JP3699502B2 - Semiconductor cleaning wastewater collection method - Google Patents
Semiconductor cleaning wastewater collection method Download PDFInfo
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- JP3699502B2 JP3699502B2 JP08816295A JP8816295A JP3699502B2 JP 3699502 B2 JP3699502 B2 JP 3699502B2 JP 08816295 A JP08816295 A JP 08816295A JP 8816295 A JP8816295 A JP 8816295A JP 3699502 B2 JP3699502 B2 JP 3699502B2
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Description
【０００１】
【産業上の利用分野】
本発明は半導体洗浄排水の回収方法に係わり、特に半導体製造工程から排出される半導体洗浄排水を活性炭塔に通水した後イオン交換装置に通水して、高純度の処理水を回収する方法に関する。
【０００２】
【従来の技術】
従来、半導体製造工程から排出される半導体洗浄排水は、例えば特公昭６１−１１９２号公報に開示されているように、活性炭（ＡＣ）塔、弱塩基性アニオン交換樹脂（ＷＡ）塔、強酸性カチオン交換樹脂（ＳＣ）塔及び強塩基性アニオン交換樹脂（ＳＡ）塔に順次通水処理された後、純水製造装置に通水処理され、超純水として再使用されている。その処理系統図を図２に示す。
【０００３】
半導体洗浄排水の処理に当たり、このように、ＡＣ塔、ＷＡ塔、ＳＣ塔及びＳＡ塔に順次通水処理する理由は次の通りである。
即ち、半導体洗浄排水は、
半導体洗浄排水中の過酸化水素はＡＣ塔で分解除去されるがこのＡＣ塔においては、過酸化水素の分解除去時に、半導体排水中に含有されるフッ酸、硫酸、塩酸等により、活性炭中に不純物として含まれるナトリウムやカルシウム等の陽イオン物質の溶出が起こる。この陽イオン物質の溶出は、微量であるが、ＡＣ塔の流出水、更にはＷＡ塔の流出水の水質を悪化させる要因となる。因に、従来の回収方法において、通常の場合、半導体洗浄排水をＡＣ塔及びＷＡ塔に通水して得られる水の電導度は１０〜２０υＳ／cmを超えるものであり、ＷＡ塔のみのイオン交換処理では、十分な純度の水を回収することはできない。このため、これらの陽イオン物質を除去するために、ＷＡ塔の後段に、カチオン交換樹脂を設ける必要がある。
【０００４】
実際には、半導体洗浄排水中の酸を効率よく除去するために、ＷＡ塔とＳＡ塔とが組み合せて使用されることから、上述の如く、半導体洗浄排水は、従来、ＡＣ塔、ＷＡ塔、ＳＣ塔及びＳＡ塔に順次通水処理され、これにより、電導度５υＳ／cm以下の水質の処理水を回収している。
【０００５】
【発明が解決しようとする課題】
上記従来の半導体洗浄排水の回収法では、ＡＣ塔の活性炭から溶出する陽イオン物質の除去設備としてのＳＣ塔を必要とするため、設置塔数が多く、装置の設置スペース、回収効率及び回収コスト等の面で工業的に不利であった。
【０００６】
本発明は、上記従来の問題点を解決し、半導体洗浄排水を、ＡＣ塔に通水した後、イオン交換装置に通水して水を回収する方法において、ＡＣ塔の活性炭からの微量の陽イオン物質の溶出を防止して、ＳＣ塔を必要とすることなく、十分に高純度の水を回収することができる半導体洗浄排水の回収方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明の半導体洗浄排水の回収方法は、半導体洗浄排水を、活性炭が充填された活性炭塔に通水した後、イオン交換装置に通水して水を回収する方法において、該活性炭が、あらかじめ２〜４重量％濃度の希塩酸と接触させた後、超純水で洗浄されていることを特徴とする。
上記の回収方法において、活性炭と希塩酸との接触時間は、３６時間以上が好適であり、また、超純水の比抵抗１０ＭΩ・cm以上であることが好ましい。
【０００８】
【作用】
ＡＣ塔に充填させる活性炭を２〜４重量％濃度の希塩酸と接触させることにより、活性炭中に不純物として含有される陽イオン物質を効率的に溶出させることができる。
【０００９】
本発明において、活性炭と希塩酸との接触は、活性炭を充填したＡＣ塔に希塩酸を通水又は滞留させて行っても良く、また、ＡＣ塔に充填する前の活性炭を別の容器内で希塩酸に浸漬することにより行っても良い。この希塩酸との接触時間は活性炭中の陽イオン物質を十分に溶出させるため、３６時間以上とするのが好ましく、通常の場合、４０〜５０時間程度であればよい。
【００１０】
希塩酸の濃度が２重量％未満では、活性炭中から陽イオン物質を効率的に溶出させることができず、４重量％を超えると活性炭の中に拡散した塩酸そのものの洗浄性が悪くなる。
【００１１】
このように活性炭を希塩酸と接触させた後は、必要に応じて付着塩酸のブロー除去を行った後、活性炭を超純水で洗浄する。この超純水による洗浄も、ＡＣ塔充填前の活性炭に別途洗浄容器を用いて行うこともできるが好ましくは活性炭を充填したＡＣ塔に、超純水を通水して洗浄するのが望ましい。この場合、超純水は、空間速度ＳＶ＝１０〜３０Ｈｒ-1で１時間以上、特に１．２〜１．５時間通水して洗浄を行うのが好ましい。
【００１２】
このような水洗浄に用いる超純水は、比抵抗１０ＭΩ・cm以上のものが好ましい。この洗浄水の比抵抗が１０ＭΩ・cm未満であると、本発明による十分な活性炭の清浄化効果が得られない。
