# US 5,702,684 A · Method of use of compositions of biocides and fluorescent indicators to control microbial growth

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- Number: US 5,702,684 A
- Document ID: US5702684A
- Status: Granted
- Kind: A
- Application number: 08/557,882
- Filed: 1995-11-14
- Granted: 1997-12-30
- Earliest claimed: 1994-05-02
- Assignees: Nalco Chemical Company
- Inventors: William F. McCoy; John E. Hoots
- Web page: https://patentgrep.com/patent/US5702684A

## CPC

- G01N 21/643: {non-biological material}
- A01N 61/00: Biocides, pest repellants or attractants, or plant growth regulators containing substances of unknown or undetermined composition, e.g. substances characterised only by the mode of action
- C02F 1/50: by addition or application of a germicide or by oligodynamic treatment {(C02F1/4606, C02F1/467, C02F1/76 take precedence)}
- G01N 33/1813: {Specific cations in water, e.g. heavy metals}
- Y10S 210/931: Zebra mussel mitigation or treatment
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- A01N: PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF (preservation of food or foodstuff A23); BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES (preparations for medical, dental or toiletry purposes which kill or prevent the growth or proliferation of unwanted organisms A61K); PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A concentration of microbiocides added to fluid systems is monitored by a fluorescence emission method which is based upon the measurement of the fluorescence intensity of an inert fluorescent additive which is added to the microbiocide composition prior to its introduction into the fluid system. Optionally, the fluorescent additive may be metered separately into the fluid system in direct proportion to the amount of industrial microbiocide added. Biocide compositions containing inert fluorescent additives are also disclosed. Preferably the fluid system is an industrial aqueous system. Preferred combinations of biocide and fluorescent additive are glutaraldehyde/1,5-naphthalene disulfonic acid, glutaraldehyde/1,3,6,8-pyrene tetrasulfonic acid, isothiazolone/1,5-naphthalene disulfonic acid, isothiazolone/1,3,6,8-pyrene tetrasulfonic acid, glutaraldehyde/fluorescein, alkyl-dimethylbenzyl ammonium chloride quaternary/2-naphthalene sulfonic acid and 2-(decylthio)-ethanamine/2-naphthalene sulfonic acid.

## Claims

### Claim 1

A method for controlling the feed rate of an aqueous biocide for controlling growth of microbiological organisms into an aqueous system containing said microbiological organisms which comprises the steps of:
a) adding to said system a known amount of a biocide/inert fluorescent compound combination selected from the group consisting of glutaraldehyde/1,5 naphthalene disulfonic acid, glutaraldehyde/1,3,6,8 pyrene tetrasulfonic acid, mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one/1,5 naphthalene disulfonic acid, mixture of 5-chloro-2-methyl-4-isothiazolin-3-one/1,3,6,8 pyrene tetrasulfonic acid, glutaraldehyde/fluorescein, alkyl dimethyl benzyl ammonium chloride quaternary/2-naphthalene sulfonic acid and 2-(decylthio)-ethanamine/2-naphthalene sulfonic acid, wherein said inert fluorescent compound is present in from 0.0005 to 10 percent by weight based on the weight of active biocide in a weight ratio of active biocide to inert fluorescent compound of from 3:1 to 1000:1, said biocide being added at a level to provide a system having a biocide dosage at or slightly greater than the minimum inhibitory concentration for said biocide in the system;
b) measuring the fluorescence of said inert fluorescent compound; and
c) maintaining the fluorescence in the system at a constant rate equal to the fluorescence at or slightly greater than the minimum inhibitory concentration of the biocide by adding additional biocide as required.

### Claim 2 (depends on 1)

The method of claim 1 wherein from 0.005 to 2.0 percent by weight of the inert fluorescent compound is added based on the weight of active biocide.

### Claim 3 (depends on 1)

The method of claim 1 wherein from 0.025 to 1.0 percent by weight of the inert fluorescent compound is added based on the weight of active biocide.

### Claim 4 (depends on 1)

The method claim 1 wherein the measurement of the fluorescence of the inert fluorescent compound is continuously monitored by a fluorometer.

### Claim 5 (depends on 4)

The method of claim 4 wherein the fluorometer signals a biocide feed pump to turn on in response to levels of fluorescence below a set treatment level, and signals the pump to mm off in response to levels of fluorescence above a set treatment level.

### Claim 6 (depends on 1)

The method of claim 1 wherein the aqueous system is selected from the group consisting of recreational water systems, paper mill white water systems, industrial water systems and open recirculating cooling systems.

