JPH0464727B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a hollow fiber membrane filter useful as a filter for ultrafiltration or reverse osmosis.

[Technical background of the invention and its problems] Hollow fiber membranes have a fine ring shape in cross section, can increase the membrane area within a unit volume, and have excellent pressure resistance, so they can be used for various membrane separations. Widely used in equipment.

By the way, in such hollow fiber membranes, as the filtration time passes, fine particles to be treated adhere to and concentrate on the membrane surface, and the filtration performance gradually decreases.
There were problems such as insufficient recovery (discharge from the processing device) of the fine particles captured and concentrated on the membrane surface.

To deal with these problems, gas or liquid is introduced from the inside of the hollow fiber membrane and permeates from the inside to the outside of the membrane surface, and a large number of air bubbles are directed from the outside of the hollow fiber membrane toward the hollow fiber membrane. A method for backwashing a hollow fiber membrane filter has been developed, in which the liquid in the container containing the hollow fiber membrane is spouted out and the liquid in the container is stirred, thereby removing particulates attached to the membrane surface.

However, as shown in FIG. 1, conventional hollow fiber membrane filters have a module 2 in which a large number of hollow fiber membranes are folded back in a U-shape with both ends facing upward, and the base 3 of the module is fixed with a seal. In addition, the side portion and lower end are collectively supported by a substantially U-shaped support body 4, and the seal portion 5 is tightly fixed to the side surface to be housed in the storage container.

Therefore, in a hollow fiber membrane filter having such a structure, the liquid is not sufficiently introduced into the inside of the module 2, and the liquid in this part is not stirred and vibrated sufficiently, so the above method prevents the liquid from adhering to the membrane surface. There was a problem in that the backwashing effect for removing the particles was not very effective.

[Objective of the Invention] The present invention has been made to solve these drawbacks, and provides a hollow fiber membrane filter that has high backwashing efficiency due to bubble jetting and has excellent filtration characteristics and discharge performance of backwash liquid. The purpose is to

[Summary of the Invention] That is, the present invention fixes the base of a module in which a plurality of hollow fiber membranes are bundled with their respective ends facing the same direction with a seal, and is arranged parallel to the module. The module is supported by a main support that supports the outer part, and a lower support that is attached to the main support and supports the non-focusing end of the module with a hollow part provided in the center thereof. This is a hollow fiber membrane filter characterized by:

In the hollow fiber membrane filter of the present invention, the non-convergent end (folded end) of the module is supported with a sufficient void inside thereof, so that it is not disturbed by lifting of the hollow fiber membrane, etc. A sufficient amount of liquid is introduced into this cavity without causing a flow, and since the liquid in this area is agitated and vibrated by ejecting bubbles, etc., the liquid adheres to the surface of the hollow fiber membrane located inside the module. Fine particles are also effectively exfoliated and removed, dramatically improving backwashing efficiency. Also,
Since the treatment liquid is evenly introduced into the module, the amount of filtration through each cycle is improved compared to the conventional method.

Furthermore, in the present invention, it is preferable that the support is made of plastic made of carbon, hydrogen, and oxygen atoms, and in this case, the support can be incinerated together with the hollow fiber membrane, reducing waste. This has the advantage that it can be made more compact.

[Embodiments of the Invention] Examples of the present invention shown in the drawings will be described below.

FIG. 2 shows a front view of one embodiment of the invention. In this figure, reference numeral 6 indicates a hollow fiber membrane module, which is composed of a large number of hollow fiber membranes 7 that are folded back and bundled into a U-shape with both ends facing upward, and the upper base is sealed and fixed with an adhesive. has been done. Reference numeral 8 indicates a sealed portion using adhesive.

Further, inside the lower non-focusing end of the module 6, a lower support 9 having a cylindrical body with an elliptical cross section as shown in FIG. 3 is attached to a main support 10 that supports the sides. The structure is such that a gap corresponding to the cylindrical interior of the lower support body 9 is secured.

Next, a processing liquid filtration and backwashing device shown in FIG. 4 was constructed using the hollow fiber membrane filter having such a structure, and the filtration characteristics and backwashing efficiency were specifically measured.

