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Pollution Prevention in Wastewater Collection and Treatment
Introduction
Wastewater collection and treatment systems vary from community to community depending on the population size and needs of the citizens. Such systems may separate the storm and sanitary discharges or have a combined system or both. All wastewater collection and treatment systems are responsible for collecting and treating residential, commercial and industrial wastewaters. The practices and processes used to collect and treat wastewater have the potential to pollute and an equal opportunity to prevent pollution. Wastewater treatment plants have an opportunity to act as prevention role models for their residential, commercial, and industrial customers and to help or require dischargers to reduce their own toxic discharges to sewers through education, on site assistance, and regulatory programs.
Losses from collection and treatment activities may be categorized into four categories:
Operations and maintenance.
Wastewater treatment.
Other operations.
Vehicle/equipment maintenance.
Typical Wastes Generated
Potential losses which contribute to pollution:
Sewer line and wastewater treatment operations and maintenance is key to insuring proper treatment of wastewater and protection of the environment. Losses include leaks from pipes, unintended discharges to water ways, etc.
The wastewater treatment process involves treating both the liquid and solid factions of waste water. In doing so, various chemicals may be added to either the solids or the liquids to produce an appropriate product meeting discharge requirements. Sample of losses include lab waste, methane flare, bar screen waste, grit chamber material, etc.
Other operations in a wastewater collection and treatment system may include such things as wetlands, storage tanks, pesticide and herbicide use, use of well water, and purchasing practices. Spills and leaks from containers, purchasing a hazardous chemical over an alternative non-toxic chemical, etc. contribute to losses that increase pollution in the environment.
The proper maintenance of vehicles and equipment is key to wastewater treatment. Potential wastes found in this area are emissions from vehicle use, spill/leaks/drips from equipment, etc.
Top Pollution Prevention Opportunities
Keep harmful chemicals out of the sewer lines and protect line workers, the plant, and the public's investment. Work closely with assistance programs at the local and state level, such as pollution prevention programs, economic development commissions and pretreatment programs.
Institutionalize a preventative maintenance program to predict problems before they occur instead of reacting to them after their occurrence.
Design, implement and evaluate sewage acceptance procedures including provisions for spill prevention, discharge limitations, hauler performance guarantee, and enforcement or permit revocation.
<Explore, evaluate and implement alternatives to existing wastewater treatment processes, such as UV and osmosis, to avoid toxic chemicals such as chlorine and hypochlorite.
Reuse or recycle solids such as primary scum and secondary screenings in areas such as landscaping. Check local and state regulations for any special requirements.
Post and track statistical control tools so all employees know at what level the plant is operating and what the target operation level is.
Establish a screening mechanism for procurement of chemicals which evaluates non-toxic alternatives, and reduces chemical dependence thereby lowering hazardous waste and your hazardous waste generator status.
Be innovative in use and reuse of energy, such as fuel cells operating from methane, participating in DOE's Green Lights Program, use of variable speed pumps, and using heating/air conditioning controls and room sensors in buildings.
Create a gain share program whereby employees benefit from reduced pollution and for sharing ideas (Labor unions embrace pollution prevention as a health and safety issue for their members).
Use alternative transportation, such as bicycles, at the facility. Offer transit subsidies, telework, and flex-schedules for employees.
Success Story
The City of Portland, Oregon's Environmental Services operates and maintains the collection and treatment systems of two wastewater treatment facilities for 550,000 people in the greater Portland area. Columbia Boulevard Wastewater Treatment Plant's average annual day flow of 80 MGD, whereas Tryon Creek Wastewater Treatment Plant's average flow ranges from 5 to 17 MGD. Each facility provides primary and secondary treatment. Using self-directed work teams and participating in a Pollution Prevention Program field project, each facility has accomplished great results in prevention. These include:
Implementing a chemical pre-screening program;
Participating in Green Lights Program, saving $28,465.00 per year in energy costs;
Testing a new fuel cell which converts methane and produces power for use by the treatment plant;
Reducing hazardous waste generator status from large quantity generator to conditionally exempt small quantity generator; and
Reusing treated effluent to water facility grounds.
References
"Promoting Pollution Prevention Among Dischargers to POTWs," Lois N. Epstein and Steven A. Skavroneck, WEF conference, Miami, FL, October 25, 1995. Available from the Environmental Defense Fund, 1875 Connecticut Avenue NW, #1016, Washington, D.C. 20009.
For more information, contact:
Margaret Nover, Pollution Prevention Program, City of Portland, Oregon, Phone: 503-823-7623 Fax: 503-823-5565, E-mail: margaret@bes.ci.portland.or.us
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