JP2007098268A - Method and apparatus for disposing waste water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for disposing waste water, in each of which particularly stable and excellent disposing water (high-purity disposing water) can be obtained while saving the installation space of the apparatus for disposing waste water when waste water having an acid component is disposed. <P>SOLUTION: The method for disposing waste water comprises the steps of disposing waste water having the acid component in an activated carbon column, in a weak basic anion exchange resin column and then in a double-layered column in one unit of which a strong acidic cation exchange resin layer and a strong basic anion exchange resin layer are formed separately. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a wastewater treatment method and apparatus for treating wastewater containing acid components such as hydrochloric acid and hydrofluoric acid and recovering it as raw water for various types of water (especially for producing pure water), and in particular, semiconductor devices. The present invention relates to a method and apparatus suitable for treating wastewater generated in the electronic component industry such as flat panel displays, silicon wafers, and printed circuit boards.

Various methods are known as a method for treating and recovering wastewater containing an oxidizing agent such as H ₂ O ₂ and acid components such as hydrochloric acid and hydrofluoric acid. For example, in Patent Document 1, wastewater discharged from a semiconductor manufacturing process or the like is an activated carbon tower (hereinafter sometimes abbreviated as CF) or a weakly basic anion exchange resin tower (hereinafter abbreviated as WA). ), A strongly acidic cation exchange resin tower (hereinafter also abbreviated as SC), and a strongly basic anion exchange resin tower (hereinafter abbreviated as SA) in this order. In addition, a method is disclosed in which water is treated through a pure water production apparatus and recovered and reused. Patent Document 2 discloses a method characterized in that the base material is a (meth) acryl-divinylbenzene copolymer having a quaternary ammonium group of more than 30 equivalent% and 50 equivalent% or less as WA. Patent Document 3 discloses a method of treating with CF + WA using CF pretreated with acid and pure water. Patent Document 4 discloses a method of treating wastewater containing organic alkali in the order of CF + WA + SA + SC. Further, in order to increase the purity of the recovered treated water, CF + WA + MB (a tower formed in a mixed bed in which a strongly basic anion exchange resin and a strongly acidic cation exchange resin are mixed) may be used. Furthermore, an ultraviolet oxidizer for the purpose of removing the TOC component, such as UV (ultraviolet ray processing apparatus) + CF + MF (microfiltration apparatus) disclosed in Patent Document 2, may be installed in the subsequent stage.

Such conventional methods have the following problems. In a typical conventional embodiment, in the method of processing in the order of CF + WA + SC + SA,
-Although the treated water has a conductivity of about 10 μS / cm or less (specific resistance: about 0.1 MΩcm or more) and recovered water, the purity is not sufficient.
・ SC + SA requires a large installation space due to the multi-floor configuration in which each tower is installed.

In the method of processing in the order of CF + WA + MB,
・ Since the two towers of SC + SA are MB1, the space can be saved, and the initial purity of the treated water is good at a specific resistance of about 3 to 5 MΩcm, but the resin separation at the time of regeneration backwashing by clamping Defects may cause poor purity of treated water (for example, conductivity is 100 μS / cm or more [specific resistance is 0.01 MΩcm or less]), and good treated water (high purity treated water) is stabilized. It was difficult to obtain.

On the other hand, the present applicant partitions the inside of one tower into an upper part and a lower part, and each of them is filled with a different type of ion exchange resin in a state where there is no free space. A multi-layer tower (hereinafter also abbreviated as SB) formed as individual layers in one tower is manufactured. In this SB, water flow is generally upward flow, and countercurrent regeneration is performed. The characteristics of SB are as follows: (1) Since the resin does not flow during sampling and can be regenerated countercurrently, it can be regenerated efficiently and highly. Therefore, the silica removal rate is superior to MB (for example, SB: <1.0 ppb, MB: 0.5 to 2.0 ppb). (2) Since there is no backwashing / mixing process, the amount of reclaimed wastewater can be reduced (about 20% reduction). (3) Since no resin is mixed, there is no mechanical consumption of the resin, and it can be used stably for a long period of time. Disadvantages include: (1) When there is no backwashing process, when water with turbid components such as SS is treated, the water flow differential pressure is likely to increase, and (2) the purity of the treated water is slightly higher than MB. It is low.
Japanese Patent Publication No. 61-1192 JP 2000-153165 A JP-A-8-281256 JP-A-8-39059

