Sterilization method for ion exchangers

Abstract

To provide a sterilization method of an ion exchanger capable of suppressing degradation of an ion exchanger while suppressing proliferation of microorganisms.SOLUTION: Provided is a sterilization method of an ion exchanger for sterilizing an ion exchanger, in which at least one of bromine-based oxidant as a sterilization agent, a stabilized hypochlorous acid composition containing chlorine-based oxidant and a sulfamic acid compound, and a stabilized hypobromous acid composition containing bromine-based oxidant and a sulfamic acid compound is added to water flowing into the ion exchanger.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for sterilizing an ion exchanger.

Background Art

[0002] With the recent water shortage, the water recovery rate in factories has been increasing. When an ion exchange resin is used in water recovery, there are cases where water with a high content of organic substances such as drainage directly flows into the ion exchange resin. In that case, microorganisms may grow on the ion exchange resin, which may deteriorate the treated water quality or cause a decrease in operating efficiency (see Patent Document 1).

[0003] Patent Document 2 describes that, as a sterilization treatment for an ion exchange resin, hot water sterilization or water containing hypochlorous acid is temporarily introduced.

[0004] However, since hypochlorous acid is an oxidizing agent, there is a concern that it may oxidatively deteriorate the ion exchange resin. When the ion exchange resin deteriorates, eluates derived from the ion exchange resin may adversely affect the devices in the subsequent stage of the ion exchange resin treatment and the water quality of the treated water (see Patent Document 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a method for sterilizing an ion exchanger that can suppress the growth of microorganisms while suppressing the deterioration of the ion exchanger. [Means for solving the problem]

[0007] The present invention relates to a method for sterilizing an ion exchanger, wherein at least one of the following is added as a disinfectant to the water flowing into the ion exchanger: a brominated oxidizing agent, a stabilized hypochlorous acid composition containing a chlorine-based oxidizing agent and a sulfamic acid compound, and a stabilized hypobromous acid composition containing a brominated oxidizing agent and a sulfamic acid compound. Furthermore, the amount of contact between the ion exchanger and the disinfectant is such that the concentration of available chlorine (mgCl 2 The CT value, which is the product of ( / L) and contact time (h), is 440 (mgCl 2 / L·h) or less This is a method for sterilizing ion exchange materials.

[0008] In the method for sterilizing the ion exchanger, it is preferable that the sterilizing agent is the stabilized hypobromous acid composition.

[0009] In the method for sterilizing the ion exchanger, it is preferable that the ion exchanger is a gel-type ion exchange resin. [Effects of the Invention]

[0011] The present invention provides a method for sterilizing an ion exchanger that can suppress the growth of microorganisms while suppressing the degradation of the ion exchanger. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing a water treatment apparatus to which the sterilization method for ion exchangers according to the present invention can be applied. [Figure 2] This graph shows the change in eluted TOC from the immersion solution of ion exchange resin in a reference example. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below. This embodiment is just one example of how the present invention can be implemented, and the present invention is not limited to this embodiment.

[0014] <Method for sterilizing ion exchangers> The method for sterilizing an ion exchanger according to this embodiment involves adding at least one of the following as a disinfectant to the water flowing into the ion exchanger: a bromine-based oxidizing agent, a stabilized hypochlorous acid composition containing a chlorine-based oxidizing agent and a sulfamic acid compound, and a stabilized hypobromous acid composition containing a bromine-based oxidizing agent and a sulfamic acid compound.

[0015] Figure 1 shows a schematic diagram of an example of a water treatment apparatus to which the ion exchanger sterilization method according to the present invention can be applied, and its configuration will be described.

[0016] The water treatment apparatus 1 includes an ion exchange treatment apparatus 10 having an ion exchanger as an ion exchange treatment means for treating water to be treated using an ion exchanger.

[0017] In the water treatment apparatus 1 shown in Figure 1, a water treatment pipe 12 is connected to the water treatment inlet of the ion exchange treatment apparatus 10, and a treated water pipe 14 is connected to the treated water outlet. A disinfectant addition pipe 16 is connected to the water treatment pipe 12 as a disinfectant addition means for adding at least one of the following as a disinfectant to the water flowing into the ion exchanger upstream of the ion exchange treatment apparatus 10: a brominated oxidizing agent, a stabilized hypochlorous acid composition containing a chlorine-based oxidizing agent and a sulfamic acid compound, and a stabilized hypobromous acid composition containing a brominated oxidizing agent and a sulfamic acid compound.

