EXPANDING PLANT CAPACITY WITH HIGH RATE ANAEROBIC TREATMENT AT THE CEDAR RAPIDS, IOWA WATER POLLUTION CONTROL FACILITY

An additional 100,000 lbs./day of BOD capacity was required at the Cedar Rapids Water Pollution Control Facility (WPCF) to accommodate continuing growth. The City, in conjunction with engineering consultants, compared the economics of adding additional aerobic treatment versus using anaerobic treatment to treat a portion of the high strength wastewater discharged to the plant. The anaerobic treatment alternative included segregation and separate conveyance of selected high strength industrial wastewater to the WPCF. The economic evaluation indicated anaerobic treatment was significantly lower cost than aerobic treatment. CH2M HILL and Howard R. Green were retained to design an anaerobic treatment system and conveyance facilities to separately convey and treat selected high strength wastewater.Although the concept may have applications in many Cities, this project is unique in many respects including:Believed to be the largest anaerobic wastewater treatment system in North America and one of the top 5 largest anaerobic wastewater treatment systems in the worldTreatment technologies traditionally used by industries are part of the municipal planIntegrated into the municipal plant rather than a remote facility at an industry or industrial parkDedicated sewers to separately convey industrial wastewater to the plantWastewater cooling facilities to cool up to 5.95 MGD of wastewater from 114°F to 98°F.First North American application of a European technology to biologically remove 1.5 to 2.8 percent H2S from the biogas prior to using the biogas for sludge incinerationFirst municipal application of floating hood pure oxygen aerators in uncovered aeration tanksFast track design and construction requiring staged design, four separate construction contracts, and competitive guaranteed price proposals to allow pre-selection of key process equipment