Method and apparatus for treating organic wastewater with 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 apparatus for on-site decomposition of organic matter contained in general industrial wastewater such as chemical cleaning wastewater, organic acid wastewater, wastewater mixed with organic rust inhibitors, and wastewater from nuclear facilities. [Background technology]

[0002] The Fenton oxidation method is commonly used to treat organic matter contained in general industrial wastewater, such as organic acid wastewater generated at industrial sites and chemical cleaning sites, wastewater mixed with organic rust inhibitors, and wastewater from nuclear facilities on site.

[0003] The Fenton oxidation process is a process in which hydrogen peroxide (H2O2) is converted into ferrous ions (Fe 2+ ) produces hydroxyl radicals (HO ) and hydroxyl ions (HO - ), and is generally said to be a method of oxidizing organic matter using hydroxyl radicals (HO·) produced by the decomposition of H2O2.

[0004] Specifically, when a ferrous compound and hydrogen peroxide are added to water containing organic matter, hydroxyl radicals (HO·) are generated according to the reaction shown below.

[0005] [ka]

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

[0007] In the actual Fenton oxidation method, it is difficult to efficiently generate the above-mentioned active oxygen species, which results in a low amount of oxidizing power and a low organic matter removal rate, making it necessary to treat the remaining hydrogen peroxide. In order to completely react hydrogen peroxide, increase the amount of active oxygen species generated, and increase the organic matter removal rate, Fe 2+ However, in this case, a large amount of sludge mainly composed of Fe(OH)3 is discharged, which causes 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 Document 2). However, as shown in the comparative example of the present invention, even if copper ions are added alone as a catalyst, the generation of active oxygen species is limited, 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 them with ultraviolet light (Patent Document 1), activating a titanium catalyst to which copper has been added by exposing it to light (Patent Document 2), bringing hydrogen peroxide and nitric acid into contact with a copper-nickel alloy plate and heating it to 180 to 200°C (Patent Document 3), and electrolyzing water using a metal electrode (one of magnesium, aluminum, zinc, iron, nickel, copper, silver, platinum, gold, or titanium), and then treating the resulting hydrogen peroxide with the metal eluted from the electrode (Patent Document 4). However, all of these methods have problems with the equipment required being complex and requiring a lot of energy.

[0010] As described above, an efficient method for treating organic waste liquid 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] JP 2000-79395 A [Non-patent literature]

[0012] [Non-Patent Document 1] Yuzo Nishida, "Fenton reaction and hydroxyl radicals", The Chemical Times, 2015 No. 2 (Volume 236), 8-16 [Non-Patent Document 2] Toshihiko Ozawa et al. "Generation of hydroxyl radicals by the reaction of copper(II) complexes with hydrogen peroxide" Journal of the Chemical Society of Japan, 1988, (4), pp.459-465 Summary of the Invention [Problem to be solved by the invention]

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

[0014] According to the present invention, there are provided the following organic wastewater treatment method and treatment device. [1] Copper ions and cobalt ions are added in combination to wastewater containing organic matter, A method for treating organic wastewater, comprising adjusting the pH of the wastewater to a range of 6.0 or more and 8.5 or less, and then adding hydrogen peroxide solution to oxidize and decompose organic matter in the wastewater. [2] The treatment method according to the above [1], characterized in that the copper ion concentration in the wastewater containing organic matter is controlled to a range of 0.1 mmol / L or more and 0.5 mmol / L or less, and the cobalt ion concentration in the wastewater containing organic matter is controlled to a range of 0.1 mmol / L or more and 2 mmol / L or less. [3] A method for treating organic wastewater according to the above item [1], characterized in that the copper ion concentration in the wastewater containing 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, and the cobalt ion concentration is controlled to be equal to or higher than the copper ion concentration. [4] A reaction tank for mixing wastewater containing organic matter with copper ions and cobalt ions; A pH adjusting means for adjusting the pH of the wastewater in the reaction tank; A means for supplying hydrogen peroxide to the reaction tank; A treatment apparatus for carrying out the wastewater treatment method according to the above item [1] or [2], comprising: [5] The treatment device according to [4] above, wherein the reaction tank further comprises a cathode and an anode for electrolyzing water, the anode being an insoluble electrode, and the amount of hydrogen peroxide supplied is adjusted by controlling the electrode potential. [6] The treatment device according to [4] or [5] above, characterized in that the means for supplying the hydrogen peroxide solution is controlled based on the electric potential of the organic wastewater in the reaction tank measured by an oxidation-reduction potentiometer installed in the reaction tank, thereby adjusting the supply of the hydrogen peroxide solution.

