JP2009247992A - Pure water producing method and pure water production apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pure water producing method efficiently removing a TOC component, in particular the TOC component derived from a slime control agent to provide pure water with low TOC, in the production of pure water by membrane treatment requiring the slime control agent. <P>SOLUTION: The pure water producing method includes processes of: adding the slime control agent to raw water; membrane-treating the slime control agent-containing raw water with the slime control agent added thereto; irradiating the membrane-treated water with ultraviolet ray; and performing ion exchange to the liquid subjected to the ultraviolet ray irradiation treatment. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pure water production method and a pure water production apparatus, and more particularly to a pure water production method and a pure water production apparatus that require a slime control agent in the production of pure water for membrane treatment.

  A typical pure water production apparatus used in a semiconductor production process or the like includes a membrane apparatus having separation membranes using raw water such as industrial water, river water, and well water.

  Due to the recent increase in environmental awareness and cost awareness, there is an increasing number of cases where water used in factories is collected and treated with a separation membrane, and then reused as raw water for pure water production equipment (pure water raw water). . In this case, the recovered water (recovered raw water) often has problems such as a higher TOC than industrial water.

  For this reason, when recovered raw water is used as raw water, problems such as an increase in differential pressure due to generation of slime and scale in the separation membrane and a decrease in the amount of permeated water (treated water) are likely to occur. For this reason, it is necessary to add a film treatment agent such as a slime control agent and a scale inhibitor to the membrane device.

  As the slime control agent for separation membranes, oxidizing agents such as hypochlorite and organic agents are generally used. However, oxidizing agents have a high slime suppression effect, but cause membrane deterioration. There are drawbacks. Organic chemicals such as halocyanoacetamide compounds, nitroalcohol compounds, and isothiazolone compounds are used as slime control agents for separation membranes because they have a high slime inhibiting effect and hardly cause membrane deterioration. In particular, since a halocyanoacetamide-based slime control agent has a high slime-inhibiting effect, its use as a film disinfectant has been proposed (see, for example, Patent Document 1).

  However, among these slime control agents, particularly in the case of organic chemicals, there is a problem that part of the TOC component of the chemical itself may permeate the separation membrane and raise the TOC of the treated water. Furthermore, liquid preparations containing halocyanoacetamide compounds that have a particularly high slime-inhibiting effect often contain large amounts of organic solvents, and some of these organic solvents may also permeate the separation membrane. When an acetamide-based slime control agent is used, there is a problem that the TOC of treated water is particularly likely to rise. For this reason, in order to obtain a sufficient slime control effect, an increase in the treated water TOC cannot be avoided, and there is a problem that a sufficient slime control effect cannot be obtained if the treated water TOC is kept low.

  Patent Document 2 reports a method of adding a scale inhibitor to raw water and oxidizing a TOC component derived from the scale inhibitor in concentrated water by UV irradiation in wastewater treatment by a reverse osmosis membrane (RO membrane) separator. ing. However, the removal of the TOC component derived from the membrane treating agent in the permeated water (treated water) is not described.

  Patent Document 3 reports a method for removing nonionic organic substances in treated water, which cannot be removed by a reverse osmosis membrane device, in the production of ultrapure water using a reverse osmosis membrane device by a UV oxidation device at the latter stage of the membrane device. Yes. However, the removal of the TOC component derived from the membrane treating agent is not described.

JP 2006-89402 A JP 2007-244930 A JP-A-6-39366

  The present invention can efficiently remove the TOC component, particularly the TOC component derived from the slime control agent, in the production of pure water that performs a membrane treatment that requires a slime control agent, thereby obtaining pure water having a low TOC. A pure water production method and a pure water production apparatus.

  The present invention includes a slime control agent addition step of adding a slime control agent to raw water, a membrane treatment step of membrane-treating the slime control agent-containing raw water to which the slime control agent is added, and the membrane-treated membrane-treated water as ultraviolet rays. It is a pure water manufacturing method including an ultraviolet irradiation treatment step for performing an irradiation treatment, and an ion exchange treatment step for performing an ion exchange treatment on the ultraviolet irradiation treatment liquid subjected to the ultraviolet irradiation treatment.

