JP2009084163A - Bactericidal/algicidal method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bactericidal/algicidal method comprising the addition of an oxidant-based bactericidal/algicidal agent and its stabilizer to a target water system to carry out a bactericidal/algicidal treatment and reducing the nitrogen content and COD level derived from the stabilizer by effectively utilizing the stabilizer and reducing the amount of the stabilizer. <P>SOLUTION: The bactericidal/algicidal method comprises the addition of an oxidant-based bactericidal/algicidal agent and its stabilizer to a target water system, while controlling the addition amount of the oxidant-based bactericidal/algicidal agent in a manner to fall the total residual chlorine concentration of the water system within a prescribed range and controlling the addition amount of the stabilizer in a manner to fall the free residual chlorine concentration within a prescribed range. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is applicable to various water systems such as a cooling water system, a paper pulp process water system, a dust collection water system, a scrubber water system, and a fountain system, and an oxidizer-based sterilizing agent (meaning sterilization and / or algae) and its stabilization. In the sterilization and algae treatment by adding an agent, the above-mentioned stabilizer is effectively used, and the amount of nitrogen and COD derived from the stabilizer can be reduced by reducing the amount of the stabilizer used. It relates to an algaecidal method.

  In various water systems, various obstacles have occurred due to fungi and algae. For example, in an open circulation cooling water system, bacteria such as zoom glial bacteria, filamentous bacteria, iron bacteria, sulfur bacteria, nitrifying bacteria, sulfate-reducing bacteria, fungi such as water mold and blue mold, cyanobacteria, green algae, diatoms, etc. Algae grow, and slime and sludge are generated by adhesion and accumulation of soft mud-like contaminants formed by mixing these inorganic substances such as earth and sand and dust, etc., mainly with these microorganisms. Slime and sludge not only cause a decrease in thermal efficiency and water flow, but also cause local corrosion of equipment and piping. In addition, there are cases where fungi grown in the water system directly cause damage to the human body, such as a local illness caused by Legionella bacteria scattered from the cooling tower. Even in the papermaking process water system, various bacteria, fungi, yeast, etc. grow to form slime, causing defects such as holes, spots, eyeballs, etc. in the product, not only reducing product quality, but also causing paper breakage. And productivity is reduced.

Conventionally, a chlorine-based oxidizing agent such as hypochlorite has been added to an aqueous system in order to prevent such damage caused by fungi and algae. In general, it is said that the growth of fungi and algae can be suppressed when the residual chlorine concentration in water is 5 mgCl ₂ / L or more. However, chlorine-based oxidizers such as hypochlorite are easily decomposed by ultraviolet rays, and if they are stored and left outdoors, such as in a plastic container filled with a bactericidal algicide, chlorine is an active ingredient due to ultraviolet rays. System oxidizer decomposes. Further, even after the bactericidal algicide is added to the aqueous system, it is difficult to completely block the cooling water from light in an open circulation cooling water system or the like. Furthermore, when copper or a copper alloy is used as a material for water-based pipes or heat exchangers and the copper ions are eluted, the decomposition of a chlorine-based oxidant such as hypochlorite is further promoted.

In order to suppress decomposition of such chlorine-based oxidants such as hypochlorite, it contains hypochlorite, benzotriazole, tolyltriazole and sulfamate, and the pH is adjusted to 13 or more. In addition, a technique for adding a stabilized effective chlorine component to an aqueous system is disclosed (for example, see Patent Document 1).
When sulfamate is added to hypochlorite, N-monochlororosulfamate or N, N-dichlorosulfamate is formed, and the effective chlorine component is stabilized.
However, when there is a lot of slime in the target water system, or when UV irradiation is strong, or under high temperature conditions, the decomposition of stabilized hypochlorite is severe, and it is necessary to increase the amount of stabilizer sulfamate used. . When the stabilized hypochlorite decomposes, the hypochlorite is consumed, but the sulfamate remains in the aqueous system. As a result, when the remaining sulfamate is blown out of the system, it affects the regulation of nitrogen and COD.
In addition, when preparing a stabilized hypochlorite solution and adding it to an aqueous system, a hypochlorite solution and a sulfamate solution are mixed in an equimolar ratio of hypochlorite and sulfamate. It is often performed to prepare a stabilized hypochlorite solution by mixing in a line. In this case, a special control device capable of line-mixing both components at an equimolar ratio is required.

