High-rate continuous biohydrogen (Bio-H 2 ) production from rice straw hydrolysate using a dynamic membrane bioreactor (DMBR)

This study reports a successful continuous biohydrogen production from rice straw hydrolysate in both 3-L and 20-L dynamic membrane bioreactor (DMBR). In the 3-L DMBR (DMBR I), the maximum average bio-H 2 production performance was 32.13 +/- 0.71 L H 2 /L-d, 1.27 +/- 0.03 mol H 2 /mol hexose-equiv consumed , and 96.39 +/- 2.12 L H 2 /d, respectively. The H 2 production performance of 20-L DMBR (DMBR II) was comparable to DMBR I, which were 33.15 +/- 0.42 L H 2 /L-d, 1.46 +/- 0.03 mol H 2 /mol hexose-equiv consumed , and 663 +/- 8 L H 2 /d, respectively. Rapid decline of hydraulic retention time (HRT) in the early stages of operation led to the metabolic flux of the mixed culture from the lactic acid pathway to the H 2 -producing pathway. Genus Clostridium was the dominant microbial population in DMBR I and DMBR II. This study provides operational criteria and insights in the scale -up design and operation of biohydrogen production from lignocellulosic biomass.