  In the pure water production method, the membrane treatment is preferably a reverse osmosis membrane treatment.

Further, in the water purification process, the slime control agent has the structure (wherein, R ₁ represents. A hydroxyl group or an alkyl group having 1 to 3 carbon atoms) of the formula (1) or (2) a It is preferable to contain an alcohol-based or glycol-based organic solvent.

（１）

（２）

(1)

(2)

  In the pure water production method, the alcohol-based or glycol-based organic solvent is preferably dipropylene glycol.

  In the pure water production method, it is preferable that the slime control agent contains at least one of a halocyanoacetamide compound, a nitroalcohol compound, and an isothiazolone compound.

  In the pure water production method, the halocyanoacetamide compound is preferably 2,2-dibromo-3-nitrilopropionamide.

  The present invention also includes a slime control agent addition means for adding a slime control agent to raw water, a membrane treatment means for membrane treatment of the slime control agent-containing raw water to which the slime control agent is added, and the membrane-treated membrane treated water. Is a pure water production apparatus comprising: an ultraviolet irradiation treatment unit that performs ultraviolet irradiation treatment; and an ion exchange treatment unit that performs an ion exchange treatment on the ultraviolet irradiation treatment liquid.

  In the present invention, in the production of pure water that performs a membrane treatment that requires a slime control agent, the raw water to which the slime control agent is added is subjected to membrane treatment, and then subjected to ultraviolet irradiation treatment and ion exchange treatment, whereby the TOC component, particularly The TOC component derived from the slime control agent can be efficiently removed, and pure water having a low TOC can be obtained.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  The outline of an example of the pure water manufacturing apparatus which concerns on embodiment of this invention is shown in FIG. 1, and the structure is demonstrated. The pure water production apparatus 1 includes a membrane treatment apparatus 10 that is a membrane treatment means, an ultraviolet irradiation treatment apparatus 12 that is an ultraviolet irradiation treatment means, and an ion exchange treatment apparatus 14 that is an ion exchange treatment means.

  In the pure water production apparatus 1 of FIG. 1, the outlet of the membrane treatment apparatus 10 and the inlet of the ultraviolet irradiation treatment apparatus 12 are connected to the outlet of the ultraviolet irradiation treatment apparatus 12 and the inlet of the ion exchange treatment apparatus 14 by piping or the like. . In the present embodiment, the arrangement order may be “membrane treatment apparatus → ultraviolet irradiation treatment apparatus → ion exchange treatment apparatus”, and other apparatuses may be arranged before, after, and between them.

  The pure water manufacturing method using the pure water manufacturing apparatus 1 which concerns on embodiment of this invention is demonstrated.

  The raw water is sent from the raw water tank or the like to the membrane treatment apparatus 10 through a raw water supply pipe or the like. Before flowing into the membrane treatment apparatus 10, the slime control agent is added from the slime control agent storage tank or the like by a slime control agent addition means such as a pump in the raw water supply pipe (slime control agent addition step). The slime control agent may be added continuously or intermittently. In addition, the slime control agent may be added to the storage tank by separately providing a storage tank for storing the raw water from the raw water tank or the raw water tank.

  In the membrane treatment apparatus 10, the raw material water containing the slime control agent to which the slime control agent is added is subjected to membrane treatment to obtain permeated water that has permeated the separation membrane and concentrated water in which impurities are concentrated (membrane treatment step). ). Concentrated water is discharged out of the system.

  Next, the permeated water (membrane treated water) that has been membrane treated in the membrane treating apparatus 10 and permeated through the separation membrane is sent to the ultraviolet irradiation treatment apparatus 12 through a membrane treated water pipe or the like. Here, the membrane treatment water is irradiated with ultraviolet rays to undergo oxidation treatment, and mainly by irradiating the organic matter derived from the raw water, the slime control agent, etc. that has passed through the separation membrane, these are carbon dioxide, Decomposed into organic acids and other volatile low-molecular compounds (ultraviolet irradiation treatment process).

