Manganese removal system and cleaning method

Abstract

This invention provides a manganese removal system and cleaning method that enable efficient cleaning of manganese removal equipment. [Solution] A manganese removal system comprising: a tank having a first catalyst layer containing a manganese catalyst formed inside, and a tank through which water to be treated is passed in an upward flow to the first catalyst layer to remove manganese from the water to be treated, the tank having a first membrane on the outlet side of the water to be treated, and a second catalyst layer being formed on the surface of the first membrane on the side of the first catalyst layer by the adhesion of manganese catalyst that rises inside the tank as water to be treated is supplied into the tank, the system comprising: a cleaning device for cleaning the second catalyst layer, and a control device for controlling the cleaning by the cleaning device, the control device performing cleaning so that the pressure loss when water to be treated that has passed through the first catalyst layer is passed in an upward flow to the second catalyst layer is within a predetermined range.

Description

Technical Field

[0001] The present disclosure relates to a manganese removal system and a cleaning method.

Background Art

[0002] In a water purification plant, for example, water purification equipment for removing suspended solids (SS: Suspended Solids) contained in raw water such as river water or well water (hereinafter also referred to as treated water) is used. Specifically, in such water purification equipment, for example, by mixing a flocculant into the treated water, the suspended solids contained in the treated water are flocculated and removed by precipitation. Further, in the above water purification equipment, for example, manganese contained in the treated water is removed. As a result, in the water purification plant, for example, it becomes possible to generate purified water (hereinafter also referred to as treated water) from the treated water (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the water purification equipment as described above, for example, it is desired to efficiently clean a device (hereinafter also referred to as a manganese removal device) for removing manganese contained in the treated water.

Means for Solving the Problems

[0005] The manganese removal system in this disclosure has a tank in which a first catalyst layer containing a manganese catalyst is formed internally, and manganese is removed from the water to be treated by passing the water to be treated, which contains manganese, through the first catalyst layer in an upward flow, the tank has a first membrane on the outlet side of the water to be treated, and a second catalyst layer is formed on the surface of the first membrane on the side of the first catalyst layer by the manganese catalyst that rises inside the tank as the water to be treated is supplied into the tank, the manganese removal system has a cleaning device for cleaning the second catalyst layer, and a control device for controlling the cleaning by the cleaning device, the control device performs the cleaning such that the pressure loss when the water to be treated that has passed through the first catalyst layer is passed into the second catalyst layer in an upward flow is within a predetermined range. [Effects of the Invention]

[0006] The manganese removal system and cleaning method described herein enable efficient cleaning of the manganese removal apparatus. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a diagram illustrating an example of the configuration of the water treatment system 100 in the first embodiment. [Figure 2] Figure 2 illustrates an example of the configuration of the manganese removal device 3 in the first embodiment. [Figure 3] Figure 3 is a diagram illustrating the hardware configuration of the control device 10. [Figure 4] Figure 4 is a flowchart illustrating the water purification method in the first embodiment. [Figure 5] Figure 5 is a flowchart illustrating the details of the cleaning method in the first embodiment. [Figure 6] Figure 6 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 7]Figure 7 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 8] Figure 8 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 9] Figure 9 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 10] Figure 10 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 11] Figure 11 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 12] Figure 12 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 13] Figure 13 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 14] Figure 14 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 15] Figure 15 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 16] Figure 16 is a diagram illustrating the details of the cleaning method in the first embodiment. [Figure 17] Figure 17 illustrates the first modified example. [Modes for carrying out the invention]

[0008] Embodiments of this disclosure will be described below with reference to the drawings. However, this description should not be interpreted as limiting, and will 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 this disclosure. Different embodiments can also be combined as appropriate.

[0009] [Water treatment system 100 in the first embodiment] First, a configuration example of the water treatment system 100 in the first embodiment will be described. FIGS. 1 and 2 are diagrams for explaining a configuration example of the water treatment system 100 in the first embodiment. Note that the positions and numbers of pumps and pipes in the following examples are just examples and are not limited thereto.

[0010] The water treatment system 100 (hereinafter also referred to as the manganese removal system 100) has, for example, one or more water purification facilities arranged in a water purification plant.

[0011] Specifically, as shown in FIG. 1, the water treatment system 100 has, for example, a coagulation mixing tank 1, a filtration device 2, a manganese removal device 3, a pump P1, a pump P2, a pump P3, a pump P11, and a pump P12. Hereinafter, the coagulation mixing tank 1, the filtration device 2, and the manganese removal device 3 are collectively referred to simply as the coagulation mixing tank 1, etc.

[0012] The pump P1 is arranged, for example, in a line L1 that communicates a raw water tank (not shown) and the coagulation mixing tank 1. And the pump P1 supplies, for example, the water to be treated from the raw water tank to the coagulation mixing tank 1.

[0013] The pump P11 is arranged, for example, in a line L11 that communicates a storage tank 7a storing a coagulant and the line L1. And the pump P11 adds, for example, a coagulant to the water to be treated supplied from the raw water tank by the pump P1. Specifically, the pump P11 adds, for example, the coagulant stored in the storage tank 7a to the water to be treated. Hereinafter, the pump P11 and the line L11 are collectively referred to as an addition device AD1.

[0014] The coagulation mixing tank 1 agitates the water to be treated after the coagulant is added by the pump P11, thereby aggregating the suspended substances contained in the water to be treated with the coagulant to form flocs. And the coagulation mixing tank 1 separates the formed flocs from the water to be treated, for example, by precipitating them.

[0015] The following description will assume that the water treatment system 100 has a coagulation and mixing tank 1, but it is not limited to this. Specifically, the water treatment system 100 may, for example, have, instead of the coagulation and mixing tank 1, a tank (not shown) for injecting a coagulant into the water to be treated, a tank (not shown) for forming flocs by stirring the water to be treated into which the coagulant has been injected, and a tank (not shown) for separating the flocs from the water to be treated by allowing them to settle.

[0016] Pump P2 is positioned, for example, in a line L2 that connects the coagulation and mixing tank 1 and the filtration device 2. Pump P2 supplies the water to be treated from the coagulation and mixing tank 1 to the filtration device 2.

[0017] The filtration device 2 filters the water to be treated using, for example, a membrane (not shown) that constitutes the filtration device 2. The membrane that constitutes the filtration device 2 is, for example, a ceramic or polymer microfiltration membrane (MF membrane) or an ultrafiltration membrane (UF membrane). The filtration device 2 then captures, for example, suspended solids contained in the water to be treated supplied from the coagulation and mixing tank 1.

[0018] Pump P3 is located, for example, in line L3 that connects the filtration device 2 and the manganese removal device 3. Pump P3 supplies the water to be treated from the filtration device 2 to the manganese removal device 3.

[0019] Pump P12 is located in a line L12 that connects, for example, a storage tank 7b containing an oxidizing agent to the manganese removal device 3. The oxidizing agent may be, for example, sodium hypochlorite. Alternatively, the oxidizing agent may be, for example, liquefied chlorine or potassium permanganate. Pump P12 then adds the oxidizing agent to the water to be treated (the water to be treated supplied from the filtration device 2 by pump P3) that flows into the manganese removal device 3. Specifically, pump P12 adds the oxidizing agent stored in the storage tank 7b to the water to be treated. Hereinafter, pump P12 and line L12 will be collectively referred to as the addition device AD2.

