Boron removal device and method, pure water production device and pure water production method

Abstract

The present invention provides a boron removal device and a boron removal method for reducing the boron concentration in treated water, and a device and a method for producing pure water with reduced boron concentration. The present invention uses a boron removal device and a boron removal method using the device, and the boron removal device has: a first electric regeneration deionization device, which is supplied with treated water; an ultraviolet oxidation device, which is supplied with water treated by the first electric regeneration deionization device; an oxide removal device, which is supplied with water treated by the ultraviolet oxidation device; and a second electric regeneration deionization device, which is supplied with water treated by the oxide removal device. The oxide removal device preferably has a platinum group metal catalyst, and the hydrogen peroxide concentration of the water treated by the oxide removal device is less than 1 ppb.

Description

Technical Field

[0001] The present invention relates to a boron removal device and a boron removal method, a pure water production device and a pure water production method. Background Art

[0002] Traditionally, pure water such as ultrapure water from which organic matter, ion components, microparticles, bacteria, etc. have been highly removed has been used as cleaning water in the manufacturing process of semiconductor devices and liquid crystal devices. In particular, when manufacturing electronic components including semiconductor devices, a large amount of pure water is used in the cleaning process, and the requirements for water quality are increasing year by year.

[0003] For example, as trace impurities, the reduction of total organic carbon (TOC) and boron is required. Generally, it is known that TOC components are removed by ultraviolet oxidation treatment, and boron is removed by reverse osmosis membrane devices, boron selective ion exchange resins, and electric regeneration deionization devices. Patent document 1 records the following: the pre-treated water is treated in the order of reverse osmosis membrane devices, electric regeneration deionization devices, ultraviolet oxidation devices, and boron resin mixed ion exchange devices to produce primary pure water with TOC and boron removed. In addition, patent document 2 records the following: the primary pure water system is equipped with a high-pressure reverse osmosis membrane separation device, a degassing device, an ultraviolet oxidation device, and an ion exchange device in sequence; the high-pressure reverse osmosis membrane has a higher removal rate of weak electrolyte components and non-charged components such as boron, silica, and non-charged organic matter than the low-pressure or ultra-low-pressure reverse osmosis membrane; the ion exchange device can also be a regeneration ion exchange device formed by connecting the electric regeneration deionization device in series with one or more stages.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-47496

[0007] Patent Document 2: Japanese Patent Application Publication No. 2017-127875 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, in the methods described in Patent Documents 1 and 2, the ozone, hydrogen peroxide and other oxidants generated in the ultraviolet oxidation device may oxidize and deteriorate the boron resin in the subsequent stage and the ion exchange resin in the electric regeneration deionization device. As a result, there is also a problem that the boron removal rate of the boron resin mixed ion exchange device and the electric regeneration deionization device is reduced, and the boron concentration cannot be reduced to an extremely low level.

[0010] Therefore, an object of the present invention is to provide a boron removal device and a boron removal method for reducing the boron concentration in water to be treated, and to provide a device and a method for producing pure water with a reduced boron concentration.

[0011] Technical solutions to solve problems

[0012] The present inventors have found that the boron concentration can be significantly reduced by appropriately combining a plurality of electrical regeneration deionization devices, ultraviolet oxidation devices, and oxide removal devices.

[0013] That is, the present invention relates to a boron removal device and a boron removal method using the device, wherein the boron removal device comprises: a first electric regeneration deionization device, which is supplied with water to be treated; an ultraviolet oxidation device, which is supplied with water treated by the first electric regeneration deionization device; an oxide removal device, which is supplied with water treated by the ultraviolet oxidation device; and a second electric regeneration deionization device, which is supplied with water treated by the oxide removal device.

