Pilot Study on Anoxic/Aerobic Membrane Bioreactor for Domestic Wastewater Treatment

An Anoxic/Aerobic Membrane Bioreactor (A/O-MBR) system have been developed to improve the efficiency of nutrient removal. The important factors those system are the ratio of anoxic zone/aerobic zone (VA:VO), internal recycle rate (IR) and solids retention times (SRT). The optimal ratio of anoxic zone/aerobic zone was 1:3. The IR ratio and SRT for effective nutrient removal were 300% and 30d, respectively. For VA:VO of 1:1, 1:2 and 1:3, there was little difference in the removal of CODCr, NH3-N and TN, although the nutrient removal efficiencies were difference to others. In comparing IR of 100%, 200% and 300%, the CODCr, NH3-N removal efficiencies were stable and good, and the removal efficiency of nitrogen increased from 62%~68% to 71%~75%. In addition, SRT is one of the important factors affecting the mixed liquor suspended solids, considering the nutrient removal efficiencies, SRT of 30d was the most stable condition. Under these conditions, the anverage removal efficiencies of CODCr, NH3-N and total nitrogen were about 93.6%, 93.2% and 71.2%.