JPH10272465A - Pure water making apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable recovery and reuse to improve a water recovery rate by mixing an industrial water treating system for decationization treatment and a waste electronic member manufacturing water treating system for deanionization treatment, installing a reverse osmosis membrane separator in a deionization device, and returning the concentrated water thereof to the waste electronic member manufacturing water treating system. SOLUTION: In an industrial water treating system A, after industrial water is subjected to cation exchange treatment in a cation exchange column 1, decarboxylation treatment is made in a decarboxylation column 2. On the other hand, in a waste electronic member manufacturing water treating system B, after waste electronic member manufacturing water and concentrated water of a reverse osmosis(RO) membrane separator 5 are treated in an active carlbon column 3, anion exchange treatment is made in an anion exchange column 4. These acidic and alkaline treated water are mixed and subjected to deionization treatment in the RO membrane separator 5. Concentrated water of the RO separator 5 is mainly anion-concentrated water. Therefore, this concentrated water is subjected to anion exchange treatment in the waste electronic member manufacturing water treating system B, allowing it to have reusable quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pure water producing apparatus for producing pure water using industrial water and electronic component production waste water as raw water.

[0002]

2. Description of the Related Art Ultrapure water used in a process for manufacturing electronic members such as semiconductors and liquid crystal display panels generally includes a primary pure water manufacturing process including membrane separation and ion exchange, ultraviolet oxidation, mixed-bed ion exchange, and the like. It is manufactured through a secondary pure water manufacturing process (also called a subsystem) consisting of ultrafiltration. In such ultrapure water production process, electronic component production wastewater, that is, used ultrapure water discharged from the electronic component production process is collected and supplied as raw water, and in order to compensate for the shortage of raw water,
Industrial water such as tap water, groundwater, and river water is supplied as makeup water.

[0003] In this case, since the water quality of the electronic component production wastewater and the industrial water is different, they are treated in separate treatment steps to obtain primary pure water and then treated in the secondary pure water production step. There is a disadvantage that the processing device and the processing operation are complicated.

That is, when industrial water and wastewater for manufacturing electronic components are mixed, calcium ions and magnesium ions in the industrial water react with fluorine ions in the wastewater for manufacturing electronic components, and colloids such as calcium fluoride are formed. Scale in the separator. When calcium fluoride or the like adheres to the separation membrane, the performance is not easily recovered even by chemical cleaning, and the amount of treated water is reduced, and the adhered substances are gradually eluted, and the quality of treated water is reduced. For this reason, conventionally, industrial water and wastewater for producing electronic components were not mixed, but were treated in separate primary pure water production steps and then fed to a secondary pure water production step.

The inventor of the present invention has previously disclosed a "cation exchange apparatus for decationizing industrial water" as a pure water production apparatus which can solve this problem and mix and treat semiconductor production wastewater and industrial water. An industrial water treatment system, a semiconductor production wastewater treatment system having an anion exchange device for deanionizing semiconductor production wastewater, and a mixing device for mixing the treated water of the industrial water treatment system and the semiconductor production wastewater treatment system to obtain a mixed raw water. And a mixed water treatment system having a deionization device for deionizing the mixed raw water. "
-39871).

[0006] In this pure water production apparatus, industrial water is supplied to an industrial water treatment system, and a cation exchanger is used to remove cations to remove hardness components such as calcium ions. The treated water of the industrial water treatment system thus obtained has a pH of 3.5 to 4.
It becomes acidic water of 5. On the other hand, semiconductor production wastewater is introduced into a semiconductor production wastewater treatment system, and anion exchange treatment is performed with an anion exchange device to remove acids. At this time, fluorine ions are also removed at the same time. The treated water of the semiconductor manufacturing wastewater treatment system thus obtained has a high pH of 9 to 10, and the pH fluctuation width is small. For this reason, by mixing the acidic treated water from which the hardness component has been removed in the industrial water treatment system and the alkaline treated water from which fluorine ions have been removed in the semiconductor manufacturing wastewater treatment system, the pH of the mixture is almost neutral, by a mixing device. As a result, the mixed raw water of No. 7 is obtained, the fluctuation range of the pH is reduced, and the formation of scale such as calcium fluoride is prevented.

[0007] Therefore, by deionizing the mixed water, pure water can be easily produced without problems of scale generation and without or reducing pH control by neutralization.

[0008]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. Hei 7-398.
In the pure water production apparatus described in Japanese Patent Publication No. 71, a reverse osmosis (RO) membrane separation apparatus is considered to be suitable as a deionization apparatus, and the RO membrane separation apparatus is used in the embodiments.
Since the concentrated water of the membrane separation device is discharged out of the system without being recovered, there is a problem that the water recovery rate is limited.

