JP2011104502A - Immersed flat membrane element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an immersed flat membrane element capable of preventing bubbles passing through a space between adjoining flat membrane elements from converging to the central part thereof to enhance the efficiency of cleaning its membrane face. <P>SOLUTION: The flat membrane elements 10 of an immersed flat-membrane filtration apparatus wherein a plurality of flat membrane elements 10 each comprising a pair of adjoining filtration membranes disposed to face each other are vertically immersed in water to be treated present in its treatment tank, and an aeration means is disposed below the plurality of flat membrane elements 10, with the flat membrane elements 10 each constituted of a base frame 12 equipped with a support plate 14 having a water collection groove 16 and with a water collection section 18 disposed on the side face of the support plate 14, and of a pair of filtration membranes 22 each disposed on either main-faces of the support plate 14 respectively, is characterized in that the vertical distances each connecting the upper end 14a and the lower end 14b of the support plate 14 are made to vary in the horizontal direction to provide a long-distance section B and a short-distance section A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an immersion flat membrane filtration device, and more particularly to an immersion flat membrane element used as a filtration membrane in the device.

  The submerged flat membrane filtration apparatus is used for activated sludge treatment such as coagulation sludge treatment for industrial drainage and sewage. In the submerged flat membrane filtration apparatus, as shown in FIG. 13, a plurality of flat membrane elements 1 arranged in parallel are arranged so as to be immersed in the treatment tank 2, and water to be treated is sucked from the inside of each flat membrane element 1. By doing so, filtered water is obtained.

  Aeration means 3 is arranged below flat membrane element 1 in such an arrangement. The air diffused by the air diffuser 3 is formed for the purpose of cleaning the membrane surface of the flat membrane element 1, stirring in the processing tank 2, supplying oxygen to the microorganisms in the processing tank 2, and the like. Among these purposes, the membrane surface cleaning is directly related to the filtration of the water to be treated. However, in the conventional submerged flat membrane filtration apparatus, when the solid matter such as activated sludge is present in the treatment tank 2 at a high concentration, the viscosity of the water to be treated increases. In addition, there is a problem that the uniformity of the thickness is lost and bubbles are unevenly distributed, so that effective membrane surface cleaning is not performed and the filtration efficiency of the water to be treated is lowered.

  Various techniques have been proposed for such a problem. For example, in Patent Document 1, in order to eliminate an air pool generated in the upper part of the flat membrane element, from the upper left and right of the flat membrane element, along with the treated water. By sucking air and preventing the occurrence of air accumulation, the cleaning efficiency is improved by aeration.

  Moreover, in patent document 2, the dispersion plate which disperse | distributes the air bubble diffused is arrange | positioned between a flat membrane element and a diffuser tube, and diameter reduction and dispersion | distribution of the bubble supplied to a flat membrane element are aimed at.

  Further, in Patent Document 3, the thickness of the lower end portion of the frame portion of the flat membrane elements arranged in parallel is narrowed from the membrane surface, and the interval is changed depending on the arrangement position, whereby the membrane is removed from the air bed formed in the lower portion of the flat membrane element. The air supplied to the surface is uniformly dispersed.

JP 2000-237551 A JP 2001-162141 A JP 2006-43631 A

  Even if various ideas as disclosed in the above patent document are made, the bubbles flowing between the adjacent flat membrane elements are concentrated in the center of the flat membrane elements, and the bubbles are coarsened to accelerate the rising speed. It has been confirmed that this phenomenon occurs. When such a phenomenon occurs, the flow of bubbles does not occur at the ends of the flat membrane element, that is, the left and right sides of the membrane surface, and both the membrane surface cleaning efficiency and the filtration efficiency of the water to be treated are reduced. It will be.

  Accordingly, the present invention provides an immersion flat membrane element that can suppress central concentration of bubbles passing between adjacent flat membrane elements and can improve the cleaning efficiency of the membrane surface and the filtration efficiency of water to be treated. With the goal.

