Substance removal method, treatment apparatus, and treatment system

Abstract

This substance removal method is used in a treatment apparatus that includes a tank for removing a substance contained in water to be treated, the method involving removing the substance from the water to be treated by: forming, in the tank, a first adsorption layer including a first adsorbent; forming, above the first adsorption layer in the tank, a second adsorption layer including a second adsorbent having a sedimentation velocity slower than that of the first adsorbent; and passing the water to be treated through the first adsorption layer and the second adsorption layer.

Description

Material removal method, treatment device and treatment system

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to material removal methods, processing devices, and processing systems.

[0002] In water purification plants, for example, water purification equipment is used to remove various substances (hereinafter simply referred to as substances) contained in raw water (hereinafter also referred to as water to be treated), such as river water or well water, to produce purified water (hereinafter also referred to as treated water) (see Patent Document 1).

[0003] JP 2018-065119 A

[0004] Here, it is desired that the water purification facility as described above efficiently removes substances contained in the water to be treated, for example.

[0005] The substance removal method disclosed herein is a substance removal method in a treatment device equipped with a tank for removing substances contained in water to be treated, in which a first adsorption layer containing a first adsorbent is formed in the tank, and a second adsorption layer containing a second adsorbent having a slower sedimentation rate than the first adsorbent is formed above the first adsorption layer in the tank, and the substances are removed from the water to be treated by passing the water to be treated through the first adsorption layer and the second adsorption layer.

[0006] According to the substance removal method, treatment device, and treatment system disclosed herein, it is possible to efficiently remove substances contained in water to be treated.

[0007] FIG. 1 is a diagram illustrating the configuration of a processing system 100 in the first embodiment. FIG. 2 is a diagram illustrating the configuration of an adsorption device 70 in the first embodiment. FIG. 3 is a diagram illustrating a substance removal method in the first embodiment. FIG. 4 is a diagram illustrating a specific example of step S3. FIG. 5 is a diagram illustrating a specific example of step S3. FIG. 6 is a diagram illustrating a specific example of step S3.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, such descriptions should not be interpreted in a limiting sense, and do not limit the subject matter described in the claims. Furthermore, various changes, substitutions, and modifications can be made without departing from the spirit and scope of the present disclosure. Furthermore, different embodiments can be combined as appropriate.

[0009] [Processing System 100 in First Embodiment] First, a configuration example of the processing system 100 in the first embodiment will be described. Fig. 1 is a diagram illustrating a configuration example of the processing system 100 in the first embodiment. Note that the positions and numbers of pumps and pipes in the following example are merely examples and are not limited to these.

[0010] The treatment system 100 is, for example, a water treatment facility that performs water purification treatment on water to be treated to produce treated water.

[0011] Specifically, as shown in FIG. 1 , the treatment system 100 includes, for example, a gritification basin 10, a receiving well 20, a mixing basin 30, a flocculation basin 40 (hereinafter also referred to as the flocculation basin 40), a sedimentation basin 50, a filtration basin 60, an adsorption device 70 (hereinafter also referred to as the treatment device 70), a purified water basin 80, a distribution basin 90, a pump P1, and a pump P2.

[0012] The pump P1 is, for example, a pump provided in a pipe connecting a river or the like to the settling basin 10. Specifically, the pump P1 supplies the water to be treated taken from the river or the like to the settling basin 10 in an amount and at a time interval designated in advance by, for example, an administrator of the treatment system 100 (hereinafter simply referred to as the administrator).

[0013] The settling basin 10 is a tank into which, for example, the treated water (treated water taken from a river, etc.) supplied by pump P1 first flows, and is a tank in which sedimentation and removal of sediment and the like contained in the treated water is performed.

[0014] The receiving well 20 is, for example, a tank that adjusts the amount of water to be treated supplied from the settling basin 10 and supplies it to the mixing basin 30.

[0015] The mixing basin 30 is, for example, a tank in which a flocculant is injected into the water to be treated supplied from the receiving well 20 .

[0016] The flocculation basin 40 is a tank that, for example, agitates the water to be treated supplied from the mixing basin 30, thereby flocculating suspended solids contained in the water to be treated supplied from the mixing basin 30 with a coagulant to form flocs.

[0017] The settling basin 50 is, for example, a tank in which flocs contained in the water to be treated supplied from the flocculation basin 40 are allowed to settle and are separated from the water to be treated.

