WO2003053864A1

WO2003053864A1 - Apparatus for treating waste water containing hydrogen peroxide

Info

Publication number: WO2003053864A1
Application number: PCT/JP2002/013353
Authority: WO
Inventors: Kazuya Uesugi; Teruo Sugizaki
Original assignee: Organo Corporation
Priority date: 2001-12-21
Filing date: 2002-12-20
Publication date: 2003-07-03
Also published as: AU2002354263A1; TWI226311B; KR20040067838A; TW200301227A; JP3894788B2; JP2003190972A; CN1633395A; CN1275876C

Abstract

An apparatus for treating a waste water containing hydrogen peroxide which passes the waste water upwardly through a reaction tower (2) packed with a hydrogen peroxide decomposition catalyst, to decompose hydrogen peroxide into oxygen and water, wherein plural catalyst layers, for example, a lower catalyst layer (8) and an upper catalyst layer (14) are provided in the perpendicular direction in the reaction tower (2), and a gas purging tube (20) is disposed in the reaction tower (2) for purging an oxygen gas generated at least in the lowermost catalyst layer to the outside of the reaction tower (2) without contacting the oxygen gas with a catalyst layer disposed at a position upper than that of the lowermost layer. The apparatus allows the enhancement of the contact efficiency of the catalyst with hydrogen peroxide, which leads to miniaturization of an apparatus, space-saving and the reduction of equipment cost.

Description

Specification

Wastewater treatment equipment containing hydrogen peroxide

"Technical field to which the invention belongs"

The present invention relates to an apparatus for treating various hydrogen peroxide-containing wastewater such as semiconductor manufacturing wastewater and food container cleaning wastewater.

"Background technology"

Hydrogen peroxide is a clean chemical that excels in cleaning and disinfecting effects, and decomposes into oxygen and water after the reaction. Therefore, it is widely used as a detergent and disinfectant in manufacturing processes. For example, in a semiconductor device manufacturing plant, hydrogen peroxide is used for cleaning wafers in various processes.

Hydrogen peroxide used for cleaning and sterilization is discharged as waste liquid (water containing hydrogen peroxide) from the manufacturing process. It is not desirable to discharge this waste liquid directly into public waters because it has bactericidal activity and causes COD.

Conventionally, wastewater containing hydrogen peroxide has been treated with a reducing agent such as sodium sulfite or an enzymatic agent such as peroxidase.However, these methods use a large amount of chemicals and run. The high cost was a problem. On the other hand, a method of reducing hydrogen peroxide using a reducing catalyst such as activated carbon, a manganese-supported catalyst, or a platinum-supported catalyst is known. Hydrogen peroxide in wastewater is decomposed into oxygen and water by contacting the above reduction catalyst. By using such a treatment method using a reduction catalyst, the running cost required for treating hydrogen peroxide-containing wastewater can be reduced.

The treatment of wastewater containing hydrogen peroxide using a reduction catalyst has the advantages described above, but this treatment requires a relatively large-scale treatment facility as compared to treatment using a reducing agent and an enzyme agent. was there.

"Disclosure of the invention"

In the present invention, a hydrogen peroxide decomposition catalyst (reduction catalyst) capable of performing an efficient treatment was used. Provided is a treatment device for wastewater containing hydrogen peroxide.

The present invention relates to a treatment apparatus for decomposing hydrogen peroxide into oxygen and water by flowing hydrogen peroxide-containing wastewater in an upward flow through a reaction tower filled with a hydrogen peroxide decomposition catalyst. The hydrogen peroxide decomposition catalyst is divided into a plurality of layers in the vertical direction in the reaction tower, and is arranged without contacting at least the oxygen gas generated in the lowermost catalyst layer with the upper catalyst layer. A gas vent pipe to be discharged outside the reaction tower is installed inside the reaction tower.

This makes it possible to effectively decompose hydrogen peroxide. "Brief description of the drawings"

FIG. 1 is a schematic diagram showing an embodiment of a wastewater treatment apparatus containing hydrogen peroxide according to the present invention.

FIG. 2 is a plan view showing an upper catalyst support plate of the apparatus of FIG.

