JPH02157006A - Two stage type filtration method and filtration column by use of filament bundle - Google Patents

Abstract

PURPOSE:To provide filtration method and a filtration column by which the quality of filtrated liquids can be raised as high as possible by conducting filtration by means of a second filament bundles composed of an assembled body of fine monofilaments. CONSTITUTION:Raw liquids flow down along first filament bundles 4 which are disposed vertically in a column 1, whereby suspended matters are captured in the void formed by the first filament bundles 4, while the filtered liquids flow into a supporting body 3 of filament bundle from a hole 21 of an upper cover body 22 and flow out from a first filtrated liquid outlet line 8 through a lower cylindrical body 24. the filtrated liquids then flow downwardly into a rear stage filtration column 10 through the line 8 and flow down along second filament bundles 11 disposed vertically in the column 10, whereby the remaining suspended matters are captured in the void formed by the bundles 11, while the filtrated liquids are taken out through a supporting body 3 of filament bundle and a second filtrated liquid outlet pipe 12.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to earthwork tap water, sewage, river water, lake water, coagulation sedimentation supernatant water, various industrial intermediate waters, and various recovered waters such as recovered water in paper manufacturing processes. A filtration method using long fiber bundles made of aggregates of single fibers to remove suspended matter in various wastewaters, treated water from biological treatment equipment, liquids containing valuables, alcohol, oil, etc., at high flow rates. The present invention relates to a filtration tower, and particularly relates to a two-stage filtration method using two types of long fiber bundles having different single fiber diameters, and a filtration tower.

<Prior Art> The applicant of the present invention previously disclosed a filtration tower using long fiber bundles in Japanese Patent Application No. 1.46989/1982 and Japanese Patent Application No. 131715/1983.

As shown in Figure 4, this filter tower has a perforated plate (b) placed horizontally on the filter tower (a), and a long fiber bundle (c) is placed on the perforated plate (b).
A long fiber bundle (c) is installed throughout the interior of the filtration tower (a) with the lower end fixed and the lower end free. Then, open the valve (BO) and let the stock solution flow in from the stock solution inflow pipe (C), pass the stock solution in a downward flow to the long fiber bundle (C), and trap the suspended matter in the voids of the long fiber bundle. Then, the filtrate is taken out from the filtrate outflow pipe (G).

In addition, when the pressure loss increases due to the capture of suspended matter, the valve (
At the same time, close valves (d) and (e), open valves (ch) and (w), and let compressed air flow in from the air inflow pipe (n) to stir and vibrate the long fiber bundle (c), and then compress it. Either with air flowing in or by stopping the inflow and opening the valve, backwash water flows in through the backwash water inlet pipe (W) and suspended matter flows out through the backwash water outflow pipe (W). be.

The filtration tower usually has a long fiber bundle of 0.4 m to 3 m in length, which is an aggregate of non-twisted single fibers such as acrylic fibers, polyester fibers, and polyamide fibers, with a thickness of IOμ to 80μ. Since it is made upright by being packed tightly, suspensions can be filtered at a high flow rate without significantly increasing pressure loss.

In addition, since the lower end of the long fiber bundle is fixed, when high-flow compressed air or backwash water flows upward during backwashing, the long fiber bundle becomes like a windsock with the lower part fixed. Since the long fiber bundle vibrates as it stretches, trapped suspended matter can be effectively removed.

By the way, the thickness of each single fiber in the long fiber bundle used is determined by the concentration of suspended matter in the stock solution or the degree to which the quality of the filtrate is to be improved, but the thickness of the single fiber used is determined by the pressure drop. There is the following relationship regarding the increase in filtrate and the quality of filtrate.

In other words, when a fiber bundle, which is an aggregate of relatively thin single fibers, is used, the quality of the filtrate improves, but because the fibers themselves are weak, the fiber bundles become less erect as suspended matter is captured during filtration. In particular, the fiber bundles become more compacted in the lower part of the filtration tower, leading to a rapid rise in pressure loss, which shortens the filtration time and, in some cases, leads to insufficient cleaning. ing.

