Adsorbent for contaminated water purification

Abstract

To provide an adsorbent for contaminated water purification that reduces the cost required to purify contaminated water containing a substance to be treated.SOLUTION: An adsorbent for contaminated water purification adsorbs a substance to be treated contained in contaminated water. The adsorbent includes: a core that is shaped according to its usage; and an adsorption layer that is composed of an adsorbate to adsorb the substance to be treated on the surface of the core, and is formed in a predetermined layer thickness according to the concentration of the substance to be treated in the contaminated water.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an adsorbent for purifying contaminated water containing radioactive substances. [Background technology]

[0002] Contaminated water generated from nuclear facilities may contain substances to be treated, such as radioactive strontium and radioactive cesium, and purification treatment is carried out to remove the substances to be treated. In the purification treatment, a method of purifying contaminated water using an adsorbent that adsorbs the substances to be treated is known. For example, Patent Document 1 describes a method of purifying the contaminated water by aggregating adsorbents formed into a predetermined particle size and passing the contaminated water through the adsorbent to adsorb the substances to be treated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-018971 A Summary of the Invention [Problem to be solved by the invention]

[0004] The adsorbents used in treating contaminated water may be made of expensive materials such as titanium and silver. When purifying a huge amount of contaminated water, the amount of adsorbent used may increase, raising the risk of costs rising.

[0005] An object of the present invention is to provide an adsorbent for purifying contaminated water, which reduces the cost of purifying contaminated water containing a substance to be treated. [Means for solving the problem]

[0006] One aspect of the present invention is an adsorbent for purifying contaminated water that adsorbs a substance to be treated contained in contaminated water, the adsorbent comprising: a core material formed into a shape according to a mode of use; and an adsorption layer formed on a surface of the core material by an adsorbent material that adsorbs the substance to be treated, the adsorption layer being formed to a predetermined layer thickness according to the concentration of the substance to be treated in the contaminated water. The concentration is 2 ppm or less, and the layer thickness is 0.1 μm or more and 500 μm or less.

[0007] According to the present invention, an adsorption layer is formed on the surface of the core material to a thickness capable of adsorbing the substance to be treated depending on the concentration of the substance to be treated, so that an adsorbent can be formed using a minimum amount of adsorption substance, thereby significantly reducing the cost of purifying polluted water.

[0008] In one aspect of the present invention, the concentration is 2 ppm or less, and the layer thickness is 0.1 μm or more and 500 μm or less.

[0009] According to the present invention, the adsorbent is formed to a predetermined film thickness required for purifying contaminated water having a predetermined concentration of the anticipated target substance, so that an adsorbent can be formed using a minimum amount of adsorbent, thereby significantly reducing the cost of purifying contaminated water.

[0010] In one aspect of the present invention, the core material is formed into particles having a predetermined particle size.

[0011] The present invention can be applied to equipment in which a particulate adsorbent is used.

[0012] In one embodiment of the present invention, the particle size is 2 mm or less.

[0013] According to the present invention, since the core material is formed to have a predetermined particle size, the substance to be treated can be efficiently adsorbed by the adsorbent while the contaminated water flows through the adsorbent.

[0014] In another aspect of the present invention, the contaminated water is filled into a container through which the contaminated water flows.

[0015] INDUSTRIAL APPLICABILITY The present invention can be applied to equipment that uses a container that contains a particulate adsorbent for purifying contaminated water to remove substances to be treated.

[0016] Furthermore, the core material according to one aspect of the present invention is formed in a membrane shape that filters contaminated water.

[0017] According to the present invention, since the core material is formed in a film shape, the adsorbent for purifying contaminated water is not scattered and is easy to handle.

[0018] In one aspect of the present invention, the adhesive layer further comprises an adsorption film formed in a film shape using the core material, and a plurality of the adsorption films are laminated.

[0019] According to the present invention, by laminating a plurality of membrane-like adsorption films, it is possible to form an adsorbent that exhibits adsorption performance for a desired period of time.

