Method of controlling enzymatic activities and tools related thereto

1 . A method of monitoring and controlling cellulolytic activity in an aqueous cellulose fiber suspension or process water for a production method of a fibrous web containing cellulose fibers, wherein the method comprises

determining cellulolytic activity in the aqueous cellulose fiber suspension comprising recycled cellulose fibers or process water for the production method of the fibrous web containing recycled cellulose fibers,

comparing the determined cellulolytic activity to a pre-determined cellulolytic activity value, and

controlling cellulolytic activity by treating the aqueous cellulose fiber suspension or process water with one or more biocides one or more times if the determined cellulolytic activity is above the pre-determined cellulolytic activity value.

2 . The method of claim 1 , wherein determining cellulolytic activity comprises determining cellulolytic activity of a sample obtained from the aqueous cellulose fiber suspension or the process water.

3 . The method of claim 1 , wherein determining cellulolytic activity comprises determining cellulolytic or cellulase activity, cellulases, and/or cellulolytic microbes in the aqueous fiber suspension or the process water.

4 . The method of claim 3 , wherein cellulolytic microbes are determined with a nucleic acid-based method.

5 . The method of claim 1 , wherein the cellulolytic activity is determined before an inlet of an intermediate residence entity, in the intermediate residence entity, and/or after an outlet of an intermediate residence entity.

6 . The method of claim 1 , wherein the cellulolytic activity is microbial or bacterial cellulolytic activity.

7 . The method of claim 6 , wherein cellulolytic microbe(s) is (are) selected from the group consisting of bacterial phyla Actinobacteria, Bacteroidetes, Firmicutes, orders Corynebacteriales, Micrococcales, Bacteroidales, Bacillales, Lactobacillies, Clostridiales, Thermoanaerobacterales, Betaproteobacteriales, Xanthomonadales, and any family or genus belonging to said phyla or orders.

8 . The method of claim 1 , wherein

the cellulolytic activity is controlled to a cellulolytic or cellulase activity level 0-1.0 mU/ml of the aqueous fiber suspension or process water, to a cellulolytic microbe level 0-1×10 9 microbes in ml of the aqueous fiber suspension or process water, and/or to a cellulolytic microbe level 0-25% of the total microbes in the aqueous fiber suspension or process water; or

the cellulolytic activity is controlled by decreasing a cellulolytic or cellulase activity at least 5% (mU/ml of the aqueous fiber suspension or process water) and/or a cellulolytic microbe level at least 5% (microbes in ml of the aqueous fiber suspension or process water).

9 . The method of claim 1 , wherein the cellulolytic activity is controlled for improving or maintaining the strength of fibers or the fibrous web.

10 . The method of claim 1 , wherein the aqueous fiber suspension is in or from an intermediate residence entity with a delay time of 1-48 hours.

11 . The method of claim 1 , wherein the consistency of the aqueous fiber suspension in an intermediate residence entity is at least 2 g/l.

12 . The method of claim 1 , wherein the aqueous fiber suspension comprises recycled fibers or the fibers of the aqueous fiber suspension are recycled fibers.

13 . The method of claim 1 , wherein the one or more biocides are selected from oxidizing biocides and non-oxidizing biocides.

