The impact of furfural concentrations and substrate-to-biomass ratios on biological hydrogen production from synthetic lignocellulosic hydrolysate using mesophilic anaerobic digester sludge

•Enhancements in biohydrogen production at furfural concentrations of up to1 g/L.•Furfural threshold concentration of ⩽1 g/L was established.•A food- to microorganisms ratio of 4 gCOD/gVSS was optimal.•Hydrogen yields correlated linearly with both furfural:sugar and furfural:biomass.•Furfural:sugars exerted a greater effect on H2 inhibition than furfural:biomass.

This study evaluated the impact of furfural (a furan derivative) on hydrogen production rates and yields at initial substrate-to-microorganism ratios (S°/X°) of 4, 2, 1, and 0.5 gCOD/gVSS and furfural concentrations of 4, 2, 1, and 0.5 g/L. Fermentation studies were carried out in batches using synthetic lignocellulosic hydrolysate as substrate and mesophilic anaerobic digester sludge as seed. Contrary to other literature studies where furfural was inhibitory, this study showed that furfural concentrations of up to 1 g/L enhanced hydrogen production with yields as high as 19% from the control (batch without furfural). Plots of hydrogen yields against g furfural/g sugars and hydrogen yields versus g furfural/g biomass showed negative linear correlation indicating that these parameters influence biohydrogen production. Regression analysis indicated that g furfural/g sugarsinitial exerted a greater effect on the degree of inhibition of hydrogen production than g furfural/g VSSfinal.