[0020] In addition, the plurality of stacked adsorption membranes according to one aspect of the present invention are attached to a flow path through which the contaminated water flows.

[0021] According to the present invention, the adsorbent can be used regardless of the direction of the flow path.

[0022] In one aspect of the present invention, a plurality of the adsorption layers are formed in a multilayer structure on the surface of the core material.

[0023] According to the present invention, an adsorbent having a peelable surface layer can be constructed.

[0024] In one aspect of the present invention, the surface layer in the multilayer is peeled off when the adsorption performance of the adsorption layer is reduced.

[0025] According to the present invention, by using the adsorption layer on the surface until its adsorption performance for the substance to be treated decreases and then peeling off the adsorption layer on the surface, it is possible to recover the adsorption performance multiple times, thereby significantly reducing the cost of water purification.

[0026] In one aspect of the present invention, the substance to be treated is at least one of a combination of cesium ions and strontium ions and the adsorbent is a silicitinate, or a combination of cesium ions and the adsorbent is a combination of zeolite or ferrocyanide, or a combination of iodide ions and the adsorbent is a combination of silver-containing zeolites, or a combination of iodate ions and / or antimony ionic compounds and the adsorbent is a combination of cerium hydroxide-based adsorbents.

[0027] According to the present invention, cesium ions and strontium ions, which are radioactive substances to be treated, can be adsorbed by an adsorption material such as silicititanate. Effect of the Invention

[0028] According to the present invention, it is possible to reduce the cost of purifying contaminated water containing a substance to be treated. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a purification facility to which an adsorbent for purifying contaminated water according to an embodiment of the present invention is applied. [Diagram 2] FIG. 1 is a diagram showing the configuration of a test device for evaluating the adsorption performance of an adsorbent. [Diagram 3] FIG. 1 is a diagram showing test results of the adsorption performance of an adsorbent. [Figure 4] FIG. 13 is a diagram showing the relationship between the concentration of contaminated water and the layer thickness required for the adsorbent, calculated based on the measurement results. [Diagram 5] FIG. 2 is a cross-sectional view showing the configuration of an adsorbent according to an embodiment. [Figure 6] FIG. 1 is a diagram showing the difference in adsorption performance between the adsorbent according to the embodiment and a conventional adsorbent. [Figure 7] FIG. 1 is a diagram showing the difference in adsorption performance between the adsorbent according to the embodiment and a conventional adsorbent. [Figure 8] FIG. 2 is a cross-sectional view showing the structure of an adsorbent formed in a film shape. [Figure 9] FIG. 1 is a diagram showing a film-like adsorbent material stacked in multiple layers. [Figure 10] FIG. 2 is a cross-sectional view showing the structure of an adsorbent in which adsorption layers are formed in layers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, the adsorbent for purifying contaminated water according to the present invention will be described with reference to the drawings.

[0031] As shown in FIG. 1, a contaminated water purification facility 1 includes, for example, a storage section 2 that stores contaminated water W, and a purification section 4 that purifies the contaminated water W flowing in from the storage section 2. The storage section 2 is a tank that stores the contaminated water W. The purification section 4 adsorbs and purifies the treatment target substances contained in the contaminated water W when the contaminated water W is circulated. The storage section 2 and the purification section 4 are connected by, for example, piping H. A pump P is provided in the middle of the piping H. The pump P pressure-pumps the contaminated water W stored in the storage section 2 to the purification section 4.

[0032] Contaminated water W flows into the storage container 5 from a nuclear facility or the like and is stored therein. A pipe H is connected to the top of the storage container 5. The upstream intake port of the pipe H is disposed slightly above and spaced from the bottom of the storage container 2. The stored contaminated water W is discharged to the purification section 4 by operating a pump P.

