JP2009195874A - Membrane separation activated sludge treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple improvement means to solve the problem that a membrane element for use in a membrane separation activated sludge treatment apparatus is damaged while undergoing the aeration in the operation, wherein a filtration film bonded to a filter plate is broken, resulting in a seal breakage, which is remarkably reduced particularly around the upper end portion of the membrane element. <P>SOLUTION: The membrane separation activated sludge treatment apparatus comprises a membrane separation device having a plurality of membrane elements disposed therein and an aeration device disposed thereunder, wherein the membrane element has the filter plate, whose surfaces are both covered by the filtration film bonded to the filter plate at the periphery of the film for sealing. The filtration film is turned down at one edge of the filter plate so as to cover both the surfaces of the plate. The membrane element is arranged in the membrane separation device so that the filtration film surface is set nearly vertically and the edge where the filtration film is turned down comes to the upper side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a membrane separation activated sludge treatment apparatus for treating wastewater or the like with activated sludge and performing membrane filtration treatment.

  As a membrane separation apparatus used in the membrane separation activated sludge method, for example, an immersion type membrane apparatus in which a plurality of membrane elements are arranged in parallel at appropriate intervals is known (Patent Document 1). As a membrane element installed inside such a submerged membrane device, a filtered water flow in which one end opens on the surface of the filter plate and the other end communicates with a filtered water suction pipe in a rectangular flat plate-shaped filter plate. The thing of the structure which formed the path | route and provided the organic filtration membrane so that the surface of the filter plate was covered is used. And the spacer which forms a predetermined gap | interval as needed is provided between the filter plate and the filtration membrane. When the treatment is performed, the membrane element is immersed in the water to be treated in the tank, and the negative pressure is applied through the filtered water suction pipe, thereby filtering the water to be treated with the filtration membrane.

  When manufacturing the membrane element as described above, there is a problem in membrane strength, such as tearing the filtration membrane at the boundary of the adhesive part when the organic filtration membrane is fixed alone. The filtration membrane arranged as is used. For the non-woven fabric as the support material, a thermoplastic resin that is hardly soluble in a solvent such as saturated polyester is mainly used because of easy manufacture. Then, a filtration membrane using a nonwoven fabric as a support material is placed on the surface of the resin filter plate, and the periphery of the filtration membrane is adhered using an adhesive, or is adhered and fixed by irradiating ultrasonic waves. It is manufactured by sealing (Patent Document 2).

  Here, in the submerged membrane separation device, particularly when solid-liquid separation is performed while aeration is performed from below for the purpose of immersing the membrane element in the activated sludge mixed treated water in the tank and cleaning the surface of the filtration membrane. There is a risk that the bonded portion of the filter membrane and the filter plate will be fatigued and destroyed by the energy of the gas-liquid mixed upward flow generated by aeration. In particular, since the load of water flow energy is large at the upper part of the membrane element, the risk of separation of the filtration membrane from the filter plate is the highest at this location, and the separation of the filtration membrane from the filter plate is concentrated at the upper part of the membrane element even in the forced test. Occur.

  For these reasons, it is desired to further increase the adhesive strength between the filter plate and the filtration membrane above the membrane element. As a method for that purpose, Patent Document 3 proposes an element using a frame, but since the frame is required, there is a problem that the cost and labor required for production increase, and a satisfactory technique. It wasn't.

Japanese Patent No. 3328149 Japanese Patent No. 3028900 JP 2003-190746 A

  The purpose of the present invention is to solve the problem that the membrane element used in the membrane separation activated sludge treatment device is subjected to aeration and the adhesion and fixation between the filter plate and the filtration membrane are broken and peeled off, and the seal is destroyed. In particular, a membrane separation activated sludge treatment apparatus that can maintain the sealing performance at the upper end of the membrane element or can greatly reduce the possibility of the seal breakage is provided with a simple improvement means. It is in. And it is providing the technique which extends the service life of the membrane element in a membrane separation activated sludge processing apparatus, and contributes to a reduction in operating cost.

