DOCSLIB.ORG

How Is Wastewater Treated (PDF)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
How Is Wastewater Treated (PDF) FOLD FOLD FOLD We Need Your Help Industrial Service Area How is Pretreatment Here are three easy things you can do to protect The City of Everett’s wastewater treatment Wastewater water quality and minimize treatment cost. plant, called the Everett Water Pollution Control unicipal treatment plants like the EWPCF are Facility (EWPCF), is located on Smith Island 1. Keep trash out of the system. designed to treat residential and commercial in North Everett. The EWPCF serves more than Treated? ■ M Put hair, feminine hygiene products, wastewater. However, some industrial 133,000 people including all of Everett and cotton swabs and grease in the wastewater contains pollutants that primary and parts of Mukilteo, Silver Lake and Alderwood. garbage. secondary treatment cannot remove. The plant treats an average of 20 million 2. Reduce your water consumption. This wastewater requires industrial pretreatment gallons of wastewater per day, although the ■ Conserving water saves money and to remove metals, acids or other chemicals, influent volume to the plant can increase to protects the environment since the less or in the case of food services, most fats almost 100 million gallons on rainy days. water you use, the less wastewater we and grease. City staff work with industrial have to treat. customers to remove these pollutants before the 3. Keep hazardous waste out of the system. wastewater is sent to the treatment plant. ■ Never put hazardous waste down the drain. Hazardous waste includes pesticides, herbicides, solvents, paint thinners and engine oil. Hazardous Biosolids waste is any material that can catch fire, Port explode, corrode or is toxic. Biosolids are treated organic by-products of the Gardner Bay Contact the Snohomish County Household treatment process. They are settled solids and Hazardous Waste Drop-Off Station at dead microorganisms that digest and stabilize 425-388-6050 for disposal locations and for up to two years in the aeration ponds. They information. are then dredged and dewatered for use mainly on farm and forest lands. Biosolids may be Contact Us treated further, with composting for example, to produce Class A Biosolids, the highest quality If you have questions, please contact us at: biosolids product approved for the widest range of uses. City of Everett Public Works Department 3200 Cedar Street Biosolids are used as a soil amendment Everett WA 98201 since they are rich in nutrients and increase 425-257-8800 the ability of soil to retain water. Here in email: [email protected] Washington, biosolids are used to grow wheat, web: www.ci.everett.wa.us/pw apples, pasture grasses, trees and other crops. Everett Water Pollution Control Facility Biosolids are also used in soil revegetation and City of Everett Water Pollution Control Facility stabilization projects. Contact us for biosolids 425-257-8220 product availability or more information at 425-257-8220. REVISED JUNE 2009 Brought to you by the City of Everett. FOLD FOLD FOLD POND SYSTEM MECHANICAL PLANT SYSTEM 1. Aeration Ponds: Microorganisms living 1. Biological Trickling Filter: Microorganisms Treatment in the ponds consume pollutants and grow on plastic media designed to Where Does eventually die. They settle to the provide surface area and air flow. These odern wastewater treatment uses the same bottom of the ponds along with settled microorganisms consume pollutants as the Wastewater Mprocess as nature, but treatment plants speed solids and are dredged every two years wastewater trickles down this plastic media. Come From? up the process. The process has two main steps: and recycled into biosolids. As they grow and get full, they wash out of primary treatment and secondary treatment. 2. Oxidation Pond: This pond allows for the tower into the aeration tank. astewater comes from many sources including further biological activity and settling. 2. Aeration Tank: Microorganisms continue homes, businesses, industry and stormwater feeding on pollutants in this tank. W 3. Polishing Pond: This pond provides even runoff. Wastewater is 99 percent water and 1 Primary Treatment at Blowers inject oxygen to help keep the more biological treatment. percent solid and dissolved materials that are poured microorganisms as active as possible. Everett’s Plant 4. Chlorine Contact Channel: Chlorine or flushed down the drain. The wastewater enters is added to kill any remaining disease 3. Secondary Clarifiers: Slow moving water a network of more than 300 miles of underground Primary treatment at the Everett Water Pollution causing microorganisms. The water is allows