JP2015016446A - Immersed membrane unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an immersed membrane unit, in which the attachment of a branch pipe of an air diffusion pipe can be facilitated.SOLUTION: The immersed membrane unit, according to one aspect, is characterized in that the immersed membrane unit is immersed in the liquid to be treated to filter the liquid to be treated. The immersed membrane unit includes: a membrane element; and the air diffusion pipe arranged below the membrane element. The air diffusion pipe includes; the branch pipe for diffusing air toward the membrane element; and a main pipe for supplying air to the branch pipe. The one end side of the branch pipe is connected to the undersurface of the main pipe.

Description

  The present invention relates to an immersion membrane unit.

  There is known an immersion membrane unit that is immersed in a liquid to be processed and filters the liquid to be processed. For example, a sludge treatment device disclosed in Patent Document 1 includes a membrane separation device having a plurality of membrane modules, and an air diffusion device having an air diffusion tube provided below the membrane separation device. As a result, the membrane surface of the membrane module is washed to remove the residue (residue) attached to the membrane module.

JP 2000-107771 A

  In an example of the air diffuser of the sludge treatment apparatus described in Patent Document 1, a U-shaped branch pipe is connected to a pair of main pipes. When this branch pipe is attached to a pair of main pipes, it is necessary to simultaneously perform an operation of attaching one end of the branch pipe to one main pipe and an operation of attaching the other end of the branch pipe to the other main pipe. For this reason, it is difficult for an operator to perform the branch pipe installation work alone. In particular, when the branch pipe is long, it is difficult to attach the branch pipe.

  Then, an object of this invention is to provide the immersion membrane unit which makes it easy to attach the branch pipe of a diffuser tube.

  An immersion membrane unit according to one aspect of the present invention is an immersion membrane unit that is immersed in a treatment liquid and filters the treatment liquid. The submerged membrane unit includes a membrane element and an air diffuser provided below the membrane element. The air diffuser includes a branch pipe that diffuses into the membrane element, and a main pipe that supplies gas to the branch pipe. The branch pipe is connected to the lower surface of the main pipe at one end side of the branch pipe.

  According to such a submerged membrane unit, the main pipe and the branch pipe are provided below the membrane element. For this reason, the handling of the branch pipe can be reduced, and the length of the branch pipe can be reduced. The branch pipe is connected to the lower surface of the main pipe on one end side of the branch pipe. For this reason, the attachment work of a branch pipe is made only by connecting the one end side of a branch pipe to the lower surface of a main pipe. As a result, the workability of attaching the branch pipe of the diffuser pipe is improved.

  In the immersion membrane unit according to another aspect of the present invention, the branch pipe includes a first protrusion that protrudes upward on one end side of the branch pipe, and the main pipe includes a first opening provided on the lower surface of the main pipe. The first protrusion may be connected to the first opening. In this case, the branch pipe is attached only by connecting the first projecting portion of the branch pipe to the first opening of the main pipe. As a result, the workability of attaching the branch pipe of the diffuser pipe is improved.

  In the submerged membrane unit according to still another aspect of the present invention, the branch pipe includes a second opening provided on the upper surface on one end side of the branch pipe, and the main pipe includes a second protrusion that protrudes below the main pipe. The second protrusion may be connected to the second opening. In this case, the branch pipe is attached only by connecting the second projecting portion of the main pipe to the second opening of the branch pipe. As a result, the workability of attaching the branch pipe of the diffuser pipe is improved.

  In the immersion film unit according to still another aspect of the present invention, the first protrusion may be detachably connected to the first opening. In the immersion membrane unit according to still another aspect of the present invention, the second protrusion may be detachably connected to the second opening.

  In the immersion membrane unit according to still another aspect of the present invention, the branch pipe may be arranged perpendicular to the main pipe in plan view.