Japanese Patent No. 3832399

  The present invention has been made under such circumstances. When the sterilizing algaecide and its stabilizer are added to the target water system and the sterilizing treatment is performed, the above stabilizer is effective. By utilizing and reducing the amount used, it is possible to reduce the nitrogen content and COD content derived from the stabilizer, and to eliminate the need for a special line mixing controller as described above, It is intended to provide.

As a result of intensive studies to achieve the above object, the inventors of the present invention have controlled the addition amount of the oxidizer-based bactericidal algicide so that the total residual chlorine concentration in the aqueous system is within a predetermined range. The inventors have found that the purpose can be achieved by controlling the amount of the stabilizer added so that the free residual chlorine concentration is within a predetermined range. The present invention has been completed based on such findings.
That is, the present invention
(1) A method for sterilizing and killing an oxidizer-based bactericidal algicide and its stabilizer to a target water system, wherein the total residual chlorine concentration in the water system is within a predetermined range, A bactericidal algaecidal method characterized by controlling the addition amount of the oxidizer-based bactericidal algicide and controlling the addition amount of the stabilizer so that the free residual chlorine concentration is within a predetermined range;
(2) The sterilizing algaecidal method according to the above (1), wherein the oxidizer-based bactericidal algicidal agent is hypochlorite and / or hypobromite,
(3) Using a chlorine concentration measuring device, the oxidizer system so that the total residual chlorine concentration in terms of chlorine of hypochlorite and / or hypobromite is in the range of 0.1 to 100 mg / L. The amount of stabilizer added is controlled so that the amount of free residual chlorine in the chlorine conversion of hypochlorite and / or hypobromite is 1 mg / L or less while controlling the amount of fungicidal algicide. The bactericidal and algicidal method according to (1) or (2) to be controlled, and (4) the stabilizer is sulfamic acid and / or a salt thereof according to any one of (1) to (3) above Bactericidal algae method,
Is to provide.

  According to the sterilizing algaecide method of the present invention, an oxidizer-based sterilizing algaecide and its stabilizer are added to various water systems such as a cooling water system, a paper pulp process water system, a dust collection water system, a scrubber water system, and a fountain system. In the sterilization and sterilization treatment, the stabilizer can be effectively used, and the amount of the stabilizer can be reduced to reduce the nitrogen and COD content derived from the stabilizer. No special control device is used.

The bactericidal algae method of the present invention is a method for adding a oxidizer-based bactericidal algicide and its stabilizer to a target water system for bactericidal algae, wherein the total residual chlorine concentration in the water system is within a predetermined range. The amount of the oxidizing agent-based disinfectant algaecide is controlled so as to be within the range, and the amount of the stabilizer added is controlled so that the free residual chlorine concentration is within a predetermined range. .
In addition, as a measuring method of the residual chlorine concentration of the bactericidal and algicidal method of the present invention, a DPD absorptiometric method, a DPD colorimetric method, an amperometric method, a polarographic method and the like can be employed.

[Oxidizer-based bactericidal algicide]
As the oxidant-based bactericidal algicide used in the method of the present invention, a compound conventionally known as an oxidant-based bactericidal algicide can be used. In the present invention, hypochlorite is particularly used. Is preferably used. Note that hypobromite alone or a combination of hypochlorite and hypobromite may be used instead of hypochlorite.
Examples of the salt form of hypochlorous acid or hypobromite include sodium salt, potassium salt, calcium salt, barium salt, etc., but from the viewpoint of water solubility and economy, sodium salt is preferable. It is.
In the present invention, these hypochlorite and hypobromite may be used singly or in combination of two or more.
These hypochlorite and hypobromite are easily decomposed by ultraviolet rays, and in order to stabilize the effective chlorine component by suppressing this decomposition, in the present invention, the oxidizer-based sterilization is performed. Along with the algicidal agent, the stabilizer is added to the target water system.

