JP2006192335A - Rotary flat membrane module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary flat membrane module capable of preventing damage of the filtration film of the rotary flat membrane disk. <P>SOLUTION: The rotary flat membrane module 10 consists of rotation shafts 22A to 22C arranged in parallel and rotary flat membrane disks 12 attached to the shafts 22A to 22C, and the outer edge 32A of a supporting plate 32 for the rotary flat membrane disk 12 is protruded from the face of a filtration membrane 36 attached to the side surface of the plate 32. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotary flat membrane module, and more particularly, to a rotary flat membrane module used in a water treatment facility.

  In recent years, many membrane separators have been put into practical use as solid-liquid separators for filtration. There are various module shapes such as a hollow fiber type, a spiral type, a flat membrane type, and a rotating flat membrane type in the membrane separation apparatus. Among these, the rotary flat membrane module is composed of a rotary flat membrane disc in which a circular support plate (disc) is covered with a filtration membrane, and a rotary shaft on which the rotary flat membrane disc is attached at a predetermined interval. Filtration is performed by generating a suction force inside the rotating flat membrane disk while rotating (see, for example, Patent Documents 1 and 2). According to this rotary flat membrane module, the rotation of the rotary flat membrane disk gives a membrane surface flow velocity to the surface of the filtration membrane, and can prevent the dirt layer from adhering to the filtration membrane.

Such a rotating flat membrane module has a problem that when the rotating flat membrane disk rotates at a high speed, the raw water (liquid to be filtered) rotates together with the rotating flat membrane disk and a sufficient membrane surface flow velocity cannot be obtained. is there. Therefore, a rotating flat membrane module has been proposed in which a plurality of rotating shafts are arranged in parallel and the rotating flat membrane disks attached to the respective rotating shafts are arranged so as to overlap each other when viewed in the direction of the rotating shaft. According to this rotating flat membrane module, since turbulent flow is generated between the rotating flat membrane disks, it is possible to prevent co-rotation of raw water.
JP-A-10-146521 Japanese Utility Model Publication 3-41785

  However, in the conventional rotary flat membrane module, when the support plate of the rotary flat membrane disc is deformed and the adjacent rotary flat membrane discs come into contact with each other, the filtration membrane is damaged, and the raw water is not filtered and becomes treated water. There was a risk of mixing. For example, when the rotating flat membrane disk of Patent Document 1 is used, there is a risk that the filtration membranes may be damaged by contact with each other, or the adhesive applied to the outer edge portion of the filtration membrane may be peeled off and leakage may occur. there were. Moreover, when the rotating flat membrane disk of patent document 2 was used, the stirring member attached to the membrane surface of the filtration membrane contacted, and there existed a problem that a filtration membrane was damaged and leakage generate | occur | produced. For this reason, in the conventional device, in order to prevent the contact between the rotating flat membrane disks, the interval between the rotating flat membrane disks must be increased more than necessary, and the effect of turbulent flow cannot be obtained sufficiently, There was a problem that the entire flat membrane module was enlarged.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a rotating flat membrane module capable of preventing the filtration membrane of the rotating flat membrane disk from being damaged.

  In order to achieve the above object, the invention according to claim 1 is attached to each of the plurality of rotating shafts arranged in parallel and the plurality of rotating shafts, and covers both surfaces of the circular support plate with a filtration membrane. A rotating flat membrane module comprising: a plurality of rotating flat membrane discs configured by: and arranged so that the rotating flat membrane discs mounted on different rotating shafts partially overlap each other when viewed in the direction of the rotating shaft The outer edge portion of the support plate is formed to protrude from the membrane surface of the filtration membrane.

  According to the invention described in claim 1, since the outer edge portion of the support plate protrudes from the membrane surface of the filtration membrane, the outer edge portions of the support plate come into contact with each other when the interval between the rotating flat membrane disks is narrowed. The contact between the filtration membranes can be prevented. Therefore, it is possible to prevent the filtration membrane from being damaged and broken.

  In order to achieve the above-mentioned object, the invention according to claim 2 is constituted by a plurality of rotating shafts arranged in parallel, each of which is attached to the plurality of rotating shafts, and a circular support plate is covered with a filtration membrane. A rotating flat membrane module comprising: a plurality of rotating flat membrane discs arranged so that the rotating flat membrane discs mounted on different rotating shafts partially overlap each other when viewed in the direction of the rotating shaft; A protective ring is provided on the outer peripheral portion of the flat membrane disk and is thicker than the rotating flat membrane disk.

