JP2003104804A - Method for pasteurizing microorganism in water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for pasteurizing microorganisms in water by using available chlorine and/or bromine, inhibiting slime disturbances occurring in a industrial water system, especially in an industrial cooling water system or a paper, pulp production water system, and capable of maintaining the pasteurization effect for a long period. SOLUTION: This method for pasteurizing microorganisms in water is provided by using (A) a compound generating available chlorine and/or available bromine in water and (B) a hydantoin compound, and maintaining 50-100 mg/L calcium concentration in the treated water system.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a general industrial water system,
In particular, the present invention relates to a microbicidal method for the purpose of suppressing slime damage that occurs in industrial cooling water systems and water systems for paper pulp manufacturing processes.

[0002]

2. Description of the Related Art In an industrial cooling water system, viscous substances secreted by microorganisms are mixed with earth and sand in the water, iron rust, other organic substances, etc. Also, it may adhere to the product and cause an obstacle such as an operation obstacle or a deterioration of the product quality.

In recent years, in the cooling water system, the circulation and reuse of water has become popular in order to reduce the amount of water used. Above all, in the open-circulation cooling water system, since the water is cooled by partially vaporizing it in the cold water tower, the dissolved components in water are concentrated and the pollutants in water increase. As a result, it becomes a favorable situation for the activity of aquatic microorganisms, and the slime formation is increased. If the slime adheres, the strainer in the water system may have poor water flow, the heat conduction of the heat exchanger may be reduced, the flow rate of the pipe may be reduced, the pipe may be blocked, and the metal may be corroded.

In the paper and pulp manufacturing industry, a large amount of water has been conventionally used for drainage. However, due to measures to increase wastewater treatment costs and increased awareness of the surrounding environment, reuse of water from the pulp and paper manufacturing process Is being promoted. Furthermore, in the paper manufacturing process,
Circulating reuse of water in order to use a wide variety of chemicals such as starch, sizing agents, retention aids, paper strength agents, latex resin, etc. leads to concentration of chemicals used in process water and is preferable for microbial growth. It is an environment. For example, slime formed by microorganisms adheres to the wall surface in the papermaking process, grows to some extent, is peeled off from the wall surface, is mixed in the pulp slurry and is made into papermaking, and the paper strength decreases and presses. In the process and the drying process, paper breakage may occur, coloring of the papermaking, spots, and eyeballs may occur, resulting in a significant decrease in product value.

In order to suppress such microbial damage,
Various types of microbicides have been proposed and used. However, in recent years, the use of conventional organic halogen-based fungicides has come to be reconsidered in consideration of the working environment and the surrounding environment, and in addition to the conventional acidic paper making, neutral paper making, and weak alkaline paper making. With the progress of migration, the growth conditions for microorganisms have improved, and it has become difficult to expect satisfactory effects with conventional microbicides.

Therefore, it has been proposed to use a halogenated hydantoin compound having a high bactericidal effect, high biodegradability and low toxicity of the decomposition product. For example, a method for preventing slime disorders using a halogenated hydantoin compound (JP-A-8-176996), a germicidal detergent composition using a combination of a halogenated hydantoin compound and chlorinated isocyanuric acid (JP-A-8-26917). Etc. are disclosed and proposed.

