THE EFFECT OF WATER-SOLUBLE INHIBITORS FROM STEAM-PRETREATED WILLOW ON ENZYMATIC-HYDROLYSIS AND ETHANOL FERMENTATION

In the process of producing ethanol from lignocellulosic materials, co mpounds inhibitory to enzymatic hydrolysis and fermentation are genera ted during the pretreatment of the wood. In an industrial process, the se compounds will accumulate due to the recirculation of process strea ms. The inhibitory effects of the accumulation of volatile and nonvola tile compounds released during stream pretreatment on enzymatic hydrol ysis and fermentation were studied. The volatile compounds did not aff ect either the enzymatic hydrolysis or the fermentation significantly even at high concentrations. In contrast, the nonvolatile compounds se verely affected both the hydrolysis and the fermentation: the effect w as more pronounced in the latter case. For the effective use of a lign ocellulosic material as a substrate for ethanol production, the nonvol atile compounds must thus be removed.