Method and apparatus for treating organic wastewater using hydrogen peroxide

Abstract

To provide a method and apparatus for efficiently decomposing organic matter contained in general industrial waste water, such as chemical cleaning waste water, organic acid waste water, and waste water mixed with organic rust inhibitors, as well as wastewater in nuclear facilities in situ.SOLUTION: A method for treating organic wastewater includes copper ions and cobalt ions added in combination to waste water containing organic matter and hydrogen peroxide water added while maintaining a pH in the range of 6.0 to 7.0. A waste water treatment apparatus includes a reaction tank 10 in which wastewater containing organic matter is mixed with copper ions and cobalt ions, a pH adjustment means 20, and a supply means 30 for hydrogen peroxide water.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for decomposing organic substances contained in general industrial wastewater such as chemical cleaning wastewater, organic acid wastewater, and mixed wastewater of organic rust inhibitors, and wastewater within nuclear power facilities, in situ.

Background Art

[0002] As a method for treating organic substances contained in general industrial wastewater such as organic acid wastewater and mixed wastewater of organic rust inhibitors generated in industrial sites and chemical cleaning sites, and wastewater within nuclear power facilities, in situ, the Fenton oxidation method is generally used.

[0003] The Fenton oxidation method utilizes the Fenton reaction in which hydrogen peroxide (H2O2) is decomposed into hydroxyl radicals (HO·) and hydroxide ions (HO 2+ ) by ferrous ions (Fe - ), and it is generally said that it is a method of oxidizing organic substances by hydroxyl radicals (HO·) generated by the decomposition of H2O2.

[0004] Specifically, it is said that when a ferrous compound and hydrogen peroxide are added to water containing organic substances, hydroxyl radicals (HO·) are generated by the reaction of the following formula.

[0005]

Chemical Formula

[0006] However, recent research has shown experimental results that in the Fenton oxidation method, hydroxyl radicals are not generated, and instead, weaker reactive oxygen species such as oxygen molecules bound to iron(III) complexes with a binuclear structure, or activation due to hydrogen peroxide showing an electron affinity similar to singlet oxygen, are generated (Non-Patent Document 1).

[0007] In actual Fenton oxidation methods, it is difficult to efficiently generate the reactive oxygen species mentioned above, resulting in low oxidizing power, low organic matter removal rates, and the need for residual hydrogen peroxide treatment. To completely react hydrogen peroxide, increase the amount of reactive oxygen species generated, and improve the organic matter removal rate, Fe 2+ While it is necessary to use a large amount of this material, this results in the discharge of a large amount of sludge mainly composed of Fe(OH)3, leading to the problem of high sludge disposal costs.

[0008] In addition to the Fenton oxidation method using ferrous iron, a method using a copper catalyst has also been proposed as a method for activating hydrogen peroxide (Non-Patent Literature 2). However, as shown in the comparative example of the present invention, adding copper ions alone as a catalyst results in limited generation of reactive oxygen species, and there is a problem that high decomposition efficiency cannot be obtained.

[0009] Other treatment methods combining hydrogen peroxide and a catalyst include adding copper ions or iron ions and irradiating with ultraviolet light (Patent Document 1), activating a titanium catalyst with added copper by irradiating it with light (Patent Document 2), contacting a copper-nickel alloy plate with hydrogen peroxide and nitric acid and heating to 180-200°C (Patent Document 3), and performing electrolysis of water using a metal electrode (one of magnesium, aluminum, zinc, iron, nickel, copper, silver, platinum, gold, or titanium) and treating with the generated hydrogen peroxide and the metal dissolved from the electrode (Patent Document 4). However, all of these methods have the problem of requiring complex equipment and energy.