  In the immersion membrane unit according to still another aspect of the present invention, the branch pipe may include a cap detachably provided at the other end of the branch pipe. In this case, by removing the cap, the inside of the branch pipe can be easily cleaned using a brush or the like. For this reason, the maintainability of the branch pipe is improved.

  The immersion membrane unit according to still another aspect of the present invention may further include a fixing portion that fixes the other end of the branch pipe. In this case, by fixing the other end of the branch pipe, the branch pipe can be supported at both ends, and fluctuations in the position of the branch pipe can be suppressed.

  In the immersion membrane unit according to still another aspect of the present invention, one end side of a plurality of branch pipes arranged in the extending direction of the main pipe is connected to the lower surface of the main pipe, and the fixing portion is connected to the main pipe. It is good also as being comprised by the comb-shaped member which is arrange | positioned so that it may become parallel and has a recessed part which fixes a branch pipe.

  In the submerged membrane unit according to still another aspect of the present invention, the branch pipe may include aeration holes provided on the lower surface of the branch pipe. In this case, by providing the diffuser holes on the lower surface of the branch pipe, the inflow of the liquid to be processed from the diffuser holes can be suppressed.

  The submerged membrane unit according to another aspect of the present invention further includes a frame body that supports the membrane element and the diffuser tube, and the frame body has a column portion extending in the vertical direction, and the column portion is supplied to the main tube. It is good also as an air supply pipe which lets the gas to pass pass through.

  The immersion membrane unit according to still another aspect of the present invention further includes a shielding plate provided so as to surround four sides of the immersion membrane unit, and the distance between the lower end of the shielding plate and the installation surface of the immersion membrane unit is 100 to It may be 400 mm. The immersion membrane unit according to still another aspect of the present invention further includes a shielding plate provided so as to surround four sides of the immersion membrane unit, and the branch pipe is provided below the membrane element and shields the lower surface of the branch pipe. The vertical distance from the lower end of the plate may be 50 to 200 mm. In the immersion membrane unit according to still another aspect of the present invention, the branch pipe is provided below the membrane element, and the vertical distance between the lower surface of the branch pipe and the lower end of the membrane element is 150 to 350 mm, It is good.

  An immersion membrane unit according to still another aspect of the present invention includes another membrane element adjacent to the membrane element, and another diffusion tube provided at a position facing the diffusion tube, and the other diffusion tube includes: Another branch pipe that diffuses into other membrane elements, and another main pipe that supplies gas to the other branch pipe, and the other branch pipe is arranged at one end side of the other branch pipe. It may be connected to the lower surface. In this case, the size of the unit can be increased without impairing the ease of attaching and detaching the diffuser branch pipe.

  ADVANTAGE OF THE INVENTION According to this invention, the attachment workability | operativity of the branch pipe of an air diffuser can be improved.

It is a front view of the immersion membrane unit which concerns on one Embodiment of this invention. It is a front view of a hollow fiber membrane element. It is a perspective view which shows the relationship between a lower rail part and a hollow fiber membrane element. (A) is sectional drawing which shows an example of the connection structure of a main pipe and a branch pipe, (b) is sectional drawing which shows the other example of the connection structure of a main pipe and a branch pipe. It is a disassembled side view which shows the fixing | fixed part which fixes the front-end | tip of a branch pipe. It is VI-VI sectional drawing of FIG.

  Hereinafter, with reference to drawings, a suitable embodiment of an immersion membrane unit concerning the present invention is described in detail. In the following description, directions such as up and down refer to directions such as up and down in the submerged membrane unit in a state of being immersed in the liquid to be treated and installed on the horizontal installation surface A (FIG. 1). Further, as shown in each figure, there is a case where an XYZ orthogonal coordinate system is defined in which the Z axis is taken in the vertical direction and the X axis and the Y axis are taken on the horizontal plane, and X, Y, and Z are used for the description of the positional relationship of each part. Moreover, the same code | symbol shall be attached | subjected to the same or an equivalent part in all the figures.

