JP4624066B2 - Operation method of electric deionized water production apparatus and electric deionized water production apparatus - Google Patents

Description

  The present invention relates to an operation method of an electric deionized water production apparatus and an electric deionized water production apparatus used in various industries such as semiconductor manufacturing field, electric power field, medical and pharmaceutical manufacturing, food industry, and research facilities. .

  As a method for producing pure water or ultrapure water from the water to be treated containing boron, (1) a method of treating with an ion exchange resin device, (2) a pH of 9. 9 by injecting an alkaline agent into the water to be treated. A method of treating with a reverse osmosis membrane device as two or more (Japanese Patent Laid-Open No. 11-188359), (3) a method of treating reverse osmosis membrane device treated water with an electric deionized water production device, and the like are known. In either method alone, it is difficult to reduce boron to several tens of ppt or less, and boron is also reduced by combining the methods (1) to (3).

  The method of removing boron by treating with the ion exchange resin (1) can be operated at low cost. However, in order to prevent ion breakthrough of the ion exchange resin, the ion exchange resin device needs to be periodically regenerated with a chemical and cannot be operated continuously. In addition, it is necessary to separately install equipment for cleaning with chemicals, which is expensive. In addition, there is an operation cost due to the necessity of regularly replenishing the medicine.

  On the other hand, in the method of removing boron by injecting an alkaline agent into the feed water of (2) and treating with a reverse osmosis membrane device, the dissociation of boric acid proceeds under alkaline conditions with a pH of 9.2 or more, and ions This utilizes the property of being easily separated as a particulate material, and the boron removal performance by the reverse osmosis membrane device is greatly improved under alkaline conditions with a pH of 9.2 or higher. However, when an alkaline agent is injected into the water to be treated, the water to be treated becomes alkaline, and hardness components such as calcium and magnesium are precipitated as scales, causing a decrease in the amount of permeated water and an increase in water flow differential pressure. Problem occurs. Therefore, it is necessary to prevent the generation of scale by injecting the scale inhibitor simultaneously with injecting the alkaline agent into the feed water. In this case, since it is necessary to install the apparatus for it separately, cost starts. Moreover, there exists a possibility of causing the deterioration of permeated water quality by inject | pouring an alkaline agent.

In the treatment method using the electric deionized water production apparatus of (3), when a reverse osmosis membrane apparatus is installed in the previous stage, it is easy to remove boron up to about several ppb, but it is removed to several ppt level. It is very difficult to do. For example, in order to provide ultra-pure water quality such as 18.2 MΩ · cm, which is required in semiconductor manufacturing factories, it is necessary to install a non-regenerative ion exchange resin device after the deionization device. As described above, the ion exchange resin breaks through in a short time due to boron that cannot be sufficiently removed. For this reason, it is necessary to frequently replace the non-regenerative ion exchange resin apparatus, which increases costs. In addition, the removal performance of boron is lowered in a supply water containing a lot of weak acid components such as carbonic acid and silica. In order to improve this, Japanese Patent Application Laid-Open No. 11-188359 discloses a method for improving the removal performance of carbonic acid, silica, and boron by adding an alkaline agent to the feed water of the electric deionized water production apparatus. ing.
JP 11-188359 A (Claim 1)

  However, when an alkaline agent is added to the water supplied to the electrical deionized water production apparatus, the load on the electrical deionized water production apparatus increases, and the quality of the treated water may be deteriorated. In addition, in the electric deionized water production apparatus described in JP-A-11-188359, the demineralization chamber structure is unknown, the anode side is partitioned by an anion exchange membrane, the cathode side is partitioned by a cation exchange membrane, and the anion exchange membrane Including two small desalting chambers defined by an intermediate ion exchange membrane located between the cation exchange membrane and the cation exchange membrane, and water to be treated is sequentially passed through the two small desalting chambers in series. There is no disclosure about what comprises a plurality of desalting chambers and one or more concentrating chambers disposed between the desalting chambers and the desalting chambers.

  Accordingly, an object of the present invention is to reduce the addition of chemicals such as alkaline agents as much as possible when producing pure water or ultrapure water using an electric deionized water production apparatus, An object of the present invention is to provide an operation method of an electric deionized water production apparatus and an electric deionized water production apparatus capable of dramatically reducing the boron concentration in treated water.