  Next, the ultraviolet irradiation treatment liquid subjected to the ultraviolet irradiation treatment in the ultraviolet irradiation treatment apparatus 12 is sent to the ion exchange treatment apparatus 14 through an ultraviolet irradiation treatment liquid pipe or the like. Here, the organic acid or other volatile low-molecular compound produced by the ultraviolet irradiation treatment is mainly adsorbed and removed by an ion exchange resin or the like to obtain treated water, that is, pure water (or ultrapure water). (Ion exchange treatment process).

  The TOC component in the slime control agent may partially permeate the separation membrane and contaminate the treated water, but by installing the ultraviolet irradiation treatment device 12 and the ion exchange treatment device 14 at the subsequent stage of the membrane treatment device 10. The TOC component derived from the slime control agent or the like is efficiently removed, and pure water with a reduced TOC component is obtained.

  The raw water to be treated in the present embodiment is not particularly limited, and examples include water collected after use in a factory (recovered raw water) in addition to industrial water, river water, well water, and the like.

  Examples of the membrane processing apparatus 10 include a membrane processing apparatus using a reverse osmosis membrane (RO membrane, NF membrane), etc., but from the viewpoint of the TOC removal effect, a reverse osmosis membrane device using an RO membrane is preferable. . As the RO membrane, a cellulose acetate membrane (CA membrane), a polyamide membrane (PA membrane), or the like can be used.

  The slime control agent suppresses generation of slime in the separation membrane. The slime control agent usually contains an active ingredient having an effect of suppressing the generation of slime and may contain a solvent for dissolving or dispersing the active ingredient. The slime control agent may contain an acid, an alkali, a known scale inhibitor, a chelating agent, an anticorrosive agent, and the like.

  As active ingredients contained in the slime control agent, oxidizing agents such as hypochlorite and organic agents are used. Although the oxidizing agent has a high slime inhibitory effect, it may cause film deterioration. Therefore, an organic agent that has a high slime suppressing effect and hardly causes film deterioration is preferable. Examples of organic agents include halocyanoacetamide compounds, nitroalcohol compounds, isothiazolone compounds, and quaternary ammonium salt compounds. From the viewpoints of slime suppression effects and effects on separation membranes, halocyanoacetamide compounds and nitroalcohol compounds At least one of the isothiazolone compounds is preferable, and a halocyanoacetamide compound is more preferable because it has a particularly high slime-inhibiting effect and hardly permeates a separation membrane such as an RO membrane.

The halocyanoacetamide compound is a halocyanoacetamide compound represented by the following formula (3) (wherein X is the same or different halogen atom or hydrogen atom, and R ₂ is a hydrogen atom or carbon number 1). For example, 2-bromo-3-nitrilopropionamide, 2,2-dibromo-3-nitrilopropionamide (DBNPA), 2-chloro-2-bromo-3-nitrilo. Propionamide, 2-chloro-3-nitrilopropionamide, 2,2-dichloro-3-nitrilopropionamide, N-methyl-2,2-dibromo-3-nitrilopropionamide, N-propyl-2-chloro-2 -Bromo-3-nitrilopropionamide and the like.

（３）

(3)

  Examples of the nitroalcohol compound include 2-bromo-2-nitropropane-1,3-diol, 2-bromo-2-nitrobutane-1,3-diol, and 3-bromo-3-nitropentane-2,4- Diol, 2,2-dibromo-2-nitro-1-ethanol, 2-nitro-1,3-propanediol, tris (hydroxymethyl) nitromethane, 2-bromo-2-nitro-1,3-diacetyloxypropane 3,3-dibromo-3-nitro-2-propanol, 2-chloro-2-nitroethanol, 2-chloro-2-nitro-1,3-propanediol, 3-chloro-3-nitro-2-propanol Etc.

  Examples of the isothiazolone compound include 2-methyl-4-isothiazolin-3-one, 2-ethyl-4-isothiazolin-3-one, 2-octyl-4-isothiazolin-3-one, and 5-chloro-2-methyl. -4-isothiazolin-3-one, 5-chloro-2-octyl-4-isothiazolin-3-one, 4,5-dichloro-2-methyl-4-isothiazolin-3-one, 4,5-dichloro-2 -Octyl-4-isothiazolin-3-one, 1,2-benzisothiazolin-3-one and the like.

