JP2016187784A - Filter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter device capable of adjusting efficiently a flowing amount of back wash water.SOLUTION: An adjustment plate 36 corresponding to a required flowing amount of back wash water is fixed to a movable valve element 31, and a flow passage of a swing check valve during close of a valve is narrowed, to thereby adjust the flowing amount of back wash water at the back wash time. Since fixation of the adjustment plate 36 can be executed without dismantling the movable valve element 31 from a body of the swing check valve, the flowing amount of back wash water can be adjusted efficiently.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a filtering device having a backwashing function of a filter medium using backwashing water.

Conventionally, as a filtration device that purifies raw water such as pond water, pool water, bath water, general household wastewater, industrial wastewater, or food industry wastewater, a space layer and a filter material layer are formed vertically and rotated or shaken. 2. Description of the Related Art Filtration devices are known that include a movably supported horizontal drum. In general, such a filtering device has a so-called backwashing function that removes contaminants adhering to the filter medium by pumping backwash water and air from the bottom of the floor material where the filter medium stays and stirring the filter medium. There is something to prepare. In such a filtration device, in general, a suitable flow rate of backwash water used during backwashing (for example, 150 L / min per 1 m ^{2 of} flow path area) is a flow rate of raw water treated during filtration (for example, 660 L / min) per channel area of 1 m ² . In order to cope with this, when a pump for pumping raw water at the time of filtration and a pump for pumping backwash water at the time of backwashing are separately provided, the apparatus becomes larger and the manufacturing cost increases. Further, it complicates peripheral devices including a control (electrical) system.

  Therefore, in the filtration device described in Patent Document 1, a swing check valve in which an opening having a certain opening area is formed in the movable valve body is provided in the first water pipe, and the movable valve body is opened during filtration. Thus, the flow path is fully opened and the flow path is narrowed by closing the movable valve element during backwashing. Thereby, the flow amount of the backwash water at the time of backwashing can be adjusted (reduced) with respect to the flow amount of the raw water at the time of filtration without adding a pump. Here, the suitable flowing amount of the backwash water at the time of backwashing differs for every use condition of a filtration apparatus. Therefore, the movable valve body of the swing check valve in the filtering device at the time of shipment from the factory is formed with an opening having a minimum required opening area, and the movable valve body is in accordance with the required amount of backwash water flowing. The opening area of the opening to be formed was adjusted.

  In other words, the adjustment of the amount of backwash water flow during backwashing, and consequently the adjustment of the opening area of the opening of the movable valve body, remove the movable valve body from the body by removing the hinge pin of the swing check valve. The opening area of the removed movable valve body is adjusted by machining or the like, and the movable valve body whose opening area is adjusted is assembled to the body. Since a series of operations are performed at the time of installation of the filtration device, that is, in the field, it takes a lot of time and labor to adjust the amount of backwash water.

JP-A-10-272493

  Then, this invention was made | formed in view of the said situation, and it was made as a subject to provide the filtration apparatus which can implement the adjustment of the flow amount of backwash water efficiently.

  In order to solve the above problems, a filtration device according to the present invention includes a horizontal drum in which a space layer and a filter medium layer are formed vertically and supported so as to be able to rotate or swing, and a shaft center portion of the drum. A first water pipe having a raw water inflow portion / drainage outflow portion located in the space layer, and a backwash water inflow portion / filtrate outflow portion penetrating into the axial center portion of the drum and located in the filter medium layer. A second water pipe, a five-way valve that controls the flow of flowing water through the drum, and a flow path that is provided in the flowing water path and opened during filtration to fully open the flow path and closed during backwashing And a swing check valve that restricts a flow path by being valved, wherein the swing check valve adjusts an opening formed in a movable valve body and an opening area of the opening. And an opening area adjusting means.

  ADVANTAGE OF THE INVENTION According to this invention, adjustment of the amount of flowing backwash water can be implemented efficiently.