[0009] That is, RO membrane concentration water separation device, water supply are concentrated 4-6 fold (RO membrane treated water separator), scale deposits and slime of SiO ₂ concentration and increase in viable cell count There is a risk of contamination. If this is to be recovered and reused, it is necessary to further increase the processing equipment and to process the concentrated water. For example, an RO membrane separator for treating the concentrated water of the RO membrane separator is provided, and the concentrated water is further treated with the RO membrane separator to remove SiO ₂ and viable bacteria,
Processing such as returning the obtained permeated water to the processing system is required. For this reason, in the pure water production apparatus described in JP-A-7-39871, the concentrated water of the RO membrane separation apparatus is recovered,
It is discharged outside the system without reuse.

The present invention solves the problem of the pure water production apparatus described in Japanese Patent Application Laid-Open No. 7-39871, and improves the water recovery rate by recovering and reusing the concentrated water of the RO membrane separation apparatus. It is an object to provide a pure water production device.

[0011]

The pure water production apparatus of the present invention comprises an industrial water treatment system having a cation exchange device for decationizing industrial water, and an anion exchange device for deanionizing waste water for producing electronic components. An electronic member production wastewater treatment system, and a pure water production apparatus comprising: a deionization device for mixing treated water of the industrial water treatment system and treated water of the electronic member production wastewater treatment system and deionizing the mixed water. ,
The deionization device includes a reverse osmosis membrane separation device, and has means for returning concentrated water of the reverse osmosis membrane separation device to the electronic component manufacturing wastewater treatment system.

Industrial water generally contains anions and cations at approximately the same concentration. Therefore, water obtained by subjecting this industrial water to a cation exchange treatment contains anions. On the other hand, the electronic component production wastewater contains anions, but the proportion of cations is low. Therefore, water obtained by anion exchange of the electronic component production wastewater and water obtained by cation exchange treatment of industrial water are mixed. Is concentrated by an RO membrane, the anion is concentrated water. Therefore, by performing the anion exchange treatment on the concentrated water of the RO membrane separation device in which the anions are concentrated in the electronic member production wastewater treatment system,
Water quality can be increased to reusable.

Further, the anion exchange resin includes SiO ₂
Because of the removal action of and viable bacteria, by which to return the concentrated water of the RO membrane separation apparatus SiO ₂ and viable cells were concentrated to an electronic member manufacturing waste water system is treated with an anion exchange device, the concentrate water SiO ₂ And viable bacteria can be removed. For this reason, it is possible to collect and reuse the concentrated water of the RO membrane separation device while preventing problems such as scale generation and slime contamination without adding a separate concentrated water treatment facility. improves.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of a pure water producing apparatus according to the present invention.

In the industrial water treatment system A, the industrial water is subjected to a cation exchange treatment in the cation exchange tower 1 and then to a decarbonation treatment in the decarbonation tower 2.

As the industrial water, tap water, groundwater,
Water that is generally used as raw water for producing pure water, such as river water, can be used as it is or after being subjected to a pretreatment for SS removal such as a coagulation sedimentation treatment, if necessary. Such industrial water generally contains all cations (T-
C) and all anions (TA) are 100-200 p.
pm-CaCO ₃ each, SiO ₂ 20-30 pp
m.

The cation exchange resin of the cation exchange tower 1 for treating industrial water may be of the Na type, but is preferably of the H type. The H type strongly acidic cation exchange resin or weakly acidic cation exchange resin, preferably neutral salt decomposition A strong acidic cation exchange resin having the ability is used. There are no particular restrictions on the water flow conditions in the cation exchange column 1, but water flow SV = 10-30.
hr- ¹ is preferred.

The effluent from the cation exchange column 1 is then decarbonated in a decarbonation column 2. Although the decarbonation tower 2 is not necessarily required, it is preferable to perform the decarbonation treatment because the water quality can be further improved.

The decarbonation tower 2 may be any device capable of decarbonation, and may be of any type such as a gas-liquid contact type or a vacuum type. In the case of the gas-liquid contact type, the G / L ratio (N-m ³ /
m ³ ) It is preferred to process in the range of 5 to 20.

The treated water of the industrial water treatment system obtained by subjecting the industrial water to the cation exchange treatment and removing the hardness component is usually acidic water having a pH of 3.5 to 4.5.

On the other hand, in the electronic member production wastewater treatment system B, after the electronic member production wastewater and the concentrated water of the RO membrane separation device 5 described below are treated in the activated carbon tower 3, anion exchange treatment is performed in the anion exchange tower 4.

The electronic component manufacturing wastewater is recovered water of used ultrapure water discharged from an electronic component manufacturing process such as a semiconductor manufacturing process or a liquid crystal display panel manufacturing process.
_{-C: 10~30ppm-CaCO 3, T} -A: 100
~ 200 ppm-CaCO ₃ and mineral acid (H ₂ SO ₄ , H
NO ₃ , HCl) and a low proportion of cations.

