The performance and microbial community identification in mesophilic and atmospheric anaerobic membrane bioreactor for municipal wastewater treatment associated with different hydraulic retention times

The anaerobic membrane bioreactors (AnMBR) with ring membrane module were operated under mesophilic temperature (M-AnMBR) and atmospheric temperature (A-AnMBR). Compared to the M-AnMBR, the removal efficiency of the A-AnMBR was found to be lower and the faster membrane fouling occurred in the A-AnMBR under corresponding hydraulic retention time (HRT). The MiSeq high-throughput sequencing was applied to analyze the microbial community structure. The HRT change had different effects on the community richness and diversity of the cake and bulk sludge. The abundance of phylum Proteobacteria in the M-AnMBR was higher than that in the A-AnMBR, which should account for the higher removal of nutrients in the M-AnMBR. The faster membrane fouling would occur in the A-AnMBR due to the relatively high abundance of Bacteroidetes in the bulk sludge and cake sludge. Moreover, specific comparison down to the genus level showed that the dominant abundant bacterial genera were Candidate division OP8 norank and Anaerolineaceae uncultured in the cake sludge for M-AnMBR, and were VadinHA17 norank, WCHB1-69 norank, VadinBC27 wastewater-sludge group, and Synergistaceae uncultured in the cake sludge for A-AnMBR The different representative genera with the variation of the HRTs for the two bioreactors might indicate the different performance between the two AnMBRs.