Evaluation of hydrogen and methane production from sugarcane bagasse hemicellulose hydrolysates by two-stage anaerobic digestion process

[Display omitted] •Hemicellulose hydrolysates (HH) were generated by autohydrolysis (AH) of bagasse.•Two-stage anaerobic digestion (2S-AD) was used for H2/CH4 production from HH.•Acidogenic stage detoxified the HH and increased methane production by 4-fold.•2S-AD allowed using more severe AH pretreatment conditions for H2/CH4 production.•Net energy generated from 2S-AD of HH was 3.15MJ·kgbagasse−1dry weight. This study aimed at optimizing the net energy recovery from hydrogen and methane production through anaerobic digestion of the hemicellulose hydrolysate (HH) obtained by desirable conditions (DC) of autohydrolysis pretreatment (AH) of sugarcane bagasse (SB). Anaerobic digestion was carried out in a two-stage (acidogenic-methanogenic) batch system where the acidogenic phase worked as a hydrolysis and biodetoxification step. This allowed the utilization of more severe AH pretreatment conditions, i.e. T=178.6°C and t=55min (DC3) and T=182.9°C and t=40.71min (DC4). Such severe conditions resulted in higher extraction of hemicelluloses from SB (DC1=68.07%, DC2=48.99%, DC3=77.40% and DC4=73.90%), which consequently improved the net energy balance of the proposed process. The estimated energy from the combustion of both biogases (H2 and CH4) accumulated during the two-stage anaerobic digestion of HH generated by DC4 condition was capable of producing a net energy of 3.15MJ·kgSB−1dry weight.