JP5665524B2 - Water treatment method for suppressing microbial damage in water - Google Patents

Description

  In the present invention, the above-mentioned halogen stabilization is carried out by adding hypohalous acid and a halogen stabilizer 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 drainage system, and then sterilizing and killing them. Effective use of chemicals to obtain an excellent bactericidal and algicidal effect at the minimum required concentration of halogen stabilizers, and by reducing the amount used, the nitrogen content and COD content derived from the halogen stabilizers are reduced. However, the present invention relates to an aqueous treatment method capable of performing aqueous sterilization and algae.

  Patent Document 1 discloses a stabilized chlorine solution for sterilization obtained by reacting sulfamic acid and hypochlorite, and about 0.2 for sterilization in a cooling system such as an evaporative water cooling tower. A method of adding a solution containing free active chlorine at a concentration of 3 to 3 mg / L and sulfamic acid ions at a concentration of about 1 to 10 mg / L is disclosed.

  This concentration of stabilizing chlorine for sterilization is expressed as “bound chlorine concentration” obtained by subtracting free residual chlorine concentration from total residual chlorine concentration. Although it has strong bactericidal power and immediate effect, the active ingredient tends to disappear and corrosive free chlorine, and the bactericidal power is suppressed, but the sustainability of the active ingredient is improved compared to free chlorine, corrosion Attempts have been made to achieve high initial sterilizing power, sustained sterilizing power, and low corrosivity by combining low-bonding bonded chlorine utilizing the respective characteristics (see, for example, Patent Document 2).

  Furthermore, the combination will be described in detail. Although there is an immediate effect, free chlorine, which does not have a long-lasting effect, acts strongly on the surface of the object to be sterilized and sterilizes. In the case of dirt that has been formed and adhered, the surface of the layer is sterilized and biocidal, but the effect does not reach the lower part of the layer. However, for example, the most serious obstacle in the cooling water system is leakage due to metal surface corrosion, and the corrosion proceeds under the soil where the layered soil contacts the metal surface. Therefore, free chlorine can sterilize and kill bacteria and algae of single cells and small clumps, but it effectively kills and kills the center of large clumps formed by the bottom of layered soil and large algae. I can't expect to algae. On the other hand, combined chlorine has a higher persistence of active ingredients than free chlorine, so it retains sufficient bactericidal and algicidal effects even when the ingredients reach the bottom of the layered soil and the central part of the large mass. Therefore, even at sites where free chlorine cannot be expected to be effective, bound chlorine can exhibit a sufficient bactericidal and algicidal effect, and also has low corrosiveness to metals, so the metal surface below the layered soil The progress of corrosion can be effectively suppressed. Thus, by using a combination of free chlorine and bonded chlorine, it is possible to obtain an excellent bactericidal / algicidal effect with low corrosivity.

In Patent Document 2, a chlorine-based oxidizing agent and sulfamic acid or a salt thereof for giving a sufficient free chlorine concentration to the target water at an initial stage are individually added, and a free residual chlorine concentration and a total residual chlorine concentration are determined in advance. In the water state determination method characterized by determining whether or not the balance is in a range, the initial concentration of free residual chlorine is 2 (mg / L) or more, and the [free residual chlorine concentration in water] Water for determining whether the value of (mg / L) +0.1] × [total residual chlorine concentration (mg / L)] is within the range of 0.1 to 1.0 (mg / L) ² The state determination method is shown. In this determination method, it is necessary to frequently measure and determine the free residual chlorine concentration and the total residual chlorine concentration.

  Patent Document 3 discloses that the total residual chlorine concentration in terms of chlorine in hypochlorite and / or hypobromite is within a range of 0.1 to 100 mg / L using a chlorine concentration measuring device. Control the amount of hypohalous acid added and control the amount of sulfamic acid added so that the free residual chlorine concentration in terms of chlorine in hypochlorite and / or hypobromite is 1 mg / L or less. Disinfecting and algae killing methods are disclosed. Here, as a method for regenerating the stabilized hypochlorite consumed by the soil components, hypochlorite is newly added to the sulfamate remaining in the system without reacting with hypochlorite. Stabilized hypochlorite is generated by adding to the system, but even in this regeneration method, the concentration of free residual chlorine and total residual While measuring the chlorine concentration, hypochlorite should be added little by little to find the appropriate amount of hypochlorite.

  Patent Document 4 discloses a drug containing a stabilized hypohalite obtained by reacting a hypohalite and a sulfamate, and converting the oxidizing power of aqueous water into the total residual chlorine concentration. By maintaining in the range of 1 mg / L or more and 5 mg / L or less, the oxidizing power of the aqueous water converted to free residual chlorine concentration is maintained in the range of 0.01 mg / L or more and less than 0.1 mg / L. A slime suppression method in aqueous water is disclosed. However, for example, the quality and operating conditions of the circulating water in the circulating water system of the chilled water tower are very diverse, and it is known that the oxidizing power varies greatly depending on the pH. Is maintained in the range of 1 mg / L or more and 5 mg / L or less, the oxidizing power of the aqueous water converted to free residual chlorine concentration can be maintained in the range of 0.01 mg / L or more and less than 0.1 mg / L. I can not say.

  As described above, the conventional attempts to effectively suppress microbial damage by combining free chlorine and combined chlorine have problems such as requiring complicated analysis, or the desired effect cannot be obtained depending on the conditions of the target water system. is there. Further, in the above-described conventional technique for measuring both the total residual chlorine concentration and the free residual chlorine concentration, the specific treatment method when the measured value is out of the control range is not clear, and the sulfamic acid is added to the appropriate concentration. Therefore, it is often troublesome to maintain a sufficient amount of bactericidal and algicidal effects only by controlling the total residual chlorine and free residual chlorine.