[0010] Thus, an efficient method for treating organic wastewater using hydrogen peroxide has not yet been established. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 05-123685 [Patent Document 2] Japanese Patent Application Publication No. 05-253581 [Patent Document 3] Japanese Patent Application Publication No. 09-010780 [Patent Document 4] Japanese Patent Publication No. 2000-79395 [Non-patent literature]

[0012] [Non-Patent Document 1] Yuzo Nishida, "Fenton Reaction and Hydroxyl Radicals," The Chemical Times, 2015 No.2 (Issue 236), 8-16. [Non-Patent Document 2] Toshihiko Ozawa et al., "Generation of Hydroxyl Radicals by Reaction of Copper(II) Complexes with Hydrogen Peroxide," Journal of the Chemical Society of Japan, 1988, (4), pp. 459-465. [Overview of the project] [Problems that the invention aims to solve]

[0013] The object of the present invention is to provide an organic wastewater treatment method and apparatus that can treat organic matter contained in general industrial wastewater such as organic acid wastewater and organic rust inhibitor mixed wastewater generated at industrial sites and chemical cleaning sites, as well as wastewater from nuclear facilities, on-site with a simple apparatus while minimizing the amount of secondary waste generated, such as sludge. [Means for solving the problem]

[0014] The present invention provides a method and apparatus for treating organic wastewater as described below. [1] Copper ions and cobalt ions are added in combination to wastewater containing organic matter. A method for treating organic wastewater, characterized by adjusting the pH of the wastewater to a range of 6.0 to 8.5, and then adding hydrogen peroxide to oxidize and decompose the organic matter in the wastewater. [2] The treatment method according to [1] above, characterized in that the copper ion concentration in the wastewater containing the organic matter is controlled to be in the range of 0.1 mmol / L or more and 0.5 mmol / L or less, and the cobalt ion concentration is in the range of 0.1 mmol / L or more and 2 mmol / L or less. [3] The method for treating organic wastewater according to [1] above is characterized in that the concentration of copper ions in the wastewater containing the organic matter is in the range of 0.1 mmol / L or more and 0.5 mmol / L or less, and the concentration of cobalt ions is in the range of 0.1 mmol / L or more and 2 mmol / L or less, and the concentration of cobalt ions is controlled to be not less than the concentration of copper ions. [4] A reaction tank for mixing wastewater containing organic matter with copper ions and cobalt ions, pH adjusting means for adjusting the pH of the wastewater in the reaction tank, Means for supplying hydrogen peroxide water to the reaction tank, A treatment apparatus for implementing the method for treating wastewater according to [1] or [2] above, provided with the above. [5] The reaction tank further includes a cathode and an anode for electrolyzing water, the anode is an insoluble electrode, and the supply amount of hydrogen peroxide is adjusted by controlling the electrode potential. The treatment apparatus according to [4] above. [(6)] The means for supplying hydrogen peroxide water is controlled based on the potential of the organic wastewater in the reaction tank measured by a redox potentiometer provided in the reaction tank, and the supply of hydrogen peroxide water is adjusted. The treatment apparatus according to [4] or [5] above.

[0015] The present invention provides a method and an apparatus for treating organic matter contained in general industrial wastewater such as chemical cleaning wastewater, organic acid wastewater, and organic rust inhibitor mixed wastewater, and wastewater in nuclear power facilities on-site. The method for treating general industrial wastewater and wastewater in nuclear power facilities on-site according to the present invention is characterized in that in the method for treating organic matter in wastewater using hydrogen peroxide, copper ions and cobalt ions are added in combination as a catalyst.

[0016] The present invention is suitable for treating a wide range of organic wastewater including organic acids, reducing agents, aromatic hydrocarbons, alcohols, organic rust inhibitors, and organic acid cleaning wastewater.

[0017] <​​​ The copper and cobalt ions, which act as catalysts, are added so that their concentrations in the wastewater during the treatment reaction are in the range of copper ions: 0.1 mmol / L to 0.5 mmol / L and cobalt ions: 0.1 mmol / L to 2 mmol / L, preferably in the range of copper ions: 0.25 mmol / L to 0.5 mmol / L and cobalt ions: 0.5 mmol / L to 2 mmol / L. It is preferable that the cobalt ion concentration in the wastewater during the treatment reaction is greater than or equal to the copper ion concentration. If it is desired to reduce the added concentrations of copper and cobalt ions from the perspective of wastewater discharge, they can be reduced to approximately 0.1 mmol / L each. This allows for a low concentration of copper ions in the treated water, which can then be easily reduced to below wastewater discharge standards through post-treatment as needed.

