Wastewater treatment method using transition metal oxide

Abstract

The present invention relates to a wastewater treatment method using a transition metal oxide, and more particularly to a technique for treating wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus using a transition metal oxide.

Description

Technical Field

[0001] The present invention relates to a wastewater treatment method using a transition metal oxide, and more particularly to a technique for treating wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus using a transition metal oxide.

Background Art

[0002] In nuclear power plants, nuclear-related facilities, and radiation (energy) utilization facilities, refractory organic substances are generated by the use of organic decontaminants, etc., and wastewater containing high-concentration organic substances such as manure and food wastewater, ammonia nitrogen, and phosphorus is generated.

[0003] Refractory organic substances, nitrogen, or phosphorus present in such wastewater reduce the performance of the purification system used in the treatment process, react with metallic radioactive waste generated in other processes, and make their treatment more difficult. Therefore, they must be separated and treated in the treatment process. However, when storing wastewater containing refractory organic substances, nitrogen, or phosphorus in a drum, refractory organic compounds, etc. react with oxidants, increasing the pressure inside the drum and posing a risk of explosion. Moreover, when using the evaporation concentration method, which is one of the treatment methods for radioactive waste such as decontamination waste liquid, environmental hormones such as dioxins may be discharged because the waste to be treated contains refractory organic compounds. Therefore, the above methods may also cause inappropriate problems in the treatment of waste liquid.

[0004] Therefore, research has been continuously conducted to overcome the above-described problems and improve the treatment efficiency and economy of wastewater containing any of refractory organic substances, nitrogen, and phosphorus. As part of such efforts, a technique has been introduced that generates hydroxyl radicals using ultraviolet light and hydrogen peroxide to decompose organic acids (such as oxalic acid) generated from organic acid-based decontamination wastewater, and has been widely used to date. However, in the case of the organic acid treatment technique using radicals as well, since UV with a high energy level is used, the irradiation range of ultraviolet light for generating hydroxyl radicals is very short, and it is necessary to use a large number of UV devices and hydrogen peroxide. To treat approximately 95% of the oxalic acid in the decontamination wastewater, a treatment time of more than 5 hours is required, so there is a problem of low economic efficiency and treatment efficiency. In addition, the present inventors have introduced a wastewater treatment technique by a simple process of injecting a solution pretreated with a semiconductor material doped with an organic or inorganic element and an oxidizing agent into wastewater containing any of refractory organic substances, nitrogen, and phosphorus and irradiating it with radiation. Aside from solving the problem of device corrosion under acidic conditions, there is still a long treatment time and relatively low organic acid treatment efficiency, and there is a problem that a fundamental solution to the treatment efficiency and economic efficiency of wastewater has not been presented.

[0005] Therefore, there is an urgent need for research on a wastewater treatment technique that can efficiently treat wastewater containing any of refractory organic substances, nitrogen, and phosphorus, improve the disadvantage of the existing long treatment time, and at the same time can quickly and perfectly treat the wastewater by the effect of strong oxidative decomposition under alkaline conditions.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention was found to overcome the above-described problems. The problem to be solved by the present invention is to treat wastewater containing at least one of refractory organic substances, nitrogen, and phosphorus under alkaline conditions with a strong oxidative decomposition effect, thereby overcoming the problem of equipment corrosion due to pH, and significantly shortening the treatment time while maintaining high treatment efficiency for refractory organic substances, nitrogen, and phosphorus, so as to greatly improve the economic efficiency of the wastewater treatment process. The present invention provides a method for treating wastewater containing any one of refractory organic substances, nitrogen, and phosphorus.

Means for Solving the Problems

[0007] In order to solve the above-described problems, the present invention provides a wastewater treatment method in which transition metal ions and a peroxide are added to wastewater containing at least one of refractory organic substances, nitrogen, and phosphorus under alkaline conditions.

[0008] Furthermore, the present invention provides a wastewater treatment apparatus including a storage unit for storing wastewater containing at least one of refractory organic substances, nitrogen, and phosphorus, a reaction unit communicating with the storage unit in which any one of the refractory organic substances, nitrogen, and phosphorus is decomposed, and an input unit communicating with the reaction unit for adding a transition metal and a peroxide to react with and decompose any one of the refractory organic substances, nitrogen, and phosphorus.

[0009] Furthermore, the present invention provides a method for removing refractory organic substances contained in decontamination waste liquid used in nuclear-related facilities, including a first step of preparing decontamination waste liquid containing transition metal ions and refractory organic substances, and a second step of adding persulfate to the decontamination waste liquid under alkaline conditions, to provide a method for removing refractory organic substances contained in radioactive waste liquid.

[0010] The present invention also provides a method for removing refractory organic substances contained in liquid scintillator waste liquid used in nuclear-related facilities, which includes a first step of preparing a liquid scintillator waste liquid containing a transition metal nanocatalyst and refractory organic substances, and a second step of adding persulfate to the liquid scintillator waste liquid under alkaline conditions.

[0011] The present invention also provides a method for treating wastewater containing at least one of nitrogen (N) and phosphorus (P), which includes a step of adding a base to the wastewater to adjust the pH to 9 or higher, adding a salt catalyst of a transition metal, and a step of adding a peroxide to the wastewater to oxidize the transition metal salt.

[0012] The present invention also provides a method for removing refractory organic substances contained in decontamination waste liquid used in nuclear-related facilities, which includes a first step of preparing decontamination waste liquid containing transition metal ions and refractory organic substances, and a second step of adding barium hydroxide (Ba(OH)2) and persulfate to the decontamination waste liquid to remove refractory organic substances contained in radioactive waste liquid.

Advantages of the Invention

[0013] By treating wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus under alkaline conditions with a strong oxidative decomposition effect, the present invention can ensure the problem of device corrosion due to pH and the stability of process operation. In addition, while maintaining a treatment efficiency equal to or higher than that of conventional treatment methods for wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus, the treatment time can be shortened by at least 10 times, thus significantly improving the economic efficiency of the wastewater treatment process.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0015] Hereinafter, examples of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily carry them out. The present invention can be embodied in various different forms and is not limited to the examples described herein. As described above, the technology for treating wastewater containing any one or more of conventional refractory organic substances, nitrogen, and phosphorus has problems such as a decrease in process efficiency due to excessive treatment time and low treatment efficiency, and equipment corrosion due to acidic conditions, and there are limitations in treating efficiently. Further, according to the conventional treatment method using microorganisms, since the growth rate of nitrifying microorganisms is slow, there are problems such as an increase in the volume of the aeration tank and a lengthening of the residence time.

[0016] Therefore, the present invention provides a wastewater treatment method for wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus, which includes a first step of preparing the wastewater containing transition metal ions and a second step of adding a peroxide to the wastewater under alkaline conditions, and has searched for solutions to the above-described problems.

[0017] Through this, the present invention can guarantee the problem of equipment corrosion due to pH and the stability of process operation by treating wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus under alkaline conditions with a strong oxidative decomposition effect. Further, while maintaining a treatment efficiency equal to or higher than that of the conventional treatment method for wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus, the treatment time can be shortened by at least 10 times or more, so that the economy of the wastewater treatment process can be significantly improved.

[0018] Hereinafter, the wastewater treatment method according to the present invention will be described.

[0019] The first step of the wastewater treatment method according to the present invention is to prepare the wastewater containing transition metal ions.

[0020] The wastewater may be radioactive wastewater generated in a nuclear facility or livestock wastewater. At this time, the radioactive wastewater may be decontamination waste liquid or liquid scintillator waste liquid generated in a nuclear facility. Further, the livestock wastewater may be not only contaminated wastewater containing a high concentration of organic substances containing at least one of nitrogen (N) and phosphorus (P), but also wastewater containing a high salt content. The decontamination waste liquid means waste liquid generated by a decontamination process performed at a nuclear power plant decommissioning facility, a radiation (energy) facility, etc., and more specifically, may be waste liquid containing an organic decontamination agent. Such a refractory organic compound containing an organic decontamination agent deteriorates the performance of the purification system used in the treatment process during the treatment of radioactive waste liquid, and reacts with metallic radioactive waste generated in other processes, making its treatment more difficult. Therefore, separation and disposal of the refractory organic compound are essential.

[0021] In addition, the liquid scintillator waste liquid is waste liquid generated by using a liquid scintillation counter (Liquid Scintillation Counter) for purposes such as measurement and analysis of beta nuclides, and can include, for example, waste fluorescent liquid. At this time, the liquid scintillator waste liquid is not particularly limited as long as it is a known type for radiation measurement such as a liquid scintillator substance or a plastic scintillator substance, and may include these. Moreover, the waste fluorescent liquid can indicate waste liquid containing a compound containing a benzene ring as a nuclear structure used as a scintillator substance. The waste fluorescent liquid is not limited to this, but may include, for example, one or more selected from the group consisting of triethyl phosphate; p-bis(o-methylstyryl)benzene; sodium dioctyl sulfosuccinate; ethylene oxide-nonylphenol polymer; 2,5-diphenyloxazole; 1,4-bis[5-phenyloxazol-2-yl]benzene; diisopropylnaphthalene; and a compound of phosphoric acid, 2-ethylhexyl ester and 2,2'-iminobis.