  In order to achieve the above object, an immersion flat membrane element comprises a plurality of flat membrane elements vertically immersed in water to be treated in a treatment tank, with a plurality of flat membrane elements arranged adjacent to each other with their membrane surfaces facing each other. A flat membrane element of a submerged flat membrane filtration apparatus having a diffuser disposed below, a base frame having a support plate having a water collecting groove and a water collecting portion arranged on a side surface of the support plate, Provided with filter membranes arranged on both main surfaces of the support plate, the vertical distance connecting the upper end portion and the lower end portion of the support plate was changed in the horizontal direction, and a long distance portion and a short distance portion were provided. It is characterized by.

  Moreover, in the submerged flat membrane element having the above-described characteristics, at least one of the upper end portion and the lower end portion of the support plate may have a linear portion connecting the long distance portion and the short distance portion.

  In the submerged flat membrane element having the above-described features, at least one of the upper end portion and the lower end portion of the support plate may have a curved portion connecting the long distance portion and the short distance portion. good.

Further, in the submerged flat membrane element having the above-described characteristics, the long distance portion is provided at a horizontal central portion of the support plate, and the short distance portion is provided at both horizontal ends of the support plate. It is good to do so.
Furthermore, in the submerged flat membrane element having the above-described characteristics, a plurality of the long distance portions and the short distance portions may be provided for one support plate.

  According to the submerged flat membrane element having the above-described characteristics, the central concentration of bubbles passing between adjacent flat membrane elements is suppressed, the membrane surface cleaning efficiency is improved, and the treatment water filtration efficiency is improved. Can be achieved. In addition, irreversible membrane clogging (sludge sticking to the membrane surface) can be suppressed by effective cleaning of the membrane surface, so that the frequency of chemical cleaning can be reduced and the membrane life can be extended. You can also.

It is a partial exploded perspective view which shows the structure of the immersion flat membrane element which concerns on 1st Embodiment. It is a perspective view showing composition of a flat membrane unit which combined a plurality of immersion flat membrane elements concerning a 1st embodiment. It is a figure for demonstrating the velocity distribution of the flow of the to-be-processed water which arises in the conventional immersion flat membrane unit, and the bias | inclination of a bubble. It is a figure for demonstrating the velocity distribution of the flow of the to-be-processed water which arises in the immersion flat membrane unit which concerns on embodiment, and dispersion | distribution of a bubble. It is a figure which shows the 1st modification of the immersion flat membrane element which concerns on 1st Embodiment. It is a figure which shows the 2nd modification of the immersion flat membrane element which concerns on 1st Embodiment. It is a top view which shows the structure of the immersion flat membrane element which concerns on 2nd Embodiment. It is a figure which shows the 1st modification of the immersion flat membrane element which concerns on 2nd Embodiment. It is a top view which shows the structure of the immersion flat membrane element which concerns on 3rd Embodiment. It is a figure which shows the 1st modification of the immersion flat membrane element which concerns on 3rd Embodiment. It is a top view which shows the structure of the immersion flat membrane element which concerns on 4th Embodiment. It is a figure which shows the example of the immersion flat membrane element which provided the convex part also in the upper end part side of the support plate, and comprised the long distance part. It is a figure which shows the structure of the immersion flat membrane filtration apparatus using an immersion flat membrane element.

  Hereinafter, embodiments of the immersed flat membrane element of the present invention will be described in detail with reference to the drawings. First, with reference to FIG. 1, 1st Embodiment which concerns on the immersion flat membrane element (henceforth only the flat membrane element 10) of this invention is described.

  The flat membrane element 10 according to the present embodiment is configured based on a base frame 12 and a filter membrane 22 attached to the base frame 12. In addition, the base frame 12 of the flat membrane element 10 according to the present embodiment includes a support plate 14 and a water collecting portion 18.

  In the support plate 14 according to the present embodiment, the vertical distance connecting the upper end portion 14a and the lower end portion 14b of the support plate 14 is changed in the horizontal direction (on the arrangement form). That is, the upper end portion 14a and the lower end portion 14b of the support plate 14 are not formed in parallel. Specifically, a long distance portion B having a long vertical distance is disposed in the vicinity of the horizontal central portion of the support plate 14, and a short distance portion A having a vertical distance shorter than the long distance portion B at both ends. Is arranged.