the microorganisms and solids sewer pipes that lead to the treatment plant. Control Facility (EWPCF) includes the following then dechlorinated so that chlorine is to settle to the bottom of these tanks. Not all drains lead to the treatment plant. steps. Most of these steps take place at a not released into the Snohomish River. Most of the microorganisms are recycled facility called the headworks, which is the first back to the aeration tank. Some of the The City of Everett is divided into a Combined 5. Snohomish River: Treated wastewater, microorganisms are sent back to the Sewer Area and a Separated Sewer Area. stop for wastewater entering the plant. called effluent, is discharged to the aeration ponds. 1. Bar Screens: Large bar screens remove Snohomish River. trash, sticks and leaves. 4. Chlorine Contact Channel: Chlorine is In the added to disinfect any remaining disease Combined Homes 2. Grit Collectors: Large sand and gravel causing microorganisms. The water is then Sewer Area, S n settles out in the grit collector tank and dechlorinated so chlorine is not released wastewater o h o Businesses m is sent to a landfill. into the bay. and i WASTEWATER s stormwater TREATMENT h PLANT R 5. Port Gardner Bay: Treated wastewater, i 3. Primary Sedimentation Tank: Small v are e called effluent, is discharged through a PRE- r particles settle out here and grease and combined Industry TREATMENT fat are skimmed off the top of the water. series of underground pipes to a deep- in the same water outfall on Port Gardner Bay. Treated pipe, called Water Gets Treated 4. Biofilters: These filters contain wood Storm Drains effluent may also be reused as non-contact a combined chips and compost and filter the air cooling water at the Kimberly Clark Corp. sewer, and flow to the treatment plant. to reduce the odor released from the before discharge to Port Gardner Bay. wastewater. Primary In the Homes Sedimentation Secondary Treatment at Tanks Separated Headworks Biofilter , S Sewer Area n Aeration o Everett’s Plant h Businesses o Pond wastewater m i WASTEWATER s Biofilter South Chlorine h 4 goes in a TREATMENT The EWPCF has two parallel systems for secondary Contact Channel PLANT R i v sanitary e treatment: a pond system and a mechanical plant. PRE- r Industry The two systems perform identical functions, but sewer and is TREATMENT Secondary 5 3 routed to the the treatment process is different in each system. Outfall to Port Clarifiers Gardner Bay treatment Wastewater is treated in the mechanical plant using 1 Trickling No Treatment Filters plant. Storm Drains a process called Trickling Filter Solids Contact. This Snohomish River 2 Aeration Stormwater process takes up much less space and is much faster Tank than the original pond system. The mechanical goes in a storm drain and is discharged directly plant can clean wastewater in a matter of hours, Biofilter to local streams without treatment. while it takes several weeks in the pond system..
Load more

Recommended publications
  • Anaerobic Digestion of Wastewater Sludge (Nazaroff & Alvarez-Cohen, Section 6.E.3)
    Anaerobic Digestion of Wastewater Sludge (Nazaroff & Alvarez-Cohen, Section 6.E.3) nice, clean water going to disinfection and then to outdoor body of receiving water (stream, lake or sea) sludge in need of further treatment The goal is to reduce the amount of sludge that needs to be disposed. The most widely employed method for sludge treatment is anaerobic digestion. In this process, a large fraction of the organic matter (cells) is broken down into carbon dioxide (CO2) and methane (CH4), and this is accomplished in the absence of oxygen. About half of the amount is then converted into gases, while the remainder is dried and becomes a residual soil-like material. What the equipment looks like The tank is capped - to prevent oxygen from coming in, - to prevent odors from escaping, and - to capture the methane produced. This methane, a fuel, can be used to meet some of the energy requirements of the wastewater treatment facility (co-generation). What the sludge looks like after anaerobic digestion and subsequent drying. It is rich in nitrates and performs well as a fertilizer. (Photos from http://www.madep-sa.com/english/wwtp.html) 1 (Originally from Metcalf & Eddy, 1991) from & Metcalf Eddy, (Originally 6.E.7) Figure Alvarez-Cohen, & (Nazaroff How the system works The treatment of wastewater sludge, from both primary and secondary treatment steps, consists of two main phases. ● In the 1st step, all incoming flows of sludge are combined, and the mixture is heated to a mild temperature (about body temperature) to accelerate biological conversion. The residence time here ranges from 10 to 20 days.
