High-rate biohydrogen production from xylose using a dynamic membrane bioreactor

This study aimed a high-rate dark fermentative H₂ production from xylose using a dynamic membrane module bioreactor (DMBR) with a 444-μm pore polyester mesh. 20 g xylose/L was fed continuously to the DMBR at different hydraulic retention times (HRTs) from 12 to 3 h at 37 °C. The maximum average H₂ yield (HY) and H₂ production rate (HPR) at 3 h HRT were found to be 1.40 ± 0.07 mol H₂/mol xylose_consumed and 30.26 ± 1.19 L H₂/L-d, respectively. The short HRT resulted in the maximum suspended biomass concentration (8.92 ± 0.40 g VSS/L) along with significant attached biomass retention (7.88 ± 0.22 g VSS/L). H₂ was produced by both butyric and acetic acid pathways. Low HY was concurrent with lactic acid production. The bacterial population shifted from non-H₂ producers, such as Lactobacillus and Sporolactobacillus spp., to Clostridium sp., when HY increased. Thus, xylose from lignocellulose is a feasible substrate for dark fermentative H₂ production using DMBR.