Water purification system and water purification method

Abstract

To provide a water purification system which can continuously generate treated water, and to provide a water purification method.SOLUTION: A water purification system includes: a first filtration facility which filters raw water; a second filtration facility which filters raw water or detergent drain discharged from the first filtration facility in association with cleaning of the first filtration facility; and a supply part which may supply the raw water to the first filtration facility, supply the detergent drain from the first filtration facility to the second filtration facility, and supply the raw water to the second filtration facility.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fresh water production system and a fresh water production method. [Background technology]

[0002] For example, water purification plants use water treatment systems (hereinafter also referred to as water treatment systems) that include filtration equipment that produces purified water (hereinafter also referred to as treated water) by filtering raw water (hereinafter also referred to as water to be treated), such as river water, dam / lake water, and well water. Specifically, in such water treatment systems, for example, the water to be treated to which a coagulant has been added is stirred to cause coagulation and sedimentation of suspended solids contained in the water to be treated, and then the water to be treated is filtered using filtration equipment (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-171228 Summary of the Invention [Problem to be solved by the invention]

[0004] In the water treatment system described above, it is desirable to continue producing treated water (creating fresh water) even if the function of the water treatment system is reduced or stopped due to the occurrence of a natural disaster or the like, for example. [Means for solving the problem]

[0005] The freshwater production system of the present invention comprises a first filtration equipment that filters raw water, a second filtration equipment that filters the raw water or cleaning wastewater discharged from the first filtration equipment in connection with cleaning of the first filtration equipment, and a supply unit that can supply the raw water to the first filtration equipment, can supply the cleaning wastewater from the first filtration equipment to the second filtration equipment, and can supply the raw water to the second filtration equipment. [Effects of the Invention]

[0006] According to the fresh water production system of the present invention, it is possible to continuously produce treated water. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a fresh water production system 1000 according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating the hardware configuration of the control device 200. As shown in FIG. [Figure 3] FIG. 3 is a diagram illustrating the function of the control device 200. As shown in FIG. [Figure 4] FIG. 4 is a flowchart illustrating purified water production control in the first embodiment. [Figure 5] FIG. 5 is a flowchart illustrating purified water production control in the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating purified water production control in the first embodiment. [Figure 7] FIG. 7 is a diagram illustrating purified water production control in the first embodiment. [Figure 8] FIG. 8 is a diagram illustrating purified water production control in the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0009] [Water production system 1000 according to the first embodiment] First, a description will be given of a configuration example of a fresh water production system 1000 in the first embodiment. Fig. 1 is a diagram illustrating a configuration example of a fresh water production system 1000 in the first embodiment.

[0010] The freshwater production system 1000 includes a water treatment system 100 installed in, for example, a water purification plant. Specifically, the water treatment system 100 includes, for example, a gritification basin 11, a receiving well 12, a chemical mixing basin 13, a flocculation basin 14, a sedimentation basin 15, a filtration equipment 16 (hereinafter also referred to as the first filtration equipment 16), a purified water basin 17, a wastewater basin 18 (hereinafter also referred to as the first wastewater basin 18), a filtration equipment 19 (hereinafter also referred to as the second filtration equipment 19), a wastewater basin 20 (hereinafter also referred to as the second wastewater basin 20), a thickener / dehydrator 21, and a chemical supply equipment 22. Note that in the example shown in FIG. 1 , pumps that supply the water to be treated between each piece of equipment and valves that control the amount of water to be treated supplied between each piece of equipment (pumps and valves installed on each line) are not shown.

[0011] The settling basin 11 is a tank into which the water to be treated first flows via a line L1 that connects the settling basin 11 to a river or the like, and is a tank where sedimentation and removal of sediment and the like contained in the water to be treated is performed. The line L1 is, for example, a pipe that connects the settling basin 11 to a river or the like.