  In the flat membrane element 10 according to the present embodiment, as shown in FIG. 1, the lower end portion 14 b of the support plate 14 is formed in a convex shape downward, thereby forming the long distance portion B and the short distance portion A. The outer shape of the lower end portion 14b of the support plate 14 is formed so as to connect the portion B and the short distance portion A with a straight line. For this reason, the lower end part 14b of the support plate 14 becomes a trapezoid shape convex downward.

  A plurality of water collecting grooves 16 are formed on the main surface (plate surface) of the support plate 14 having such an outer shape. The water collecting grooves 16 are formed on both main surfaces of the support plate 14, and one of the end portions is connected to a water collecting portion 18, which will be described in detail later, so that the main surface passes through a filter membrane 22, which will be described in detail later. It is possible to guide the water to be treated in contact with the water collecting section 18.

  The water collecting portion 18 is a water channel arranged on both side surfaces of the support plate 14. The water collecting portion 18 is provided with a suction port 20, and when negative pressure is applied to the suction port 20, the water to be treated sucked from the water collecting groove 16 formed in the support plate 14 is collected in the water collecting portion 18. It flows into the inside and is fed to the outside through the suction port 20. The water collecting portion 18 is formed to be thicker than the support plate 14, and is configured such that the support plate 14 is disposed at the central portion in the thickness direction of the water collecting portion 18. By adopting such a configuration, when the flat membrane elements 10 are arranged adjacent to each other, a gap can be formed between the support plates 14 of the adjacent flat membrane elements 10, and a flow path through which bubbles pass can be secured. Further, it is possible to prevent damage to the filter membrane 22 due to contact between the filter membranes 22 described later in detail. In addition, the filter membrane 22 is affixed on both main surfaces of the support plate 14, and bears the role which filters to-be-processed water.

  FIG. 2 shows a flat membrane unit 50 configured by arranging a plurality of flat membrane elements 10 according to this embodiment adjacent to each other. The flat membrane unit 50 is configured such that the membrane surfaces of the filtration membranes 22 in the plurality of flat membrane elements 10 are opposed to each other and the water collecting portions 18 are overlapped.

  In the flat membrane element 10 arranged in this way, the air passes between the filter membranes 22 of the adjacent flat membrane elements 10, so that the treated water located between the membrane surfaces of the adjacent flat membrane elements 10 is treated. As a result, an upward flow is generated by the action of the air lift.

  At this time, since the water collecting portions 18 are arranged at both ends of the filter membrane 22, the flow rate of the water to be treated flowing on the filter membrane is collected in the conventional flat membrane element as shown in FIG. Since the resistance in the central part of the membrane is less than that in the vicinity of the water part, the flow in the central part of the membrane is faster.

  When an upward flow having such a velocity distribution is generated between the filter membranes of adjacent flat membrane elements, a pressure difference based on the flow rate is generated. When such a pressure difference occurs between the filter membranes, bubbles tend to concentrate in a low pressure portion, that is, a central portion where the flow velocity is high. And the bubbles concentrated in the central part are coarsened by coalescence, and the rising speed is accelerated, resulting in a further deviation of the flow velocity, resulting in a decrease in the cleaning efficiency of the filter membrane, specifically, on the filter membrane end side. The cleaning efficiency is reduced (see FIG. 3B). Further, the air bubbles which are coarsened and concentrated in the center cause distortion of the flat membrane element, which may cause contact and breakage between adjacent flat membrane elements.

  In contrast, in the flat membrane element 10 according to the present embodiment having the above-described features, the length of the central portion of the support plate is made longer than both end portions where the water collecting portions 18 are arranged. The flow velocity distribution shown in FIG. 3A as described above also occurs between the membrane surfaces of the filter membranes 22 in the flat membrane elements 10 arranged adjacent to each other. The resistance received by the air increases, and the speed of the upward flow generated by the air lift is prevented from accelerating. As shown in FIG. 4 (A), in the flat membrane element 10 of the present embodiment, the facing region (BB cross section) in the long distance portion B of the support plate 14 is the facing region (A-) of the short distance portion A. The vertical distance is longer than (A cross section). For this reason, in the center part of the support plate 14 which is the long distance part B, acceleration of the upward flow caused by the air lift is unlikely to occur, and the concentrated enlargement of bubbles caused by the pressure difference can be avoided. For this reason, as shown in FIG. 4B, the bubbles can be dispersed.

