JP2009233571A - Element array fixing implement and membrane separation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress vibrations of a filter membrane element generated by receiving aeration when using a membrane separation apparatus for the purpose of solid/liquid separation of a suspended-solid-containing liquid such as active sludge. <P>SOLUTION: In the membrane separation apparatus with a plurality of flat membrane elements which are planar support plates having a sheet-like separative membrane disposed on its both surfaces or one surface and is arrayed in an element holding frame body, an element array fixing implement is installed right above the flat membrane elements so as to fix the array of the flat membrane elements, has a first rigid plate 1 horizontally disposed and fixed at the upper part of the element holding frame body 6, a second rigid plate 2 arranged below the first rigid plate, and a pressure imparting member 3 for pressurizing the second rigid plate downwards, and has a structure for pressurizing and fixing the upper end part of the flat membrane elements 5 by the second rigid plate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flat membrane type membrane separation apparatus used for solid-liquid separation of a solid-containing liquid such as an activated sludge liquid or a microorganism culture liquid.

  Membrane separation methods have become popular while expanding their application fields because they have features such as energy saving, space saving, labor saving and product quality improvement. Membrane separation methods include methods such as reverse osmosis, ultrafiltration, and microfiltration, and filtration membranes in the form of hollow fiber membranes, flat membranes, tubular membranes, etc. are used. As an application field, it has been conventionally used in seawater desalination, water purification, gas separation, blood purification, etc. Recently, membrane separation has been applied to wastewater treatment from the viewpoint of environmental conservation.

  When membrane separation technology is applied to wastewater treatment, treat the treated water by immersing the membrane filtration device in a biological treatment tank containing activated sludge and sucking the permeate side with a pump, or using a water level difference such as siphon. The method of obtaining is known. At this time, normally, in the biological treatment tank, since microorganisms require oxygen in order to oxidize organic substances in the wastewater, oxygen is supplied by aeration. By using this aeration and placing a filtration membrane element on the upper part of the aeration diffuser, membrane filtration (solid-liquid separation) can be performed while washing the membrane surface simultaneously with the purpose of supplying oxygen. Overall, very low cost operation is possible. In particular, when a flat membrane type filtration membrane element (hereinafter referred to as a flat membrane element) is used, the membrane surface is highly cleanable and it is easy to construct an efficient process.

  In the case of a membrane separation apparatus using a flat membrane element as described above, normally, using an element holding frame, a plurality of flat membrane elements are arranged in parallel with the membrane surface facing up and down at intervals. An air diffuser is installed below the membrane element. Since the gas-liquid mixed upward flow generated from this air diffuser passes through the gaps between the flat membrane elements, the substances adhering to the surfaces of the separation membranes installed on both sides of the flat membrane elements are separated from the membrane surface. However, membrane separation can be performed. In this way, the gas-liquid mixed upward flow generated from the diffuser plays an important role in maintaining the performance of the separation membrane. The element floats and vibrates. If such levitation and vibration occur continuously, the flat membrane element will be worn and damaged, making it difficult to stably maintain membrane separation.

In order to solve such a problem, a method of installing an element arrangement fixture on the upper part of a flat membrane element is known. For example, in the method of Patent Document 1, a pressing plate for pressing from above is used as an element arrangement fixture, and a comb-like convex portion made of an elastic material that is press-fitted into each gap of a flat membrane element is placed under the pressing plate. The comb-like convex portion is provided and fixed by press-fitting between the elements to suppress vibration.
Japanese Patent Laid-Open No. 10-137556

  In the method of Patent Document 1 as described above, since the vibration in the vertical direction (vertical direction) and the vibration in the horizontal direction (horizontal direction) of the flat membrane element are to be suppressed at the same time, the pressing force is dispersed and vibration is suppressed. In some cases, it could not be suppressed sufficiently. In addition, a plurality of flat membrane elements are fixed at the same time, and the fixing force is determined by the force for fixing the element arrangement fixture to the element holding frame (generally, fixing with bolts and nuts). Therefore, the flat membrane element at the end close to the element holding frame is sufficiently transmitted and the position of the flat membrane element at the center is sufficiently fixed, but the flat membrane element at the center is affected by the warp of the holding plate, etc. The pressing force is not transmitted sufficiently, and position fixing tends to be insufficient. In particular, when the number of arranged flat membrane elements is as large as several tens, the adverse effect becomes significant.

