Case Study for Customer Location CA90:
Reservoir or Lake Use:
Sludge storage basins associated with the municipal wastewater treatment plant.
System Overview and Reservoir:
The municipal wastewater treatment plant is an extended aeration system consisting of two oxidation ditches. Sludge from the secondary clarifiers is pumped to aerobic digesters and then to two sludge storage basins (1.6 surfaces acres each basin). The current average daily flow to the WWTF is 1.6 million gallons per day, and the sludge storage basins receive about 5,000 gallons of 0.5% waste activated sludge per day. The operating depth is 9 ft, with approximately 4-5 ft of sludge in each basin. Each basin had 30 hp (2 x 15 hp) of brush aerators installed, operating 24 hours per day for 365 days per year.
Reported Problem Before SolarBee Installation:
Objectives were to provide energy/cost savings by eliminating brush aerator run time and associated maintenance costs, while maintaining odor capping.
SolarBee Installation:
Date: August 2004. Installed two (2) SB10000v12-OC odor capping SolarBee machines, one in each basin. The SolarBees are anchored in a manner so as to permit sludge dredging equipment to operate around the SolarBees without having to remove or relocate the SolarBees.
Results:
Since the SolarBees were installed, the desired odor capping and residual dissolved oxygen (DO) goals have been achieved continuously without needing the brush aerators. DO concentrations have remained above 3 mg/L, algal blooms and surface scums have been eliminated, and water clarity has noticeably improved. Each SolarBee replaced 2 brush aerators per basin, for an energy savings of 30 hp per basin and 60 hp for the project. Annual savings to the District are expected to be 400,000 kW-hrs of consumption, and 60 hp
of demand charges. This installation qualified for incentive funding from the Wastewater Optimization Program (mandated by the Public Utility Commission), which paid for 54% of the total cost of the SolarBees, making the payback period about 2 years. In addition to being very happy with the improved water quality, odor control, and the realized energy and economic savings, the General Manager of the town wrote in 2007 that he “will forever remember SolarBee for its outstanding customer service.”
One SolarBee in one of two sludge storage basins.
Updated: 04/10/2007
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