[0020] The manganese removal device 3 is a tank that removes dissolved manganese (manganese ions) contained in the water to be treated, supplied from the filtration device 2 by, for example, the pump P3. Hereafter, dissolved manganese will also be simply referred to as manganese.

[0021] Specifically, the manganese removal device 3, for example, oxidizes the manganese contained in the water to be treated, supplied from the filtration device 2 by the pump P3, using an oxidizing agent to solidify it. Then, the manganese removal device 3 separates the manganese oxide (solidified manganese) produced by the oxidation of manganese from the water to be treated.

[0022] Subsequently, the treated water from which manganese has been removed by the manganese removal device 3 is supplied to a water purification reservoir (not shown) via, for example, line L4. Line L4 is, for example, a line connecting the manganese removal device 3 and the water purification reservoir. Specifically, the treated water from which manganese has been removed is supplied from the manganese removal device 3 to the water purification reservoir by, for example, a pump (not shown) located in line L4.

[0023] [Manganese removal device 3 in the first embodiment] Next, the configuration of the manganese removal device 3 will be described. Figure 2 is a diagram illustrating an example of the configuration of the manganese removal device 3 in the first embodiment.

[0024] As shown in Figure 2, the manganese removal device 3 includes, for example, a tank body 31, a membrane 32 (hereinafter also referred to as the first membrane 32) provided on the inflow side of the water to be treated W, a fluidized bed 33 containing a manganese catalyst (hereinafter also referred to as the first catalyst bed 33), and a membrane 34 (hereinafter also referred to as the second membrane 34) provided on the outflow side of the water to be treated W. The manganese catalyst may be, for example, manganese oxide.

[0025] The tank body 31 has a shape that extends along the Z-axis direction, for example, and is capable of containing the water to be treated W supplied from the filtration device 2 by the pump P3. Specifically, the water to be treated W supplied from the filtration device 2 by the pump P3 flows into the tank body 31 from the Z2 direction (downward direction), as shown by the solid arrows in Figure 2, for example, and then rises inside the tank body 31 due to an upward flow toward the Z1 direction (upward direction).

[0026] The membrane 32 is, for example, a membrane attached to the end of the tank body 31 on the Z2 direction side (the side where the treated water W flows in). Specifically, the membrane 32 may be, for example, a membrane similar to the membrane of the filtration device 2. The treated water W supplied from the filtration device 2 by the pump P3 flows into the tank body 31 by passing through the membrane 32, for example. The membrane 32 may be, for example, a ceramic or polymer membrane.

[0027] In other words, the membrane 32 allows the water to be treated W supplied from the filtration device 2 by the pump P3 to flow into the tank body 31, and prevents manganese catalyst particles forming the fluidized bed 33 (for example, manganese catalyst particles whose particle size has been reduced by contact with other manganese catalysts) from flowing out of the tank body 31 from the Z2 direction side (lower end side) to the outside (for example, line L3).

[0028] Then, an oxidizing agent is added to the water to be treated W (water to be treated while passing through the fluidized bed 33) that has passed through the membrane 32 and flowed into the tank body 31, for example, by a pump P12. In other words, the pump P12 adds an oxidizing agent to the water to be treated that has flowed into the tank body 31, for example.

[0029] In other words, instead of adding the oxidizing agent to the water to be treated W flowing through the upstream equipment (e.g., line L3) of the manganese removal device 3, the pump P12 adds the oxidizing agent to the water to be treated W after it has flowed into the manganese removal device 3.

[0030] As a result, the water treatment system 100 in this embodiment can prevent, for example, the oxidation reaction of manganese contained in the water to be treated W from occurring within the membrane 32. Therefore, the water treatment system 100 can prevent, for example, the occurrence of fouling in the membrane 32. Furthermore, the water treatment system 100 in this embodiment can also prevent, for example, the oxidation reaction of manganese contained in the water to be treated W from occurring within the line L3. Therefore, the water treatment system 100 can also prevent, for example, the occurrence of blockage in the line L3.

[0031] Returning to Figure 2, the fluidized bed 33 is, for example, a fluidized bed of manganese catalyst formed within the tank body 31. Specifically, the manganese catalyst particles forming the fluidized bed 33 are, for example, particles having a density and particle size (terminal settling velocity) that allows the fluidized bed 33 to be maintained even when the water to be treated W rises within the tank body 31.

[0032] Then, the water to be treated W that flows into the tank body 31 is, for example, treated with an oxidizing agent by the pump P12 and rises upward to the fluidized bed 33. Subsequently, the fluidized bed 33 oxidizes the manganese contained in the water to be treated W that has risen to the height of the fluidized bed 33 within the tank body 31 to produce manganese oxide, and also captures the produced manganese oxide.

[0033] In other words, the fluidized bed 33 captures manganese contained in the water to be treated W by solidifying the manganese contained in the water to be treated W that has risen to the height of the fluidized bed 33 within the tank body 31.

[0034] Specifically, in the fluidized bed 33, for example, catalytic oxidation of manganese contained in the treated water W occurs on the surface of the manganese catalyst forming the fluidized bed 33. Then, in the fluidized bed 33, for example, manganese oxide precipitates on the surface of the manganese catalyst.

[0035] The membrane 34 is, for example, a membrane attached to the Z1 direction side (the outlet side of the treated water W) of the tank body 31. Specifically, the membrane 34 may be, for example, a membrane similar to the membrane of the filtration device 2. The treated water W that has passed through the fluidized bed 33 then rises further inside the tank body 31, for example, and then flows out of the tank body 31 (for example, line L4) by passing through the membrane 34. The membrane 34 may be, for example, a ceramic or polymer membrane. That is, the membrane 34 may be made of a different material than the membrane 32, or it may be made of the same material as the membrane 32.

[0036] Here, among the manganese catalysts forming the fluidized bed 33, the manganese catalyst particles whose particle size has been reduced by contact with other manganese catalysts have a lower terminal sedimentation velocity compared to, for example, manganese catalyst particles whose particle size has not been reduced. Similarly, manganese oxide particles that precipitate on the surface of the manganese catalyst and are further detached from the surface of the manganese catalyst by contact with other manganese catalysts have a lower terminal sedimentation velocity compared to, for example, manganese catalyst particles whose particle size has not been reduced. Therefore, the manganese catalyst particles with reduced particle size and the manganese oxide particles detached from the surface of the manganese catalyst rise together with the water to be treated W in the tank body 31, for example. Then, the manganese catalyst particles with reduced particle size and the manganese oxide particles detached from the surface of the manganese catalyst adhere to, for example, the Z2-direction surface of the film 34, forming a coating layer 35 (hereinafter also referred to as the second catalyst layer 35) that coats the Z2-direction surface of the film 34. Hereinafter, the manganese catalyst and manganese oxide that form the coating layer 35 will be collectively referred to simply as manganese catalyst, etc.