  These compounds may be contained independently and 2 or more types may be contained. Among the above-mentioned compounds, DBNPA has a particularly high bactericidal effect and is difficult to permeate a separation membrane such as an RO membrane, and thus is suitable as a slime control agent for the separation membrane.

  Some of these active ingredients may permeate a separation membrane such as an RO membrane and raise the TOC of treated water. In addition, these active ingredients may contain a solvent in order to obtain a liquid preparation. In particular, DBNPA has a low solubility in water and is easily decomposed in water. Therefore, DBNPA liquid preparations often contain a large amount of organic solvents as stabilizers, and some of these organic solvents also separate RO membranes. The TOC of the treated water may be increased through the membrane. According to the pure water production method and the pure water production apparatus according to the present embodiment, treated water having a low TOC can be obtained even when a DBNPA liquid preparation containing a large amount of an organic solvent is used.

  Examples of the scale inhibitor include polyacrylic acid, acrylic acid / hydroxyethylidene methacrylate copolymer, acrylic acid / hydroxyethylidene methacrylate / methyl acrylate copolymer, and acrylic acid / allyl glycidyl ether copolymer. , Copolymer of acrylic acid / 2-hydroxy-3-allyloxy-1-propanesulfonic acid, copolymer of acrylic acid / isoprene sulfonic acid, copolymer of acrylic acid / vinyl sulfonic acid, acrylic acid / allyl sulfonic acid , Maleic acid or maleic anhydride / isobutylene copolymer, maleic acid or maleic anhydride / styrene sulfonic acid copolymer, maleic acid or maleic anhydride / acrylic acid copolymer, maleic acid or maleic anhydride / Acrylic acid copolymer, male Or a copolymer of maleic acid / 2-acrylamido-2-methylpropanesulfonic acid, a copolymer of maleic acid or maleic anhydride / amylene acid, polyacrylamide, and the like polyitaconic acid and their salts.

  Examples of the chelating agent include EDTA (ethylenediamine tetraacetic acid), TET (triethylenetetraamine), and EGTA (ethylene glycol bistetraacetic acid).

  Examples of the anticorrosive agent include tolyltriazole, benzotriazole, methylbenzotriazole, molybdic acid, tungstic acid, silicic acid, nitrous acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxyethylidene diphosphonic acid, hexametaphosphoric acid. , Tripolyphosphoric acid, orthophosphoric acid and salts thereof, zinc chloride, acidic hydrochloric acid chloride, zinc sulfate, zinc lignin sulfonate, hydrazine and the like.

The solvent contained in the slime control agent is not particularly limited as long as it can dissolve or disperse the active ingredient, and examples thereof include water and organic solvents, but it is difficult to permeate a separation membrane such as an RO membrane. Therefore, it may contain an alcohol-based or glycol-based organic solvent containing the structure of the above formula (1) or (2) (wherein R ₁ represents a hydroxyl group or an alkyl group having 1 to 3 carbon atoms). preferable.

  Specific examples of such alcohol solvents or glycol solvents include 2-butanol, isobutanol, tert-butanol, propylene glycol, dipropylene glycol, and tripropylene glycol. These may be used alone or in combination of two or more.

  Among the above solvents, an organic solvent having a branched structure such as the above formula (1) or (2) is difficult to permeate a separation membrane such as an RO membrane, so that the quality of treated water is hardly deteriorated. Dipropylene glycol, which is a representative example of the organic solvent having a branched structure, can be removed with high efficiency by the ultraviolet irradiation treatment device 12 and the ion exchange treatment device 14 in the subsequent stage.

  The content of an active ingredient such as a halocyanoacetamide compound is preferably 1 to 60% by weight, more preferably 10 to 40% by weight in the slime control agent. Here, when the content is less than 1% by weight, it is necessary to increase the amount of the drug added to the raw water, which may increase the transportation cost and is not economical. When the content exceeds 60% by weight, the quality of the treated water may be deteriorated, such as precipitation of a halocyanoacetamide compound.

  In addition, the content of a solvent such as an alcohol solvent or a glycol solvent is preferably 0.1 to 50 times, more preferably 0.5 to 5 times by weight with respect to the active ingredient.

