JP2003144864A - Immersing type membrane filtering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dispersing plate which can disperse air bubbles to entire part even when the air bubbles occurring from a diffuser tube are gathered in the neighborhood of the center, and to provide a lightweight dispersing means whose maintenance is easy by making the structure of the dispersing plate into a simple shape. SOLUTION: In the immersing type membrane filtering device 1, a hollow fiber membrane module 4a is provided in which a plurality of hollow fiber membranes 2 are spanned between posts 3 and 3, the hollow fiber membrane module 4a and 4b are stacked in a multiple stage manner, and the diffuser tube 8 is provided which is formed at the lowermost stage side of the module 4a and causes the air bubbles for cleaning the hollow fiber membrane module. The dispersing means which has a predetermined tilt angle and guides the air bubbles risen to the sides of the posts 3 and 3 while cleaning the module 4a at the side of the lower part is provided between the module 4a and the module 4b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filtration device for purification such as industrial wastewater treatment and sewage treatment, and more particularly to an immersion type membrane filtration device for purification using a hollow fiber membrane module.

[0002]

2. Description of the Related Art Conventionally, as a means for purifying a suspension which is water to be treated, an immersion type membrane filtration device as disclosed in JP-A-11-57426 is known. This immersion type membrane filtration device is a membrane module in which a plurality of flat plate-shaped membrane elements (flat membrane elements) are arranged in parallel at predetermined intervals so that the membrane surfaces are parallel to each other. It is immersed in the treated water tank so that it is oriented, and an air diffuser is installed under the membrane module to diffuse air, and the membrane surface is cleaned by an air scrubbing cleaning method (hereinafter referred to as air scrubbing). Meanwhile, filtered water (purified water) is taken out.

FIG. 3 (a) disclosed in Japanese Patent Laid-Open No. 11-57426 shows a submerged membrane filtration apparatus 10 in which two membrane modules 15a and 15b are vertically stacked to form a water tank 11 to be treated. It is a schematic diagram which shows the state immersed. Figure 3
As shown in (a), the flat sheet membrane elements 14, 14 ...
Guide rail 21 for fixing the membrane modules 15a and 15b
It is provided between A and 21B and is installed in multiple stages. An air diffuser 18 is arranged at the bottom of the treated water tank 11. In this submerged membrane filtration device 10, the purified water outlet is provided in the upper portion 14a of the flat membrane element 14, and pipes for collecting the purified water are installed between the upper and lower membrane modules 15a and 15b. Since there is no need, the device structure is simple. In addition, each membrane module 15a,
15b is removable and individual membrane modules 15a,
15b allows the flat membrane element 14 to be inserted and removed, which facilitates workability in assembling the membrane module and exchanging the membrane element.

However, in the immersion type membrane filtration device 10,
The bubbles rising along the flat membrane element 14 of the membrane module 15a, 15b tend to be attracted and collected near the center between the membrane module 15a and the membrane module 15b. Therefore, when air is diffused from the lower side of the lower membrane module 15a by the air diffuser 18, in the upper membrane module 15b, the bubbles are gathered near the center, so that the passage region of the bubbles is unevenly distributed, and the flat membrane element is formed. The contact between 14 and bubbles becomes insufficient.

Therefore, the membrane modules 1 installed above and below
By providing the rectifying plate 16 between the 5a and 15b, the bubbles from the membrane module 15a are rectified and evenly distributed and enter the upper membrane module 15b, so that the bubbles are not unevenly distributed in the membrane module 15b. Can be prevented. Further, by rectifying the bubbles over the entire area of the membrane module 15b, it is possible to reliably prevent the flat membrane elements 14, 14 ... Of the membrane module 15b from being contaminated (adhered with dirt).

FIGS. 3B and 3C are perspective views showing the current plate 16. The current plate 16a shown in FIG. 3B is formed of a multi-layer plate and can prevent bubbles from moving in the left-right direction. Further, the current plate 16b is further formed in a lattice shape so that bubbles can be prevented from moving in the left-right direction and the front-back direction.

