Modeling a Retention Treatment Basin for CSO
Publication: Journal of Environmental Engineering
Volume 133, Issue 3
Abstract
Combined sewer overflows (CSOs) result in hazardous and unsightly contamination of receiving waters, particularly swimming areas. The removal of suspended solids and associated biological oxygen demand (BOD) can accelerate the recovery following a CSO event. This paper presents a numerical model to simulate the solids removal efficiency of a retention treatment basin (RTB) that utilizes polymers to improve the flocculation and settling rates for the suspended solids. The model includes settleable, nonsettleable, and floatable solids. The sludge is treated as a non-Newtonian fluid. Discrete, zone, and compression settling/floatation regimes are included. In-tank flocculation and a storage zone for sludge flushing are also included in the model. The model was calibrated and validated with data from a RTB pilot plant, and was applied to evaluate preliminary designs for a prototype RTB for the City of Windsor. The calibrated model showed that the optimum location of the target baffle was approximately 30% of the distance to the scum baffle. For design flows of and run durations of up to , it was found that the removal was insensitive to slopes from to and depths greater than . The simulations indicate that 70 to 78% of solids removal can be achieved at surface overflow rates up to .
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Acknowledgments
The Windsor Combined Sewer Overflow Treatability Study—Chemical Coagulation was funded by the City of Windsor and by the Government of Canada through the Great Lakes Sustainability Fund. The writers gratefully acknowledge the advice and help received from Mr. Paul Drca and Mr. Kit Woods of the City of Windsor, Ms. S. Kok, Dr. P. Seto, and Dr. J. Marsalek of Environment Canada, Mr. K. Ferguson of the Ontario Ministry of the Environment, Mr. J. Drummond of the Detroit River Canadian Clean-Up Committee, Mr. David Averill of Questor Veritas Inc., and Mr. Ken Madill of Stantec Consulting Ltd.
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Information & Authors
Information
Published In
Journal of Environmental Engineering
Volume 133 • Issue 3 • March 2007
Pages: 263 - 270
Copyright
© 2007 ASCE.
History
Received: Apr 8, 2005
Accepted: Jul 10, 2006
Published online: Mar 1, 2007
Published in print: Mar 2007
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