  In such a situation, the present inventors conducted extensive studies, and as a result, the anode chamber and the cathode chamber were disposed at both ends, the anode side was partitioned by an anion exchange membrane, the cathode side was partitioned by a cation exchange membrane, and the anion exchange membrane and the A first small desalination chamber filled with an anion exchanger monolayer partitioned by an intermediate ion exchange membrane located between cation exchange membranes, and a second small desalination filled with a mixed bed of anion exchanger and cation exchanger. One or a plurality of desalination chambers containing a salt chamber, and water to be treated containing boron is serially passed through the first small desalination chamber and the second small desalination chamber in this order; In an electric deionized water production apparatus comprising one or more concentration chambers disposed between a desalting chamber and the desalting chamber, the pH of the second small desalting chamber feed water is set to 9.2 or more, If this water is passed through the second small desalting chamber, the addition of a chemical such as an alkaline agent is minimal. Even, it found such that it is possible to dramatically reduce the boron concentration in the treated water, and have completed the present invention.

  That is, in the present invention (1), the anode chamber and the cathode chamber are arranged at both ends, the anode side is partitioned by the anion exchange membrane, the cathode side is partitioned by the cation exchange membrane, and the anode chamber and the cathode chamber are positioned between the anion exchange membrane and the cation exchange membrane. Including a first small desalting chamber filled with an anion exchanger monolayer partitioned by an intermediate ion exchange membrane and a second small desalting chamber filled with a mixed bed of anion exchanger and cation exchanger, and boron One or a plurality of desalting chambers in which treated water containing water is passed in series in this order through the first small desalting chamber and the second small desalting chamber, the desalting chamber, and the desalting chamber In an electric deionized water production apparatus provided with one or a plurality of concentrating chambers arranged between chambers, the pH of the second small demineralization chamber feed water is set to 9.2 or more, and this is supplied to the second small deionization water. It provides a method for operating an electric deionized water production apparatus characterized by passing water through a salt chamber. That.

  Moreover, this invention (2) provides the operating method of the said electrical deionized water manufacturing apparatus characterized by filling the said ion concentration body into the said concentration chamber. Moreover, this invention (3) provides the operating method of the said electrical deionized water manufacturing apparatus characterized by inject | pouring an alkaline agent into the flow path of said 2nd small demineralization chamber feed water. Moreover, this invention (4) provides the operating method of the said electrical deionized water manufacturing apparatus characterized by the above-mentioned to-be-processed water containing a boron being what salt was inject | poured. Further, the present invention (5) is characterized in that the water to be treated containing boron is obtained by decarboxylation, and then an alkaline agent is injected into the decarboxylation water. The operation method of an ion water production apparatus is provided.

In the present invention (6), the anode chamber and the cathode chamber are disposed at both ends, the anode side is partitioned by an anion exchange membrane, the cathode side is partitioned by a cation exchange membrane, and the anode chamber and the cathode chamber are positioned between the anion exchange membrane and the cation exchange membrane. Including a first small desalting chamber filled with an anion exchanger monolayer partitioned by an intermediate ion exchange membrane and a second small desalting chamber filled with a mixed bed of anion exchanger and cation exchanger, and boron One or a plurality of desalting chambers in which treated water containing water is passed in series in this order through the first small desalting chamber and the second small desalting chamber, the desalting chamber, and the desalting chamber An electric deionized water production apparatus comprising one or a plurality of concentrating chambers arranged between chambers, the following (1) to (3); (1) the second small demineralization chamber feed water Alkaline injection means for injecting an alkaline agent into the flow path, (2) Salt injection for injecting salt into the water to be treated containing boron One or two selected from a stage, (3) a decarboxylation means for decarboxylating the treated water containing boron and an alkali injection means for injecting an alkaline agent into the flow path of the decarboxylated treatment water or means by further comprising Rukoto a, there is provided a second electrodeionization water producing apparatus according to claim 9.2 or more and a to Rukoto the pH of the feed water to the small depletion chamber.