[0018] The operation of the water treatment device 1, to which the sterilization method for ion exchangers according to this embodiment can be applied, will be described.

[0019] The water to be treated, which is the water flowing into the ion exchanger, is fed into the ion exchange treatment device 10 through the water to be treated pipe 12. Here, in the water to be treated pipe 12, through the disinfectant addition pipe 16, at least one of a stabilized hypochlorous acid composition containing a bromine-based oxidant, a chlorine-based oxidant and a sulfamic acid compound, and a stabilized hypobromous acid composition containing a bromine-based oxidant and a sulfamic acid compound is added to the water to be treated (disinfectant addition step), and the water to be treated to which the disinfectant has been added is fed into the ion exchange treatment device 10. In the ion exchange treatment device 10, ion exchange treatment of the water to be treated is performed (ion exchange treatment step). The treated water after the ion exchange treatment is discharged through the treated water pipe 14.

[0020] A water to be treated tank for storing the water to be treated may be installed in front of the ion exchange treatment device 10. In that case, the disinfectant may be added to the water to be treated in the water to be treated tank, or may be added to the water to be treated in the water to be treated pipe 12.

[0021] The inventors of the present invention have found that by adding at least one of a stabilized hypochlorous acid composition containing a bromine-based oxidant, a chlorine-based oxidant and a sulfamic acid compound, and a stabilized hypobromous acid composition containing a bromine-based oxidant and a sulfamic acid compound to the water to be treated flowing into the ion exchanger, it is possible to suppress the growth of microorganisms while suppressing the deterioration of the ion exchanger. It is possible to suppress the growth of microorganisms without substantially impairing the performance of the ion exchanger.

[0022] [Ion exchanger] There is no particular limitation on the ion exchanger, but ion exchange resins such as anion exchange resins and cation exchange resins that can remove ion components in water are targeted. The shape of the ion exchanger can be a monolithic ion exchanger in addition to the granular ion exchange resin.

[0023] The ion exchange resin may be a gel type or a macroporous type, but in terms of having a smaller surface area and less deterioration when contacting with an oxidant, and having a large exchange capacity, etc., it is preferably a gel type ion exchange resin.

[0024] The water retention capacity of the ion exchanger is, for example, in the range of 30-80%, and the total exchange capacity is, for example, in the range of 0.1-5.0 eq / L·resin.

[0025] The ion exchange treatment device 10 can be any device that performs ion exchange treatment on water to be treated using an ion exchanger, and there are no particular restrictions, but examples include an ion exchange resin tower filled with ion exchange resin, a cartridge, a cylinder, etc.

[0026] [Water to be treated] There are no particular restrictions on the type of water to be treated. Examples of water to be treated include environmental water such as groundwater, river water, and seawater, as well as wastewater discharged from various factories, etc.

[0027] [Fungicide] The disinfectant is at least one of the following: a brominated oxidizing agent, a stabilized hypochlorous acid composition containing a chlorine-based oxidizing agent and a sulfamic acid compound, or a stabilized hypobromous acid composition containing a brominated oxidizing agent and a sulfamic acid compound.

[0028] A "stabilized hypochlorous acid composition containing a chlorine-based oxidizing agent and a sulfamic acid compound" may be a stabilized hypochlorous acid composition containing a mixture of a "chlorine-based oxidizing agent" and a "sulfamic acid compound," or it may be a stabilized hypochlorous acid composition containing the "reaction product of a chlorine-based oxidizing agent and a sulfamic acid compound." A "stabilized hypobromous acid composition containing a bromine-based oxidizing agent and a sulfamic acid compound" may be a stabilized hypobromous acid composition containing a mixture of a "bromine-based oxidizing agent" and a "sulfamic acid compound," or it may be a stabilized hypobromous acid composition containing the "reaction product of a bromine-based oxidizing agent and a sulfamic acid compound."

[0029] Examples of bromine-based oxidizing agents include bromine (liquid bromine), bromine chloride, bromate, bromate salts, and hypobromous acid. Hypobromous acid may also be produced by reacting a bromine compound such as sodium bromide with a chlorine-based oxidizing agent such as hypochlorous acid.

[0030] Examples of bromine compounds include sodium bromide, potassium bromide, lithium bromide, ammonium bromide, and hydrobromic acid. Of these, sodium bromide is preferred from the standpoint of formulation cost and other factors.

