A study was conducted to determine if the swirl concentrator principle could be used to provide primary treatment to combined sewer overflows and municipal wastewater. A hydraulic model with synthetic wastewater and a mathematical model were both used to arrive at an optimized configuration and a design basis. The design was then tested under actual wet- and dry-weather flow conditions using a large scale, 1,137 cu m/d (0.3 mgd) pilot constructed in Toronto, Canada. The Toronto pilot evaluations confirmed the accuracy of the design (and associated design curves) developed under the model studies. The model and pilot studies indicated that the device could achieve 30 to 50 percent settleable solids removal efficiency for flows of less than 22 l/sec (0.5 mgd) at costs comparable to, or less than, conventional treatment units. Overflow rates of two to three times that of conventional units make possible the saving. The report contains thorough descriptions of the hydraulic/mathematical and pilot studies, and most importantly, the detailed design methodology.

"August 1978." "This report supplements EPA-R2-72-008; EPA-670/2-74-039; EPA-670/2-75-011." "Prepared by American Public Works Association, under Contract no. 68-03-0272, Grant no. S-803157." "Other authors included Morris H. Cohn, James E. Ure, Fred Parkinson, G. Galiana, Ralph R. Boericke, Carl Koch, Paul Zielinski, Includes bibliographical references.