Operational Characteristics of a Full-scale Submerged Membrane Bioreactor Treating Domestic Sewage

摘要

A full-scale submerged membrane bioreactor (MBR) with capacity of 1200 m3/d is operated to treat domestic wastewater,and the effluent is used for irrigating and toilet-flushing in Tsinghua University's campus.The wastewater treatment plant is composed of a grating,a hydraulic screen,a regulating tank,a hair gathering device,and a submerged membrane bioreactor.The efficiency and process stability of the plant were evaluated over 10-month-operation.It was found that the effluent quality is good.In spite of the fluctuation of the water temperature and the hydraulic loading,the MBR was able to achieve more than 80％ in COD removal,more than 90％ in BOD removal and more than 95％ in NH3-N removal.As the result,the effluent presented mean values of 10.5 mg/L of COD,3.0 mg/L of BOD5,0.2 mg/L of NH4+-N,1.0 mg/L of SS,and lower than 0.2 NTU of turbidity,which meets the national Water Quality Standard for Urban Miscellaneous Water Consumption (GB/T 18920-2002).But the removal efficiency of total nitrogen and total phosphorus should be improved by certain measures.Because of the suitable operation,membrane fouling developed slowly,and the membrane didn't need to wash frequently,although the MLSS of the MBR reached nearly 15 g/L.The operational cost of the plant was 0.71 RMB Yuan/m3.