Hydrogen production from diluted and raw sugarcane vinasse under thermophilic anaerobic conditions

Two continuous anaerobic fluidized bed reactors (AFBRs) were operated under thermophilic (55 degrees C) temperature for 150 days to investigate the effect of dark H-2 fermentation of diluted and raw sugarcane vinasse on H-2 production using mixed seed sludge. Although effective H-2 production (52.8% of H-2; 0.80 L H-2 h(-1) L-1; 0.79 mmol gCOD(added)(-1) was observed using an elevated substrate concentration (30,000 mg COD L-1), the optimal operational conditions were found for the AFBR(1) (10,000 mg COD L-1) fed with diluted sugarcane vinasse (HRT 6 h; OLR 40 kg COD m(-3) d(-1)), achieving a H-2 yield of 2.86 mmol H-2 g CODadded-1. H-2 production was inhibited by elevated volatile fatty acid (VFA) concentrations (butyric and acetic acids = 3.7 and 3.0 g L-1, respectively) in the raw feedstock. Denaturing gradient gel electrophoresis (DGGE) analyses revealed changes in the bacterial population of the expanded clay biofilm as a function of the substrate concentration. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.