  According to the second aspect of the present invention, since the protective ring thicker than the rotating flat membrane disk is mounted on the outer peripheral portion of the rotating flat membrane disk, it is protected that the filtration membranes of the rotating flat membrane disk are in contact with each other. Can be prevented by the ring. Therefore, it is possible to prevent the filtration membrane from being damaged and broken.

  According to a third aspect of the present invention, in the second aspect of the present invention, the protection ring is constituted by a long member in which a groove into which an outer peripheral portion of the rotating flat membrane disk is inserted is formed in the longitudinal direction. Features. Therefore, according to the invention of claim 3, the long member is mounted by being wound around the outer peripheral portion of the rotating flat membrane disk while the outer peripheral portion of the rotating flat membrane disk is fitted in the groove of the long member. it can. Since such a protective ring can be retrofitted to the rotating flat membrane disk, it can also be attached to an existing rotating flat membrane disk.

  The invention according to claim 4 is the invention according to claim 3, characterized in that notches are formed in the longitudinal direction at predetermined intervals on the surface of the elongated member where the groove is formed. Therefore, according to the invention of claim 4, since the long member is configured to be easily bent toward the groove surface, the long member can be easily mounted on the outer peripheral portion of the rotating flat membrane disk.

  According to a fifth aspect of the present invention, in any one of the second to fourth aspects, the outer peripheral surface of the protective ring is formed with a through hole communicating with the inner peripheral surface of the protective ring. To do. Therefore, according to the invention of claim 5, the liquid to be filtered outside the protective ring can be taken into the protective ring. Therefore, the flow volume of the process liquid which permeate | transmits the filtration membrane inside a protection ring can be increased, and filtration efficiency can be improved.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the outer peripheral surface of the protection ring is provided with a scraping portion for scraping the liquid to be filtered into the through hole. Therefore, according to the invention of claim 6, a large amount of liquid to be filtered can be scraped into the inside of the protective ring, and the filtration efficiency can be further improved.

  According to the rotating flat membrane device according to the present invention, since the protective ring thicker than the rotating flat membrane disk is mounted on the outer peripheral portion of the rotating flat membrane disk, the protective ring prevents the filtration membranes of the rotating flat membrane disk from contacting each other. Can be prevented. Therefore, it is possible to prevent the filtration membrane from being damaged and broken.

  Hereinafter, preferred embodiments of a rotating flat membrane module according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a first embodiment of a rotating flat membrane module 10 according to the present invention, and FIG. 2 is a perspective view showing a part of its internal configuration. 3 is a plan sectional view showing a part of the internal configuration of the rotary flat membrane module 10, and FIG. 4 is a perspective view showing the configuration of the rotary flat membrane disk.

  As shown in FIG. 1, the rotary flat membrane module 10 has a treatment tank 14, and raw water (liquid to be treated) flows into the treatment tank 14 from an inflow pipe 16. A large number of rotating flat membrane disks 12, 12,... Are provided inside the processing tank. As shown in FIG. 2, the rotating flat membrane disk 12 is attached to three rotating shafts 22A, 22B, and 22C arranged in parallel at a predetermined interval. The rotating shafts 22A to 22C are connected to motors 20A, 20B, and 20C via couplings 18A, 18B, and 18C provided outside the processing tank 14 of FIG. Therefore, the rotating shafts 22A to 22C can be rotated by driving the motors 20A to 20C. In addition, each motor 20A-20C is comprised so that rotation shaft 22A-22C may be rotationally driven in the same direction. Further, speed reducers 21A to 21C are provided between the motors 20A to 20C and the couplings 18A to 18C so that the rotational speeds of the rotary shafts 22A to 22C can be accurately controlled.

  The rotary shafts 22A to 22C are formed in a hollow shape, and the inside thereof communicates with the inside of each rotary flat membrane disk 12, 12,. Furthermore, the inside of the rotating shafts 22A to 22C is communicated with the treated water pipe 24. By driving the pump 26, a suction force is generated therein, and the fluid in the rotating shafts 22A to 22C is discharged from the treated water pipe 24. It has become. In addition, the code | symbol 27 of FIG. 1 is a flowmeter which measures the flow volume of the treated water which flows through the treated water pipe 24. FIG. Reference numeral 28 denotes a drain pipe for draining concentrated water from the treatment tank 14, and reference numeral 30 denotes a control panel in which a control system of the rotating flat membrane module 10 is accommodated.