  Moreover, it is preferable that the molecular weights of these solvents, such as alcohol solvent or glycol solvent, exist in the range of 70-200. If the molecular weight is less than 70, it is easy to permeate a separation membrane such as an RO membrane, which may deteriorate the quality of treated water. Moreover, when the molecular weight exceeds 200, the viscosity becomes high, and there may be a problem that the medicine does not easily flow through a device such as a pump.

  The ultraviolet irradiation processing device 12 is not particularly limited as long as it can irradiate UV including UV having a wavelength of at least 185 nm. As such an ultraviolet irradiation treatment apparatus, a low-pressure UV oxidation apparatus generally used for water treatment can be used.

The UV irradiation amount is not particularly limited as long as it is an amount sufficient to decompose at least an organic substance dissolved in water, and can be appropriately determined depending on the design conditions of the apparatus. For example, from the relationship between the irradiation cost and the removal efficiency, it is preferably in the range of 0.05 to 0.5 (kW · hr / m ³ ).

  The TOC at the entrance of the ultraviolet irradiation processing device 12 is preferably less than 100 ppb from the viewpoint of removal efficiency.

  As the ion exchange treatment device 14, an ion exchange treatment device generally used for water treatment can be used. Examples of the ion exchange resin include an anion exchange resin, a cation exchange resin, or a mixed bed thereof, and the adsorption efficiency of organic acids and other volatile low-molecular compounds generated in the ultraviolet irradiation processing apparatus 12 is high. A mixed bed of an anion exchange resin and a cation exchange resin is preferable.

  With the pure water manufacturing method and the pure water manufacturing apparatus according to the present embodiment, for example, pure water having a low TOC and ultrapure water used in a semiconductor manufacturing process, a power plant, and the like can be manufactured. The TOC of pure water and ultrapure water obtained by the pure water manufacturing method and the pure water manufacturing apparatus according to this embodiment is, for example, 1 ppb or less.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

Example 1
The pure water production apparatus 1 shown in FIG. 1 is used for the test, and points a to c (point a: after addition of the slime control agent and before flowing into the membrane treatment apparatus 10; point b: flow into the ultraviolet irradiation treatment apparatus 12; Table 1 shows the TOC measurement results before and after point c: after flowing out of the ion exchange treatment device 14.

Ultra pure water was used as raw water. A slime control agent containing DBNPA (10% by weight) as a halocyanoacetamide compound and dipropylene glycol as a solvent was used as the RO membrane treatment agent. It added so that the addition density | concentration of a slime control agent might be set to about 150 ppb as TOC at the inlet_port | entrance of the ultraviolet irradiation processing apparatus 12. FIG. The membrane processing apparatus 10 used was equipped with ES10, which is an RO membrane manufactured by Nitto Denko Corporation. As the ultraviolet irradiation treatment device 12, a UV oxidation device manufactured by Chiyoda Kogyo Co., Ltd. was used. The irradiation UV wavelength was 185 nm, and the UV irradiation amount was adjusted to be about 0.05 to 0.5 (kw · hr / m ³ ). As the ion exchange treatment device 14, a device filled with EPS-2 which is a resin (mixed bed) obtained by mixing a cation exchange resin and an anion exchange resin manufactured by Organo Corporation was used. As the TOC meter, ANATEL A-1000XP was used.

(Comparative Example 1)
A test is performed under the same conditions as in Example 1 except that a pure water production apparatus (without an ultraviolet irradiation treatment apparatus and an ion exchange treatment apparatus) including the membrane treatment apparatus 50 shown in FIG. The TOC at point a: after addition of the slime control agent and before inflow into the membrane treatment apparatus 50, point c: after outflow from the membrane treatment apparatus 50 was measured. The same film processing apparatus 50 as in Example 1 was used. The results are shown in Table 1.

  As described above, in Example 1, it was possible to suppress troubles such as slime generation by using the slime control agent while keeping the TOC of the treated water low. Moreover, even when the slime control agent was a preparation containing a large amount of solvent such as a DBNPA preparation, the TOC of the treated water could be kept low.