[0015] The present invention provides a method and apparatus for treating organic matter contained in general industrial wastewater, such as chemical cleaning wastewater, organic acid wastewater, and wastewater mixed with organic rust inhibitors, and in wastewater from nuclear facilities in situ. The method for treating general industrial wastewater and wastewater from nuclear facilities in situ of the present invention is characterized in that a combination of copper ions and cobalt ions is added as a catalyst in a method for treating organic matter in wastewater using hydrogen peroxide.

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

[0017] The wastewater pH during the treatment reaction is controlled in the range of 6.0 to 8.5, preferably 6.0 to 7.5, and more preferably 6.0 to 7.0.

[0018] The copper ions and cobalt ions serving as catalysts are added so that the 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 copper ions: 0.25 mmol / L to 0.5 mmol / L and cobalt ions: 0.5 mmol / L to 2 mmol / L. The cobalt ion concentration in the wastewater during the treatment reaction is preferably equal to or higher than the copper ion concentration. When it is desired to reduce the concentration of copper ions and cobalt ions added from the viewpoint of the discharge of the treated water, they can be suppressed to about 0.1 mmol / L each. This makes it possible to suppress the copper ion concentration in the treated water low, and to easily reduce it to below the discharge standard value by post-treatment as necessary.

[0019] In the wastewater treatment method of the present invention, an aqueous solution containing copper ions and cobalt ions is added to wastewater containing organic matter (hereinafter referred to as "organic wastewater"), the pH is adjusted, and then hydrogen peroxide solution is added to oxidize and decompose the organic matter. By adding copper ions and cobalt ions in advance to adjust the pH before adding hydrogen peroxide solution, it is possible to suppress unnecessary reactions such as the self-decomposition of hydrogen peroxide and efficiently oxidize and decompose the organic matter in the wastewater.

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

[0021] The reaction vessel may be provided with a cathode and an anode for electrolyzing water, an insoluble electrode being used as the anode, and the amount of hydrogen peroxide supplied may be adjusted by controlling the electrode potential.

[0022] The means for supplying the hydrogen peroxide solution may be configured to be controlled based on the potential of the organic wastewater in the reaction tank measured by an oxidation-reduction potentiometer provided in the reaction tank, thereby adjusting the supply of the hydrogen peroxide solution. Effect of the Invention

[0023] According to the present invention, an aqueous solution containing copper ions and cobalt ions is added to organic matter contained in general industrial wastewater such as chemical cleaning wastewater, organic acid wastewater, and organic rust inhibitor mixed wastewater, and in wastewater from nuclear facilities, and the organic matter is oxidized and decomposed to carbon dioxide and water by adding hydrogen peroxide after adjusting the pH. The copper ions and cobalt ions act as catalysts for generating active oxygen species. Since the amount of copper ions and cobalt ions added is small, the amount of secondary waste generated can be reduced to a small amount and removed from the treated water by, for example, ferrite formation using a small amount of iron powder or adsorption and precipitation using a small amount of iron-based coagulant. This makes it possible to avoid the need for energy supply such as ultraviolet ray irradiation equipment and heating equipment, and to treat organic waste liquid with a simple device, thereby solving problems such as the initial cost of manufacturing a complex device, the operating cost due to energy input, and the increase in sludge disposal costs. [Brief description of the drawings]

