Cartridge filter device for adsorbing hardly decomposable substance, system of removing hardly decomposable substance, method of removing hardly decomposable substance, and method of decreasing water content of cartridge filter device

Abstract

To provide a cartridge filter device for adsorbing a hardly decomposable substance, which device is compact and simple, and is capable of efficiently removing a hardly decomposable substance present in water to be treated, a system of removing a hardly decomposable substance, a method of removing a hardly decomposable substance, and a method of decreasing the water content of the cartridge filter device.SOLUTION: The cartridge filter device for adsorbing a hardly decomposable substance comprises: a filter unit 2 comprising a perforated water collection pipe 1, and an adsorptive sheet 21 which is wound round the water collection pipe 1, has gas permeability, and comprises a graft chain imparted with an ion exchange group for adsorbing a hardly decomposable substance; and a housing container 3 housing the filter unit 2, in which water to be treated including a hardly decomposable substance is fed into the housing container 3 to make the adsorption sheet 21 adsorb the hardly decomposable substance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cartridge filter device for adsorbing persistent substances, a system for removing persistent substances, a method for removing persistent substances, and a method for reducing the water content of a cartridge filter device. [Background technology]

[0002] Polychlorinated biphenyls (PCBs), dioxins, and fluorocarbons (PFASs), which are regulated by the Stockholm Convention on Persistent Organic Pollutants (POPs Convention), are substances that are difficult to decompose, highly accumulative, long-distance mobile, and harmful (to human health and ecosystems), and their accumulation in soil and water environments is a problem. In particular, PFASs have been detected in tap water and well water in certain areas in recent years at concentrations above the standard value, so there is a strong demand for their separation and decomposition from the water environment.

[0003] For example, JP 2010-519018 A (Patent Document 1) describes the removal of perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and the like, using an ion exchange resin containing an insoluble matrix to which functional groups are bonded in order to remove fluorochemicals from water.

[0004] Japanese Patent Application Publication No. 2022-069280 (Patent Document 2) describes a method for filtering persistent organic pollutants using a filtration device carrying an adsorbent such as activated carbon or Prussian blue on the outer surface of a pleated filter. In addition, Japanese Patent Application Publication No. 2001-62313 (Patent Document 3) describes an example of a method for eluting PFOA or the like bound to an anion exchange resin by contacting it with a mixture of water and an organic solvent. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2010-519018 [Patent Document 2] Patent Publication No. 2022-069280 [Patent Document 3] JP 2001-62313 A Summary of the Invention [Problem to be solved by the invention]

[0006] PFAS separated from the treated water using adsorbents, etc. are difficult to completely decompose using ozone, ultraviolet light, hydrogen peroxide, photocatalysts, or combinations thereof (AOP, etc.), so incineration is one of the practical decomposition methods. However, in adsorbents filled with granular or aggregated adsorbents such as activated carbon and ion exchange resins, as described in Patent Documents 1 to 3, in order to increase the surface area and increase the amount of adsorption per unit volume, the particle diameter must be reduced, resulting in increased water resistance and air resistance. Therefore, it takes time to dry and dehydrate adsorbents such as used activated carbon and ion exchange resins, and dehydration may be insufficient.

[0007] When PFAS, which is a persistent substance, is adsorbed and separated from treated water using adsorbents such as ion exchange resins and activated carbon, it has been considered to separate PFAS from the used adsorbent and regenerate the adsorbent. However, this process usually requires organic solvents, making on-site regeneration at water purification plants and water treatment facilities difficult. Therefore, the adsorbent is regenerated at a regeneration plant, but the work of removing the adsorbent, which contains a large amount of water, and transporting it to the regeneration plant takes time, cost, and energy.

[0008] In view of the above problems, the present invention provides a cartridge filter device for adsorbing persistent substances, which is capable of removing persistent substances in treated water more efficiently and in a more energy-saving manner using a small, simple device, a system for removing persistent substances, a method for removing persistent substances, and a method for reducing the water content of a cartridge filter device. [Means for solving the problem]

[0009] As a result of intensive research conducted by the present inventors to solve the above problems, they discovered that it is effective to adsorb and remove persistent substances in the water to be treated using a filter cartridge device having a predetermined configuration.

[0010] In order to solve the above problems, in one aspect, the present invention provides a cartridge filter device for adsorbing difficult-to-decompose substances, comprising a perforated water collection pipe, a filter unit wound around the water collection pipe, which is breathable and has an adsorption sheet having graft chains to which ion exchange groups for adsorbing difficult-to-decompose substances are attached, and a storage container for housing the filter unit, in which water to be treated containing difficult-to-decompose substances is supplied into the storage container and the difficult-to-decompose substances are adsorbed onto the adsorption sheet.

[0011] In one embodiment of the cartridge filter device for adsorbing persistent substances according to the present invention, the adsorption sheet has a size of 100 to 350 cm 3 / cm 2 -S breathability.

[0012] In another embodiment of the cartridge filter device for adsorbing difficult-to-decompose substances according to the present invention, the difficult-to-decompose substances include an organic fluorine compound having a hydroxy group, a carboxy group, or a sulfo group, and the ion exchange group is one or more types of functional groups selected from a primary amine group, a secondary amine group, a tertiary amine group, and a quaternary amine group.

[0013] In yet another embodiment of the cartridge filter device for adsorbing persistent substances according to the present invention, the storage container has one or more openings, and the openings are either open to the outside so as to allow moisture in the storage container to escape to the outside of the storage container when a dry fluid is supplied from a water collection pipe to remove moisture from the filter section, or are connected to a pipe that discharges moisture to the outside.

[0014] In another aspect, the present invention provides a system for removing persistent substances, comprising: a filter unit including a perforated water collection pipe, a filter section including an adsorption sheet wound around the water collection pipe, the filter section being breathable and having graft chains to which ion exchange groups for adsorbing persistent substances are attached, and a storage container for accommodating the filter section; treated water supply means connected to the filter unit and supplying water to be treated into the storage container and bringing it into contact with the filter section, thereby adsorbing the persistent substances onto the adsorption sheet, and causing the treated water after adsorption treatment to flow out of the storage container via the water collection pipe; and drying means connected to the filter unit and supplying a drying fluid to the filter section via the water collection pipe to bring it into contact with the filter section, thereby removing moisture from the filter section.