  Further, although a nitrogen-containing compound such as sulfamic acid is used as a halogen stabilizer for generating bound chlorine in the system, it is not preferable that the nitrogen content and COD content of aqueous water increase due to the addition of the compound, There is a need for the minimum addition of the compound.

US Pat. No. 3,170,883 JP 2008-241296 A JP 2009-84163 A JP 2009-160505 A

  In the present invention, when adding a hypohalous acid generating compound and a halogen stabilizer to a water system to be treated to suppress various microbial disturbances, the concentration of the halogen stabilizer is kept constant and effectively used. With the minimum additive concentration of the halogen stabilizer, it has low corrosivity and excellent bactericidal and algicidal effects, and by reducing the amount used, the nitrogen content and COD content derived from the halogen stabilizer are reduced. It is an object of the present invention to provide an aqueous treatment method that can suppress various microbial damages by a simple and inexpensive method without requiring a complicated and expensive analysis device or control device.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have been able to prevent corrosion and scale such as organophosphate compounds, polymerized phosphate compounds, orthophosphoric acid and anionic polymer electrolytes capable of measuring concentrations. Therefore, by adding a halogen stabilizer at a constant ratio in proportion to the addition of the compound being added, the concentration of the halogen stabilizer in the treated water system is kept constant, while the redox potential in the treated water system is increased. By controlling the amount of hypohalous acid generating compound added so as to be within a predetermined range, it has been found that low corrosiveness and an excellent inhibitory effect against various microbial disorders can be obtained, and the present invention has been achieved. It is a thing.

  In the method of the present invention, by keeping the concentration of the halogen stabilizer in the treated water system constant, the bound halogen concentration in the treated water system can be kept constant, thereby promoting the adhesion microbial soil that promotes corrosion of the metal. In addition to suppressing metal corrosion by killing and peeling, sterilize fine bacteria and algae that can flow from outside the system and become components of attached dirt by combining free halogen.

  In addition, the oxidation-reduction potential in the water system to be treated indicates the sum of the oxidation power in the water system. When the oxidation-reduction potential falls below the appropriate range, the oxidation power decreases and the bactericidal power is insufficient, and the oxidation-reduction potential falls within the appropriate range. Since the oxidizing power increases and the metal corrosivity increases, the addition of a hypohalous acid-generating compound so that the redox potential is within an appropriate range while appropriately combining free halogen and bound halogen. By controlling the amount, both low corrosivity and excellent bactericidal and algicidal effects were achieved.

  The hypohalous acid generating compound used in the present invention is a compound that generates hypochlorous acid and / or hypobromite, and specifically corresponds to hypochlorite, hypobromite, and the like. For example, when the hypohalous acid generating compound is hypochlorite, the hypochlorite salt of the hypochlorite is maintained so that the oxidation-reduction potential is maintained within a certain range while keeping the concentration of the halogen stabilizer in the treated water system constant. It has been found that by controlling the amount added, the bound chlorine produced is kept constant, and the concentration of free chlorine is maintained at the concentration required for sterilization without depending on the operating conditions (particularly pH) of the system.

  Here, when the concentration of the system fluctuates, the conventional technique frequently measures the free residual chlorine concentration and the total residual chlorine concentration, and adds a halogen stabilizer so that the combined chlorine becomes the concentration before the fluctuation. The amount of hypochlorite is adjusted so that the amount of free residual chlorine before fluctuation is obtained. In this adjustment process, hypochlorite addition is likely to be insufficient or excessive, and sterilization power is insufficient or metal corrosion is promoted. On the other hand, in the present invention, the addition amount of the halogen stabilizer increases and decreases following the fluctuation of the system, and since its concentration is always kept constant, hypochlorous acid so as to match the redox potential before the fluctuation. By adding the salt, the same sterilizing power as before the change is secured, and the corrosion of the metal is suppressed. The operation of “adding hypochlorite to match the redox potential” can be easily automated. In this way, even when the system conditions fluctuate, the nitrogen content and COD content of the aqueous water due to excessive addition and the like are maintained by keeping the concentration of the halogen stabilizer in the treated water system constant at the necessary minimum appropriate concentration. Can be suppressed.

That is, the invention according to claim 1 is an aqueous treatment method for suppressing microbial damage in an aqueous system,
(1) means for measuring the oxidation-reduction potential of water to be treated;
(2) means for adjusting the addition amount of the hypohalous acid generating compound so that the oxidation-reduction potential is in the range of 300 to 700 mV (silver / silver chloride electrode with saturated KCL);
(3) Concentration measurement target selected from organic phosphate compound, polymerized phosphate compound, orthophosphoric acid, anionic polymer electrolyte, water-soluble zinc compound, water-soluble molybdate compound, benzotriazole and its derivatives, and water-soluble lithium compound Means for measuring the concentration of the compound in the treated water system;
(4) A composition containing (a) one or more compounds of the concentration measurement target compound and (b) one or more halogen stabilizers selected from sulfamic acid and sulfonamide is added to the treated water system. However, the present invention relates to an aqueous treatment method characterized by comprising means for adjusting the amount of the composition to be added based on the measurement result of the concentration measurement target compound.

  The invention according to claim 2 relates to an aqueous treatment method according to claim 1, wherein the additive concentration of the halogen stabilizer to the treated water system is in the range of 0.01 to 5 mmol / L.

  According to the water treatment method of the present invention, a hypohalous acid generating compound and a halogen stabilizer are added to various water systems such as a cooling water system, a pulp and paper process water system, a dust collection water system, a scrubber water system, and a waste water system. When controlling microbial damage, halogen stabilizers are effectively utilized to obtain excellent bactericidal and algicidal effects with low corrosiveness at the minimum required concentration, and by reducing the amount used, the halogen stabilization The purpose can be achieved by a simple and inexpensive method that reduces the nitrogen content and COD content derived from the agent and does not require a complicated and expensive analyzer or controller.

