JP2014000575A - Apparatus and method for producing purified water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing purified water capable of efficiently producing a purified water having a low boron concentration.SOLUTION: There is provided an ultrapure water producing apparatus which comprises: an activated carbon device 1; a heater 2; a membrane type filtration device 3; a raw water tank 4; a pretreatment device 5; an electrically deionizing device 6; and a subtank 7 for primary purified water. Further, the pretreatment device 5 comprises: a first reverse osmosis membrane (RO) device 8; a second reverse osmosis membrane (RO) device 9; and a decarbonation membrane device 10. The pretreatment device 5 is designed so that treated water W1 having a chloride ion concentration of 100 ppb or less may be introduced into a desalination chamber in the electrically deionizing device 6 according to water quality of raw water W0.

Description

  The present invention relates to a pure water production apparatus suitable for incorporation into an ultrapure water production system or the like, and more particularly to a pure water production apparatus for producing pure water having a low boron concentration. The present invention also relates to a pure water production method suitable for an ultrapure water production system or the like, and more particularly to a pure water production method for producing pure water having a low boron concentration.

  The ultrapure water production system is generally composed of a pretreatment system, a primary pure water system, and a subsystem. The pretreatment system is composed of a turbidity treatment device such as coagulation filtration, MF membrane (microfiltration membrane), UF membrane (ultrafiltration membrane), etc., and a dechlorination treatment device such as activated carbon.

  The primary pure water system is composed of an RO (reverse osmosis membrane) device, a degassing membrane device, an electrodeionization device, and the like, and most of ionic components and TOC components are removed. In addition, the subsystem is composed of a UV device (ultraviolet oxidation device), a non-regenerative ion exchange device, a UF device (ultrafiltration device), etc., and removes trace ions, particularly low-molecular trace organic substances, and particulates. Removal is performed. In general, the ultrapure water produced by this subsystem is sent to the point of use, and the excess ultrapure water is generally returned to the tank in the previous stage of the subsystem.

  By the way, the required water quality of ultrapure water becomes stricter year by year, and ultrapure water having a boron concentration of 10 ppt or less is now required in the state-of-the-art electronics industry. This boron exists almost as borate ions in ultrapure water, but these borate ions are weak ions and are difficult to remove. Therefore, in order to produce pure water with a low boron concentration, it has been proposed to improve the boron removal rate in the RO device by setting the water supply of the RO device to pH 10 or higher (see Patent Document 1).

  Also, the treated water after pretreatment is brought into contact with a boron-selective ion exchange resin (see Patent Document 2), and the raw water is desalted with a desalinator such as an RO device and then passed through a boron adsorption resin tower. Has been proposed (see Patent Document 3).

Furthermore, an ultrapure water production apparatus has been proposed in which treated water obtained by passing raw water through a pretreatment device, a two-stage RO device, an electric regenerative desalination device, etc. is brought into contact with a boron-selective ion exchange resin (Patent Literature). 4).
Japanese Patent No. 3321179 Japanese Patent No. 3200301 JP-A-8-89956 JP-A-9-192661

  In the pure water production method described in Patent Document 1, it is necessary to use an alkali or to provide an anion exchange resin tower in order to adjust the feed water of the RO device to pH 10 or higher, which increases chemical costs or equipment load. However, there is a problem that continuous operation is not possible.

  Moreover, although the pure water manufacturing method described in patent documents 2-4 distribute | circulates treated water to boron selective ion exchange resin or boron adsorption resin, it removes boron, When the concentration is high, these boron adsorbing resins and the like break through in a short period of time, while the removal rate decreases when the boron concentration of the water to be treated is low, for example, about 10 ppb or less. is there. Further, since there is a risk of TOC elution from the boron adsorption resin, there is a problem that the boron adsorption resin needs to be cleaned and conditioned.

  Furthermore, it is conceivable to remove borate ions, which are anions, simultaneously with an electrodeionization device. However, since borate ions are weak ions, they can also be removed by increasing the current density of the electrodeionization device. It is difficult to make the rate 90% or more. Moreover, even if the RO device is combined, the boron removal rate cannot be increased to 98% or more.

  That is, in recent years, the required water quality of ultrapure water has become stricter year by year, and even though the water concentration of boron concentration of 100 ppt or less, the boron concentration of 10 ppt or less, and in some cases 1 ppt or less is required in the state-of-the-art electronics industry, There was no pure water production system that could achieve this with a structure. In order to achieve this in the electrodeionization apparatus, at least the boron removal rate in the electrodeionization apparatus needs to be 99% or more, particularly 99.5% or more.

