Treatment of Micro-Polluted River Water by MBR

A pilot study was carried out to treat inferior Ⅴ grade micro-polluted river water by Anoxic /Membrane bioreactor(A /MBR)combined with pretreatment with coagulation and sedimentation.The process conditions and measures were investigated to achieve good effluent quality in terms of treating the micro-polluted river water with high concentrations of nitrogen and phosphorus and low concentrations of carbon.The pilot system with a capacity of 10 m3 /d worked at air flow-rate 8 m3 /h and HRT of the sedimentation tank,anoxic tank and membrane tank at 25 min,0.8 h and 2.5 h respectively,and under the additional conditions of MLSS concentration 6.0 ～ 6.5 g /L.The polymeric aluminums(PAC)were dosed 10 mg /L in the sedimentation tank and 5 mg /L in the membrane tank respectively,and about two times the theoretical methanol quantity was dosed in the anoxic tank.The results showed that the mass concentrations of CODCr,BOD5,NH3-N and TP in the effluent could meet the grade Ⅲ standards of Environmental Quality Standards for Surface Water(GB3838-2002),and TN was less than 15 mg /L.