[0015] In one embodiment, the system for removing difficult-to-decompose substances according to the present invention includes a plurality of filter units, the plurality of filter units including a plurality of treatment units connected in series to each other and a spare unit connectable to the plurality of treatment units, and the removal system includes a switching means for switching the flow path of the treated water so that, when the filter portion of any treatment unit among the plurality of treatment units is replaced, the spare unit is connected in series subsequent to a treatment unit that is the last of the plurality of treatment units other than the any treatment unit.

[0016] In another embodiment of the system for removing persistent substances according to the present invention, the filter unit includes a plurality of filter parts connected in series within a container.

[0017] In yet another embodiment of the system for removing persistent substances according to the present invention, the filter unit comprises: The device includes a plurality of filter elements each having a water collection pipe, one or more filter portions, and a storage container as constituent units, and the plurality of filter elements are arranged in parallel to one another within a housing that contains the plurality of filter elements.

[0018] In yet another aspect, the present invention provides a method for removing difficult-to-decompose substances, comprising the steps of supplying water to be treated containing difficult-to-decompose substances into a filter unit including a perforated water collection pipe, a filter part wound around the water collection pipe, the filter part having an adsorption sheet which is breathable and has graft chains to which ion exchange groups for adsorbing difficult-to-decompose substances are attached, and a storage container for housing the filter part, and bringing the water to be treated into contact with the filter part, thereby adsorbing the difficult-to-decompose substances onto the adsorption sheet and removing them.

[0019] In one embodiment, the method for removing persistent substances according to the present invention further comprises a drying step of removing moisture from the filter portion by supplying a drying fluid from a water collection pipe.

[0020] In another embodiment of the method for removing persistent substances according to the present invention, the method further comprises an incineration step of recovering and incinerating the filter part after the drying step.

[0021] In yet another embodiment of the method for removing difficult-to-decompose substances according to the present invention, the filter unit comprises a plurality of treatment units connected in series to each other and a spare unit connectable to the plurality of treatment units, and includes stopping the supply of the water to be treated or the water to be treated to any one of the plurality of treatment units, and after stopping the supply of the water to be treated or the water to be treated, supplying a dry fluid from a water collection pipe to the any one of the treatment units to remove moisture from the filter section, and then recovering the filter section from which moisture has been removed. During the process of removing moisture and the process of recovering the filter section, the spare unit is connected in series to a downstream stage of a treatment unit that is the last stage of the plurality of treatment units other than the any one of the treatment units, and the water to be treated is supplied to the treatment unit connected to the downstream stage of the any one of the treatment units, and a process of adsorption and removal of difficult-to-decompose substances in the water to be treated or the water to be treated is performed.

[0022] In still another embodiment, the method for removing persistent substances according to the present invention comprises treating water to be treated having an organofluorine compound concentration of 50,000 ng / L or less.

[0023] In yet another aspect, the present invention provides a method for reducing the moisture content of a cartridge filter device, comprising: removing moisture from a filter portion by supplying a dry fluid from a water collection pipe of the cartridge filter device for adsorbing persistent substances; and discharging the dry fluid after contact with the filter portion to the outside of a storage container through one or more openings provided in the storage container, thereby reducing the moisture content of the filter portion. Effect of the Invention

[0024] According to the present invention, it is possible to provide a cartridge filter device for adsorbing persistent substances, which is capable of removing persistent substances in treated water more efficiently and in a more energy-saving manner using a small and simple device, a system for removing persistent substances, a method for removing persistent substances, and a method for reducing the water content of a cartridge filter device. [Brief description of the drawings]

[0025] [Figure 1] 1 is a schematic view showing an example of a cross section of a cartridge filter device according to an embodiment of the present invention as viewed from an axial direction. [Diagram 2] 1 is a schematic view showing an example of a cross section of a cartridge filter device according to an embodiment of the present invention as viewed in a radial direction. [Diagram 3] FIG. 2 is a perspective view showing an example of a filter unit according to an embodiment of the present invention. [Figure 4] 5A to 5C are schematic diagrams illustrating an example of a method for producing an adsorption sheet according to an embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic view showing an example of a cross section seen from a radial direction of a cartridge filter device according to a modified embodiment of the present invention. [Figure 6] 6 is a schematic view showing an example of an axial cross section along the VI-VI cross section of the cartridge filter device of FIG. 5. [Figure 7] 4 is a flowchart illustrating a method for reducing a moisture content of a cartridge filter device according to an embodiment of the present invention. [Figure 8] 1 is an explanatory diagram illustrating a method for reducing a moisture content in a cartridge filter device according to an embodiment of the present invention. [Figure 9] 1 is a schematic diagram showing an example of a persistent substance removal system according to an embodiment of the present invention. [Figure 10] FIG. 2 is a schematic diagram showing a modified example of the system for removing persistent substances according to an embodiment of the present invention. [Figure 11] 1 is a graph showing the drying characteristics of samples of Examples 1 and 2 and Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. Note that the embodiment shown below is an example of an apparatus and method for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the structure, arrangement, etc. of the components to those described below.

[0027] (Water to be treated) In the embodiment of the present invention, the water to be treated is not particularly limited as long as it contains a hardly decomposable substance, and various waters such as industrial water, agricultural water, drinking water, and pure water are used. Here, the hardly decomposable substance refers to organic matter that is harmful to human health, such as dioxins, polychlorinated biphenyls (PCBs), organochlorine pesticides such as DDT, and polycyclic aromatic hydrocarbons, which are regulated by the Stockholm Convention on Persistent Organic Pollutants. In particular, in this embodiment, water to be treated that contains hardly soluble substances including organic fluorine compounds having a hydroxyl group, a carboxyl group, or a sulfo group, typically PFOS, PFOA, etc., can be treated.