[0012] The receiving well 12 is, for example, a tank that adjusts the amount of water to be treated supplied from the settling basin 11 via line L2 and supplies the water to the chemical mixing basin 13. The line L2 is, for example, a pipe that connects the settling basin 11 and the receiving well 12.

[0013] The chemical mixing basin 13 is, for example, a tank in which a flocculant is injected into the water to be treated supplied from the receiving well 12 via line L3. The line L3 is, for example, a pipe connecting the receiving well 12 and the chemical mixing basin 13.

[0014] The flocculation basin 14 is a tank that, for example, agitates the water to be treated supplied from the chemical mixing basin 13 via line L4, thereby flocculating suspended solids contained in the water to be treated supplied from the chemical mixing basin 13 with a flocculant to form flocs. The line L4 is, for example, a pipe that connects the chemical mixing basin 13 and the flocculation basin 14.

[0015] The settling tank 15 is a tank in which flocs contained in the water to be treated, supplied from the flocculation tank 14 via the line L5, are precipitated and separated from the water to be treated. The line L5 is, for example, a pipe connecting the flocculation tank 14 and the settling tank 15.

[0016] The filtration equipment 16 is, for example, a facility (tank) that produces treated water (hereinafter also referred to as first treated water or first purified water) by filtering the water to be treated supplied from the settling tank 15 via line L6. Line L6 is, for example, a pipe that connects the settling tank 15 and the filtration equipment 16. Specifically, the filtration equipment 16 has a filter body (not shown) made of, for example, sand, gravel, or the like, and is a facility that performs sand filtration on the water to be treated. Furthermore, the filtration equipment 16 has a filtration membrane such as a microfiltration membrane or an ultrafiltration membrane, and is a facility that performs membrane filtration on the water to be treated.

[0017] Furthermore, the filtration equipment 16 backwashes (cleans) the filter body by using a portion of the treated water filtered by the filtration equipment 16, for example, periodically, such as once a day, or depending on the condition of the filter body, such as clogging. Hereinafter, the wastewater discharged in association with the backwashing of the filtration equipment 16 will also be referred to as washing wastewater or first washing wastewater. Hereinafter, the timing when the filtration equipment 16 is filtering the water to be treated will also be referred to as normal operation, and the timing when the filtration equipment 16 is backwashed will also be referred to as backwashing.

[0018] In the above example, the water treatment system 100 has been described as having the settling tank 15, but the present invention is not limited to this. Specifically, the water treatment system 100 may have, for example, other filtration equipment (not shown) that performs membrane filtration instead of the settling tank 15.

[0019] In the above example, the chemical mixing basin 13 and the flocculation basin 14 are separate entities, but the present invention is not limited to this. Specifically, the chemical mixing basin 13 and the flocculation basin 14 may be, for example, an integrated facility.

[0020] In the above example, the flocculation basin 14 and the settling basin 15 are separate bodies, but the present invention is not limited to this. Specifically, the flocculation basin 14 and the settling basin 15 may be, for example, an integrated facility (tank).

[0021] In the above example, the sedimentation tank 15 and the filtration equipment 16 are separate entities, but this is not limiting. Specifically, the sedimentation tank 15 and the filtration equipment 16 may be, for example, an integrated facility.

[0022] In the above example, the water treatment system 10 has been described as having one filtration equipment 16, but the present invention is not limited to this. Specifically, the water treatment system 100 may have, for example, multiple filtration equipment 16 that perform distributed filtration of the water to be treated supplied from the settling tank 15.

[0023] The purified water reservoir 17 is, for example, a tank that stores treated water supplied from the filtration equipment 16 via a line L7. The line L7 is, for example, a pipe that connects the filtration equipment 16 and the purified water reservoir 17. The treated water stored in the purified water reservoir 17 is then supplied to homes, etc., via a distribution reservoir (not shown), for example.

[0024] The wastewater reservoir 18 is, for example, a tank that stores the first cleaning wastewater discharged from the filtration equipment 16 via a line L11. The line L11 is, for example, a pipe that connects the filtration equipment 16 and the wastewater reservoir 18.

