Study on Treatment of Domestic Wastewater by Submerged Flat MBR

The treatment of dormitory and refectory mixed wastewater by a submerged flat membrane bioreactor (MBR) was studied. The A/O MBR system treated wastewater 4 m³/d. The mean removal efficiency of BOD₅ and COD_Cr was more than 95% with the influent concentration of 100~500 mg/L BOD₅ and 120-900 mg/L COD_Cr. It was proved that active carbon treatment reduced effluent chroma effectively. At the steady working period (MLSS 8,000~15,000 mg/L), TN and NH₃-N removal efficiencies were more than 85%, and that of TP was between 50% and 95%. Besides, this paper studied the membrane fouling mechanism and revealed that membrane fouling was affected by MLSS, particle size distribution of sludge and composition of raw water. We found that the diameter of sludge particles changes with the MLSS. We also found the small particles caused membrane fouling. The results proved that submerged flat MBR was suitable to treat small-or-medium-size domestic and industrial wastewater and would have a promising future.