  FIG. 1 is a front view of an immersion membrane unit according to the embodiment. As shown in FIG. 1, the immersion membrane unit 1 according to this embodiment is an immersion membrane that is immersed in the treatment liquid and filters the treatment liquid. The pair of hollow fiber membrane elements 2A and 2B and the frame 3 A liquid collection header pipe 4, a liquid collection branch pipe 5, a suction device 6, and an air diffusion pipe 40. Since the hollow fiber membrane element 2A and the hollow fiber membrane element 2B have basically the same configuration, the hollow fiber membrane element 2A and the hollow fiber membrane element 2B are combined together unless otherwise specifically described. This will be described as element 2.

  FIG. 2 is a front view of the hollow fiber membrane element. As shown in FIG. 2, the hollow fiber membrane element 2 has a flat plate shape extending along a plane parallel to the YZ plane. The hollow fiber membrane element 2 includes a hollow fiber membrane group 22 in which a number of hollow fiber membranes 21 extending in the Z direction are arranged in parallel to form a flat membrane shape (or a flat plate shape), and an upper end of the hollow fiber membrane group 22 And connected to both ends of the upper liquid collecting pipe 23 and the lower liquid collecting pipe 24 which are connected to the lower ends and extend linearly in the Y direction, and are connected to both ends of the upper liquid collecting pipe 23 and the lower liquid collecting pipe 24 and straight in the Z direction. A pair of support tubes 25 extending in a shape.

  The hollow fiber membrane 21 filters the liquid to be treated by immersing the immersion membrane unit 1 in the liquid to be treated, and allows the filtrate to pass through the hollow interior. The arrangement of the hollow fiber membranes 21 in the hollow fiber membrane group 22 is not particularly limited as long as it is formed in a film shape. For example, when the arrangement of the hollow fiber membranes 21 in the hollow fiber membrane group 22 is n rows and m columns, n can be 1 to several tens, and m can be several tens to several thousand.

  The upper liquid collection pipe 23 and the lower liquid collection pipe 24 communicate with all the hollow fiber membranes 21 and collect the filtrate filtered through each hollow fiber membrane 21. For this reason, the inside of the upper liquid collection pipe 23 and the lower liquid collection pipe 24 communicates with the hollow inside of each hollow fiber membrane 21, and the extending direction of the upper liquid collection pipe 23 and the lower liquid collection pipe 24 ( A space portion (not shown) extending along the direction in which the hollow fiber membrane 21 extends is formed.

  The pair of support pipes 25 support the upper liquid collection pipe 23 and the lower liquid collection pipe 24 in parallel at a predetermined interval, and move the filtrate between the upper liquid collection pipe 23 and the lower liquid collection pipe 24. Is possible. For this reason, inside the pair of support pipes 25 are communicated with the upper liquid collection pipe 23 and the lower liquid collection pipe 24, and extend along the extending direction of the support pipe 25 (the extending direction of the hollow fiber membrane 21). An extending space (not shown) is formed. In addition, a nozzle 26 is formed on the upper surface of the upper liquid collection pipe 23 to be connected to the liquid collection branch pipe 5.

  As shown in FIG. 1, the frame 3 supports a pair of hollow fiber membrane elements 2 A and 2 B adjacent in the Y direction, and the pair of hollow fiber membrane elements 2 A and 2 B along the upper liquid collection pipe 23. They are arranged in a straight line. The frame 3 includes a lower rail portion 31 on which the lower ends of the pair of hollow fiber membrane elements 2A and 2B are placed to regulate the positions of the pair of hollow fiber membrane elements 2A and 2B, and the pair of hollow fiber membrane elements. And an upper rail portion 32 that regulates the position of the pair of hollow fiber membrane elements 2A and 2B with the upper end portions of 2A and 2B interposed therebetween. The frame body 3 is provided with a plurality of sets of lower rail portions 31 and upper rail portions 32 extending in the Y direction, arranged in a direction (X direction) perpendicular to the surface of the hollow fiber membrane element 2. With this configuration, the frame 3 can be arranged in parallel with any number of pairs of hollow fiber membrane elements 2A and 2B in the X direction. The frame 3 is a structure that is formed in a rectangular parallelepiped shape with pillars and beams and is capable of supporting the hollow fiber membrane elements 2A and 2B and the air diffuser 40. However, in FIG. Is omitted as appropriate.

