JP3543435B2 - Ultrapure water production method - Google Patents

Description

【００４２】
実施例５，６
原水を凝集・浮上・濾過処理した後、ＡＣ→Ｈ_１→Ｏ_３吸収塔→ＵＶ装置→Ｄ_ｅｃａ→ＯＨ_１に順次通水して処理した。なお、ＡＣ処理水のＴＯＣは３５０ｐｐｂであり、Ｏ_３吸収塔の流入水（Ｈ_１処理水）のｐＨ及びＴＯＣは表２に示す通りであった。
【００４３】
Ｏ_３吸収塔におけるＯ_３注入濃度及びＵＶ装置におけるＵＶ出力を表２に示す値とし、ＯＨ_１流出水のＴＯＣを調べ、結果を表２に示した。
【００４４】
比較例４
原水を凝集・浮上・濾過処理した後、ＡＣ→２Ｂ３Ｔ→Ｏ_３吸収塔→ＵＶ装置→ＭＢに順次通水して処理した。なお、ＡＣ処理水のＴＯＣは３５０ｐｐｂであり、Ｏ_３吸収塔の流入水（２Ｂ３Ｔ処理水）のｐＨ及びＴＯＣは表２に示す通りであった。
【００４５】
Ｏ_３吸収塔におけるＯ_３注入濃度及びＵＶ装置におけるＵＶ出力を表２に示す値とし、ＭＢ流出水のＴＯＣを調べ、結果を表２に示した。
【００４６】
【表２】

