TW201825405A - System for producing ultrapure water and method for producing ultrapure water - Google Patents

Abstract

Provided is a system for producing ultrapure water, said system being provided with a pre-treatment system, a primary purification system, and a secondary purification system in the stated order, wherein: the primary/secondary pure water system is provided with an ion exchange device that treats boron-containing to-be-treated water using an ion-exchange resin; the ion exchange device has an accommodation part for filling in the ion-exchange resin, a supply part for supplying the to-be-treated water to the accommodation part, and a discharge part for discharging treated water from the accommodation part; and, in the accommodation part, a boron-selective ion-exchange resin fills the supply-part side, and an ion-exchange resin other than the boron-selective ion-exchange resin fills the discharge-part side.

Description

Ultrapure water manufacturing system and method

The present invention relates to an ultrapure water production system capable of efficiently reducing boron present in water to be treated and an ultrapure water production method using the same.

Conventionally, in the field of manufacturing electronic devices such as semiconductors and liquid crystal panels, ultrapure water with extremely low levels of impurities such as organics, fine particles, and ionic substances has been used for cleaning systems. Among them, in the manufacturing steps of semiconductors, with the miniaturization and large capacity of semiconductors, extremely high purity is required for the ultrapure water used.

Such ultrapure water used in semiconductor manufacturing steps is mainly produced in an ultrapure water manufacturing system including a pre-treatment system, a primary pure water system, and a secondary pure water system, and is supplied to a use point. . The purpose of the pre-treatment system is to use raw coalescing filtration, microfiltration membrane (MF membrane), ultrafiltration membrane (Ultrafiltration, UF membrane) and other turbidity removal treatment equipment or activated carbon dechlorination treatment equipment to remove turbidity . The purpose of the primary pure water system is to use a two-bed three-tower ion exchange device, a reverse osmosis membrane (Reverse Osmosis, RO membrane) device, etc. to convert the ion components or total organic carbon (TOC) contained in the pretreated water. ) Remove impurities such as ingredients. The secondary pure water system is also called a subsystem, and its purpose is to use an ultraviolet oxidation device (Ultraviolet, UV device), a mixed-bed ion exchange device, a membrane degassing device, and an ultrafiltration membrane device (UF Device), etc., to remove ultra-fine particles or trace ions, especially low-molecular-weight organic matter-like impurities in primary pure water, to produce ultra-pure water with higher purity. Such an ultrapure water manufacturing system generally includes a water supply pipe that circulates ultrapure water from the secondary system to the point of use, and a return pipe that returns ultrapure water that is not used at the point of use to the front end of the secondary system and circulates.

In recent years, the negative effects of ions contained in ultrapure water, especially boron, on semiconductor products have become a problem, and reducing the concentration of boron in ultrapure water has become an important issue. Furthermore, if the treated water (primary pure water) supplied to the secondary system contains a large amount of ionic components or TOC components, it is necessary to frequently regenerate the ion exchange resin of the mixed-bed ion exchange device constituting the secondary system. The overall cost of a pure water manufacturing system is increased and unsatisfactory. Therefore, most of the ionic components or TOC components contained in the treated water are mostly removed in the primary pure water system.

The boron contained in the water to be treated can also be removed using a general ion exchange resin (for example, a strongly basic anion exchange resin, etc.). However, boron exists in the aqueous solution in the form of very weak acid boric acid, so the ion exchange capacity is smaller than that of silicon dioxide (silicic acid) or other anions, and it breaks through the ion exchange resin and leaks into the treated water relatively early. Therefore, if it is desired to reduce boron to the concentration required for ultrapure water by using such an ordinary ion exchange resin, the ion exchange resin must be frequently regenerated, and the chemicals used for the regeneration are costly.

