Method to separate lignin-rich solid phase from acidic biomass suspension at an acidic pH

1. A method of separating a lignin-rich solid phase from an aqueous suspension comprising a lignocellulosic biomass having an acidic pH and aromatic components, the method comprising:

dividing the aqueous suspension comprising the lignocellulosic biomass having the acidic pH and the aromatic components into a residual lignocellulosic biomass and a suspension comprising soluble components having colloidal material and primarily lignin containing particles, said suspension having a pH less than about 4, using a pretreatment fluid;

flocculating said suspension using a sufficient amount of polyethylene oxide (PEO) as a flocculating agent, substantially without added cofactors;

adding to said suspension a precipitated calcium carbonate to raise the pH to between about 5 to 7.5; and

separating the flocculated suspension to remove agglomerates to achieve a reduction in turbidity of about 99.5%.

2. The method according to claim 1 , wherein said dividing comprises at least one method selected from the group consisting of sedimentation, centrifugation, and microfiltration.

3. The method according to claim 1 , wherein said pretreatment fluid comprises a hot water extraction fluid.

4. The method according to claim 1 , wherein said flocculating is conducted at a temperature of about 21.5° C. to about 25° C.

5. The method according to claim 1 , further comprising fermenting a solution resulting after separating the flocculated suspension to remove agglomerates.

6. The method according to claim 1 , wherein said separating comprises filtering through a filter having a pore size of less than about 10 microns.

7. The method according to claim 1 , wherein said separating comprises filtering through at least one of a ceramic filter and a cloth filter.

8. The method according to claim 1 , wherein the flocculating is performed for a sufficient time of less than about 2 hours to form agglomerates separable from the flocculated suspension to achieve the reduction in turbidity of about 99.5%.

9. The method according to claim 1 , wherein the precipitated calcium carbonate is limited to an amount that does not substantially increase turbidity of the suspension.

10. A method for treating lignocellulosic biomass comprising:

treating the lignocellulosic biomass with an extractant to extract a suspension comprising soluble components having colloidal material and primarily lignin containing particles from the lignocellulosic biomass, yielding a residual biomass and the suspension having a pH less than about 4;

separating the suspension from the residual biomass;

adding a flocculating agent to the suspension to form a flocculated suspension, wherein the flocculating agent comprises polyethylene oxide (PEO) in an amount sufficient to achieve a 99.5% reduction in turbidity after separation;

adding to the suspension a precipitated calcium carbonate to raise the pH between about 5 and 7.5; and

separating a flocculated portion of the flocculated suspension from a non-flocculated portion of the flocculated suspension to produce a fermentable solution from the lignocellulosic biomass.

11. The method according to claim 10 , wherein the extractant comprises hot water.

12. The method according to claim 10 , wherein the suspension is separated from the residual biomass with a separation device which comprises at least one of a filter, a sedimentation tank, and a centrifuge.

13. A method of separating a lignin-rich solid phase from a suspension comprising:

dividing a lignocellulosic biomass into a residual lignocellulosic biomass and a suspension comprising soluble components having colloidal material and primarily lignin containing particles, the suspension having a pH less than about 4, using a pretreatment fluid;

treating the suspension with a polymer flocculating agent comprising a sufficient amount of polyethylene oxide (PEO) and precipitated calcium carbonate to raise the pH to between about 5 and 7.5 and said polymer flocculating agent, being substantially without additional cofactors; and

separating the flocculated suspension to remove agglomerates to achieve a reduction in turbidity of about 99.5%.

14. The method according to claim 13 , wherein said dividing comprises at least one method selected from the group consisting of sedimentation, centrifugation, and microfiltration.

15. The method according to claim 13 , wherein said suspension comprises an aqueous suspension.

16. The method according to claim 13 , wherein said treating is conducted at a temperature of about 21.5° C. to about 25° C.

17. The method according to claim 13 , further comprising microbially processing a non-agglomerated portion of the flocculated suspension.

18. The method according to claim 17 , wherein said microbially processing comprises fermenting.

19. The method according to claim 13 , wherein said separating comprises filtering through a filter having a pore size of less than about 10 microns.

20. The method according to claim 13 , wherein said separating comprises filtering through at least one of a ceramic filter and a cloth filter.

21. The method according to claim 13 , wherein the treating is performed for less than about 2 hours.

22. The method according to claim 13 , wherein said pretreatment fluid comprises a hot water extraction fluid and said treating is conducted at a temperature of about 21.5° C. to about 25° C.

23. The method according to claim 13 , wherein the precipitated calcium carbonate is limited to an amount that does not substantially increase turbidity of the suspension.