Enhanced continuous biohydrogen production using dynamic membrane with conductive biofilm supporter.

Abstract

The present study investigated the effect of a conductive biofilm supporter on continuous production of biohydrogen in a dynamic membrane bioreactor (DMBR). Two lab-scale DMBRs were operated: one with a nonconductive polyester mesh (DMBR I) and the other with a conductive stainless-steel mesh (DMBR II). The highest average hydrogen productivity and the yield were 16.8% greater in DMBR II than in DMBR I, with values of 51.64 ± 0.66 L/L-d and 2.01 ± 0.03 mol H₂/mol hexose_consumed, respectively. The improved hydrogen production was concurrent with a higher NADH/NAD⁺ ratio and a lower ORP (Oxidation-reduction potential). Metabolic flux analysis implied that the conductive supporter promoted H₂-producing acetogenesis and repressed competitive NADH-consuming pathways, such as homoacetogenesis and lactate production. Microbial community analysis revealed that electroactive Clostridium sp. were the dominant H₂ producers in DMBR II. Conclusively, conductive meshes may be useful as biofilm supporters of dynamic membranes during H₂ production for selectively enhancing H₂-producing pathways.