[0022] At this time, since the refractory organic matter may vary depending on the type of wastewater, it is not particularly limited, and may include, for example, one or more selected from the group consisting of oxalic acid, citric acid, formic acid, picolinic acid, ethylenediamine-N,N,N',N'-tetraacetic acid (Ethylenediamine-N,N,N',N'-tetraacetic acid, EDTA), gluconic acid, acetic acid, and sulfamic acid (Sulfamic Acid).

[0023] On the one hand, in the present invention, the efficient separation and disposal / treatment of the refractory organic compound means reducing the content of the refractory organic compound in the above-mentioned wastewater, and ultimately can also mean substantially removing the organic decontaminant (that is, reducing the content of the organic decontaminant in the decontaminated wastewater to approximately 0%). More specifically, in the present invention, the efficient treatment of the refractory organic compound in the wastewater means reducing the content of oxalic acid, and ultimately can also mean substantially removing oxalic acid (that is, reducing the content of oxalic acid in the decontaminated wastewater to approximately 0%).

[0024] In order to treat such wastewater, the present invention performs a second step of introducing a peroxide into the wastewater under alkaline conditions. At this time, the second step can be performed by introducing barium hydroxide or sodium hydroxide under alkaline conditions with a pH of 9 or higher.

[0025] Generally, when persulfate is injected in an acidic or neutral environment, sulfate radicals are generated by transition metal ions present in wastewater containing one or more of refractory organic substances, nitrogen, and phosphorus, and the organic waste liquid is decomposed by a radical reaction. However, since the radical conversion time of persulfate is slow, it takes a long time. In contrast, in a highly basic environment with a pH of 9 or higher, transition metal ions are converted into transition metal oxides. When a peroxide is injected into such transition metal oxides, the generation of sulfate radicals and hydroxyl radicals is suppressed, the peroxide is adsorbed on the surface of the transition metal oxides, and the oxidation value of the transition metal oxides instantaneously increases.

[0026] That is, in the present invention, barium hydroxide or sodium hydroxide is injected into wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus, and a peroxide is injected to convert transition metal ions present in the wastewater into transition metal oxides. Such transition metal oxides adsorb the peroxide, and the oxidation state of the transition metal oxides increases. When the oxidation state of the transition metal oxides increases, the oxidizing power increases significantly, and the wastewater can be rapidly treated with excellent efficiency by a catalytic reaction of the metal oxides other than the sulfate radical reaction by persulfate. Thus, when the transition metal ions in the wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus are not sufficient to react with the peroxide, the present invention can add transition metal ions before the two steps mentioned above.

[0027] In addition, in the second step of the method for treating wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus according to the present invention, if only any two of the three conditions of the presence of transition metal ions, alkaline conditions, and peroxide are satisfied without satisfying all three conditions, the present invention cannot guarantee a fast treatment efficiency for the targeted refractory organic substances, nitrogen, and phosphorus.

[0028] That is, in the present invention, when all three conditions of the presence of transition metal ions, alkaline conditions, and peroxide are satisfied, refractory organic substances and the like are removed by 90% or more within 10 minutes after the transition metal and peroxide are added. Therefore, while maintaining a treatment efficiency equal to or higher than that of the conventional treatment method, the treatment time can be shortened by at least 10 times. It can be seen that the economy of the wastewater treatment process containing any one or more of refractory organic substances, nitrogen, and phosphorus can be significantly improved.

[0029] For this purpose, the transition metal ion can be at least any one selected from the group consisting of scandium ion, titanium ion, vanadium ion, chromium ion, manganese ion, cobalt ion, cerium ion, copper ion, nickel ion, zinc ion, yttrium ion, zirconium ion, niobium ion, molybdenum ion, technetium ion, ruthenium ion, rhodium ion, palladium ion, silver ion, cadmium ion, hafnium ion, tantalum ion, tungsten ion, rhenium ion, osmium ion, iridium ion, platinum ion, gold ion and mercury ion, and more preferably, it may be nickel ion or copper ion. That is, since the present invention aims to efficiently treat wastewater through a high oxidation reaction by increasing the oxidation state of a transition metal with a peroxide, the transition metal ion must be a transition metal ion whose oxidation state can be increased by a peroxide.

[0030] In addition, in terms of improving the wastewater treatment efficiency, the peroxide can use persulfate or peroxide capable of oxidizing a transition metal oxide. As a non-limiting example thereof, one or more selected from the group consisting of peroxydisulfate, peroxymonosulfate and salts thereof can be used. At this time, the "salt" may include one or more selected from the group consisting of potassium salt, sodium salt and ammonium salt.

[0031] On the other hand, when peroxydisulfate is used as the persulfate, the oxidation-reduction potential difference is +2.1V, and when peroxymonosulfate is used, the oxidation-reduction potential difference is +1.8V. However, since the oxidizing power for oxidizing the transition metal oxide is sufficient even when peroxymonosulfate is used, it can be appropriately selected and used according to the oxidation-reduction potential difference, the amount and type of wastewater, etc. According to a preferred embodiment of the present invention, taking the case where the transition metal is nickel as an example, since ionic nickel mainly exists as divalent ions, at pH 9 or higher, it can exist as nickel oxide such as NiO, Ni2O3 or Ni(OH)2. When persulfate according to the present invention is adsorbed on the surface of such nickel oxide, the nickel oxidation state increases from +2 to +3 and +4 or higher by persulfate, and the nickel oxide with an instantaneously increased oxidation state is in a very unstable state, so the redox potential becomes high and it can become a strong oxidizing agent. The Ni of nickel oxide 3+ / Ni 2+ has a redox potential of 3.5 - 3.8 V, which has a much higher oxidizing power than the redox potential of hydroxyl radical (2.8 V) or sulfate radical (2.5 - 3.1 V). Generally, the redox potential of transition metal oxides increases as the oxidation state increases for late transition metals, and increases in the order of Ti < V < Cr < Mn < Co < Ni, etc. Also, the greater the oxidation state of the transition metal oxide, the higher the redox potential, and M 3+ / / M 2+ <M 4+ / / M 3+ has the characteristics.

[0032] That is, nickel ions or nickel oxide are most stable when present at +2, so the nickel oxide converted to +2 valence will adsorb persulfate again and participate in the oxidation reaction.

[0033] On the other hand, in the case of iron, at pH 4 or higher, it exists as iron oxide such as FeO, Fe2O3, Fe(OH)2, but the reaction of being oxidized from +2 to +3 is not a spontaneous reaction at -0.47 V, and rather than being oxidized from +3 to +4, it is converted from +3 to +2, so almost no catalytic effect by persulfate can be expected.

[0034] On the one hand, the transition metal can be contained in an amount of 0.1 to 10 moles relative to the refractory organic substance, more preferably, it can be contained in an amount of 0.5 to 5 mole parts relative to the refractory organic substance, and most preferably, it can be contained in an amount of 0.8 to 2 moles relative to the refractory organic substance. At this time, if the transition metal is contained in an amount of less than 0.1 mole relative to the refractory organic substance, there may be a problem that the production amount of metal oxide sufficient to decompose the waste liquid is small, resulting in a decrease in treatment efficiency. Also, if the transition metal is contained in an amount exceeding 10 moles relative to the refractory organic substance, the solubility of persulfate is decreased, the amount of persulfate adsorbed on the metal oxide is decreased, and there may be a problem that the treatment efficiency is decreased.

[0035] Also, the peroxide can be contained in an amount of 1 to 20 moles relative to the refractory organic substance, more preferably, it can be contained in an amount of 3 to 18 moles relative to the refractory organic substance. At this time, if the peroxide is contained in an amount of less than 1 mole relative to the refractory organic substance, after being adsorbed on the metal oxide, the amount of peroxide capable of oxidizing the transition metal is decreased, and there may be a problem that the treatment efficiency is decreased. Also, if the peroxide is contained in an amount exceeding 20 parts by weight relative to the refractory organic substance, the pH of the waste liquid is rapidly decreased, and due to the rapid chemical reactivity of the peroxide, there may be a problem that safety accidents such as explosion may occur. Thus, the present invention can guarantee the problem of apparatus corrosion due to pH and the stability of process operation by treating wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus under alkaline conditions with a strong oxidative decomposition effect. Also, while maintaining a treatment efficiency equal to or higher than that of a conventional method for treating wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus, the treatment time can be shortened by at least 10 times, so that the economy of the wastewater treatment process can be significantly improved.

[0036] Next, the wastewater treatment apparatus according to the present invention will be described. However, in order to avoid duplication, the description of the parts having the same technical idea as the above-described wastewater treatment method will be omitted. The wastewater treatment apparatus according to the present invention includes a storage unit for storing wastewater containing any one or more of hardly decomposable organic substances, nitrogen, and phosphorus, a reaction unit communicating with the storage unit in which any one of the hardly decomposable organic substances, nitrogen, and phosphorus is decomposed, and an input unit communicating with the reaction unit for introducing a transition metal and a peroxide to react with and decompose any one of the hardly decomposable organic substances, nitrogen, and phosphorus.

[0037] The storage unit serves to store wastewater containing any one or more of hardly decomposable organic substances, nitrogen, and phosphorus in order to treat the wastewater.

