JP2004136194A - Waste water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method for reducing COD (chemical oxygen demand), TOC (total organic carbon), a total nitrogen concentration of waste water containing oxidizable substances such as various organic substances, ammonia, hydrazine, and organic suspended substances. <P>SOLUTION: The waste water is electrolytically treated under conditions that electrolytic reactors 1-3 to use conductive diamond electrodes 111-113 are installed in series at plural stages and current densities of the electrolytic reactors of respective stages are set to different conditions. The areas of the electrodes 111-113 of the respective electrolytic reactors 1-3 may be determined to be larger at a preceding stage than at a subsequent stage, and the distances between the electrodes may be determined to be larger at the preceding stage than at the subsequent stage. The electrodes 111-113 of the respective electrolytic reactors 1-3 may be energized through connection in series. Oxidizable substances may include organic suspended substances and organic substances to cause gas accompanied by electrolytic reaction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for treating wastewater containing oxidizable substances such as various organic substances, ammonia, hydrazine, and organic suspended substances, and particularly to a chemical oxygen demand (COD) or total organic carbon (TOC) of the wastewater. And a treatment method capable of reducing the total nitrogen concentration.
[0002]
[Prior art]
Conventionally, as a method of treating wastewater containing oxidizable substances such as various organic substances, ammonia, and hydrazine, electrolytic treatment is performed using a platinum-based electrode having iridium oxide supported on its surface, followed by a nickel peroxide-based catalyst or a peroxide catalyst. A method of treating by bringing it into contact with a cobalt oxide-based catalyst has been put to practical use (see “Thermal Nuclear Power Generation” 51 (12), 1711 (2000), JP-A-10-174976, JP-A-11-216473, etc. ).
A method of electrolytically treating wastewater containing an oxidizable substance using a conductive diamond electrode instead of the platinum-based electrode has also been proposed (see Japanese Patent Application No. 2002-24529).
[Patent Document 1] Japanese Patent Application Laid-Open No. Hei 10-174976 [Patent Document 2] Japanese Patent Application Laid-Open No. Hei 11-216473 [Non-Patent Document 1] “Thermal Nuclear Power Generation” 51 (12), 1711 (2000)
[0003]
[Problems to be solved by the invention]
However, if suspended matter coexists in the wastewater, the suspended matter accumulates in the electrolytic reaction tank, causing a short circuit between the two electrodes, causing troubles, or increasing the resistance between the electrodes and lowering the current efficiency. In some cases.
Therefore, these suspended substances must be separated and removed before introducing the wastewater into the electrolytic reaction tank, and a separate device and time are required for separation and removal. The cost required for processing was enormous.
[0004]
Therefore, the present invention eliminates the need for an apparatus and time for separating and removing suspended substances even in wastewater in which suspended substances coexist, and removes oxidizable substances more than the conventional treatment method described above. It is an object of the present invention to provide a method for treating wastewater containing an oxidizable substance and a suspended substance, which has high efficiency and high reduction efficiency of COD and TOC concentrations.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a drainage method of the present invention is a method of electrolytically treating wastewater containing an oxidizable substance and an electrolyte substance by using a conductive diamond electrode, wherein a plurality of electrolytic reaction tanks are connected in series. It is characterized in that the electrolytic treatment is performed by setting the current density of the electrode of each stage of the electrolytic reaction tank under different conditions.
The area of the conductive diamond electrode in each of the electrolytic reaction tanks may be set so that the former is greater than the latter, or the distance between the electrodes may be set so that the former is greater than the latter.
In addition, it is preferable that the conduction to the conductive diamond electrode in each electrolytic reaction tank is performed by connecting them in series.
[0006]
The wastewater to be treated according to the present invention contains oxidizable substances and electrolyte substances, and may be industrial wastewater discharged from various factories, domestic wastewater, or other wastewater.
Examples of the oxidizable substance in the wastewater include various organic substances, ammonia, hydrazine, and the like. In the present invention, a preferable effect is obtained by applying to the wastewater containing at least one of these organic substances, ammonia, and hydrazine. Can be. The concentration of these oxidizable substances in the wastewater is not particularly limited, and can be preferably applied to wastewater containing various concentrations of the oxidizable substances.
[0007]
Further, the oxidizable substance may include a hardly soluble or insoluble polycarboxylic acid resin, a polyamino acid resin, and an organic suspending substance such as a surfactant, or may include methanol, ethanol, acetone, acetic acid, It may contain an organic substance such as monoethanolamine, diethanolamine, diisopropanolamine, monoethylamine, and triethylamine, which generates a gas with an electrolytic reaction.