It is explanatory drawing of the filtration apparatus which concerns on this embodiment, Comprising: It is a figure which especially shows a drum by the cross section by a uniaxial plane. It is explanatory drawing of the filtration apparatus which concerns on this embodiment, Comprising: It is especially a figure which shows the swing check valve single-piece | unit by the cross section by a uniaxial plane. It is explanatory drawing of the filtration apparatus which concerns on this embodiment, Comprising: It is a top view of the movable valve body single-piece | unit of a swing check valve especially. It is explanatory drawing of the filtration apparatus which concerns on this embodiment, Comprising: It is a top view of each of 3 types of adjustment plates of (A), (B), (C) which has an opening part from which an opening area differs especially. It is explanatory drawing of the filtration apparatus which concerns on this embodiment, Comprising: It is a figure which shows the state by which the adjustment plate of (A) of FIG. 4 was especially fixed to the movable valve body of FIG. It is explanatory drawing of other embodiment. It is explanatory drawing of other embodiment.

An embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, for convenience, the “vertical direction” and “left / right direction” in FIG. 1 are referred to as “vertical direction” and “left / right direction” as they are.
The filtration device 1 according to the present embodiment pumps backwash water into a space 13 formed between the filtration net 11 inside the drum 2 and the lid body 12 and simultaneously rotates the drum 2 at a low speed to remove the filter medium. It has a so-called back-washing function that moves and thereby removes contaminants adhering to the filter medium.

  As shown in FIG. 1, the filtration device 1 includes a horizontal drum 2 that is supported by a pair of left and right bearings 14 and 20 so as to be rotatable about an axis. Inside the drum 2, a space layer 3 and a filter medium layer 4 composed of granular filter medium are formed vertically. The filtration device 1 includes a flowing water path that passes through the drum 2. The flowing water path includes a first flowing water pipe 7 penetrating into the center (axial center portion) of the left side wall 5 of the drum 2 and a second flowing water pipe 8 penetrating into the center (axial center portion) of the right side wall 6 of the drum 2. And including. A dust seal 15 and a gland packing 16 are provided on the inner peripheral surface of the bearing portion 14. The bearing portion 14 is supported by a column 18 erected on the base 17. The support column 18 is provided with three cam followers 19 (only one cam follower 19 is shown in FIG. 1) that are equally distributed around the shaft center and are in contact with the outer peripheral surface of the bearing portion 14.

  On the other hand, on the inner peripheral surface of the left end portion of the bearing portion 20, one end portion of the second flowing water pipe 8, in other words, the end portion of the portion extending horizontally along the axis of the drum 2 is slidably fitted. The Further, the water pipe 24 whose right end is connected to the five-way valve 25 is fitted to the inner peripheral surface of the bearing portion 20. The bearing portion 20 is supported by a support column 22 erected on the base 17. The support column 22 is provided with three cam followers 23 (only one cam follower 23 is shown in FIG. 1) that are equally distributed around the shaft center and are in contact with the outer peripheral surface of the bearing portion 20. A gland packing 21 is provided on the inner peripheral surface of the bearing portion 20. Further, a dust seal (15) can be provided on the inner peripheral surface of the bearing portion 20. And the 2nd flowing water pipe 8 is fixed to the attachment frame of the filtration net | network 11 in which the edge by the side of the 2nd flowing water part 10 mentioned later rotates integrally with the drum 2. Further, the second water pipe 8 and the water pipe 24 are disposed on the axis of the drum 2 and are relatively rotatable around the axis of the drum 2. Thereby, at the time of backwashing, the drum 2 rotates around the shaft center, whereby the second flowing water pipe 8 rotates around the shaft center integrally with the drum 2.

  As shown in FIG. 1, the first flowing water pipe 7 has a first flowing water portion 9 (raw water inflow portion / drainage outflow portion) located in the space layer 3. On the other hand, the second flowing water pipe 8 has the above-described second flowing water portion 10 (backwash water inflow portion / filtered water outflow portion) located in the filter medium layer 4. At the time of filtration, the raw water pumped by a pump (not shown) passes through the water pipe 26, the five-way valve 25, the water pipe 27, the first water pipe 7, and the first water flow section 9 to the inside of the drum 2. While flowing into (space layer 3), filtrate flows out of the drum 2 via the second flowing water section 10, the second flowing water pipe 8, the flowing water pipe 24, the five-way valve 25, and the flowing water pipe 28. . On the other hand, at the time of backwashing, the backwashing water pumped by the same pump as used at the time of filtration described above is the flowing water pipe 26, the five-way valve 25, the flowing water pipe 24, the second flowing water pipe 8, and the second flowing water. While flowing into the interior (space 13) of the drum 2 via the section 10, the waste water containing the pollutant is discharged into the first flowing water section 9, the first flowing water pipe 7, the flowing water pipe 27, the five-way valve 25, and the flowing water pipe. It flows out of the drum 2 via 29. The flowing water path includes the flowing water pipes 24 and 26 to 29.