On the other hand, when a long fiber bundle, which is an aggregate of relatively thick single fibers, is used, the fibers themselves are strong, so compaction of the fiber bundle does not occur as much, the rise in pressure loss is slow, and the filtration time is long. However, it has the disadvantage that the quality of the filtrate decreases.

Therefore, it has been difficult to meet the demands of increasing the quality of the filtrate as much as possible and increasing the filtration time.

<Problems to be Solved by the Invention> The present invention solves the above-mentioned problems using long fiber bundles, and provides long fiber bundles that can improve the quality of the filtrate as much as possible and extend the filtration time. The object of the present invention is to provide a filtration method and a filtration tower using the same.

<Means for Solving the Problems> The filtration method according to the present invention, which has been made to achieve the above object, fixes the lower end of the long fiber bundle inside the tower, and sets the upper end as a free end to The stock solution is introduced from one side of the filtration tower, which has long fiber bundles erected throughout, and is passed from the top end of the long fiber bundles to the bottom end, thereby trapping suspended matter in the voids within the long fiber bundles. In the filtration method, after filtration is performed with a first long fiber bundle consisting of an aggregate of single fibers,
This is a two-stage filtration method using a long fiber bundle, characterized in that filtration is performed with a second long fiber bundle made of an aggregate of single fibers that are thinner than the single fibers used in the first long fiber bundle.

Further, the invention described in the second claim is the second aspect of the present invention described above.
This relates to a filtration tower that allows the stage filtration method to be carried out at low cost.The lower end of the long fiber bundle is fixed inside the tower, and
With the upper end as a free end, the stock solution is introduced from above the filtration tower in which long fiber bundles are set upright throughout the inside of the tower, and the stock solution is passed from the top end of the long fiber bundles toward the bottom end, thereby making it possible to remove the In a filtration tower that captures suspended matter in the voids, a first long fiber bundle made of an aggregate of single fibers is formed in the upper stage of the tower, and the first long fiber bundle is used in the lower stage of the first long fiber bundle. forming a second long fiber bundle consisting of an aggregate of single fibers that are thinner than the single fibers used;
2 using a long fiber bundle characterized in that the stock solution is consistently passed through the first long fiber bundle and the second long fiber bundle.
It is a stage filtration tower.

The present invention will be explained in detail below.

FIG. 1 is an explanatory diagram showing an example of an embodiment of the method of the present invention, in which two filtration towers using long fiber bundles are arranged in series.

That is, a perforated plate 2 is installed horizontally in the lower part of the front-stage filtration tower 1, and a support 3 for a long fiber bundle, which will be described later, is attached to the perforated plate 2.
The lower end of the first long fiber bundle 4 is fixed by the support 3, and the second end of the first long fiber bundle 4 is made a free end. ,
The long fiber bundle 4 is set up in the front filtration tower 1.

Further, a stock solution inflow pipe 5 is communicated above the first stage filtration tower 1, and a backwash water discharge pipe 6A is branched and communicated with the stock solution inflow pipe 5.

Further, a backwash air inflow pipe 7A is communicated with the lower part of the perforated plate 2, and a first filtrate outflow pipe 8 is connected to the lowermost end of the filtration tower 1.
A backwash water flow pipe 9A is branched and communicated with the first filtrate outflow pipe 8.

A rear filtration tower 10 is installed at the rear of such a front filtration tower 1, a perforated plate 2 is installed horizontally in the lower part of the latter filtration tower 10, and a support 3 for long fiber bundles is placed on the perforated plate 2. attachment,
The lower end of the second long fiber bundle 11 is fixed by the support 3, the upper end of the second long fiber bundle 11 is set as a free end, and the long fiber bundle 11 is relatively densely packed in the column 10, so that The long fiber bundle 11 is also set up in the filter tower 10 .

Further, the other end of the first filtrate outflow pipe 8 is communicated with one side of the latter stage filtration tower 10, and a backwash water discharge pipe 6B is branched and communicated with the outflow pipe 8.