[0037] The coating layer 35 then oxidizes, for example, the manganese contained in the water to be treated W that has risen through the tank body 31 to the coating layer 35.

[0038] In other words, the coating layer 35 is a layer that enables the solidification of manganese even if, for example, manganese that was not solidified in the fluidized bed 33 is contained in the water to be treated W.

[0039] Specifically, in the coating layer 35, for example, catalytic oxidation of manganese contained in the treated water W occurs on the surface of the manganese catalyst forming the coating layer 35, and manganese oxide precipitates. In other words, in the coating layer 35, for example, catalytic oxidation of manganese that was not catalytically oxidized in the fluidized bed 33 occurs, and manganese oxide precipitates.

[0040] Subsequently, the water to be treated W, having passed through the coating layer 35, flows out of the tank body 31 (for example, line L4) by further passing through, for example, the membrane 34. Meanwhile, manganese contained in the water to be treated W (manganese oxide solidified in the fluidized bed 33 or the coating layer 35) is removed (separated) from the water to be treated W by, for example, the membrane 34.

[0041] As a result, the manganese removal device 3 in this embodiment can remove manganese contained in the water to be treated W that flows into the tank body 31 to a higher degree. Therefore, the manganese removal device 3 in this embodiment can prevent the oxidation reaction of manganese contained in the water to be treated W from occurring within the membrane 34. Consequently, the manganese removal device 3 in this embodiment can prevent the occurrence of fouling in the membrane 34.

[0042] Thus, the water treatment system 100 in this embodiment includes, for example, an additive device AD2 for adding an oxidizing agent to the water to be treated W containing manganese, and a manganese removal device 3 in which a fluidized bed 33 containing a manganese catalyst is formed, and the water to be treated W to which the oxidizing agent has been added is passed through the fluidized bed 33 by an upward flow to remove manganese from the water to be treated W. The additive device AD2, for example, adds the oxidizing agent to the water to be treated W within the manganese removal device 3.

[0043] As a result, the water treatment system 100 in this embodiment can prevent, for example, the oxidation reaction of manganese contained in the water to be treated W from occurring within the membrane 32. Therefore, the water treatment system 100 in this embodiment can prevent, for example, the occurrence of fouling in the membrane 32. Furthermore, the water treatment system 100 in this embodiment can also prevent, for example, the oxidation reaction of manganese contained in the water to be treated W from occurring in line L3. Therefore, the water treatment system 100 in this embodiment can also prevent, for example, the occurrence of blockage in line L3.

[0044] Furthermore, the manganese removal device 3 in this embodiment has, for example, a membrane 32 on the inflow side of the water to be treated W.

[0045] As a result, the manganese removal device 3 in this embodiment can prevent, for example, the manganese catalyst forming the fluidized bed 33 from flowing out of the tank body 31 to the outside on the Z2 side (lower end side). Furthermore, the manganese removal device 3 in this embodiment can control, for example, the inflow of the water to be treated W into the tank body 31 to occur uniformly in the XY plane, and furthermore, it can control the upward flow of the water to be treated W within the tank body 31 to occur uniformly in the XY plane. Therefore, the manganese removal device 3 in this embodiment can, for example, equalize the residence time of the water to be treated W within the tank body 31, and can suppress the generation of manganese that has not undergone sufficient oxidation (i.e., the generation of uneven reaction).

[0046] Furthermore, the manganese removal device 3 in this embodiment has, for example, a membrane 34 on the outlet side of the water to be treated W.

[0047] As a result, the manganese removal device 3 in this embodiment can prevent, for example, the manganese catalyst forming the fluidized bed 33 from flowing out of the tank body 31 to the outside in the Z1 direction (upper end side).

[0048] In particular, when miniaturizing the device while maintaining the manganese removal capacity contained in the treated water W, the manganese removal device 3 needs to reduce the size of the manganese catalyst particles that form the fluidized bed 33. However, when the size of the manganese catalyst particles that form the fluidized bed 33 is reduced, the terminal settling velocity of the manganese catalyst particles that form the fluidized bed 33 decreases, which increases the risk of these particles flowing out of the tank body 31 (outside in the Z1 direction). Therefore, in the manganese removal device 3 of this embodiment, by providing a membrane 34 on the outlet side of the treated water W, it is possible not only to maintain the manganese removal capacity and miniaturize the device, but also to prevent the manganese catalyst that forms the fluidized bed 33 (including manganese catalysts whose particle size has been reduced by contact with other manganese catalysts) from flowing out of the tank body 31.

[0049] Furthermore, in the manganese removal device 3 of this embodiment, a coating layer 35 is formed on the surface of the membrane 34 on the fluidized bed 33 side by, for example, the adhesion of a manganese catalyst that has risen within the manganese removal device 3. The manganese removal device 3 then removes manganese from the water to be treated W that has passed through the fluidized bed 33 by, for example, passing the water to be treated W that has passed through the fluidized bed 33 through the coating layer 35 in an upward flow.

[0050] As a result, the manganese removal device 3 in this embodiment can remove manganese even if it is present in the treated water W that could not be removed in the fluidized bed 33. Therefore, the manganese removal device 3 in this embodiment can remove manganese more effectively from the treated water W that flows into the tank body 31.

[0051] Furthermore, the manganese removal device 3 in this embodiment can, for example, more effectively remove manganese contained in the water to be treated W that flows into the tank body 31, thereby preventing the oxidation reaction of manganese contained in the water to be treated W from occurring within the membrane 34. Therefore, the manganese removal device 3 in this embodiment can, for example, prevent the occurrence of fouling in the membrane 34.

[0052] In the above example, the case where the manganese removal device 3 is a single tank was described, but it is not limited to this. Specifically, the manganese removal device 3 may have, for example, a tank having a membrane 32 and a fluidized bed 33 inside (hereinafter also referred to as the first tank) and a tank having a membrane 34 inside (hereinafter also referred to as the second tank). In this case, the treated water W discharged from the first tank (the treated water W after manganese removal in the fluidized bed 33) may be supplied to the second tank via, for example, a line (not shown) connecting the first tank and the second tank.

[0053] Returning to Figure 1, the water treatment system 100 further includes, for example, a pump P21 and a control device 10.

[0054] Pump P21 is located in a line L21 that connects, for example, a storage tank (not shown) for storing washing water and the manganese removal device 3 (tank body 31). Pump P21 then cleans the manganese removal device 3 by, for example, supplying washing water from the storage tank to the manganese removal device 3. The washing water may also be, for example, a portion of the water to be treated W supplied from the manganese removal device 3 to the water purification reservoir via line L4.

[0055] The control device 10 performs, for example, control over the execution of cleaning in the manganese removal device 3 (hereinafter also referred to as cleaning control). Specifically, the control device 10 controls the timing of cleaning in the manganese removal device 3 by, for example, adjusting the frequency of an inverter (not shown) attached to the motor (not shown) of the pump P21. The configuration of the control device 10 will be described below.

