JP2011167633A - Water treatment method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce high-purity ultrapure water by removing a TOC (total organic carbon) component including low molecular weight nitrogen compounds in a higher degree. <P>SOLUTION: When organic matter-containing raw water is passed through an organic matter removal catalyst column 4 including a metal, on which hydrogen is adsorbed in the presence of dissolved oxygen, to remove organic matter, the raw water is passed through a H<SB>2</SB>O<SB>2</SB>decomposition catalyst column 1 to remove hydrogen peroxide. The DO (dissolved oxygen) concentration of the hydrogen peroxide-removed raw water is adjusted in a gas dissolution membrane module 2. The organic matter in the raw water having the adjusted DO concentration is decomposed in a low-pressure UV oxidation unit 3. The organic matter-decomposed raw water is passed through the organic matter removal catalyst column 4 and further passed through an ion exchange resin column 5 to perform ion exchange treatment. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a water treatment method and apparatus for highly removing organic substances in water, and in particular, high-purity water substantially free of organic substances having a TOC of 1 ppb or less by easily and highly removing difficult-to-removable organic substances in water. It is related with the method and apparatus which obtains.

  For cleaning and surface treatment of electronic parts, highly concentrated chemicals and detergents and a large amount of pure water or ultrapure water for rinsing them are used. In recent years, with the advancement of electronic components, the improvement of water recovery by wastewater recovery aimed at improving the quality of ultrapure water and reducing the amount of water used has become a challenge. There is a demand for the development of a technique for reducing TOC) to a lower concentration more efficiently.

  Conventional methods for removing TOC in water include biological treatment and physicochemical treatment. When biological treatment is difficult to apply, organic matter removal using a reverse osmosis (RO) membrane or a low-pressure ultraviolet (UV) lamp can be used. The low-pressure UV oxidizer used is used.

For example, Patent Document 1 proposes a water treatment device that removes organic substances in water using a low-pressure UV oxidizer, and is provided with a means for adding oxygen gas to the water to be treated in the previous stage of the low-pressure UV oxidizer. Has been.
That is, if dissolved oxygen is present in the water to be treated with the low-pressure UV oxidizer, hydroxy radicals and hydrogen peroxide are generated by UV irradiation and the TOC decomposition efficiency is improved as described below. Then, oxygen gas is added to the water to be treated at the front stage of the low-pressure UV oxidizer.

  Usually, water is excited by UV irradiation energy, dissociates into H radicals and OH radicals as shown in the following formula, and repeats the reaction of returning to water instantly.

  A part of the dissociated OH radical reacts with the TOC component and contributes to the TOC component oxidative decomposition, but most recombines and returns to water. In order to increase the amount of TOC component decomposition, it is necessary to increase the amount of OH radicals that react with the TOC component.

  As in Patent Document 1, when oxygen gas is injected into the water to be treated before UV irradiation, the dissociated part of the H radical and the injected oxygen are combined and returned to water as shown in the following equation. Occur. At this time, a part of the OH radical generated by the dissociation of water remains, and this OH radical contributes to the oxidative decomposition of the TOC component, and is considered to increase the TOC component decomposition efficiency.

  In the low-pressure UV oxidation apparatus, hydrogen peroxide is generated by the reaction of oxygen in water and water, and at the same time, hydrogen peroxide is generated by the following reaction by excitation of water.

  However, RO membranes and low-pressure UV oxidizers that are usually used in ultrapure water production equipment, etc., are used for TOC components called difficult-to-removable organic substances typified by nitrogen compounds with low molecular weight (such as urea). There was a problem that the removal efficiency was extremely poor.

  On the other hand, since these low molecular nitrogen compounds occupy most of the TOC components present in the ultrapure water, if these can be removed, it becomes possible to remove almost all of the TOC in the ultrapure water, Higher purity ultrapure water can be obtained.

  As a method for efficiently decomposing and removing organic substances in water with low energy consumption, the present applicant has first converted water to be treated containing organic substances into a platinum group metal catalyst that has adsorbed hydrogen in the presence of dissolved oxygen. The method of decomposing and removing the organic substance in to-be-processed water by making it contact is proposed (patent document 2).

  With the method of Patent Document 2, organic substances are efficiently decomposed and removed by the catalytic action of a platinum group metal catalyst in the presence of hydrogen and oxygen. The reason is estimated as follows.

  That is, in the presence of the platinum group metal catalyst, hydrogen adsorbed on the platinum group metal catalyst and oxygen in water are combined, and electrons are unevenly distributed on the surface of the platinum group metal catalyst. As a result, it is presumed that the unshared electron pair possessed by the low-molecular nitrogen compound such as urea is bonded (adsorbed) to the rough portion of the platinum group metal catalyst surface. Then, by subsequently supplying hydrogen, when oxygen comes into contact with hydrogen and becomes water, the bond of the unshared electron pair is broken, and the organic substance is desorbed from the metal catalyst and returns to the original state. Thus, it is considered that the organic matter is decomposed and removed from the water by repeating the adsorption and desorption of the organic matter.