In order to prevent the cost increase caused by the regenerating chemicals of the so-called regenerative ion exchange device as described above, for example, in Patent Document 1, it is proposed to use an ion exchange capacity larger than As a method of a boron selective ion exchange resin for an anion exchange resin, Patent Document 2 proposes a method using an organic porous body having a boron selective adsorption ability, and Patent Document 3 proposes a method using a boron selective removal ion exchange fiber. method. However, the methods described in Patent Documents 1 to 3 have the following problems: In addition to additional equipment, since the treated water containing the TOC component eluted from the component is supplied to the secondary system at the subsequent stage, the TOC component must be made Reduction to the level required for ultrapure water in the secondary system leads to an increase in the overall cost of the ultrapure water manufacturing system.

In addition, boron contained in the water to be treated can be removed by a normal reverse osmosis membrane (RO membrane). However, as described above, since the boric acid in the aqueous solution is a very weak acid, only a small part of it is dissociated, and most of it remains in the form of H ₃ BO ₄ . Therefore, the removal rate of boron by the RO membrane is extremely low. If it is desired to reduce boron to a concentration required for ultrapure water, the RO membrane device itself becomes heavy, which is not realistic in terms of cost.

In order to improve the removal rate of boron by the RO membrane as described above, for example, Patent Document 4 proposes the following method: adjusting the pH value of the water to be introduced into the RO device to be alkaline so that the weak ion component of boron is ionized The ionized boron is removed by using a RO device. However, the method described in Patent Document 4 has a problem that in addition to the addition of chemicals for adjusting the pH of the water to be treated introduced into the RO device to be alkaline, the increase in the amount of chemicals used directly Lead to increased costs and so on. In addition, when the pH value is set to a high value, there is a possibility that the hardness component (Ca, Mg, etc.) in the water precipitates in the form of a hydroxide to block the RO film. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 9-192661 [Patent Document 2] Japanese Patent Laid-Open Publication No. 2004-066153 [Patent Document 3] Japanese Patent Laid-Open Publication No. 2005-246126 [Patent Document 4] Japanese Patent Special 2004-283710

[Problems to be Solved by the Invention] The present invention has been made in view of the circumstances described above, and an object thereof is to provide an ultrapure water production system and an ultrapure water production method, the ultrapure water production system and the ultrapure water production method. By supplying the treated water in which the boron and TOC components are reduced by the primary pure water system, the ultrapure water having reduced concentration of boron can be obtained stably without applying a TOC load to the secondary system. [Means to solve the problem]

In order to solve the problem, the present invention first provides an ultrapure water manufacturing system, which is a manufacturing system of an ultrapure water including a pretreatment system, a primary pure water system, and a secondary pure water system in sequence, and the primary pure water The water system includes an ion-exchange device for processing to-be-processed water containing boron with an ion-exchange resin. The ion-exchange device includes a storage section for filling the ion-exchange resin, and a water supply section for supplying the processing water to the storage section. A supply section, and a discharge section for discharging treated water from the storage section; in the storage section, a boron selective ion exchange resin is filled on the supply section side, and boron is filled on the discharge section side An ion exchange resin other than a selective ion exchange resin (Invention 1).

According to the invention (Invention 1), in the ion exchange device provided in the primary pure water system, the supply portion side of the storage portion is filled with a boron selective ion exchange resin, and the discharge portion side is filled with a boron selective ion exchange resin other than Ion exchange resin, by which boron is selectively removed from the supplied boron-containing treated water by boron selective ion exchange resin, and then selected from boron by ion exchange resin other than boron selective ion exchange resin Since the TOC component eluted from the neutral ion exchange resin is adsorbed and removed, the primary treated water having a reduced boron concentration can be supplied without applying a TOC load to the secondary system at the subsequent stage. Thereby, ultrapure water with reduced concentration of boron can be obtained stably. In addition, the processing cost due to an increase in the TOC load in the secondary system can be reduced.

In the invention (Invention 1), it is preferable that the storage portion is erected, the supply portion is disposed on the upper side of the storage portion, and the discharge portion is disposed on the lower side of the storage portion Ministry (Invention 2).

According to this invention (Invention 2), since the treated water can be supplied from the supply part in the containing part filled with the ion exchange resin from the supply part so that the flow direction is from the upper part to the lower part of the containing part, the treated water and the ion exchange resin can be supplied. Contact efficiently, and exert the adsorption ability of each ion exchange resin to a high degree. Therefore, the boron contained in the water to be treated and the TOC component eluted from the boron selective ion exchange resin can be effectively removed.

