The High-solids Mesophilic Anaerobic Co-digestion of Food Waste and Sewage Sludge: the Impact of Sewage Sludge Ratio

摘要

System stability and biogas recovery performance of high-solids mesophilic anaerobic co-digestion of food waste (FW) and sewage sludge(SS) were investigated. FW and SS were mixed with ratios of 100:0,75:25, 50:50 and 0:100(based on total solids) and fed into CSTR reactor. The feedstock TS concentration was fixed at about 10% and HRT was set at 30d. Through the long term experiment, it is found that for high-solids digestion of FW, the deficiency of nutrition elements was overcome and then VFA accumulation was avoided by the introduction of SS. For high-solids digestion of SS, the accumulation of ammonia was diluted and volumetric biogas production was enhanced greatly when FW was added. Biogas production and organic removal efficiency declined linearly with the increasing of SS ratio, the VS reduction decreased from 80% to 54%. Furthermore, a stoichiometric model was developed to illustrate the co-digestion, and its liability was dependable and consistent with major fermentation indexes.