JP 2008-264630 A Japanese Patent Application No. 2008-193626

  According to the method of Patent Document 2, organic substances in water can be easily and highly removed, but further improvement in organic substance removal efficiency is desired.

  An object of the present invention is to provide a method and an apparatus for producing ultrapure water with high purity by further improving the method of Patent Document 2 and further removing low-molecular nitrogen compounds in water to a higher degree. .

  As a result of intensive studies to solve the above-mentioned problems, the present inventor brought water to be treated containing an organic substance into contact with an organic substance removal catalyst containing a metal adsorbed with hydrogen in the presence of dissolved oxygen. Prior to the removal of the organic matter in the treated water, it was found that the organic matter in the treated water can be removed to a higher degree by decomposing the organic matter in the treated water by low-pressure ultraviolet oxidation treatment.

  The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[1] Water containing an organic matter removing step of contacting an organic matter-containing water with an organic matter removing catalyst containing a metal adsorbed with hydrogen in the presence of dissolved oxygen to remove the organic matter in the treated water A water treatment characterized by having a low-pressure UV oxidation step for decomposing organic matter in the water to be treated by low-pressure ultraviolet oxidation, wherein the treated water of the low-pressure UV oxidation step is introduced into the organic matter removal step. Method.

[2] The method according to [1], further comprising a DO concentration adjustment step of adjusting a dissolved oxygen concentration of the water to be treated, wherein the treated water of the DO concentration adjustment step is introduced into the low-pressure UV oxidation step. Water treatment method.

[3] The water treatment method according to [2], wherein in the DO concentration adjusting step, the dissolved oxygen concentration in water is adjusted to 1 to 200 ppb.

[4] In [2] or [3], there is a H ₂ O ₂ removal step for removing hydrogen peroxide in the water to be treated, and the treated water in the H ₂ O ₂ removal step is used as the DO concentration adjustment step. A water treatment method characterized by being introduced.

[5] The water treatment method according to any one of [1] to [4], further comprising an ion exchange step of subjecting the treated water in the organic matter removal step to an ion exchange treatment.

[6] In any one of [1] to [5], the water to be treated is treated water treated by any one or more of a reverse osmosis membrane separation device, an ion exchange device, and a low-pressure ultraviolet oxidation device. A water treatment method characterized by the above.

[7] Water containing organic matter removing means for contacting organic matter-containing water with an organic matter removal catalyst containing a metal adsorbed with hydrogen in the presence of dissolved oxygen to remove the organic matter in the treated water In the treatment apparatus, the organic matter removing means has a low pressure UV oxidizing means for decomposing the organic matter in the water to be treated by low-pressure ultraviolet oxidation before the organic matter removing means, and the treated water of the low pressure UV oxidizing means is introduced into the organic matter removing means. A water treatment apparatus.

[8] In [7], a DO concentration adjusting unit that adjusts a dissolved oxygen concentration of the water to be treated is provided upstream of the low pressure UV oxidizing unit, and the treated water of the DO concentration adjusting unit is supplied to the low pressure UV oxidizing unit. A water treatment device that is introduced.

[9] The water treatment apparatus according to [8], wherein the DO concentration adjusting means adjusts the dissolved oxygen concentration in water to 1 to 200 ppb.

[10] In [8] or [9], an H ₂ O ₂ removing unit that removes hydrogen peroxide in the water to be treated is provided upstream of the DO concentration adjusting unit, and the H ₂ O ₂ removing unit A water treatment apparatus, wherein treated water is introduced into the DO concentration adjusting means.

[11] The water treatment apparatus according to any one of [7] to [10], further comprising an ion exchange means for performing an ion exchange treatment of the treated water of the organic matter removing means after the organic matter removing means.

[12] In any one of [7] to [11], the water to be treated is treated water treated by any one or more of a reverse osmosis membrane separation device, an ion exchange device, and a low-pressure ultraviolet oxidation device. Water treatment device characterized by.

  According to the present invention, by combining an organic substance removal step using an organic substance removal catalyst containing a metal adsorbed with hydrogen and an organic substance decomposition step by low-pressure ultraviolet oxidation treatment, without performing chemical treatment or heating treatment, Organic matter in the water to be treated is highly removed, and high-purity water substantially free of organic matter can be obtained.

It is a systematic diagram which shows embodiment of the water treatment method and apparatus of this invention.

Embodiments of a water treatment method and apparatus according to the present invention will be described below in detail with reference to the drawings.
In the following, the present invention will be described with reference to FIG. 1, but the present invention is not limited to the method and apparatus of FIG.