  FIG. 3 is a perspective view showing the relationship between the lower rail portion 31 and the hollow fiber membrane elements 2A and 2B. In addition, in FIG. 3, the hollow fiber membrane element is simplified and shown. As shown in FIG. 3, the lower rail portion 31 extends linearly and is formed in a U shape with a cross section opened upward. For this reason, the hollow fiber membrane elements 2 </ b> A and 2 </ b> B can be moved left and right along the lower rail portion 31 by being placed on the lower rail portion 31.

  Further, a stopper 31a with which the lower liquid collection pipe 24 of the hollow fiber membrane element 2A and the hollow fiber membrane element 2B abuts is provided at the center of the lower rail portion 31. The stopper 31a prevents the one hollow fiber membrane element 2A, 2B from moving toward the other hollow fiber membrane element 2B, 2A, and the lower collecting pipe of the hollow fiber membrane element 2A and the hollow fiber membrane element 2B. When 24 contacts the stopper 31a, a gap is formed between the hollow fiber membrane element 2A and the hollow fiber membrane element 2B. For this reason, it is possible to adjust the space | interval of the hollow fiber membrane element 2A and the hollow fiber membrane element 2B by adjusting the width | variety of the stopper 31a.

  As shown in FIGS. 1 and 2, the liquid collection header pipe 4 is disposed above the hollow fiber membrane element 2 and connected to the suction device 6, and is connected to the upper liquid collection pipe via the liquid collection branch pipe 5. 23. For this reason, when a suction force is generated by the suction device 6, the filtrate filtered by the hollow fiber membrane 21 is collected through the hollow portion of the hollow fiber membrane 21 into the upper liquid collection pipe 23 and the lower liquid collection pipe 24. The The filtrate collected in the lower collecting tube 24 is collected in the upper collecting tube 23 through the pair of support tubes 25. The filtrate collected in the upper liquid collection pipe 23 is collected from the nozzle 26 through the liquid collection branch pipe 5 to the liquid collection header pipe 4 and then sucked into the suction device 6. The liquid collection branch pipe 5 is connected to the side surface of the liquid collection header pipe 4.

  Subsequently, the air diffuser 40 will be described in detail with reference to FIGS. 1 and 4 to 6.

  The air diffuser 40 is supported by the frame 3 and is disposed below the hollow fiber membrane element 2 and includes a main pipe 41 and a branch pipe 43 that form an air passage. In this air diffuser 40, two main pipes 41 extend in the X direction, and a plurality of branch pipes 43 extending in parallel below the hollow fiber membrane element 2 are arranged and attached to each main pipe 41 in the X direction. Yes. From one main pipe 41, a plurality of branch pipes 43 extend in the + Y direction in plan view, and from the other main pipe 41, a plurality of branch pipes 43 extend in the -Y direction in plan view. And the front-end | tip part of the branch pipe 43 has opposed in the center position of both the main pipes 41. FIG. A cap 43c (see FIG. 4) for sealing the branch pipe 43 is detachably attached to the distal end 43b of each branch pipe 43. In this case, by removing the cap 43c, the inside of the branch pipe 43 can be easily cleaned using a brush or the like, and the maintainability of the branch pipe 43 is improved. In addition, on the lower surface of each branch pipe 43, a large number of air diffusion holes 43a for air diffusion are formed.

