Clean sugar and lignin from non-chemically pretreated lignocellulosic biomass

1. A method of lignocellulosic biomass conversion, the method comprising:

obtaining non-chemically pretreated, milled softwood lignocellulosic biomass having a particle size greater than 10 microns and less than 300 microns, wherein the softwood lignocellulosic biomass is from Douglas fir;

reacting the milled softwood lignocellulosic biomass with an enzymatic agent to produce a slurry that includes converted monomeric lignocellulosic sugars and lignin-rich residuals and is free of furans and other fermentation inhibitors; and

separating the slurry into a sugar composition that includes the converted monomeric lignocellulosic sugars and a lignin-rich composition that includes the lignin-rich residuals;

wherein the sugar composition, not including water, includes at least 75% monomeric lignocellulosic sugar, less than 0.20% sulfur, less than 3.0% metal ion content, and has:

a ratio of monomeric glucose plus monomeric mannose to monomeric xylose greater than 23.4,

a ratio of monomeric glucose plus monomeric mannose to monomeric galactose greater than 93.6, and/or

a ratio of monomeric glucose plus monomeric mannose to monomeric arabinose greater than 280.7; and

wherein the lignin-rich composition includes at least 35% lignin and less than 0.50% sulfur.

2. The method of claim 1 , wherein separating the slurry includes filtering the slurry to yield a filtrate that includes the sugar composition, and a high solid stream that includes the lignin-rich composition and undigested lignocellulosic biomass.

3. The method of claim 1 , further comprising, subsequent to separating the slurry, concentrating the sugar composition to produce a concentrated lignocellulosic sugar mixture.

4. The method of claim 1 , further comprising, subsequent to separating the slurry, drying the lignin-rich composition to produce a lignin composition having a solid content of at least 80%.

5. The method of claim 1 , wherein the composition of the sugar composition, not including water, includes at least 85.0% (w/w) monomeric lignocellulosic sugar.

6. The method of claim 1 , wherein the composition of the sugar composition, not including water, includes at least 90.0% (w/w) monomeric lignocellulosic sugar.

7. The method of claim 1 , further comprising producing a fermentation product from the converted monomeric lignocellulosic sugars in the sugar composition.

8. The method of claim 7 , wherein the fermentation product includes one or more of an alcohol and an organic acid.

9. The method of claim 1 , wherein the particle size of the non-chemically pretreated, milled lignocellulosic biomass is greater than 25 microns and less than 300 microns.

10. The method of claim 1 , wherein the Douglas fir is debarked.

11. A method of hydrolytic lignocellulosic biomass conversion, the method comprising:

in a first hydrolysis reaction, reacting non-chemically pretreated, milled softwood lignocellulosic biomass, the milled lignocellulosic biomass having a particle size greater than 10 microns and less than 300 microns, wherein the softwood lignocellulosic biomass is from Douglas fir, with an enzymatic agent to produce a first slurry that includes converted lignocellulosic sugars, lignin-rich residuals, and unused enzymatic agent;

mixing additional non-chemically pretreated, milled softwood lignocellulosic biomass with the first slurry to produce a slurry mixture;

separating the converted lignocellulosic sugars from the slurry mixture;

in a second hydrolysis reaction, reacting the non-chemically pretreated, milled softwood lignocellulosic biomass in the slurry mixture with the unused enzymatic agent in the slurry mixture to produce a second slurry that includes converted lignocellulosic sugars and lignin-rich residuals; and

separating the converted lignocellulosic sugars from the second slurry;

wherein the converted lignocellulosic sugars separated from the slurry mixture and/or the second slurry provide a sugar composition that has:

a ratio of monomeric glucose plus monomeric mannose to monomeric xylose greater than 23.4,

a ratio of monomeric glucose plus monomeric mannose to monomeric galactose greater than 93.6, and/or

a ratio of monomeric glucose plus monomeric mannose to monomeric arabinose greater than 280.7.

12. The method of claim 11 ,

wherein the first hydrolysis reaction is carried out in a hydrolysis unit;

wherein the separating is carried out in a filtration unit; and

wherein the mixing is carried out while transporting the slurry mixture from the hydrolysis unit to the filtration unit.

13. The method of claim 11 , further including one or more of:

combining the converted lignocellulosic sugars separated from the first and second slurries, and

combining the lignin-rich residuals from the first and second slurries.

14. A method of lignocellulosic biomass conversion, comprising:

obtaining non-chemically pretreated, milled softwood lignocellulosic biomass having a particle size greater than 10 microns and less than 300 microns, wherein the softwood lignocellulosic biomass is from Douglas fir;

reacting the milled lignocellulosic biomass with an enzymatic agent to produce a slurry that includes converted monomeric lignocellulosic sugars and lignin-rich residuals, wherein the slurry is free of furans and other fermentation inhibitors; and

separating the slurry into a sugar composition that includes the converted monomeric lignocellulosic sugars and a lignin-rich composition that includes the lignin-rich residuals;

wherein the sugar composition, not including water, includes at least 75% monomeric lignocellulosic sugar, less than 0.20% sulfur, less than 3.0% metal ion content, and has a monomeric glucose content that is greater than or equal to 78.8% of a total monomeric sugar content of the group consisting of glucose, mannose, arabinose, galactose, and xylose; and

wherein the lignin-rich composition includes at least 35% lignin and less than 0.50% sulfur.

15. The method of claim 14 , wherein the Douglas fir is debarked.