Design And Selection Of Small Wastewater Treatment Systems

This report provides general information on the design and selection of wastewater systems with capacities for populations up to 2500. This information is intended for use by individuals with limited experience in wastewater treatment and disposal as a source of available alternatives in small systems, as well as an outline of the steps and procedures to undertake when selecting a particular wastewater management scheme for a small community. Material covered includes: measurement and estimation of wastewater flows; physical, chemical and biological characteristics of domestic wastewater; on-site wastewater treatment and disposal processes; central wastewater collection and treatment systems; operating problems associated with small treatment systems; disposal of liquid effluents and waste sludges; and procedures employed in the selection and approval of wastewater systems. A case history is provided to illustrate the selection procedures discussed within the text.

This manual is intended to provide guidance and criteria for the design and selection of small-scale wastewater treatment facilities. It provides both the information necessary to select, size, and design such wastewater treatment unit processes, and guidance to generally available and accepted references for such information. For the purpose of this manual, small-scale wastewater treatment systems are those with average daily design flows less than 379 000 liters per day (L/d) or 100,000 gallons per day (gal/d), including septic tanks for flows less than 18 900 L/d (5000 gal/d), small prefabricated or package plants for flows between 18 900 L/d (5000 gal/d) and 190 000 L/d (50,000 gal/d), and larger prefabricated treatment systems with capacities of no more than 379 000 L/d (100,000 gal/d).

These materials, prepared for the U. S. Environmental Protection Agency Technology Transfer Program, were used in presenting Technology Transfer design seminars throughout the United States. When faced with decisions on wastewater treatment system upgrading or replacement, many small communities and rural areas run into financial difficulties. This trio of documents presents the results of research into this problem, which examines various strategies and systems, and their associated costs, in order to arm utilities managers in such communities with information vital to making informed, responsible decisions regarding wastewater treatment.

Step-by-step procedures for planning, design, construction and operation: * Health and environment * Process improvements * Stormwater and combined sewer control and treatment * Effluent disposal and reuse * Biosolids disposal and reuse * On-site treatment and disposal of small flows * Wastewater treatment plants should be designed so that the effluent standards and reuse objectives, and biosolids regulations can be met with reasonable ease and cost. The design should incorporate flexibility for dealing with seasonal changes, as well as long-term changes in wastewater quality and future regulations. Good planning and design, therefore, must be based on five major steps: characterization of the raw wastewater quality and effluent, pre-design studies to develop alternative processes and selection of final process train, detailed design of the selected alternative, contraction, and operation and maintenance of the completed facility. Engineers, scientists, and financial analysts must utilize principles from a wide range of disciplines: engineering, chemistry, microbiology, geology, architecture, and economics to carry out the responsibilities of designing a wastewater treatment plant. The objective of this book is to present the technical and nontechnical issues that are most commonly addressed in the planning and design reports for wastewater treatment facilities prepared by practicing engineers. Topics discussed include facility planning, process description, process selection logic, mass balance calculations, design calculations, and concepts for equipment sizing. Theory, design, operation and maintenance, trouble shooting, equipment selection and specifications are integrated for each treatment process. Thus delineation of such information for use by students and practicing engineers is the main purpose of this book.

This manual is intended to provide guidance and criteria for the design and selection of small-scale wastewater treatment facilities. It provides both the information necessary to select, size, and design such wastewater treatment unit processes, and guidance to generally available and accepted references for such information. For the purpose of this manual, small-scale wastewater treatment systems are those with average daily design flows less than 379 000 liters per day (L/d) or 100,000 gallons per day (gal/d), including septic tanks for flows less than 18 900 L/d (5000 gal/d), small prefabricated or package plants for flows between 18 900 L/d (5000 gal/d) and 190 000 L/d (50,000 gal/d), and larger prefabricated treatment systems with capacities of no more than 379 000 L/d (100,000 gal/d).

"This manual contains overview information on treatment technologies, installation practices, and past performance."--Introduction.

These materials, prepared for the U. S. Environmental Protection Agency Technology Transfer Program, were used in presenting Technology Transfer design seminars throughout the United States. When faced with decisions on wastewater treatment system upgrading or replacement, many small communities and rural areas run into financial difficulties. This trio of documents presents the results of research into this problem, which examines various strategies and systems, and their associated costs, in order to arm utilities managers in such communities with information vital to making informed, responsible decisions regarding wastewater treatment.