[0024] [Figure 1] 1 is a schematic explanatory diagram showing one embodiment of a treatment device for treating organic matter in wastewater according to the present invention. [Diagram 2] FIG. 1 is a schematic explanatory diagram showing an embodiment of a treatment device for treating organic matter in wastewater according to the present invention, the treatment device having a configuration for controlling the supply amount of hydrogen peroxide. [Diagram 3] 1 is a graph showing activation of hydrogen peroxide treatment by the addition of a copper-cobalt composite catalyst. [Figure 4] 1 is a graph showing the relationship between pH conditions and TOC reduction rate. [Diagram 5] 1 is a graph showing the results of a test for reducing the concentration of an added catalyst. [Figure 6] 1 is a graph showing an example of treatment of organic wastewater having a high initial TOC concentration. Preferred Embodiments

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

[0026] One embodiment of an apparatus for carrying out the processing method of the present invention is shown in FIG. The treatment device of the present invention comprises a reaction tank 10 for mixing organic wastewater containing organic matter with copper ions and cobalt ions, a pH adjusting means 20, and a supplying means 30 for supplying hydrogen peroxide solution.

[0027] The reaction tank 10 is preferably equipped with, for example, an agitator 40 as a means for mixing the 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 is composed of, for example, a pH meter, a pH adjuster storage tank 21 which is an acid or alkali, and a pH adjuster injection pump 22 which injects the pH adjuster into the reaction tank 10, and preferably has a function of automatically controlling the operation of the pH adjuster injection pump 22 so as to maintain a certain pH range (for example, a pH range of 6.0 or more and 7.0 or less) based on a control signal from the pH meter.

[0029] The hydrogen peroxide supply means 30 is preferably composed of, for example, a hydrogen peroxide storage tank 31 and a hydrogen peroxide injection pump 32, and is provided with a mechanism that can supply hydrogen peroxide after pH adjustment. For example, an automatic control mechanism may be provided that uses a timer to set the pH adjustment start time before the hydrogen peroxide supply start time, or that operates the hydrogen peroxide injection pump when the output range of a pH meter falls within a specified range.

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

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

[0032] Although not shown, the reaction tank 10 may be provided with a treated water pipe for discharging the treated water.

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

[0034] As an aqueous solution containing copper ions, for example, copper sulfate CuSO4·5H2O is preferably used, and as an aqueous solution containing cobalt ions, for example, cobalt sulfate CoSO4·7H2O is preferably used.

[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 are within the above-mentioned predetermined ranges.

[0036] Next, the pH of the raw water in the reaction tank 10 is adjusted using the pH adjustment means 20 to, for example, a range of pH 6.0 to 7.0. The chemical solution used for pH adjustment is preferably, for example, an aqueous solution of 5% sulfuric acid and 5% caustic soda. If the pH fluctuation range is known in advance, it is sufficient to provide only one of the acid or alkali chemical solution storage tanks and a pH adjuster injection pump, but if the pH fluctuation range is unknown, it is preferable to provide both chemical solution storage tanks and a pH adjuster injection pump. It is preferable to continue pH adjustment until the treatment is completed.

[0037] After the pH adjustment, hydrogen peroxide is added using the hydrogen peroxide supply means 30 while continuing stirring in the reaction tank 10. The hydrogen peroxide to be added may be, for example, a commercially available 30% hydrogen peroxide.

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

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

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

[0041] In most cases, it is preferable from the viewpoint of wastewater management to have no residual hydrogen peroxide in the treated water. In that case, it is preferable to stop the injection of hydrogen peroxide solution in the later stage of treatment to allow the hydrogen peroxide to be consumed by the remaining organic matter, or to add a reducing agent such as sodium thiosulfate at the end to decompose the residual hydrogen peroxide.

