Integrated processing of biomass and liquid effluents

Abstract

An integrated process for the combined fermentation and the conversion of liquid and solid residues generated by the cane sugar industry into a variety of useful products. The process also relates to the treatment of other biomass materials. The process combines elements of alcohol-based organosolv pulping with fermentation in a fully integrated operation. This process eliminates the need for separate costly facilities, thus reducing capital and operating costs, providing opportunities for heat and energy reduction and a high degree of internal process recycle. The process would replace costly waste and residue treatment operations with revenue generating operations.

What I claim as my invention is:  
     
         1 . An integrated process performing fermentation of low value (molasses) and waste sugars together with the conversion of biomass residues from the cane sugar industry (bagasse) for the production of multiple useful products. Such process combines the elements of alcohol-based organosolv pulping and ethanol fermentation into a single integrated process.  
     
     
         2 . A process, as in  claim 1 , in which the useful products are any combination, or number, of products including unbleached papermaking pulp, bleached papermaking pulp, high alpha-cellulose pulp, organosolv lignin, furfural, acetic acid, ethyl acetate, sodium acetate, xylose, xylan, butanol, acetone, high-protein animal feed, plant fertilizer, uronic acids and ethanol.  
     
     
         3 . A process for delignifying biomass fibrous residues comprising, digesting biomass fibrous residues in a mixture of ethanol and water in a digester at elevated temperature and pressure, continually exposing the mixture of ethanol and water to the fibrous residues in a suitable digester, or by circulating the mixture of ethanol and water between the digester and a holding tank for a time sufficient to at least partially delignify the biomass fibrous residues and form a pulp, draining the mixture to a spent liquor tank at the end of the circulation time, causing the remaining liquor and partially delignified biomass to transfer from the digester to a blow tank by opening the valve to the blow tank.  
     
     
         4 . A process according to  claim 3 , wherein the process includes the step of recovering lignin and other chemicals from the mixture of ethanol and water contained in the spent liquor tank.  
     
     
         5 . A process according to  claim 3  or  claim 4 , wherein the mixture of ethanol and water in the digester is maintained at a temperature in a range from 170 to 205° C.  
     
     
         6 . A process according to  claim 5 , wherein the pressure in the digester and the holding tank is maintained at a level sufficient to prevent the mixture of water and ethanol from vaporizing.  
     
     
         7 . A process according to any one of  claims 3  to  6 , wherein the mixture of ethanol and water in the digester contains ethanol and water in a ratio in a range from 35% to 70% by weight ethanol to water.  
     
     
         8 . A process according to any one of  claims 3  to  7 , wherein the circulation time lies in a range from 30 minutes to 3 hours.  
     
     
         9 . A process according to  claim 8 , wherein the circulation time lies in a range from 1 to 2 hours.  
     
     
         10 . A process according to any one of  claims 3  to  9 , wherein the process includes transferring the contents of the spent liquor tank to a flash tank to enable volatile material to evaporate thereby leaving a lignin-rich condensed liquor, lowering the pH of the condensed liquor to a level below 3, diluting the condensed liquor with an aqueous stream and cooling the condensed liquor to cause lignin to precipitate from the mother liquor and separating lignin from the mother liquor.  
     
     
         11 . A process according to  claim 10 , wherein the process includes the steps of distilling the diluted mother liquor to recover ethanol and furfural therefrom leaving an aqueous stillage.  
     
     
         12 . A process according to  claim 11 , including the steps of concentrating the aqueous stillage by evaporation, allowing a liquid lignin fraction to settle, removing the liquid lignin fraction from an upper layer of the aqueous stillage thereby leaving an aqueous layer containing xylose, xylan and other sugars.