  According to the present invention, when pure water or ultrapure water is produced using an electric deionized water production apparatus in various industries or research facilities such as the semiconductor manufacturing field, electric power field, medical and pharmaceutical manufacturing, and food industry, Even if the addition of a chemical such as a chemical is extremely small, the boron concentration in the treated water of the electric deionized water production apparatus can be drastically reduced to several tens of ppt or less. As a result, the load on the non-regenerative ion exchange resin apparatus in the subsequent stage can be greatly reduced, so that the frequency of replacement of the non-regenerative ion exchange resin apparatus can be reduced, and high-purity water can be stably supplied. Can be provided. In addition, stable operation can be continued for a long time for the entire subsystem including the non-regenerative ion exchange resin apparatus. Further, for example, the weakly acidic components in the water to be treated containing a large amount of weakly acidic components such as silica and carbonic acid such as permeated water of a reverse osmosis membrane device can be removed very efficiently.

  An electric deionized water production apparatus (hereinafter also simply referred to as EDI) used in the operation method of the present invention has an anode chamber containing an anode plate and a cathode chamber containing a cathode plate arranged at both ends, and the anode side is an anion exchange membrane. Including a first small desalting chamber and a second small desalting chamber which are partitioned by a cation exchange membrane and partitioned by an intermediate ion exchange membrane located between the anion exchange membrane and the cation exchange membrane. One or a plurality of desalination chambers in which water to be treated is passed through the first small desalination chamber and the second small desalination chamber in series in this order; the desalination chamber and the desalination chamber; One or a plurality of concentrating chambers disposed between them is provided, and such a structure and a water flow method are disclosed in Japanese Patent Application Laid-Open No. 2001-239270.

  The first small desalting chamber of EDI is filled with an anion exchanger monolayer. The filling form of the anion exchanger monolayer in the first small desalting chamber is not particularly limited, and may be a part or all of the first small desalting chamber. The second small desalting chamber of EDI is filled with a mixed bed of cation exchanger and anion exchanger. The form of filling the mixed bed of the cation exchanger and the anion exchanger in the second small desalting chamber is not particularly limited and may be any part or all of the second small desalting chamber. The EDI concentration chamber may be either filled or unfilled with an ion exchanger, but the one filled with an ion exchanger is preferable in that the electric resistance of EDI can be reduced and the operating cost can be reduced. . Further, when the electric resistance is reduced, a larger amount of current can be applied at a low voltage, and a higher current value applied to EDI is preferable in terms of improving boron removal performance.

  In the present invention, the water to be treated containing boron is not particularly limited. For example, from well water, tap water, sewage, industrial water, river water, cleaning wastewater such as semiconductor devices in a semiconductor manufacturing factory, or from a concentration chamber Examples thereof include permeated water obtained by treating the recovered water with a reverse osmosis membrane, and recovered water that has been used at a point of use such as a semiconductor manufacturing factory and has not been subjected to a reverse osmosis membrane treatment. Moreover, these mixed water may be sufficient. Although it does not restrict | limit especially as a boron density | concentration in to-be-processed water, For example, the to-be-processed water which contains about 1-500 microgram / l boron is mentioned.

In the operation method of the present invention, the pH of the second small desalting chamber feed water is set to 9.2 or more, and this is passed through the second small desalting chamber. Under alkaline conditions with a pH of 9.2 or higher, the dissociation of boric acid proceeds and it is easily separated as an ionic substance. In other words, boron exists mainly in the form of boric acid H ₃ BO ₃ in an aqueous solution, whereas it takes a chemical form as boric acid in an undissociated state when the pH is 9.2 or less of boric acid. When the pH is 9.2 or more, dissociation proceeds as H ₃ BO ₃ + OH ⁻ → B (OH) ⁴⁻ . Therefore, the boron removal performance is greatly improved in the second small desalting chamber under alkaline conditions where the pH is 9.2 or higher.

