Primary treatment included a new 75-foot diameter circular clarifier with continuous sludge and scum removal. Effluent from the primary clarifier is treated in one of the two aeration basins. The aeration basins have new fine bubble membrane diffusers installed to increase oxygen transfer capability. The oxygen is provided by four new centrifugal blowers and is continuously supplied to the aeration basins and aerobic digesters to sustain the waste reducing microorganisms. Wastewater from the aeration basins flows to two secondary clarifiers. Return activated sludge is pumped back to the aeration basins; the return sludge pumps were enlarged to an increased firm capacity of 3 MGD. Waste activated sludge from the clarifiers is pumped to the aerobic digesters before being dewatered in the centrifuge facility.
Solids from the primary clarifier and thickened waste activated sludge from the secondary clarifiers is aerobically digested in the new 100-foot diameter anaerobic digester or the two existing aerobic digesters. The solids are dewatered by a centrifuge and transported to the landfill for disposal.
The project also included a new chemical disinfection building that utilizes sodium hypochlorite and sodium bisulfate for chlorination and dechlorination, respectively. The chemicals are stored in bulk liquid form in the chemical building and chemicals are fed into the plant effluent.
The project was successfully completed in 2003 and resulted in over $700,000 in shared savings being returned to the city. By utilizing the Design-Build project delivery method, the Burns & McDonnell team realized the savings through incorporation of several value engineering ideas developed in partnership with city staff.