[0031] Examples of chlorine-based oxidizing agents include chlorine gas, chlorine dioxide, hypochlorous acid or its salts, chlorous acid or its salts, chloric acid or its salts, perchloric acid or its salts, chlorinated isocyanuric acid or its salts, etc. Among these, examples of salts include alkali metal hypochlorite salts such as sodium hypochlorite and potassium hypochlorite, alkaline earth metal hypochlorite salts such as calcium hypochlorite and barium hypochlorite, alkali metal hypochlorite salts such as sodium chlorite and potassium chlorite, alkaline earth metal hypochlorite salts such as barium chlorite, other metal hypochlorite salts such as nickel chlorite, alkali metal chlorite salts such as ammonium chlorate, sodium chlorate, and potassium chlorate, alkaline earth metal chlorite salts such as calcium chlorate and barium chlorate, etc. These chlorine-based oxidizing agents may be used individually or in combination of two or more. From the viewpoint of handling, etc., sodium hypochlorite is preferred as the chlorine-based oxidizing agent.

[0032] Sulfamic acid compounds are compounds represented by the following general formula (1). R2NSO3H (1) (In the formula, R is independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)

[0033] Examples of sulfamic acid compounds include sulfamic acid (amidosulfuric acid), in which both R groups are hydrogen atoms; sulfamic acid compounds in which one of the two R groups is a hydrogen atom and the other is an alkyl group having 1 to 8 carbon atoms, such as N-methylsulfamic acid, N-ethylsulfamic acid, N-propylsulfamic acid, N-isopropylsulfamic acid, and N-butylsulfamic acid; sulfamic acid compounds in which both of the two R groups are alkyl groups having 1 to 8 carbon atoms, such as N,N-dimethylsulfamic acid, N,N-diethylsulfamic acid, N,N-dipropylsulfamic acid, N,N-dibutylsulfamic acid, N-methyl-N-ethylsulfamic acid, and N-methyl-N-propylsulfamic acid; sulfamic acid compounds in which one of the two R groups is a hydrogen atom and the other is an aryl group having 6 to 10 carbon atoms, such as N-phenylsulfamic acid; or salts thereof. Examples of sulfamate salts include alkali metal salts such as sodium salts and potassium salts, alkaline earth metal salts such as calcium salts, strontium salts and barium salts, other metal salts such as manganese salts, copper salts, zinc salts, iron salts, cobalt salts and nickel salts, ammonium salts and guanidine salts. Sulfamate compounds and their salts may be used individually or in combination of two or more. From the standpoint of environmental impact, sulfamic acid (amidosulfate) is preferred as the sulfamate compound.

[0034] The stabilized hypobromite composition may further contain an alkali. Examples of alkalis include sodium hydroxide, potassium hydroxide, and other alkali hydroxides. Sodium hydroxide and potassium hydroxide may be used in combination from the viewpoint of product stability at low temperatures. The alkali may also be used as an aqueous solution rather than a solid.

[0035] As a stabilized hypobromite composition, in order to further degrade the ion exchanger, it is preferable to have one that contains bromine and a sulfamic acid compound, or one that contains a mixture of bromine and a sulfamic acid compound, for example, a mixture of bromine, a sulfamic acid compound, an alkali, and water, or one that contains a reaction product of bromine and a sulfamic acid compound, for example, a mixture of a reaction product of bromine and a sulfamic acid compound, an alkali, and water.

[0036] Stabilized hypobromite compositions, particularly those containing bromine and sulfamic acid compounds, exhibit superior bactericidal effects compared to chlorine-based oxidizing agents such as hypochlorous acid, while causing virtually no significant degradation of ion exchangers, unlike chlorine-based oxidizing agents such as hypochlorous acid. At typical usage concentrations, the impact on ion exchanger degradation is practically negligible. Therefore, they are ideal as bactericidal agents for ion exchangers. When a reverse osmosis membrane treatment device is installed downstream of an ion exchange treatment device, using a stabilized hypobromite composition can suppress the degradation of the reverse osmosis membrane, thus protecting the reverse osmosis membrane.

[0037] Since the stabilized hypobromite composition can be measured on-site, similar to hypochlorous acid, more accurate concentration control is possible.

[0038] The pH of the stabilized hypobromite composition is, for example, greater than 13.0, and more preferably greater than 13.2. If the pH of the stabilized hypobromite composition is 13.0 or lower, the effective halogen in the stabilized hypobromite composition may become unstable.