Further, in the same way, a backwash air inflow pipe 7B branched from the backwash air inflow pipe 7A is communicated below the perforated plate 2, and a second filtrate outflow pipe 12 is communicated with the lowest end of the filtration tower 10. A backwash water inflow pipe 9B branched from the backwash water inflow pipe 9A is communicated with the second filtrate outflow pipe 12.

Note that 12 to 20 each indicate a valve.

The support body 3 for the long fiber bundle used in the first stage filtration tower 1 and the second stage filtration tower 10 has the following structure.

That is, as shown in FIG. 2, the support body 3 includes an upper lid-like body 22 having a large number of holes 21 in the upper and side body parts, and a lower cylindrical body 24 having open upper and lower ends and having slits 23 in the side body parts. When attaching the support 3 to the perforated plate 2, first insert the 1-shaped bolt 25 into the lower cylindrical body 2.
4, and the lower cylindrical body 24 is attached to the T-shaped port 25.
hang it up.

Next, insert the tip of the one-shaped bolt 25 from the lower part of the perforated hole 26 of the perforated plate 2, insert the upper part of the lower cylindrical body 24 into the hole 26, and then screw the nut 28 having the leg 27 into the T-shaped port 25. Fix the 1-shaped bolt 25 in the hole 26 by using the following steps.

Next, the lower end of the first long fiber bundle 4 or the second long fiber bundle 11 is fixed around the entire circumference of the side trunk of the upper lid-like body 22 using the hand 29, and the long fiber bundle 4 (
11) is fixed by person 3.
0 through the T-shaped bolt 25, cover the hole 26 of the perforated plate 2 with the upper lid-shaped body 22, and then insert the nut 31 into the T-shaped port 25.
By screwing into the hole 26, the upper lid-like body 22
to be fixed.

Both the first long fiber bundle 4 and the second long fiber bundle 11 are composed of aggregates of single fibers, but the most important point of the present invention is that the thickness of the single fibers used in both long fiber bundles is different. It is.

That is, as the first long fiber bundle 4, a long fiber bundle which is an aggregate of non-twisted single fibers with a thickness of 20 to 80 μ made of synthetic fibers such as acrylic fibers, polyester fibers, and polyamide fibers is used, and the second long fiber bundle As the bundle 11, a long fiber bundle is used, which is an aggregate of non-twisted single fibers made of the synthetic fibers having a thickness of 1 to 43 μm, which are thinner single fibers than the single fibers used in the first long fiber bundle 4.

In the present invention, as described above, the thickness of each single fiber used in the first long fiber bundle 4 and the second long fiber bundle 11 is changed, and the thickness of the latter single fiber is made thinner than that of the former single fiber, but both What is the thickness of the single fiber of the undiluted solution? , 8? It is preferable to use within the above-mentioned range depending on the amount of FA, the quality of the filtrate, etc. For example, use single fibers with a thickness of 35 to 43μ as the first long fiber bundle, and use thick fibers as the second long fiber bundle 11. It is preferable to use single fibers with a diameter of about 14 μm.

<Effect> The present invention will be explained in detail below.

When filtering stock solutions containing suspended matter, valve 12.16
．． 20 is opened, and the stock solution first flows downward into the pre-stage filtration tower 1 from the stock solution inlet pipe 5.

The raw solution flows down along the first long fiber bundle 4 installed vertically in the tower 1, suspended matter is captured in the void formed by the first long fiber bundle 4, and the filtrate flows into the upper lid-shaped body 22. The long fiber bundle enters the inside of the support 3 through the hole 21 , and then flows out from the first filtrate outflow pipe 8 via the lower cylindrical body 24 .

By such filtration in the pre-stage filtration tower 1, most of the suspended matter in the stock solution is filtered by the first long fiber bundle 4.

Next, the filtrate flows down from the first filtrate outflow pipe 8 into the latter stage filtration tower 10, flows down along the second long fiber bundle 11 installed upright in the tower 10, and is filtered by the second long fiber bundle 11. The remaining suspended matter is captured in the formed voids, and the filtrate is similarly taken out from the long fiber bundle support 3 and the second filtrate outflow pipe 12.