[0025] As shown in Fig. 1 , the wastewater reservoir 18 may be supplied with a portion of the water to be treated stored in the chemical mixing reservoir 13 via a line L12. The line L12 is, for example, a pipe connecting the chemical mixing reservoir 13 and the wastewater reservoir 18. Similarly, the wastewater reservoir 18 may be supplied with a portion of the water to be treated stored in the flocculation reservoir 14 via a line L13. The line L13 is, for example, a pipe connecting the flocculation reservoir 14 and the wastewater reservoir 18. The wastewater reservoir 18 may be supplied with a portion of the water to be treated stored in the sedimentation reservoir 15 via a line L14. The line L14 is, for example, a pipe connecting the sedimentation reservoir 15 and the wastewater reservoir 18.

[0026] Furthermore, when the water treatment system 100 has a plurality of filtration equipments 16, the line L11 may be, for example, a pipe (branch pipe) that connects each of the plurality of filtration equipments 16 with the wastewater reservoir 18.

[0027] The filtration equipment 19 is, for example, equipment that filters the first cleaning wastewater (first cleaning wastewater discharged from the filtration equipment 16) supplied from the wastewater pond 18 via the line L15. The line L15 is, for example, a pipe that connects the wastewater pond 18 and the filtration equipment 19. Specifically, the filtration equipment 19 is, for example, a sand filtration equipment that performs sand filtration, or a membrane filtration equipment having a filtration membrane made of a microfiltration membrane, an ultrafiltration membrane, a reverse osmosis membrane, or the like, and may be equipment that performs filtration alone or in combination depending on the water quality of the water to be treated.

[0028] The wastewater reservoir 20 is, for example, a tank that stores the first cleaning wastewater (first cleaning wastewater after filtering in the filtration equipment 19) discharged from the filtration equipment 19 via a line L16. The line L16 is, for example, a pipe that connects the filtration equipment 19 and the wastewater reservoir 20. In this case, the first cleaning wastewater stored in the wastewater reservoir 20 is returned to the receiving well 12 via a line L17. The line L17 is, for example, a pipe that connects the wastewater reservoir 20 and the receiving well 12.

[0029] Furthermore, the filtration equipment 19 periodically, for example, once a day, backwashes the filter body by using a portion of the treated water filtered by the filtration equipment 16. Hereinafter, the wastewater discharged in association with the backwashing of the filtration equipment 19 is also referred to as "washing wastewater" or "second washing wastewater." In this case, the wastewater reservoir 20 stores the second washing wastewater discharged from the filtration equipment 19 via, for example, line L16. Thereafter, solids (solids that tend to settle) contained in the second washing wastewater stored in the wastewater reservoir 20 are discharged, for example, by an extraction device (not shown) via line L18 to the concentration dehydrator 21, where they are concentrated and dehydrated, and then used as a resource or disposed of in a landfill. The line L18 is, for example, a pipe connecting the wastewater reservoir 20 and the concentration dehydrator 21. The suspended water from which the solids (solids that tend to settle) contained in the second washing wastewater stored in the wastewater reservoir 20 have been removed is returned to the receiving well 12 via, for example, line L17.

[0030] Furthermore, when the operation of each piece of equipment (e.g., filtration equipment 16) included in the water treatment system 100 stops due to a power outage caused by a natural disaster or the like, the filtration equipment 19 continues operation by using power stored in an emergency power supply (not shown). The filtration equipment 19 generates treated water (hereinafter also referred to as second treated water or second purified water) by filtering the water to be treated supplied from the receiving well 12 via, for example, line L21 and a part of line L15. The line L21 is, for example, a pipe connecting the receiving well 12 and line L15. The purified water reservoir 17 stores the treated water supplied from the filtration equipment 19 via, for example, line L22. The line L22 is, for example, a pipe connecting the filtration equipment 19 and the purified water reservoir 17. The treated water stored in the purified water reservoir 17 is then supplied to homes or the like via, for example, a distribution reservoir. Hereinafter, the timing when the operation of equipment such as the filtration equipment 16 stops is also referred to as equipment shutdown.

