Fig. 6

Ethanol fermentation of glycerol organosolv-pretreated (220 °C, 2 h) sugarcane bagasse at an initial solid content of 15 % (w/v). The enzyme loading of cellulase Cellic CTec2 was 10, 20, and 30 FPU/g dried substrate. For the SSF, the fermentation (initial pH 4.8, inoculation size 10 %, and shaking speed 120 r/min) was carried out at 37 °C for 72 h. For the semi-SSF and fed-batch semi-SSF, the prehydrolysis was made at 50 °C for 24 h. For the fed-batch semi-SSF, the other part of dried pretreated substrate (as much as total dried substrate used for the prehydrolysis) was divided into three aliquots and fed simultaneously with some corresponding cellulase enzymes into the fermenter after 8, 24, and 36 h of fermentation to ensure an equivalent 30 % (w/v) solid content