[Stabilizer]
In the method of the present invention, as the stabilizer for the above-mentioned oxidant-based bactericidal algicide, any one of known compounds conventionally known as stabilizers for oxidant-type bactericidal algicide can be used. It can be appropriately selected and used. More specific stabilizers include sulfamic acid and / or its salt, azole compound, urea, thiourea, creatinine, cyanuric acid, alkylhydantoin, mono- or diethanolamine, organic sulfonamide, burette, organic sulfamic acid and melamine Etc. Among these, it is preferable to use sulfamic acid and / or a salt thereof effective as a stabilizer for hypochlorite or hypobromite. The sulfamate is not particularly limited, and examples thereof include sodium sulfamate, potassium sulfamate, calcium sulfamate, strontium sulfamate, barium sulfamate, iron sulfamate, and zinc sulfamate. From the viewpoint of water solubility and economy, sodium sulfamate is preferred.
In the present invention, these sulfamic acids and salts thereof may be used alone or in combination of two or more.

Hypochlorite ion and sulfamic acid react as shown in the following formula to form N-monochlorosulfamate ion or N, N-dichlorosulfamate ion to stabilize the active ingredient of the chlorinated oxidant.
HClO + H ₂ NSO ₃ ⁻ → HClNSO ₃ ⁻ + H ₂ O
2HClO + H ₂ NSO ₃ ⁻ → Cl ₂ NSO ₃ ⁻ + 2H ₂ O
Mono- or dichlorosulfamic acid ions have a weaker bactericidal effect than free chlorine ions.

On the other hand, hypobromite ion and stabilizer sulfamic acid react as shown in the following formula to form N-monobromosulfamic acid ion or N, N-dibromosulfamic acid ion to form brominated oxidant. Stabilize active ingredients.
HBrO + H ₂ NSO ₃ ⁻ → HBrNSO ₃ ⁻ + H ₂ O
2HBrO ⁻ + H ₂ NSO ₃ ⁻ → Br ₂ NSO ₃ ⁻ + 2H ₂ O
Mono- or dibromosulfamate ions have a bactericidal effect almost similar to free bromine ions.

[Control of addition amount of oxidizer-based bactericidal algicide and stabilizer]
In the present invention, the amount of the aforementioned oxidizer-based bactericidal and algicidal agent is controlled so that the total residual chlorine concentration in the target water system is within a predetermined range, and the free residual chlorine concentration is within the predetermined range. In addition, the amount of the stabilizer mentioned above is controlled. Even when hypobromite is used instead of or in addition to hypochlorite, the concentration of hypobromite is expressed as a chlorine equivalent.
Incidentally, it converts as hypochlorous acid (52.5 g / L) = hypochlorous acid (97.5 g / L) = chlorine (71 g / L).
Specifically, using a chlorine concentration measuring device, the total residual chlorine concentration in the target water system is preferably in the range of 0.1 to 100 mg / L, more preferably 1 to 100 mg / L. While controlling the addition amount of the bactericidal algicide, the addition amount of the stabilizer is usually within the range of 0.5 to 2.0 times the molar amount with respect to the addition amount of the oxidizing bactericidal algicide. And by controlling the free residual chlorine concentration to be preferably 1 mg / L or less, more preferably 0.5 mg / L or less, and even more preferably 0.3 mg / L or less. I do.
Such a bactericidal and algicidal treatment is advantageously performed while controlling the pH of the aqueous system to be in the range of 3.0 to 10.0, preferably in the range of 6.0 to 9.0.
The method for measuring the total residual chlorine concentration and the free residual chlorine concentration will be described in detail later.
In order to strengthen the bactericidal and algicidal power, it is better to increase the total residual chlorine concentration. However, if the free residual chlorine concentration increases at this time, the stabilizer is insufficient. By increasing the agent concentration, the free residual chlorine concentration is reduced. Such control may be performed automatically or manually.
In addition, the addition amount of the oxidizing agent bactericidal algicide may be controlled by an online total residual chlorine concentration analyzer, and the addition amount of the stabilizer may be controlled by an online free residual chlorine concentration analyzer.

