title: Potential of agricultural residues and hay for bioethanol production.
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 degrees 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(R) 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.
authors.affiliation: Department of Biological and Agricultural Engineering, North Carolina State University, Campus Box 7625, Raleigh, NC 27695-7625, USA.
authors.forename: Ye
authors.initials: Y
authors.lastname: Chen
authors.forename: Ratna R
authors.initials: RR
authors.lastname: Sharma-Shivappa
authors.forename: Deepak
authors.initials: D
authors.lastname: Keshwani
authors.forename: Chengci
authors.initials: C
authors.lastname: Chen
mesh_terms: D001709:Biotechnology / Q000379:methods*; D018556:Crops, Agricultural / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005936:Glucans / Q000378:metabolism; D006868:Hydrolysis; D008031:Lignin / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D014990:Xylans / Q000378:metabolism
chemical_list: D005936:Glucans; D014990:Xylans; D000431:Ethanol; D008031:Lignin