JP2538789B2 - Flat membrane type ultrafiltration machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a flat membrane type ultrafiltration machine, and more particularly to a flat membrane type ultrafiltration machine capable of eliminating clogging of an intermembrane flow channel.

BACKGROUND OF THE INVENTION Conventionally, a so-called UF membrane treatment technology has been known in which an ultrafiltration membrane (hereinafter referred to as UF membrane) is incorporated to treat waste liquid.

The inventors of the present invention developed a unique process using a UF membrane (Japanese Patent Application No. 59-267725, etc.), applied it to various waste liquids such as domestic wastewater and night urine, tried various experiments, and completed the process. Striving for development.

The UF membrane used in this process is a so-called flat membrane,
Regarding the membrane module structure, refer to Japanese Examined Patent Publication No. 52-10113.
No. 53-3756, No. 57-7524, and the like. An outline of this membrane module is as follows: flat membranes are placed on both sides of the membrane plate, a gap (groove) is provided between the membrane and the plate, and the module units of the membrane-coated plate are coaxially arranged side by side. It has a structure that allows the undiluted solution to pass through.

The present inventors have applied this membrane module to wastewater treatment. Here, the treatment of tap water refers to a series of processes for treating domestic wastewater generated from a building or the like and reusing it for drinking water (clean water), for example, a flush toilet. As a result, the treatment effect of the membrane module was confirmed.

Then, when the subject to be treated was further expanded and the membrane module was tried to be applied to the treatment of human urine, it was found that a problem considered to be "blockage of the transmembrane channel" occurred. Therefore, in order to eliminate the blockage, it is necessary to open the membrane module and clean the membrane surface, which requires a lot of labor for the cleaning and at the same time exerts an unreasonable pressure on the membrane, resulting in damage to the membrane. It has been found that there is a problem that the membrane replacement cost increases.

[Object of the Invention] Therefore, an object of the present invention is to provide a flat membrane type ultrafiltration machine capable of significantly reducing the labor and cost required for membrane cleaning in UF membrane treatment.

[Means for Solving Problems] The inventors of the present invention have earnestly studied to achieve the above object, and have obtained the following findings.

Generally, in the UF membrane treatment process, basically clogging such as clogging inside the membrane and clogging at the gel layer on the membrane surface can be considered, but clogging inside the membrane can be solved by the structure of the membrane itself, and It has been found that the blockage in (1) is solved by, for example, corrugating the shape of the support for attaching the membrane (see JP-A-55-86510).

However, if the membrane treatment of human waste is intermittently performed for a long period of time, a solid phase is inevitably formed on the membrane surface and the intermembrane flow channel is blocked, so that a target flux (permeation flux) cannot be obtained. For this reason, open frame cleaning is usually performed. What is open frame cleaning here?
As mentioned above, when the target flux cannot be obtained, the packing and frame body in the membrane module are disassembled, the membrane surface is exposed, and cleaning is performed with a sponge (hereinafter, this cleaning The law is called unavoidable open frame cleaning).

As a pretreatment of the UF membrane, we also considered installing a screen with a 0.2 to 1 mm opening and installing a centrifuge, but in both cases, it is enough to reduce the number of open frame cleaning to obtain the target flux. It wasn't.

The inventors of the present invention further advanced the investigation and pursued the cause of generating the extra open-frame washing, and the occurrence of the solid phase on the membrane surface is a unique problem that the membrane is blocked by an intermembrane flow channel different from the above basic cause of clogging. It was discovered that there was. The clogging of the intermembrane flow channel was such that when a foreign substance existing between the membranes adheres to the membrane surface, it becomes a nucleus to accelerate the growth of the clogging area, and the filtration function is lost.

Further, it was also found that the above-mentioned foreign matter as a core exists only in human excrement and is a crude fiber material that does not exist in the raw water of the above-mentioned raw water.

Based on the above findings, the present inventors have earnestly studied, and as a result, by making the distance between the films longer than before, no extra open-frame cleaning is necessary without devising pretreatment, and the labor and cost required for cleaning. The present invention has been made by discovering that such problems can be reduced.

That is, the flat membrane ultrafilter according to the present invention is a flat membrane ultrafilter in which a stock solution is passed between parallel flat membranes and separated into a permeate and a concentrated solution, wherein the flat membrane is corrugated. Is a structure in which a membrane supporting plate on which irregularities are formed is fixed, the flat membrane spacing is 2 mm to 6 mm, and the flat membrane spacing is a space held by the thickness of the packing. .

 Hereinafter, the configuration of the present invention will be described in detail.

First, an example of a flat sheet membrane ultrafilter according to the present invention will be described with reference to FIG.

FIG. 1 is a schematic perspective view of a main part of the flat sheet membrane type ultrafiltration machine of the present embodiment.

In the figure, 1 is a support frame provided on both sides of the main body of the filter, one of which is shown in the figure. The support frame 1
Can be constructed by assembling a rectangular member or L-shaped steel, and the reinforcing member 1A may be installed if necessary.

A guide member 2 is provided at the center of the upper portions of both support frames 1. In this embodiment, the guide member 2 is However, any member may be used as long as it can slide a membrane module or the like described later in parallel to the axial direction X.