    [Show full text]
  • Sewage Secondary Treatment After Primary Treatment, the Sewage Water Is Subjected to the Next Phase Called Biological Treatment Or Secondary Treatment
    Sewage secondary treatment After primary treatment, the sewage water is subjected to the next phase called biological treatment or secondary treatment. Dissolved and suspended biological materials are removed by indigenous microbial decomposition in a managed environment. In this treatment, BOD is reduced up to 90-95%. Biological treatment is carried out in two important phases: 1. Aerobic phase: oxidation lagoons trickling filters, activated sludge 2. Anaerobic phase: sludge digestion A. Oxidation lagoons /oxidation ponds / stabilization ponds 1. It is outdoor, simple, suspension type aerobic treatment. 2. It is suggested for small societies in rural areas where sufficient low lying land of little real state value is available. 3. It is oldest of the sewage treatment systems used in most of developing countries due to its low cost. 4. In this shallow pond is required which should be maximum of 10 feet depth having inlet and outlet. 5. It consists of three different zones as shown in the following diagram: Requirements of Oxidation pond: 1. Presence of algal growth which produces oxygen. 2. Oxygen is also available from atmosphere. 3. Heterotrophic aerobic and anaerobic microbes for decomposing sewage. 4. Sunlight required for photosynthesis, also has bactericidal properties (UV). Advantages of oxidation pond: 1. Simple 2. Inexpensive 3. Low maintenance Disadvantages of oxidation pond: 1. Effected by environment: low temperature, cloudy sky lowers efficiency 2. Takes longer time(Long retention time) 3. Gives bad odour(H2 S) 4. Not hygienic 5. Just lowers BOD by 25%to 60% B. Trickling Filter Method 1. It is also outdoor, aerobic, relatively simple but of film flow type.
    [Show full text]
  • Anaerobic Digestion of Primary Sewage Effluent
    Anaerobic Digestion of Primary Sewage Effluent Prepared for the U.S. Department of Energy Office of Electricity Delivery and Energy Reliability Under Cooperative Agreement No. DE-EE0003507 Hawai‘i Energy Sustainability Program Subtask 3.4: Biomass Submitted by Hawai‘i Natural Energy Institute School of Ocean and Earth Science and Technology University of Hawai‘i September 2014 Acknowledgement: This material is based upon work supported by the United States Department of Energy under Cooperative Agreement Number DE-EE0003507. Disclaimer: This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference here in to any specific commercial product, process, or service by tradename, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. SUMMARY A hybrid system comprised an up-flow packed bed anaerobic reactor and a down-flow trickling-filter reactor connected in series was shown to effectively treat primary clarifier effluent. When a clarifier and sand filter were added to the system, the effluent water quality achieved values of BOD5 and TSS that were below the EPA’s water discharge limits of 30 mg/l and equivalent to highly efficient activated sludge systems.
    [Show full text]
  • Treatment and Biosolids Technologies
    Treatment and Biosolids Technologies City of Morro Bay New Water Reclamation Facility Engineering Component of Siting Study • Project engineering team will look at the following parameters related to each site: – Range of cost for conveyance, treatment, and distribution to potential users – Land availability for range of treatment and biosolids management options • A range of treatment technologies can reach City objectives – Keep options open during preliminary planning Public Workshop Results Top‐Ranked Issues from Dot Exercise • Environmental – Avoid Visual Impacts • Cost Issues – Keep Costs Low (highest score) • Engineering and Design – Recharge Morro Aquifer Overview • Environmental – Effluent reuse goals – Quality and Quantity – Conveyance methods for recycled water • Cost Issues / Engineering and Design – Liquid treatment technologies – Biosolids processing technologies / products – Procurement Treatment Processes • Preliminary – Screening of large solids • Primary –Flotation & settling • Secondary – Biological Treatment Source of • Tertiary – Filtration Biosolids • Disinfection • Advanced – Salts – Contaminants of Emerging Concern Treatment Process Selection Driven by End Goals 1. Start with effluent reuse goals 2. Identify treatment technologies to meet those goals 3. Develop plan for handling biosolids from range of liquid treatment options Effluent Reuse Goals ‐ Quantity • “How much” varies seasonally • Evapotranspiration rates determine potential use for irrigation • Wet weather or production of “off‐spec” water often require