[0033] The purification unit 4 includes, for example, a storage container 5 (container) for temporarily storing the contaminated water W, an adsorbent 6 filled in the storage container 5, and a drain pipe H3 for discharging the treated water that has been purified by passing the adsorbent 6 through it. The storage container 5 is formed in a tank shape. An outlet H2 is provided on the upper part of the storage container 5 on the downstream side of the piping H. The contaminated water W is discharged from the outlet H2 into the storage container 5. The outlet H2 is formed, for example, in the shape of a shower head expanded in the radial direction of the storage container 5.

[0034] The inside of the storage container 5 is filled with, for example, particulate adsorbent 6 that adsorbs the substance to be treated. A drain outlet H4 of a drain pipe H3 is arranged at the bottom of the storage container 5. A filter F that prevents the adsorbent 6 from being discharged is provided at the drain outlet H4. A drain pump (not shown) is provided at the drain pipe H3. When the drain pump is operated, negative pressure is generated at the drain outlet H4, and the contaminated water W in the upper layer of the storage container 5 flows through the adsorbent 6 and moves in the direction of the drain outlet H4. While the contaminated water W flows through the adsorbent 6, the substance to be treated contained in the contaminated water W is adsorbed and purified by the adsorbent 6, and the purified water is discharged from the drain outlet H4 to the outside of the storage container 5.

[0035] Contaminated water W contains, for example, radioactive cesium ions (Cs + ) and radioactive strontium ion (Sr 2+ ) contains substances subject to treatment.

[0036] The characteristics of the adsorbent 6 will now be described.

[0037] 2, a test device 20 for evaluating the performance of an adsorbent 6 is configured to simulate a purification facility 1. The test device 20 includes, for example, a first container 21 that simulates the storage section 2, a pump Q that simulates the pump P, a second container 30 that simulates the purification section 4, and a third container 40 that contains wash water discharged from the second container 30.

[0038] A contaminated water simulant W' is stored inside the first container 21. The contaminated water simulant W' contains non-radioactive substances with the same atomic number as the substances to be treated contained in the actual contaminated water discharged from a nuclear facility or the like. In the contaminated water simulant W', the substances to be treated are adjusted to a concentration several hundred to several thousand times higher than that of the actual contaminated water. The contaminated water W used for measurement has the concentrations of the substances to be treated adjusted to, for example, 0.2 ppm, 2 ppm, or 20 ppm. The pump Q pumps the contaminated water simulant W' from the first container 21 to the second container 30. The pump Q continuously circulates the contaminated water simulant W' at a flow rate that matches, for example, the flow rate (linear velocity) in the actual purification facility 1.

[0039] The second container 30 is filled with an adsorbent 6. The adsorbent 6 is formed in a particulate form from, for example, a silicic titanate-based material. For example, five types of silicic titanate-based materials are used in the measurement. In the second container 30, the contaminated water simulation liquid W' flows in from the bottom, passes through the adsorbent 6, and becomes cleaning water and is discharged from the top. The discharged cleaning water is stored in the third container 40. The combination of the absorbing material and the substance to be treated is as follows. When the substance to be treated is cesium ions and strontium ions, the adsorbent is a silicic titanate. Alternatively, when the substance to be treated is cesium ions, the adsorbent is a combination of zeolite or ferrocyanide. Alternatively, when the substance to be treated is iodide ions, the adsorbent is a combination of silver-containing zeolite. Alternatively, when the substance to be treated is iodate ions and / or antimony ionic compounds (e.g., hexahydroxoantimonate ions), the adsorbent is a cerium hydroxide-based adsorbent. The combination of the absorbing material and the material to be treated is at least one of the combinations described above.