14 . The method of claim 1 , wherein

the one or more biocides is a non-oxidizing biocide selected from the group consisting of: 2,2-Dibromo-3-nitrilopropionamide (DBNPA); 2-Bromo-2-nitropropane-1,3-diol (Bronopol); 2-Bromo-2-nitro-propan-1-ol (BNP); 2,2-Dibromo-2-cyano-N-(3-hydroxypropyl) acetamide; 2,2-Dibromomalonamide; 1,2-Dibromo-2,4-dicyanobutane (DCB); Bis(trichloromethyl) sulfone; 2-Bromo-2-nitrostyrene (BNS); Didecyl-dimethylammonium chlorine (DDAC); ADBAC and other quaternary ammonium compounds; 3-Iodopropynyl-N-butylcarbamate (IPBC); Methyl and Dimethyl-thiocarbamates and their salts; 5-Chloro-2-methyl-4-isothiazolin-3-one (CMIT); 2-Methyl-4-isothiazolin-3-one (MIT) and their mixture; 2-n-Octyl-4-isothiazolin-3-one (OIT); 4,5-Dichloro-2-(n-octyl)-3 (2H)-isothiazolone (DCOIT); 4,5-Dichloro-1,2-dithiol-3-one; 1,2-Benzisothiazolin-3-one (BIT); 2-(Thiocyanomethylthio)benzthiazole (TCMBT); 2-Methyl-1,2-benzisothiazolin-3 (2H)-one (MBIT); Tetrakis hydroxymethyl phosphonium sulfate (THPS); Tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione (Dazomet); Methylene bisthiocyanate (MBT); Ortho-phenylphenol (OPP) and its salts; Glutaraldehyde; Ortho-phthaldehyde (OPA); Guanidines and biguanidines; N-dodecylamine or n-dodecylguanidine; dodecylamine salt or dodecylguanidine salt; Bis-(3-aminopropyl) dodecylamine; Pyrithiones; Triazines; 3-[(4-Methylphenyl) sulfonyl]-2-propenenitrile; 3-Phenylsulphonyl-2-propenenitrile; 3-[(4-trifluormethylphenyl)sulphonyl]-2-propenenitrile; 3-[(2,4,6-trimethylphenyl)sulphonyl]-2-propenenitrile; 3-(4-methoxyphenyl)sulphonyl-2-propenenitrile; 3-[(4-methylphenyl)sulphonyl]prop-2-enamide; any of their isomers; and any combination thereof; and/or

the one or more biocides is an oxidizing biocide and selected from the group consisting of: chlorine; alkali and alkaline earth hypochlorite salts; hypochlorous acid; bromine; alkali and alkaline earth hypobromite salts; hypobromous acid; chlorine dioxide; ozone; hydrogen peroxide; peroxy compounds; halogenated hydantoins; dihalodimethylhydantoins; perhalogenated hydantoins; monochloramines; monobromamines; dihaloamines; trihaloamines; urea reacted with an oxidant; and ammonium salts reacted with an oxidant.

15 . The method of claim 14 , wherein the at least one of the one or more biocides is a non-oxidizing biocide selected from the group consisting of: dodecylguanidine hydrochloride; Zinc pyrithione; Hexahydro-1,3,5-trimethyl-1,3,5-triazine; and combinations thereof, and/or wherein the at least one of the at least one biocides is an oxidizing biocide selected from the group consisting of: performic acid; peracetic acid; percarbonate, persulfate;

monohalodimethylhydantoins; urea reacted with an oxidant, the oxidant being alkali and alkaline earth hypochlorite salts or alkali and alkaline earth hypobromite salts; ammonium bromide, ammonium sulfate or ammonium carbamate, reacted with an oxidant, the oxidant being alkali and alkaline earth hypochlorite salts or alkali and alkaline earth hypobromite salts, and combinations thereof.

16 . The method of claim 1 , wherein the aqueous cellulose fiber suspension or process water is treated with a combination of the one or more biocides and zinc ions.

17 . A method of manufacturing a fibrous web, wherein the method comprises

forming an aqueous fiber suspension comprising recycled cellulosic fibers from one or more raw material flows and/or process water,

determining cellulolytic activity of the aqueous cellulose fiber suspension, raw material flow and/or process water,

comparing the determined cellulolytic activity to a pre-determined cellulolytic activity value,

controlling cellulolytic activity by treating the aqueous cellulose fiber suspension or process water with one or more biocides one or more times if the determined cellulolytic activity is above the pre-determined cellulolytic activity value, and

forming the aqueous cellulose fiber suspension into a fibrous web and drying the fibrous web.

18 . The method of claim 17 , wherein the fibrous web comprises a paper, board, or tissue.