Hydrazine-containing waste water treatment method, and hydrazine-containing waste water treatment facility

Abstract

An embodiment of the present invention provides a hydrazine-containing waste water treatment method in which hydrazine-containing waste water containing hydrazine and metal ions that are more easily reducible than water is irradiated with light in the presence of a photocatalyst to cause an oxidation reaction of the hydrazine and a reduction reaction of the metal ions. In addition, an embodiment of the present invention provides a hydrazine-containing waste water treatment facility comprising: a reaction tank which can accommodate hydrazine-containing waste water containing hydrazine and metal ions that are more easily reducible than water; and a photocatalyst provided in the reaction tank, wherein the hydrazine-containing waste water treatment facility is capable of irradiating the hydrazine-containing waste water with light in the presence of the photocatalyst to cause an oxidation reaction of the hydrazine and a reduction reaction of the metal ions.

Description

Hydrazine-containing wastewater treatment method and hydrazine-containing wastewater treatment equipment

[0001] The present invention relates to a method for treating hydrazine-containing wastewater and a facility for treating hydrazine-containing wastewater.

[0002] Methods for treating hydrazine-containing wastewater have been known for some time. As examples of such treatment methods, Patent Documents 1 and 2 disclose a method in which hydrazine in hydrazine-containing wastewater is oxidatively decomposed by reacting it with oxygen in the presence of copper (II) sulfate or metallic copper according to the following reaction formula (reaction formula: N ２ H ４ +O ２ →N ２ +2H ２ O).

[0003] JP-A No. 57-27193 JP-A No. 9-174066

[0004] However, the above-mentioned conventional treatment methods have room for technical improvement in the following respects. Specifically, in the conventional treatment methods, hydrazine is oxidatively decomposed by continuously adding a metal or metal salt, but the metal or metal salt must be diluted before being discharged. Furthermore, since an oxygen source is required for the oxidative decomposition of hydrazine, aeration is necessary to promote the reaction. Implementing such aeration increases the overall size of the equipment and makes it difficult to simplify the equipment configuration.

[0005] Furthermore, when wastewater contains metal ions in addition to hydrazine, it is desirable to not only oxidize and decompose hydrazine but also remove the metal ions to effectively utilize metal resources.

[0006] In view of the above, an object of the present invention is to provide a method for treating hydrazine-containing wastewater and a hydrazine-containing wastewater treatment facility that can efficiently perform oxidative decomposition of hydrazine and removal of contained metal ions with a simple configuration when the wastewater contains metal ions in addition to hydrazine.

[0007] In order to achieve the above object, one embodiment of the present invention provides a method for treating hydrazine-containing wastewater, which comprises irradiating hydrazine-containing wastewater containing hydrazine and metal ions that are more easily reduced than water with light in the presence of a photocatalyst, thereby causing an oxidation reaction of the hydrazine and a reduction reaction of the metal ions.

[0008] In order to achieve the above object, one embodiment of the present invention provides a hydrazine-containing wastewater treatment facility, which includes a reaction tank capable of accommodating hydrazine-containing wastewater containing hydrazine and metal ions that are more easily reduced than water, and a photocatalyst disposed in the reaction tank, and which is capable of irradiating the reaction tank with light in the presence of the photocatalyst to carry out an oxidation reaction of the hydrazine and a reduction reaction of the metal ions.

[0009] According to one embodiment of the present invention, when wastewater contains metal ions in addition to hydrazine, it is possible to efficiently perform the oxidative decomposition of hydrazine and the removal of contained metal ions by irradiating light in the presence of a photocatalyst using a simple facility equipped with a photocatalyst.

[0010] Fig. 1 is a perspective view schematically showing an example of a hydrazine-containing wastewater treatment facility according to one embodiment of the present invention. Fig. 2 is a diagram schematically showing an example of a hydrazine-containing wastewater treatment facility according to one embodiment of the present invention. Fig. 3 is a flowchart showing an example of a hydrazine-containing wastewater treatment method according to one embodiment of the present invention. Fig. 4 is a graph showing the behavior of hydrazine, contained metal (Ni) ions, and generated hydrogen contained in wastewater by a hydrazine-containing wastewater treatment method according to one embodiment of the present invention.

[0011] Hereinafter, a hydrazine-containing wastewater treatment facility and a hydrazine-containing wastewater treatment method according to one embodiment of the present invention will be described.