[0028] Although not limited thereto, the adsorption and removal performance is more suitable and efficient for the water to be treated having an organic fluorine compound concentration of, for example, 50,000 ng / L or less, further 20,000 ng / L or less, and further 6,000 ng / L or less. In particular, even when the water to be treated has a relatively low organic fluorine compound concentration of 1,000 ng / L or less, further 600 ng / L or less, the adsorption and removal performance is higher than that of the conventional adsorption treatment using ion exchange resin. There is no particular limit to the lower limit of the organic fluorine compound concentration in the water to be treated, and the water can be treated by the treatment method according to the embodiment of the present invention as long as the water contains organic fluorine compounds at least equal to or higher than the detection limit (about 5 ng / L). In addition to organic fluorine compounds, the water to be treated may contain various ions derived from the aqueous environment, for example, ions of natural organic compounds having a charge.

[0029] (Cartridge filter device for adsorbing persistent substances) As shown in FIG. 1, a cartridge filter device for adsorbing persistent substances according to an embodiment of the present invention comprises a perforated water collection pipe 1, a breathable filter unit 2 wound around the water collection pipe 1, and a storage container 3 for housing the filter unit 2.

[0030] The pipe wall of the water collection pipe 1 is permeable and is configured as a perforated pipe having a plurality of holes 12 so that the treated water that has passed through the filter section 2 can flow from the outside of the water collection pipe 1 into the inside of the water collection pipe 1. The shape and size of the holes 12 provided in the water collection pipe 1 are not particularly limited. In order to efficiently pass the fluid from the water collection pipe 1 to the filter section 2, for example, the diameter of the holes 12 is preferably 5 mm or more, further 10 mm or more, typically about 10 to 20 mm. The number and positions of the holes 12 are not particularly limited. In order to more efficiently pass the fluid to be flowed into the water collection pipe 1, the water collection pipe 1 preferably has holes 12 at least in the portions facing the filter sections 2a and 2b.

[0031] 1 shows an example in which two filter units 2a, 2b are provided in series within the storage container 3, but the number of filter units 2a, 2b is not limited to two and may be one, or three or more, for example, 3 to 10. It is preferable that a plurality of filter units 2a, 2b are connected in series and appropriately set depending on the desired performance, the size of the installation location, etc.

[0032] As shown in Fig. 2, the filter unit 2a typically has a cylindrical shape with a through hole in the center for passing the water collection pipe 1 through. As shown in Fig. 3, the filter unit 2 includes a breathable adsorption sheet 21 wound around the water collection pipe 1, and a water-repellent mesh-like resin sheet 22 provided on the outermost part of the adsorption sheet 21 to protect the adsorption sheet 21. Removable end caps 23 are provided on both ends of the adsorption sheet 21 and the mesh-like resin sheet 22. The end caps 23 protect both ends of the adsorption sheet 21 and the mesh-like resin sheet 22, and have the function of preventing the treated water that has flowed into the filter units 2a and 2b from leaking out of the filter unit 2 before it flows into the water collection pipe 1.

[0033] As the adsorption sheet 21, it is preferable to use an adsorption sheet 21 having graft chains to which ion exchange groups for adsorbing persistent substances are added. The adsorption sheet 21 has a higher effective surface area and higher air permeability than adsorbents filled with activated carbon or granular ion exchange resin. Therefore, the adsorption sheet 21 has a larger pore size of the base material than the ion exchange resin, and the contact efficiency between the ion exchange groups and the target substance to be treated is significantly improved, so that it is also excellent in treating low-concentration target substances and can adsorb persistent substances more efficiently at low cost.

[0034] The suction sheet 21 has a ventilation rate of 100 to 350 cm 3 / cm 2 s, preferably 120 to 300 cm 3 / cm 2 s, more preferably 150 to 250 cm 3 / cm 2Since the adsorption sheet 21 has air permeability, the moisture in the adsorption sheet 21 is easily and quickly removed by the drying step described below in which a drying fluid is brought into contact with the adsorption sheet 21 after the adsorption of the persistent substances. 3 / cm 2 If the air permeability is less than 350 cm s, the air permeability is too low, and it may be difficult to efficiently dry the used adsorption sheet 21. 3 / cm 2 If it exceeds ·s, the strength of the adsorption sheet 21 will be weakened, and the filter portions 2a, 2b may be damaged.

[0035] The air permeability of the suction sheet 21 is evaluated in accordance with the air permeability test based on JIS L 1096A (Fragile method). Specifically, five test pieces of approximately 200 mm x 200 mm are taken, attached to a Frazier type tester, air is sucked in to a pressure of 125 Pa, and the air flow rate is measured using a conversion table attached to the tester. The air permeability (cm 3 / (cm 2 ·s) is required.

[0036] The adsorption sheet 21 preferably uses a material selected from woven fabric, nonwoven fabric, fiber material, etc. as the substrate 20, and a material having graft chains 202 and ion exchange groups 203 provided on the substrate 20. For example, polyolefins such as polyethylene, polyethylene terephthalate, polypropylene, polybutene, and polystyrene, copolymers of olefins and halogenated polyolefins such as ethylene-tetrafluoroethylene copolymers, etc. are used as the substrate 20. The substrate 20 may be a single fiber using one type of polymer, or a composite fiber using multiple types of polymers.

[0037] The adsorption sheet 21 can be manufactured, for example, by using a graft polymerization method, particularly a radiation-induced graft polymerization method. The radiation-induced graft polymerization method includes a pre-irradiation method in which a polymer substrate is irradiated with radiation and then brought into contact with a monomer to carry out a polymerization reaction, and a simultaneous method in which a polymer substrate is irradiated with radiation while being brought into contact with a monomer, and either method may be adopted. In the radiation-induced graft polymerization method, for example, as shown in FIG. 4(a), a substrate 20 is irradiated with radiation such as gamma rays or electron beams, and radicals 201 are generated on the substrate 20 as shown in FIG. 4(b). Then, for example, a graft chain 202 having an ion exchange group 203 for adsorbing a poorly soluble substance is formed on the substrate 20.