[0031] In addition, the filtration equipment 19 may also filter the water to be treated supplied from the chemical mixing tank 13 via line L12, the drainage tank 18, and a part of line L15, the water to be treated supplied from the flocculation tank 14 via line L13, the drainage tank 18, and a part of line L15, and the water to be treated supplied from the sedimentation tank 15 via line L14, the drainage tank 18, and a part of line L15, for example, when the operation of the equipment included in the water treatment system 100 stops due to a power outage caused by a natural disaster or the like.

[0032] The chemical supply equipment 22 is, for example, equipment that supplies a coagulant or chlorine to the water to be treated from line L24 when the equipment is stopped, and is equipment that performs coagulation of suspended solids, sterilization, etc. Line L24 is, for example, a pipe that connects the chemical supply equipment 22 to line L15 (downstream of the junction of line L15 with line L21). The chemical supply equipment 22 may also be equipment that removes odorous substances and harmful substances contained in the water to be treated by, for example, supplying activated carbon (mainly powdered activated carbon) to the water to be treated. The chemical supply equipment 22 may also be equipment that sterilizes the water to be treated and decomposes odorous substances and harmful substances contained in the water to be treated by, for example, supplying ozone.

[0033] Specifically, the chemical supply facility 22 includes, for example, an ozone generator (not shown) that generates ozone, and a valve (not shown) that adjusts the injection amount of ozone gas or ozone-dissolved water generated by the ozone generator. Hereinafter, the flocculant, chlorine, activated carbon, and ozone are collectively referred to simply as flocculants, etc.

[0034] The fresh water production system 1000 may have two or more chemical supply facilities 22, for example, a chemical supply facility 22 that supplies a coagulant or chlorine, a chemical supply facility 22 that supplies activated carbon, and a chemical supply facility 22 that supplies ozone.

[0035] Furthermore, a mixer (not shown) may be provided at the connection between the line L24 and the line L15 to mix the water to be treated supplied from the line L15 with the coagulant and chlorine supplied from the line L24. This enables the fresh water production system 1000 to efficiently perform the treatment performed in the filtration equipment 19, for example.

[0036] That is, in the fresh water production system 1000 of this embodiment, if the operation of each facility included in the water treatment system 100 stops due to a power outage caused by the occurrence of a natural disaster or the like, filtration of the water to be treated (the water to be treated from the receiving well 12) begins by using the filtration facility 19. In other words, in this case, in the fresh water production system 1000, for example, the filtration facility 19 that filters the first washing wastewater during backwashing is reused as the facility that filters the water to be treated.

[0037] This allows the fresh water production system 1000 in this embodiment to continue producing treated water, for example, even when the equipment is stopped. Specifically, the fresh water production system 1000 can continue producing the minimum required amount of treated water (for example, an amount of treated water equivalent to drinking water for homes, etc.) even when the equipment is stopped.

[0038] Furthermore, the amount of water to be treated that is filtered by the filtration equipment 16 during normal operation is greater than the amount of first washing wastewater that is filtered by the filtration equipment 19 during backwashing. Therefore, the filtration capacity (filtration capacity per unit time) of the filtration equipment 16 is usually designed to be greater than the filtration capacity (filtration capacity per unit time) of the filtration equipment 19. Therefore, the power consumption required to operate the filtration equipment 19 is usually less than the power consumption required to operate the filtration equipment 16.

[0039] Therefore, in the fresh water production system 1000 of this embodiment, for example, when the equipment is stopped, it is possible to continue producing treated water with less power than during normal operation. Therefore, even when the equipment is stopped, the fresh water production system 1000 can continue producing treated water by using an emergency power supply that has stored electricity in advance using renewable energy or a generator that uses sunlight as a power supply source.