【００４７】
表１，２より、本発明によれば、Ｏ_３注入及びＵＶ照射によるＴＯＣ低減濃度を、従来に比べてほぼ半減させることができることが明らかである。
【００４８】
【発明の効果】
以上詳述した通り、本発明の超純水の製造方法によれば、ＴＯＣを効率的に分解除去して、極めて高純度な超純水を製造することができる。
【図面の簡単な説明】
【図１】本発明の超純水の製造方法の一実施例を示す一次純水製造装置の系統図である。
【図２】本発明の超純水の製造方法の他の実施例を示す一次純水製造装置の系統図である。
【図３】超純水製造装置の構成を示す系統図である。
【図４】従来の一次純水製造装置を示す系統図である。
【図５】従来の一次純水製造装置を示す系統図である。
【符号の説明】
１ 前処理装置
２ 一次純水製造装置
３ 二次純水製造装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic industry, ultrapure water used in pharmaceutical industry such as production how, in particular, TOC is significantly lower, about the how it is possible to produce a very high purity ultra-pure water.
[0002]
[Prior art]
In the electronics industry that produces ultra-high-density integrated circuits (ultra-LSIs), extremely high-purity pure water is used for cleaning semiconductor products in each manufacturing process. In particular, with the change in the degree of integration of LSIs in recent years, the required quality of pure water used for cleaning has become more and more severe, and reduction of TOC, viable bacteria, and dissolved oxygen (DO) has become a major issue.
[0003]
Conventionally, ultrapure water used for such purposes is made of industrial water, city water, well water, and the like, and is subjected to gravity such as coagulation sedimentation and coagulation floating for removing suspended substances and colloidal substances in the raw water. A pretreatment device combining any number of separation devices, filtration devices using sand, membranes, etc., activated carbon adsorption towers, etc., and ion exchange devices and reverse osmosis membrane separation devices for removing ions and salts in pretreatment water, and underwater Primary deionized water production equipment combining any number of decarbonation towers and deaerators that remove gaseous components such as carbon dioxide and DO, oxidizers and heaters that decompose organic matter, and primary deionized water and use points A secondary pure water production system (subsystem) combining any number of ultraviolet irradiation equipment, mixed-bed pure water equipment, and ultrafiltration membrane separation equipment for further purifying and sterilizing the returned water. Manufactured with ultrapure water production equipment To have.
[0004]
As a means for reducing the TOC of the obtained ultrapure water in such an ultrapure water production apparatus, ozone (O ₃ ) is injected into the water to be treated in the primary pure water production apparatus to emit ultraviolet (UV) light. A means for irradiating the water is known, and a specific apparatus configuration includes a pretreatment apparatus 1, a primary pure water production apparatus 2, and a secondary pure water production apparatus 3 shown in FIG. 2 employs an ultrapure water production apparatus having the configuration shown in FIG. 4 or FIG.
[0005]
[Problems to be solved by the invention]
According to the conventional _{O 3} injection and UV radiation, although it is possible to reduce the TOC, the pretreated water of about TOC50～70ppb, a limit to reduce to about 20ppb as primary pure water, sufficient TOC reduction No effect has been obtained. In particular, there was a disadvantage that the TOC decomposition efficiency was low with respect to the amount of O ₃ injected (1 to 10 ppm).
[0006]
The present invention solves the above conventional problems, by performing an efficient TOC degradation, and to provide a way to produce a very high purity ultra-pure water.
[0007]
[Means for Solving the Problems]
The method for producing ultrapure water according to the present invention is the method for producing ultrapure water having a step of decomposing TOC by injecting ozone into water and irradiating ultraviolet rays, wherein the pH of the water into which ozone is injected is 3.5 to 4 times. It is characterized by adjusting to.
[0008]
In the conventional TOC decomposition means, although _{O 3} injection and UV irradiation is performed for the neutral to weakly basic aqueous, in accordance with the present invention, _{O 3} implantation and UV in an acidic region of PH3.5～ 4 By performing irradiation, TOC can be efficiently decomposed and reduced to an extremely low concentration.
[0009]
The method of the present invention includes, for example, ultrapure water production provided with a primary pure water production apparatus in which a decarbonation tower, a reverse osmosis membrane separation apparatus, an ozone absorption tower, an ultraviolet irradiation apparatus, and an ion exchange pure water apparatus are sequentially arranged. an apparatus, ultrapure water production apparatus provided with means for by injecting an acid into deaerator the pH of the water to be introduced into the ozone absorption column and from 3.5 to 4, it is carried out easily it can.
[0010]
As described above, after the reverse osmosis membrane separation device is provided with the ozone absorption tower and the ultraviolet irradiation device, and after removing most of the TOC in the water to be treated by the reverse osmosis membrane separation device, the remaining TOC is removed by the ozone absorption tower and the ultraviolet light By removing the TOC with the irradiation device, TOC removal can be performed efficiently. Since a reverse osmosis membrane separator cannot remove carbon dioxide (CO ₂ ) almost, a decarbonation tower is provided in front of the reverse osmosis membrane separator. In this case, acid is injected into the decarbonation tower. By introducing an acid for adjusting pH for decomposing TOC by injecting O ₃ and UV irradiation in this decarbonation tower, the injected acid can be used for decarboxylation. It also works effectively for decomposition, which is extremely advantageous.
[0011]
Further, the method of the present invention can be easily carried out by an ultrapure water production apparatus including a cation exchange tower, an ozone absorption tower, an ultraviolet irradiation apparatus, and a primary pure water production apparatus in which anion exchange towers are sequentially arranged. be able to.
[0012]
That is, the cation exchange water flowing out of the cation exchange tower can be acidic water having a pH of 3.5 to 4 , and thus, by arranging the ozone absorption tower and the ultraviolet irradiation device at the stage of the cation exchange tower. This eliminates the need for acid injection for pH adjustment.
[0013]
Injection of O ₃ and UV irradiation generate hydroxyl radicals in water via active oxygen, which is presumed to act on TOC to oxidize and decompose TOC. _In order to capture and remove these products, the product is brought into contact with an anion exchange resin disposed downstream of the ozone absorption tower and the ultraviolet irradiation device.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
Figure 2 is a system diagram of a primary pure water producing apparatus according to an embodiment of the manufacturing how ultrapure water of the present invention, these primary pure water production apparatus, as shown in FIG. 3, the pre-processing unit An ultrapure water production device is arranged between the first and second pure water production devices 3.
[0016]
In the apparatus shown in Figure 1, before treated water fed from the pre-processing device, first, removing CO ₂ treatment was introduced to the decarbonation tower after injection of acid. Here, as the acid to be injected, any acid such as sulfuric acid or hydrochloric acid can be used, and the acid has a pH of 3 . Inject so that it becomes 5-4.
[0017]