[0056] [Control device 10 in the first embodiment] Figure 3 is a diagram illustrating the hardware configuration of the control device 10.

[0057] As shown in Figure 3, the control device 10 is, for example, an electronic device having an electronic circuit. Specifically, the control device 10 is a computer device having, for example, a CPU 101 which is a processor, a memory 102, a communication device 103, and a storage medium 104. Each part is connected to the others via, for example, a bus 105.

[0058] The storage medium 104 has, for example, a program storage area (not shown) for storing a program 110 for performing cleaning control. The storage medium 104 also has, for example, an information storage area 130 for storing information used when performing cleaning control. The storage medium 104 may be, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0059] The CPU 101 performs cleaning control, for example, by executing a program 110 loaded from the storage medium 104 into the memory 102.

[0060] The communication device 103 accesses, for example, an operating terminal (not shown) where an administrator inputs necessary information via a network (not shown), such as the Internet.

[0061] The control device 10 may, for example, have an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). Alternatively, the control device 10 may have, for example, a PIC (Peripheral Interface Controller). Furthermore, the cleaning control may be performed, for example, by an FPGA or ASIC.

[0062] Furthermore, the control device 10 may, for example, in addition to cleaning control, perform control to adjust the frequency of inverters (not shown) attached to the motors (not shown) of pumps P1, P2, P3, P11, and P12, and control the opening and closing of valves (not shown) provided in lines L1, L2, L3, L4, L11, and L12, thereby sequentially supplying treated water W to each of the coagulation mixing tanks 1, etc., to produce treated water (hereinafter also referred to as purified water production control). The following will describe the case in which the control device 10 also performs purified water production control.

[0063] [Method for producing purified water in the first embodiment] Next, the method for producing purified water in the first embodiment will be described. Figure 4 is a flowchart illustrating the method for producing purified water in the first embodiment.

[0064] As shown in Figure 4, pump P11 adds a coagulant to the water to be treated W (water to be treated supplied from the raw water tank) flowing through line L1 (step S1 in Figure 4).

[0065] Then, the coagulation mixing tank 1 stirs the water to be treated W after the coagulant has been added in step S1, for example, by coagulating the suspended solids contained in the water to be treated W with the coagulant to form flocs (step S2 in Figure 4).

[0066] Subsequently, the coagulation and mixing tank 1 separates the flocs formed in step S2 from the treated water W by, for example, allowing them to settle (step S3 in Figure 4).

[0067] Next, pump P12 adds an oxidizing agent to the treated water W after the flocs have been separated in step S3 (the treated water W after the suspended solids have been removed in the filtration device 2) (step S4 in Figure 4). Specifically, pump P12 adds an oxidizing agent to the treated water W after it has flowed into the manganese removal device 3 (tank body 31).

[0068] Then, the manganese removal device 3 solidifies the manganese contained in the water to be treated W by passing the water to be treated W, after the oxidizing agent has been added in step S4, through the fluidized bed 33 (step S5 in Figure 4).

[0069] Specifically, the manganese removal device 3 solidifies the manganese contained in the treated water W after the oxidizing agent has been added, for example.

[0070] More specifically, the manganese removal device 3 precipitates manganese oxide by causing catalytic oxidation of manganese contained in the water to be treated W on the surface of the manganese catalyst forming the fluidized bed 33, for example.

[0071] Subsequently, the manganese removal device 3 solidifies the manganese contained in the water to be treated W by passing the water to be treated W, which has passed through the fluidized bed 33 in step S5, through the coating layer 35 (step S6 in Figure 4).

[0072] Specifically, the manganese removal device 3 solidifies the manganese contained in the water to be treated W after it has passed through the fluidized bed 33 by oxidation.

[0073] More specifically, the manganese removal device 3 generates catalytic oxidation of manganese contained in the water to be treated W on the surface of a manganese catalyst, for example, that forms the coating layer 35, thereby precipitating manganese oxide.

[0074] Then, the manganese removal device 3, for example, in step S6, discharges the water to be treated W that has passed through the coating layer 35 from inside the manganese removal device 3, and removes the manganese oxide contained in the water to be treated W from the water to be treated W (step S7 in Figure 4).

[0075] Specifically, the manganese removal device 3 removes solidified manganese oxide (manganese oxide deposited and detached from the surface of the manganese catalyst) in the fluidized bed 33 or coating layer 35 from the water to be treated W using a film 34.

[0076] Subsequently, the treated water supplied from the manganese removal device 3 is supplied to downstream facilities such as a water purification reservoir.

[0077] [Outline of the cleaning method in the first embodiment] Next, we will describe the general outline of the cleaning method in the first embodiment. The following description will assume that the control device 10 is the primary entity performing the cleaning method; however, the cleaning method may also be performed manually by an administrator, for example. Furthermore, the following description will assume that the cleaning method in the first embodiment is performed during the execution of the water purification method described in Figure 4.

[0078] The control device 10 determines, for example, at regular intervals such as every 10 minutes, whether the current timing is the timing to perform cleaning of the manganese removal device 3 (hereinafter also simply referred to as the execution timing).

[0079] Specifically, the control device 10 acquires (calculates), for example, the pressure loss (hereinafter also referred to as the first pressure loss) when the water to be treated W that has passed through the fluidized bed 33 is passed through the coating layer 35. More specifically, the control device 10 acquires, for example, the difference (film differential pressure) between the pressure on the upstream side of the coating layer 35 (hereinafter also referred to as the first pressure) and the pressure on the downstream side of the coating layer 35 (hereinafter also referred to as the second pressure). The first pressure may be, for example, the pressure measured by a pressure gauge (not shown) installed downstream of the pump P3 in line L3 or upstream of the coating layer 35 in the manganese removal device 3. The second pressure may be, for example, the pressure measured by a pressure gauge (not shown) installed in line L4. Then, if the control device 10 determines, for example, that the acquired first pressure loss is greater than or equal to a predetermined threshold (hereinafter also referred to as the first threshold), it determines that the current timing is the timing to execute cleaning of the manganese removal device 3. On the other hand, if, for example, the acquired first pressure loss is determined to be less than the first threshold, the control device 10 determines that the current timing is not the timing for the manganese removal device 3 to perform cleaning.

[0080] For example, if the control device 10 determines that the current timing is the time to perform cleaning of the manganese removal device 3, it determines a cleaning method for the manganese removal device 3 (in other words, a method for peeling off a portion of the coating layer 35 from the film 34).

[0081] Specifically, the control device 10 selects, for example, a cleaning method for the manganese removal device 3 from a plurality of cleaning methods. The plurality of cleaning methods may include, for example, the first cleaning method and the second cleaning method described later. Furthermore, the control device 10 may, for example, make the decision on the cleaning method for the manganese removal device 3 before the execution timing.

[0082] Subsequently, the pump P21 cleans the manganese removal device 3 (tank body 31) according to a cleaning method determined by the control device 10, for example.

