JPH11156162A - Membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane module wherein the membrane module in which permeated water is obtained by feeding raw water to a plane membrane, the raw water can be filtered in a short time, and concentration and a deposit can be recovered easily and safely without waste. SOLUTION: A scraper 7 which is placed on a membrane surface to a raw water side of a plane membrane 4 and contains a magnet, and a supporting plate 2 and a cover 3 as a housing a guide space holding liquid tightly the plane membrane 4 guiding the scraper 7 in a surface direction of the plane membrane 4 between an inlet of the raw water and the surface to the raw water side of the plane membrane 4, are provided. When a part, among the housing, opposed to a surface of the raw water side of the plane membrane 4 is made transparent, a state of the plane membrane 4 can be seen from outside conveniently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a membrane module, and more particularly to a membrane module for filtering raw water containing microorganisms such as protozoa and fungi.

[0002]

2. Description of the Related Art Some microorganisms such as protozoa and fungi are difficult to detect because there is no means for culturing them. For example, Cryptosporidium, a pathogenic protozoan parasitizing in the digestive tract of mammals. The protozoa may be parasitized using drinking water as a medium, and inhabit oocysts in rivers, lakes, and the like serving as water sources for water purification plants. Only a few Cryptosporidium oocysts are present in 10 L of water and do not grow outside the host organism.
Therefore, when detecting this protozoan from raw water collected from a river or the like, it is necessary to concentrate 20 L or more of raw water to several tens to several hundred mL.

[0003] Conventionally, a membrane module utilizing filtration by a membrane has been used for concentrating raw water containing microorganisms. Among these, the batch type flat membrane module is generally used, and there are a total filtration type and a type provided with a stirrer.

[0004]

However, in the flat membrane module of the total filtration type, the sediment generated by the filtration covers the surface of the flat membrane, so that the filtration rate decreases as the sediment increases. It takes a long time to filter the whole amount. Also, if the filtration rate is significantly reduced,
The flat membrane needs to be replaced.

[0005] In a flat membrane module provided with a stirrer, although a decrease in filtration speed can be suppressed to some extent, since the flat membrane area cannot be increased, it takes a long time to perform filtration. Furthermore, in this type of flat membrane module, the concentrated solution and the deposits are liable to adhere to the dead space and the like, so that the concentrated solution and the deposits cannot be collected without waste. There is also a method of disassembling the module and scraping off the attached concentrate and deposits with a wiper, but the work is complicated, and when the module is disassembled,
In doing so, the loss of concentrate and sediment cannot be avoided and there is a risk of infection.

Therefore, an object of the present invention is to enable raw water to be filtered in a short period of time, and to concentrate and deposit without waste.
An object of the present invention is to provide a membrane module that can be easily and safely recovered.

[0007]

SUMMARY OF THE INVENTION The present invention provides a membrane module for supplying raw water to a flat membrane to obtain permeated water, comprising: a scraper which is placed on the raw water side of the flat membrane and has a magnet built therein; In addition to maintaining the membrane in a liquid-tight manner, a housing having a guide space for guiding the scraper in the plane direction of the flat membrane is provided between the raw water inlet and the surface of the flat membrane on the raw water side.

[0008] A scraper containing a magnet is placed on the membrane surface of the flat membrane, and the housing has a guide space for guiding the scraper in the plane direction of the flat membrane. The scraper moves on the surface of the flat membrane. Therefore, when the raw water is filtered while the scraper is moved to scrape off the sediment, the filtration speed can be reduced in a short time without lowering the filtration speed. Further, when the concentrated liquid and the deposit are collected, by moving the scraper, the concentrated liquid and the deposited substance can be mixed, so that the collection can be performed without waste. Moreover, the recovery operation is simple and there is no fear of infection.

It is convenient to make the portion of the housing that faces the raw water side of the flat membrane transparent so that the state of the flat membrane can be seen from the outside. In addition, scraper,
When a triangular prism, a quadrangular prism, or the like having an edge is used, the sediment can be efficiently scraped off. Also, it is possible to prevent the concentrated liquid and the deposit from adhering to the scraper.

[0010]

FIG. 1 is a sectional view and FIG. 2 is a plan view of an embodiment of the present invention. FIG. 3 is a perspective view of the scraper.

In the membrane module 1 shown in FIGS. 1 and 2, the housing comprises a support plate 2 and a lid 3. Both the support plate 2 and the lid 3 are circular in plan view. The support plate 2 is provided with a permeated water outlet 11, and the lid 3 is provided with a raw water inlet 9 and an air hole 10. The support plate 2 and the lid 3 are fixed to each other by screws 12, and the O-ring 6 is interposed therebetween to prevent liquid leakage. Inside the housing,
The flow path member 5 and the flat membrane 4 having the same shape and the same area as the bottom surface of the support plate 2 are sequentially installed from the permeate outlet 11 side. A rubber scraper 7 having a triangular prism shape is placed between the flat membrane 4 and the lid 3 as shown in FIG. The raw water side surface of the flat membrane 4 and the inner surface of the lid 3 are
And at an interval so as to be in contact with the inner surface of the lid 3. Therefore, the space formed between the flat membrane 4 and the lid 3 functions as a guide for guiding the scraper 7 in the plane direction of the flat membrane 4. Further, since the scraper 7 has the magnet 71 built therein, another magnet 8 is disposed outside the housing, and when the magnet 8 is moved on the outer surface of the lid 3, the scraper 7 simultaneously moves on the film surface of the flat film 4. .

