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 NH4+-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.

► Performance of a pilot-scale submerged MBR with nylon mesh as filter was studied.
► Low-strength wastewater was treated at a prolonged SRT and a low loading rate.
► High removal efficiencies of COD and NH4+-N were achieved.
► Almost zero discharge of excess sludge was achieved during the operation.
► The system shows a high potential for application in underdeveloped rural areas.