[0018] The filtration basin 60 is a tank that filters the water to be treated supplied from the settling basin 50 by using a filter body (not shown) made of, for example, sand, gravel, or the like.

[0019] The adsorption device 70 is a water treatment device that uses an adsorbent (hereinafter simply referred to as the adsorbent) such as ion exchange resin or powdered activated carbon to remove substances (hereinafter simply referred to as the substances) such as perfluoroalkyl substances and polyfluoroalkyl substances (PFAS) contained in the water to be treated supplied from the filtration basin 60. Specifically, the adsorption device 70 removes the substances from the water to be treated supplied from the filtration basin 60 by, for example, causing the adsorbent to adsorb the substances contained in the water to be treated.

[0020] The purified water reservoir 80 is, for example, a tank that temporarily stores the treated water supplied from the adsorption device 70 (for example, the treated water after being disinfected by chlorine downstream of the adsorption device 70) and supplies it to the distribution reservoir 90.

[0021] The pump P2 is, for example, a pump provided in a pipe connecting the purified water reservoir 80 and the distributing reservoir 90. Specifically, the pump P2 supplies the untreated water (treated water) from the purified water reservoir 80 to the distributing reservoir 90 in an amount and at a time interval predetermined by, for example, an administrator.

[0022] The distributing reservoir 90 temporarily stores the water to be treated (treated water) supplied from the purified water reservoir 80, for example, and supplies it to homes and the like (not shown).

[0023] The following description will be given assuming that the adsorption device 70 is included in the treatment system 100 that performs water purification treatment on the water to be treated, but the present invention is not limited to this. Specifically, the adsorption device 70 may be directly supplied with the water to be treated (e.g., groundwater). The adsorption device 70 may remove substances contained in the directly supplied water to be treated.

[0024] [Adsorption Device 70 in First Embodiment] Next, a configuration of the adsorption device 70 in the first embodiment will be described. Fig. 2 is a diagram illustrating an example of the configuration of the adsorption device 70 in the first embodiment.

[0025] As shown in FIG. 2 , the adsorption device 70 includes, for example, a tank body 71 (hereinafter also referred to as simply the tank), a membrane 72, an adsorption layer L1 (hereinafter also referred to as the first adsorption layer) formed by an adsorbent 73 (hereinafter also referred to as the first adsorption layer), an adsorption layer L2 (hereinafter also referred to as the second adsorption layer) formed by an adsorbent 74 (hereinafter also referred to as the second adsorption material), and a membrane 75.

[0026] The tank body 71 has, for example, a hollow cylindrical shape extending along the Z direction, and is capable of accommodating the water to be treated supplied from the filtration basin 60 therein.

[0027] The membrane 72 is, for example, a membrane provided at the end (lower end) of the tank body 71 on the Z2 direction side. The membrane 75 is, for example, a membrane provided at the end (upper end) of the tank body 71 on the Z1 direction side. Specifically, each of the membranes 72 and 75 may be made of a material that can prevent the adsorbent 73 and the adsorbent 74 from leaking out of the tank body 71, and may be, for example, a filter with a pore size of approximately 0.1 mm. Note that, for example, another member (a member other than a membrane) that can prevent the adsorbent 73 and the adsorbent 74 from leaking out of the tank body 71 may be attached to at least one of the end (Z1 direction side) of the tank body 71 on the Z2 direction side.

[0028] The adsorption layer L1 is, for example, a layer formed in the tank body 71 by an adsorbent 73 such as an ion exchange resin or powdered activated carbon.

[0029] The adsorption layer L2 is a layer formed of an adsorbent 74 such as an ion exchange resin or powdered activated carbon above the adsorption layer L1 (on the Z1 direction side) in the tank body 71, for example.

[0030] Here, the adsorbent 74 forming the adsorption layer L2 is, for example, an adsorbent having a slower sedimentation rate than the adsorbent 73 forming the adsorption layer L1. That is, the adsorbent 74 is, for example, an adsorbent having the same wet density as the adsorbent 73 but a smaller particle size.

[0031] Specifically, the wet density and particle size of the adsorbent 73 are 1.05 (g / cm ３ ) and 0.7 (mm), the wet density and particle size of the adsorbent 74 are, for example, 1.05 (g / cm ３ ) and 0.675 (mm). Hereinafter, an adsorbent having the same wet density but a smaller particle size will also be simply referred to as an adsorbent having a smaller particle size.