  The air diffuser 40 is connected to an air supply device (not shown) for supplying gas via an air supply tube 45 (see FIG. 1) described later. As the air supply device, a blower, a compressor, or the like can be used. Gas is supplied from the above air supply device to the upper end of the air supply pipe 45, and is diffused from the air diffusion holes 43 a of the branch pipe 43 through the main pipe 41 and the branch pipe 43. It is possible to remove the residue attached to the hollow fiber membrane 21 by the air bubbles diffused from the diffuser holes 43a. Since the air diffusion holes 43a are provided on the lower surface of the branch pipe 43, the inflow of the liquid to be processed from the air diffusion holes 43a can be suppressed.

  Next, a connection portion between the main pipe 41 and the base end 43d side of the branch pipe 43 will be described. A base end 43 d of the branch pipe 43 is connected to the lower surface of the main pipe 41. The branch pipe 43 has an L-shape that extends vertically downward from the lower surface of the main pipe 41, is bent, and extends in the Y direction. The distal end 43b of the branch pipe 43 reaches the vicinity of the center position between the two main pipes 41.

  As shown in FIG. 4A, the branch pipe 43 includes a vertical pipe part (first protrusion) 43f that protrudes upward on the base end 43d side. Correspondingly, a lower surface opening (first opening) 41 a provided on the tube wall of the main tube 41 is formed on the lower surface of the main tube 41. And the vertical pipe part 43f is connected with respect to the lower surface opening part 41a by the attachment method (for example, fitting, screwing, etc.) which can be attached or detached.

  Instead of the above connection structure, a connection structure shown in FIG. 4B may be adopted. In the connection structure of FIG. 4B, the branch pipe 43 includes an upper surface opening (second opening) 43h provided on the upper surface on the base end 43d side. Corresponding to this, the main pipe 41 includes a vertical pipe part (second projecting part) 41b projecting downward. And the vertical pipe part 41b is connected with the upper surface opening part 43h by the attachment method (for example, fitting, screwing, etc.) which can be attached or detached.

  Next, the fixing portion of the distal end 43b of each branch pipe 43 will be described with reference to FIG. At the center position between the two main pipes 41, a branch pipe holding part (fixing part) 51 extending in the X direction is attached to the frame body 3, and the distal end 43 b of each branch pipe 43 is connected to the branch pipe holding part. Held in the part 51.

  As shown in FIG. 5, the branch pipe holding part 51 is a comb-shaped member including a plurality of concave parts 51 a arranged in the X direction. The recesses 51 a are open downward and are arranged corresponding to the arrangement pitch of the branch pipes 43. The tips 43b of the plurality of branch pipes 43 arranged in the X direction are fitted into the corresponding recesses 51a from below. It should be noted that the distal ends 43b of the two branch pipes 43 are fitted together in one recess 51a in a state where the distal end surfaces are close to each other. A long flat plate 53 having the same length as that of the branch pipe holding portion 51 is attached to the lower side of the branch pipe holding portion 51, and each tip 43 b of the branch pipe 43 has a recess 51 a and a long flat plate 53. It is sandwiched between and fixed.

  Next, with reference to FIGS. 1 and 6, the air supply pipe 45 that conveys the gas to be diffused to the air diffusion pipe 40 will be described. The air supply pipe 45 extends in the vertical direction from the upper end of the submerged membrane unit 1 to the air diffusion pipe 40. The above-described air supply device is connected to the upper end of the air supply pipe 45 and is connected to the end of the main pipe 41 of the air diffusion pipe 40. The gas supplied from the air supply device passes through the air supply pipe 45 and is conveyed to the air diffusion pipe 40. The air supply pipe 45 is piped along the support column part 3 a included in the frame body 3. The column 3a is a vertical structural member that is positioned at each of the four corners of the frame 3 in plan view.

