Enhanced anoxic biodegradation of pyridine coupled to nitrification in an inner loop anoxic/oxic-dynamic membrane bioreactor (A/O-DMBR)

Abstract Enhanced biodegradation of high-strength pyridine was successfully achieved in the inner loop anoxic/oxic-dynamic membrane bioreactor (A/O-DMBR) in this study. Due to the key role of dynamic membrane in biomass retention, NH 4 + released from pyridine biodegradation could be effectively nitrified to NO 3 − in oxic zone, which was then recirculated into the anoxic zone to serve as electron acceptor for pyridine biodegradation. Acetate dosage adversely affected pyridine biodegradation, due to the competitive effect of acetate towards NO 3 − . Increase of recirculation ratio positively affected pyridine biodegradation, due to high availability of NO 3 − at high recirculation ratio. At influent pyridine concentration as high as 1500 mg L −1 , effluent turbidity was well maintained below 10 NTU, indicating excellent biomass retention performance of the dynamic membrane. Microbial community analysis confirmed the enrichment of specific functional species in both anoxic and oxic zones. Stable performance during 260 days’ operation confirmed the potential of A/O-DMBR for full-scale application.