Nitrogen and phosphorus removal from domestic wastewater using sequencing batch reactor

Nitrogen and phosphorous removal from municipal wastewaters was investigated using Sequencing Batch Reactor (SBR) in this study. For this purpose, a sequencing batch reactor with an active volume of 4 liters was fed with municipal wastewater and the effect of hydraulic retention time of phases was investigated via running the system under distinct operational phases. The SBR was run in a fill/ anaerobic/ aerobic1/ anoxic/ aerobic2/ settle/ decant sequence while distinct hydraulic retention times for phase sequences were tested during the study. Also, ORP and DO values were measured to observe their changes during the phases. The highest removal efficiencies was observed in the SET where fill / anaerobic / aerobic1 / anoxic / aerobic2 / settle / decant phases were set to be 0.5 h / 2 h / 2 h / 1 h / 0.75 h/ 1 h / 0.5 h, respectively. For this SET, the removal efficiencies of COD, TKN, NH3-N, TP and PO4-P were found to be 91%, 78%, 85%, 87% and 83% on average, respectively. ORP value was -306.9 mV min. for anaerobic phase, 39.7 mV max. for aerobic1 phase, -227.9 mV min. for anoxic phase, and 38.6 mV max. for aerobic2 phase. This SET was determined to be the most suitable one among all conditions investigated. Keywords : Sequencing Batch Reactor (SBR), nutrient removal, domestic wastewater