JPH11319513A - Membrane element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a filtration membrane from peeling off a filtration plate by the vibration of the filtration membrane by foam by structuring the filtration membrane of a support on one of the faces of which a membrane material is coated and with the other face exposed, in the membrane element consisting of the filtration membrane arranged on both faces of the filtration plate having a projecting and recessed part on the surface. SOLUTION: The membrane element provided in a membrane separation device to be used for filtrating an industrial waste water or the like is composed of a filtration membrane 3 arranged on both faces of a filtration plate 1 having a projecting and recessed part 10 on the surface. The filtration membrane 3 is of such a construction that a membrane material 31 of polyolefin or polysulfone coats one of the faces of an nonwoven fabric of polyolefin or polyester as a support 30 and the support 30 is exposed on the other face of the fabric which dues not coat the membrane material 31. Further, the filtration plate 1 is an extruded molding of polypropylene, polyethylene, polycarbonate or the like and has a projecting and recessed part 10 for forming a water gathering passage 2 which receives a filtrate, provided on the surface. Thus the problem that the filtration membrane 3 peels off the filtration plate 1 is solved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane element, and more particularly, to a membrane separation apparatus for filtering or concentrating industrial wastewater or middle sewage water.
The present invention relates to a membrane element having improved durability and reliability.

[0002]

2. Description of the Related Art A membrane separation apparatus for filtering or concentrating industrial wastewater or middle sewage water, etc., often employs a method of filtering a stock solution by applying a negative pressure to a filtrate side of a plurality of membrane elements immersed in a stock solution tank. ing.

[0003] In the above-mentioned membrane separation apparatus, as the filtration proceeds, the substance captured by the filtration membrane adheres to the surface to form a cake layer, thereby decreasing the filtration flow rate. The filtration is interrupted and air is supplied from below the membrane element to generate air bubbles, and the adhesion of the cake layer is suppressed by the vibration of the filtration membrane due to the air bubbles and the contact between the air bubbles and the cake layer, and the adhering cake layer Is promoted, and the membrane element can be used for a long period of time.

As the membrane element used in the above-mentioned membrane separation device, there are a membrane element made of a hollow fiber and a flat membrane suitable for filtration of a relatively large volume. In recent years, a membrane element made of a flat membrane has been frequently used. ing.

[0005] The flat membrane is obtained by coating a membrane material on a support such as a non-woven fabric in order to increase the strength. The membrane element is such that the flat membrane is disposed on both sides of a filter plate, and the filtrate is filtered by the filter plate. To form a flow path for obtaining the same.

An example of a membrane element using the above-mentioned flat membrane is described in Japanese Patent Application Laid-Open No. 5-137971.

That is, what is described in the above publication is
A membrane material is coated on the surface of a support made of nonwoven fabric, and the support is adhered to both sides of a filter plate.A filtration membrane formed by coating the membrane material on the support is directly adhered to the filter plate. Therefore, a membrane element having high adhesive strength between the filtration membrane and the filter plate can be obtained.

[0008] Then, a filtrate outlet for obtaining a filtrate is provided at the upper part of the filter plate, and filtration is performed by applying a negative pressure to the filtrate outlet, and if necessary, a device for generating air bubbles below the filter plate is provided. The filter is interrupted during or periodically during filtration and air is fed into the apparatus to generate air bubbles, and the adhesion of the cake layer is suppressed by the vibration of the filtration membrane due to the air bubbles and the contact between the air bubbles and the cake layer. The membrane element can be used for a long period of time by promoting the peeling of the attached cake layer.

[0009]

The membrane element described in the above publication can prevent the problem that the filtration membrane is peeled off from the filter plate due to the vibration of the filtration membrane caused by air bubbles, and can be used for a long time. Although it is possible to obtain a membrane element that can withstand, when the use period is long, the filtration membrane peels off from the peripheral portion where the filtration membrane and the filter plate are bonded,
Although the filter membrane is not damaged at the center where the filter membrane and the filter plate are not bonded, the filter membrane vibrates and the filter membrane and the filter plate come into contact with each other, and the filter membrane is worn out. There is the problem that the substances to be trapped are mixed in the filtrate, thereby reducing the reliability of the membrane element.