[0019] The wastewater treatment method of the present invention involves adding an aqueous solution containing copper ions and cobalt ions to wastewater containing organic matter (hereinafter referred to as "organic wastewater"), adjusting the pH, and then adding hydrogen peroxide to oxidize and decompose the organic matter. By adding copper ions and cobalt ions to adjust the pH beforehand and then adding hydrogen peroxide, unnecessary reactions such as the self-decomposition of hydrogen peroxide can be suppressed, and organic matter in the wastewater can be efficiently oxidized and decomposed.

[0020] The present invention also provides an organic wastewater treatment apparatus comprising a reaction vessel for mixing wastewater containing organic matter with copper ions and cobalt ions, a pH adjustment means, and a means for supplying hydrogen peroxide solution.

[0021] The reaction vessel may be equipped with a cathode and an anode for the electrolysis of water, and may be configured to use an insoluble electrode as the anode and adjust the supply amount of hydrogen peroxide by controlling the electrode potential.

[0022] The means for supplying hydrogen peroxide solution may be configured to adjust the supply of hydrogen peroxide solution based on the potential of the organic wastewater in the reaction vessel, which is measured by an oxidation-reduction potential meter installed in the reaction vessel. [Effects of the Invention]

[0023] According to the present invention, organic matter contained in general industrial wastewater such as chemical cleaning wastewater, organic acid wastewater, and wastewater mixed with organic rust inhibitors, as well as wastewater from nuclear facilities, can be oxidized and decomposed into carbon dioxide and water by adding an aqueous solution containing copper ions and cobalt ions, adjusting the pH, and then adding hydrogen peroxide. The copper ions and cobalt ions act as catalysts for generating the reactive oxygen species. Since only trace amounts of copper ions and cobalt ions are added, the amount of secondary waste generated can be kept to a minimum, for example, by ferritization with a small amount of iron powder or adsorption and sedimentation with a small amount of iron-based coagulant, and these can be removed from the treated water. Therefore, the need for energy supply such as ultraviolet irradiation devices and heating devices can be avoided, and organic wastewater can be treated with a simple device, solving problems such as the initial cost of manufacturing complex devices, operating costs due to energy input, and rising sludge disposal costs. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic diagram illustrating one embodiment of a treatment apparatus for carrying out the treatment of organic matter in wastewater according to the present invention. [Figure 2] This is a schematic diagram illustrating an embodiment of the present invention that includes a configuration for controlling the supply amount of hydrogen peroxide in a treatment apparatus for treating organic matter in wastewater. [Figure 3] This graph shows the activation of hydrogen peroxide treatment by adding a copper-cobalt composite catalyst. [Figure 4] This graph shows the relationship between pH conditions and the rate of decrease in TOC. [Figure 5] This graph shows the results of a test to reduce the concentration of the added catalyst. [Figure 6] This graph shows an example of treating organic wastewater with a high initial TOC concentration. Preferred Embodiment

[0025] The present invention will be described in detail below with reference to the attached drawings, but the present invention is not limited thereto.

[0026] Figure 1 shows one embodiment of an apparatus for carrying out the processing method of the present invention. The apparatus of the present invention comprises a reaction tank 10 for mixing organic wastewater containing organic matter with copper ions and cobalt ions, a pH adjustment means 20, and a hydrogen peroxide water supply means 30.

[0027] The reaction tank 10 is preferably equipped with, for example, a stirrer 40 as a means for mixing organic wastewater. Alternatively, it is also preferable to generate a water flow in the tank using a water flow generating means (not shown), such as a submersible pump.

[0028] The pH adjustment means 20 preferably consists of, for example, a pH meter, a pH adjusting agent storage tank 21 which is an acid or alkali, and a pH adjusting agent injection pump 22 which introduces the pH adjusting agent into the reaction tank 10, and is equipped with a function to automatically control the operation of the pH adjusting agent injection pump 22 so that the pH is within a certain range (for example, a range of pH 6.0 to 7.0) based on a control signal from the pH meter.

