| abstract |
A method of controlling starch degradation in starch-containing process water from pulp, paper or board production, comprising: treating the process water with zinc ions and a biocide, wherein the biocide is an oxidizing biocide or a non-oxidizing biocide, wherein the non-oxidizing biocide is selected from: glutaraldehyde, 2,2-dibromo-3-nitrilopropionamide (DBNPA), 2-bromo-2-nitropropane-1,3-diol (Bronopol), 5- chloro-2-methyl-4-isothiazolin-3-one (CMIT), 2-methyl-4-isothiazolin-3-one (MIT), and a combination thereof; and where the oxidizing biocide is selected from: alkaline and alkaline earth hypochlorite salts, hypochlorous acid, hypobromous acid, chlorine dioxide, peracetic acid, performic acid, percarbonate salts, persulfate salts, monohalodimethylhydantoins, dihalodimethylhydantoins, monochloramines, monobromines, dihaloamines , urea reacted with hypochlorite, ammonium salts reacted with hypochlorite, or a combination thereof. |