In the case where an organic substance that generates a gas in association with the electrolytic reaction is contained, it is preferable that the gas generated in the electrolytic reaction be removed and then introduced into a subsequent electrolytic reaction tank.
The COD and TOC of the wastewater containing the oxidizable substance as described above are not particularly limited. However, the method of the present invention has a COD of 500 mg / L or more, a TOC of 200 mg / L or more, and more preferably a COD of 1000 mg, in terms of current efficiency. / L or more, TOC 400 mg / L or more, more preferably COD 3000 mg / L or more, and TOC 1100 mg / L or more. The COD and TOC upper limits are not particularly limited, but generally 300,000 mg / L. L and TOC of about 1,000,000 mg / L.
[0008]
On the other hand, the electrolyte substance may be any substance, but is generally an inorganic compound, for example, NaCl, H ₂ SO ₄ , Na ₂ SO ₄ or the like is preferable, and these may be used alone. However, two or more types may be used in an appropriate combination.
The concentration of these electrolyte substances in the wastewater is not particularly limited, and may be about 50 to 50,000 mg / liter (hereinafter, liter is described as L and milliliter is described as mL) necessary for conventional electrolytic treatment, Even if it is less than 6,000 mg / L, which is extremely poor in the conventional electrolytic treatment, it can be treated efficiently.
That is, in the conventional method using a platinum-based electrode carrying an iridium oxide surface, the electrolyte substance that functions to increase the current efficiency during the electrolysis treatment requires an electrolyte substance (NaCl) concentration of 6,000 mg / L or more. On the other hand, in the present invention using a conductive diamond electrode capable of improving current efficiency, a sufficient processing effect can be obtained even in a low concentration region of less than 6,000 mg / L.
However, even in the present invention using a conductive diamond electrode, if the concentration of the electrolyte substance is too low, sufficient current efficiency may not be obtained for electrolyzing the oxidizable substance in the wastewater in some cases. Therefore, the preferred concentration of the electrolyte substance in the present invention varies depending on the concentration of the oxidizable substance in the target wastewater, but is about 500 to 6,000 mg / L for the above wastewater.
[0009]
The above-mentioned electrolyte substance may be contained in the above-mentioned wastewater, and if the above-mentioned electrolyte substance concentration alone can secure the above-mentioned electrolyte substance concentration, it is not necessary to separately add an electrolyte substance.
When the above-mentioned electrolyte substance concentration cannot be secured only by the contained electrolyte substance, an amount of the electrolyte substance capable of securing the above-mentioned electrolyte substance is introduced prior to the treatment of the present invention.
[0010]
The conductive diamond electrode used in the present invention is formed by using a conductive metal material such as Ni, Ta, Ti, Mo, W, or Zr as a substrate and depositing a conductive diamond thin film on the surface of the substrate, or a silicon wafer. And the like, and a conductive polycrystalline diamond material prepared by forming a conductive diamond thin film on the surface of a wafer using a semiconductor material such as a substrate, or a plate-like synthetic material without using a substrate.
The conductive (polycrystalline) diamond thin film is obtained by doping a predetermined amount of boron or nitrogen during the preparation of the diamond thin film to impart conductivity, and is generally doped with boron.
If the doping amount is too small, the technical significance of the doping is not exhibited, and if it is too large, the doping effect is saturated. Therefore, the doping amount in the range of 50 to 20,000 ppm with respect to the carbon amount of the diamond thin film material is suitable. ing.
[0011]
In the present invention, a plate-shaped conductive diamond electrode is generally used, but a plate-shaped network structure can also be used.
[0012]
In addition, a material obtained by covering the surface of carbon powder or another powdery material with a conductive diamond thin film can be used as an electrode. When this powdery diamond electrode is used, for example, a powdery diamond electrode is dispersed in an electrolytic solution and fluidized to form a fluidized bed, and a pair of this fluidized bed is made to act as a cathode and an anode. Just fine.
The electrode area in the case where the fluidized bed is used as an electrode is theoretically the entire area in contact with the wastewater, but the present invention is not limited to this, and the area of the flush surface facing the counter electrode is sufficient. is there.
