Filter membrane unit, holder for holding the filter membrane unit, filtration system including the filter membrane unit and the holder, and filtration processing device including a plurality of filtration systems

Abstract

The filtration membrane unit (21) includes a filtration membrane (22) and a suction-side socket (23) that is fixed to an end portion on one side in the long-side direction of the filtration membrane (22) in order to hold the filtration membrane (22) on one side in the long-side direction. The suction-side socket (23) extends along the short-side direction of the filtration membrane (22) in a state of being fixed to the above-mentioned end portion. Moreover, the suction-side socket (23) includes: a recess into which the above-mentioned end portion is inserted; a flow path that communicates with the recess and extends along the extending direction of the suction-side socket (23); and a discharge port for discharging the filtrate in the flow path. Among them, the suction-side socket (23) includes a first outlet (provided on the first protrusion 23b) and a second outlet (provided on the second protrusion 23c) as the above-mentioned discharge port. The first outlet is arranged at a position on one side in the extending direction with respect to the center in the extending direction of the suction-side socket, and the second outlet is arranged at a position on the other side in the extending direction with respect to the center in the extending direction of the suction-side socket (23).

Description

Technical Field

[0001] The present invention relates to a filter membrane unit, a holder for holding the filter membrane unit, a filtration system including the filter membrane unit and the holder, and a filtration processing apparatus including a plurality of filtration systems. Background Art

[0002] Conventionally, there has been known a filter membrane unit including a filter membrane and a socket fixed to an end portion on one side in the long side direction of the filter membrane in order to hold the filter membrane on one side in the long side direction.

[0003] For example, a filter unit described in Patent Document 1 as a filter membrane unit includes a ceramic filter as a filter membrane and a bracket as a socket. The ceramic filter has a flat plate shape. The bracket extends along the short side direction of the ceramic filter in a state of being fixed to an end portion on one side in the long side direction of the flat plate-shaped ceramic filter. Further, the bracket includes a recess into which the above-described end portion of the ceramic filter is inserted, a flow path that communicates with the recess and extends in the extending direction of the bracket, and a filtrate outlet as a discharge port for discharging the filtrate in the flow path. If a negative pressure is generated at the filtration outlet by the suction of a pump or the like, the water to be treated existing around the ceramic filter is attracted into the fine pores of the ceramic filter and filtered. The filtrate is discharged from the filtration outlet through the flow path of the bracket from inside the ceramic filter.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: WO2007 / 128565 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In the filter unit described in Patent Document 1, the filtrate outlet is disposed at one end in the extending direction of the bracket. In this structure, a deviation in negative pressure occurs in the filter in the short side direction of the ceramic filter. Specifically, in the entire region in the short side direction of the ceramic filter, the negative pressure in the region closer to the filtrate outlet is greater than the negative pressure in the region farther from the filtrate outlet. As a result, the amount of filtered water per unit time in the former region is larger than the amount of filtered water per unit time in the latter region, and the clogging in the former region occurs earlier than in the latter region. As a result, compared with a filter unit in which the deviation in the amount of filtered water in each region is small, the time interval between filter cleaning operations for removing clogging becomes shorter, and the maintainability deteriorates.

[0009] The present invention has been completed in view of the above background, and an object thereof is to provide a filter membrane unit capable of improving the maintainability of a filter membrane, a holder for holding the filter membrane unit, a filtration system including the filter membrane unit and the holder, and a filtration processing apparatus including a plurality of filtration systems.

[0010] Means for Solving the Problem

[0011] To achieve the above object, a filter membrane unit according to one aspect of the present invention includes a filter membrane and a socket. The socket is fixed to an end portion on one side in the long side direction of the filter membrane so as to hold the filter membrane on one side in the long side direction, and the socket extends in the short side direction of the filter membrane in a state of being fixed to the end portion. The socket includes a recess into which the end portion is inserted, a flow path that communicates with the recess and extends in the extending direction of the socket, and a discharge port for discharging the filtrate in the flow path. The filter membrane unit is characterized in that the socket has a first outlet and a second outlet as the discharge ports, the first outlet is disposed at a position closer to one side in the extending direction than the center in the extending direction of the socket, and the second outlet is disposed at a position closer to the other side in the extending direction than the center in the extending direction of the socket.

[0012] Effects of the Invention

[0013] According to the present invention, there is an excellent effect of being able to improve the maintainability of the filter membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 FIG. is a schematic configuration diagram of a water treatment facility including a filtration system according to an embodiment.

[0015] Figure 2 FIG. is a perspective view of a filter membrane unit according to an embodiment.

[0016] Figure 3 FIG. is a cross-sectional view of a suction side socket of the filter membrane unit taken along the longitudinal section.

[0017] Figure 4 FIG. is a side view of the filter membrane unit as viewed from the side.

[0018] Figure 5 FIG. is a perspective view of a filtration system according to an embodiment.

[0019] Figure 6 FIG. is an exploded perspective view of the filtration system.

[0020] Figure 7 FIG. is a perspective view of a water collection box of a holder according to an embodiment.

[0021] Figure 8 FIG. is a perspective view of a filtration processing apparatus according to an embodiment.

[0022] Figure 9 This is a perspective view showing the upper water collection box and the lower water collection box configured in multiple layers in the filtration processing device, as well as the connecting pipes connecting these boxes.

[0023] Figure 10 This is a cross-sectional view showing the longitudinal section of two water collection boxes stacked one above the other in the filtration processing device of the embodiment together with the cross-section of the connecting pipe.

[0024] Figure 11 This is the cross-sectional ratio of the connecting pipe Figure 10 A cross-sectional view shown enlarged.

[0025] Figure 12 This is a side view of the filter membrane unit of the first comparative example in which only one discharge port is arranged at the suction side socket in the same manner as the filter unit described in Patent Document 1. Detailed implementation mode

[0026] Hereinafter, an embodiment of the filtration processing device to which the present invention is applied will be described with reference to the respective drawings. In the embodiment, for easy understanding of the description, the structures and elements other than the main part of the present invention are simplified or omitted from the description. In addition, in each drawing, the same reference numerals are assigned to the same elements. It should be noted that the shapes, dimensions, etc. of the respective elements shown in each drawing are schematically represented and do not represent the actual shapes, dimensions, etc.

[0027] Figure 1 This is a diagram showing the schematic structure of a water treatment facility equipped with the filtration processing device of the embodiment. This water treatment facility includes a raw water tank 1, a filtration processing tank 2, a treated water tank 3, a control device 4, a raw water pump 5, a first water level sensor 6, a raw water transfer pipe 7, a treated water transfer pipe 8, a suction pump 9, a second water level sensor 11, a third water level sensor 12, etc. In addition, the water treatment facility includes a blower 13, an air supply pipe 14, a pedestal 15, a filtration processing device 20, a bubble generating device 90, etc.

[0028] Raw water (water before treatment) W as a liquid is stored in the raw water tank 1 1 . The first water level sensor composed of an ultrasonic sensor or the like provided in the raw water tank 1 detects the water level (height of the water surface) of the raw water W in the raw water tank 1 and sends the detection result to the control device 4 as a water level signal. The raw water pump 5 provided in the raw water tank 1 sucks and discharges the raw water W in the raw water tank 1 1 and sends it to the filtration processing tank 2 through the raw water transfer pipe 7. As the raw water pump 5, a pump composed of a submersible pump is exemplified, but a pump composed of a surface pump can also be used. 1

[0029] The filtration treatment water tank 2 is a water tank made of reinforced concrete. A filtration treatment device 20 and a bubble generating device 90 are provided in the filtration treatment water tank 2. The filtration treatment device 20 and the bubble generating device 90 are supported by a pedestal 15. The pedestal 15 supports the bubble generating device 90 so as to be directly below the filtration treatment device 20. The filtration treatment device 20 and the bubble generating device 90 are respectively immersed in the raw water W in the filtration treatment water tank 2 1 inside.