[0038] Next, the reaction unit communicates with the storage unit and provides a space where wastewater containing any one or more of the hardly decomposable organic substances, nitrogen, and phosphorus in the storage unit is transferred and reacts with the transition metal and peroxide introduced from the input unit.

[0039] At this time, an alkali is injected into the reaction unit, and treatment can proceed through oxidation of the hardly decomposable organic substances contained in the wastewater under alkaline conditions with a pH of 9 or higher. That is, the wastewater is transferred to the reaction unit via the storage unit, and the transferred wastewater is injected and reacted with transition metal ions, an alkali, and a peroxide via the input unit, whereby the transition metal in the wastewater can be converted into a metal oxide. By adsorbing the peroxide by the metal oxide thus converted, the oxidation value of the metal oxide increases, whereby the oxidizing power greatly increases, and the wastewater can be rapidly treated with excellent efficiency by a catalytic reaction of the metal oxide rather than a sulfate radical reaction by persulfate.

[0040] Next, the input unit communicates with the reaction unit and serves to introduce a transition metal, an alkali, and a peroxide into the reaction unit.

[0041] The transition metal in such an input section can be contained in an amount of 0.1 to 10 moles, more preferably 0.5 to 5 moles, and most preferably 0.8 to 2 moles, relative to the refractory organic matter contained in the storage section.

[0042] In addition, the persulfate can be contained in an amount of 1 to 20 moles, more preferably 3 to 18 moles, relative to the refractory organic matter.

[0043] Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples do not limit the scope of the present invention and should be construed to assist in the understanding of the present invention.

Examples

[0044] Example 1 - Treatment of decontamination waste liquid according to the present invention - low-concentration oxalic acid, nickel oxide In the decontamination process of a nuclear power plant, nickel, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and a complexing agent. The concentration of oxalic acid was adjusted to 2 mM according to the concentration present in the decontamination waste liquid. The alkali was adjusted to pH 12 using 2.5 M NaOH.

[0045] Thereafter, nickel was prepared to 0.625 M using nickel sulfate and then injected to a concentration of 2 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 10, 20, and 30 mM, and the effect of oxalic acid treatment over time was confirmed.

[0046] At pH 12, the effect of oxalic acid treatment with nickel, alkali, and persulfate was confirmed by measuring TOC to confirm the effect of complete removal of organic carbon. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency of oxalic acid were calculated and shown in Table 1 and Figure 1 below.

[0047]

Table 1

[0048] As confirmed in Table 1 and Figure 1, as the injection amount of persulfate increases to 2, 6, 10, 20, 30 mM, 87.8, 90.1, 90.4, 90.9, 92.0% is removed. After 3 minutes of reaction time, 88.8, 88.9, 90.2, 92.5, 92.5% of oxalic acid is removed under the conditions of injection amounts of persulfate of 2, 6, 10, 20, 30 mM, indicating that most of the oxalic acid is removed very quickly.

[0049] Example 2 - Treatment of decontamination waste liquid according to the present invention - Low-concentration oxalic acid, copper oxide In the decontamination process of nuclear power plants, to treat oxalic acid used as an organic acid and a complexing agent, copper, alkali, and persulfate were injected, and the concentration of oxalic acid was adjusted to 2 mM according to the concentration present in the decontamination waste liquid. The alkali was adjusted to pH 12 using 2.5 M NaOH.

[0050] Subsequently, copper was prepared to 0.625 M using copper sulfate and then injected to a concentration of 2 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 10, 20, 30 mM, and the effect of oxalic acid treatment over time was confirmed.

[0051] At pH 12, the effect of oxalic acid treatment by copper, alkali, and persulfate was confirmed by measuring TOC, showing that organic carbon was completely removed. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency of oxalic acid were calculated and shown in Table 2 and Figure 2 below.

[0052]

Table 2

[0053] As confirmed in Table 2 and Figure 2 above, as the injection amount of persulfate increased to 2, 6, 10, 20, and 30 mM, the removal rates were 86.4, 86.7, 85.8, 90.2, and 91.5% respectively. After 3 minutes of reaction time, 85.7, 85.8, 88.1, 88.3, and 91.4% of oxalic acid was removed under the conditions of injection amounts of persulfate at 2, 6, 10, 20, and 30 mM. It can be seen that most of the oxalic acid was removed very quickly.

[0054] Example 3-1 - Treatment of decontamination waste liquid according to the present invention - Medium-concentration oxalic acid and nickel oxide In the decontamination process of nuclear power plants, nickel, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and a complexing agent. The concentration of oxalic acid was adjusted to 10 mM according to the concentration present in the decontamination waste liquid. The alkali was adjusted to pH 12 using 2.5 M NaOH.

[0055] After that, nickel was prepared to 0.625 M using nickel sulfate and then injected to a concentration of 10 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 0, 10, 20, 30, 50, 100, and 150 mM, and the effect of oxalic acid treatment over time was confirmed.

[0056] At pH 12, the effect of oxalic acid treatment by nickel, alkali, and persulfate was confirmed by measuring the TOC, showing that the organic carbon was completely removed. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency of oxalic acid were calculated and shown in the following table and Figure 3a.

[0057] [Table 3]

[0058] As confirmed in Table 3 and Figure 3a above, as the injection amount of persulfate increased to 0, 10, 30, 50, 100, 150 mM, the removal rates were 3.1, 93.3, 97.3, 97.2, 96.8, 98.3% respectively. After 3 minutes of reaction time, the removal rates of oxalic acid were 0.8, 92.2, 96.9, 96.2, 95.6, 95.9% under the conditions of persulfate injection amounts of 0, 10, 30, 50, 100, 150 mM, indicating that most of the oxalic acid was removed very quickly.

[0059] Example 3-2 - Treatment of decontamination waste liquid according to the present invention - Medium-concentration oxalic acid and copper oxide In the decontamination process of nuclear power plants, copper, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and complexing agent. The concentration of oxalic acid was adjusted to 10 mM according to the concentration present in the decontamination waste liquid. The alkali was adjusted to pH 12 using 2.5 M NaOH.

[0060] Subsequently, copper was prepared to 0.625 M using copper sulfate and then injected to a concentration of 10 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 0, 10, 20, 30, 50, 100, 150 mM, and the treatment effect of oxalic acid over time was confirmed.

[0061] At pH 12, the treatment effect of oxalic acid by copper, alkali, and persulfate was confirmed by measuring TOC to ensure complete removal of organic carbon. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency of oxalic acid were calculated and shown in Table 4 and Figure 3b below.

[0062]

Table 4

[0063] As confirmed in Table 4 and Figure 3b above, as the injection amount of persulfate increased from 0, 10, 30, 50, 100 to 150 mM, the removal rates were 4.7, 3.7, 6.9, 97.7, 97.9, 99.2% respectively. After 3 minutes of reaction time, the removal rates of oxalic acid were 3.8, 4.5, 40.5, 97.7, 97.7, 99.2% under the conditions of persulfate injection amounts of 0, 10, 30, 50, 100, 150 mM. It can be seen that most of the oxalic acid was removed very quickly.

[0064] Example 4-1 - Treatment of decontamination waste liquid according to the present invention - High-concentration oxalic acid and nickel oxide In the decontamination process of nuclear power plants, nickel, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and a complexing agent. The concentration of oxalic acid was adjusted to 20 mM according to the concentration present in the decontamination waste liquid. The alkali was adjusted to pH 12 using 2.5 M NaOH.

[0065] Subsequently, nickel was prepared to 0.625 M using nickel sulfate and then injected to a concentration of 20 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 0, 20, 40, 60, 100, 200, 300 mM, and the effect of oxalic acid treatment over time was confirmed.

[0066] At pH 12, the effect of oxalic acid treatment by nickel, alkali, and persulfate was confirmed by measuring TOC, showing that organic carbon was completely removed. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted to calculate the concentration and treatment efficiency of oxalic acid, as shown in Table 5 and Figure 4a below.

[0067] [Table 5]

[0068] As confirmed in Table 5 and Figure 4a above, as the injection amount of persulfate increased from 0, 20, 40, 60, 100, 200 to 300 mM, the removal rates were 2.4, 88.4, 98.5, 98.8, 98.7, 98.8%. After 3 minutes of reaction time, the removal rates of oxalic acid were 1.7, 82.3, 98.4, 98.7, 98.7, 98.7% under the conditions of injection amounts of persulfate at 0, 20, 40, 60, 100, 200, 300 mM, indicating that most of the oxalic acid was removed very quickly.

[0069] Example 4-2 - Treatment of Decontamination Waste Liquid According to the Present Invention - High Concentration of Oxalic Acid and Copper Oxide In the decontamination process of nuclear power plants, copper, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and complexing agent. The concentration of oxalic acid was adjusted to 20 mM according to the concentration present in the decontamination waste liquid. The alkali was adjusted to pH 12 using 2.5 M NaOH.

[0070] After that, copper was prepared to 0.625 M using copper sulfate and then injected to a concentration of 20 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 0, 20, 40, 60, 100, 200, 300 mM, and the effect of oxalic acid treatment over time was confirmed.

[0071] At pH 12, the effect of oxalic acid treatment by copper, alkali, and persulfate was confirmed by measuring TOC to ensure complete removal of organic carbon. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency of oxalic acid were calculated and shown in Table 6 and Figure 4b below.

