JP2012254428A - Ultrapure water producing method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily control the concentration of dissolved nitrogen to be necessary in a use point without wasting added nitrogen while removing dissolved oxygen in ultrapure water that is treated water.SOLUTION: The pure water production apparatus comprises: a primary pure water tank 11 for storing the treated water that contains dissolved oxygen; an ultraviolet oxidation apparatus 14 that irradiates the treated water from the primary pure water tank 11 with ultraviolet; a non-regeneration type mixed bed ion-exchange apparatus 21 that removes an ion component in the treated water having irradiated with the ultraviolet; a supply line that supplies the treated water from which ion has been removed to the use point; and a circulation line that branches from the supply line and returns a portion or all of treated water to the primary pure water tank 11. The apparatus is further provided with: a nitrogen addition apparatus 15 that adds nitrogen to the treated water; and a dissolved oxygen removing apparatus 17 that is provided with a catalytic metal carrier supporting a platinum group metal, and brings the treated water to which the nitrogen has been added into contact with to the catalytic metal carrier to remove the dissolved oxygen in the treated water.

Description

  The present invention relates to an ultrapure water manufacturing method and apparatus, and more particularly, to ultrapure water that is suitable for use in an electronic component manufacturing process such as a semiconductor device and has a very low concentration of dissolved oxygen and a controlled concentration of dissolved nitrogen. The present invention relates to a method and an apparatus for manufacturing.

  In the manufacture of semiconductor devices and liquid crystal display devices, pure water such as ultrapure water from which impurities are highly removed is used. In ultrapure water that is widely used in the field of semiconductor manufacturing, the dissolved oxygen (DO) concentration, which is one of the water quality indicators, is often managed to be 5 ppb or less, for example, 1 ppb or less.

  Ultra-pure water is prepared by pre-treating raw water such as industrial water, well water, tap water, etc., and then treating the raw water with a primary pure water production device composed of a reverse osmosis membrane separation device and an ion exchange device. And the primary pure water is processed by a subsystem constituted by an ultraviolet oxidation device, an ion exchange device, an ultrafiltration membrane separation device, and the like. A primary pure water tank that temporarily stores primary pure water is often provided between the primary pure water production apparatus and the subsystem.

  In order to make dissolved oxygen into a very low concentration, a dissolved oxygen removal apparatus is provided in a primary pure water manufacturing apparatus and a subsystem. Further, the inside of the primary pure water tank is sealed with nitrogen gas, that is, nitrogen purge is also performed.

  As a method for removing dissolved oxygen from pure water, Patent Document 1 proposes treating treated water with a resin carrying a platinum group metal. In Patent Document 2, a platinum group-supported monolith in which a platinum group metal is supported on a monolithic organic porous anion exchanger is used, and after adding hydrogen to the water to be treated, the water is treated with the platinum group-supported monolith. It has been proposed to remove dissolved oxygen from water. Patent Document 2 also discloses a method for producing a platinum group-supported monolith.

  By the way, depending on the process in which ultrapure water is used, it may be desirable to have a predetermined amount (for example, about 10 ppm) of dissolved nitrogen. In recent years, the concentration of dissolved nitrogen is controlled in addition to the concentration of dissolved oxygen. It is also demanded. As a method for controlling the dissolved nitrogen concentration in ultrapure water, in Patent Document 3, by adjusting the degree of vacuum of the degassing membrane device while measuring the dissolved nitrogen concentration when performing deaeration treatment of the water to be treated, A method for controlling the dissolved nitrogen concentration has been proposed. Patent Document 4 proposes a method in which high-purity nitrogen is added to the water to be treated after the dissolved gas is removed by a degassing membrane or the like, and the flow rate of the added nitrogen gas is controlled at that time. . Further, in Patent Document 5, after deoxidizing the water to be treated with a palladium catalyst capable of selectively removing dissolved oxygen, high purity nitrogen gas is dissolved in the water to be treated to remove nitrogen gas. A method for producing dissolved water has been proposed.

