predictions against field experiments; 2. ocean disposal. For persistent, naturally occur- develop a waste management plan for coastal areas which considers effects of ring materials, such as heavy metals and petro- all pollutant sources; leum hydrocarbons, a reasonable argument 3. design delivery systems which will mini- might be that dispersal is sensible. However, mize environmental degradation; large or continuous additions of even such ma- 4. continue to work on developing pretreat- terials can produce harmful departures from ment techniques that will ‘per-m-it waste background levels, particularly on a localized material to be considered as a resource basis. For certain amounts of nontoxic or bio- rather than a waste.199 degradable materials, the assimilative capac- Scientists must determine what additional in- ity of specific ocean locations may be ade- formation is needed to evaluate oceanic dis- quate. Acids, alkalis, and nutrients are exam- charge under the condition that oceanic re- ples. A management philosophy aimed at sources must be maintained in renewable maximizing dispersal of such materials, states and threats (even if long term) to human while avoiding disruption of local ecological health are minimized. What are the long-term systems, might be most sensible. effects of the very low levels of constituents in the sea? What are the synergistic and antago- When considering possibly acceptable nistic effects of collectives of constituents? ocean-disposal activities, it is also necessary While both general and specific stress indica- to consider the various advantages and disad- tors are available, such as those for metals and vantages of different sites. For example, shal- petroleum components, there remains a need low, continental-shelf waters offer the advan- to identify specific indices applicable to indi- tages of being better understood, based on ex- vidual or classes of constituents. Work should perience and scientific research, requiring low- be done to compare alternate ocean-disposal to-moderate transportation costs, and a locali- l98 strategies, such as dispersing waste above or zation of potential detrimental effects. On the 200 beneath the thermocline. Federal actions that negative side, the resource value of these areas should precede any widespread movement to is typically greater. There also is a tendency use oceans for hazardous waste management for substances to accumulate in bottom-living 20l include: organisms and sediments in these locations. Deep-ocean waters, on the other hand, offer the 1. assessing the state of pollution in U.S. advantage of broader dispersion and dilution coastal and deep-ocean waters; of waste and reduced conflicts with other 2. precisely defining present standards and marine resources. Disadvantages include un- criteria in terms of specific constituents certainties about the ultimate fate and effect and regional bodies of water; of waste, with potential large-scale impacts, 3. developing an information system to rou- and a likely greater effect on planktonic and tinely report what has been learned; bottom-living organisms. 4. coordinating all research to achieve the maximum results from limited research Technical Regulatory Issues funds; 5. implementing a cost-effective network of It is recognized that a number of important coastal water-quality monitoring; issues should be resolved before proceeding 6. simplifying regulatory procedures; and with widespread or indiscriminate use of the 7. continuously evaluating and reevaluating oceans for hazardous waste management. water-quality standards. Thus, a current study recommends that: ‘WR. L. Swanson and M. Devine, “The Pendulum Swings Again: Ocean Dumping Policy,” Environment vol. 24, June 1982, Before it is too late and major investments pp. 14-20. 2WKester, op. cit. 201J. P. Walsh, “U.S. Policy on Marine Pollution: Changes 1e*Kester, op. cit. Ahead,” OCEAIVLR5, vol. 24, No. 1, 1981, pp. 18-24. Ch. 5— Technologies for Hazardous Waste Management ● 205

~~Uncontrolled Sites~~

This section discusses methods for the iden- Uncontrolled sites fall into three categories: tification, evaluation, comparison, and remedi- 1. Operational uncontrolled sites are those ition of uncontrolled sites. A number of policy hazardous waste sites requiring, but not ssues associated with the CERCLA legislation currently receiving, attention to ameliorate and its implementation by EPA and the States dangerous conditions. Either ongoing re- are discussed in chapters 6 and 7. The objec- leases to the environment or the threat of ive of this section is to consider several tech- imminent releases of hazardous waste lical areas related to cleaning up uncontrolled would constitute such conditions, iites, including the problems of identifying 2. Inactive sites are those sites no longer re- iites, developing plans for cleanup, and select- ceiving hazardous waste and for which ng remediation technologies, * there is an identifiable responsible party The magnitude of the uncontrolled site prob- or owner. em is generally recognized to be substantial. 3. Abandoned sites are uncontrolled hazard- Although the precise number has not been ous waste sites where no responsible party determined, there are probably some 15,000 un- or owner has been identified, or where controlled sites in the Nation requiring remedi- such parties lack the resources to take the ation. Costs of remediation vary greatly but will steps needed to remedy danger conditions probably average several million dollars per at the site. ite, * * The total national cost of cleaning up uncontrolled sites is probably in the range of Issues Concerning Effectiveness $1O billion to $40 billion, far more than the cur- ent $1.6 billion estimated to be collected under The national effort to clean up uncontrolled IERCLA by 1985, A recent congressional anal- sites is in its early stages. The magnitude of the sis revealed that, through FY 1982, only $88 problem, in terms of potential harm to human million of $452 million collected under CERCLA health and the environment and of potential ad been expended for cleanup, no cleanup costs of cleanup, is such that it is imperative unds had been earmarked or expended on 97 to give considerable attention to three major f the initial 160 priority sites determined by issues, which are discussed below: JPA, and only 3 CERCLA sites had been totally 202 1. What basis should be used to determine leaned up (1 entirely with State funds). the end point for a remedial action? This is