  As shown in FIGS. 3 and 4, the rotating flat membrane disk 12 is provided with a circular support plate 32 called a disk, water-permeable spacers 34 provided on both surfaces of the support plate 32, and further provided on both outer surfaces thereof. The circular filter membrane 36 is formed. The spacer 34 is formed by combining nonwoven fabric, punching metal, and the like, and has water permeability. As the filtration membrane 36, an ultrafiltration membrane (UF membrane) is used, and as a material thereof, for example, a polymer resin membrane such as polystyrene, polypropylene, polyethylene, or polyolefin is used. The type of the filtration membrane 36 is not limited to an ultrafiltration (UF) membrane, and a microfiltration (MF) membrane, a nanofiltration (NF) membrane, a reverse osmosis (RO), or the like may be used.

  The support plate 32 is made of a hard vinyl chloride resin, is formed in a disc shape, and its outer edge portion 32A is formed wide across the entire circumference. The spacer 34 and the filtration membrane 36 are attached to a portion inside the outer edge portion 32A. The width w1 of the outer edge portion 32A is formed larger than the thickness t1 of the portion where the spacer 34 and the filtration membrane 36 are provided, and the outer edge portion 32A is formed so as to protrude from the membrane surfaces of the filtration membranes 36 and 36.

  The spacer 34 and the filtration membrane 36 are fixed to the support plate 32 by adhesion. The adhesive is applied to the outer edges of the spacer 34 and the filtration membrane 36 over the entire circumference, and the adhesive prevents the liquid from leaking from the outer edges of the spacer 34 and the filtration membrane 36.

  The rotating flat membrane disk 12 is attached to predetermined positions of the rotating shafts 22A to 22C via the liquid ring 38 shown in FIG. As shown in FIG. 3, holes 23A to 23C are formed in the rotating shafts 22A to 22C at the mounting positions of the spacers 34 of the rotating flat membrane disk 12, and the liquid that has passed through the spacers 34 passes through the holes 23A to 23C. And are configured to flow into the rotary shafts 22A to 22C. The liquid seal ring 38 prevents leakage to the outside.

  As shown in FIG. 2 or 3, the rotating flat membrane disk 12 configured as described above includes the rotating flat membrane disks 12, 12... Attached to the rotating shaft 22A, and the rotating flat membrane attached to the rotating shaft 22B. The disks 12, 12... Are alternately arranged in the axial direction, and the two rotary flat film disks 12, 12 are partially overlapped as viewed in the axial direction. Similarly, the rotating flat membrane disks 12, 12,... Attached to the rotating shaft 12B and the rotating flat membrane disks 12, 12,... Attached to the rotating shaft 12C are alternately arranged in the axial direction, and viewed in the axial direction. Both rotating flat membrane disks 12, 12 are arranged so as to partially overlap each other.

  Next, the operation of the rotating flat membrane module 10 configured as described above will be described.

  First, while the motors 20A to 20C in FIG. 1 are driven to rotate each rotating flat membrane disk 12, the pump 26 is driven to generate a suction force inside each rotating flat membrane disk 12. As a result, the raw water is sucked into the rotary flat membrane disk 12 through the filtration membrane 36 of the rotary flat membrane disk 12, and the raw water is filtered at that time. The treated water after filtration passes through the spacer 34 of the rotating flat membrane disk 12 and is sucked into the rotary shafts 22A to 22C, and is sent to the subsequent equipment through the treated water pipe 24. In such a filtration process, a membrane surface flow velocity is imparted to the membrane surface of the filtration membrane 36 by the rotation of the rotating flat membrane disk 12. Therefore, the filtration membrane 36 is less likely to be clogged, and the filtration process can be continuously performed for a long time.