  In order to achieve the above object, the present invention has the following configuration.

  In a membrane separation activated sludge treatment apparatus in which a membrane separation apparatus in which a plurality of membrane elements are arranged in a tank and an air diffuser is installed below the membrane separation apparatus, the membrane elements are arranged on the front and back of the filter plate. Filtration membranes are arranged on both sides and the periphery of the filtration membrane is tightly fixed to the filter plate and sealed, and the filtration membrane is folded on one side of the filter plate and arranged on both sides of the filter plate, In the membrane separator, the membrane element is arranged so that the filtration membrane surface is substantially the same as the vertical surface, and the folded side of the filtration membrane is vertically upward.

  At the upper end of the membrane element, the filtration membrane is connected over the front and back in a folded state, and therefore membrane peeling at the upper end of the membrane element can be prevented reliably and easily. As a result, the service life of the membrane element can be extended, the operating cost can be reduced, and the membrane replacement operation can be simplified.

  In FIG. 1, the apparatus structure of the membrane separation activated sludge processing apparatus of this invention is shown notionally.

  The membrane separation activated sludge treatment apparatus shown in FIG. 1 includes an activated sludge treatment tank (aeration tank) 1 for containing activated sludge and performing biological treatment, a stock solution supply pump 4 for supplying wastewater into the aeration tank 1, A membrane separation device 2 for solid-liquid separation of biologically treated water biologically treated with activated sludge, a suction pump 3 for sucking the filtrate side for solid-liquid separation with a membrane, and a sludge extraction pump 7 for extracting excess sludge , And. The membrane separation device 2 is immersed in the water to be treated in the aeration tank 1, and oxygen is supplied below the membrane separation device 2 to advance the aerobic treatment and to clean the filtration membrane surface. For this purpose, an air diffuser 5 connected to the blower 6 is provided. As a treatment tank other than the aeration tank 1 in which the membrane separation device 2 is accommodated, another biological treatment tank such as an anaerobic tank, an oxygen-free tank, an aerobic treatment tank, or the like may be provided independently.

  Here, the membrane element arranged inside the membrane separation device 2 is a membrane element formed by arranging filtration membranes on both front and back surfaces of a filter plate, and sealing the peripheral edge of the filtration membrane tightly fixed to the filter plate. The filtration membrane is folded on one side of the filter plate and arranged on both sides of the filter plate, and the filtration membrane surface is substantially the same as the vertical line in the membrane separation tank, and the folded side of the filtration membrane is The membrane element is arranged so as to be vertically upward.

  Hereinafter, the manufacturing method of the membrane element used in the present invention will be described with reference to FIGS. 2, 3, and 4. FIG. 2 is a plan view showing an example of a membrane element used in the present invention. FIG. 3 is a top view of the membrane element viewed from one side where the membrane is folded. FIG. 4 is a perspective view for explaining the folding of the membrane during the production of the membrane element.

  In these drawings, 10 is a rectangular flat filter plate, and 11 is a filtration membrane arranged so as to cover both the front and back surfaces of the filter plate. Between the filtration membrane 11 and the filter plate 10, you may provide the spacer for ensuring the flow path of water as needed. The filter plate 10 is made of a thermoplastic resin such as ABS resin, and is manufactured in a flat plate shape or a plate shape having a thicker structure than a central portion where both sides of the long side are covered with a film. A filtrate flow path is formed between the filter plate and the filtration membrane, and a filtrate suction pipe 13 is provided in communication with the filtrate flow path.

  The filtration membrane 11 uses a nonwoven fabric made of thermoplastic resin such as saturated polyester as a support material, and a separation membrane layer is integrally formed on the surface thereof, and is tightly fixed to the filter plate 10 at the peripheral edge portion 14 thereof. The filtration membrane 11 is not particularly limited as long as it is porous and has a membrane separation function, but particularly when solid-liquid separation of the activated sludge mixed treated water is performed, the pore diameter of the membrane surface is 0. It is preferably within a range of about 01 to 20 μm. 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, polyolefin resins and fluorine resins having high physical and chemical durability are preferable.

