JP7057091B2 - Treatment method of open circulation cooling water system - Google Patents

Description

The present invention can prevent the generation of biofilms, reliably sterilize and suppress Legionella spp., And suppress the growth of drug-resistant algae, especially granular green algae, for a long period of time. The present invention relates to a method for treating an open circulation cooling water system.

In circulating water systems such as cooling water systems, biofilms cause contamination of equipment and surrounding water systems, and in cooling water systems, they cause a decrease in heat exchange efficiency, and various technical proposals have been made to suppress this. ..

Among such techniques, the applicant also proposes a slime suppression method in aqueous water in Patent Document 1. This method is a technique for adding a chemical containing a halogen-based oxide, and can suppress biofilm extremely effectively while preventing corrosion of water-based metal materials. As described above, halogen-based oxides are extremely effective in sterilizing bacteria and suppressing the growth of biofilms.

Here, in the open circulation cooling water system, in addition to suppressing biofilm, a bactericidal effect against Legionella spp. Is required.

The above halogen-based oxides show excellent bactericidal action against Legionella spp. In laboratory tests, but when the actual open circulation cooling water system is treated with halogen-based oxides, Legionella spp. In many cases, sufficient bactericidal and inhibitory effects cannot be obtained against bacteria. Surprisingly, there are some water systems that cannot kill Legionella spp. Even if the free residual chlorine concentration is maintained at 2 mg / L.

On the other hand, various organic fungicides have been used for a long time in the sterilization treatment of Legionella spp., And by adding them in high concentration or continuously adding them to the water system, Legionella spp. Are effective. It is said that it can be sterilized and suppressed. However, since such organic fungicides have a weak bactericidal and peeling effect on biofilms, even if Legionella spp. Temporarily suspended in water are not detected by intermittent treatment, they are water-based. A biofilm remains inside, which serves as a breeding ground for Legionella spp., And Legionella spp. Can be detected in water in a relatively short period of time.

In addition, compared to halogen-based oxides, organic fungicides have the disadvantage that resistant bacteria are more likely to grow, and algae resistant to organic fungicides, especially granular green algae, are more likely to grow. ..

Therefore, the applicant applies the treatment with the halogen-based oxide to the cooling water of the open circulation cooling water system proposed in Patent Documents 2 to 5 for 1 hour or more every 24 hours, and the treatment with the organic bactericide. These problems were solved by a treatment method of an open circulation cooling water system in which the above was performed at least once every 30 days.

The granular green algae are green algae having spherical cells such as chlorella and spheroxtis. Such spherical green algae tend to have strong drug resistance, and often propagate in water systems treated by the conventional treatment method as described above, which has been a problem.

Japanese Unexamined Patent Publication No. 2009-160505 Japanese Unexamined Patent Publication No. 2012-36108 Japanese Unexamined Patent Publication No. 2013-158669 Japanese Unexamined Patent Publication No. 2013-158670 Japanese Unexamined Patent Publication No. 2013-202484 Special Table 2003-503323 Gazette Special Table No. 11-506139 Gazette Japanese Unexamined Patent Publication No. 2-138103 Japanese Unexamined Patent Publication No. 5-331002

Edited by Toshitaka Nakahara, "Guidelines for Prevention of Legionellosis", 4th Edition (Editor / Publisher: Toshitaka Nakahara, Publisher :, Japan Building Hygiene Management Education Center, July 2017), pp. 32-38

The present invention solves the above-mentioned problems, that is, it is possible to prevent the generation of biofilm, sterilize and suppress Legionella spp. To a non-detectable level, and have drug resistance, especially granular green algae. It is an object of the present invention to provide a method for treating an open circulation cooling water system that suppresses the reproduction of green algae for a long period of time.

In order to solve the above-mentioned problems, the method for treating an open circulating cooling water system of the present invention comprises at least one oxidizing substance selected from chloramine T and chloramine B and an odor with respect to the cooling water of the open circulating cooling water system. A chlorine concentration maintenance treatment for maintaining the bound residual chlorine concentration in the cooling water within a predetermined range by adding a chemical solution containing sodium bromide and at least one bromine compound selected from potassium bromide 24. It is a treatment method of an open circulating cooling water system in which the sterilizing agent addition treatment of adding an organic sterilizing agent to the cooling water is carried out at least once every 30 days.
The content of the oxidizing substance in the chemical solution is 0.5% by mass or more and 20% by mass or less.
The concentration of the bromine compound in the chemical solution is 0.1 or more and 10 or less in terms of mass ratio when the concentration of the oxidizing substance in the chemical solution is 1.
The organic disinfectant
A fungicide containing 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one as isothiazolin compounds.
Fungicide containing glutaraldehyde,
A fungicide containing 1,4-bis [3,3'-(1-decylpyridinium) methyloxy] butane dibromide,
Fungicide containing poly [oxyethylene (dimethyliminio) ethylene (dimethylimilio) ethylene dichloride],
A fungicide containing a water-soluble cationic polymer obtained by the reaction of dimethylamine with epichlorohydrin, and
Fungicide containing 2-bromo-2-nitropropane-1,3-diol
It is characterized by being at least one organic fungicide selected from .

