2-STEP ACID-HYDROLYSIS PROCESS KINETICS IN THE SACCHARIFICATION OF LOW-GRADE BIOMASS .1. EXPERIMENTAL STUDIES ON THE FORMATION AND DEGRADATION OF SUGARS

Two-step acid hydrolysis studies were performed on various types of lo w-grade biomass, such as bakery waste, grain dust wood chips and wheat straw These wastes contain predominantly starch, cellulose, hemicellu lose, or combinations of these carbohydrates. The hydrolysis condition s for each step were determined by using pure starch and cellulose as substrates. Starch and hemicellulose were hydrolyzed at 132 degrees C for 40 min using 2% H2SO4 Cellulose was hydrolyzed at 132 degrees C fo r 70 min using 15% H2SO4 Dilute acid hydrolysis of bakery waste provid ed 92% conversion to glucose with no xylose in the hydrolyzate. In the case of wood chips, grain dust and wheat straw, substantial quantitie s of xylose were obtained at the end of the second hydrolysis step. Ba kery waste has good potential for use as a feedstock for the productio n of chemicals due to the high yield of almost 80 g glucose/100 g subs trate. Twostep hydrolysis gave 40-50 g of total sugars/100 g of substr ates in the case of wood chips, grain dust and wheat straw. The observ ed trends for starch and cellulose hydrolysis indicate that the conver sion of biomass to sugars can be maximized by using a two-step hydroly sis process. Copyright (C) 1997 Elsevier Science Ltd.