[0040] Furthermore, in the fresh water production system 1000 of this embodiment, for example, by producing treated water using the filtration equipment 19 when the equipment is stopped, there is no need to separately provide other equipment for filtering the water to be treated when the equipment is stopped. Therefore, in the fresh water production system 1000, it is possible to reduce the introduction costs and operating costs of each equipment, for example.

[0041] [Control device 200 in the first embodiment] Fig. 2 is a diagram illustrating the hardware configuration of the control device 200. Fig. 3 is a diagram illustrating the functions of the control device 200. Hereinafter, lines L1, L2, L3, L4, L5, L6, L7, L8, L11, L12, L13, L14, L15, L16, L17, L18, L21, L22, L23, L24, and L25 will also be collectively referred to simply as lines L or supply units L.

[0042] As shown in Figure 2, the fresh water production system 1000 has a control device 200 that performs control (hereinafter also referred to as purified water production control) to produce treated water from the water to be treated, for example, by controlling pumps (not shown) provided in each line L and valves (not shown) provided in each line L.

[0043] Specifically, the control device 200 executes, for example, purified water production control, a control to generate treated water by filtering water to be treated using the filtration equipment 16 (hereinafter also referred to as first control), a control to backwash the filtration equipment 16 (hereinafter also referred to as second control), and a control to generate treated water by filtering water to be treated using the filtration equipment 19 (hereinafter also referred to as third control). That is, the first control is, for example, a control that is performed during normal operation. The second control is, for example, a control that is performed during backwashing. Furthermore, the third control is, for example, a control that is performed when the equipment is stopped.

[0044] 3, the control device 200 is, for example, an electronic device having an electronic circuit. Specifically, the control device 200 is, for example, a computer device having a CPU 201 which is a processor, a memory 202, a communication device 203, and a storage medium 204. Each unit is connected to each other via a bus 205, for example.

[0045] The storage medium 204 has, for example, a program storage area (not shown) that stores a program 210 for performing purified water generation control. The storage medium 204 also has, for example, an information storage area 230 that stores information used when performing purified water generation control. The storage medium 204 may be, for example, a hard disk drive (HDD) or a solid state drive (SSD).

[0046] The CPU 201 controls purified water production by executing a program 210 loaded into the memory 202 from the storage medium 204, for example.

[0047] The communication device 203 accesses an operation terminal (not shown) through which an operator inputs necessary information, for example, via a network (not shown) such as the Internet.

[0048] The control device 200 may have, for example, an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The control device 200 may also include, for example, a PIC (Peripheral Interface Controller). The purified water generation control may be executed by, for example, the FPGA or the ASIC.

[0049] [Purified Water Generation Control in the First Embodiment] Next, purified water generation control in the first embodiment will be described. Figures 4 and 5 are flow charts explaining purified water generation control in the first embodiment. Figures 6 to 8 are diagrams explaining purified water generation control in the first embodiment.

[0050] [Purified water generation control when switching between first control and second control] First, purified water generation control when switching between first control and second control is described. Figure 4 is a flowchart illustrating switching between first control and second control. In the following, a line represented by a solid line indicates that a valve provided on the line is open. In the following, a line represented by a dashed line indicates that a valve provided on the line is closed. In the following, an initial state is described as the valves provided on lines L1, L2, L3, L4, L5, L6, L7, and L8 are open, as shown in Figure 6.

[0051] The control device 200 performs, for example, a first control on the water treatment system 100 (step S1 in FIG. 4).

[0052] Specifically, the control device 200 controls pumps provided on lines L1, L2, L3, L4, L5, L6, L7, and L8, for example, to supply the treated water to the grit basin 11, the receiving well 12, the chemical mixing basin 13, the flocculation basin 14, the sedimentation basin 15, the filtration equipment 16, and the purified water basin 17 in this order, as shown by the solid lines in Figure 6.