The shape of the support plate 2 and the lid 3 in plan view is not limited to a circle, but is preferably a circle in consideration of the operability of the scraper 7. As the material, a transparent resin that easily conducts magnetism is used. For example, polyvinyl chloride, acryl, polycarbonate and the like can be mentioned.

The type of the flat membrane 4 may be appropriately selected according to the object to be concentrated. When concentrating raw water containing microorganisms, use a microfiltration membrane (MF membrane) or ultrafiltration membrane (UF membrane).
Membrane) can be used. Preferably, the pore size is 0.4
Use an MF film of 5 μm or less. Further, as the material of the flat membrane 4, cellulose acetate, PTFE, polypropylene, polyolefin, polysulfone, or the like is used.

The magnet 71 incorporated in the scraper 7 includes:
A ferrite magnet or a neodymium magnet can be used, but a neodymium magnet having a strong magnetic force is preferable. The magnetic flux density of the magnet 71 is preferably 1500 G or more.
00G or more is particularly preferred.

The flow path member 5 is made of a porous material and functions to guide the permeated water to the permeated water outlet 11 while supporting the flat membrane 4 against the liquid pressure on the raw water side. Materials that can be used for the flow path member 5 include polyester, polypropylene, and polyethylene.

FIG. 4 is a system flow chart showing an example of use of the membrane module 1. Pressure tank 15 at raw water inlet 9
However, valves 13 are connected to the air holes 10, respectively. The following procedure may be used to filter raw water with the system shown in FIG.

First, a compressed gas is injected through a gas line 14 into a pressure tank 15 containing raw water. Then, raw water is supplied from the raw water line 16 into the membrane module 1 from the raw water inlet 9. At this time, the valve 13 is opened for a while after the supply is started in order to remove the air in the membrane module 1. Next, when the valve 13 is closed, the raw water supplied into the membrane module 1 is filtered by the flat membrane 4 and concentrated in the membrane module 1. The permeated water passes through the flow path member 5 and is discharged from the permeated water outlet 11 through the permeation line 17. The sediment increases as the filtration continues, but in order to prevent a decrease in the filtration speed due to the sediment, the magnet 8 is moved by hand and the scraper 7 is used to occasionally scrape the sediment to filter. The operation of scraping the deposit with the scraper 7 may be performed at all times during the filtration. In this case, it is convenient to install a magnetic stirrer and automatically rotate the scraper 7. When the raw water is sufficiently concentrated, the valve 13 is opened to stop the filtration. When collecting the concentrated liquid and the sediment, the concentrated liquid and the sediment are sucked by a pump from the raw water inlet 9 and collected while being mixed with the scraper 7. When the concentrated liquid and the deposits remain in the membrane module 1, a small amount of pure water is added, washed, and then sucked again. Although the system shown in FIG. 4 shows an example in which filtration is performed while applying pressure through the gas line 14, filtration may be performed by reducing the pressure of the permeated water outlet 11 using a vacuum pump or the like.

[0018]

EXAMPLE Filtration of river water was attempted using the membrane module 1 of FIGS. The time required for concentrating 20 L of raw water 100 times is compared between the case where the scraper 7 has not scraped off the sediment during the filtration and the case where the scraping has been done at intervals of 7 to 9 minutes. did. The conditions relating to the flat membrane, pressure and the like are as follows. Raw water sample: Tokyo, Arakawa river water (water temperature, 25 degrees Celsius), 2
0L flat membrane: Nitto Denko UF membrane NTU-3175M (350m diameter)
m, effective membrane area 0.096m ² ) Pressure: 50 Torr (reduced pressure)

As a result, when no scraping was performed, the time required for concentrating 20 L of the raw water 100-fold was 62 minutes. On the other hand, when the scraping was performed at intervals of 7 to 9 minutes, it was possible to concentrate 100 times in 49 minutes. From the above, it has been clarified that if the sediment is filtered while scraping off by a scraper, a decrease in the filtration speed can be prevented and the filtration time can be shortened. After the filtration is completed, the concentrated solution and the sediment are mixed with a scraper, suctioned with a pump, and a small amount of pure water is added to wash the inside of the membrane module. Then, the concentrated solution and the sediment are collected without waste. I was able to.

[0020]

According to the present invention, the raw water can be filtered in a short time, and the concentrated liquid and the sediment can be recovered easily and safely without waste.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a membrane module of the present invention.

FIG. 2 is a plan view showing an embodiment of the membrane module of the present invention.

FIG. 3 is a perspective view of a scraper.

FIG. 4 is a system flow chart showing an example of use of the membrane module of the present invention.

[Explanation of symbols]

 1, membrane module 2, support plate 3, lid 4, flat membrane 5, flow path material 6, O-ring 7, scraper 71, magnet 8, magnet 9, raw water inlet 10, air hole 11, permeated water outlet 12, screw 13, valve 14, gas line 15, pressure tank 16, raw water line 17, permeation line

Claims (5)

[Claims] 1. A membrane module for supplying permeated water by supplying raw water to a flat membrane, comprising: a scraper which is placed on the raw water side of the flat membrane and has a built-in magnet; And a housing having a guide space for guiding the scraper in the surface direction of the flat membrane between the raw water inlet and the surface of the flat membrane on the raw water side. 2. The membrane module according to claim 1, wherein a portion of the housing facing the raw water side surface of the flat membrane is transparent. 3. The membrane module according to claim 1, wherein the scraper has a shape having an edge such as a triangular prism or a quadrangular prism. 4. The membrane module according to claim 1, wherein the flat membrane is a membrane that does not allow passage of microorganisms such as protozoa and fungi. 5. The magnet according to claim 1, wherein the magnet is a neodymium magnet.
5. The membrane module according to any one of to items