[0012] [Hydrazine-containing wastewater treatment facility] Fig. 1 is a perspective view showing a typical example of a hydrazine-containing wastewater treatment facility according to one embodiment of the present invention. Fig. 2 is a diagram showing a typical example of a hydrazine-containing wastewater treatment facility according to one embodiment of the present invention. Fig. 2 is a diagram showing a specific configuration of Fig. 1.

[0013] As shown in Figure 1, a hydrazine-containing wastewater treatment system 100 according to one embodiment of the present invention includes a reaction tank 20 capable of accommodating wastewater 10 containing hydrazine, metal ions, and water, and a photocatalyst 30 disposed in the reaction tank 20. In this specification, it is assumed that the wastewater before the specific treatment described below contains hydrazine, and such wastewater is referred to as hydrazine-containing wastewater. In the present invention, light L can be irradiated from outside onto the photocatalyst 30 in the reaction tank 20.

[0014] The "metal ions" referred to here refer to ions that are originally contained in the wastewater 10 and are more easily reduced than the water contained in the wastewater 10. The "metal ions" referred to here also refer to ions that are originally contained in the wastewater 10 and have a standard electrode potential that is equal to or more noble than the standard electrode potential of hydrogen. As the metal ions, at least one can be selected from the group consisting of nickel ions, iron ions, cobalt ions, copper ions, tin ions, and lead ions. In the following, nickel ions (Ni ２＋ ) will be explained as an example.

[0015] As shown in Fig. 2, the reaction tank 20 is a tank that contains at least hydrazine-containing wastewater 10 and photocatalyst 30, and is provided with a supply port 21 on one side and a discharge port 22 on the other side. The hydrazine-containing wastewater 10 is supplied into the reaction tank 20 through the supply port 21 from a supply path for the hydrazine-containing wastewater 10. After the oxidative decomposition of hydrazine by the photocatalyst 30, the treated wastewater 10 is discharged through the discharge port 22 to a wastewater discharge path. The hydrazine-containing wastewater 10 in the reaction tank 20 may be treated batchwise or continuously.

[0016] The light L to be irradiated onto the photocatalyst 30 can be sunlight, ultraviolet light, or the like. A combination of both can also be used. When sunlight is used, hydrazine can be oxidized and decomposed with less energy than when an ultraviolet light source is used.

[0017] On the other hand, when ultraviolet light from an ultraviolet light source is used, the ultraviolet light is absorbed by the photocatalyst, and the catalytic action of the photocatalyst is exerted, thereby enabling effective oxidative decomposition of hydrazine. The type of ultraviolet light source is not particularly limited, but examples thereof include LEDs (light-emitting diodes) and ultraviolet lamps (e.g., mercury lamps and metal halide lamps).

[0018] The type of photocatalyst 30 is not particularly limited, but it is preferable that the photocatalyst 30 be alkali-resistant, since hydrazine-containing wastewater may be alkaline due to the hydrazine.

[0019] The pH of the hydrazine-containing wastewater 10 is not particularly limited, but may be, for example, 12 or more and 14 or less. Here, the "pH of the hydrazine-containing wastewater" refers to the pH of the hydrazine-containing wastewater 10 at a stage before the oxidative decomposition of hydrazine by the photocatalyst 30.

[0020] In view of this, it is preferable that the photocatalyst 30 contains strontium titanate. This allows the photocatalyst to stably exhibit catalytic activity in hydrazine-containing wastewater, thereby stably decomposing hydrazine. Other examples of the photocatalyst that can be used include titanium oxide.

[0021] The photocatalyst (e.g., strontium titanate) is preferably doped with an impurity element, which can improve the activity of the photocatalyst. Examples of the impurity element include aluminum and rhodium. The photocatalyst (e.g., strontium titanate doped with an impurity element) can be produced by, for example, a solid-phase method or a flux method.

[0022] As described above, in the present invention, light L can be irradiated from the outside onto the photocatalyst 30 in the reaction tank 20. When the photocatalyst 30 is irradiated with light, the following oxidation-reduction reaction occurs with respect to the components contained in the wastewater 10.

[0023] Specifically, oxidation reaction: N ２ H ４ →N ２ +4H＋ +4e － Reduction reaction: 4H ２ O+4e － →2H ２ +4OH － / 2M ｎ＋ +4e － → 2M oxidation-reduction reaction takes place. Here, M represents a metal and n represents a natural number. That is, overall, N ２ H ４ → 2H ２ +N ２ and M ｎ＋ The reaction of M takes place. Note that M in the above reduction reaction formula corresponds to the aforementioned metal element contained in the wastewater 10.