  As a method of setting the pH of the second small desalting chamber feed water to 9.2 or more, a method of injecting an alkaline agent into the flow path of the second small desalting chamber feed water (method 1), a treatment containing boron Examples thereof include a method of injecting salt into water (method 2) and a method of injecting an alkaline agent into the decarboxylated water after decarboxylation of the water to be treated containing boron (method 3). Among these, the method 1 is preferable in that the pH of the second small desalting chamber feed water can be stably increased to 9.2 or more by adding an extremely small amount of an alkaline agent. These methods 1 to 3 may be performed either alone or in combination. However, performing any method alone makes the apparatus simple and easy to operate. Is preferable.

  According to the method of injecting the alkali agent into the flow path of the second small desalination chamber supply water, the boron concentration in the EDI-treated water is drastically reduced to several tens of ppt or less simply by adding a very small amount of the alkali agent. be able to. Since the anion components such as carbonic acid that inhibit the increase in pH in the first small desalting chamber filled with the anion exchanger are removed, the second small desalting chamber feed water is water that has little buffering action due to the anion components. And water rich in cationic components. For this reason, the alkali agent added in a very small amount contributes to the action of raising the pH as it is. Therefore, there is almost no influence on the quality of treated water due to the addition of the alkaline agent, and high-purity treated water with a drastically reduced boron concentration can be obtained. The amount of the alkaline agent injected into the second small desalination chamber feed water is not particularly limited because it varies depending on the quality of the water to be treated, but is generally 0.1 to 10 mg NaOH / l, preferably 0.5 to 5 mg NaOH / l. It is. The amount of alkali added is about 1/10 compared to the case of using a conventional electric deionized water production apparatus described in the prior art of JP-A-2001-239270. The alkali agent is not particularly limited, and examples thereof include sodium hydroxide and potassium hydroxide.

According to the method of injecting salt into the water to be treated containing boron, the concentration of boron in the EDI treated water is several times without deteriorating the quality of the EDI treated water simply by adding a very small amount of salt to the treated water. It can be drastically reduced to 10 ppt or less. The EDI first small desalination chamber treated water used in the present invention has a high pH even if it is treated water to which no salt is added because it is rich in cationic components. By adding, the first small desalting chamber treated water is further rich in cationic components, and the pH rises. The amount of salt injected into the water to be treated is not particularly limited because it varies depending on the quality of the water to be treated, but is generally 0.05 to ⁶ mg Na ⁺ / l, preferably 0.25 to 3 mg Na ⁺ / l. The salt is not particularly limited, and examples thereof include sodium chloride, potassium chloride, sodium nitrate, and potassium nitrate.

  According to the method of injecting an alkaline agent into the decarboxylated water after decarbonating the water to be treated containing boron, the buffering action of carbonic acid in the water to be treated supplied to EDI is greatly reduced. For this reason, the pH of the second small desalting chamber feed water can be easily increased to 9.2 or more simply by adding a trace amount of an alkali agent to the decarboxylated water. Further, for the same reason as in the method (1), it is possible to obtain high-purity treated water in which boron is drastically reduced without deteriorating the treated water quality of EDI. The decarboxylation method is not particularly limited, and examples thereof include a decarboxylation method using a membrane deaerator. Examples of the alkali agent include the same as the alkali agent used in the method (1).

  In the EDI apparatus of the present invention, an anode chamber and a cathode chamber are arranged at both ends, an anode side is partitioned by an anion exchange membrane, a cathode side is partitioned by a cation exchange membrane, and an intermediate located between the anion exchange membrane and the cation exchange membrane. Contains a first small desalting chamber filled with an anion exchanger monolayer partitioned by an ion exchange membrane and a second small desalting chamber filled with a mixed bed of anion exchanger and cation exchanger, and contains boron One or a plurality of desalination chambers in which treated water is passed through the first small desalination chamber and the second small desalination chamber in series in this order, the desalination chamber, and the desalination chamber One or a plurality of concentrating chambers arranged in between, and a pH meter for measuring the pH of the second small desalting chamber feed water as required, comprising the following (1) to (3 ); (1) Alkaline injection means for injecting an alkaline agent into the flow path of the second small desalination chamber feed water, (2) the boron Salt injecting means for injecting salt into the water to be treated containing, (3) decarbonation means for decarboxylating the water to be treated containing boron, and an alkali agent being injected into the flow path of the decarbonized treated water One or more means selected from alkali injection means. If the EDI of the present invention is used, the above-mentioned EDI operating method can be reliably implemented. In the EDI of the present invention, it is preferable that the means (1) to (3) are individually installed from the viewpoint that the apparatus becomes simple and the cost can be reduced.