[0040] The purified water discharged from the second container 30 is sampled and filtered every day at regular times, for example, 0, 2, and 6 hours, and then the concentration of the substance to be treated is measured. In the second container 30, the contaminated water simulant W' is circulated until the adsorbent 6 reaches its limit of adsorption of the substance to be treated. When the concentration of the contaminated water simulant W' at the inlet of the second container 30 matches the concentration of the contaminated water simulant W' at the outlet of the second container 30, it is determined that the adsorbent 6 has reached its limit of adsorption performance, and the measurement is terminated. After the adsorbent 6 has been used until its limit of adsorption performance, it is removed from the second container 30 and dried, and the distribution of the substance to be treated in the cross section is observed.

[0041] FIG. 3 shows the observation result of the adsorbent 6 used to the limit of its adsorption performance. As shown in the figure, when the adsorbent 6 purified 20 ppm contaminated water simulant W', it adsorbed the target substance to the inside. When the adsorbent 6 purified 2 ppm contaminated water simulant W', it adsorbed the target substance at a predetermined layer thickness of the surface. When the adsorbent 6 purified 0.2 ppm contaminated water simulant W', it adsorbed the target substance at a predetermined layer thickness of the surface that was thinner than the case of 2 ppm. From the measurement result, it was found that if the concentration of the contaminated water simulant W' is 2 ppm or less, the center part deeper than the predetermined layer thickness of the surface of the adsorbent 6 does not adsorb the target substance. *Note that in the Sr distribution pattern in FIG. 3, the part that appears thin in the center of the adsorbent cross section under the 0.2 ppm and 2 ppm conditions is not Sr but interference due to Si. (In SEM-EDX analysis of Sr, the Si peak appears faint due to interference with the Si detection peak.)

[0042] FIG. 4 shows the relationship between the concentration of the contaminated water simulant W' and the layer thickness required for the adsorbent 6, calculated based on the measurement results. As shown in the figure, there is a proportional relationship between the concentration of the substance to be treated in the contaminated water simulant W' and the layer thickness for adsorbing the substance to be treated on the surface layer of the adsorbent 6. When the substance to be treated is adsorbed by the adsorbent 6 using a silicic acid-based material, the adsorption performance can be achieved if the surface layer has a predetermined layer thickness. For example, the contaminated water at the Fukushima Daiichi Nuclear Power Plant has a radioactive cesium ion concentration of about 0.01 ppm, so the adsorbent 6 can ensure the adsorption performance if it has a layer thickness of about several μm.

[0043] As shown in Fig. 5, the adsorbent 7 (adsorbent for purifying contaminated water) of the embodiment comprises a core material 8 formed in a predetermined shape, and an adsorption layer 9 formed of an adsorbent that adsorbs the substance to be treated on the surface of the core material. The adsorbent 7 can be applied to equipment that uses a particulate adsorbent, such as the purification section 4 of a purification facility 1. The core material 8 is formed in a granular shape. The core material 8 is formed in a granular shape, for example, with a particle size of 2 mm or less. By forming the core material 8 in a predetermined particle size, the substance to be treated can be efficiently adsorbed in the adsorption layer 9 when contaminated water flows through the core material.

[0044] The core material 8 may be formed not only in a granular shape, but also in other shapes according to the manner of use in devices other than the purification unit 4. The core material 8 is formed from a material that is cheaper than the adsorbent, such as sand, rock, ceramic, resin, or natural zeolite.

[0045] The adsorption layer 9 adsorbs the target substance contained in the contaminated water. The adsorption layer 9 is formed of, for example, a silicic acid-based adsorption material. The adsorption layer 9 is formed to a predetermined layer thickness according to the concentration of the target substance in the contaminated water W. In the embodiment, for example, the concentration of the target substance in the contaminated water W to be purified is set to 2 ppm or less. The layer thickness of the adsorption layer 9 is formed to be, for example, 0.1 μm or more and 500 μm or less according to the concentration of the target substance in the contaminated water W of 2 ppm.

[0046] The adsorbent 7, having the above-mentioned configuration, is filled into the storage container 5 in the purification facility 1 (see FIG. 1 ) through which the contaminated water W flows. That is, the adsorbent 7 can be applied to equipment in a usage mode in which a container containing the adsorbent formed into particles, such as the purification section 4 of the purification facility 1, is used to remove substances to be treated, instead of the adsorbent 6.

