The Cultivation of Denitrifying Phosphorus Removal-aerobic Granular Sludge under Low Carbon Condition: Removal Performance and Microbial Characteristics

Abstract

The sequencing batch reactor (SBR) was inoculated with fully granulated aerobic granular sludge (AGS). In this study, AGS was induced to enrich the denitrifying phosphorus-accumulating organisms (DPAOs) by gradually reducing the influent chemical oxygen demand (COD) concentration (550, 400, 160 mg/L). Here, the maximum denitrifying phosphorus removal efficiency of AGS and the microbial community were investigated. The removal efficiencies of TN and TP were greatly improved during the enrichment of DPAOs, increasing from 64.57% to 80.48% and 59.56% to 81.89%, respectively. Meanwhile, due to dense structure of AGS, aerobic and anoxic/anaerobic layers could be formed to promote the cultivation of DPAOs. The PPR and PUR of DPR-AGS were 6.02 mg TP/(g SS h) and 5.20 mg TP/(g SS h), respectively. Through high-throughput sequencing, predominant phosphorus accumulating organisms in AGS was the Canadidatus Accumulibacter, which had excellent denitrifying phosphorus removal capacity. The results indicated that DPAOs could be well enriched in AGS under low carbon condition.