[0038] Examples of monomers that can be used to form the graft chain 202 include vinylbenzyltrimethylammonium chloride (VBTAC), N-vinylpyrrolidone (NVP), dimethylaminoethyl methacrylate (DMAEMA), diethylaminoethyl methacrylate (DEAEMA), dimethylaminopropylacrylamide (DMAPAA), styrene (St), glycidyl methacrylate (GMA), glycidyl acrylate, chloromethylstyrene (CMS), vinylpyridine (VP), and the like. Among these, at least one of VBTAC, NVP, and CMS is preferably used.

[0039] The substrate 20 is impregnated with a monomer solution to carry out a graft polymerization reaction, thereby forming graft chains 202 to which ion exchange groups 203 have been imparted, as shown in Fig. 4(d). When the graft chains 202 do not have the desired ion exchange groups 203 derived from the monomer, as shown in Fig. 4(c), the graft chains 202 may be formed on the substrate 20 as shown in Fig. 4(c), and then the desired ion exchange groups 203 may be imparted to the surface and inside of the graft chains 202 as shown in Fig. 4(d).

[0040] As the ion exchange groups imparted to the adsorption sheet 21, anion exchange groups are preferably imparted. As the anion exchange groups, one or more types of functional groups selected from primary amine groups, secondary amine groups, tertiary amine groups, and quaternary amine groups are preferably used. In order to more efficiently adsorb low-concentration poorly soluble substances contained in the water to be treated, it is more preferable to impart tertiary amine groups, quaternary amine groups, etc. to the adsorption sheet 21 rather than primary amine groups and secondary amine groups. Most preferable are quaternary amine groups (quaternary ammonium groups), which are strongly basic anion exchange groups. The amount of anion exchange groups imparted can be appropriately selected depending on the application, required performance, etc.

[0041] Although there is no particular limitation on the configuration of the mesh-like resin sheet 22, a mesh-like water-repellent sheet is typically used. The end caps 23 are made of a water-impermeable material.

[0042] Although the specific shape and size of the storage container 3 are not particularly limited, it is preferable that the size be portable for efficient replacement work. Although not limited thereto, for example, the length of the storage container 3 in the extension direction (axial direction) is typically 400 to 800 mm, and the diameter may be about 100 to 300 mm.

[0043] As shown in Figures 1 and 2, the storage container 3 has openings 11a, 11b for inserting the water collection pipe 1, and openings 31a, 31b connected to supply pipes 32a, 32b that supply the water to be treated into the storage container 3.

[0044] The openings 11a, 11b function as an outlet for discharging treated water obtained in the filter unit 2 from the filter unit 2 via the water collection pipe 1 to the outside of the storage vessel 3 during the adsorption treatment of persistent substances, while functioning as an inlet for allowing a drying fluid to flow into the storage vessel 3 via the water collection pipe 1 during the drying treatment. The openings 31a, 31b function as an inlet for allowing the treated water flowing in from the filter unit 2 to flow into the inside of the storage vessel 3 during the adsorption treatment of persistent substances, while being opened to the outside so that the moisture in the storage vessel 3 can escape to the outside of the storage vessel 3 when the drying fluid is supplied from the water collection pipe 1 to remove the moisture in the filter unit 2, or function as an outlet for discharging a fluid containing moisture (water vapor) generated in the storage vessel 3 to the outside of the storage vessel 3 via the supply pipes 32a, 32b. Although not shown, in order to further promote ventilation in the storage container 3 and improve the efficiency of the drying process of the filter portion 2, the storage container 3 may be provided with one or more openings (not shown) other than the openings 31a, 31b for allowing moisture within the storage container 3 to escape to the outside when the filter portion 2 is dried.

[0045] 5, the cartridge filter device may include a plurality of filter elements 10. That is, the cartridge filter device according to the embodiment of the present invention may include a filter unit 100 including a plurality of filter elements 10, each of which has a water collection pipe 1, one or more filter portions 2, and a storage container 3 including a supply pipe 32a as its constituent units. The plurality of filter elements 10 are housed in a housing 101 for housing the plurality of filter elements 10.

[0046] As shown in FIG. 6, the supply pipes 32a, 32b connected to the openings 31a, 31b of the multiple filter elements 10 are connected via flow paths 34a, 34b, respectively. The flow path 34a is connected to openings 311a, 312a provided in the housing 101. The opening 311a is connected to a supply flow path for supplying treated water (also called "pre-treated water") supplied from another filter unit (not shown) connected to the upstream side of the housing 101 in FIG. 6 into the storage vessel 3. The opening 312a is connected to a flow path for supplying water to be treated (raw water). The flow path 34b is connected to openings 311b, 312b provided in the housing 101. The opening 311b is connected to a supply flow path for supplying treated water (also called "pre-treated water") supplied from another filter unit (not shown) connected to the upstream side of the housing 101 in FIG. 6 into the storage vessel 3. The opening 312b is connected to a flow path through which the water to be treated (raw water) is supplied.

[0047] The water collection pipes 1 are connected in parallel via flow paths 13a and 13b, respectively. The treated water collected in the water collection pipes 1 is discharged to the outside via discharge flow paths for discharging the treated water from openings 313a and 313b of the housing 101. The housing 101 may further include one or more openings 314 for ventilation.

[0048] According to the embodiment of the present invention, as shown in Figures 5 and 6, a filter unit 100 is provided in which a plurality of filter elements 10 are housed in parallel in a housing 101, thereby increasing the treatment capacity of the water to be treated. This makes it possible to more efficiently remove persistent substances in the water to be treated. Note that, although the example of Figure 5 shows an example in which four filter elements 10 are housed in the housing 101, the number of filter elements 10 can of course be changed as appropriate based on the required treatment capacity and the installation location.

