Effect of influent nutrient ratios and hydraulic retention time (HRT) onsimultaneous phosphorus and nitrogen removal in a two-sludge sequencing batchreactor process

摘要

A laboratory-scale anaerobic–anoxic/nitrification sequencing batch reactor (A2N-SBR) fed with domestic wastewater was operated to examine the effect of varyingratios of influent COD/P, COD/TN and TN/P on the nutrient removal. With theincreased COD/P, the phosphorus removals exhibited an upward trend. The influentTN/P ratios had a positive linear correlation with the phosphorus removalefficiencies, mainly because nitrates act as electron acceptors for thephosphorus uptake in the A2N-SBR. Moreover, it was found that lower COD/TNratio, e.g. 3.5, did not significantly weaken the phosphorus removal, though thenitrogen removal first decreased greatly. The optimal phosphorus and nitrogenremovals of 94% and 91%, respectively were achieved with influent COD/P and COD/TN ratios of 19.9 and 9.9, respectively. Additionally, a real-time controlstrategy for A2N-SBR can be undertaken based on some characteristic points ofpH, redox potential (ORP) and dissolved oxygen (DO) profiles in order to obtainthe optimum hydraulic retention time (HRT) and improve the operating reliabilit