[0030] The blower 13 discharges the air as a gas sucked from the suction port to the air supply pipe 14 through the discharge port. The air discharged to the air supply pipe 14 is supplied to the bubble generating device 90. The bubble generating device 90 discharges the air supplied from the air supply pipe 14 as bubbles upward. The discharged bubbles rise in the raw water W while contacting a plurality of filter membranes mounted on the filtration treatment device 20 1 inside. At this time, the bubbles separate the solids attached to the surface of the filter membrane from the surface of the filter membrane. By this separation, clogging of the filter membrane can be suppressed.

[0031] The third water level sensor 12 provided in the filtration treatment water tank 2 detects the water level of the raw water W in the filtration treatment water tank 2 1 and sends the detection result to the control device 4 as a water level signal.

[0032] The suction pump 9 sucks the raw water W in the filtration treatment water tank 2 via the treated water transfer pipe 8 and a plurality of filter membranes (to be described later) mounted in the filtration treatment device 20 1 . The sucked raw water W 1 is filtered by the filter membrane to become treated water W 2 and then is sent to the treatment water tank 3 through the treated water transfer pipe 8. The second water level sensor 11 set in the treatment water tank 3 detects the water level of the treated water W 2 in the treatment water tank 3 and sends the detection result to the control device 4 as a water level signal.

[0033] It should be noted that a pump that generates suction force using the head pressure can also be used instead of the suction pump 9. The suction means is not particularly limited.

[0034] When the water level in the treatment water tank 3 does not reach the upper limit and the specified operation execution conditions are satisfied, the control device 4 operates the suction pump 9 and the blower 13 to perform the filtration treatment of the raw water W 1 . However, even if the operation execution conditions are satisfied, when the water level of the raw water W in the raw water tank 1 is below the lower limit and when the water level of the raw water W in the filtration treatment water tank 2 1 is below the lower limit, the control device 4 also aborts the execution of the filtration treatment. 1

[0035] ​The filtration processing device 20 includes filtration systems in multiple embodiments (detailed later). Each filtration system includes filtration membrane units in multiple embodiments (detailed later).

[0036] Figure 2 FIG. is a perspective view showing the filtration membrane unit 21 of the embodiment. The filtration membrane unit 21 includes a flat filtration membrane 22. Examples of the material of the filtration membrane 22 include organic materials such as PVDF (polyvinylidene fluoride) and PVC (polyvinyl chloride). In addition, as the material of the filtration membrane 22, ceramics mainly composed of alumina, silicon carbide, etc. can also be used. The filtration membrane 22 of the filtration membrane unit 21 in the embodiment is composed of a ceramic membrane.

[0037] When the above suction pump ( Figure 1 No. 9) operates, an attraction force along the long side direction of the filtration membrane 22 is applied to the filtration membrane 22. In the filtration system of the embodiment, an attraction force is applied to the filtration membrane 22 from one side in the long side direction of the filtration membrane 22 (the right side in the left-right direction described later in Figure 4 ). That is, one side in the long side direction of the filtration membrane 22 is the attraction side to which the attraction force is applied. The other side in the long side direction of the filtration membrane 22 (the left side in the left-right direction described later in Figure 4 ) is the shielding side that shields the attraction force applied to the filtration membrane 22.

[0038] In addition to the above filtration membrane 22, the filtration membrane unit 21 further includes an attraction side socket 23 and a shielding side socket 24. The attraction side socket 23 of the socket in the present invention is fixed to the end of one side in the long side direction (attraction side) of the filtration membrane 22 in order to hold the filtration membrane 22. The shielding side socket 24 is fixed to the end of the other side in the long side direction (shielding side) of the filtration membrane 22 in order to hold the filtration membrane 22. The attraction side socket 23 and the shielding side socket 24 respectively extend along the short side direction of the filtration membrane 22 (the up-down direction along the gravity direction in the embodiment) in a state of being fixed to the filtration membrane 22.

[0039] Figure 3 FIG. is a cross-sectional view showing the longitudinal section of the attraction side socket 23. The attraction side socket 23 includes a socket main body 23a. The socket main body 23a includes a recess 23d into which the end of one side in the long side direction of the filtration membrane ( Figure 2 No. 22) is inserted, and a flow path 23e that communicates with the recess 23d and extends along the extending direction of the socket main body 23a.

[0040] In addition to the above socket main body 23a, the attraction side socket 23 further includes a first protrusion 23b and a second protrusion 23c. The first protrusion 23b and the second protrusion 23c are respectively in the long side direction of the filtration membrane ( Figure 2 No. 22) ( Figure 3in the left - right direction) is located outside the socket body 23a ( Figure 3 on the right side in), and is arranged along the extending direction of the socket body 23a ( Figure 3 in the up - down direction).

[0041] The structures of the first protruding body 23b and the second protruding body 23c are both tubular structures with a hollow (23b - 1, 23c - 1). Each of the hollows (23b - 1, 23c - 1) in the first protruding body 23b and the second protruding body 23c communicates with the flow path 23e of the socket body 23a. In addition, each of the hollows (23b - 1, 23c - 1) in the first protruding body 23b and the second protruding body 23c opens at both ends in the extending direction ( Figure 3 of the left - right direction) of the protruding bodies (23b, 23c). One of the two openings of the hollow 23b - 1 of the first protruding body 23b, on the side ( Figure 3 in the left - right direction) of the extending direction of the first protruding body 23b ( Figure 3 on the right side in) is the first outlet 23b - 2 which is a discharge port for discharging the treated water ( Figure 1 the W 2 ) in the flow path 23e. In addition, one of the two openings of the hollow 23c - 1 of the second protruding body 23c, on the side ( Figure 3 in the left - right direction) of the extending direction of the second protruding body 23c ( Figure 3 on the right side in) is the second outlet 23c - 2 which is a discharge port for discharging the treated water in the flow path 23e.

[0042] The hollow 23b - 1 of the first protruding body 23b communicates with the flow path 23e through the opening 23b - 3 on the other side ( Figure 3 in the left - right direction) of the extending direction of the first protruding body 23b ( Figure 3 on the left side in) among its two openings. In addition, the hollow 23c - 1 of the second protruding body 23c communicates with the flow path 23e through the opening 23c - 3 on the other side ( Figure 3 in the left - right direction) of the extending direction of the second protruding body 23c ( Figure 3 on the left side in) among its two openings.

[0043] When the suction pump ( Figure 1 9) works, an attraction force generated by negative pressure is respectively generated in the hollow 23b - 1 of the first protruding body 23b and the hollow 23c - 1 of the second protruding body 23c. Through this attraction force, the treated water in the flow path 23e of the socket body 23a is attracted into the interiors of the hollow 23b - 1 of the first protruding body 23b and the hollow 23c - 1 of the second protruding body 23c.

[0044] Figure 4is a side view showing the filtration membrane unit 21 from the side. The shielding side socket 24 of the filtration membrane unit 21 includes a socket body 24a and two protrusions 24b. The socket body 24a has a recess (not shown) into which the end portion on the other side ( Figure 4 the left - right direction in Figure 4 the left side in

[0045] the long - side direction of the filtration membrane 22) is inserted. It should be noted that the socket body 24a does not have a flow path communicating with the above - mentioned recess. The suction force applied to the filtration membrane 22 is shielded on the other side in the long - side direction of the filtration membrane 22 through the shielding side socket 24. Figure 4 the left side in Figure 4 the long - side direction of the filtration membrane 22) is located outside ( Figure 4 the left side in

[0046] Figure 12 is a side view showing the filtration membrane unit 121 of the first comparative example in which, similar to the filter unit described in Patent Document 1, only one discharge port is provided in the suction side socket 123. In Figure 12 , the arrow indicated by the dashed - dotted line represents the flow direction of the treated water. The discharge port is arranged at the end portion on the other side ( Figure 12 the up - down direction in Figure 12 the lower side in

[0047] In this structure, a stronger suction force (negative pressure) is applied to the regions closer to the discharge port in each region in the short - side direction ( Figure 12 the up - down direction in

[0048] On the other hand, in the filtration membrane unit 21 of the embodiment, as Figure 4 shown, the first protrusion 23b and the second protrusion 23c having discharge ports ( Figure 3 the first outlet 23b - 2, the second outlet 23c - 2) are arranged along the extending direction ( Figure 4arranged in the vertical direction). That is, the filter membrane unit 21 has two discharge ports arranged in the extending direction of the socket body 23a.