The long fiber bundle 11 used in the second stage filtration tower 10 has a thinner single fiber diameter than the long fiber bundle 4 used in the first stage filtration tower 1. The substances are reliably captured in the second-stage filtration tower 10, and a high-quality filtrate is obtained from the second-stage filtration tower 10. In addition, in the above-mentioned filtration, aluminum sulfate, P
There is no problem in adding a flocculant such as AC1 polymer a-flocculant.

If the pressure loss in both filtering towers increases due to the continuation of such filtration (however, in the normal case, the pressure loss in the first stage! passing tower 1 increases first), the following backwashing is performed.

That is, valve 12.16.20 is closed, valve I7.18 is opened, and compressed air flows in from backwash air inlet pipe 7B.

Since the lower part of the perforated plate 2 is filled with filtrate, a portion of the filtrate initially flows out from each member 21 of the neck-shaped body 22 due to the inflow of compressed air, but soon the filtrate flows under the perforated plate 2. As shown in Figure 2, a liquid level is formed and a compressed air layer A is formed above the liquid level. The compressed air enters the lower cylindrical body 24 through the slit 23 located above the liquid level, and then blows out from each member 21 of the upper lid-shaped body 22.

Due to the inflow of the compressed air, the water in the latter stage filtration tower 10 is stirred and the long fiber bundles 11 are vibrated, the voids formed between the fibers are destroyed, and the aggregate of suspended matter is destroyed. The suspended matter adhering to the long fiber bundle 11 is peeled off.

In particular, at the initial stage of the inflow of compressed air, the liquid present below the porous plate 2 is pushed up by the compressed air at once and becomes a powerful piston flow, which is effective in removing suspended matter.

Continue the inflow of compressed air as described above, or close valve 1.
8 to stop the inflow of compressed air, and open the valve 19 to allow backwash water to flow in from the backwash water inflow pipe 9B.

The inflowing backwash water mainly enters into the cylindrical body 24 from the lower end opening of the lower cylindrical body 24, and then flows out from each person 21 of the upper lid-shaped body 22.

Since the lower end of the long fiber bundle 11 is fixed and the upper end is free, the long fiber bundle 11 becomes like a windsock and stretches due to the upward flow of backwash water, and each fiber vibrates. do. Therefore, the suspended matter separated from the long fiber bundle 11 due to the shock caused by the inflow of the compressed air is washed away, and the backwash water containing the suspended matter is sent to the backwash water discharge pipe 6.
It flows out from B.

In addition to the above-mentioned method, the backwashing procedure involves injecting a certain amount of backwashing water from the backwashing water inflow pipe 9B, and
There is also a method of intermittently inflowing compressed air from the backwash air inflow pipe 7B. In this case, each time compressed air flows in, the piston flow with the above-mentioned force is generated, so that backwashing can be suppressed more effectively.

When the above-described backwashing of the latter filtration tower 10 is completed, or in parallel with the backwashing, the first filtration tower 1 is backwashed.

The backwashing of the front-stage filtration tower 1 is basically the same as the backwashing of the rear-stage filtration tower 10 described above, and compressed air is introduced from the backwash air inflow pipe 7A by opening and closing the valves 13, 14 or 15. Also, backwash water flows in from the backwash water inflow pipe 98, and backwash water flows out from the backwash water discharge pipe 6A.

After completing the backwashing of both columns as described above, the above-described filtration is performed again.

The flow shown in Figure 1 is as follows:
Although two towers are used in series, the filtration method of the present invention can also be carried out using one tower.

FIG. 3 is an explanatory diagram of the flow of another embodiment of the present invention, in which the method of the present invention is carried out in one column.

That is, perforated plates 52A and 52B are installed horizontally at approximately the center and lower parts of the filter tower 51, respectively, and the perforated plates 52A and 52
A support body 53 of a long fiber bundle similar to that shown in FIG. The upper ends of bundles 54 and 60 are free ends;
By filling the side long fiber bundles 54 and 60 relatively densely in the tower 51, the double cast fiber bundles 54 and 60 are set up.