● For the purposes of this discussion, emergency response and sometimes asked as the question “How clean mmediate ” removal are not considered as remediation of a is clean?” te. They are conventional actions associated with accidents ld spills to remove immediate threats, generally followed by This question of extent of cleanup is often ore technology-intensive and systematic efforts. Also, those addressed by defining some nonharmful, or ac- :tivlties defined within EPA’s National Contingency Plan as nitial remedial” will not be considered as distinct, technolog- ceptable, level of contamination that may be ally, from remedial control technologies. Differences between left at a site after remedial actions are termi- ese technologies concern timeframes, funding sources, and nated. This approach, however, can be difficult gulatory approaches rather than substantial technical dif- rences. to apply since the toxicological effects of many ● *For example, the cleanup of one of the ]nltial 160 priority wastes and of low levels of some wastes are tes, the Seymour site in Indiana, is estimated by EPA to cost unknown. This could lead to somewhat arbi- 2.7 million to remove 60,000 barrels of wastes and to clean I contaminated soil and ground water beneath the site. An ex- trary choices of acceptable residual chemical nple of a less costly remedial action is the Trammel Crow site contamination. Texas where five sludge pits with over 5 million gal of waste ;re cleaned up onsite using a solidification process and cost Extent of cleanup can also be considered 78,000. In both cases additional moneys were spent for ini- from the perspective of protection of the public 11 studies of the sites.

zozstudy by the House Subcommittee on Commerce, Transpor- and the environment in a cost-effective way. !Ion, and Tourism, as reported in Hazardous Waste Report, This may be accomplished by various ap- IV. 1, 1982, proaches, such as: 206 Ž Technologies and Management Strategies for Hazardous Waste Control —

● An alternate water supply might be pro- ● the degree of success of the various tech- vided for a community using contami- nology options is sometimes site-specific. nated ground water, rather than cleaning Therefore, the comparison of alternate the original supply. Such an approach technologies for a specific site remediation might be appropriate for small numbers of cannot always be extrapolated into a valid water users, particularly when there might generic comparison; be a natural reduction of the contamina- ● the long timespans involved in some of the tion in time (e. g., with biodegradable or- technologies require assumptions regard- ganic waste). Sometimes outright pur- ing their long-term effectiveness. Some of chases of the affected homes might be the the technology options generate future most efficient way to accomplish the goal operation, maintenance, and monitoring of limiting human exposure. costs that are difficult to estimate; and ● Parties responsible for a number of sites ● the possibility of systems failure and the might propose a partial cleanup, less than need for subsequent remediation are diffi might be necessary to eliminate all poten- cult to predict. Only crude estimates of tial future risk. Thus, buried drums and the these potential “second-round costs” are most contaminated soil might be removed, available for comparison. without extensive ground-water recovery 3. Which current technologies may create and treatment. Long-term environmental future problems? Some technological choices monitoring then would be provided to as- could create needs for future remediation, for sure that there is no release in excess of extended operation and maintenance proce predefine action levels. dures, with continuing risks and costs. 2. How can the relative cost-effectiveness The choice of a technology for site remedia of alternative cleanup approaches be deter- tion can result in the need for certain long-tern mined? commitments. Such requirements might in There are many difficulties in trying to ana- elude physical maintenance of the grounds anc lyze the economics and cost effectiveness of site security if residuals of hazardous waste o: various remediation options. There is no ques- other potential hazards remain after site reme tion, however, that the costs of remediating un- diation. Further, certain technologies, by vir controlled waste sites are high. For example, tue of the time needed for implementation (i.e. the initial phases of site identification, evalua- ground water recovery and treatment), involve tion, and assessment may cost from $50,000 to long-term operation and maintenance costs several hundred thousand dollars. The prelimi- Also, there is a continuing level of risk during nary engineering efforts taken before remedia- the implementation of these long-term technol tion may cost several hundred thousand dollars ogies. These deferred costs, as well as the possi more, and actual remediation generally costs ble costs for alternate remedial technology i from several hundred thousand dollars to sev- the initial control technology fails, should be eral million dollars per site. There has not been considered when making a choice between an enough accumulated experience to quantify initially more expensive remediation (e.g., ex and compare how effectively different technol- cavation with offsite disposal or treatment) and ogies reduce risks. Some of the factors that af- a long-term technology with lower initial cos fect analyses of cost effectiveness include: (e.g., encapsulation). ● public policy regarding the level of accept- Taking remedial actions that are effective in able risk subsequent to a site remediation the long term is advisable because new uncon remains unclear; trolled sites are likely to be identified, requix ● the operating history of cleanup technol- ing still further expenditures in the future. Cur ogies at uncontrolled sites has not been rent practices of land disposal of hazardou sufficiently documented; waste may be creating future needs for reined Ch. 5– Technologies for Hazardous Waste Management ● 207

al action. Disposal sites, even state-of-the-art forms, and compositions; and evidence of ac- installations meeting regulatory standards for tual releases, Table 37 summarizes the types design, operation, closure, and post-closure of data required. Nontechnical descriptive in- monitoring, do not always eliminate the possi- formation might be collected concerning his- bility of releases of hazardous materials into tory of the site, ownership, adjacent properties, the environment, Moreover, because of a num- previous administrative or legal actions, associ- ber of exemptions in RCRA itself and of those ated potentially responsible parties such as gen- resulting from administrative decisions, haz- erators and waste haulers, and other relevant ardous wastes are being disposed in subtitle D background information. These nontechnical sanitary landfills that are not designed for haz- types of information are important for obtain- ardous waste. Such facilities have already ac- ing more detailed technical information, as counted for large numbers of uncontrolled sites, and others will likely become uncon- Table 37.— Data Required To Identify and trolled sites. Evaluate Uncontrolled Sites