[0049] In this structure, two discharge ports ( Figure 3 the first outlet 23b-2 and the second outlet 23c-2) that exist at different positions in the extending direction of the socket body 23a respectively generate suction forces. Thus, as Figure 4 shown by the dashed-dotted arrow in the single figure, the deviation of the amount of filtrate in the short side direction of the filter membrane 22 can be suppressed, and thus, the equalization of the amount of filtrate in the short side direction of the filter membrane 22 can be achieved. As a result, the time interval of the filter membrane cleaning operation for removing clogging becomes longer, and the maintainability is improved. Therefore, according to the filter membrane unit 21 of the embodiment, the maintainability of the filter membrane 22 can be improved.

[0050] Hereinafter, the first outlet provided in the first protrusion 23b ( Figure 3 23b-2) and the ( Figure 3 second outlet 23c-2) provided in the second protrusion 23c are collectively referred to as "the two discharge ports of the suction side socket 23". When the diameter of the discharge port is set to a specified value and the amount of filtrate per unit time of the filter membrane (22, 122) is set to a specified value, the following conditions need to be adopted as the conditions for the flow rate of the treated water passing through the discharge port per unit time. That is, the condition is that the inflow amount of the treated water into the discharge port of the filter membrane unit 121 of the first comparative example is set to about twice the inflow amount of the treated water into each of the "two discharge ports of the suction side socket 23" of the embodiment. Under this condition, since the flow path resistance of the treated water in the filter membrane unit 21 of the embodiment is smaller than that of the first comparative example, the power of the suction power machine such as the Figure 1 suction pump 9 can be further reduced, and energy saving can be achieved.

[0051] Regarding each of the first outlet ( Figure 3 23b-2) and the second outlet ( Figure 3 23c-2), different from the Figure 3 shown manner, they may also be arranged at specified positions on the circumferential surface of the protrusions (23b, 23c) (hereinafter, this arrangement is referred to as circumferential surface arrangement). However, as Figure 3As shown, it is more preferable to dispose a first outlet 23b-2 and a second outlet 23c-2 on the front end faces of the protruding bodies (23b, 23c) respectively (hereinafter, this disposition is referred to as the front end face disposition). This is for the reasons described below. That is, in the circumferential surface disposition, it is necessary to change the flow direction of the treated water in the hollows (23b-1, 23c-1) of the protruding bodies (23b-2, 23c-2) by an angle of approximately 90° just before reaching the discharge outlets (the first outlet 23b-2, the second outlet 23c-2). Thereby, the flow path resistance of the filtration membrane unit 21 is increased. In contrast, in the front end face disposition, the flow direction of the treated water in the hollows (23b-1, 23c-1) of the protruding bodies (23b-2, 23c-2) is the same as the flow direction of the treated water when passing through the discharge outlets (the first outlet 23b-2, the second outlet 23c-2). Therefore, different from the circumferential surface disposition, the flow direction of the treated water in the hollows (23b-1, 23c-1) is not greatly changed, and thus, the flow path resistance can be reduced compared with the circumferential surface disposition.

[0052] Figure 5 FIG. is a perspective view showing a filtration system 31 according to an embodiment. The filtration system 31 includes a plurality of filtration membrane units 21 and a holder 40 that holds the plurality of filtration membrane units 21. The holder 40 has a frame shape, and the holder 40 holds a plurality of filtration membrane units 21 within the frame. In addition, the holder 40 includes a water collection box 41, a blind cassette 60, a first side cover 65, and a second side cover 66.

[0053] Figure 6 FIG. is an exploded perspective view showing the filtration system 31 according to the embodiment. The holder ( Figure 5 40) is formed by combining a flat rectangular parallelepiped-shaped water collection box 41, a flat plate-shaped first side cover 65, a flat rectangular parallelepiped-shaped blind cassette 60, and a flat plate-shaped second side cover 66 into a frame shape. Different from the state shown in this figure, the water collection box 41 faces the blind cassette 60 in a state where there are no plurality of filtration membrane units 21. In addition, in the above state, the first side cover 65 and the second side cover 66 face each other in a direction orthogonal to the facing direction of the water collection box 41 and the blind cassette 60.

[0054] The water collection box 41 and the blind cassette 60 are respectively disposed such that their long side directions are along the facing direction of the first side cover 65 and the second side cover 66. On the other hand, the first side cover 65 and the second side cover 66 are respectively disposed such that their long side directions are along the facing direction of the water collection box 41 and the blind cassette 60.

[0055] Figure 7 FIG. is a view showing the holder ( Figure 5Perspective view of the water collection box 41 of (40). The water collection box 41 is formed by combining a top plate 42, a bottom plate 45, a first long side plate 43, a second long side plate 44, and a first short side plate 46 and a second short side plate 47 that are shorter than the long side plates (43, 44) into a flat rectangular parallelepiped shape. The top plate 42 and the bottom plate 45 are opposite to each other. In the water treatment facility, as shown in this figure, the water collection box 41 is arranged in such a way that the top plate 42 and the bottom plate 45 are arranged in the up and down direction along the gravity direction.

[0056] The first long side plate 43 and the second long side plate 44 are respectively arranged in such a way that their long side directions are along the short side directions of the first short side plate 46 and the second short side plate 47 respectively. On the other hand, the first short side plate 46 and the second short side plate 47 are respectively arranged in such a way that their long side directions are along the facing direction of the top plate 42 and the bottom plate 45.

[0057] On the front surface of the first short side plate 46, a first fixing portion 48 protruding from the front surface is provided. In addition, on the front surface of the second short side plate 47, a second fixing portion 49 protruding from the front surface is provided.

[0058] Hereinafter, the frame structure of the frame-shaped holding body ( Figure 5 of (40)) will be simply referred to as "frame". The first long side plate 43 is located at a position inside the "frame" closer to the second long side plate 44. The first long side plate 43 functions as a side plate for holding one end portion in the long side direction of the filter membrane unit ( Figure 6 of (21)).

[0059] The first long side plate 43 has a plurality of hole pairs, and each hole pair is composed of an insertion hole for inserting either the first protruding body ( Figure 3 of (23b)) or the second protruding body ( Figure 3 of (23c)) and an insertion hole for inserting the other of the first protruding body and the second protruding body that is not inserted into the above insertion hole. In each pair of the plurality of hole pairs, the distances between the two insertion holes are the same.

[0060] As Figure 6 shown, the two insertion holes of the hole pair are arranged along the short side direction of the first long side plate 43 ( Figure 6 the up and down direction). By inserting either the first protruding body 23b or the second protruding body 23c into either of the two insertion holes of the hole pair and inserting the other protruding body into the other insertion hole, the following can be explained. That is, one end portion in the long side direction of the filter membrane unit ( Figure 6 of (21)) can be positioned on the surface of the first long side plate 43 and the above end portion can be held by the first long side plate 43.

