Method for the production of a fermentation product from a pretreated lignocellulosic feedstock
First Claim
1. A method for obtaining ethanol from a feedstock comprising hemicellulose, comprising:
- (i) pretreating the feedstock to produce a stream comprising pretreated feedstock;
(ii) optionally removing xylose from the stream produced in step (i);
(iii) hydrolyzing the pretreated feedstock with an enzyme mixture comprising cellulase enzymes and beta-glucosidase to produce a sugar hydrolyzate comprising at least glucose;
(iv) fermenting the sugar hydrolyzate in a fermentation reaction with yeast to produce a fermentation broth comprising ethanol;
(v) withdrawing a slurry comprising yeast during the fermenting step (step iv);
(vi) treating the slurry comprising yeast with an oxidant to kill microbial contaminants, thereby producing an oxidant-treated slurry comprising yeast;
(vii) re-introducing at least a portion of the oxidant-treated slurry comprising yeast back to the fermenting step (step iv) to increase the concentration of yeast in the fermentation reaction; and
(viii) recovering the ethanol.
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Abstract
A method for obtaining a fermentation product from a sugar hydrolysate obtained from a feedstock containing hemicellulose, by (i) removing suspended fiber solids from said sugar hydrolysate to obtain a clarified sugar solution; (ii) fermenting xylose in the clarified sugar solution in a fermentation reaction with yeast to produce a fermentation broth comprising the fermentation product; (iii) separating the yeast from the fermentation broth to produce a yeast slurry; (vi) treating the yeast slurry thus obtained with an oxidant to kill microbial contaminants, thereby an oxidant-treated yeast slurry; (v) re-introducing at least a portion of the oxidant-treated yeast back to step (ii) to increase the concentration of yeast in said fermentation reaction; and (vi) recovering the fermentation product.
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Citations
16 Claims
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1. A method for obtaining ethanol from a feedstock comprising hemicellulose, comprising:
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(i) pretreating the feedstock to produce a stream comprising pretreated feedstock; (ii) optionally removing xylose from the stream produced in step (i); (iii) hydrolyzing the pretreated feedstock with an enzyme mixture comprising cellulase enzymes and beta-glucosidase to produce a sugar hydrolyzate comprising at least glucose; (iv) fermenting the sugar hydrolyzate in a fermentation reaction with yeast to produce a fermentation broth comprising ethanol; (v) withdrawing a slurry comprising yeast during the fermenting step (step iv); (vi) treating the slurry comprising yeast with an oxidant to kill microbial contaminants, thereby producing an oxidant-treated slurry comprising yeast; (vii) re-introducing at least a portion of the oxidant-treated slurry comprising yeast back to the fermenting step (step iv) to increase the concentration of yeast in the fermentation reaction; and (viii) recovering the ethanol. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification