Organic shock loads of different intensity and a recovery strategy for co-digestion with waste activated sludge and food waste in a continuous anaerobic dynamic membrane bioreactor: Reactor stability, filtration characteristics, and microbial community

The feasibility and reactor performance of a co-digestion system using food waste (FW) and waste activated sludge (WAS) in a continuous anaerobic dynamic membrane bioreactor (DMBR) was investigated for the first time under different intensity shock loads. The results showed that stable and high-rate operation with good filtration performance can be achieved in a continuous DMBR through gradual acclimatization under low-intensity shock loads. However, the continuous DMBR was rapidly broke down with a high-intensity shock load under the high-load conditions, as indicated by extremely low pH and methane production, even after long-term acclimatization. To address the instability issue, the bioaugmentation strategy via reinjecting high-load digestate was used to recovery the DMBR performance. This approach enhanced the microbial diversity and upregulated amino acid and energy metabolism, as evidenced by microbial community and metabolic pathways analyses. Furthermore, the Methanosarcina genus was the dominant archaea during the whole operation even with the high-intensity shock load. Therefore, the gradual acclimatization combined with bioaugmentation method is a simple and useful recovery strategy to realize stable operation even when faced with shock loads of different intensity.