AN ANOXIC/OXIC MEBRANE BIOREACTOR FOR THE TREATMENT OF CONCENTRATED COLD-ROLLING WASTEWATER FROM REVERSE OSMOSIS PROCESS

An anoxic/oxic membrane bioreactor (MBR) system was developed and operated for 8 runs during 236 days operation for concentrated cold-rolling wastewater (CRW) from reverse osmosis (RO) process in a steel manufacturing company. The trans-membrane pressure (TMP) variation demonstrated that MBR was feasible for RO concentrated water treatment. Total nitrogen (TN) removal efficiency of 97.7 % and chemical oxygen demand (COD) removal efficiency of 96.0 % were obtained. Mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS) and sludge particle size distribution showed that high salinity in CRW could decrease the ratio of MLVSS and MLSS, and reduce the particle size of activated sludge. The results of high-throughput 454 pyrosequencing indicated that microbial communities in MBR system for RO concentrated water treatment were significantly distinct. Thauera was the dominant genus in MBR system and it could be able to degrade aromatic matters which are commonly found in steel industrial wastewater.