Synergistic composition and method for inhibiting growth of microorganisms

1. A composition for inhibiting the growth of microorganisms comprising effective amounts of:

a first oxidizing composition comprising hydantoin stabilized hypochlorite,

long loop white water from a paper pulping process, and

a second oxidizing composition comprising peracetic acid or salts thereof;

wherein the hydantoin stabilized hypochlorite comprises a hypochlorite portion and a hydantoin portion, the hypochlorite portion of the hydantoin stabilized hypochlorite comprises an alkali- or alkaline salt of hypochlorite, the hydantoin portion of the hydantoin stabilized hypochlorite comprises a hydantoin-based halide or hydantoin represented by formula (1):

wherein:

R 1 is the same or different; when different it independently represents H or OR 4 , wherein R 4 is H, halogen, or alkyl of 1 to 5 carbon atoms, and

R 2 and R 3 are the same or different; when different they independently represent H or alkyl of 1 to 5 carbon atoms;

and

peracetic acid and the hydantoin stabilized hypochlorite are at a total concentration of about 25 ppm or less;

peracetic acid and the hydantoin stabilized hypochlorite are in a molar ratio of at least about 1 to 1; and

the composition displays a synergy index of less than 1.

2. The composition of claim 1 , further comprising a halogen based hydantoin.

3. The composition of claim 1 , further comprising a hydantoin chlorite.

4. The composition of claim 1 , wherein R 1 of formula (1) are each H, R 2 and R 3 are different and independently C 1 to C 5 alkyl and the hypochlorite portion is sodium hypochlorite.

5. The composition of claim 1 , in which the hydantoin portion is a dialkyl hydantoin.

6. The composition of claim 1 , in which the composition displays a synergy index of less than 0.98.

7. The composition of claim 1 , used to control slime deposition in industrial water systems.

8. The composition of claim 1 , used to control growth of filamentous bacteria in industrial water systems.

9. The composition of claim 1 , used to control slime deposition in a papermaking process.

10. The composition of claim 1 , further comprising a fast acting biocide.

11. The composition of claim 1 , wherein the composition displays at least a 2-log reduction in bacterial count within 50 minutes of formation of the composition.

12. The composition of claim 1 , wherein the composition displays at least a 3-log reduction in bacterial count within 50 minutes of formation of the composition.

13. The composition of claim 1 , wherein the composition displays at least a 3-log reduction in bacterial count within 30 minutes of formation of the composition.

14. The composition of claim 1 , wherein the composition displays at least a 4-log reduction in bacterial count within 30 minutes of formation of the composition.

15. The composition of claim 1 , wherein the hydantoin stabilized hypochlorite is at a concentration of about 2.5 ppm or less.

16. The composition of claim 1 , wherein peracetic acid and the hydantoin stabilized hypochlorite are in a molar ratio of at least about 12 to about 1.

17. The composition of claim 1 , used to control bacterial growth in a mechanical pulping process.

18. The composition of claim 1 , used to control bacterial growth in a chemical pulping process.