Water treatment system, control device, program and control method

Abstract

To provide a water treatment system where a treatment liquid capable of properly performing backwashing is stored in a backwashing water tank storing the treatment liquid for backwashing when performing the backwashing using the treatment liquid.SOLUTION: A water treatment system 1 includes a backwashing water tank 50 storing a treatment liquid W1 filtrated by a filter body 32 and a backwashing means backwashing the filter body 32 using the treatment liquid W1 stored in the backwashing water tank 50 after filtration is performed by the filter body 32 for a prescribed time. The backwashing means sets the storage start timing of the treatment liquid W1 or backwashing start timing so that time to store the treatment liquid W1 in the backwashing water tank 50 is shorter than filtration time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water treatment system, a control device, a program, and a control method. [Background technology]

[0002] In some cases, the filter body of a filtration device is backwashed to remove solid components accumulated in the filter body. For example, Patent Document 1 describes that the treated liquid filtered by the filtration device is stored in a backwash water tank and supplied to the secondary side of the filter body to backwash the filter body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-226345 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, if the treated liquid (filtrate) from the initial stage of filtration is stored in a backwash tank and used for backwashing, treated liquid from which the components to be removed have not been sufficiently removed may be supplied to the secondary side, and the components to be removed may remain in the secondary side.

[0005] The present invention has been made in consideration of the above, and aims to provide a control device, a filtration system, and a control method that, when backwashing is performed using a treatment liquid, can store a treatment liquid that is suitable for appropriate backwashing in a backwash tank that stores the treatment liquid for backwashing. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objectives, the water treatment system of the present disclosure includes a backwash tank that stores the treatment liquid filtered by a filter body, and a backwash means that backwashes the filter body with the treatment liquid stored in the backwash tank after filtering by the filter body for a predetermined time, and the backwash means sets the timing to start storing the treatment liquid or the timing to start backwashing so that the time the treatment liquid is stored in the backwash tank is shorter than the filtration time.

[0007] In order to solve the above-mentioned problems and achieve the objective, the control device of the present disclosure is a control device for a filtration device including a filter body and a backwash tank for storing a treatment liquid filtered by the filter body, and is characterized in that after filtration by the filter body for a predetermined time, the filter body is backwashed with the treatment liquid stored in the backwash tank, and the timing for starting storage of the treatment liquid or the timing for starting backwashing is set so that the time for which the treatment liquid is stored in the backwash tank is shorter than the filtration time.

[0008] In order to solve the above-mentioned problems and achieve the object, the program disclosed herein is a program for causing a computer to execute a control method for a filtration device including a filter body and a backwash tank for storing a treatment liquid filtered by the filter body, the program causing the computer to execute a backwash step of backwashing the filter body with the treatment liquid stored in the backwash tank after filtration by the filter body for a predetermined time, and is characterized in that in the backwash step, the timing for starting storage of the treatment liquid or the timing for starting the backwash are set so that the time for which the treatment liquid is stored in the backwash tank is shorter than the filtration time.

[0009] In order to solve the above-mentioned problems and achieve the objectives, the control method disclosed herein is a control method for a filtration device including a filter body and a backwash tank for storing a treatment liquid filtered by the filter body, and includes a backwash step of backwashing the filter body with the treatment liquid stored in the backwash tank after filtration by the filter body for a predetermined time, and in the backwash step, a timing for starting storage of the treatment liquid or a timing for starting the backwash is set so that the time for which the treatment liquid is stored in the backwash tank is shorter than the filtration time. Effect of the Invention

[0010] According to the present invention, when backwashing is performed using a treatment liquid, a treatment liquid capable of performing appropriate backwashing can be stored in the backwash water tank that stores the treatment liquid for backwashing. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a water treatment system according to a first embodiment. [Diagram 2] FIG. 2 is a schematic block diagram of the control device according to the present embodiment. [Diagram 3] FIG. 3 is a diagram illustrating the storage of the treated liquid in the backwash tank. [Figure 4] FIG. 4 is a diagram illustrating the backwashing of the filter body. [Diagram 5] FIG. 5 is a diagram illustrating an example of the timing of the filtering step, the storing step, and the backwashing step. [Figure 6] FIG. 6 is a flowchart illustrating a control flow of the filtering device by the control device according to the first embodiment. [Figure 7] FIG. 7 is a schematic diagram of a water treatment system according to the second embodiment. [Figure 8] FIG. 8 is a diagram illustrating backwashing of the filter body in the second embodiment. [Figure 9] FIG. 9 is a flowchart illustrating a control flow of the filtering device by the control device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described below.