FIG. 3 is a schematic diagram of the experimental apparatus A used in the experimental example.

FIG. 4 is a schematic diagram of the experimental apparatus B used in the experimental example.

"Preferred embodiment for carrying out the invention"

First, in order to complete the present invention, the present inventors conducted TJ studies described in the following ① to ④.

(1) In a reaction system using a catalyst, the reaction efficiency is generally increased by improving the contact efficiency between the catalyst and the reaction target (in the present invention, hydrogen peroxide in water). Costs can be reduced.

(2) On the other hand, in a hydrogen peroxide-containing wastewater treatment system using a reduction catalyst, hydrogen peroxide-containing wastewater is continuously passed through the reaction tower filled with the catalyst in an upward or downward flow, and It is common to obtain treated water from the lower part. However, when high-concentration hydrogen peroxide is decomposed, a large amount of oxygen gas is generated, which generates air bubbles and is trapped in the packed bed. From the viewpoint of safety, it is desirable to select an upward flow that allows easy release of gas from the upper part of the reaction tower.

③However, the bubbles of oxygen gas generated during decomposition of hydrogen peroxide cause the contact between catalyst and hydrogen peroxide. It is thought that the contact efficiency is reduced, and as a result, the reaction efficiency of the processing apparatus is reduced. In particular, when treating wastewater containing a high concentration of hydrogen peroxide, it is desirable to use an upward flow type reaction tower for the above-mentioned reasons.However, the process in which generated oxygen gas bubbles rise in the catalyst layer It is presumed that air bubbles hinder contact between the catalyst and the wastewater.

Therefore, the present inventors studied a method for preventing the generated bubbles of oxygen gas from inhibiting the contact between the catalyst and hydrogen peroxide. As a result, in a reaction tower that treats hydrogen peroxide-containing wastewater in an upward flow, the catalyst is divided into multiple layers in the vertical direction in the reaction tower, and the oxygen gas generated in the lower catalyst layer is removed. By discharging the bubbles out of the reaction tower without contacting the upper catalyst layer, the upper catalyst layer contacts the catalyst with hydrogen peroxide without being disturbed by the oxygen gas bubbles generated in the lower catalyst layer. Was found, and as a result, the hydrogen peroxide removal rate in the reaction tower was improved. At this time, it was found that by installing an oxygen gas discharge pipe in the reaction tower, it was possible to satisfactorily discharge the oxygen gas generated in the catalyst layer.

The apparatus according to the present embodiment is a treatment apparatus that decomposes hydrogen peroxide into oxygen and water by flowing hydrogen peroxide-containing wastewater in an upward flow through a reaction tower filled with a hydrogen peroxide decomposition catalyst. The hydrogen peroxide decomposition catalyst is vertically divided into a plurality of layers in the reaction tower, and at least oxygen gas generated in the lowermost catalyst layer is transferred to the upper catalyst layer. A gas vent pipe that discharges outside the reaction tower without contact is installed inside the reaction tower.

In this case, the number of layers of the hydrogen peroxide decomposition catalyst can be determined as appropriate, but it is usually appropriate to divide the catalyst into two to four layers, particularly two layers.

Further, in the processing apparatus of the present embodiment, since the amount of oxygen gas generated in the lowermost catalyst layer is the largest, a gas vent pipe for discharging at least bubbles of oxygen gas generated in the lowermost catalyst layer to the outside of the reaction tower. Although it is more appropriate to provide a gas vent pipe for discharging the gas generated in each catalyst layer to the outside of the reaction tower.

The oxygen gas should be discharged from the gas vent tube to such an extent that the generated oxygen gas bubbles can be effectively prevented from obstructing the contact between the catalyst and hydrogen peroxide in the upper catalyst layer. Therefore, it is not always necessary to discharge all of the gas generated in the catalyst layer, but part of the gas may be discharged. In the present embodiment, the type of hydrogen peroxide decomposition catalyst is not limited, and any catalyst can be used as long as it can reduce hydrogen peroxide to decompose it into oxygen and water. Specific examples of the hydrogen peroxide decomposition catalyst include metal catalysts such as platinum, palladium, and manganese; and activated carbon. Further, a catalyst in which a metal such as platinum, palladium, or manganese is supported on a base made of activated carbon, alumina, silica, or the like can also be used.