    [Show full text]
  • Giving Wastewater a Boost with Breakthroughs in Secondary Treatment Brent Giles Research Director About Lux Research Coverage Areas
    Giving Wastewater a Boost with Breakthroughs in Secondary Treatment Brent Giles Research Director About Lux Research Coverage areas . Advanced Materials Helps clients find new business opportunities from . Agro Innovation emerging technologies in physical and life sciences . Alternative Fuels Offers ongoing technology and market intelligence, as . Autonomous Systems 2.0 well as market data and consulting services . Bio‐based Materials & Chemicals . Bioelectronics Over 250 clients on six continents – multinational . Efficient Building Systems corporations, investors, governments, and SMEs . Energy Electronics . Energy Storage Global reach,with offices in Boston, New York, . Exploration and Production Amsterdam, Singapore, Shanghai, and Tokyo . Food and Nutrition . Printed, Flexible, and Organic Combines deep technical expertise with business analysis Electronics to support strategic decisions . Solar . More at www.luxresearchinc.com Sustainable Building Materials . Water 2 Contents Problems with existing wastewater treatment A picture of the “average” activated sludge plant Six innovative technologies go head to head Stickney Water Reclamation Plant, Chicago 3 Contents Problems with existing wastewater treatment A picture of the “average” activated sludge plant Six innovative technologies go head to head Stickney Water Reclamation Plant, Chicago 4 Wastewater treatment gobbles energy and produces large volumes of sludge The dominant process for treating the world’s wastewater, activated sludge, faces three major issues: High energy Mountains of The squeeze consumption waste sludge for space 5 Anaerobic digestion reduces, but doesn’t eliminate waste sludge Does not scale down well Many facilities need to combine sludge with other waste streams Reduces sludge volume by about 40%, but you still have to do something with the remaining stabilized biosolids 6 Many U.S.
    [Show full text]
  • Municipal Wastewater Anaerobic Treatment with Enhanced Clarification Kevin Berg Marquette University
    Marquette University e-Publications@Marquette Master's Theses (2009 -) Dissertations, Theses, and Professional Projects Municipal Wastewater Anaerobic Treatment with Enhanced Clarification Kevin Berg Marquette University Recommended Citation Berg, Kevin, "Municipal Wastewater Anaerobic Treatment with Enhanced Clarification" (2015). Master's Theses (2009 -). 331. https://epublications.marquette.edu/theses_open/331 MUNICIPAL WASTEWATER ANAEROBIC TREATMENT WITH ENHANCED CLARIFICATION by Kevin J. Berg A Thesis submitted to the Faculty of the Graduate School, Marquette University, in Partial Fulfillment of the Requirements for the Degree of Master of Science Milwaukee, Wisconsin August 2015 ABSTRACT MUNICIPAL WASTEWATER ANAEROBIC TREATMENT WITH ENHANCED CLARIFICATION Kevin J. Berg Marquette University, 2015 As energy costs rise, water reclamation facilities (WRFs) desire lower cost, easily operated systems to remove BOD5 and suspended solids. WRFs typically utilize an aerobic process called activated sludge to remove biochemical oxygen demand (BOD). BOD, specifically 5 day BOD (BOD5), is used as an indicator of the organic strength of a solution. Anaerobic treatment provides an alternative to activated sludge by removing BOD5, generating biogas containing methane for energy and producing less biomass that requires disposal. Anaerobic treatment functions as an exceptional alternative to activated sludge when packaged as a system with a small footprint that operates at ambient temperature. These systems can produce effluent with organic constituent quality similar to activated sludge without requiring the energy inputs that conventional treatment demands. In this work, an anaerobic, fluidized bed reactor (FBR) treating both synthetic and real domestic primary effluent was utilized to remove BOD5 from wastewater. The reactor was operated at 10°C to determine operation under challenging, low-temperature conditions.