[0013] (First embodiment) Fig. 1 is a schematic diagram of a water treatment system according to the first embodiment. As shown in Fig. 1, the water treatment system 1 according to the first embodiment includes a filtration device 10 and a control device 12. The filtration device 10 includes a treatment liquid storage tank 20, a filtration section 30, a supply mechanism 40, a backwash water tank 50, a gas supply section 60, a concentrated liquid storage tank 70, pipes L1, L2, and L3, a pump P, and valves V1, V2, V3, V4, V5, and V6.

[0014] The treatment liquid storage tank 20 is a water tank in which the treatment liquid W0 (raw water) to be filtered by the filtration device 10 is stored. The filtration section 30 includes a filter body 32 and a housing 34 that houses the filter body 32. The filter body 32 is a ceramic filter body. Examples of ceramics used for the filter body 32 include alumina, titania, zirconia, silica, mullite, spinel, and mixtures thereof. The filter body 32 is provided with a plurality of holes extending from one end 32A to the other end 32B. The filtration section 30 is configured to perform membrane filtration by a dead-end method, but the filtration method is arbitrary. The structure of the filtration section 30 is not limited to the above description and may be arbitrary. The material of the filter body 32 is not limited to ceramic and may be formed of any material.

[0015] The pipe L1 is connected to the treatment liquid storage tank 20 and the end 32A, which is the primary side of the filter body 32. A pump P and a valve V1 are provided in the pipe L1. A flocculant addition mechanism that adds a flocculant to the treatment liquid W0 flowing through the pipe L1 may be connected to the pipe L1. In this case, the pipe L1 may be provided with an in-line mixer that stirs the flocculant between the connection point of the flocculant addition mechanism and the connection point of the end 32A.

[0016] The pipe L2 is provided with a valve V2 and is connected to the side surface 34A of the housing 34 and the supply mechanism 40. The side surface 34A of the housing 34 faces the side surface (outer peripheral surface) 32C, which is the secondary side of the filter body 32, so it can be said that the pipe L2 is connected to the secondary side of the filter body 32. The supply mechanism 40 is a mechanism to which the treatment liquid W1 flowing through the pipe L2 is supplied, and is, for example, a water tank, but is not limited to a water tank and may have any configuration. In addition, a backwash water tank 50 is also connected to the pipe L2. The backwash water tank 50 is connected to the pipe L2 by branching (in parallel) from the connection line with the supply mechanism 40. The backwash water tank 50 stores a part of the treatment liquid W1 flowing through the pipe L2. A gas supply unit 60 is connected to the backwash water tank 50. The gas supply unit 60 is a tank in which a gas such as air is stored, and supplies gas toward the liquid surface of the treatment liquid W1 in the backwash water tank 50. A valve V3 is provided between the backwash water tank 50 and the pipe L2, and a valve V5 is provided between the backwash water tank 50 and the gas supply unit 60. In addition, the backwash water tank 50 is also provided with a valve V4 for releasing pressure within the backwash water tank 50.

[0017] The pipe L3 is connected to the pipe L1 (i.e., the primary side of the filter body 32) and a concentrated liquid storage tank 70. The concentrated liquid storage tank 70 stores the concentrated liquid W2 generated by backwashing the filter body 32. The pipe L3 is provided with a valve V6.

[0018] FIG. 2 is a schematic block diagram of the control device according to this embodiment. The control device 12 is a device that controls the filtration device 10, which is a computer in this embodiment, and includes a control unit 80 and a storage unit 90 as shown in FIG. 2. The control unit 80 is a CPU (Central Processing Unit). The control unit 80 reads out and executes a program (software) from the storage unit 90 to execute the processes described below. The control unit 80 may execute these processes using one CPU, or may include multiple CPUs and execute these processes using the multiple CPUs. The processes described below may also be realized using hardware circuits, etc.

