JP5489419B2 - Method and apparatus for treating hydrogen peroxide-containing water - Google Patents

Description

  The present invention relates to a method and apparatus for treating hydrogen peroxide-containing water discharged from a semiconductor manufacturing process, a food container cleaning process, and the like.

  Hydrogen peroxide is a chemical with a low environmental impact that decomposes into harmless oxygen and water after reaction, and is widely used as a cleaning agent and disinfectant in manufacturing processes. . For example, in a semiconductor device manufacturing factory, hydrogen peroxide is used for cleaning wafers in various processes.

  Hydrogen peroxide used for cleaning, sterilization, etc. is discharged as wastewater from the manufacturing process, but since hydrogen peroxide is sterilizing and itself becomes a COD source, it must be discharged directly into public waters. However, it is necessary to decompose hydrogen peroxide.

  Conventionally, as a decomposition treatment method of hydrogen peroxide-containing water, (1) a method of adding a reducing agent such as sodium bisulfite, (2) a method of continuously passing water through an activated carbon tower (see, for example, Patent Document 1), ( 3) A method of adding catalase (see, for example, Patent Document 2) has been adopted.

  Here, regarding the decomposition treatment method using sodium bisulfite, since sodium bisulfite reacts with hydrogen peroxide in an equimolar amount, if the concentration of hydrogen peroxide in the wastewater is high, a large amount of sodium bisulfite must be used. However, there is a problem that the processing cost becomes high. In addition, when sodium bisulfite is added excessively, there is a disadvantage that the pH of the treated water is lowered, and when biological treatment is performed at a later stage, the biological treatment is adversely affected. Furthermore, since sodium ions, sulfate ions, etc. remain, there is a problem that the quality of treated water is deteriorated.

  In addition, regarding the decomposition treatment method using the activated carbon tower, there is a problem that the activated carbon tower is clogged with slime, turbidity, and the like when the waste water contains organic matter and turbid components.

  On the other hand, the decomposition treatment method in which catalase is added is characterized in that hydrogen peroxide can be decomposed relatively efficiently and without causing problems as compared with the treatment method using sodium bisulfite or activated carbon tower. However, since the decomposition treatment with catalase is a catalytic reaction by an enzyme, a relatively long reaction time is required to continuously decompose hydrogen peroxide. Therefore, if the installation space of the reaction tank is limited and the reaction time (residence time) cannot be increased, a large amount of catalase must be added to continuously decompose hydrogen peroxide. However, there is a problem that the treatment cost is increased and the TOC rise of the treated water due to catalase is caused.

JP 2000-135492 A JP-A 1-111689

  As described above, there is a demand for a method capable of efficiently decomposing hydrogen peroxide when the reaction time (residence time) cannot be sufficiently long because the installation space of the reaction tank is limited.

  The present invention is a method for treating hydrogen peroxide-containing water that can efficiently decompose hydrogen peroxide even when the reaction time (residence time) cannot be sufficiently long due to the limited installation space of the reaction tank. And processing equipment.

The present invention relates to a method for treating hydrogen peroxide-containing water in which catalase is added to raw water containing hydrogen peroxide of 1,000 mg / L or more to decompose hydrogen peroxide, and the reaction zone is divided into a plurality of zones. The raw water is continuously supplied to a multi-stage reaction tank having the following, and catalase produced from a microorganism belonging to the genus Aspergillus is added to a reaction zone where the raw water is first supplied, and the raw water and the catalase are added: This is a method for treating hydrogen peroxide-containing water that is sequentially fed to the reaction zone on the subsequent stage.

Further, at least one established a partition plate into the reactor, by partitioning the reaction vessel in a plurality of reaction zones, Rukoto be processed sequentially to overflow the raw water is preferable.

