METHODS AND SYSTEMS FOR ENZYMATIC HYDROLYSIS OF PRETREATED BIOMASS AT HIGH SOLIDS CONCENTRATIONS
A method of enzymatically hydrolyzing pretreated lignocellulosic biomass at high solids concentration includes introducing pretreated biomass to a hydrolysis reactor, to hydrolyze the cellulose to glucose monomer and glucose oligomers, and circulating a liquid stream, from which glucose is removed to reduce glucose inhibition of cellulose hydrolysis. A surfactant may be added to the hydrolysis reactor. Heat and/or acid treatment of the glucose oligomers may be used to generate additional glucose monomer. Some variations introduce pretreated biomass to a hydrolysis reactor to hydrolyze cellulose to glucose monomer and glucose oligomers, followed by conveying a portion of the solid phase to a mechanical refiner and/or a unit under reduced pressure, to generate a refined and/or exploded solid phase; and recycling the refined and/or exploded solid phase, optionally reheated, back to an input of the hydrolysis reactor.
1 . A method of enzymatically hydrolyzing pretreated lignocellulosic biomass at high solids concentration, said method comprising:
(a) providing pretreated lignocellulosic biomass containing cellulose;
(b) introducing said pretreated lignocellulosic biomass to a hydrolysis reactor under effective hydrolysis conditions and in the presence of enzymes including cellulases, to hydrolyze said cellulose to glucose monomer and glucose oligomers; and
(c) circulating a liquid stream in a circulation line configured from an output of said reactor back to an input of said hydrolysis reactor, wherein at least a portion of said glucose monomer is removed from said circulation line to reduce glucose inhibition of cellulose hydrolysis,
wherein said method further comprises a glucose oligomer hydrolysis step to generate additional glucose monomer from said glucose oligomers.
2 . The method of claim 1 , wherein said glucose oligomer hydrolysis step is integrated with step (b).
3 . The method of claim 1 , wherein said glucose oligomer hydrolysis step is integrated with step (c).
4 . The method of claim 1 , wherein at least a portion of said glucose oligomers is also removed from said circulation line to reduce glucose oligomer inhibition of cellulose hydrolysis.
5 . The method of claim 1 , wherein additional cellulase enzymes are introduced to said circulation line, to convert said glucose oligomers to said additional glucose monomer.
6 . The method of claim 1 , wherein said method further comprises introducing a surfactant to said hydrolysis reactor during step (b) or step (c).
7 . The method of claim 6 , wherein said surfactant includes lignin.
8 . A method of enzymatically hydrolyzing pretreated lignocellulosic biomass at high solids concentration, said method comprising:
(a) providing pretreated lignocellulosic biomass containing cellulose;
(b) introducing said pretreated lignocellulosic biomass to a hydrolysis reactor under effective hydrolysis conditions and in the presence of enzymes including cellulases, to hydrolyze a portion of said cellulose to glucose monomer and glucose oligomers present in a liquid phase, wherein non-hydrolyzed cellulose remains in a solid phase; and
(c) conveying a portion of said solid phase to a mechanical refiner, to generate a refined solid phase; and
(d) recycling said refined solid phase back to an input of said hydrolysis reactor.
9 . A method of enzymatically hydrolyzing pretreated lignocellulosic biomass at high solids concentration, said method comprising:
(a) providing pretreated lignocellulosic biomass containing cellulose;
(b) introducing said pretreated lignocellulosic biomass to a hydrolysis reactor under effective hydrolysis conditions and in the presence of enzymes including cellulases, to hydrolyze a portion of said cellulose to glucose monomer and glucose oligomers present in a liquid phase, wherein non-hydrolyzed cellulose remains in a solid phase;
(c) feeding a portion of said solid phase to a unit under reduced pressure, to generate an exploded solid phase; and
(d) recycling said exploded solid phase, optionally reheated, back to an input of said hydrolysis reactor.
10 . The method of either one of claim 8 or 9 , wherein said method further comprises an oligomer hydrolysis step of said glucose oligomers to generate additional glucose monomer.
11 . The method of either one of claim 8 or 9 , wherein said method further comprises introducing a surfactant to said hydrolysis reactor.
12 . The method of either one of claim 8 or 9 , wherein said pretreated lignocellulosic biomass is a pulp material, derived from wood or lignocellulosic biomass, selected from the group consisting of kraft pulp, sulfite pulp, soda pulp, mechanical pulp, thermomechanical pulp, chemimechanical pulp, and combinations thereof.
13 . The method of either one of claim 8 or 9 , wherein said pretreated lignocellulosic biomass is obtained from steam or hot-water extraction of lignocellulosic biomass.
14 . The method of either one of claim 8 or 9 , wherein said pretreated lignocellulosic biomass is present in said hydrolysis reactor at a solids concentration of about 20 wt % or more.
15 . The method of either one of claim 8 or 9 , wherein a first amount of enzymes is introduced at a first solids concentration, wherein a second amount of enzymes is introduced at a second solids concentration, and wherein said second solids concentration is higher than said first solids concentration.