Performance evaluation of A2O MBR system with graphene oxide (GO) blended polysulfone (PSf) composite membrane for treatment of high strength synthetic wastewater containing lead

High strength synthetic wastewater containing 5 mg L−1 of lead was studied for treatment using an A2O MBR system. The system showed 99% removal of ammonia and COD, a maximum removal of 52% of total phosphorus and an average minimum removal of 72% of total nitrogen. A maximum lead removal of 98% was achieved for hydraulic retention time (HRT) of 144 h, which decreased to 85% when the influent COD concentration was decreased. Mass balance for lead revealed that much of its removal was through accumulation by the biomass present in the anaerobic and anoxic tanks. Comparative study on virgin PSf and GO blended PSf membrane showed that the GO blended membrane lasted 1.4 times longer than the other. SEM-EDS of membranes showed lead peaks on the fouled and un-fouled sections of the membranes indicating the association of lead with the foulant and the role of membrane in lead separation. Good separation efficiency was achieved irrespective of the membranes used.