[0083] In other words, the coating layer 35 generated in the manganese removal device 3 can remove manganese contained in the water to be treated W that has passed through the fluidized bed 33 (in other words, manganese that could not be removed in the fluidized bed 33). However, depending on the thickness in the Z-axis direction, the pressure loss (first pressure loss) when the water to be treated W passes through the coating layer 35 may increase, which may cause a decrease in the amount of water to be treated W that passes through the manganese removal device 3 (amount of water that passes through per unit time).

[0084] Therefore, if the control device 10 determines, for example, that the first pressure loss is greater than or equal to the first threshold, it cleans the manganese removal device 3 within a range in which the first pressure loss does not fall below another threshold (hereinafter also referred to as the second threshold) that is smaller than the first threshold. The second threshold is, for example, a predetermined threshold, which is the first pressure loss when the thickness of the coating layer 35 is the minimum thickness required for manganese removal.

[0085] This allows the control device 10 to clean the manganese removal device 3, for example, so that the thickness of the coating layer 35 is reduced to a level that does not fall below the minimum thickness required for manganese removal.

[0086] [Details of the cleaning method in the first embodiment] Next, the details of the cleaning method in the first embodiment will be described. Figure 5 is a flowchart illustrating the details of the cleaning method in the first embodiment. Figures 6 to 16 are diagrams illustrating the details of the cleaning method in the first embodiment.

[0087] As shown in Figure 5, the control device 10 determines, for example, the next cleaning method (the next cleaning method for the manganese removal device 3) at a predetermined timing (step S21 in Figure 5). The predetermined timing may be, for example, a timing predetermined by the administrator. Specifically, the first predetermined timing may be, for example, the timing after a predetermined time has elapsed since the start of the water purification process. The second and subsequent predetermined timings may be, for example, the timing after step S24 or step S27 described later has been executed (for example, 5 minutes after step S24 or step S27 described later has been executed).

[0088] More specifically, the control device 10, for example, acquires (calculates) a first pressure loss when the water to be treated W that has passed through the fluidized bed 33 is passed through the coating layer 35 at a predetermined timing. Then, if the control device 10 determines, for example, that the acquired first pressure loss is greater than or equal to a second threshold and less than a predetermined threshold (hereinafter also referred to as the third threshold), it selects the first cleaning method as the next cleaning method. The first cleaning method is, for example, a method of cleaning the manganese removal device 3 using the water to be treated W in the tank body 31. In other words, the first cleaning method is, for example, a method of cleaning the manganese removal device 3 without using cleaning water. The third threshold is, for example, a threshold that is greater than the second threshold and less than the first threshold. On the other hand, if the control device 10 determines, for example, that the acquired first pressure loss is greater than or equal to the third threshold, it selects the second cleaning method as the next cleaning method. The second cleaning method is, for example, a method of cleaning the manganese removal device 3 using cleaning water.

[0089] In other words, for example, if the control device 10 determines that the acquired first pressure loss is greater than or equal to the third threshold, it selects a second cleaning method, which has a stronger cleaning intensity than the first cleaning method, as the next cleaning method. On the other hand, for example, if the control device 10 determines that the acquired first pressure loss is less than the third threshold, it selects a first cleaning method, which can reduce the time required to clean the manganese removal device 3 and the cost required to operate the pump P21 compared to when the second cleaning method is performed, as the next cleaning method.

[0090] As a result, the control device 10 can, for example, select the cleaning method that needs to be performed on the film 34 and coating layer 35 at each timing, and control the system so that the first cleaning method is selected as much as possible, thereby reducing the time and cost required for cleaning the manganese removal device 3. In other words, the control device 10 in this embodiment can, for example, efficiently clean the manganese removal device 3.

[0091] Returning to Figure 5, if the first cleaning method is determined in step S21 (YES in step S21 of Figure 5), the control device 10 determines, for example, at regular intervals such as every 10 minutes, whether the current timing is an execution timing (step S22 of Figure 5).

[0092] Specifically, the control device 10 acquires (calculates) a first pressure loss at regular intervals, such as every 10 minutes. Then, if the control device 10 determines that the acquired first pressure loss is equal to or greater than a predetermined first threshold, it determines that the current timing is the timing for cleaning the manganese removal device 3. On the other hand, if the control device 10 determines that the acquired first pressure loss is less than the first threshold, it determines that the current timing is not the timing for cleaning the manganese removal device 3.

[0093] In other words, for example, in step S22, the control device 10 waits until the current timing becomes the execution timing, or in other words, until the first pressure loss becomes equal to or greater than the first threshold.

[0094] For example, if step S22 determines that the current timing is the timing to perform cleaning of the manganese removal device 3, the control device 10 performs cleaning of the manganese removal device 3 (tank body 31) using the first cleaning method (step S23 in Figure 5). A specific example of step S23 will be explained below.

[0095] [Specific example of step S23] Figures 6 to 9 illustrate specific examples of step S23. In other words, Figures 6 to 9 illustrate specific examples of the first cleaning method.

[0096] Furthermore, as shown in Figure 6 and other figures, the water treatment system 100 will be described assuming that it further includes lines L31 and L32 that communicate with the manganese removal device 3 (tank body 31). Line L31 is, for example, a pipe that connects the inside of the manganese removal device 3 to the outside (atmosphere) of the manganese removal device 3. Line L31 is provided with a valve V1 whose opening and closing can be controlled by the control device 10. Line L32 is, for example, a pipe that connects the manganese removal device 3 to line L22 (for example, a pipe that communicates with the tank body 31 on the Z2 side of line L31). Line L32 is provided with a valve V2 whose opening and closing can be controlled by the control device 10. Furthermore, the pump P21, valve V1, and valve V2 will be collectively referred to simply as the cleaning device. Furthermore, the following description will assume that valves V1 and V2 are closed in the state before step S23 is performed.

[0097] First, we will explain the process of cleaning the manganese removal device 3 (hereinafter also simply referred to as the cleaning process), which is one of the processes included in the first cleaning method.

[0098] As shown in Figure 6, the control device 10 stops the supply of water to be treated W to the manganese removal device 3, for example, by controlling the pump P3. Specifically, the control device 10 stops the supply of water to be treated W to the manganese removal device 3, for example, by stopping the operation of the pump P3.

[0099] Then, inside the tank body 31, for example, a portion of the coating layer 35 peels off and falls (moves toward the Z2 direction) due to gravity. Hereafter, the portion of the coating layer 35 that falls due to gravity will also be referred to as coating layer 35a. Also below, the other portion of the coating layer 35 that does not fall due to gravity (the other portion of the coating layer 35 that remains attached to the film 34) will also be referred to as coating layer 35b.

[0100] Furthermore, within the tank body 31, in this case, for example, when the supply of water to be treated W to the tank body 31 is stopped, the manganese catalyst that formed the fluidized bed 33 (i.e., the manganese catalyst that was flowing due to the supply of water to be treated W to the tank body 31) is deposited on the surface of the membrane 32 (on the surface of the membrane 32 on the Z1 direction side). Hereinafter, the layer containing the manganese catalyst deposited on the membrane 32 will also be referred to as the fixed layer 33a.

[0101] Furthermore, as shown in Figure 7, the coating layer 35a gradually breaks down in shape during the falling process and disperses within the treated water W.