[0061] As Figure 2As shown, each of the two protrusions 24b that shield the side socket 24 has a cube shape or a rectangular parallelepiped shape. The two protrusions 24b are used to position the other end of the filter membrane unit ( Figure 6 21) in the long side direction at the shielding box ( Figure 6 60), and hold the other end at the shielding box.

[0062] In the suction side socket 23, each of the two protrusions (23b, 23c) integrally formed with the socket body 23a has a tubular shape.

[0063] Hereinafter, in each component, the length in the direction along the thickness direction of the flat filter membrane 22 is referred to as the width. In order to efficiently exhibit the filtering performance of the filter membrane 22, it is preferable that the inner diameters of the two protrusions (23b, 23c) of the suction side socket 23 are the same as the width of the filter membrane 22. Then, as Figure 2 shown, the peripheral walls of the two protrusions (23b 23c) protrude from the socket body 23a in the width direction. That is, the outer diameters of the two protrusions (23b, 23c) are larger than the width of the socket body 23a.

[0064] In this structure, miniaturization of the filtration system ( Figure 5 31) becomes difficult. Specifically, in order to achieve miniaturization of the filtration system, it is preferable to minimize the arrangement pitch in the arrangement direction of the plurality of filter membrane units ( Figure 6 21). Moreover, the narrowing of the above arrangement pitch is restricted by the outer diameters of the two protrusions (23b, 23c) of the suction side socket 23.

[0065] The reason why the narrowing of the above arrangement pitch is restricted by the outer diameters of the protrusions (23b, 23c) is as follows. That is, in each of the plurality of hole pairs provided on the first long side plate ( Figure 7 43), the insertion holes on one side in the short side direction of the first long side plate (43) among the two insertion holes are arranged along the long side direction of the first long side plate (43). In addition, in each of the plurality of hole pairs, the insertion holes on the other side in the short side direction of the first long side plate (43) among the two insertion holes are also arranged along the long side direction of the first long side plate (43). Hereinafter, two insertion holes adjacent to each other along the above long side direction are referred to as "two adjacent arranged insertion holes". Due to the miniaturization of the filtration system ( Figure 5 31), as the plurality of filter membrane units ( Figure 6The arrangement pitch (the arrangement pitch along the long side direction of the first long side plate 43) of 21) becomes smaller, and the distance between "two adjacent insertion holes" becomes shorter. If this distance is too short, the inter-hole length of the portion between the holes (the portion between "two adjacent insertion holes") of the first long side plate (43) is too small, and the required strength cannot be obtained in the inter-hole portion. In the above-mentioned inter-hole portion of the first long side plate (43), if the material and thickness of the first long side plate (43) are the same, the inter-hole length (narrow limit value) capable of obtaining the minimum strength is constant. On the other hand, even if the arrangement pitches of the plurality of filter membrane units 21 are the same, if the outer diameters of the protruding bodies (23b, 23c) are different, the above-mentioned inter-hole length is also different. The larger the outer diameter of the protruding bodies (23b, 23c), the smaller the inter-hole length (the lower the strength of the inter-hole portion). Therefore, the narrowing of the arrangement pitch of the insertion holes is restricted by the outer diameters of the protruding bodies (23b, 23c).

[0066] Therefore, in the suction side socket (23) of the filter membrane unit 21 of the embodiment, the two protruding bodies (23b, 23c) are respectively arranged in the Figure 3 manner shown. Specifically, it is a manner in which the distance α from the center in the extending direction of the socket body 23a (the position indicated by the single dotted line L1) to the first protruding body 23b and the distance β from the above center to the second protruding body 23c are different from each other (α < β). In this structure, compared with the case where the inter-hole length of the inter-hole portion of the first long side plate (43) is narrowed to the narrow limit value and the distance α and the distance β are the same as each other, the effect of reducing the arrangement pitch of the plurality of filter membrane units (21) can be achieved.

[0067] The reason for being able to achieve the above effect is as follows. That is, there are two types of multiple hole pairs provided on the Figure 7 first long side plate 43 shown. Among the multiple hole pairs, the first type is the first hole pair 43c, and the second type is the second hole pair 43f. The first hole pair 43c and the second hole pair 43f are alternately arranged along the long side direction of the first long side plate 43 (in the Figure 7 it is the up and down direction). The distance between the two insertion holes (43a, 43b) in the first hole pair 43c is the same as the distance between the two insertion holes (43d, 43e) in the second hole pair 43f. The insertion hole 43a on one side in the short side direction of the first long side plate 43 (in the Figure 7 it is the upper side) among the two insertion holes (43a, 43b) of the first hole pair 43c is arranged at a specified first position along the short side direction of the first long side plate 43 in the plane of the first long side plate 43. This first position is indicated by the single dotted line L2 in the Figure 7 . The insertion hole 43d on one side in the short side direction of the first long side plate 43 (in the Figure 7The insertion holes 43d (on the upper side in the figure) are arranged at a prescribed second position in the plane of the first long side plate 43 along the short side direction of the first long side plate 43. This second position is indicated by a single-dot chain line L3 in Figure 7 the figure. In the short side direction of the first long side plate 43, the above-mentioned first position and second position are different from each other.

[0068] For the first type of hole pair 43c, two protrusions (23b, 23c) of the filter membrane unit (21) adopting a prescribed first posture are inserted. In contrast, for the second type of hole pair 43f, two protrusions (23b, 23c) of the filter membrane unit (21) adopting a prescribed second posture are inserted. The filter membrane unit (21) adopting the first posture and the filter membrane unit (21) adopting the second posture are located at point-symmetrical positions (positions rotated 180°) with respect to the axis ( Figure 2 of the single-dot chain line L4) passing through the center of the extending direction of the suction side socket (23) and the center of the extending direction of the shielding side socket (24).

[0069] Hereinafter, in each component, the position shift along the short side direction of the first long side plate 43 is simply referred to as position shift. The insertion hole 43a arranged at the above-mentioned first position (single-dot chain line l2) among the two insertion holes (43a, 43b) of the first type of hole pair 43c and the insertion hole 43e arranged at the above-mentioned second position (single-dot chain line L2) among the two insertion holes (43d, 43e) of the second type of hole pair 43f are shifted in position from each other. For one of the two adjacent filter membrane units (21), the two protrusions (23b, 23c) of the suction side socket (23) are inserted into the two insertion holes (43a, 43b) of the first type of hole pair 43c. For the other filter membrane unit (21), the two protrusions (23b, 23c) of the suction side socket (23) are inserted into the two insertion holes (43d, 43e) of the second type of hole pair.

[0070] In this structure, in the long side direction of the first long side plate 43, the end on the other side of the adjacent arrangement insertion hole located on one side among the "two adjacent arrangement insertion holes" is located at a position on the other side than the end on one side of the adjacent arrangement insertion hole located on the other side, and the inter-hole part of the first long side plate 43 can be ensured. More specifically, in Figure 7 the figure, the long side direction of the first long side plate 43 is substantially along Figure 7 the left-right direction (strictly speaking, the above-mentioned long side direction is slightly inclined from Figure 7 the left-right direction), so hereinafter, the long side direction of the first long side plate 43 is regarded as Figure 7The left - right direction will be described. For example, among the multiple pairs of holes provided in the first long side plate 43, the insertion hole 43a of the first type of hole pair 43c, which is the left - most one in the left - right direction in the figure, and the insertion hole 43d of the second type of hole pair 43f adjacent to it on the right side in the left - right direction are regarded as "two adjacent - set insertion holes". The insertion hole 43a of the first type of hole pair 43c is located to the left of the insertion hole 43d of the second type of hole pair 43f in the left - right direction in the figure. That is, taking the insertion hole 43a of the first type of hole pair 43c as the adjacent - set insertion hole on the other side in the long - side direction of the first long side plate 43 among the "two adjacent - set insertion holes", and the insertion hole 43d of the second type of hole pair 43f as the adjacent - set insertion hole on one side in the above - mentioned long - side direction as an example. In this example, the end on the left side (the other side) of the insertion hole 43d of the second type of hole pair 43f is located to the left of the end on the right side (one side) of the insertion hole 43a of the first type of hole pair 43c. Maintaining such a positional relationship, and in the first long side plate 43, an inter - hole portion between the insertion hole 43a and the insertion hole 43d is ensured. The larger the positional offset between the insertion hole 43a and the insertion hole 43d, the larger the inter - hole length of the above - mentioned inter - hole portion. Therefore, even if the two protrusions (23b, 23c) of the suction - side socket (23) are enlarged in diameter, or the arrangement pitch of the multiple filter membrane units (21) is narrowed, by further increasing the above - mentioned positional offset, the inter - hole length can be made equal to or more than the narrow - limit value.