  This invention is made | formed in view of the said subject, and it aims at providing the pure water manufacturing apparatus which can manufacture the pure water with a low boron concentration efficiently. Moreover, an object of this invention is to provide the pure water manufacturing method which can manufacture the pure water with a low boron concentration efficiently.

  In order to solve the above-mentioned problems, firstly, the present invention provides a pure water production apparatus having a pretreatment device and an electrodeionization device that receives treatment water of the pretreatment device in a demineralization chamber and performs deionization treatment. And the said pre-processing apparatus provides the pure water manufacturing apparatus characterized by making the chloride ion density | concentration of the treated water introduce | transduced into the demineralization chamber of the said electrodeionization apparatus into 100 ppb or less (invention 1). .

  According to the above invention (Invention 1), chloride ions are easier to remove than boron, and the electrode ionization device can be obtained by reducing the chloride ion concentration of treated water introduced into the electrodeionization device to 100 ppb or less. The removal rate of boron can be significantly improved to 99% or more.

  In the said invention (invention 1), the said pre-processing apparatus is equipped with 1 or 2 or more RO membrane apparatuses, and the carbonic acid concentration of the treated water introduced into the demineralization chamber of the said electrodeionization apparatus shall be 1 ppm or less. Preferably (Invention 2), in the invention (Invention 2), the pretreatment apparatus preferably further comprises one or more ion exchange resin towers. In the invention (Invention 3), the pretreatment apparatus However, it is preferable to further comprise a decarbonation membrane device, a decarbonation tower or a vacuum degassing tower (Invention 4).

  According to the said invention (invention 2-4), the chloride ion density | concentration and carbonate ion density | concentration of the treated water introduce | transduced into the demineralization chamber of an electrodeionization apparatus can further be reduced, The removal rate can be further improved.

  In the said invention (invention 1-4), a part of demineralized water of the said electrodeionization apparatus is introduce | transduced into the concentration chamber of the said electrodeionization apparatus from the opposite direction to the introduction direction of the treated water to the said demineralization chamber. (Invention 5)

  According to the above invention (Invention 5), the drainage water (desalted water) of the desalting chamber with good water quality is circulated from the outlet side of the desalting chamber toward the inlet side to the concentration chamber, whereby the desalting chamber Since the concentration gradient of boron between the concentration chamber and the concentration chamber is relaxed, the boron removal rate in the electrodeionization apparatus can be further improved.

  In the said invention (invention 1-5), it is preferable that the said electrodeionization apparatus is provided in multiple stages in series (invention 6). According to this invention (Invention 6), since the removal rate of boron can be increased to 99.99%, ultrapure water having a boron ion concentration of 1 ppt or less can be supplied.

  Secondly, the present invention is a method for producing pure water in which raw water is treated with a pretreatment device, and the treated water is introduced into a demineralization chamber of an electrodeionization device to perform deionization treatment, the pretreatment device A pure water production method is provided in which treated water having a chloride ion concentration of 100 ppb or less is introduced into a demineralization chamber of the electrodeionization apparatus (Invention 7).

  According to the above invention (Invention 7), chloride ions are easier to remove than boron, and the concentration of chloride ions in the treated water to be introduced into the electrodeionization is 100 ppb or less. The removal rate of boron can be greatly improved to 99% or more.

  In the above invention (Invention 7), a portion of the deionized water of the electrodeionization device is introduced into the concentration chamber of the electrodeionization device from the direction opposite to the direction of introduction of treated water into the demineralization chamber. Preferred (Invention 8).

  According to the above invention (Invention 8), the drainage water (demineralized water) of the desalting chamber with good water quality is circulated from the outlet side of the desalting chamber toward the inlet side to the concentrating chamber. Since the concentration gradient of boron between the concentration chamber and the concentration chamber is relaxed, the boron removal rate in the electrodeionization apparatus can be further improved.

  In the said invention (invention 7 and 8), it is preferable that the said electrodeionization apparatus is provided in multiple stages in series (invention 9). According to this invention (Invention 9), since the removal rate of boron can be increased to 99.99%, ultrapure water having a boron ion concentration of 1 ppt or less can be supplied.

