Inductive effect of functional microbial consortia in promoting the rapid granulation of aerobic granular sludge in an internal circulation-membrane bioreactor

The added functional microbial consortia (SAB) was found to accelerate the formation of aerobic granular sludge (AGS) in a continuous experiment lasting 150 days, where the primary AGS was first observed on day 7 and the bioreactor was started-up very quickly and performed well in removing the main pollutants. According to the obtained results, Streptomyces sp. Esraa could form a skeleton to support the formation of AGS, while Bacillus cereus aggregated microorganisms by secreting a large amount of extracellular polymeric substances (mainly protein) continuously, and extracellular polymeric substances immediately increase from 97 mg/gMLVSS to 1551 mg/gMLVSS. With the succession of microbial community, the abundance of Streptomyces and Bacillus in sludge decreased significantly on day 21, from 43.22% to 1.78% and from 5.87% to 0, respectively, while the abundance of Bacillus in AGS remained 0.1% on day 120, and SAB was gradually replaced by other dominant microorganisms, which indicated that the added SAB exhibited an inductive effect on the formation of AGS.