[0014] In addition, the present invention relates to a pure water manufacturing device and a pure water manufacturing method using the device, wherein the pure water manufacturing device comprises: a low-pressure reverse osmosis membrane device, which is supplied with treated water; a pH adjustment device, which adjusts the pH of the permeated water from the low-pressure reverse osmosis membrane device; a high-pressure reverse osmosis membrane device, which is supplied with adjusted water after the pH is adjusted by the pH adjustment device; a first electric regeneration deionization device, which is supplied with the permeated water from the high-pressure reverse osmosis membrane device; an ultraviolet oxidation device, which is supplied with water treated by the first electric regeneration deionization device; an oxide removal device, which is supplied with water treated by the ultraviolet oxidation device; a second electric regeneration deionization device, which is supplied with water treated by the oxide removal device; and a cartridge polisher, which is supplied with water treated by the second electric regeneration deionization device.

[0015] Effects of the Invention

[0016] According to the present invention, a boron removal device and a boron removal method capable of significantly reducing the boron concentration are provided. In addition, a pure water production device and a pure water production method capable of producing high-purity pure water are provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a conceptual diagram showing the structure of a boron removal device according to one embodiment of the present invention.

[0018] Figure 2 This is a conceptual diagram showing the structure of a pure water production apparatus according to one embodiment of the present invention.

[0019] Figure 3 This is a conceptual diagram of the device used in Comparative Example 1.

[0020] Figure 4 This is a graph showing the relationship between the water passing time in Comparative Example 1 and the hydrogen peroxide concentration at the catalyst tower outlet.

[0021] Figure 5 This is a graph showing the relationship between the water flow time in Comparative Example 1 and the pressure difference in the deionization chamber of the first electrical regeneration deionization device (EDI-1). DETAILED DESCRIPTION

[0022] Hereinafter, the present invention will be described with reference to the drawings, but the present invention is not limited to the structures described in the drawings.

[0023] exist Figure 1 In the embodiment, the boron removal device 100 involved in the present invention comprises: a first electric regeneration deionization device (EDI-1) 30, which is supplied with the treated water 10 via a pump 45; an ultraviolet oxidation device 40, which is supplied with the water treated by the electric regeneration deionization device 30; an oxide removal device (catalyst tower) 50, which is supplied with the water treated by the ultraviolet oxidation device 40; and a second electric regeneration deionization device (EDI-2) 60, which is supplied with the water treated by the oxide removal device (catalyst tower) 50.

[0024] Furthermore, the treated water 10 is passed through the first electric regeneration deionization device 30 to remove the ion components and boron in the treated water, and then the treated water is supplied to the ultraviolet oxidation device 40, and the organic matter (TOC components, etc.) is decomposed. In the ultraviolet oxidation device 40, the organic matter is decomposed to produce oxidizing substances such as hydrogen peroxide and ozone. The oxidizing substances cause the degradation of the ion exchange resin in the second electric regeneration deionization device 60 described later. Therefore, the water treated by the ultraviolet oxidation device 40 is supplied to the second electric regeneration deionization device 60 and treated after the oxidizing substances are removed by the oxide removal device (catalyst tower) 50, thereby obtaining treated water 20.

[0025] The ultraviolet oxidation device 40 used in the present invention is provided for the purpose of removing organic matter. Therefore, it is preferred to use an ultraviolet oxidation device that irradiates ultraviolet rays with a wavelength of less than 185nm and performs ultraviolet oxidation treatment. In addition, there is also a case where an ultraviolet oxidation device is provided in a subsystem (secondary pure water system), but in a device such as one that requires a TOC concentration of less than 1μg / L as ultrapure water, by providing an ultraviolet oxidation device in a primary pure water system with a higher dissolved oxygen (DO) concentration, the overall energy cost can be suppressed. In addition, due to the presence of dissolved oxygen, it can be expected that hydroxyl radicals and hydrogen peroxide will be generated from the dissolved oxygen by ultraviolet irradiation, thereby improving the TOC decomposition efficiency.

[0026] When the ultraviolet oxidizing device 40 is arranged in the front stage of the first electric regeneration deionizing device 30, the oxidizing substance generated by the polymerization of free radicals generated in the ultraviolet oxidizing device, namely hydrogen peroxide, may deteriorate the ion exchange resin in the first electric regeneration deionizing device, causing performance degradation. Therefore, the ultraviolet oxidizing device 40 is arranged in the rear stage of the first electric regeneration deionizing device 30. In addition, by arranging the ultraviolet oxidizing device 40 in the front stage of the second electric regeneration deionizing device (EDI-2) 50, the load of the monolithic water purifier (CP) in the subsystem can be reduced, and high-purity pure water can be obtained.