  A swing check valve 30 is provided in the above-described water flow pipe 27, that is, the water flow pipe 27 through which the raw water pumped by the pump flows during filtration and through which the waste water flowing out from the drum 2 flows during back washing. As shown in FIG. 2, the swing check valve 30 is obtained by forming an opening 32 in the movable valve body 31 of a ready-made swing check valve. The swing check valve 30 opens when the movable valve element 31 rotates around the hinge pin 33 by the flow of raw water during filtration, and as a result, the flow path is fully opened. On the other hand, at the time of backwashing, the movable valve body 31 is seated on the seat portion 34 by the flow of drainage, and as a result, the flow path is narrowed to a predetermined opening degree.

  The swing check valve 30 adjusts the amount of drainage flowing through the water flow pipe 26 by adjusting the opening area of the opening 32 formed in the movable valve body 31. Opening area adjusting means for adjusting the amount of backwash water used is provided. The opening area adjusting means includes a plurality of (three in this embodiment) that are selectively fixed to one side 35 of the movable valve body 31, that is, the surface 35 opposite to the surface seated on the seat portion 34. Includes adjustment plates 36-38 (see FIG. 4). As shown in FIG. 3, the opening 32 formed in the movable valve body 31 is a circular hole having an opening area (channel area) smaller than the opening 39 (channel) formed in the seat portion 34. In a state in which the movable valve body 31 is closed, the movable valve body 31 is located concentrically with the opening 39. Moreover, the opening part 32 has an opening area corresponding to the maximum flow amount of backwash water assumed.

  As shown in FIG. 4A, the adjustment plate 36 is generally formed in an annular shape having an outer diameter larger than the opening 32 of the movable valve body 31. The adjustment plate 36 has a pair of upper and lower attachment pieces 40 and 41. Each attachment piece 40, 41 is provided with attachment holes 44, 45 facing each screw hole 42, 43 provided in the movable valve body 30. The adjustment plate 36 is fixed to one side surface 35 of the movable valve body 30 by fastening the bolts 46 and 47 (see FIG. 5) inserted through the attachment holes 44 and 45 to the screw holes 42 and 43. .

  Here, FIG. 5 shows the movable valve body 31 to which the adjustment plate 36 is fixed. In this state, the opening 48 </ b> A formed in the adjustment plate 36 is located concentrically with the opening 32 formed in the movable valve body 31. The opening 48 </ b> A has an opening area (flow path area) that is slightly smaller than the opening 32. By fixing the adjustment plate 36 having such an opening 48A to the movable valve body 31, the flow path of the swing check valve 30 when the valve is closed is narrowed, that is, the amount of backwash water flowing during the backwash. Can be adjusted.

  In the present embodiment, adjustment plates 36, 37, and 38 each having openings 48A, 48B, and 48C (see FIG. 4) having different opening areas (channel areas) are prepared. Then, an adjustment plate (36, 37, 38) corresponding to the required amount of backwash water is fixed to one side surface 35 of the movable valve body 31, and the flow path when the swing check valve 30 is closed is narrowed. Thus, the flow amount of backwash water during backwashing is adjusted. 4B has an opening 48B having an opening area (flow channel area) that is slightly smaller than the opening 48A formed in the adjustment plate 36. The adjustment plate 37 shown in FIG. Further, the adjustment plate 38 of FIG. 4C has an opening 48C having an opening area (flow channel area) that is slightly smaller than the opening 48B formed in the adjustment plate 37.

Next, the operation of the filtration device 1 described above will be described. An adjustment plate 36 (opening area adjusting means) is fixed to the movable valve body 31 of the swing check valve 30.
(When filtering)
As shown in FIG. 1, raw water pumped by a single pump (not shown) passes through a water flow pipe 26, a five-way valve 25, a water flow pipe 27, a first water flow pipe 7, and a first water flow section 9. Then, it flows into the drum 2 (space layer 3). At this time, the raw water flowing through the flowing water pipe 27 rotates the movable valve body 31 of the swing check valve 30 in the valve opening direction (clockwise direction in FIG. 2). As a result, the flow path of the swing check valve 30 is fully opened, and raw water of a constant flow rate (for example, 660 L / min per 1 m ^{2 of} flow path area) flows through the swing check valve 30. Then, the raw water purified by the filter medium layer 4, that is, the filtered water passes through the second flowing water section 10, the second flowing water pipe 8, the flowing water pipe 24, the five-way valve 25, and the flowing water pipe 28 to the outside of the drum 2. Spill to