[0102] Next, the control device 10 performs control to open valves V1 and V2, for example, as shown in Figure 8.

[0103] Then, within the tank body 31, for example, a portion of the water to be treated W within the tank body 31 is discharged to the outside (for example, line L22) from line L32 as washing wastewater, and air A is supplied into the tank body 31 from line L31. Specifically, within the tank body 31, as shown in Figure 9, for example, a portion of the water to be treated W within the tank body 31 is discharged until the height of the water to be treated W within the tank body 31 reaches the height of the communication point with line L32.

[0104] In other words, as shown in Figures 6 to 9, the control device 10, for example, after peeling off the coating layer 35a by gravity, discharges a portion of the manganese catalyst and other materials that formed the coating layer 35a to the outside of the manganese removal device 3 together with the water to be treated W.

[0105] In the above example, we have described the case where one line L32 is installed in the manganese removal device 3, but this is not the only case. Specifically, the manganese removal device 3 may have multiple lines L32 installed at different heights, for example. In this case, the control device 10 may select one or more lines L32 (one or more lines L32 that open valve V2) for discharging the treated water W (the amount of manganese catalyst, etc., that needs to be discharged from the manganese removal device 3), for example.

[0106] Furthermore, the above example describes the case where the treated water W in the manganese removal device 3 is discharged up to the height of line L32, but it is not limited to this. Specifically, the control device 10 may, for example, continue to discharge the treated water W in the manganese removal device 3 until the water level (water level of the treated water W in the manganese removal device 3) measured by a water level gauge (not shown) installed in the manganese removal device 3 reaches a predetermined water level. Alternatively, the control device 10 may, for example, continue to discharge the treated water W in the manganese removal device 3 until the elapsed time since the start of discharge of the treated water W from the manganese removal device 3 (elapsed time since valve V2 was opened) reaches a predetermined time.

[0107] Next, we will explain the step of filling the tank body 31 with water to be treated W (hereinafter also simply referred to as the water filling step), which is one of the steps included in the first washing method.

[0108] As shown in Figure 10, the control device 10 performs control to close valve V2 after the state described in Figure 9. Then, the control device 10 starts (restarts) the supply of water to be treated W to the tank body 31 by controlling pump P3, for example. That is, the control device 10 controls the supply of water to be treated W to the tank body 31 via membrane 32 (from the Z2 direction side).

[0109] As a result, as shown in Figure 10, the water level of the treated water W inside the tank body 31 gradually rises. Also, inside the tank body 31, for example, the air A inside the tank body 31 is discharged to the outside of the tank body 31 via line L31. Furthermore, inside the tank body 31, for example, the manganese catalyst forming the stationary layer 33a starts (restarts) flowing to form (reform) the fluidized layer 33.

[0110] Subsequently, as shown in Figure 11, the control device 10 performs control to close the valve V1 in response to the water level of the water to be treated W supplied into the tank body 31 rising to approximately the height of the communication point with line L31.

[0111] Then, as shown in Figure 12, inside the tank body 31, for example, when the water to be treated W inside the tank body 31 is discharged to the outside of the tank body 31 via the membrane 34 (from the Z1 direction side), the manganese catalyst etc. contained in the water to be treated W (the manganese catalyst etc. dispersed in the water to be treated W by the first washing method) adheres (re-adheres) to the surface of the membrane 34 (the surface of the membrane 34 on the Z2 direction side) and forms (reforms) a coating layer 35 (hereinafter also called coating layer 35c).

[0112] In other words, in this case, within the tank body 31, for example, a portion of the manganese catalyst that formed the coating layer 35 is discharged to the outside by the first cleaning method, resulting in the formation of a coating layer 35c that is thinner than before the first cleaning method was performed.

[0113] Returning to Figure 5, the control device 10 restarts, for example, the water purification method described in Figure 4 (step S24 in Figure 5).

[0114] Subsequently, the control device 10 determines, for example, the next cleaning method at the next predetermined timing (step S21 in Figure 5).

[0115] On the other hand, if the second cleaning method is determined in step S21 (NO in step S21 of Figure 5), the control device 10 determines, for example, at regular intervals such as every 10 minutes, whether the current timing is an execution timing (step S25 in Figure 5).

[0116] For example, if step S25 determines that the current timing is the timing to perform cleaning of the manganese removal device 3, the control device 10 performs cleaning of the manganese removal device 3 (tank body 31) using the second cleaning method (step S26 in Figure 5). A specific example of step S26 will be explained below.

[0117] [Specific example of step S26] Figures 13 to 16 illustrate specific examples of step S26. Specifically, Figures 13 to 16 illustrate specific examples of the second cleaning method.

[0118] First, we will explain the cleaning process, which is one of the steps included in the second cleaning method.

[0119] The control device 10, for example, performs the control described in Figures 6 to 9, similar to the first cleaning method, and then performs the control to close valve V2, as shown in Figure 13. Then, the control device 10 starts supplying cleaning water Wa to the tank body 31 by controlling pump P21, for example. In this case, the control device 10 controls the supply of cleaning water Wa to the tank body 31 via membrane 34 (from the Z1 direction side).

[0120] As a result, within the tank body 31, for example, the coating layer 35b peels off from the surface of the film 34 (the surface of the film 34 on the Z2 side) due to the supply of cleaning water Wa from the Z1 side and moves to the Z2 side. Also, within the tank body 31, in this case, for example, the air A inside the tank body 31 is discharged to the outside of the tank body 31 via line L31.

[0121] In other words, the control device 10, for example, by performing a second cleaning method, removes not only the manganese catalyst attached to the surface of the membrane 34 (the surface on the Z2 direction side of the membrane 34) but also the manganese catalyst that has entered into the pores (not shown) of the membrane 34 by supplying cleaning water Wa by the pump P21 (for example, supplying high-pressure cleaning water Wa).

[0122] Furthermore, as shown in Figure 14, the coating layer 35b gradually breaks down during the falling process, for example, and disperses into the washing water Wa containing the treated water W that remained in the tank body 31. Hereinafter, the washing water Wa containing the treated water W that remained in the tank body 31 will also be simply referred to as washing water Wa.

[0123] Next, the control device 10 performs a control to open valve V2, for example, as shown in Figure 15.

[0124] Then, within the tank body 31, for example, some of the cleaning water Wa is discharged to the outside (for example, line L22) from line L32, and air A is supplied into the tank body 31 from line L31. Specifically, within the tank body 31, as shown in Figure 16, for example, some of the cleaning water Wa is discharged until the height of the cleaning water Wa within the tank body 31 reaches the height of the communication point with line L32.

[0125] In other words, as shown in Figures 13 to 16, the control device 10, for example, removes the coating layer 35b attached to the film 34 by supplying washing water Wa, and then discharges a portion of the manganese catalyst that formed the coating layer 35b to the outside of the manganese removal device 3 along with the washing water Wa.

[0126] Next, we will explain the water filling step, which is one of the steps included in the second washing method.