[0049] (Method for removing persistent substances) Next, a method for removing persistent substances according to an embodiment of the present invention will be described with reference to the flow chart of FIG. 7 and the explanatory diagrams of FIG. 8(a) and FIG. 8(b). In step S101, the water to be treated is supplied into the storage container 3. For example, as shown in FIG. 8(a), the water to be treated is supplied into the storage container 3 from the supply pipe 32a connected to one end of the storage container 3. At this time, the water to be treated is not supplied from the supply pipe 32b connected to the other end of the storage container 3. The water to be treated supplied into the storage container 3 through the supply pipe 32a flows into the inside of the water collection pipe 16 through the filter parts 2a and 2b. The persistent substances contained in the water to be treated are captured by binding to the anion exchange groups imparted to the graft chains of the adsorption sheet 21 of the filter part 2a when passing through the filter parts 2a and 2b. The water to be treated that has flowed into the inside of the water collection pipe 1 flows toward one end of the storage container 3 on the side where the opening 11b is formed, and flows out of the filter element 10.

[0050] After the above treatment is performed for a predetermined time, the water to be treated is then supplied from the other supply pipe 32b into the storage vessel 3. At this time, the water to be treated is not supplied from the supply pipe 32a connected to the other end of the storage vessel 3. The water to be treated supplied into the storage vessel 3 through the supply pipe 32b flows into the water collection pipe 1 through the filter units 2a and 2b. When passing through the filter units 2a and 2b, poorly soluble substances contained in the water to be treated are captured by binding with anion exchange groups provided to the graft chains of the adsorption sheet 21 of the filter unit 2a, and are adsorbed and removed from the water to be treated (step S102). The water to be treated that has flowed into the water collection pipe 1 flows toward one end of the storage vessel 3 on the side where the opening 11a is formed, and flows out of the filter element 10.

[0051] In this manner, the water to be treated is alternately supplied from the axial ends of the storage vessel 3 to perform the adsorption and separation process of the persistent substances. This allows the performance of the filter units 2a, 2b to remove persistent substances to be fully utilized over the entire surface of the filter units 2a, 2b. In other words, by appropriately changing the flow direction of the water to be treated in the storage vessel 3, the water to be treated can be brought into contact with the adsorption sheets 21 of the filter units 2a, 2b more uniformly, thereby improving the performance of the filter units 2a, 2b in adsorbing and removing persistent substances.

[0052] As the water to be treated continues to pass through and the hardly decomposable substances are adsorbed to the filter sections 2a and 2b, the adsorption performance of the filter sections 2a and 2b begins to decrease. When the adsorption performance of the filter sections 2a and 2b decreases, the concentration of the hardly soluble substances in the treated water begins to increase, and the target adsorption effect cannot be obtained. In step S103 of FIG. 7, the operator determines whether or not to replace the filter sections 2a and 2b. If the filter sections 2a and 2b are to be replaced, the process proceeds to step S104, and if not, the process returns to step S102.

[0053] The timing for replacing the filter units 2a, 2b can be determined, for example, as follows. For example, there is a method of measuring the concentration of poorly soluble substances in the treated water collected from the water collection pipe 1 at regular intervals, and replacing the filter units 2a, 2b when the concentration of poorly soluble substances exceeds a predetermined reference value. Another method is to install a flow meter (not shown) at the inlet of the water to be treated or pre-treated water and at the outlet side of the water collection pipe 1, and monitor the decrease in the flow rate at the outlet side of the water collection pipe 1. As a method for monitoring the decrease in flow rate, for example, the filter units 2a, 2b are replaced when the flow rate at the outlet side of the water collection pipe 1 falls below a predetermined reference value.

[0054] Next, in step S104, the supply of water to be treated to the filter element 10 including the filter portions 2a, 2b to be replaced is stopped. Here, for example, as shown in FIG. 8(b), a dry fluid is fed into the storage container 3 from both ends of the storage container 3 through the water collection pipe 1. The dry fluid flows through the water collection pipe 1 to the filter portions 2a, 2b, whereby the moisture in the filter portions 2a, 2b is condensed and removed. After contacting the filter portions 2a, 2b, the dry fluid is discharged to the outside together with the moisture (water vapor) condensed in the storage container 3 through the supply pipe 32a connected to the opening 31a formed in the storage container 3.

[0055] Typically, air is used as the drying fluid, but there is no particular limitation as long as it is a fluid that can dry the filter element 10. The drying fluid may be heated and supplied into the storage container 3 to promote the drying process of the filter parts 2a and 2b. In this case, the temperature of the drying fluid may be from the outside air temperature to 100°C. The flow direction of the drying fluid may be alternately from one end to the other end of the storage container 3 and from the other end to one end, or the drying fluid may be supplied from both ends of the storage container 3 simultaneously.

[0056] The amount of the drying fluid flowing into the water collection pipe 1 is not particularly limited, but may be 100 L / min or more for more efficient drying. The time (drying time) for circulating the drying fluid into the water collection pipe 1 depends on the size of the filter element 10, etc., but is, for example, 1 hour or more, more typically 3 hours or more. If the drying time is too long, it may be undesirable from the viewpoint of energy saving. Although not limited to the following, for example, it is preferable to set it to 10 hours or less, and further 6 hours or less. By performing such a drying process, the moisture content of the adsorption sheet 21 provided in the filter element 10 can be reduced by, for example, 5% or more, more typically 15% or more, compared to before drying, although it is not limited to the following. The time for circulating the drying fluid into the water collection pipe 1 and the temperature of the drying fluid can be appropriately adjusted according to the outside air temperature, the processing flow rate, and the size of the adsorption sheet 21, such as the thickness and area.

[0057] After the drying process in step S104 is completed, in step S105, the filter element 10 including the dried filter portions 2a, 2b is collected and replaced with a new filter element 10. If necessary, the filter portions 2a, 2b can be disassembled and incinerated in an incineration process, whereby the persistent substances adsorbed to the filter portions 2a, 2b can be decomposed and rendered harmless.

[0058] According to the method for removing persistent substances according to the embodiment of the present invention, the persistent substances contained in the water to be treated are adsorbed using the filter parts 2a and 2b including the adsorption sheet 21 having ion exchange groups attached to the graft chains. The adsorption sheet 21 according to the embodiment of the present invention is less expensive, smaller, and has a larger surface area than the case where the persistent substances are removed using granular ion exchangers, etc., and therefore, the adsorption and separation process of the persistent substances can be performed more efficiently with a simple device. After the adsorption and separation process of the persistent substances, a drying fluid is supplied to the filter parts 2a and 2b to remove the moisture from the filter parts 2a and 2b and to reduce the moisture content of the filter parts 2a and 2b. This can reduce the amount of thermal energy consumed when the filter parts 2a and 2b are incinerated. Furthermore, the drying process of the filter parts 2a and 2b can be performed on-site in the facility in which the filter element 10 is arranged. Therefore, the weight of the filter element 10 can be reduced in the facility and then transported to a predetermined facility. This reduces the burden of the work of transporting the filter element 10 compared to the case where the filter element 10 that has not been dried is transported to the outside.