In the method for treating hydrogen peroxide-containing water, in the reaction zone where the raw water is initially supplied, the concentration x of the added catalase, the enzyme activity z possessed by the catalase, and the hydrogen peroxide concentration y in the raw water However, it is preferable to satisfy | fill following formula (1).
250 ≦ xz / y <2500 (1)

The present invention is also a hydrogen peroxide-containing water treatment apparatus for decomposing hydrogen peroxide by adding catalase to raw water containing hydrogen peroxide of 1,000 mg / L or more , and is divided into a plurality of sections. A multistage reaction tank having a reaction zone; raw water supply means for continuously supplying the raw water to the reaction tank; and catalase produced from a microorganism belonging to the genus Aspergillus in the reaction zone to which the raw water is first supplied. A treatment apparatus for adding hydrogen peroxide, wherein the raw water and the catalase are sequentially fed to a reaction zone on the downstream side.

  In the present invention, raw water containing hydrogen peroxide is continuously supplied to a multistage reaction tank having a reaction zone divided into a plurality of zones, and catalase is added to the reaction zone to which this raw water is first supplied. Therefore, even when the reaction time (residence time) cannot be sufficiently long due to the limited installation space of the reaction tank, the hydrogen peroxide-containing water treatment method and treatment can efficiently decompose hydrogen peroxide. An apparatus can be provided.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  As a result of intensive studies, the present inventors have provided a multi-stage reaction tank having a reaction zone divided into a plurality of sections, continuously supplying raw water containing hydrogen peroxide therein, and this raw water is supplied first. It was found that hydrogen peroxide can be efficiently decomposed by adding catalase to the reaction zone.

  An outline of an example of a hydrogen peroxide-containing water treatment apparatus according to an embodiment of the present invention is shown in FIG. The hydrogen peroxide-containing water treatment apparatus 1 includes a raw water tank 10, a multistage reaction tank 12 having reaction zones 20 and 22 divided into two, and a catalase solution storage tank 14. The reaction tank 12 is divided by a partition plate 24 into a reaction zone 20 on the upstream side of the raw water flow and a reaction zone 22 on the downstream side.

  In the hydrogen peroxide-containing water treatment apparatus 1 of FIG. 1, the outlet of the raw water tank 10 is connected to a reaction zone 20 on the upstream side of the reaction tank 12 by a raw water pipe or the like via a pump 16 that is a raw water supply means. . The outlet of the catalase solution storage tank 14 is connected to the reaction zone 20 on the front stage side by a catalase solution pipe or the like via a pump 18 which is a catalase addition means. A treated water pipe or the like is connected to the outlet of the reaction zone 22 on the rear stage side of the reaction tank 12. In the reaction zones 20 and 22, stirring devices 26 and 28, which are stirring means provided with stirring blades, are installed.

  The operation of the hydrogen peroxide-containing water treatment method and the hydrogen peroxide-containing water treatment apparatus 1 according to this embodiment will be described.

  Raw water containing hydrogen peroxide (hereinafter may be simply referred to as “raw water”) is stored in the raw water tank 10 and then pumped by a pump 16 to the reaction zone 20 on the upstream side of the reaction tank 12 through raw water piping or the like. The liquid is sent. Further, the catalase solution containing catalase at a predetermined concentration stored in the catalase solution storage tank 14 is fed by the pump 18 to the reaction zone 20 on the front stage side of the reaction tank 12 through the catalase solution piping or the like. In the reaction zone 20, the decomposition treatment of hydrogen peroxide with catalase is performed while being stirred by the stirring device 26 (hydrogen peroxide decomposition step). The raw water in which at least a part of the hydrogen peroxide is decomposed in the reaction zone 20 and the hydrogen peroxide concentration is lowered is overflowed, sent to the reaction zone 22 on the rear stage side, and the remaining water while being stirred by the stirring device 28. Hydrogen peroxide is decomposed. Thereafter, the decomposed treated water is discharged out of the system through treated water piping or the like. Thereafter, biological treatment, activated carbon treatment, RO membrane treatment, or the like may be performed on the treated water as necessary.

