Patent ID: 8030040
Filing Date: 2011-10-04
Classification: C12P,C13K,Y02E

Abstract:
1. A process of producing fermentation product comprising the steps of, (i) forming an acidified suspension of particulate plant derived material comprising a first polysaccharide which is more readily hydrolysable and a second polysaccharide which is more difficult to hydrolyse, (ii) allowing the first polysaccharide to undergo hydrolysis by action of the acid at a temperature of at least 50° C. under conditions such that the first polysaccharide is hydrolysed and thereby forming a mixture of an aqueous liquor containing dissolved sugar and a solid residue containing the second polysaccharide, (iii) subjecting the acidic mixture to one or more separation stages in which the solid residue and aqueous sugar liquor are substantially separated from each other, (iv) optionally washing the residue substantially free of the acid and the sugar, (v) passing the solid cellulosic residue to a further treatment stage in which the residue is subjected to the action of dilute acid at a temperature of at least 50° C. under conditions such that the second polysaccharide is hydrolysed and thereby forming a mixture of an aqueous liquor containing dissolved sugar and a solid residue, (vi) subjecting the acidic mixture to one or more separation stages in which the solid residue and aqueous sugar liquor are substantially separated from each other, (vii) optionally washing the residue substantially free of the acid and the sugar, (viii) adjusting the pH of the aqueous liquor from stages (iii), (iv), (vi) and (vii) to a pH of at least 4, (ix) passing the aqueous liquor from stage (viii) to a fermentation stage where the dissolved sugars are acted upon by a microorganism in a fermentation broth to produce a fermentation product, (x) separating the fermentation product from the broth, characterised in that the separation stage in steps (iii) and/or (vi) a flocculating agent is added to form a waste by-product, employing one or more flocculating agent(s) selected from the group consisting of water-soluble polymers, and water-swellable polymers and the water-soluble or water-swellable polymer is selected from the group consisting of polyacrylate salts, polyacrylamide, copolymers of acrylamide with (meth)acrylic acid or salts thereof, copolymers of acrylamide with dialkylaminoalkyl (meth)acrylate or acid addition or quaternary ammonium salts, polymers of diallyldimethyl ammonium chloride, polyamines and polyethylene imines, the separation stage in steps (iii) and/or (vi) further includes mechanical means selected from the group consisting of a filter press, centrifuge, belt press, horizontal belt filter, and pressure filter, to separate the solid residue as cake solids.