  In the said invention (invention 9), the concentrated water of the last-stage electrodeionization apparatus is introduce | transduced into the demineralization chamber of the first-stage electrodeionization apparatus with the said treated water among the said multiple-stage electrodeionization apparatuses. (Invention 10)

  According to the above invention (Invention 10), the concentrated water of the last electrodeionization device not only has a lower boron concentration than the treated water after being treated by the pretreatment device, but also has a significantly lower chloride ion concentration. By introducing this into the demineralization chamber of the first-stage electrodeionization apparatus, the boron concentration of the treated water from the demineralization chamber of the first-stage electrodeionization apparatus is further improved while maintaining the basic configuration of the apparatus. can do.

  According to the pure water production apparatus of the present invention, chloride ions are easier to remove than boron, and the electrode ionization apparatus can be obtained by reducing the chloride ion concentration of treated water introduced into the electrodeionization apparatus to 100 ppb or less. The removal rate of boron can be significantly improved to 99% or more. According to the present invention, since boron can be removed greatly by the electrodeionization apparatus, not only continuous operation is possible, but also chemicals such as alkali are not used, so there is little environmental load and boron in feed water (raw water) It is possible to deal with a wide concentration range. Further, since breakthrough does not occur as compared with boron adsorption resin or the like, pure water having a low boron concentration can be stably supplied for several years. Moreover, by providing a plurality of electrodeionization devices in series, ultrapure water having a boron ion concentration of 1 ppt or less can be supplied.

[First embodiment]
Hereinafter, a first embodiment of a pure water production apparatus of the present invention will be described in detail based on the drawings.
FIG. 1 is a flowchart showing a pure water production apparatus according to the present embodiment, and FIG. 2 is a schematic configuration diagram showing an electrodeionization apparatus according to the present embodiment.

  As shown in FIG. 1, the ultrapure water production apparatus includes an activated carbon device 1, a heater 2, a membrane filtration device 3, a raw water tank 4, a pretreatment device 5, an electrodeionization device 6, and a primary pure water. And a sub-tank 7 for water. In this embodiment, the pretreatment device 5 includes a first reverse osmosis membrane (RO) device 8, a second reverse osmosis membrane (RO) device 9, and a decarbonation membrane device 10. Yes. This pretreatment device 5 is designed such that treated water W1 having a chloride ion concentration of 100 ppb or less is introduced into the demineralization chamber of the electrodeionization device 6 according to the quality of the raw water W0.

  In the ultrapure water production apparatus as described above, the electrodeionization apparatus 6 includes a demineralization chamber 11 and a concentration chamber 12 as shown in FIG. 2, and the demineralization chamber 11 includes treated water of the pretreatment device 5. While the flow path R1 of W1 is connected, the outlet side of the desalting chamber 11 is a flow path R2 of demineralized water W2. A branch channel R3 branches from this channel R2, and a portion of the desalted water W2 in the desalting chamber 11 is introduced into the concentration chamber 12 from the outlet side of the desalting chamber 11 toward the inlet side. That is, it is the structure which introduce | transduces into the concentration chamber 12 from the direction opposite to the distribution direction of the treated water W1 in the desalination chamber 11, and discharges the concentrated water W3.

The effect | action is demonstrated about the ultrapure water manufacturing apparatus which has such a structure.
First, after removing organic matter from the raw water W0 in the activated carbon device 1 and then heating up to a predetermined temperature in the heater 2, the solid fine particles are removed by the membrane filtration device 3 and temporarily stored in the raw water tank 4. Subsequently, the raw water W0 is treated by the pretreatment device 5.

In the pretreatment device 5, strong ionic impurities are removed by the first reverse osmosis membrane (RO) device 8 and the second reverse osmosis membrane (RO) device 9, and further, by the decarbonation membrane device 10. Carbonate ions (CO ₂ ) are removed.

  The pretreatment device 5 is designed so that the chloride ion concentration in the treated water W1 is 100 ppb or less, preferably 50 ppb or less, particularly preferably 30 ppb or less. If the chloride ion concentration in the treated water W1 exceeds 100 ppb, the boron removal rate in the subsequent electrodeionization apparatus 6 cannot be made 99% or more.

Moreover, CO ₂ concentration in the treated water W1 is preferably set to 1ppm or less. If the CO ₂ concentration in the treated water W1 exceeds 1 ppm, the boron removal rate may decrease to less than 99%, and in some cases to less than 90%.

