Feedstock mixture effects on sugar monomer recovery following dilute acid pretreatment and enzymatic hydrolysis

This study seeks to investigate the effects of biomass mixtures on overall sugar recovery from the combined processes of dilute acid pretreatment and enzymatic hydrolysis. Aspen, a hardwood species well suited to biochemical processing, was chosen as the model species for this study. Balsam, a high-lignin softwood species, and switchgrass, an herbaceous energy crop with high ash content, were chosen as adjuncts. A matrix of three different dilute acid pretreatment severities and three different enzyme loading levels was used to characterize interactions between pretreatment and enzymatic hydrolysis. No synergism or antagonism was observed for any of the feedstock mixtures. Maximum glucose yield was 70% of theoretical for switchgrass and maximum xylose yield was 99.7% of theoretical for aspen. Supplemental β-glucosidase increased glucose yield from enzymatic hydrolysis by an average of 15%. Total sugar recoveries for mixtures could be predicted to within 4% by linear interpolation of the pure species results.