FIG. 1 is a system diagram showing an embodiment of a water treatment method and apparatus of the present invention, wherein 1 is a H ₂ O ₂ decomposition column, 2 is a gas dissolution membrane module, 3 is a low-pressure UV oxidizer, and 4 is an organic substance removal catalyst. Column 5 is an ion exchange resin column. That is, the water to be treated (hereinafter referred to as “raw water”) is added to the H ₂ O ₂ decomposition catalyst column 1, the gas dissolution membrane module 2, the low-pressure UV oxidizer 3, the organic substance removal catalyst column 4, and the ion exchange resin column 5. Sequentially passed and processed.

[Raw water]
As raw water to be treated in the present invention, raw water for producing ultrapure water, for example, city water, well water, surface water, semiconductors, electronic components, etc., in order to effectively demonstrate the features of the present invention Examples include waste water from the process. In particular, treated water treated by an impurity removing device such as a reverse osmosis membrane separation device, a low-pressure UV oxidation device, an ion exchange device, specifically a general pure water production device In addition, primary pure water and secondary pure water (ultra pure water) obtained by an ultrapure water production apparatus are preferably used.

The TOC concentration of the raw water to be treated in the present invention is preferably 1 to 1000 ppb, particularly 1 to 50 ppb, especially 1 to 30 ppb.
In the case of raw water containing hydrogen peroxide, such as ultrapure water or treated water of a low-pressure UV oxidizer, the concentration is preferably 100 ppb or less, particularly about 1 to 60 ppb.

[H ₂ O ₂ decomposition catalyst column]
In the water treatment apparatus of FIG. 1, the raw water is first introduced into the H ₂ O ₂ decomposition catalyst column 1 packed with the H ₂ O ₂ decomposition catalyst 1A to decompose and remove hydrogen peroxide contained in the water.
That is, as described above, when ultrapure water or low-pressure UV-oxidized water is used as raw water, the hydrogen load of about 1 to 60 ppb contained in the raw water is decomposed to reduce the oxygen load on the subsequent organic substance removal catalyst. To remove hydrogen peroxide. Further, in order to surely adjust the DO concentration by the gas-dissolving membrane module 2 in the subsequent stage, it is preferable to previously remove hydrogen peroxide that generates oxygen by decomposition.

The _H 2 _{O 2} decomposition catalyst 1A which is charged to the _H 2 _{O 2} decomposition catalyst column 1, there may be mentioned activated carbon, other, as catalytically active component, platinum, palladium, ruthenium, rhodium, indium, iridium, silver, Gold, cobalt, copper, nickel and tungsten, and water-insoluble or poorly water-soluble compounds of these metals, specifically, cobalt monoxide, cobalt peroxide, nickel monoxide, ruthenium dioxide, rhodium trioxide, palladium monoxide In addition, one or two or more selected from oxides such as iridium dioxide, cupric oxide, and tungsten dioxide are supported on a carrier such as alumina, activated carbon, titanium oxide, zirconia, zeolite, and other synthetic resins. It is done. The supported amount of the metal and / or the compound thereof in the supported catalyst is usually 0.05 to 25% by weight, preferably 0.5 to 10% by weight of the support weight. Such activated carbon and supported catalyst can be used in various forms such as a spherical shape, a pellet shape, a columnar shape, a fragmented shape, a honeycomb shape, and a powder shape, and the particle size is usually 0.2 to 10 mm, particularly It is preferably about 0.5 to 5 mm.

In the present invention, it is preferable to remove hydrogen peroxide in the raw water to about 5 ppb or less by passing the raw water through the H ₂ O ₂ decomposition catalyst column 1 for treatment.

In the present invention, the H ₂ O ₂ decomposition catalyst column 1 is not necessarily required, and is omitted when hydrogen peroxide is not contained in the raw water or when the H ₂ O ₂ concentration is 5 ppb or less. can do.

Further, the means for removing hydrogen peroxide in the raw water is not limited to the one using the H ₂ O ₂ decomposition catalyst, but the hydrogen peroxide in the water is changed to H ₂ O ₂ → H ₂ O + 1 / 2O ₂ . A method using an H ₂ O ₂ decomposition catalyst that undergoes catalytic decomposition by reaction is preferable in that efficient treatment can be performed without causing secondary contamination.

[Gas dissolved membrane module]
In FIG. 1, the effluent of the H ₂ O ₂ decomposition catalyst column 1 is introduced into the gas dissolution membrane module 2 to adjust the dissolved oxygen (DO) concentration.