[0013]
Further, a substrate having a porous body, or a porous body made of a synthetic resin or the like and having conductive diamond powder supported thereon to form an electrode having a high surface area can also be used. A fixed bed may be constituted by electrodes having a surface area, and a pair of the fixed beds may be used as a cathode and an anode.
The electrode area when this fixed bed is used as an electrode is also theoretically the entire area that comes into contact with the drainage. However, the present invention is not limited to this, and the area of the same surface facing the counter electrode is sufficient. is there.
[0014]
In the present invention, an electrolytic reaction tank using the conductive diamond as described above for both the negative and positive electrodes is installed in a plurality of stages in series, and the electrolytic treatment is performed by setting the current density of each stage of the electrolytic reaction tank to different conditions. .
The conditions having different current densities are, for example, such that the current density of the electrolytic reaction tank from the first stage to the n-th stage is gradually increased, vice versa, or randomly. Alternatively, the quality of the outlet water of each electrolytic reaction tank is monitored to make the current density optimal for the next electrolytic reaction tank.
In the present invention, in the first stage, the wastewater contains a large amount of the oxidizable substance to be electrolyzed, so that it is preferable to use an electrode having a large area. Since the amount of the substance is small, there is no problem even if an electrode having a small area is used. In addition, since it is preferable that the current is supplied in series from the first stage to the last stage, the current density gradually increases toward the later stage. It is preferable that the setting is made as follows.
[0015]
The current density at this time may be set differently in the above-described manner for each stage within the range of 10 to 100,000 A / m ² in terms of the current density on the surface of the conductive diamond electrode.
[0016]
Further, in the present invention, the area of the conductive diamond electrode in each electrolytic reaction tank may be such that the former is greater than the latter.
For example, the electrode area of the electrolytic reaction tank from the first stage to the n-th stage is gradually reduced from the first stage> the second stage> the third stage> to the n-th stage. To be.
When a conductive diamond electrode is used, the current density on the electrode surface can be increased to perform the electrolytic treatment of the wastewater as compared with the case of using a conventional platinum electrode or a iridium oxide surface-supported platinum-based electrode. Although the area is small and the equipment can be made compact, a large amount of oxidizable substances can be electrolyzed in the previous stage of the electrolytic reaction tank, where wastewater containing a large amount of oxidizable substances is introduced, in order to conduct electrolytic treatment with high efficiency. Even a conductive diamond electrode requires a certain electrode area. In a subsequent electrolytic reaction tank for treating wastewater from which a considerable amount of oxidizable substances has been removed, sufficient treatment efficiency can be obtained even with a small electrode area.
[0017]
In order to reliably obtain such an electrolytic treatment effect, the degree of reduction in the electrode area varies depending on the number of electrolytic reaction tanks (the number of treatment stages). The second stage is smaller than the second stage by about 10 to 60%, preferably about 10 to 35%, and the third stage is smaller than the second stage by about 10 to 60%, preferably about 10 to 50%. As described above, it is preferable that the size of the subsequent stage is smaller by about 10 to 60% than that of the preceding stage.
The specific electrode area varies depending on the amount of the oxidizable substance in the wastewater, the treatment amount (treatment capacity) of the wastewater, and the like, and thus cannot be unconditionally determined.
[0018]
Further, in the present invention, the distance between the electrodes of the conductive diamond electrode in each electrolytic reaction tank may be such that the former stage> the latter stage.
For example, the distance between the electrodes of the electrolytic reaction tank from the first stage to the n-th stage is gradually reduced from the first stage> the second stage> the third stage to the n-th stage. To be.
[0019]
As described above, when the conductive diamond electrode is used, the current density on the electrode surface can be increased to perform the electrolytic treatment of the wastewater, as compared with the case of using the conventional platinum electrode or the iridium oxide surface-supported platinum-based electrode. Although the required electrode area can be reduced and the device can be made compact, the overvoltage is high and the voltage between the electrodes is high.
In order to increase energy efficiency, it is common to minimize the distance between electrodes.However, in an electrolytic reaction tank with a reduced distance between electrodes, if there is an organic suspended substance in the wastewater to be treated, clogging may occur. This causes a short circuit between the electrodes.
Therefore, in the present invention, in the electrolytic reaction tank at the stage before the wastewater in which a large amount of the organic suspended substance is present is introduced, the distance between the electrodes is increased to prevent the short-circuit between the electrodes due to the organic suspended substance while the organic suspended Is electrolytically removed, and the distance between the electrodes is reduced in the latter stage of the electrolytic reaction tank into which the wastewater with reduced organic suspended matter is introduced, thereby improving energy efficiency.