(Reference Examples 1-4)
In water containing bacteria, halocyanoacetamide compound DBNPA (Reference Example 1), isothiazolone compound 5-chloro-2-methyl-4-isothiazolin-3-one (CMI) (Reference Example 2), nitroalcohol compound 2,2-dibromo-2-nitroethanol (DBNE) (Reference Example 3) and ethanol (Reference Example 4) were added so as to be 3 mg / L, respectively, and before addition and 5 minutes after addition, 30 minutes The results of measuring the number of bacteria in water after 24 hours are shown in Table 2.

  Thus, DBNPA, CMI, and DBNE have a high bactericidal effect, and in particular, DBNPA, which is a halocyanoacetamide compound, has a high bactericidal effect.

(Reference Examples 5 and 6)
Using a pure water production apparatus having an ultraviolet irradiation treatment device 52 and an ion exchange treatment device 54 shown in FIG. 3, dipropylene glycol is added to ultrapure water so that the TOC becomes about 20 ppb at the entrance of the ultraviolet irradiation treatment device 52. (Reference Example 5) or methanol (Reference Example 6) was added, the TOC at the outlet of the ion exchange treatment device 54 was measured, and the TOC removal rate in the ultraviolet irradiation treatment device 52 and the ion exchange treatment device 54 was determined. The results are shown in Table 3.

<Test conditions>
Ultraviolet irradiation treatment device: manufactured by Chiyoda Kogyo Co., Ltd., UV oxidation device UV irradiation amount: 0.1 (kW · hr / m ³ )
Ion exchange treatment device: filled with ion exchange resin EPS-2 manufactured by Organo Corporation

  Thus, it can be seen that Reference Example 5 (dipropylene glycol) has a higher TOC removal rate than Reference Example 6 (methanol), and that dipropylene glycol can be removed with high efficiency by ultraviolet irradiation treatment → ion exchange treatment.

It is a schematic block diagram which shows an example of the pure water manufacturing apparatus which concerns on embodiment of this invention. It is a schematic block diagram which shows the pure water manufacturing apparatus used in the comparative example 1 of this invention. It is a schematic block diagram which shows the pure water manufacturing apparatus used in Reference Examples 5 and 6 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Pure water manufacturing apparatus, 10,50 Membrane processing apparatus, 12,52 Ultraviolet irradiation processing apparatus, 14,54 Ion exchange processing apparatus.

Claims (7)

Adding a slime control agent to the raw water,
A membrane treatment step of membrane-treating the slime control agent-containing raw water to which the slime control agent is added;
An ultraviolet irradiation treatment step of subjecting the membrane treated water to ultraviolet irradiation treatment;
An ion exchange treatment step of ion exchange treatment of the ultraviolet irradiation treatment liquid subjected to the ultraviolet irradiation treatment;
The pure water manufacturing method characterized by including. It is a pure water manufacturing method of Claim 1, Comprising:
The method for producing pure water, wherein the membrane treatment is a reverse osmosis membrane treatment. It is a pure water manufacturing method of Claim 1 or 2, Comprising:
The slime control agent contains an alcohol-based or glycol-based organic solvent containing a structure of the following formula (1) or (2) (wherein R ₁ represents a hydroxyl group or an alkyl group having 1 to 3 carbon atoms). A method for producing pure water.

(1)

(2) It is a pure water manufacturing method of Claim 3, Comprising:
The method for producing pure water, wherein the alcohol-based or glycol-based organic solvent is dipropylene glycol. It is the pure water manufacturing method of any one of Claims 1-4,
The method for producing pure water, wherein the slime control agent contains at least one of a halocyanoacetamide compound, a nitroalcohol compound, and an isothiazolone compound. It is a pure water manufacturing method of Claim 5, Comprising:
The method for producing pure water, wherein the halocyanoacetamide compound is 2,2-dibromo-3-nitrilopropionamide. A slime control agent addition means for adding a slime control agent to raw water;
Membrane treatment means for membrane-treating the slime control agent-containing raw water to which the slime control agent is added;
Ultraviolet irradiation treatment means for ultraviolet irradiation treatment of the membrane-treated water subjected to the membrane treatment;
Ion exchange treatment means for ion exchange treatment of the ultraviolet irradiation treatment liquid subjected to the ultraviolet irradiation treatment;
An apparatus for producing pure water, comprising:

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