  By such a method, it is possible to efficiently decompose hydrogen peroxide by adding catalase to the reaction zone 20 where the raw water is first supplied and the peroxide concentration is high. Therefore, the amount of catalase added can be reduced, the processing cost can be reduced, and the increase in TOC of treated water due to catalase can be suppressed.

  In this embodiment, there are no particular restrictions on the method of dividing the reaction tank 12. For example, as shown in FIG. 1, a method may be considered in which at least one partition plate 24 is installed in one reaction tank 12, divided into a plurality of reaction zones, and raw water is sequentially overflowed. As shown in FIG. 2, a plurality of reaction tanks (in FIG. 2, two reaction tanks, that is, an upstream reaction tank 30 and a downstream reaction tank 32) are installed and connected in series. Alternatively, the raw water may be sequentially fed and processed. When the installation space of the reaction tank is limited, a method of dividing one reaction tank into a plurality of reaction zones with a partition plate as shown in FIG. 1 is preferable.

  Although there is no restriction | limiting in particular regarding the division division number of the reaction tank 12, 2-5 divisions are preferable from points, such as reaction efficiency, and 2 divisions are more preferable. If the number of compartments is increased more than necessary, the reaction efficiency may be lowered.

  The sizes of the reaction zones divided into a plurality may be the same or different. From the viewpoint of reaction efficiency and the like, it is preferable that the size of the reaction zone to which raw water is supplied first is the smallest.

  In this embodiment, catalase is added to the reaction zone to which raw water is first supplied, that is, the reaction zone 20 on the front stage in FIG. 1 and the reaction tank 30 on the front stage in FIG. It is not necessary to add catalase to the downstream side of the reaction zone to which raw water is first supplied, that is, the downstream side reaction zone 22 in FIG. 1 and the downstream side reaction tank 32 in FIG.

  Catalase is a metabolic enzyme for detoxifying hydrogen peroxide generated in the body of an organism during the process of oxygen respiration into water and oxygen. Since catalase is an enzyme, that is, a biocatalyst, a large number of hydrogen peroxide molecules can be decomposed by one catalase molecule. Therefore, catalase can decompose hydrogen peroxide with a smaller addition amount than sodium bisulfite. Catalase is an enzyme that specifically decomposes hydrogen peroxide, and most living organisms that breathe oxygen have catalase in their bodies, although their amounts differ. In general, catalase can be used for industrial purposes because it does not deactivate hydrogen peroxide decomposition even when extracted from the living body.

  In order to industrially produce catalase, from the viewpoint of production efficiency, a method of culturing a microorganism excellent in catalase production ability and extracting catalase from the culture solution is preferable. Examples of the catalase derived from microorganisms include catalase produced by bacteria and fungi, and these can be used.

  The type of catalase used is not particularly limited, and catalase produced from a microorganism (hereinafter sometimes referred to as “microorganism-derived catalase”), for example, the genus Aspergillus (also known as the genus Aspergillus, another name): Examples include catalase produced from microorganisms such as Aspergillus, Thermomyces, and Micrococcus. It is known that these microorganism-derived catalases have different properties depending on the types of microorganisms to be produced. For example, catalase produced from Aspergillus niger (accession number: Z23138) exhibits excellent hydrogen peroxide decomposition treatment ability in the pH range of 2-7. Catalase produced from Micrococcus lysodeikticus exhibits an excellent ability to decompose hydrogen peroxide in the pH range of 7-9. Catalase produced from Thermomyces lanuginosus exhibits an excellent ability to decompose hydrogen peroxide even under high temperature (eg, 60 ° C. or higher) environment. Therefore, these catalases can be appropriately selected and used according to the type and situation of raw water.

  Of these, catalase produced from microorganisms of the genus Aspergillus is not easily deactivated even when contacted with a relatively high concentration of hydrogen peroxide, and is not susceptible to reaction inhibition. By adding to the reaction zone having a high concentration, hydrogen peroxide can be efficiently decomposed. Therefore, the amount of catalase added can be reduced, which is preferable.