[0032] The adsorbent 74 may be, for example, an adsorbent having a smaller specific gravity than the adsorbent 73 and therefore a slower settling rate than the adsorbent 73. The adsorbent 74 may also be, for example, an adsorbent having a smaller particle size than the adsorbent 73 and a smaller specific gravity than the adsorbent 73 and therefore a slower settling rate than the adsorbent 73.

[0033] Furthermore, the adsorbent 74 may be made of the same material as the adsorbent 73, as long as it has a slower sedimentation rate than the adsorbent 73. Specifically, each of the adsorbent 73 and the adsorbent 74 may be, for example, an ion exchange resin made of divinylbenzene-crosslinked polystyrene.

[0034] In the following description, the adsorption device 70 will be described as using two types of adsorbents (adsorbent 73 and adsorbent 74), but the present invention is not limited to this. Specifically, the adsorption device 70 may use, for example, three or more types of adsorbents that differ in at least one of particle size and specific gravity. That is, the adsorption device 70 may form, for example, three or more adsorption layers.

[0035] [Substance Removal Method in First Embodiment] Next, a substance removal method in the first embodiment will be described. Figure 3 is a diagram for explaining the substance removal method in the first embodiment.

[0036] 3, the worker forms an adsorption layer L1 containing the adsorbent 73 in the tank body 71 (step S1 in FIG. 3). Specifically, the worker forms the adsorption layer L1 in the tank body 71 by supplying the adsorbent 73 into the tank body 71 from the Z1 direction side of the tank body 71, for example.

[0037] Next, after step S1, the worker forms, for example, an adsorption layer L2 containing an adsorbent 74 having a slower settling velocity than the adsorbent 73 above the adsorption layer L1 in the tank body 71 (step S2 in FIG. 3 ). Specifically, the worker forms the adsorption layer L2 on the surface of the adsorption layer L1 in the tank body 71 by, for example, supplying the adsorbent 74 into the tank body 71 from the Z1 direction side of the tank body 71.

[0038] After step S2, the operator removes substances from the water to be treated, for example, by passing the water through the adsorption layers L1 and L2 (step S3 in FIG. 3).

[0039] [Specific Example of Step S3] Next, a specific example of step S3 will be described. Figures 4 to 6 are diagrams for explaining a specific example of step S3.

[0040] For example, when the water to be treated is passed through the adsorption layers L1 and L2 in a downward flow (hereinafter also referred to as a downward flow), the water to be treated flows into the tank body 71 through the membrane 75 (Z1 direction side), passes through the adsorption layers L2 and L1 in that order, and then flows out of the tank body 71 through the membrane 72 (Z2 direction side), as shown in FIG.

[0041] That is, in this case, for example, water is passed through adsorption layer L2 before it is passed through adsorption layer L1 in the tank body 71. Therefore, for example, a large amount of substances contained in the water to be treated is adsorbed by adsorption layer L2 (adsorbent 74) in the tank body 71. In other words, for example, the degree of contamination of adsorbent 74 in the tank body 71 becomes higher than the degree of contamination of adsorbent 73.

[0042] On the other hand, when the treated water is passed through the adsorption layers L1 and L2 in an upward flow direction, as shown in FIG. 5, the treated water flows into the tank body 71 through the membrane 72 (Z2 direction side), passes through the adsorption layers L1 and L2 in that order, and then flows out of the tank body 71 through the membrane 75 (Z1 direction side).

[0043] Specifically, in this case, the water to be treated rises in the tank body 71 while stirring up, for example, the adsorbent 73 forming the adsorption layer L1 and the adsorbent 74 forming the adsorption layer L2.

[0044] Here, if the adsorption layer is formed only by adsorbents with the same (or nearly the same) settling velocity, for example, highly contaminated adsorbents (adsorbents located on the Z2 side) and less contaminated adsorbents (adsorbents located on the Z1 side) will be rolled up in a mixed state within the tank body 71. Then, after the adsorbents are rolled up by the rising of the water to be treated, for example, the highly contaminated adsorbents and the less contaminated adsorbents will settle at the same settling velocity within the tank body 71, and an adsorption layer in which the highly contaminated adsorbents and the less contaminated adsorbents remain mixed will be formed (deposited) on the membrane 75.