  In addition, if solid-liquid separation is continued while immersed in a liquid to be filtered such as activated sludge, a small amount of the liquid to be filtered is placed in the slight gap between the flat membrane element and the element array fixture or element holding frame. The liquid may enter and gradually solidify to accumulate dirt, and the vertical position of each flat membrane element may slightly shift. In such a case, the method of Patent Document 1 tends to cause a problem that the force for pressing the flat membrane element positioned slightly downward is weakened and vibrations cannot be sufficiently suppressed.

The present invention for solving this problem has the following configuration.
(1) In order to fix the arrangement of the flat membrane elements in a membrane separation apparatus in which a plurality of flat membrane elements having sheet-like separation membranes arranged on both sides or one side of a flat support plate are arranged in an element holding frame An element array fixture that is installed directly above a flat membrane element, and is disposed below the first rigid plate, a first rigid plate that is horizontally mounted and fixed on the upper part of the element holding frame. A second rigid plate and a pressure applying member for pressing the second rigid plate downward, and the upper end portion of the flat membrane element is pressed and fixed by the second rigid plate. An element array fixture.
(2) A rod-like rigid body that can be moved up and down is inserted into a through-hole provided in the first rigid plate, and the second rigid plate is pressed downward by moving the rod-like rigid body downward. The element array fixture according to (1), characterized in that:

(3) A spring-like body is disposed in a gap between the first rigid plate and the second rigid plate, and the second rigid plate is pressed downward by the spring-like body ( The element arrangement fixture according to 1).
(4) The elastic member is arrange | positioned in the position which contact | connects the upper end part of the said flat membrane element on the lower surface of the said 2nd rigid board, It is characterized by the above-mentioned in any one of (3) Element array fixture.
(5) The element arrangement fixture according to (4), wherein the elastic member has a shape having a protrusion that can be inserted into each gap between the flat membrane elements.

(6) A membrane separation apparatus in which a plurality of flat membrane elements having sheet-like separation membranes arranged on both surfaces or one surface of a flat plate-like support plate are accommodated in an element holding frame in an arrayed state, (1) to (5 A membrane separation apparatus, wherein the element arrangement fixture according to any one of the above is installed in contact with a flat membrane element.
(7) The lower elastic member is mounted at a lower end of the arranged flat membrane elements and at a position facing the arrangement position of the element arrangement fixing tool. Membrane separator.
(8) A membrane separation apparatus in which the element arrangement fixture according to (4) or (5) is installed, wherein the upper membrane is in contact with the elastic member at the upper end surface of the flat membrane element, and / or the flat membrane The unevenness | corrugation shape is formed in the part which contacts the said lower elastic member in the lower end surface of an element, The membrane separator as described in (6) or (7) characterized by the above-mentioned.

  In the present invention, since the force for fixing the arranged flat membrane elements can be concentrated in the vertical direction, the flat membrane elements can be sufficiently fixed without the pressing force being dispersed. In addition, since the pressing force against the flat membrane element can be adjusted near each flat membrane element, even when the number of flat membrane elements is large, the flat membrane element is pressed and fixed with sufficient force. In addition, vibrations caused by aeration energy can be sufficiently suppressed even when immersed in a liquid to be filtered such as activated sludge for a long period of time.

  The element arrangement fixing tool of the present invention is a membrane separation apparatus in which a plurality of flat membrane elements each having a sheet-like separation membrane disposed on both sides or one side of a flat support plate are arranged in an element holding frame. It is installed directly above the flat membrane element to fix the arrangement.

  Here, the shape of the flat support plate is not particularly limited as long as it is a flat plate shape. For example, the front and back surfaces of the support plate are thick convex portions with a concave portion provided on the inside. And A sheet-like separation membrane is arranged so as to cover the concave portion, and the flat membrane element is formed by fixing the separation membrane and the flat plate-like supporting plate at the peripheral convex portion. In the flat membrane element, a gap existing between the recess and the separation membrane functions as a flow path for the filtrate to move, and the filtrate passes through a filtrate outlet that communicates with the gap. It is taken out of the flat membrane element.