[0029] The hydrogen peroxide supply means 30 preferably consists of, for example, a hydrogen peroxide storage tank 31 and a hydrogen peroxide injection pump 32, and is equipped with a mechanism that can supply hydrogen peroxide after pH adjustment. For example, an automatic control mechanism may be provided that sets the pH adjustment start time to be earlier than the hydrogen peroxide supply start time using timer control, or that activates the hydrogen peroxide injection pump when the output range of the pH meter enters a specified range.

[0030] Figure 2 shows an embodiment of the apparatus of the present invention, in which a reaction vessel 10 is equipped with an oxidation-reduction potential meter 33, as well as a cathode 51 for the electrolysis of water, an anode (insoluble electrode) 52, and a DC power supply (constant potential power supply potentiostat) 53.

[0031] The oxidation-reduction potential meter 33 measures the potential of the organic wastewater in the reaction vessel 10 and controls the hydrogen peroxide supply means 30 based on the measured potential to adjust the amount of hydrogen peroxide supplied. For the anode 52 used in the electrolysis of water, an insoluble electrode such as a platinum, iridium oxide, or ruthenium-coated titanium electrode is preferred. By controlling the electrode potential with a DC power supply 53, it is possible to control whether oxygen, ozone, or hydrogen peroxide is preferentially generated from the insoluble electrode anode 52, and hydrogen peroxide can be supplied additionally.

[0032] Although not shown in the diagram, the reaction tank 10 may be equipped with treated water piping for discharging treated water.

[0033] Next, an example of the organic wastewater treatment method of the present invention using the treatment apparatus shown in Figure 1 will be described. The treatment apparatus of the present invention is installed at the site where organic wastewater is generated or in a nearby treatment space, and the organic wastewater to be treated (hereinafter referred to as "raw water") is received into the reaction tank 10 and stirred. In the treatment method of the present invention, it is necessary that the raw water in the reaction tank 10 contains copper ions and cobalt ions. In the reaction tank 10, or at any point upstream of the reaction tank 10, an aqueous solution containing copper ions and cobalt ions is added to adjust the copper ion concentration in the raw water to 0.1 mmol / L or more and 0.5 mmol / L or less, and the cobalt ion concentration to 0.1 mmol / L or more and 2 mmol / L or less. It is preferable that the cobalt ion concentration in the raw water is greater than or equal to the copper ion concentration.

[0034] For example, copper sulfate (CuSO4·5H2O) is preferred as an aqueous solution containing copper ions, and cobalt sulfate (CoSO4·7H2O) is preferred as an aqueous solution containing cobalt ions.

[0035] The concentrations of copper ions and cobalt ions in the raw water can be measured in advance, and the concentrations of copper ions and cobalt ions in the aqueous solution to be added can be adjusted so that the concentrations in the raw water fall within the predetermined range.

[0036] Next, the pH of the raw water in the reaction vessel 10 is adjusted using the pH adjustment means 20 to a range of, for example, pH 6.0 to 7.0. For pH adjustment, aqueous solutions of 5% sulfuric acid and 5% caustic soda are preferably used. If the pH fluctuation range is known in advance, only one chemical storage tank (acid or alkali) and a pH adjusting agent injection pump are needed. However, if the pH fluctuation range is unknown, it is preferable to provide both chemical storage tanks and pH adjusting agent injection pumps. pH adjustment is preferably carried out continuously until the treatment is completed.

[0037] After pH adjustment, hydrogen peroxide is added using the hydrogen peroxide supply means 30 while continuing to stir in the reaction vessel 10. For example, commercially available 30% hydrogen peroxide solution can be used as the hydrogen peroxide solution to be added.

[0038] The amount of hydrogen peroxide added should be adjusted as needed depending on the properties of the raw water, but as a guideline, it is sufficient to add hydrogen peroxide in an amount between 10 and 40 times the weight of TOC (total organic carbon) to be decomposed. For example, 1mg of 1-hydroxybenzotriazole (HOBt), an organic rust inhibitor with a TOC of 230mg / L. 3 To treat this, adding 30 liters of 30% hydrogen peroxide solution is sufficient. After decomposition, hydrogen peroxide becomes water and oxygen, and no salts or other substances remain in the treated water. Therefore, even if the amount added increases, there is no problem of increased generation of secondary waste such as sludge.