[0072] [Table 6]

[0073] As confirmed in Table 6 and Figure 4b above, as the injection amount of persulfate increased to 0, 20, 40, 60, 100, 200, 300 mM, the removal rates were 1.1, 87.0, 98.6, 98.5, 98.6, 98.6%. After 3 minutes of reaction time, 1.2, 91.3, 98.4, 98.5, 98.6, 98.7% of oxalic acid was removed under the conditions of injection amounts of persulfate of 0, 20, 40, 60, 100, 200, 300 mM, indicating that most of the oxalic acid was removed very quickly.

[0074] Comparative Example 1 - Treatment of decontaminated waste liquid (nickel, acidic condition) For comparison with the examples, acid and persulfate were injected into the organic waste liquid containing oxalic acid. The concentration of oxalic acid used in this experiment was adjusted to 2 mM according to the concentration present in the decontaminated waste liquid. The acid was adjusted to pH 2 using 2.5 M H2SO4. Then, nickel was prepared to 0.625 M using nickel sulfate and then injected to a concentration of 2 mM, which is the concentration present in the decontaminated waste liquid. Subsequently, persulfate was injected to concentrations of 10, 20, 30 mM, and the effect of oxalic acid treatment over time was confirmed.

[0075] At pH 2, the effect of oxalic acid treatment by nickel, alkali, and persulfate was confirmed by measuring TOC to verify the effect of complete removal of organic carbon. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency of oxalic acid were calculated and shown in Table 7 and Figure 5a below.

[0076]

Table 7

[0077] As confirmed in Table 7 and Figure 5a above, as the injection amount of persulfate increased to 10, 20, 30 mM, the removal rates were 19.5, 23.7, 32.0%. Although a part of the oxalic acid was decomposed, the rate was significantly lower compared to the alkaline condition, indicating a limitation in the treatment of decontaminated waste liquid.

[0078] Comparative Example 2 - Treatment of decontamination waste liquid (copper, acid condition) For comparison with the examples, acid and persulfate were injected into the organic waste liquid. The concentration of oxalic acid used in this experiment was adjusted to 2 mM according to the concentration present in the decontamination waste liquid. The acid was adjusted to pH 2 using 2.5 M H2SO4. Then, copper was prepared to 0.625 M using copper sulfate and then injected to a concentration of 2 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 10, 20, and 30 mM, and the effect of oxalic acid treatment over time was confirmed.

[0079] At pH 2, the effect of oxalic acid treatment by copper, acid, and persulfate was confirmed by measuring TOC, and the effect of completely removing organic carbon was verified. Also, after the treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency of oxalic acid were calculated and shown in Table 8 and Figure 5b below.

[0080] [Table 8]

[0081] As confirmed in Table 8 and Figure 5b above, as the injection amount of persulfate increased to 10, 20, and 30 mM, the removal rates were 18.4%, 25.3%, and 31.2% respectively. Although a part of the oxalic acid was decomposed, the rate was significantly lower compared to the alkaline condition, indicating a limit in the treatment of decontamination waste liquid.

[0082] Comparative Example 3 - Treatment of decontamination waste liquid (excluding nickel only persulfate) To confirm the effect of injecting persulfate under very high alkaline conditions of pH 12, after adjusting to pH 12 using 2.5 M NaOH, the effect of oxalic acid treatment was confirmed for the case where only nickel was injected without persulfate. When only nickel was injected without persulfate, after preparing oxalic acid to 2 mM, nickel was prepared to 0.625 M using nickel sulfate and then injected to concentrations of 1, 2, and 3 mM, which are the concentrations present in the decontamination waste liquid.

[0083] Subsequently, the effect of oxalic acid treatment over time was confirmed and shown in Table 9 and Figure 6a below.

[0084]

Table 9

[0085] As confirmed in Table 9 and Figure 6a, when only nickel was injected without persulfate, as the nickel injection amount increased to 1, 2, and 3 mM, the removal rates were 0.5%, 0.4%, and 0.4% at a reaction time of 120 minutes, and almost no removal occurred.

[0086] Comparative Example 4 - Treatment of decontamination waste liquid (copper only, excluding persulfate) To confirm the effect of injecting copper oxide and persulfate under alkaline conditions at pH 12, after adjusting the pH to 12 using 2.5 M NaOH, the effect of oxalic acid treatment was confirmed for the case where only copper was injected without persulfate. When only copper was injected without persulfate, after preparing oxalic acid to 2 mM, copper was prepared to 0.625 M using copper sulfate and injected to be 1, 2, and 3 mM, which are the concentrations present in the decontamination waste liquid. Subsequently, the effect of oxalic acid treatment over time was confirmed. At pH 12, the effect of oxalic acid treatment by alkali and copper was confirmed by measuring TOC, and the effect of completely removing organic carbon was observed. Also, after the treatment, subtracting the TOC concentration of the remaining oxalic acid, the concentration of oxalic acid and the treatment efficiency (%) were calculated and shown in Table 10 and Figure 6b.

[0087]

Table 10

[0088] As confirmed in Table 10 and Figure 6b, when only copper was injected without persulfate, as the copper injection amount increased to 1, 2, and 3 mM, the removal rates were 0.3%, 0.2%, and 0.3% at a reaction time of 120 minutes, and almost no removal occurred.

[0089] Comparative Example 5 - Treatment of decontamination waste liquid (excluding transition metals) To confirm the effect of injecting transition metals under very high alkaline conditions of pH 12, after adjusting to pH 12 using 2.5 M NaOH, the oxalic acid treatment effect was confirmed for the case where only persulfate was injected without transition metals. When only persulfate was injected without transition metals, after preparing oxalic acid to 2 mM, persulfate was injected to be 10, 20, 30 mM, and the oxalic acid treatment effect over time was confirmed, which is shown in Table 11 and Figure 7 below.

[0090]

Table 11

[0091] As confirmed in Table 11 and Figure 7 above, when only persulfate was injected without transition metals, as the injection amount of persulfate increased from 10, 20, 30 mM, it was removed at 1.2, 1.4, 1.6% in 120 minutes of reaction time and was hardly removed.

[0092] Comparative Example 6 - Treatment of decontamination waste liquid (transition metal: iron) To compare with Example 1 above, alkali and persulfate were injected into the decontamination waste liquid containing oxalic acid and iron, and the concentration of oxalic acid was adjusted to 2 mM according to the concentration present in the decontamination waste liquid. The alkali was adjusted to pH 12 using 2.5 M NaOH. Thereafter, iron was prepared to 0.625 M using iron sulfate and then injected to be 2 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to be 10, 20, 30 mM, and the oxalic acid treatment effect over time was confirmed.

[0093] At pH 12, the effect of oxalic acid treatment with iron, alkali, and persulfate was confirmed by measuring TOC, showing that organic carbon was completely removed. Also, after the treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency (%) of oxalic acid were calculated and shown in Table 12 and Figure 8 below.

[0094]

Table 12

[0095] As confirmed in Table 12 and Figure 8 above, as the injection amount of persulfate increased to 10, 20, and 30 mM, the removal rates were 7.4%, 4.3%, and 4.1% respectively, and almost no removal occurred. After 5 minutes of reaction time, under the conditions of persulfate injection amounts of 10, 20, and 30 mM, the TOC concentrations of oxalic acid were 37.2, 36.0, and 36.3 mg / L respectively, and it seemed that the removal rates were 35.8%, 37.8%, and 37.3%. However, after 30 minutes of reaction time, under the conditions of persulfate injection amounts of 10, 20, and 30 mM, the TOC concentrations of oxalic acid increased to 53.6, 52.7, and 51.9 mg / L. It was found that oxalic acid was temporarily adsorbed on iron oxide and then released again, resulting in an increase in TOC concentration.

[0096] That is, different from nickel oxide, almost no persulfate was adsorbed on iron oxide. As the reaction time elapsed, it was confirmed that the oxalic acid temporarily adsorbed on iron oxide flowed out and remained.

[0097] Comparison Example 7 - Comparison between UV / Hydrogen Peroxide Treatment and Radiation Treatment (pH 3) In the decontamination process of nuclear power plants, to treat oxalic acid used as an organic acid and complexing agent, a conventional general UV / hydrogen peroxide process and a radiation decomposition process with metal ions and oxidants added were used.

[0098] In this experiment, after preparing an aqueous solution with a concentration of 10 mM oxalic acid, the pH was adjusted to 3 to prepare the solution to be treated. Copper ions were used as the metal ions, and persulfate was used as the oxidizing agent. The molar equivalent of copper ions and persulfate was 1:5. UV was carried out using a 1 kW medium-pressure ultraviolet lamp, and 20 mM hydrogen peroxide was added. UV irradiation was performed for 5 hours under temperature conditions of 35 - 55 °C. The radiation was irradiated at irradiation doses of 0, 10, 20, 30, and 50 kGy respectively based on the absorbed dose, and the results are shown in Figures 9 and 10 respectively.

[0099] Referring to Figure 9, as a result of decomposing oxalic acid in the UV / hydrogen peroxide process, at pH 3, it was decomposed at 0, 1, 2, 3, 4, and 5 hours respectively, to 10 mM, 3.0 mM (decomposition rate: 69.8%), 2.3 mM (77%), 1.7 mM (82.7%), 1.2 mM (88%), and 1.0 mM (90.4%), and it was confirmed that the treatment efficiency showed a maximum of 90.4% at 5 hours.