[0071] Therefore, according to the filtration system 31, it is possible to narrow the arrangement pitch of the multiple filter membrane units 21 without causing the positional offset (positional offset along the short - side direction of the first long side plate 43) of the multiple filter membrane units 21, and achieve miniaturization of the filtration system 31. In addition, according to the filtration system 31, it is also possible to enlarge the diameter of the two protrusions (23b, 23c) of the suction - side socket (23) and improve the filtration performance of the filter membrane 22.

[0072] Figure 6 The shielding box 60 shown has a plurality of shielding - side insertion holes (not shown) on the facing surface facing the multiple filter membrane units 21. These shielding - side insertion holes are insertion holes for inserting the protrusions 24b of the shielding - side socket 24 of the filter membrane unit 21. By inserting the two protrusions 24b of the shielding - side socket 24 into the shielding - side insertion holes provided on the above - mentioned facing surface respectively, the end on the other side in the long - side direction of the filter membrane unit 21 is positioned relative to the shielding box 60. In addition, the end on the other side in the long - side direction of the filter membrane unit 21 is held by the shielding box 60.

[0073] It should be noted that an example has been described in which a plurality of shielding-side insertion holes are arranged on the facing surface of the shielding box 60 facing the plurality of filter membrane units 21, and two protrusions 24b are provided on the shielding-side socket 24 of the filter membrane unit 21. However, the provision of the shielding-side insertion holes and the protrusions 24b can also be omitted. In this case, for example, by using the following rubber component, the ends of the plurality of filter membrane units 21 on the other side (shielding side) in the longitudinal direction can be held. That is, it is a rubber component having a base plate extending along the longitudinal direction of the shielding box 60 and a plurality of partition plates protruding from the surface of the base plate and arranged at a prescribed arrangement pitch along the longitudinal direction of the shielding box 60. The shielding-side socket 24 of the filter membrane unit 21 can be sandwiched between two adjacent partition plates of the rubber component.

[0074] In addition, an example in which the shape of the filter membrane 22 is flat has been described. However, the shape of the filter membrane 22 is not limited to flat, and it can also be corrugated plate shape or the like, for example.

[0075] Stress is applied to the filter membrane unit 21 by the flow of raw water (W 1 ) existing around the filter membrane unit 21, the bubbles released from the bubble generating device 90, etc. Through this stress, a force (skewing force) is applied to the filter membrane unit 21 to cause the short side direction of the filter membrane 22 to be inclined from the short side directions of the water collection box 41 and the shielding box 60 (in Figure 6 it is the up and down direction). Through this skewing force, a relatively large force is applied to the regions in the entire area of the filter membrane 22 that are close to the first protrusion 23b of the suction-side socket 23, the second protrusion 23c close to the suction-side socket, and the two protrusions 24b close to the shielding-side socket 24. Hereinafter, the above four regions are collectively referred to as the regions near the protrusions.

[0076] As Figure 3 shown, the first protrusion 23b of the suction-side socket 23 is located on one side (the upper side in this figure) of the second protrusion 23c in the extending direction of the socket body 23a (the up and down direction in this figure). In addition, the first protrusion 23b exists at a position offset from one end (the upper end in this figure) in the extending direction of the socket body 23a to the other side (the lower side in this figure) (hereinafter, the amount of this offset is referred to as the "first offset amount"). Furthermore, the second protrusion 23c exists at a position offset from the other end (the lower end in this figure) in the extending direction of the socket body 23a to one side (the upper side in this figure) (hereinafter, the amount of this offset is referred to as the "second offset amount").

[0077] Hereinafter, among the two protrusions 24b provided on the shielding side socket 24, the protrusion located on one side (the upper side in this figure) in the extending direction of the socket main body (24a) (the vertical direction in this figure) is referred to as the "protrusion 24b on one side". In addition, among the two protrusions 24b, the protrusion located on the other side (the lower side in this figure) in the above-mentioned extending direction is referred to as the "protrusion 24b on the other side". The "protrusion 24b on one side" exists at a position offset from the end on one side in the extending direction of the socket main body (24a) (the upper end in this figure) to the other side (the lower side in this figure) (hereinafter, the amount of this offset is referred to as the "third offset amount"). In addition, the "protrusion 24b on the other side" exists at a position offset from the end on the other side in the extending direction of the socket main body (24a) (the lower end in this figure) to one side (the upper side in this figure) (hereinafter, the amount of this offset is referred to as the "fourth offset amount").

[0078] A second comparative example different from the Figure 3 example shown is studied as a comparison object with the Figure 3 example shown. In the second comparative example, the first protrusion 23b of the attracting side socket 23 is located at the end on one side in the extending direction of the socket main body 23a (the upper end in this figure). In addition, the second protrusion 23c of the attracting side socket 23 is located at the end on the other side in the extending direction of the socket main body 23a (the lower end in this figure).

[0079] In the shielding side socket 24 of the second comparative example, the "protrusion 24b on one side" is located at the end on one side in the extending direction of the socket main body (24a) (the upper end in this figure). In addition, the "protrusion 24b on the other side" is located at the end on the other side in the extending direction of the socket main body (24a) (the lower end in this figure).

[0080] That is, in the second comparative example, the "first offset amount", "second offset amount", "third offset amount", and "fourth offset amount" are all zero. In the second comparative example with this structure, the distance between the first protrusion 24b and the second protrusion 24c of the attracting side socket 23 is longer than that in the filter membrane unit 21 of the embodiment. In addition, in the second comparative example, the distance between the "protrusion 24b on one side" and the "protrusion 24b on the other side" of the shielding side socket 24 is longer than that in the filter membrane unit 21 of the embodiment. Therefore, in the second comparative example, according to the lever principle, the force applied to the area near the protrusion of the filter membrane 22 is greater than that in the filter membrane unit 21 of the embodiment. Therefore, breakage of the filter membrane 22 is likely to occur. In other words, by not arranging each protrusion at the end in the extending direction of the socket, the filter membrane unit 21 of the embodiment can suppress breakage of the filter membrane 22 caused by the skew force.

[0081] In the filtration membrane unit 21 of the embodiment, in order to efficiently suppress breakage of the filtration membrane 22, it is preferable to increase the "first offset", "second offset", "third offset", and "fourth offset" as much as possible. However, in the suction-side socket 23, if the "first offset" and "second offset" are made too large, it becomes difficult to equalize the water collection amounts from the first protrusion 23b and the second protrusion 23c. In order to achieve the above equalization, it is preferable to set the "first offset" and "second offset" to 1 / 10 or less of the length in the extending direction of the socket body 23a of the suction-side socket 23. More preferably, the range is 1 / 4 to 1 / 3 of the length in the extending direction of the socket body 23a of the suction-side socket 23. The same applies to the "third offset" and "fourth offset" in the shielding-side socket 24.

