[Long-term Performance and Bacterial Community Composition Analysis of AGS-SBR Treating the Low COD/N Sewage at Low...

This study utilized the sequencing batch activated sludge reactor (SBR) inoculated aerobic granular sludge (AGS) to treat the low COD/N ratio (<4.0) domestic wastewater under low DO (0.5-1.0 mg·L^-1) concentration condition. Long-term performance of simultaneous nitrogen and phosphorus removal and bacterial community composition of AGS-SBR were studied. The results showed that the AGS-SBR system had good and stable decontamination abilities in its 180-day operation. The average removal rates of COD, NH₄⁺-N, TN and TP were 87.17%, 95.21%, 77.05%, and 91.11%, respectively. At the same time, the AGS showed good settling performance, and always kept its integrated and compact structure. No obvious granular sludge disintegration phenomenon occurred in 180 days. Meanwhile, by using Illumina 16S rRNA gene MiSeq sequencing, we investigated the bacterial abundance in AGS-SBR reactor. Proteobacteria, Firmicutes, Chlorobi, Chloroflex, and Bacteroidetes were the dominant microbial communities in the simultaneous nitrogen and phosphorus removal reactor. Denitratisoma, Planctomycetaceae, Thauera, Comamonas, Nitrosomonas and Nitrospira were suggested to be the primary organisms responsible for the nitrogen removal. Clostridium and Anaerolinea were the main bacterial communities of phosphorus removal.