In the said invention (invention 1, invention 2), it is preferable that the said ion exchange resin is a structure which laminated | stacked the said boron selective ion exchange resin and the ion exchange resin other than the said boron selective ion exchange resin (invention) 3).

According to this invention (Invention 3), since the ion-exchange resin is a two-layer structure of a boron-selective ion-exchange resin and an ion-exchange resin other than the boron-selective ion-exchange resin, it is easy to predict the adsorption efficiency of each ion-exchange resin. Therefore, the treatment using the ion exchange resin can also be performed efficiently.

In the invention (Inventions 1-3), the ion exchange device is preferably provided at an end of the primary pure water system (Invention 4).

In order to maximize the adsorption capacity of the boron selective ion exchange resin, it is preferred that the load of the water to be treated is only boron. According to this invention (Invention 4), by providing an ion exchange device having a boron selective ion exchange resin at the end of a primary pure water system, it is possible to supply to-be-treated water with reduced load other than boron to the ion exchange device. Therefore, the adsorption capacity of the boron selective ion exchange resin can be maximized, and the removal efficiency of boron can be improved.

In the invention (Inventions 1-4), it is preferable that the ion exchange resin other than the boron selective ion exchange resin is selected from the group consisting of a strongly basic anion exchange resin, a mixture of an anion exchange resin and a cation exchange resin, and a zwitterion. At least one of the exchange resins (Invention 5).

According to this invention (Invention 5), the TOC component eluted from the boron selective ion exchange resin can be more efficiently adsorbed and removed.

The second aspect of the present invention provides a method for producing ultrapure water, using the ultrapure water production system (invention 6). [Effect of the invention]

According to the ultrapure water production system and the ultrapure water production method of the present invention, by supplying treated water after reducing boron and TOC components in the primary pure water system to the secondary system (secondary pure water system), it is possible to eliminate When a TOC load is applied to the system, ultra-pure water having a reduced concentration of boron is stably obtained.

Hereinafter, embodiments of the ultrapure water production system and the ultrapure water production method of the present invention will be described with reference to the drawings as appropriate. The embodiments described below are for easy understanding of the present invention, and do not limit the present invention at all.

(Ultra-pure water) The ultra-pure water produced in this embodiment preferably has a boron concentration between 0.5 ppt and 50 ppt. If the boron concentration is outside the range, the semiconductor product may be adversely affected during system cleaning in the manufacturing process of the semiconductor product, which is not preferable.

(Treatment Water) The treatment water containing boron used in this embodiment is not particularly limited. Usually the treated water (pre-treated water) after the turbidity treatment of the pre-treatment system, that is, the treated water supplied to the primary treatment system, contains about 30 ppb of boron. Furthermore, boron mainly exists in the form of boric acid (B (OH) ₃ ) in the water to be treated.

[Ultra-pure water production system] FIG. 1 is a block diagram showing an ultra-pure water production system according to an embodiment of the present invention. The ultrapure water manufacturing system 1 shown in FIG. 1 includes a pre-treatment system 2, a primary pure water system 3, and a secondary pure water system (secondary system) 4 in this order. The raw water supplied to the pretreatment system 2 is subjected to a turbidity removal treatment using a coalescing filtration, an MF membrane (microfiltration membrane), a UF membrane (ultrafiltration membrane), or a dechlorination treatment using activated carbon, and then passes through a water supply pipe L1. It is supplied to the primary pure water system 3. The pre-treatment water supplied to the primary pure water system 3 is obtained by removing impurities such as ionic components or TOC components, and then supplying the water to the secondary system 4 through the water supply pipe L2. In the sub-system 4, extremely small amounts of fine particles or trace ionic components in the water to be treated, especially impurities such as low-molecular trace organic matter, are removed to produce ultra-pure water with higher purity. The ultrapure water produced in the secondary system 4 is sent to the use point 5 through the water supply pipe L3.