[0019] FIG. 1 shows a state in which the filtration device 10 is performing filtration, that is, a filtration process. When performing filtration, the control device 12 drives the pump P, opens the valves V1, V2, and V4, and closes the valves V3, V5, and V6. As a result, the liquid to be treated W0 stored in the treatment liquid storage tank 20 is supplied to the end 32A, which is the primary side of the filter body 32, through the pipe L1. The liquid to be treated W0 penetrates into the holes of the filter body 32 from the end 32A and is membrane filtered. The liquid to be treated W0 is membrane filtered through the holes of the filter body 32 and is discharged as a treated liquid W1 after filtration from the side 32C, which is the secondary side of the filter body 32. The treated liquid W1 discharged from the side 32C is supplied to the supply mechanism 40 through the pipe L2. In addition, if there is a flocculant addition mechanism, the control device 12 may control the flocculant addition mechanism during the filtration to add a flocculant to the treated liquid W0 before filtration.

[0020] FIG. 3 is a diagram for explaining the storage of the treatment liquid in the backwash tank. As shown in FIG. 3, when the treatment liquid W1 for backwashing is stored in the backwash tank 50, that is, during the storage process, the control device 12 keeps the pump P driven, opens the valves V1, V3, and V4, and closes the valves V2, V5, and V6. As a result, the filtration of the liquid W0 to be treated in the filter body 32 continues, and the treatment liquid W1 discharged from the side surface 32C is supplied into the backwash tank 50 through the pipe L2. The supplied treatment liquid W1 is stored in the backwash tank 50. Note that the control device 12 does not need to close the valve V3 during the storage process, and may open both the valves V2 and V3 to supply the treatment liquid W1 to both the backwash tank 50 and the supply mechanism 40.

[0021] FIG. 4 is a diagram for explaining the backwashing of the filter body. The water treatment system 1 executes the backwashing process described below by the backwashing means. The backwashing means is a main body that executes the backwashing process in the water treatment system 1, and is realized by the control device 12, the valves V1 to V5, the gas supply unit 60, and the like. As shown in FIG. 4, when backwashing the filter body 32, that is, during the backwashing process, the control device 12 stops the pump P, opens the valves V3, V5, and V6, closes the valves V1, V2, and V4, and controls the gas supply unit 60 to supply gas A toward the liquid surface of the treatment liquid W1 in the backwash water tank 50. As a result, filtration in the filter body 32 is stopped, and the treatment liquid W1 stored in the backwash water tank 50 is pressurized by the gas A and supplied to the secondary side of the filter body 32 through the pipe L2, and is discharged as the concentrated liquid W2 to the pipe L3 together with foreign matter such as viruses and solid components that have clogged the filter body 32. The concentrated liquid W2 is supplied to the concentrated liquid storage tank 70 through a pipe L3.

[0022] In this way, the control device 12 causes the treatment liquid W1 stored in the backwash water tank 50 to be supplied to the secondary side of the filter body 32 to perform backwashing of the filter body 32. Here, the filtration device 10 tends to have a low removal rate of foreign matter such as viruses and solid components at the beginning of filtration, and for example, if backwashing is performed using the treatment liquid W1 at the beginning of filtration, the treatment liquid W1 from which foreign matter has not been sufficiently removed is supplied to the secondary side of the filter body 32, and there is a risk that foreign matter will remain on the secondary side. Therefore, the treatment liquid W1 capable of being appropriately backwashed is stored in the backwash water tank 50. Correspondingly, the water treatment system 1 according to this embodiment makes it possible to store the treatment liquid W1 that has been filtered by the filter body 32 for a predetermined time and is capable of being appropriately backwashed in the backwash water tank 50 by backwashing the filter body using the treatment liquid W1 stored in the backwash water tank 50 by the backwashing means, thereby filtering the filter body after the predetermined time has elapsed. Hereinafter, the control of the control device 12 will be specifically described.

[0023] FIG. 5 is a diagram for explaining an example of the timing of the filtration process, the storage process, and the backwash process. The water treatment system 1 according to this embodiment starts the filtration process at a filtration start timing T0. Then, at a storage start timing T1, which is a timing when a predetermined time has elapsed since the start of filtration, the storage process starts. From the filtration start timing T0 to the storage start timing T1 (ΔT0A), filtration by the filter body 32 is performed without storing the treatment liquid W1 in the backwash water tank 50. Then, when the backwash start timing T2 is reached, the backwash process starts. From the storage start timing T1 to the backwash start timing T2 (time ΔT1), the treatment liquid W1 filtered by the filter body 32 is stored in the backwash water tank 50, and after the backwash start timing T2, filtration by the filter body 32 is stopped, and backwashing is performed with the treatment liquid W1 stored in the backwash water tank 50. In the water treatment system 1 according to this embodiment, the storage start timing T1 or the backwash start timing T2 is set so that the time (ΔT1) during which the treatment liquid W1 is stored in the backwash tank is shorter than the filtration time (ΔT0A or ΔT0B).