Type of data—spectfic factors Site Identification and Evaluation Site assessmenf: Wastes: The amount of information available regard- ● Quantity ing uncontrolled sites (e. g., location, number, ● Corn position ● Form and level of hazard) is generally recognized to . Condition of waste (containerized, bulk, burled, open be incomplete, There are continuing efforts at lagoon) both the Federal and State levels to identify un- ● Acute hazards (acute toxicity, flammability, controlled sites, with the problem being acute explosiveness, etc. ) ● Chronic cumuIative hazard (toxicity, mutagenicity, for abandoned sites for which there are no re- carclnogenicity, teratogenicity, radioactivity, etc. ) sponsible parties available to provide detailed ● Synergistic/antagonistic components information (see ch. 7). It is generally accepted Site: ● Geological features that many thousands of uncontrolled sites • Topographical features exist. ● Vegetation ● Surface water There are three means of identifying uncon- ● Ground water trolled sites: . Structures ● Access 1. Federal and State efforts to prepare inven- Exposure: Releases tories of sites based on file information or Ž Past or present releases on field investigations; • Potential for future releases 2. reporting by the general public and by par- • Migration routes of releases (air, ground water, stir- face water, overland flow or runoff, etc.) ties such as developers that may discover Potential exposure: sites accidentally; and Ž Estimates of release quantities 3. requirements that industries producing or Ž Exposure routes managing hazardous wastes submit infor- Risk: mation on sites either created by them or Environments: ● Waters known to them. • Land areas ● Air Following the identification of a problem ● Vegetation site, considerable data is required for evalua- ● WiIdlife ● Agricultural areas tion of the level of hazard posed by the site. ● Recreational areas Relevant data include both physical and de- Populations: scriptive factors. Physical considerations in- • Location ● Sensitivity clude the population or environment at risk; • Numbers critical pathways; site conditions, including hydrogeologic characteristics; waste amounts, SOURCE Office of Technology Assessment 208 ● Technologies and Management Strategies for Hazardous Waste Control well as for other purposes, such as enforcement quality control in both government and pri- actions. This is necessary because site inspec- vate laboratories. tions are difficult, costly, and sometimes dan- Techniques for the comparison of sites often gerous, and because there often is no immedi- involve the combination of various “weighted” ate source of technical information. components of hazard into a single numerical A site inspection to observe surface condi- measure for a site. Such values for various sites tions may include: are compared in order to produce a ranked listing, from which remedial priorities are then sampling of wastes, and surface and established. (see chs. 6 and 7 for discussions ground waters, of hazard evaluations, risk assessment, and air monitoring, ranking systems), some random excavation to identify buried materials, Site Cleanup Plans magnetic surveys to locate buried metal (possible containerized material), Once a decision is made to proceed with re- resistivity surveys (to determine whether medial action at a site, it becomes necessary there is underground contamination), and to establish a step-by-step procedure for imple- an assessment of site conditions in general. mentation. The basic steps in remedial action or site cleanup are: Determining what a site contains can present substantial problems of sampling and analysis. 1. preliminary assessment, Only a limited number of samples can be taken 2. feasibility study, because sampling itself can pose risks of re- 3. engineering design, lease of hazardous materials from the site. With 4. construction, hundreds or thousands of drums that are often 5. startup, trouble shooting, and cleanup, and unmarked, and a relatively small number of 6. possible long-term operation and mainte- samples taken, there is no assurance that anal- nance. ysis will accurately indicate the hazardous con- Following assessment and the decision to ef- tents of the site, or that any hazardous materi- fect remediation, the feasibility study would als will be discovered. There are also substan- identify alternative engineering options for mit- tial problems concerning the detection of haz- igation, including limitations, costs, and effec- ardous materials in underground water sup- tiveness. The feasibility study should evaluate plies. There is no consensus on drilling meth- the various remedial technologies for the spe- ods, sampling frequency or protocol, standard cific conditions at the site under consideration. quality assurance procedures, or the number The basic technological options are: of wells needed to define problems, Drillers run the risk of contaminating clean aquifers while 1. removal followed by appropriate disposal drilling into polluted ones. or treatment—e.g., fixation, neutralization, or any other conventional technology, or There are also considerable problems con- by treatment of the waste on the uncon- cerning chemical analysis. Standard methods trolled site (see discussion earlier in this such as mass spectroscopy do not necessarily chapter); yield useful results for many chemicals. Newer, 2. pathway control through encapsulation or sophisticated laboratory procedures may re- containment, or by ground or surface wa- quire laboratory facilities not available to inves- ter diversion; tigators. There are few standard testing proce- 3. mitigation of exposures by providing an dures for complex waste constituents. Waste alternate water supply, land use restric- may contain byproduct chemicals, or altered tions, or evacuation of people; chemicals, and laboratories may not have standards for their identification. There are in- An important issue concerning the choice of dications of substantial problems concerning remedial technologies, because of current EPA Ch. 5— Technologies for Hazardous Waste Management ● 209 policies (see ch. 7), is the difference in initial, ogies are discussed below, and a summary of capital costs v. longer term operating and the advantages and disadvantages of primary maintenance (O&M) costs. The specifics of technological options is given in table 38. A re- O&M depend on the technology chosen. Those cent survey of technologies used at uncon- technological options that permanently deal trolled hazardous waste sites indicates the dis- with the hazard often have high initial costs tribution of currently used technologies, as and low O&M costs. Conversely, those options shown in table 39. These technologies may be that, for example, do not destroy or treat the grouped into two broad categories: waste to reduce risks are likely to have high . waste control technologies; and and uncertain O&M costs. For example, exca- . environmental pathway control. vation and removal followed by treatment or disposal would initially be both capital-inten- Waste control technologies for uncontrolled sive and labor-intensive, but subsequent O&M sites act on the amount of waste or on some requirements would be minimal. Alternatively, hazardous property or constituent of the waste. encapsulation with ground water recovery and Such methods include: treatment would generally incur lower initial Excavation and removal offsite of the costs but have subsequent large O&M costs. hazardous waste.–This method is suitable Implementation of engineered remedial ac- for all sites with containerized or bulk dis- tivities at a site may require a wide variety of posal of waste. Normally it must be fol- ancilliary and support activities, depending on lowed with some type of secondary clean- the conditions at the specific site and the up of ground water if the materials depos- choice of control technology. Epidemiological ited were water soluble, and evidence studies may be required when there has been shows ground water contamination. While a release of hazardous waste that may have af- such techniques eliminate or minimize fected public health or if there is a need for both future O&M costs and future risk to baseline data to monitor future effects arising the public and environment, there are high from the choice of site-control technology. initial costs, with possible higher risk of Chemical analysis may also be needed for exposure during the period of excavation. many purposes, ranging from quality control To some degree, risk may be relocated work during cleanup, protection of onsite depending on the offsite disposal option workers exposed to hazardous materials, to chosen. Populations and environments verification that the intended level of cleanup along routes chosen for transportation be- has been reached. tween sites and disposal facilities are exposed to risk of spills while wastes are in Technical Approaches for Remedial Control transit. Those responsible for the remedial action become generators under the provi- The following review and discussion of the sions of RCRA with all the associated re- generic technology options is based on consul- sponsibilities and liabilities. Such methods tations with professionals working in the area are neither cost effective for large amounts of uncontrolled site remediation, a recent study 203 of low-level hazardous waste, nor for un- for EPA of remediation technologies, and containerized buried waste dispersed proceedings from annual conferences on un- 204 through a large area. controlled hazardous waste sites. Any tech- Excavation with onsite treatment.—This nological option for site remediation has limita- approach can be used for some onsite tions that will keep it from being effective treatment technologies such as fixation, under all circumstances. Examples of technol- use of mobile treatment units for physical —. or chemical treatment or incineration, or ZOJ~nvlronmenta] ~rote~tl~n Agency, ‘‘ Handbook—Reined ial for site preparation and lining prior to re- Action at Waste Disposal Sites, ” EPA 625/6-82-006, June 1982. Z04These \,o]umes are published by the Hazardous Materials interment. Such methods can expose Control Research Institute, Silver Spring, Md. wastes quite efficiently to a treatment 210 ● Technologies and Management Strategies for Hazardous Waste Control

