Effect of organic loading rate on continuous hydrogen production from food waste in submerged anaerobic membrane bioreactor

•H2 production by MBR from food waste was successfully achieved with CH4-free.•The H2 production was improved by shortening the HRTs and increasing the OLRs.•MBR had a higher degradation potential and H2 production from of food waste.•The microbial community in the MBR was dominated by Clostridium sp. strain Z6.

The characteristics of hydrogen fermentation in a membrane bioreactor (HF-MBR) fed with food waste were investigated at thermophilic condition. The HF-MBR was operated at three different organic loading rates (OLRs) of 70.2, 89.4 and 125.4 kg-COD/m3/day. Biogas production rate increased from 22.4 to 32.8 and 62.5 l/day with OLR. The maximum Hydrogen yield and production rate were 111.1 mL-H2/g-VS added and 10.7 l-H2/L/day at an OLR of 125.4 kg-COD/m3/day. The total carbohydrate degradation was better than 96% throughout the experimental runs. Continuous H2 production from food waste with CH4-free biogas was successfully sustained in the HF-MBR for 90 days. The microbial community was dominated by Clostridium sp. strain Z6. The H2 production was significantly improved by shortening the retention time and increasing the OLRs. The HF-MBR showed an H2 production capacity at the high OLRs due to its higher cell retention.