Further, in the treatment method of the open circulation cooling water system of the present invention, in addition to the above configuration, the chlorine concentration maintenance treatment reduces the oxidizing power of the cooling water to 0.1 mg / L or more and 100 mg / L or less as the combined residual chlorine concentration. It can be configured to be a process that maintains the range.

Further, the method for treating the open circulation cooling water system of the present invention may have a configuration in which the chlorine concentration maintenance treatment is constantly performed in addition to the above configuration.

Further, in the treatment method of the open circulation cooling water system of the present invention, in addition to the above configuration, the disinfectant addition treatment can be performed once every two to 30 days.

Further, in the treatment method of the open circulating cooling water system of the present invention, in addition to the above configuration, the disinfectant addition treatment is a disinfectant containing the isothiazolinone compound, and the concentration of the isothiazolinone compound is 0.1 mg / L or more and 100 mg. The configuration may include a step of adding to the cooling water so that the content is / L or less.

Further, in the treatment method of the open circulating cooling water system of the present invention, in addition to the above configuration, the bactericidal agent addition treatment makes the bactericidal agent containing the glutaraldehyde a concentration of 1 mg / L or more and 1000 mg / L or less. As such, the configuration may include a step of adding to the cooling water.

Further, in the treatment method of the open circulating cooling water system of the present invention, in addition to the above configuration, the disinfectant addition treatment is carried out by the above 1,4-bis [3,3'-(1-decylpyridinium) methyloxy] butane dibromide. The disinfectant containing the above-mentioned cooling agent is cooled so that the concentration of the 1,4-bis [3,3'-(1-decylpyridinium) methyloxy] butane dibromide is 0.1 mg / L or more and 500 mg / L or less. The configuration may include a step of adding to water.

Further, in the treatment method of the open circulating cooling water system of the present invention, in addition to the above configuration, the disinfectant addition treatment comprises a disinfectant containing the poly [oxyethylene (dimethyliminio) ethylene (dimethylimilio) ethylene dichloride]. , The step of adding the poly [oxyethylene (dimethyliminio) ethylene (dimethylimilio) ethylene dichloride] to the cooling water so that the concentration of the active ingredient is 0.1 mg / L or more and 500 mg / L or less. It can be configured to include.

Further, in the treatment method of the open circulating cooling water system of the present invention, in addition to the above configuration, the bactericidal agent containing the water-soluble cation polymer obtained by the reaction of the dimethylamine and epichlorohydrin in the bactericidal agent addition treatment. Can be configured to include a step of adding the water -soluble cationic polymer to the cooling water so that the concentration of the water-soluble cationic polymer is 0.1 mg / L or more and 500 mg / L or less.

Further, in the treatment method of the open circulating cooling water system of the present invention, in addition to the above configuration, the disinfectant addition treatment uses the disinfectant containing 2-bromo-2-nitropropane-1,3-diol. The configuration may include a step of adding to the cooling water so that the concentration of bromo-2-nitropropane-1,3-diol is 0.1 mg / L or more and 1000 mg / L or less.

According to the treatment method of the open circulation cooling water system of the present invention, at least one oxidizing substance selected from chloramine T and chloramine B, sodium bromide, and an odor with respect to the cooling water of the open circulation cooling water system. A chlorine concentration maintenance treatment for maintaining the bound residual chlorine concentration in the cooling water within a predetermined range by adding a chemical solution containing at least one bromine compound selected from potassium bromide is performed every 24 hours for 1 hour or more. Moreover , it is a treatment method of an open circulation cooling water system in which a sterilizing agent addition treatment of adding an organic sterilizing agent to the cooling water is performed at least once every 30 days.
The content of the oxidizing substance in the chemical solution is 0.5% by mass or more and 20% by mass or less.
The concentration of the bromine compound in the chemical solution is 0.1 or more and 10 or less in terms of mass ratio when the concentration of the oxidizing substance in the chemical solution is 1.
The organic disinfectant
A fungicide containing 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one as isothiazolin compounds.
Fungicide containing glutaraldehyde,
A fungicide containing 1,4-bis [3,3'-(1-decylpyridinium) methyloxy] butane dibromide,
Fungicide containing poly [oxyethylene (dimethyliminio) ethylene (dimethylimilio) ethylene dichloride],
A fungicide containing a water-soluble cationic polymer obtained by the reaction of dimethylamine with epichlorohydrin, and
The composition is at least one organic fungicide selected from fungicides containing 2-bromo-2-nitropropane-1,3-diol to prevent the formation of biofilms and ensure Legionella spp. It is possible to sterilize and suppress to a non-detection level, and it is possible to suppress the growth of drug-resistant algae, particularly granular green algae, for a long period of time. In addition, it is possible to effectively suppress the growth of amebas, which are known as hotbeds for the breeding of Legionella spp.
Further, among the above configurations, the concentration of the bromine compound in the chemical solution is 0.1 or more and 10 or less in terms of mass ratio when the concentration of the oxidizing substance in the chemical solution is 1. While the above effects are surely obtained, the chemical solution is stable, and it is possible to prevent the generation of precipitates and the like even when stored for a long period of time.
In addition, among the above configurations, the configuration in which the bromine compound is at least one selected from sodium bromide and potassium bromide makes it possible to further improve the storage stability of the chemical solution.

