A pilot investigation into membrane bioreactor using mesh filter for treating low-strength municipal wastewater

A pilot-scale submerged membrane bioreactor (MBR) using nylon mesh as filter was investigated for treatment of low-strength municipal wastewater (average influent COD=145.7±59.9 mg/L). During the operation, biomass was effectively retained by the nylon mesh with biofilm attached, and a low effluent turbidity of below 2 NTU was obtained. The average COD and NH(4)(+)-N removal efficiencies reached 86.3% and 98.1%, respectively, at a hydraulic retention time of 5 h. A sludge concentration of 4.15±0.15 g/L was maintained in the system without excess sludge discharge, attributed to the prolonged solid retention time and low organic loading rate. The low sludge concentration was also beneficial for mitigating the filter fouling. Thus, this mesh filter MBR provides a low-cost, efficient and simple approach to treat municipal wastewater, and shows a high potential for application in rural and sparsely populated areas.