【００１３】
なお、本発明において、ＡＣ塔に充填される活性炭としては、粒度１０〜４０メッシュ程度の粒状活性炭が好ましく使用される。
【００１４】
上述の方法によって、希塩酸による処理と水洗浄で十分に清浄度が高められた活性炭には、不純物である陽イオン物質の溶出の問題はなくなり、陽イオン物質除去のためのＳＣ塔が、不要となるので、ＡＣ塔の後段のイオン交換装置としては、図１に示す如く、ＷＡ塔のみで十分に高純度の水を回収することができる。
【００１５】
ただし、本発明において、ＡＣ塔の後段のイオン交換装置としては、ＷＡ塔のみに限られるものではなく、ＷＡ塔とＳＡ塔とを組み合わせたり、更に、ＷＡ塔と混床式ポリッシャーを組み合わせたり、ＷＡ塔とＲＯ装置を組み合わせても良い。
【００１６】
なお、活性炭の酸洗浄自体は、従来、一般排水用或は給水用、上水用にも行われている。しかし、従来の酸洗浄は、活性炭初期充填直後のＰＨが高くなることを防止するためのもので、ＰＨを中性にするために４．０〜１０．０重量％程度の比較的濃度の高い酸の注入を行っているのみであり、本発明の方法とは目的及び操作条件が異なる。
【００１７】
【実施例】
以下、図面を参照して本発明の半導体洗浄排水の回収方法を詳細に説明する。
図１は本発明の半導体洗浄排水の回収方法の一実施例を示す系統図であり、１は活性炭（１Ａ）が充填されたＡＣ塔、２は弱塩基性アニオン交換樹脂（２Ａ）が充填されたＷＡ塔を示し、１１は処理すべき半導体洗浄排水配管、１２はＡＣ塔とＷＡ塔を連絡する配管、１３は処理水の配管を示す。
【００１８】
本実施例の方法においては、半導体製造工程から排出された半導体洗浄排水を、まず配管（１１）よりＡＣ塔（１）に下向流通水して有機物を除去した後、配管（１２）よりＷＡ塔（２）に下向流通水してフッ酸、硝酸、硫酸等の酸を除去し、処理水を配管（１２）より抜き出す。
【００１９】
本発明の方法においては、このような半導体洗浄排水からの水の回収方法において、半導体洗浄排水の通水処理に先立ち、ＡＣ塔に充填する活性炭は、あらかじめ２〜４重量％濃度の希塩酸に接触させた後、超純水で洗浄する。
以下に具体的な実施例及び比較例を挙げて、本発明をより具体的に説明する。
【００２０】
（本発明例）
活性炭として石炭系粒状活性炭（粒度１０〜３２メッシュ）を用い、この活性炭３００mlを２．５〜３．５重量％の希塩酸中に４４時間浸漬処理した。その後、活性炭を分取し、希塩酸をブローして除去した後、ＡＣ塔に比抵抗１０．０〜１１．０ＭΩ・cmの超純水を空間速度＝１２Ｈｒ-1で１．２時間通水して活性炭を洗浄した。
【００２１】
このＡＣ塔と、弱塩基性アニオン交換樹脂（ダイヤイオンＷＡ３０）を２００ml充填したＷＡ塔とに、表１に示す水質の半導体洗浄排水をＳＶ＝１８Ｈｒ-1で順次下向流通水し、ＡＣ塔流出水のＰＨ及び処理水（ＷＡ塔流出水）ＰＨ、電導度を測定した。
その結果は表１に示すように、本発明の方法によれば、ＡＣ塔とＷＡ塔のみで、十分に高純度の水を回収することができる。
【００２２】
（比較例）
一方、ＡＣ塔に充填する活性炭の希塩酸処理に際してその濃度が２重量％未満の場合、及び希塩酸処理と水洗浄を行わなかった場合には、同じく表１に示すように、高純度水を回収することができない。
【００２３】
【表１】
【発明の効果】
以上記述した通り、本発明の半導体洗浄排水の回収方法によれば、半導体洗浄排水をＡＣ塔に通水した後、イオン交換装置に通水して水を回収するに当たり、イオン交換装置として、活性炭からの溶出陽イオン物質除去のためのＳＣ塔が不要となり、ＷＡ塔のみで即ち、ＡＣ塔とＷＡ塔のみで、電導度５υＳ／cm以下という高純度水を効率的に回収することができる。
その結果として、本発明の半導体洗浄排水の回収方法によれば、イオン交換装置の必要塔数が低減され、装置の設置スペースの低減、回収効率の向上及びコストの低減が図れ、工業的に極めて有利である。
【図面の簡単な説明】
【図１】本発明の半導体洗浄排水の回収方法の一実施例を示す系統図である。
【図２】従来の半導体洗浄排水の回収方法を示す系統図である。
【符号の説明】
１ 活性炭（ＡＣ）塔
１Ａ 活性炭
２ アニオン樹脂（ＷＡ）塔
２Ａ アニオン樹脂（ＷＡ）
３ カチオン樹脂（ＳＣ）塔
３Ａ カチオン樹脂（ＳＣ）
４ アニオン樹脂（ＳＡ）塔
４Ａ アニオン樹脂（ＳＡ）
１１ 半導体洗浄排水配管
１２ ＡＣ塔とＷＡ塔を連絡する配管
１３ 処理水配管[0001]
[Industrial application fields]
The present invention relates to a method for collecting semiconductor cleaning wastewater, and more particularly to a method for collecting high-purity treated water by passing the semiconductor cleaning wastewater discharged from the semiconductor manufacturing process through an activated carbon tower and then through an ion exchange device. .
[0002]
[Prior art]
