Self-cleaning type filtration facility and cleaning method of the same

Abstract

To improve recovery efficiency of treated water treated through a precipitation facility in a previous step.SOLUTION: In a self-cleaning type filtration facility 10, raw water is supplied from a raw water passage 16 to filter basins 12 and filtrate water filtered by a filter layer 30 of each filter basin is collected into a filter adjustment tank 20 to be supplied to a next step. Then, a water level of the filter basin to be cleaned is lowered to a level lower than a water level of the filter adjustment tank to back wash the filter layer of the filter basin to be cleaned with filtrate water of the filter adjustment tank. The self-cleaning type filtration facility includes: a filtrate water storage tank 22 in which raw water discharged when the water level of the filter basin to be cleaned is lowered is filtered and stored; and a storage tank outflow pump 24 which supplies the filtrate water in the filtrate water storage tank to a surface cleaning device 28 configured to clean a surface of the filter layer and supplies the filtrate water to the raw water passage 16.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a self-cleaning filtration facility in which the filter layer of a filtration basin to be cleaned is back-washed with filtrate water from a filtration adjustment tank, and a cleaning method thereof. [Background technology]

[0002] For example, Patent Document 1 discloses a self-cleaning filtration system in which the cleaning water for backwashing one line of filtration equipment is performed using filtrate treated in another line of filtration equipment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-226311 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional self-cleaning filtration equipment, the raw water in the filtration basin is discharged to lower the water level in the filtration basin. The raw water in the filtration basin is treated through a pre-processing settling equipment, and discharging this water will reduce the recovery efficiency of the treated water. In addition, the wastewater treatment also requires energy and does not save energy.

[0005] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide a self-cleaning filtration equipment and a cleaning method thereof that can improve the recovery efficiency of treated water that has been treated through a sedimentation equipment in a previous process. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a self-cleaning filtration equipment which supplies raw water from a raw water conduit to a plurality of filtration basins, collects the filtrate filtered through the filter layers of each filtration basin in a filtration adjustment tank and supplies it to a next process, lowers the water level of the filtration basin to be cleaned below the water level of the filtration adjustment tank, and backwashes the filter layers of the filtration basin to be cleaned with the filtrate water from the filtration adjustment tank, and is characterized in comprising a filtrate water storage tank which filters and stores the raw water discharged when the water level of the filtration basin to be cleaned is lowered, and a storage tank outflow pump which supplies the filtrate water in the filtrate water storage tank to a surface washing device which washes the surfaces of the filter layers and also supplies it to a raw water conduit.

[0007] According to the present invention, raw water discharged when the water level of the filter basin to be cleaned is lowered can be filtered and temporarily stored in the filtered water storage tank. In this embodiment, the filtered water stored in the filtered water storage tank is pumped up by the driving action of the storage tank outlet pump and supplied to the surface washing device, and is also pumped up by the driving action of the storage tank outlet pump and supplied to the raw water conduit. As a result, in the present invention, it is no longer necessary to discharge raw water discharged when the water level of the filter basin to be cleaned is lowered to the outside as in the conventional method, and a decrease in the recovery efficiency of the filtered water can be avoided.

[0008] The present invention also provides a method for cleaning a self-cleaning filtration equipment, which includes a filtration process in which raw water is supplied from a raw water conduit to a plurality of filtration basins, and the filtrate filtered through the filter layers of each filtration basin is collected in a filtration adjustment tank and supplied to a next process, and a backwashing process in which the water level of the filtration basin to be cleaned is lowered below the water level of the filtration adjustment tank and the filter layers of the filtration basin to be cleaned are backwashed with the filtrate water from the filtration adjustment tank. The method includes a water level lowering process in which raw water discharged when the water level of the filtration basin to be cleaned is lowered and the raw water is stored in a filtrate water storage tank, a surface washing process in which the filtrate water from the filtrate water storage tank is supplied to a surface washing device that washes the surface of the filter layer, and a return process in which the filtrate water from the filtrate water storage tank is supplied to the raw water conduit, and the filtration layer is backwashed with the filtrate water from the filtration adjustment tank during the surface washing process.

