Anaerobic Codigestion of Kitchen Waste with Cattle Manure for Biogas Production

Kitchen waste (KW), cattle manure (CM), and the mixture of KW and CM were anaerobically digested. The performances of single digestion with KW or CM and of codigestion with KW and CM were investigated and compared. Two loading rates of 10 and 20 g volatile solid (VS) L-1 were used for KW, CM, and their mixture digestion, respectively. NaOH was used as supplementary for KW, and sulfuric acid pretreatment was used for CM to explore the effects of alkalinity and acidification on methane production to verify the roles of codigestion. Scanning electron microscopy (SEM) was used to analyze the structural changes of CM fibers. The results showed that the codigestion of KW and CM increased methane yield by 44% as compared to the single digestion of KW, and the increase could be attributed to the synergistic effect in the codigestion process. A 32% more methane yield was achieved for the KW with NaOH addition than raw KW, which was due to increased alkalinity and buffering capacity. The methane yield and VS reduction for acid-pretreated CM were 116 and 74% higher than raw CM. SEM analysis showed that the structural changes of CM fibers were helpful for methane production. The results showed that codigestion could obtain better and stable performances and might be one of many options for efficient biogas production.