[0027] The oxide removal device (catalyst tower) 50 is filled with a catalyst having a resolution of oxidizing substances. Thus, the oxidizing substances generated in the ultraviolet oxidation device are decomposed by the catalyst to prevent the degradation of the ion exchange resin in the second electric regeneration deionization device described later. The hydrogen peroxide concentration of the treated water obtained from the oxide removal device is preferably less than 1 ppb. As a catalyst, a platinum group metal catalyst with less elution is preferred. The platinum group metals mentioned here are ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt), and one of them can be used alone or in combination of two or more. Among these platinum group metals, Pt, Pd, etc. can be preferably used, and Pd is preferred from the perspective of cost, etc. In addition, as the carrier used, an anion exchanger is preferred. The anion exchanger can be a granular anion exchange resin, or it can be an integral organic porous anion exchanger integrally formed with an anion exchange resin. For example, monolithic organic porous anion exchangers that can be used here are described in Japanese Patent Publication No. 2002-306976 and Japanese Patent Publication No. 2009-62512. By carrying a platinum group metal catalyst in the anion exchanger, it is effective to exert high catalytic ability and reduce the elution from the catalyst. The ion form of the strongly basic anion exchange resin is preferably OH form, and as a catalyst, a catalyst having palladium (Pd) carried in the OH form of the strongly basic anion exchange resin is more preferably used.

[0028] The second electric regeneration deionizer 60 removes the organic matter and ion components that are not completely treated in the ultraviolet oxidizing device 40. As the second electric regeneration deionizer 60, the same device as the first electric regeneration deionizer 30 may be used, or a different device may be used.

[0029] Next, the pure water production device involved in the present invention is described. Figure 2In the invention, the pure water production device 200 comprises: a low-pressure reverse osmosis membrane device 70, which is supplied with treated water 10; a pH adjustment device 75, which is supplied with permeate water from the low-pressure reverse osmosis membrane device 70; a high-pressure reverse osmosis membrane device 80, which is supplied with adjusted water having pH adjusted by the pH adjustment device 75 via a pump 45; a first electric regeneration deionization device (EDI-1) 30, which is supplied with permeate water from the high-pressure reverse osmosis membrane device 80; an ultraviolet oxidation device 40, which performs ultraviolet oxidation treatment on the water treated by the first electric regeneration deionization device 30; an oxide removal device (catalyst tower) 50, which treats the water treated by the ultraviolet oxidation device 40; a second electric regeneration deionization device (EDI-2) 60, which is supplied with water treated by the catalyst tower 50; and a monolithic water purifier (CP) 90, which is supplied with water treated by the second electric regeneration deionization device 60.

[0030] Moreover, the treated water 10 is passed through the low-pressure reverse osmosis membrane device 70 to remove ion components and suspended substances such as organic matter in the treated water. Then, the permeated water is preferably adjusted to pH = 5.0 to 9.0, and more preferably adjusted to pH = 5.5 to 8.5 through the pH adjustment device 75. Thereafter, the adjusted water having the adjusted pH is treated by using the high-pressure reverse osmosis membrane device 80 and the first electric regeneration deionization device (EDI-1) 30 to effectively remove boron. The total organic carbon (TOC) component remaining in the treated water is decomposed into organic acid and carbon dioxide by the ultraviolet (UV) oxidation device 40. On the other hand, the ultraviolet oxidation device 40 decomposes the total organic carbon (TOC) component to produce oxidizing substances such as hydrogen peroxide and ozone. Therefore, in the catalyst tower 50 provided at the rear stage of the ultraviolet oxidation device 40, after removing these oxidizing substances, ion exchange treatment is performed by the second electric regeneration deionization device 60, and finally pure water 95 is produced. In semiconductor manufacturing and the like, pure water 95 is supplied to a subsystem as primary pure water to produce ultrapure water.