  Catalase derived from the genus Micrococcus or Thermomyces is subject to reaction inhibition by the high concentration of hydrogen peroxide when the concentration of hydrogen peroxide in the raw water is high, which may reduce the ability to decompose hydrogen peroxide. . Specifically, at a hydrogen peroxide concentration of 5 g / L or more, there may be a significant decrease in the ability to decompose hydrogen peroxide. The reason for this is presumed that the protein constituting catalase is denatured by high concentration of hydrogen peroxide and its enzymatic activity is deactivated or reduced.

  However, catalase derived from Aspergillus is less susceptible to reaction inhibition even in raw water containing hydrogen peroxide at a high concentration of, for example, 5 g / L or more, and hydrogen peroxide decomposition treatment compared to catalase derived from other microorganisms. Ability can be maintained at a high level. Therefore, if catalase derived from Aspergillus is used, hydrogen peroxide is rapidly decomposed even when the amount is significantly lower than that of other microorganism-derived catalase compared to raw water containing hydrogen peroxide at a high concentration. It can be processed. Since the amount of catalase added can be made small, the decomposition treatment of hydrogen peroxide can be performed at low cost. Although it is not clear why Aspergillus-derived catalase can maintain a high level of hydrogen peroxide decomposing ability against high concentrations of hydrogen peroxide, it has a protein structure that is unlikely to be denatured by hydrogen peroxide. Inferred.

  Although it does not specifically limit as a catalase derived from Aspergillus genus, The catalase etc. which are produced from Aspergillus niger (accession number: Z23138) are mentioned. In particular, catalase produced from Aspergillus niger exhibits excellent hydrogen peroxide decomposing ability in the pH range of 2 to 7, and has high decomposing ability for high concentrations of hydrogen peroxide. Hydrogen peroxide can be efficiently decomposed by adding it to the reaction zone having a high peroxide concentration. Therefore, the amount of catalase added can be reduced, which is preferable.

  Catalase derived from the genus Aspergillus can be obtained as a commercial product. Examples of commercially available catalase include Orthosorb EZ-752H (manufactured by Organo Corporation).

  Catalase is preferably stored by being dissolved in a solution such as a buffer so that the enzyme activity can be maintained. Catalase is mixed with stabilizers such as sodium chloride and ethanol, and various additives typified by reducing agents such as sodium bisulfite as a hydrogen peroxide decomposition aid for the purpose of stabilizing its storage. May be.

In this embodiment, in the reaction zone where raw water is first supplied, the concentration x of catalase added to the raw water, the enzyme activity z possessed by the catalase, and the hydrogen peroxide concentration y in the raw water are expressed by the following formula (1). It is preferable to satisfy.
250 ≦ xz / y <2500 (1)
In the formula (1), x represents the concentration (g / L) of catalase added to the raw water. z is a value obtained by converting the number of units of 1 g of catalase from the mass of catalase that decomposes 1 μmol of hydrogen peroxide per minute under a temperature condition of 30 ° C., and the peroxidation of catalase. It represents the enzyme activity (u / g) of catalase, which is the strength of hydrogen decomposition. y represents the hydrogen peroxide concentration (g / L) of the raw water. More preferably, the range is 250 ≦ xz / y <1250.

  The enzyme activity z (u / g) can be determined by the following method. First, 5 mL of a 1/100 mol / L hydrogen peroxide solution (pH 7) is collected in a test tube having a diameter of 30 mm, and immersed in a constant temperature water bath at 30 ° C. to obtain a constant temperature. Thereafter, 1 g of a catalase solution kept at 30 ° C. is added to this hydrogen peroxide solution, reacted for 5 minutes, and the residual hydrogen peroxide concentration after 5 minutes is measured. From the measurement result, the enzyme activity z (u / g) can be determined by determining the concentration of hydrogen peroxide decomposed by catalase.

