Design and Operation of a Pilot-Scale Biological Phosphate Removal Plant at Central Contra Costa Sanitary District

Abstract

A pilot plant incorporating side-stream biological phosphate (P) removal was operated at the Central Contra Costa Sanitary District (CCCSD), CA, USA wastewater treatment plant from Apr-Dec 1981. Secondary effluent total P< 1 mg P/L was obtained consistently both when the plant nitrified and did not nitrify. The P-stripper usually employed elutriation of solids with primary effluent, however operation with no elutriation was tested briefly. A minimum elutriation rate was required for successful P removal in this study. Uptake and release of Mg2+ and K+ accompanied P uptake and release. Bulking at low F/M was controlled by introducing two small-volume compartments at the head end of the aeration basin.