(When backwashing)
On the other hand, at the time of backwashing, the drum 2 is rotationally driven at a constant rotational speed by a driving means (not shown). As a result, the drum 2 rotates about the shaft center, and the filtration net 11 and the second flowing water pipe 8 rotate together with the drum 2 to form a filter medium layer 4 formed inside the drum 2. Are rubbed together, and the contaminants adhering to the filter medium are peeled off. Further, the particulate filter medium is also rubbed with the filter net 11 (for example, a wedge wire), and the contaminants attached to the filter medium are more efficiently removed. And the backwash water pumped by the same pump used at the time of filtration passes through the flowing water pipe 26, the five-way valve 25, the flowing water pipe 24, the second flowing water pipe 8, and the second flowing water part 10. It flows into the interior (space 13) of the drum 2.

Then, the wastewater containing the pollutant removed from the filter medium flows out of the drum 2 via the first flowing water section 9, the first flowing water pipe 7, the flowing water pipe 27, the five-way valve 25, and the flowing water pipe 29. . At this time, the drainage flowing through the flowing water pipe 27 urges the movable valve body 31 in the valve closing direction (counterclockwise direction in FIG. 2). Thereby, the movable valve body 31 is seated on the seat portion 34, and the flow path of the swing check valve 30 is restricted to the opening area of the opening 48 </ b> A formed in the adjustment plate 36. As a result, a predetermined amount of flowing water (for example, 150 L / min per 1 m ^{2 of} the channel area) flows through the swing check valve 30.

This embodiment has the following effects.
According to the present embodiment, the adjusting plates 36, 37, 38 (opening area adjusting means) in which the openings 48A, 48B, 48C having different opening areas are formed are provided, and the required amount of backwash water is supplied. Corresponding adjustment plates (36, 37, 38) are fixed to the movable valve body 31, and the flow amount of the backwash water at the time of backwashing is adjusted by narrowing the flow path of the swing check valve 30 when the valve is closed. be able to.
Here, the operation of fixing the adjustment plate (36, 37, 38) to the movable valve body 31 can be performed without removing the movable valve body 31 from the body 49 of the swing check valve 30, and machining is also possible. Since it is not necessary, the operation of adjusting the amount of backwash water flowing at the time of backwashing can be greatly rationalized as compared with the prior art.
Moreover, since the change with respect to the existing equipment only needs to add the opening part 32 and the screw holes 42 and 43 to the movable valve body 31 of the swing check valve 30, it can be implemented easily and at low cost.

In addition, this invention is not limited to embodiment mentioned above, For example, it can comprise as follows.
In the above-described embodiment, the flow amount of the flowing water flow path through which the waste water flowing out from the drum 2 is squeezed by the swing check valve 30 to adjust the flow amount of the backwash water during backwashing. The flow amount of the backwash water at the time of backwashing can also be adjusted by restricting the flow path of the waterflow path through which the backwash water flowing into the drum 2 flows by the swing check valve 30.

In the above-described embodiment, the adjustment plates 36, 37, and 38 (opening area adjusting means) having the openings 48, 48B, and 48C having different opening areas are prepared, and the adjustment corresponding to the required amount of backwash water flowing is prepared. The plate (36, 37, 38) is fixed to the movable valve body 31, and the flow amount of the backwash water at the time of backwashing is adjusted by restricting the flow path of the swing check valve 30 when the valve is closed. However, as shown in FIG. 6, the opening area adjusting means can be constituted by a circular adjusting plate 51 having no opening.
In this case, the adjustment plate 51 has an attachment piece 52 in which an attachment hole 55 is formed, and a bolt 53 inserted through the attachment hole 55 is fastened to a screw hole 54 provided in one side surface 35 of the movable valve body 30. As a result, the movable valve body 30 is fixed to one side surface 35. At this time, by adjusting the mounting angle of the adjustment plate 51, that is, the mounting angle with the bolt 53 (shaft) as the swing center, the adjustment plate 51 is swung around the bolt 53 (shaft). The opening area of the opening 32 formed in the movable valve body 31 is adjusted. In this manner, the flow amount of the backwash water at the time of backwashing can be adjusted by restricting the flow path of the swing check valve 30 at the time of valve closing.
Further, a plurality of concave portions (not shown) arranged at regular intervals on a predetermined arc centered on the screw hole 54 are provided on one side surface 35 of the movable valve body 31, and the adjustment plate 51 is attached. Protrusions that can be engaged with the respective recesses are provided at positions opposite to the pieces 52, and the flow path of the swing check valve 30 when the valve is closed is selected by selecting the recesses with which the protrusions are engaged. The opening area adjusting means can be configured to adjust the area, that is, the flow amount of the backwash water during backwashing in a plurality of stages.