[0009] According to the present invention, raw water discharged when the water level of the filter basin to be washed is lowered can be filtered and temporarily stored in the filtered water storage tank. The filtered water stored in the filtered water storage tank is supplied to the surface washing device and also to the raw water conduit. As a result, the present invention makes it unnecessary to discharge raw water discharged when the water level of the filter basin to be washed is lowered to the outside as in the conventional method, and it is possible to avoid a decrease in the recovery efficiency of the filtered water and achieve energy savings. Effect of the Invention

[0010] According to the present invention, it is possible to obtain a self-cleaning filtration facility and a cleaning method thereof that can improve the recovery efficiency of treated water that has been treated through a sedimentation facility in a previous process. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of a water purification system to which a self-cleaning filtration facility according to an embodiment of the present invention is applied. [Diagram 2] FIG. 2 is a schematic diagram of the water purification system shown in FIG. 1 during a filtration process. [Diagram 3] FIG. 2 corresponds to FIG. 1 and is a schematic diagram showing the water level lowering process. [Figure 4] FIG. 3 corresponds to FIG. 2 and is a schematic diagram showing the water level lowering process. [Diagram 5] FIG. 2 corresponds to FIG. 1 and is a schematic diagram showing a backwashing step. [Figure 6] FIG. 3 corresponds to FIG. 2 and is a schematic diagram showing the backwashing process. [Figure 7] This corresponds to Figure 1 and is a schematic diagram showing the water draining process. [Figure 8] 4 is a table showing the operation states of various valves and gates in each process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In Fig. 1 to Fig. 7, various valves depicted in white indicate that they are in an open state, and various valves depicted in black indicate that they are in a closed state.

[0013] A water purification system to which the self-cleaning filtration equipment 10 according to the embodiment of the present invention is applied includes a grit basin (not shown), a receiving well (also called a raw water tank depending on the equipment), a rapid mixing tank (mixing tank), a flocculation basin, a sedimentation basin, and the self-cleaning filtration equipment 10 (hereinafter simply referred to as the filtration equipment 10). The sedimentation basin is disposed downstream of the flocculation basin. The flocculation basin is a facility that uses a flocculator to slowly stir small flocs produced in the rapid mixing basin (not shown) to turn them into large flocs that are easy to settle.

[0014] 1 and 2, the filtration equipment 10 includes a plurality of filtration basins 12 (see FIG. 2), a raw water conduit 16, a drainage conduit 18, a filtration adjustment tank 20, a filtrate water storage tank 22, and a storage tank outflow pump 24. In this embodiment, as shown in FIG. 2, four filtration basins 12 having the same structure are depicted, but the number is not limited thereto.

[0015] As shown in FIG. 1, each filter basin 12 is provided with a drainage trough 26 arranged in the vertical middle of the filter basin 12, a surface washing device 28 arranged below the drainage trough 26, a filter layer 30 made of a filter material arranged below the surface washing device 28, and a water collection device 32 arranged below the filter layer 30.

[0016] The drainage trough 26 is configured, for example, as a drainage groove formed of a U-shaped groove (see FIG. 2). The lower bottom wall of the drainage trough 26 is configured as an inclined surface that slopes downward from the raw water conduit 16 side toward the drainage conduit 18 side (see FIG. 1). The lower bottom wall of the drainage trough 26 may be configured as a flat surface without being inclined.

[0017] 1, the surface washing device 28 is arranged at a predetermined distance from the upper surface of the filter bed 30 and is composed of a surface washing pipe 36 having a plurality of nozzles 34 for spraying water onto the upper surface of the filter bed 30, and a surface washing valve 38 provided at the end of a branch pipe branching off from the surface washing pipe 36 and for starting and stopping the supply of water into the surface washing pipe 36. The surface washing valve 38 is provided with an opening / closing device 38a for opening and closing the surface washing valve 38.

[0018] The water collecting device 32 is disposed under the filter basin 12, and is a device for collecting the filtrate water and dispersing the backwash cleaning water uniformly. The water collecting device 32 can exert an excellent cleaning effect on the filter layer (filter material) 30 by uniformly dispersing the backwash cleaning water.

[0019] The raw water conduit 16 is a channel through which raw water flows, and supplies the raw water to the filtration basin 12. This raw water has been treated through a previous process of sedimentation equipment (not shown). An inlet 40a is formed between the raw water conduit 16 and the filtration basin 12 to supply raw water to the filtration basin 12. A raw water inlet gate 40 for opening and closing the inlet 40a and a raw water inlet gate opening and closing device 42 for opening and closing the raw water inlet gate 40 are provided.