  The support column 3 a extends from the upper end of the submerged membrane unit 1 to the lowest end. For example, when the immersion membrane unit 1 is installed on the installation surface A, the lower ends of the four support columns 3 a are grounded to the installation surface A. As shown in FIG. 6, a channel material is employed for the support portion 3a for the purpose of reducing the weight. The air supply tube 45 extends in the Z direction in the inner groove portion having a U-shaped cross section of the single column portion 3a. With this arrangement, an installation space for the air supply pipe 45 can be saved. As shown in FIG. 1, a total of two air supply pipes 45 respectively connected to the two main pipes 41 provided in the submerged membrane unit 1 are provided in a symmetric configuration.

  In addition, four shielding plates 47 are attached to the frame 3 so as to surround the four sides of the immersion film unit 1. Due to the presence of the shielding plate 47, the bubbles diffused in the diffuser tube 40 rise in the frame 3, and the liquid to be treated that flows upward as the bubbles rise efficiently contacts the hollow fiber membrane element 2. To do.

  Next, the positional relationship among the shielding plate 47, the hollow fiber membrane element 2, the branch pipe 43, and the installation surface A of the immersion membrane unit 1 will be described with reference to FIG. The installation surface A of the immersion membrane unit 1 is the lowermost end surface of the immersion membrane unit 1, and is defined here as a plane in contact with the lowermost ends of the four support columns 3a.

  The distance h1 between the lower end of the shielding plate 47 and the installation surface A is preferably 100 to 400 mm. For example, the distance h1 may be about 200 mm, and when the immersion membrane unit 1 is enlarged, the distance h1 may be 300 mm.

  In this case, when the distance h1 is shorter than 100 mm, the line speed when the liquid to be filtered passes under the shielding plate 47 and is drawn into the unit becomes too fast, and the liquid to be filtered in the vicinity of the branch pipe 43 It will cause the flow to be disturbed. On the other hand, when the distance h1 is longer than 400 mm, the linear velocity of the liquid to be filtered in the vicinity of the installation surface A is reduced, and problems such as sedimentation of turbid and wet components in the liquid to be filtered occur.

  The lower end of the shielding plate 47 may be positioned below the lower surface of the branch pipe 43. According to this configuration, the flow of the liquid to be filtered in the vicinity of the branch pipe 43 disposed inside the shielding plate 47 becomes a uniform upward flow, and the aeration amount from each of the air diffusion holes 43 a disposed in the branch pipe 43 is uniform. Can be realized. This effect is more preferable as the distance h2 in the vertical direction from the lower surface of the branch pipe 43 to the lower end of the shielding plate 47 (the height difference between the lower surface of the branch pipe 43 and the lower end of the shielding plate 47) is longer, but the distance h2 is longer. If it is too large, the unit 1 is unnecessarily enlarged, and therefore the distance h2 is preferably 50 to 200 mm. For example, the distance h2 may be 83 mm, and the distance h2 may be further increased when the immersion membrane unit 1 is enlarged. Further, when the distance h2 is smaller than 50 mm, the flow of the liquid to be filtered in the vicinity of the branch pipe 43 becomes a lateral flow that flows from the shielding plate 47 to the inside of the unit 1, and the amount of aeration from each air diffusion hole 43 a of the branch pipe 43. This causes the variation.

  The vertical distance h3 between the lower surface of the branch pipe 43 and the lower end of the hollow fiber membrane element 2 (the height difference between the lower surface of the branch pipe 43 and the lower end of the hollow fiber membrane element 2) is preferably 150 to 350 mm. For example, in the case of the unit 1 having 20 hollow fiber membrane elements 2, the distance h3 may be 220 mm. In the case of the large unit 1 having 60 hollow fiber membrane elements 2, the distance h3 may be 280 mm. Good. According to this configuration, it is possible to improve the homogenization of the air diffusion from the air diffusion holes 43a of the branch pipe 43 to the hollow fiber membrane element 2. When the distance h3 is less than 150 mm, the amount of air bubbles introduced into the gaps between the membrane elements is not uniform. On the other hand, when the distance h3 is longer than 350 mm, the unit 1 is unnecessarily enlarged.