[0042] When copper ions or cobalt ions remaining in the treated water are a problem, they can be removed by providing a post-treatment device. For example, a sludge sedimentation tank can be provided as the post-treatment device, and copper ions or cobalt ions can be separated by ferritization with iron powder or adsorption and sedimentation with an iron-based coagulant. When the treated water does not contain turbidity, it is also preferable to remove them by adsorption or ion exchange by passing the water through a column of iron material or ion exchange resin. EXAMPLES

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

[0044] [Table 1]

[0045] [Example 1 and Comparative Examples 1 and 2] Activation of hydrogen peroxide treatment by adding copper-cobalt composite catalyst A composite catalyst of copper and cobalt was used in Example 1, a copper catalyst alone was used in Comparative Example 1, and a cobalt catalyst alone was used in Comparative Example 2. 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 the 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 copper ion and cobalt ion concentrations 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 so that the hydrogen peroxide concentration in the raw water was 9000 mg / L (0.9%), and the change in TOC concentration over time was measured.

[0047] [Table 2]

[0048] The results of Example 1, Comparative Example 1 and Comparative Example 2 are shown in FIG. In Example 1, by adding a combination of copper and cobalt as a catalyst, the TOC concentration was reduced to 50 mg / L within 2 hours. In contrast, in Comparative Example 1, in which only copper was added, and Comparative Example 2, in which only cobalt was added, the TOC concentration was still over 200 mg / L even after 4 hours, and no significant reduction in the TOC concentration occurred. This result shows that the combination of copper and cobalt has the unexpected effect of activating hydrogen peroxide, enabling efficient reduction of TOC.

[0049] In addition, 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 had fallen to nearly 0 mg / L. This is believed to be because the activation of hydrogen peroxide was achieved with nearly 100% efficiency by the combined catalyst of copper and cobalt, 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 was shown that the present invention has the effect of eliminating the need for post-treatment, since hydrogen peroxide does not remain in the treated water, even if TOC is reduced by adding an excess of hydrogen peroxide.

[0050] [Comparative Examples 3 to 5 and Examples 2 to 5] Effect of pH on activation of hydrogen peroxide treatment The hydrogen peroxide concentration in the raw water was fixed at 0.9%, the copper ion concentration at 0.5 mmol / L, and the cobalt ion concentration at 2 mmol / L, and the pH of the raw water was changed in the range of 5 to 9 using a pH stat. The TOC concentration after 2 hours of treatment was measured, and the reduction rate 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, it was shown that 30% or more of TOC derived from HOBt could be decomposed within 2 hours in the range of pH 6.0 to 8.5, whereas the removal rate dropped to less than 20% outside the above pH range. Furthermore, it was shown that the removal rate improved to 49% or more in the range of pH 6.0 to 7.5, and more preferably, the removal rate improved to 62% or more in the range of pH 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 conditions of about pH 3 to 4, which are generally used in Fenton treatment using hydrogen peroxide.

[0053] [Examples 6-13] Applicability to various organic wastewater Treatment tests were carried out on various organic wastewaters shown in Table 4 under test conditions controlled at a hydrogen peroxide concentration of 0.9%, copper ion concentration of 0.5 mmol / L, cobalt ion concentration of 2 mmol / L, and pH of 6.5 in the raw water. Example 13 had an initial TOC concentration of 21390 mg / L, which was very high, so it was diluted to 230 mg / L for use in this experiment. The results are shown in Table 4.

[0054] [Table 4]

[0055] As shown in Table 4, organic acids, reducing agents, organic rust inhibitors, alcohols, and aromatic hydrocarbons can all be treated by the method of activating hydrogen peroxide by combining copper ions and cobalt ions according to the present invention. It was also shown that it is possible to reduce the TOC content of chemical cleaning wastewater, which contains a mixture of various organic components and has a very high initial TOC concentration, by diluting it in advance.