The gas dissolution membrane module 2 is divided into a liquid phase chamber 2A and a gas phase chamber 2B by a gas permeable membrane 2M. The gas phase chamber 2B is configured to supply oxygen gas at a predetermined flow rate while evacuating the inside with a vacuum pump 2P. With such a configuration, the gas phase chamber 2B passes through the gas permeable membrane 2M from the gas phase chamber 2B. Thus, a predetermined concentration of oxygen gas can be dissolved in the liquid in the liquid phase chamber 2A. In addition, by supplying oxygen gas while evacuating the gas phase chamber 2B in this way, the concentration is lower than the concentration of dissolved oxygen generated by the decomposition of hydrogen peroxide in the preceding H ₂ O ₂ decomposition catalyst column 1. It is also possible to adjust the dissolved oxygen concentration. Although there is no restriction | limiting in particular in the vacuum pump used here, The oil-free scroll-type vacuum pump etc. which do not have a problem of secondary contamination are used suitably.

  In FIG. 1, the desired DO concentration is obtained by adjusting the oxygen gas supply amount by controlling the opening of the valve 2V of the oxygen gas supply pipe in conjunction with the DO meter 2K provided in the outlet pipe of the liquid phase chamber 2A. Get the water.

  The gas permeable membrane 2M is a membrane that transmits gas such as oxygen, nitrogen, carbon dioxide, and water vapor but does not transmit water. For example, a silicone-based film, a polytetrafluoroethylene-based film, a polyolefin-based film, a polyurethane-based film, and the like Can be mentioned.

  As the DO concentration adjusting means, a gas dissolution method using an ejector or a method of adjusting the concentration by injecting high-concentration oxygen water can be adopted. However, if the gas dissolution membrane module 2 as shown in FIG. An order of low concentration DO is preferable because the concentration can be easily and accurately adjusted.

  In the present invention, the DO concentration in the DO concentration adjusting water (the outlet water of the gas dissolving membrane module 2) is adjusted to about 1 to 200 ppb, particularly 5 to 100 ppb by adjusting the DO concentration using such a gas dissolving membrane module. It is preferable to adjust to the extent.

  That is, in the present invention, as shown in FIG. 1, the organic substance removing means is used in combination with the low pressure UV oxidizer 3 and the organic substance removal catalyst column 4, but the organic substance decomposition efficiency in the low pressure UV oxidizer is It is known that a DO oxygen concentration of about 5 to 100 ppb is higher than a lower DO concentration (for example, less than 1 ppb) (Patent Document 1 described above), and further, an organic substance removal catalyst column 4 in the latter stage. DO is also required for the organic matter treatment. Therefore, in the present invention, the DO concentration in the DO concentration adjusting water (the outlet water of the gas dissolution membrane module 2) is adjusted to about 1 to 200 ppb, particularly about 5 to 100 ppb by adjusting the DO concentration prior to low-pressure UV oxidation. It is preferable.

  If the DO concentration is too low, a sufficiently high organic substance removal efficiency cannot be obtained in the low-pressure UV oxidizer 3 and further the organic substance removal catalyst column 4. If the DO concentration is too high, the processing time and processing amount of the organic substance removal catalyst column are reduced, which is not preferable.

  In the present invention, the DO concentration adjusting means is not necessarily required, and can be omitted when the DO concentration in the raw water is stable within a desired range.

[Low pressure UV oxidizer]
In FIG. 1, the water whose DO concentration is adjusted by the gas-dissolving membrane module 2 is then introduced into the low-pressure UV oxidizer 3 to oxidize and decompose organic substances in the water.

  In the low-pressure UV oxidizer 3, organic substances other than the hardly decomposable organic substances (mainly low molecular nitrogen compounds such as urea) in water are oxidized and decomposed into carbon dioxide and organic acids, and the decomposition products are the organic substance removal catalyst column 4 in the subsequent stage. The anion exchange group of the organic matter removal catalyst 4A and the ion exchange resin of the ion exchange resin column 5 in the subsequent stage are removed.

  In the low-pressure UV oxidizer 3, as described above, hydrogen peroxide is generated. This hydrogen peroxide is catalytically decomposed by the organic substance removing catalyst in the organic substance removing catalyst column 4 in the subsequent stage to generate hydrogen peroxide. Oxygen generated by the decomposition is utilized as a dissolved oxygen source necessary for organic substance removal treatment by the organic substance removal catalyst.

In the low pressure UV oxidizer 3, water is excited by irradiation with low pressure UV, and hydrogen peroxide and hydrogen are generated by the reaction of 2H ₂ O → H ₂ O ₂ + H _2. In the latter organic substance removal catalyst column 4, the reaction returns to water again by the reaction of H ₂ O ₂ + H ₂ → 2H ₂ O. Here, the hydrogen peroxide derived from oxygen, 1 / 2O ₂ + H ₂ O → H ₂ O ₂ is decomposed to become an oxygen source. There is no distinction between the resulting hydrogen peroxide, but H ₂ O ₂ , O ₂ and H ₂ are balanced, and the oxygen at the UV inlet is used as the oxygen source in the catalyst column.