[0100] Also, referring to Figure 10, as a result of irradiating with radiation and decomposing oxalic acid, at pH 3 and an irradiation dose rate of 10 kGy / hr, it was irradiated at 0, 5, 10, 20, 30, and 50 kGy (0, 0.5, 1, 2, 3, and 5 hours) respectively, and 10 mM, 8.7 mM (decomposition rate: 16.7%), 6.8 mM (36.5%), 3.2 mM (69.5%), 1.7 mM (83.4%), 0.8 mM (92.2%) were obtained. At 50 kGy, a maximum treatment efficiency of 92.2% was observed.

[0101]

Table 13

[0102] Experimental Example 1 In Experimental Example 1, an experiment was conducted to confirm that the oxidation reaction of the metal oxide according to the present invention is oxidized to persulfate. That is, since persulfate becomes sulfate radicals or hydroxyl radicals at alkaline pH, the content of the experiment was carried out to show that the present invention is the result of the oxidation of metal oxides that do not involve radical reactions.

[0103] For this purpose, at pH 12, 2 mM of copper oxide and 2 mM of nickel oxide were used respectively with a concentration of 2 mM of oxalic acid, and the concentration of persulfate was 20 mM. Here, 2000 mM of TBA and 2000 mM of MeOH, which are sufficient radical scavenger concentrations, were added to compare the oxalic acid decomposition performance, which is shown in Table 14, Figure 11 and Table 15, Figure 12. It can be seen that TBA and MeOH, which are radical scavengers, can scavenge most of the radicals generated by chemical reactions when present at 1000 times the concentration of the metal oxide.

[0104]

Table 14

[0105]

Table 15

[0106] Referring to Table 14, Figure 11 and Table 15, Figure 12 above, it was found that the oxidation reaction by metal oxides that do not generate radicals because there is almost no influence of the scavenger on all nickel oxides and copper oxides.

[0107] Example 5 - Adjust the pH with Ba(OH)2 for 2 mM of oxalic acid (nickel) In the decontamination process of nuclear power plants, nickel, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and a complexing agent. The concentration of oxalic acid used in this experiment was adjusted to 2 mM according to the concentration present in the decontamination waste liquid. The alkali was Ba(OH)2 injected to adjust the pH to 12. Then, nickel was prepared to 0.625 M using nickel sulfate and then injected to a concentration of 2 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 2, 6, 10, 20, and 30 mM, and the treatment effect of oxalic acid over time was confirmed. At pH 12, the treatment effect of oxalic acid by nickel, alkali, and persulfate was confirmed by measuring TOC, and the effect of completely removing organic carbon was verified. Also, after the treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency (%) of oxalic acid were calculated and shown in Figure 14 and Table 16. As confirmed in Figure 14 and Table 16, as the injection amount of persulfate increased to 2, 6, 10, 20, and 30 mM, it was removed at 79.6, 93.8, 94.1, 93.1, and 89.2%. After 3 minutes of reaction time, 91.9, 93.6, 93.6, 94.1, and 89.9% of oxalic acid was removed under the conditions of persulfate injection amounts of 2, 6, 10, 20, and 30 mM, and it was found that most of the oxalic acid was removed very quickly.

[0108]

Table 16

[0109] Example 6 - Adjusting the pH with NaOH for 2 mM Oxalic Acid (Nickel) The same procedure as in Example 5 was carried out, but sodium hydroxide was used instead of barium hydroxide to analyze the treatment efficiency for oxalic acid, and this is shown in Figure 15 and Table 17. As can be seen from FIG. 15 and Table 17, as the injection amount of persulfate increases to 2, 6, 10, 20, 30 mM, it is removed at 87.8, 90.1, 90.4, 92.0, 90.9%. After 3 minutes of reaction time, 88.8, 88.9, 90.2, 92.5, 92.5% of oxalic acid is removed under the conditions of injection amounts of persulfate of 2, 6, 10, 20, 30 mM, and it was found that most of the oxalic acid was removed very quickly.

[0110]

Table 17

[0111] Experimental Example 2 - Comparison of the effects of barium hydroxide and sodium hydroxide on 2 mM oxalic acid To know the difference between the pH adjustment effect of Ba(OH)2 and the pH adjustment effect of NaOH, the values in Table 17 were subtracted from the values in Table 16, and the waste liquid decomposition effect by the pH adjustment method is shown in Table 18 and FIG. 16.

[0112] As can be seen from Table 18 and FIG. 16 below, the difference between the two conditions was negligible at -8.3, 3.8, 3.7, 1.0, -1.7% as the injection amount of persulfate increased to 2, 6, 10, 20, 30 mM. After 3 minutes of reaction time, under the conditions of injection amounts of persulfate of 2, 6, 10, 20, 30 mM, it was negligible at 3.0, 4.7, 3.4, 1.6, -2.5%, and the difference due to pH adjustment was negligible.

[0113]

Table 18

[0114] Example 7 - Adjusting the pH with Ba(OH)2 for 2 mM oxalic acid (copper) In the decontamination process of a nuclear power plant, copper, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and a complexing agent. The concentration of oxalic acid used in this experiment was adjusted to 2 mM according to the concentration present in the decontamination waste liquid. Alkali was injected with Ba(OH)₂ and adjusted to pH 12. Then, copper was prepared to 0.625 M using copper sulfate and then injected to a concentration of 2 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 2, 6, 10, 20, and 30 mM, and the effect of oxalic acid treatment over time was confirmed. At pH 12, the effect of oxalic acid treatment by copper, alkali, and persulfate was confirmed by measuring TOC, and the effect of complete removal of organic carbon was verified. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency (%) of oxalic acid were calculated and shown in Figure 17 and Table 19. As confirmed in Figure 17 and Table 19, as the injection amount of persulfate increased to 2, 6, 10, 20, and 30 mM, it was removed at 88.6, 99.1, 92.5, 93.5, and 92.1%. After 3 minutes of reaction time, 92.5, 92.7, 87.2, 94.2, and 92.6% of oxalic acid was removed under the conditions of persulfate injection amounts of 2, 6, 10, 20, and 30 mM, and it was found that most of the oxalic acid was removed very quickly.

[0115]

Table 19

[0116] Example 8 - Adjusting pH with NaOH for 2 mM Oxalic Acid (Copper) The same procedure as in Example 7 was performed, but sodium hydroxide was used instead of barium hydroxide to analyze the treatment efficiency for oxalic acid, and this is shown in Figure 18 and Table 20.

[0117] As can be seen from Fig. 18 and Table 20, as the injection amount of persulfate increases to 2, 6, 10, 20, 30 mM, 86.4, 86.7, 85.8, 90.2, 90.5% is removed. After 3 minutes of reaction time, 85.7, 85.8, 88.1, 88.3, 91.4% of oxalic acid is removed under the conditions of persulfate injection amounts of 2, 6, 10, 20, 30 mM, and it was found that most of the oxalic acid was removed very quickly.

[0118]

Table 20

[0119] Experimental Example 3 - Comparison of the effects of barium hydroxide and sodium hydroxide on 2 mM oxalic acid To know the difference between the Ba(OH)₂ pH adjustment effect and the NaOH pH adjustment effect, the values in Table 20 were subtracted from the values in Table 19, and the waste liquid decomposition effect by the pH adjustment method is shown in Fig. 19 and Table 21.

[0120] As can be seen from the following Fig. 19 and Table 21, the difference between the two conditions was negligible at 2.2, 12.4, 6.7, 3.3, 1.6% as the injection amount of persulfate increased to 2, 6, 10, 20, 30 mM. After 3 minutes of reaction time, it was negligible at 6.8, 6.9, -0.8, 5.9, 1.3% under the conditions of persulfate injection amounts of 2, 6, 10, 20, 30 mM, and the difference due to pH adjustment was negligible.

[0121]

Table 21

[0122] Example 9 - Adjusting the pH with Ba(OH)₂ for 10 mM oxalic acid (nickel) In the decontamination process of nuclear power plants, nickel, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and a complexing agent. The concentration of oxalic acid used in this experiment was adjusted to 10 mM according to the concentration present in the decontamination waste liquid. As the alkali, Ba(OH)₂ was injected to adjust the pH to 12. Then, nickel was prepared to 0.625 M using nickel sulfate and then injected to a concentration of 10 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 0, 10, 30, 50, 100, and 150 mM to confirm the effect of oxalic acid treatment over time. At pH 12, the effect of oxalic acid treatment by nickel, alkali, and persulfate was confirmed by measuring TOC, and the effect of complete removal of organic carbon was confirmed. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency (%) of oxalic acid were calculated and shown in Figure 20 and Table 22. As confirmed in Figure 20 and Table 22, as the injection amount of persulfate increased from 0, 10, 30, 50, 100, to 150 mM, it was removed at 70.5, 96.3, 98.4, 98.5, 98, and 98.5%. After 3 minutes of reaction time, under the conditions of injection amounts of persulfate of 10, 30, 50, 100, and 150 mM, 68.3, 96.7, 98.6, 98.7, 98.3, and 98.3% of oxalic acid was removed, and it was found that most of the oxalic acid was removed very quickly.