However, when the amount of organic components in water increases, the microbicidal effect of the hypohalous acid type bactericide decreases,
A method has been proposed in which it is used in combination with an organic halogen-based bactericide and the bactericidal power is increased by its synergistic effect. For example, a slime control method using a halogenated hydantoin compound and an isothiazolone compound in combination (JP-A-11-477).
55), a method of obtaining a synergistic effect by the combined use of 2-bromo-2-nitro-1,3-propanediol and a chlorine agent (US Pat. No. 4,966,775), 2-bromo-.
There is a method of increasing the bactericidal effect by using a bactericidal agent prepared by preliminarily formulating 2-nitro-1,3-propanediol and chlorine dioxide (Japanese Patent Publication No. 63-62486). Furthermore, a method of imparting osmotic force to enhance the bactericidal effect by acting on an aqueous system at the same time as an organic bromine compound and a chlorine agent (JP-A-7-171575), synergistically using an ammonium salt and hypohalous acid at the same time. A method of increasing the bactericidal power by the effect (Japanese Patent Laid-Open No. 5-146785), and a method of maintaining effective chlorine concentration in water by mixing hydantoin or a derivative thereof and a chlorine agent such as sodium hypochlorite (SHO 55-18259). Japanese Patent Publication No. 56-50638).
In this case, the hypohalous acid is a substance that generates hypochlorous acid or hypobromite in water, and corresponds to, for example, sodium hypochlorite.

Hypohalous acid has a high microbiocidal effect, but the effect does not last for a long time, and when the effective halogen and the hydantoin compound are combined, the bond between the hydantoin compound and the halogen is too strong, and the effect is added to the water system. However, it also has a drawback that the amount of free halogen is small and the microbicidal effect is not sufficiently exerted.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides effective chlorine and / or effective bromine in water for the purpose of suppressing slime damage occurring in general industrial water systems, especially industrial cooling water systems and paper pulp manufacturing process water systems. It is an object of the present invention to provide a water-based microbiocidal method capable of maintaining the microbiocidal effect for a long time while maintaining the microbiocidal effect.

[0010]

Means for Solving the Problems As a result of intensive studies on the sterilization method in an industrial water system, the present inventors have found that when a compound that produces an effective halogen in water is mixed with a hydantoin compound to sterilize the water system. The inventors have found that the bactericidal activity can be adjusted when a compound that produces an effective halogen in water and a hydantoin compound are mixed and applied, and the present invention has been completed.

That is, the invention according to claim 1 is a water-based microbicidal method, which comprises a compound which produces effective chlorine and / or effective bromine in water (hereinafter referred to as "(A) compound") and a general formula ( 1) [In the formula, R ¹ and R ² may be the same or different and each represents a hydrogen atom, an alkali metal atom or a hydroxylalkyl group having 1 to 4 carbon atoms, and R ³ and R ⁴ are May be the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms] and mix each solution of a hydantoin compound [hereinafter referred to as "(B) compound"] In the aqueous microbicidal method to be added later, the calcium ion concentration of the aqueous system is maintained at 50 to 1,000 mg / L.

[0012]

[Chemical 2]

The invention according to claim 2 is the aqueous microbiocidal method according to claim 1, characterized in that the calcium ion concentration in the aqueous system is maintained at 100 to 800 mg / L.

The invention according to claim 3 is the aqueous microbiocidal method according to claim 1, wherein the compound (A) and the compound (B) are the total number of moles of available chlorine and available bromine derived from the compound (A). And the number of moles of the compound (B) is 1: 0.3 to 1: 1.
It is characterized in that they are mixed so as to be 5.

The invention according to claim 4 is the aqueous microbiocidal method according to claim 1, wherein the compound (A) is chlorine, bromine,
Chlorine dioxide, sodium hypochlorite, calcium hypochlorite, sodium hypobromite, bromchlor-5,5-
One or more selected from dimethylhydantoin, dibromo-5,5-dimethylhydantoin, dichloro-5,5-dimethylhydantoin, sodium chloroisocyanurate, and potassium chloroisocyanurate.

The invention according to claim 5 is the aqueous microbiocidal method according to claim 1, wherein the compound (B) is 5,5-dimethylhydantoin, monomethylol-5,5-dimethylhydantoin, dimethylol-5, It is characterized by being one or more selected from 5-dimethylhydantoin.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

The compound (A) is a compound that produces effective chlorine and / or effective bromine such as hypochlorous acid and hypobromite in water.

Here, available chlorine means free chlorine (HOC).
1, OCl ⁻ ), bound chlorine, and effective bromine is free bromine (HOBr, OBr ⁻ ), bound bromine, and the definition and measurement method are in accordance with “JIS KI0101”.