[0024] As described above, according to the present invention, with a simple structure of the reaction vessel 20 provided with the photocatalyst 30, the oxidation reaction of hydrazine and the reduction reaction of the metal ions can be carried out by irradiating the light L in the presence of the photocatalyst 30. As a result, the oxidative decomposition of hydrazine and the reduction of the contained metal ions (M ｎ＋ ) and extracting the contained metal M can be efficiently carried out.

[0025] Thus, unlike conventional methods, hydrazine is oxidatively decomposed by the photocatalyst 30 without the continuous addition of a metal or metal salt (such as copper (II) sulfate or metallic copper), eliminating the need for subsequent dilution of the metal or metal salt (such as copper (II) sulfate or metallic copper). Furthermore, unlike conventional methods, hydrazine can be oxidatively decomposed without reacting it with an oxygen source, eliminating the need for aeration. From the perspective of accelerating the decomposition reaction of hydrazine, the hydrazine may be oxidatively decomposed by the photocatalyst 30 while bubbling or stirring the hydrazine-containing wastewater 10.

[0026] Furthermore, as described above, in the present invention, metal ions originally contained in the wastewater 10 are easier to reduce than water. In other words, the water contained in the wastewater 10 is more difficult to reduce than metals. Focusing on the reduction reaction itself, although the reduction reaction may occur later than the metal ions originally contained in the wastewater 10, the water contained in the wastewater 10 itself can also be reduced to produce hydrogen, as shown in the above formula.

[0027] From the above, according to the present invention, it is possible to extract hydrogen in addition to oxidatively decomposing hydrazine and extracting the contained metal M. As described above, the oxidative decomposition of hydrazine produces nitrogen in addition to hydrogen, and at least a portion of this nitrogen can be further oxidized by the photocatalyst 30 to produce, for example, nitric acid, nitrous acid, etc.

[0028] In contrast, conventionally, hydrazine was reacted with an oxygen source to oxidize and decompose the hydrazine (N ２ H ４ +O ２ →N ２ +2H ２ O), the H in hydrazine reacts with O to form water. Therefore, the generation of water by oxidation of hydrogen 2H ２ +O ２ →2H ２ O (Δ ｒ In principle, the energy of the hydrogen (G°=-474.28 kJ / mol) cannot be utilized in the conventional embodiment. On the other hand, as described above, the present invention allows hydrogen to be extracted, and therefore this energy can be utilized advantageously.

[0029] The components of the hydrazine-containing wastewater treatment facility 100 will be specifically described below.

[0030] The reaction tank 20 preferably has a photocatalyst immobilizing layer 23 for immobilizing the photocatalyst 30. This allows the photocatalyst 30 to efficiently oxidatively decompose the hydrazine in the hydrazine-containing wastewater 10, and also allows the hydrazine-containing wastewater 10 and the photocatalyst 30 to be easily separated after the decomposition treatment.

[0031] The photocatalyst fixing layer 23 is formed from a plate material capable of fixing the photocatalyst 30, and has a surface on which the powdery photocatalyst 30 is fixed. The photocatalyst fixing layer 23 is provided, for example, on the bottom surface of the reaction vessel 20.

[0032] The material of the photocatalyst fixing layer 23 is not particularly limited, but is preferably one that can support the photocatalyst 30 and is resistant to hydrazine, and specific examples include plastic sheets such as polyethylene terephthalate (PET) films and polyimide sheets. For example, the photocatalyst 30 can be fixed onto the photocatalyst fixing layer 23 by arranging (spreading) powdered photocatalyst 30 on the photocatalyst fixing layer 23 and baking it under pressure.

[0033] It is also possible to oxidatively decompose hydrazine using the photocatalyst 30 in a state where the powdered photocatalyst 30 is suspended in the hydrazine-containing wastewater 10 without using the photocatalyst fixing layer 23. In this case, however, it is preferable to recover the photocatalyst 30 after the oxidative decomposition of hydrazine.

[0034] Furthermore, the reaction vessel 20 preferably has a light-transmitting window material 24. This allows light to be irradiated onto the photocatalyst 30 through the window material 24 while maintaining the inside of the reaction vessel 20 as a closed system. Therefore, hydrogen gas, which is a product of the decomposition reaction of hydrazine, can be efficiently collected.

[0035] The location where the window material 24 is installed is not particularly limited, and for example, it may be installed on the top surface of the reaction vessel 20 as shown in FIG. 2, or on the side or bottom surface of the reaction vessel 20.