~~Table 38.—Advantages and Disadvantages of Control Technologies~~

Type Advantages Disadvantages Waste control technologies: Excavation and removal followed by a) Good for containerized or bulk disposal a) High initial costs treatment or disposal b) Potential higher risk during cleanup c) Relocation of risk unless waste is treated d) Not cost effective for low-level hazardous waste or uncontainerized buried waste in large area Excavation with onsite treatment a) Expose waste to complete treatment a) High initial cost option b) No off site exposure b) Difficult to assure monitoring effectiveness c) Some risk of exposure d) Not cost effective for large amount of low-hazard waste Neutralization/stabilization a) Useful in areas where waste can be a) Limited application excavated prior to mixing b) Requires long-term land use b) Low risk of exposure if injection regulations method is used c) Eventual off site migration if reaction is incomplete Biodegradation Low costs Difficult to maintain optimum conditions to keep reaction going Solution mining Useful in homogeneous uncontainerized Can result in uncontrolled release solvent-soluble, buried solid hazardous waste Environmental pathway (vector) control: Isolation, containment, and Useful for large volumes of mixed a) Effectiveness depends on physical encapsulation hazardous and domestic waste, and conditions at site low-hazard waste b) Long-term O&M needed Ground water diversion and recovery Useful if soils are permeable or if there a) Requires wastewater treatment option are high or perched water tables b) Process is slow c) O&M monitoring d) Not effective for insoluble or contain erized material Surface water diversion a) Easy to implement Can create flooding off site b) No transport of waste off site Ground and surface water treatment a) Can be used onsite or off site a) May generate hazardous sludges, spent carbon b) Long-term monitoring Gas collection or venting Low costs a) Site safety and fire hazards b) Off site air pollution c) Long-term monitoring and O&M O&M—operating and maintenance SOURCE: Off Ice of Technology Assessment

process and, in some cases, may be less mobile treatment process chosen. This expensive than excavation followed by technology is not cost effective for large transportation to an offsite treatment facil- amounts of low-level waste and is not ef- ity. offsite populations are not exposed to fective for uncontainerized waste dis- possible spills. Future O&M costs are elim- persed through a large area. inated with future risks if waste destruc- ● Direct neutralization/stabilization/fixation or detoxification options are also im- tion.–This technology is used primarily plemented. There is a high initial cost, and for large volumes of homogeneous uncon- long-term monitoring is required when the tainerized liquids or sludges. Agents are reinterment option is chosen. Local popu- injected directly into the ground where lation is subject to additional risks inherent wastes are buried, Neutralization, an acid- in the excavation and exposure of buried base balancing mechanism, aids in the re- waste, as well as those inherent in the moval of hazardous constituents through Ch. 5— Technologies for Hazardous Waste Management • 271