<Pure primary water system> The primary pure water system 3 has a two-bed three-tower ion exchange device (first ion exchange device) 31, a reverse osmosis membrane (RO membrane) device 32, and a mixed-bed ion exchange device ( A second ion exchange device) 33 and an ion exchange device (third ion exchange device) 34 containing a boron selective ion exchange resin. The first ion exchange device 31 includes a cation exchange tower (H tower), a decarbonation tower, and an anion exchange tower (OH tower) in this order, and is used to dechlorinate the water to be treated supplied from the pretreatment system 2. A reverse osmosis membrane (RO membrane) device 32 is used to remove impurities such as ionic components or TOC components in the water to be treated. Through the dechlorination treatment of the first ion exchange device 31, the treated water having a reduced chlorine concentration is supplied to the reverse osmosis membrane (RO membrane) device 32, so the water recovery rate in the reverse osmosis membrane (RO membrane) device 32 is improved. Along with this, the removal rate of impurities such as ionic components or TOC components contained in the treated water is also improved. The second ion exchange device 33 includes a column that uniformly mixes and fills the anion exchange resin and the cation exchange resin, and removes low-molecular-weight cations and anions present in the water to be treated to improve the purity of the treated water.

Furthermore, the mixed-bed ion exchange device provided in the primary pure water system may be any of a regenerative type and a non-regenerating type, and a non-regenerating type ion exchange device is preferred. The reason is that if a regenerative ion exchange device is used in a primary pure water system, the cost is increased not only by the chemicals used to regenerate the ion exchange resin, but also by the chemicals necessary for the regeneration of the ion exchange resin. The amount of drainage is easily increased. Generally, when a non-regenerating ion exchange device is used in a primary pure water system, it is used in combination with a reverse osmosis membrane (RO membrane) device or the like as in this embodiment to increase the removal rate of ion components.

(Ion Exchange Device Containing Boron Selective Ion Exchange Resin) Next, referring to FIG. 2, an ion exchange device (third ion exchange device) containing a boron selective ion exchange resin included in the primary pure water system 3 of this embodiment is also referred to in FIG. 2. Be detailed.

The third ion exchange device 34 is used to remove boron contained in the water to be treated with a boron selective ion exchange resin, and to remove the boron contained in the boron selective ion exchange resin from an ion exchange resin other than the boron selective ion exchange resin. The dissolved TOC component is removed. In order to maximize the adsorption capacity of the boron selective ion exchange resin, it is desirable that the load of the water to be treated supplied to the third ion exchange device 34 is only boron, so the third ion exchange device 34 is installed in primary pure water. The end of system 3. In addition, since the ultraviolet oxidizing device (UV device) 41 provided at the front end of the secondary system 4 at the rear stage is large and expensive, it is required to reduce the size as much as possible. Therefore, it is also desirable to remove the TOC component of the treated water as much as possible in the third ion exchange device 34 provided at the end of the primary pure water system 3, so that the ultraviolet oxidation device provided at the front end of the secondary system 4 is not ( UV device) 41 applies a TOC load.

FIG. 2 is a schematic diagram showing a configuration of a third ion exchange device 34 according to this embodiment. The third ion exchange device 34 includes a storage portion 341 to fill the ion exchange resin A, a supply portion 342 to supply treated water to the storage portion 341, and a discharge portion 343 to discharge the processed water from the storage portion 341. . The storage portion 341 is erected, a supply portion 342 is arranged on the upper side of the storage portion 341, a discharge portion 343 is arranged on the lower side of the storage portion 341, and a boron selective ion exchange resin A1 is filled on the supply portion 342 side. The discharge portion 343 side is filled with an ion exchange resin A2 other than a boron selective ion exchange resin.