The specific operating conditions of EDI in the present invention are not particularly limited, and for example, the SV of the water to be treated that flows into the first small desalination chamber and the second small desalination chamber in series is 50 to 500 [h. ^-1 ], more desirably 100-300 [h ^-1 ], the structure of the desalting chamber and the flow rate of the desalting chamber are adjusted to pass water, and the current density applied to the desalting chamber is 0.05. It may be adjusted and operated so as to be ˜0.5 [A / dm ² ], more preferably 0.15 to 0.4 [A / dm ² ].

  EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, this is merely illustrative and does not limit the present invention.

  An electric deionized water production apparatus having the following specifications was operated according to the flow shown in FIG. Moreover, the boron concentration and specific resistivity in the treated water of the electric deionized water production apparatus were measured. The results are shown in Table 1. The injection of caustic soda into the second small desalting chamber feed water was adjusted so that the pH of the second small desalting chamber feed water was 10.2.

(Electrical deionized water production equipment)
The electric deionized water production apparatus 1 has the above-described structure, and a more detailed structure and water flow method are disclosed in Japanese Patent Laid-Open No. 2001-239270. The electric deionized water production apparatus 1 in FIG. 1 is shown in a simplified manner, and a first small desalting chamber 21 and a second small desalting chamber 22 are connected in series by a pipe 23. The pipe 23 connecting the first small desalting chamber 21 and the second small desalting chamber 22 has one end connected to one end of a caustic soda injection pipe 31 connected to the caustic soda injection means 3, and the second small desalination chamber A pH meter 4 is attached to the pipe 23 after the addition of caustic soda in the pipe 23 connecting the first small desalting chamber 21 and the second small desalting chamber 22 so that the pH of the feed water in the chamber 22 can be understood.

(EDI operating conditions)
EDI: “Standard D2EDI” (manufactured by Organo)
-Desalination chamber; first small desalination chamber (width 300 mm, height 360 mm, thickness 8 mm),
Second small desalination chamber (width 300mm, height 360mm, thickness 4mm)
An ion exchange membrane; a cation exchange membrane (Neoceptor C66-10F),
Anion exchange membrane (Neocepta AHA) (both manufactured by Tokuyama)
-Ion exchange resin: 1st small desalting chamber (anion exchange resin (IRA402BL)), 2nd small desalting chamber (cation exchange resin (IR120B) and anion exchange resin (IRA402BL) mixed bed (volume ratio 1: 1)) (Both made by Rohm and Haas)
・ Processed water volume: 1.0 m ³ / h
Current density: 0.2 A / dm ²
Water to be treated to be supplied to EDI; water containing 40 to 50 ppb of boron treated with a reverse osmosis membrane device after the city water has been turbidized. Electric conductivity of water to be supplied to EDI: 4 to 5 μS / cm
, Carbon concentration of the treated water supplied to the EDI: 3~4 mgCO ₂ / L
The reverse osmosis membrane device uses “ES-10” (8 inches, 2 pieces) (manufactured by Nitto Denko), and the caustic soda injection means is a chemical injection unit “PTU-100-PZD-61” (manufactured by Takumina). Was used.

Comparative Example 1
Except for omitting the addition of caustic soda to the second small demineralization chamber feed water, the same method as in Example 1 was used to measure the boron concentration and specific resistivity in the treated water of the electrical deionized water production apparatus. The results are shown in Table 1.

  As is apparent from Table 1, when caustic soda was injected into the second small desalting chamber feed water and the pH of the second small desalting chamber feed water was 10.2, the boron concentration in the treated water was dramatically increased. It can be seen that it can be reduced. Further, it can be seen that the amount of the caustic soda added is very small, and the quality of the treated water is not deteriorated.