  Thereby, it is possible to improve the cleaning effect of the filter membrane 22, that is, to prevent the unevenness of the cleaning rate of the filter membrane 22 and to improve the filtration efficiency of the water to be treated by the effective cleaning of the filter membrane 22. Moreover, the distortion of the flat membrane element 10 which comprises the support plate 14 by resin can be suppressed, and the damage by the contact of the filter membrane 22 etc. can also be prevented. Furthermore, since the cleaning effect can be improved, irreversible membrane blockage of the filter membrane 22 can be suppressed. Thereby, the frequency of chemical cleaning can be reduced, and the life of the membrane can be extended.

  FIG. 5 is a first modification of the flat membrane element 10 according to the present embodiment. In the embodiment shown in FIG. 1, the long distance portion B and the short distance portion A are connected by a straight line, and the trapezoidal shape is formed on the lower end portion 14 b of the support plate 14. On the other hand, in the modification shown in FIG. 5, the lower end portion 14b of the support plate 14 is formed so as to connect the long distance portion B and the short distance portion A with a curve. For this reason, in the flat membrane element 10a which concerns on a present Example, the shape of the lower end part 14b of the support plate 14 will comprise circular arc shape.

  Even when the shape of the support plate 14 is such, the structure having the long distance portion B and the short distance portion A at the vertical distance connecting the upper end portion 14a and the lower end portion 14b of the support plate 14 is obtained. Therefore, the same effect as the flat membrane element 10 according to the above embodiment can be obtained.

  FIG. 6 is a second modification of the flat membrane element 10 according to the present embodiment. In the first modification shown in FIG. 5, the entire lower end portion 14b of the support plate 14 is formed in an arc shape. On the other hand, in the flat membrane element 10b according to this modified example, the side connecting the long distance part B and the short distance part A is curved while leaving the straight part in the area (long distance part area) constituting the long distance part B. It is constituted by.

  Even when the shape of the support plate 14 is such, the structure having the long distance portion B and the short distance portion A at the vertical distance connecting the upper end portion 14a and the lower end portion 14b of the support plate 14 is obtained. Therefore, the same effect as the flat membrane element 10 according to the above embodiment can be obtained.

  Next, 2nd Embodiment which concerns on the immersion flat membrane element of this invention is described with reference to FIG. The flat membrane element 110 according to the present embodiment has the same configuration as that of the flat membrane element 10 according to the first embodiment described above. Therefore, portions having the same function are denoted by the same reference numerals in the drawings, and detailed description thereof is omitted.

Compared with the flat membrane element 10 according to the first embodiment described above, the flat membrane element 110 according to the present embodiment expands the formation region (short distance portion region) of the short distance portion A in the support plate 14 and increases the long distance portion. It is characterized in that the formation region (long distance portion region) of B is narrowed. According to the flat membrane element 110 having such morphological characteristics, the area of the short-distance portion A located on both ends (left and right sides) of the filter membrane 22 is widened, so that the acceleration of the upward flow generated in the portion is increased. Can be improved. For this reason, even if it is the to-be-processed water with high viscosity which promotes the central concentration of a bubble, it becomes possible to suppress the central concentration of a bubble effectively.
In addition, about another structure, an effect | action, and an effect, it is the same as that of the flat membrane element 10 which concerns on 1st Embodiment mentioned above.

FIG. 8 is a modification of the flat membrane element 110 according to the present embodiment. In the present modification, similarly to the first modification in the first embodiment described above, the long distance portion B and the short distance portion A are connected by a curve, and the shape of the lower end portion 14b of the support plate 14 is an arc shape. . In addition, in this modification, since the area | region of the short distance part A is ensured widely, a linear part will be provided in the both ends side of the circular arc-shaped lower end part 14b.
Even when the shape of the support plate 14 is such, the same effect as the flat membrane element 110 according to the second embodiment can be obtained.

  Next, 3rd Embodiment which concerns on the immersion flat membrane element of this invention is described with reference to FIG. The flat membrane element 210 according to this embodiment is almost the same as the flat membrane elements 10 and 110 according to the first and second embodiments described above. Therefore, portions having the same function are denoted by the same reference numerals in the drawings, and detailed description thereof is omitted.