[0082] A filtration system (31) that employs a so-called single-sided suction method in which only one side out of both sides in the long side direction of the filtration membrane 22 is used as the suction side has been described, but a so-called double-sided suction method in which both sides are used as the suction side can also be employed. In this case, suction-side sockets 23 having the same structure may be provided as the sockets for both sides.

[0083] Figure 8 It is a perspective view showing the filtration processing apparatus 20 of the embodiment. The filtration processing apparatus 20 includes three filtration systems 31. The three filtration systems 31 are arranged along the short side direction of the first long side plate (43). In this figure, since the above short side direction is along the vertical direction, the structure of the filtration processing apparatus 20 becomes a three-layer structure in which the three filtration systems 31 are stacked in the vertical direction.

[0084] Figure 9 It is a perspective view showing the water collection box 41 of the filtration system (31) arranged on one side (the upper side in this figure) in the short side direction of the first long side plate (43), the water collection box 41 of the filtration system (31) arranged on the other side (the lower side in this figure) in the above short side direction, and the connection pipe 70. The connection pipe 70 functions to connect the two water collection boxes 41. In Figure 9 On the top plates 42 of the two shown water collection boxes 41, three top plate openings 42a are arranged at a predetermined interval along the long side direction of the top plate 42. The top plate openings 42a face one side (the upper side in this figure) in the short side direction (the vertical direction in this figure) of the first long side plate 43.

[0085] Three cylindrical first connection sockets 50 are arranged inside the water collection box 41. These first connection sockets 50 are fixed to the back surface of the top plate 42 and communicate with the top plate openings 42a.

[0086] On the bottom plate 45 of each of the three water collecting boxes 41, three bottom plate openings 45a are arranged at regular intervals along the long side direction of the bottom plate 45. The bottom plate openings 45a face the other side (the lower side in this figure) in the short side direction of the first long side plate 43.

[0087] One of the three top plate openings 42a and one of the three bottom plate openings 45a face each other along the short side direction of the first long side plate 43. Further, another one of the three top plate openings 42a and another one of the three bottom plate openings 45a face each other along the above-mentioned short side direction. Further, the last one of the three top plate openings 42a and the last one of the three bottom plate openings 45a face each other along the above-mentioned short side direction.

[0088] Three cylindrical second connection sockets 51 are arranged inside the water collecting box 41. These second connection sockets 51 are fixed to the back surface of the bottom plate 45 and communicate with the bottom plate openings 45a.

[0089] The water collecting box 41 arranged on the lower side in this figure and the water collecting box 41 arranged on the upper side in this figure are connected by three connecting pipes 70. The connecting pipes 70 are arranged such that the pipe length direction is along the short side direction of the first long side plate 43 (the up and down direction in this figure). At the ends on one side and the other side in the above-mentioned short side direction of the connecting pipe 70, annular recesses (not shown) extending over the entire circumferential surface of the pipe are respectively arranged, and O-rings 71 are inserted into the respective annular recesses.

[0090] The end on one side (the upper side in this figure) in the above-mentioned short side direction of the connecting pipe 70 is inserted into the second connection socket 51 of the water collecting box 41 on the upper side in this figure. Further, the end on the other side (the lower side in this figure) in the above-mentioned short side direction of the connecting pipe 70 is inserted into the first connection socket 50 of the water collecting box 41 on the upper side in this figure. The internal space of the water collecting box 41 on the upper side in this figure and the internal space of the water collecting box 41 on the lower side in this figure communicate with each other through the three connecting pipes 70.

[0091] It should be noted that in the lowermost water collecting box 41 among the three water collecting boxes 41 stacked in a three-layer overlapping manner, instead of inserting the connecting pipe 70 into each of the three second connection sockets 51, a sealing plug (not shown) is inserted into each second connection socket 51. Thereby, it is possible to prevent the suction force generated in the internal space of the lowermost water collecting box 41 from leaking to the outside through the second connection socket 51.

[0092] Further, in the uppermost water collecting box 41 among the three water collecting boxes 41 stacked in a three-layer overlapping manner, instead of inserting the connecting pipe 70 into the three first connection sockets 50, water collecting branch pipes are inserted. These water collecting branch pipes are connected to one treated water transfer pipe ( Figure 1 of 8).

[0093] The treated water that has passed through the filter membranes of a plurality of filter membrane units (not shown) held by the first long side plate 43 of the water collection box 41 flows into the inner space of the water collection box 41 on the lower side of this figure. In addition, the treated water that has passed through the filter membranes of a plurality of filter membrane units (not shown) held by the first long side plate 43 of the water collection box 41 flows into the inner space of the water collection box 41 on the upper side of this figure. The treated water present in the inner space of the water collection box 41 on the lower side of this figure is attracted through the connection pipe 70 into the inner space of the water collection box 41 on the upper side by the suction force generated inside the connection pipe 70.

[0094] That is, in Figure 8 each of the three filtration systems 31 shown, the treated water that has passed through each of the plurality of filter membranes 22 is collected in the water collection box 41. Moreover, in the water collection box 41 of each of the three filtration systems 31, the treated water in the inner space of the water collection box 41 located on the lower side is attracted into the inner space of the water collection box 41 located on the upper side. As a result, after the treated water collected in the inner space of each of the three water collection boxes 41 is finally collected in the inner space of the uppermost water collection box 41, it is transferred to the treatment water tank ( Figure 1 3).

[0095] In Figure 9 the connection pipe 70 shown, as described above, the pipe length direction is along the short side direction of the first long side plate 43. The O-ring 71 embedded at one end (the upper side in this figure) in the short side direction of the connection pipe 70 prevents the end inserted into the second connection socket 51 from falling off the second connection socket 51 and improves the sealing performance between the end and the second connection socket 51. In order to more reliably prevent the above-mentioned detachment or further improve the above-mentioned sealing performance, a plurality of O-rings 71 arranged in the short side direction may also be embedded at the above-mentioned end.

[0096] The O-ring 71 embedded at the other end (the lower side in this figure) in the short side direction of the connection pipe 70 prevents the end inserted into the first connection socket 50 from falling off the first connection socket 50 and improves the sealing performance between the end and the first connection socket 50. In order to more reliably prevent the above-mentioned detachment or further improve the above-mentioned sealing performance, a plurality of O-rings 71 arranged in the short side direction may also be embedded at the above-mentioned end.

[0097] The number of the top plate opening 42a, the bottom plate opening 45a, the first connection socket 50, the second connection socket 51, and the connection pipe 70 is not limited to three. As long as it is one or more.

[0098] In the filter unit described in Patent Document 1, the filtrate outlet as the discharge port faces the direction in which the filtrate is discharged along the short side direction of the ceramic filter. In the filter system as a filter system having a plurality of filter units, the filtrate discharged from the filtrate outlets of the respective plurality of filter units is collected by the filtrate collection pipe. This filtrate collection pipe is arranged in a manner that follows the short side direction of the ceramic filter with respect to the plurality of filter units according to the discharge direction of the filtrate from the filtrate outlet. In this structure, if a multi-layer method of overlapping a plurality of filter systems in the vertical direction is adopted, the height dimension of the filter system increases correspondingly because a filtrate collection pipe is interposed between the respective filter units in the upper and lower filter systems.

[0099] In contrast, in the filtration processing apparatus (20) of the embodiment, the first outlet (23b-2) and the second outlet (23c-2) as the discharge holes respectively face the direction in which the treated water is discharged along the long side direction of the filter membrane (22). The filtration system (31) having a plurality of filter membrane units (21) collects the treated water discharged from the first outlet (23b-2) and the second outlet (23c-2) of the respective plurality of filter membrane units (21) through the water collection box (41). This water collection box (41) is arranged in a manner that follows the long side direction of the filter membrane (22) with respect to the plurality of filter membrane units (21) according to the discharge direction of the treated water discharged from the first outlet (23b-2) and the second outlet (23c-2) respectively. In this structure, even if a multi-layer method of overlapping a plurality of filtration systems (31) in the vertical direction is adopted, different from the filter system described in Patent Document 1, a filtrate collection pipe is not interposed between the respective filter membrane units (21) in the upper and lower filtration systems (31). Therefore, corresponding to the fact that a filtrate collection pipe is not interposed between the respective filter membrane units (21) in the upper and lower filtration systems (31), the height dimension of the filtration system (31) can be reduced, and miniaturization in the height direction of the filtration processing apparatus (20) can be achieved.