[0045] In other words, if the adsorption layer is formed only by adsorbents with the same settling velocity, within the tank body 71, for example, some of the highly contaminated adsorbents will flow or accumulate near the membrane 72 (closer to the membrane 72 than the less contaminated adsorbents), resulting in a decrease in the treatment rate (the rate at which substances contained in the treated water are removed).

[0046] In contrast, the adsorption device 70 of this embodiment uses, for example, multiple types of adsorbents with different settling velocities. Specifically, the adsorption device 70 of this embodiment uses multiple types of adsorbents, including, for example, adsorbent 73 and adsorbent 74, which has a slower settling velocity than adsorbent 73. Therefore, as shown in FIG. 5 , for example, the adsorbent 73 forming the adsorption layer L1 and the adsorbent 74 forming the adsorption layer L2 are wound up in an unmixed state within the tank body 71. In other words, for example, the adsorbent 73 and the adsorbent 74 are wound up in a separated state within the tank body 71. Furthermore, after the adsorbent 73 and the adsorbent 74 are wound up by the rising of the water to be treated, as shown in FIG. 6 , for example, the adsorbent 73 settles faster than the adsorbent 74 within the tank body 71. Therefore, the adsorption layer L1 containing the adsorbent 73 is re-formed on the upper surface of the membrane 75, and then the adsorption layer L2 containing the adsorbent 74 is re-formed on the surface of the adsorption layer L1. In other words, within the tank body 71, for example, an adsorption layer L1 containing the adsorbent 73 and an adsorption layer L2 containing the adsorbent 74 are formed on the upper surface of the membrane 75 in a separated state.

[0047] That is, even when the water to be treated flows upward through the adsorption layers L1 and L2, the adsorption device 70 in this embodiment can prevent the low-contamination adsorbent 73 from mixing with the high-contamination adsorbent 74. In other words, in this case, the adsorption device 70 can prevent the high-contamination adsorbent 74 from flowing or accumulating near the membrane 72 (closer to the membrane 72 than the low-contamination adsorbent 73).

[0048] Therefore, the adsorption device 70 in this embodiment can prevent the adsorbents 73 and 74 from mixing with each other, even when the water to be treated flows upward through the adsorption layers L1 and L2, and can suppress a decrease in the treatment rate (the rate at which substances contained in the water to be treated are removed). Therefore, the adsorption device 70 in this embodiment can efficiently remove substances contained in the water to be treated, for example.

[0049] In addition, the adsorption device 70 in this embodiment can suppress a decrease in the treatment rate (the rate at which substances contained in the water to be treated) even when, for example, the water to be treated is passed through the adsorption layers L1 and L2 in a downward flow, and then cleaning (backwashing) the adsorption layers L1 and L2 is performed by passing cleaning water through the adsorption layers L1 and L2 in an upward flow.

[0050] Specifically, in this case, as shown in FIG. 5 , the cleaning water flows into the tank body 71 from the membrane 72 (Z2 direction side), and is passed through the adsorption layers L1 and L2 in that order to clean (backwash) the adsorption layers L1 and L2, and then flows out of the tank body 71 from the membrane 75 (Z1 direction side).

[0051] Therefore, in this case as well, for example, the adsorbent 73 forming the adsorption layer L1 and the adsorbent 74 forming the adsorption layer L2 are wound up in a separated state inside the tank body 71. After the inflow of cleaning water into the tank body 71 is completed, for example, the adsorption layer L1 is formed again on the upper surface of the membrane 75 inside the tank body 71, and then the adsorption layer L2 is formed again on the surface of the adsorption layer L1, as shown in FIG.

[0052] Therefore, the adsorption device 70 of this embodiment can prevent the adsorbent 73 from mixing with the adsorbent 74, even when, for example, cleaning (backwashing) the adsorption layers L1 and L2 by passing cleaning water through them in an upward flow, and can suppress a decrease in the treatment rate (the rate at which substances contained in the water to be treated are removed). Therefore, the adsorption device 70 of this embodiment can efficiently remove substances contained in the water to be treated, for example.

