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Comparison of Three Wet Weather Flow Treatment Alternatives to Increase Plant Capacity
Author: Don Esping, Bill Krill, Denny Parker, Jose Jimenez, Jim Fitzpatrick, Fenghua Yang and Tim Bate
Date: 10/12
WEFTEC 2012, New Orleans, LA, Sept. 29 Oct. 3, 2012

The Milwaukee Metropolitan Sewerage District is evaluating alternatives to increase the South Shore Water Reclamation Facility wet weather treatment capacity from 300 to 450 million gallons per day. In this study, side-by-side testing of biological contact treatment, chemically enhanced sedimentation, and compressible media filtration was conducted to define treatment performance and design criteria for treating wet weather flows. Based upon wet weather testing conducted to date on primary influent, biological contact achieved the lowest effluent concentrations and met all project effluent water quality goals when operated at mixed liquor concentrations between 1600 and 2000 mg/L and contact times of 15 minutes. Compressible media filtration effluent solids and biochemical oxygen demand concentrations were also less than the project effluent goals when operating at filtration rates of 7.5 gpm/sf. Chemically enhanced sedimentation testing was inconclusive due to equipment malfunctions during testing. At the time of this writing, additional wet weather testing was ongoing.