Conventionally, semiconductor cleaning wastewater discharged from a semiconductor manufacturing process is, for example, as disclosed in Japanese Patent Publication No. 61-1192, activated carbon (AC) tower, weakly basic anion exchange resin (WA) tower, strong acid cation. After being sequentially passed through an exchange resin (SC) tower and a strongly basic anion exchange resin (SA) tower, the water is passed through a pure water production apparatus and reused as ultrapure water. The processing system diagram is shown in FIG.
[0003]
The reason for sequentially passing the water through the AC tower, WA tower, SC tower, and SA tower in the treatment of the semiconductor cleaning wastewater is as follows.
That is, the semiconductor cleaning wastewater
The hydrogen peroxide in the semiconductor cleaning wastewater is decomposed and removed by the AC tower. In this AC tower, hydrofluoric acid, sulfuric acid, hydrochloric acid, etc. contained in the semiconductor wastewater are dissolved in the activated carbon when hydrogen peroxide is decomposed and removed. The elution of cationic substances such as sodium and calcium contained as impurities occurs. Although the elution of this cationic substance is very small, it causes deterioration of the quality of the effluent of the AC tower and further the effluent of the WA tower. In the conventional recovery method, the electrical conductivity of the water obtained by passing the semiconductor cleaning wastewater through the AC tower and the WA tower exceeds 10 to 20 υ S / cm. In the exchange process, water with sufficient purity cannot be recovered. For this reason, in order to remove these cationic substances, it is necessary to provide a cation exchange resin after the WA tower.
[0004]
Actually, in order to efficiently remove the acid in the semiconductor cleaning wastewater, the WA tower and the SA tower are used in combination. Therefore, as described above, the semiconductor cleaning wastewater has been conventionally used in the AC tower, WA tower, The SC tower and the SA tower are sequentially subjected to water treatment, thereby recovering treated water having a conductivity of 5 υ S / cm or less.
[0005]
[Problems to be solved by the invention]
The conventional semiconductor cleaning wastewater recovery method requires an SC tower as a facility for removing cationic substances eluted from the activated carbon of the AC tower, so there are a large number of installation towers, installation space for the equipment, recovery efficiency, and recovery costs. It was industrially disadvantageous in terms of such factors.