  The material of the plate-like support plate is preferably a material having a tensile strength of 15 MPa or more in D638 of the ASTM test method. For example, the versatility of a copolymer represented by acrylonitrile butadiene styrene resin (ABS) Examples include a single-polymer versatile resin such as resin, polyethylene, and polyvinyl chloride, a fiber reinforced resin that is a composite material, and metals.

  The separation membrane is not particularly limited as long as it is a porous membrane and has a solid-liquid separation function and a reverse osmosis function, and examples include a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, and a reverse osmosis membrane. However, particularly when activated sludge is subjected to solid-liquid separation, a microfiltration membrane or an ultrafiltration membrane having a pore diameter on the membrane surface in the range of about 0.01 to 20 μm is preferable. The material is not particularly limited, and polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinyl alcohol, cellulose acetate, polyacrylonitrile, chlorinated polyethylene, polyvinylidene fluoride, polyvinyl fluoride, and other materials are appropriately selected. Can be used. In particular, a material of polyolefin or fluorine resin having high physical and chemical durability can be particularly preferably used.

  A plurality of flat membrane elements as described above are arranged in the element holding frame. Here, the element holding frame has a plurality of flat membrane elements whose membrane surfaces are substantially parallel to the vertical direction so that a desired interval is provided between separation membranes arranged in adjacent flat membrane elements. The structure is not particularly limited as long as it has a function capable of being arranged in a direction. For example, the element holding frame may have a casing structure that is open at the top and bottom, and a structure that accommodates a plurality of flat membrane elements therein. Or it is good also as a structure where the several element was arranged in the frame by forming the holding | maintenance frame part by passing and fixing the side edge part of the arranged flat membrane element with a volt | bolt and a nut. The material of the element holding frame is not particularly limited as long as the material has strength and durability capable of stably holding a plurality of flat membrane elements simultaneously for a long period of time even in activated sludge. Examples thereof include metals such as stainless steel, resins such as ABS, and fiber reinforced composite resins in which reinforcing fibers such as carbon fibers are blended with these resins.

  In the above membrane separation apparatus, a diffuser is usually installed below the flat membrane element. The air diffuser is connected to an air supply device such as a blower, and when the gas-liquid mixed upward flow generated from the air diffuser flows between the separation membranes of adjacent flat membrane elements, the surface of the separation membrane is washed. By performing membrane filtration at the same time, clogging of the separation membrane can be suppressed. The air diffuser is not particularly limited, but a diffuser of a hollow pipe, a diffuser made of ceramic with a void, a rubber-like elastic body having a slit, or the like. There are things that have a gastric part. In the present invention, an air diffuser that generates microbubbles having a diameter of 2 mm or less in fresh water is particularly preferable. Thereby, it is possible to increase the oxygen supply efficiency and to suppress the vibration of the flat membrane element.

  The present invention provides an element arrangement fixing tool suitable for arranging and fixing the flat membrane elements in the membrane separation apparatus as described above, and is horizontally fixed on the upper part of the element holding frame. A first rigid plate, a second rigid plate disposed below the first rigid plate, and a pressure applying member for pressing the second rigid plate downward, and The upper end portion of the flat membrane element is pressed and fixed by the second rigid plate.

  The basic structure of one embodiment of the element array fixture in the present invention is shown in FIG. 1 (schematic cross-sectional view). The first rigid plate 1 is horizontally mounted on the upper part of the element holding frame body 6 and is fixed at a position 7. For the fixing, it is preferable to use fixing means such as bolts and nuts. A second rigid plate 2 is disposed immediately below the first rigid plate 1. Furthermore, a pressure applying member for pressing the second rigid plate 2 downward is disposed. In the case of FIG. 1, the rod-shaped rigid body 3 is arrange | positioned as the pressure provision member. As shown in FIG. 1, the rod-like rigid body 3 is attached by being inserted into one or a plurality of through holes provided in the first rigid plate 1. The rod-like rigid body 3 has a structure in which, for example, the rod-like rigid body 3 is a bolt, the inside of the through hole is a screw hole, and the bolt tip position moves up and down by turning the bolt. When the bolt tip moves downward, the second rigid plate 2 arranged in contact with the tip is pushed downward by the bolt tip, and the second rigid plate 2 is pressed downward.