[0020]
In order to reliably obtain such an effect of preventing a short circuit between electrodes and an improvement effect of energy efficiency, the degree of reduction of the distance between the electrodes depends on the number of installed electrolytic reaction tanks (the number of processing stages). In the case of processing in the second stage, the second stage is smaller by about 10 to 50% than the first stage, and the third stage is also smaller by about 10 to 50% than the second stage. It is preferable to make it smaller by about 10 to 50% of the former stage.
Note that the specific distance between the electrodes cannot be unconditionally determined because it differs depending on the amount of the organic suspended solids in the wastewater to be treated, the amount of treated wastewater (treatment capacity), and the like. It is preferable that the thickness is gradually reduced to about 0.5 to 2.0 cm in the second step and the third step, and about 0.2 to 0.5 cm in the n-th step (final step).
[0021]
And, in the present invention, the current density in each electrolytic reaction tank is inevitably changed depending on the set area of the electrode in each reaction tank by energizing the conductive diamond electrode in each electrolytic reaction tank in series connection. Since they differ, it is not necessary to control the amount of electricity supplied to each reaction tank (processing stage), and the apparatus configuration is simplified.
When power is supplied to each electrolytic reaction tank (that is, parallel power supply is performed), it is necessary to control the amount of electricity supplied to each reaction tank (each processing stage), which complicates the apparatus configuration.
[0022]
In addition, the more the oxidizable substance is present in the preceding electrolytic reaction tank, the more the amount of gas generated by the electrolytic treatment. When the amount of generated gas is large, the gas bubble system in the inter-electrode flow channel also becomes large, and the contact efficiency between the drainage and the electrode surface is reduced. The reduction of the contact efficiency due to the bubbles becomes more remarkable as the distance between the electrodes becomes smaller.
For this generated gas, it is desirable to perform gas separation and removal for each electrolytic reaction tank in addition to adjusting the distance between the electrodes.
The gas separation and removal performed for each electrolytic reaction tank can be performed, for example, by using a normal gas-liquid separation device between the electrolytic reaction tanks or a gas venting section (space section) provided above and a gas venting section (gas venting pipe, This is performed by a method such as installing a liquid receiving tank provided with a gas vent or the like, or using a gas vent provided above the electrolytic reaction tank itself and provided with a gas vent at the top.
[0023]
The degree of removal of gas components in the gas-liquid separation is not particularly limited, but the degree to which the electrolytic treatment in the subsequent electrolytic reaction tank can obtain a desired electrolysis efficiency, and generally, the degree of removal in the former electrolytic reaction tank. It may be about 50-95%, preferably about 70-95%, of the gas component accompanying the treated water.
That is, when a conductive diamond electrode is used, if the concentration of the gas component in the wastewater in the electrolytic reaction tank is about 0 to 10%, contact inhibition between the electrode surface and the wastewater due to the gas component and, consequently, an increase in interelectrode resistance are caused. Can be suppressed, and an electrolysis efficiency close to a desired electrolysis efficiency can be obtained.
In order to secure this gas component concentration, it is desirable to set the gas component removal rate to the above-described level.
[0024]
By performing the separation and removal of the generated gas for each electrolytic reaction tank in this manner, since the generated gas is not brought into the subsequent stage, the distance between the electrodes in the subsequent electrolytic reaction tank can be reduced, and the energy efficiency can be reduced. Can be enhanced.
[0025]
In each of the electrolytic reaction tanks configured in the above-described manner, the wastewater containing the oxidizable substance and the electrolyte substance is drained in parallel with the conductive diamond electrode surface at a liquid flow velocity (LV) of 10 to 1,000 m. It is preferable that the liquid be passed at a rate of / hr to make contact with the electrode surface.
[0026]
The reason why the direction of flow of the wastewater is parallel to the electrode surface is to increase the contact efficiency between the wastewater and the electrode surface. This is because it is possible to alleviate contact inhibition to some extent.
If the flow rate of the drainage at this time is 10 to 1,000 m / hr in linear velocity (LV), if it is too slow, the flow direction of the drainage may be parallel to the electrode surface, or the gas may not flow. Even if the interelectrode distance is increased in the first-stage electrolytic reaction tank in which the amount of generated methane is large, the effect of alleviating the inhibition of contact between the wastewater and the electrode surface by the gas component cannot be obtained. This is because a sufficient contact time between the electrode and the electrode surface cannot be obtained, and the electrolysis of the oxidizable substance cannot be sufficiently advanced.