Further, in the treatment method of the open circulation cooling water system of the present invention, in addition to the above configuration, the chlorine concentration maintenance treatment sets the oxidizing power in the cooling water in the range of 0.1 mg / L or more and 100 mg / L or less as the combined residual chlorine concentration. It is possible to effectively prevent the corrosion of water-based equipment while surely obtaining the above-mentioned effect by the configuration which is the treatment to maintain the above.

Further, in the treatment method of the open circulation cooling water system of the present invention, it is possible to more effectively suppress the growth of granular green algae by constantly maintaining the chlorine concentration in addition to the above configuration.

Further, in the treatment method of the open circulation cooling water system of the present invention, in addition to the above configuration, the disinfectant addition treatment is performed once every two to 30 days to further enhance the effect of the present invention. be able to.

Further, in the treatment method for the open circulating cooling water system of the present invention, in addition to the above configuration, at least one of the following treatments (a) to (f) is performed as a bactericide addition treatment, whereby the effect of the present invention is obtained. Can be further enhanced.

(A) A treatment including a step of adding a bactericide containing the isothiazolin-based compound to the cooling water so that the concentration of the isothiazolin-based compound is 0.1 mg / L or more and 100 mg / L or less.

(B) A treatment including a step of adding the bactericidal agent containing the glutaraldehyde to the cooling water so that the concentration of the glutaraldehyde is 1 mg / L or more and 1000 mg / L or less.

(C) The disinfectant containing the 1,4-bis [3,3'-(1-decylpyridinium) methyloxy] butane dibromide is used as the 1,4-bis [3,3'-(1-decylpyridinium) methylpyridinium. ) Methyloxy] A treatment including a step of adding to the cooling water so that the concentration of butane dibromide is 0.1 mg / L or more and 500 mg / L or less.

(D) A bactericidal agent containing the poly [oxyethylene (dimethylimino) ethylene (dimethylimilio) ethylene dichloride] is used as an active ingredient , and the poly [oxyethylene (dimethylimilio ) ethylene (dimethylimilio) ethylene dichloride] is used as an active ingredient. ] Concentration of 0.1 mg / L or more and 500 mg / L or less, a treatment including a step of adding to the cooling water.

(E) A bactericidal agent containing a water-soluble cationic polymer obtained by the reaction of the dimethylamine with epichlorohydrin has a concentration of the water-soluble cationic polymer of 0.1 mg / L or more and 500 mg / L or less. A process including a step of adding to the cooling water so as to be.

(F) The disinfectant containing 2-bromo-2-nitropropane-1,3-diol has a concentration of 2-bromo-2-nitropropane-1,3-diol of 0.1 mg / L or more and 1000 mg /. A process including a step of adding to the cooling water so that the concentration is L or less.

The method for treating the open circulation cooling water system of the present invention will be described below.
<Oxidizing substance>
In the present invention, at least one selected from chloramine T and chloramine B is used as the oxidizing substance. Here, chloramine T has an IUPAC name of N-chloro-4-methylbenzenesulfonamide, and chloramine B has an IUPAC name of N-chlorobenzenesulfonamide. These are usually marketed as hydrates of sodium salts, but are included in the present invention regardless of the type of salt as long as they are soluble in water and exhibit oxidizing power and have an algae-suppressing effect. Examples of such salts include lithium salts, potassium salts and the like, in addition to sodium salts. Chloramine T and chloramine B exhibit oxidizing power as bound residual chlorine in water. When commercially available chloramine T and chloramine B are added to the water system, bound chlorine having a concentration of about 1/4 of the concentration added to the water system as a solid content is detected in the water. That is, when the consumption and decomposition of oxidizing power are ignored, the combined residual chlorine concentration indicated by the 4 mg / L (liter) aqueous solution of chloramine T and chloramine B is 1 mg / L.

In the present invention, by using chloramine T or chloramine B as an oxidizing substance, the storage stability of the drug solution is significantly improved as compared with sodium hypochlorite or the like. A preferred oxidizing substance is chloramine-T in terms of availability.

<Brominated compound>
Examples of the bromine compound used in the present invention include sodium bromide, potassium bromide, lithium bromide, calcium bromide, magnesium bromide, ammonium bromide and the like. Of these, it is preferable to use sodium bromide, potassium bromide, and lithium bromide from the viewpoint of storage stability, and the use of potassium bromide enables a preparation having particularly excellent storage stability.

