Domestic wastewater treatment without primary clarification by contact stabilization activated sludge process

Abstract

The contact stabilization activated sludge process (CSASP) is amply applied in full scale plants treating domestic sewage, it is usually preceded by a primary clarifier. A pilot scale CSASP without and with primary clarification was evaluated to investigate the effect of primary clarification elimination on system performance. The system performance was monitored by measuring the MLVSS, COD, BOD and TSS. The results showed that elimination of primary clarification increased the biodegradable organic matter influent by 44% but fats, oils and surfactants entrance were observed. Fats and oils formed a floating sludge layer in the surface secondary clarifier that affect its performance and sludge quality. However, COD, BOD5 and TSS removal efficiency was higher than 76% for in both CSASP without and with primary clarification.