Comparisons of pretreatment of switchgrass by CELF to that possible by hydrothermal and dilute acid pretreatments

Over the last few decades, numerous concerns, environmental and political, have motivated research into renewable, domestic sources of fuels to replace those derived from petroleum. Lignocellulosic biomass represents the most abundant carbon-neutral renewable resource for biofuels production and provides the only known route to sustainably produce liquid fuels on a large scale and low cost. Due to its recalcitrant nature, raw biomass hinders enzymatic digestion of the cellulose thus necessitating pretreatment to deconstruct the plant structure and allow cellulose to be more accessible for enzymes to release fermentable sugars. Several pretreatment methods, including hydrothermal and dilute acid pretreatments, have been developed but are limited in their ability to break lignin bonds, a key contributor to biomass recalcitrance. Recently, we have developed a new pretreatment method called Co-solvent Enhanced Lignocellulosic Fractionation (CELF) that utilizes aqueous tetrahydrofuran (THF) to effectively remove lignin, while simultaneously achieving high yields of C5 and C6 sugars from hemicellulose and cellulose fractions using very low enzyme loadings [1]. In this study we evaluated the pretreatment of switchgrass using hydrothermal, dilute acid, and CELF in terms of changes in solids compositions, sugar recovery, and the digestibility of the resulting pretreated solids produced over a range of enzyme loadings for each pretreatment.

References:

[1] Nguyen, T.Y., Cai, C.M., Kumar, R., Wyman, C.E. 2014. THF co-solvent pretreatment achieves unprecedented total sugar and ethanol yields from lignocellulosic biomass at low enzyme loadings. submitted.