Effect of lignin-derived and furan compounds found in lignocellulosic hydrolysates on biomethane production

► Anaerobic digestion of xylose in presence of pretreatment byproducts was studied. ► Neither phenolic and furan compounds nor lignin polymers inhibited anaerobic digestion. ► Byproducts and natural and synthetic lignin polymers took place in the methane production. ► Higher S/G ratios and lower molecular weights in lignin led to greater methane production. Hydrolysates resulting from the lignocellulosic biomass pretreatment in bioethanol production may be used to produce biogas. Such hydrolysates are rich in xylose but also contain lignin polymers or oligomers as well as phenolic and furan compounds, such as syringaldehyde, vanillin, HMF, furfural. The aim of this study was to investigate the impact of these byproducts on biomethane production from xylose. The anaerobic digestion of the byproducts alone was also investigated. No inhibition of the anaerobic digestion of xylose was observed and methane was obtained from furans: 430mLCH4/g of furfural and 450mLCH4/g of HMF; from phenolic compounds: 453mLCH4/g of syringaldehyde and 105mLCH4/g of vanillin; and, to a lesser extent, from lignin polymers: from 14 to 46mLCH4/gMV. The use of different natural polymers (lignosulfonates, organosolv and kraft lignins) and synthetic dehydrogenative polymers showed that higher S/G ratios and lower molecular weights in lignin polymers led to greater methane production.