It is a systematic diagram which shows the test apparatus used for the Example.

The aqueous treatment method of the present invention is an aqueous treatment method for suppressing microbial damage in an aqueous system,
(1) means for measuring the oxidation-reduction potential of water to be treated;
(2) means for adjusting the addition amount of the hypohalous acid generating compound so that the oxidation-reduction potential is in the range of 300 to 700 mV (saturated KCl-containing silver / silver chloride electrode standard);
(3) Concentration measurement target selected from organic phosphate compound, polymerized phosphate compound, orthophosphoric acid, anionic polymer electrolyte, water-soluble zinc compound, water-soluble molybdate compound, benzotriazole and its derivatives, and water-soluble lithium compound Means for measuring the concentration of the compound in the treated water system;
(4) A composition containing (a) one or more compounds of the concentration measurement target compound and (b) one or more halogen stabilizers selected from sulfamic acid and sulfonamide is added to the treated water system. However, it has means for adjusting the addition amount of the composition based on the measurement result of the concentration of the concentration-measurement target compound.

  The means for measuring the oxidation-reduction potential of the present invention includes a reference electrode and a platinum electrode that are immersed in the water to be treated to measure the oxidation-reduction potential, and their supports, and a potentiometer that measures the potential difference between the reference electrode and the platinum electrode. Composed. As a reference electrode for measuring the oxidation-reduction potential, a silver / silver chloride electrode, a saturated calomel electrode, a mercuric sulfate electrode, a mercury oxide electrode, or the like can be used, and a silver / silver chloride electrode is generally used. Moreover, you may use the composite electrode which integrated the reference electrode and the platinum electrode. These electrodes are not particularly limited, and commercially available ones can be used. Different reference electrodes have different oxidation-reduction potential values, but even if the reference electrodes are different, they can be converted into specific reference electrode reference values by adjusting specific conversion values. Such converted values are described, for example, in the Chemical Handbook Basic Edition (edited by the Chemical Society of Japan, published by Maruzen).

  As a potentiometer for measuring the potential difference between the reference electrode and the platinum electrode, a pH meter capable of displaying a potential, an electrometer, a potentiometer, a digital multimeter, a recorder capable of inputting a voltage, and the like can be used.

  Since the oxidation-reduction potential has a high correlation with the bactericidal and algicidal power, it is suitable for the management of the bactericidal and algicidal effects. The oxidation-reduction potential is the sum of the oxidative power of each oxidizing substance present in water. The total residual chlorine concentration, free residual chlorine concentration, or combined chlorine concentration cannot be determined from the oxidation-reduction potential, and depends on the oxidation-reduction potential. Management and residual chlorine management are completely different.

  Total residual chlorine is the sum of free residual chlorine and combined residual chlorine, free residual chlorine is the total of hypochlorous acid and hypochlorite ion, and combined residual chlorine is the total of chloramine and various N-chloro compounds. However, hypochlorous acid and hypochlorite ions, chloramine and various N-chloro compounds have different oxidizing powers, and the oxidizing power of these substances changes when the operating conditions (especially pH) of the system change. Therefore, in many cases, sufficient sterilization effect and algicidal effect cannot be obtained only by management of total residual chlorine and free residual chlorine.

  In the present invention, the addition amount of the hypohalous acid generating compound is adjusted so that the oxidation-reduction potential is in the range of 300 to 700 mV (saturated KCl-containing silver / silver chloride electrode standard). The oxidation-reduction potential to be maintained varies depending on the system conditions, tolerance to biological contamination, the type of problematic microorganisms and aquatic organisms, etc., but when less than 300 mV, the hypohalous acid concentration is low and sufficient sterilization effect cannot be obtained. There is. Moreover, when it exceeds 700 mV, the concentration of hypohalous acid becomes very high, and the amount of hypohalous acid added to maintain this becomes not only an improvement in the effect commensurate with the increase in the amount added, It is not preferable because corrosion to metal also increases.

  The step of adjusting the amount of hypohalous acid added based on the measurement result of the oxidation-reduction potential is composed of a hypohalous acid generating compound supply device and a control unit. Here, the control unit compares the measured value of the oxidation-reduction potential with the set value, and gives an output to the hypohalous acid generating compound supply device. For example, if a redox potential range is set corresponding to the hypohalous acid concentration that maintains the sterilizing effect of the water to be treated, and the redox potential is less than the set range value, the hypohalous acid generating compound Operate the addition equipment. When the oxidation-reduction potential reaches within the set range, the oxidation-reduction potential of the water to be treated is maintained by stopping the addition apparatus for the hypohalous acid generating compound.

  The hypohalous acid generating compound of the present invention is a compound that generates hypochlorous acid and / or hypobromite, and specifically, hypochlorite, hypobromite, liquefied chlorine, bromine Halogenated dimethylhydantoin compounds such as bromine chloride, bromochlorodimethylhydantoin, dibromodimethylhydantoin, dichlorodimethylhydantoin, and alkali metal salts such as trichloroisocyanuric acid, dichloroisocyanuric acid, chloroisocyanuric acid and their sodium and potassium salts, There are combinations of ammonium salts, and bromides such as sodium bromide, ammonium bromide, potassium bromide, magnesium bromide and the like, and hypochlorous acid by mixing hypochlorite aqueous solutions. May be used in combination of two or more. Examples of the form of hypochlorite and hypobromite include sodium salt, potassium salt, lithium salt, calcium salt, magnesium salt, ammonium salt, and the like, from the viewpoint of water solubility and economy. Therefore, the sodium salt is preferred. In the present invention, these hypohalous acid generating compounds may be used alone or in combination of two or more.

