Novel dynamic membrane, metabolic flux balance and PICRUSt analysis for high-rate biohydrogen production at various substrate concentrations

This research aimed to implement high-rate biohydrogen production using dynamic membrane at various substrate concentrations. Two identical dynamic membrane bioreactors (DMBRs) on the laboratory scale were equipped with polyester mesh of 444-μm pore size. The DMBRs were continuously fed with glucose as a model substrate at 15, 20, and 25 g/L at hydraulic retention times (HRTs) of 2 h and 3 h. The DMBR enabled high-rate hydrogen production at both HRTs in long-term operation without backwashing. The peak average H₂ production rate (HPR) and H₂ yield (HY) per glucose_consumed was 58.86 ± 0.73 L/L-d and 2.00 ± 0.04 mol H₂/mol glucose_consumed, respectively, with a feed glucose concentration of 20 g/L at 2 h HRT. At 3 h HRT, the highest HPR and HY were 29.81 ± 1.01 L/L-d and 1.53 ± 0.05 mol H₂/mol glucose_consumed with a feed glucose concentration of 20 g/L, respectively. HPR and HY were decreased in other feed concentration (15 g/L and 25 g/L) at each HRT, which was concomitant with metabolic flux shifted to lactic acid production and homoacetogenesis. Additionally, substrate consumption efficiency decreased at a feed concentration of 25 g/L. The microbial population at 20 g/L was dominated by Clostridium sp. and lactic acid bacteria. PICRUSt bioinformatics predicted the highest ferredoxin hydrogenase expression and LDH expression of Clostridium sp.