Effect of inoculation ratio for methane potential of food waste on mesotherm anaerobic digestion

With inoculation ratio as a parameter for the organic loading rate of food waste anaerobic digestion, the purpose of this study was to research the effect of different inoculation ratios of food waste on methane potential from mesothermal anaerobic digestion on a batch scale and to determine the optimal inoculation ratio of food waste for mesothermal anaerobic digestion. In this study, the inoculation ratios of 10%, 15%, 20%, 25%, 30%, and 35% were adopted, and the differences in biogas production, methane content, total solids (TS), volatile solids (VS), and volatile fatty acids (VFAs) were analyzed among the different inoculation ratios. The results showed that all these fermentation tanks stopped producing gas after 6 days and the 35% inoculation ratio led to system acidization. When the inoculation ratio was 30% or 25%, the concentration of VFAs was stable at high levels, and there were high residual VFAs at the end of the test. This means that although the reaction could operate theoretically, the VFAs generated from acidization were not used efficiently to produce biogas. When the inoculation ratio was 10%, 20%, and 30%, the VFAs from acidization were used efficiently. Maximum biogas production occurred when the inoculation ratio was 20%, with a methane content of 52.88% and removal rates of TS and VS of 32.11% and 38.24%, respectively. Therefore, the 20% inoculation ratio was deemed the most suitable from the batch and continuous tests.