Depth-resolved microbial community analyses in the anaerobic co-digester of dewatered sewage sludge with food waste

This study evaluated the impacts of FW addition on co-digestion in terms of microbial community. Anaerobic co-digestion (AcoD) reactors were conducted at gradually increased addition of food waste (FW) from 0 to 4kg-VSm^-3d^-1 for 220days. Although no markable acidification was found at an OLR of 4kg-VSm^-3d^-1, the unhealthy operation was observed in aspect of an inhibited methane yield (185mLg^-1VS_added), which was restricted by 40% when compared with its peak value. Deterioration of digestion process was timely indicated by the dramatic decrease of archaeal population and microbial biodiversity. Furthermore, the cooperation network showed a considerable number of rare species (<1%) were strongly correlated with methane production, which were frequently overlooked due to the limits of detecting resolution or analysis methods before. Advances in the analysis of sensitive microbial community enable us to detect the early disturbances in AcoD reactors.