[0053] That is, in this case, the control device 200 generates treated water from the water to be treated by filtering the water to be treated in the filtration equipment 16, for example.

[0054] Then, when it is time for backwashing, the control device 200, for example, shifts the control of the water treatment system 100 from the first control to the second control (step S2 in FIG. 4, step S3 in FIG. 4).

[0055] Specifically, for example, as shown by the solid lines in Figure 7, when at least one of the valves provided on line L11, line L15, line L16, and line L17 is closed, the control device 200 controls these valves to open.

[0056] Subsequently, the control device 200 performs, for example, a second control on the water treatment system 100 (step S4).

[0057] Specifically, the control device 200 performs backwashing in the filtration equipment 16, as shown by the solid lines in Figure 7, and controls the pumps provided on lines L11, L15, L16 and L17, thereby supplying the first cleaning wastewater discharged from the filtration equipment 16 to the wastewater pond 18, the filtration equipment 19, the clean water pond 17, the wastewater pond 20 and the receiving well 12 in that order.

[0058] The control device 200 may also be configured to control the opening of at least one of the valves provided on the lines L12, L13, and L14 when these valves are closed in step S3, as shown by the solid lines in Fig. 7. The control device 200 may also be configured to supply the untreated water discharged from at least one of the chemical mixing basin 13, the flocculation basin 14, and the sedimentation basin 15 to the wastewater basin 20 together with the first washing wastewater in step S4, as shown by the solid lines in Fig. 7.

[0059] Furthermore, when the water treatment system 100 has a plurality of filtration equipment 16, the control device 200 may, for example, in step S3, transition the control of some of the filtration equipment 16 to the second control, while maintaining the control of some of the other filtration equipment 16 under the first control. Specifically, for example, when the water treatment system 100 has four filtration equipment 16, the control device 200 may transition the control of one filtration equipment 16 to the second control, while maintaining the control of the remaining three filtration equipment 16 under the first control. In other words, the control device 200 may continue to produce treated water even during backwashing, for example.

[0060] Furthermore, the control device 200 may perform backwashing of the filtration equipment 19 in step S4, for example, together with or instead of backwashing of the filtration equipment 16. Specifically, the control device 200 may also perform control to open a valve provided on line L18 when the valve is closed in step S3, for example, as shown in the solid line portion of Fig. 7. The control device 200 then performs backwashing of the filtration equipment 19 in step S4, as shown in the solid line portion of Fig. 7, and controls the pumps provided on lines L16, L17, and L18, thereby supplying solids contained in the second cleaning wastewater discharged from the filtration equipment 16 to the wastewater tank 20 and the thickening / dehydrating machine 21 in that order, and supplying suspended solids from which solids (solids that easily settle) contained in the second cleaning wastewater discharged from the filtration equipment 16 have been removed to the wastewater tank 20 and the receiving well 12 in that order.

[0061] Thereafter, when normal operation resumes, that is, when backwashing is completed, the control device 200, for example, transitions the control of the water treatment system 100 from the second control to the first control (step S5 in FIG. 4, step S6 in FIG. 4).

[0062] Specifically, the control device 200, for example, sets the open / closed states of the valves provided in each line to the same states as those described with reference to FIG.

[0063] [Purified water generation control when switching between first control and third control] Next, the purified water generation control when switching between the first control and the third control will be described. Fig. 5 is a flowchart illustrating the switching between the first control and the third control.

[0064] The control device 200 performs, for example, a first control on the water treatment system 100 (step S11 in FIG. 5).

[0065] Specifically, the control device 200 controls the pumps provided on lines L1, L2, L3, L4, L5, L6, L7, and L8, as described in step S1 of Figure 4, to supply the treated water to the settling tank 11, the receiving well 12, the chemical mixing tank 13, the flocculation tank 14, the sedimentation tank 15, the filtration equipment 16, and the purified water tank 17 in that order.