[0039] If the TOC of the raw water is very high (for example, organic acid washing wastewater has a TOC of about 20,000 mg / L), it is also preferable to supply hydrogen peroxide using an insoluble electrode 52 installed in the reaction vessel 10, as shown in Figure 2. In that case, it is also preferable to use a potentiostat 53 to control the potential of the anode 52 to a standard electrode potential of 1.8 V to 2.1 V (vs. SHE) and preferentially generate hydrogen peroxide.

[0040] To prevent hydrogen peroxide from being wasted by its self-decomposition, it is preferable to supply hydrogen peroxide solution gradually in accordance with the progress of oxidative decomposition. It is also preferable to inject it intermittently with time control, or to measure the oxidation-reduction potential of the raw water in the reaction vessel 10 using an ORP electrode 33, and to inject additional hydrogen peroxide solution when the potential drops to, for example, 230 mV or less.

[0041] Ultimately, it is often preferable from a wastewater management perspective to not leave any hydrogen peroxide residue in the treated water. In such cases, it is preferable to stop injecting hydrogen peroxide solution in the later stages of treatment and allow the residual organic matter to consume the hydrogen peroxide, or to add a reducing agent such as sodium thiosulfate at the end to decompose the residual hydrogen peroxide.

[0042] If residual copper or cobalt ions in the treated water pose a problem, they can be removed by providing a post-treatment device. For example, a sludge sedimentation tank can be provided as a post-treatment device, allowing for the separation of copper or cobalt ions by ferritization with iron powder or adsorption sedimentation with an iron-based coagulant. If the treated water does not contain turbidity, it is also preferable to remove the ions by adsorption or ion exchange by passing the water through a column made of iron material or ion exchange resin. [Examples]

[0043] The present invention will be specifically described below with reference to examples and comparative examples. Treatment tests for various types of organic wastewater were conducted using the treatment apparatus shown in Figure 1 under the test conditions shown in Table 1. Unless otherwise specified, the organic wastewater used was an aqueous solution containing the organic rust inhibitor 1-hydroxybenzotriazole (HOBt).

[0044] [Table 1]

[0045] [Example 1, Comparative Examples 1 & 2] Activation of hydrogen peroxide treatment by adding a copper-cobalt composite catalyst In Example 1, a copper-cobalt composite catalyst was used, in Comparative Example 1, the copper catalyst alone was used, and in Comparative Example 2, the cobalt catalyst alone was used. Specifically, in Example 1, CuSO4·5H2O was added as an aqueous solution containing copper ions, and CoSO4·7H2O was added as an aqueous solution containing cobalt ions. In Comparative Example 1, only CuSO4·5H2O was added, and in Comparative Example 2, only CoSO4·7H2O was added.

[0046] An aqueous solution containing the organic rust inhibitor 1-hydroxybenzotriazole (hereinafter referred to as HOBt) was used as simulated organic wastewater, and the initial TOC concentration was adjusted to 230 mg / L. CuSO4·5H2O and / or CoSO4·7H2O were added to the simulated organic wastewater (raw water) to adjust the concentrations of copper ions and cobalt ions in the raw water to those shown in Table 2. After adjusting the pH of the raw water to 7, 30% hydrogen peroxide solution was added to the raw water to a hydrogen peroxide concentration of 9000 mg / L (0.9%), and the change in TOC concentration over time was measured.

[0047] [Table 2]

[0048] The results for Example 1, Comparative Example 1, and Comparative Example 2 are shown in Figure 3. In Example 1, adding a combination of copper and cobalt as a catalyst reduced the TOC concentration to 50 mg / L after 2 hours. In contrast, in Comparative Example 1, where only copper was added, and Comparative Example 2, where only cobalt was added, the TOC concentration still exceeded 200 mg / L after 4 hours, and no significant reduction in TOC concentration occurred. These results indicate that combining copper and cobalt unexpectedly activates hydrogen peroxide, leading to an efficient reduction of TOC.