[0127] The control device 10, as described in Figure 10, for example, performs control to close valve V2 after the state described in Figure 16. Then, the control device 10 starts (restarts) the supply of water to be treated W to the tank body 31 by controlling pump P3, for example. That is, the control device 10 controls the supply of water to be treated W to the tank body 31 via membrane 32 (from the Z2 direction side).

[0128] As a result, within the tank body 31, for example, the water level of the water to be treated W (including the washing water Wa) gradually rises. Also, within the tank body 31, for example, the air A inside the tank body 31 is discharged to the outside of the tank body 31 via line L31. Furthermore, within the tank body 31, for example, the manganese catalyst forming the stationary layer 33a starts (restarts) flowing and forms (reforms) the fluidized layer 33.

[0129] Subsequently, the control device 10 performs control to close the valve V1, for example, in response to the water level of the water to be treated W supplied into the tank body 31 rising to approximately the height of the communication point with line L31, as described in Figure 11.

[0130] Then, inside the tank body 31, as explained in Figure 12, for example, when the water to be treated W inside the tank body 31 is discharged to the outside of the tank body 31 via the membrane 34 (from the Z1 direction side), the manganese catalyst contained in the water to be treated W (the manganese catalyst that was washed by the second washing method and dispersed in Wa) adheres (re-adheres) to the surface of the membrane 34 (the surface of the membrane 34 on the Z2 direction side) and forms (reforms) a coating layer 35 (hereinafter also called the coating layer 35c).

[0131] In other words, in this case, within the tank body 31, for example, a portion of the manganese catalyst that formed the coating layer 35 is discharged to the outside by the second cleaning method, resulting in the formation of a coating layer 35c that is thinner than before the second cleaning method was performed.

[0132] Returning to Figure 5, the control device 10 restarts, for example, the water purification method described in Figure 4 (step S27 in Figure 5).

[0133] Subsequently, the control device 10 determines, for example, the next cleaning method at the next predetermined timing (step S21 in Figure 5).

[0134] Specifically, the control device 10, for example, acquires a first pressure loss at the following predetermined timing. If the acquired first pressure loss is greater than or equal to a third threshold, it selects a second cleaning method as the next cleaning method. If the acquired first pressure loss is less than the third threshold, it selects a first cleaning method as the next cleaning method.

[0135] In other words, for example, if the coating layer 35c does not become sufficiently thin and the first pressure loss of the coating layer 35c does not decrease sufficiently even after performing the first cleaning method or the second cleaning method in step S23 or step S26, the control device 10 selects the second cleaning method as the next cleaning method in step S21, which is performed at the next predetermined timing. Similarly, for example, if fouling occurs in the film 34 and the first pressure loss of the coating layer 35c does not decrease sufficiently even after performing the first cleaning method or the second cleaning method in step S23 or step S26, the control device 10 selects the second cleaning method as the next cleaning method in step S21, which is performed at the next predetermined timing.

[0136] On the other hand, if, for example, the first pressure loss of the coating layer 35c is sufficiently reduced as a result of the first cleaning method or the second cleaning method being performed in step S23 or step S26, the control device 10 selects the first cleaning method as the next cleaning method in step S21, which is performed at the next predetermined timing.

[0137] This enables the control device 10 to efficiently clean, for example, the manganese removal device 3.

[0138] Thus, the water treatment system 100 in this embodiment includes, for example, a manganese removal device 3 in which a fluidized bed 33 containing a manganese catalyst is formed internally, and manganese is removed from the water to be treated W by passing the water to be treated W through the fluidized bed 33 in an upward flow. Furthermore, in the water treatment system 100 in this embodiment, the manganese removal device 3 has, for example, a membrane 34 on the outlet side of the water to be treated W, and a coating layer 35 is formed on the surface of the membrane 34 on the fluidized bed 33 side by, for example, the manganese catalyst that has risen inside the manganese removal device 3 adhering to it.

[0139] Furthermore, the water treatment system 100 in this embodiment includes, for example, a pump P21 for cleaning the coating layer 35, and a control device 10 for controlling the cleaning performed by the pump P21. In the water treatment system 100 in this embodiment, the control device 10 performs cleaning such that, for example, the first pressure loss when the water to be treated W that has passed through the fluidized bed 33 is passed to the coating layer 35 by upward flow falls within a predetermined range. The predetermined range is, for example, a range that is greater than or equal to a second threshold and less than a first threshold.

[0140] Specifically, in the water treatment system 100 of this embodiment, the control device 10 performs a control (hereinafter also referred to as the first control) that, for example, stops the supply of water to be treated W to the manganese removal device 3, thereby peeling off the manganese catalyst (such as manganese catalyst) that forms the coating layer 35 from the film 34, discharges a portion of the water to be treated W containing the peeled-off manganese catalyst from the manganese removal device 3, and then restarts the supply of water to be treated W to the manganese removal device 3, thereby reattaching the manganese catalyst contained in the water to be treated W that was not discharged from the manganese removal device 3 to the film 34. In other words, in this case, the control device 10 performs, for example, the first washing method.

[0141] Furthermore, in the water treatment system 100 of this embodiment, the control device 10 performs a control (hereinafter also referred to as the second control) that causes the manganese catalyst (manganese catalyst, etc.) forming the coating layer 35 to peel off from the membrane 34 by, for example, stopping the supply of water to be treated W into the manganese removal device 3 and supplying washing water from the membrane 34 into the manganese removal device 3, and after stopping the supply of washing water into the manganese removal device 3, discharge a portion of the water to be treated W containing the peeled manganese catalyst from the manganese removal device 3 and restart the supply of water to be treated W to the manganese removal device 3, thereby reattaching the manganese catalyst contained in the water to be treated W to the membrane 34. In other words, in this case, the control device 10 performs, for example, the second washing method.

[0142] Furthermore, in the water treatment system 100 of this embodiment, the control device 10 performs at least one of the first control and the second control when, for example, the first pressure loss is equal to or greater than the first threshold.

[0143] Furthermore, in the water treatment system 100 of this embodiment, the control device 10 performs a first control if, for example, the first pressure loss is greater than or equal to a first threshold. Then, in the water treatment system 100 of this embodiment, the control device 10 performs a first control if, for example, the first pressure loss after the first control is less than a third threshold (hereinafter also referred to as other thresholds) which is smaller than the first threshold, and performs a second control if the first pressure loss after the first control is greater than or equal to the third threshold.

[0144] Furthermore, in the water treatment system 100 of this embodiment, the manganese removal device 3 has, for example, one or more lines L32 that discharge a portion of the water to be treated W within the manganese removal device 3. In the water treatment system 100 of this embodiment, the control device 10 controls, for example, at least one of the one or more lines L32 so that a portion of the water to be treated W containing the manganese catalyst (manganese catalyst, etc.) is discharged from at least one of the one or more lines L32.

[0145] As a result, the water treatment system 100 in this embodiment can, for example, control the system to select the first cleaning method as much as possible while cleaning the manganese removal device 3 using a cleaning method that corresponds to the state of the membrane 34 and coating layer 35 at each timing, thereby reducing the time and cost required to clean the manganese removal device 3. In other words, the water treatment system 100 in this embodiment can, for example, efficiently clean the manganese removal device 3.