[0059] (Removal system for persistent substances) As shown in Fig. 9, the removal system for persistent substances according to the embodiment of the present invention includes a filter unit 100 including a perforated water collection pipe 1, filter parts 2a and 2b wound around the water collection pipe 1, which are breathable and include an adsorbent sheet 21 having graft chains to which ion exchange groups for adsorbing persistent substances are attached, a storage vessel 3 for storing the filter parts 2a and 2b, a water-to-be-treated supply means 4, and a drying means 5. The filter unit 100 in Fig. 9 illustrates an example in which two filter parts 2a and 2b are connected in series to the water collection pipe 1 within the storage vessel 3, but it is needless to say that the present invention is not limited to this example.

[0060] The untreated water supplying means 4 is connected to the filter unit 100, and is configured to supply the untreated water into the storage container 3 and bring it into contact with the filter sections 2a, 2b, thereby causing the persistently decomposable substances to be adsorbed onto adsorption sheets (not shown) provided in the filter sections 2a, 2b, and to cause the treated water after the adsorption treatment to flow out of the storage container via the water collection pipe 1. The untreated water supplying means 4 includes, for example, a untreated water storage tank 40, flow paths 41, 43 for supplying the untreated water to the filter unit 100, switching means 42 such as a switching valve provided in the flow paths 41, 43, a flow path 44 for supplying the treated water collected from the water collection pipe 1, and a treated water storage tank 45 for storing the treated water.

[0061] The drying means 5 is connected to the filter unit 100, and is configured to supply a drying fluid to the filter parts 2a, 2b via the water collection pipe 1 to bring the drying fluid into contact with the filter parts 2a, 2b, thereby removing moisture from the filter parts 2a, 2b. The drying means 5 includes, for example, a drying fluid supplying part 50 such as a compressor that supplies the drying fluid, flow paths 51, 53 that supply the drying fluid to the filter units, and a switching means 52 such as a switching valve provided in the flow paths 51, 53. The switching means 42, 52 may be connected to a control means 6 that can output a control signal for switching the flow paths 41, 43, 51, 53 by the switching means 42, 52. The switching means 42, 52 may be manually switched by an operator.

[0062] When supplying the water to be treated to the filter unit 100 to supply the persistent substances in the water, the water is supplied from the water storage tank 40 through the flow path 41, the switching means 42, and the flow path 43 into the filter unit 100, and the water is brought into contact with the filter sections 2a and 2b. The treated water after contacting the filter sections 2a and 2b is stored in the treated water storage tank 45 from the water collection pipe 1 through the flow path 53, the switching means 52, and the flow path 44.

[0063] When drying the filter parts 2a and 2b in the filter unit 100, a drying fluid is supplied from the drying fluid supply part 50 into the filter unit 100 via the flow path 51, the switching means 52, and the flow path 53, and the drying fluid is brought into contact with the filter parts 2a and 2b. Here, the openings 11a and 11b provided in the filter unit 100 are either opened to the outside so that the moisture in the storage container 3 can escape to the outside of the storage container 3, or are connected to a pipe 46 that discharges the moisture to the outside, and the drying fluid (fluid containing water vapor) after contacting the filter parts 2a and 2b is discharged to the outside of the filter unit 100 from the openings 11a and 11b.

[0064] According to the embodiment of the present invention, the system for removing difficult-to-decompose substances is equipped with a water-to-be-treated supply means 4 and a drying means 5, making it possible to remove difficult-to-decompose substances in the water to be treated more efficiently and in a more energy-saving manner using a small and simple device.

[0065] (Modification) A persistent substance removal system according to a modified embodiment of the present invention may have a plurality of filter units 100a, 100b, 100c, and 100d connected in series, as shown in Fig. 10. The number of the plurality of filter units 100a, 100b, 100c, and 100d is not particularly limited, but for example, by connecting 4 to 10 filter units 100a, 100b, 100c, and 100d in series with each other, it is possible to deal with wastewater treatment of a large amount of water and to improve the removal rate of target substances.

[0066] The filter units 100a, 100b, 100c, and 100d may be configured, for example, by a plurality of treatment units 100a, 100b, and 100c connected in series with each other, and a spare unit 100d connectable to the treatment units 100a, 100b, and 100c. Water to be treated is passed from the water storage tank 40 to the treatment unit 100a, treated water from the treatment unit 100a is passed to the treatment unit 100b, and treated water from the treatment unit 100b is passed to the treatment unit 100c.

[0067] When the concentration of persistent substances in the treated water from the treatment unit 100c exceeds the control value, the treatment unit 100a, which is the most upstream in the direction of flow of the treated water (raw water), is selected for replacement. Then, the flow of water through the treatment unit 100a is stopped, a drying fluid is fed from the drying fluid supply unit 50 into the treatment unit 100a, and after drying treatment, the filter element in the treatment unit 100a is replaced.

[0068] While the dry fluid is fed from the dry fluid supply unit 50 into the treatment unit 100a and the treatment unit 100a is being replaced, the water to be treated from the water storage tank 40 is passed through the treatment unit 100b connected one stage downstream of the treatment unit 100a. Then, the treated water from the treatment unit 100b is passed through the treatment unit 100c. At this time, the spare unit 100d is connected to the rear stage of the treatment unit 100c, which is the last stage of the adsorption separation treatment, and the treated water from the spare unit 100d is passed through the spare unit 100d. This allows the treatment of the water to be treated to be continued even when the treatment unit 100a is being replaced.