[0049] Furthermore, while hydrogen peroxide remained in the treated water in Comparative Examples 1 and 2, the hydrogen peroxide concentration in the treated water in Example 1 decreased to almost 0 mg / L. This is thought to be because the combined copper and cobalt catalyst activated the hydrogen peroxide with almost 100% efficiency, resulting in a reduction in the half-life of hydrogen peroxide in water from the usual 5 days to a few minutes or less. Therefore, it has been shown that in the present invention, even if hydrogen peroxide is added in excess to reduce TOC, no hydrogen peroxide remains in the treated water, thus eliminating the need for post-treatment.

[0050] [Comparative Examples 3-5 and 2-5] Effect of pH on the activation of hydrogen peroxide treatment The hydrogen peroxide concentration, copper ion concentration, and cobalt ion concentration in the raw water were fixed at 0.9%, and the pH of the raw water was varied from 5 to 9 using a pH stat. The TOC concentration after 2 hours of treatment was measured, and the percentage decrease from the initial TOC concentration was calculated. The results are shown in Table 3 and Figure 4.

[0051] [Table 3]

[0052] As shown in Table 3 and Figure 4, within the pH range of 6.0 to 8.5, more than 30% of TOC derived from HOBt could be decomposed within 2 hours, whereas outside this pH range, the removal rate decreased to less than 20%. Furthermore, within the pH range of 6.0 to 7.5, the removal rate improved to more than 49%, and more preferably to more than 62% within the pH range of 6.0 to 7.0. By controlling the pH within this range, TOC in organic wastewater can be efficiently reduced, but it was confirmed that the treatment reaction of the present invention does not proceed under the pH conditions of around 3 to 4, which are commonly used in Fenton treatment using hydrogen peroxide.

[0053] [Examples 6-13] Applicability to various types of organic wastewater Treatment tests for various organic wastewaters, as shown in Table 4, were conducted under test conditions where the raw water contained 0.9% hydrogen peroxide, 0.5 mmol / L copper ions, 2 mmol / L cobalt ions, and a pH of 6.5. Example 13 had a very high initial TOC concentration of 21390 mg / L, so it was diluted to 230 mg / L before being used in this experiment. The results are shown in Table 4.

[0054] [Table 4]

[0055] As shown in Table 4, the method of activating hydrogen peroxide by combining copper ions and cobalt ions according to the present invention was able to treat organic acids, reducing agents, organic rust inhibitors, alcohols, and aromatic hydrocarbons. Furthermore, it was shown that chemical cleaning wastewater with a very high initial TOC concentration, which contains various organic components, could be reduced without any problems by pre-diluting it.

[0056] [Examples 8, 14-15, Reference Examples 6-8] Conditions for reducing copper-cobalt catalyst concentration Treatment tests were conducted to reduce the copper ion and cobalt ion concentrations in raw water under test conditions controlled to a hydrogen peroxide concentration of 0.9%, an initial TOC concentration of 230 mg / L, and a pH of 6.5. CuSO4·5H2O was used as the aqueous solution containing copper ions, and CoSO4·7H2O was used as the aqueous solution containing cobalt ions. The copper ion and cobalt ion concentrations in the raw water are shown in Table 5, and the test results are shown in Figure 5.

[0057] [Table 5]

[0058] As shown in Figure 5, in Examples 8, 14, and 15, when the copper ion concentration was 0.1 mmol / L or higher, it was possible to reduce the TOC to approximately 50 mg / L by combining it with a cobalt ion concentration of 0.1 mmol / L or higher. On the other hand, as shown in Reference Examples 6-8, when the copper ion concentration was reduced to 0.03 mmol / L, even when the combined cobalt ion concentration was increased to 2 mmol / L, the decrease in TOC concentration stopped at 100 mg / L or higher. However, compared to Comparative Examples 1 and 2, which used copper ions or cobalt ions alone, the TOC concentration decreased to 200 mg / L or lower in 3 hours, indicating that even small amounts of combined copper and cobalt ions are effective. These results indicate that the concentrations of the catalytic copper and cobalt ions are preferably in the range of copper ions: 0.1 to 0.5 mmol / L and cobalt ions: 0.1 to 2 mmol / L, and that if it is desired to reduce the concentration of copper and cobalt ions, they can be suppressed to approximately 0.1 mmol / L each.