Table 39.—Types of Remedial Action Employed takes place, replacing at least some of the at a Sample of Uncontrolled Sites chlorine atoms with the reagent glycols Number of theoretically forming less toxic and less Remedial action sitesa Percent of total bioaccumulative compounds. In unpub- Waste actions: lished EPA testing, a solution of 1,000 ppm Drum and contaminant removal 126 410/0 Contaminant treatment 48 16 hexachlorobenzene was destroyed with 95 Incineration 3 1 percent efficiency in 7 days at room tem- Dredging 5 2 on route of release: perature, and reapplication achieved com- Action 205 Capping/grading 59 19 pletion. However, the chemistry of this Ground water pumping 22 7 process at ambient temperatures and in Ground water containment 23 8 Encapsulation 8 3 the presence of water has yet to be proven, Gas control 3 1 Lining 7 2 and little has been published. Important questions concerning the composition of — 304 100’/0 aAs many as 25 spill sites may be Included the resulting compounds and their tox- SOURCE S R Cochran, et al , “Survey and Case Study Invest lgatlon of Remedial icities remain to be studied. Further, these Act Ions at Uncontrolled Hazardous Waste Sttes “ In Marragemerrf of Uncontrolled Hazardous Waste S/fes, Hazardous Materials Control reagents have not yet been applied outside Research Insf(fute, 1982 pp 131 135 the laboratory. Biodegradation.—Microhial degradation precipitation. Fixation immobilizes solu- techniques have been applied to uncon- ble waste by binding them with a stable tainerized, biodegradable organic waste, material, Thus, an immobile solid is usually for spills. It possibly might be used formed. Onsite applications eliminate the as a final step to remove low concentra- need for offsite disposal areas or for site tion residuals left at sites after the use of upgrading following removal of excavated other technologies, such as excavation materials. There is low risk of exposure to with offsite disposal or ground water re- buried waste when the injection option is covery and treatment. Biodegradation is chosen. However, the technology has lim- usually a low-cost option. However, the ited application and requires long-term method requires acclimated organisms, land use restrictions at the site along with and supplemental injections of nutrients environmental monitoring. Reaction or or oxygen may be required to support bio- immobilization may be incomplete, and logical action. The limited applications are there may be eventual breakdown and slow and are affected by ambient temper- stripping from repeated flushing by ground ature. water, resulting in subsequent offsite mi- Solution mining.—This method is re- gration of hazardous waste, stricted to limited (and unusual) situations In addition, other detoxification tech- where a homogeneous, uncontainerized, niques to be used at the site are being re- solvent-soluble, solid hazardous waste is searched, One method is a chemical de- buried. Solvent is injected into the site and chlorination or dehalogenation process recovered through a series of well points. which uses a sodium or potassium poly- Various applications of this technology use ethylene glycol reagent. The sodium re- water as the solvent. Caution must be agent (NaPEG) patented by the Franklin taken that dissolving nonmobile hazardous Research Institute. EPA has been working waste does not produce an uncontrolled with the Institute to find a faster acting release or leave behind dissolved and reagent using potassium, In the envisioned mobile material, practice, the reagent would be spread over Environmental pathway control for hazard- a spill or dump site. Perhaps it would be ous waste sites attempt to inhibit offsite migra- covered for rain protection and to raise —. Zoschar]es Rogers, IlnVrirOrlrnenta] Protection Agency, office temperature, and perhaps reapplied in sev- of Research and Development, IERL, personal communication, eral days. In principle, a series of reactions January 1983. 212 ● Technologies and Management Strategies for Hazardous Waste Control tion of hazardous materials by a number of may require additional remedial action. methods, as discussed below. The most com- Security for this approach, where the mon route amenable to such controls is water— water route is of concern, can be enhanced surface, ground, and rainwater; although gas by combination with a ground water re- controls are sometimes used at sites where covery and treatment system. methane or other gases are present. In most Ground water diversion and recovery.— cases, there is a continuing need for monitor- These methods make use of collection and ing and potential need for repeated remedial diversion trenches or of well points with actions. Pathway control technologies include: pumping, and sometimes in combination with subsequent up-gradient injection or ● Isolation, containment, and encapsula- percolation ponds to shift piezometric sur- tion techniques.—Mechanical barriers— faces, The technology is useful in situa- e.g., in capping, bottom sealing, and pe- tions where underlying soils are permeable rimeter containment barriers—use natural (e.g., sands or fractured shales where well materials (e. g., clay) or synthetic imperme- points may be used) or at sites with a high able materials (e. g., asphalt, cement, po- or perched water table and underlying clay lymer sheet, chemical grout) that are either or other tight formations where trenches poured, injected, or placed into desired may be used, These diversion methods are locations to provide containment or inhibit effective for collecting highly contami- water intrusion on buried hazardous nated leachate before dilution after mix- waste. Surface contour modifications and ing with main body of ground water, Effec- revegetation are used to enhance rain- tive recovery can be enhanced with up- water runoff or to capture it for subsequent gradient injection, Ground water flow removal via natural processes of evapora- rates consequently are increased, and an tion and transpiration. Such methods are augmented volume of flush water is pro- used in those situations where no onsite vided to wash soluble hazardous constitu- treatment or removal is planned or where ents from the site to the collection system. there is a need to contain residuals from This technology generally requires waste such actions. They are most practical at water treatment, although collected water sites with extremely large volumes of can be directly discharged to a surface mixed hazardous and domestic wastes or stream if it meets applicable discharge with widespread low-level contamination standards. The process is slow and re- (e.g., mine tailings or contaminated soil] quires O&M and constant monitoring of where costs of alternative actions are pro- the collection system and the offsite envi- hibitive. The costs of these techniques are ronment, It is not effective for container- favorable compared with those of other op- ized materials or insoluble waste. tions, and exposure of buried waste is not Surface water diversion. -These diver- required, The effectiveness of these meth- sion methods are used where surface ods, however, is greatly dependent on am- streams run through or near an uncon- bient environmental conditions, such as trolled site, Such systems are relatively geohydrology, precipitation, and geomor- easy to implement with existing technol- phology. Long-term O&M as well as long- ogy. Addition of undesirable water on the term monitoring are required.206 Failure ✎ site is not required, and associated offsite ZOOA recent study on the use of slurry wai] i nsta]]ations con- transportation of hazardous materials is cluded: “Unfortunately, most of the slurry wall installations to reduced. However, offsite flooding prob- date have been in the private sector, from which little monitoring data are available. Until such data are assembled and cri- lems may be created, tiqued, it remains to be seen just how effective, and how long Ground and surface water treatment.— term this remedial measure is in controlling the spread of con- These treatment methods may be used taminated ground water. ” P. A. Spooner, et al., “pollution Migra- tion Cut~ff Using Slurry Trench Construction, ” in Management where there is a system to recover contam- of Uncontrolled Hazardous Waste Sites, Hazardous Materials inated water and may be implemented ei- Control Research Institute, 1982, pp. 191-197, ther offsite or onsite. Treatment technol- Ch 5— Technologies for Hazardous Waste Management • 213

ogy is the same as for other aqueous Hazardous waste in the form of sludges wastes—biologil, al, carbon absorption, and spent carbon may be generated. physicallchemical, or air stripping. Vari- ● Gas collection or venting .—These meth- ous levels of treatment can be chosen in ods are used for collection of gases for combination with appropriate collection treatment, or for controlled venting of methods. Effectiveness is limited by the gases generated at a site from decomposi- ability of the associated collection system tion of organic matter or from chemical to contain and recover the hazardous reactions of waste. Such technologies pro- waste, There have been some operational vide methods of handling toxic or flam- problems where waste characteristics mable gases that may present site safety vary, as is often encountered at hazardous and fire hazards as well as offsite air pollu- waste sites that have a history of receiv- tion threats. Long-term monitoring is re- ing mixed waste, although batching and quired, and there are O&M costs. equalization can minimize this problem.