[0024] (1. Setting the storage start timing) An example of setting the storage start timing T1 will be described. The control device 12 sets the timing at which a predetermined time has elapsed since the start of filtration based on a predetermined filtration time as the storage start timing T1. The storage start timing T1 may be set based on a backwash start timing T2 that is predetermined from a predetermined filtration time (ΔT0B in FIG. 5), for example, or may be set based on a predetermined filtration time (ΔT0A in FIG. 5). It is preferable that the storage start timing T1 is set after a time has elapsed from the filtration start timing T0 to a degree that the decrease in the removal rate of foreign matter by the filter body 32 is sufficiently eliminated. For example, the storage start timing T1 is preferably set so that the time ΔT0A from the filtration start timing T0 to the storage start timing T1 is 70% or more and 98.7% or less of the time ΔT0B from the filtration start timing T0 to the backwash start timing T2, and more preferably, the storage start timing T1 is set immediately before the backwash start timing T2. However, the method for setting the storage start timing T1 is not limited to the above, and may be set arbitrarily.

[0025] (1-1. When setting based on a specified filtration time ΔT0B) In this case, the time when a predetermined filtration time ΔT0B has elapsed is preset as the backwash start timing T2. Therefore, the control device 12 sets a predetermined time before the backwash start timing T2 as the storage start timing T1. Specifically, the control device 12 acquires a supply flow rate, which is the flow rate of the treated liquid W0 supplied to the filter body 32 per unit time, and a required flow rate, which is the flow rate of the treated liquid W1 required for backwashing, and calculates a supply time, which is the time required for storage. The control device 12 calculates the supply time for supplying the treated liquid W1 to the backwash water tank 50 by dividing the acquired required flow rate by the supply flow rate. The control device 12 sets the storage start timing T1, which is earlier than the backwash start timing T2 in the supply time, based on the calculated supply time. Note that a buffer may be provided in the supply time, and the timing obtained by going back from the backwash start timing T2 by the supply time and the buffer may be set as the storage start timing T1.

[0026] Here, the required flow rate is set in advance, and the control device 12 may read out the required flow rate from the storage unit 90. In addition, the supply flow rate may be a preset value read out from the storage unit 90. Alternatively, the flow rate of the liquid to be treated W0 supplied to the filter body 32 may be detected by a sensor (flow meter) provided in the filtration device 10, and used as the supply flow rate.

[0027] (1-2. When setting based on a specified filtration time ΔT0A) In this case, the predetermined filtration time ΔT0A is set based on the required flow rate. The controller 12 sets the time point when the predetermined filtration time ΔT0A has elapsed as the storage start timing T1.

[0028] (2. Setting the backwash start timing) The treatment liquid W1 is stored in the backwash tank 50 from a predetermined storage start timing T1. The control device 12 sets the backwash start timing T2. The backwash start timing T2 may be set based on, for example, a supply time or a required flow rate.

[0029] (2-1. Setting based on supply time) In this case, the storage start timing T1 is set. The control device 12 sets the backwash start timing T2 to a predetermined time after the storage start timing T1. Specifically, the control device 12 calculates the supply time required to store the treatment liquid W1 based on the supply flow rate and the required flow rate, and sets the backwash start timing T2 based on the storage start timing T1 and the supply time. The control device 12 may set the backwash start timing T2 to a timing that is the supply time after the storage start timing T1, or may set a buffer in the supply time and set the backwash start timing T2 to a timing that is the supply time plus the buffer after the storage start timing T1.

