Process for the hydrolysis of biomass
The present invention is directed to a novel and advantageous process for the hydrolysis of biomass which enables a thorough hydrolyzation also of recalcitrant biomass such as sugar cane straw and sugar cane bagasse.
1. A process for the hydrolysis of biomass comprising the steps of:
a) Contacting the biomass with an enzyme-composition containing at least one enzyme selected from the class of hydrolases sufficient to hydrolyze at least part of the biomass to fermentable sugars in a vessel for 3 to 60 h and at a temperature of from 45 to 65° C., whereby a solid phase and a liquid phase comprising the fermentable sugars are formed;
b) Separating the solid and liquid phases;
c) Enzymatically converting the separated solid phase with further addition of an enzyme-composition containing at least one enzyme selected from the class of hydrolases sufficient to hydrolyze the solid phase to more fermentable sugars to produce a converted solid phase comprising more fermentable sugars:
d) Combining at least part of the converted solid phase of step (c) with the liquid phase of step (b); wherein at least one fermentation organism is added to the liquid phase before or during step (d), wherein the temperature during the addition of the at least one fermentation organism is from 25 to 45° C., and wherein from 10 to 100 wt-% of the converted solid phase is fed to the liquid phase of step (b).
2. The process of claim 1 , wherein an amount of liquid is added to the solid phase before or during step (c).
3. The process of claim 1 , wherein at least one fermentation organism is added to the liquid phase after step (d) of the process.
4. The process of claim 1 , wherein step (c) is carried out for at least 30 minutes before feeding at least part of the converted solid phase in step (d).
5. The process of claim 1 , wherein the combining in step (d) is carried out using a heat exchanger.
6. The process of claim 1 , wherein steps (a) to (d) are at least partially carried out simultaneously and/or continuously.
7. The process of claim 1 , wherein the enzyme-composition in step (a) or contains at least one cellobiohydrolase (EC 3.2.1-) and at least one endo-,4-β-glucanase (EC 3.2.1.4).
8. The process of claim 1 , wherein the biomass is selected from sugar-beet, sugar cane, sugar-cane straw, sugar-beet pulp, sugar-cane bagasse, straw, corn, wood, oilseed and mixtures thereof.
9. The process of claim 1 , wherein the dry matter content of the biomass is in the range from 5 to 30 wt.-%.