Concentration measurement target compounds of the present invention include organic phosphate compounds, polymerized phosphate compounds, orthophosphoric acid, anionic polymer electrolytes, water-soluble zinc compounds, water-soluble molybdate compounds, benzotriazole and derivatives thereof, and water-soluble lithium compounds. Selected. The concentration measurement target compound is known as a corrosion inhibitor and a scale inhibitor except for a water-soluble lithium compound, and is added to the water to be treated for the purpose of preventing the corrosion of metal and preventing the scale.

  Examples of the organic phosphoric acid compound of the present invention include organic phosphonic acids, phosphonocarboxylic acids, and phosphinopolycarboxylic acids.

  The organic phosphonic acid is an organic compound having one or more phosphono groups in the molecule, specifically, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriamine. Examples include pentamethylene phosphonic acid and hexamethylene diamine tetramethylene phosphonic acid, and 1-hydroxyethylidene-1,1-diphosphonic acid is preferable.

  The phosphonocarboxylic acid is an organic compound having one or more phosphono groups and one or more carboxyl groups in the molecule, specifically, 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxyphosphonoacetic acid. , Phosphonopolymaleic acid, phosphonic succinic acid, and the like, preferably 2-phosphonobutane-1,2,4-tricarboxylic acid and phosphonopolymaleic acid. Here, phosphonocarboxylic acid is commercially available from Rhodia under the trade name BRICORRR288 and from BWA under the trade name BELCOR585. The phosphonocarboxylic acid can be produced, for example, by heating phosphorous acid and monoethylenically unsaturated carboxylic acid in a neutral to alkaline aqueous solvent in the presence of a free radical initiator (for example, special (Kaihei 4-334392). The phosphonocarboxylic acid can be obtained by reacting a reaction product of hypophosphorous acid with a carbonyl compound or an imine compound with an unsaturated carboxylic acid in the presence of a reaction initiator (Japanese Patent No. 3284318). .

  The phosphinopolycarboxylic acid is a compound having one or more phosphino groups and two or more carboxyl groups in the molecule, and specifically, bis-poly (obtained by reacting acrylic acid and hypophosphorous acid. 2-Carboxyethyl) phosphinic acid, bis-poly (1,2-dicarboxyethyl) phosphinic acid obtained by reacting maleic acid and hypophosphorous acid, maleic acid, acrylic acid and hypophosphorous acid Bis-poly [2-carboxy- (2-carboxymethyl) ethyl] obtained by reacting the resulting poly (2-carboxyethyl) (1,2-dicarboxyethyl) phosphinic acid, itaconic acid and hypophosphorous acid Examples include phosphinic acid, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid and hypophosphorous acid, preferably acrylic acid and maleic acid. It is a reaction product of acid and hypophosphorous acid, a reaction product of itaconic acid, maleic acid and hypophosphorous acid. The preparation of phosphinopolycarboxylic acid is usually carried out by heating hypophosphorous acid and monoethylenically unsaturated carboxylic acid in an aqueous solvent in the presence of a free radical initiator, for example, JP-B-54-29316. No. 5, JP-B-5-57992 and JP-B-6-47113. Further, phosphinopolycarboxylic acids are commercially available from Bio Labs under trade names such as BELCLENE500, BELPERSE164, and BELCLENE400.

  The polymerized phosphoric acid compound of the present invention is a polymerized phosphate having a degree of polymerization of 2 to 100 such as pyrophosphate, tripolyphosphate, hexametaphosphate and the like.

  The orthophosphoric acid of the present invention is phosphoric acid, primary phosphate, secondary phosphate, or tertiary phosphate.

  The anionic polymer electrolyte of the present invention is a water-soluble polymer compound having a molecular weight of 500 or more having a plurality of carboxyl groups or sulfonic acid groups in the molecule, and is mainly used for corrosion prevention and scale prevention in aqueous systems. It is added to the treated water system. Examples of anionic polyelectrolytes include acrylic acid mono- or copolymers, maleic acid mono- or copolymers, itaconic acid mono- or copolymers, 2-acrylamido-2-methylpropanesulfonic acid And a mono- or copolymer of 3-allyloxy-2-hydroxy-1-propanesulfonic acid, a mono- or copolymer of isopropyl sulfonic acid, and the like.

  The water-soluble zinc compound of the present invention may be anything as long as it dissolves in water and releases zinc ions, but water-soluble zinc salts such as zinc chloride, zinc sulfate, zinc nitrate, and zinc sulfamate are preferred.

  The water-soluble molybdate compound of the present invention is not particularly limited as long as it dissolves in water and generates molybdate ions, but is preferably molybdic acid, sodium molybdate, potassium molybdate or the like.

  The benzotriazole and derivatives thereof of the present invention include 1,2,3-benzotriazole, substituted-1,2,3-benzotriazole (alkyl groups, carboxyl groups, chlorine, bromine, hydroxyl groups, nitro groups, sulfonic acids as substituents One or more selected from a group and a phosphonic acid group), and a combination of two or more of these may be used.

Water-soluble lithium compound of the present invention, the treated aqueous system is a low density material capable of concentration analysis in quality be inert.

  As a means for measuring the concentration of the concentration measurement target compound of the present invention in the treated water system, a method known as a concentration analysis method for these compounds can be used.

  For example, the means for measuring the concentration of the organic phosphoric acid compound and the polymerized phosphoric acid compound according to the present invention is that orthophosphoric acid compound or polymerized phosphoric acid compound contained in water to be treated is treated with orthophosphoric acid, heat, light, etc. under strong acidity. After decomposition into an acid, orthophosphoric acid is analyzed by absorptiometry (molybdenum blue method) and measured as a phosphoric acid equivalent concentration. As an analysis method of the organic phosphate compound and the polymerized phosphate compound, for example, an analysis method of hydrolyzable phosphorus or total phosphorus in JIS K0101: 1998 “Industrial Water Test Method” can be used.

