Performance of AnMBR for the co-digestion of food waste and waste activity sludge

Continuous experiments and activity experiments were conducted to systematically explore the effect of anaerobic membrane bioreactor (AnMBR) on the efficiency, stability, and kinetic characteristics of the treatment of food waste and waste activated sludge under different organic loading rates (OLRs). The results indicated that AnMBR can operate stably under various working conditions (OLR: 3.22~12.92gCOD/(L•d)). When the OLR was 6.48gCOD/(L•d), the methane production was (4335±2)mL/d, the methane yield (calculated as COD) was (361.2±0.2)mLCH4/gCODremoval, the COD removal efficiency was maintained at (98.6±0.9)%, and the pH was stable at 7.71±0.03. When the OLR exceeded 12.92gCOD/(L•d), the volatile fatty acid in the reactor reached 6108mg COD/L. Membrane fouling was dominated by cake layer fouling. High-throughput sequencing was used to characterize the evolution of microorganisms in the system. Levilinea was the dominant genus of bacteria, and its relative abundance was highest (20.1%) when the OLR was 6.48gCOD/(L•d). Methanosarcina was the dominant genus of archaea, and its relative abundance was maintained above 67% as the OLR increased. Specific methanogenic activity experiments showed that with the increase of OLR, the ability of methanogens to degrade acetic acid continues to increase.. The results of this research provide useful information for the selection of optimal working conditions of AnMBR treatment for the co-digestion of food waste and waste activated sludge. © 2021, Editorial Board of China Environmental Science. All right reserved.