  In the low-pressure UV oxidizer, the proportion of oxygen in the water to be treated that contributes to hydrogen peroxide generation and TOC decomposition depends on the irradiation intensity of the low-pressure UV lamp. For example, in the case of the UV lamp model “AY-7” manufactured by Nippon Photo Science Co., Ltd., almost all of the DO concentration up to 10 ppb is consumed for hydrogen peroxide generation and TOC decomposition, and the difference (supply DO concentration − 10 ppb) becomes the dissolved oxygen load to the subsequent stage as it is. In this lamp, about 80% of the dissolved oxygen consumed is used for hydrogen peroxide production, and 20% contributes to the decomposition of TOC. Therefore, the supplied (dissolved oxygen-2 ppb) becomes a dissolved oxygen load to the subsequent stage. As described above, since hydrogen peroxide derived from the excitation of water generated by UV irradiation returns to water, it is not necessary to consider it as an oxygen source for the organic substance removal reaction by the organic substance removal catalyst.

  In the present invention, prior to the organic substance removal step by the organic substance removal catalyst, the organic substance decomposition treatment by such low-pressure UV oxidation is performed, and the DO efficiency is expected to be improved by increasing the DO before UV. As a result, the overall TOC removal rate can be increased. Moreover, as described above, hydrogen peroxide generated by low-pressure UV oxidation is decomposed and removed by the organic substance removal catalyst, and oxygen generated by the decomposition of hydrogen peroxide is used for organic substance removal reaction by the organic substance removal catalyst and consumed. Therefore, the DO load at the latter stage of the organic substance removing step is reduced, and a deaeration means for removing the subsequent DO becomes unnecessary.

[Organic substance removal catalyst column]
In FIG. 1, the treated water of the low-pressure UV oxidizer 3 is then introduced into an organic substance removing catalyst column 4 packed with an organic substance removing catalyst 4A, and the organic substances are removed by the organic substance removing catalyst that has adsorbed hydrogen in the presence of dissolved oxygen. Removed. The organic substance removal mechanism in the organic substance removal catalyst column 4 is as follows.

  That is, as described above, in the presence of the organic substance removal catalyst, hydrogen adsorbed on the organic substance removal catalyst and oxygen in water are combined, and electrons are unevenly distributed on the surface of the organic substance removal catalyst. As a result, it is presumed that the unshared electron pair possessed by the low molecular nitrogen compound such as urea is bonded (adsorbed) to the rough portion of the surface of the organic substance removal catalyst. Then, by subsequently supplying hydrogen, when oxygen comes into contact with hydrogen and becomes water, the bond of the unshared electron pair is broken, and the organic matter is desorbed from the organic matter removing catalyst and returns to the original state. Thus, it is considered that the organic matter is decomposed and removed from the water by repeating the adsorption and desorption of the organic matter.

  Here, the metal contained in the organic substance removal catalyst may be any metal that can sufficiently adsorb hydrogen, and platinum group metal, magnesium, or an alloy thereof (hereinafter, these catalyst metals are referred to as “platinum group metal etc.”). Among them, examples of the platinum group metal include ruthenium, rhodium, palladium, osmium, iridium and platinum. These metals can be used individually by 1 type, and can also be used in combination of 2 or more type. It can also be used as an alloy made of two or more metals. Moreover, the refined product of the mixture produced naturally can also be used without isolate | separating into a single-piece | unit. Among these, platinum, palladium, a platinum / palladium alloy alone or a mixture of two or more of them is particularly suitable because of its strong catalytic activity.

  The organic substance removal catalyst may be a fine particle such as a platinum group metal or a metal supported catalyst in which nano colloidal particles such as a platinum group metal are supported on the surface of the support. Further, the organic substance removal catalyst may be one in which a coating such as platinum group metal such as platinum is formed on a base such as a ceramic ball by plating or the like.

  There is no restriction | limiting in particular in the method of manufacturing nano colloidal particles, such as a platinum group metal, For example, a metal salt reduction reaction method, a combustion method etc. can be mentioned. Among these, the metal salt reduction reaction method can be suitably used because it is easy to produce and stable metal nanocolloid particles can be obtained. In the case of the metal salt reduction reaction method, for example, an alcohol, citric acid or a salt thereof is added to a 0.1 to 0.4 mmol / L aqueous solution such as a platinum group metal such as platinum, a nitrate, a sulfate, or a metal complex. Nano colloidal particles such as platinum group metals can be produced by adding a reducing agent such as formic acid, acetone, acetaldehyde, etc. 4 to 20 equivalents with respect to the platinum group metals and boiling for 1 to 3 hours. Further, for example, by dissolving 1-2 mmol / L of hexachloroplatinic acid, potassium hexachloroplatinate, etc. in an aqueous polyvinylpyrrolidone solution, adding a reducing agent such as ethanol, and heating and refluxing in a nitrogen atmosphere for 2 to 3 hours, Nanocolloid particles can be produced.