Further, in the present embodiment, the catalyst loading amount in each of the catalyst layers divided into a plurality of layers in the vertical direction depends on the concentration of hydrogen peroxide in the wastewater, the flow rate of the wastewater, and the target removal of hydrogen peroxide. Each can be set arbitrarily in consideration of the rate and the like. It is also possible to fill each catalyst layer with a different type of catalyst.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing an embodiment of a wastewater treatment apparatus containing hydrogen peroxide according to the present invention. In FIG. 1, the reaction tower 2 is formed, for example, in a cylindrical shape. The raw water supply pipe 4 is fixed to the bottom of the reaction tower 2 by being inserted from the outside. A support gravel layer 6 is provided at the bottom of the reaction tower 2, and the raw water supply pipe 4 is opened in the support gravel layer 6. On the support gravel layer 6 in the reaction tower 2, a lower catalyst layer 8, an upper catalyst support plate 10, a support gravel layer 12, and an upper catalyst layer 14 are sequentially formed in this order. The supporting gravel layers 6 and 12 support the lower catalyst layer 8 and the upper catalyst layer 14, respectively, and have a larger particle size than the catalyst particles constituting the lower catalyst layer 8 and the upper catalyst layer 14. It is composed of

An L-shaped treated water discharge pipe 16 having an open upper end is provided above the upper catalyst layer 14 to overflow and discharge treated water (supernatant water) in the reaction tower 2. Further, a gas outlet 18 for discharging the internal gas is provided at the upper end of the reaction tower 2. A gas vent pipe 20 is provided to penetrate the upper catalyst support plate 10, the support gravel layer 12, and the upper catalyst layer 14 of the reaction tower 2. The gas vent tube 20 has a lower end supported by an upper catalyst support plate 10 and an upper end supported by a gas vent tube support 22 disposed above the reaction tower 2.

Here, the upper catalyst support plate 1◦ supporting the gravel layer 12 and the upper catalyst layer 14 has eight water collecting ports (collector screens) 24 and four gas vent ports 2 as shown in Fig. 2. 6 are provided, and each gas vent 2 The lower end of 0 is connected. That is, in FIG. 1, only one gas vent pipe 20 is shown, but the gas vent pipes 20 are provided corresponding to the gas vent ports 26, and in this apparatus, a total of four gas vent pipes 20 are provided. Draft 20 is installed. Further, these gas vent pipes 20 pass through the upper catalyst layer 14 and open above the treated water level 30 at the top of the tower. That is, the upper end of the degassing pipe 20 is located above the upper end opening of the treated water discharge pipe 16. The upper catalyst support plate 10 is disposed above the lower catalyst layer 8, and a space 32 is formed between the lower catalyst layer 8 and the upper catalyst support plate 10. .

As described above, in this apparatus, the catalyst layer is divided into the upper and lower layers (the lower catalyst layer 8 and the upper catalyst layer 14) and arranged in the reaction tower 2, and the gas vent pipe bypassing the upper catalyst layer 14 is provided. 20 are provided.

In such a device, the hydrogen peroxide-containing wastewater 28 is supplied from the raw water supply pipe 4 to the lower part of the reaction tower 2. A support gravel layer 6 is provided at the lower part of the reaction tower 2, and the hydrogen peroxide-containing wastewater spreads throughout the bottom of the reaction tower 2 in the support gravel layer 6 _{c as} described above. A support plate 10 for the upper catalyst layer 14 is provided on the lower surface, a space 32 is formed below the support plate 10, and the lower catalyst 10 is provided on the support plate 10 as described above. A gas vent 26 for collecting oxygen gas generated from the layer 8 is provided. The gas vent port 26 is connected to a gas vent pipe 20 extending above the upper catalyst layer 8 above the reaction tower 2. Therefore, a part or all of the oxygen gas generated in the lower catalyst layer 8 passes through the gas vent port 26 of the support plate 10, passes through the gas vent pipe 20, and flows above the upper catalyst layer 14. And is discharged out of the system without contacting the catalyst in the upper catalyst layer 14.