Further, a stock solution inflow pipe 55 is communicated above the filtration tower 51, and a backwash water discharge pipe 56A is branched and communicated with the stock solution inflow pipe 55.

Furthermore, a backwash air inflow pipe 57A is communicated between the lower part of the perforated plate 52A and the second long fiber bundle 60, and a backwash water discharge pipe 56B is also communicated.

In addition, a backwash air inflow pipe 57B is connected to the lower part of the perforated plate 52B, and a filtrate outflow pipe 58 is connected to the lowermost end of the filtration tower 51, and a backwash water flow pipe 59 is branched to the filtrate outflow pipe 58. Communicate.

Note that 61 to 67 each indicate a valve.

Both the first long fiber bundle 54 and the second long fiber bundle 60 used in the filtration tower shown in FIG. 3 are composed of aggregates of single fibers, but the thickness of the single fibers used in both cast fiber bundles is different. .

That is, the first long fiber bundle 54 uses long fibers made of an aggregate of single fibers having a thickness of 20 to 80 μm, for example, as in the case of the first stage filtration tower in the flow shown in FIG. 1, and the second long fiber bundle 60 is As in the case of the latter stage filtration tower in the frame LJ- of FIG. 1, long fibers made of an aggregate of single fibers thinner than the single fibers used for the first long fiber bundle 54, for example, having a thickness of 1 to 43 μm, are used.

When filtering suspended matter in the filter tower, valve 61.
67 is opened, and the stock solution flows downward from the stock solution inflow pipe 55, and is caused to flow down consistently to the first long fiber bundle 54 and the second long fiber bundle 60. In addition, also in the case of this filtration, a flocculant can be added to the stock solution if necessary.

The stock solution flows down along the first long fiber bundles 54 that are installed upright, and
Most of the suspended matter is captured in the voids formed by the long fiber bundles 54, and then the filtrate of the first long fiber bundles 54 flows down along the second long fiber bundles 60 standing upright at the lower stage. Residual suspended solids are captured in the voids formed by the long fiber bundles 60,
Filtrate is obtained from filtrate outlet tube 58 .

Further, backwashing performed after filtration may be performed separately for the first long fiber bundle 54 and the second long fiber bundle 60, or may be performed for both cast fiber bundles at the same time.

That is, for the former type of backwashing, valves 65 and 64 are opened and the other valves are closed, compressed air is introduced from the backwash air inflow pipe 57B, and then valve 66 is opened and the backwash water flow pipe 5
9, backwash water flows in from the second long fiber bundle 60 to flow out from the backwash water discharge pipe 56B, then valves 63 and 62 are opened and other valves are closed, and the backwash air inflow pipe 56B is opened. Compressed air flows in from 57A, then valve 66 is opened, backwash water flows in from backwash water outflow pipe 59, and backwash wastewater from the first long fiber bundle 54 flows out from backwash water discharge pipe 56A. It is.

For the latter backwashing, valves 65 and 62 are opened and the other valves are closed, and compressed air is flowed in from the backwash air inflow pipe 57B to uniformly flow into the second long fiber bundle 60 and the first long fiber bundle 54. compressed air flows in and simultaneously stirs the remanufactured fiber bundle,
Next, the valve 66 is opened to allow backwash water to flow in from the backwash water flow pipe 59 to wash the remanufactured fiber bundles at the same time, and the backwash water is discharged from the backwash water discharge pipe 56A.

Note that for both the former and latter backwashing methods, compressed air may be intermittently introduced while backwashing water is introduced.

The filtration tower shown in Fig. 3 has long fiber bundles arranged in two stages in one tower, so unlike the flow shown in Fig. 1, two stages of filtration can be performed in one tower, and the number of columns is It is possible to reduce the number of pipes and valves, reduce installation costs, and reduce the installation area.