In the third ion exchange device 34, the supply portion 342 is filled with a boron selective ion exchange resin A1, and the discharge portion 343 is filled with an ion exchange resin A2 other than the boron selective ion exchange resin. The selective ion exchange resin A1 adsorbs and removes boron from the boron-containing treated water supplied to the storage portion 341, and then removes the boron selective ion exchange resin A1 from an ion exchange resin A2 other than the boron selective ion exchange resin. The eluted TOC component is adsorbed and removed, so that the primary treated water having a reduced boron concentration can be supplied without applying a TOC load to the secondary system 4 in the subsequent stage. The TOC load on the secondary system 4 can be suppressed, thereby preventing the overall cost of the ultrapure water production system from increasing.

In addition, the storage portion 341 is erected, and a supply portion 342 is disposed on the upper side and a discharge portion 343 is disposed on the lower side, whereby the supply portion 342 can be self-supported in a flow direction from above the storage portion 341. The treated water is supplied, so the ion exchange resin A is not easily stirred by the treated water, and the two-layer structure of the boron selective ion exchange resin A1 and the ion exchange resin A2 other than the boron selective ion exchange resin is maintained. Thereby, the to-be-processed water can be made to contact with each ion exchange resin A1 and ion exchange resin A2 efficiently, and the adsorption ability which each ion exchange resin A1 and ion exchange resin A2 has is exhibited to a high degree. Therefore, the boron contained in the water to be treated and the TOC component eluted from the boron selective ion exchange resin A1 can be effectively removed.

The ion exchange resin A filled in the storage portion 341 may have a structure in which a boron selective ion exchange resin A1 and an ion exchange resin A2 other than the boron selective ion exchange resin are laminated. Since the ion-exchange resin A has the general two-layer structure described above, the prediction of the adsorption efficiency of the ion-exchange resin A1 and the ion-exchange resin A2 becomes easy, so that it can be efficiently processed.

In addition, the storage section 341 may have a partition for separating the boron-selective ion-exchange resin A1 from the ion-exchange resin A2 other than the boron-selective ion-exchange resin. By having such a separator, it is possible to prevent the ion exchange resin A1 and the ion exchange resin A2 from being mixed or flowing up and down. The storage portion 341 may be, for example, a secondary storage portion 3411 (not shown) filled with a boron selective ion exchange resin A1 and a secondary storage portion 3412 filled with an ion exchange resin A2 other than the boron selective ion exchange resin. (Not shown) Structure of serial connection.

The layer height of the boron selective ion exchange resin A1 is not particularly limited, and may be appropriately set according to need. It is preferably set to be 800 mm or more, and more preferably set to 1000 mm or more. By setting the layer height to 800 mm or more, the adsorption efficiency of the boron selective ion exchange resin A1 is improved. In addition, the layer height of the ion exchange resin A2 other than the boron-selective ion exchange resin is not particularly limited, and may be appropriately set as necessary. It is preferably set to be 100 mm or more, and more preferably to be 500 mm or more. set up. By setting the layer height to 100 mm or more, the adsorption efficiency of the ion exchange resin A2 other than the boron selective ion exchange resin is improved.

(Boron-Selective Ion Exchange Resin) As long as the boron-selective ion-exchange resin A1 contains a boron-selective N-methylglucosamine group instead of an ion-exchange group in the anion-exchange resin as a functional group (chelating resin), , It is not particularly limited. However, the introduction rate of boron-selective chelating groups into anion exchange resins has not reached 100%, and the adsorption rate may decrease due to the adsorption of other ions on the remaining anion groups. Therefore, in order to prevent this, the boron selective ion exchange resin A1 is preferably a chelate resin used to produce ultrapure water or a chelate resin washed with ultrapure water, which has a small amount of TOC components such as elution, and a TOC concentration in water passing through. Try not to add resin before and after. Such a chelate resin preferably has an N-methylglucosamine group. For example, CRB03 manufactured by Mitsubishi Chemical Corporation can be used.