[0039] The bromate concentration in the stabilized hypobromous acid composition is preferably less than 5 mg / kg. If the bromate concentration in the stabilized hypobromous acid composition is 5 mg / kg or higher, the bromate ion concentration in the treated water may increase.

[0040] (Method for producing stabilized hypobromite composition) A stabilized hypobromite composition can be obtained by mixing a brominated oxidizing agent with a sulfamic acid compound, and an alkali may be further added.

[0041] A method for producing a stabilized hypobromite composition containing bromine and a sulfamic acid compound preferably includes the step of adding bromine to a mixture containing water, alkali, and a sulfamic acid compound under an inert gas atmosphere and allowing it to react, or the step of adding bromine to a mixture containing water, alkali, and a sulfamic acid compound under an inert gas atmosphere. Adding and reacting under an inert gas atmosphere, or adding under an inert gas atmosphere, lowers the concentration of bromate ions in the stabilized hypobromite composition.

[0042] While there are no limitations on the inert gas used, at least one of nitrogen and argon is preferred from the standpoint of manufacturing and other factors, and nitrogen is particularly preferred from the standpoint of manufacturing cost and other factors.

[0043] The oxygen concentration in the reactor during bromine addition is preferably 6% or less, more preferably 4% or less, even more preferably 2% or less, and particularly preferably 1% or less. If the oxygen concentration in the reactor during the bromine reaction exceeds 6%, the amount of bromate produced in the reaction system may increase.

[0044] The bromine addition rate is preferably 25% by weight or less relative to the total amount of the stabilized hypobromous acid composition, and more preferably 1% by weight or more and 20% by weight or less. If the bromine addition rate exceeds 25% by weight relative to the total amount of the stabilized hypobromous acid composition, the amount of bromate produced in the reaction system may increase. If it is less than 1% by weight, the cleaning power may be inferior.

[0045] The reaction temperature during bromine addition is preferably controlled within the range of 0°C to 25°C, but from the standpoint of manufacturing costs, it is more preferable to control it within the range of 0°C to 15°C. If the reaction temperature during bromine addition exceeds 25°C, the amount of bromate produced in the reaction system may increase, and if it is below 0°C, freezing may occur.

[0046] [Method of adding fungicide] The disinfectant may be added to the water to be treated manually using a disinfectant injection pump or the like, or it may be added automatically to the water to be treated.

[0047] The "stabilized hypochlorous acid composition" may be added to the water to be treated separately, for example, by adding the "chlorine-based oxidizing agent" and the "sulfamic acid compound" separately, or by mixing the stock solutions together before adding them to the water to be treated. The "stabilized hypobromous acid composition" may be added to the water to be treated separately, for example, by adding the "bromine-based oxidizing agent" and the "sulfamic acid compound" separately, or by mixing the stock solutions together before adding them to the water to be treated.

[0048] The method of adding the disinfectant may be continuous addition, where the disinfectant is added to the water to be treated continuously, or intermittent addition, where there is a period of addition and a period of no addition. Intermittent addition is preferred because it shortens the contact time with the ion exchanger while maintaining the disinfecting effect, and further reduces the deterioration of the ion exchanger.

[0049] The disinfectant may be added in the treated water piping 12, or it may be added in a separate treated water tank.

[0050] The amount of contact between the ion exchanger and at least one of the bromine-based oxidizing agent, stabilized hypochlorous acid composition, and stabilized hypobromous acid composition is preferably 9,000,000 (mgCl2 / L·h) or less, and more preferably 440 (mgCl2 / L·h) or less, as a CT value, which is the product of the concentration as available chlorine (mgCl2 / L) and the contact time (h). If the CT value exceeds 9,000,000, the ion exchanger may deteriorate.

[0051] This specification includes the embodiments described below. [1] A method for sterilizing an ion exchanger, A method for sterilizing an ion exchanger, comprising adding at least one of the following as a disinfectant to the water flowing into the ion exchanger: a brominated oxidizing agent, a stabilized hypochlorous acid composition containing a chlorine-based oxidizing agent and a sulfamic acid compound, and a stabilized hypobromous acid composition containing a brominated oxidizing agent and a sulfamic acid compound.

[0052] A method for sterilizing an ion exchanger as described in [2][1], A method for sterilizing an ion exchanger, wherein the disinfectant is the stabilized hypobromous acid composition.