[0031] Next, the reverse osmosis membrane device used in the present invention is described. The reverse osmosis membrane device is composed of a reverse osmosis membrane, a reverse osmosis membrane element composed of components such as a flow path material, and one or more pressure vessels (cargo buckets) loaded with one or more reverse osmosis membrane elements. By pressurizing the treated water to the cargo bucket filled with the reverse osmosis membrane element, an amount of permeate water commensurate with the effective pressure is obtained from the cargo bucket. In addition, the water that does not pass through the reverse osmosis membrane element and is concentrated in the cargo bucket is discharged from the cargo bucket as concentrated water. There is no particular restriction on the shape of the reverse osmosis membrane element, and a tubular type, a spiral type, and a hollow fiber type can be used. When multiple reverse osmosis membrane elements are used in the same cargo bucket, each reverse osmosis membrane element is connected in series. When multiple cargo buckets are used in the reverse osmosis membrane device, the cargo buckets can be arranged in parallel or in series. For example, the pressurized treated water can be supplied to multiple cargo buckets arranged in parallel, and the permeate water and concentrated water of each cargo bucket can be merged and discharged from the device. Furthermore, it can be a cargo bucket structure such as the so-called Christmas tree method in which the concentrated water discharged from each cargo bucket is supplied to other cargo buckets.

[0032] The structure of the reverse osmosis membrane element and the structure of the cargo box in these reverse osmosis membrane devices can be designed and selected appropriately according to the required permeate water quality, permeate water volume, water recovery rate, occupied space, etc.

[0033] The water recovery rate of each reverse osmosis membrane device used in the present invention is calculated by the ratio of the treated water supplied to each reverse osmosis membrane device and the permeate water obtained by each reverse osmosis membrane device. That is, the water recovery rate of each reverse osmosis membrane device = (the amount of permeate water obtained by each reverse osmosis membrane device) / (the amount of treated water supplied to each reverse osmosis membrane device). The water recovery rate can be designed and selected according to the water quality of the treated water, the required permeate water quality, the permeate water amount, the recovery rate, the occupied space, etc. There is no particular restriction on the water recovery rate. The water recovery rate of the low-pressure reverse osmosis membrane device is preferably 50-90%, more preferably 65-85%, and the water recovery rate of the high-pressure reverse osmosis membrane device is preferably 80-99%, more preferably 85-95%. In particular, with respect to the water recovery rate of the high-pressure reverse osmosis membrane device, since the impurity concentration in the treated water is reduced by the low-pressure reverse osmosis membrane treatment, a higher value can be set.

[0034] In addition, in the reverse osmosis membrane device, chemicals (for example, a reducing agent, a pH adjuster, a scale dispersant, a bactericide, etc.) used in a general reverse osmosis membrane device can be used.

[0035] As the reverse osmosis membrane used in the low-pressure reverse osmosis membrane device (BWRO device) used in the present invention, it is preferable to use a low-pressure membrane or an ultra-low-pressure membrane that can be operated at a relatively low pressure.

[0036] As the low-pressure reverse osmosis membrane and ultra-low-pressure reverse osmosis membrane, a reverse osmosis membrane having a permeation flux of pure water of preferably 0.65 to 1.8 m / d, more preferably 0.65 to 1.0 m / d at an effective pressure of 1 MPa and a water temperature of 25°C can be used.

[0037] Here, the permeation flux is obtained by dividing the amount of permeated water by the area of ​​the reverse osmosis membrane. "Effective pressure" refers to the effective pressure (effective pressure) acting on the membrane obtained by subtracting the permeation pressure difference and the secondary side pressure from the average operating pressure as described in JIS K3802: 2015 "Membrane Terminology". In addition, the average operating pressure is the average of the pressure of the membrane supply water (operating pressure) on the primary side of the reverse osmosis membrane and the pressure of the concentrated water (concentrated water outlet pressure), and is expressed by the following formula.