[0027]
The temperature in each electrolytic reaction tank is not particularly limited. However, if the temperature is too low, the electrolysis of the wastewater does not proceed favorably, and if the temperature is too high, vaporization is added to increase the generation of gas components and the wastewater is discharged. Not only does contact inhibition with the electrode surface increase, but also in the low-concentration region as described above, there is a concern about corrosion of device constituent materials by the electrolyte substance. It is desirable to do.
[0028]
FIG. 1 is a flow chart for explaining one embodiment of a wastewater treatment method according to the present invention. In FIG. 1, three electrolytic reaction tanks 1, 2, and 3 are arranged in series, and The reaction tanks 1, 2, 3 are provided with conductive diamond electrodes 111, 111, 112, 112, 113, 113 on opposite side walls, drainage introduction pipes 121, 122, 123 at the lower part, and treated water discharge pipe at the upper part. 131, 132, and 133, and the first and second electrolytic reaction tanks 1 and 2 are provided with spaces S1 and S2 above, and gas vent pipes 141 and 142 are opened at the tops of the spaces. Let me.
[0029]
These electrodes have the area of 111, 111> 112, 112> 113, 113, and the distance between the poles is 111, 111 distance> 112, 112 distance> 113, 113 distance.
The conductive diamond electrodes 111, 111, 112, 112, 113, 113 are connected in series and energized as shown by the dotted lines in the figure.
[0030]
In the above embodiment, the wastewater to be treated is introduced into the first-stage electrolytic reaction tank 1 from the drainage introduction pipe 121 and is transferred from the lower part to the upper part, during which the conductive diamond electrodes 111, Electrolytic treatment is performed in parallel with the surface of the substrate 111.
The gas component generated in the course of the electrolysis rises in the tank 1 and moves to the space S1, and is extracted out of the system from the gas exhaust pipe 141.
On the other hand, the wastewater thus gas-liquid separated is extracted from the pipe 131.
[0031]
The extracted water is introduced from the introduction pipe 122 into the second-stage electrolysis reaction tank 2 and electrolyzed in the same manner as in the first-stage electrolysis reaction tank 1.
In the second-stage electrolytic reaction tank 2, the wastewater introduced from the introduction pipe 122 contains almost no organic suspended substances or gas components. The 112 and 112 are not short-circuited by the organic suspended substance, and the generation of air bubbles that hinders the contact between the wastewater and the surface of the electrodes 112 and 112 is small, and the wastewater contacts the surfaces of the electrodes 112 and 112 with high efficiency. Electrolysis treatment is performed.
[0032]
In this way, the treated water that has been electrolyzed in the second-stage electrolytic reaction tank 2 is separated from the gas component generated in the second-stage electrolytic treatment and transferred to the space S2, and , And introduced into the third-stage electrolytic reaction tank 3 through the introduction pipe 123, and subjected to a final-stage electrolysis treatment.
[0033]
【Example】
Example 1
The first to third stage electrolytic reaction tanks were configured as follows so as to have the flow mode shown in FIG.
The first-stage electrolytic reaction tank 1 is composed of two laminated polycrystalline diamond electrode plates (4 cm × 12 cm × 0.05 cm) 111, 111 that have been vapor-phase deposited and synthesized by using a boron doping method, and the interelectrode distance is 1 cm. It was configured as follows.
The second-stage electrolytic reaction tank 2 is a laminated polycrystalline diamond electrode plate used for the first-stage electrolytic reaction tank, and has two sheets 112, 112 each having a size of 4 cm × 8 cm × 0.05 cm. The distance between the electrodes was set to 0.5 cm.
The third-stage electrolysis reaction tank 3 is a laminated polycrystalline diamond electrode plate used for the first and second-stage electrolysis reaction tanks, and has two pieces each having a size of 4 cm × 4 cm × 0.05 cm. , 113 were set so that the distance between the electrodes was 0.3 cm.
The electrodes 111, 111, 112, 112, 113 and 113 of the first to third stages of the electrolytic reaction tanks 1 to 3 were energized in series.
[0034]
The synthetic wastewater containing 600 mg / L of phenol and 14 g / L of Na ₂ SO ₄ (CODMn: 720 mg / L) was passed through the treatment flow configured as described above at a flow rate of 8 L / hr to the first stage. The solution was passed in the order of electrolysis reaction tank 1 → second-stage electrolysis reaction tank 2 → third-stage electrolysis reaction tank 3.
