Pretreatment and Fractionation of Wheat Straw for Production of Fuel Ethanol and Value-added Co-products in a Biorefinery

X. Zhang, N.P. Nghiem
USDA ARS Eastern Regional Research Center, US

Keywords: lignocellulosic biomass, fuel ethanol, value-added products, fermentation

Summary:

Wheat straw was used to demonstrate a process for production of ethanol and value-added co-products. The pretreatment of wheat straw was carried out using the soaking in aqueous ammonia (SAA) process. The pretreated wheat straw was first hydrolyzed with Multifect Xylanase (a commercial hemicellulase product) to generate a xylose-rich solution with about 95 % of the glucan being left intact. The xylose-rich solution was used for production of value-added products using selected microorganisms. The resulted cellulose-enriched solid residue was used for ethanol production in a fed-batch simultaneous saccharification and fermentation (SSF) using Accellerase® 1500 (a commercial cellulase product) and the industrial yeast Saccharomyces cerevisiae. At the end of the fermentation final ethanol concentrations above 50 g/l were routinely obtained. Highlights: 1. A process for production of ethanol and value-added co-products from lignocellulosic feedstock. 2. Pretreated wheat straw was hydrolyzed with commercial hemicellulase to generate xylose-rich stream for use in production of value-added products, leaving most of the glucan intact. 3. The resulted cellulose-enriched residue was used in a fed-batch SSF with a commercial cellulase and Saccharomyces cerevisiae to produce ethanol above 50 g/L.