Specific examples include chlorine, bromine, chlorine dioxide, hypochlorites, hypobromides, halogenated hydantoins represented by the general formula (2), halogenated isocyanuric acid and salts thereof. And one or more of these.

[0021]

[Chemical 3]

As the hypochlorites, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite,
Examples include magnesium hypochlorite and the like.

As the hypobromite salts, sodium hypobromite, potassium hypobromite, calcium hypobromite,
Examples include magnesium hypobromite and the like.

Halogenated hydan represented by the general formula (2)
Toins are R⁵And R⁶Are the same but different
Yes, hydrogen atom, alkali metal atom, salt
Elemental atom, bromine atom, hydroxylal having 1 to 4 carbon atoms
Represents a kill group, R⁷And R ⁸Are the same but different
May be present, respectively, a hydrogen atom or a carbon number of 1 to 4
Is a hydantoin compound represented by
Bromchloro-5,5-dimethylhydantoin,
Romchloro-5,5-diethylhydantoin, bromuk
Lolo-5-ethyl-5-methylhydantoin, dibromo
-5,5-Dimethylhydantoin, dibromo-5,5-
Diethylmethylhydantoin, dibromo-5-ethyl-
5-methylhydantoin, dichloro-5,5-dimethyl
Hydantoin, dichloro-5,5-diethylhydantoy
Dichloro-5-ethyl-5-methylhydantoin,
Halogenated isocyanuric acid and its salts include:
Loloisocyanuric acid, chloroisocyanuric acid Natri
Um, disodium chloroisocyanurate, chloroi
Potassium cyanate, Dica chloroisocyanurate
Lium, dichloroisocyanuric acid, dichloroisocyanate
Sodium nourate, potassium dichloroisocyanurate
, Trichloroisocyanuric acid, bromine isocyanurate
Acid, sodium bromiso cyanurate, bromiso
Cyanuric acid disodium salt, bromisocyanuric acid salt
Lithium, bromine dipotassium isocyanurate, dibrom
Isocyanuric acid, dibrom isocyanuric acid sodium
, Dibrom potassium isocyanurate, tribromui
There is socyanuric acid.

Of these, chlorine, bromine, chlorine dioxide, sodium hypochlorite, calcium hypochlorite, sodium hypobromite, bromochloro-5,5-dimethylhydantoin, dibromo-5,5- are preferred. Dimethylhydantoin, dichloro-5,5-dimethylhydantoin,
Sodium chloroisocyanurate and potassium chloroisocyanurate, more preferably sodium hypochlorite, sodium hypobromite, bromochloro-5,5-dimethylhydantoin, sodium chloroisocyanurate, and a mixture of two or more thereof. You may use it.

The compound (B) is a hydantoin compound represented by the general formula (1), and R ¹ and R ² may be the same or different and each is a hydrogen atom, an alkali metal atom or a carbon number. Represents a hydroxylalkyl group having 1 to 4 and R ³ and R ⁴ may be the same or different and each is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0027]

[Chemical 4]

Specifically, hydantoin, 5,5-dimethylhydantoin, 5-ethyl-5-methylhydantoin, 5-methyl-5-butylhydantoin, 5-butyl-5-ethylhydantoin and alkali metal salts thereof, There are mono-methylol-5,5-dimethylhydantoin, dimethylol-5,5-dimethylhydantoin, etc., preferably 5,5-dimethylhydantoin, monomethylol-5,5-dimethylhydantoin, dimethylol-5,5-dimethylhydantoin. Therefore, two or more of these may be mixed and used.

For the compound (A) and the compound (B), both compounds are dissolved in water and / or an organic solvent in advance,
This solution is mixed at a predetermined ratio, kept for a predetermined time, and then poured into a target water system. The concentration of both solutions at this time may be any concentration as long as the respective compounds are stably dissolved, and diluting more than necessary not only makes it difficult to handle, but also has the microbiocidal effect of the present invention. The contribution to the increase may be less.