<Chemical solution>
In a drug solution containing at least one oxidizing substance selected from chloramine T and chloramine B used in the present invention and at least one bromine compound, at least one oxidizing substance selected from chloramine T and chloramine B. The content of the substance is usually about 0.5% by mass or more and 20% by mass or less, but when it is 1% by mass or more and 15% by mass or less, the chemical solution is stable and precipitates even if left for a long period of time. It is preferable in that no object or the like is generated.

Further, in the above chemical solution, when the concentration of the bromine compound is 1 in the chemical solution of at least one oxidizing substance selected from chloramine T and chloramine B, the mass ratio is 0.1 or more and 10 or less. Then, it is preferable in that the chemical solution is stable and no precipitate or the like is generated even if it is stored for a long period of time, while ensuring the effect of the present invention. The preferred range is 0.2 or more and 5 or less.

In addition, the pH of the chemical solution is preferably 9.5 or higher in order to ensure ease of production and stability of the oxidizing substance. A more preferable pH is 10 or more, and a more preferable range is 11.5 or more and less than 13.5. As the pH adjusting agent used for adjusting the pH of the composition, a general alkaline agent can be used, and sodium hydroxide, potassium hydroxide, lithium hydroxide and the like are preferably used.

<Treatment with chemicals>
In the present invention, treatment with a chemical solution containing at least one oxidizing substance selected from chloramine T and chloramine B and at least one bromine compound, that is, to the cooling water of the open circulation cooling water system of this chemical solution. Is added every 24 hours for 1 hour or more.

In addition, instead of treating with a chemical solution containing at least one oxidizing substance selected from chloramine T and chloramine B and at least one bromine compound, the oxidizing substance and the bromide compound are separately cooled water. When added to, the effect of the present invention cannot be sufficiently obtained.

Treatment of the cooling water of the open circulation cooling water system with the above chemical solution effectively suppresses the biofilm in the water system, which is a hotbed for the growth of Legionella spp., And effectively suppresses the growth of drug-resistant algae, especially granular green algae. In order to suppress it, it is necessary to carry out at least 1 hour in 24 hours, and if the treatment is less than 1 hour in 24 hours, the effect of the present invention may not be sufficiently obtained. It is more preferable to perform this process at all times.

When the above treatment is performed intermittently for 1 hour every 24 hours or longer, the oxidizing power of the cooling water is maintained in the range of 0.1 mg / L or more and 100 mg / L or less as the bound residual chlorine concentration. In addition, the amount of addition is adjusted so that the oxidizing power in the cooling water is maintained in the range of 0.1 mg / L or more and 10 mg / L or less as the bound residual chlorine concentration in the case of continuous treatment at all times. It is preferable to do so. A more preferable maintenance concentration is the bound residual chlorine concentration in the range of 0.5 mg / L or more and 10 mg / L or less in the case of intermittent treatment, and in the range of 0.1 mg / L or more and 2 mg / L or less in the case of continuous treatment. The measured residual chlorine is carried out by a method according to JIS K0101 28, 1998. Further, as long as the method can obtain the same measurement result as the method described in JIS K0101 28 1998, the measurement may be performed using a bonded residual chlorine concentration measuring electrode or other measuring device.

<Treatment with organic fungicides>
In the treatment method for the open circulating cooling water system of the present invention, in addition to the treatment with the above-mentioned chemical solution containing the oxidizing organic fungicide and the brominated compound, the cooling water is treated with the organic fungicide once every 30 days. Do the above. If the treatment with an organic fungicide is less than once every 30 days, the effect of the present invention may not be sufficiently obtained. The treatment with an organic fungicide is preferably performed once every 2 to 30 days.

As the organic bactericidal agent used in the treatment with this organic bactericidal agent, it is preferable to use an agent having an excellent bactericidal effect against Legionella spp. In particular, when at least one of the following organic bactericidal agents (a) to (f) is added at the addition concentrations shown below, at least one oxidizing substance selected from chloramine T and chloramine B can be added. When used in combination with treatment with a chemical solution containing at least one bromine compound, it reliably suppresses the generation of biofilm with a small amount of addition, sterilizes and suppresses Green algae, and has drug resistance. It can suppress the growth of algae, especially granular green algae.

(A) 5-Chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, and 1,2 -At least one isothiazolinone compound selected from benzoisothiazolin-3-one.

It is preferable to add this thiazolin-based compound to the cooling water so that the addition concentration with respect to the retained water amount of the open circulation cooling water system is 0.1 mg / L or more and 100 mg / L or less. A more preferable addition concentration range is 1 mg / L or more and 20 mg / L or less.

(B) At least one aldehyde selected from glutaraldehyde and o-phthalaldehyde for treatment with an organic fungicide.

It is preferable to add these aldehydes to the cooling water so that the concentration of the aldehydes added to the amount of water held in the open circulation cooling water system is 1 mg / L or more and 1000 mg / L or less as the active ingredient concentration. A more preferable addition concentration range is 20 mg / L or more and 500 mg / L or less.