[0038] Average operating pressure = (operating pressure + concentrated water outlet pressure) / 2

[0039] The permeation flux per effective pressure of 1 MPa can be calculated based on information recorded in the catalog of the membrane manufacturer, such as the permeate volume, membrane area, water recovery rate during evaluation, NaCl concentration, etc. In addition, when multiple reverse osmosis membranes with the same permeate flux are loaded in one or more pressure vessels, the permeate flux of the loaded membranes can be calculated based on information such as the average operating pressure / secondary side pressure of the pressure vessel, the quality of the water to be treated, the permeate volume, the number of membranes, etc.

[0040] As low-pressure and ultra-low-pressure reverse osmosis membranes, for example, there can be mentioned the ES series (ES15-D8, ES20-U8) (trade names) manufactured by NITTO, the ESPA series (ESPAB, ESPA2, ESPA2-LD-MAX) (trade names) manufactured by HYDRANAUTICS, the CPA series (CPA5-MAX, CPA7-LD) (trade names), the TMG series (TMG20-400, TMG20D-440) (trade names) manufactured by Toray Industries, Inc., the TM700 series (TM720-440, TM720D-440) (trade names), the BW series (BW30HR, BW30XFR-400 / 34i) manufactured by Dow Chemical, the SG series (SG30LE-440, SG30-400) (trade names), and FORTILIFECR100 (trade name).

[0041] As the definition of "high pressure" in the high pressure reverse osmosis membrane device (SWRO device) used in the present invention, the following properties can be roughly listed. That is, the definition that the permeation flux of pure water under the conditions of effective pressure 1MPa and water temperature 25°C is 0.2-0.65m / d. The effective pressure of the high pressure reverse osmosis membrane is preferably 1.5-2.0MPa. By setting the effective pressure to above 1.5MPa, the boron rejection rate of the high pressure reverse osmosis membrane can be fully improved. In addition, by setting the effective pressure to above 2.0MPa, it is possible to foresee a further improvement in the boron rejection rate, but since it is necessary to increase the durable pressure of the device, there is a situation where the equipment cost increases.

[0042] Examples of the high-pressure reverse osmosis membrane include SWC series (SWC4, SWC5, SWC6) (trade names) manufactured by HYDRANAUTICS, TM800 series (TM820V, TM820M) (trade names) manufactured by Toray Industries, and SW series (SW30HRLE, SW30ULE) (trade names) manufactured by Dow Chemical.

[0043] In this way, by providing the low-pressure type reverse osmosis membrane device 70 and the high-pressure type reverse osmosis membrane device 80 in the upstream stage of the first electric regeneration type deionization device 30, the boron concentration of the treated water can be further reduced.

[0044] Next, the electric regeneration deionization device (EDI) used in the present invention is described. EDI is a device having a desalination chamber divided by an ion exchange membrane and filled with an ion exchanger, a concentration chamber for concentrating the ions desalted by the desalination chamber, an anode for passing an electric current, and a cathode. Moreover, it is a device that is operated by passing an electric current, thereby simultaneously performing a deionization (desalination) treatment of the treated water based on the ion exchanger and a regeneration treatment of the ion exchanger. The treated water that has passed through the EDI is desalinated by the ion exchanger filled in the desalination chamber and discharged to the outside of the EDI as EDI treated water. Similarly, the concentrated water in which the ions are concentrated is discharged to the outside as EDI concentrated water.

[0045] The water recovery rate of EDI is calculated by the amount of water to be treated supplied to EDI and the amount of treated water obtained. That is, the water recovery rate of EDI = (EDI treated water amount) / (EDI treated water amount). The water recovery rate of EDI is not particularly limited, but is preferably 90 to 95%.

[0046] The water recovery rate of the RO-EDI (reverse osmosis membrane device-electric regeneration deionization device) system is calculated by the ratio of the amount of treated water supplied to the RO and the amount of treated water obtained by the EDI. That is, the water recovery rate of the RO-EDI system = EDI treated water volume / RO treated water volume. The water recovery rate of the present RO-EDI system is not particularly limited, and is preferably 80 to 99%, and more preferably 85 to 95%. In the present RO-EDI system, since the concentrated water of the high-pressure reverse osmosis membrane device and the EDI concentrated water are recovered and no concentration of components occurs in the system, a high system water recovery rate can be achieved.

