HRT control as a strategy to enhance continuous hydrogen production from sugarcane juice under mesophilic and thermophilic conditions in AFBRs

The objective of this study was to evaluate the effects of hydraulic retention time (HRT) (8 -1 h) on H-2 production from sugarcane juice (5000 mg COD L-1) in mesophilic (30 degrees C, AFBR-30) and thermophilic (55 degrees C, AFBR-55) anaerobic fluidized bed reactors (AFBRs). At HRTs of 8 and 1 h in AFBR-30, the H-2 production rates were 60 and 116 mL H-2 h(-1) L-1, the hydrogen yields were 0.60 and 0.10 mol H-2 mol(-1) hexose, and the highest bacterial diversities were 2.47 and 2.34, respectively. In AFBR-55, the decrease in the HRT from 8 to 1 h increased the hydrogen production rate to 501 mL H-2 h(-1) L-1 at the HRT of 1 h. The maximum hydrogen yield of 1.52 mol H-2 mol(-1) hexose was observed at the HRT of 2 h and was associated with the lowest bacterial diversity (0.92) and highest bacterial dominance (0.52). (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.