[0069] After the replacement of the treatment unit 100a is completed, the supply of treated water from the treatment unit 100c is switched from the standby unit 100d to the treatment unit 100a. That is, after the replacement of the treatment unit 100a, the flow path is switched so that the treated water (raw water) is supplied in the order of the treatment unit 100b, the treatment unit 100c, and the treatment unit 100a.

[0070] In this way, water is passed through the multiple treatment units 100a, 100b, and 100c in a merry-go-round type multi-stage treatment, and switching means A, B, and C are arranged to switch the flow path of the treated water so that when the filter part of any of the treatment units 100a, 100b, and 100c is replaced, the spare unit 100d is connected in series to the rear of the last treatment unit among the multiple treatment units other than the arbitrary treatment units. This allows the water to be passed continuously through a large amount of water to be treated without stopping the adsorption treatment.

[0071] As described above, the present invention has been described with reference to the above-mentioned embodiment, but the description and drawings forming a part of this disclosure should not be understood as limiting the present invention. The present disclosure is not limited to the above-mentioned embodiment, and the components can be combined and modified to be embodied without departing from the spirit of the present disclosure. EXAMPLES

[0072] Examples of the present invention will be described below together with comparative examples. These examples are provided for a better understanding of the present invention and its advantages, and are not intended to limit the invention.

[0073] 1. Adsorption test 1 An ion exchange resin (Comparative Example 1: Dowex Monosphere 550A) and an ion exchange nonwoven fabric (Example 1: EPIX-B membrane, manufactured by ECE; Example 2: A-IEN membrane, manufactured by ECE) were prepared. The EPIX-B membrane is an adsorption sheet in which vinylbenzyltrimethylammonium chloride (VBTAC), which has a quaternary amine group (quaternary ammonium group), is used as a monomer on a base material of a polyethylene sheath / polypropylene core composite fiber to form a graft chain having a quaternary amine group (quaternary ammonium group) by radiation graft polymerization. The A-IEN membrane is an adsorption sheet in which chloromethylstyrene (CMS) is used as a monomer on a base material of a polyethylene fiber to form a polyCMS graft copolymer by radiation graft polymerization, and then trimethylamine is reacted to form a graft chain having a quaternary amine group (quaternary ammonium group). Each sample was adjusted so that the functional group equivalent weight was the same between Examples 1 and 2 and Comparative Example 1, and each sample was immersed in a PFOA solution (raw water) in which PFOA was added to pure water at the concentration shown in Table 1 for 24 hours while stirring, and the PFOA in the solution was adsorbed into each sample. The removal rate (%) when each sample was used was evaluated from the relationship between the PFOA concentration in the treated water after the immersion treatment and the PFOA concentration in the raw water. In this example, the PFOA concentration was calculated in accordance with JIS K0450-70-10:2011 using a liquid chromatography mass spectrometer. Table 1 shows the results of the adsorption removal treatment.

[0074] [Table 1]

[0075] In both Examples 1 and 2, the PFOA concentration in the treated water was reduced to 20 ng / L or less, and the ion exchange resin had high PFOA adsorption performance equivalent to that of the ion exchange resin of Comparative Example 1.

[0076] 2. Adsorption test 2 Using the same ion exchange resin and ion exchange nonwoven fabric as in Adsorption Test 1 above, samples were prepared with the same equivalent weight of functional groups for the ion exchange resin and ion exchange nonwoven fabric, and each sample was immersed for 24 hours while stirring in a PFOA mixed solution (raw water) made by adding a small amount of PFOA to actual river water, allowing the PFOA in the solution to be adsorbed into each sample. The removal rate (%) when each sample was used was evaluated based on the relationship between the PFOA concentration in the treated water after the immersion treatment and the PFOA concentration in the raw water. The results are shown in Table 2.

[0077] [Table 2]

[0078] It can be seen that both Examples 1 and 2 have high PFOA removal performance. In Comparative Example 1, in which a solution adjusted so that the PFOA concentration in the raw water was 300 to 600 ng / L (390 ng / L) was used, the removal rate was 61%, and sufficient adsorption effect was not obtained. On the other hand, it can be seen that both Examples 1 and 2 exhibit high PFOA removal rates in the range of PFOA concentrations of about 300 to 50,000 ng / L. In particular, even in the low concentration range of PFOA concentration in the raw water of 390 ng / L, the treated water concentration can be reduced to 20 ng / L or less, and it can be seen that Examples 1 and 2 can handle solutions with low to high PFOA concentrations, and can remove persistent substances at a high removal rate even in cases where coexisting ions coexisting with PFOA are contained, such as in river water.

[0079] 3. Drying test The same ion exchange resin and ion exchange nonwoven fabric as those used in the above adsorption tests 1 and 2 were prepared and each was 3After collecting samples and measuring their weights, they were immersed in ultrapure water overnight. After immersion, the samples of Examples 1 and 2 were taken out of the water, and the water was dripped off for more than 3 minutes, and then the samples were transferred to test tubes and their weights were measured. For the sample of Comparative Example 1 after immersion, the water was removed with a pipetter after being transferred to a test tube, and the weight of each test tube was measured. After measuring the weights, the samples of Examples 1 and 2 and Comparative Example 1 were placed in a dryer (drying temperature 55°C) and treated for a certain period of time, then removed from the dryer and allowed to cool, and the weights of the samples after cooling were measured. The weights of each sample before drying were set to 1, and the measurement results of the weight changes of each sample when drying was performed for 5 to 360 minutes are shown in FIG. 11. The weight change rate (vertical axis) in FIG. 11 was calculated by dividing the weight of each sample that changes with the drying time by the initial weight of each sample.

[0080] As shown in FIG. 11, the samples of Examples 1 and 2 showed larger changes in weight due to the drying treatment than Comparative Example 1, and the drying speed of the ion exchange nonwoven fabrics (graft polymerization membranes) of Examples 1 and 2 was about 1.3 times that of the ion exchange resin of Comparative Example 1.