[0036] The window material 24 is formed from a plate material that transmits light (preferably ultraviolet light). The material of the window material 24 is not particularly limited, but is preferably a material that transmits ultraviolet light and is resistant to hydrazine and hydrogen.

[0037] The material of the reaction vessel 20 excluding the window material 24 is not particularly limited, but is preferably resistant to hydrazine and hydrogen.

[0038] The window material 24 may be irradiated with sunlight, or as shown in Fig. 2, the hydrazine-containing wastewater treatment equipment 100 may further include an ultraviolet light source 31 that irradiates ultraviolet light onto the window material 24. In either case, the ultraviolet light can be irradiated onto the photocatalyst 30 through the window material 24. Note that the window material 24 may be irradiated with both sunlight and ultraviolet light from the ultraviolet light source 31.

[0039] From the viewpoint of efficient recovery of hydrogen gas, as shown in FIG. 2, it is preferable that the reaction tank 20 has a hydrogen recovery layer 25 that recovers hydrogen generated by the oxidative decomposition of hydrazine by the photocatalyst 30, and it is preferable that the hydrazine-containing wastewater treatment equipment 1 further includes a hydrogen storage equipment 32 that stores the generated hydrogen.

[0040] The hydrogen recovery layer 25 is a layered space provided above the hydrazine-containing wastewater 10, and is surrounded by the hydrazine-containing wastewater 10 and the upper part of the reaction tank 20. In addition, a hydrogen recovery port 26 connected to the hydrogen recovery layer 25 is provided in the upper part of the reaction tank 20.

[0041] The hydrogen storage facility 32 includes a cylinder, a hydrogen adsorption tower, etc., and is connected to the hydrogen recovery port 26 via a pressurizing pump 33. When the pressurizing pump 33 is operated, the hydrogen gas generated from the hydrazine-containing wastewater 10 and stored in the hydrogen recovery layer 25 is discharged from the hydrogen recovery port 26 and stored in the cylinder or hydrogen adsorption tower of the hydrogen storage facility 32.

[0042] The hydrazine-containing wastewater treatment facility 1 may include a gas separation membrane (not shown) that separates hydrogen and nitrogen from each other between the hydrogen recovery port 26 and the hydrogen storage facility 32. This allows for the recovery of hydrogen gas with higher purity.

[0043] [Method for treating hydrazine-containing wastewater] Hereinafter, a method for treating hydrazine-containing wastewater according to one embodiment of the present invention will be described using the hydrazine-containing wastewater treatment facility 100 having the above-described configuration. Figure 3 is a flowchart showing an example of the method for treating hydrazine-containing wastewater according to one embodiment of the present invention. In order to avoid duplication, the following description of overlapping content will be omitted or omitted.

[0044] A method for treating hydrazine-containing wastewater according to one embodiment of the present invention is characterized in that the hydrazine-containing wastewater 10 is irradiated with light L in the presence of a photocatalyst 30 to cause an oxidation reaction of hydrazine and a reduction reaction of metal ions. As described above, the hydrazine-containing wastewater 10 contains hydrazine and metal ions that are more easily reduced than water.

[0045] In the treatment method of the present invention, light L is irradiated from outside onto the photocatalyst 30 in the reaction tank 20. The light irradiation of the photocatalyst 30 causes the aforementioned oxidation-reduction reaction of the components contained in the hydrazine-containing wastewater 10. As a result of this oxidation-reduction reaction, hydrazine is decomposed into hydrogen and nitrogen, and metal ions are reduced to metals.

[0046] As described above, according to the treatment method of the present invention, the oxidation reaction of hydrazine and the reduction reaction of metal ions can be carried out by irradiating light L in the presence of the photocatalyst 30. As a result, the oxidative decomposition of hydrazine and the reduction of the contained metal ions (M ｎ＋ ) and extracting the contained metal M can be efficiently carried out.

[0047] Furthermore, the water contained in the wastewater 10 itself can be reduced to produce hydrogen, as shown in the above formula. From the above, in addition to the oxidative decomposition of hydrazine and the extraction of the contained metal M, it is also possible to preferably extract hydrogen. Furthermore, from the viewpoint of efficiently recovering hydrogen gas, an inert gas (e.g., argon gas) may be supplied into the reaction vessel 20 to purge it.

[0048] As an example, as shown in the flowchart of FIG. 3, wastewater 10 containing hydrazine and the above-mentioned metal ions discharged from various processes is passed through a hydrazine-containing wastewater treatment facility 100, where the hydrazine is oxidized and decomposed and the metal ions are removed by a photocatalyst 30.