FIG. 4 is a sectional view of an immersion type membrane filtration device using a hollow fiber membrane module. As shown in FIG. 4, the immersion type membrane filtration device 30 is a hollow fiber in which a plurality of hollow fiber membranes 32 having a myriad of micropores are spanned between vertically arranged posts 33 in a water tank 38 to be treated. A membrane module 34a and a hollow fiber membrane module 34b stacked on top of it are arranged, and an external pressure type hollow fiber membrane module is used for filtering by extracting water from the upper ends of the posts 33, 33 for immersion type membrane filtration. In the apparatus 30, when the suspended substance adhering to the outer periphery of the hollow fiber membrane 32 is washed with air bubbles, the air bubbles generated from the air diffusing pipe 36 are also collected so as to be attracted to the center where the resistance is low.

[0008]

However, as shown in FIG. 4, even when the flow straightening plate 16 is provided between the hollow fiber membrane modules 34a and 34b, the bubbles generated from the air diffuser 36 are generated between the posts 33 and 33. It is difficult to disperse the air bubbles by the straightening vanes 16 juxtaposed to each other, because they tend to gather in the center. In addition, the straightening vane 16 has a problem that the structure is complicated and that maintenance such as cleaning is difficult.

[0009] Therefore, an object of the present invention is to provide a dispersion plate which can disperse air bubbles generated from an air diffusing tube in the whole area even if they gather around the center. Another object is to provide a dispersing means that is lightweight and easy to maintain by making the structure of the dispersing plate a simple shape.

[0010]

In order to solve the above-mentioned problems, an immersion type membrane filtration device according to a first aspect of the present invention comprises a hollow fiber membrane module having a plurality of hollow fiber membranes suspended between posts. , Stacking the hollow fiber membrane modules in multiple stages,
What is claimed is: 1. A submerged membrane filtration device comprising: a diffusing tube for generating bubbles for cleaning the hollow fiber membrane module on the lowermost side of the hollow fiber membrane module, wherein the hollow fiber membrane module and the hollow fiber membrane module Between the two or at the bottom of the hollow fiber membrane module, a dispersion means having a predetermined inclination angle and having an inclined surface for guiding bubbles rising from the lower side to the post side is provided. And

In the invention described in claim 1, the dispersing means having an inclined surface is provided in the lower portion of the hollow fiber membrane module or between the hollow fiber membrane modules, so that the dispersion from the lower layer is reduced. Bubbles can be dispersed into three parts, the right side part, the left side part, and the central part. Further, the bubbles dispersed on the right side and the left side strongly collide with the vicinity of the connecting portion of the hollow fiber membranes connected to both posts, and the impact causes the hollow fiber membranes to vibrate, and the vibration propagates to the central portion. By vibrating the entire hollow fiber membrane, a higher cleaning effect can be exhibited.

Claim 1 according to the invention described in claim 2
In the immersion type membrane filtration device described in the above, the dispersing means has an inclined surface on the upper side from the central portion between the pair of posts toward both posts, and the three directions of the right side portion, the left side portion, and the central portion. It is a dispersion plate that is dispersed in.

In the invention described in claim 2, the dispersion plate is composed of two plates and is installed in an inverted V shape.
The inclination angle of the inclined surface of the dispersion plate is preferably 45 to 70 degrees. Unlike the straightening vane, the dispersion plate with this angle is 3
Can be dispersed in any direction. In other words, by dispersing the innumerable bubbles gathering toward the center of the posts from the bottom to the top without impairing them, as a result, the bubbles are converged, and the bubbles are formed on both sides of the hollow fiber membrane that is spanned between the posts. By providing a vibration source for generating vibration by collision, and vibration of both of them and the vibration of the central portion resonate with each other to cause more irregular vibration, a higher cleaning effect can be exhibited. Further, by making the structure of the dispersion plate simple, it is possible to provide a dispersion means that is lightweight, inexpensive, and easy to maintain.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an immersion type membrane filtration device 1 of the embodiment. Also,
FIG. 2 is a perspective view of the immersion type membrane filtration device showing the whole. As shown in FIG. 1, the immersion type membrane filtration device 1 of the present invention
Is a hollow fiber membrane module 4a in which a plurality of hollow fiber membranes 2 are arranged in a bundle between water collecting pipes 3 which are vertically arranged posts. A hollow fiber membrane module group 5 in which a plurality of hollow fiber membrane modules 4a are arranged side by side in the water tank 8 to be treated
a and a hollow fiber membrane module group 5b in which a plurality of hollow fiber membrane modules 4b are arranged in parallel are arranged above and below a.