JP 2008-93606 A JP 2010-240642 A JP 10-309566 A JP 2008-86879 A JP 2007-699 A

  Among the conventional methods for controlling the dissolved nitrogen concentration in the production of ultrapure water, the method disclosed in Patent Document 3 adjusts the degree of vacuum in the degassing process, so that the performance for removing dissolved oxygen is lowered. It is difficult to adjust the dissolved nitrogen concentration while adjusting the concentration to a very low concentration. In the method described in Patent Document 4, dissolved nitrogen that has already been contained in the water to be treated is also removed at the time of removing the dissolved gas, so that more nitrogen must be added in the subsequent nitrogen addition step. Therefore, the amount of nitrogen added is wasted. In the method shown in Patent Document 5, nitrogen gas is added to ultrapure water in which almost no dissolved gas exists due to removal of dissolved oxygen, so that the dissolution rate of nitrogen gas is increased, and dissolved nitrogen is increased. It is difficult to finely adjust the density of the toner.

  An object of the present invention is to provide a pure water production method capable of easily managing the concentration of dissolved nitrogen required at a use point while removing dissolved oxygen in ultrapure water which is treated water to an extremely low concentration, and To provide an apparatus.

  The pure water production method of the present invention has at least an irradiation step of irradiating the water to be treated containing dissolved oxygen with ultraviolet rays and an ion exchange step of performing an ion exchange treatment on the water to be treated irradiated with ultraviolet rays. In the pure water production method in which pure water is generated and the generated pure water is circulated to the irradiation step as at least part of the water to be treated, a nitrogen addition step of adding nitrogen to the water to be treated, and a platinum group metal And a dissolved oxygen removing step of contacting the treated catalyst metal carrier to which the treated water to which nitrogen has been added in the nitrogen adding step is brought into contact, and removing dissolved oxygen in the treated water.

  The pure water production apparatus of the present invention includes a storage tank for storing water to be treated containing dissolved oxygen, an ultraviolet oxidation device for irradiating ultraviolet light to the water to be treated flowing out of the storage tank, and a treatment to be irradiated with ultraviolet rays by the ultraviolet oxidation device. An ion exchange device that removes ion components in the water, a supply line that supplies treated water from which ion components have been removed by the ion exchange device to a use point, and a part or all of the treated water is returned to the storage tank by branching from the supply line A pure water production apparatus having a circulation line, comprising: a nitrogen addition apparatus for adding nitrogen to the water to be treated; and a catalyst metal carrier on which a platinum group metal is supported, wherein nitrogen is added by the nitrogen addition apparatus. A dissolved oxygen removing device for bringing the water to be treated into contact with the catalyst metal carrier to remove the dissolved oxygen in the water to be treated.

  In the present invention, nitrogen is added to the water to be treated in the presence of dissolved oxygen in the water to be treated, and then the water to be treated is brought into contact with a catalyst metal carrier (that is, a platinum group catalyst) on which a platinum group metal is supported. And only the dissolved oxygen is selectively removed. This makes it possible to easily manage the concentration of dissolved nitrogen required at the point of use without consuming wasteful nitrogen.

It is a figure which shows an example of a structure of the pure water manufacturing apparatus of one Embodiment of this invention. It is a figure which shows the structure of a pure water manufacturing apparatus in an experiment example.

  Next, embodiments of the present invention will be described with reference to the drawings. The pure water production apparatus according to one embodiment of the present invention shown in FIG. 1 is configured as an ultrapure water production apparatus that is a subsystem, and receives the supply of primary pure water from a primary pure water production apparatus (not shown). Ultrapure water in which the dissolved oxygen (DO) concentration is controlled to an extremely low concentration and the dissolved nitrogen (DN) concentration is controlled to a predetermined value is generated and supplied to the use point. Naturally, the pure water manufacturing apparatus based on this invention is not limited to what was shown by FIG.