[0049] Thereafter, the wastewater from which the hydrazine has been oxidatively decomposed and the metal ions have been removed can be discharged, for example, into a river without dilution as described above. Alternatively, the treated wastewater can be subjected to biological treatment before being discharged into a river. The hydrazine-containing wastewater 10 to be photocatalytically treated does not need to be diluted as described above, so it can be subjected to biological treatment as is. Biological treatment is not particularly limited as long as it treats wastewater using microorganisms, and examples include the activated sludge method.

[0050] In addition, hydrogen produced through the hydrazine-containing wastewater treatment facility 100 can be recovered. The recovered hydrogen can be used as an energy source, for example, to supply heat or electricity. In this case, since the produced gas contains nitrogen and the like in addition to hydrogen as described above, it is preferable to use a gas separation device having a gas separation membrane for separating hydrogen and to carry out a gas separation process using the same device. This makes it possible to recover hydrogen gas with higher purity.

[0051] The present invention is not limited to the following configurations, and can be appropriately modified and applied within the scope of the present invention. Note that the present invention also includes a combination of two or more of the individual desirable configurations described below.

[0052] Examples will be described below, but the present invention is not limited to the following examples.

[0053] As shown in Fig. 1, wastewater 10 containing hydrazine, nickel ions, and water (also referred to as hydrazine-containing wastewater 10) was introduced into a reaction vessel 20 in which a photocatalyst 30 was immobilized. After that, ultraviolet light from a mercury-xenon lamp was irradiated onto the hydrazine-containing wastewater 10 from above the reaction vessel 20 for 8 hours.

[0054] The various components of the equipment 100 and the hydrazine-containing wastewater 10 used were as follows: Photocatalyst 30: aluminum-doped strontium titanate Reaction tank 20: rectangular parallelepiped with a base length of 2 cm, width of 2 cm, and height of 10 cm Material: acrylic Hydrazine-containing wastewater 10: hydrazine concentration of approximately 6000 μmol / L, nickel (ion) concentration of approximately 5 μmol / L

[0055] During light irradiation, argon gas was introduced into the upper space of the reaction vessel 20 as a carrier gas for collecting the generated gas, and the generated gas was collected using an aluminum gas collection bag connected to the upper part of the reaction vessel 20 via a tube.

[0056] The components of the treated wastewater were analyzed using the following equipment: Hydrazine: UV-visible spectrophotometer (U-4100 manufactured by Hitachi High-Tech Science Corporation) Nickel: ICP-AES (ICPE-9800 manufactured by Shimadzu Corporation) Furthermore, a gas chromatograph (Agilent 7890A manufactured by Agilent Technologies) was used to analyze the collected evolved gas (hydrogen).

[0057] The analysis results are shown in FIG.

[0058] As shown in Figure 4, nickel ions were successfully removed 8 hours after the start of light irradiation (the line marked with ■ in the graph). This indicates that nickel ions in the wastewater 10 are reduced by light irradiation using the photocatalyst 30, and the nickel ions are removed, and nickel is also obtained by the reduction reaction.

[0059] Furthermore, after 8 hours had passed since the start of light irradiation, the molar concentration of hydrazine was reduced to about one-sixth of the initial value. This indicates that hydrazine in the wastewater 10 can be oxidized and decomposed by light irradiation using the photocatalyst 30.

[0060] Furthermore, it was found that hydrogen could be produced at a molar concentration of over 200 mol / L after 8 hours had passed since the start of light irradiation. This indicates that light irradiation using the photocatalyst 30 reduces the water in the wastewater 10, enabling hydrogen to be produced.

[0061] Furthermore, as can be seen from the gradient of the graph, up until 4 hours after the start of light irradiation, it was found that the removal of nickel ions by reduction of nickel ions was more active / preferential than the generation of hydrogen by reduction of water. From 4 to 8 hours after the start of light irradiation, it was found that the generation of hydrogen by reduction of water was more active / preferential than the removal of nickel ions by reduction of nickel ions. This is believed to be due to the fact that nickel ions have the property of being easier to reduce than water.