[0030] (2-2. Setting based on required flow rate) The control device 12 sets the backwash start timing T2 based on the timing when the flow rate of the treatment liquid W1 stored in the backwash tank 50 reaches the required flow rate. In this case, the backwash tank 50 is provided with a sensor for detecting the flow rate of the treatment liquid W1. This sensor may be a water level gauge that measures the water level of the treatment liquid W1 in the backwash tank 50, or a flow meter that measures the inflow amount of the treatment liquid W1 into the backwash tank 50 per unit time. The control device 12 starts storing the treatment liquid W1 in the backwash tank 50 from the storage start timing T1, while sequentially acquiring the detection value of this sensor, and judges whether the flow rate of the treatment liquid W1 stored in the backwash tank 50 has reached the required flow rate. The control device 12 may set the backwash start timing T2 as the timing when the flow rate of the treatment liquid W1 in the backwash tank 50 reaches the required flow rate, or may set a buffer and set the backwash start timing T2 as the timing after the buffer amount after the flow rate of the treatment liquid W1 in the backwash tank 50 reaches the required flow rate.

[0031] In the above description, filtration by the filter body 32 is stopped and backwashing is started at the backwashing start timing T2, but the invention is not limited to this, and the timing to start backwashing may be delayed from the timing to stop filtration by the filter body 32 (the timing to stop storage in the backwashing tank 50). In this case, it is preferable to set the time between the timing to stop filtration (the timing to stop storage in the backwashing tank 50) and the timing to start backwashing short, and it is preferable to set the timing to start backwashing within a predetermined time after filtration is stopped (after storage in the backwashing tank 50 is stopped).

[0032] It is to be noted that only one of the setting of the storage start timing T1 and the setting of the backwash start timing T2 may be performed, or both may be performed.

[0033] The above-described filtration process, storage process, and backwash process will be described based on a flowchart. FIG. 6 is a flowchart illustrating the control flow of the filtration device by the control device according to the first embodiment. As shown in FIG. 6, the control device 12 causes the filtration device 10 to execute the filtration process from the filtration start timing T0 (step S10). While executing the filtration process, the control device 12 judges whether the storage start timing T1 has been reached (step S12), and if the storage start timing T1 has not been reached (step S12; No), the filtration process is continued. On the other hand, if the supply start timing has been reached (step S12; Yes), the control device 12 executes the storage process (step S14) and starts storing the treatment liquid W1 in the backwash water tank 50. While executing the storage process, the control device 12 judges whether the backwash start timing T2 has been reached (step S16), and if the backwash start timing T2 has not been reached (step S16; No), the storage process is continued. On the other hand, when the backwash start timing T2 is reached (step S16; Yes), the control device 12 stops filtration by the filter body 32 and executes the backwashing process (step S18). When the backwashing process is completed, the control device 12 determines whether to resume filtration (step S20), and if it is to be resumed (step S20; Yes), the process returns to step S10, and if it is not to be resumed (step S20; No), the process ends.

[0034] According to the water treatment system 1, the treatment liquid W1 in the early stage of filtration, from which foreign matter has not been sufficiently removed, is prevented from being supplied to the secondary side of the filter body 32, and the treatment liquid W1 capable of being appropriately backwashed can be stored in the backwash water tank 50. In addition, for example, if the treated liquid W0 is high temperature, the treatment liquid W1 cools as the storage time of the treatment liquid W1 increases, and the temperature difference between the treated liquid W0 and the treatment liquid W1 for backwashing increases, and the treatment liquid W1 may rapidly cool the filter body 32 during backwashing, causing damage to the filter body 32. As in the conventional technology, when the treatment liquid W1 in the early stage of filtration is stored in the backwash water tank 50, the storage time in the backwash water tank 50 is almost the same as the filtration time, but according to the water treatment system 1, the storage start timing T1 and the backwash start timing T2 are set so that the storage time in the backwash water tank 50 is shorter than the filtration time, so that backwashing can be performed before the cooling of the treatment liquid W1 progresses, thereby suppressing damage to the filter body 32 due to rapid cooling.

[0035] The backwashing means sets the timing when a predetermined time has elapsed since the start of filtration as the storage start timing T1 of the treated liquid W1. According to this water treatment system 1, since storage of the treated liquid W1 in the backwash tank 50 starts after the predetermined time has elapsed, backwashing can be performed using the treated liquid W1 for which a sufficient amount of time has elapsed since the start of filtration, and backwashing can be performed appropriately.

[0036] The backwashing means sets the storage start timing T1 of the treated liquid W1 to a predetermined time before the backwashing start timing T2. According to this water treatment system 1, the treated liquid W1 is not stored at the beginning of filtration, but is stored a predetermined time before the backwashing start timing T2, so that backwashing can be performed appropriately using the treated liquid W1 that has been in use for a sufficient amount of time since the start of filtration.

