Abstract: The effects of water-washing on inhibitors removal, enzymatic hydrolysis and fermentation of acid steam-exploded corn stover were investigated. The results revealed that the washing process (solid-to-liquid ratio of 1:7.5, room temperature) removed more than 50% of the carbohydrate degradation products and more than 70% of lignin degradation products. The washing process obviously enhanced the fermentability of the concentrated enzymatic hydrolysate and decreased yeast inoculum in fermentation. The concentrated hydrolysate containing 170.69 g/L glucose, which was hydrolyzed, solid-liquid separation and concentrated from washing pretreated corn stover at solid-to-liquid ratio of 1:7.5(g:mL), was fermented by Saccharomyces cerevisiae with a low initial yeast inoculation of OD₆₀₀ 3.84 for 48 h. 80.67 g/L ethanol and 93.66% of ethanol yield were obtained, respectively. The corresponding ethanol production was 173.00 g based on 1 000 g dry pretreated corn stover. The whole enzymatic hydrolysate of the washed substrate at a substrate loading of 350 g/L with a yeast inoculum of 1.0×10⁷ cfu/mL hydrolysate was fermented for 48 h. 54.50 g/L ethanol was formed from 106.64 g/L glucose, and the corresponding ethanol production was 162.17 g based on 1 000 g pretreated dry corn stover.

Key words: washing, acid steam explosion, corn stover, ethanol