PRETREATMENT OF WHEAT-STRAW USING COMBINED WET OXIDATION AND ALKALINE-HYDROLYSIS RESULTING IN CONVERTIBLE CELLULOSE AND HEMICELLULOSE

The wet oxidation process of wheat straw has been studied as a pretrea tment method to attain our main goal: To break down cellulose to gluco se enzymatic, and secondly, to dissolve hemicellulose (e.g., for ferme ntation) without producing microbial inhibitors. Wet oxidation combine d with base addition readily oxidizes lignin from wheat straw facilita ting the polysaccharides for enzymatic hy drolysis. By using a special ly constructed autoclave system, the wet oxidation process was optimiz ed with respect to both reaction time and temperature. The best condit ions (20 g/L straw, 170 degrees C, 5 to 10 min) gave about 85% w/w yie ld of converting cellulose to glucose. The process water, containing d issolved hemicellulose and carboxylic acids, has proven to be a direct nutrient source for the fungus Aspergillus niger producing exo-beta-x ylosidase. Furfural and hydroxymethyl-furfural, known inhibitors of mi crobial growth when other pretreatment systems have been applied, were not observed following the wet oxidation treatment. (C) 1996 John Wil ey & Sons, Inc.