[0037] The backwashing means calculates a supply time required to store the treated liquid W1 in the backwash tank 50 based on the supply flow rate of the treated liquid W0 to the filter body 32 and the required flow rate of the treated liquid W1 required for backwashing. The backwashing means sets the storage start timing T1 of the treated liquid W1 to a point in time before the supply time of the predetermined backwashing start timing T2. According to this water treatment system 1, since the storage start timing T1 is set in this manner, it is possible to use the treated liquid W1 that has been there for a sufficient amount of time since the start of filtration, and backwashing can be performed appropriately.

[0038] The backwashing means calculates a supply time required to store the treated liquid W1 in the backwash tank 50 based on the required flow rate of the treated liquid W1 required for backwashing and the supply amount of the treated liquid W0. The backwashing means sets the backwashing start timing T2 to a point within a predetermined time after the supply time has elapsed from the storage start timing T1. Since the backwashing start timing T2 is set in this manner, the water treatment system 1 can use the treated liquid W1 for which a sufficient amount of time has passed since the start of filtration, and can perform backwashing appropriately.

[0039] The backwashing means sets the backwashing start timing T2 to a time within a predetermined time after the amount of the treated liquid W1 required for backwashing is stored in the backwashing tank 50. According to this water treatment system 1, backwashing is started immediately after the amount of the treated liquid W1 required for backwashing is stored in the backwashing tank 50, so that backwashing is performed before cooling of the treated liquid W1 progresses, thereby suppressing damage to the filter body 32 due to rapid cooling.

[0040] Furthermore, after filtering the filter body 32 for a predetermined time, the control device 12 backwashes the filter body 32 using the treatment liquid W1 stored in the backwash tank 50. The control device 12 sets the storage start timing T1 of the treatment liquid W1 or the backwash start timing T2 so that the time the treatment liquid W1 is stored in the backwash tank 50 is shorter than the filtration time. This control device 12 makes it possible to perform backwashing using the treatment liquid W1 that has been in use for a sufficient amount of time since the start of filtration, and therefore allows the backwashing to be performed appropriately.

[0041] Second embodiment Next, a second embodiment will be described. In the second embodiment, the structure of the filtration device 10 is different from that of the first embodiment. In the second embodiment, the description of the parts having the same configuration as the first embodiment will be omitted.

[0042] FIG. 7 is a schematic diagram of a water treatment system according to a second embodiment. As shown in FIG. 7, in the filtration device 10a according to the second embodiment, a pipe L2a1 is connected to a backwash water tank 50a and the secondary side (side surface 34A of the housing 34) of the filter body 32. A valve V3 is provided in the pipe L2a1. A pipe L2a2 is connected between the backwash water tank 50a and the supply mechanism 40. A valve V2 is provided in the pipe L2a2. That is, while the backwash water tank 50a and the supply mechanism 40 are connected in parallel to the secondary side of the filter body 32 in the first embodiment, the backwash water tank 50a and the supply mechanism 40 are connected in series to the secondary side of the filter body 32 in the second embodiment. The backwash water tank 50a is configured to be able to discharge the treatment liquid W1 supplied thereinto to the supply mechanism 40.

[0043] FIG. 7 shows the filtration process. In the second embodiment, the treated liquid W1 from the filter body 32 is stored in the backwash water tank 50a, and the treated liquid W1 flowing out from the backwash water tank 50a is discharged to the supply mechanism 40. In this way, since the filtration process of the second embodiment also stores the treated liquid W1 in the backwash water tank 50a, it can be said that the filtration process of the first embodiment, in which the treated liquid W1 is discharged without being stored in the backwash water tank 50a, and the storage process of storing the treated liquid W1 in the backwash water tank 50a are performed simultaneously. When performing the filtration process, the control device 12 drives the pump P, opens the valves V1, V2, V3, and V4, and closes the valves V5 and V6, as shown in FIG. 7. As a result, the treated liquid W1 filtered by the filter body 32 is supplied to the backwash water tank 50a through the pipe L2a1. In addition, because the valve V2 is open, the treatment liquid W1 supplied to the backwash tank 50a is stored in the backwash tank 50a while a portion of the treatment liquid W1 is discharged to the supply mechanism 40 via the pipe L2a2. It can be said that the treatment liquid W1 supplied to the backwash tank 50a is discharged to the supply mechanism 40 after being stored in the backwash tank 50a for a predetermined residence time.