[0100] Although the filtration processing apparatus (20) in which a plurality of filtration systems (31) are stacked in a multi-layer manner has been described, a multi-connected method in which a plurality of filtration systems (31) are connected horizontally can also be adopted. In addition, both the multi-layer method and the multi-connected method can be adopted.

[0101] Next, an embodiment in which a more characteristic structure is added to the filtration processing apparatus (20) of the embodiment will be described. It should be noted that unless otherwise specified, the structure of the filtration processing apparatus (20) of the embodiment is the same as that of the embodiment.

[0102] The filtration system (31) of the filtration processing apparatus (20) in the embodiment assumes an upside-down posture. The respective insertion holes are configured such that even when the posture of the filtration system (31) is thus turned upside down, the two-dimensional layout of the respective insertion holes on the plane of the first long side plate (43) of the water collection box (41) is the same as before the upside-down turn. Further, in the water collection box (41), the plate material that functions as the top plate (42) before the upside-down turn functions as the bottom plate (45) after the upside-down turn, and the plate material that functions as the bottom plate (45) before the upside-down turn functions as the top plate (42) after the upside-down turn. In the region from one end to the other end in the longitudinal direction of the water collection box (41), the relative positions of the three top plate openings (42a) of the top plate (42) before the upside-down turn are the same as the relative positions of the three top plate openings (42a) of the top plate (42) after the upside-down turn. Accordingly, in the region from one end to the other end in the longitudinal direction of the water collection box 41, the relative positions of the three bottom plate openings (45a) of the bottom plate (45) before the upside-down turn are the same as the relative positions of the three bottom plate openings (45a) of the bottom plate (45) after the upside-down turn. Accordingly, in the filtration processing apparatus (20) of the embodiment, the filtration system (31) can be processed without considering the upside-down posture of the filtration system (31).

[0103] Figure 10 is a cross-sectional view showing a longitudinal section of two water collection boxes 41 stacked one above the other in the filtration processing apparatus (20) of the embodiment together with a cross-section of the connection pipe 70. Figure 11 is a cross-sectional view showing a magnification of the cross-section of the connection pipe 70 Figure 10 in an enlarged manner.

[0104] As Figure 11 shown, the three first connection sockets 50 fixed to the top plate 42 of the water collection box 41 each have an internal thread portion 50a on the inner circumferential surface. The internal thread portion 50a is provided in a region biased upward in the entire region in the pipe length direction of the first connection socket 50 formed of a pipe material. Further, the three second connection sockets 51 fixed to the bottom plate 45 of the water collection box 41 each have an internal thread portion 51a on the inner circumferential surface. The internal thread portion 51a is provided in a region biased downward in the entire region in the pipe length direction of the second connection socket 51 formed of a pipe material.

[0105] When the posture of the water collection box 41 is turned upside down, the plate material that functions as the top plate 42 before the upside-down turn functions as the bottom plate 45, and the pipe material that functions as the first connection socket 50 before the upside-down turn functions as the second connection socket 51. As Figure 11As shown, the connecting pipe 70 has an external thread portion 70a on its outer peripheral surface. The external thread portion 70a is provided in a region biased to one side in the entire region in the pipe length direction of the connecting pipe 70. The connecting pipe 70 is used in such a manner that one end portion having the external thread portion 70a among the two end portions in the pipe length direction of the connecting pipe 70 is located below the other end portion.

[0106] In Figure 10 Among them, the three connecting pipes 70 are respectively inserted into the first connection socket 50 while screwing their external thread portions 70a with the internal thread portion 50a of the first connection socket 50 of the lower water collecting box 41 among the two water collecting boxes 41. Through the above screwing, it is possible to prevent the connecting pipe 70 from falling off from inside the first connection socket 50. In addition, when separating the upper water collecting box 41 and the lower water collecting box 41 for maintenance inspection work, the state of holding the three connecting pipes 70 in the lower water collecting box 41 can be reliably maintained. Therefore, the workability of maintenance inspection can be improved.

[0107] In the filtration treatment device (20), the connecting pipe 70 is not inserted into the second connection socket 51 in the water collecting box 41 of the lowermost filtration system (31) among the three filtration systems (31) stacked in a three-layer overlapping manner. Instead, a sealing plug (not shown) having an external thread portion on its outer peripheral surface is inserted into the second connection socket 51. At this time, the sealing plug is inserted into the second connection socket 51 while screwing its external thread portion with the internal thread portion 51a of the second connection socket 51. In this way, the sealing plug inserted into the second connection socket 51 can be prevented from falling off from inside the second connection socket 51 through the above screwing.

[0108] In the first connection socket 50 in the water collecting box 41 of the uppermost filtration system (31) among the three filtration systems (31) in the filtration treatment device (20), the connecting pipe 70 is not inserted. Instead, the above-mentioned water collecting branch pipe is inserted into the first connection socket 50. An external thread portion is provided on the outer peripheral surface of the water collecting branch pipe. The water collecting branch pipe is inserted into the first connection socket 50 while screwing its external thread portion with the internal thread portion of the first connection socket 50. In this way, the water collecting branch pipe inserted into the first connection socket 50 can be prevented from falling off from inside the first connection socket 50 through the above screwing.

[0109] The present invention is not limited to the above-described embodiments and examples, and within the scope where the structure of the present invention can be applied, a structure different from the embodiments and examples can also be adopted. The present invention has unique effects in each of the following modes.

[0110] 〔First mode〕

[0111] The filtration membrane unit of the first mode (e.g., the filtration membrane unit 21) includes: a filtration membrane (e.g., the filtration membrane 22) and a socket (e.g., the suction side socket 23). The socket is fixed to one end of the filtration membrane in the longitudinal direction to hold the filtration membrane on one side in the longitudinal direction. The socket extends along the short side direction of the filtration membrane in the state of being fixed to the end. And the socket includes: a recess (e.g., the recess 23d) for inserting the end, a flow path (e.g., the flow path 23e) communicating with the recess and extending along the extending direction of the socket, and a discharge port for discharging the filtrate in the flow path. It is characterized in that the socket has a first outlet (e.g., the first outlet 23b-2) and a second outlet (e.g., the second outlet 23c-2) as the discharge port. The first outlet is arranged at a position on one side of the center of the extending direction of the socket closer to the extending direction, and the second outlet is arranged at a position on the other side of the center of the extending direction of the socket closer to the extending direction.

[0112] According to this structure, similarly to the filtration membrane unit (21) of the embodiment, the maintainability of the filtration membrane can be improved.

[0113] 〔Second mode〕

[0114] The second mode is characterized in that in the filtration membrane unit having the structure of the first mode, the socket includes a socket body (e.g., the socket body 23a), a first protrusion (e.g., the first protrusion 23b), and a second protrusion (e.g., the second protrusion 23c). The socket body includes the recess and the flow path. The first protrusion and the second protrusion are respectively arranged in a manner of being located outside the socket body in the longitudinal direction of the filtration membrane and arranged along the extending direction of the socket body.

[0115] According to this structure, similarly to the filtration membrane unit (21) of the embodiment, one end of the filtration membrane unit in the longitudinal direction can be held by the holding body using the first protrusion and the second protrusion.

