PNNL

Abstract

Biomass ash was added during pretreatment and enzymatic hydrolysis to examine its influence on biochemical processes for producing fermentable sugars. Corn stover was pretreated using hot water, dilute acid, alkaline, ?-valerolactone, and ionic liquid methods, each examined with ash loadings of 8.26% and 13.21%. The results indicated that the total sugar yield was 3% - 15% lower at the higher ash content for all pretreatments, and up to 6.7% lower during the subsequent enzymatic hydrolysis. Acidic pretreatments were particularly negatively affected by the ash content. The primary causes for the reduced sugar yield in higher-ash biomass during acidic pretreatments were likely the neutralizing effect of the ash and reduced acid access to the substrates. During enzymatic hydrolysis, ash decreased the sugar yield by limiting enzyme access to cellulose. Alkaline pretreatment showed less impact from ash.