[0047] The monolithic water purifier (CP) 90 is a non-regenerative ion exchange device filled with an ion exchanger, which removes organic acids and carbon dioxide generated in the ultraviolet oxidation device. In addition, there are also cases where a monolithic water purifier is provided in the subsystem, but by providing the CP in the present invention, it is possible to prevent organic acids and carbon dioxide from flowing into the ultraviolet oxidation device of the subsystem. Therefore, the TOC concentration that should be decomposed in the ultraviolet oxidation device of the subsystem can be reduced, and the energy cost can be suppressed. In addition, since the ion load on the CP can also be reduced, the exchange frequency of the CP can be reduced.

[0048] In addition, a degassing membrane device (not shown) may be provided between the high-pressure reverse osmosis membrane device 80 and the first electric regeneration deionization device 30. By providing the degassing membrane device, the carbonic acid load on the electric regeneration deionization device (EDI) can be reduced, so it is expected that the coexisting ions can be removed to improve the boron removal rate. In addition, the carbonic acid load on the oxide removal device can be reduced, and the ion form of the strong basic anion exchange resin used in the oxide removal device can be maintained in the OH form, so the removal capacity of oxidizing substances can be maintained for a long time.

[0049] Furthermore, when DO is present in excess, DO becomes a radical scavenger for the ultraviolet oxidizing device, and the TOC decomposition efficiency decreases. Therefore, a DO adjustment mechanism may be provided to control the vacuum degree on the gas side of the degassing membrane device and the purge gas flow rate.

[0050] The treated water used in the present invention is not particularly limited, and examples thereof include industrial water, groundwater, surface water, tap water, seawater, desalinated seawater treated water obtained by desalting seawater by reverse osmosis or evaporation, sewage, sewage treatment water, various drainages, such as drainage used in semiconductor manufacturing processes, and mixed water thereof. In addition, as a component of the treated water, it is preferred to satisfy any one or more of the following conditions: conductivity 10 to 1000 μS / cm, TDS (total soluble substances) = 5 to 500 ppm, and boron concentration 10 ppb to 10 ppm. In the case where the treated water component does not satisfy these conditions, it is preferred to perform pre-treatments such as coagulation and precipitation treatment, filtration treatment, softening treatment, decarbonation treatment, and activated carbon treatment.

[0051] The water quality of the treated water (permeated water) of the high-pressure reverse osmosis membrane device obtained in the present invention preferably satisfies the conductivity of less than 2μS / cm, the sodium concentration of less than 200ppb, or both. If the sodium concentration of the SWRO permeated water (EDI supply water) is high, the paired anions also leak from the SWRO together with the sodium. Therefore, the selectivity of boron in the ion exchange resin filled in the EDI decreases, and the boron of the EDI treated water cannot be fully reduced. In addition, the water quality of the pure water obtained in the present invention is not particularly limited, and water qualities with a resistivity of more than 17MΩ·cm, a boron concentration of less than 50ppt, a silica concentration of less than 50ppt, and a TOC concentration of less than 5ppb can be cited.

[0052] Example

[0053] Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to the examples.

[0054] (Example 1)

[0055] For 100L / h of treated water with an inorganic carbon (IC: Inorganic carbon) concentration of 300ppb, an ionic silica concentration of 23ppb, a boron concentration of 14ppb, a TOC concentration of 13ppb, and a hydrogen peroxide concentration of <1ppb, use Figure 1The device shown was subjected to a water flow test for about 2000 hours. The first electric regeneration deionizer (EDI-1) and the second electric regeneration deionizer (EDI-2) both used EDI-XP (trade name, manufactured by Ogano Corporation), and the water recovery rate was set to 90%. The operating current value was set to 5A. The ultraviolet (UV) oxidation device used JPW (manufactured by Japan PHOTO SCIENCE Co., Ltd.). The oxide removal device (catalyst tower) used a device in which 200mL (layer height of about 400mm) of catalyst resin was filled in a cylindrical container (inner diameter 25mm, height 600mm). The catalyst resin used a resin with a Pd loading of 100mg-Pd / LR (gel type, OH form: >99%). Table 1 shows the water quality of each outlet of EDI-1, UV oxidation device, catalyst tower, and EDI-2.

