Effects of 5-hydromethylfurfural, levulinic acid and formic acid, pretreatment byproducts of biomass, on fermentative H2 production from glucose and galactose

•H2 fermentation has been significantly influenced by the pretreatment byproducts.•The half maximal inhibitory concentrations have been determined.•Decreased H2 production was concurrent with lactic and propionic acids production.

In this study, the effects of 5-hydromethylfurfural (5-HMF), levulinic acid, and formic acid on fermentative H2 production have been investigated. The major byproducts of physicochemical pretreatment of lignocellulosic or algal biomass inhibited H2 production from glucose and galactose. The half maximal inhibitory concentrations (IC50) of 5-HMF on glucose, levulinic acid on glucose, formic acid on glucose, levulinic acid on galactose and formic acid on galactose were 0.59, 1.55, 12.50, 1.33 and 2.99 g/L, respectively. The pretreatment byproducts levels should be mitigated by controlling the severity of a physicochemical treatment or an additional selective removal process prior to H2 fermentation.