The opening 32 is not only arranged at the center (center) of the movable valve body 31, but can be biased to the left with respect to the center of the movable valve body 31, for example, as shown in FIG.
In addition to the means for fixing the adjustment plates 36, 37, 38, 51 to the one side surface 35 of the movable valve body 31 with the bolts 46, 46, 53, for example, openings (flow paths) are formed as the opening area adjusting means. By fitting a circular adjustment plate (not shown) into the opening 32 formed in the movable valve body 31, the flow area of the swing check valve 30 when the valve is closed, that is, the reverse when backwashing is performed. It can be configured to adjust the amount of flush water.

DESCRIPTION OF SYMBOLS 1 Filtration apparatus, 2 drums, 3 Space layer, 4 Filter material layer, 7 1st flow pipe, 8 2nd flow pipe, 9 1st flow part (raw water inflow part / drainage outflow part), 10 2nd flow part (backwash) (Water inflow part / drainage part), 25 5-way valve, 30 swing check valve, 31 movable valve body, 32 opening, 36-38 adjustment plate (opening area adjusting means)

In order to solve the above problems, a filtration device according to the present invention includes a horizontal drum in which a space layer and a filter medium layer are formed vertically and supported so as to be able to rotate or swing, and a shaft center portion of the drum. A first water pipe having a raw water inflow portion / drainage outflow portion located in the space layer, and a backwash water inflow portion / filtrate outflow portion penetrating into the axial center portion of the drum and located in the filter medium layer. A second water pipe, a five-way valve that controls the flow of flowing water through the drum, and a flow path that is provided in the flowing water path and opened during filtration to fully open the flow path and closed during backwashing And a swing check valve that restricts a flow path by being valved, wherein the swing check valve adjusts an opening formed in a movable valve body and an opening area of the opening. possess the opening area adjusting means, for the opening area adjusting means, the opening area Among the plurality of adjustment plates in which different openings are formed, the adjustment plate in which an opening having an opening area corresponding to the amount of backwash water flowing through the water flow path during backwashing is formed. It is fixed to the body .
Further, the filtration device of the present invention includes a horizontal drum in which a space layer and a filter medium layer are formed vertically and supported so as to be rotatable or swingable, and penetrated into an axial center portion of the drum, and is positioned in the space layer. A first water pipe having a raw water inflow part / drainage outflow part, a second water pipe having a backwash water inflow part / filtrate outflow part penetrating into the axial center of the drum and located in the filter medium layer; A five-way valve that controls the flow of flowing water through the drum and a flow path that is provided in the flowing water path and is opened during filtration to fully open the flow path and closed during backwashing. A swing check valve for restricting a path, wherein the swing check valve includes an opening formed in a movable valve body, and an opening area adjusting means for adjusting an opening area of the opening. And the opening area adjusting means is provided on one side of the movable valve body. An adjustment plate that can swing about an axis, and the opening angle of the opening is adjusted by adjusting an attachment angle of the adjustment plate with respect to the movable valve body about the axis. It is characterized by.

In order to solve the above problems, a filtration device according to the present invention includes a horizontal drum in which a space layer and a filter medium layer are formed vertically and supported so as to be able to rotate or swing, and a shaft center portion of the drum. A first water pipe having a raw water inflow portion / drainage outflow portion located in the space layer, and a backwash water inflow portion / filtrate outflow portion penetrating into the axial center portion of the drum and located in the filter medium layer. A second water pipe, a five-way valve that controls the flow of flowing water through the drum, and a flow path that is provided in the flowing water path and opened during filtration to fully open the flow path and closed during backwashing And a swing check valve that restricts a flow path by being valved, wherein the swing check valve adjusts an opening formed in a movable valve body and an opening area of the opening. Opening area adjusting means, and the opening area adjusting means has an opening area. Among the plurality of adjustment plates in which different openings are formed, the adjustment plate in which an opening having an opening area corresponding to the amount of backwash water flowing through the water flow path during backwashing is formed. It is fixed to the body .

