Two-stage dilute-acid pretreatment of softwoods.
Whole tree chips obtained from softwood forest thinnings were pretreated via single- and two-stage dilute-sulfuric acid pretreatment. Whole-tree chips were impregnated with dilute sulfuric acid and steam treated in a 4-L steam explosion reactor. In single-stage pretreatment, wood chips were treated using a wide range of severity. In two-stage pretreatment, the first stage was carried out at low severity to maximize hemicellulose recovery. Solubilized sugars were recovered from the first-stage prehydrolysate by washing with water. In the second stage, water-insoluble solids from first-stage prehydrolysate were impregnated with dilute sulfuric acid, then steam treated at more severe conditions to hydrolyze a portion of the remaining cellulose to glucose and to improve the enzyme digestibility. The total sugar yields obtained after enzymatic hydrolysis of two-stage dilute acid-pretreated samples were compared with sugar yields from single-stage pretreatment. The overall sugar yield from two-stage dilute-acid pretreatment was approx 10% higher, and the net enzyme requirement was reduced by about 50%. Simultaneous saccharification and fermentation using an adapted Saccharomyces cerevisiae yeast strain further improved cellulose conversion yield and lowered the enzyme requirement.
Nguyen
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National Renewable Energy Laboratory, Golden, CO 80401-3393, USA. quang_nguyen@nrel.gov
Tucker
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MP
Keller
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Eddy
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D002480:Cellulase; D002482:Cellulose; D032462:Cycadopsida; D005285:Fermentation; D006868:Hydrolysis; D011134:Polysaccharides; D012441:Saccharomyces cerevisiae / Q000502:physiology; D013227:Steam; D013464:Sulfuric Acids; D014197:Trees; D014934:Wood
D011134:Polysaccharides; D013227:Steam; D013464:Sulfuric Acids; C007916:hemicellulose; D002482:Cellulose; D002480:Cellulase; C033158:sulfuric acid