Conversion of Lignocellulosics Pretreated With Liquid Hot Water to Ethanol

Lignocellulosic materials pretreated using liquid hot water (LHW) (220°C, 5 MPa, 120 s) were fermented to ethanol by batch simultaneous saccharification and fermentation (SSF) using Saccharomyces cerevisiae in the presence of Trichoderma reesei cellulase. SSF of sugarcane bagasse (as received), aspen chips (smallest dimension 3mm), and mixed hardwood flour (-60 +70mesh) resulted in 90% conversion to ethanol in 2-5 d at enzyme loadings of 15-30 FPU/ g. In most cases, 90% of the final conversion was achieved within 75 h of inoculation. Comminution of the pretreated substrates did not affect the conversion to ethanol. The hydrolysate produced from the LHW pretreatment showed slight inhibition of batch growth of S. cerevisiae. Solids pretreated at a concentration oflOOgiLwere as reactive as those pretreated at a lower concentration, provided that the temperaturewas maintained at 220°C. Index Entries: Liquid hot water; pretreatment; SSF; inhibition; particle size reduction.