  By the way, in the present embodiment, the rotating flat membrane disk 12 attached to the rotating shaft 22A and the rotating flat membrane disk 12 attached to the rotating shaft 22B are arranged so as to overlap each other in the axial direction, and the rotating shaft 22A, Since 22B rotates in the same direction, the rotating flat membrane disks 12 and 12 move in opposite directions in the overlapping portion, and a turbulent flow is generated between them. Similarly, the rotary flat membrane disk 12 attached to the rotary shaft 22B and the rotary flat membrane disc 12 attached to the rotary shaft 22C are arranged so as to overlap each other when viewed in the axial direction, and the rotary shafts 22B and 22C rotate in the same direction. Therefore, the rotating flat membrane disks 12 and 12 move in opposite directions in the overlapping portion, and turbulent flow is generated between them. Therefore, since raw water can be prevented from co-rotating with the filtration membrane 36, a sufficient membrane surface flow rate can be imparted to the membrane surface of the filtration membrane 36, and blockage of the filtration membrane 36 can be suppressed.

  In order to sufficiently obtain the effect of preventing the blockage due to such turbulent flow, it is preferable to arrange the rotating flat membrane disks 12 and 12 close to each other. However, if the rotating flat membrane disks 12 and 12 are arranged close to each other, the rotating flat membrane disks 12 and 12 may come into contact with each other when the support plate 32 of the rotating flat film disk 12 is deformed. For this reason, in the conventional device, it is necessary to increase the interval between the rotating flat membrane disks 12 and 12, and a sufficient blocking prevention effect due to turbulent flow cannot be obtained.

  Therefore, in the present embodiment, the outer edge portion 32A of the support plate 32 of the rotating flat membrane disk 12 is formed wide and protrudes outward from the filtration membrane 36. Therefore, even if the support plate 32 is deformed, Since the outer edge portions 32A and 32A of the support plates 32 and 32 are in contact with each other, the filtration membrane 36 is protected without contact. Therefore, it is possible to prevent the filtration membrane 36 from being damaged and broken.

  As described above, in this embodiment, the outer peripheral portions 32A and 32A of the support plates 32 and 32 are protruded from the membrane surface of the filtration membrane 36 to prevent the filtration membrane 36 from being damaged. The distance between each other can be reduced. Therefore, the effect of preventing clogging due to turbulent flow can be sufficiently obtained, and the apparatus can be miniaturized. Further, by forming the outer edge portion 32A of the support plate 32 over the entire circumference to form a flange shape, the strength of the support plate 32 can be increased, and deformation of the support plate 32 can be suppressed.

  Next, a second embodiment of the rotating flat membrane module according to the present invention will be described. FIG. 5 is a plan sectional view showing a part of the internal configuration of the rotating flat membrane module of the second embodiment, and FIG. 6 is a perspective view showing the rotating flat membrane disk. Note that the second embodiment is different from the first embodiment in the configuration of the rotating flat membrane disk 12 and is otherwise configured in the same manner as in the first embodiment.

  As shown in FIGS. 5 and 6, in the rotating flat membrane disk 50 of the second embodiment, the support plate 52 is formed in a flat disk shape (that is, a disk shape in which the outer edge portion does not protrude). A protective ring X is attached to the outer edge of the support plate 52.

  The protective ring X is configured by attaching the long member 54 shown in FIG. 7 to the outer edge portion of the rotating flat membrane disk 50 to form a ring shape. The elongate member 54 in FIG. 7 is made of a flexible material such as polyethylene resin, and the width w2 thereof is formed to be larger than the thickness t2 of the rotating flat membrane disk 50. The elongated member 54 is formed with two protruding portions 56, 56 projecting along the longitudinal direction, and a concave groove 58 is formed between the two protruding portions 56, 56. Has been. A width w3 of the groove 58 is formed to be substantially the same as the thickness t1 of the rotating flat membrane disk 50, and an outer edge portion of the rotating flat membrane disk 50 can be inserted between the grooves 58. The long member 54 is formed such that the length L in the longitudinal direction matches the outer peripheral length of the rotating flat membrane disk 50. Therefore, as shown in FIG. 8, the long member 54 is wound around the outer periphery of the rotating flat membrane disk 50 while the outer edge portion of the rotating flat membrane disk 50 is fitted in the groove 58 of the long member 54. When the long member 54 goes around the outer edge portion of the rotating flat membrane disk 50, the end surfaces 60, 60 of the long member 54 come into contact with each other. As a result, the protective ring X is attached to the outer edge portion of the rotating flat membrane disk 50. The long member 54 may be bonded to the rotating flat membrane disk 50 by applying an adhesive inside the groove 58 and the end surfaces 60 and 60 of the long member 54 may be bonded and fixed. Thereby, the leakage of the liquid from the outer edge portion of the rotating flat membrane disk 50 can be prevented by the adhesive. The attachment of the long member 54 may be mechanical coupling such as fitting or engagement. For example, an engagement groove may be formed at one end of the long member 54, and an engagement portion that engages with the engagement groove may be provided at the other end of the long member 54. In that case, it is preferable to provide a mechanism that can be locked in a state where the engaging portion is engaged with the engaging groove.