The support plate 10 in the middle stage of the reaction tower is provided with a water collecting port 24 for guiding wastewater to the upper catalyst layer 14 separately from the gas venting port 26, and a part or all of the generated gas is removed. The drained water is passed through the water collecting port 24 into the upper catalyst layer 14, and the hydrogen peroxide in the drain is further reduced and decomposed. The oxygen gas generated in the upper catalyst layer 14 is discharged upward as it is. The wastewater that has passed through the upper catalyst layer 14 reaches the water surface 30 at the top of the tower, and is discharged out of the reaction tower 2 from the treated water discharge pipe 16. Oxygen gas from the lower catalyst layer 8 guided upward through the water surface through the gas vent pipe 20, and the upper catalyst layer 14 Oxygen gas is discharged out of the reaction tower 2 from the gas outlet 18 at the top of the tower.

This system treats wastewater containing hydrogen peroxide in an upward flow direction. In the reactor, the catalyst is divided into two layers (lower catalyst layer 8 and upper catalyst layer 14) in the vertical direction, and is arranged. A space 32 is formed between both layers, and oxygen gas generated in the lower catalyst layer 8 is discharged out of the reaction tower 2 without contacting the upper catalyst layer 14. As a result, the upper catalyst layer 14 makes contact between the catalyst and hydrogen peroxide without being hindered by the oxygen gas generated in the lower catalyst layer 8, and as a result, the hydrogen peroxide removal rate in the reaction tower 2 is improved. .

In particular, in this apparatus, the wastewater containing hydrogen peroxide is treated in an upward flow, so that the generated oxygen gas easily escapes above each catalyst layer. Further, a vent pipe 20 for discharging the generated oxygen gas is provided in the reaction tower 2. When the gas vent pipe 20 is installed outside the reaction tower 2, that is, when the gas vent pipe 20 is externally connected to the peripheral wall between the upper catalyst layer 14 and the lower catalyst layer 8 of the reaction tower 2, In comparison, the oxygen gas generated in the lower catalyst layer is discharged well out of the system.

In this device, the number of gas vents 26 and water collecting ports 24 provided on the support plate 10 and their locations can be arbitrarily set as long as the strength of the support plate 10 is sufficiently maintained. . In this case, since the gas rise causes an air lift effect on water in the gas vent pipe 20, it is necessary to design the pipe diameter so that the drain below the support plate does not reach the upper water surface through the gas vent pipe due to the air lift . In addition, it is appropriate that the water collecting port 24 has a diameter smaller than the size of the catalyst or a mesh-shaped or comb-shaped screen is provided so that the catalyst in the upper catalyst layer 14 does not fall downward.

It is also preferable that the lower end opening position of the gas vent port 26 of the support plate 10 is located above the lower end opening position of the water collecting port 24. The support plate 10 is not a flat plate but a shape that faces upward toward the gas vent 26 (shape of an inverted funnel), or a pipe-like member extending downward around the water intake 24 is attached. By doing so, the lower end of the gas vent 26 can be positioned below the water intake 24. (Experimental example)

An experimental example will be described below.

The experimental device A shown schematically in FIG. 3 and the experimental device B schematically shown in FIG. The effect of Ming was verified. That is, two sets of reaction towers of the same shape were prepared, A and B. Experimental apparatus A degassed in the middle stage according to the present embodiment, experimental apparatus B did not degas, and other conditions were completely different. Simulated hydrogen peroxide-containing wastewater was passed in the same manner. In experimental machines A and B shown in Figs. 3 and 4, reference numeral 42 denotes a reaction tower, 44 denotes a raw water supply pipe, 46 denotes a lower catalyst layer, 48 denotes an upper catalyst support plate, 50 denotes an upper catalyst layer, and 52 denotes a treated water discharge pipe. Numeral 54 denotes a gas vent pipe connected to the gas vent of the support plate 48 (installed only in the experimental machine A), and numeral 56 denotes a water collecting port formed in the support plate 48. The specifications of experimental units A and B are shown below.