Reference numeral 3 is a side plate provided near the support frame 1. The side plate 3
The upper part is slidably hooked on the guide member 2, and the lower part is fitted with a support rod 4 in a notch (not shown).
Lateral shake is prevented. Above the side plate 3, two through holes 5A and 5B for the undiluted solution inlet are provided, and the two through holes 5A and 5B are provided.
A stock solution supply pipe (not shown) is connected to.

The positions where the through holes 5A and 5B are provided are the side plates 3 as shown in the drawing.
May be above, but is not limited to this, and may be below. On the side surface of the side plate 3, there is a groove for mounting a guide rod.
One or two or more 3A may be provided.

Reference numeral 6 denotes a membrane support plate. An upper portion of the membrane support plate 6 is slidably hooked on the guide member 2, and a support rod 4 is fitted in a notch 7 at a lower portion thereof to prevent lateral shake.

A plurality of the membrane supporting plates 6 are provided so as to be in contact with each other to form one set. In the present embodiment, a case where four sheets are set is shown. However, the number of sets is not limited and may be any number. .

The structure of the membrane supporting plate 6 will be described with reference to FIG. 2 as well. Grooves 9A and 9B are formed on both surfaces of the plate 8, and a flat film shape is formed so as to cover the grooves 9A and 9B. The ultrafiltration membrane 10 is fixed.

On the bottom surfaces of the groove portions 9A and 9B formed on both surfaces of the plate 8, the unevenness 11 having a corrugated cross section as shown in the drawing is formed.

A through hole 12A and a through hole 12B are provided above the membrane supporting plate 6 and are provided at the same height as the through holes 5A and 5B.
It is preferable that the duct-shaped liquid flow paths be formed by 5A and 12A and by the through holes 5B and 12B, respectively.

Similarly, the through holes 13A, 1 are also provided below the membrane supporting plate 6.
3B is provided.

A liquid flow path is formed in the through holes 12A, 12B, 13A, 13B by, for example, a male and female sealing member 12 ', and water tightness between the membrane 10 and the plate 8 is secured.

Below the plate 8, a permeate passage 14 communicating with both the groove portions 9A and 9B is provided.

A vinyl hose 16 is attached to the outlet of the permeate passage 14 through a nozzle 15. In Figure 1, vinyl hose 16
Although only one is shown, each is provided for each membrane support plate 6, and a plurality of vinyl hoses are collected in the water collecting pipe 17.

A packing 18 called a frame joint is attached between the plurality of membrane support plates 6 to prevent the liquid from leaking to the outside and to adjust the distance between the membranes. Also, the packing 18
Also serves to fix the membrane on the side surface of the support plate 6.

20 is a separating plate, and the plate 20
Through holes 21A and 21B are provided below. 20A is a notch.

When the above-mentioned membrane supporting plate 6 is provided in contact with the side plate 3 via the packing 22 and the separating plate 20 is provided in contact with the membrane supporting plate 6 via the packing 23, the membrane module units M ₁ , M ₂ , ... Is configured. Two or more membrane module units are combined to form a membrane module.
FIG. 2 shows a case where a membrane module is constructed by combining two membrane module units using two membrane support plates.

The outline of the flat membrane type ultrafiltration machine to which the present invention is applicable has been described above.
It will be described with reference to FIGS.

In the present invention, the distance between the flat membranes refers to the inner distance L between the membranes as shown in FIG. 3, and in the case where the membrane itself is wavy as shown in FIG. is there.

In the present invention, the distance between the flat membranes is 2 mm to 6 mm, preferably 3 mm to 5 mm. If it is less than 2 mm, there is no blockage preventing effect, and if it exceeds 6 mm, not only is the treatment flux reduced, but it is not economical because the area of the incorporated membrane per module cannot be increased. The interval can be arbitrarily changed by means such as changing the thickness of the packing.

In the present invention, it is not necessary to keep all the membranes of the membrane module constant within the above range, and it may be varied, or may be varied within each membrane module unit, and further varied on both sides of the membrane. Good. Further, for example, one membrane module may be configured by combining module units with 2 mm intervals, module units with 2.5 mm intervals, and module units with 3 mm intervals. In such a combination, the membranes forming the module unit closer to the stock solution supply side may be widened and the membranes forming the module unit on the outlet side may be narrowed, or vice versa.

In the present invention, the term “distance between membranes” includes not only the case where both sides are membranes as described above but also the distance between the membrane 10 and the side plate 3 or the membrane 10 and the separating plate 20 (see FIG. 4). reference).

Next, the outline of the processing mechanism of the UF membrane will be described with reference to FIG.

When the pressurized stock solution is supplied to the first membrane module unit M ₁ , it is distributed to three flow paths (three passes).
Flows from above to below. Part of the undiluted solution passes through the membrane 10 and the groove
Enter into 9A and 9B, pass through permeate passage 14, vinyl hose
It is collected in the water collection pipe 17 via 16 and becomes a treatment liquid.

 The mechanism for passing through the membrane is as shown in FIG.