[0066] When the equipment is stopped, the control device 200, for example, shifts the control of the water treatment system 100 from the first control to the third control (step S12 in FIG. 5, step S13 in FIG. 5).

[0067] Specifically, for example, as shown by the solid lines in Figure 8, when at least one of the valves provided on line L21, part of line L15, line L22 and line L23 is closed, the control device 200 controls these valves to open.

[0068] Next, the control device 200 performs, for example, a third control on the water treatment system 100 (step S14).

[0069] Specifically, the control device 200 controls the pumps provided on lines L1, L2, L21, part of line L15, line L22 and line L23, as shown by the solid lines in Figure 8, so that the treated water is supplied to the settling tank 11, the receiving well 12 and the filtration equipment 19 in that order, and the treated water is supplied to the purified water tank 17.

[0070] The treated water may be supplied directly from the line L25 to a vehicle or the like (not shown) having a storage tank. That is, the treated water may be transported directly by a vehicle or the like having a storage tank without passing through the line L22 or the line L23.

[0071] In other words, if the function of the filtration equipment 16 (the function of the water treatment system 100 including the filtration equipment 16) is reduced or stopped due to a power outage caused by a natural disaster, for example, the control device 200 causes the filtration of the water to be treated to be performed by the filtration equipment 19 instead of the filtration equipment 16.

[0072] In this case, the control device 200 may also supply the water to be treated stored in each facility (e.g., filtration facility 16) of the water treatment system 100 to the filtration facility 19. In other words, the filtration facility 19 may also use the water to be treated stored in each facility of the water treatment system 100 to produce treated water.

[0073] Specifically, the control device 200 may, for example, control at least one of the valves provided on lines L11, L12, L13, and L14 to open these valves when the valve is closed. The control device 200 may, for example, control pumps provided on lines L11, L12, L13, and L14 to supply the untreated water stored in the chemical mixing basin 13, the flocculation basin 14, the sedimentation basin 15, and the filtration equipment 16 to the wastewater basin 18. Furthermore, the control device 200 may, for example, control the pump provided on line L15 to supply the untreated water stored in the wastewater basin 18 to the filtration equipment 19.

[0074] In this case, the control device 200 may acquire a measurement value for the treated water from a measuring device (not shown) provided in equipment downstream of the line L22 or the filtration equipment 19. The measuring device is, for example, a turbidity meter that measures the turbidity of the treated water after filtration in the filtration equipment 19. The control device 200 may then supply a flocculant or the like from the chemical supply equipment 22 (increase the amount of flocculant or the like supplied from the chemical supply equipment 22) when the acquired measurement value (e.g., turbidity) is equal to or greater than a threshold value.

[0075] That is, for example, if the control device 200 determines that the water quality of the treated water after filtration in the filtration equipment 19 does not meet a predetermined standard (hereinafter simply referred to as the standard), it controls the water quality of the treated water to meet the standard by supplying a coagulant, etc. (increasing the supply amount of coagulant, etc.).

[0076] This allows the control device 200 to generate treated water that meets the standards even when the facility is stopped, for example.

[0077] Thereafter, when normal operation resumes, i.e., when the filtering function of the filtering equipment 16 is restored upon recovery from the power outage, the control device 200, for example, transitions the control of the water treatment system 100 from the third control to the first control (step S15 in Figure 5, step S16 in Figure 5).

[0078] Specifically, the control device 200, for example, sets the open / closed states of the valves provided in each line to the same states as those described with reference to FIG.

[0079] As such, the fresh water production system 1000 in this embodiment includes, for example, a filtration equipment 16 that filters raw water, a filtration equipment 19 that filters the raw water or the first cleaning wastewater discharged from the filtration equipment 16 in connection with cleaning the filtration equipment 16, and a supply unit L that can supply raw water to the filtration equipment 16, can supply the first cleaning wastewater from the filtration equipment 16 to the filtration equipment 19, and can supply raw water to the filtration equipment 19.