Next, to explain the long fiber bundle used in the filtration tower shown in Fig. 1 or 2, even if the stock solution is passed down at a relatively high flow rate, the long fiber bundle has a long length at the initial stage. The lower part of the fiber bundle bends slightly and its height shrinks slightly, and as the liquid continues to flow, the bent part of the lower part increases, and the height of the upright long fiber bundle gradually decreases. The long fiber bundles do not bend horizontally and remain upright as a whole during the passage of liquid in the filtration tower, so it is necessary to have sufficient strength and filling volume. Synthetic fibers or natural fibers such as cotton and wool can be used.

These synthetic fibers or natural fibers are usually aggregates of non-twisted single fibers, and the thickness of the single fibers is usually 20 to 80μ in the case of the first long fiber bundle, and In this case, usually 1 fiber is thinner than the thickness of the single fiber used in the first long fiber bundle.
~43μ single fibers are used.

Further, the length of the first long fiber bundle is usually 1 to 3 m, and the length of the second long fiber bundle is usually 0.4 to 2 m.

<Effects> - As explained above, the present invention filters the first long fiber bundle and the second long fiber bundle in two stages in series, and the thickness of the single fibers used in the second long fiber bundle is the same as that of the first long fiber bundle. Since it is thinner than the thickness of the single fibers used in the fiber bundle, it has the following effects.

In other words, in the first stage filtration section using the first long fiber bundle, as long as most of the suspended matter in the stock solution is removed, there is no problem even if some suspended matter leaks from the filtration section. By using the first long fiber bundle, which is an aggregate of fibers, even if filtration is performed for a long period of time, the pressure loss will not increase significantly, and in the latter stage filtration section using the second long fiber bundle, the former stage filtration section will not increase. Since most of the suspended solids have been removed,
By using a long fiber bundle, which is an aggregate of relatively thin single fibers, a filtrate of good quality can be obtained without significantly increasing pressure loss.

Therefore, according to the present invention, it is possible to achieve the objectives of improving the quality of the filtrate and increasing the filtration time, which could not be achieved with conventional long fiber filtration.

Examples will be described below to make the effects of the present invention more clear.

Example diameter: 650mm, height: 4. OOOmn (straight section) stainless steel filtration tower bottom and middle section (2,0 mm from the bottom)
00m position), two perforated plates are installed horizontally, upper and lower, and the upper layer has a thickness of 43μ, a length of 1,600++m, and a packing density of 100kg.
The lower end of the first long fiber bundle consisting of an aggregate of acrylic non-twisted single fibers of /m is fixed, and the lower end has a thickness of 14 μm and a length of 60 μm.
A filtration tower as shown in FIG. 3 was constructed by fixing the lower end of a second long fiber bundle made of an aggregate of non-twisted acrylic single fibers with a packing density of 50 kg/% and having a free upper end. . From above the filter tower, 5■/7!
suspension to which PAC (polyaluminum chloride) was added (
SS)? Once the industrial water containing 5 ■/l is transported at a downward flow velocity of 7
When water was passed through at 5 m/h, the suspended solids concentration was 0.05 mg/h.
A filtered water of 7+ (SP I value -1,4) was obtained.

In addition, after 8 hours of water flow, the differential pressure was 0.5 kg /
cnl (initial differential pressure 0.3 kg/cnl), water flow was terminated, and then compressed air with an upward linear flow rate of 1,00 ONrrr/d was supplied from the bottom of the filtration tower for 1 minute, and then compressed air (1, 000Nrd/rrr) and 10(1m/H
of backwashing water for 3 minutes, then 1 minute of backwashing water of 100ml/l (100ml/l) for 1 minute, 14t for the first long fiber bundle and the second long fiber bundle.
When the filtration tower was backwashed, the pressure difference in the filtration tower returned to the initial pressure difference, the suspended matter trapped in the long fiber bundles could be completely removed, and the condition of the filtration surface could be restored.

