Anaerobic digestion of activated sludge, anaerobic granular sludge and cow dung with food waste for enhanced methane production

Abstract

The effect of inoculum [cow dung (CD), acclimatized anaerobic granular sludge (AAGS) and waste activated sludge (WAS)] on co-digestion of food waste (FW) was investigated in this study. Seven batch reactors were prepared using the different combinations of FW and inoculums and methane (CH4) generation was monitored for 30 d. Results suggested that inoculum type and combination cause significant effect on biomethanation process. The reactor with CD: AAGS: WAS: FW in 1:1:1:1 ratio showed the maximum CH4 generation (109 mL CH4 g−1 VS removed). There was reduction in volatile solids (VS) (16.24–56.58%) and soluble chemical oxygen demand (SCOD) (20.54–66.24%) during the AD process in all batch reactors. The results suggested that type and combination of inocula with FW was the prime factor in improving the co-digestion process. A combination of AAGS, CD and WAS with FW (1:1:1:1) appeared as the best co-digestion inocula for enhanced biomethanation process. Experimental results fits well with Gompertz and first order (FO) model for all waste combinations.