Biological phosphorus removal from real wastewater in a sequencing batch reactor operated as aerobic/extended-idle regime

Abstract

Recently, it has been reported that biological phosphorus removal (BPR) could be achieved in a sequencing batch reactor (SBR) with aerobic/extended-idle (A/EI) regime using synthetic medium. This paper first examined the feasibility and stability of the A/EI regime treating real domestic wastewater. The results showed that the A/EI-SBR removed 1.32±0.03–3.55±0.04mg of phosphorus per g of volatile suspended solids during the steady-state operation, suggesting that BPR from domestic wastewater could be well realised in the A/EI regime. Then, another SBR operated as the conventional anaerobic/oxic (A/O) regime was conducted to compare the soluble orthophosphate (SOP) removal with the A/EI regime. The results clearly showed that the A/EI regime achieved higher SOP removal than the A/O regime. Finally, the mechanism for the A/EI-SBR driving superior SOP removal was investigated. It was found that the sludge cultured by the A/EI regime had more polyphosphate accumulating organisms and less glycogen accumulating organisms than that by the A/O regime. Further investigations showed that the A/EI-SBR had a lower glycogen transformation and a higher PHB/PHV ratio, which correlated well with the superior phosphorus removal.