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 a VFA control agent. The VFA control agent is non-biocidal, comprises a surfactant or dispersant, a chelator or sequestrant, or a combination thereof, is capable of inhibiting amylase activity in the process flow, 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 VFA control agent.

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 a non-biocidal VFA control agent in an amount sufficient to inhibit microbiological production of one or more VFA.   
     
     
         2 . The method of  claim 1 , wherein the VFA control agent comprises a surfactant, a dispersant, a chelator, a sequestrant, or a combination thereof, capable of inhibiting amylase activity in the process flow. 
     
     
         3 . The method of  claim 1 , wherein the VFA control agent comprises a surfactant or dispersant comprising an alkylbenzene sulfonate. 
     
     
         4 . The method of  claim 1 , wherein the VFA control agent 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 VFA control agent, 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 VFA control agent; 
         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 VFA control agent; and 
         water. 
       
     
     
         5 . The method of  claim 4 , wherein: (i) the 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). 
     
     
         6 . The method of  claim 1 , wherein the VFA control agent comprises a chelator or sequestrant comprising an organic or inorganic phosphonate, a phosphonic acid or salt thereof, or a combination thereof. 
     
     
         7 . The method of  claim 1 , wherein the VFA control agent comprises an amino phosphonic acid or a salt thereof. 
     
     
         8 . The method of  claim 1 , wherein the VFA control agent comprises: (i) an alkylbenzene sulfonate; (ii) a polyamino polyether methylene phosphonic acid (PAPEMP); (iii) a bis(hexamethylenetriaminepenta(methylene phosphonic acid)) (BHMTAP); (iv) a diethylenetriamine penta(methylene phosphonic acid) (DTPMPA) or a sodium salt thereof; (iv) a sodium hexametaphosphate (SHMP); or (v) any combination of (i)-(iv). 
     
     
         9 . The method of  claim 8 , wherein the VFA control agent further comprises sodium bisulfite. 
     
     
         10 . The method of  claim 1 , wherein treating the process flow comprises adding the VFA control agent in an amount effective to give an active concentration in the process flow of from about 1 to about 1000 ppm, based on the volume of the process flow treated with the VFA control agent. 
     
     
         11 . 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. 
     
     
         12 . The method of  claim 11 , wherein the biocidal agent comprises the 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 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 VFA control agent. 
     
     
         13 . The method of  claim 12 , wherein the oxidizing biocide comprises monochloramine (MCA). 
     
     
         14 . The method of  claim 11 , 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 VFA control agent. 
     
     
         15 . The method of  claim 14 , wherein the non-oxidizing biocide comprises a thiazole-based microbiocide, a carbamate-based microbiocide, bronopol, or combinations thereof. 
     
     
         16 . The method of  claim 14 , wherein the non-oxidizing biocide comprises a methylchloroisothiazolinone, an ammonium carbamate, bronopol or a combination thereof. 
     
     
         17 . The method of  claim 11 , wherein treating the process flow comprises adding the VFA control agent and the biocidal agent simultaneously to the process flow in a synergistically effective combined amount effective to control the production of at least one VFA in the process flow. 
     
     
         18 . The method of  claim 17 , wherein the biocidal agent comprises monochloramine (MCA), a methylchloroisothiazolinone, an ammonium carbamate, bronopol, or a combination thereof; and wherein the VFA control agent comprises at least one of an alkylbenzene sulfonate, a polyamino polyether methylene phosphonic acid (PAPEMP), a bis(hexamethylenetriaminepenta(methylene phosphonic acid)) (BHMTAP), a diethylenetriamine penta(methylene phosphonic acid) (DTPMPA) or a sodium salt thereof, and a sodium hexametaphosphate (SHMP). 
     
     
         19 . The method of  claim 18 , wherein the VFA control agent further comprises sodium bisulfite. 
     
     
         20 . 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.