[0056] Here, if we focus on the hydrogen peroxide concentration, it is <1ppb in the treated water and at the outlet of EDI-1, but it rises to 25ppb at the outlet of the UV oxidation device. This is believed to be due to the polymerization of OH radicals generated by the UV oxidation device and the decomposition of 9ppb of TOC at the outlet of EDI-1. The hydrogen peroxide is decomposed in the catalyst tower and becomes less than 1ppb at the outlet of the catalyst tower. As a result, almost no hydrogen peroxide flows into EDI-2, and it is not affected by hydrogen peroxide, showing that boron and TOC have been removed. This is also confirmed by the fact that the pressure difference in the desalination chambers of EDI-1 and EDI-2 is the same as 0.16MPa at the beginning of water flow.

[0057] Furthermore, the results of analyzing the ionic forms of the catalyst before and after passing water showed that the proportion of the OH form before passing water was >99%, and the proportion of the OH form after passing water was 97%, and no significant difference was found.

[0058] [Table 1]

[0059]

[0060] (Comparative Example 1)

[0061] In addition to using Figure 3 Except for the devices shown, a water flow test was carried out for 5000 minutes under the same conditions as in Example 1. Table 2 shows the water quality at each outlet of EDI-1, UV oxidation device, catalyst tower, and EDI-2.

[0062] The pressure difference of the desalination chamber of EDI-1 increased from 0.16 MPa at the beginning of water flow to 0.18 MPa. In addition, it can be seen that the hydrogen peroxide concentration is 16 ppb at the inlet of EDI-1 (catalyst tower outlet) and 12 ppb at the outlet of EDI-1, and hydrogen peroxide is consumed inside EDI-1. In other words, it is suggested that the ion exchange resin in EDI-1 is oxidized and may be deteriorated.

[0063] [Table 2]

[0064]

[0065] In addition, in Comparative Example 1, Figure 4 , Figure 5 The figure shows the changes in the hydrogen peroxide concentration at the catalyst tower outlet and the pressure difference in the EDI-1 desalination chamber during the water flow time. Figure 4 It can be seen that the hydrogen peroxide removal performance of the catalyst tends to decrease significantly as the water flow time passes. Figure 5 It can be seen that the pressure difference in the EDI desalination chamber began to increase 2000 minutes after hydrogen peroxide began to leak to the catalyst tower outlet, and an increase of 0.006MPa was confirmed between 2000 minutes and 3500 minutes, and further, an increase of 0.014MPa was confirmed between 3500 minutes and 5000 minutes. After 2000 minutes, since the pressure difference increased in an accelerated manner, even if the operation continued in this state, it was possible to exceed the withstand pressure of the EDI device. In addition, it was considered that the target water volume could not be passed due to insufficient pressure of the supply water, and it was judged that it could not be applied to the actual system and stopped operation.

[0066] The results of analyzing the ion form of the catalyst when the water flow was stopped showed that the proportion of the OH form before the water flow was >99%, while the proportion of the OH form after the water flow decreased to 85%. In other words, it was found that the ion form of the catalyst could not maintain the OH form, the reaction rate decreased, and hydrogen peroxide began to leak.

[0067] As described above, in the boron removal device of the present invention, by appropriately combining multiple EDIs, ultraviolet oxidation devices, and oxide removal devices, the boron concentration of the treated water can be stably reduced within 2000 hours. On the other hand, in Comparative Example 1, it can be seen that even a 5000-minute operation will hinder boron removal.

[0068] (Description of the label)

[0069] 10 Treated water

[0070] 20 Treating water

[0071] 30 The first electrical deionization device (EDI-1)

[0072] 40 Ultraviolet oxidation device (UV)

[0073] 45 Pump

[0074] 50 Oxide removal device (catalyst tower)

[0075] 60 Second Electric Deionization Device (EDI-2)

[0076] 70 Low pressure reverse osmosis membrane device (BWRO)

[0077] 75 pH adjustment device

[0078] 80 High pressure reverse osmosis membrane device (SWRO)

[0079] 90 Block Water Purifier (CP)

[0080] 95 Pure Water

[0081] 100 Boron Removal Device

[0082] 200 Pure water manufacturing equipment.