[0044] FIG. 8 is a diagram for explaining the backwashing of the filter body in the second embodiment. As shown in FIG. 8, during the backwashing process, the control device 12 stops the pump P, opens the valves V3, V5, and V6, closes the valves V1, V2, and V4, and controls the gas supply unit 60 to supply the gas A toward the liquid surface of the treatment liquid W1 in the backwash water tank 50a. As a result, the filtration in the filter body 32 is stopped, and the treatment liquid W1 stored in the backwash water tank 50a is pressurized by the gas A and supplied to the secondary side of the filter body 32 through the pipe L2, and is discharged as the concentrated liquid W2 to the pipe L3 together with the foreign matter clogging the filter body 32. The concentrated liquid W2 is supplied to the concentrated liquid storage tank 70 through the pipe L3.

[0045] FIG. 9 is a flow chart for explaining the control flow of the filtration device by the control device according to the second embodiment. As shown in FIG. 9, the control device 12 causes the filtration device 10 to execute the filtration process from the filtration start timing T0 (step S30). The control device 12 judges whether the backwash start timing T2 has been reached while executing the filtration process (step S32), and if the backwash start timing T2 has not been reached (step S32; No), the filtration process is continued. On the other hand, if the backwash start timing T2 has been reached (step S32; Yes), the control device 12 causes the backwash process to be executed (step S34). In the second embodiment, the filtration time is preset, and the timing at which the filtration time has elapsed from the filtration start timing T0 is the backwash start timing T2. When the backwash process is completed, the control device 12 judges whether to resume filtration (step S36), and if it is to be resumed (step S36; Yes), the process returns to step S30, and if it is not to be resumed (step S36; No), the process ends.

[0046] Thus, in the second embodiment, the treatment liquid W1 is continuously supplied to the backwash tank 50a from the filtration start timing T0 to the backwash start timing T2 without setting the storage start timing T1 at which the filtration process is switched to the storage process. Then, at the backwash start timing T2, the supply of the treatment liquid W1 to the backwash tank 50a is stopped to perform backwashing. At the backwash start timing T2, the backwash tank 50a stores the treatment liquid W1 that has been filtered after a predetermined time has elapsed from the filtration start timing, before the residence time has elapsed since it was supplied to the backwash tank 50a. Therefore, at the backwash start timing T2, the backwash tank 50a contains the treatment liquid W1 that has been filtered after a predetermined time has elapsed since the start of filtration, so that the treatment liquid W1 used for backwashing includes the treatment liquid W1 that has been stored in the backwash tank 50 after a predetermined time has elapsed since the start of filtration. In addition, the residence time of the treatment liquid W1 is shorter than the filtration time (here, the time from the filtration start timing T0 to the backwash start timing T2). Since the residence time of the treatment liquid W1 corresponds to the time the treatment liquid W1 is stored in the backwash tank 50a, in the second embodiment as well, it can be said that the backwash start timing T2 is set so that the time the treatment liquid W1 is stored in the backwash tank 50a is shorter than the filtration time.

[0047] As described above, in the second embodiment, the backwash tank 50a is configured to be able to discharge the treated liquid W1 supplied therein to the supply mechanism 40 to which the treated liquid W1 is supplied. The backwash means supplies the treated liquid W1 to the backwash tank 50a from the start of filtration, while discharging a part of the treated liquid W1 in the backwash tank 50a to the supply mechanism 40. The backwash means starts backwashing when a predetermined filtration time has elapsed. In the second embodiment, the backwash means backwashes the filter body 32 using the treated liquid W1 stored in the backwash tank 50a after filtering for a predetermined time, and sets the backwash start timing T2 so that the time the treated liquid W1 is stored in the backwash tank 50a is shorter than the filtration time. Therefore, in the second embodiment, as in the first embodiment, backwashing can be appropriately performed using the treated liquid W1 that has been filtered for a sufficient amount of time since the start of filtration, and cooling of the treated liquid W1 is suppressed, thereby suppressing damage to the filter body 32 due to rapid cooling. In the second embodiment, the supply of the treatment liquid W1 to the backwash tank 50a starts from the start of filtration, which has the advantage of reliably securing the treatment liquid W1 for backwashing. On the other hand, in the first embodiment, the storage of the treatment liquid W1 in the backwash tank 50 starts after a predetermined time has elapsed from the start of filtration, which has the advantage of more suitably preventing the intrusion of foreign matter.