That is, an active skin layer having a porous structure (thickness of about 0.1 to 1 μm
Pass about 10A, then sponge layer (thickness about 150-200
The permeated liquid is obtained by passing through 10B (about 10 μm), while the unpermeated liquid advances as it is in the flow direction of the stock solution as a concentrated liquid.

The flow direction of the undiluted solution is upside down with the separating plate 20 as a boundary, and the second membrane module unit M ₂ flows from the lower side to the upper side in the drawing.

In this embodiment, the stock solution is supplied above the first membrane module unit M ₁ , but the present invention is not limited to this and may be supplied below.

In the above examples, the stock solution supplied to the two through holes 5A and 5B is processed without being separated in series in the membrane module.
It is also possible to divide the membrane module into two in the vertical direction and perform two-series processing.

The flat membrane type ultrafiltration machine of the present invention is effective when applied to the treatment of human waste liquid, but it is also effective for the treatment of wastewater of a municipal water supply.

 The film used in the present invention may be a flat film.

The process to which the flat membrane ultrafilter of the present invention can be applied is not particularly limited, but processes A to E shown in FIG. 6 are exemplified.

In the figure, Pre is pretreatment (foreign matter treatment, coagulation sedimentation,
Dehydration treatment, sludge treatment, etc.), Bio is biological treatment (organic matter treatment, denitrification treatment, dephosphorization, etc.), UF is the flat membrane ultrafilter of the present invention, Suldge is sludge treatment, Phos is dephosphorization treatment (special treatment). Wish 61
-236725), Med is a drug, High Bio is an advanced biological treatment (for example, Chlorella treatment, etc., see Japanese Patent Application No. 60-287480), and Cake is a dehydrated cake treatment (incineration).

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 A total of 3 membrane module units (M ₁ , M ₂ , M ₃ ) configured with 5 membrane support plates (6 passes) are combined.
A series of membrane modules were constructed. The intermembrane distance was changed as shown in Table 1.

As the target undiluted solution, human waste from the human waste treatment plant in Chiba Prefecture is used,
The process A in FIG. 6 was adopted as the processing process.

 The processing conditions were as follows.

Target filtration amount 15m ³ / D Membrane specifications: Membrane area 14m ² or more was treated and the clogging condition was investigated for 1 month. Table 1 shows the results.

× in the table: The occlusion was severe and the open frame cleaning was required before less than one month.

△: A little occlusion was seen after 1 month.

○: Almost no occlusion was observed after 1 month.

A: No obstruction was observed after 1 month.

As is clear from the table, when the distance between the membranes is within the range of the present invention, there is no clogging, whereas when it is 1.5 mm as in No. 1, it is found that the membrane clogging is severe. Further, it was found that when the thickness exceeds 7.0 mm, not only the intermembrane blockage is observed, but also there is no economical efficiency.

Example 2 An experiment was conducted in the same manner as in Experiment No. 4 of Example 1 except that the target stock solution was replaced with medium water.

As a result, UF treatment was possible without clogging and without long-term washing, as compared with the case of human waste.

[Effect of the Invention] According to the present invention, it is possible to provide a flat membrane type ultrafiltration machine which can greatly reduce the labor and cost required for membrane cleaning in UF membrane treatment.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of an essential part showing an example of a flat membrane ultrafilter of the present invention, FIG. 2 is a schematic sectional view showing an example of a membrane module structure of the present invention, and FIGS. 3 and 4 are FIG. 5 is a cross-sectional view for explaining the distance between the films, FIG. 5 is a cross-sectional view of the film, and FIG. 6 is a diagram showing an example of a process to which the present invention can be applied. 1: Support frame 2: Guide member 3: Side plate 4: Support rod 5A, 5B: Through hole 6: Membrane support plate 7: Notch 8: Plate 9A, 9B: Groove 10: Membrane 12A, 12B: Through hole 13A, 13B: Through hole 14: Permeate passage 15: Nozzle 16: Vinyl hose 17: Water collection pipe 18: Packing 20: Separating plate 21A, 21B: Through hole 22, 23: Packing

Front page continuation (72) Inventor Shigeru Katayama 3-5 Kasumigaseki, Chiyoda-ku, Tokyo Mitsui Petrochemicals Ltd. (72) Inventor Hikoki Kanayama 1-1-4 Yurakucho, Chiyoda-ku, Tokyo Japan Aqua In PEX Co., Ltd. (72) Inventor Akira Sakazaki 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Japan Aquapex Co., Ltd. (72) In Hitoshi Yano 5-6-4 Tsukiji, Chuo-ku, Tokyo Mitsui Shipbuilding Engineering Co., Ltd. In-house (56) References JP-A-52-75667 (JP, A)

Claims (1)

(57) [Claims] 1. A flat membrane type ultrafiltration machine in which an undiluted solution is passed between parallel flat membranes and separated into a permeate and a concentrated solution, wherein the flat membrane is a membrane support plate having corrugated irregularities. A flat membrane ultrafilter having a fixed structure, wherein the flat membrane has a space of 2 mm to 6 mm, and the space of the flat membrane is a space held by the thickness of the packing.