Effect of pelleting on the recalcitrance and bioconversion of dilute-acid pretreated corn stover under low- and high-solids conditions

Knowledge regarding the performance of densified biomass in biochemical processes is limited. The effects of densification on biochemical conversion are explored here. Results: Pelleted corn stover samples were generated from bales that were milled to 6.35 mm. Low-solids acid pretreatment and simultaneous saccharification and fermentation were performed for pelleted and ground stover ( 6.35 and 2 mm) formats. Monomeric xylose yields were significantly higher for pellets (similar to 60%) than for ground formats (similar to 38%). Pellets achieved approximately 84% of theoretical ethanol yield; ground stover formats had similar profiles, reaching approximately 68% theoretical ethanol yield. Pelleted and 6.35-mm ground stover were evaluated using a ZipperClave (R) reactor under high-solids,process-relevant conditions for multiple pretreatment severities (R-o); feedstock reactivity increased slightly following combined pretreatment and enzymatic hydrolysis for three of five severities tested. Conclusion: Pelleting did not render corn stover more recalcitrant to dilute-acid pretreatment under low-or high-solids conditions, and even enhanced ethanol yields.