(Ion exchange resin other than boron selective ion exchange resin) The ion exchange resin A2 other than boron selective ion exchange resin is not particularly limited, and it is preferably an ion exchange resin used for producing ultrapure water or an ion exchange resin washed with ultrapure water. Resin with less elution of TOC components such as ion exchange resins and increase in TOC concentration (ΔTOC) before and after water passing is about 1 ppb to 3 ppb. Such an ion exchange resin is preferably at least one selected from the group consisting of a strongly basic anion exchange resin, a mixture of an anion exchange resin and a cation exchange resin, and an amphoteric ion exchange resin. A more basic anion exchange resin is more suitable. For example, it can be used. SAT10L manufactured by Mitsubishi Chemical Corporation.

<Secondary system> The secondary system 4 includes an ultraviolet oxidation device (UV device) 41, a membrane degassing device 42, a mixed-bed ion exchange device 43, and an ultrafiltration membrane device (UF device) 44 in this order. The ultraviolet oxidation device (UV device) 41 is used to oxidize and decompose the TOC component remaining in the water to be treated by an oxidation treatment by ultraviolet irradiation. The membrane deaerator 42 is used to reduce the amount of dissolved oxygen in the treated water. The mixed-bed ion exchange device 43 is used to remove ionized components from the oxidatively decomposed TOC components in the treated water, and to improve the purity of the treated water. An ultrafiltration membrane device (UF device) 44 is used to remove particles and the like of an ion exchange resin flowing out of the mixed bed ion exchange device 43.

Moreover, in the ordinary ultrapure water manufacturing system, the scale of the primary pure water system and the secondary system are quite different, and the primary pure water system is large-scale. In this embodiment, the scale of each device included in the primary pure water system 3 is larger than that of the secondary system 4. For example, the third ion exchange device 34 provided at the end of the primary pure water system 3 is not usually installed in The front ends of the sub-systems 4 of different sizes. Similarly, the ultraviolet oxidizing device (UV device) 41 provided at the front end of the secondary system 4 is generally not installed at the end of the primary pure water system 3 having different scales.

[Ultra-pure water production method] Next, a method for producing ultra-pure water using the ultra-pure water production system 1 of the present embodiment as described above will be described.

The raw water supplied to the pretreatment system 2 is subjected to a turbidity removal treatment using a coacervation filtration, an MF membrane (microfiltration membrane), a UF membrane (ultrafiltration membrane), or a dechlorination treatment (pretreatment step) using activated carbon, etc. It is supplied to the primary pure water system 3 through the water supply pipe L1. The pre-treatment water supplied to the primary pure water system 3 is supplied to the secondary system 4 through a water supply pipe L2 after the removal processing of impurities such as ionic components or TOC components (primary pure water production step). The primary pure water supplied to the sub-system 4 removes extremely small amounts of fine particles or trace ionic components, especially low-molecular trace organic matter-like impurities, to produce ultra-pure water with higher purity (secondary pure water production step) ). The ultrapure water produced in the secondary system 4 is sent to the use point 5 through the water supply pipe L3.

(Processing Procedure of Ion Exchange Device Containing Boron Selective Ion Exchange Resin) Next, referring to FIG. 2, an ion exchange device containing a boron selective ion exchange resin (third ion exchange) included in the primary pure water system 3 of this embodiment is also referred to. The processing steps of the device) 34 are described in detail.

First, in the storage portion 341, the treated water is supplied from the supply portion 342 so that the flow direction is from above the storage portion 341 to downward. The receiving portion 341 is erected, a supply portion 342 is arranged on the upper side, a discharge portion 343 is arranged on the lower side, a boron selective ion exchange resin A1 is filled on the supply portion 342 side, and boron is filled on the discharge portion 343 side. Ion exchange resin A2 other than selective ion exchange resin. For the treated water supplied to the storage portion 341, boron ions are first adsorbed and removed by the boron selective ion exchange resin A1, and then the boron selective ion exchange is performed by ion exchange resin A2 other than the boron selective ion exchange resin. The TOC component eluted from the resin A1 is adsorbed and removed. The treated water (primary treated water) from which boron and TOC components have been removed is discharged from the discharge section 343 and sent to the next step.

