Effect of substrate ratio on biogas yield for anaerobic co-digestion of fruit vegetable waste & sugarcane bagasse

Abstract

Abstract The present study investigates the influence of mixture of waste activated sludge (WAS) as inoculum (I) to the ratio of sugarcane bagasse (SB) and fruit-vegetable waste (FVW) as substrate (S) on biogas yield during anaerobic co-digestion. The lignin content of SB is very high, limiting its application for anaerobic digestion; therefore, FVW was used at varied ratio as substrate. Batch studies were conducted under ambient conditions in 500 mL glass bottles for 30 d at five different mixtures ratio of SB: FVW (100:0, 70:30, 50:50, 30:70 and 0:100) at different organic loading rate (OLR) varied from 0.85–2.4 g VS L−1 d−1 and at fixed Inoculum/Substrate (I/S) ratio of 1. Results demonstrate that the maximum biogas yield of 2600 mL d − 1 was observed at substrate (SB: FVW) ratio of 30:70 with I/S ratio ≈ 1.0. An increment of 79, 58 and 56% in biogas generation at 70:30, 50:50 and 30:70 mixture ratio of SB: FVW was observed compared to the mono anaerobic digestion of SB. The experimental data was validated with modified Gompertz equation and first order model and fits well. The kinetic coefficients determined at optimum ratio of 70:30 from Gompertz model were well supported the experimental data.