[0048] Although the embodiments of the present invention have been described above, the embodiments are not limited to the contents of these embodiments. The above-described components include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the gist of the above-described embodiments. [Explanation of symbols]

[0049] 1. Water Treatment System 10 Filtration equipment 12 Control device 32 Filter body 50 Backwash tank W0 Liquid to be treated W1 Processing solution

Claims

1. A filter body, a supply mechanism to which treated water filtered by the filter body is supplied; a backwash water tank for storing the treated water, the treated water being supplied through a line branched off from a connection line between the filter body and the supply mechanism; and a backwashing means for backwashing the filter body with the treatment liquid stored in the backwash water tank after filtering for a predetermined time by the filter body, The backwashing means is A portion of the treatment liquid filtered by the filter body and supplied to the supply mechanism is supplied to the backwash water tank; The timing for starting the storage of the treated liquid or the backwashing is set so that the time during which the treated liquid is stored in the backwashing tank is shorter than the filtration time. A water treatment system comprising:

2. The backwashing means is The water treatment system according to claim 1 , wherein the timing to start storing the treatment liquid is set to a timing when a predetermined time has elapsed since the start of filtration.

3. The backwashing means is The water treatment system according to claim 2 , wherein the storage start timing for the treatment liquid is set to a predetermined time before a predetermined backwash start timing.

4. The backwashing means is calculating a supply time required to store the treatment liquid in the backwash tank based on the amount of the treatment liquid required for backwashing and the amount of the liquid to be treated; The water treatment system according to claim 3 , wherein the storage start timing for the treatment liquid is set to a time point before the supply time of a predetermined backwash start timing.

5. The backwashing means is calculating a supply time required to store the treatment liquid in the backwash tank based on the amount of the treatment liquid required for backwashing and the amount of the liquid to be treated; The water treatment system according to any one of claims 1 to 4, wherein the backwash start timing is set to a point within a predetermined time after the supply time has elapsed from the storage start timing.

6. The backwashing means is The water treatment system according to any one of claims 1 to 4, wherein the backwash start timing is set to a point within a predetermined time after the amount of treatment liquid required for backwashing is stored in the backwash tank.

7. A control device for a filtration device including a filter body, a supply mechanism to which treated water filtered by the filter body is supplied, and a backwash water tank to which the treated water filtered by the filter body is supplied via a line branched off from a connection line between the filter body and the supply mechanism, the control device comprising: A portion of the treatment liquid filtered by the filter body and supplied to the supply mechanism is supplied to the backwash water tank; After filtering the wastewater through the filter for a predetermined time, the filter is backwashed with the treatment liquid stored in the backwash water tank; The timing for starting the storage of the treated liquid or the backwashing is set so that the time during which the treated liquid is stored in the backwashing tank is shorter than the filtration time. A control device comprising:

8. A program for causing a computer to execute a control method for a filtration device including a filter body, a supply mechanism for supplying treated water filtered by the filter body, and a backwash water tank for storing the treated water, the backwash water tank being supplied with the treated water filtered by the filter body via a line branched off from a connection line between the filter body and the supply mechanism, a backwashing step of supplying a portion of the treatment liquid filtered by the filter body and supplied to the supply mechanism to the backwash water tank, filtering the treatment liquid for a predetermined time using the filter body, and then backwashing the filter body with the treatment liquid stored in the backwash water tank; Let the computer run In the backwashing step, The timing for starting the storage of the treated liquid or the backwashing is set so that the time during which the treated liquid is stored in the backwashing tank is shorter than the filtration time. A program characterized by:

9. A method for controlling a filtration apparatus including a filter body, a supply mechanism to which treated water filtered by the filter body is supplied, and a backwash water tank to which the treated water filtered by the filter body is supplied via a line branched off from a connection line between the filter body and the supply mechanism, the method comprising: A backwashing step of backwashing the filter body with the treatment liquid stored in the backwash water tank after filtering for a predetermined time with the filter body, In the backwashing step, A part of the treated liquid filtered by the filter body and supplied to the supply mechanism is supplied to the backwash tank, and a timing to start storing the treated liquid or a timing to start backwashing is set so that the time the treated liquid is stored in the backwash tank is shorter than the filtration time. A control method comprising:

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