LAUSR

Abstract Aerobic granular sludge (AGS) has been frequently investigated as a novel wastewater treatment technology. This work explored the microbial community structure during aerobic granulation under an OLR of 6 kg COD (m3 d)−1. Extracellular polymeric substances (EPS), granule size, sludge settleability and sludge morphology were also analyzed. Tightly-bound EPS significantly accumulated during aerobic granulation, when the extracellular protein played a key role in AGS due to the increasing extracellular protein/extracellular polysaccharide ratio. The microbial community diversity and richness declined sharply in the first 40 days during aerobic granulation. Flavobacteriaceae, Propionibacteriaceae, Burkholderiaceae, Rhodocyclaceae, Chitinophagaceae and norank_o_Saccharimonadales were dominant families in AGS. The EPS producers, carbohydrate degraders and glycogen accumulating organisms were key genera in the formation and stability of AGS under the high OLR condition. The results may promote the comprehension of aerobic granulation from the viewpoint of microbial community.