  As shown in the flow diagram of FIG. 2, the embodiment is the same except that the caustic soda injection means is omitted and one end of a sodium chloride injection pipe 51 whose other end is connected to the sodium chloride injection means 5 is connected to the treated water supply pipe 11. 1 was performed, and the boron concentration and the specific resistivity in the water to be treated of the electric deionized water production apparatus 1a were measured. The results are shown in Table 2. In addition, injection | pouring of sodium chloride to to-be-processed water was adjusted so that the pH of the 2nd small desalination chamber feed water might be set to 9.7. As the sodium chloride injection means, a chemical injection unit “PTU-100-PZD-61” (manufactured by Takumina) was used.

Comparative Example 2
Except for omitting the addition of sodium chloride to the EDI treated water, the same method as in Example 2 was used to measure the boron concentration and specific resistivity in the treated water of the electric deionized water production apparatus. The results are shown in Table 2.

Comparative Example 3
As shown in the flow diagram of FIG. 3, instead of the electric deionized water production apparatus 1 having a demineralization chamber in which two small demineralization chambers are arranged in series, electric deionization having a single type of demineralization chamber. Except having used the water manufacturing apparatus 1b, it carried out by the method similar to Example 2, and measured the boron density | concentration and specific resistivity in the treated water of the electrical deionized water manufacturing apparatus 1b. The results are shown in Table 2. In addition, one type of desalination chamber 24 of the electrical deionized water production apparatus 1b has a width of 300 mm, a height of 360 mm, and a thickness of 12 mm, and is filled with a mixed bed of anion exchange resin and cation exchange resin.

  From the results of Table 2, in Comparative Example 2 in which sodium chloride was not added to the first small desalting chamber feed water, the pH of the second small desalting chamber feed water was lower than 8.4 and pH 9.2. While the boron concentration in the treated water of the deionized water production apparatus is 3 μg / l, in Example 2 in which sodium chloride was added to the first small desalting chamber feed water, the pH of the second small desalting chamber feed water was It became 9.7, and the boron concentration in the treated water was 0.05 μg / l, which was drastically reduced. On the other hand, Comparative Example 3 in which the structure of the demineralization chamber of the electric deionized water production apparatus is only one type of demineralization chamber filled with a mixed bed of anion exchange resin and cation exchange resin is the same as in Example 2. Despite the addition of sodium chloride, the boron concentration in the treated water of the electric deionized water production apparatus was 4 μg / l. Since the structure of the desalting chamber of Comparative Example 3 is similar to the structure of the conventional electric deionized water production apparatus described in the prior art of Japanese Patent Laid-Open No. 2001-239270, the desalting chamber is more than one type of room. It can be seen that the general EDI constructed does not have the effect of the present invention.

  As shown in the flowchart of FIG. 4, the membrane degassing device 6 is installed in the treated water supply pipe 11, and the first small desalination chamber 21 and the second small desalination chamber 22 are connected at a caustic soda injection location. It replaces with the piping 23, and it carries out by the method similar to Example 1 except having set it as the piping 12 which connects the membrane deaeration apparatus 6 and the 1st small demineralization chamber 21, Processing of the electrical deionized water manufacturing apparatus 1c The boron concentration and specific resistivity in water were measured. The results are shown in Table 3. In addition, the injection | pouring of the caustic soda to the to-be-processed water by which the membrane deaeration process was carried out was adjusted so that pH of a 2nd small desalination chamber feed water might be set to 9.8. As the membrane deaerator, “liqui-Cel G284” (X-40) (manufactured by Hoechst International Tokyo) was used.

Comparative Example 4
Except for omitting the addition of caustic soda to the membrane deaeration treated water passing through the pipe 12 connecting the membrane deaerator 6 and the first small desalination chamber 21, the same method as in Example 3 was used. The boron concentration and specific resistivity in the treated water of the deionized water production apparatus were measured. That is, in Comparative Example 4, the treated water that has been membrane deaerated is supplied to the first small desalting chamber as it is to obtain treated water. The results are shown in Table 3.