[Target water system]
There is no restriction | limiting in particular in the water system to which the sterilization algicide method of this invention is applied, For example, a cooling water system, a paper pulp process water system, a dust collection water system, a scrubber water system, a fountain system etc. can be mentioned.
By applying the sterilizing and algae killing method of the present invention to these water systems, high residuals can be obtained even in environments where sunlight is irradiated, or in water systems where copper or copper alloy materials are used in piping, heat exchangers, etc. The chlorine concentration is maintained, and effective sterilization and algae treatment of the target water system is possible, and the stabilizer is effectively utilized. By reducing the amount of the stabilizer used, the nitrogen content and COD derived from the stabilizer are reduced. Minutes can be reduced.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
The free residual chlorine concentration and the total residual chlorine concentration were measured according to the methods shown below.
(1) Free residual chlorine concentration (a) Preparation of DPD reagent DPD (N, N-diethyl-p-phenylenediamine) comprising a mixture of 1.0 g of N, N-diethyl-phenylenediamine sulfate and 24 g of anhydrous sodium sulfate Make reagents.
(B) Preparation of phosphate buffer solution (pH = 6.5) 35.4 mL of 0.2 mol / L sodium hydroxide solution was added to 100 mL of 0.2 mol / L potassium dihydrogen phosphate, and trans-1,2 was added thereto. -Dissolve 0.13 g of cyclohexanediaminetetraacetic acid-hydrate to prepare a phosphate buffer (pH = 6.5).
(C) Measurement of Free Residual Chlorine Concentration: Take 2.5 mL of phosphate buffer solution in 50 mL of a stoppered container, add 0.5 g of PDP reagent, add test water to make the total volume 50 mL, and mix. Next, an appropriate amount of the mixed solution is taken in an absorption cell, the absorbance at a wavelength of about 510 to 555 nm is measured using a photoelectric spectrophotometer, and the free residual chlorine concentration is obtained from a calibration curve prepared in advance.
(2) Total residual chlorine concentration To 50 mL of the mixed solution obtained in (1) and (c) above, about 0.5 g of potassium iodide was added and dissolved, and after standing for about 3 minutes, the above (1) (c) and Similarly, the absorbance in the vicinity of a wavelength of 510 to 555 nm is measured using a photoelectric spectrophotometer, and the total residual chlorine concentration is obtained from a calibration curve prepared in advance.

Example 1
Stabilized simulated cooling water for hypochlorite (M alkalinity 250 mg / L, calcium hardness 250 mg / L, magnesium hardness 125 mg / L) 1 L at 30 ° C., sodium hypochlorite 0.014 mmol / L (Total residual chlorine concentration 1 mg / L) was added. To this, sodium sulfamate was added in a molar equivalent of 1, 2, 5 times the active ingredient of sodium hypochlorite.
As a result, it was confirmed that the free residual chlorine concentration can be stabilized at a low level after about 24 hours by reacting the active ingredient of hypochlorite with an equimolar amount or more of sulfamate.
The results are shown in Table 1 and shown in FIG. In the tables and figures, T-Cl ₂ : total residual chlorine concentration, F-Cl ₂ : free residual chlorine concentration, NT: stabilized hypochlorite concentration ([T-Cl ₂ ]-[F-Cl ₂ ]). The same applies below

Example 2
Regeneration method of stabilized hypochlorite consumed by soil components Simulated cooling water (M alkalinity 250 mg / L, calcium hardness 250 mg / L, magnesium hardness 125 mg / L) 1 L, hypochlorous acid at 30 ° C. 0.0705 mmol / L of sodium (effective chlorine concentration 5 mg / L) and 0.3525 mmol / L of sodium sulfamate (5-fold molar equivalent with respect to effective chlorine concentration) were added. To this, a soil component collected from the actual cooling water system was added, and the turbidity was adjusted to 100. The effective chlorine component was consumed by the soil component. The total residual chlorine concentration, which was initially 5 mg / L, decreased to 1.5 mg / L after about 3 days. At that time, as a result of adding 5 mg / L of sodium hypochlorite as an active ingredient, the total residual chlorine concentration increased to 6.5 mg / L. Little free residual chlorine concentration was detected. That is, the stabilized hypochlorite could be regenerated. Thereafter, the effective chlorine component was consumed again by the soil component, and the total residual chlorine concentration tended to decrease.
The results are shown in FIG.
The effective chlorine component (hypochlorite) is consumed by the soil component, but the sulfamate remains in the system. If hypochlorite is added in this state, it reacts with the sulfamate remaining in the system, and stabilized hypochlorite is produced again.
In the real system, it can be managed by the following method. When the active ingredient concentration (total residual chlorine concentration) of the stabilized hypochlorite has decreased, a predetermined active ingredient concentration (total residual chlorine concentration) is maintained by adding hypochlorite. Free hypochlorite concentration is detected when hypochlorite is added in excess to the sulfamate. At that time, by adding sulfamate, the concentration of free residual chlorine can be reduced, and the stabilized hypochlorite can be regenerated.