（ただし、上記一般式（１）において、Ｒ_１およびＲ_４は、炭素数１～４の直鎖若しくは分岐の同一または異なるアルキレン基であり、Ｒ_２およびＲ_５は、水素原子、同一または異なるハロゲン原子、低級アルキル基または低級アルコキシ基であり、Ｒ_３は、炭素数２～１２の直鎖若しくは分岐のアルキレン基であり、Ｒ_６は、炭素数１～１８の直鎖若しくは分岐のアルキル基であり、Ｚ^－は、水中で解離可能な陰イオンである。） (C) A compound represented by the following general formula (1).

(However, in the above general formula (1), R ₁ and R ₄ are linear or branched alkylene groups having 1 to 4 carbon atoms, and R ₂ and R ₅ are hydrogen atoms, which are the same or different. A halogen atom, a lower alkyl group or a lower alkoxy group, R ₃ is a linear or branched alkylene group having 2 to 12 carbon atoms, and R ₆ is a linear or branched alkyl group having 1 to 18 carbon atoms. And Z ^- is an anion that can be dissociated in water.)

It is preferable to add the compound represented by the general formula (1) to the cooling water so that the concentration of the compound represented by the general formula (1) added to the retained water amount of the open circulation cooling water system is 0.1 mg / L or more and 500 mg / L or less as the active ingredient concentration. .. A more preferable addition concentration range is 0.5 mg / L or more and 100 mg / L or less.

The effect of the present invention is further enhanced by using 1,4-bis [3,3'-(1-decylpyridinium) methyloxy] butane dibromide as the compound represented by the above general formula (1). It is preferable because it can be used.

(D) Poly [oxyethylene (dimethyliminio) ethylene (dimethylimilio) ethylene dichloride].

Poly [oxyethylene (dimethylimino) ethylene (dimethylimilio) ethylene dichloride] should be added so that the concentration of the active ingredient added to the amount of water held in the open circulation cooling water system is 0.1 mg / L or more and 500 mg / L or less. It is preferable to add it to the cooling water. A more preferable addition concentration range is 1 mg / L or more and 200 mg / L or less.

(E) A water-soluble cationic polymer obtained by the reaction of dimethylamine with epichlorohydrin. Here, the water-soluble cationic polymer obtained by the reaction of dimethylamine and epichlorohydrin is specifically a compound having a structural unit represented by the following chemical formula (2).

It is preferable to add this water-soluble cation polymer to the cooling water so that the addition concentration with respect to the retained water amount of the open circulation cooling water system is 0.1 mg / L or more and 500 mg / L or less as the active ingredient concentration. A more preferable addition concentration range is 1 mg / L or more and 200 mg / L or less.

Here, the water-soluble cationic polymer obtained by the reaction of dimethylamine and epichlorohydrin is a substance proposed in Patent Documents 8 and 9 as a composition for inhibiting the growth of microorganisms and an algae control agent. be.

(F) At least one bromonitroalcohol-based compound selected from 2,2-dibromo-2-nitroethanol and 2-bromo-2-nitropropane-1,3-diol.

It is preferable to add this bromonitroalcohol-based compound to the cooling water so that the concentration of the added component with respect to the retained water amount of the open circulation cooling water system is 0.1 mg / L or more and 1000 mg / L or less as the active ingredient concentration. A more preferable addition concentration range is 0.2 mg / L or more and 500 mg / L or less.

<Other ingredients that can be used together>
In the treatment method of the open circulation cooling water system of the present invention, chloramine T and chloramine which have been conventionally used for water treatment for the purpose of further improving the characteristics thereof within the range where the effect of the present invention is not hindered. An oxidizing substance other than B, a known organic bactericidal agent, an anticorrosion agent, and an antiscale agent can be appropriately used in combination, and these are also included in the present invention.

《Oxidizing substance》
Examples of oxidizing substances other than chloramine T and chloramine B include hypohalogenates such as sodium hypochlorite, calcium hypochlorite and sodium hypobromous acid, sodium dichloroisosianurate and trichloroisosianulic acid. Halogenated isocyanuric acid, 1-bromo-3-chloro-5,5-dimethylhydantoin, 1,3-dibromo-5,5-dimethylhydantoin, 1,3-dichloro-5,5-dimethylhydantoin, 1,3- Examples thereof include halogenated hydantoin such as dichloro-5,5-ethylmethylhydantoin, 1,3-dichloro-5,5-diethylhydantoin, stabilized hypohalogenate and the like.

As the stabilized hypochlorite, as disclosed in Patent Document 6 and Patent Document 7, stabilized hypochlorite obtained from hypochlorite and sulfamate, sodium bromide, and the like. A bromine ion source selected from one or more of potassium bromide, lithium bromide and the like, hypochlorite, and stabilized hypochlorite obtained from sulfamate can be used.

In addition, hypohalite is added to water in which ammonium ion is present to produce chloramines, or hypohalite is added to water in which sulfamic acid or a salt thereof is present. , Stabilized hypohalites may be produced.

