Enhanced Biogas Production from Co-digestion of Intestine Waste from Slaughterhouse and Food Waste

The presence of higher protein and lipids contents of the intestine waste from slaughterhouse affects the anaerobic digestion (AD) process due to volatile fatty acids accumulation and ammonia toxicity. The aim of the present batch reactor study was to evaluate the effect of the mixing ratio on anaerobic co-digestion of intestine waste from the slaughterhouse (IWS) and carbon-rich food waste (FW) to enhance the biogas production and to optimize the C/N ratio for improving the efficiency and better performance of AD. Biogas productions were estimated for various mixing ratios on volatile solid (VS) basis (IWS/FW: 1:1, 1:2, 1:3, 1:4, and 1:5) keeping the inoculum to substrate ratio maintained at 0.5 as per German method VDI 4630. On the basis of the present study, the biogas productions of different mixing ratios at the end of 30th day were found to be on the order of 0.43 (1:2) > 0.39 (1:3) > 0.38 (1:1) > 0.36 (FW) > 0.35 (1:4 and 1:5) > 0.18 (IWS) L/g of VS added. Similarly, the VS removal efficiencies were on the order of 64.02% (1:2) > 61.28% (1:3) > 60.91% (FW) > 60.34% (1:4) 60.21% > (1:2) > 60.15% (1:1) > 47.69% (IWS). Results of the study reveal that the mixing ratio of 1:2 is found to be the suitable mixing ratio which resulted in enhancement of biogas production by 57% and 17% when compared with IWS and FW alone, respectively. The lowest theoretical retention time of 12 days was observed in the mixing ratio of 1:4 with biogas production of 0.28 L/g of VS added while in the mixing ratio of 1:2, the biogas production of 0.35 L/g of VS added was achieved in 13 days.