[0059] [Example 16] Treatment of high-concentration wastewater Under test conditions where the pH was controlled to 6.5, the chemical washing wastewater used in Example 13 was diluted to an initial TOC concentration of 6735 mg / L at a lower dilution ratio than in Example 13, and the treatment test was carried out until the TOC concentration decreased to 50 mg / L or less. Hydrogen peroxide was repeatedly added every 15 to 30 minutes so that the concentration in the raw water each time was between 3000 mg / L and 6000 mg / L. The test results are shown in Figure 6. In Figure 6, the vertical axis represents the TOC concentration of the reaction solution, and the horizontal axis represents the cumulative concentration of added hydrogen peroxide in mg / L.

[0060] As shown in Figure 6, even highly concentrated chemical washing wastewater could be treated to reduce its TOC by repeatedly adding hydrogen peroxide. In the high-concentration range of TOC above 4000 mg / L, the hydrogen peroxide addition rate was high, and adding 5.6 g of hydrogen peroxide for every 1 g of TOC in organic wastewater was sufficient to reduce the TOC. As the TOC concentration of organic wastewater decreased, the hydrogen peroxide addition rate decreased, and ultimately, adding 41 times the weight of hydrogen peroxide reduced the TOC to 42 mg / L.

[0061] The results above demonstrate that the method of activating hydrogen peroxide by combining copper ions and cobalt ions according to the present invention can treat even highly concentrated organic wastewater. [Industrial applicability]

[0062] The present invention provides a method and apparatus for treating organic wastewater, enabling the smooth treatment of wastewater that is difficult to dispose of efficiently on-site, such as general industrial wastewater including chemical cleaning wastewater, organic acid wastewater, and organic rust inhibitor mixed wastewater, as well as wastewater from nuclear facilities. It solves problems in facility operation and management, such as low organic matter decomposition efficiency, complex equipment, and the generation of large amounts of secondary waste. Furthermore, in the case of nuclear facilities, it can also serve as a means to solve the problem of residual waste during decommissioning.

Claims

1. Copper ions and cobalt ions are added in combination to wastewater containing organic matter. A method for treating organic wastewater, characterized by adjusting the pH of the wastewater to a range of 6.0 to 8.5, and then adding hydrogen peroxide to oxidize and decompose the organic matter in the wastewater.

2. The treatment method according to claim 1, characterized in that the copper ion concentration in the wastewater containing the organic matter is controlled to be in the range of 0.1 mmol / L or more and 0.5 mmol / L or less, and the cobalt ion concentration is controlled to be in the range of 0.1 mmol / L or more and 2 mmol / L or less.

3. The method for treating organic wastewater according to claim 1, characterized in that the copper ion concentration in the wastewater containing the organic matter is in the range of 0.1 mmol / L or more and 0.5 mmol / L or less, and the cobalt ion concentration is in the range of 0.1 mmol / L or more and 2 mmol / L or less, and the cobalt ion concentration is controlled to be equal to or greater than the copper ion concentration.

4. A reaction vessel for mixing wastewater containing organic matter with copper ions and cobalt ions, A pH adjustment means for adjusting the pH of the wastewater in the reaction tank, Means for supplying hydrogen peroxide solution to the reaction vessel, A treatment apparatus for carrying out the wastewater treatment method described in claim 1, comprising the provision of a device.

5. The apparatus according to claim 4, wherein the reaction vessel further comprises a cathode and an anode for the electrolysis of water, the anode being an insoluble electrode, and the amount of hydrogen peroxide supplied is adjusted by controlling the electrode potential.

6. The apparatus according to claim 4 or 5, characterized in that the means for supplying hydrogen peroxide solution is controlled based on the potential of organic wastewater in the reaction vessel, measured by an oxidation-reduction potential meter installed in the reaction vessel, and the supply of hydrogen peroxide solution is adjusted accordingly.

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