  The means for measuring the concentration of the anionic polymer electrolyte of the present invention is measured by, for example, a polymer turbidimetric method, a fluorometric method, an ultraviolet absorptiometric method, or the like. Here, the polymer turbidimetric method quantitatively reacts an anionic polyelectrolyte with a cationic compound to generate stable white turbidity, measures the intensity of transmitted light or scattered light, and creates a calibration curve prepared in advance. The concentration of the anionic polymer electrolyte is obtained more. As a cationic compound that reacts quantitatively with an anionic polyelectrolyte to produce a stable white turbidity, it is a quaternary ammonium salt having 12 or more carbon atoms. As a specific example of a quaternary ammonium salt, a tetraalkyl Ammonium salts, trialkylbenzylammonium salts, dialkyldibenzylammonium salts, alkyltribenzylammonium salts, benzethonium salts, benzalkonium salts, alkylpyridinium salts, imidazolinium salts and derivatives thereof. The quaternary ammonium salt may have two or more quaternary ammonium groups in the molecule. The form of the quaternary ammonium salt is chloride, bromide, iodide, sulfate or the like. By adding a chelating agent together with the cationic compound, it is possible to mask the metal ions coexisting in the sample water from interfering with the quantitative reaction between the quaternary ammonium salt and the anionic polymer electrolyte. Moreover, it can also be made to act as a pH buffer at the time of reaction by adding a chelating agent as a neutralization salt. As chelating agents, aminocarboxylic acids such as ethylenediaminetetraacetate, nitrilotriacetate, diethylenetriaminepentaacetate, and hydroxy acids such as citrate, malate, tartrate, glycolate can be used. Or two or more types are used in combination.

  A monomer having fluorescence or ultraviolet absorption activity is polymerized at the time of polymerization of the anionic polyelectrolyte, or a compound having fluorescence or ultraviolet absorption activity is reacted with the anionic polyelectrolyte and subjected to fluorometry or ultraviolet absorption photometry. The concentration in the treated water may be measured.

  Means for measuring the concentration of the benzotriazole and derivatives thereof of the present invention are, for example, a fluorescence method, an ultraviolet absorptiometry, a liquid chromatograph method and the like. A method for measuring the concentration of benzotriazole and its derivatives by the ultraviolet absorptiometry is disclosed in JP-A-9-229851.

  The means for measuring the concentration of the water-soluble zinc compound of the present invention includes, for example, atomic absorption method, ICP emission analysis method, ICP mass spectrometry method, EDTA titration method and the like.

  Means for measuring the concentration of the water-soluble molybdate compound of the present invention include, for example, ICP emission spectrometry, ICP mass spectrometry, thioglycolic acid absorptiometry, and the like.

It means for analyzing the water-soluble lithium compound of the present invention atomic absorption spectrometry, ICP emission spectrometry, how the ion electrode method can be used.

  As the halogen stabilizer of the present invention, at least one selected from sulfamic acid and sulfonamide is used. The sulfamic acid is water-soluble such as sodium salt, potassium salt, lithium salt, calcium salt, magnesium salt, ammonium salt and the like. The sulfonamide may be a salt, for example, p-toluenesulfonamide, m-toluenesulfonamide, o-toluenesulfonamide, imidodisulfonamide, benzenesulfonamide, alkylsulfonamide, sulfamide, etc., but sulfamic acid Alternatively, sulfonamides may be used alone or in combination of two or more.

  Preferable examples of the halogen stabilizer are sulfamic acid, p-toluenesulfonamide, benzenesulfonamide, and alkylsulfonamide, and more preferable is sulfamic acid.

  The concentration of the halogen stabilizer of the present invention added to the water system to be treated is preferably 0.01 to 5 mmol / L, more preferably 0.03 to 1 mmol / L. The additive concentration of the halogen stabilizer is set according to the degree of contamination in the system and the system conditions. For example, it is added in the range of 0.1 to 5 mmol / L at the start of operation of a system with a lot of contamination or the system, and there is little contamination. In the system, it is added in the range of 0.01 to 0.1 mmol / L.

  In the present invention, the concentration measurement is carried out while adding a composition containing one or more compounds of the concentration measurement target compound and one or more halogen stabilizers selected from sulfamic acid and sulfonamide to the water to be treated. A means for adjusting the addition amount of the composition based on the measurement result of the concentration of the target compound;

  Here, the blending ratio in the composition of the concentration measurement target compound and the halogen stabilizer of the present invention is the amount required for the original purpose of adding the concentration measurement target compound (for example, corrosion suppression, scale suppression, tracer, etc.). It is simply calculated as the ratio of the concentration in the treated water and the required concentration of the halogen stabilizer in the treated water, and does not need to be in a specific range. That is, while adding the composition containing the concentration measurement target compound and the halogen stabilizer whose mixing ratio was calculated by the above method to the treated water system, analyzing the concentration of the concentration measurement target compound in the treated water, Therefore, the concentration of the halogen stabilizer can be maintained within the proper range by adjusting the amount of the composition added so that the concentration of the concentration measurement target compound is within the proper range.

In the present invention, the addition concentration of the hypohalous acid generating compound in the water to be treated is adjusted based on the measurement result of the oxidation-reduction potential, but usually 0.1 to 100 mg / L in terms of Cl ₂ as effective halogen. It is a range.

  Although the pH of the to-be-processed water system in this invention is not specifically limited, Usually, it is the range of pH3.0-10.0.