The mixing ratio of the compound (A) and the compound (B) is 1: 0.3 to the compound (B) based on the total number of moles of available chlorine and available bromine in the compound (A).
1: 1.5 (molar ratio), preferably 1: 0.5 to 1:
Set it to 1.0.

The microbicidal agent of the present invention can generally be used immediately by mixing a solution of both compounds at room temperature, and the holding time after mixing and preparation is usually 90 minutes or less, preferably 60 minutes or less. , And more preferably within 30 minutes. If the holding time is longer than 90 minutes, it does not increase the microbicidal action, but rather, the longer the holding time is, the more effective chlorine and available bromine may be decomposed. While the mixture is held, it may be allowed to stand, but it is preferable to stir it gently.

The amount added to the water system varies depending on the water quality of the target water system, temperature, other operating conditions, the number of microorganisms in the water, the type of microbial bacteria in the water and the number of surviving the microorganisms.
Generally, the compound A is added in an amount of 0.01 to 10 mg / L, preferably 0.1 to 5 in total concentration of available chlorine and available bromine in water.
mg / L, more preferably 0.2 to 2 mg / L, and the compound B is added so as to make the ratio of the total moles of available chlorine and available bromine suitable. This concentration range was obtained from a microbicidal and economic standpoint, but the total concentration of available chlorine and available bromine was 10.0 mg.
If it exceeds / L, the corrosion of the metal in the water system may become a problem, so care must be taken. The addition to the water system may be continuous addition or intermittent addition, but it is preferable to appropriately adjust it depending on the total concentration of effective chlorine and effective bromine in the water system. In practice,
It is preferable to observe the number of microorganisms in water and the state of slime generation, and determine the amount and frequency of addition commensurate with them.

In the present invention, when the compound (A) and the compound (B) are mixed and added, the calcium ion concentration in the water of the target water system is 50 to 1,000 mg / L, preferably 100 to 800 mg / L. L, more preferably 100
It is characterized in that the bactericidal effect is maintained for a long period of time by maintaining it at ˜500 mg / L. If the calcium ion concentration in the water is less than 50 mg / L, the microbiocidal effect aimed at by the present invention is insufficient for a long time, and if the calcium ion concentration exceeds 1,000 mg / L,
It may be accompanied by reduced bactericidal activity and the development of calcium scale.

The calcium ion concentration in water is adjusted by appropriately adding a calcium compound that releases calcium ions in water, specifically calcium hydroxide, calcium carbonate, calcium oxalate, calcium chloride and the like. When the water system evaporates a part of the water like the circulating cooling water system, the calcium ion concentration in the water will be concentrated, so while checking the calcium ion concentration in the water, the calcium compound can be continuously or intermittently supplied. Adjust while adding. If the calcium ion concentration in the water is within the appropriate range,
It is not necessary to intentionally add calcium ions.

The pH of the aqueous system for carrying out the present invention is 4-1.
1, preferably 6-9. This pH range is a practical aqueous pH range and is selected from the viewpoint of microbiocidal effect.

In carrying out the present invention, a scale inhibitor, a corrosion inhibitor, a microbicide other than the present invention and the like, which are generally used in water treatment, may be added, but the effect of the present invention is not impaired. It does not prevent the use of these additives. In particular, since the present invention maintains a high calcium concentration in water, it is often practically necessary to use a scale inhibitor in combination to suppress the generation of calcium scale.