[0035]
The amount of electricity supplied to the first-stage electrolytic reaction tank 1 was set to 10 A (10 A of electricity flows through the second-stage electrolytic reaction tank 2 and the third-stage electrolytic reaction tank 3). ).
With this quantity of electricity, the current density of each of the electrolytic reaction tanks 1 to 3 is approximately as follows.
First stage electrolytic reaction tank 1: 20.8 A / dm ² (2080 A / cm ² )
Second stage electrolytic reaction tank 2: 31.3 A / dm ² (3130 A / cm ² )
Third stage electrolytic reaction tank 3: 62.5 A / dm ² (6250 A / cm ² )
[0036]
The CODMn concentration of the effluent from each of the electrolytic reaction tanks 1 to 3 at the time when 3 hours had passed after the start of the passage was as follows.
First-stage electrolytic reaction tank 1: 382 mg / L
Second stage electrolytic reaction tank 2: 64.9 mg / L
Third stage electrolytic reaction tank 3: 3.2 mg / L
The current efficiency in this flow was 53.1%.
[0037]
Further, as a result of continuous treatment under the same conditions as above for two weeks, it was confirmed that a stable treatment effect could be maintained.
[0038]
Comparative Example 1
Two laminated polycrystalline diamond electrode plates (4 cm × 24 cm × 0.05 cm) synthesized by vapor deposition using the boron doping method in the same manner as in Example 1 were installed so that the distance between the electrodes was 5 mm. And
The electrode area of this one electrolytic reaction tank is the same as the total total electrode area of the first to third-stage electrolytic reaction tanks 1 to 3 of Example 1.
The amount of electricity input to this electrolytic reaction tank was 30 A. The current density is about 31.3 A / dm ² (about 3130 A / cm ² ).
[0039]
The same synthetic wastewater (CODMn: 720 mg / L) as in Example 1 was passed through this electrolytic reaction tank at the same flow rate as in Example 1 for treatment.
The effluent from the electrolytic reaction tank 3 hours after the start of the liquid passage had a CODMn of 57.2 mg / L.
This current efficiency was 48.9%.
[0040]
【The invention's effect】
As described above, according to the present invention, even if the wastewater to be treated contains an organic suspended substance or an organic compound that generates a gas by an electrolytic reaction as an oxidizable substance, even if the wastewater to be treated contains Does not occur, and the generated gas can effectively prevent the contact between the oxidizable substance and the electrode surface.
Therefore, not only can the processing cost required for reducing the COD, TOC, and total nitrogen concentrations in the wastewater be reduced, but also stable continuous operation can be performed for a long period of time.
[Brief description of the drawings]
FIG. 1 is a diagram for describing an embodiment of a processing method according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st-stage electrolysis reaction tank 2 2nd-stage electrolysis reaction tank 3 3rd-stage electrolysis reaction tank 111,111 Electrode 112,112 of 1st-stage electrolysis reaction tank 1 2nd-stage electrolysis Electrodes 113, 113 of reaction tank 2 Electrodes 121, 122, 123 of third-stage electrolytic reaction tank 3 Drainage introduction pipes 131, 132, 133 Treated water discharge pipes 141, 142 Gas release pipes S1, S2 Space

Claims (6)

A method for electrolytically treating wastewater containing an oxidizable substance and an electrolyte substance using a conductive diamond electrode,
A method for treating wastewater, comprising: installing a plurality of electrolytic reaction tanks in series, and performing electrolytic treatment while setting current densities of electrodes of the electrolytic reaction tanks at different stages to different conditions. 2. The method for treating wastewater according to claim 1, wherein the area of the conductive diamond electrode in each of the electrolytic reaction tanks is set so as to be greater than the former stage. 3. The method for treating wastewater according to claim 1, wherein the distance between the conductive diamond electrodes in each of the electrolytic reaction tanks is set to be greater than the former stage. The method for treating wastewater according to any one of claims 1 to 3, wherein energization of the conductive diamond electrode in each of the electrolytic reaction tanks is performed in series. The wastewater treatment method according to any one of claims 1 to 4, wherein the oxidizable substance includes an organic suspended substance. The wastewater treatment method according to any one of claims 1 to 4, wherein the oxidizable substance includes an organic substance that generates a gas with an electrolytic reaction.

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