[0006]
The present invention solves the above-mentioned conventional problems, and in a method for collecting the water by passing the semiconductor cleaning wastewater through the AC tower and then through the ion exchange device, a small amount of positive water from the activated carbon of the AC tower is collected. An object of the present invention is to provide a semiconductor cleaning wastewater recovery method capable of preventing elution of ionic substances and recovering sufficiently high-purity water without requiring an SC tower.
[0007]
[Means for Solving the Problems]
The semiconductor cleaning wastewater recovery method of the present invention is a method in which the semiconductor cleaning wastewater is passed through an activated carbon tower filled with activated carbon and then passed through an ion exchange device to collect water. It is characterized by being washed with ultrapure water after being brought into contact with dilute hydrochloric acid having a concentration of ˜4% by weight.
In the above recovery method, the contact time between the activated carbon and dilute hydrochloric acid is preferably 36 hours or more, and the specific resistance of ultrapure water is preferably 10 MΩ · cm or more.
[0008]
[Action]
By contacting the activated carbon charged in the AC tower with dilute hydrochloric acid having a concentration of 2 to 4% by weight, the cationic substance contained as an impurity in the activated carbon can be efficiently eluted.
[0009]
In the present invention, the contact between activated carbon and dilute hydrochloric acid may be carried out by passing or retaining dilute hydrochloric acid in an AC tower filled with activated carbon, and the activated carbon before filling the AC tower is converted into dilute hydrochloric acid in a separate container. It may be performed by dipping. The contact time with the dilute hydrochloric acid is preferably 36 hours or more in order to sufficiently elute the cationic substance in the activated carbon, and in a normal case, it may be about 40 to 50 hours.
[0010]
If the concentration of dilute hydrochloric acid is less than 2% by weight, the cationic substance cannot be efficiently eluted from the activated carbon, and if it exceeds 4% by weight, the cleanability of hydrochloric acid itself diffused into the activated carbon is deteriorated.
[0011]
After the activated carbon is brought into contact with dilute hydrochloric acid in this manner, the attached hydrochloric acid is removed by blow as necessary, and the activated carbon is washed with ultrapure water. This cleaning with ultrapure water can also be performed by using a separate cleaning container for the activated carbon before filling the AC tower, but it is preferable to wash the AC tower filled with activated carbon by passing ultrapure water. In this case, the ultrapure water is preferably washed by passing water at a space velocity SV = 10 to 30 Hr −1 for 1 hour or longer, particularly 1.2 to 1.5 hours.
[0012]
The ultrapure water used for such water washing preferably has a specific resistance of 10 MΩ · cm or more. If the specific resistance of the cleaning water is less than 10 MΩ · cm, the sufficient activated carbon cleaning effect according to the present invention cannot be obtained.
[0013]
In the present invention, as the activated carbon filled in the AC tower, granular activated carbon having a particle size of about 10 to 40 mesh is preferably used.
[0014]
With the above-mentioned method, the activated carbon whose purity is sufficiently increased by treatment with dilute hydrochloric acid and water washing eliminates the problem of elution of the cationic substance as an impurity, and the SC tower for removing the cationic substance is unnecessary. Therefore, as the ion exchange apparatus in the latter stage of the AC tower, as shown in FIG. 1, sufficiently high-purity water can be recovered only by the WA tower.
[0015]
However, in the present invention, the ion exchange apparatus at the latter stage of the AC tower is not limited to the WA tower alone, or a combination of the WA tower and the SA tower, or a combination of the WA tower and a mixed bed polisher, You may combine WA tower and RO apparatus.
[0016]
In addition, the acid cleaning itself of activated carbon itself has been conventionally performed for general drainage, water supply, and water. However, the conventional acid cleaning is intended to prevent the PH immediately after the initial charging of the activated carbon from becoming high. In order to make the pH neutral, the concentration is relatively high, such as about 4.0 to 10.0% by weight. Only the injection of acid is performed, and the purpose and operating conditions are different from the method of the present invention.
[0017]
【Example】
Hereinafter, the semiconductor cleaning waste water recovery method of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a system diagram showing an embodiment of the method for recovering a semiconductor cleaning wastewater according to the present invention. 1 is an AC tower filled with activated carbon (1A), 2 is filled with weakly basic anion exchange resin (2A). 11 shows a semiconductor cleaning drain pipe to be treated, 12 a pipe connecting the AC tower and the WA tower, and 13 a pipe for treated water.
[0018]
In the method of the present embodiment, the semiconductor cleaning wastewater discharged from the semiconductor manufacturing process is first circulated downward from the pipe (11) to the AC tower (1) to remove organic substances, and then the WA from the pipe (12). Water flowing downward into the tower (2) is removed to remove acids such as hydrofluoric acid, nitric acid and sulfuric acid, and treated water is extracted from the pipe (12).