[0123]

Table 22

[0124] Example 10 - Adjusting the pH with NaOH for 10 mM oxalic acid (nickel) The same procedure as in Example 9 was carried out, but sodium hydroxide was used instead of barium hydroxide to analyze the treatment efficiency for oxalic acid, and this is shown in Figure 21 and Table 23.

[0125] As can be seen from Fig. 21 and Table 23, as the injection amount of persulfate increases from 0, 10, 30, 50, 100, to 150 mM, the removal rates are 3.9, 3.7, 6.9, 97.7, 97.9, and 99.2%, respectively. After 3 minutes of reaction time, 4.1, 4.5, 40.5, 97.7, 97.7, and 99.2% of oxalic acid are removed under the conditions of persulfate injection amounts of 0, 10, 30, 50, 100, and 150 mM, respectively. It was found that most of the oxalic acid was removed very quickly.

[0126]

Table 23

[0127] Experimental Example 4 - Comparison of the effects of barium hydroxide and sodium hydroxide on 10 mM oxalic acid To understand the difference between the pH adjustment effects of Ba(OH)₂ and NaOH, the values in Table 19 were subtracted from the values in Table 18, and the waste liquid decomposition effects by the pH adjustment methods are shown in Fig. 22 and Table 24.

[0128] As can be seen from the following Fig. 22 and Table 24, the difference between the two conditions shows a large difference under the injection conditions of 0 - 30 mM persulfate at 66.6, 92.6, 91.5, 0.8, 0.7, and -0.7% as the injection amount of persulfate increases from 0, 10, 30, 50, 100, to 150 mM. After 3 minutes of reaction time, a large difference is observed under the injection conditions of 0 - 30 mM persulfate at 64.2, 92.2, 58.1, 1.0, 0.6, and -0.9% under the conditions of persulfate injection amounts of 0, 10, 30, 50, 100, and 150 mM.

[0129]

Table 24

[0130] Example 11 - Adjusting the pH with Ba(OH)₂ for 10 mM oxalic acid (copper) In the decontamination process of nuclear power plants, copper, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and a complexing agent. The concentration of oxalic acid used in this experiment was adjusted to 10 mM according to the concentration present in the decontamination waste liquid. Alkali was injected with Ba(OH)2 and adjusted to pH 12. Then, copper was prepared to 0.625 M using copper sulfate and then injected to a concentration of 10 mM, which is the concentration present in the decontamination waste liquid. Then, it was injected to 0, 10, 30, 50, 100, 150 mM to confirm the effect of oxalic acid treatment over time. At pH 12, the effect of oxalic acid treatment with copper, alkali, and persulfate was confirmed by measuring TOC, and the effect of completely removing organic carbon was confirmed. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency (%) of oxalic acid were calculated and shown in Fig. 23 and Table 25. As confirmed in Fig. 23 and Table 25, as the injection amount of persulfate increased from 0, 10, 30, 50, 100, 150 mM, it was removed at 61.1, 87.6, 98.6, 98.5, 98.3, 98.0%. After 3 minutes of reaction time, 63.0, 97.6, 98.1, 98.4, 98.6, 98.2% of oxalic acid was removed under the conditions of 0, 10, 30, 50, 100, 150 mM injection amount of persulfate, and it was found that most of the oxalic acid was removed very quickly.

[0131]

Table 25

[0132] Example 12 - Adjusting the pH with NaOH for 10 mM Oxalic Acid (Copper) Perform in the same manner as in Example 11 above, but use sodium hydroxide instead of barium hydroxide to analyze the treatment efficiency for oxalic acid, and show this in Fig. 24 and Table 26. As can be seen from FIG. 24 and Table 26, as the injection amount of persulfate increases to 0, 10, 30, 50, 100, 150 mM, it is removed at 0.3, 93.3, 97.3, 97.2, 96.8, 98.3%. After 3 minutes of reaction time, oxalic acid is removed at -1.8, 92.4, 96.9, 97.0, 96.2, 95.6% under the conditions of injection amounts of persulfate of 0, 10, 30, 50, 100, 150 mM, and it was found that most of the oxalic acid was removed very quickly.

[0133]

Table 26

[0134] Experimental Example 5 - Comparison of the effects of barium hydroxide and sodium hydroxide on 10 mM oxalic acid To know the difference between the Ba(OH)2 pH adjustment effect and the NaOH pH adjustment effect, the values in Table 22 were subtracted from the values in Table 21, and the waste liquid decomposition effect by the pH adjustment method is shown in FIG. 25 and Table 27.

[0135] As can be seen from FIG. 25 and Table 27 below, the difference between the two conditions is 60.8, -5.7, 1.4, 1.3, 1.5, -0.3% as the injection amount of persulfate increases to 0, 10, 30, 50, 100, 150 mM. When the persulfate is 0 mM, a very large difference is observed, and the Ba(OH)2 pH adjustment effect is higher. After 3 minutes of reaction time, it is 64.8, 5.2, 1.3, 1.4, 2.3, 2.3% under the conditions of injection amounts of persulfate of 0, 10, 30, 50, 100, 150 mM. When the persulfate is 0 mM, a very large difference is observed.

[0136]

Table 27

[0137] Example 13 - Adjusting the pH with Ba(OH)2 for 20 mM oxalic acid (nickel) In the decontamination process of a nuclear power plant, nickel, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and a complexing agent. The concentration of oxalic acid used in this experiment was adjusted to 20 mM according to the concentration present in the decontamination waste liquid. As the alkali, Ba(OH)2 was injected to adjust the pH to 12. Then, nickel was prepared to 0.625 M using nickel sulfate and then injected to a concentration of 20 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 0, 20, 60, 100, 200, and 300 mM to confirm the effect of oxalic acid treatment over time. At pH 12, the effect of oxalic acid treatment by nickel, alkali, and persulfate was confirmed by measuring TOC, and the effect of completely removing organic carbon was verified. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency (%) of oxalic acid were calculated and shown in Figure 26 and Table 28. As confirmed in Figure 26 and Table 28, as the injection amount of persulfate increased from 0, 20, 60, 100, 200, to 300 mM, it was removed at 81.8, 91.0, 98.3, 98.7, 98.8, and 98.8%. After 5 minutes of reaction time, 84.7, 91.4, 98.8, 98.6, 98.7, and 98.7% of oxalic acid was removed under the conditions of persulfate injection amounts of 0, 20, 60, 100, 200, and 300 mM, and it was found that most of the oxalic acid was removed very quickly.

[0138]

Table 28

[0139] Example 14 - Adjusting the pH with NaOH for 20 mM Oxalic Acid (Nickel) The same procedure as in Example 13 was carried out, but sodium hydroxide was used instead of barium hydroxide to analyze the treatment efficiency for oxalic acid, and this is shown in Figure 27 and Table 29. As can be seen from Fig. 27 and Table 29, as the injection amount of persulfate increases from 0, 20, 60, 100, 200 to 300 mM, the removal rates are -2.4, 88.4, 98.5, 98.8, 98.7, 98.8%, respectively. After 5 minutes of reaction time, 1.7, 82.3, 98.4, 98.7, 98.7, 98.7% of oxalic acid is removed under the conditions of injection amounts of persulfate of 0, 20, 60, 100, 200, 300 mM, indicating that most of the oxalic acid is removed very quickly.

[0140]

Table 29

[0141] Experimental Example 6 - Comparison of the effects of barium hydroxide and sodium hydroxide on 20 mM oxalic acid To understand the difference between the pH adjustment effects of Ba(OH)₂ and NaOH, the values in Table 25 were subtracted from the values in Table 24, and the waste liquid decomposition effects by the pH adjustment methods are shown in Fig. 28 and Table 30.

[0142] As can be seen from Fig. 28 and Table 30 below, the difference between the two conditions is that as the injection amount of persulfate increases from 0, 20, 60, 100, 200 to 300 mM, the differences are 84.2, 2.6, -0.2, -0.1, 0.1, 0.0% respectively. Under the injection condition of 0 mM persulfate, a large difference was observed. After 5 minutes of reaction time, under the conditions of injection amounts of persulfate of 0, 20, 60, 100, 200, 300 mM, the differences are 83.0, 9.1, 0.4, -0.1, 0.0, 0.0% respectively. Under the injection condition of 0 mM persulfate, a large difference was observed.

[0143]

Table 30

[0144] Example 15 - pH adjustment with Ba(OH)₂ for 20 mM oxalic acid (copper) In the decontamination process of nuclear power plants, copper, alkali, and persulfate were injected to treat oxalic acid used as an organic acid and a complexing agent. The concentration of oxalic acid used in this experiment was adjusted to 20 mM according to the concentration present in the decontamination waste liquid. Alkali was injected with Ba(OH)₂ and adjusted to pH 12. Then, copper was prepared to 0.625 M using copper sulfate and then injected to a concentration of 20 mM, which is the concentration present in the decontamination waste liquid. Then, persulfate was injected to concentrations of 0, 20, 60, 100, 200, and 300 mM, and the effect of oxalic acid treatment over time was confirmed. At pH 12, the effect of oxalic acid treatment with copper, alkali, and persulfate was confirmed by measuring TOC, and the effect of complete removal of organic carbon was verified. Also, after treatment, the TOC concentration of the remaining oxalic acid was subtracted, and the concentration and treatment efficiency (%) of oxalic acid were calculated and shown in Figure 29 and Table 31. As confirmed in Figure 29 and Table 31, as the injection amount of persulfate increased to 0, 20, 60, 100, 200, and 300 mM, it was removed at 81.3, 81.1, 98.9, 99.0, 99.1, and 99.0%. After 5 minutes of reaction time, under the conditions of injection amounts of persulfate of 0, 20, 60, 100, 200, and 300 mM, 83.7, 90.7, 99.0, 99.1, 98.9, and 98.9% of oxalic acid was removed, and it was found that most of the oxalic acid was removed very quickly.