  The weight average particle diameter of the nano colloidal particles such as platinum group metal is preferably 1 to 50 nm, more preferably 1.2 to 20 nm, and still more preferably 1.4 to 5 nm. If the weight average particle diameter of the metal nanocolloid particles is less than 1 nm, the catalytic activity for the decomposition and removal of organic substances may be reduced. When the weight average particle diameter of the metal nanocolloid particles exceeds 50 nm, the specific surface area of the nanocolloid particles becomes small, and the catalytic activity for the decomposition and removal of organic substances may be reduced.

  There is no restriction | limiting in particular in the support | carrier which carries nano colloidal particles, such as a platinum group metal, For example, a magnesia, a titania, an alumina, a silica-alumina, a zirconia, activated carbon, a zeolite, a diatomaceous earth, an ion exchange resin etc. can be mentioned. Among these, an anion exchange resin can be particularly preferably used. Nano colloidal particles such as platinum group metals have an electric double layer and are negatively charged. Therefore, they are stably supported on an anion exchange resin and hardly peel off. This anion exchange resin is preferably a strongly basic anion exchange resin based on a styrene-divinylbenzene copolymer, and more preferably a gel resin. The exchange group of the anion exchange resin is preferably in the OH form.

  The amount of nanocolloid particles such as platinum group metal supported on a carrier such as an anion exchange resin is preferably 0.01 to 0.2% by weight, more preferably 0.04 to 0.1% by weight. preferable. If the supported amount of metal nanocolloid particles is less than 0.01% by weight, the catalytic activity for the decomposition and removal of organic substances may be insufficient. The supported amount of the metal nanocolloid particles is 0.2% by weight or less, and sufficient catalytic activity is exhibited for the decomposition and removal of the organic matter. Usually, it is not necessary to support the metal nanocolloid particles exceeding 0.2% by weight. In addition, when the amount of metal nanocolloid particles supported increases, the risk of metal elution into water also increases.

  It should be noted that by continuing the organic substance removal treatment with the organic substance removal catalyst column 4, the amount of hydrogen adsorption of the organic substance removal catalyst 4a in the organic substance removal catalyst column 4 is reduced, and the organic substance removal efficiency is reduced. A hydrogen adsorption step is performed on the removed catalyst.

Whether or not the hydrogen adsorption amount of the organic substance removal catalyst has decreased is determined, for example, by measuring the DO concentration of the inflow water and the effluent water to the organic substance removal catalyst column 4 and determining whether or not this difference in concentration is equal to or less than a predetermined value. can do. That is, if the difference between the DO concentration of the inflowing water and the DO concentration of the outflowing water of the organic matter removal catalyst column 4 is equal to or less than a predetermined value, the hydrogen adsorption amount is sufficient and the DO is removed by the reaction with hydrogen. Conversely, when it exceeds a predetermined value, it indicates that DO is not consumed in the reaction with hydrogen because the hydrogen adsorption amount is insufficient.
Therefore, for example, when the outlet DO concentration of the organic matter removal catalyst column 4 is measured by the DO meter 4K and the measured value of the DO meter 4K increases, the organic matter removal step can be switched to the hydrogen adsorption step.

  In carrying out the hydrogen adsorption process, the inflow of water from the low-pressure UV oxidizer 3 is stopped and the water in the organic matter removal catalyst column 4 is discharged, and then hydrogen gas is introduced into the organic matter removal catalyst column 4 and the column 4 Hydrogen is adsorbed on the organic matter removal catalyst 4A in the inside (pipe shown by a broken line in FIG. 1). At this time, the organic substance removal catalyst column 4 may be sealed, and the inside of the organic substance removal catalyst column 4 may be pressurized to promote hydrogen adsorption. Further, hydrogen may be circulated through the column 4.

  After sufficiently adsorbing hydrogen to the organic matter removing catalyst 4A, the water from the low-pressure UV oxidizer 3 is passed again, the column 4 is filled with this water, and the organic matter removing step is restarted.

  In this way, in addition to adsorbing hydrogen to the organic substance removal catalyst in the organic substance removal catalyst column and using it again, the organic substance removal catalyst in the organic substance removal catalyst column is exchanged with another organic substance removal catalyst that has adsorbed hydrogen. Also good. In addition, multiple organic substance removal catalyst columns are arranged side by side, the organic substance removal process is performed in some columns, the hydrogen adsorption process is performed in other columns, and the column for removing organic substances and hydrogen adsorption is switched to perform continuous processing. You can also

[Ion exchange resin column]
In the apparatus of FIG. 1, the effluent of the organic substance removal catalyst column 4 is then passed through the ion exchange resin column 5 packed with the ion exchange resin 5A, and undecomposed organic substances contained in the organic substance removal treated water Adsorbs and removes organic acids, etc. that are generated during the decomposition of organic matter.