The treated water of the decarbonation tower is then subjected to removal of salts, ionic, and colloidal TOC by a reverse osmosis membrane separation device, followed by injection of O ₃ by an ozone absorption tower, followed by UV irradiation by an ultraviolet irradiation device and TOC. Is decomposed and removed.
[0018]
After removing residual O ₃ , CO ₂ and DO with the deaerator, the treated water of the ultraviolet irradiation device is further purified with a mixed-bed ion exchange pure water device and sent to the secondary pure water production device. I do.
[0019]
The apparatus shown in FIG. 2 includes an ozone absorption tower and an ultraviolet ray between a cation exchange tower and a decarbonation tower of a multi-bed tower ion exchange resin desalination apparatus comprising an activated carbon tower, a cation exchange tower, a decarbonation tower, and an anion exchange tower. It is an arrangement of irradiation devices.
[0020]
In this apparatus, the pretreatment water fed from the pretreatment apparatus is first subjected to cation exchange treatment in a cation exchange tower after TOC and residual chlorine are removed in an activated carbon tower.
[0021]
The effluent of this cation exchange column has a pH of 3. Since the acidic water of 5 to 4 can be used, the pH condition of the present invention can be easily satisfied by injecting O ₃ and UV irradiation to the cation exchange water.
[0022]
The effluent of the ultraviolet irradiation device from which TOC has been decomposed and removed by the ozone absorption tower and the ultraviolet irradiation device is then sent to the anion exchange column after CO ₂ and residual O ₃ have been removed by the decarbonation column. Incidentally, the inflow water of the decarbonation tower, a high CO ₂ removal efficiency for an acidic water low pH.
[0023]
The water subjected to the anion exchange treatment in the anion exchange tower is further treated in order in a degassing device and a reverse osmosis membrane separation device, and then sent to a secondary pure water production device.
[0024]
In the apparatus shown in FIG. 2, an intermediate product generated by decomposition of TOC by O ₃ injection and UV irradiation is removed in the anion exchange tower.
[0025]
In the apparatus shown in FIGS. 1 and 2, an air stripping tower or the like can be adopted as the decarbonation tower. Further, as the deaerator, a vacuum deaerator or a nitrogen gas deaerator can be adopted.
[0026]
As the ozone absorption tower, any gas-liquid contact type can be used.For example, water is supplied from above to a cylindrical container, and ozone-containing air is bubbled from a diffuser provided below the stored water. However, a system in which a part of water is discharged from the lower part and brought into contact with ozone can be employed. The ozone absorption tower may be filled with a filler to improve the contact efficiency.
[0027]
On the other hand, the light source used in the ultraviolet irradiation device only needs to generate ultraviolet light having a wavelength of 254 nm (254 nm alone, or 185 nm and 254 nm), and a mercury lamp is usually used. This ultraviolet irradiation device may be a low pressure type or a high pressure type.
[0028]
In the present invention, the feedwater pH of the ozone absorption tower is adjusted to 3.5 to 4. In this adjusted pH range, the lower the pH, the higher the TOC decomposition rate. However, when the pH is less than 3.5, although the TOC decomposition effect is obtained, the improvement rate of the TOC decomposition efficiency is not high despite the increase in the amount of acid added. This leads to an increased load on the device, which is not desirable. On the other hand, when the pH exceeds 4 , the TOC decomposition efficiency decreases, and approaches the conventional decomposition rate near neutral. For this reason, the adjusted pH is 3 . 5 to 4.
[0029]
In the present invention, the O ₃ injection and UV irradiation conditions in the ozone absorption tower can be in the usual ranges of the O ₃ injection amount of 1 to 10 ppm and the UV output of 0.03 to 0.3 KW / m ³ .
[0030]
Note that the apparatus shown in FIGS. 1 and 2 is an example of an apparatus suitable for the present invention, and the present invention is not limited to the illustrated apparatus at all unless it exceeds the gist.
[0031]
For example, in FIG. 1, the remaining O ₃ is removed by the O ₃ injection and UV irradiation by the deaerator, but NaHSO ₃ is injected at the outlet of the ultraviolet irradiation device to decompose the remaining O _3. good.
[0032]
In the apparatus shown in FIG. 2, the decarbonation tower may be provided between the cation exchange tower and the ozone absorption tower. However, from the viewpoint of O ₃ injection and removal of residual O ₃ after UV irradiation, FIG. As shown in the above, it is preferable to provide it at the subsequent stage of the ultraviolet irradiation device.
[0033]
In addition, in the apparatus shown in FIG. 2, when NaHSO ₃ is injected at the outlet of the ultraviolet irradiation apparatus to decompose residual O _3, a cation exchange tower is further provided downstream of the anion exchange tower, so that Na ⁺ , SO ₃ ⁺ , and SO ₄ ²⁻ ions can be removed.
[0034]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0035]
In the following Examples and Comparative Examples, Atsugi City Water was used as raw water. The specifications of each device used are as follows.
UF: Ultrafiltration membrane separator using polysulfone ultrafiltration membrane Coagulation / floating / filtration: After treatment at pH 6.5 by adding polyaluminum chloride, RO filtration: Using polyamide reverse osmosis membrane There was a reverse osmosis membrane separation device O ₃ absorption tower: blowing the O ₃ from the lower-free method of ozone absorption tower UV equipment: vertical cylindrical container to the low-pressure mercury lamp "AZ-3" (manufactured by Nippon photo Science, Inc.) four inserts ultraviolet ray irradiation apparatus degasser: nitrogen gas deaerator MB: mixed bed ion exchange pure water device AC: activated carbon column _{D eca:} decarbonation tower _{H 1:} cation exchange column OH _1: anion exchange column 2B3T: _{H 1} → _Deca → OH
[0036]
Examples 1 and 2
The raw water was treated with UF, adjusted to pH _{4 by} injecting H ₂ SO _4, and then passed through _Deca → RO → O ₃ absorption tower → UV device → deaerator → MB for treatment.
[0037]
The UV output the values shown in Table 1 in _{O 3} injection concentration and UV device in O ₃ absorption tower, examined the TOC of _{O 3} absorption column influent (RO effluent water), the TOC of MB runoff, Table 1 Results It was shown to.
[0038]
Comparative Example 1
After UF treatment of the raw water, NaHSO ₃ was injected to remove residual chlorine, and then the water was sequentially passed through RO → O ₃ absorption tower → UV device → (injection of NaHSO ₃ ) → degasifier → MB. . The pH of the inflow water (RO outflow water) of the O ₃ absorption tower was 7.5.
[0039]
The UV output the values shown in Table 1 in _{O 3} injection concentration and UV device in O ₃ absorption tower, examined the TOC of _{O 3} absorption column influent (RO effluent water), the TOC of MB runoff, Table 1 Results It was shown to.
[0040]
Example 3, Comparative Examples 2 and 3
In Example 1, the treatment was performed in the same manner as in Example 1 except that the pH due to H ₂ SO ₄ injection was set to the value shown in Table 1, and the TOC of the O ₃ absorption tower inflow water (RO effluent) and the TOC of the MB effluent were measured. And the results are shown in Table 1.
[0041]
[Table 1]