On the other hand, for comparison, one stage of perforated plate was placed horizontally at the bottom of a filtration tower with the same diameter and height as used in the example. A filtration tower (Comparative Example-1) in which the lower end of a long fiber bundle made of an aggregate of non-twisted single fibers was fixed, and a perforated plate placed horizontally at the bottom of a filtration tower having the same diameter and height as those used in the example. set, thickness 14μ,
An example in which the same amount of PAC was added to each of the filtration towers (Comparative Example-2) in which the lower ends of long fiber bundles made of aggregates of acrylic non-twisted single fibers having a length of 2.2 m and a packing density of 50 kg/rf were fixed. The downward flow velocity of industrial water is 75 m/+
- (When water was passed through the filter, in Comparative Example-1, it was possible to pass water for 10 hours until the differential pressure reached 0°5 kg/cnt, but the suspended solids concentration in the filtrate water was 0.2 mg/j2,
In addition, in Comparative Example-2, the suspended matter concentration in the filtrate water was 0.0
5■/β, but the differential pressure decreased to 0.5k within just one hour.
g/cnl.

[Brief explanation of the drawing]

Figures 1, 2, and 3 all show embodiments of the present invention, and Figure 1 is an explanatory diagram showing the flow when filtration towers are arranged in a two-bath row. FIG. 3 is an enlarged sectional view showing a support for long fiber bundles used in the present invention, and FIG. 3 is an explanatory diagram showing a flow when long fiber bundles are arranged in two stages in one tower. FIG. 4 is an explanatory diagram showing the flow of a conventional long fiber bundle. DESCRIPTION OF SYMBOLS 1... Front stage filtration tower 2... Porous plate 3... Support body for long fiber bundle 4... First long fiber bundle 5... Stock solution inflow pipe 6...
- Backwash water discharge pipe 8... First filtrate outflow pipe 9... Backwash water flow pipe 11... Second long fiber bundle 21... Hole 23... Slit 25... T-shape Bolt 27...Leg 29...Tightening by hand 31...Nand 51...Filtering tower 53...Support for long fiber bundle 54...First long fiber bundle 56...Backwashing Water discharge pipe 58...Filtrate outflow pipe 60...Second long fiber bundle 7...Backwash air inflow pipe 10 Later stage filtration towers 12-20...Valve 22...Upper lid-shaped body 24... ... Lower cylindrical body 26 ... Hole 28 ... Nut 30 ... Take-out hole 52 ... Perforated plate 55 ... Stock solution inflow pipe 57 ... Backwash air inflow pipe 59 ...・Backwash water inflow pipes 61 to 67...Valves Figure 3 Figure 4

Claims (1)

[Claims] 1. The lower end of the long fiber bundle is fixed inside the tower, and the upper end is set as a free end, and the raw solution is introduced from above the filtration tower in which the long fiber bundle is set upright throughout the inside of the tower. , in a filtration method in which suspended matter is captured in the voids within a long fiber bundle by passing the stock solution from the upper end to the lower end of the long fiber bundle, filtration is performed using a first long fiber bundle consisting of an aggregate of single fibers. A two-stage filtration method using a long fiber bundle, characterized in that the second long fiber bundle is made of an aggregate of single fibers thinner than the single fibers used in the first long fiber bundle. 2. The lower end of the long fiber bundle is fixed inside the tower, and the upper end is set as a free end, and the raw solution is introduced from above the filtration tower in which the long fiber bundle is installed vertically throughout the inside of the tower, and the upper end of the long fiber bundle is fixed. In a filtration tower that traps suspended matter in the voids in the long fiber bundle by passing the raw solution from the filtrate toward the lower end, a first long fiber bundle consisting of an aggregate of single fibers is formed in the upper stage of the tower, and the first long fiber bundle is formed in the upper stage of the tower. A second long fiber bundle consisting of an aggregate of single fibers thinner than the single fibers used in the first long fiber bundle is formed in the lower stage of the first long fiber bundle, and the stock solution is applied to the first long fiber bundle and the second long fiber bundle. A two-stage filtration tower using long fiber bundles, characterized in that the liquid is passed through the tower consistently.