[0020] The drainage culvert 18 temporarily stores wastewater (such as backwash wastewater, which will be described later) from the filter basin 12. Between the filter basin 12 and the drainage culvert 18, a drainage outlet 44a is formed to discharge the wastewater from the filter basin 12 into the drainage culvert 18, and a drainage gate 44 for opening and closing the drainage outlet 44a and a drainage gate opening / closing device 46 for opening and closing the drainage gate 44 are provided. The drainage gate 44 is disposed at the same or approximately the same height as the downstream end of the drainage trough 26 in the vertical direction. The drainage culvert 18 is connected to the drainage basin.

[0021] 1, a wastewater outlet 48a is formed between the drainage culvert 18 and the water collection device 32 below the filter basin 12, and discharges wastewater from the filter basin 12 into the drainage culvert 18. A wastewater valve 48 is provided for opening and closing the wastewater outlet 48a, and a wastewater valve opening / closing device 50 is provided for opening and closing the wastewater valve 48. The wastewater valve 48 is opened when the wastewater process described below starts, and closed when the wastewater process stops (ends).

[0022] The filtration adjustment tank 20 collects the filtered water filtered by the filter layers 30 of each filtration basin 12 and supplies it to the next process. The filtration adjustment tank 20 is connected to a water distribution reservoir via a purified water reservoir (see FIG. 1). A first communication passage 52 is provided between the filtration basin 12 and the filtration adjustment tank 20 to communicate between them. A purified water valve 54 that opens and closes the first communication passage 52 is disposed midway along the first communication passage 52. The purified water valve 54 is provided with an opening / closing device 54a that opens and closes the purified water valve 54.

[0023] As shown in Fig. 1, a branch passage 56 branching off from the first communication passage 52 is provided between the filtration basin 12 (water collection device 32) and the purified water valve 54. The branch passage 56 is connected to the filtrate water storage tank 22 via a storage tank inlet valve 58. The filtrate water storage tank 22 filters and temporarily stores raw water discharged when lowering the water level of the filtration basin 12 to be cleaned. The storage tank inlet valve 58 opens and closes the branch passage 56. The storage tank inlet valve 58 is provided with an opening / closing device 58a that opens and closes the storage tank inlet valve 58.

[0024] A storage tank outflow pump 24 is connected to the downstream side of the filtered water storage tank 22. This storage tank outflow pump 24 pumps up the filtered water stored in the filtered water storage tank 22 and supplies it to a surface washing device 28 as described below, and also supplies (returns) it to the raw water conduit 16.

[0025] Between the filtrate water storage tank 22 and the storage tank outflow pump 24, a second communication passage 60 is provided to communicate the filtrate water storage tank 22 and the storage tank outflow pump 24. In addition, between the storage tank outflow pump 24 and the raw water conduit 16, a third communication passage 62 is provided to communicate the storage tank outflow pump 24 and the raw water conduit 16. A raw water conduit return valve 64 for opening and closing the third communication passage 62 is provided in the middle of the third communication passage 62. Furthermore, a fourth communication passage 66 is provided to communicate the storage tank outflow pump 24 and the surface washing device 28 of the filtration basin 12. The raw water conduit return valve 64 is provided with an opening / closing device 64a for opening and closing the raw water conduit return valve 64.

[0026] The storage tank outflow pump 24, under the driving action of a motor not shown, pumps up the filtrate water stored in the filtrate water storage tank 22, supplies the filtrate water to the surface washing device 28 that washes the surface of the filter layer 30, and also supplies the filtrate water to the raw water conduit 16. That is, the filtrate water stored in the filtrate water storage tank 22 is pumped up under the driving action of the storage tank outflow pump 24, and is supplied to the surface washing device 28 via the second communication passage 60 and the fourth communication passage 66. At the same time or subsequently, the filtrate water stored in the filtrate water storage tank 22 is pumped up under the driving action of the storage tank outflow pump 24, and is supplied to the raw water conduit 16 via the second communication passage 60 and the third communication passage 62.

[0027] The water purification system to which the self-cleaning filtration equipment 10 according to this embodiment is applied is basically configured as described above, and its operation and effects will be described below. In each process, the operation states of the various valves and gates are performed based on the table shown in FIG.

[0028] The operation of the filtration equipment 10 will be described in detail below. In the valve / gate operation table shown in Fig. 8, which shows the operation states of various valves and gates, the circled numbers 1 to 4 respectively indicate the order of operation in various processes.