[0145]

Table 31

[0146] Example 16 - Adjusting pH with NaOH for 20 mM Oxalic Acid (Copper) Using sodium hydroxide instead of barium hydroxide, the treatment efficiency for oxalic acid was analyzed and shown in Figure 30 and Table 32.

[0147] As can be seen from FIG. 30 and Table 32, as the injection amount of persulfate increases at 0, 20, 60, 100, 200, 300 mM, it is removed at -1.1, 87.0, 98.6, 98.5, 98.6, 98.6%. After 5 minutes of reaction time, under the conditions of injection amounts of persulfate of 0, 20, 60, 100, 200, 300 mM, 1.2, 91.3, 98.4, 98.5, 98.6, 98.7% of oxalic acid was removed, and it was found that most of the oxalic acid was removed very quickly.

[0148]

Table 32

[0149] Experimental Example 7 - Comparison of the effects of barium hydroxide and sodium hydroxide on 20 mM oxalic acid To know the difference between the Ba(OH)₂ pH adjustment effect and the NaOH pH adjustment effect, the values in Table 28 were subtracted from the values in Table 27, and the waste liquid decomposition effect by the pH adjustment method is shown in Table 33 and FIG. 31.

[0150] As can be seen from Table 33 and FIG. 31 below, the difference between the two conditions is 82.4, -6.0, 0.3, 0.5, 0.5, 0.4% as the injection amount of persulfate increases at 0, 20, 60, 100, 200, 300 Mm. When the persulfate is 0 mM, a very large difference is observed, and the Ba(OH)₂ pH adjustment effect is higher. After 5 minutes of reaction time, under the conditions of injection amounts of persulfate of 0, 20, 60, 100, 200, 300 mM, it is 82.5, -0.6, 0.6, 0.6, 0.3, 0.2% for persulfate. When the persulfate is 0 mM, a very large difference is observed.

[0151]

Table 33

[0152] Example 17 An experiment was conducted in advance to confirm that the reaction is the oxidation of the valence of the metal oxide according to the present invention to persulfate. That is, since persulfate becomes sulfate radicals or hydroxyl radicals at alkaline pH, this is the content of the experiment to show that the present invention is the result of the oxidation of metal oxides that are not radical reactions. For this purpose, 10 mM of copper oxide and 10 mM of nickel oxide were used respectively in the liquid scintillation waste liquid prepared under the condition of pH 12, and the concentration of persulfate was 150 mM. Here, 2000 mM of TBA and 2000 mM of MeOH, which are sufficient radical scavenger concentrations, were added, and the oxalic acid decomposition performance was compared, which is shown in Table 34 and Figure 32.

[0153]

Table 34

[0154] In the operation process of the nuclear power plant, in order to treat the liquid scintillator waste liquid used in the liquid scintillation counter, nickel, alkali, and persulfate were injected, and it was mixed and diluted with the mixture of liquid scintillation substances used in this experiment (a 1:1 mixture of CarboSorb and Permafluor E+ from PerkinElmer).

[0155] The alkali was adjusted to pH 12 using 2.5 M NaOH. Then, nickel was prepared to 0.625 M using nickel sulfate and then injected to be 10 mM. Then, persulfate was injected to be 10, 30, 50, 100, 150, 200 mM, and the TOC treatment effect over time was confirmed. At pH 12, the waste liquid treatment effect by nickel, alkali, and persulfate was confirmed by measuring TOC that the organic carbon was completely removed. Also, after treatment, the remaining TOC concentration of the waste liquid was subtracted, and the waste liquid concentration and treatment efficiency (%) were calculated and shown in Figures 33, 34 and Table 35. As confirmed in FIGS. 33, 34 and Table 35, as the injection amount of persulfate increased to 10, 30, 50, 100, 150, 200 mM, after 3 minutes of reaction time, it was removed at 7.5, 24.3, 38.9, 62.8, 93.7, 97.1%, and after 120 minutes of reaction time, it was removed at 10.8, 34.6, 40.4, 72.7, 96.2, 98.4%. It was found that most of the organic substances were removed very quickly within 3 minutes of reaction time.

[0156]

Table 35

[0157] Comparative Example 8 In order to confirm the effect of injecting nickel oxide and persulfate under very high alkaline conditions at pH 12, after adjusting to pH 12 using 2.5 M NaOH, the liquid scintillator waste liquid treatment effect was confirmed for the case of injecting only nickel without persulfate and the case of injecting only persulfate without nickel. When injecting only nickel without persulfate, after preparing the waste liquid, nickel was prepared to 0.625 M using nickel sulfate and injected to be 10, 20, 30 mM. Then, the waste liquid treatment effect over time was confirmed and shown in FIGS. 35 and 36 and Table 36.

[0158] When injecting only nickel without persulfate to be 10, 20, 30 mM, the waste liquid treatment effect over time can be seen. That is, for the waste liquid treatment effect, by measuring TOC, the effect of completely removing organic carbon was confirmed. Also, after treatment, subtracting the TOC concentration of the remaining waste liquid, as confirmed in FIGS. 35 and 36, when injecting only nickel without persulfate, as the nickel injection amount increased to 10, 20, 30 mM, it was removed at 1.2, 1.1, 1.3% in 120 minutes of reaction time, and it can be seen that hardly any was removed.

[0159] Also, when only persulfate was injected without nickel, as the injection amount of persulfate increased to 10, 30, 50, 100, 150, 200 mM, as shown in FIGS. 35 and 36 and Table 37, it was removed at 1.8, 1.5, 1.2, 1.3, 1.5, 1.4% at a reaction time of 120 minutes, indicating that almost no removal occurred.

[0160]

Table 36

[0161]

Table 37

[0162] Comparative Example 9 For comparison with the examples, it was irradiated with iron, acid, and gamma rays, and mixed and diluted with a mixture of liquid scintillator substances (CarboSorb and Permafluor E+ from PerkinElmer, mixed 1:1 and used) used in this experiment. The acid was adjusted to pH 3 using 0.1 N HNO3.

[0163] Fe was added to the prepared liquid scintillator waste liquid as a metal ion 2+ to a concentration of 1 mM, N2O was injected at a rate of 0.1 MPa / 10 mL for 20 minutes, and persulfate was added as an oxidant to a concentration of 1 mM for the experiment. Gamma rays were irradiated at a dose rate of 10 kGy / hr and irradiated for 30 minutes, 60 minutes, and 180 minutes, with a gamma ray irradiation dose of 5, 10, and 30 kGy.

[0164] Specifically, the experiment was carried out in batches with only metal ions added to the liquid scintillator waste liquid, batches with oxidants and nitrous oxide added to the liquid scintillator waste liquid, and batches with metal ions, oxidants, and nitrous oxide added to the liquid scintillator waste liquid. The TOC concentration of the liquid scintillator waste liquid after radiation irradiation was subtracted from the TOC concentration before radiation irradiation, and the treatment efficiency (%) of the liquid scintillator waste liquid was calculated and shown in FIGS. 37 and Table 38.

[0165] When the gamma-ray irradiation doses were 5, 10, and 30 kGy (30, 60, and 180 minutes), the treatment efficiencies of the batches with only metal ions added were 3.7%, 6.6%, and 14.2% respectively. For the batches with an oxidizing agent and nitrous oxide added to the liquid scintillator waste liquid, the treatment efficiencies were 6%, 18.4%, and 37.1% respectively. For the batches with metal ions, an oxidizing agent, and nitrous oxide added to the liquid scintillator waste liquid, the treatment efficiencies were 22.1%, 34.6%, and 73.9% respectively.

[0166]

Table 38

[0167] Comparative Example 10 For comparison with the examples, copper, neutral, and gamma-ray irradiated, and mixed and diluted with the mixture of liquid scintillator used in this experiment (a 1:1 mixture of PerkinElmer's CarboSorb and Permafluor E+). Cu was added to the prepared liquid scintillator waste liquid as a metal ion to a concentration of 1 mM, N2O was injected at a rate of 0.1 MPa / 10 mL for 20 minutes, and persulfate was added as an oxidizing agent to a concentration of 1 mM for the experiment. The gamma-ray was irradiated at a dose rate of 10 kGy / hr for 30 minutes, 60 minutes, and 180 minutes, with gamma-ray irradiation doses of 5, 10, and 30 kGy. 2+ Specifically, the experiment was carried out in batches with only metal ions added to the liquid scintillator waste liquid, batches with an oxidizing agent and nitrous oxide added to the liquid scintillator waste liquid, and batches with metal ions, an oxidizing agent, and nitrous oxide added to the liquid scintillator waste liquid. The treatment efficiency (%) of the liquid scintillator waste liquid was calculated by subtracting the TOC concentration of the liquid scintillator waste liquid after radiation irradiation from the TOC concentration before radiation irradiation, and the results are shown in Figure 38 and Table 39.