  The flat membrane element 210 according to the present embodiment defines the lower shape of the support plate 14 along a straight line extending toward the short distance portion A located at both ends with the long distance portion B formed on the support plate 14 as one point. ing. For this reason, the shape of the lower end part 14b of the support plate 14 in the flat membrane element 210 which concerns on this embodiment becomes a triangle convex downward. In the flat membrane element 210 provided with the support plate 14 having such an end shape, it is possible to disperse the bubbles even if the water to be treated has a higher viscosity.

  FIG. 10 is a modification of the flat membrane element 210 according to the present embodiment. In this modified example, the long distance portion B and the short distance portion A are connected by a curve, similarly to the first modified example in the first embodiment described above, but in the flat membrane element 210a according to the modified example, Since the sides are formed so that the arc portion faces upward, the long distance portion B, which is one point, has a shape that projects at an acute angle. Even when the shape of the support plate 14 is as described above, the same effect as that of the flat membrane element 210 according to the third embodiment can be obtained.

  Next, a fourth embodiment according to the immersed flat membrane element of the present invention will be described with reference to FIG. The flat membrane element 310 according to the present embodiment is almost the same as the flat membrane elements 10, 110, and 210 according to the first, second, and third embodiments described above. Therefore, portions having the same function are denoted by the same reference numerals in the drawings, and detailed description thereof is omitted.

As shown in FIG. 11, the flat membrane element 310 according to the present embodiment has a plurality of (two places in FIG. 11) long distance portions B and a plurality (three places in FIG. 11) with respect to one support plate 14. The short distance portion A is provided.
Even if it is a case where it is set as such a form, dispersion | distribution of the rising bubble can be aimed at similarly to the flat membrane element which concerns on each embodiment mentioned above.

  In the above embodiments, only the shape of the lower end portion 14b of the support plate 14 is changed, and a convex portion is formed on the lower end portion 14b of the support plate 14. However, the long distance portion B may be formed by using the upper end portion 14a of the support plate 14. For example, when the upper end portion 14a of the flat membrane element 10 according to the first embodiment is deformed, the form shown in FIG. 12 is obtained, and the upper end portion 14a has a convex trapezoid in addition to the lower end portion 14b of the support plate 14. It becomes a form. According to the flat membrane element 10c provided with the support plate 14 of such a form, the length of the long distance part B used as resistance can be made longer. Therefore, the inhibitory effect of bubbles concentrating to the center and enlarging can be improved.

10 ......... Flat membrane element, 12 ......... Base frame, 14 ......... Support plate, 14a ......... Upper end, 14b ......... Lower end, 16 ......... Water collecting groove, 18 ......... Water collecting Part, 20 ......... suction port, 22 ...... filter membrane, 50 ...... flat membrane unit.

Claims (5)

Submerged flat membrane filtration in which a plurality of flat membrane elements arranged adjacent to each other with the membrane surface facing each other are vertically immersed in the water to be treated in the treatment tank, and a diffuser is disposed below the plurality of flat membrane elements. A flat membrane element of the device,
A base frame having a support plate having a water collecting groove and a water collecting portion disposed on a side surface of the support plate;
Comprising a filter membrane disposed on both main surfaces of the support plate;
An immersion flat membrane element characterized in that a vertical distance connecting the upper end portion and the lower end portion of the support plate is changed in the horizontal direction to provide a long distance portion and a short distance portion.   2. The immersed flat membrane element according to claim 1, wherein at least one of an upper end portion and a lower end portion of the support plate has a straight portion connecting the long distance portion and the short distance portion.   2. The immersed flat membrane element according to claim 1, wherein at least one of an upper end portion and a lower end portion of the support plate has a curved portion connecting the long distance portion and the short distance portion. The long distance portion is provided in a horizontal central portion of the support plate,
4. The submerged flat membrane element according to claim 1, wherein the short distance portion is provided at both ends in the horizontal direction of the support plate. 5.   4. The submerged flat membrane element according to claim 1, wherein a plurality of the long distance portions and the short distance portions are provided with respect to one of the support plates. 5.

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