Enhancement of hydrogen production using untreated inoculum in two-stage food waste digestion

Abstract This research investigated the possibility to enhance H 2 production using untreated inoculum in a two-stage hydrogen-methane process from food waste. Batch experiments were conducted to evaluate the H 2 production efficiency at different F/M ratios (ranging from 1:1 to 64:1). The results showed that when a proper F/M ratio was selected, significant H 2 production was feasible to be achieved even inoculated with untreated anaerobic sludge. Among the F/M ratios studied, maximum H 2 yield (217.98 mL H 2 g VS −1 FW) was found in the digester at the F/M of 64:1, which was 93.75 times higher than that of the digester at the F/M of 1:1. Higher hydrogen yield was achieved at the greater F/M ratio, due to the enrichment of the H 2 producing bacteria and the reduction of the antagonistic bacteria. The two-stage process allowed more stable methane production and higher overall energy yield compared to the single-stage process.