It is explanatory drawing of the filtration apparatus which concerns on this embodiment, Comprising: It is a figure which especially shows a drum by the cross section by a uniaxial plane. It is explanatory drawing of the filtration apparatus which concerns on this embodiment, Comprising: It is especially a figure which shows the swing check valve single-piece | unit by the cross section by a uniaxial plane. It is explanatory drawing of the filtration apparatus which concerns on this embodiment, Comprising: It is a top view of the movable valve body single-piece | unit of a swing check valve especially. It is explanatory drawing of the filtration apparatus which concerns on this embodiment, Comprising: It is a top view of each of 3 types of adjustment plates of (A), (B), (C) which has an opening part from which an opening area differs especially. It is explanatory drawing of the filtration apparatus which concerns on this embodiment, Comprising: It is a figure which shows the state by which the adjustment plate of (A) of FIG. 4 was especially fixed to the movable valve body of FIG. It is explanatory drawing of a reference example . It is explanatory drawing of a reference example .

In the above-described embodiment, the adjustment plates 36, 37, and 38 (opening area adjusting means) having the openings 48, 48B, and 48C having different opening areas are prepared, and the adjustment corresponding to the required amount of backwash water flowing is prepared. The plate (36, 37, 38) is fixed to the movable valve body 31, and the flow amount of the backwash water at the time of backwashing is adjusted by restricting the flow path of the swing check valve 30 when the valve is closed. I did . On the other hand, in the reference example shown in FIG. 6, the opening area adjusting means is configured by the circular adjusting plate 51 having no opening .
In this case, the adjustment plate 51 has an attachment piece 52 in which an attachment hole 55 is formed, and a bolt 53 inserted through the attachment hole 55 is fastened to a screw hole 54 provided in one side surface 35 of the movable valve body 30. As a result, the movable valve body 30 is fixed to one side surface 35. At this time, by adjusting the mounting angle of the adjustment plate 51, that is, the mounting angle with the bolt 53 (shaft) as the swing center, the adjustment plate 51 is swung around the bolt 53 (shaft). The opening area of the opening 32 formed in the movable valve body 31 is adjusted. In this manner, the flow amount of the backwash water at the time of backwashing can be adjusted by restricting the flow path of the swing check valve 30 at the time of valve closing.
Further, a plurality of concave portions (not shown) arranged at regular intervals on a predetermined arc centered on the screw hole 54 are provided on one side surface 35 of the movable valve body 31, and the adjustment plate 51 is attached. Protrusions that can be engaged with the respective recesses are provided at positions opposite to the pieces 52, and the flow path of the swing check valve 30 when the valve is closed is selected by selecting the recesses with which the protrusions are engaged. The opening area adjusting means can be configured to adjust the area, that is, the flow amount of the backwash water during backwashing in a plurality of stages.

Claims (3)

A horizontal drum in which a space layer and a filter medium layer are formed vertically and supported so as to be rotatable or swingable, and a raw water inflow portion / drainage outflow portion that is inserted into an axial center portion of the drum and located in the space layer. A first flowing water pipe having a second flowing water pipe penetrating into an axial center portion of the drum and having a backwash water inflow portion / filtered water outflow portion located in the filter medium layer; A five-way valve that controls the flow of water, and a swing check valve that is provided in the flowing water path and is opened during filtration to fully open the flow path, and closed during backwash to narrow the flow path. A filtration device comprising:
The swing check valve has an opening formed in a movable valve body and an opening area adjusting means for adjusting an opening area of the opening. The opening area adjusting means includes a plurality of adjusting plates in which openings having different opening areas are formed, and an opening having an opening area corresponding to the amount of backwash water flowing through the flowing water path during backwashing. The filtration device according to claim 1, wherein the formed adjustment plate is fixed to the movable valve body. The opening area adjusting means includes an adjustment plate that can swing around an axis provided on one side of the movable valve body, and an attachment angle of the adjustment plate with respect to the movable valve body about the axis is set. The filtration device according to claim 1, wherein the opening area of the opening is adjusted by the adjustment.

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