  The object of the present invention is to focus particularly on the characteristics of the multi-layer tower (SB) as described above, and to incorporate it into a treatment system, so that when wastewater containing acid components is treated, it is particularly stable while saving space. Another object of the present invention is to provide a wastewater treatment method and apparatus capable of obtaining good treated water (high-purity treated water).

  In order to solve the above-mentioned problems, the wastewater treatment method according to the present invention comprises treating an wastewater containing an acid component with an activated carbon tower, a weakly basic anion exchange resin tower, a strongly acidic cation exchange resin and a strongly basic anion. It consists of a method characterized in that it is processed in this order in a multi-layered column (hereinafter sometimes simply referred to as SB) in which ion exchange resins are formed as individual layers in one column.

  Further, the wastewater treatment apparatus according to the present invention includes an activated carbon tower, a weakly basic anion exchange resin tower, and a strongly acidic cation exchange resin and a strongly basic anion as a treatment tower for treating wastewater containing an acid component. It consists of an apparatus characterized by arranging a multi-layered tower in which exchange resins are formed as individual layers in one tower in this order.

  In the wastewater treatment method and apparatus according to the present invention, a multi-layered tower (SB) in which a strongly acidic cation exchange resin and a strongly basic anion exchange resin are formed as separate layers in one tower is used. Compared to the conventional CF + WA + SC + SA system, the number of towers is reduced, and the entire system can be saved in space. Moreover, compared with the CF + WA + MB system, it is possible to suppress fluctuations in the quality of the treated water, and it is possible to stably obtain a desired good water quality.

  The upstream layer of the multi-layer tower is preferably a strongly acidic cation exchange resin layer. As an advantage of making the upstream layer of SB a strong acid cation exchange resin layer, since the WA-treated water is weakly alkaline, it is processed in the order of strong acid cation exchange resin and strong basic anion exchange resin. Is optimal.

  Moreover, it is preferable that the water to be treated be passed through the multi-layer tower in a downward flow. As described above, the advantage of the SB as a downflow is that the recovery system process requires less high water quality (conductivity) and is ON / OFF operation, so it can be stopped at any stage. Is suitable.

  Furthermore, the properties of the wastewater that is to be treated are not particularly limited as long as it is wastewater containing an (oxidizer and) acid component or an acid component and an oxidizer, but the drainage conductivity is 100 to 2000 μS / cm, and the pH is The effect of the present invention is particularly great when wastewater of 2 to 6 is treated.

  As described above, according to the wastewater treatment method and apparatus according to the present invention, it is possible to obtain particularly stable treated water (high-purity treated water) in a space-saving manner, which occurs in the electronic component industry and the like. It becomes possible to collect the wastewater stably.

Hereinafter, the present invention will be described in detail together with preferred embodiments.
In the wastewater treatment method and apparatus according to the present invention, wastewater containing an acid component is activated carbon tower (CF), weakly basic anion exchange resin tower (WA), and strongly acidic cation exchange resin and strongly basic. The treatment is performed in this order in a multi-layered column (SB) in which an anion exchange resin is formed as individual layers in one column. Preferably, the upstream layer of the multi-layer tower is a strong acid cation exchange resin layer, and the flow of water to be treated to the multi-layer tower is a downward flow.