  The apparatus shown in FIG. 1 includes a primary pure water tank 11 that is a storage tank that receives primary pure water as supply water, and a pump (P) 12 that sends pure water from the primary pure water tank 11. On the other hand, the heat exchanger 13, the ultraviolet oxidation device 14, the nitrogen addition device 15, the dissolved oxygen removal device 17, the non-regenerative mixed bed ion exchange device (CP) 21 and the ultrafiltration membrane device (UF) 22 are arranged in this order. The water flowing out from the ultrafiltration membrane device 22 is connected to the use point through the valve 23 as ultrapure water. In order to return the ultrapure water that has not been used at the use point to the primary pure water tank 11, a circulation pipe including a valve 24 is provided. In this apparatus, the primary pure water tank 11 to the pump 12, the heat exchanger 13, the ultraviolet oxidation apparatus 14, the nitrogen addition apparatus 15, the dissolved oxygen removal apparatus 17, the non-regenerative mixed bed ion exchange apparatus 21 and the ultrafiltration membrane apparatus. A circulation system that returns to the primary pure water tank 11 through 22 is formed.

In this configuration, the primary pure water in the primary pure water tank 11 is supplied to the ultraviolet oxidizer 14 through the heat exchanger 13 by the pump 12 and irradiates the pure water with ultraviolet rays in the ultraviolet oxidizer 14. As a result, organic substances in pure water are decomposed. Subsequently, nitrogen (N ₂ ) is added to the pure water flowing out from the ultraviolet oxidation device 14 by the nitrogen addition device 15. In the pure water to which nitrogen is added, the dissolved oxygen is removed by the dissolved oxygen removing device 17, and then metal and the like are removed by ion exchange treatment in the non-regenerative mixed bed ion exchange device 21. Further, ultrafiltration is performed. Fine impurities are removed in the membrane device 22 and sent to the use point as ultrapure water. The primary pure water tank 11, the pump 12, the heat exchanger 13, the ultraviolet oxidizer 14, the non-regenerative mixed bed ion exchanger 21 and the ultrafiltration membrane device 22 are manufactured as ultrapure water equipment constructed as a subsystem. Since what is generally used in the apparatus can be used, the nitrogen addition apparatus 15 and the dissolved oxygen removal apparatus 17 will be described in detail below.

<Nitrogen addition device>
The nitrogen addition device 15 includes a nitrogen supply unit that supplies nitrogen gas into pure water, a dissolved nitrogen meter 32 that measures a dissolved nitrogen concentration in pure water, and a supply amount of nitrogen gas based on the measurement results of the dissolved nitrogen meter 32. And a control unit 33 for determining. The nitrogen supply unit includes a gas-dissolving film 31 and a mass flow controller 34 provided between the nitrogen (N ₂ ) gas supply source and the gas-dissolving film 31. Supply high purity nitrogen gas. The supply amount of nitrogen gas is adjusted by the mass flow controller 34 by the control unit 33.

  The gas-dissolving film 31 is a film that does not transmit liquid but allows only gas to pass. Examples of such a film include a film made of polyolefin such as polyethylene and polypropylene, and a fluorine resin such as polytetrafluoroethylene. In addition, there are membranes made of polysulfone, silicone rubber or the like. A hollow fiber membrane in which a gas permeable membrane is formed in a hollow fiber shape is also suitably used as the gas dissolving membrane 31. The shape of such a hollow fiber membrane is not particularly limited, but the inner diameter of the hollow fiber membrane is 0.00. The thing of about 1-1 mm is preferable. The length of the hollow fiber membrane is preferably about 10 to 300 cm, particularly about 50 to 100 cm.

  The mass flow controller 34 detects the flow rate on the inlet side with a flow rate sensor, and adjusts the flow rate on the outlet side to a set flow rate with a flow rate control valve.

  The dissolved nitrogen meter 32 measures the concentration of dissolved nitrogen in the water to be measured by taking the water to be measured through the valve 16 using pure water to which nitrogen has been added as the water to be measured. For example, a measuring cell into which water to be measured is introduced, a change rate of thermal conductivity before and after introduction is obtained by a heat detector, and a dissolved nitrogen concentration is calculated from the obtained change rate as the dissolved nitrogen meter 32. be able to. As such a dissolved nitrogen meter, a commercially available one, for example, model-3621 manufactured by Hack Ultra, Inc. can be used.