[0081] The air permeability of the ion-exchange nonwoven fabrics of Examples 1 and 2 was measured in accordance with JIS L 1096A (Fragile method). The ion-exchange nonwoven fabric of Example 1 (EPIX-B) had an air permeability of 160 cm 3 / (cm 2 s), and the ion-exchange nonwoven fabric of Example 2 (A-IEN) is 217 cm 3 / (cm 2 ·s). [Explanation of symbols]

[0082] 1: Water collection pipe 2, 2a, 2b: Filter section 3: Containment Container 4: Means for supplying treated water 5:Drying means 6: Control means 10: Filter element 11a, 11b, 31a, 31b, 311a, 311b, 312a, 312b, 313a, 313b, 314: Opening 12: Hole 13a, 13b, 34a, 34b, 41, 43, 44, 51, 53: flow path 20: Base material 21: Adsorption sheet 22: Mesh resin sheet 23: End cap 32a, 32b: Supply pipe 40: Treated water storage tank 42, 52: Switching means 45: Treated water storage tank 46: Piping 50: Drying fluid supply section 100: Filter unit (processing unit, spare unit) 101: Housing 201: Radical 202: Graft chain 203: Ion exchange group

Claims

1. A perforated collection pipe; a filter section that is wound around the water collecting pipe, has air permeability, and includes an adsorption sheet having graft chains to which ion exchange groups for adsorbing persistent substances are attached; A container that houses the filter unit; Equipped with A cartridge filter device for adsorbing persistent substances, characterized in that water to be treated containing the persistent substances is supplied into the storage container, and the persistent substances are adsorbed onto the adsorption sheet.

2. The adsorption sheet has a thickness of 100 to 350 cm 3 / cm 2 2. The cartridge filter device for adsorbing persistent substances according to claim 1, which has an air permeability of 1.0 s.

3. 2. The cartridge filter device for adsorbing difficult-to-decompose substances according to claim 1, wherein the difficult-to-decompose substances include an organic fluorine compound having a hydroxy group, a carboxy group, or a sulfo group, and the ion exchange group is one or more types of functional groups selected from a primary amine group, a secondary amine group, a tertiary amine group, or a quaternary amine group.

4. the container has one or more openings; The cartridge filter device for adsorbing persistent substances as described in any one of claims 1 to 3, wherein the opening is open to the outside so as to allow the moisture in the storage container to escape to the outside of the storage container when a dry fluid is supplied from the water collection pipe to remove moisture from the filter section, or is connected to a pipe that discharges the moisture to the outside.

5. a filter unit including a perforated water collection tube, a filter part that is wound around the water collection tube, has air permeability, and includes an adsorption sheet having graft chains to which ion exchange groups for adsorbing persistent substances are attached, and a container that contains the filter part; a water-to-be-treated supply means connected to the filter unit, for supplying water to be treated into the storage container and bringing the water into contact with the filter section, thereby causing the persistent substances to be adsorbed onto the adsorption sheet, and discharging the treated water after the adsorption treatment out of the storage container through the water collection pipe; a drying means connected to the filter unit, supplying a drying fluid to the filter portion through the water collection pipe to bring the drying fluid into contact with the filter portion and remove moisture from the filter portion; A system for removing persistent substances comprising:

6. The method includes providing a plurality of the filter units, The plurality of filter units include A plurality of processing units connected in series with each other; a spare unit connectable to the plurality of processing units; Equipped with The removal system comprises: The system for removing persistent substances as described in claim 5, further comprising a switching means for switching the flow path of treated water so that, when a filter portion of any one of the plurality of treatment units is replaced, the spare unit is connected in series subsequent to a final treatment unit among the plurality of treatment units other than the any one of the plurality of treatment units.

7. 7. The system for removing persistent substances according to claim 5 or 6, wherein the filter unit includes a plurality of the filter parts connected in series within the storage vessel.

8. The filter unit comprises:

7. The system for removing persistent substances as described in claim 5 or 6, comprising a plurality of filter elements each having the water collection pipe, one or more of the filter sections, and the storage container as constituent units, the plurality of filter elements being arranged in parallel to one another within a housing that contains the plurality of filter elements.

9. A method for removing difficult-to-decompose substances, comprising the steps of: supplying water to be treated containing the difficult-to-decompose substances into a filter unit comprising a perforated water collection pipe, a filter section wound around the water collection pipe, the filter section having an adsorption sheet which is breathable and has graft chains to which ion exchange groups for adsorbing the difficult-to-decompose substances are attached, and a storage container for housing the filter section; and bringing the water to be treated into contact with the filter section, thereby adsorbing the difficult-to-decompose substances onto the adsorption sheet and removing them.

10. 10. The method for removing persistent substances according to claim 9, further comprising a drying step of removing moisture from the filter portion by supplying a drying fluid from the water collection pipe.

11. The method for removing persistent substances according to claim 10, further comprising an incineration step of recovering and incinerating the filter portion after the drying step.

12. the filter unit includes a plurality of processing units connected in series with each other and a spare unit connectable to the plurality of processing units, Stopping the supply of the water to be treated or the treated water to any one of the plurality of treatment units; After stopping the supply of the water to be treated or the treated water, a dry fluid is supplied from the water collection pipe to the arbitrary one of the treatment units to remove moisture from the filter section, and then the filter section from which the moisture has been removed is collected; While performing the process of removing the moisture and the process of recovering the filter portion, the spare unit is connected in series to a rear stage of the processing unit that is a last stage of the plurality of processing units other than the arbitrary processing unit, The water to be treated is supplied to the treatment unit connected downstream of any one of the treatment units, and an adsorption and removal treatment of the persistent substances in the water to be treated or the treated water is performed. The method for removing a persistent substance according to claim 9, comprising:

13. The method for removing persistent substances according to any one of claims 9 to 12, comprising treating the water to be treated having an organic fluorine compound concentration of 50,000 ng / L or less.

14. A cartridge filter device for adsorbing persistent substances according to any one of claims 1 to 3, wherein moisture is removed from the filter portion by supplying a dry fluid from the water collection pipe; A method for reducing the moisture content of a cartridge filter device, comprising: discharging the dry fluid after contact with the filter portion to the outside of the storage container through one or more openings provided in the storage container, thereby reducing the moisture content of the filter portion.

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