And such treated water W1 is processed with the electrodeionization apparatus 6. FIG. The electrodeionization apparatus 6 is preferably operated at a current density of 300 mA / dm ² or more. By operating at such a current density, although depending on the performance of the electrodeionization apparatus, a boron removal rate of 99% or more, particularly 99.5% or more, which could not be achieved by the conventional electrodeionization apparatus. be able to.

  Thus, according to the pure water manufacturing apparatus which concerns on this embodiment, if the boron concentration of the treated water W1 is 10 ppb or less, the desalted water W2 with a boron concentration of 100 ppt or less can be obtained reliably. Further, if the boron removal rate of the pure water producing apparatus according to the present embodiment is 99.5%, the treated water W1 has a boron concentration of 20 ppb, and if the boron removal rate is 99.8% or more, the treated water W1. The demineralized water W2 having a boron concentration of 50 ppb and a boron concentration of 100 ppt or less can be obtained. In addition, since the boron can be sufficiently removed by the electrodeionization apparatus 6, not only continuous operation is possible, but also no chemical such as alkali is used, so the environmental load is small. Moreover, it can handle a wide range of boron concentrations in the feed water (raw water) and does not cause breakthrough compared to boron-adsorbing resins, etc., so it can supply pure water with a low boron concentration stably for several years. It becomes possible.

[Second Embodiment]
Next, 2nd embodiment of the pure water manufacturing apparatus of this invention is described based on FIG.
FIG. 3 is a flowchart showing the pure water production apparatus according to the second embodiment.

  In the pure water production apparatus according to the second embodiment, the electrodeionization apparatus is connected in series with the first electrodeionization apparatus 6A and the second electrodeionization apparatus 6B in the first embodiment described above. It has the same configuration except that the concentrated water W3 of the second electrodeionization device 6B is returned to the treated water tank T provided in the previous stage of the first electrodeionization device 6A.

The effect | action is demonstrated about the ultrapure water manufacturing apparatus which has such a structure.
First, the raw water W0 is subjected to organic substance removal treatment with the activated carbon device 1 and then heated to a predetermined temperature with the heater 2, and then the solid particulates are removed with the membrane filtration device 3 into the raw water tank 4. Once stored. Then, the raw water W0 is treated by the pretreatment device 5.

In the pretreatment device 5, strong ionic impurities are removed by the first reverse osmosis membrane (RO) device 8 and the second reverse osmosis membrane (RO) device 9, and further, by the decarbonation membrane device 10. Carbonate ions (CO ₂ ) are removed.

  The pretreatment device 5 is designed so that the chloride ion concentration in the treated water W1 is 100 ppb or less, preferably 50 ppb or less, particularly preferably 30 ppb or less. If the chloride ion concentration in the treated water W1 exceeds 100 ppb, the boron removal rate in the subsequent electrodeionization apparatus 6A cannot be 99% or more.

  Then, such treated water W1 is continuously treated by the first electrodeionization device 6A and the second electrodeionization device 6B, and the concentrated water W3 is provided upstream of the first electrodeionization device 6A. Return to the treated water tank T.

The electrodeionization devices 6A and 6B are preferably operated at a current density of 300 mA / dm ² or more. A current density of less than 300 mA / dm ² is not preferable because the boron removal rate is less than 99%. Specifically, 99% or more of boron is removed in the first electrodeionization apparatus 6A, and 99% or more of boron is further removed in the second electrodeionization apparatus 6B.

  In particular, in the present embodiment, the concentrated water W3 of the second electrodeionization apparatus 6B is returned to the treated water tank T provided in the front stage of the first electrodeionization apparatus 6A, and the concentrated water W3 is Since the boron concentration is lower than that of the treated water W1, the chloride ion concentration and the boron concentration are further lowered in the treated water tank T over the treated water W1 over time, so that ultrapure water having a boron concentration of 1 ppt or less is obtained. Is also possible.

  As mentioned above, although the pure water manufacturing system which concerns on this embodiment has been demonstrated based on drawing, this invention is not limited to the said embodiment, A various change implementation is possible.

  For example, the pretreatment device 5 can supply treated water W1 having a chloride ion concentration of 100 ppb or less to the electrodeionization device 6 and can obtain pure water having a desired boron concentration according to the quality of the raw water W0. Various settings can be made.