  As shown in FIG. 7, V-shaped notches 62, 62... Are formed at regular intervals in the longitudinal direction on the ridges 56, 56 of the long member 54. Therefore, the elongate member 54 can be flexibly bent toward the protruding portion 56 side (that is, the groove 58 side). Thereby, the elongate member 54 can be easily wound and mounted on the outer edge portion of the rotating flat membrane disk 50.

  Further, the elongate member 54 is formed with through holes 64, 64... Penetrating the outer peripheral surface and the inner peripheral surface. The through holes 64 are formed at regular intervals in the longitudinal direction, and are communicated with a portion other than the groove 58 on the inner peripheral surface of the elongated member 54. Therefore, when the elongated member 54 is mounted on the rotating flat membrane disk 50, the outer peripheral surface side and the inner peripheral surface side of the rotating flat membrane disk 50 are communicated with each other through the through hole 64. In addition, what is necessary is just to form the through-hole 64 as needed, and the embodiment without the through-hole 64 is also possible.

  According to the second embodiment configured as described above, the protective ring X wider than the rotating flat membrane disk 50 in the thickness direction is attached to the outer edge portion of the rotating flat membrane disk 50. Therefore, even if the support plate 52 of the rotating flat membrane disk 50 is deformed, the protective rings X come into contact with each other, so that the filtration membrane 36 is protected by the protective ring X. Therefore, it is possible to prevent the filtration membrane 36 from being damaged and broken.

  Thus, in this embodiment, since the protective ring X is attached to the rotating flat membrane disk 50 to prevent the filtration membrane 36 from being damaged, the interval between the rotating flat membrane disks 50 and 50 can be reduced. Therefore, the effect of preventing clogging due to turbulent flow can be sufficiently obtained, and the apparatus can be miniaturized. Further, since the support plate 52 of the rotating flat membrane disk 50 can be mass-produced and reduced in cost by being punched out with a die with a ring, the production cost can be reduced. That is, in the conventional apparatus, in order to prevent the support plate 52 from being deformed, it has been necessary to use FRP (fiber reinforced plastic) or the like, which is difficult to mass-produce. Since the filtration membrane 36 can be prevented from being damaged, a hard vinyl chloride resin or the like can be used, and the cost can be reduced by mass production.

  Further, in the present embodiment, since the slippery polyethylene resin is used as the protective ring X, even when the protective rings X come into contact with each other and slide, the rotation of the rotating flat membrane disk 50 is greatly hindered. There is no. The support plate 52 may be made of polyethylene resin, water resistant rubber or the like.

  Furthermore, in the present embodiment, since the through-hole 64 is formed in the protective ring X, the raw water is easily introduced from the outside to the inside of the rotating flat membrane disk 50. Accordingly, the amount of liquid that passes through the filtration membrane 36 of the rotating flat membrane disk 50 increases, and the filtration efficiency can be improved.

  In the above-described embodiment, an impact detection sensor may be attached to the protection ring X to detect contact between the protection rings X.

  FIG. 9 shows a guard ring X having another shape. In the protective ring X shown in the figure, a through hole 70 penetrating the outer peripheral surface side and the inner peripheral surface side is formed in a rectangular shape, and a scraping portion 72 is formed to protrude outward at the position of the through hole 70. ing. The through hole 70 and the scraping portion 72 are simultaneously formed by cutting the protective ring X into a “U” shape. Further, the scraping portion 72 is formed so that the upstream side opens outward with respect to the rotation direction of the rotating flat membrane disk 50. In addition, it is preferable that the scraping part 70 forms the front-end | tip of a rotation direction at an acute angle, and can reduce resistance at the time of this.