  Then, the effect by the above-mentioned immersion film unit 1 is demonstrated.

  According to the immersion membrane unit 1, the main pipe 41 and the branch pipe 43 are provided below the hollow fiber membrane element 2. For this reason, the handling of the branch pipe 43 can be reduced, and the length of the branch pipe 43 can be reduced. The branch pipe 43 is connected to the lower surface of the main pipe 41 on the base end 43d side of the branch pipe. For this reason, the attachment work of the branch pipe 43 is done only by connecting the base end 43d side of the branch pipe 43 to the lower surface of the main pipe 41. As a result, the workability of attaching the branch pipe 43 of the diffuser pipe 40 is improved. Since the distal end 43b of the branch pipe 43 is fixed by the branch pipe holding part 51, the branch pipe 43 can be supported at both ends, and fluctuations in the position of the branch pipe 43 can be suppressed.

  Also, considering the work of connecting a U-shaped branch pipe to a pair of main pipes as in the above-described air diffuser of Patent Document 1, the work of attaching one end of a branch pipe to one main pipe, It is necessary to simultaneously perform the work of attaching the end to the other main pipe. In particular, when the branch pipe becomes longer due to the enlargement of the membrane unit, the work of attaching the branch pipe is difficult. On the other hand, according to the submerged membrane unit 1, since a pair of opposed L-shaped branch pipes 43 may be attached to both main pipes 41 one by one, even when the distance between the main pipes 41 is long, It is possible to avoid extremely deteriorated workability. Therefore, according to the immersion membrane unit 1, the unit 1 can be increased in size without impairing the ease of attaching and detaching the branch pipe 43.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and may be modified without changing the gist described in each claim.

Next, examples of the present invention will be described, but the present invention is not limited to the following examples.

(Example 1) Ten hollow fiber membrane elements 2 having a width of 1,000 mm, a length of 2,200 mm, and a thickness of 50 mm are stacked in the X direction at positions 2A and 2B in FIG. A membrane unit equipped with was prepared. In the membrane unit, the air supply pipe 45 has an outer diameter of 60 mm and an inner diameter of 51 mm, the main pipe 41 has an outer diameter of 76 mm, an inner diameter of 67 mm, and the branch pipe 43 is a polyvinyl chloride pipe having an outer diameter of 32 mm and an inner diameter of 25 mm. used. The branch pipes were arranged at the same pitch so as to be located in the center between the elements in the X direction in FIG. 1, and 11 branch pipes were connected to each main pipe. The connection between the main pipe and the branch pipe adopts the format shown in FIG. Air diffuser holes 43a are provided on the lower surface of the branch pipe so as to have an equal pitch. The other end of the branch pipe was fixed with a comb-shaped member as shown in FIG. Further, a shielding plate 47 is provided on each side of the unit, and h1, h2, and h3 in FIG. 1 are 250 mm, 83 mm, and 220 mm, respectively. This membrane unit was placed in fresh water, and the air supply amount to the unit was changed from 60 to 720 Nm ³ / h to observe bubbles and water flow in the unit. Was confirmed. Moreover, the way of blowing air from the air diffuser holes 43a of the branch pipes was upward and uniform. This unit was placed in activated sludge and subjected to a continuous filtration test for 2 months. The filtration condition was stable, and clogging of the sludge into the branch pipe was hardly observed.

(Comparative Example 1) In the membrane unit of Example 1, when the same observation test was performed in clear water with h2 = 0 mm, in the vicinity of the branch pipe 43, the horizontal direction from the vicinity of the lower end of the shielding plate 47 toward the vicinity of the unit center The flow was remarkably observed, and a phenomenon was confirmed in which the bubble blowing state was unstable and unstable from the diffuser holes located near 43b which is the end of the branch pipe in the diffuser holes 43a.