[0047] As shown in Figure 6, in the cesium adsorption performance test, it can be seen that the adsorbent 7 has the same adsorption performance for adsorbing the target substance as the adsorbent 6. In the performance test, at the beginning of the water flow, the cesium adsorption performance of the adsorbent 6 tended to be higher than that of the adsorbent 7. From the water flow base to the end of the water flow, the results showed that the adsorption performance of the adsorbent 7 and the adsorbent 6 was equivalent.

[0048] 7, in the performance test for adsorbing strontium, it is found that the adsorbent 7 has the same adsorption performance for adsorbing the target substance as the adsorbent 6. In the performance test, the results showed that the adsorption performance of the adsorbent 7 was equivalent to that of the adsorbent 6 from the beginning to the end of the water flow.

[0049] As described above, in the adsorbent 7, the adsorption layer 9 is formed on the surface of the core material 8 to a thickness that allows it to adsorb the target substance according to its concentration, thereby minimizing the amount of expensive adsorbent used and significantly reducing the cost of purifying contaminated water. According to the adsorbent 7, the adsorbent is formed to a predetermined film thickness necessary for purifying contaminated water with a predetermined concentration of the expected target substance, so an adsorbent using a minimum amount of adsorbent can be formed.

[0050] [Variation 1] As shown in Fig. 8, the adsorbent 12 may be formed in a membrane. The adsorbent 12 includes a core material 13 formed in a membrane shape for filtering contaminated water, and an adsorption layer 14 formed in a layer shape on the surface of the core material 13. The adsorption layer 14 is formed to a predetermined thickness according to the concentration of the substance to be treated. According to the adsorbent 12, the core material 13 is formed in a membrane shape, and thus an integrally formed adsorption film is formed, which is less likely to dissipate compared to a particle-shaped one, can be attached regardless of the direction of the flow path, and is easy to handle when replacing.

[0051] As shown in FIG. 9, the adsorbent 12 formed into an adsorption film by a film-like core material 13 may be laminated into multiple layers. The number of layers of the adsorbent 12 to be laminated is appropriately adjusted according to the period during which the adsorption performance is to be exhibited, the shape of the object to be installed, and the like. The multiple layers may be formed by folding the adsorbent 12 formed into a single adsorption film into an accordion-like shape and laminating it. The multiple adsorbents 12 may be used, for example, as a replacement filter to be attached in the middle of a flow path through which the contaminated water W flows. Each layer of the adsorbent 12 may be formed into a pleated shape in order to increase the surface area. According to the adsorbent 12, since multiple film-like adsorption films are laminated, the adsorption performance can be exhibited for a desired period of time.

[0052] [Variation 2] As shown in FIG. 10, the adsorbent 15 has a plurality of adsorption layers 17 formed in a multi-layered manner on the surface of a core material 16. The core material 16 is formed in a particulate form. A release layer 18 is formed between the core material 16 and the adsorption layers 17 formed in a multi-layered manner and between the adsorption layers 17. The core material 16 is formed in a particulate form, for example, as described above. The adsorption layer 17 is formed of an adsorption material formed in the form of fine particles having a particle size of, for example, about 0.005 mm. The adsorption layer 17 is formed, for example, in a particulate form, such that the release layer 18 is formed of an adsorption material having a particle size larger than that of the adsorption layer 17 (for example, about 0.01 mm in diameter).