  Further, in order to press the second rigid plate 2 downward, a structure in which a spring-like body is installed in a gap portion between the two rigid plates and the second rigid plate 2 is pressed by a pressing force by the spring-like body. It is good.

  A plurality of bolts and spring-like bodies arranged as pressure applying members for pressing the second rigid plate 2 downward are pressed with a force suitable for each of a plurality of arranged flat membrane elements. As described above, for example, 2 to 10 are preferably arranged at substantially equal intervals.

  By adopting the structure as described above, by pressing the second rigid plate 2 downward, even if the upper ends of the arranged flat membrane elements have a step in the vertical direction, the flat membrane The elements can be sufficiently pressed vertically downward, the arrangement can be sufficiently fixed, and the vibration of the flat membrane element can be suppressed.

  It is preferable that the first rigid plate 1 and the second rigid plate 2 are made of a material having a tensile strength of 15 MPa or more in D638 of the ASTM test method. Examples include general-purpose copolymer resins represented by acrylonitrile butadiene styrene resin (ABS), single-polymer general-purpose resins such as polyethylene and polyvinyl chloride, fiber reinforced resins that are composite materials, and metals. However, it is particularly preferable that the stainless steel has high rigidity and is widely used.

  Further, it is preferable that the elastic member 4 is disposed at a position in contact with the upper end portion of the flat membrane element 5 on the lower surface of the second rigid plate. The elastic member 4 can enhance the effect of suppressing the vibration of the flat membrane element 5 in the left-right direction. The elastic member 4 is not particularly limited as long as it is a material having elasticity, but ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR), butadiene rubber (BR), acrylonitrile-butadiene rubber ( NBR) can be preferably used.

  The elastic member 4 attached to the lower surface of the second rigid plate may have a flat plate shape as shown in FIG. 1, but as shown in FIG. 2, a convex portion that can be inserted into a gap between flat membrane elements. 8 is preferably a comb-teeth shape. At this time, the elastic member 4 and the convex part 8 should just be the elastic material comb-tooth shaped material integrated. It is preferable that the width of the tip portion of the convex portion 8 is made smaller than the flat membrane element gap width to make it easy to insert. Further, the width of the concave portion of the elastic comb-like material may be made smaller than the width of the flat membrane element 5, and the convex portion 8 may be press-fitted into the gap of the flat membrane element 5. In order to sufficiently press the upper end portion of the flat membrane element 5, it is more effective to suppress the vibration of the flat membrane element if the width of the concave portion is the same as the width of the flat membrane element 5 or about 1 to 2 mm. Preferred for enhancing.

  Further, as shown in FIG. 2, in addition to disposing the element array fixture directly above the flat membrane element 5, a lower elastic member 9 is disposed in contact with the lower end of the flat membrane element 5, and the flat membrane element 5 is Fixing so as to be sandwiched at corresponding positions is preferable in order to further absorb and suppress vibration of the flat membrane element. The lower elastic member 9 is not particularly limited as long as it is a material having elasticity, like the elastic member 4 of the above-described array fixture, but ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR) Butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR) and the like can be preferably used. The shape of the elastic member 9 may be a flat plate shape, but it may be a comb tooth shape with a tooth portion inserted between the elements at the lower end of the arranged flat membrane elements.

  Moreover, the part which contacts the elastic member 4 in the upper end surface of the flat membrane element 5 is made into the uneven | corrugated shape which has a convex part and a recessed part, for example, the shape with a streak-like unevenness, the shape with a checkered pattern unevenness It is preferable that Thereby, the convex part in the upper end surface of the flat membrane element 5 bites into a contact surface with the elastic member 4, and the elastic member 4 bites into the concave part in the upper end surface, thereby further suppressing horizontal vibration. Such a concavo-convex shape having a convex portion and a concave portion may be provided also in a portion in contact with the lower elastic member on the lower end surface of the flat membrane element 5. Thereby, the vibration in the horizontal direction can be further suppressed.

  In order to verify the effect of the element array fixture of the present invention, a membrane separation apparatus as shown in FIG. 3 was created. In this membrane separation apparatus, a frame having a stainless steel casing structure is used as the element holding frame 6, and a sheet-like polyvinylidene fluoride flat membrane (average pore diameter 0.08 μm) is attached to the frame 50. A sheet of flat membrane element 5 (made of ABS resin) was loaded. Here, lower elastic members 9 were installed at the left and right ends (two locations) below the flat membrane element 5 so as to be in contact with the lower end of the flat membrane element 5. As the lower elastic member 9, a flat rubber made of EPDM was used.