[0053] Furthermore, in the adsorption device 70 of this embodiment, for example, when the treated water is passed through the adsorption layers L1 and L2 in a downward flow, even if the adsorbent material 73 forming the adsorption layer L1 and the adsorbent material 74 forming the adsorption layer L2 are partially lifted up due to the generation of bubbles, etc., it is possible to suppress a decrease in the treatment rate (the rate at which substances contained in the treated water are removed).

[0054] In this manner, the adsorption device 70 in this embodiment forms, for example, an adsorption layer L1 containing the adsorbent 73 in the tank body 71. Then, the adsorption device 70 in this embodiment forms, for example, an adsorption layer L2 containing the adsorbent 74 having a slower settling velocity than the adsorbent 73 above the adsorption layer L1 in the tank body 71. Furthermore, the adsorption device 70 removes substances from the water to be treated by, for example, passing the water to be treated through the adsorption layers L1 and L2.

[0055] Specifically, the adsorbent 74 is an adsorbent having at least one of a particle size and a specific gravity smaller than those of the adsorbent 73, for example.

[0056] The adsorption device 70 also removes substances from the water to be treated by, for example, passing the water in a downward flow through the adsorption layer L2 and then the adsorption layer L1.

[0057] The adsorption device 70 also cleans (backwashes) the adsorbent 73 and the adsorbent 74 by, for example, passing cleaning water through the adsorption layer L1 and then the adsorption layer L2 in an upward flow.

[0058] The adsorption device 70 also removes substances from the water to be treated by, for example, passing the water through the adsorption bed L1 and then the adsorption bed L2 in an upward flow manner.

[0059] As a result, the adsorption device 70 in this embodiment can prevent mixing of the adsorbent 73 and the adsorbent 74, and suppress a decrease in the treatment rate, even when, for example, the water to be treated is passed through the adsorption layers L1 and L2 in an upward flow or when the adsorption layers L1 and L2 are cleaned (backwashed) with backwash water. Therefore, the adsorption device 70 in this embodiment can efficiently remove substances contained in the water to be treated, for example.

[0060] 10: Grit chamber 20: Receiving well 30: Mixing chamber 40: Flocculation chamber 50: Sedimentation chamber 60: Filtration chamber 70: Adsorption device 71: Tank body 72: Membrane 73: Adsorbent 74: Adsorbent 75: Membrane 80: Clean water reservoir 90: Distribution reservoir L1: Adsorption layer L2: Adsorption layer P1: Pump P2: Pump

Claims

1. A substance removal method in a treatment device equipped with a tank for removing substances contained in water to be treated, comprising: forming a first adsorption layer containing a first adsorbent within the tank; forming a second adsorption layer containing a second adsorbent having a slower sedimentation rate than the first adsorbent above the first adsorption layer within the tank; and passing the water to be treated through the first adsorption layer and the second adsorption layer to remove the substances from the water to be treated.

2. The substance removal method according to claim 1, wherein the second adsorbent has at least one of a particle size and a specific gravity smaller than that of the first adsorbent.

3. A substance removal method as described in claim 1, wherein in the removal step, the substance is removed from the treated water by passing the treated water downward through the second adsorption layer and then the first adsorption layer.

4. A substance removal method as described in claim 2, further comprising passing cleaning water through the first adsorption layer and then the second adsorption layer in an upward flow, thereby cleaning the first adsorbent and the second adsorbent, respectively.

5. A substance removal method as described in claim 1, wherein in the removal step, the substance is removed from the treated water by passing the treated water through the first adsorption layer and then the second adsorption layer in an upward flow manner.

6. A treatment device comprising a tank for removing substances contained in water to be treated, wherein a first adsorption layer containing a first adsorbent is formed inside the tank, and a second adsorption layer containing a second adsorbent having a slower sedimentation rate than the first adsorbent is formed above the first adsorption layer inside the tank, and wherein the substances are removed from the water to be treated by passing the water to be treated through the first adsorption layer and the second adsorption layer.

7. A treatment system having one or more treatment devices that perform various types of treatment, wherein at least one of the one or more treatment devices is provided with a tank that removes substances contained in the water to be treated, wherein the tank has: a first adsorption layer containing a first adsorbent formed therein; and a second adsorption layer containing a second adsorbent having a slower sedimentation rate than the first adsorbent formed above the first adsorption layer inside the tank; and the substances are removed from the water to be treated by passing the water to be treated through the first adsorption layer and the second adsorption layer.

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