《Organic fungicide》
The agents that can be used as the organic bactericide are not particularly limited to the organic bactericides (a) to (f) described above, and are, for example, 2,2-dibromo-3-nitrilopropionamide and 2-pyridinethiol-. 1-sodium oxide, zincpyridione, 4,5-dichloro-1,2-dithiolan-3-one, methylenebisthiocyanate, N-decyl-N-isononyl-N, N-dimethylammonium chloride, N, N'-hexamethylene Bis (4-carbamoyl-1-decylpyridinium bromide), tri-n-butyl-n-hexadecylphosphonium chloride, tri-n-butyl-n-dodecylphosphonium chloride, tetrakis (hydroxymethylphosphonium) sulfate, N, N-bis Examples thereof include (3-aminopropyl) dodecylamine, and one or more of them can be selected and used, or may be used in combination with the above-mentioned organic bactericides (a) to (f).

<< Anticorrosive agent (azole compound) >>
An azole compound is suitable as an anticorrosive agent that can be used in combination with the open circulation cooling water system treatment method of the present invention. Examples of the azole compound include monocyclic azole compounds such as imidazole, pyrazole, oxazole, thiazole, triazole and tetrazole, benzoimidazole, benzoxazole, benzoisoxazole, benzothiazole, mercaptobenzoimidazole and mercaptomethylbenzoimidazole. Condensed polycyclic azole compounds such as mercaptobenzothiazole, benzotriazole, triltriazole, indazole, purine, imidazole thiazole, and pyrazolooxazole, and in the case of compounds that form salts among azole compounds, those Examples include salt. These azole compounds may be used in combination of only one type or in combination of two or more types. Preferred azole compounds are benzotriazoles and triltriazoles in that they have a high effect of suppressing the decomposition of oxidizing substances.

Examples of the anticorrosion agent other than the azole compound that can be used in combination in the treatment method of the open circulating cooling water system of the present invention include phosphoric acid or a salt thereof, polymerized phosphoric acid such as pyrophosphate, tripolyphosphate, hexamethaphosphate or a salt thereof, and zinc. Examples thereof include salt, molybdic acid or a salt thereof, tungstate acid or a salt thereof, gluconic acid, citric acid, tartaric acid, phytic acid, sucrose, lactic acid and other organic carboxylic acids or salts thereof.

<< Anti-scale agent >>
Examples of the antiscale agent that can be used in combination in the treatment method of the open circulating cooling water system of the present invention include 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid and aminotrimethylene. Phosphonic acids such as phosphonic acid and water-soluble salts thereof, acrylic acid-based, maleic acid-based, methacrylic acid-based, sulfonic acid-based, itaconic acid-based, or isobutylene-based polymers and polymers such as copolymers thereof. Examples thereof include phosphinocarboxylic acids such as hypophosphite adducts of acrylic acid-based polymers, aminocarboxylic acid-based compounds such as nitrilotriacetic acid, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid. Among them, 2-phosphonobutane-1,2,4-tricarboxylic acid or a water-soluble salt thereof, maleic acid, alkyl acrylate, ternary copolymer of vinyl acetate, hypophosphorous acid adduct of polyacrylic acid, acrylic. When at least one anti-scale agent selected from the hypophosphorous acid adduct of the copolymer of the acid and 2-acrylamide-2-methylpropanesulfonic acid is used, the decomposition of the oxidizing substance by the combined anti-scale agent is used. Is preferable because there is almost no.

Although the present invention has been described above with reference to preferred embodiments, the method for treating the open circulation cooling water system of the present invention is not limited to the configuration of the above embodiment.

Those skilled in the art can appropriately modify the treatment method of the open circulation cooling water system of the present invention according to the conventionally known knowledge. Even with such a modification, it is, of course, included in the category of the present invention as long as it has the configuration of the treatment method of the open circulation cooling water system of the present invention.

Hereinafter, examples of the treatment method for the open circulation cooling water system of the present invention will be specifically described, but the present invention is not limited to these examples.

<Evaluation by cooling tower simulation test device 1>
Cooling tower simulated test equipment (installed outdoors in the sun (however, except for the upper water tank, covered with a black curtain to prevent direct sunlight), holding water amount: 60 L, cooling water: circulated by a pump, water temperature with an electric heater The test was carried out using 8 units (adjusted to 35 ° C.) using the chemicals and bactericides shown in Table 1. In Table 1, chloramine T is N-chloro-4-methylbenzenesulfonamide sodium hydrate, and chloramine B is N-chlorobenzenesulfonamide sodium hydrate (hereinafter, the same applies).

<Test and its results>
The mock test devices 1 to 8 were operated for 2 months under the drug injection conditions shown in Table 2. Here, in Table 2, "CL" is the maintenance concentration (mg / L) of the bound residual chlorine in the cooling water during the test period, and in this test, the treatment with a chemical solution was always carried out. Further, in the simulated test apparatus 8, the same mass of the chemical solution was directly added to the cooling water without mixing the chemical solution 5a and the chemical solution 5b in advance. In Table 2, "concentration of addition of fungicide" indicates the concentration of addition of the active ingredient of each fungicide with respect to the amount of water possessed. In addition, a white non-woven fabric for observing the occurrence of algae was installed in the upper water tank of each test device, and then the test was started.