~~Appendix 5A. –Case Examples of Process Modifications~~

Chlor-Alkali Process Diaphragm Cell Process .—The advantage of this process is that it does not use mercury. If a graphite The production of chlorine and sodium hydrox- electrical terminal is used, the waste contains chlo- de is an important process in the chemical indus- rinated hydrocarbons that are considered hazard- ry. These chemicals are major materials for the ous constituents (e.g., chloroform, carbon tetra- manufacture of many different consumer and in- chloride, and trichloroethane). Another source of dustrial products such as pulp and paper, fibers, hazardous waste using this process is the asbestos plastics, petrochemicals, fertilizers, and solvents. diaphragm, While not yet regulated under RCRA, The production process is a large-scale system in disposal of asbestos is limited by regulations pro- which modifications have been extensively imple- mulgated for the Toxic Substances Control Act. mented in the past to achieve higher process effi- Three modifications have occurred that reduce ciencies. Significant reduction of hazardous waste the amount of hazardous waste generated in a generation is possible through still further process chlor-alkali process. The first has been substitution nodifications, of a diaphragm cell for the mercury cell in most The chlor-alkali process is based on electrolysis production facilities in the United States. This has of brines—i.e., an electric current is passed through been possible because of the availability y of natural a solution of sodium chloride to produce chlorine, salt brine in this country, which is a preferred raw hydrogen, and sodium hydroxide. Two basic proc- material for the diaphragm cell process. This sub- ess designs were originally developed: one incor- stitution has been quite successful; in the last 15 porates a mercury cell and the other utilizes a dia- years, no new mercury cell plants have been con- phragm cell. Each type of cell has advantages and structed. disadvantages which will be discussed below. A second modification has reduced successfully Mercury Cell Process .–This process yields a very the amount of chlorinated hydrocarbons found in ligh quality of sodium hydroxide. A disadvantage, process waste. This was accomplished by replacing however, is that it results in a large concentration the graphite anode with a dimensionally stable of mercury discarded in process waste. Although anode (i. e., an electrical terminal). In addition to his process accounts for only 25 percent of the the reduction of hazardous constituents in waste, chlorine production in the united States, approxi- this modification contributed to a more efficient mately 42,000 tonnes of mercury-contaminated and longer cell life. rine are disposed in landfills on an annual basis. The third modification, development of a memb- Source segregation technologies do exist to remove rane cell, incorporates a major change in the type ome of the mercury from waste, but complete re- of membrane used in the diaphragm cell process. noval is not possible. Waste containing various The asbestos membrane is replaced with an ion- hlorinated hydrocarbons also are produced. exchange membrane, which generates a higher 214 Ž Technologies and Management Strategies for Hazardous Waste Control quality of sodium hydroxide. This quality is similar reliable performance has been demonstrated with to that produced by the mercury cell. Full develop- relatively few operating problems, ment and use of this modification would reduce the Chlorinolysis represents a recovery option. High amount of hazardous waste generated in two ways: pressure and temperatures are used to reduce the 1. mercury contamination in chlor-alkali waste liquid chlorohydrocarbon waste to carbon tetra- would be eliminated by a complete phase-out chloride. This system has two major drawbacks: of the mercury cell process, and 1) the capital costs are high because of the high 2. the amount of asbestos waste would be re- pressures and temperatures; and 2) the demand for duced. carbon tetrachloride is decreasing due to regulatory The membrane cell is a new modification and has restrictions on the use of products for which it is not yet been incorporated on a large scale. A total a raw material—e.g., fluorocarbons. Therefore, of 25 units of various sizes have been built in the chlorinolysis is an unlikely choice in the future world. A small unit (1 I tonnes/day) currently is reduction of liquid waste from VCM production operating in a U.S. pulp mill. A larger unit (220 unless new uses are found for carbon tetrachloride. tonnes/day) will be in operation in the United States Another option for handling VCM liquid waste by late 1983. The capital investment required for is to use a catalytic fluidized-bed reactor process incorporation of a membrane cell is slightly higher developed by B. F. Goodrich. Hydrogen chloride than a diaphragm cell that also offers a savings in gas is recovered and can be recycled without fur- energy costs. For those facilities with capacities of ther treatment as feedstock in the oxychlorination less than 500 tonnes/day, a membrane cell is more process, The advantages of this system are low tem- economical than a diaphragm cell. At greater ca- perature operation, direct recycling of hydrogen pacities, neither system is superior, and other fac- chloride without additional treatment require- tors will determine the selection. These include the ments, and energy recovery, The primary disadvan- availability of appropriate raw material (e. g., nat- tage of this recovery process results from restric- ural salt brine or solid forms of sodium chloride) tive requirements for application—i.e., only a plant and ease of retrofitting an existing facility. using an oxychlorination process in conjunction with a fixed-bed reactor can accept the hydrogen Vinyl Chloride Process chloride gas as feedstock. If an oxychlorination plant has a fluidized-bed reactor, the hydrogen chlo- Vinyl chloride monomer (VCM) is one of many ride must be adsorbed from the gas stream and re- chemicals manufactured by the chlorohydrocarbon covered with conventional recovery technology, industry. This chemical is considered a hazard to The added cost of the absorption process makes this human health, its production is regulated under the option prohibitive for fluidized-bed oxychlorination Occupational Safety and Health Act, and its dis- plants. posal is regulated under RCRA. It is an intermediate product in the manufacture of PVC and can be Metal-Finishing Process produced by several different manufacturing routes. Several modifications in metal cleaning and seal- About 92 percent of all VCM plants in the United ing processes have enabled the metal-finishing in- States have both oxychlorination and direct chlori- dustry to eliminate requirements for corporation nation plants onsite. The manufacture of VCM pro- owned and operated wastewater pretreatment facil- duces gaseous emissions of the monomer and liquid ties. An example is provided in figure 5A.1. This process residues that are a mixture of chlorinated process is designed to remove oil and grease from hydrocarbons. metal parts and seal the surface in preparation for Incineration of these process wastes is used to application of a coating. The process consists of six recover hydrogen chloride, which is either recycled stages, The parts are cleaned in stage 1, rinsed in back to the VCM process or neutralized. Conven- stage II, treated in stage III, rinsed in stage IV, tional incinerators designed for onsite treatment of sealed in stage V, and rinsed in stage VI. many different wastes are not effective in the treat- The first modification is the incorporation of flow ment of chlorinated hydrocarbons, as incomplete controllers to decrease the volume of water used combustion results. Therefore, high-efficiency in- in rinse. This results in a reduced volume of poten- cineration specifically designed for liquid or gas- tially hazardous sludge. While the flow in rinse eous chlorinated hydrocarbons is used. Although stages IV and VI can be controlled without affect- success with incineration systems has been mixed, ing other stages, any change in stage II will affect Ch. 5— Technologies for Hazardous Waste Management ● 215