  As apparent from Table 3, Comparative Example 4 in which caustic soda was not injected into the first small demineralization chamber feed water after membrane deaeration treatment had a pH of 8.4 for the second small demineralization chamber feed water, The membrane was adjusted so that the pH of the second small desalting chamber feed water was 9.8, while the pH was lower than 9.2 and the boron concentration in the treated water of the electric deionized water production apparatus was 3 μg / l. In Example 3 in which caustic soda was injected into the first small desalination chamber feed water after the deaeration treatment, the boron concentration in the treated water of the electric deionized water production apparatus became 0.06 μg / l, and the effect of dramatically reducing boron. Was recognized. In addition, since the first small desalting chamber feed water is subjected to membrane deaeration treatment and the carbonic acid concentration is reduced, the buffering effect on the pH of carbonic acid is weakened, and the pH can be raised even with a smaller amount of caustic soda added. It was. As a result, the effect of dramatically reducing boron without deteriorating the quality of treated water was recognized.

It is a flowchart of the operating method of the electric deionized water manufacturing apparatus used in Example 1. It is a flowchart of the operating method of the electric deionized water manufacturing apparatus used in Example 2. It is a flowchart of the operating method of the electric deionized water manufacturing apparatus used in Comparative Example 3. It is a flowchart of the operating method of the electric deionized water manufacturing apparatus used in Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a-1c Electric deionized water manufacturing apparatus 3 Caustic soda injection | pouring means 4 pH meter 5 Sodium chloride injection | pouring means 6 Membrane deaeration apparatus 21 1st small demineralization chamber 22 2nd small demineralization chamber 24 Demineralization chamber

Claims (6)

  The anode chamber and the cathode chamber are arranged at both ends, the anode side is partitioned by an anion exchange membrane, the cathode side is partitioned by a cation exchange membrane, and is partitioned by an intermediate ion exchange membrane positioned between the anion exchange membrane and the cation exchange membrane. The first small desalting chamber filled with the anion exchanger monolayer and the second small desalting chamber filled with the mixed bed of the anion exchanger and the cation exchanger are included, and the treated water containing boron contains the first treated water containing boron. One or a plurality of desalting chambers that are passed in series in this order through one small desalting chamber and the second small desalting chamber, and one disposed between the desalting chamber and the desalting chamber Alternatively, in the electric deionized water production apparatus having a plurality of concentrating chambers, the pH of the second small desalting chamber feed water is set to 9.2 or more, and this is passed through the second small desalting chamber. The operation method of the electrical deionized water production apparatus.   The operation method of the electric deionized water production apparatus according to claim 1, wherein the concentration chamber is filled with an ion exchanger.   The operation method of the electric deionized water production apparatus according to claim 1, wherein an alkaline agent is injected into the flow path of the second small desalination chamber supply water.   The operating method of the electric deionized water production apparatus according to any one of claims 1 to 3, wherein the water to be treated containing boron is injected with salt.   5. The electricity according to claim 1, wherein the water to be treated containing boron is obtained by decarboxylation, and then an alkali agent is injected into the decarboxylation water. Of operating a deionized water production system. The anode chamber and the cathode chamber are arranged at both ends, the anode side is partitioned by an anion exchange membrane, the cathode side is partitioned by a cation exchange membrane, and is partitioned by an intermediate ion exchange membrane positioned between the anion exchange membrane and the cation exchange membrane. The first small desalting chamber filled with the anion exchanger monolayer and the second small desalting chamber filled with the mixed bed of the anion exchanger and the cation exchanger are included, and the treated water containing boron contains the first treated water containing boron. One or a plurality of desalting chambers that are passed in series in this order through one small desalting chamber and the second small desalting chamber, and one disposed between the desalting chamber and the desalting chamber Or an electric deionized water production apparatus comprising a plurality of concentration chambers, the following (1) to (3);
(1) Alkaline injection means for injecting an alkaline agent into the flow path of the second small desalting chamber supply water;
(2) salt injection means for injecting salt into the water to be treated containing boron;
(3) Decarbonation means for decarboxylating the water to be treated containing boron, and alkali injection means for injecting an alkaline agent into the flow path of the decarboxylated treatment water,
One or further comprising the Rukoto two or more means, the second manufacturing electrodeionization water, wherein 9.2 or more and a to Rukoto the pH of the feed water to the small depletion chamber selected from apparatus.

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