Biomass pretreatment often leads to the formation of compounds that are inhibitory to enzymatic hydrolysis. To remove inhibitory compounds prior to enzymatic hydrolysis, pretreated biomass is washed with at least 3 volumes of water. However, this washing step would be difficult to manage in commercial operations because of the unsustainable water consumption. This study reports on the effects of formic acid and furfural on Accellerase 1500 with cellulose powder and dilute acid-pretreated poplar as substrates. Using cellulose powder as the substrate for enzymatic hydrolysis with the addition of 5 or 10 mg/mL formic acid, glucose recovery was reduced by 34% and 81%, respectively, in comparison to the control. The addition of furfural, at 2 or 5 mg/mL, to the enzymatic system reduced glucose recovery by 5% and 9%, respectively. When 5 mg/mL of formic acid was combined with 5 mg/mL of furfural, glucose recovery in the cellulose powder enzymatic system was reduced by 59%. Inhibition of sugar recovery was more pronounced when dilute acid-pretreated poplar was used as a substrate for enzymatic hydrolysis. At 24 h incubation, recovery reductions were 94%, 97%, and 93% in the presence of 5 or 10 mg/mL formic acid or the 5 mg/mL combination.
In this work, Populus deltoides L. biomass was pretreated in 0.98% (v/v) sulfuric acid at 140 °C for 40 min. Prior to enzymatic hydrolysis, pretreated biomass was either not washed or washed with 1.5 or 3 volumes of water, as compared to biomass. Rinsing the pretreated biomass with 1.5 or 3 volumes of water resulted in glucose yields that were seven times greater than the nonwashed treatment. Pretreatment hydrolyzates, wash waters, and enzymatic hydrolysis hydrolyzates were analyzed for carbohydrate, aliphatic acid, aldehyde, and phenolic content. An analysis of the wash waters showed the presence of gallic, vanillic, syringic, p-coumaric, ferrulic, trans-cinnamic, and salicylic acids at concentrations below 0.07 mg mL −1 . Washed and nonwashed enzymatic hydrolyzates showed significant differences in gallic, vanillic, ferrulic, and salicylic acid concentrations, indicating that these compounds could be in part responsible for inhibiting enzymatic hydrolysis. Nonwashed and washed enzymatic hydrolysates were fermented to ethanol with self-flocculating SPSC01 and nonflocculating ATCC4126 yeasts. While the biomass washed with 3 volumes of water produced the highest ethanol yields (up to 0.43 g g −1 glucose) and were significantly higher than those from the nonwashed sample (≤0.28 g g −1 glucose), the ensuing differences between samples washed with 3 and 1.5 volumes of water were not significant. The SPSC01 strain generally outperformed the ATCC4126 strain in ethanol fermentation efficiency, in particular when the nonwashed hydrolysates were used as feedstock.
Economic contributions of an industry sector are often vital information in the policy-making process. IMPLAN data and software were used to determine the economic contribution of forest industries to all 50 states plus Washington, D.C. Rankings of the states' contributions to employment, employee compensation, and value added were determined. National forest inventory data, rural population, and industrial energy costs were examined for correlation with total forestry contributions to each state's economies. Rankings were based on absolute contributions as well as contributions as a percentage of a state's total economy. Percentage rankings present the relative importance of forestry to a state's economy, and can differ considerably from absolute value rankings. Regional and national contributions were also calculated to model interstate and regional contribution “leakages,” or trade effects. Differences in both interstate and interregional trade flows are substantial. Industrial energy costs, rural population, and timber removals were significantly correlated with total economic contributions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.