As described above, the supply portion 342 is filled with a boron-selective ion exchange resin A1, and the discharge portion 343 is filled with an ion-exchange resin A2 other than the boron-selective ion-exchange resin. A1 adsorbs and removes boron from the treated water containing boron supplied to the storage portion 341, and then removes the TOC component eluted from the boron-selective ion-exchange resin by ion-exchange resin A2 other than the boron-selective ion-exchange resin. Therefore, it is possible to supply primary treated water having a reduced boron concentration without applying a TOC load to the secondary system 4 in the subsequent stage. The TOC load on the secondary system 4 can be suppressed, thereby preventing the overall cost of the ultrapure water production system from increasing.

In the method for producing ultrapure water according to this embodiment, the water passing velocity of the treated water into the third ion exchange device 34 is not particularly limited, but it is preferably 30 / h to 180 / h in terms of space velocity (SV) The range is more preferably 60 / h. If the water passing rate of the water to be treated is less than 30 / h, the processing speed of the third ion exchange device 34 becomes slow and the efficiency is poor. If the water passing rate of the water to be treated exceeds 180 / h, the treatment of the third ion exchange device 34 becomes insufficient, and boron in the water to be treated cannot be sufficiently removed.

According to the ultrapure water production method using the ultrapure water production system 1 of this embodiment, the treated water obtained by reducing boron and TOC components in the primary pure water system 3 is supplied to the secondary system (secondary pure water system) 4 It is possible to stably obtain ultra-pure water having a reduced concentration of boron without applying a TOC load to the secondary system 4.

Furthermore, the above-mentioned ultrapure water manufacturing method can also be understood as the following ultrapure water manufacturing method: it is an ultrapure water that includes a pretreatment step, a primary pure water manufacturing step, and a secondary pure water manufacturing step in this order. The manufacturing method, and the one-time pure water manufacturing step includes a step of treating the treated water containing boron by using an ion exchange resin, and the processing step of the ion exchange resin includes a first separation step of selecting the treated water containing boron from boron. The ion-exchange resin is contacted to separate boron from the treated water; and the second separation step is to contact the treated water after the first separation step with an ion-exchange resin other than the boron-selective ion-exchange resin. TOC components are separated in the treated water.

As mentioned above, although this invention was demonstrated with reference to drawings, this invention is not limited to the said embodiment, Various changes are possible. [Example]

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

[Example 1] Treatment of the water to be treated was performed using the third ion exchange device 34 shown in FIG. 2. A cylindrical acrylic tube string with a diameter of 40 mm (hereinafter referred to as "acrylic string") was used as the receiving portion 341, and Mitsubishi was filled in the acrylic string so that the layer height became 100 mm. A strongly basic anion exchange resin manufactured by Chemical Co., Ltd. is filled with a boron selective ion exchange resin manufactured by Mitsubishi Chemical Corporation so that the layer height becomes 800 mm. The treated water with a boron concentration of 0.8 ppb, a resistivity of 18.2 MΩ · cm, and a TOC component of 0.5 ppb was passed through the water at a flow rate of 60 / h (SV). The boron concentration (ppt) and TOC concentration (ppb) of the obtained treated water were measured.

[Comparative Example 1] Except that a boron selective ion exchange resin manufactured by Mitsubishi Chemical Corporation was filled in an acrylic string so that the layer height became 800 mm, the same conditions as in Example 1 were performed. The boron concentration (ppt) and TOC concentration (ppb) of the obtained treated water were measured.

[Comparative Example 2] Except that a strong basic anion exchange resin manufactured by Mitsubishi Chemical Corporation was filled in an acrylic column so that the layer height became 800 mm, the same conditions as in Example 1 were performed. The boron concentration (ppt) and TOC concentration (ppb) of the obtained treated water were measured.

[Results] Table 1 shows the boron concentration (ppt) and TOC concentration (ppb) of the treated water over time. As is clear from the results, in Example 1, the boron concentration of the treated water can be maintained at a level satisfying 24 hours, and the TOC concentration can also be maintained without a significant increase.