  When the rotating flat membrane disk 50 equipped with such a protection ring X is rotated, the raw water is scraped to the through hole 70 by the scraping portion 72 and guided to the inner peripheral surface side of the protection ring X. Accordingly, the amount of liquid that permeates the filtration membrane 36 of the rotating flat membrane disk 50 can be increased, and the filtration efficiency can be greatly improved.

  The shape of the protective ring X is not limited to the above-described embodiment, and any shape may be used as long as it is attached along the outer edge portion of the rotating flat membrane disk 50 to form a ring shape. For example, as shown in FIG. 10A, the protective ring X may be formed using a long member 80 having a substantially circular cross section and a groove 82 formed in the longitudinal direction. Further, as shown in FIG. 10B, the protective ring X may be formed by using a long member 84 having a substantially triangular cross section and a groove 86 formed in the longitudinal direction. When the protective ring X is formed using these long members 80 and 84, when the protective rings X come into contact with each other, the contact area is reduced, and the contact resistance can be reduced.

  In the second embodiment described above, the protective ring X is formed by winding the long member 54. However, the method of forming the protective ring X is not limited to this, and for example, using a mold. A resin such as vinyl chloride may be molded into a ring shape and attached to the edge of the support plate 52. Alternatively, those formed in a semi-ring shape may be combined at the edge of the support plate 52. Thereby, the protection ring X can be attached to the ready-made rotating flat membrane disk, and the cost can be reduced.

The perspective view which shows the rotation flat membrane module which concerns on this invention The perspective view which shows a part of internal structure of a rotation flat membrane module Plan sectional drawing which shows a part of internal structure of a rotation flat membrane module Perspective view showing the configuration of a rotating flat membrane disk Plan sectional drawing which shows a part of internal structure of the rotation flat membrane module of 2nd Embodiment The perspective view which shows the structure of the rotation flat film disk of 2nd Embodiment. The perspective view which shows the elongate member which comprises a protection ring The perspective view which shows the attachment condition of a elongate member The perspective view which shows a part of protection ring of another shape The perspective view which shows the elongate member of another shape

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Rotating flat membrane module, 12 ... Rotating flat membrane disk, 22A-22C ... Rotating shaft, 32 ... Support plate, 34 ... Spacer, 36 ... Filtration membrane, 50 ... Rotating flat membrane disc, 52 ... Support plate, 54 ... Long Scale member, 56 ... convex line part, 58 ... groove, 62 ... notch, 64 ... through hole, 70 ... through hole, 72 ... scraping part, X ... protective ring

Claims (6)

A plurality of rotating shafts arranged in parallel, and a plurality of rotating flat membrane disks that are respectively attached to the plurality of rotating shafts and are configured by covering both surfaces of a circular support plate with a filtration membrane. In the rotating flat membrane module arranged so that the rotating flat membrane disks mounted on the rotating shaft partially overlap each other in the direction of the rotating shaft,
The rotating flat membrane module, wherein an outer edge portion of the support plate is formed so as to protrude from a membrane surface of the filtration membrane. A plurality of rotating shafts arranged in parallel; and a plurality of rotating flat membrane disks each mounted on the plurality of rotating shafts and covered with a circular membrane with a filter membrane; and different rotating shafts In the rotating flat membrane module arranged so that the rotating flat membrane disks mounted on each other partially overlap in the direction of the rotation axis,
A rotating flat membrane module comprising a protective ring attached to an outer peripheral portion of the rotating flat membrane disc and having a thickness larger than that of the rotating flat membrane disc.   3. The rotating flat membrane module according to claim 2, wherein the protection ring is constituted by an elongated member in which a groove into which an outer peripheral portion of the rotating flat membrane disk is inserted is formed in a longitudinal direction.   The rotary flat membrane module according to claim 3, wherein notches are formed at predetermined intervals in the longitudinal direction on the surface of the elongated member on which the groove is formed.   The rotating flat membrane module according to any one of claims 2 to 4, wherein a through-hole communicating with the inner peripheral surface of the protective ring is formed on the outer peripheral surface of the protective ring.   6. The rotating flat membrane module according to claim 5, wherein a scraping portion that rakes the liquid to be filtered into the through-hole is projected on the outer peripheral surface of the protective ring.

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