[0116] 〔Third mode〕

[0117] The third mode is characterized in that in the filtration membrane unit having the structure of the second mode, the first outlet is provided on the first protrusion and communicates with the flow path through the hollow (e.g., the hollow 23b-1) of the first protrusion. The second outlet is provided on the second protrusion and communicates with the flow path through the hollow (e.g., the hollow 23c-1) of the second protrusion.

[0118] According to this structure, similar to the filtration membrane unit (21) of the embodiment, the treated water in the filtration membrane unit can be discharged from the filtration membrane unit by using the first protrusion and the second protrusion for holding one end portion in the long side direction of the filtration membrane unit with respect to the holding body.

[0119] 〔Fourth mode〕

[0120] In the fourth mode, in the filtration membrane unit having the structure of the third mode, it is characterized in that the first outlet is arranged on the front end surface of the first protrusion, and the second outlet is arranged on the front end surface of the second protrusion.

[0121] According to this structure (front end surface arrangement), different from the circumferential surface arrangement, the flow direction of the treated water is not greatly changed in the hollows of the first protrusion and the second protrusion respectively. Therefore, compared with the circumferential surface arrangement, the flow path resistance can be reduced.

[0122] 〔Fifth mode〕

[0123] In the fifth mode, in the filtration membrane unit having the structure of the third mode or the fourth mode, it is characterized in that the distance from the center in the extending direction of the socket body to the first protrusion is different from the distance from the center to the second protrusion.

[0124] According to this structure, similar to the filtration membrane unit (21) of the embodiment, compared with the case where the inter-hole length of the inter-hole portion of the side plate is narrowed to the narrow limit value and the former distance and the latter distance are made the same, the arrangement pitch of a plurality of filtration membrane units can be reduced, and miniaturization of the filtration system can be achieved.

[0125] 〔Sixth mode〕

[0126] The holding body of the sixth mode (e.g., the holding body 40) holds each of a plurality of filter membrane units, and is characterized by including a side plate (e.g., the first long side plate 43) that holds one end portion in the long side direction of each of the plurality of filter membrane units. Each of the plurality of filter membrane units is a filter membrane unit of the fifth mode. The side plate includes a plurality of hole pairs, and each hole pair is composed of an insertion hole into which either the first protrusion or the second protrusion is inserted and an insertion hole into which the other of the first protrusion and the second protrusion that is not inserted into the insertion hole is inserted. In each of the plurality of hole pairs, the two insertion holes are arranged along the short side direction of the side plate. In each of the plurality of hole pairs, the distances between the two insertion holes in the short side direction are the same. The first type of hole pairs (e.g., the first type of hole pairs 43c) classified as the first type among the plurality of hole pairs and the second type of hole pairs (e.g., the second type of hole pairs 43f) classified as the second type among the plurality of hole pairs are alternately arranged along the long side direction of the side plate. The insertion hole located on one side in the short side direction of the two insertion holes of the first type of hole pair (e.g., the insertion hole 43d, the insertion hole 43e) is arranged at a prescribed first position along the short side direction within the plane of the side plate. The insertion hole located on one side in the short side direction of the two insertion holes of the second type of hole pair is arranged at a prescribed second position along the short side direction within the plane of the side plate. The first position and the second position are different from each other.

[0127] According to this structure, it is possible to narrow the arrangement pitch of a plurality of filter membrane units (21) having the structure of the fifth mode, and to miniaturize the filtration system.

[0128] 〔Seventh mode〕

[0129] The filtration system of the seventh mode (e.g., the filtration system 31) includes a plurality of filter membrane units and a holding body that holds these filter membrane units, and is characterized in that each of the plurality of filter membrane units is a filter membrane unit having the structure of any one of the first mode to the fifth mode.

[0130] According to this structure, it is possible to improve the maintainability of a plurality of filter membrane units mounted on the filtration system.

[0131] 〔Eighth mode〕

[0132] The eighth mode is a filtration system having the structure of the seventh mode, and is characterized in that each of the plurality of filter membrane units is a filter membrane unit having the structure of the fifth mode, and the holding body is a holding body of the sixth mode.

[0133] According to this structure, it is possible to narrow the arrangement pitch of a plurality of filter membrane units and to miniaturize the filtration system.

[0134] 〔Ninth mode〕

[0135] The ninth mode is a filtration processing device (such as the filtration processing device 20) composed of a combination of multiple filtration systems, characterized in that the multiple filtration systems are respectively filtration systems having the structure of the seventh mode or the eighth mode.

[0136] According to this structure, by narrowing the arrangement pitch of the multiple filtration membrane units, miniaturization of the multiple filtration systems can be achieved, and thus miniaturization of the filtration processing device can be achieved.

[0137] Explanation of reference numerals

[0138] 20 Filtration processing device, 21 Filtration membrane unit, 22 Filtration membrane, 23 Suction side socket (socket), 23a Socket body, 23b First protrusion, 23b-1 Hollow, 23b-2 First outlet, 23c Second protrusion, 23c-1 Hollow, 23c-2 Second outlet, 23d Recess, 23e Flow path, 31 Filtration system.

Claims

1. A filtration system, the filtration system comprising a plurality of filtration membrane units and a holder for holding these filtration membrane units side by side, Characterized in that, The filtration membrane unit comprises: A filtration membrane; and A suction side socket, the suction side socket being fixed to an end portion of the filtration membrane in the longitudinal direction, extending along the short side direction of the filtration membrane to form a flow path for the filtrate to flow, On the suction side socket, a plurality of protrusions each having a discharge port for the filtrate are arranged at intervals on one side and the other side in the short side direction, The holder has a plurality of first holes into which the protrusions on the one side are respectively inserted and a plurality of second holes into which the protrusions on the other side are respectively inserted, Between a first filtration membrane unit and a second filtration membrane unit arranged adjacent to the first filtration membrane unit, the positions of the first holes into which the protrusions on the one side are inserted and the positions of the second holes into which the protrusions on the other side are inserted are respectively offset in the short side direction.

2. The filtration system according to claim 1, Characterized in that, The filtration membrane is in a flat plate shape or a corrugated plate shape.

3. The filtration system according to claim 1, Characterized in that, The filtration membrane unit has: a first protrusion arranged at a first distance from the center of the suction side socket in the short side direction; and a second protrusion arranged at a second distance different from the first distance from the center of the suction side socket in the short side direction, In the first filtration membrane unit, the protrusion on the one side inserted into the first hole is the first protrusion, and the protrusion on the other side inserted into the second hole is the second protrusion, In the second filtration membrane unit, the protrusion on the one side inserted into the first hole is the second protrusion, and the protrusion on the other side inserted into the second hole is the first protrusion.

4. The filtration system according to claim 3, Characterized in that, Each of the filtration membrane units has the suction side socket mounted on one side in the longitudinal direction and supports the other side in the longitudinal direction via a shielding side socket mounted on the other side in the longitudinal direction, The first protrusion provided on the suction side socket is arranged at a position offset to one side in the short side direction of the filtration membrane and at a position offset toward the center side of the suction side socket from one end of the suction side socket, A first offset amount representing the magnitude of the offset of the first protrusion relative to the second protrusion and a second offset amount representing the magnitude of the offset of the first protrusion relative to one end of the suction side socket are respectively set within a range of 1 / 4 to 1 / 3 of the length of the suction side socket in the extending direction.

5. The filtration system according to claim 4, Characterized in that, The first filtration membrane unit and the second filtration membrane unit are located at positions that are point-symmetrical with respect to an axis passing through the center of the extending direction of the suction side socket and the center of the extending direction of the shielding side socket, The holding body holds the first filter membrane unit and the second filter membrane unit alternately in a direction intersecting with the long side direction and the short side direction.

6. A filtration processing device composed of a combination of multiple filtration systems, characterized in that the multiple filtration systems are respectively the filtration systems described in any one of claims 1 to 5.

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