  That is, the ion exchange resin column 5 removes carbon dioxide and organic acid generated by the low-pressure UV oxidizer 3, ion components generated from the organic substance removal catalyst column, and other organic substances. Examples of the ion exchange resin include those containing an anion exchange resin, a cation exchange resin, or both, but a non-regenerative type in which a strongly acidic cation exchange resin and a strongly basic anion exchange resin are mixed and filled in accordance with an ion load. It is preferable to use a mixed bed type ion exchanger. The mixed-bed ion exchanger removes residual organic substances and organic acids generated during the decomposition process of organic substances, and also completely removes cations and anions in water, resulting in extremely low organic substance concentration and electrical conductivity. Pure water can be obtained.

  In addition, the organic substance removal treated water from the organic substance removal catalyst column 4 may be subjected to deaeration treatment before passing through the ion exchange resin column 5. Thereby, the carbon dioxide gas generated by the decomposition of the organic matter or the like is removed, so that the carbonate ion load on the anion exchange resin is reduced.

  The effluent water from the ion exchange resin column 5 is ultrapure water from which organic substances and ionic components are highly removed, and is supplied to the place of use as treated water.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

[Example 1]
Water treatment was performed using the water treatment apparatus shown in FIG.
The specifications of each part of this water treatment device are as follows.

H ₂ O ₂ decomposition catalyst column 1: Pt-supported resin for nanosaber manufactured by Kurita Kogyo Co., Ltd.
Gas dissolution membrane module 2 filled with 100 mL: Degassing membrane module “Lixel G420” manufactured by Celgard
Low pressure UV oxidizer 3: “AY-7” manufactured by Nippon Photo Science Co., Ltd.
Organic substance removal catalyst column 4: Pt-supported resin for nanosaber manufactured by Kurita Kogyo Co., Ltd.
500 mL packed ion exchange resin column 5: anion exchange resin “KR-UA1” manufactured by Kurita Kogyo Co., Ltd.
310 mL and the same cation exchange resin “KR-UC1”
Filled with 190mL

As raw water, synthetic water obtained by adding urea 3 ppb (carbon equivalent concentration) and isopropanol 5 ppb (carbon equivalent concentration) as TOC sources to ultrapure water was used. This raw water contained 15 ppb of hydrogen peroxide. The amount of raw water treated water was 0.5 L / min, and the following water quality meters were used. In addition, hydrogen was adsorbed in advance for the organic substance removal catalyst. In the gas dissolving membrane module 2, the DO concentration was adjusted so that the DO concentration in the module outlet water was 30 ppb.
TOC meter: "Seabas 500RLe" manufactured by Seabass
DO meter: “Orvis 3610” manufactured by Hack Ultra Analytics Japan

The raw water contains 15 ppb of hydrogen peroxide, and as it is, it is decomposed by the reaction of 2H ₂ O ₂ → 2H ₂ O + O _{2 in} the organic substance removal catalyst column 4, and this hydrogen peroxide has a dissolved oxygen load of 7 ppb. However, since the H ₂ O ₂ decomposition catalyst column 1 and the gas dissolution membrane module 2 while degassing were provided in the previous stage, the DO concentration could be adjusted according to the set value. The H ₂ O ₂ concentration in the outlet water of the H ₂ O ₂ decomposition catalyst column 1 was 1 ppb or less.

As a result, the TOC concentration of the treated water (the outlet water of the ion exchange resin column 5) was 1 ppb or less, and the TOC concentration in the raw water was highly removed.
Further, the DO concentration of the outlet water of the organic matter removal catalyst column 4 was 1 ppb or less, the H ₂ O ₂ concentration was 1 ppb or less, deoxygenation was performed by the organic matter removal catalyst, and hydrogen peroxide was also decomposed and removed.

[Comparative Example 1]
In Example 1, the low-pressure UV oxidizer and the 3 organic substance removal catalyst column 4 are replaced, and the order of H ₂ O ₂ decomposition catalyst column → gas dissolution membrane module → organic substance removal catalyst column → low pressure UV oxidizer → ion exchange resin column is as follows: Similarly, the raw water was treated.
As a result, the TOC concentration of the treated water (the outlet water of the ion exchange resin column) was 1.2 ppb, the H ₂ O ₂ concentration was 5 ppb, and the DO concentration was ₂ ppb.
In this example, since the water deoxygenated by the organic substance removal catalyst was supplied to the low-pressure UV oxidizer, it is considered that the organic substance removal effect was lowered due to the reduced organic substance oxidative decomposition efficiency in the low-pressure UV oxidizer. Further, since there was no unit operation for highly decomposing hydrogen peroxide in the subsequent stage of the low pressure UV oxidizer, hydrogen peroxide remained. In addition, it is considered that DO increased due to hydrogen peroxide slightly decomposed by the ion exchange resin.

