Biological Systems Engineering
Date of this Version
4-2007
Abstract
Production of bioethanol from agricultural residues and hays (wheat, barley, and triticale straws, and barley, triticale, pearl millet, and sweet sorghum hays) through a series of chemical pretreatment, enzymatic hydrolysis, and fermentation processes was investigated in this study. Composition analysis suggested that the agricultural straws and hays studied contained approximately 28.62–38.58% glucan, 11.19–20.78% xylan, and 22.01–27.57% lignin, making them good candidates for bioethanol production. Chemical pretreatment with sulfuric acid or sodium hydroxide at concentrations of 0.5, 1.0, and 2.0% indicated that concentration and treatment agent play a significant role during pretreatment. After 2.0% sulfuric acid pretreatment at 121°C/15 psi for 60 min, 78.10–81.27% of the xylan in untreated feedstocks was solubilized, while 75.09–84.52% of the lignin was reduced after 2.0% sodium hydroxide pretreatment under similar conditions. Enzymatic hydrolysis of chemically pretreated (2.0% NaOH or H2SO4) solids with Celluclast 1.5 L–Novozym 188 (cellobiase) enzyme combination resulted in equal or higher glucan and xylan conversion than with Spezyme® CP- xylanase combination. The glucan and xylan conversions during hydrolysis with Celluclast 1.5 L–cellobiase at 40 FPU/g glucan were 78.09 to 100.36% and 74.03 to 84.89%, respectively. Increasing the enzyme loading from 40 to 60 FPU/g glucan did not significantly increase sugar yield. The ethanol yield after fermentation of the hydrolyzate from different feedstocks with Saccharomyces cerevisiae ranged from 0.27 to 0.34 g/g glucose or 52.00–65.82% of the theoretical maximum ethanol yield.
Comments
Published in Applied Biochemistry and Biotechnology Part A: Enzyme Engineering and Biotechnology 142 (2007), pp. 276–290; doi: 10.1007/s12010-007-0026-3 Copyright © 2007 Humana Press Inc. (Springer Verlag). Used by permission. http://www.springerlink.com/content/a2542710357w3u12