[0029] First, a "filtration process" is performed to remove impurities from raw water (see Figs. 1 and 2). In this filtration process, the raw water inflow gate opening / closing device 42 is driven to open the raw water inflow gate 40, and the purified water valve 54 is opened. In this case, the drain gate 44 is closed, and all other valves are closed. When the raw water inflow gate 40 is opened, raw water is supplied from the raw water conduit 16 to each filter basin 12. The raw water supplied from the raw water conduit 16 to each filter basin 12 is filtered by the filter layer 30, and collected in the filtration adjustment tank 20 via the first communication passage 52, and is supplied to the next process.

[0030] During the filtration process, the filter layer 30 gradually becomes clogged, so in order to maintain a constant filtration rate, the water depth above the filter layer 30 gradually increases. The difference between the water level in the filter basin 12 and the water level in the filtration adjustment tank 20 indicates the filtration resistance at that time. As filtration progresses, the filter layer 30 becomes clogged due to turbidity in the raw water, and in response, the water depth above the filter layer 30 continues to rise until it reaches a predetermined water level or when a preset timer is triggered, the filtration process ends.

[0031] After the filtration process is completed, a "water level lowering process" is performed in which the water level of the raw water in the filtration basin 12 to be cleaned is lowered below the water level in the filtration adjustment tank 20 (see Figs. 3 and 4). Here, an example is shown of cleaning the filtration basin 12 located at the leftmost position in Fig. 4. At the start of this water level lowering process, the raw water inlet gate 40 is switched from an open state to a closed state, and the purified water valve 54 is switched from an open state to a closed state. At the start of the water level lowering process, the storage tank inlet valve 58 in the branch passage 56 is switched from a closed state to an open state. When the water level in the filtration basin 12 has lowered to the surface of the filter layer 30, the storage tank inlet valve 58 is switched from an open state to a closed state.

[0032] In the water level lowering process, the storage tank inlet valve 58 is opened, and the raw water in the filtration tank 12 is supplied to the filtrate water storage tank 22 via the first communication passage 52 and the branch passage 56 and temporarily stored therein. In this embodiment, when the water level of the raw water in the filtration tank 12 to be cleaned is lowered below the water level in the filtration adjustment tank 20, the raw water in the filtration tank 12 is not discharged to the outside, but is stored in the filtrate water storage tank 22. In this embodiment, the water level lowering process ends when the water level in the filtration tank 12 falls to the surface of the filter layer 30 (below the drainage trough 26).

[0033] Next, a "cleaning step" is performed to clean the filter layer 30 of the filter basin 12 to be cleaned (see Figs. 5 and 6). This cleaning step is broadly divided into a "surface cleaning step", a "surface cleaning step" + "backwashing step", and a "backwashing step". The "surface cleaning step" is a step in which water is supplied from above the filter layer 30 to clean the upper layer of the filter layer 30. The backwashing step is a step in which water is supplied from below the filter layer 30 to clean the entire filter layer 30.

[0034] First, at the start of the cleaning process, only the surface cleaning process is performed. In this surface cleaning process, the drain gate opening / closing device 46 is driven to switch the drain gate 44 from a closed state to an open state. Then, the surface cleaning valve 38 of the surface cleaning device 28 is switched from a closed state to an open state. Furthermore, the motor of the storage tank outflow pump 24 is driven to operate the storage tank outflow pump 24. In this surface cleaning process, the filtered water stored in the filtered water storage tank 22 by the storage tank outflow pump 24 is supplied to the surface cleaning valve 38 of the surface cleaning device 28 through the second communication passage 60 and the fourth communication passage 66 (see FIG. 6). Since the surface cleaning valve 38 is in an open state, the filtered water stored in the filtered water storage tank 22 is discharged into the surface cleaning pipe 36 and sprayed from the multiple nozzles 34 toward the upper surface of the filter bed 30. As a result, the upper surface of the filter bed 30 is cleaned.

[0035] During the surface washing process, the purified water valve 54 is switched from a closed state to an open state. As a result, the filtered water in the filtration adjustment tank 20 is supplied to the water collecting device 32 arranged at the bottom of the filtration basin 12 via the first communication passage 52 (see FIG. 5). In the water collecting device 32, the filtered water in the filtration adjustment tank 20 is back-sprayed toward the bottom of the filter bed 30 to perform backwashing (surface washing process + backwashing process). Next, the surface washing valve 38 is switched from an open state to a closed state, cutting off the supply of filtered water to the surface washing device 28, stopping the surface washing process, and entering the backwashing process in which the filtered water is supplied only to the water collecting device 32. When the surface washing process stops, the raw water conduit return valve 64 is switched from a closed state to an open state, and the filtered water pumped up from the filtered water storage tank 22 by the storage tank outflow pump 24 is supplied (returned) to the raw water conduit 16 via the second communication passage 60 and the third communication passage 62 (see Figure 6).