Example 3
Reactivity simulated cooling water of sulfamate and hypochlorite (M alkalinity 250 mg / L, calcium hardness 250 mg / L, magnesium hardness 125 mg / L) 1 L at 30 ° C. with sodium hypochlorite 0 0.084 mmol / L (total residual chlorine concentration 6 mg / L) was added. To this, sodium sulfamate was added in an amount of 0.83, 1.7, 4.2 times the molar equivalent of the active ingredient of sodium hypochlorite, and T-Cl ₂ and F-Cl ₂ over time were added. I examined the changes. The results are shown in Table 2 and shown in FIG.
As a result, it is possible to generate stabilized chlorine after 22 hours and to reduce the free residual chlorine concentration to a low level by reacting sulfamate with an equimolar amount or more with respect to the active ingredient of hypochlorite. Was confirmed. Further, it can be seen from the comparison between Table 1 and Table 2 that the rate of formation of stabilized chlorine can be increased by increasing the total residual chlorine concentration from 1 mg / L to 6 mg / L.

Comparative Example 1
In Example 4 of JP-A-2006-206608 “Bactericidal Algicidal Composition”, 8.2 g of water, 19.3 g of 45 wt% aqueous sodium hydroxide, 12.0 g of sulfamic acid, 12 wt% hypochlorous acid One stabilized hypochlorous acid blended with 60.0 g sodium and 0.5 g benzotriazole is mentioned.
As in Example 2, when this agent is applied to an aqueous system with a high soil load, the active hypochlorite concentration (total residual chlorine concentration) of the stabilized hypochlorite is consumed. In order to maintain the active ingredient concentration, it is necessary to increase the additive concentration of the drug. In that case, sulfamic acid, COD derived from benzotriazole, and nitrogen content in the drug are added to the aqueous system, leading to an environmental burden.

  The bactericidal and algicidal method of the present invention comprises stabilizing hypochlorite and / or hypochlorite by reacting hypochlorite and / or hypobromite and sulfamate efficiently without excess or deficiency. This is a technology capable of producing bromate, and can reduce COD and nitrogen load derived from sulfamic acid and benzotriazole, which are problems of the prior art.

3 is a graph showing the relationship between residual chlorine concentration and time in Example 1. 6 is a graph showing the relationship between residual chlorine concentration and time in Example 2. 6 is a graph showing a relationship between residual chlorine concentration and time in Example 3.

Claims (4)

  An oxidizer-based bactericidal algicide and its stabilizer are added to a target water system for bactericidal algae, wherein the oxidizer is such that the total residual chlorine concentration in the water system is within a predetermined range. A sterilizing algaecidal method characterized by controlling the addition amount of the system sterilizing algicide and controlling the addition amount of the stabilizer so that the free residual chlorine concentration is within a predetermined range.   The sterilizing algaecide method according to claim 1, wherein the oxidizer-based sterilizing algaecide is hypochlorite and / or hypobromite.   Using a chlorine concentration measuring device, the oxidizer-based sterilizing alga so that the total residual chlorine concentration in terms of chlorine of hypochlorite and / or hypobromite is in the range of 0.1 to 100 mg / L The amount of stabilizer added is controlled, and the amount of stabilizer added is controlled so that the free residual chlorine concentration in terms of chlorine in hypochlorite and / or hypobromite is 1 mg / L or less. Item 3. The method for bactericidal algae killing according to item 1 or 2.   The sterilizing method according to any one of claims 1 to 3, wherein the stabilizer is sulfamic acid and / or a salt thereof.

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