  The control unit 33 calculates the set flow rate of the mass flow controller 34 from the measurement result of the dissolved nitrogen meter 32 and the detection result of the flow rate sensor of the mass flow controller 34, and adjusts the opening degree of the flow rate control valve of the mass flow controller 34. A simple signal is sent to the mass flow controller 34.

<Dissolved oxygen removal device>
The dissolved oxygen removing device 17 is a device using a catalytic metal carrier on which a platinum group metal is supported. Hereinafter, the catalyst metal carrier on which the platinum group metal is supported is referred to as a platinum group catalyst 41. The dissolved oxygen removing device 17 removes dissolved oxygen in the pure water by bringing the pure water into contact with the platinum group catalyst 41.

Consider a case where the primary pure water tank 11 is purged with nitrogen. When nitrogen is purged, the concentration of dissolved nitrogen in pure water delivered from the primary pure water tank 11 is about 3 ppm. In such a case, if a degassing membrane is used to remove dissolved oxygen,
(1) In the configuration in which the nitrogen addition device is provided at the subsequent stage of the degassing membrane for removing dissolved oxygen, the dissolved nitrogen derived from the nitrogen purge is also removed by the degassing membrane along with the dissolved oxygen. Nitrogen must also be added with a nitrogen addition device, resulting in wasted nitrogen,
(2) In a configuration in which a nitrogen addition device is provided in front of the degassing membrane for removing dissolved oxygen, it is necessary to add nitrogen in consideration of the dissolved nitrogen removed by the degassing membrane, and fine adjustment of the amount of dissolved nitrogen is possible. Become difficult,
This creates a problem. Therefore, in the present embodiment, the dissolved oxygen is removed using the platinum group catalyst 41 that can selectively remove the dissolved oxygen. Thereby, only dissolved oxygen can be removed without reducing the concentration of dissolved nitrogen in the pure water, and the dissolved nitrogen dissolved in the pure water can be used effectively in the nitrogen-purged primary pure water tank 11. Become.

The form of the platinum group catalyst 41 is not particularly limited, but preferably, an ion exchange resin (particularly an anion exchange resin) carrying a platinum group metal or an anion exchanger that is monolithic organic porous (ie A monolith anion exchanger) carrying a platinum group metal is preferable. When a monolith anion exchanger is used, 2000 to 20000 times the volume of the monolith anion exchanger per hour (ie SV = 2000 to 20000 h ^-1 ; SV is several times the catalyst support volume per hour) Therefore, it is more preferable to use a monolith anion exchanger as a carrier.

The dissolved oxygen removing device 17 may be configured by only the platinum group catalyst 41. However, when the platinum group catalyst 41 is used alone, there is a limit in the amount of reaction with dissolved oxygen in pure water. If it exceeds, dissolved oxygen cannot be removed from pure water. Therefore, a hydrogen addition means for supplying hydrogen to the platinum group catalyst 41 is provided, and water and dissolved oxygen are reacted in the presence of the platinum group catalyst 41 to generate water, and the amount of dissolved oxygen is reduced by the amount of reaction. It is preferable to adopt such a configuration. As a means for adding hydrogen, one having a configuration in which hydrogen (H ₂ ) gas is directly added to the platinum group catalyst 41 can be used, and pure water is supplied from the hydrogen gas through a gas dissolution membrane in the previous stage of the platinum group catalyst 41. It is also possible to add in. However, as the hydrogen addition means, since the adjustment of the addition amount is easy, as shown in FIG. 1, hydrogen water in which hydrogen is dissolved in advance is passed through the dissolved oxygen removing device 17 and the platinum group catalyst 41 and It is preferable to make the structure which contacts. 1, hydrogen water is supplied from a hydrogen gas supply source to dissolve hydrogen in pure water to generate hydrogen water, and the flow rate of hydrogen water from the hydrogen water generator 18 is as follows. A hydrogenation means is constituted by the flow meter (FI) 19 to be measured and the valve 20 provided between the flow meter 19 and the dissolved oxygen removing device 17. This hydrogen water is mixed with pure water from the nitrogen addition device 15 and comes into contact with the platinum group catalyst 41. The hydrogen supplied to the hydrogen water generator 18 is preferably generated by electrolyzing pure water from the standpoint of preventing impurities from being mixed and eliminating the need for a hydrogen gas cylinder. For example, a gas-dissolved film can be used for the hydrogen water generator 18.