In the electronic member manufacturing wastewater treatment system B,
The activated carbon tower 3 is not essential, but it is preferable because the activated carbon tower 3 is provided to remove an organic substance and a solid substance so that the anion exchange resin of the anion exchange tower 4 can be protected.

Although the treatment conditions of the activated carbon tower 3 are not particularly limited, it is generally preferable that the water passing SV is about 5 to 20 hr ^-1 .

The effluent from the activated carbon tower 3 is then subjected to an anion exchange treatment in an anion exchange tower 4. This anion exchange tower 4
The anion exchange resin may be an OH type, and may be a weakly basic anion exchange resin such as "MP64" manufactured by Bayer or a strongly basic anion exchange resin such as "MP500" manufactured by Bayer. There are no particular restrictions on the water flow conditions of the anion exchange column 4, but water flow SV = 10-30.
It is preferably about hr ^-1 .

As described above, an electronic member production wastewater treatment system obtained by anion-exchange treatment of the electronic member production wastewater and the concentrated water of the RO membrane separation device 5 (hereinafter sometimes referred to as “recycled concentrated water”) in the subsequent step. The treated water is usually pH 8.
5-10 alkaline water.

The acidic treated water from the industrial water treatment system A and the alkaline treated water from the electronic component manufacturing wastewater treatment system B are mixed and deionized by the RO membrane separation apparatus 5. The pH of the feed water of the RO membrane separation device 5 is not particularly limited, but may be pH 7-9.
Therefore, if the pH of the mixed water of the industrial water treatment water and the electronic component production wastewater treatment is outside this range, an acid or alkali pH adjuster may be added as necessary to adjust the pH. Adjustment is preferred.

The type of the RO membrane of the RO membrane separation apparatus 5 is not particularly limited, and any type of membrane such as a spiral type, a tubular type, and a hollow fiber type can be used.

The permeated water of the RO membrane separation device 5 is discharged out of the system as treated water (pure water), sent to a secondary pure water production step, and subjected to further advanced treatment.

On the other hand, the concentrated water is returned to the electronic component production wastewater treatment system B, and is treated in the activated carbon tower 3 and the anion exchange tower 4 together with the electronic component production wastewater.

The concentrated water of the RO membrane separation device 5 is an industrial water treatment water obtained by removing cations from industrial water containing cations and anions, and an electron water obtained by removing anions from an electronic member production wastewater containing anions and containing almost no cations. Since it is obtained by condensing water mixed with component manufacturing wastewater treatment water with an RO membrane, the water is mainly anion-concentrated water. Therefore, the concentrated water is subjected to anion exchange treatment in the electronic component manufacturing wastewater treatment system B, whereby the water quality can be made reusable. Moreover, the anion exchange resin contains S
Since it also has an action of removing iO ₂ and viable bacteria, scale concentration and slime contamination due to their concentration are prevented.

In the present invention, if the ratio of the concentrated water of the RO membrane separation device 5 returned to the wastewater treatment system B for manufacturing electronic components is too large, problems such as deterioration of treated water quality, scale formation, and slime contamination will occur. . Therefore, the ratio of the concentrated water returned to the electronic component production wastewater treatment system B is 50% of the total amount of the electronic component production wastewater and the return concentrated water introduced into the electronic component production wastewater treatment system B. % Is preferable. Therefore, when the amount of concentrated water generated is large relative to the amount of wastewater for manufacturing electronic components, a part of the concentrated water is returned and the remaining part is discharged out of the system.

FIG. 1 shows an example of an embodiment of the present invention, and the present invention is not limited to the illustrated method.

For example, it is also effective to increase the quality of treated water by arranging two or more RO membrane separators in series as a deionizer and performing a multi-stage RO membrane separation process. Further, an MF (microfiltration) membrane separator or a UF (ultrafiltration) membrane separator may be provided in a stage preceding the RO membrane separator, or an ion exchanger may be provided in a stage subsequent to the RO membrane separator. Further, a mixing tank for mixing the treated water of the industrial water treatment system A and the treated water of the electronic member production wastewater treatment system B, or a mixing tank for mixing the electronic member production wastewater and the return concentrated water may be provided.

[0036]

The present invention will be described more specifically below with reference to examples and comparative examples.

For convenience of explanation, a comparative example will be described first.

Comparative Example 1 Pure water was produced by the pure water production apparatus shown in FIG. 1 (however, the concentrated water was not returned to the RO membrane separation apparatus, and the entire concentrated water was discharged outside the system). .).

In the industrial water treatment system, Atsugi-shi water is first passed through a cation exchange tower (filled with 30 L of H-type strongly acidic cation exchange resin “SP112” manufactured by Bayer) at 500 L / hr (SV = 17 hr ^−1). ), G / L ratio 2 in the decarbonation tower 2
At 0, the mixture was brought into countercurrent contact with air for decarboxylation. The quality of the obtained industrial water treatment water is as shown in Table 1.