The submerged membrane filtration device 1 is a filtration device for purifying the hollow fiber membrane 2 immersed in water to be treated through a kind of filter. Therefore, it is possible to remove a suspended substance having a diameter larger than the innumerable micropores of the hollow fiber membrane 2. The micropores have a diameter of 0.01 to 0.001 μm, and can remove not only suspended substances but also Escherichia coli, general bacteria, viruses and the like.

As shown in FIG. 1, between the hollow fiber membrane module group 5a and the hollow fiber membrane module group 5b, there are dispersion plates 7a, 7a which are dispersion means for efficiently dispersing bubbles from below. It is provided. The dispersion plates 7a and 7b are 2
It is composed of a single plate and has an inverted C shape that spreads upward, and a gap is provided between the lower part of the dispersion plate 7a and the lower part of the dispersion plate 7b. The arrows in the figure indicate the flow of bubbles. It is easy to see that the flow of bubbles is dispersed into three bubbles: a bubble a on the right side, a bubble b on the left side, and a bubble c in the center. The inclination angle of the dispersion plates 7a and 7b is 45 °.
A range of ˜70 ° is preferable and an adjustable type is preferable. Dispersion plate 7a,
The shape of 7b may be flat or a corrugated plate having a corrugation. The material is SPC of steel plate
The C material and the SPHC material are coated with anticorrosion treatment or the like, but may be a stainless plate or a plastic plate. Further, at the bottom of the water tank to be treated, there is provided an air diffuser 6 for generating bubbles for cleaning the hollow fiber membrane 2 by air scrubbing. The air diffuser 6 is always
Compressed air is supplied.

FIG. 2 is a perspective view of the immersion type membrane filtration device 1. The arrows in the figure indicate the flow of bubbles. As shown in FIG. 2, countless bubbles from the air diffuser 6 provided at the bottom of the treated water tank 8 collide with the hollow fiber membranes 2 of the hollow fiber membrane modules 4a of the first hollow fiber membrane module group 5a. Clean with air scrubbing. And since countless bubbles rise while gathering in the central part where resistance is low,
The dispersion plates 7a and 7b of the present invention disperse into three.

That is, the air bubbles in the central portion passing between the dispersion plate 7a and the dispersion plate 7b continue to rise as they are, and the hollow fiber membrane is washed by air scrubbing. Air scrubbing refers to a method of blowing bubbles. Now, the air bubbles dispersed to the left and right by the dispersion plates 7a and 7b rise along the inclined surfaces of the dispersion plates 7a and 7b, and are diffused again to the left and right in the figure to air scrub the right side of the hollow fiber membrane module 4b. The cleaning effect can be enhanced by not only cleaning by means of the above, but also collision of the hollow fiber membrane module 4b in the vicinity of the connecting portion between the post 3 and the hollow fiber membrane 2 and vibrating the hollow fiber membrane by the impact. The same applies to the left side.

As described above, by effectively providing the vibration sources on both sides of the hollow fiber membrane 2 of the hollow fiber membrane module 4b, the vibrations of the both and the vibration of the central portion resonate with each other to cause more irregular vibration. By causing it, the cleaning effect of the hollow fiber membrane 2 can be further enhanced. Further, the entire cleaning is efficiently performed, and it is compact, space saving, and low cost.

