Effect of inoculum VS, organic loads and I/S on the biochemical methane potential of sludge, buckwheat husk and straw

Abstract

This study aims to evaluate the influence of inoculum volatile solids (VS), organic loads and I/S ratios on methane production from anaerobic co-digestion of sludge (PS), straw (WS) and buckwheat husk (BH). Biochemical methane potential (BMP) tests were conducted in 500 mL digesters under mesophilic conditions. For this paper, two experiments were carried out: in the first experiment, five mixtures of PS, WS and BH were tested depending on their I/S ratios, to investigate the optimum mixture for effective methane production. The highest CH4 yield was recorded at an I/S ratio of 3, which showed an increase of 1.06–1.74 times more than the other I/S ratios. In the second experiment, six amounts of PS, WS and BH at different inoculum VS organic loads were used to investigate the best VS organic loads for optimum gas generation. The highest methane (CH4) yield was recorded at an organic load of 15 g VS/L, which showed higher CH4 yields of 1.20–1.58 times more than other organic loads, while the lowest CH4 yield was obtained at an organic load of 10 g VS/L. The results were obtained using a statistical analysis test. The VS removal rate and pH were evaluated. The results indicated the positive effect that inoculum VS organic loads and I/S ratios have on improving CH4 production.