The results are also shown in Table 2. In Table 2, "Biofilm generation" is the result of visually observing the adhesion of biofilm to the packing material of the cooling tower at the end of the test, and "Number of Legionella spp." Is in 100 mL of cooling water collected immediately before the end of the test. The number of Legionella spp. And "Algae outbreak" indicate the state at the end of the test of the white non-woven fabric installed in the upper water tank. If there is a slight amount of algae, it is indicated as "±", and if algae are attached, it is indicated as "+" to "++++" (the larger the number of "+", the larger the amount of attached algae). The bound residual chlorine concentration was in accordance with JIS K0101 28 and 1998, and the inspection of Legionella spp. Was carried out in accordance with the culture method described in Non-Patent Document 1.

From Table 2, in the tests with the cooling tower simulated test devices 1 to 6 corresponding to the present invention, it was found that the inhibitory effect on biofilm, Legionella spp., And algae was sufficiently exhibited, while chloramine T and In the test with the cooling tower simulated test device 7 to which the stabilized sodium hypochlorite preparation was added as an oxidizing substance instead of the chemical solution containing chloramine B and the bromine compound, the growth of Legionella spp. And the generation of algae were sufficient. In the test with the cooling tower simulated test device 8 to which chloramine T and bromine compound were added separately, the suppression effect on biofilm and Legionella spp. Was sufficiently obtained, but the suppression of algae was insufficient. Is understood to be. By observation with a microscope, it was confirmed that the algae generated in the apparatus 7 and the apparatus 8 were granular green algae.

Instead of the disinfectant 1, an aqueous solution containing 3% by mass of 2-n-octyl-4-isothiazolin-3-one, an aqueous solution containing 5% by mass of 1,2-benzoisothiazolin-3-one, and o-phthal. The test was carried out under the same conditions as in the apparatus 1 of Table 2 except that an aqueous solution containing 5% by mass of aldehyde and an aqueous solution containing 10% by mass of 2,2-dibromo-2-nitroethanol were used. It was confirmed that the growth of biofilm, Legionella spp., And algae was suppressed even under the conditions.

<Evaluation by cooling tower simulation test device 2>
Similar to the evaluation 1 by the above cooling tower simulated test device, however, the test was conducted with the chemical injection conditions as shown in Table 3. Here, in Table 3, "treatment time with chemical solution" indicates the addition time of chemical solution per 24 hours a day, and "twice / week" of "frequency of addition of fungicide" is sterilized every Monday and Thursday. It indicates that the agent was added. The test results are also shown in Table 3.

According to Table 3, in the tests with the cooling tower simulated test devices 1 to 6 corresponding to the present invention, even if the concentration and frequency of addition of the chemical solution and the bactericidal agent are changed, the biofilm and Legionella spp. , And it is understood that the inhibitory effect on algae is sufficiently exerted. On the other hand, in the tests with the cooling tower simulated test devices 7 and 8 in which chloramine T and the bromine compound are added separately without being mixed in advance, the inhibitory effect on algae is insufficient. By observation with a microscope, it was confirmed that the algae generated in the apparatus 7 and the apparatus 8 were granular green algae.

Although the cause of such a difference in effect is not clear, by premixing chloramine T or chloramine B with a bromine compound, at least a part of chloramine T or chloramine B is brominated and N-brom-4- This is because methylbenzene sulfonamide and N-brombenzene sulfonamide are produced, and this substance exerts a significantly superior effect on the growth suppression of granular green algae as compared with chloramine T and chloramine B before the reaction. presume. The present inventors consider that when they are added separately to the cooling water without premixing, chloramine T and chloramine B react with microorganisms faster than bromization, so that the desired effect cannot be obtained.

<Examination of actual cooling water system>
The chemicals shown in Table 1 for 5 months from mid-April to mid-September with two cooling tower equipment (refrigeration capacity 500RT, water capacity 10m ³ , installed in a sunny place) in a certain factory in Ibaraki Prefecture. Comparison of the effects of the combined treatment of 1 and the disinfectant 1 (treatment 1), the treatment of adding the chemical solution 5a and the chemical solution 5b to the cooling water without premixing, and the combined treatment of the chemical solution 1 (treatment 2). A test was performed. During the period, the combined residual chlorine concentration in the cooling water was maintained in the range of 0.1 to 0.5 mg / L, and the disinfectant 1 was added so that the concentration added to the amount of retained water was 2 mg / L as the active ingredient concentration. It was added once a week.

As a result, no biofilm adhered to the cooling tower filler even after 5 months, and all Legionella spp. Were not detected (less than 10/100 mL) during the period, but in treatment 1, No algae were found in the upper water tank of the cooling tower, and the number of amoeba in the cooling water was maintained at 10/100 mL, whereas in treatment 2, granular green algae were observed in the upper water tank from the 4th month. As for the number of amoeba, more than 10/100 mL was detected in the 5th month.