The present invention is not limited to this embodiment, but can be appropriately modified as long as it is based on the technical idea of the present invention. For example, the dispersing means for dispersing the bubbles is not limited to between the hollow fiber membrane module group 5a and the hollow fiber membrane module group 5b, and may be installed below the hollow fiber membrane module group 5a or in the middle. It doesn't matter. Further, the dispersion means having the inclined surface is not limited to the dispersion plate which is the inclined plate, and may have a form as shown in FIGS. 2B and 2C. That is, FIG. 2B is a perspective view, and shows an example in which a triangular dispersion column-shaped hollow dispersion means having an inclined surface has a triangular cross-sectional shape, and the hypotenuse thereof is an inclined surface. Further, FIG. 2C shows an example in which a solid block in the shape of a triangular prism having an inclined surface is used as the dispersion means.

[0021]

As described in detail above, according to the immersion type membrane filtration device of the present invention as set forth in claim 1, in order to enhance the air scrubbing effect, an inclination is provided between vertically adjacent hollow fiber membrane modules. By installing the dispersion plate, the bubbles from the lower layer can be dispersed in the left side portion, the center portion, and the right side portion. Further, vibration sources due to collision of bubbles are provided on both sides of the hollow fiber membrane of the hollow fiber membrane module, and the vibrations of both of them and the vibration of the central portion resonate with each other to cause more irregular vibration. The cleaning effect can be further enhanced. Further, the entire cleaning is efficiently performed, and it is compact, space saving, and low cost.

According to the immersion type membrane filtration device of the present invention as defined in claim 2, the dispersion plate can disperse the light in three directions for focusing. In other words, by dispersing the innumerable bubbles gathering toward the center of the posts from the bottom to the top without impairing them, as a result, the bubbles are converged, and the bubbles are formed on both sides of the hollow fiber membrane that is spanned between the posts. By providing a vibration source that generates vibration by colliding with each other and the vibration of both of them and the vibration of the central portion resonate to cause more irregular vibration, a higher cleaning effect can be exhibited. Further, by making the structure of the dispersion plate simple, it is possible to provide a dispersion plate that is lightweight, inexpensive, and easy to maintain.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an immersion type membrane filtration device showing an embodiment.

FIG. 2A is a perspective view of an immersion type membrane filtration device showing the entire embodiment. (B) is a perspective view showing an example of a dispersion means having an inclined surface. (C) is a perspective view showing an example of a dispersion means having an inclined surface.

FIG. 3A is a schematic diagram showing a conventional immersion-type membrane filtration device, in which membrane modules are vertically stacked in two stages and immersed in a water tank to be treated. (B), (c) is a perspective view which shows the shape of a current plate.

FIG. 4 is a cross-sectional view of a conventional submerged membrane filtration device using a hollow fiber membrane module.

[Explanation of symbols]

1 Immersion type membrane filtration device 2 Hollow fiber membrane 3 post (water collection pipe) 4a, 4b hollow fiber membrane module 5a, 5b Hollow fiber membrane module group 6 Air diffuser 7a, 7b Dispersion plate

Continued front page    F-term (reference) 4D006 GA07 HA16 HA19 HA93 JA19A                       JA29A JA29C JA31A KA43                       MA22 PA01 PB08

Claims (2)

[Claims] 1. A hollow fiber membrane module in which a plurality of hollow fiber membranes are laid between posts and the hollow fiber membrane module are stacked in multiple stages, and the hollow fiber membrane module is washed on the lowermost side of the hollow fiber membrane module. An air diffusing tube for generating air bubbles for, and an immersion type membrane filtration device comprising: between the hollow fiber membrane module and the hollow fiber membrane module,
Alternatively, the hollow fiber membrane module is provided at its lower portion with a dispersion means having a predetermined inclination angle and having an inclined surface for guiding bubbles rising from the lower side to the post side. Membrane filtration device. 2. The dispersion means has an inclined surface on the upper side from the central portion between the pair of posts toward both posts,
The immersion type membrane filtration device according to claim 1, which is a dispersion plate that disperses in three directions of a right side portion, a left side portion, and a central portion.