Purification of polluted surface water by sponge moving bed membrane bioreactor with short hydraulic retention time operation

Abstract

A sponge moving bed membrane bioreactor (SMB‐MBR) was developed for high‐rate biological purification of polluted surface water for nonpotable utilization purposes. The SMB‐MBR contains polyurethane sponge cubes (10% v/v) and submerged hollow fibre membranes in a solid separation compartment and operated under a short hydraulic retention time of 1 h. High organic (96% biochemical oxygen demand [BOD], 85% soluble chemical oxygen demand [COD] and 84% COD) and nitrogen (99% ammonium nitrogen [NH4+], 98% total Kjeldahl nitrogen [TKN] and 87% total nitrogen [TN]) removals were achieved. In the SMB‐MBR, the suspended and attached biomass were allowed to develop under no sludge wastage operation. The co‐existence of heterotrophs, nitrifiers and denitrifiers in the biomass was confirmed under a high oxygen environment. Sustainable operation of SMB‐MBR could be achieved by maintaining stable membrane flux without chemical cleaning for 60 days. This research demonstrates the technical feasibility of applying the SMB‐MBR for clean water production when the polluted surface is the only raw water source.