Integration of moving bed biofilm reactor and gravity-driven membrane bioreactor for decentralized domestic wastewater treatment: Efficiency and mechanistic insights

This study investigated the coupling of a moving bed biofilm reactor (MBBR) with a gravity-driven membrane bioreactor (GDMBR) for the long-term treatment of decentralized domestic wastewater. The results indicated that the introduction of MBBR significantly improved the stable flux of GDMBR (by 8 % – 22 %) and enhanced its resistance to the shock loading of influent quality. Such improvements were attributed to the reduction in extracellular polymeric substances (EPS) (by 30 % – 46 %), positive modifications to the membrane biofilm, and improvements in microbial richness and community composition. Compared to GDMBR control, the start-up period of MBBR-GDMBR systems was reduced by 6–15 days, owing to the beneficial effects of MBBR-derived microorganisms, which promoted microbial evolution within the GDMBR membrane biofilm, thereby accelerating the stabilization of filtration performance. Overall, this study provides valuable insights into shortening the start-up period of the GDMBR process, enhancing its resistance to external shock loads, and improving flux levels.