  When the hydrogen addition means is provided as described above, if dissolved hydrogen is present in the pure water, the dissolved nitrogen concentration may be detected at a value higher than the actual dissolved nitrogen concentration in the dissolved nitrogen meter. The hydrogenation is preferably performed downstream of the branch of the piping to the dissolved nitrogen meter 32 of the nitrogen addition device 15 in the circulation system.

<Arrangement of nitrogen addition device and dissolved oxygen removal device>
Next, the arrangement relationship between the nitrogen addition device 15 and the dissolved oxygen removal device 17 will be described.

  In general, when nitrogen gas is added to pure water through a gas dissolution membrane, the dissolution rate of nitrogen gas in pure water is determined by the sum of the partial pressures of the gases contained in the pure water and the gas phase side of the gas dissolution membrane. The larger the difference from the partial pressure of the gas, the larger the difference. That is, pure water that hardly contains dissolved gas for any gas component is easy to dissolve the gas. For this reason, when nitrogen gas is added after removing dissolved oxygen in pure water, it becomes difficult to adjust the nitrogen gas flow rate according to the opening degree of the flow rate adjustment valve of the mass flow controller 34 in the nitrogen addition device 15. It becomes difficult to finely adjust the amount of dissolved nitrogen in water. Therefore, in the present embodiment, the nitrogen addition device 15 is disposed in front of the dissolved oxygen removal device 17. Since nitrogen gas is added in a state where dissolved oxygen is present in pure water, it becomes easy to finely adjust the amount of nitrogen gas added so as to obtain a predetermined dissolved nitrogen concentration.

[Experimental example]
Next, the results of experiments conducted to show the effectiveness of the pure water production apparatus of this embodiment will be described.

The pure water manufacturing apparatus shown in FIG. 2 was configured. In this apparatus, the nitrogen addition apparatus 15 is removed from the apparatus shown in FIG. 1, and instead, the valves 51 to 54, the dissolved oxygen meter 55, and the dissolved nitrogen meter 56 are provided, so that the inlet and the outlet of the dissolved oxygen removing device 17 are provided. It is possible to measure the dissolved oxygen concentration and dissolved nitrogen concentration of pure water, that is, the dissolved oxygen concentration and dissolved nitrogen concentration in pure water before and after passing through the dissolved oxygen removing device 17. The dissolved oxygen concentration was measured using a dissolved oxygen meter 55 (model-3600 manufactured by Hack Ultra), and the dissolved nitrogen concentration was measured using a dissolved nitrogen meter 56 (model-3621 manufactured by Hack Ultra). The dissolved oxygen removal device 17 uses a platinum group catalyst carrier comprising a polyvinyl chloride column with an inner diameter of 16 mm and a Pd-supported monolith (supported amount: 2.3 g / L) filled with a layer height of 40 mm (about 8 mL). It was. The primary pure water tank 11 was purged with nitrogen, and the pure water was passed through the dissolved oxygen removing device 17 at 40 L / h (that is, SV = 5000 h ⁻¹ ). Table 1 shows the measurement results of the dissolved oxygen concentration and the dissolved nitrogen concentration in pure water before and after passing through the dissolved oxygen removing device 17.