[0036] In the backwash process (cleaning process), the clean water valve 54 is switched from an open state to a closed state, and the drain gate opening / closing device 46 is driven to switch the drain gate 44 from an open state to a closed state, thereby completing the "cleaning process" for cleaning the filter layer 30 of the filter basin 12 to be cleaned. When the filtered water in the filtrate water storage tank 22 runs out, the storage tank outflow pump 24 stops, and the raw water drain return valve 64 switches from an open state to a closed state.

[0037] Next, a "water disposal process" is performed in which the filtered water stored in the water collection device 32 of the filtration basin 12 is discharged into the drainage ditch 18 (see FIG. 7). At the start of this water disposal process, the water disposal valve 48 is switched from a closed state to an open state. Next, the raw water inflow gate opening / closing device 42 is driven to switch the raw water inflow gate 40 from a closed state to a half-open state. This causes the filtered water stored in the water collection device 32 of the filtration basin 12 to be discharged into the drainage ditch 18 via the water disposal port 48a. When the water disposal process is to be stopped, the water disposal valve 48 is switched from an open state to a closed state, and the raw water inflow gate opening / closing device 42 is driven to switch the raw water inflow gate 40 from a half-open state to a fully-open state.

[0038] After the water disposal process is completed, the process returns to the above-mentioned "filtration process" and then sequentially repeats the "water level lowering process" and "cleaning process (surface washing process, surface washing process + backwashing process, backwashing process)." When returning to the filtration process, the raw water inflow gate 40, which was in a half-open state, is switched to a fully open state, and the purified water valve 54 is switched from a closed state to an open state.

[0039] In this embodiment, the system is configured to include a filtered water storage tank 22 that filters and stores raw water discharged when the water level of the filter basin 12 to be washed is lowered, and a storage tank outflow pump 24 that supplies the filtered water in the filtered water storage tank 22 to a surface washing device 28 that washes the surface of the filter layer 30 and also supplies the filtered water to the raw water conduit 16.

[0040] In this embodiment, raw water discharged when the water level of the filter basin 12 to be cleaned is lowered can be filtered and temporarily stored in the filtered water storage tank 22. In this embodiment, the filtered water stored in the filtered water storage tank 22 is pumped up under the driving action of the storage tank outflow pump 24 and supplied to the surface washing device 28, and is also pumped up under the driving action of the storage tank outflow pump 24 and supplied to the raw water conduit 16. As a result, in this embodiment, it is no longer necessary to discharge raw water discharged when the water level of the filter basin 12 to be cleaned is lowered to the outside as in the conventional method, and a decrease in the recovery efficiency of the filtered water can be avoided. In addition, energy for the discharge treatment of raw water is no longer required, and energy saving can be achieved.

[0041] In this embodiment, the process includes a filtration process in which raw water is supplied from a raw water conduit 16 to a plurality of filtration basins 12, and the filtrate filtered through the filter layer 30 of each filtration basin 12 is collected in a filtration adjustment tank 20 and supplied to a next process; a water level lowering process in which raw water discharged when lowering the water level of the filtration basin 12 to be cleaned is filtered and stored in a filtrate water storage tank 22; a surface washing process in which the filtrate water in the filtrate water storage tank 22 is supplied to a surface washing device 28 that cleans the surface of the filter layer 30; a return process in which the filtrate water in the filtrate water storage tank 22 is supplied to the raw water conduit 16 during this surface washing process, while backwashing the filter layer 30 of the filtration basin 12 to be cleaned with the filtrate water in the filtration adjustment tank 20 (surface washing process + backwashing process), and a drainage process in which wastewater (backwash water) in the filtration basin 12 is drained to a drainage conduit 18.

[0042] As a result, in this embodiment, it is possible to avoid a decrease in the recovery efficiency of the filtered water and to achieve energy savings.

