Effect of organic compounds on the performance of a step-feed hybrid MBR process

An innovative process step-feed Anaerobic (Anoxic/Oxic) n-Membrane Bioreactor [An-(A/O) n-MBR] was developed to treat synthetic domestic wastewater. Performance of the lab-scale system was investigated at different organic compounds in the influent. The results showed that, under the conditions imposed, although the COD concentration fluctuated in the range of 120-1200mg/L, high performance on COD removal was achieved in the system and more than 95% removal efficiency were obtained throughout the operation. However, COD levels in the influent had great influence on nitrogen and phosphorus removal. When COD level was low (120~200mg/L), poor performance of nitrogen and phosphorus removal were obtained because of carbon source deficiency. Good performance on TN and TP removal were achieved when COD level was in the range of 350~710mg/L, and the average removal efficiency of TN and TP was above 85% and 84%, respectively. But when COD increased to a high level (1110~1200mg/L), the performance of nitrogen and phosphorus removal also deteriorated possibly because of the shift of the composition of the microbial communities.