WRRCSR No.9:19:86 Rotating Biological Contactor Pilot Study: Fort Kamehameha Wastewater Treatment Plant, Pearl Harbor, Hawaii

Dugan, Gordon L.
Takiguchi, Dean K.
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Water Resources Research Center, University of Hawaii at Manoa
A self-contained pilot unit (including primary and secondary sedimentation) complete with electric motor driven plastic discs (surface area approximately 500 ft^2), located at the U.S. Navy's 7.5 mgd Fort Kamehameha Wastewater Treatment Plant (WWTP) at Pearl Harbor, Oahu, Hawaii, was operated from July 1985 to July 1986 at four different operating modes: hydraulic loadings of 1.5, 3.0, and 5.0 gpd/ft^2 (flat disc area) with discs exposed; and 5.0 gpd/ft^2 with discs covered. The influent for the RBC unit was primary clarifier effluent, which was very brackish for wastewater (4000-5000 mg/l chloride). In addition, wastewater from industrial-type operations that use and discharge controlled/treated concentrations of heavy metals were received at the WWTP. The median effluent BOD5 concentrations for the first two hydraulic loading rates (1.5 and 3.0 gpd/ft^2) were respectively 2.0 and 8.0 mg/l, with corresponding respective median suspended solids values of 8.0 am 7.5 mg/l. These values were comparable with the present WWTP operation utilizing the activated sludge process. Hydraulic loadings at 5.0 gpd/ft^2 provided median effluent BOD5 concentrations in the 30 to 35 mg/l range. Heavy metal concentrations in the wastewater flows of the WWTP and RBC unit were considerably below the level of concern, while some accumulation of heavy metals was noted for the higher concentrations of suspended and settled solids--the mixed liquor suspended solids and the raw and digested sludge. Replacing the existing activated sludge component with an RBC component being hydraulically loaded at 3.0 gpd/ft^2 would require an estimated capital cost of approximately $2,500,000, which would require nearly 20 years to repay in electrical cost savings, based on a 10¢/kWh electrical cost, that increases in cost at an annual rate of 5%, and an interest rate of 8% compounded annually.
raw wastewater, biochemical oxygen demand, chemical oxygen demand, wastewater treatment, secondary wastewater, primary wastewater treatment, suspended solids, rotating biological contactor, wastewater treatment efficiency, Fort Kamehameha WWTP, Oahu
Dugan GL, Takiguchi DK. 1986. Rotating biological contactor pilot study: Fort Kamehameha Wastewater Treatment Plant, Pearl Harbor, Hawaii. Honolulu (HI): Water Resources Research Center, University of Hawaii at Manoa. WRRC special report, 09:19:86.
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