  The spacer is formed to be the same size as the filtration membrane or smaller than the filtration membrane. Thus, the spacer is not essential when a gap serving as a flow path for the filtered water is substantially secured.

  When the membrane element as described above is manufactured, the filter plate 10 and the filtration membrane 11 are, as shown in FIG. 2, the treated water side surface of the filtration membrane is the front side on one side above the filter plate. The entire periphery of the filtration membrane is tightly fixed to the filter plate and sealed. As means for tightly fixing, adhesion by an adhesive or welding by ultrasonic waves or local heating may be performed. Since the filtration membrane is connected at the folded-back side 12 of the filtration membrane, as shown in FIGS. The filtration membrane and the filter plate may be tightly fixed on the lower side.

  The membrane element is placed inside the membrane separation device and placed in the tank so that the folded side 12 of the filtration membrane is on the vertical upper side in order to improve the durability against membrane surface cleaning by aeration. In this way, even if aeration from below in the tank significantly affects the filtration membrane at the upper end of the membrane element, it is possible to greatly reduce the seal breakage at the upper end of the membrane element.

  When cleaning the membrane surface by aeration from below, it is better to place the short side of the filtration membrane on the upper lower side. The long side is in the vertical direction, and the filtration membrane may be folded at the short side on the upper side of the filter plate.

  The attachment position of the filtered water suction pipe 13 is not particularly limited, but the membrane is provided on the short side on the upper side where the filtration membrane 12 is folded back and close to the left and right ends not covered with the filtration membrane. It is preferable because the element can be easily replaced.

  The surface of the upper end of the filter plate that comes into contact with the inside of the folded side 12 of the filtration membrane preferably has a non-cornered shape such as a semi-cylindrical shape. If it makes such a shape, the area which a filtration membrane contacts will become large, and the danger of a filtration membrane failure | damage can be reduced because force is disperse | distributing.

  When sealing the filter membrane by folding the filter membrane on one side of the filter plate and placing the filter membrane on the front and back surfaces of the filter membrane in close contact with the filter plate, the two sides on the opposite side of the filter membrane ( It is preferable that the lower two sides) are pulled and sealed in a tensioned state so that the surface of the filtration membrane is flatly adhered and fixed to the filter plate.

  The membrane separation activated sludge treatment apparatus of the present invention can be used to purify sewage such as wastewater.

It is a figure which shows notionally the apparatus structure of the membrane separation activated sludge apparatus which concerns on this invention. It is a top view which shows an example of the membrane element in this invention. FIG. 3 is a top view of the membrane element of FIG. 2 viewed from one side where the membrane is folded. It is a perspective view for demonstrating the return | turnback of the film | membrane at the time of membrane element preparation.

Explanation of symbols

1: Aeration tank 2: Membrane separation device 3: Suction pump 4: Stock solution supply pump 5: Aeration device 6: Blower 7: Sludge extraction pump 10: Filter plate 11: Filtration membrane 12: Folding side 13 of filtration membrane: Filtration water Suction tube 14: peripheral edge of filtration membrane

Claims (1)

  In a membrane separation activated sludge treatment apparatus in which a membrane separation apparatus in which a plurality of membrane elements are arranged in a tank and an air diffuser is installed below the membrane separation apparatus, the membrane elements are arranged on the front and back of the filter plate. Filtration membranes are arranged on both sides and the periphery of the filtration membrane is tightly fixed to the filter plate and sealed, and the filtration membrane is folded on one side of the filter plate and arranged on both sides of the filter plate, Membrane separation activated sludge characterized in that the membrane element is arranged in the membrane separation device so that the filtration membrane surface is substantially the same as the vertical surface and the folded side of the filtration membrane is vertically upward Processing equipment.

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