As described above, the cooling water of the open circulation cooling water system is treated with a chemical solution containing at least one oxidizing substance selected from chloramine T and chloramine B and at least one bromine compound and organic. By using the treatment with a system bactericide in combination under appropriate conditions, it is possible to effectively suppress the growth of algae, especially granular green algae, as compared with the case where an oxidizing substance and a bromine compound are added separately to the cooling water. As a whole, it is possible to suppress the generation of biofilms, the growth of Legionella spp., And the growth of algae, and keep the cooling water system in good condition for a long period of time.

Claims (10)

For the cooling water of the open circulation cooling water system, at least one oxidizing substance selected from chloramine T and chloramine B , and at least one bromine compound selected from sodium bromide and potassium bromide . The chlorine concentration maintenance treatment for maintaining the combined residual chlorine concentration in the cooling water within a predetermined range by adding a chemical solution containing the above-mentioned is carried out for 1 hour or more every 24 hours, and an organic bactericidal agent is applied to the cooling water. It is a treatment method of an open circulation cooling water system in which the addition treatment of the bactericide to be added is performed at least once every 30 days.
The content of the oxidizing substance in the chemical solution is 0.5% by mass or more and 20% by mass or less.
The concentration of the bromine compound in the chemical solution is 0.1 or more and 10 or less in terms of mass ratio when the concentration of the oxidizing substance in the chemical solution is 1.
The organic disinfectant
A fungicide containing 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one as isothiazolin compounds.
Fungicide containing glutaraldehyde,
A fungicide containing 1,4-bis [3,3'-(1-decylpyridinium) methyloxy] butane dibromide,
Fungicide containing poly [oxyethylene (dimethyliminio) ethylene (dimethylimilio) ethylene dichloride],
A fungicide containing a water-soluble cationic polymer obtained by the reaction of dimethylamine with epichlorohydrin, and
Fungicide containing 2-bromo-2-nitropropane-1,3-diol
A method for treating an open circulating cooling water system, which is an organic bactericide selected from the above . The opening according to claim 1, wherein the chlorine concentration maintaining treatment is a treatment for maintaining the oxidizing power in the cooling water in the range of 0.1 mg / L or more and 100 mg / L or less as the bound residual chlorine concentration. Treatment method for circulating cooling water system. The method for treating an open circulating cooling water system according to claim 1 or 2 , wherein the chlorine concentration maintenance treatment is constantly performed. The method for treating an open circulating cooling water system according to any one of claims 1 to 3 , wherein the disinfectant addition treatment is performed once every 2 to 30 days. The bactericidal agent addition treatment includes a step of adding the bactericidal agent containing the isothiazolinone compound to the cooling water so that the concentration of the isothiazolinone compound is 0.1 mg / L or more and 100 mg / L or less. The method for treating an open circulating cooling water system according to any one of claims 1 to 4 , which is characteristic. The claim comprising the step of adding the bactericidal agent containing the glutaraldehyde to the cooling water so that the concentration of the glutaraldehyde is 1 mg / L or more and 1000 mg / L or less. The method for treating an open circulating cooling water system according to any one of Items 1 to 5 . The disinfectant addition treatment is a disinfectant containing the 1,4-bis [3,3'-(1-decylpyridinium) methyloxy] butane dibromide, and the 1,4-bis [3,3'-( 1-Decilpyridinium) Methyloxy] Claims 1 to 6 include a step of adding butane dibromide to the cooling water so that the concentration is 0.1 mg / L or more and 500 mg / L or less. The method for treating an open circulation cooling water system according to any one of the above items. The disinfectant addition treatment uses the disinfectant containing the poly [oxyethylene (dimethyliminio) ethylene (dimethylimilio) ethylene dichloride] as the active ingredient of the poly [oxyethylene (dimethylimilio) ethylene (dimethyli). The item according to any one of claims 1 to 7 , wherein the step of adding to the cooling water is included so that the concentration of [minio) ethylene dichloride] is 0.1 mg / L or more and 500 mg / L or less. The method for treating an open circulating cooling water system described. The bactericidal agent addition treatment is a bactericidal agent containing a water-soluble cationic polymer obtained by the reaction of the dimethylamine with epichlorohydrin, and the concentration of the water-soluble cation polymer is 0.1 mg / L or more and 500 mg. The method for treating an open circulating cooling water system according to any one of claims 1 to 8 , wherein the step of adding to the cooling water is included so as to be / L or less. The disinfectant addition treatment is a disinfectant containing the 2-bromo-2-nitropropane-1,3-diol, and the concentration of the 2-bromo-2-nitropropane-1,3-diol is 0.1 mg / The method for treating an open circulating cooling water system according to any one of claims 1 to 9 , further comprising a step of adding the cooling water to L or more and 1000 mg / L or less.