Performance evaluation and microbial dynamics of submerged anaerobic membrane bioreactors for municipal wastewater treatment

It is challenging to treat municipal wastewater anaerobically and gain energy to provide an economically sustainable process. In this study, the municipal wastewater treatment performance of AnMBR was investigated, and the membrane fouling along with the microbial community dynamics were evaluated. In this scope, COD and nutrient removal, methane production, SMP and EPS, TMP, CST, SRF, and microbial community within the reactor were investigated. AnMBR was operated in two periods. In the first period (P1), HRT and flux averaged 23.5 ± 0.4 h and 3 ± 0.1 LMH, respectively. In the second period (P2), HRT and flux averaged 12.4 ± 1.2 h and 5.7 ± 0.5 LMH, respectively. The OLRs were 0.53 ± 0.04 and 1.00 ± 0.14 kg/(m³·d) for P1 and P2, respectively. Maximum COD removal efficiency around 92 % was obtained while average methane yield was 207 ± 17.3 mL CH₄/gCOD_consumed. AnMBR permeate has the potential for agricultural irrigation due to its high nutrient content and quality. The bacterial community abundance changed through the acclimation and operation of AnMBR. Carbohydrate and amino acid metabolisms are the major metabolism cluster. The bacterial family fermenting carbohydrates under anaerobic conditions Anaerolineaceae and anaerobic mesophilic acetogens Bacteroidetes were the predominant families in the bacterial community. No significant fouling has been observed during AnMBR operation, as the modification of the membrane module has contributed to the alleviation of fouling, which resulted in obtaining stable flux and constant TMP. The treatment of municipal wastewater with AnMBR can be energy-positive without heating in tropical climates.