[0053] For example, when the adsorption performance of the outermost adsorption layer 17 of the adsorbent 15 is reduced, the surface layer of the adsorbent 15 is peeled off, and the adsorption layer 17 formed in the lower layer is exposed on the surface, thereby recovering the adsorption performance. When the adsorption performance is reduced, the adsorption layer 17 is peeled off sequentially from the surface layer. When the adsorption performance is reduced, the adsorption layer 17 is stirred by a water flow or dried in a container, for example, and the peeling layer 18 is collapsed by stirring in the container, and the adsorption layer 17 formed on the lower side of the peeling layer 18 is exposed. The peeling layer 18 may be formed of a substance that dissolves and collapses in response to a specific chemical solution, and the surface adsorption layer 17 may be peeled off by spraying the chemical solution after use. The peeled adsorption layer 17 and the adsorbent 15 may be separated, for example, by centrifugation.

[0054] The adsorbent 15 can be used until the adsorption performance of the surface adsorption layer 17 for the substance to be treated decreases, and then the surface adsorption layer 17 can be peeled off, making it possible to recover the adsorption performance multiple times, thereby significantly reducing the cost of purifying the contaminated water W.

[0055] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention as well as the invention described in the claims and their equivalents. For example, the adsorbent may adsorb not only cesium ions and strontium ions but also other ionic compounds. In that case, the adsorption layer may be formed to a layer thickness according to the concentration of the substance to be treated. The adsorbent may not only be replaced in the purification unit 4, but may also be replaced with the purification unit 4. The adsorbent may be used to adsorb ionic compounds as well as radioactive substances, and may be applied to improving water quality as well as purifying contaminated water. [Explanation of symbols]

[0056] Reference Signs List 1...purification facility, 2...storage section, 4...purification section, 5...storage container, 6...adsorbent, 7...adsorbent, 8...core, 9...adsorption layer, 12...adsorbent, 13...core, 14...adsorption layer, 15...adsorbent, 16...core, 17...adsorption layer, 18...peeling layer, 20...test device, 21...first container, 30...second container, 40...third container, F...filter, H...piping, H2...discharge port, H3...drain pipe, H4...drain port, P...pump, Q...pump, W...contaminated water, W'...contaminated water simulant

Claims

1. An adsorbent for purifying contaminated water that adsorbs a substance to be treated contained in contaminated water, A core material formed into a shape according to the mode of use; an adsorption layer formed on a surface of the core material by an adsorption material that adsorbs the substance to be treated, the adsorption layer being formed to a predetermined layer thickness according to the concentration of the substance to be treated in the contaminated water; Equipped with The concentration is 2 ppm or less, and the layer thickness is 0.1 μm or more and 500 μm or less.

2. The core material is formed into particles having a predetermined particle size. The adsorbent for purifying contaminated water according to claim 1.

3. The particle size is 2 mm or less. The adsorbent for purifying contaminated water according to claim 2.

4. The contaminated water is filled into a container through which the contaminated water flows. The adsorbent for purifying contaminated water according to claim 1 or 2.

5. The core material is formed in a membrane shape that filters the contaminated water. The adsorbent for purifying contaminated water according to claim 1.

6. An adsorption film formed in a film shape by the core material is provided, A plurality of the adsorption films are stacked. The adsorbent for purifying contaminated water according to claim 5.

7. The stacked adsorption films are attached to a flow path through which the contaminated water flows. The adsorbent for purifying contaminated water according to claim 6.

8. A plurality of the adsorption layers are formed in a multilayer on the surface of the core material. The adsorbent for purifying contaminated water according to any one of claims 1 to 7.

9. The surface layer in the multilayer is peeled off when the adsorption performance of the adsorption layer is deteriorated. The adsorbent for purifying contaminated water according to claim 8.

10. The substance to be treated is cesium ions and strontium ions and the adsorbent is a silicitanate, or the substance to be treated is cesium ions and the adsorbent is a combination of zeolite or ferrocyanide, or the substance to be treated is iodide ions and the adsorbent is a combination of silver-containing zeolites, or the substance to be treated is iodate ions and / or antimony ionic compounds and the adsorbent is at least one of a combination of cerium hydroxide-based adsorbents. The adsorbent for purifying contaminated water according to any one of claims 1 to 9.

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