In Comparative Example 1, although the boron concentration of the treated water was maintained at a level of 24 hours, the TOC concentration increased significantly at 1 hour, and no significant decrease was observed at the time of 24 hours. The reason is that the TOC component is eluted from the boron selective ion exchange resin. Furthermore, the case where the treated water (primary treated water) of Comparative Example 1 was supplied to the secondary system 4 and treated at a water flow rate of 60 / h (SV) to obtain a treated water with a TOC concentration of 1.0 ppb or less stably was performed. In the estimation, the following result was obtained: compared with the case of the embodiment 1, a cost equivalent to 10% of the cost of the entire secondary system 4 is further required.

In Comparative Example 2, since the ion exchange capacity was low, the boron concentration of the treated water could not be maintained at a level of 24 hours, but the TOC concentration did not increase significantly.

[Table 1]

As described above, according to the ultrapure water production system and the ultrapure water production method of the present invention, the treated water obtained by reducing boron and TOC components in the primary pure water system is supplied to the secondary system (secondary pure water system). It can stably obtain ultra-pure water with low concentration of boron without applying a TOC load to the secondary system. [Industrial availability]

The present invention is useful as an ultrapure water production system and an ultrapure water production method for stably obtaining ultrapure water having a reduced concentration of boron.

1‧‧‧ Ultra-pure water manufacturing system

2‧‧‧ pre-processing system

3‧‧‧Pure water system

31‧‧‧Two-bed three-tower ion exchange device (first ion exchange device)

32‧‧‧ reverse osmosis membrane (RO membrane) device

33‧‧‧ Mixed bed type ion exchange device (second ion exchange device)

34‧‧‧ ion exchange device containing boron selective ion exchange resin (third ion exchange device)

341‧‧‧ Containment Department

342‧‧‧Supply Department

343‧‧‧Exhaust

4‧‧‧ secondary pure water system (secondary system)

41‧‧‧ultraviolet oxidation device (UV device)

42‧‧‧ membrane degassing device

43‧‧‧ mixed bed type ion exchange device

44‧‧‧ Ultrafiltration membrane device (UF device)

5‧‧‧use points

L1, L2, L3 ‧‧‧ water supply piping

R1‧‧‧ return piping

A‧‧‧ion exchange resin

A1‧‧‧ Boron Selective Ion Exchange Resin

A2 ‧‧‧ ion exchange resin other than boron selective ion exchange resin

FIG. 1 is a block diagram showing an ultrapure water production system according to an embodiment of the present invention. FIG. 2 is a schematic view showing an ion exchange device containing a boron selective ion exchange resin included in an ultrapure water production system according to an embodiment of the present invention.

Claims (6)

An ultrapure water manufacturing system is a system for manufacturing ultrapure water including a pretreatment system, a primary pure water system, and a secondary pure water system in sequence, and the primary pure water system is provided with an ion exchange resin for An ion exchange device for processing to-be-processed water, the ion-exchange device includes: a storage section for filling an ion-exchange resin, a supply section for supplying the water to be processed to the storage section, and a storage section from the storage A discharge section that discharges treated water in the section, and in the storage section, a boron selective ion exchange resin is filled on the supply section side, and an ion exchange resin other than a boron selective ion exchange resin is filled on the discharge section side. . The ultrapure water manufacturing system according to item 1 of the scope of patent application, wherein the storage portion is erected, the supply portion is disposed on the upper side of the storage portion, and the supply portion is disposed on the lower side of the storage portion. There is the discharge section. The ultrapure water manufacturing system according to item 1 or item 2 of the patent application scope, wherein the ion exchange resin is an ion exchange resin other than the boron selective ion exchange resin and the boron selective ion exchange resin Layered structure. The ultrapure water manufacturing system according to any one of claims 1 to 3, wherein the ion exchange device is provided at an end of the primary pure water system. The ultrapure water production system according to any one of claims 1 to 4, wherein the ion exchange resin other than the boron selective ion exchange resin is selected from the group consisting of a strongly basic anion exchange resin and an anion exchange resin. At least one of a mixture with a cation exchange resin and an amphoteric ion exchange resin. A method for producing ultrapure water using the ultrapure water production system according to any one of claims 1 to 5 of the scope of patent application.