Abstract: The liquid hot water pretreatment (LHWP) of waste wheat straw (WWS) and the effect of prewashing on the LHWP were investigated. The pretreated WWS had the highest enzymatic hydrolysis and fermentable sugars production after the pretreatment at 180℃ for 40 min with the solid to liquid ratio of 1:10(g:mL). The corresponding glucan and xylan enzymatic hydrolysis yields were 40.84% and 39.67%, respectively, and the fermentation sugars production was 15.74 g (glucose was 11.68 g and xylose was 4.06 g). The yield of glucan and xylan were 48.98% and 49.06% respectively under the conditions of the cellulase, xylanase and β-glucosidase loadings of 40 FPU/g glucan, 140 U/g xylan and 48 U/g glucan. The key factor of the LHWP of WWS was the acid buffering ability of the absorbable ash in the WWS. Thus, the WWS was first water washed with the dose of 500 mL/g WWS and then was subjected to the LHWP. After prewashing, the enzymatic hydrolysis yields of glucan and xylan were increased from 48.98% and 49.06% to 65.59% and 70.11%, respectively, with the corresponding glucose and xylose concentrations of 17.50 and 4.75 g/L. Moreover, the prewashing could also lower the enzyme dosages in the enzymatic hydrolysis process.

Key words: waste wheat straw, liquid hot water pretreatment, prewashing, fermentable sugars