For example, in electronic parts factories such as semiconductor factories, wastewater containing (oxidant and) acid components is discharged. For example, waste water from a washing process using a mixed solution of sulfuric acid / H ₂ O ₂ , hydrochloric acid / H ₂ O ₂ , HF / H ₂ O _2, etc., and the acid components include dilute hydrofluoric acid, nitric acid, acetic acid, Contains phosphoric acid. In the activated carbon tower, the oxidizing agent is decomposed and organic substances are removed by adsorption. Most of the H ₂ O ₂ is removed by the activated carbon tower. Activated carbon can also decompose and remove ozone and chlorine-based oxidants. In the weakly basic anion exchange resin tower, the acid component is removed. Since the acid component is contained, the pH of the waste water usually shows an acidity of about 2 to 6, so that the acid component can be efficiently removed by WA. Even if it is said to be drainage, the SS of process wastewater is originally low. Moreover, since WA itself functions also as a filter, even if SS is mixed, it can be removed. SS captured by WA can be removed by backwashing. Therefore, since there is almost no SS load on the SB, the differential pressure of the SB does not increase greatly even if it is operated for a long time. That is, no problem occurs in the application of SB.

  The treated water quality by the system of the present invention is about 1 MΩcm in specific resistance, which is slightly inferior to the initial MB treated water quality (3 to 5 MΩcm), but is sufficiently satisfactory as the treated water quality. And, by using SB instead of MB, it is possible to secure a stable water quality for a long period of time (that is, the water quality is not stable in MB as described above), and the extremely excellent effect by the present invention, that is, space saving is achieved. However, the effect that the good water quality can be stably maintained is obtained. In addition, the quality of the treated water (for example, about 1 MΩcm in specific resistance) is sufficiently high in purity as recovered water (accepted by a deionized water device, a two-bed / three-column device, a reverse osmosis membrane device (RO), MB, etc. Therefore, there is no problem even when compared with the initial MB treated water.

  FIG. 1 shows a schematic equipment system diagram of a wastewater treatment apparatus according to an embodiment of the present invention. In the wastewater treatment apparatus 1 shown in FIG. 1, raw water as treated water is introduced into an activated carbon tower (CF) 2, from which a weakly basic anion exchange resin tower (WA) 3, a downflow type The strongly acidic cation exchange resin layer 4 and the strongly basic anion exchange resin layer 5 are sent in this order to a multi-layered column (SB) 6 formed as individual layers in one column and processed. The treated water from the multi-layered tower (SB) 6 can be reused as pure water raw water or miscellaneous water, and a TOC removal device 7 (for example, a UV oxidation device, an ozone treatment device, a RO (reverse osmosis membrane device), etc.) Can be reused as pure water with higher purity.

As a more specific embodiment, for example, the following conditions can be adopted.
(1) Although it does not specifically limit as activated carbon, For example, "Diahope" 006N by Mitsubishi Chemical Corporation can be used. As a design condition of the activated carbon tower, use at SV: 1 to 50 can be adopted. In particular, SV: about 10 to 20 is suitable.
(2) Although it does not specifically limit as WA, For example, IRA-96RF by Rohm and Haas company can be used. As a design condition, use at LV: 10 to 100 m / H can be adopted. Particularly, LV: about 20 to 30 m / H is preferable.
(3) The SB is not particularly limited. For example, “AMBERJET” 1500H and “AMBERJET” 4400OH manufactured by Rohm and Haas can be used. As a design condition, use at LV: 10 to 100 m / H can be adopted. In particular, good water quality (1 MΩcm or more in specific resistance) can be obtained even at about LV: 20 to 30 m / H.
(4) The treated water by the apparatus according to the present invention can be used for multipurpose applications (boilers, cooling towers, etc.) in addition to raw water for pure water. However, when the raw water TOC concentration is high or high-purity water quality is required, as shown in FIG. 1, a device for removing the TOC in the subsequent stage (UV oxidation + activated carbon, ozone oxidation + activated carbon, RO, etc.) ) May be installed. The treated water can be reused as raw water for a pure water device.