[0168] ​When the gamma-ray irradiation dose was 5, 10, 30 kGy (30, 60, 180 minutes), in the case of the batch with only metal ions added, the treatment efficiencies were -0.5, -2.4, -1.6% respectively; in the case of the batch with an oxidizing agent and nitrous oxide added to the liquid scintillator waste liquid, the treatment efficiencies were 28.2, 35.7, 49.4% respectively; in the case of the batch with metal ions, an oxidizing agent and nitrous oxide added to the liquid scintillator waste liquid, the treatment efficiencies were 29.5, 48.4, 89.8% respectively.

[0169]

Table 39

[0170] Example 18: Wastewater treatment method by nickel metal and persulfate treatment To treat wastewater with pH 9.7, salt content 5.6%, total organic carbon (TOC) 3,882 mg / L, ammonia (NH3) 2,410 mg / L, and nitrate nitrogen 0 mg / L, nickel sulfate (NiSO4) was used as a transition metal salt, NaOH was used as a strong base to meet the basic conditions, and sodium peroxydisulfate was used as a strong oxidizing agent and they were respectively added for wastewater treatment.

[0171] First, NaOH was added to the wastewater at a concentration of 2.5 M to adjust the pH of the wastewater to 12. Here, nickel sulfate was added at a concentration of 0.4 M, and after uniformly stirring, SDS was injected to a concentration of 2 M. Then, after the treatment reaction proceeded and 1 hour had passed, the concentrations of TOC and ammonia were measured, and the treatment efficiency was calculated and shown in Table 40 below. The treatment efficiency was calculated as the percentage of the concentrations (decrease amounts) of the treated TOC and ammonia after 1 hour when the initial concentrations of TOC and ammonia were set to 100.

[0172] Example 19: Wastewater treatment method by nickel metal and persulfate treatment The procedure was the same as in Example 18, except that the concentration of nickel sulfate was changed to 0.2 M. After 1 hour from the start of the treatment reaction, the concentrations of TOC and ammonia and the treatment efficiency were measured in the same manner and are shown in Table 40 below.

[0173] Example 20: Wastewater treatment method by nickel metal and persulfate treatment The procedure was the same as in Example 18, except that the concentration of nickel sulfate was changed to 0.1 M to treat the wastewater differently. After 1 hour from the start of the treatment reaction, the concentrations of TOC and ammonia and the treatment efficiency were measured in the same manner and are shown in Table 40 below.

[0174] Example 21: Wastewater treatment method by nickel metal and persulfate treatment The procedure was the same as in Example 18, except that the concentration of nickel sulfate was changed to 2.0 M to treat the wastewater differently. After 1 hour from the start of the treatment reaction, the concentrations of TOC and ammonia and the treatment efficiency were measured in the same manner and are shown in Table 40 below.

[0175] Example 22: Wastewater treatment method by nickel metal and persulfate treatment The procedure was the same as in Example 18, except that the concentration of nickel sulfate was changed to 4.0 M to treat the wastewater differently. After 1 hour from the start of the treatment reaction, the concentrations of TOC and ammonia and the treatment efficiency were measured in the same manner and are shown in Table 40 below.

[0176] Example 23: Wastewater treatment method by nickel metal and persulfate treatment The procedure was the same as in Example 18, except that the concentration of nickel sulfate was changed to 0.01 M to treat the wastewater differently. After 1 hour from the start of the treatment reaction, the concentrations of TOC and ammonia and the treatment efficiency were measured in the same manner and are shown in Table 40 below.

[0177] Example 24: Wastewater treatment method by nickel metal and persulfate treatment The procedure was the same as in Example 18, except that the persulfate compound was added at a concentration of 5 M for treatment, and then wastewater treatment was carried out. After 1 hour had elapsed since the start of the treatment reaction, the concentrations of TOC and ammonia and the treatment efficiency were measured in the same manner and are shown in Table 40 below.

[0178] Example 25: Wastewater treatment method by nickel metal and persulfate treatment The procedure was the same as in Example 18, except that the persulfate compound was added at a concentration of 0.05 M for treatment, and then wastewater treatment was carried out. After 1 hour had elapsed since the start of the treatment reaction, the concentrations of TOC and ammonia and the treatment efficiency were measured in the same manner and are shown in Table 40 below.

[0179] Example 26: Wastewater treatment method by nickel metal and persulfate treatment The procedure was the same as in Example 18, but without adding NaOH, nickel sulfate and sodium peroxydisulfate compounds were added under the condition that the pH of the wastewater was 9.7, and the wastewater treatment reaction was advanced. After 1 hour had elapsed since the start of the treatment reaction, the concentrations of TOC and ammonia and the treatment efficiency were measured in the same manner and are shown in Table 40 below.

[0180] Comparative Example 11: Wastewater treatment method with different nickel metal and persulfate treatment conditions The procedure was the same as in Example 18, but the wastewater treatment was advanced without adding any nickel sulfate. After 1 hour had elapsed since the start of the treatment reaction, the concentrations of TOC and ammonia and the treatment efficiency were measured in the same manner and are shown in Table 40 below.

[0181] Comparative Examples 12 and 13: Wastewater treatment method by conventional microbial treatment method For the same wastewater as in Example 18, wastewater treatment was carried out using a conventional microbial treatment process. The microbial concentration was MLSS 8,020 mg / L, DO 3.2 mg / L, and the operation was carried out for 20 days of HRT. For the sample after 1 hour of operation, the concentrations of TOC and ammonia and the treatment efficiency were measured as in the examples and are shown in Table 36 below (Comparative Example 17). Also, similar numerical values were measured and calculated for the treatment results at 480 hours, which is 20 days after operation, and are shown together in Table 40 (Comparative Example 18).

[0182]

Table 40

[0183] Referring to Table 40 above, it can be seen that Example 20 with a nickel sulfate content of 0.4M shows the highest treatment efficiency. When the nickel sulfate content is more than that, especially in Example 22 exceeding 3.0M, and also in Examples and Comparative Example 6 with a low nickel sulfate content (without nickel sulfate), it can be confirmed that the treatment efficiencies of TOC and NH3 are all very low.

[0184] Differences in effects can also be confirmed depending on the persulfate content. According to Example 24 and Example 25, it was confirmed that when the persulfate content is excessive or low, the water treatment efficiency decreases rapidly. Also, the synergistic effect of using both nickel sulfate and persulfate is maximized when the pH is 12 or higher, and it was found that the treatment efficiency decreased in Example 26 without adding NaOH.

[0185] When comparing the treatment method of Example 18 with a comparative example and treating for 1 hour in the same way (Comparative Example 11), it can be seen that the treatment in Example 20 is remarkably effective, and its efficiency is at a level similar to that of Comparative Example 13, which is the result after 480 hours of operation. Therefore, it was confirmed that the water treatment method according to the present invention can quickly and highly efficiently treat high-salt wastewater containing nitrogen and / or phosphorus.

Claims

1. A wastewater treatment method for wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus, in which transition metal ions and peroxide are added under alkaline conditions.

2. The wastewater treatment method according to claim 1, wherein the wastewater is radioactive wastewater or livestock wastewater generated in a nuclear facility.

3. The wastewater treatment method according to claim 1, further comprising a step of adding transition metal ions.

4. The wastewater treatment method according to claim 1, wherein barium hydroxide or sodium hydroxide is added and the treatment is carried out under alkaline conditions with a pH of 9 or higher.

5. The wastewater treatment method according to claim 1, wherein 90% or more of the refractory organic substances are removed within 10 minutes after the addition of the peroxide.

6. The transition metal ions are at least any one selected from the group consisting of scandium ions, titanium ions, vanadium ions, chromium ions, manganese ions, cobalt ions, cerium ions, copper ions, nickel ions, zinc ions, yttrium ions, zirconium ions, niobium ions, molybdenum ions, technetium ions, ruthenium ions, rhodium ions, palladium ions, silver ions, cadmium ions, hafnium ions, tantalum ions, tungsten ions, rhenium ions, osmium ions, iridium ions, platinum ions, gold ions, and mercury ions. The wastewater treatment method according to claim 1.

7. The wastewater treatment method according to claim 1, wherein the peroxide is either persulfate or peroxide.

8. The transition metal ions are converted into transition metal oxides, The peroxide is adsorbed on the surface of the transition metal oxide, increasing the oxidation state of the transition metal oxide to oxidize and remove refractory organic substances. The wastewater treatment method according to claim 1.

9. A storage unit for storing wastewater containing any one or more of refractory organic substances, nitrogen, and phosphorus, A reaction unit communicating with the storage unit, in which any one of the refractory organic substances, nitrogen, and phosphorus is decomposed, and A wastewater treatment apparatus including an input unit communicating with the reaction unit and for inputting a transition metal and a peroxide to react with and decompose any one of the refractory organic substances, nitrogen, and phosphorus.

10. The wastewater treatment device according to claim 9, characterized in that it removes 90% or more of the refractory organic substances contained in the radioactive waste liquid used in nuclear-related facilities within 10 minutes.

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