Synergistic effect and biodegradation kinetics of sewage sludge and food waste mesophilic anaerobic co-digestion and the underlying stimulation mechanisms

Anaerobic co-digestion has attracted much attention due to its unique advantages compared with the anaerobic mono-digestion. In this work, the synergistic effect and biodegradation kinetics of sewage sludge (SS)and food waste (FW)were studied during anaerobic co-digestion. Biochemical methane potential (BMP)assay and three kinetic models were used to detect and analyze methane production potential during co-digestion under different ratios of SS and FW. The SS:FW ratios of 0.5:0.5 showed very high methane recovery, with the methane productivity increasing by 4.59 times (50.30 ± 10.37 mL/g-VS/day), the lag-phase shortening by 11.53 times (0.182 day)and the hydrolysis rate increasing by 3.88 times (0.334/day)compared with the SS mono-digestion. Moreover, correlation model parameter analysis indicated the Cone model has the best fitness to the experimental data. These results confirmed the superiority of co-digestion and the existence of synergy, which can greatly accelerate the biodegradation process and more effectively recover bioenergy.