Next, the present invention will be described based on examples.
Example 1
Waste water from the semiconductor manufacturing process (conductivity: 1000-1500 μS / cm, pH 2-4, H ₂ O ₂ : 1 ppm, fluorine ion: 5 ppm included) is put into an activated carbon tower packed with “DIAHOPE” 006N manufactured by Mitsubishi Chemical Corporation. Then, it was treated under the condition of SV10, and then treated with WA filled with IRA-96RF made by Rohm and Haas under the condition of LV 30 m / H. The water was treated with SB filled with “AMBERJET” 1500H and “AMBERJET” 4400OH manufactured by Rohm and Haas under the condition of LV 30 m / H.

Comparative Example 1
Wastewater from the same semiconductor manufacturing process as in Example 1 was treated under the condition of SV10 in an activated carbon tower filled with “DIAHOPE” 006N manufactured by Mitsubishi Chemical Corporation, and then LV30 m with WA filled with IRA-96RF manufactured by Rohm and Haas. Treated under the conditions of / H. The water was treated with MB filled with “AMBERJET” 1500H and “AMBERJET” 4400OH manufactured by Rohm and Haas under the condition of LV 30 m / H.

Comparative Example 2
Wastewater from the same semiconductor manufacturing process as in Example 1 was treated under the condition of SV10 in an activated carbon tower filled with “DIAHOPE” 006N manufactured by Mitsubishi Chemical Corporation, and then LV30 m with WA filled with IRA-96RF manufactured by Rohm and Haas. Treated under the conditions of / H. The water was treated with an SC filled with “AMBERJET” 1500H made by Rohm and Haas, under the condition of LV30 m / H, and further treated with SA filled with “AMBERJET” 4400OH made by Rohm and Haas under the condition of LV30 m / H. .

  As a result, in Example 1, a water quality of 2 to 3 MΩcm was stably obtained with a specific resistance over one year or more. Moreover, compared with the comparative example 2, since it is one tower, installation space is small. In Comparative Example 1, although the water quality of about 5 MΩcm was obtained in the initial stage, the water quality deteriorated as the regeneration cycle was repeated, and after one month, even after regeneration, the water quality increased only about 0.01 MΩcm and water could not be collected. (Reproduction failure). In Comparative Example 2, a water quality of 0.03 to 0.05 MΩcm or more was stably obtained over a long period of time, but the water quality was much inferior to that of Example 1 and the problem of a large installation space remained. Remained.

1 is a schematic equipment diagram of a wastewater treatment apparatus according to an embodiment of the present invention.

Explanation of symbols

1 Wastewater treatment equipment 2 Activated carbon tower (CF)
3 Weakly basic anion exchange resin tower (WA)
4 Strongly acidic cation exchange resin layer 5 Strongly basic anion exchange resin layer 6 Multi-layer tower (SB)
7 TOC removal device

Claims (8)

  An activated carbon tower, a weakly basic anion exchange resin tower, and a multi-layer tower in which a strongly acidic cation exchange resin and a strongly basic anion exchange resin are formed as separate layers in a single tower. In this method, the wastewater is treated in this order.   The wastewater treatment method according to claim 1, wherein the upstream layer of the multi-layered tower is a strongly acidic cation exchange resin layer.   The wastewater treatment method according to claim 1 or 2, wherein the water to be treated is passed through the multi-layer tower in a downward flow.   The wastewater treatment method according to any one of claims 1 to 3, wherein the property of the wastewater to be treated is an electrical conductivity of 100 to 2000 µS / cm and a pH of 2 to 6.   As a treatment tower for treating wastewater containing acid components, activated carbon tower, weakly basic anion exchange resin tower, and strongly acidic cation exchange resin and strong basic anion exchange resin as separate layers in one tower A wastewater treatment apparatus in which the formed multi-layer towers are arranged in this order.   The waste water treatment apparatus according to claim 5, wherein the upstream layer of the multi-layer tower is a strongly acidic cation exchange resin layer.   The wastewater treatment apparatus according to claim 5 or 6, wherein water to be treated is passed through the multi-layer tower in a downward flow.   The wastewater treatment apparatus according to any one of claims 5 to 7, wherein the wastewater being treated water has a conductivity of 100 to 2000 µS / cm and a pH of 2 to 6.

Images