    [Show full text]
  • The Activated Sludge Process Part II Revised October 2014
    Wastewater Treatment Plant Operator Certification Training Module 16: The Activated Sludge Process Part II Revised October 2014 This course includes content developed by the Pennsylvania Department of Environmental Protection (Pa. DEP) in cooperation with the following contractors, subcontractors, or grantees: The Pennsylvania State Association of Township Supervisors (PSATS) Gannett Fleming, Inc. Dering Consulting Group Penn State Harrisburg Environmental Training Center MODULE 16: THE ACTIVATED SLUDGE PROCESS – PART II Topical Outline Unit 1 – Process Control Strategies I. Key Monitoring Locations A. Plant Influent B. Primary Clarifier Effluent C. Aeration Tank D. Secondary Clarifier E. Internal Plant Recycles F. Plant Effluent II. Key Process Control Parameters A. Mean Cell Residence Time (MCRT) B. Food/Microorganism Ratio (F/M Ratio) C. Sludge Volume Index (SVI) D. Specific Oxygen Uptake Rate (SOUR) E. Sludge Wasting III. Daily Process Control Tasks A. Record Keeping B. Review Log Book C. Review Lab Data Unit 2 – Typical Operational Problems I. Process Operational Problems A. Plant Changes B. Sludge Bulking C. Septic Sludge D. Rising Sludge E. Foaming/Frothing F. Toxic Substances II. Process Troubleshooting Guide Bureau of Safe Drinking Water, Department of Environmental Protection i Wastewater Treatment Plant Operator Training MODULE 16: THE ACTIVATED SLUDGE PROCESS – PART II III. Equipment Operational Problems and Maintenance A. Surface Aerators B. Air Filters C. Blowers D. Air Distribution System E. Air Header/Diffusers F. Motors G. Gear Reducers Unit 3 – Microbiology of the Activated Sludge Process I. Why is Microbiology Important in Activated Sludge? A. Activated Sludge is a Biological Process B. Tools for Process Control II. Microorganisms in Activated Sludge A.
    [Show full text]
  • Wastewater Treatment Processes
    Wastewater Treatment Processes (Sep 12 th -15 th , 2016) by Dr. Arun Kumar ( [email protected] ) Objective: To learn about processes used in wastewater treatment plant Courtesy: Dr. Irene Xagoraraki, MSU, USA September 27, 2016 Arun Kumar 1 ([email protected]) Minor 1 copies • Minor 1 copies next week Monday afternoon in different slots • Slot timings will be emailed. September 27, 2016 2 Characteristics of Domestic Wastewater September 27, 2016 4 Wastewater characteristics • Compare wastewater (WW)characteristics of – Domestic WW – Industrial WW (for ex: tannery industry; distillery industry) September 27, 2016 5 Wastewater Management Different sources http://dnr.metrokc.gov/WTD/homepage/process.htm Wastewater Management www.oconomowocusa.com/ wastewater.gif Municipal Wastewater Treatment Systems • Preliminary treatment (removes materials that can cause operational problems, equalization basins are optional) • Primary treatment (remove ~60% of solids and ~35% of BOD) • Secondary treatment (remove ~85% of BOD and solids) • Advanced treatment (varies: 95+ % of BOD and solids, N, P) • Final Treatment (disinfection) • Solids Processing (sludge management) Pre-Treatment of Industrial Wastewaters • Industrial wastewaters must be pretreated prior to being discharged to municipal sewer system • Pretreatment requirements set by regulatory agencies • Why: remove materials that will not be treated by municipal system, remove materials that inhibit the biological processes in secondary treatment • For example: silver ions are toxic to
    [Show full text]
  • Comparative Analysis of Grey Water Treatment Using Vermifilter Through Various Filter Depth Level
    Special Issue - 2019 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 ICONEEEA - 2k19 Conference Proceedings Comparative Analysis of Grey Water Treatment using Vermifilter Through Various Filter Depth Level 1* 2 T. Janani , Dr. S. Evany Nithya 1 2 Student, Asst.professor/HOD, Department of Civil Engineering, University college of engineering (BIT campus), Tiruchirappalli, Tamilnadu, India. Abstract:- Wastewater contains high number of organic solids consists of low number of organic solids and inorganic and harmful contaminants. Due to these harmful substance solids comparatively low than wastewater but these grey wastewater treatments is essential but many developed and waters is one of the major parts of wastewater so developing countries like India cannot construct and maintain treatment of grey water in house itself reduce the volume the conventional centralized sewage treatment plants due to of wastewater production. untreated grey water consists of high cost of treatment and high amount of wastewater production. So, cost effective and eco-friendly decentralized high amount of microorganism. These pathogens make sewage treatment system is needed in small areas. Hence grey water as harmful. So, treatment is essential before vermifilteration can be very effective for small villages and usage. According to United States Environmental colonies. In this system filter bed is inoculated with Protection agency, grey water can be treated to varying earthworms (Eisenia fetida). these earthworms body works as degrees U (victor G.Ngnaga et. al,2012) It can be treated a “biofilter” and it has high efficiency to remove BOD, using various secondary treatment. Mainly we have used COD.TSS by the general mechanism of biodegradation and Activates sludge process, waste stabilization pond, adsorption of organic wastes.