[0042]
Examples 5 and 6
After coagulation / floating / filtration treatment of the raw water, water was passed through AC → H ₁ → O ₃ absorption tower → UV device → _Deca → OH _{1 in} that order for treatment. Incidentally, TOC of AC treated water is 350 ppb, pH and TOC of _{O 3} absorption tower of influent _{(H 1} treated water) was as shown in Table 2.
[0043]
The UV output the values shown in Table 2 in the _{O 3} injection concentration and UV device in O ₃ absorption tower, examine the TOC of OH ₁ effluent, and the results are shown in Table 2.
[0044]
Comparative Example 4
The raw water was subjected to coagulation / floating / filtration treatment, and then passed through AC → 2B3T → O ₃ absorption tower → UV device → MB for treatment. The TOC of the AC treated water was 350 ppb, and the pH and TOC of the inflow water (2B3T treated water) of the O ₃ absorption tower were as shown in Table 2.
[0045]
The UV output the values shown in Table 2 in the _{O 3} injection concentration and UV device in O ₃ absorption tower, examine the TOC of MB effluent, and the results are shown in Table 2.
[0046]
[Table 2]

[0047]
From Tables 1 and 2, it is clear that according to the present invention, the TOC reduction concentration by O ₃ injection and UV irradiation can be reduced by almost half as compared with the related art.
[0048]
【The invention's effect】
As described in detail above, according to the manufacturing how ultrapure water of the present invention, TOC and efficiently decomposed and removed, can be produced very high purity ultra-pure water.
[Brief description of the drawings]
1 is a system diagram of a primary pure water producing apparatus according to an embodiment of the manufacturing how ultrapure water of the present invention.
2 is a system diagram of a primary pure water producing system according to still another embodiment of the manufacturing how ultrapure water of the present invention.
FIG. 3 is a system diagram showing a configuration of an ultrapure water production apparatus.
FIG. 4 is a system diagram showing a conventional primary pure water production apparatus.
FIG. 5 is a system diagram showing a conventional primary pure water production apparatus.
[Explanation of symbols]
1 Pretreatment device 2 Primary pure water production device 3 Secondary pure water production device

Claims (1)

In water by performing an ozone injection and ultraviolet irradiation in the manufacturing process of ultra-pure water having a step of decomposing the TOC, the ultrapure water and adjusting the pH of the water to inject ozone into 3.5 to 4 Manufacturing method .

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