[0146] [Cleaning method in the first modified example] Next, a first modification of the cleaning method in the first embodiment (hereinafter also simply referred to as the first modification) will be described. Figure 17 is a diagram illustrating the first modification.

[0147] In the first modified example, the manganese removal device 3, as shown in Figure 17, has, for example, a line L33 that connects the manganese removal device 3 with line L22, in place of or together with lines L31 and L32, as described in Figure 6. Line L33 is, for example, a pipe that communicates with the tank body 31 at a position in the Z1 direction side of the communication point with lines L31 and L32 in the tank body 31.

[0148] Specifically, as shown in Figure 17, line L33 communicates with the tank body 31 at a height where, for example, the coating layer 35 is formed. Line L33 is also provided with a valve V3 whose opening and closing can be controlled by, for example, the control device 10.

[0149] In the first modified example, the control device 10 performs control to open valve V3 in steps S23 and S26 of Figure 5, for example, instead of the cleaning step and water filling step in the first cleaning method (the cleaning step described in Figures 6 to 9 and the water filling step described in Figures 10 to 12).

[0150] As a result, within the tank body 31, for example, when the treated water W (washing wastewater) is discharged from the tank body 31 to the line L33, a portion of the coating layer 35 (for example, a portion located on the Z2 side of the height of the line L33) is peeled off and discharged from the line L33.

[0151] Thus, in the water treatment system 100 in this modified example, the manganese removal device 3 has a line L33 that discharges the water to be treated W from within the manganese removal device 3 at a height where the coating layer 35 is formed within the manganese removal device 3. Furthermore, in the water treatment system 100 in this modified example, the manganese removal device 3 controls the line L33, for example, to detach the manganese catalyst forming the coating layer 35 from the film 34 by the upward flow of the water to be treated W, and controls the water to be treated W containing the detached manganese catalyst to be discharged from the line L33.

[0152] In other words, the water treatment system 100 in this modified example makes it possible to reduce the thickness of the coating layer 35 without stopping the supply of water to be treated W to the manganese removal device 3 or supplying water to be treated W into the manganese removal device 3 (filling the manganese removal device 3 with water to be treated W), thereby reducing the pressure loss (first pressure loss) when the water to be treated W passes through the coating layer 35.

[0153] As a result, the manganese removal device 3 in this modified example can, for example, remove manganese contained in the water to be treated W without stopping the supply of the water to be treated W to the manganese removal device 3. Therefore, the control device 10 in this modified example can, for example, suppress the decrease in the amount of water to be treated W flowing through the manganese removal device 3, and remove manganese contained in the water to be treated W more efficiently.

[0154] In this modified example, multiple lines L33 may be installed on the tank body 31 at locations on the Z1 side of the communication points with lines L31 and L32. Specifically, in this case, multiple lines L33 may be installed on the tank body 31, for example, oriented in different directions in the XY plane. The water to be treated W inside the tank body 31 may be discharged from each of the multiple lines L33.

[0155] As a result, in this modified example, the manganese removal device 3 can be controlled to ensure that the thickness of the coating layer 35 is uniform, even when, for example, the treated water W is discharged from line L33.

[0156] Furthermore, the control device 10 in this modified example may, for example, as described in Figures 6 and 7, stop the supply of water to be treated W to the manganese removal device 3, thereby dispersing a portion of the coating layer 35 into the water to be treated W, and then opening the valve V3. [Explanation of Symbols]

[0157] 1: Coagulation mixing tank 2: Filtration device 3: Manganese removal device 7a: Storage tank 7b: Storage tank 10: Control device 31: Tank body 32: Membrane 33: Fluidized bed 33a: Fixed bed 34: Film 35: Coating layer 35a: Coating layer 35b: Coating layer 35c: Coating layer 100: Water treatment system 101: CPU 102: Memory 103: Communication device 104: Storage medium 105: Bus 110: Program 130: Information storage area A: Air AD1: Addition device AD2: Addition device L1: Line L2: Line L3: Line L4: Line L11: Line L12: Line L21: Line L22: Line L31: Line L32: Line P1: Pump P2: Pump P11: Pump P12: Pump P21: Pump V1: Valve V2: Valve V3: Valve V4: Valve W: Water to be treated Wa: Washing water

Claims

1. A manganese removal system comprising: a tank having a first catalyst layer containing a manganese catalyst formed internally, and a tank through which the water to be treated is passed in an upward flow to the first catalyst layer to remove manganese from the water to be treated, wherein the tank has a first membrane on the outlet side of the water to be treated, and a second catalyst layer is formed on the surface of the first membrane on the side of the first catalyst layer by the manganese catalyst rising inside the tank as the water to be treated is supplied into the tank, A cleaning apparatus for cleaning the second catalyst layer, The system includes a control device that controls the cleaning performed by the cleaning device, The control device performs the cleaning such that the pressure loss when the water to be treated, which has passed through the first catalyst layer, is passed through the second catalyst layer in an upward flow is within a predetermined range.

2. The manganese removal system according to claim 1, wherein the control device performs a first control by stopping the supply of the water to be treated to the tank, thereby detaching the manganese catalyst forming the second catalyst layer from the first film, discharging a portion of the water to be treated containing the detached manganese catalyst from the tank, and then restarting the supply of the water to be treated to the tank, thereby reattaching the manganese catalyst contained in the water to be treated that was not discharged from the tank to the first film.

3. The manganese removal system according to claim 2, wherein the control device performs a second control, in which it stops supplying the water to be treated to the tank and supplies washing water from the first membrane to the tank, thereby detaching the manganese catalyst that forms the second catalyst layer from the first membrane, and after stopping the supply of washing water to the tank, it discharges a portion of the water to be treated containing the detached manganese catalyst from the tank and resumes supplying the water to be treated to the tank, thereby reattaching the manganese catalyst contained in the water to be treated to the first membrane.

4. The manganese removal system according to claim 3, wherein the control device performs at least one of the first control and the second control when the pressure loss is equal to or greater than a first threshold.

5. The control device is If the pressure loss is greater than or equal to the first threshold, the first control is performed. The manganese removal system according to claim 4, wherein if the pressure loss after the first control is less than another threshold smaller than the first threshold, the first control is performed, and if the pressure loss after the first control is greater than or equal to the other threshold, the second control is performed.

6. A cleaning method for a manganese removal system comprising: a tank having a first catalyst layer containing a manganese catalyst formed internally, and a tank through which water to be treated is passed in an upward flow to the first catalyst layer to remove manganese from the water to be treated, the tank having a first membrane on the outlet side of the water to be treated, a second catalyst layer formed on the surface of the first membrane on the side of the first catalyst layer by the manganese catalyst rising inside the tank as the water to be treated is supplied into the tank, and a cleaning device for cleaning the second catalyst layer, wherein A cleaning method in which the cleaning is performed such that the pressure loss when the water to be treated, which has passed through the first catalyst layer, is passed through the second catalyst layer in an upward flow is included within a predetermined range.

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