Apparatus and process for fermentation of biomass hydrolysate

Abstract

A process for converting biomass hydrolysate into biofuel, the process comprising the steps of: obtaining a biomass hydrolysate solution comprising monosaccharides; immobilizing Pachysolen tannophilus ; contacting the solution with the immobilized Pachysolen tannophilus ; and recovering a fermented biofuel.

What is claimed is: 
     
         1 . A process for converting biomass hydrolysate into biofuel, the process comprising the steps of:
 a. obtaining a biomass hydrolysate solution comprising monosaccharides;   b. immobilizing  Pachysolen tannophilus;      c. contacting the biomass hydrolysate solution with the immobilized  Pachysolen tannophilus ; and   d. recovering a fermented biofuel.   
     
     
         2 . The process according to  claim 1 , wherein  Pachysolen tannophilus  is immobilized in calcium alginate. 
     
     
         3 . The process according to  claim 2 , wherein the calcium alginate is in the form of beads ranging from 0.1 mm to 5 mm in diameter. 
     
     
         4 . The process according to  claim 2 , wherein the calcium alginate is in the form of a coating applied to a natural matrix. 
     
     
         5 . The process according to  claim 2 , wherein the calcium alginate is in the form of a coating applied to a synthetic matrix. 
     
     
         6 . The process according to  claim 2 , further comprising the step of treating the calcium alginate immobilized  Pachysolen tannophilus  with a yeast growth medium. 
     
     
         7 . The process according to  claim 3 , further comprising the step of recovering and recycling calcium alginate used to immobilize the  Pachysolen tannophilus.    
     
     
         8 . The process according to  claim 7 , wherein the calcium alginate used to immobilize the  Pachysolen tannophilus  is recovered and recycled by a process comprising the steps of:
 a. treating the calcium alginate with a calcium chelator and monovalent counter-ion to thereby form a solution; and   b. performing dialysis on the solution against an inorganic salt to form sodium alginate.   
     
     
         9 . The process according to  claim 1 , wherein the biomass hydrolysate solution comprises a substantial amount of fermentation inhibitors. 
     
     
         10 . The process according to  claim 9 , wherein the solution of monosaccharides has furfural levels in the range of about 0.01 to 10 g/L. 
     
     
         11 . The process according to  claim 9 , wherein the solution of monosaccharides has 5-hydroxymethylfurfural levels in the range of about 0.01 to 10 g/L. 
     
     
         12 . The process according to  claim 9 , wherein the solution of monosaccharides has acetic acid levels in the range of about 0.5 to 20 g/L. 
     
     
         13 . The process according to  claim 1 , wherein more than 80% of the monosaccharides in the solution are converted to ethanol. 
     
     
         14 . The process according to  claim 1 , wherein the biomass hydrolysate is obtained by pressing a pretreated biomass. 
     
     
         15 . The process according to  claim 1 , wherein the biomass hydrolysate is obtained by pressing biomass subjected to a pretreatment process and a saccharification process. 
     
     
         16 . The process according to  claim 2 , wherein the calcium alginate is hardened to increase structural stability. 
     
     
         17 . A process for converting biomass hydrolysate into biofuel, the process comprising the steps of:
 a. contacting the biomass hydrolysate solution with a first immobilized microbe strain;   b. contacting the biomass hydrolysate solution with a second immobilized microbe strain; and   c. recovering a fermented biofuel.   
     
     
         18 . The process according to  claim 17 , wherein the first immobilized microbe strain is a bacterium and the second immobilized microbe strain is a yeast. 
     
     
         19 . The process according to  claim 17 , wherein the first immobilized microbe strain is contained in a first reactor and the second immobilized microbe strain is contained in a second reactor. 
     
     
         20 . The process according to  claim 17 , wherein the first immobilized microbe strain and the second immobilized microbe strain are immobilized together within the same immobilization medium. 
     
     
         21 . The process according to  claim 20 , wherein the immobilization medium is a calcium alginate bead. 
     
     
         22 . The process according to  claim 17 , wherein the first immobilized microbe strain is immobilized in a first immobilization medium and the second immobilized microbe strain is immobilized in a second immobilization medium. 
     
     
         23 . The process according to  claim 22 , wherein the first immobilization medium is a first plurality of calcium alginate beads and the second immobilization medium is a second plurality of calcium alginate beads. 
     
     
         24 . The process of  claim 17  wherein the second immobilized microbe strain is capable of fermenting a hexose mannose to a biofuel. 
     
     
         25 . A process for converting biomass hydrolysate into biofuel, the process comprising the steps of:
 a. flowing a biomass hydrolysate solution comprising monosaccharides and one or more inhibitory secondary products through a continuous flow reactor containing an immobilized microbe strain and contacting the immobilized microbe strain with the biomass hydrolysate;   e. recovering a fermented biofuel.   
     
     
         26 . The process according to  claim 25 , wherein the flow rate of the biomass hydrolysate exceeds the sedimentation rate of the immobilized microbe strain in a “free” condition. 
     
     
         27 . The process according to  claim 25 , wherein the continuous flow reactor is an upflow reactor. 
     
     
         28 . The process according to  claim 25 , wherein the productivity of the biofuel conversion process is at least 0.3 g/L·h for a flow rate corresponding to a 10 hour retention time. 
     
     
         29 . The process according to  claim 25 , wherein the productivity of the biofuel conversion process is at least 0.42 g/L·h for a flow rate corresponding to a 5 hour retention time. 
     
     
         30 . A process for converting biomass hydrolysate into biofuel the process comprising the steps of:
 contacting a biomass hydrolysate solution with an immobilized fermentative microbe strain for a sufficient reaction time to convert monosaccharides in the biomass hydrolysate to biofuel; and   recovering biofuel from the fermented hydrolysate.   
     
     
         31 . The process according to  claim 32 , wherein the immobilized fermentative microbe strain is a yeast and the process further comprises the step of treating the yeast with a yeast regeneration medium. 
     
     
         32 . The process according to  claim 32 , further comprising the step of conditioning the biomass hydrolysate by passing the hydrolysate over activated carbon, strong acid ion exchange resin and weak base ion exchange resin. 
     
     
         33 . The process according to  claim 32 , wherein the immobilized fermentative microbe strain is immobilized in calcium alginate and the process further comprises the step of recovering and recycling the calcium alginate. 
     
     
         34 . The process according to  claim 32 , wherein the biomass hydrolysate solution contains inhibitory secondary products sufficient to prevent more than 50% conversion of pentoses by the fermentative microbes in their “free” state. 
     
     
         35 . The process according to  claim 32 , wherein the immobilized fermentative microbe strain is at least one strain selected from the group consisting of  Pichia, Candida, Klyveromyces  and  Zymomonas mobilis  NREL strain 8b. 
     
     
         36 . The process according to  claim 32 , wherein the immobilized fermentative microbe strain converts about 30% more pentoses than the same fermentative microbe strain in a “free” condition.