表１から、白金族触媒を用いた溶存酸素除去装置では、その前後での溶存窒素濃度に変わりがなく、純水中の溶存酸素を選択的に除去できることがわかる。したがって、本実施形態の純水製造装置のように、窒素添加装置の後段に、白金族触媒を用いた溶存酸素除去装置を配置することにより、溶存酸素濃度を極低濃度にまで低減しつつ、ユースポイントで必要とする溶存窒素濃度にするために添加すべき窒素ガスの量を少なくすることができることが分かる。また、白金族触媒による溶存酸素除去装置を用いる場合には、超純水を循環させる構成として純水製造装置を構成すると、循環する超純水中の溶存窒素濃度が基本的に低下することがないから、一度、ユースポイントで必要な溶存窒素濃度に調整した後は、窒素添加装置による窒素ガスの添加を微調整程度で済ませることができる。

From Table 1, it can be seen that the dissolved oxygen removal apparatus using a platinum group catalyst has no change in the dissolved nitrogen concentration before and after that, and can selectively remove dissolved oxygen in pure water. Therefore, like the pure water production apparatus of the present embodiment, by disposing a dissolved oxygen removal apparatus using a platinum group catalyst at the subsequent stage of the nitrogen addition apparatus, while reducing the dissolved oxygen concentration to an extremely low concentration, It can be seen that the amount of nitrogen gas to be added in order to obtain the dissolved nitrogen concentration required at the use point can be reduced. In addition, when using a dissolved oxygen removal device using a platinum group catalyst, if the pure water production device is configured as a configuration for circulating ultrapure water, the concentration of dissolved nitrogen in the circulating ultrapure water may basically decrease. Therefore, once the dissolved nitrogen concentration required at the point of use is adjusted, the addition of nitrogen gas by the nitrogen adding device can be finely adjusted.

[Comparative example]
The same experiment as the experimental example was performed except that a degassing membrane (Dainippon Ink & Chemicals, Inc .: EF-002A) was used as the dissolved oxygen removal device in the pure water production apparatus shown in FIG. Table 2 shows the measurement results of the dissolved oxygen concentration and the dissolved nitrogen concentration in pure water before and after passing through the dissolved oxygen removing device.

表２から、溶存酸素除去装置として脱気膜を使用した場合には、溶存酸素除去装置を通過した純水での溶存窒素濃度が低下しており、溶存酸素だけでなく溶存窒素も溶存酸素除去装置によって除去されてしまうことが分かった。脱気膜による溶存酸素除去装置では、純水中の溶存酸素とともに溶存窒素も除去してしまうため、ユースポイントで必要とする溶存窒素濃度にするために添加すべき窒素ガスの量が、実験例に比べて多くなる。

From Table 2, when a degassing membrane is used as a dissolved oxygen removal device, the concentration of dissolved nitrogen in the pure water that has passed through the dissolved oxygen removal device is reduced, and not only dissolved oxygen but also dissolved nitrogen is removed. It was found that it was removed by the device. Since the dissolved oxygen removal device using a degassing membrane removes dissolved nitrogen as well as dissolved oxygen in pure water, the amount of nitrogen gas to be added to achieve the dissolved nitrogen concentration required at the point of use is an experimental example. More than

  When ultrapure water is circulated in the circulation system, dissolved nitrogen is also removed every time it passes through the dissolved oxygen removal device. Therefore, in order to make the dissolved nitrogen concentration at the point of use constant, it was removed. It can also be seen that there is a waste of having to add nitrogen again by the amount of nitrogen. Since the amount of dissolved nitrogen removed by the device for removing dissolved oxygen using a degassing membrane is not always constant, the amount of nitrogen gas to be added is frequently adjusted according to fluctuations in the amount of dissolved nitrogen to be removed. It becomes necessary to do this, and the control becomes complicated.