[0037]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these examples. [A compound] A-1: sodium hypochlorite (12% aqueous solution) [reagent, manufactured by Kanto Chemical Co., Inc.] A-2: bromochloro-5,5-dimethylhydantoin "Bromide" (trade name) [Great Lakes Chemicals Co., Ltd.] [B compound] B-1: 5,5-dimethylhydantoin [Mitsui Chemicals, Inc.] B-2: Monomethylol-5,5-dimethylhydantoin [Wako Pure Chemical Industries, Ltd., reagent ] [Strain] Pseudomona
aeruginosa (IFO-12689)) [Medium] 1.0 g of glucose, 5.0 g of heptone, 2.5 g of yeast extract, and 18 g of agar were dissolved in 950 ml of distilled water, and the pH was adjusted to 6.8. Distilled water was added to bring the total volume to 1,000 ml to prepare a plate medium for general bacteria. [Method for measuring the number of bacteria] 0.1 mL of sample water was dropped on a plate medium, and the whole surface of the medium was expanded using a sterilized conradi rod to culture, and the number of generated colonies was multiplied by 10 to count the number of bacteria (cells / mL). And

[0038]

Example 1 A microbe-killing effect was evaluated by adding a culture solution cultivated in a medium for general bacteria to water to prepare sample water. Evaluation,
The respective solutions of the compound (A) and the compound (B) were mixed in a predetermined ratio, lightly stirred at room temperature for 3 minutes, and then available chlorine was added to the sample water so as to be 17 mmol / L. Then, a predetermined concentration of calcium ion was added, and the number of bacteria after a predetermined time elapsed was measured. The results are shown in Tables 1 and 2.

[0039]

[Table 1]

[0040]

[Table 2]

When the contact time was 30 minutes, the microbicidal effect was recognized in both cases where the compound (A) alone or the compound (A) and the compound (B) were mixed and the amount of calcium ion added was changed. There was no substantial difference in the conditions. However, after 240 minutes, the (A) compound and the (B) compound of the present invention were mixed with 1: 0.3 to 1: 1.5.
When mixed in a (molar ratio) ratio and the calcium ion concentration is in a specific range (50 to 1000 mg / L), there is a microbicidal effect, but outside this condition, the microbicidal effect is substantially lost and microbiocidal. It was confirmed that the effect could not be maintained for a long time.

From this, it was confirmed that the sterilizing effect of the present invention was used, and the sterilizing effect excellent in durability was confirmed.

[0043]

According to the present invention, the microbicidal action in the cooling water system of various industries, the process water system such as the paper industry can be stably maintained for a long period of time, and the slime problem occurring in these water systems can be solved. This can contribute to the stabilization of the process and the stability of the quality of the product manufactured from each process.

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Claims (5)

[Claims] 1. A compound (A) which produces effective chlorine and / or effective bromine in water, and (B) a general formula (1) [in the formula, R ¹ and R ² may be the same or different. Well, each has a hydrogen atom, an alkali metal atom, and a carbon number of 1.
Represents a hydroxylalkyl group of ~ 4, R ³ and R ⁴
Which may be the same or different and each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms] and the calcium ion concentration of the water to be treated is 50 to 1000 mg / L. A water-based microbiocidal method characterized in that [Chemical 1] 2. The calcium ion concentration of the water to be treated is 1
The water-based microbicidal method according to claim 1, wherein the amount is from 00 to 800 mg / L. 3. The compound (A) which produces effective chlorine and / or effective bromine in water and (B) the hydantoin compound represented by the general formula (1) are the total number of moles of effective chlorine and effective bromine and the hydantoin compound. Has a molar number of 1: 0.3 to 1:
The water-based microbicidal method according to claim 1, which is 1.5. 4. A compound which produces effective chlorine and / or effective bromine in water is chlorine, bromine, chlorine dioxide, sodium hypochlorite, calcium hypochlorite, sodium hypobromite, bromochloro-5,5. -The water-based microbiocidal method according to claim 1, which is one or more selected from dimethylhydantoin, dibromo-5,5-dimethylhydantoin, dichloro-5,5-dimethylhydantoin, sodium chloroisocyanurate, and potassium chloroisocyanurate. 5. The water-based microbicide according to claim 1, wherein the hydantoin compound is one or more selected from 5,5-dimethylhydantoin, monomethylol-5,5-dimethylhydantoin, and dimethylol-5,5-dimethylhydantoin. Method.