Experiment machine A

Degassing mechanism: Yes

Degassing mechanism specifications

Gas vent port: 1 piece (center of support plate, diameter 15 mm)

Experiment machine B

Degassing mechanism: None

Common specifications for experimental units A and B

Reaction tower diameter: 70mm

Hydrogen peroxide decomposition catalyst used: manganese supported catalyst

Catalyst filling height: 500mm each for upper and lower

Catalyst filling amount: 192mL each for upper and lower

Water inlets: 6 (diameter 2 mm)

Flow rate: 770 mL / hr, 1540 mL / hr r 3080 mL / hr Flow rate: SV = 2 / hr, 4 / hr 8 / hr

Simulated wastewater: Hydrogen peroxide concentration: 2000 Omg / L (Dissolve the reagent hydrogen peroxide solution in pure water, adjust to pH = 10.5 with sodium hydroxide aqueous solution) Table 1 shows the hydrogen peroxide concentration and the hydrogen peroxide removal rate of the treated water of the experimental machine. As shown in Table 1, the concentration of hydrogen peroxide in the treated water and the removal rate of hydrogen peroxide in Experimental Unit A were all higher than those in Experimental Unit B in each water flow condition. That is, by guiding a part or all of the oxygen gas generated from the lower catalyst layer to the outside of the system from the middle stage of the reaction tower so as not to reach the upper catalyst layer, the same catalyst amount and It was confirmed that the quality of the treated water and the removal rate of hydrogen peroxide were improved under the water flow conditions.

table 1

Water flow results (lower limit of hydrogen peroxide measurement: 0.1 mg / L)

As described above, the hydrogen peroxide-containing wastewater treatment device of the present embodiment is intended to increase the contact efficiency between the hydrogen peroxide decomposition catalyst and hydrogen peroxide, to reduce the size of the device, save space, and reduce equipment costs. Can be.

Claims

The scope of the claims

1. A treatment device for flowing hydrogen peroxide-containing wastewater in an upward flow through a reaction tower filled with a hydrogen peroxide decomposition catalyst to decompose hydrogen peroxide into oxygen and water, wherein the hydrogen peroxide decomposition catalyst Is divided into a plurality of layers in the vertical direction in the reaction tower, and at least the oxygen gas generated in the lowermost catalyst layer is discharged out of the reaction tower without contacting the catalyst layer above it A wastewater treatment device containing hydrogen peroxide with a gas vent tube installed in the reaction tower.

2. The hydrogen peroxide-containing wastewater treatment device according to claim 1,

A hydrogen peroxide-containing wastewater treatment apparatus in which a gas vent pipe for discharging gas generated in each catalyst layer to the outside of the reaction tower without contacting the catalyst layer above the catalyst layer is installed in the reaction tower.

3. The hydrogen peroxide-containing wastewater treatment apparatus according to claim 2,

A hydrogen peroxide-containing wastewater treatment device, wherein a lower end of the degassing pipe is supported at a lower end by a support plate that supports an upper catalyst layer that does not contact the gas.

4. The wastewater treatment device containing hydrogen peroxide according to claim 3,

The hydrogen peroxide-containing wastewater treatment device, wherein a lower end of the gas vent pipe is connected to a gas vent provided in the support plate.

5. The wastewater treatment device containing hydrogen peroxide according to claim 4, wherein

There is a space between the upper end of the lowermost catalyst layer and the support plate, through which gas generated in the lowermost catalyst layer is collected, and hydrogen peroxide collected in the degassing pipe Contained wastewater treatment equipment.

6. The wastewater treatment device containing hydrogen peroxide according to claim 4,

A hydrogen peroxide-containing wastewater treatment device, wherein the support plate is provided with a water collection port for guiding wastewater from below to an upper catalyst layer.

7. The hydrogen peroxide-containing wastewater treatment apparatus according to claim 4,

A hydrogen peroxide-containing wastewater treatment device, wherein an upper end of the gas vent pipe is open on a water surface in a reaction tower.