13-23: Alkaline pre-extraction with AHP post-treatment of corn stover to enhance the digestibility, fermentability, and process economics

In this study, we present a pretreatment approach comparable to alkaline pulping followed by alkaline oxidative delignification optimized for enzymatic digestibility of grasses.  This couples an alkaline pre-extraction of grass lignin and xylan with an oxidative post-treatment of the residual cell wall that makes use of synergies between the two steps to considerably improve the enzymatic digestibility, fermentability, and economics of relative to either as a stand-alone pretreatment.  Specifically, an experimental design was performed investigating the impacts of alkaline pre-extraction conditions, washing efficiency, subsequent H₂O₂ loadings, and enzyme loading on the digestibility corn stover and switchgrass.  The results showed that a very low oxidant loadings (<2.5% w/w) on the alkali pre-extracted biomass were needed to provide substantial digestibility gains and that the hydrolysates were highly fermentable by xylose-fermenting Saccharomyces cerevisiae strain GLBRC-Y73.