  In particular, a catalase derived from the genus Aspergillus exhibits a particularly remarkable hydrogen peroxide decomposition rate as compared with catalases derived from other microorganisms when (xz / y) is within the range of the above formula (1). When (xz / y) is less than 250, since the concentration x of catalase is too low, the time required for the hydrogen peroxide decomposition treatment may be longer than the preferred range. Moreover, when (xz / y) is 2500 or more, the concentration x of catalase is high, and not only Aspergillus-derived catalase but also other microorganism-derived catalases exhibit a high hydrogen peroxide decomposition rate. Therefore, the superiority of the Aspergillus-derived catalase that hydrogen peroxide can be rapidly decomposed with a small addition amount is hardly exhibited.

  The pH in the reaction tank 12 is preferably in the range of 2 to 11, more preferably in the range of 5 to 9, from the viewpoint of reaction efficiency.

  The temperature of the liquid in the reaction vessel 12 is preferably in the range of 5 ° C to 80 ° C from the viewpoint of reaction efficiency.

  In the present embodiment, the raw water to be treated is not particularly limited as long as it contains hydrogen peroxide, and examples thereof include waste water discharged from a semiconductor manufacturing process, a food container cleaning process, and the like. .

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail more concretely, this invention is not limited to a following example.

  The hydrogen peroxide-containing water was treated using an experimental apparatus having a reaction vessel partitioned into two reaction zones and a reaction vessel having one reaction zone as shown in FIG.

<Example 1, Comparative Example 4 >
In Example 1 and Comparative Example 4 , a reaction vessel partitioned into two reaction zones was used, and catalase was used as a hydrogen peroxide treatment chemical. The type of catalase used in this example, the experimental conditions, and the method for measuring the hydrogen peroxide concentration are as follows. The results are shown in Table 1.

<Comparative Examples 1-3>
In Comparative Examples 1 and 3, a reaction tank having one reaction zone is used, and as a chemical for hydrogen peroxide treatment, the same catalase as in Example 1 is used in Comparative Example 1, and in place of Catalase in Comparative Example 3, Sodium bisulfite was used. In Comparative Example 2, a reaction vessel partitioned into two reaction zones was used, and sodium bisulfite was used in place of catalase as a treatment chemical for hydrogen peroxide. The results are shown in Table 1.

(Catalase used)
In Example 1 and Comparative Example 1, catalase derived from (a) Aspergillus niger was used.
In Comparative Example 4 , (b) Catalase derived from Thermomyces lanuginosus was used.
The enzyme activities of these two types of catalase were both catalase showing an enzyme activity of about 50,000 (u / g).

(Experimental conditions)
Experimental apparatus: See FIG. 3 Reaction tank: 1 L reaction tank is equally divided into 0.5 L × 2 (Example 1, Comparative Example 4 , Comparative Example 2)
No 1L reactor division (Comparative Examples 1 and 3)
Raw water: Hydrogen peroxide 1,000 (mg / L) solution (simulated drainage)
pH: 7.0
Raw water injection rate: 33 mL / min
Water temperature: 25 (° C)
Reaction time: Example 1, Comparative example 4 , Comparative example 2 Each reaction zone for 15 minutes, 30 minutes in total
Comparative Examples 1 and 3 30 minutes Chemicals used: (Example 1, Comparative Example 1) Aspergillus niger-derived catalase
( Comparative Example 4 ) Thermolyces lanuginosus-derived catalase
Comparative Examples 2 and 3 Bisulfite Na
Catalase enzyme activity: about 50,000 (u / g)
Chemical solution concentration: (Example 1, Comparative Example 4 ) 2,500 mg / L
(Comparative Example 1) 20,000 mg / L
(Comparative Examples 2 and 3) 100,000 mg / L
Chemical solution injection rate: Example 1 1.0 mL / min (catalase 73.5 mg / L)
Comparative Example 4 1.7 mL / min (catalase 122 mg / L)
Comparative Example 1 1.0 mL / min (catalase 588 mg / L)
Comparative Examples 2, 3 1.05 mL / min (Na bisulfite 3,083 mg / L)
Evaluation item: Addition amount of chemicals required to make the overwater concentration of treated water 10 (mg / L)