On the other hand, in the electronic member manufacturing wastewater treatment system, HF, HNO ₃ , H ₂ S is added to pure water by simulating semiconductor manufacturing wastewater.
Water to which O ₄ , NaOH and NH ₄ F are added (pH = 3.
5-4, TC = 10 ppm-CaCO ₃ , TA = 1
00 ppm-CaCO ₃ ) in an activated carbon tower (filled with 30 L of activated carbon) 3 and an anion exchange tower (OH type weakly basic anion exchange resin “Diaion WA-30” 20 L, manufactured by Mitsubishi Chemical Corporation)
(Activated carbon tower 3 = SV)
17 hr ^-1 , water flow SV of the anion exchange column 4 = 25 h
r ^-1 ). The quality of the obtained electronic component manufacturing wastewater is shown in Table 1.
As shown in FIG.

The treated water for industrial use and the treated water for producing electronic components were mixed at the same volume ratio (the pH of the mixed water was 7.1).
The treatment was performed by the RO membrane separation apparatus 5. The RO membrane separation device 5 includes a low-pressure RO membrane “NTR-759HR” 4 manufactured by Nitto Denko Corporation.
Water was supplied at a feed pressure of 15 kg / cm ² using a series of three inches, and RO membrane separation treatment was performed at a water recovery rate of 80%, and the concentrated water was discharged out of the system.

Water quality and permeated water (pure water) of the obtained concentrated water
Was as shown in Table 2.

Example 1 In Comparative Example 1, 3/4 of the concentrated water of the RO membrane separation device 5, that is, 15% of the feed water of the RO membrane separation device 5,
Was returned to the inlet side of the activated carbon tower 3 of the electronic member production wastewater treatment system A, and the same treatment was performed except that only the remaining 5% was discharged outside the system.

In this embodiment, in the RO membrane separation apparatus 5, permeated water is obtained at a water recovery rate of 80%, and a portion corresponding to 15% of the feedwater of the concentrated water is recovered and reused. The recovery rate is 95%.

The water quality of the industrial water treatment water and the electronic component production wastewater treatment water, the quality of the concentrated water obtained by the RO membrane separator, and the conductivity of the permeated water (pure water) are as shown in Tables 1 and 2.
According to the present invention, it can be seen that the water recovery rate can be increased by merely providing a concentrated water return line without lowering the quality of pure water and without increasing the number of treatment facilities.

In Example 1, the operation was continued for 20 days, but there was no problem of scale formation or slime contamination.

[0047]

[Table 1]

[0048]

[Table 2]

Comparative Example 2 The same treatment as in Example 1 was carried out except that the concentrated water of the RO membrane separator 5 was directly returned to the inlet side of the RO membrane separator 5, and the results shown in Table 1 were obtained. The conductivity of the permeated water (pure water) of the RO membrane separation apparatus was 4 to 5 μS / cm, but after 15 days of operation, scale separation was impossible due to scale formation.

COMPARATIVE EXAMPLE 3 In Comparative Example 2, an additional RO membrane separation device (the low-pressure RO membrane) was additionally provided.
Was processed in the same manner except that the permeated water obtained by treating the concentrated water of the above with the newly provided RO membrane separation apparatus was returned. The conductivity of the obtained permeated water (pure water) was 1 to 2 μm.
/ Cm, and there was no operation trouble due to scale or the like, but in this comparative example, there was a problem of cost for adding and operating the RO membrane separation device.

[0051]

As described above in detail, according to the pure water production apparatus of the present invention, the concentrated water of the RO membrane separation apparatus for the deionization treatment can be used without requiring additional treatment equipment. , Without reducing the quality and quantity of treated water,
Can be reused. For this reason, the water recovery rate is improved, and the cost of ultrapure water used in large quantities in the electronic component manufacturing field can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of a pure water production apparatus of the present invention.

[Explanation of symbols]

 A Industrial water treatment system B Electronic component production wastewater treatment system 1 Cation exchange tower 2 Decarbonation tower 3 Activated carbon tower 4 Anion exchange tower 5 RO membrane separation device

Claims (1)

[Claims] 1. An industrial water treatment system including a cation exchange device for decationizing industrial water, an electronic member production wastewater treatment system including an anion exchange device for deionizing an electronic member production wastewater, and the industrial water treatment system A deionization apparatus for mixing the treated water with the treated water of an electronic component production wastewater treatment system and deionizing the mixed water, wherein the deionization apparatus includes a reverse osmosis membrane separation apparatus. And a means for returning the concentrated water of the reverse osmosis membrane separation device to the wastewater treatment system for manufacturing electronic components.