Vertical Baffled Reactor of High-Concentration Aerobic Granular Sludge for the Treatment of Unstable-Load Domestic Wastewater

The study evaluate the pollutant degradation ability and the microbial community of aerobic granular sludge（AGS）in the modified Vertical baffle reactors (VBRs) in the treatment of unstable–load domestic wastewater. Domestic wastewater was applied as the influent for 180 days of continuous experiments with a high pollutant removal efficiency. On day 180, MLSS maintained at 7000 mg/L with the average particle size of sludge at 1000 μm. VBRs can maintain a high sludge concentration without sludge bulking, while long HRT can ensure a high sludge concentration to cope with the high influent load. The values of extracellular polymeric substances (EPS), especially polysaccharide, increased significantly which was conducive to the bridging among particles to form AGS, which played an important role in maintaining the stability of granular sludge. The results of functional microbial communities showed that Proteobacteria was the most abundant phylum in aerobic sludge, while the Nitrospira was the dominant bacteria in genus level. The microbial community was biodiverse, and can achieve the effect of the simultaneous removal of multiple contaminants.