### Claim 7

A method for determining the consumption of biocide for controlling growth of microbiological organisms within a fluid system containing said microbiological organisms which comprises the steps of:
a) adding to said fluid system containing microbiological organisms an amount of a composition comprising a biocide/inert fluorescent compound combination of a known weight ratio selected from the group consisting of glutaraldehyde/1,5 naphthalene disulfonic acid, glutaraldehyde/1,3,6,8 pyrene tetrasulfonic acid, mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one/1,5 naphthalene disulfonic acid, mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one/1,3,6,8 pyrene tetrasulfonic acid, glutaraldehyde/fluorescein, alkyl dimethyl benzyl ammonium chloride quaternary/2-naphthalene sulfonic acid and 2-(decylthio)-ethanamine/2-naphthalene sulfonic acid, wherein said inert fluorescent compound is present in from 0.0005 to 10 percent by weight based on the weight of active biocide;
b) determining the amount of biocide added to the system at an initial time by measuring the intensity of the fluorescence of the fluorescent compound present in the system and calculating the mount of biocide using the known weight ratio;
c) determining the amount of biocide present in the system at a second time by measuring the intensity of the fluorescence of the fluorescent compound and calculating the amount of biocide at said second time using the known weight ratio; and
d) subtracting the actual amount of biocide present as determined in step (c) from the total amount of biocide added as determined in step (b), which yields the amount of biocide consumed.

### Claim 8 (depends on 7)

The method of claim 7 wherein from 0.005 to 2.0 percent by weight of the inert fluorescent compound is added based on the weight of active biocide.

### Claim 9 (depends on 7)

The method of claim 7 wherein from 0.025 to 1.0 percent by weight of the inert fluorescent compound is added based on the weight of active biocide.

### Claim 10 (depends on 7)

The method of claim 7 wherein the system is an aqueous system.

### Claim 11 (depends on 10)

The method of claim 10 wherein the aqueous system is selected from the group consisting of recreational water systems, paper mill white water systems, industrial water systems and open recirculating cooling systems.

### Claim 12 (depends on 7)

The method of claim 7 wherein the inert fluorescent compound is added to the biocide at a level to obtain a 0.005 to 1.0% weight percent of the fluorescent compound.

### Claim 13

A method for maintaining the concentration of a biocide for controlling growth of microbiological organisms in an industrial fluid system containing said microbiological organisms which comprises the steps of:
a) adding to said industrial fluid system containing microbiological organisms an amount of a composition comprising a biocide/inert fluorescent compound combination of a known weight ratio selected from the group consisting of glutaraldehyde/1,5 naphthalene disulfonic acid, glutaraldehyde/1,3,6,8 pyrene tetrasulfonic acid, mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one/1,5 naphthalene disulfonic acid, mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one/1,3,6,8 pyrene tetrasulfonic acid, glutaraldehyde/fluorescein, alkyl dimethyl benzyl ammonium chloride quaternary/2-naphthalene sulfonic acid and 2-(decylthio)-ethanamine/2-naphthalene sulfonic acid, wherein said inert fluorescent compound is present in from 0.0005 to 10 percent by weight based on the weight of active biocide;
b) determining the amount of biocide added to the system at an initial time by measuring the intensity of the fluorescence of the inert fluorescent compound present in the system and calculating the amount of biocide using the known weight ratio;
c) determining the amount of biocide present in the system at a second time by measuring the intensity of the fluorescence of the fluorescent compound and calculating the amount of biocide at said second time using the known weight ratio;
d) subtracting the actual amount of biocide present as determined in step (c) from the total amount of biocide added as determined in step (b), which yields the amount of biocide consumed; and
e) adding to the industrial fluid system an amount of biocide to maintain the biocide at a specified concentration which inhibits microbial growth.

### Claim 14 (depends on 13)

The method of claim 13 wherein from 0.005 to 2.0 percent by weight of the inert fluorescent compound is added based on the weight of active biocide.

### Claim 15 (depends on 13)

The method of claim 13 wherein from 0.025 to 1.0 percent by weight of the inert fluorescent compound is added based on the weight of active biocide.

### Claim 16 (depends on 13)

The method of claim 13 wherein the industrial fluid system is an aqueous system.

### Claim 17 (depends on 16)

The method of claim 16 wherein the aqueous system is selected from the group consisting of recreational water systems, paper mill white water systems and open recirculating cooling systems.

### Claim 18 (depends on 13)

The method of claim 13 wherein the inert fluorescent compound is added to the biocide at a level to obtain a 0.005 to 1.0 weight percent of the fluorescent compound based on biocide active ingredients.