Composition and method for controlling volatile fatty acid content in pulp, paper, and/or board making processes

Abstract

A method of controlling volatile fatty acid (VFA) content in a pulp, paper, and/or board making processes is disclosed. The method may be used to provide process improvements in the form of reduced microbial contamination and odor, reduced starch degradation, optimized retention, and improved runability. The method includes treating a process flow comprising a cellulosic material comprising a starch with an enzymatic VFA control agent. The enzymatic VFA control agent is non-biocidal, may further comprise a surfactant or dispersant, and is utilized in an amount sufficient to inhibit microbiological production of one or more VFA. The method optionally includes treating the process flow with a biocidal agent in combination with the enzymatic VFA control agent. A composition for carrying out the method is also disclosed.

What is claimed is: 
     
         1 . A method of controlling volatile fatty acid (VFA) content in pulp, paper, and/or board making processes, said method comprising:
 treating a process flow comprising a cellulosic material comprising a starch with an enzymatic VFA control agent in an amount sufficient to inhibit microbiological production of one or more VFA.   
     
     
         2 . The method of  claim 1 , wherein the enzymatic VFA control agent: (i) comprises an enzyme selected from oxidases, proteases, nucleases, and combinations thereof; (ii) exhibits an optimal enzymatic activity at a temperature of from about 15 to about 70° C.; or (iii) both (i) and (ii). 
     
     
         3 . The method of  claim 1 , wherein the enzymatic VFA control agent comprises a cellobiose oxidase, a glucose oxidase, a combination of a protease and a nuclease, or a combination thereof. 
     
     
         4 . The method of  claim 2 , wherein the enzymatic VFA control agent further comprises a surfactant, a dispersant, a chelator, a sequestrant, or a combination thereof, capable of inhibiting amylase activity in the process flow. 
     
     
         5 . The method of  claim 4 , wherein the enzymatic VFA control agent comprises a biodispersant comprising an alkylbenzene sulfonate. 
     
     
         6 . The method of  claim 5 , wherein the biodispersant comprises a linear alkylbenzene sulfonate surfactant present in an amount of from about 5 to about 30 weight percent actives, based on a total weight of the biodispersant, and having the structure: 
       
         
           
           
               
               
           
         
         wherein X is a counter ion and each subscript m and n is independently from 0 to 16, with the proviso that m+n is from 4 to 16; 
         a defoamer present in an amount of from about 1 to about 20 weight percent actives based on a total weight of the biodispersant; 
         a thickening agent present in an amount of from greater than zero to an amount of about 3 weight percent actives based on a total weight of the biodispersant; and 
         water. 
       
     
     
         7 . The method of  claim 6 , wherein: (i) the linear alkylbenzene sulfonate surfactant is sodium dodecylbenzene sulfonate; (ii) the defoamer is an emulsion comprising hydrophobic silica; (iii) the thickening agent is a cross-linked polyacrylic acid; or (iv) any combination of (i)-(iii). 
     
     
         8 . The method of  claim 1 , wherein treating the process flow: (i) comprises adding the enzymatic VFA control agent in an amount effective to give an active concentration in the process flow of from about 1 to about 200 ppm, based on the volume of the process flow treated with the enzymatic VFA control agent; (ii) is conducted in batch or continuous mode; (iii) is carried out at a temperature of from about 15 to about 70° C.; or (iv) any combination of (i)-(iii). 
     
     
         9 . The method of  claim 1 , further comprising treating the process flow with a biocidal agent, wherein the biocidal agent comprises an oxidizing biocide, a non-oxidizing biocide, or a combination thereof. 
     
     
         10 . The method of  claim 9 , wherein the biocidal agent comprises the oxidizing biocide; wherein the method comprises treating the process flow with the oxidizing biocide after treating with the enzymatic VFA control agent; and wherein treating the process flow with the oxidizing biocide comprises adding the oxidizing biocide to the process flow in an amount effective to give an active concentration of the oxidizing biocide in the process flow of from about 0.1 to about 250 ppm, based on the volume of the process flow treated with the enzymatic VFA control agent. 
     
     
         11 . The method of  claim 10 , wherein the oxidizing biocide comprises monochloramine (MCA). 
     
     
         12 . The method of  claim 9 , wherein the biocidal agent comprises the non-oxidizing biocide, and wherein treating the process flow with the biocidal agent comprises adding the biocidal agent in an amount effective to give an active concentration of the non-oxidizing biocide in the process flow of from about 0.1 to about 1000 ppm, based on the volume of the process flow treated with the enzymatic VFA control agent. 
     
     
         13 . The method of  claim 12 , wherein the method comprises treating the process flow with the enzymatic VFA control agent and the non-oxidizing biocide: (i) simultaneously, optionally as a premixed VFA control composition; or (ii) sequentially. 
     
     
         14 . The method of  claim 12 , wherein the non-oxidizing biocide comprises a thiazole-based microbiocide, a carbamate-based microbiocide, bronopol, or combinations thereof. 
     
     
         15 . The method of  claim 1 , wherein the one or more VFA is selected from formic acid, acetic acid, propionic acid, lactic acid, butyric acid, valeric acid, and combinations thereof. 
     
     
         16 . The method of  claim 1 , wherein treating the process flow with the enzymatic VFA control agent results in: (i) a reduction in VFA content of at least about 5% within 1 hour of the treating; (ii) a reduction in VFA content of at least about 15% after 48 hours of the treating; or (iii) both (i) and (ii), in each case as compared to an untreated sample of the process flow taken before the treating. 
     
     
         17 . A composition for treating a process flow comprising a cellulosic material comprising a starch, the composition comprising:
 an enzymatic VFA control agent; and   optionally, a biodispersent.   
     
     
         18 . The composition of  claim 17 , wherein the enzymatic VFA control agent: (i) comprises an enzyme selected from oxidases, proteases, nucleases, or combinations thereof; (ii) exhibits an optimal enzymatic activity at a temperature of from about 15 to about 70° C.; or (iii) both (i) and (ii). 
     
     
         19 . The composition of  claim 17 , wherein the composition: (i) comprises the biodispersant, and the biodispersant comprises an alkylbenzene sulfonate; (ii) further comprises a nonoxidizing biocide; or (iii) both (i) and (ii). 
     
     
         20 . A kit, comprising the composition of  claim 17  and an oxidizing biocide.