Optimization of Biogas Production through Selection of Appropriate Inoculum-to-Substrate ((I/S) Ratio

Abstract

The impact of Inoculum-to-Substrate (I/S) ratio on the optimization of biogas yield from the co-digestion of FW and MH was investigated in five anaerobic reactors B-1 to B-5 at 37±1oC. Cumulative biogas yield of digester B-3(28.92 L/gVS) with the I/S ratio 1 was higher than that of the other digesters. Simulation study through adoption of Gompertz model (modified) showed a large reduction in latency (λ) by 59.7% with increase in I/S ratio from 0.25 to 1, which indicates that the time taken for methanogenesis to begin was reduced by over 59%. Increase in I/S ratio had positive effects on maximum specific biogas production (Rm) and maximum biogas production potential (A) with reactor B-3 having the largest (Rm) and (A) values of 1.26 L/gVS/day and 29.58 L/gVS respectively. Lower I/S ratios of 0.25 and 0.5 were found to rather decrease biogas production. Biogas yield at I/S ratios 2 and 4 was lower than the yield at ratio 1.