Anaerobic Co-Digestion of Sugarcane Leaves, Cow Dung, and Food Waste: Focus on Methane Yield and Synergistic Effects

Anaerobic co-digestion (AcoD) of food waste (FW) and lignocellulose waste for methane production is a promising technology. This work investigated the methane generation from AcoD of FW, sugarcane leaves (SL), and cow dung (CD) under mesophilic condition in a batch test. As for AcoD of two feedstocks (SL and FW or CD and FW), introduction of SL and CD (25%, volatile solid (VS) basis) showed slight improvement in methane production from FW. In contrast, positive synergistic effect (synergy index=1.03–1.14>1) was observed in all the AcoD reactors of the three feedstocks (SL, CD, and FW). The optimum mixing ratio of FW:SL:CD (VS basis) was 85:11.25:3.75 with a synergy index of 1.07, achieving a methane yield rate and methane content of 297.16 mL/g VS and 73.26%, respectively. This methane production rate was 110.45% and 444.72% higher than mono-digestion of SL and CD. The biodegradability, soluble chemical oxygen demand (SCOD), and VS removal rate are 56.44%, 44.55%, and 55.38%, respectively. The optimum results indicate that AcoD of FW, SL, and CD have higher potentials for energy recovery and providing a forceful scientific evidence for their energy utilization.