[0043] In this embodiment, the filtrate water in the filtrate water storage tank 22 is returned to the raw water conduit 16 in the return process. This is because the raw water in the filtration basin 12 is filtered by the filter layer 30 in the water level lowering process, but since the filtration speed is faster than in a normal filtration process, there is a risk that sufficient filtration processing will not be performed. For this reason, the filtrate water in the filtrate water storage tank 22 is returned to the raw water conduit 16 in the return process. The filtrate water returned to the raw water conduit 16 is filtered by the filtration basins 12 other than the filtration basin 12 to be washed.

[0044] Furthermore, in the conventional water level lowering step, the raw water in the filtration basin 12 is drained through the drainage trough 26, so the water level of the filtration basin 12 is lowered to the drainage trough 26. In contrast, in the water level lowering step in this embodiment, the water level of the filtration basin 12 can be lowered to the upper surface of the filter layer 30, which is below the drainage trough 26. As a result, in this embodiment, the cleaning efficiency in the surface washing step can be improved compared to the conventional method.

[0045] Furthermore, a self-cleaning filter basin is usually composed of eight basins, and the total water from the seven basins is used to ensure the amount of backwash water required to backwash one basin. In this embodiment, by newly providing the filtrate water storage tank 22, the amount of backwash water can be ensured, and the number of filter basins 12 can be reduced. This allows for greater freedom in the layout of each filter basin 12.

[0046] In this embodiment, the filtered water in the filtered water storage tank 22 is supplied to the surface washing device 28 by the storage tank outflow pump 24, and is supplied to the raw water conduit 16 after the surface washing process is completed, but if the capacity of the filtered water storage tank 22 is large, the water conveying force of the storage tank outflow pump 24 is large, and the surface washing process is not hindered, the filtered water in the filtered water storage tank 22 may be supplied to the raw water conduit 16 during the surface washing process. In addition, the opening and closing device 38a of the surface washing valve 38, the raw water inflow gate opening and closing device 42 of the raw water inflow gate 40, the drain gate opening and closing device 46 of the drain gate 44, the drain valve opening and closing device 50 of the drain valve 48, the opening and closing device 54a of the purified water valve 54, the opening and closing device 58a of the storage tank inflow valve 58, the opening and closing device 64a of the raw water conduit return valve 64, and the drive device of the storage tank outflow pump 24 are connected to a control device (not shown) and are operated by signals from the control device. This control device controls various devices using a water level sensor, timer, etc. (not shown) according to the valve / gate operation table shown in FIG. [Explanation of symbols]

[0047] 10 Self-cleaning filtration equipment 12 Filtration pond 16 Raw Water Channel 20 Filtration adjustment tank 22 Filtrate water storage tank 24 Reservoir Outflow Pump 28 Surface washing equipment 30 Layer

Claims

1. In a self-cleaning filtration system, raw water is supplied from a raw water conduit to a plurality of filtration basins, the filtrate filtered through the filtration layers of each filtration basin is collected in a filtration adjustment tank and supplied to the next process, the water level of the filtration basin to be cleaned is lowered below the water level of the filtration adjustment tank, and the filtration layer of the filtration basin to be cleaned is backwashed with the filtrate from the filtration adjustment tank. A filtrate water storage tank for filtering and storing raw water discharged when lowering the water level of the filter basin to be cleaned; a storage tank outflow pump that supplies the filtrate in the filtrate storage tank to a surface washing device that washes the surface of the filter layer and also supplies the filtrate to a raw water conduit; A self-cleaning filtration equipment comprising:

2. A method for cleaning a self-cleaning filtration system, comprising a filtering step in which raw water is supplied from a raw water conduit to a plurality of filtration basins, and the filtered water filtered through the filtration layers of each filtration basin is collected in a filtration adjustment tank and supplied to a next step, and a backwashing step in which the water level of the filtration basin to be cleaned is lowered below the water level of the filtration adjustment tank, and the filter layer of the filtration basin to be cleaned is backwashed with the filtrate from the filtration adjustment tank, A water level lowering process for filtering raw water discharged when lowering the water level of the filter basin to be cleaned and storing the filtered water in a filtrate storage tank; a surface washing step of supplying the filtrate water from the filtrate water storage tank to a surface washing device that washes the surface of the filter layer; A return step of supplying the filtrate water in the filtrate water storage tank to the raw water conduit; having A method for cleaning a self-cleaning filtration equipment, characterized in that during the surface washing step, the filter layer is backwashed with filtrate water from the filtration adjustment tank.

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