Specifically, the pretreatment device 5 is (1) RO device + decarbonation membrane device (2) first RO device + second RO device + decarbonation membrane device (3) ion exchange resin device (2B3T) + RO. Device + decarbonation membrane device (4) ion exchange resin device (4B5T) + RO device + decarbonation membrane device.

  In addition, the electrodeionization device 6 may be a single stage, or two or more stages may be provided in series. If three or more stages are provided, the final stage of the electrodeionization apparatus 6 The concentrated water W3 may be merged with the treated water W1 of the first stage electrodeionization apparatus.

  Furthermore, although there is no restriction | limiting in particular as the electrodeionization apparatus 6, What provided the hexagonal member which does not permeate | transmit water on a vertical side surface but permeate | transmits a slope can be used suitably.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
In the examples and comparative examples, the following test apparatus was used.
・ Electrodeionization equipment (Kurita Kogyo Co., Ltd., product name: KCDI-UPz-150H, amount of treated water: 150 m ³ / hr)
・ Reverse osmosis membrane device (Nitto Denko, product name: ES-20)
Decarbonation membrane device (Rixel, product name: X-50)

[Example 1]
As shown in FIGS. 1 and 2, the pretreatment device 5 includes a first reverse osmosis membrane (RO) device 8, a second reverse osmosis membrane (RO) device 9, and a decarbonation membrane device 10. The electrodeionization apparatus 6 was arranged in one stage to manufacture a pure water production apparatus.

When the raw water W0 having a boron concentration of 25 ppb, a chloride ion concentration of 11000 ppb, and a CO ₂ concentration of 8 ppm was treated with this pure water production apparatus, the boron concentration of the treated water W1 of the pretreatment apparatus 5 was 25 ppb and the chloride ion concentration Was 10 ppb and the CO ₂ concentration was 1 ppm or less.

The result of processing the treated water W1 in electrodeionization apparatus 6, the boron concentration is 50 ppt, the chloride ion concentration is 0.5ppb or less, CO ₂ concentration is less demineralized water W2 0.01 ppm was obtained. At this time, the boron removal rate in the electrodeionization apparatus 6 was 99.8%.

[Comparative Example 1]
As shown in FIG. 4, in Example 1, the pure water manufacturing apparatus was manufactured by the same apparatus structure except having the reverse osmosis membrane (RO) apparatus in one stage structure.

When the same raw water W0 as that in Example 1 was treated with this pure water production apparatus, the boron concentration of the treated water W1 of the pretreatment apparatus 5 was 25 ppb, the chloride ion concentration was 150 ppb, and the CO ₂ concentration was 1 ppm or less.

The result of processing the treated water W1 in electrodeionization apparatus 6, the boron concentration is 500 ppt, the chloride ion concentration is 0.5ppb or less, CO ₂ concentration is less demineralized water W2 0.01 ppm was obtained. At this time, the boron removal rate in the electrodeionization apparatus 6 was 98%.

[Comparative Example 2]
In Example 1, when the treatment was performed in the same manner except that sodium chloride was added to the treated water W1 to change the chloride ion concentration of the treated water W1 of the pretreatment device 5 to 150 ppb, the boron concentration was 400 ppt, the chloride Desalted water W2 having an ion concentration of 0.5 ppb or less and a CO ₂ concentration of 0.01 ppm or less was obtained. The boron removal rate in the electrodeionization apparatus 6 was 98.4%.

[Example 2]
As shown in FIG. 3, the pretreatment device 5 includes a first reverse osmosis membrane (RO) device 8, a second reverse osmosis membrane (RO) device 9, and a decarbonation membrane device 10. The ion apparatus is arranged in series in two stages of 6A and 6B, and the concentrated water W3 of the second electrodeionization apparatus 6B is returned to the treated water tank T provided in the front stage of the first electrodeionization apparatus 6A. A pure water manufacturing apparatus was manufactured as a configuration.

When the raw water W0 having a boron concentration of 25 ppb, a chloride ion concentration of 11000 ppb, and a CO ₂ concentration of 8 ppm was treated with this pure water production apparatus, the boron concentration of the treated water W1 of the pretreatment apparatus 5 was 25 ppb and the chloride ion concentration Was 30 ppb and the CO ₂ concentration was 1 ppm or less.

