Tracing membrane biofouling to the microbial community structure and its metabolic products: An investigation on the three-stage MBR combined with worm reactor process.

•Flavobacteria, Firmicutes and Chloroflexi caused slow membrane fouling of the S-MBR.•The enrichment of β-proteobacterium brought about the rise-associated in TMP of the C-MBR.•SMPc in conjunction with EPSc and SMPp accelerated the membrane fouling.•A quick rise in SMPc triggered an abrupt increase in TMP.•The EPSc and SMPp caused the sustained increase in TMP.