    [Show full text]
  • Supporting Document #3
    Supporting Document 3 Leachate Treatment Alternatives – Assessment and Evaluation Methodology Waste Management of Canada Corporation West Carleton Environmental Centre Landfill Footprint Expansion LEACHATE TREATMENT ALTERNATIVES – ASSESSMENT AND EVALUATION METHODOLOGY Prepared by: AECOM Canada Ltd. Project Number: 60242342 Date: August, 2012 Leachate Treatment Alternatives – Assessment and Evaluation Methodology West Carleton Environmental Centre Table of Contents Page 1. Overview of Leachate Treatment Alternatives ................................................. 1 1.1 Background .......................................................................................................... 1 1.2 Report Objective .................................................................................................. 1 2. Considerations for Leachate Treatment Alternatives ..................................... 2 2.1 Leachate Control.................................................................................................. 2 2.2 Leachate Generation Rate ................................................................................... 2 2.3 Leachate Quality .................................................................................................. 3 2.4 Leachate Pretreatment ........................................................................................ 5 2.4.1 Equalization .............................................................................................. 5 2.4.2 Biological Treatment ................................................................................
    [Show full text]
  • WASTEWATER TREATMENT Freshwater Water Quality 1
    WASTEWATER TREATMENT Freshwater Water Quality 1. INDICATOR (a) Name: Wastewater treatment. (b) Brief Definition: Proportion of wastewater that is treated, in order to reduce pollutants before being discharged to the environment, by level of treatment. (c) Unit of Measurement: Percentage of volume of generated wastewater treated by primary treatment, secondary treatment, tertiary treatment or not treated. (d) Placement in the CSD Indicator Set: Freshwater/Water Quality. 2. POLICY RELEVANCE (a) Purpose: This indicator assesses the potential level of pollution from domestic and industrial/commercial point sources entering the aquatic environment, and monitors progress towards reducing this potential within the framework of integrated water resources management. It helps to identify communities where wastewater treatment action is required to protect the ecosystem. Wastewater from households and different industries represent a significant pressure on the environment and treatment is normally required before discharge. The indicator assesses the proportion of wastewater that undergoes different (primary, secondary and tertiary) levels of treatment. It includes the volume of wastewater treated at public wastewater treatment plants, industrial wastewater treatment plants and by independent wastewater treatment systems. For treated wastewater from households (sometimes mixed with industrial wastewater in a public collecting system) to be considered acceptable it should undergo at least secondary treatment either at a public wastewater treatment
    [Show full text]
  • Performance Indicator Analysis As a Basis for Process Optimization and Energy Efficiency in Municipal Wastewater Treatment Plants
    UPTEC W 14 008 Examensarbete 30 hp Februari 2014 Performance Indicator Analysis as a Basis for Process Optimization and Energy Efficiency in Municipal Wastewater Treatment Plants Elin Wennerholm ABSTRACT Performance Indicator Analysis as a Basis for Process Optimization and Energy Efficiency in Municipal Wastewater Treatment Plants Elin Wennerholm The aim of this Master Thesis was to calculate and visualize performance indicators for the secondary treatment step in municipal wastewater treatment plants. Performance indicators are a valuable tool to communicate process conditions and energy efficiency to both management teams and operators of the plant. Performance indicators should be as few as possible, clearly defined, easily measurable, verifiable and easy to understand. Performance indicators have been calculated based on data from existing wastewater treatment plants and qualified estimates when insufficient data was available. These performance indicators were then evaluated and narrowed down to a few key indicators, related to process performance and energy usage. Performance indicators for the secondary treatment step were calculated for four municipal wastewater treatment plants operating three different process configurations of the activated-sludge technology; Sternö wastewater treatment plant (Sweden) using a conventional activated-sludge technology, Ronneby wastewater treatment plant (Sweden) using a ring-shaped activated-sludge technology called oxidation ditch, Headingley wastewater treatment plant (Canada) and Kimmswick wastewater treatment plant (USA), both of which use sequencing batch reactor (SBR) activated-sludge technology. Literature reviews, interviews and process data formed the basis of the Master Thesis. The secondary treatment was studied in all the wastewater treatment plants. Performance indicators were calculated, to the extent it was possible, for this step in the treatment process.
    [Show full text]