[0080] The fresh water production system 1000 in this embodiment also includes, for example, a control device 200 that controls the supply unit L. The control device 200 performs, for example, one of a first control of supplying raw water to the filtration equipment 16 to cause the filtration equipment 16 to produce first purified water, a second control of stopping the supply of raw water to the filtration equipment 16 and supplying first wash wastewater to the filtration equipment 19, and a third control of stopping the supply of raw water to the filtration equipment 16 and supplying raw water to the filtration equipment 19 to cause the filtration equipment 19 to produce second purified water.

[0081] That is, in the fresh water production system 1000 of this embodiment, for example, when the timing for stopping the equipment comes, the filtration equipment 19 that filters the first cleaning wastewater at the timing for backwashing is reused as equipment for filtering the water to be treated.

[0082] This allows the fresh water production system 1000 in this embodiment to continue producing treated water, for example, even when the equipment is shut down. Specifically, the fresh water production system 1000 can continue producing the minimum required amount of treated water (for example, an amount of treated water equivalent to drinking water for homes, etc.) even when the equipment is shut down.

[0083] Furthermore, in the fresh water production system 1000, for example, by producing treated water using the filtration equipment 19 when the equipment is stopped, there is no need to separately prepare other equipment that filters the water to be treated when the equipment is stopped. Therefore, in the fresh water production system 1000, for example, it is possible to reduce the introduction costs and operating costs of each equipment. [Explanation of symbols]

[0084] 11: Sand basin 12: Landing well 13: Chemical mixing tank 14: Flocculation tank 15: Sedimentation tank 16: Filtration tank 17: Clean water reservoir 18: Wastewater reservoir 19: Filtration equipment 20: Drainage pond 21: Concentration and dehydration machine 22: Chemical supply equipment 100: Water treatment system 200: Control device 201:CPU 202:Memory 203: Communication equipment 204: Storage medium 205: Bus 210: Program 230: Information storage area 1000: Water production system L1: Line L2: Line L3: Line L4: Line L5: Line L6: Line L7: Line L8: Line L11: Line L12: Line L13: Line L14: Line L15: Line L15: Line L16: Line L17: Line L18: Line L21: Line L22: Line L23: Line L24: Line L25: Line

Claims

1. a first filtration device for filtering raw water; a second filtration device that filters the raw water or cleaning wastewater discharged from the first filtration device in association with cleaning of the first filtration device; a supply unit capable of supplying the raw water to the first filtration equipment, supplying the cleaning wastewater from the first filtration equipment to the second filtration equipment, and supplying the raw water to the second filtration equipment.

2. Further, a control device for controlling the supply unit is provided, 2. The freshwater production system according to claim 1, wherein the control device performs one of a first control for supplying the raw water to the first filtration equipment to cause the first filtration equipment to produce first purified water, a second control for stopping the supply of the raw water to the first filtration equipment and supplying the cleaning wastewater to the second filtration equipment, and a third control for stopping the supply of the raw water to the first filtration equipment and supplying the raw water to the second filtration equipment to cause the second filtration equipment to produce second purified water.

3. A fresh water production method in a fresh water production system including a first filtration equipment that filters raw water, a second filtration equipment that filters the raw water or washing wastewater discharged from the first filtration equipment in association with washing of the first filtration equipment, and a supply unit that can supply the raw water to the first filtration equipment, can supply the washing wastewater from the first filtration equipment to the second filtration equipment, and can supply the raw water to the second filtration equipment, A fresh water production method comprising: performing one of a first control for supplying the raw water to the first filtration equipment to cause the first filtration equipment to produce first purified water; a second control for stopping the supply of the raw water to the first filtration equipment and supplying the cleaning wastewater to the second filtration equipment; and a third control for stopping the supply of the raw water to the first filtration equipment and supplying the raw water to the second filtration equipment to cause the second filtration equipment to produce second purified water.

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