As a result of continuously treating the treated water W1 with the electrodeionization devices 6A and 6B, the boron concentration of the treated water in the treated water tank T is 20 ppb, the chloride ion concentration is 24 ppb, and CO ₂ after 15 hours. The concentration is 0.6 ppm, the boron concentration of the demineralized water of the first-stage electrodeionization device 6A is 40 ppt, the chloride ion concentration is 0.5 ppb or less, the CO ₂ concentration is 0.01 ppm or less, The boron removal rate in the apparatus 6A was 99.8%. Furthermore, the boron concentration of the demineralized water of the second-stage electrodeionization apparatus 6B is 0.4 ppt, the chloride ion concentration is 0.5 ppb or less, and the CO ₂ concentration is 0.01 ppm or less. The removal rate was 99%.

[Comparative Example 3]
In Example 2, treatment was performed in the same manner except that sodium chloride was added to the treated water tank T so that the chloride ion concentration of the treated water W1 of the electrodeionization apparatus 6 was 150 ppb. The boron concentration of the deionized water of the ion device 6A is 400 ppt, the chloride ion concentration is 0.5 ppb or less, the CO ₂ concentration is 0.01 ppm or less, and the boron removal rate in the first electrodeionization device 6A is 98%. there were. In addition, the boron concentration of the demineralized water of the second electrodeionization apparatus 6B is 2 ppt, the chloride ion concentration is 0.5 ppb or less, and the CO ₂ concentration is 0.01 ppm or less. The boron removal rate was 99.5%.

It is a flowchart which shows the pure water manufacturing apparatus which concerns on 1st embodiment of this invention. It is a schematic block diagram which shows the demineralization chamber and the concentration chamber of the electrodeionization apparatus of the said embodiment. It is a flowchart which shows the pure water manufacturing apparatus which concerns on 2nd embodiment of this invention. It is a flowchart which shows the pure water manufacturing apparatus of the comparative example 1.

5 ... Pretreatment device 6 ... Electrodeionization device 6A ... First electrodeionization device 6B ... Second electrodeionization device 8 ... First reverse osmosis membrane (RO) device (pretreatment device)
9. Second reverse osmosis membrane (RO) device (pretreatment device)
10. Decarbonation membrane device (pretreatment device)
11 ... Desalination chamber 12 ... Concentration chamber W3 ... Concentrated water T ... Treated water tank

Claims (10)

A deionized water production apparatus comprising: a pretreatment device; and an electrodeionization device that performs deionization treatment by receiving treated water from the pretreatment device in a demineralization chamber,
An apparatus for producing pure water, wherein the pretreatment device makes a chloride ion concentration of treated water introduced into a demineralization chamber of the electrodeionization device to 100 ppb or less.   The said pre-processing apparatus is provided with 1 or 2 or more RO membrane apparatus, The carbonic acid concentration of the treated water introduced into the demineralization chamber of the said electrodeionization apparatus shall be 1 ppm or less. Pure water production equipment.   The pure water production apparatus according to claim 2, wherein the pretreatment apparatus further includes one or more ion exchange resin towers.   The pure water production apparatus according to claim 3, wherein the pretreatment device further includes a decarbonation membrane device, a decarbonation tower, or a vacuum degassing tower.   The part of the demineralized water of the electrodeionization apparatus is introduced into the concentration chamber of the electrodeionization apparatus from a direction opposite to the introduction direction of the treated water into the demineralization chamber. The pure water manufacturing apparatus in any one.   The pure water production apparatus according to claim 1, wherein the electrodeionization apparatus is provided in a plurality of stages in series. A method for producing pure water, in which raw water is treated with a pretreatment device, and the treated water is introduced into a demineralization chamber of an electrodeionization device to perform deionization treatment,
A pure water production method, wherein treated water having a chloride ion concentration of 100 ppb or less in the pretreatment device is introduced into a demineralization chamber of the electrodeionization device.   The part of the demineralized water of the electrodeionization apparatus is introduced into the concentration chamber of the electrodeionization apparatus from a direction opposite to the direction of introduction of treated water into the demineralization chamber. A method for producing pure water.   The method for producing pure water according to claim 7 or 8, wherein the electrodeionization apparatus is provided in a plurality of stages in series.   The concentrated water of the last-stage electrodeionization device among the plurality of-stage electrodeionization devices is introduced into the demineralization chamber of the first-stage electrodeionization device together with the treated water. The manufacturing method of the pure water of description.

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