The water system to which the water treatment method of the present invention is applied is not particularly limited, and examples thereof include a cooling water system, a paper pulp process water system, a dust collection water system, a scrubber water system, and a drainage water system.
By applying the water treatment method of the present invention to these water systems, even if the environment is exposed to sunlight or copper or copper alloy materials are used in piping and heat exchangers, the target water system is effective. In addition to being able to perform sterilization and algaecide treatment, a halogen stabilizer can be effectively utilized, and the amount of nitrogen and COD derived from the halogen stabilizer can be reduced by reducing the amount used.

  The water treatment method of the present invention not only kills various aerobic bacteria, anaerobic bacteria, facultative anaerobic bacteria, fungi, yeasts and other microorganisms, shellfish, protozoa, algae, etc., but already adheres to the system. It is also possible to peel off and remove living microorganisms and aquatic organisms. It is also effective against Legionella pneumophila.

  The present invention will be specifically described below, but the present invention is not limited to these examples.

Example 1
An example of an embodiment of the present invention is shown in FIG. The open-type circulating water system includes a cold water tower 8, a circulating pump 9, a heat exchanger 10, a circulating water line 11, a makeup water line 12, and a forced blow line 13. A redox potential measuring cell 3 is installed in the circulating water line 11, and a platinum electrode 1 and a reference electrode (silver / silver chloride electrode) 2 are inserted into the redox potential measuring cell 3. A potentiometer 4 was connected between the silver chloride electrode) 2 and the oxidation-reduction potential was measured. The output signal from the potentiometer 4 is input to the control unit 5. The control unit 5 compares the measured value of the oxidation-reduction potential with the set value, and supplies the hypohalous acid generating compound when the measured value is lower than the set value. An output signal was sent to the pump 6, and the hypohalous acid generating compound entered in the hypohalous acid generating compound tank 7 was added to the open circulating water system.

  A signal from the electrical conductivity measurement cell 14 immersed in the circulating water of the chilled water tower 8 is input to the electrical conductivity indicating controller 15 to measure the electrical conductivity of the circulating water, and the measured value and set value of the electrical conductivity are measured. In comparison, when the measured value is higher than the set value, an output signal is sent to the blow-down valve 16, the blow-down valve 16 is opened to blow down the circulating water at a constant flow rate, and at the same time, output to the composition supply pump 17. The composition supply pump 17 is actuated by sending a signal, and the circulating water in the chilled water tower 8 is supplied to the composition containing the concentration target compound and the halogen stabilizer in the composition tank 18 by an amount corresponding to the maintenance concentration in the circulating water. Added to.

The electrical conductivity of the circulating water was maintained in the range of 900 ± 10 μS / cm, but the pH varied between 8.5 and 9.0. The water temperature of the circulating water line 11 was 35 ° C. at the inlet of the heat exchanger 10 and 50 ° C. at the outlet. The flow rate in the heat exchanger tube was 0.3 m / s.
An aqueous sodium hypochlorite solution (containing 1% of effective chlorine in terms of Cl ₂ ) is placed in the hypohalous acid generating compound tank 7 and when the oxidation-reduction potential becomes 450 mV or less, the controller 5 generates the hypohalous acid generating compound. An output signal is sent to the supply pump 6 to operate the hypohalous acid generating compound supply pump 6 to supply the hypohalous acid generating compound that has entered the hypohalous acid generating compound tank 7 to the open circulating water system. When the voltage became 450 mV or more, the output signal was turned off and the hypohalous acid generating compound supply pump 6 was stopped. Thereafter, this step was repeated.

  In the composition tank 18, 10% of polymaleic acid (Berkulen 200LA manufactured by BWA), a copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid (copolymerization ratio 50: 50% by weight, weight average molecular weight) About 6,000), 6.8% sulfamic acid, 1% methylbenzotriazole, and 10% sodium hydroxide.

  The concentration of the composition in the circulating water was analyzed by polymer turbidimetry. That is, 1 mL of reagent A (dissolved 364 g of monoethanolamine and 465 g of ethylenediaminetetraacetic acid / disodium in 1 L of pure water) and 10 g of reagent B (40 g of benzethonium chloride and 62 g of monoethanolamine in 1 L of pure water) were added to 10 mL of filtered circulating water. 1 mL of sodium citrate dihydrate (250 g dissolved) was added, stirred well, allowed to stand for 10 minutes, and then added with 1 mL of reagent A only to circulating water filtered using a spectrophotometer at 420 nm as a control. Absorbance was measured. The composition supply pump 17 obtains the composition concentration from the absorbance of the circulating water determined by the polymer turbidimetric method from the relationship between the composition concentration and the absorbance prepared in advance, so that the composition concentration in the circulating water becomes 100 mg / L. The amount of discharge was adjusted.

During the test period of 1 month, the redox potential was maintained in the range of 450 ± 1 mV, but the total number of bacteria in the circulating water was 1 × 10 ² cells / mL or less. The average concentration of the composition during the test period was 105 mg / L on average, and the average addition concentration of sulfamic acid was 0.074 mmol / L. The corrosion rate of a carbon steel tube (JIS G3445: STKM11A, outer diameter 12.7 mm, length 500 mm) set in the heat exchanger 10 is 1.9 mdd, a copper alloy tube (JIS H3300: C6871 brass for condenser 2) The corrosion rate of the seed, the outer diameter of 12 mm, and the length of 500 mm was 0.1 mdd, and no pitting corrosion was observed on the test tube surface. Also, no algae adhered to the cooling tower. The nitrogen concentration derived from the halogen stabilizer was 1.0 mg / L.

