Effect of microwave treatment on maximizing biogas yield for anaerobic co-digestion of fruit and vegetable waste and anaerobic sludge

Treatment of organic waste has gain importance in the last decade due to stringent environmental laws. Fruit and vegetable waste (FVW) is potent substrate to be utilized for the recover energy via anaerobic digestion, a sustainable approach for the waste to energy transformation. Co-digestion of FVW and anaerobic sludge (AS) was explored in batch anaerobic digestion for a retention time of 31 days. Mixing ratio of (AS:FVW) 25:75 claimed 22% and 43% higher biogas yield as compared to 50:50 and 75: 25 ratio, respectively. Highest methane yield of 62% which is equivalent to 275.9 NmL/g VS was observed for (AS:FVW) 25:75 ratio. Further, application of microwave (MW) treatment enhanced the solubilization of the feedstock and rendered 10% higher methane yield as compared to untreated (AS:FVW) 25:75 ratio at operating power of 300W. Performance analysis indicated highest VS reduction of 77% for MW-treated FVW at optimal ratio of FVW and AS. Kinetic modelling was done, and experimental data fits well to the first-order model as compared to modified Gompertz model. Rate constant at optimal ratio with microwave pre-treatment was found to be 0.111, while the value for untreated optimal ratio was found as 0.1085.