[0053] A method for sterilizing an ion exchanger as described in [3][1] or [2], A method for sterilizing an ion exchanger, wherein the ion exchanger is a gel-type ion exchange resin.

[0054] A method for sterilizing an ion exchanger as described in any one of [4][1] to [3], A method for sterilizing an ion exchanger, wherein the amount of disinfectant in contact with the ion exchanger is 9,000,000 (mgCl2 / L·h) or less, as a CT value which is the product of the concentration as available chlorine (mgCl2 / L) and the contact time (h). [Examples]

[0055] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0056] [Oxidizing agent used] (Stabilized hypobromite composition) Under a nitrogen atmosphere, a stabilized hypobromite composition was prepared by mixing liquid bromine: 16.9 wt%, sulfamic acid: 10.7 wt%, sodium hydroxide: 12.9 wt%, potassium hydroxide: 3.94 wt%, and water: the remainder. The pH of the stabilized hypobromite composition was 14, and the total chlorine concentration was 7.5 wt%. The total chlorine concentration was measured using the total chlorine measurement method (DPD (diethyl-p-phenylenediamine) method) with a HACH DR / 4000 multi-parameter water quality analyzer (mg-Cl2 / L). The detailed preparation method of the stabilized hypobromite composition is as follows.

[0057] To maintain an oxygen concentration of 1% in the reaction vessel, nitrogen gas was continuously injected into a 2L four-necked flask using a mass flow controller. 1436g of water and 361g of sodium hydroxide were added and mixed, followed by 300g of sulfamic acid and mixing. While maintaining a cooling temperature of 0-15°C, 473g of liquid bromine was added, followed by 230g of 48% potassium hydroxide solution. The resulting stabilized hypobromous acid composition was obtained with a weight ratio of 10.7% sulfamic acid and 16.9% bromine relative to the total volume of the composition, and an equivalent ratio of sulfamic acid to bromine of 1.04. The pH of the resulting solution was measured by the glass electrode method and found to be 14. The bromine content of the resulting solution was measured by converting bromine to iodine with potassium iodide and then performing a redox titration with sodium thiosulfate and found to be 16.9%, which was 100.0% of the theoretical content (16.9%). Furthermore, the oxygen concentration in the reaction vessel during the bromine reaction was measured using the "Oxygen Monitor JKO-02 LJDII" manufactured by Jiko Co., Ltd. The bromate concentration was less than 5 mg / kg.

[0058] The pH was measured under the following conditions. Electrode type: Glass electrode type pH meter: Toa DKK Corporation, IOL-30 model Electrode calibration was performed using two-point calibration with Kanto Chemical Co., Ltd.'s neutral phosphate pH (6.86) standard solution (Type 2) and Kanto Chemical Co., Ltd.'s borate pH (9.18) standard solution (Type 2). Measurement temperature: 25℃ Measurement value: The electrode is immersed in the measuring solution, and the value after stabilization is taken as the measurement value. The average of three measurements is then taken.

[0059] (Sodium hypobromite) Sodium hypobromite was prepared by mixing 40% by weight of 12% sodium hypochlorite, 18.4% of 40% sodium bromide (NaBr) solution, and the remainder in water.

[0060] (Sodium hypochlorite) A commercially available 12% sodium hypochlorite solution was used.

[0061] < reference Example 1> [Ion exchange resin degradation test (accelerated beaker test under high concentration conditions)] To compare the effects of various oxidizing agents on ion exchange resins, tests were conducted at higher concentrations than the usual contact concentrations in an accelerated manner.

[0062] [Test conditions] • Ion exchange resin: Anion exchange resin (Dupont "AMBERTEC 4003 Cl", matrix structure: gel type, water retention capacity: 49-55%, total exchange capacity: ≥1.25 eq / L resin) ·Resin amount: 200mL • Oxidizing agent: Sodium hypobromite as shown above ( reference Example 1) Stabilized hypobromite composition ( reference Example 2) Sodium hypochlorite (Comparative Example 1) • Oxidizing agent concentration: 1000 mg / L in terms of available chlorine • Immersion water: Pure water with various oxidizing agents added at specified concentrations. ·Immersion water amount: 800mL • Immersion time: 900 hours ·Soaking temperature: 25℃ • CT value, which is the product of the concentration of available chlorine (mgCl2 / L) and the contact time (h): 9,000,000 (mgCl2 / L·h)

[0063] Tables 1 and 2 show the neutral salt decomposition capacity and water retention capacity of the ion exchange resin before and after the test, respectively. Figure 1 also shows the change in the cumulative amount of TOC leached from the ion exchange resin during immersion.