(Measurement method of hydrogen peroxide concentration)
The hydrogen peroxide concentration was determined by an iodometric titration method. The iodine titration method is shown below. First, an appropriate amount (about 5 mL) of a sample was taken into a test tube, and 2 mL of 1N sulfuric acid solution, 1 mL of 10% potassium iodide solution, and 1 drop (about 0.05 mL) of 1% ammonium molybdate solution were added thereto. . Thus, iodine liberated by the action of residual hydrogen peroxide under sulfuric acid acidity was titrated with a 1 / 100N sodium thiosulfate solution. Based on the titration value obtained by titration, the residual hydrogen peroxide concentration was determined using the following formula.
Residual hydrogen peroxide concentration = ((Titration value (mL)-Blind value)) x 170 / Sample volume (mL)

Thus, in Example 1 and Comparative Example 4 in which catalase was added to the reaction zone to which raw water was first supplied using a multistage reaction tank having a plurality of partitioned reaction zones, a small amount of catalase was used. Thus, hydrogen peroxide was efficiently decomposed. In particular, in Example 1 using catalase produced from a microorganism belonging to the genus Aspergillus, hydrogen peroxide could be efficiently decomposed with a smaller amount of catalase used.

It is a schematic block diagram which shows an example of the hydrogen peroxide containing water processing apparatus which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the hydrogen peroxide containing water processing apparatus which concerns on embodiment of this invention. It is a schematic block diagram which shows the experimental apparatus used in the Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Hydrogen peroxide containing water processing apparatus, 10 Raw water tank, 12 Reaction tank, 14 Catalase solution storage tank, 16, 18 pump, 20 Upstream reaction zone, 22 Downstream reaction zone, 24 Partition plate, 26, 28 Stirrer , 30 upstream reaction tank, 32 downstream reaction tank.

Claims (4)

A method for treating hydrogen peroxide-containing water comprising adding catalase to raw water containing hydrogen peroxide of 1,000 mg / L or more to decompose hydrogen peroxide,
The raw water is continuously supplied to a multistage reaction tank having a reaction zone divided into a plurality of zones, and catalase produced from a microorganism belonging to the genus Aspergillus is added to the reaction zone to which the raw water is first supplied,
A method for treating hydrogen peroxide-containing water, wherein the raw water and the catalase are sequentially fed to a reaction zone on the downstream side. A method for treating hydrogen peroxide-containing water according to claim 1,
A method for treating hydrogen peroxide-containing water, characterized in that at least one partition plate is installed in the reaction tank, the reaction tank is partitioned into a plurality of reaction zones, and the raw water is sequentially overflowed for treatment. A method for treating hydrogen peroxide-containing water according to claim 2,
In the reaction zone where the raw water is initially supplied, the concentration x of the added catalase, the enzyme activity z of the catalase, and the hydrogen peroxide concentration y in the raw water satisfy the following formula (1): A method for treating hydrogen peroxide-containing water.
250 ≦ xz / y <2500 (1) A hydrogen peroxide-containing water treatment apparatus for decomposing and treating hydrogen peroxide by adding catalase to raw water containing 1,000 mg / L or more of hydrogen peroxide,
A multistage reaction tank having a reaction zone divided into a plurality of zones;
Raw water supply means for continuously supplying the raw water to the reaction tank;
A catalase addition means for adding a catalase produced from a microorganism belonging to the genus Aspergillus to the reaction zone to which the raw water is first supplied;
With
The apparatus for treating hydrogen peroxide-containing water, wherein the raw water and the catalase are sequentially fed to a reaction zone on the downstream side.

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