[0062] The present invention may take the following forms. <1> A method for treating hydrazine-containing wastewater, the method comprising irradiating hydrazine-containing wastewater containing metal ions that are more easily reduced than hydrazine and water with light in the presence of a photocatalyst to cause an oxidation reaction of the hydrazine and a reduction reaction of the metal ions. <2> The method according to <1>, wherein the metal ions are at least one selected from the group consisting of nickel ions, iron ions, cobalt ions, copper ions, tin ions, and lead ions. <3> The method according to <1> or <2>, wherein the standard electrode potential of the metal ions is equal to or more noble than the standard electrode potential of hydrogen. <4> The method according to any one of <1> to <3>, wherein a reduction reaction of water contained in the hydrazine-containing wastewater is carried out. <5> The method according to <4>, wherein hydrogen is obtained by the reduction reaction of water. <6> The method according to any one of <1> to <5>, wherein the photocatalyst contains at least one of strontium titanate and titanium oxide. <7> A hydrazine-containing wastewater treatment facility comprising: a reaction tank capable of accommodating hydrazine-containing wastewater containing hydrazine and metal ions more easily reduced than water; and a photocatalyst disposed in the reaction tank, wherein light is applied in the presence of the photocatalyst to carry out an oxidation reaction of the hydrazine and a reduction reaction of the metal ions. <8> The hydrazine-containing wastewater treatment facility according to <7>, wherein the metal ions are at least one selected from the group consisting of nickel ions, iron ions, cobalt ions, copper ions, tin ions, and lead ions. <9> The hydrazine-containing wastewater treatment facility according to <7> or <8>, wherein the standard electrode potential of the metal ions is equal to or more noble than the standard electrode potential of hydrogen. <10> The hydrazine-containing wastewater treatment facility according to any one of <7> to <9>, wherein a reduction reaction of water contained in the hydrazine-containing wastewater is carried out. <11> The hydrazine-containing wastewater treatment facility according to <10>, wherein hydrogen is produced by the reduction reaction of water, and the hydrogen can be recovered. <12> The hydrazine-containing wastewater treatment facility according to any one of <7> to <11>, wherein the reaction tank has a photocatalyst immobilization layer capable of immobilizing the photocatalyst.

[0063] REFERENCE SIGNS LIST 100 Hydrazine-containing wastewater treatment equipment 10 Hydrazine-containing wastewater 20 Reaction tank 21 Supply port 22 Discharge port 23 Photocatalyst fixing layer 24 Window material 25 Hydrogen recovery layer 26 Hydrogen recovery port 30 Photocatalyst 31 Ultraviolet light source 32 Hydrogen storage equipment 33 Pressurizing pump

Claims

1. A method for treating hydrazine-containing wastewater, which contains hydrazine and metal ions that are more easily reduced than water, by irradiating the wastewater with light in the presence of a photocatalyst to cause an oxidation reaction of the hydrazine and a reduction reaction of the metal ions.

2. The treatment method according to claim 1, wherein the metal ions are at least one selected from the group consisting of nickel ions, iron ions, cobalt ions, copper ions, tin ions, and lead ions.

3. The treatment method according to claim 1 or 2, wherein the standard electrode potential of the metal ions is equal to or more noble than the standard electrode potential of hydrogen.

4. The treatment method according to any one of claims 1 to 3, wherein a reduction reaction of water contained in the hydrazine-containing wastewater is carried out.

5. The treatment method according to claim 4, wherein hydrogen is obtained by a reduction reaction of the water.

6. The treatment method according to any one of claims 1 to 5, wherein the photocatalyst contains at least one of strontium titanate and titanium oxide.

7. A hydrazine-containing wastewater treatment facility comprising a reaction tank capable of accommodating hydrazine-containing wastewater containing hydrazine and metal ions that are more easily reduced than water, and a photocatalyst provided in the reaction tank, wherein light is irradiated in the presence of the photocatalyst to carry out an oxidation reaction of the hydrazine and a reduction reaction of the metal ions.

8. The hydrazine-containing wastewater treatment facility according to claim 7, wherein the metal ions are at least one selected from the group consisting of nickel ions, iron ions, cobalt ions, copper ions, tin ions, and lead ions.

9. The hydrazine-containing wastewater treatment facility according to claim 7 or 8, wherein the standard electrode potential of the metal ions is equal to or more noble than the standard electrode potential of hydrogen.

10. A hydrazine-containing wastewater treatment facility according to any one of claims 7 to 9, which is capable of carrying out a reduction reaction of water contained in the hydrazine-containing wastewater.

11. The hydrazine-containing wastewater treatment facility according to claim 10, wherein hydrogen is produced by the reduction reaction of the water, and the hydrogen can be recovered.

12. A hydrazine-containing wastewater treatment facility according to any one of claims 7 to 11, wherein the reaction tank has a photocatalyst fixing layer capable of fixing the photocatalyst.

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