Record Display for the EPA National Library Catalog


Main Title Replacement of activated sludge secondary clarifiers by dynamic straining /
Author Joyce, Michael, ; Schultz, William ; Strom., Arvid
Other Authors
Author Title of a Work
Schultz, William,
Storm, Arvid,
CORP Author FMC Corp., Itasca, Ill. Environmental Equipment Div.;Environmental Protection Agency, Washington, D.C. Office of Research and Development.
Publisher National Environmental Research Center, Office of Research and Development, U.S. Environmental Protection Agency,
Year Published 1975
Report Number EPA-670/2-75-045; EPA-68-03-0102; EPA-ROAP-21ASR-039
Stock Number PB-242 828
OCLC Number 01611190
Subjects Sewage--Purification--Activated sludge process ; Sewage disposal plants ; Sewage clarifiers
Additional Subjects Sewage filtration ; Activated sludge process ; Clarification ; Strainers ; Sewage treatment ; Aeration tanks ; Waste water ; Straining ; Feasibility ; Liquids ; Solids ; Pilot plants ; Separation ; Industrial wastes ; Ultrasonic frequencies ; Transducers ; Cost analysis ; Dynamic straining
Internet Access
Description Access URL
Library Call Number Additional Info Location Last
EJBD  EPA 670-2-75-045 c.1 Headquarters Library/Washington,DC 09/19/2013
ELBD ARCHIVE EPA 670-2-75-045 Received from HQ AWBERC Library/Cincinnati,OH 10/04/2023
ELBD  EPA 670-2-75-045 AWBERC Library/Cincinnati,OH 04/26/2017
NTIS  PB-242 828 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation vii, 76 pages : illustrations ; 27 cm.
Pilot plant studies were conducted on domestic wastewater to determine the feasibility of replacing conventional activated sludge gravitational clarifiers by dynamic straining. The dynamic strainers consisted of a rotating cylinder cleaned by an internal ultrasonic transducer. A primary strainer was placed and operated directly in the mixed liquor in the aeration tank. A secondary strainer was installed and operated in a separate tank to further clarify the effluent from the primary strainer. This work indicated that dynamic straining is a technically feasible process for replacing conventional activated sludge gravitational clarifers. Suspended solids removals of well over 99% were achieved with a single primary strainer operating in the pilot plant aerator with a mixed liquor suspended solids concentration of over 6,500 mg/l. When operated at lower specific flow rates, primary straining appears to be capable of consistently producing an effluent suspended solids in the 15-30 mg/l range. Present economic predictions indicate that plants equipped with primary and secondary dynamic strainers would cost more than plants utilizing conventional secondary gravity clarifiers. This factor can be tempered by several projected dynamic straining advantages. Two-stage dynamic straining has excellent application where space limitations exist. Secondary gravity clarifiers could be eliminated under the right conditions and aeration tank sizes could be appreciably smaller with the higher MLVSS concentrations achievable with dynamic straining.
Report prepared by FMC Corporation, Environmental Equipment Division, Itasca, Illinois. "Contract no. 68-03-0102; program element no. 1BB043." Includes bibliographical references (page 49).