  DESCRIPTION OF SYMBOLS 1 ... Submerged membrane unit, 2, 2a, 2b ... Hollow fiber membrane element, 3 ... Frame body, 3a ... Strut part, 40 ... Aeration pipe, 41 ... Main pipe, 41a ... Lower surface opening part (1st opening part), 41b ... Vertical pipe part (second projecting part), 43 ... branch pipe, 43a ... diffuser hole, 43b ... tip (other end of branch pipe), 43c ... cap, 43d ... base end (one end of branch pipe), 43f ... vertical pipe Part (first projecting part), 43h ... upper surface opening part (second opening part), 45 ... air supply pipe, 47 ... shielding plate, 51 ... branch pipe holding part (fixing part), 51a ... concave part.

Claims (15)

An immersion membrane unit that is immersed in a liquid to be processed and filters the liquid to be processed.
A membrane element;
An air diffuser provided below the membrane element;
With
The air diffuser includes a branch pipe that diffuses into the membrane element, and a main pipe that supplies gas to the branch pipe,
The submerged membrane unit is connected to the lower surface of the main pipe on one end side of the branch pipe. The branch pipe includes a first protrusion protruding upward on the one end side of the branch pipe,
The main pipe includes a first opening provided on a lower surface of the main pipe,
The immersion film unit according to claim 1, wherein the first protrusion is connected to the first opening. The branch pipe includes a second opening provided on an upper surface on the one end side of the branch pipe,
The main pipe includes a second protrusion that protrudes downward from the main pipe,
The immersion film unit according to claim 1, wherein the second protrusion is connected to the second opening.   The immersion film unit according to claim 2, wherein the first protrusion is detachably connected to the first opening.   The immersion film unit according to claim 3, wherein the second protrusion is detachably connected to the second opening.   The submerged membrane unit according to claim 1, wherein the branch pipe is disposed perpendicular to the main pipe in a plan view.   The said branch pipe is an immersion membrane unit as described in any one of Claims 1-6 provided with the cap provided in the other end of the said branch pipe so that attachment or detachment was possible.   The immersion membrane unit according to any one of claims 1 to 7, further comprising a fixing portion that fixes the other end of the branch pipe. The one end side of the plurality of branch pipes arranged in the extending direction of the main pipe is connected to the lower surface of the main pipe,
The fixing part is
Arranged parallel to the main pipe,
The submerged membrane unit according to claim 8, comprising a comb-shaped member having a recess for fixing the branch pipe.   The said branch pipe is a submerged membrane unit as described in any one of Claims 1-9 provided with the diffused hole provided in the lower surface of the said branch pipe. A frame that supports the membrane element and the air diffuser;
The frame body has a column portion extending in the vertical direction,
The submerged membrane unit according to any one of claims 1 to 10, wherein an air supply pipe that allows gas supplied to the main pipe to pass through is provided in the support column.   12. The apparatus according to claim 1, further comprising a shielding plate provided so as to surround four sides of the immersion membrane unit, wherein a distance between a lower end of the shielding plate and an installation surface of the immersion membrane unit is 100 to 400 mm. The immersion membrane unit according to claim 1. Further comprising a shielding plate provided so as to surround four sides of the immersion membrane unit,
The branch pipe is provided below the membrane element;
The submerged membrane unit according to any one of claims 1 to 11, wherein a distance in a vertical direction between a lower surface of the branch pipe and a lower end of the shielding plate is 50 to 200 mm. The branch pipe is provided below the membrane element;
The submerged membrane unit according to any one of claims 1 to 13, wherein a distance in a vertical direction between the lower surface of the branch pipe and the membrane element is 150 to 350 mm. Other membrane elements adjacent to the membrane element;
Another air diffuser provided at a position facing the air diffuser, and
The other air diffuser is
Other branch pipes that diffuse into the other membrane elements;
Another main pipe for supplying gas to the other branch pipe;
Further comprising
The said other branch pipe is an immersion membrane unit as described in any one of Claims 1-14 connected to the lower surface of the said other main pipe in the one end side of the said other branch pipe.

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