[0019]
In the method of the present invention, in such a method for recovering water from the semiconductor cleaning wastewater, prior to the water treatment of the semiconductor cleaning wastewater, the activated carbon charged in the AC tower is contacted with dilute hydrochloric acid having a concentration of 2 to 4% by weight in advance. Then, wash with ultrapure water.
Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples.
[0020]
(Example of the present invention)
Coal-based granular activated carbon (particle size 10 to 32 mesh) was used as the activated carbon, and 300 ml of this activated carbon was immersed in 2.5 to 3.5% by weight of dilute hydrochloric acid for 44 hours. Then, after separating activated carbon and removing dilute hydrochloric acid by blowing, ultrapure water having a specific resistance of 10.0 to 11.0 MΩ · cm was passed through the AC tower for 1.2 hours at a space velocity of 12 Hr −1 The activated carbon was washed.
[0021]
In this AC tower and a WA tower packed with 200 ml of weakly basic anion exchange resin (Diaion WA30), the semiconductor wastewater having the water quality shown in Table 1 is successively circulated downward at SV = 18Hr −1 to obtain AC tower. The pH of the effluent water, treated water (WA tower effluent water) PH, and conductivity were measured.
As a result, as shown in Table 1, according to the method of the present invention, sufficiently high-purity water can be recovered only with the AC tower and the WA tower.
[0022]
(Comparative example)
On the other hand, when the concentration of the activated carbon charged in the AC tower is less than 2% by weight in the treatment with dilute hydrochloric acid, and when the dilute hydrochloric acid treatment and water washing are not performed, as shown in Table 1, high-purity water is recovered. I can't.
[0023]
[Table 1]
【The invention's effect】
As described above, according to the semiconductor cleaning wastewater recovery method of the present invention, the semiconductor cleaning wastewater is passed through the AC tower and then passed through the ion exchange device to collect water. The SC column for removing the eluted cationic substance from the water is not required, and high-purity water having an electric conductivity of 5 υ S / cm or less can be efficiently recovered with only the WA column, that is, only the AC column and the WA column.
As a result, according to the semiconductor cleaning wastewater recovery method of the present invention, the required number of towers of the ion exchange device is reduced, the installation space of the device can be reduced, the recovery efficiency can be improved, and the cost can be reduced. It is advantageous.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a method for collecting semiconductor cleaning wastewater according to the present invention.
FIG. 2 is a system diagram showing a conventional method for collecting semiconductor cleaning wastewater.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Activated carbon (AC)
3 Cationic Resin (SC) Tower 3A Cationic Resin (SC)
4 Anion resin (SA)
11 Semiconductor cleaning drain piping 12 Piping connecting AC tower and
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08816295A JP3699502B2 (en) | 1995-04-13 | 1995-04-13 | Semiconductor cleaning wastewater collection method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08816295A JP3699502B2 (en) | 1995-04-13 | 1995-04-13 | Semiconductor cleaning wastewater collection method |
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| Publication Number | Publication Date |
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| JPH08281256A JPH08281256A (en) | 1996-10-29 |
| JP3699502B2 true JP3699502B2 (en) | 2005-09-28 |
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| JP08816295A Expired - Fee Related JP3699502B2 (en) | 1995-04-13 | 1995-04-13 | Semiconductor cleaning wastewater collection method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR100345315B1 (en) * | 2000-02-25 | 2002-07-25 | 주식회사 아토 | Recycling apparatus and Method of Waste Acid |
| JP4774617B2 (en) * | 2001-04-05 | 2011-09-14 | 栗田工業株式会社 | Cleaning method of activated carbon |
| JP2002301332A (en) * | 2001-04-05 | 2002-10-15 | Nomura Micro Sci Co Ltd | Method for treating gas containing inorganic acid, device for treatment, treating system and device for cleaning treatment |
| KR100735734B1 (en) * | 2006-03-21 | 2007-07-06 | 재단법인 서울의과학연구소 | The cleansing method of slide for chromosome and the cleansing device |
| US7648637B1 (en) * | 2009-01-29 | 2010-01-19 | Otv S.A. | Water treatment method by ballasted flocculation, settling, and prior adsorbent contact |
| JP5232059B2 (en) * | 2009-03-27 | 2013-07-10 | 日本錬水株式会社 | Wastewater recovery method and wastewater recovery device |
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1995
- 1995-04-13 JP JP08816295A patent/JP3699502B2/en not_active Expired - Fee Related
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