August 2008, Vol. 20, No.8
Test Your Knowledge of Distributed Wastewater Management
True or False Questions:
- In distributed wastewater management, wastewater treatment systems are dispersed across a service area and may include individual onsite systems, cluster or community systems, satellite facilities, and/or large central wastewater facilities.
- Distributed wastewater treatment systems may be found within urban, suburban, and rural areas.
- Septic systems are only a temporary treatment solution until a sewer line and central wastewater treatment plant can collect and treat wastewater generated on a property.
- Properly designed soil treatment units or soil dispersal areas have the ability to clean effluent to tertiary standards, remove such emerging contaminants as endocrine-disrupting compounds, and naturally disinfect the water.
- Central wastewater treatment systems are always the least-cost alternative for wastewater treatment.
Multiple Choice Questions:
Which of the following choices is NOT a potential benefit of distributed wastewater treatment systems?
A. Aquifer and watershed recharge.
B. Reuse of effluent for beneficial purposes.
C. Guaranteed reduction in project costs.
D. Reduced nutrient and pollutant loadings on waterbodies.
What is the average design hydraulic retention time for domestic wastewater in a septic tank?
A. 8 hours
B. 2 days
C. 6 days
D. 5 years
What is the primary benefit of intermittently pumping water to a soil dispersal area?
A. Reducing power costs.
B. Promoting aerobic and facultative bacteria growth to improve treatment and extend dispersal area life.
C. Allowing maintenance time for equipment.
D. Matching dispersal pumping with generation of wastewater.
If the monthly average 5-day biochemical oxygen demand permit limit is 20 mg/L, and weekly grab sample results for the month are 18 mg/L, 25 mg/L, 22 mg/L, and 12 mg/L, how many times was the permit violated?
D. Four Times.
Reuse regulations require calculation of the annual loading of nitrogen per acre of irrigated area. Approximately 100,000 gal/wk of reclaimed water with an average total nitrogen concentration of15 mg/L is applied to a 10-ac site for 6 months of a year. How many pounds of total nitrogen were applied per acre for the year?
A. 10 lb/ac.
B. 32.5 lb/ac.
C. 325 lb/ac.
D. 1000 lb/ac.
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Questions were developed by Todd Danielson, manager of community systems at Loudoun Water (Ashburn, Va.) and a member of the Water Environment Federation (Alexandria, Va.) Small Communities Committee. Questions were reviewed by the Association of Boards of Certification (Ames, Iowa) Validation and Examination Committee.
D’Amato, Victor A., Anita Bahe, Terry Bounds, Billie Comstock, Thomas Konsler, Sarah K. Liehr, Sharon C. Long, Krich Ratanaphruks, Chet A. Rock, and Kevin Sherman (2008). Factors Affecting Performance of Primary Treatment in Decentralized Wastewater Systems (04-DEC-7). Alexandria, Va.: Water Environment Research Foundation.
Danielson, Todd (2004). “No Long Pipelines and No TMDLs,” Water Environment & Technology (November), pp. 22–25.
Kriessl, James (2007). “Year in Review,” Water Environment & Technology (December), pp. 14–15.
Siegrist, Robert (2008). “So Much for So Little: The Modern Soil Treatment Unit,” Water Environment & Technology (July), pp. 6–12.
U.S. Environmental Protection Agency Office of Wastewater Management (2005). Handbook for Managing Onsite and Clustered (Decentralized) Wastewater Treatment Systems (EPA 832-B-05-001). Washington, D.C.: U.S. Environmental Protection Agency.
U.S. Environmental Protection Agency Office of Water (2005). Decentralized Wastewater Treatment Systems: A Program Strategy (EPA 832-R-05-002). Washington, D.C.: U.S. Environmental Protection Agency.