[0010]

Means for Solving the Problems In order to solve the above problems, the invention according to claim 1 is a membrane element in which filtration membranes are arranged on both sides of a filter plate having an uneven portion on the surface, wherein the filtration membrane is One side of the support is coated with a membrane material and the other side is exposed to the support, and the surface facing the filter plate is the other surface,
As a result, even if the filter membrane vibrates due to bubbles and the filter membrane and the filter plate or the filter and the spacer arranged to form the flow path for obtaining the filtrate come into contact with each other, the filter membrane is supported on the surface facing the filter plate. Since the body is exposed, it is possible to prevent a problem that the filtration membrane is worn and a substance to be captured by filtration is mixed into the filtrate.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on its embodiments.

FIG. 1 is a sectional view of a membrane element according to an embodiment of the present invention.

A feature of the membrane element according to the embodiment of the present invention shown in FIG. 1 is that a filter plate 1 having an uneven portion 10 on its surface is provided.
Filtration membranes 3 are arranged on both sides of the support 30.
One side of the non-woven fabric is coated with the film material 31,
The support 30 is exposed on the other surface, and the surface facing the filter plate 1 is the other surface.

The filter plate 1 is preferably a lightweight and inexpensive resin, such as polypropylene, polyethylene, or polycarbonate, which can easily form the uneven portion 10 on the surface and can be continuously manufactured by extrusion.

The filtration membrane 3 has a thickness of 0.1 mm.
One surface of a non-woven fabric of polyolefin or polyester as the support 30 having a thickness of about 2 to 0.6 mm is coated with a polyolefin or polysulfone type membrane material 31, and the surface coated with the membrane material 31 has a pore diameter of 0.1 mm.
About 25 to 0.4 μm, and the thickness of the film material 31 is 0.1 to
The thickness is set to about 0.2 mm, and the other surface not coated with the film material 31 exposes the support 30.

A filter membrane 3 is provided on both sides of the filter plate 1.
A filter membrane 3 and the filter plate 1 are integrated at the peripheral edge, and a filtrate collecting channel 2 is formed by the uneven portion 10 on the surface of the filter plate 1. .

Next, the above-mentioned filtration membrane 3 and filter plate 1 are integrated, and have a width of 300 mm, a height of 500 mm and a thickness of 7 mm.
mm of the membrane element of the present invention and a filtration membrane 3 of the same material
Then, the membrane material is coated on both sides of the support, the pore diameter is about 0.25 to 0.4 μm, and the thickness is 0.1 to 0.2 mm.
20 conventional membrane elements of the same dimensions, each of which is about the same size, were manufactured, and a flat-plate type membrane separation device was manufactured using each of them. And immersed in a stock solution having a concentration of 1000 ppM, and continuously suction-filtered while bubbling by feeding air at 15 liter / m ² · min from below, and 3 months after the start, When the presence or absence of turbidity of the filtrate was examined after 6 months, the filtrate obtained from the flat plate type membrane separation device using the membrane element of the present invention did not show turbidity even after 6 months had passed. The filtrate obtained from the plate-type membrane separation device using the above membrane element did not show any turbidity after 3 months, but slightly after 6 months. Then, when the filtrate obtained from the conventional membrane element was examined, it was found that the filtrate obtained from two of the twenty membranes was turbid.

When the element having a turbidity in the filtrate was disassembled and the filtration membrane was examined, a part of the membrane surface of the filtration membrane on the side from which the filtrate was obtained was peeled off to expose the nonwoven fabric as a support. As a result, it was found that the pore diameter of the filtration membrane was enlarged, and that redwood in the stock solution was leaking to the filtrate side.

[0019]

As described above, according to the first aspect of the present invention, since the support is exposed on the surface of the filter membrane facing the filter plate, the filter membrane and the filter plate or the filter membrane and the filtrate are exposed. Can prevent the problem that the filtration membrane is worn out due to contact with the spacers and uneven portions arranged to form the flow path for obtaining the flow path, thereby contributing to the improvement of the reliability of the membrane element. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view of a membrane element according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Filter plate 2 Filtrate collecting channel 3 Filtration membrane

Claims (1)

[Claims] 1. A membrane element comprising a filter plate having an uneven portion on its surface and a filter membrane provided on both sides of said filter plate, said filter membrane coating a membrane material on one side of a support and exposing the support on the other side. A membrane element, wherein the surface facing the filter plate is the other surface.