[0064] [Table 1]

[0065] [Table 2]

[0066] The general guideline for replacing the neutral salt decomposition capacity is to keep it below 1.20 (eq / L·swelled resin). Brominated oxidizing agents had less impact on the performance of ion exchange resins compared to hypochlorous acid. Brominated oxidizing agents also have less impact on ion exchange resins because they leach less TOC from them compared to hypochlorous acid. Furthermore, TOC leaching is undesirable because it affects the water quality in subsequent stages. Among oxidizing agents, stabilized hypobromous acid compositions have the least impact on ion exchange resins.

[0067] <Example 3> [Ion exchange resin degradation test (column water flow test under normal concentration conditions)] To confirm the effect of stabilized hypobromite compositions on ion exchange resins under normal operating conditions, tests were conducted using resin columns under conditions similar to actual use. Specifically, test water containing a predetermined concentration of stabilized hypobromite composition was continuously passed through cation exchange resins and anion exchange resins for predetermined times, and the neutral salt exchange capacity and water retention capacity were measured after the test. The neutral salt decomposition capacity and water retention capacity of the ion exchange resins before and after the test are shown in Tables 3 and 4, respectively.

[0068] [Test conditions] • Cation exchange resin: Dupont "AMBERLITE HPR1024 H", matrix structure: gel, water retention capacity: 45-51%, total exchange capacity: ≥2.10 eq / L • resin • Anion exchange resin: Dupont "AMBERJET 4002(OH)-HG", matrix structure: gel, water retention capacity: 49-55%, total exchange capacity: ≥1.25 eq / L • Resin • Resin quantity: Cation exchange resin = 480 mL, Anion exchange resin = 1300 mL • Oxidizing agent: Stabilized hypobromite composition as shown above • Oxidizing agent concentration: 0.2 mg / L in terms of available chlorine • Test water: Pure water with a specified concentration of oxidizing agent added. ·Water flow rate: 30L / h • Water flow time: 2200 hours ·Soaking temperature: 25℃ • CT value, which is the product of the concentration of available chlorine (mgCl2 / L) and the contact time (h): 440 (mgCl2 / L·h)

[0069] [Table 3]

[0070] [Table 4]

[0071] Under actual usage conditions, it was confirmed that stabilized hypobromite had almost no effect on the performance of the ion exchange resin as long as the CT value was 360 (mgCl2 / L·h) or less. Furthermore, it was found that the growth of microorganisms was suppressed by using stabilized hypobromite.

[0072] As described above, by adding at least one of the following as a disinfectant to the water flowing into the ion exchanger, a bromine-based oxidizing agent, a stabilized hypochlorous acid composition containing a chlorine-based oxidizing agent and a sulfamic acid compound, and a stabilized hypobromous acid composition containing a bromine-based oxidizing agent and a sulfamic acid compound, it was possible to suppress the growth of microorganisms while suppressing the deterioration of the ion exchanger. [Explanation of Symbols]

[0073] 1 water treatment device, 10 ion exchange treatment device, 12 water treatment pipes, 14 treated water pipes, 16 disinfectant addition pipes.

Claims

1. A method for sterilizing an ion exchanger, To the water flowing into the ion exchanger, at least one of the following is added as a disinfectant: a bromine-based oxidizing agent, a stabilized hypochlorous acid composition containing a chlorine-based oxidizing agent and a sulfamic acid compound, and a stabilized hypobromous acid composition containing a bromine-based oxidizing agent and a sulfamic acid compound. A method for sterilizing an ion exchanger, characterized in that the amount of contact of the disinfectant with the ion exchanger is 440 (mgCl² / L·h) or less, as a CT value which is the product of the concentration as available chlorine (mgCl² / L) and the contact time (h).

2. A method for sterilizing an ion exchanger according to claim 1, A method for sterilizing an ion exchanger, characterized in that the disinfectant is the stabilized hypobromous acid composition.

3. A method for sterilizing an ion exchanger according to claim 1 or 2, A method for sterilizing an ion exchanger, characterized in that the ion exchanger is a gel-type ion exchange resin.

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