~~Figure 5A.1 .—Metal Preparation for Coating Applications~~

~~Metal parts for treatment Description of process modification~~

~~Stage~~

~~1. Flow controller used to decrease volume Stage II of water used.~~

~~Originally, a combination of nickel and zinc used. First changed to all zinc (reduce hazard). Subsequently changed to manganese or iron depending on 1 metal finishing process required.~~

~~I I StagelV Rinse 3. Flow controllers used to decrease volume of water used.~~

L I 4. Originally chromic acid solution of both I trivalent and hexavalent chromium. First Stage V Sealer changed to all trivalent chromium (reduce hazard). Subsequently changed I I to organic compound.

~~I 1 5. Flow controller used to decrease volume Stage Vl Rinse of water used.~~

~~Prepared metal parts sent to finished process~~

SOURCE Office of Technology Assessment directly the quantity of chemicals required for stage and, for certain applications, manganese or iron III. For example, a decrease in rinsewater flow pro- can be substituted for zinc. Presence of iron in duces a more alkaline rinse. Thus, more acid is re- wastewater actually can be beneficial for municipal quired in stage III. Increased acid levels also re- waste treatment processes as it facilitates removal quire additional amounts of metallic ions, such as of phosphorus. nickel and zinc. Therefore, any changes in flow An acidic solution containing chromium in both control for stage II must be carefully balanced with the hexavalent and trivalent states is normally used increased chemical requirements for stage 111. in stage V. A third modification involves replace- A second process modification occurs in stage III ment of hexavalent with the trivalent chromium, with the replacement of nickel and zinc by less haz- reducing the hazard. The chromium can be re- ardous metals. Zinc can be substituted for nickel placed entirely with a biodegradable organic com- 216 ● Technologies and Management Strategies for Hazardous Waste Control pound. These modifications made in stages III and water treatment. Potential markets for recovered V permit discharge of metal-finishing wastewater ferric oxide salts are in magnetic tapes, pigments, directly into municipally owned treatment facili- steelmaking, and sintering operations. ties. Such changes also eliminate formation of haz- Sulfuric and hydrochloric acid pickling account ardous sludge. for 85 to 90 percent of all pickling operations in the United States. Presumably, recovery of these acids Case Examples of a Recovery/Recycle Operation for recycling could reduce spent liquor disposal by that same percentage. Because spent pickle liquor Recycling of Spent Pickle Liquor in the Steel Industry represents a large-volume hazardous waste, recovery and recycle could reduce the volume of hazard- A major waste disposal problem for the steel in- ous waste disposed. dustry concerns spent liquor from a pickling operation. The pickling process removes surface scale and rust from iron and steel prior to application Recovery Technologies of a final coating. The metal is immersed in an acid bath and as the scale dissolves, iron salts are form- Recovery processes are designed to recover either ed. The contaminated acid bath is known as spent the free acid or both free acid and iron salts. Two pickle liquor. methods are available for recovery of spent sulfuric Approximately 500 million gal/yr of spent pickle and hydrochloric acid liquor. Cooling of the liquor liquor are generated from acid pickling. This solu- results in separation of ferrous sulfate crystals. The tion contains 0.5 to 16 percent acid and 10 to 25 unit operations required in this recovery system percent ferrous salts. Ninety percent of the total are: 1) precooking, 2) crystallization, 3) slurry acid is hydrochloric or sulfuric acid; the remainder thickening, and 4) crystal separation by centrifuga- often includes nitric acid. The presence of nitric tion. Another process involves roasting the ferrous acid in spent liquor will determine which recovery sulfate to produce ferric oxide and sulfur dioxide. option is possible. The sulfur dioxide can be scrubbed to regenerate Several disposal/treatment options are available: sulfuric acid. This is similar to the roasting process ● injection into deep wells; originally developed for recovery of hydrogen chlo- ● neutralization of the spent pickle liquor (using ride. lime, soda ash, or caustic soda to increase the Spent liquor from hydrochloric acid-pickling op- pH level) and landfilling the resulting sludge; erations recovery technology is similar to the above ● recovery and regeneration of acid; sulfuric acid recovery technologies. Roasting fer- ● byproduct recovery; and rous chloride produces ferric oxide and hydrogen ● discharge to wastewater treatment facilities. chloride gas. Auxiliary fuel is used to maintain Because increased transportation costs and stricter reactor temperature at 1,5000 F. The hydrogen chlo- regulations have limited the availability of suitable ride gas generated is absorbed in water to form deep wells, costs for containing spent liquor have hydrochloric acid for recycle. Unit operations in- risen steadily. The gelatinous iron hydroxide sludge clude: 1) evaporation, 2) high-temperature decom- formed after neutralization creates a disposal prob- position, 3) absorption, and 4) scrubbing of vent lem, and costs of chemicals required for neutraliza- gases. tion also have increased. Thus, the attractiveness Economic Factors .—The economics of acid recovery of the first two options is reduced. are based on cost and availability of acid, disposal The remaining options involving some type of re- cost of spent pickle liquor, quality and market value cycling and/or recovery have become more viable. of byproducts (iron sulfate or iron oxide), and cost Spent liquor can be used directly in treatment of of selected recovery processes. Each of these fac- municipal wastewater for removal of phosphorus. tors is dependent on the particular plant and proc- Addition of spent sulfuric acid has been shown to ess involved. be particularly effective for water and wastewater Major economic advantages of acid recovery are treatment. Acid recovered from spent liquor can reduced raw material costs, elimination of trans- be recycled back to the pickling process. The salts portation costs incurred in disposal of spent liquor formed (ferrous sulfate from sulfuric acid pickling or sludge, and byproduct sales credits. The major and ferrous chloride from hydrochloric acid pick- economic disadvantages are utility requirements ling) have several uses. For example, ferrous sulfate (primarily fuel requirements for hydrogen chloride crystals currently are used in the manufacture of recovery from dilute aqueous solutions) and capital pigments, magnetic tapes, fertilizers, and in waste- investment requirements, Ch. 5— Technologies for Hazardous Waste Management ● 217