  In addition, a diffuser tube 11 for cleaning the membrane surface was installed immediately below the arranged flat membrane elements 5. The air diffuser 11 is provided with a rubber sheet material having fine slits made of EPDM rubber on the outer periphery of a cylindrical support member, and supplies air to the gap between the support member outer periphery and the fine slit rubber sheet material. Thus, bubbles with an average diameter of 2 mm are generated during clean water.

  Moreover, the element arrangement | sequence fixing tool 10 of the structure similar to FIG. 1 was installed in the right-and-left end (two places) on the arranged flat membrane element 5. FIG. Here, a flat plate made of stainless steel (SUS304) was used for the first rigid plate 1 and the second rigid plate 2. As the elastic member 4, a flat rubber made of EPDM was used. The first rigid plate 1 was provided with five through holes at equal intervals, and female screws were formed in the through holes. A bolt that matches the female screw was used as the pressure applying member 3, and the second rigid plate 2 was pushed vertically downward while tightening the bolt in order to press the flat membrane element 5.

  The membrane separation apparatus as described above was immersed in a tank containing activated sludge (sludge concentration (MLSS): 20 g / l), and aeration was continued for 6 months at a flow rate of 500 L / min. Thereafter, the membrane separation apparatus was taken out of the tank, and the conditions of the flat membrane element 5 and the element array fixture 10 were confirmed. In either case, no scraping or wear was observed, and the flat membrane element was sufficiently fixed. .

It is a schematic sectional drawing which shows one embodiment of the element arrangement | sequence fixing tool which concerns on this invention. It is a schematic sectional drawing which shows other one embodiment of the element arrangement | sequence fixing tool which concerns on this invention. It is a schematic perspective view of the membrane separator used in the Example.

Explanation of symbols

1: first rigid plate 2: second rigid plate 3: rod-like rigid body as a pressure applying member 4: elastic member 5: flat membrane element 6: element holding frame 7: fixed position 8: convex portion 9: lower elasticity Member 10: Element arrangement fixture 11: Diffuser

Claims (8)

  In a membrane separation apparatus in which a plurality of flat membrane elements having sheet-like separation membranes arranged on both sides or one side of a flat support plate are arranged in an element holding frame, a flat membrane element is used to fix the arrangement of the flat membrane elements. An element array fixture that is installed directly above the first rigid plate that is horizontally mounted and fixed on the upper portion of the element holding frame, and a second rigid plate that is disposed below the first rigid plate. And a pressure applying member for pressing the second rigid plate downward, and the upper end of the flat membrane element is pressed and fixed by the second rigid plate. Array fixture.   A rod-like rigid body that can move up and down is inserted into a through-hole provided in the first rigid plate, and the second rigid plate is pressed downward by moving the rod-like rigid body downward. The element array fixture according to claim 1.   The spring-like body is disposed in a gap between the first rigid plate and the second rigid plate, and the second rigid plate is pressed downward by the spring-like body. The element arrangement fixture as described.   The element arrangement fixture according to any one of claims 1 to 3, wherein an elastic member is disposed at a position on the lower surface of the second rigid plate in contact with the upper end portion of the flat membrane element.   The element array fixture according to claim 4, wherein the elastic member has a shape having a protrusion that can be inserted into each gap between the flat membrane elements.   A membrane separation apparatus in which a plurality of flat membrane elements having sheet-like separation membranes arranged on both sides or one side of a flat support plate are accommodated in an element holding frame in an arrayed state. A membrane separation apparatus, wherein the element arrangement fixture described above is placed in contact with a flat membrane element.   7. The membrane separation device according to claim 6, wherein a lower elastic member is mounted at a lower end of the arranged flat membrane elements and at a position opposite to an arrangement position of the element arrangement fixing tool. .   A membrane separation apparatus comprising the element array fixture according to claim 4 or 5, wherein the upper end surface of the flat membrane element is in contact with the elastic member and / or the lower end surface of the flat membrane element. The membrane separation apparatus according to claim 6 or 7, wherein a concave-convex shape is formed in a portion in contact with the lower elastic member.

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