(Example 2)
5% of 2-phosphonobutane-1,2,4-tricarboxylic acid, 4% of sodium hexametaphosphate, 2% of phosphoric acid, copolymer of acrylic acid and 3-allyloxy-2-hydroxy-1-propanesulfonic acid ( A composition containing 10% of a copolymerization ratio of 50: 50% by weight, a weight average molecular weight of about 5,000), 3.4% of sulfamic acid and 0.6% of benzotriazole, The test was conducted in the same manner as in Example 1 except that the concentration was measured by the total phosphoric acid concentration measurement method. Here, the total phosphoric acid concentration was measured by the total phosphorus analysis method of JIS K0101: 1998. During the 1-month test period, the redox potential was maintained in the range of 400 ± 1 mV, but the total number of bacteria in the circulating water was 1 × 10 ² cells / mL or less. The addition concentration of the composition during the test period was 102 mg / L on average, and the average addition concentration of sulfamic acid was 0.036 mmol / L. The corrosion rate of the carbon steel tube set in the heat exchanger 10 was 1.5 mdd, the corrosion rate of the copper alloy tube was 0.2 mdd, and no pitting corrosion was observed on the test tube surface. Also, no algae adhered to the cooling tower. The nitrogen concentration derived from the halogen stabilizer was 0.5 mg / L.

Example 3
The oxidation-reduction potential was set to 500 mV, 5% of polyitaconic acid (average molecular weight 2,000), a copolymer of acrylic acid and isopropylsulfonic acid copolymer (copolymerization ratio 50: 50% by weight, weight average molecular weight of about 10,000%), zinc oxide 2.2%, sulfamic acid 8.5%, benzotriazole 1%, and sodium hydroxide 1.5%. The test was conducted in the same manner as in Example 1 except that the measurement was performed by the ultraviolet absorptiometry. During the one month test period, the redox potential was maintained in the range of 500 ± 1 mV, but the total number of bacteria in the circulating water was 1 × 10 ² cells / mL or less. The average addition concentration of the composition during the test period was 98 mg / L, and the average addition concentration of sulfamic acid was 0.086 mmol / L. The corrosion rate of the copper alloy specimen (JIS H3100: C1201 Phosphorous Deoxidized Copper 1A, 1 × 13 × 50 mm) set in the circulating water line 11 is 0.3 mdd, and pitting corrosion is observed on the specimen surface. There wasn't. Also, no algae adhered to the cooling tower. The nitrogen concentration derived from the halogen stabilizer was 1.2 mg / L.

Example 4
10% of polymaleic acid (Berkulen 200LA manufactured by BWA), 10% of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid (copolymerization ratio 50: 50% by weight) copolymer (weight average molecular weight about 6,000) %, 5% of p-toluenesulfonamide, 1% of benzotriazole and 10% of sodium hydroxide were added, and the test was conducted in the same manner as in Example 1. During the test period of 1 month, the redox potential was maintained in the range of 450 ± 1 mV, but the total number of bacteria in the circulating water was 1 × 10 ² cells / mL or less. The addition concentration of the composition during the test period was 100 mg / L on average, and the average addition concentration of p-toluenesulfonamide was 0.029 mmol / L. The corrosion rate of the carbon steel tube set in the heat exchanger 10 was 2.2 mdd, the corrosion rate of the copper alloy tube was 0.3 mdd, and no pitting corrosion was observed on the test tube surface. Also, no algae adhered to the cooling tower. The nitrogen concentration derived from the halogen stabilizer was 0.4 mg / L.

(Example 5)
The test was performed in the same manner as in Example 1 except that the set value of the oxidation-reduction potential was set to 310 ± 1 mV. The average addition concentration of the composition during the test period was 105 mg / L, and the average addition concentration of sulfamic acid was 0.074 mmol / L. The total number of bacteria in the circulating water was 1 × 10 ³ cells / mL. No algae adhered to the cooling tower. The corrosion rate of the carbon steel tube set in the heat exchanger 10 was 2.2 mdd, and the corrosion rate of the copper alloy tube was 0.3 mdd.

(Example 6)
The test was performed in the same manner as in Example 1 except that the set value of the oxidation-reduction potential was set to 690 ± 1 mV. The average addition concentration of the composition during the test period was 105 mg / L, and the average addition concentration of sulfamic acid was 0.074 mmol / L. The total number of bacteria in the circulating water was 1 × 10 ² cells / mL or less. No algae adhered to the cooling tower. The corrosion rate of the carbon steel tube set in the heat exchanger 10 was 3.8 mdd, and the corrosion rate of the copper alloy tube was 0.5 mdd.

(Example 7)
The test was performed in the same manner as in Example 1 except that the amount of the composition added was 4250 mg / L. At this time, the average addition concentration of sulfamic acid was 3.0 mmol / L. The total number of bacteria in the circulating water was 1 × 10 ² cells / mL or less. No algae adhered to the cooling tower. The corrosion rate of the carbon steel tube set in the heat exchanger 10 was 4.5 mdd, and the corrosion rate of the copper alloy tube was 0.6 mdd.

(Comparative Example 1)
The test was performed in the same manner as in Example 1 except that the set value of the oxidation-reduction potential was set to less than 300 mV. The average addition concentration of the composition during the test period was 105 mg / L, and the average addition concentration of sulfamic acid was 0.074 mmol / L. Although the oxidation-reduction potential was in the range of 250 to 299 mV, the total number of bacteria in the circulating water varied between 1 × 10 ^{4 and} 1 × 10 ⁵ cells / mL. Moreover, adhesion of algae was observed in the cooling tower. The corrosion rate of the carbon steel tube set in the heat exchanger 10 was 5.2 mdd, and the corrosion rate of the copper alloy tube was 0.8 mdd.