Byproduct recovery of spent liquor for waste- ply increased storage requirements. Storage of water treatment does not require a capital invest- spent liquor can create certain problems, e.g., ment. This is a major advantage for this option, premature precipitation of ferrous sulfate during However, disposal costs and repurchase of acid periods of low temperature. In addition, early sepa- have been estimated at $ll0/tonne compared to ration of acid from various sources of spent liquor recovery costs of about $22 to $88/tonne. may be required to eliminate potential contamina- Corporate Factors .–Regional recovery/recycle facil- tion from proprietary chemical additives. Another ities provide the opportunity of transferring bur- disadvantage to a regional facility is added costs dens of investment cost from individual steel opera- for transportation of spent liquor and recovered tions to a commercial recovery developer and of- acid from the generator to the recovery facility and fer reduced risk. However, regional facilities im- then to the consumer. 218 • Technologies and Management Strategies for Hazardous Waste Control

Table 5A.l.—Summary Evaluation of Liner Types . Range of a Liner material Characteristics Costs Advantages — Disadvantages Soils: Compacted clay Compacted mixture of onsite soils L High cation exchange capacity, Organic or inorganic acids or soils to a permeability of 10-7cm/sec resistant to many types of bases may solubilize portions of Ieachate clay structure Soil-bentonite Compacted mixture of onsite soil, L High cation exchange capacity, Organic or inorganic acids or water and bentonite resistant to many types of bases may solubilize portions of Ieachate clay structure Admixes: Asphalt-concrete Mixtures of asphalt cement and M Resistant to water and effects of Not resistant to organic solvents, high quality mineral aggregate weather extremes; stable on partially or wholly soluble in side slopes; resistant to acids, hydrocarbons, does not have bases, and inorganic salts good resistance to inorganic chemicals: high gas permeability Asphalt- Core layer of blown asphalt M Flexible enough to conform to Ages rapidly in hot climates, not membrane blended with mineral fillers and irregularities in subgrade; resist- resistant to organic solvents, reinforcing fibers ant to acids, bases, and particularly hydrocarbons inorganic salts Soil asphalt Compacted mixture of asphalt, L Resistant to acids, bases, and Not resistant to organic solvents, water, and selected in-place salts particularly hydrocarbons soils Soil cement Compacted mixture of Portland L Good weathering in wet-dry/freeze- Degraded by highly acidic cement, water, and selected ln - thaw cycles; can resist moder- environments place soils ate amount of alkali, organics and inorganic salts Polymerlc membranes: M Low gas and water vapor perme- Highly swollen by hydrocarbon ability; thermal stability; only solvents and petroleum oils, slightly affected by oxygenated difficult to seam and repair solvents and other polar liquids Chlorinated Produced by chemical reaction M Good tensile strength and elonga- Will swell in presence of aromatic polyethylene between chlorine and high tion strength; resistant to many hydrocarbons and oils density polyethylene inorganic Chlorosulfonate Family of polmers prepared by H Good resistance to ozone, heat, Tends to harden on aging; low polyethylene reacting polyethylene with acids, and alkalis tensile strength, tendency to chlorine and sulfur dioxide shrink from exposure to sun- Iight, poor resistance to 011 Elasticized Blend of rubbery and crystalline L Low density; highly resistant to Difficulties with low temperatures polyolefins polyolefins weathering, alkalis, and acids and oils Epichlorohydrin Saturated high molecular weight, M Good tensile and teat strength; None reported rubbers aliphatic polethers with chloro- thermal stability; low rate of gas methyl side chains and vapor permeability; resistant to ozone and weathering, resistant to hydrocarbons, sol - vents, fuels, and oils Ethylene Family of terpolymers of ethylene, M Resistant to dilute concentrations Not recommended for petroleum propylene propylene, and nonconjugated of acids, alkalis, silicates, phos- solvents or halogenated rubber hydrocarbon phates and brine, tolerates solvents extreme temperatures; flexible at low temperatures; excellent resistance to weather and ultraviolet exposure Neoprene Synthetic rubber based on H Resistant to oils, weathering, None reported chloroprene ozone and ultraviolet radiation; resistant to puncture, abrasion, and mechanical damage Polyethylene Thermoplastic polymer based on L Superior resistance to oils, Not recommended for exposure to ethylene solvents, and permeation by weathering and ultraviolet light water vapor and gases conditions Polyvinyl Produced in roll form in various L Good resistance to inorganic; Attacked by many organics, chloride widths and thicknesses; poly- good tensile, elongation, including hydrocarbons, sol- merization of vinyl chloride puncture, and abrasion resistant vents and oils; not recom- monomer properties, wide ranges of mended for exposure to weath- physical properties ering and ultraviolet light conditions Thermoplastic Relatively new class of polymeric M Excellent oil, fuel, and water None reported elastomers materials ranging from highly resist- polar to nonpolar ance with high tensile strength and excellent resistance to weathering and ozone aL - $1 10 S4 installed costs per sq yd In 1981 dollars, M = S4 to S8 per sq yd , H = S8 to $12 per sq yd SOURCE “Comparative Evaluation of Incinerators and Landfills, ” prepared for the Chemical manufacturers association, by Englneerlng Science, McLean, Va, May 1982