[Reference Example 1]
In Example 1, the H ₂ O ₂ decomposition catalyst column 1 is omitted, the gas dissolution membrane module 2 and the low pressure UV oxidizer 3 are replaced, and the low pressure UV oxidizer → the gas dissolution membrane module → the organic substance removal catalyst column → the ion exchange resin column. The raw water was treated in the same way.
As a result, the TOC concentration of the treated water (the outlet water of the ion exchange resin column) was 1.2 ppb, the H ₂ O ₂ concentration was 1 ppb or less, and the DO concentration was 1 ppb or less.
In this example, since the DO concentration of the water flowing into the low-pressure UV oxidizer is low, it can be considered that the organic substance removal effect is lowered due to the decrease in the isopropanol resolution in the low-pressure UV oxidizer.

  According to the present invention, a TOC component containing a low molecular nitrogen compound can be easily and highly removed, and dissolved oxygen and hydrogen peroxide can also be highly removed. For this reason, the present invention can be suitably applied to an ultrapure water production system or the like, and the TOC component, dissolved oxygen, and hydrogen peroxide in ultrapure water can be easily and highly reduced in concentration.

1 H ₂ O ₂ decomposition catalyst column 2 Gas dissolution membrane module 3 Low pressure UV oxidizer 4 Organic substance removal catalyst column 5 Ion exchange resin column

Claims (12)

In a water treatment method including an organic matter removing step of removing an organic matter in water to be treated by bringing the treated water containing the organic matter into contact with an organic matter removing catalyst containing a metal adsorbed with hydrogen in the presence of dissolved oxygen. ,
A water treatment method comprising a low-pressure UV oxidation step of decomposing organic matter in the water to be treated by low-pressure ultraviolet oxidation, wherein treated water in the low-pressure UV oxidation step is introduced into the organic matter removal step.   2. The water treatment method according to claim 1, further comprising a DO concentration adjustment step of adjusting a dissolved oxygen concentration of the water to be treated, wherein the treated water of the DO concentration adjustment step is introduced into the low-pressure UV oxidation step. .   3. The water treatment method according to claim 2, wherein in the DO concentration adjustment step, the dissolved oxygen concentration in water is adjusted to 1 to 200 ppb. According to claim 2 or 3, having a H ₂ O ₂ removal step of removing hydrogen peroxide of the water to be treated, that the treated water of the H ₂ O ₂ removal step is introduced into the DO concentration adjusting process A water treatment method characterized.   5. The water treatment method according to claim 1, further comprising an ion exchange step in which the treated water in the organic substance removal step is subjected to an ion exchange treatment.   In any 1 item | term of the Claims 1 thru | or 5, The said to-be-processed water is a treated water processed with any one or more of a reverse osmosis membrane separator, an ion exchange apparatus, and a low voltage | pressure ultraviolet oxidation apparatus, It is characterized by the above-mentioned. Water treatment method. In a water treatment apparatus comprising an organic matter removing means for bringing water to be treated containing organic matter into contact with an organic matter removing catalyst containing a metal adsorbed with hydrogen in the presence of dissolved oxygen to remove the organic matter in the treated water. ,
It has a low-pressure UV oxidation means for decomposing the organic matter in the water to be treated by low-pressure ultraviolet oxidation before the organic matter removal means, and the treated water of the low-pressure UV oxidation means is introduced into the organic matter removal means. Water treatment equipment.   8. The DO concentration adjusting means for adjusting the dissolved oxygen concentration of the water to be treated is provided upstream of the low pressure UV oxidizing means, and the treated water of the DO concentration adjusting means is introduced into the low pressure UV oxidizing means. The water treatment apparatus characterized by the above-mentioned.   9. The water treatment apparatus according to claim 8, wherein the DO concentration adjusting means adjusts the dissolved oxygen concentration in water to 1 to 200 ppb. According to claim 8 or 9, wherein upstream of the DO concentration adjusting means includes a H ₂ O ₂ removing means for removing the hydrogen peroxide of the water to be treated, the H ₂ O ₂ treated water the DO removal means A water treatment apparatus which is introduced into a concentration adjusting means.   11. The water treatment apparatus according to claim 7, further comprising an ion exchange unit that ion-exchanges treated water of the organic substance removing unit after the organic substance removing unit.   In any 1 item | term of the Claims 7 thru | or 11, The said to-be-processed water is a treated water processed with any one or more of a reverse osmosis membrane separator, an ion exchange apparatus, and a low voltage | pressure ultraviolet oxidation apparatus, It is characterized by the above-mentioned. Water treatment equipment.

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