DESCRIPTION OF SYMBOLS 11 Primary pure water tank 12 Pump 13 Heat exchanger 14 Ultraviolet oxidizer 15 Nitrogen addition device 16, 20, 23, 24, 51-54 Valve 17 Dissolved oxygen removal device 18 Hydrogen water production device 19 Flow meter (FI)
21 Non-regenerative mixed bed ion exchanger (CP)
22 Ultrafiltration membrane device (UF)
31 Gas dissolved membrane 41 Platinum group catalyst 32,56 Dissolved nitrogen meter 55 Dissolved oxygen meter

Claims (12)

Producing and producing pure water having at least an irradiation step of irradiating the water to be treated containing dissolved oxygen with ultraviolet rays and an ion exchange step of performing ion exchange treatment on the water to be treated irradiated with ultraviolet rays In the pure water production method in which the purified water is circulated to the irradiation step as at least part of the treated water,
A nitrogen addition step of adding nitrogen to the water to be treated;
A dissolved oxygen removing step of contacting the water to be treated to which nitrogen is added in the nitrogen addition step with a catalytic metal carrier on which a platinum group metal is supported, and removing dissolved oxygen in the water to be treated;
A method for producing pure water, comprising:   The nitrogen addition step and the dissolved oxygen removal step are performed on the treated water irradiated with ultraviolet rays in the irradiation step, and then the ion exchange step is performed on the treated water from which the dissolved oxygen has been removed. The method for producing pure water according to claim 1.   The nitrogen addition step is a gas dissolution step of adding nitrogen to the water to be treated through a gas dissolution membrane, a concentration of dissolved nitrogen in the water to be treated downstream from the nitrogen addition step, and a measured dissolved nitrogen The pure water manufacturing method of Claim 1 or 2 which has a control process which controls the amount of nitrogen supplied to the said gas dissolution film | membrane according to a density | concentration.   The method for producing pure water according to any one of claims 1 to 3, further comprising a hydrogenation step of adding hydrogen so that hydrogen is supplied to the catalyst metal carrier.   The hydrogen addition step includes a step of adding hydrogen to pure water to form hydrogen water, and the hydrogen water is brought into contact with the catalyst metal carrier together with the treated water to which nitrogen has been added by the nitrogen addition step. The pure water manufacturing method of Claim 4. A storage tank for storing treated water containing dissolved oxygen, an ultraviolet oxidation device for irradiating ultraviolet rays to the treated water flowing out of the storage tank, and an ionic component in the treated water irradiated with ultraviolet rays by the ultraviolet oxidation device is removed. An ion exchange device, a supply line for supplying treated water from which ion components have been removed by the ion exchange device to a use point, and a circulation line that branches from the supply line and returns part or all of the treated water to the storage tank A pure water production apparatus comprising:
A nitrogen addition device for adding nitrogen to the water to be treated;
Dissolved oxygen removal comprising a catalyst metal carrier on which a platinum group metal is supported, and removing the dissolved oxygen in the water to be treated by bringing the treated water to which nitrogen has been added by the nitrogen addition device into contact with the catalyst metal carrier. Equipment,
An ultrapure water production apparatus.   The pure water production apparatus according to claim 6, wherein the nitrogen addition apparatus and the dissolved oxygen removal apparatus are disposed at a position that is subsequent to the ultraviolet oxidation apparatus and is upstream of the ion exchange apparatus.   The nitrogen addition apparatus includes a gas-dissolving film for adding nitrogen to the water to be treated, a dissolved nitrogen meter for measuring a dissolved nitrogen concentration in the water to be treated to which nitrogen is added, and a measured dissolved nitrogen concentration. The pure water manufacturing apparatus according to claim 6, further comprising: a control unit that determines a flow rate of nitrogen supplied to the gas dissolution membrane and controls a nitrogen addition amount in the gas dissolution membrane.   The pure water production apparatus according to any one of claims 6 to 8, wherein the catalyst metal carrier is a catalyst metal carrier in which a platinum group metal is supported on an anion exchanger.   The apparatus for producing pure water according to claim 9, wherein the anion exchanger is monolithic organic porous.   The pure water manufacturing apparatus according to any one of claims 6 to 10, further comprising hydrogen adding means for supplying hydrogen to the dissolved oxygen removing apparatus.   The pure water production apparatus according to claim 11, wherein the hydrogen addition unit includes a hydrogen water generation device that adds hydrogen to pure water and supplies the hydrogen water as hydrogen water to the dissolved oxygen removal device.

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