(Comparative Example 2)
Example 1 except that instead of the oxidation-reduction potential measurement, a residual chlorine automatic analyzer (CL-17 model, manufactured by Hack) was installed by the DPD colorimetric method, and the treatment agent supply pump was controlled by the total residual chlorine concentration. Were tested in the same manner. Here, when the total residual chlorine concentration becomes 4 mg / L or less, an output signal is sent from the control unit 5 to the hypohalous acid generating compound supply pump 6 to operate the processing agent supply pump 6 and the hypohalous acid generating compound tank. The composition No. 7 was supplied, and when the total residual chlorine concentration reached 5 mg / L or more, the output signal was turned off and the hypohalous acid generating compound supply pump 6 was stopped. The discharge rate of the composition supply pump 17 was adjusted so that the free residual chlorine concentration was 1 mg / L or less. During the one month test period, the total residual chlorine concentration was maintained in the range of 4-5 mg / L, while the free residual chlorine concentration varied in the range of 0.1-0.9 mg / L. The oxidation-reduction potential at this time was often less than 300 mV, and was a minimum of 250 mV. The concentration of the composition varied between 50 and 200 ppm, and the addition concentration of sulfamic acid varied between 0.035 and 0.14 mmol / L. The total number of bacteria in the circulating water varied between 1 × 10 ^{2 and} 1 × 10 ³ cells / mL. Moreover, adhesion of algae was observed in the cooling tower. The corrosion rate of the carbon steel tube set in the heat exchanger 10 was 9.7 mdd, and the corrosion rate of the copper alloy tube was 1.2 mdd.

(Comparative Example 3)
Using the same test apparatus as in Comparative Example 1, an aqueous solution containing 7% sodium hypochlorite and 20% sodium sulfamate in terms of Cl ₂ was placed in the hypohalous acid generating compound tank 7, and the total residual chlorine concentration was When it becomes 1 mg / L or less, the controller 5 sends an output signal to the hypohalous acid generating compound supply pump 6 to operate the processing agent supply pump 6 to supply the composition of the hypohalous acid generating compound tank 7. When the total residual chlorine concentration reached 2 mg / L or more, the output signal was turned off and the hypohalous acid generating compound supply pump 6 was stopped.
During the one month test period, the total residual chlorine concentration was maintained in the range of 1-2 mg / L and the free residual chlorine concentration was in the range of 0.01-0.1 mg / L. The total number of bacteria in the circulating water varied between 1 × 10 ^{3 and} 1 × 10 ⁴ cells / mL. In addition, a large amount of algae adhered to the cooling tower. The corrosion rate of the carbon steel tube set in the heat exchanger 10 was 6.4 mdd, and the corrosion rate of the copper alloy specimen was 1.0 mdd. The nitrogen concentration derived from the halogen stabilizer was 3.6 mg / L.

  From the results of Examples 1, 5, and 6 and the result of Comparative Example 1, the aqueous treatment method of the present invention for adjusting the redox potential to be in the range of 300 to 700 mV is excellent in both sterilization effect and corrosion inhibition. I understand that. In addition, the results of Example 1 of the present invention in which the treatment was controlled by the oxidation-reduction potential and the results of Comparative Example 2 in which the conventional technique for management by the total residual chlorine concentration and the free residual chlorine concentration was applied instead of the oxidation-reduction potential. In comparison, it can be seen that the aqueous treatment method of the present invention is superior in both sterilization effect and corrosion inhibition. Furthermore, although the comparative example 3 is an example which applied the stabilization sodium hypochlorite process using the aqueous solution containing sodium hypochlorite and sodium sulfamate, when the result is compared with the result of Example 1, it is a comparison. It is understood that the treatment method of Example 3 is difficult to reduce not only the bactericidal effect and the corrosion inhibiting effect but also the nitrogen content derived from the halogen stabilizer as compared with the aqueous treatment method of the present invention.

  In the water-based treatment method of the present invention, an excellent bactericidal / algicidal effect can be obtained with low corrosion by reacting the secondary halogen salt and the halogen stabilizer efficiently without excess or deficiency. Furthermore, COD and nitrogen load derived from sulfamic acid can be reduced.

1: platinum electrode 2: reference electrode 3: oxidation-reduction potential measurement cell 4: potentiometer 5: control unit 6: hypohalous acid generating compound supply pump 7: hypohalous acid generating compound tank 8: cold water tower 9: circulation pump 10: Heat exchanger 11: Circulating water line 12: Makeup water line 13: Forced blow line 14: Electrical conductivity measurement cell 15: Electrical conductivity indicating controller 16: Blow down valve 17: Composition supply pump 18: Composition tank

Claims (2)

An aqueous treatment method for suppressing microbial damage in an aqueous system,
(1) means for measuring the oxidation-reduction potential of water to be treated;
(2) means for adjusting the addition amount of the hypohalous acid generating compound so that the oxidation-reduction potential is in the range of 300 to 700 mV (saturated KCl-containing silver / silver chloride electrode standard);
(3) Concentration measurement target selected from organic phosphate compound, polymerized phosphate compound, orthophosphoric acid, anionic polymer electrolyte, water-soluble zinc compound, water-soluble molybdate compound, benzotriazole and its derivatives, and water-soluble lithium compound Means for measuring the concentration of the compound in the treated water system;
(4) A composition containing (a) one or more compounds of the concentration measurement target compound and (b) one or more halogen stabilizers selected from sulfamic acid and sulfonamide is added to the treated water system. However, it has a means to adjust the addition amount of this composition based on the measurement result of the density | concentration of the said compound for a density | concentration measurement object, The aqueous processing method characterized by the above-mentioned. The method for treating an aqueous system according to claim 1, wherein the concentration of the halogen stabilizer added to the treated water system is in the range of 0.01 to 5 mmol / L.

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