Biocidal methods and compositions for recirculating water systems

A solid biocidal composition for use in recirculating water systems, comprising a hypochlorite donor and a bromide ion donor:

• (i) wherein said biocidal composition contains a biocidally effective amount of the bromide ion donor in amounts sufficient to make said composition perform as a bromine biocide in said recirculating water system and to maintain a mole ratio of the sum of all bromine containing species to the sum of all hypohalite species in the recirculating water of about 0.2 to about 20;
• (ii) wherein said hypochlorite donor is selected from
• the group consisting of trichloro-s-triazinetrione, dichloroisocyanuric acid, [mono(trichloro)-tetra(monopotassium dichloro)]-penta-s-triazinetrione, [mono(trichloro)-mono(monopotassium dichloro)]-di-s-triazinetrione, or mixtures thereof;
• and
• (iii) said bromide ion donor is an N-brominated hydantoin.

A method of controlling biofouling and microorganism population levels in a recirculating water system comprising (a) determining the rate of loss of bromide ion from the system due to blow-down, volatilization and formation of stable organobromine compounds;

• and (b) adding, in a biocidally effective amount to provide prolonged and controlled release of hypobromous acid and to maintain the mole ratio of the sum of all bromine containing species to the sum of all hypohalite species in the recirculating water in the range of at least about 0.2 to about 20, a solid biocidal composition comprising a hypochlorite donor and a bromide ion donor in amounts sufficient to make said composition perform as a bromine biocide in said recirculating water system,
• (i) wherein said hypochlorite donor is selected from the group consisting of trichloro-s-triazinetrione, dichloroisocyanuric acid, or mixtures thereof;
• and
• (ii) wherein said bromide ion donor is sodium bromide.

A method of providing prolonged and controlled release of hypobromous acid in a recirculating water system in a biocidally effective amount to maintain the mole ratio of the sum of all bromine containing species to the sum of all hypohalite species in the recirculating water in the range of at least about 0.2 to about 20, comprising

• (i) determining the rate of loss of bromide ion from the system due to blow-down, volatilization and formation of stable organobromine compounds;
• and
• (ii) adding to the system a solid biocidal composition comprising a hypochlorite donor and a bromide ion donor in amounts sufficient to make said composition perform as a bromine biocide in said recirculating water system;
• (iii) wherein said hypochlorite donor is selected from the group consisting of trichloro-s-triazinetrione, dichloroisocyanuric acid, or mixtures thereof;
• and
• (iv) wherein said bromide ion donor is sodium bromide.

A method of maintaining the bromine concentration in a recirculating water system in a mole ratio of the sum of all bromine containing species to the sum of all hypohalite species in a recirculating water system in the range of at least about 0.2 to about 20 comprising:

• (i) determining the rate of loss of bromide ion from the system due to blow-down, volatilization and formation of stable organobromine compounds;
• and
• (ii) adding to the system a solid composition comprising a hypochlorite donor and a bromide ion donor in amounts sufficient to make said composition perform as a bromine biocide in said recirculating water system;
• (iii) wherein said hypochlorite donor is selected from the group consisting of trichloro-s-triazinetrione, dichloroisocyanuric acid, or mixtures thereof;
• and
• (iv) wherein said bromide ion donor is sodium bromide.

A method of controlling biofouling and microorganism population levels in a recirculating water system comprising (a) determining the rate of loss of bromide ion from the system due to blow-down, volatilization and formation of stable organobromine compounds;

• and (b) adding, in a biocidally effective amount to provide prolonged and controlled release of hypobromous acid and to maintain the mole ratio of the sum of all bromine containing species to the sum of all hypohalite species in the recirculating water in the range of at least about 0.2 to about 20, a solid biocidal composition comprising a hypochlorite donor and a bromide ion donor in amounts sufficient to make said composition perform as a bromine biocide in said recirculating water system,
• (i) wherein said hypochlorite donor is selected from the group consisting of trichloro-s-triazinetrione, dichloroisocyanuric acid, [mono(trichloro)-tetra(monopotassium dichloro)]-penta-s-triazinetrione, [mono(trichloro)-mono(monopotassiumdichloro)]-di-s-triazinetrione, or mixtures thereof;
• and
• (ii) wherein said bromide ion donor is an N-brominated hydantoin.