Claims

1. A boron removal device, comprising: a first electrically regenerated deionization device supplied with water to be treated; an ultraviolet oxidizing device supplied with water treated by the first electric regeneration deionizing device; an oxide removal device supplied with water treated by the ultraviolet oxidation device; as well as a second electrically regenerated deionization device supplied with water treated by the oxide removal device, The oxide removal device comprises a platinum group metal catalyst supported on an OH-type strongly basic anion exchanger. The hydrogen peroxide concentration of the water treated by the first electric regeneration deionization device is less than 1 ppb.

2. The boron removal device according to claim 1, wherein: The hydrogen peroxide concentration of the water treated by the oxide removal device is less than 1 ppb.

3. A pure water production device, comprising: a low-pressure reverse osmosis membrane device supplied with water to be treated; A pH adjusting device for adjusting the pH of permeated water from the low-pressure reverse osmosis membrane device; a high-pressure reverse osmosis membrane device supplied with the adjusted water whose pH is adjusted by the pH adjusting device; a first electric regeneration deionization device supplied with permeate water from the high pressure reverse osmosis membrane device; an ultraviolet oxidizing device supplied with water treated by the first electric regeneration deionizing device; an oxide removal device supplied with water treated by the ultraviolet oxidation device; a second electric regeneration deionization device supplied with water treated by the oxide removal device; as well as a monolithic water purifier supplied with water treated by the second electric regeneration deionization device, The oxide removal device comprises a platinum group metal catalyst supported on an OH-type strongly basic anion exchanger. The hydrogen peroxide concentration of the water treated by the first electric regeneration deionization device is less than 1 ppb.

4. The pure water production device according to claim 3, wherein: The pH adjusting device adjusts the pH of the permeated water to 5.0 to 9.

0.

5. A method for removing boron, comprising: Step a, supplying the treated water to a first electric regeneration deionization device for treatment; Step b, supplying the treated water from the first electric regeneration deionization device to an ultraviolet oxidation device for treatment; Step c, supplying the treated water from the ultraviolet oxidation device to an oxide removal device to remove oxides; as well as Step d, supplying the treated water from the oxide removal device to a second electric regeneration deionization device for treatment, The hydrogen peroxide concentration of the water after treatment in step a is less than 1 ppb, The removal of oxides in step c is carried out by a platinum group metal catalyst supported on an OH-type strongly basic anion exchanger.

6. The boron removal method according to claim 5, wherein: In the step c, the oxides are removed so that the concentration of hydrogen peroxide is less than 1 ppb.

7. A method for producing pure water, comprising: Step a, supplying the treated water to a low-pressure reverse osmosis membrane device for treatment; Step b, supplying the permeate water from the low-pressure reverse osmosis membrane device to a pH adjustment device to adjust the pH; Step c, supplying the adjusted water after the pH is adjusted by the pH adjusting device to a high-pressure reverse osmosis membrane device for treatment; Step d, supplying the permeate water from the high pressure reverse osmosis membrane device to a first electric regeneration deionization device for treatment; Step e, supplying the treated water from the first electric regeneration deionization device to an ultraviolet oxidation device for treatment; Step f, supplying the treated water from the ultraviolet oxidation device to an oxide removal device to remove oxides; Step g, supplying the treated water from the oxide removal device to a second electric regeneration deionization device for treatment; as well as Step h, supplying the treated water from the second electric regeneration deionization device to a monolithic water purifier for treatment, The hydrogen peroxide concentration of the water after treatment in step d is less than 1 ppb, The removal of oxides in step f is carried out by a platinum group metal catalyst supported on an OH-type strongly basic anion exchanger.

8. The method for producing pure water according to claim 7, wherein: In the step b, the pH of the permeated water is adjusted to 5.0 to 9.0.

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