Processes Using Antibiotic Alternatives In Bioethanol Production

Abstract

Methods for controlling the growth of bacteria in ethanol fermentation systems with antibiotic alternatives, which can be nonoxidizing biocides, stabilized oxidizers, or any combinations thereof, are described. As an option, a process or composition of the present invention can include one or more polycyclic antibacterial peptides. The methods can provide improvements, such as increased ethanol yields with minimal carryover of biocide into co-products of the processes.

1 - 12 . (canceled) 
     
     
         13 . A method for producing ethanol with fermentation comprising:
 a) fermenting a fermentable mash in the presence of at least one stabilized oxidizer, and yeast in a vessel to produce ethanol and a solids content, wherein said stabilized oxidizer controls growth of bacteria in the mash without reducing yeast population; and   b) distilling the fermented mash to separate at least a portion of the ethanol from the solids content of the fermented mash.   
     
     
         14 . The method of  claim 13 , further comprising obtaining a distillers dried grains product from said solid contents containing less than about 100 ppm of the stabilized oxidizer. 
     
     
         15 . The method of  claim 13 , wherein the stabilized oxidizer is stabilized hypochlorous acid, stabilized hypochlorite, stabilized chloramine, stabilized hypobromous acid (e.g. bromosulfamate), stabilized chlorine dioxide, stabilized peracetic acid, iodine, stabilized iodine products, slow releasing chlorine trione sodium triochloro-s-triazinetrione, slow releasing sodium dichloro-s-triazinetrione, slow releasing chlorine trione, slow releasing sodium trichloro-s-triazinetrione, stabilized chlorohydantoin, stabilized bromohydantoin, or a stabilized modified hydantoin, or any combinations thereof. 
     
     
         16 . The method of  claim 13 , wherein the fermented mash in step (b) contains no greater than 10 ppm antibiotic. 
     
     
         17 . The method of  claim 13 , wherein said fermented mash in step b) has less than about 10 ppm of stabilized oxidizer present after distillation. 
     
     
         18 . The method of  claim 13 , wherein said fermented mash in step b) has less than about 1 ppm of stabilized oxidizer present after distillation. 
     
     
         19 . The method of  claim 13 , wherein the bacteria is a  Lactobacillus  sp.,  Acetobacter  sp., or any combinations thereof. 
     
     
         20 . The method of  claim 13  wherein the bacteria are obligate anaerobes. 
     
     
         21 . The method of  claim 13 , wherein the fermented mash in step (a) has at least about 5-fold less acid on a weight % basis than the same fermented mash fermented in the absence of the stabilized oxidizer biocide, wherein the acid is lactic acid or acetic acid. 
     
     
         22 . (canceled) 
     
     
         23 . A method for producing ethanol with fermentation comprising:
 a) fermenting a fermentable mash in the presence of at least one yeast in a vessel to produce ethanol and a solids content;   b) storing at least a portion of the fermented mash in at least one beer well in the presence of at least one nonoxidizing biocide, wherein the nonoxidizing biocide controls the growth of bacteria in the at least one beer well; and   c) feeding stored mash from the at least one beer well to at least one distillation unit;   d) distilling the fermented mash in the at least one distillation unit to separate at least a portion of the ethanol from the solids content.   
     
     
         24 . A method for producing ethanol comprising:
 a) fermenting a fermentable mash in the presence of yeast and recycled process water in a fermenter vessel to produce fermented mash comprising ethanol and a solids content;   b) optionally scrubbing gaseous emissions from the fermenter vessel with an aqueous solution and recycling at least a portion of the scrubber effluent solution into the fermenter vessel;   c) optionally storing at least a portion of the fermented mash in at least one beer well;   d) feeding fermented mash to a distillation unit;   e) distilling the fermented mash in the distillation unit to separate at least a portion of the ethanol from stillage;   f) separating the stillage into a liquids-containing fraction and a solids-containing fraction;   g) optionally recycling at least portion of the liquids-containing fraction of f) into the fermenter vessel,   h) recovering the solids-containing fraction of f) as at least in part as wet distillers grains product and/or drying at least a portion of the solids-containing fraction to produce distillers dried grains product and evaporated vapors;   i) optionally condensing the evaporated vapors of h) and recycling at least a portion of the condensed vapors into the fermenter vessel, and   
       wherein nonoxidizing biocide and/or stabilized oxidizer is added to or is present in at least one source of recycled water of the scrubber effluent solution of b), the liquids-containing fraction from stillage separation of f), and condensed vapors from distillers grains drying of i), or any combinations thereof, before the water source is recycled into the fermenter vessel. 
     
     
         25 . A method for producing distillers dried grains coproducts of ethanol production comprising:
 a) fermenting a fermentable mash in the presence of yeast in a fermenter vessel to produce fermented mash comprising ethanol and a solids content;   b) optionally scrubbing gaseous emissions from the fermenter vessel with an aqueous solution and recycling at least a portion of the scrubber effluent solution into the fermenter vessel;   c) optionally storing at least a portion of the fermented mash in at least one beer well;   d) feeding fermented mash to a distillation unit;   e) distilling the fermented mash in the distillation unit to separate at least a portion of the ethanol from stillage;   f) separating the stillage into a liquids-containing fraction and a solids-containing fraction;   g) optionally recycling at least portion of the liquids-containing fraction of f) into the fermenter vessel,   h) recovering the solids-containing fraction of f) with drying of at least a portion of the solids-containing fraction to produce distillers dried grains product and evaporated vapors;   i) optionally condensing the evaporated vapors of h) and recycling at least a portion of the condensed vapors into the fermenter vessel, and   
       wherein nonoxidizing biocide and/or stabilized oxidizer for control of bacteria in the fermentation vessel is added to or is present in at least one of the fermenter vessel, beer well, and recycled sources of water, or any combinations thereof. 
     
     
         26 . The method of  claim 25 , further comprising obtaining a distillers dried grains product containing less than about 100 ppm of the nonoxidizing biocide and/or stabilized oxidizer. 
     
     
         27 - 32 . (canceled)