Hot Liquid Water Pretreatment of Lignocellulosics at High Solids Concentrations

Abstract

Rapid (120 s), batch, hot-liquid-water pretreatment of biomass (up to 30 g) at high solids concentrations has been studied using feed materials representative of woody and herbaceous species, namely aspen and sugar-cane bagasse. Although the current pretreatment apparatus was not designed to minimize water consumption, a mean reaction temperature of 220 °C was still achieved at solids concentrations of up to 18%. The yield of pretreated biomass was insensitive to the mean reaction temperature over the range studied (205 to 220 °C), but increased slightly with increasing solids concentration (ie. fractionation decreased). A minimum of 10% of the biomass was fractionated into the hydrolyzate at 18% solids. After pretreatment at 9% solids concentration, less than 10% of the hemicellulose content of the feed material remained within the pretreated lignocellulosics. The production of possible inhibitors such as furfural and hydroxymethyl furfural accounted for less than 3% of the original carbohydrates. Initial results indicate that the pretreated biomass can be readily converted to ethanol by SSF. A device capable of pretreating 1 kg of biomass at high solids concentrations is now being designed and constructed.