Improved membrane sequencing batch reactor: effect of carbon and nitrogen volumetric loading rate on dephosphatation

ABSTRACTA lab-scale anaerobic–anoxic–aerobic membrane bioreactor (A2NO-MBR) fed with synthetic wastewater was operated to investigate the impact of influent carbon and nitrogen volumetric loading rate (VLR) on dephosphatation, and the corresponding influent concentration was 100–300 mg L−1 (COD), 24–50 mg L−1 (NH4+–N) and 4.8–6.0 mg L−1 (TP), respectively. The results demonstrated that carbon VLR had a negligible effect on the COD removal with effluent below 50 mg L−1, and high and stable removal capacity for phosphorus were also obtained, regardless of carbon VLR change. Whereas TN removal efficiency was positively correlated with carbon VLR reduction, and lower carbon VLR produced a negative effect on TN removal. In addition, since nitrate served as an electron acceptor for denitrifying phosphorus removal (DPR), a significant effect on nitrogen and phosphorus removal was observed with different nitrogen VLR. The TN and TP removal efficiency was 68.30 ± 1.36%, 70.70 ± 1.23%, 45.19 ± 1.72% and 41.63 ± 3.0...