[0056] [Example 8, Examples 14-15, Reference Examples 6-8] Conditions for reducing copper-cobalt catalyst concentration A treatment test was conducted to reduce the copper and cobalt ion concentrations in the raw water under test conditions of 0.9% hydrogen peroxide, 230mg / L initial TOC concentration, and pH 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 and cobalt ion concentrations in the raw water are shown in Table 5, and the test results in Figure 5.

[0057] [Table 5]

[0058] As shown in Fig. 5, in the case of copper ion concentrations of 0.1 mmol / L or more shown in Examples 8, 14, and 15, it was possible to reduce the TOC to about 50 mg / L by combining it with a cobalt ion concentration of 0.1 mmol / L or more. On the other hand, as shown in Reference Examples 6 to 8, when the copper ion concentration was reduced to 0.03 mmol / L, the reduction in the TOC concentration stopped at 100 mg / L or more even when the combined cobalt ion concentration was increased to 2 mmol / L. However, compared to Comparative Examples 1 and 2 in which copper ions or cobalt ions were used alone, the TOC concentration was reduced to 200 mg / L or less in 3 hours, and the combined use of copper ions and cobalt ions was effective even in small amounts. These results show that the concentrations of the copper ions and cobalt ions that serve as catalysts are preferably in the ranges of 0.1 to 0.5 mmol / L for copper ions and 0.1 to 2 mmol / L for cobalt ions, and that when it is desired to reduce the concentrations of the copper ions and cobalt ions added, they can each be suppressed to approximately 0.1 mmol / L.

[0059] [Example 16] Treatment of high-concentration wastewater Under the test conditions where the pH was controlled at 6.5, the chemical cleaning wastewater used in Example 13 was adjusted to an initial TOC concentration of 6735 mg / L at a dilution rate lower than that of Example 13, and a treatment test was performed 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 in each run was 3000 mg / L or more and 6000 mg / L or less. 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 the added hydrogen peroxide in mg / L.

[0060] As shown in Figure 6, repeated addition of hydrogen peroxide enabled the TOC reduction treatment of even high-concentration chemical cleaning wastewater. In the high-concentration range of TOC levels above 4000 mg / L, the addition rate of hydrogen peroxide was high, and the TOC could be reduced by adding 5.6 g of hydrogen peroxide per 1 g of TOC in the organic wastewater. As the TOC concentration of the organic wastewater decreased, the addition rate of hydrogen peroxide decreased, and ultimately the TOC was reduced to 42 mg / L by adding 41 times the weight of hydrogen peroxide.

[0061] The above results demonstrate that the method of the present invention for activating hydrogen peroxide by combining copper ions and cobalt ions makes it possible to treat even high-concentration organic wastewater. [Industrial Applicability]

[0062] The organic wastewater treatment method and apparatus of the present invention can smoothly treat wastewater that is difficult to dispose of efficiently on-site, such as general industrial wastewater such as chemical cleaning wastewater, organic acid wastewater, and organic rust inhibitor mixed wastewater, and wastewater from nuclear facilities. It can solve problems in facility operation and management such as low organic matter decomposition efficiency, complex equipment, and large amounts of secondary waste, and can also be a means of solving the problem of residual waste in nuclear facilities toward decommissioning.

Claims

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

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

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

4. a reaction tank for mixing the wastewater containing organic matter with copper ions and cobalt ions; A pH adjusting means for adjusting the pH of the wastewater in the reaction tank; A means for supplying hydrogen peroxide to the reaction tank; 3. A treatment device for carrying out the wastewater treatment method according to claim 1 or 2, comprising:

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

6. 6. The treatment device according to claim 4 or 5, characterized in that the means for supplying the hydrogen peroxide solution is controlled based on the potential of the organic wastewater in the reaction tank measured by an oxidation-reduction potentiometer installed in the reaction tank, thereby adjusting the supply of the hydrogen peroxide solution.

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