That is, as the hollow fiber membrane 7, a module 6 made of polyethylene with a length of 70 cm is bundled and folded back into a U-shape and the base part is sealed and fixed, and a main support 10 of the above-mentioned shape made of polyethylene is used. The sample was housed in the storage container 11 while being supported by the lower support member 9, and the following operations were performed.

First, as a stock solution, amorphous Fe colloid and α
- Prepare a mixed solution of Fe ₂ O ₃ colloid (PH 6.7 to 6.9, conductivity 1 to 5 μS/cm) and transfer it to stock solution tank 12.
After sufficiently stirring and mixing using the stirrer 13, the valve 16 was closed, the valves 14 and 15 were opened, and the mixture was supplied into the storage container 11. The temperature of the stock solution at this time was 25°C±1°C.

The storage container 11 is filled with the undiluted solution, and the undiluted solution comes out into the overflow tank 17 through the valve 15. Close the valve 15, open the valves 19 and 20 while checking the flow meter 18, and adjust the valve 21. The stock solution was filtered at a predetermined flow rate.

In this filtration step, the Fe colloid in the stock solution supplied into the storage container 11 is completely blocked and captured on the outer surface of the hollow fiber membrane 7, and the filtrate passes through the hollow fiber membrane 7 and collects in the filtrate reservoir 22. , through valves 19 and 20 and collected in a filtrate tank 23. Moreover, at this time, as the Fe colloid was captured by the hollow fiber membrane, the filtration pressure difference (pressure loss) gradually increased.

In this way, the stock solution is processed for 60 minutes at a predetermined flow rate, and valves 14, 19 and 1 are closed.
5 was opened, and air whose pressure was regulated to 3 kg/cm ² was introduced from the pressurized air tank 25 into the filtrate reservoir 22 of the storage container 11. The compressed air pushed out the filtrate in the filtrate reservoir 22 and a small amount of the filtrate from the hollow fiber membrane 7 in a direction opposite to the filtration direction, and then backwashed with compressed air for 20 minutes. At the same time, the valve 26 was opened to blow compressed air from the bubble generating nozzle 27 to the lower part of the hollow fiber membrane 7 at a flow rate of 10 N/min for 20 minutes. As a result, a large number of bubbles of 2 to 5 mmφ were generated from the bubble generating nozzle 27 and rose in the stock solution in the storage container 11, vigorously stirring the stock solution and also vibrating the hollow fiber membrane 7.

After continuing this backwashing for 20 minutes, valves 24, 19, 2
6 to stop the supply of compressed air, then close valve 16
was opened and the concentrated liquid containing the iron colloid peeled off from the hollow fiber membrane 7 was discharged into the concentrated liquid tank 28.

After that, close the valve 16 again, open the valve 14,
The stock solution was introduced into the storage container 11, and when the stock solution came out into the overflow tank 17 through the valve 15, the valve 15 was closed, and the valves 19 and 20 were opened to perform the filtration process.

Repeat this cycle of filtration and backwashing multiple times, and calculate the backwashing efficiency (the amount of Fe colloid removed by backwashing in that cycle divided by the amount of Fe colloid captured in that cycle) for each cycle. It was measured. The results are shown in FIG. In FIG. 5, the horizontal axis shows the test cycle, and the vertical axis shows the backwashing efficiency for each cycle, and the black circles indicate the case of this example.

Further, in each cycle, the differential pressure across the hollow fiber membrane 7 after the filtration treatment and after the backwashing treatment was measured using pressure gauges 29 and 30 to determine the filtration differential pressure. The results are shown in FIG. 6 as a solid line. In FIG. 6, the horizontal axis represents the operating time, and the vertical axis represents the filtration pressure, and the black circles indicate the case of this embodiment.

Note that the white circles in FIGS. 5 and 6 indicate cases in which filtration and reverse filtration are performed in the same manner using a hollow fiber membrane filter in which the module 6 is supported in the conventional manner using the lower support 9 without providing a void. This figure shows the results of the washing process.

As is clear from the measurement results shown in Figure 5, the hollow fiber membrane filter of the example has much higher efficiency of backwashing due to bubble ejection than the conventional hollow fiber membrane filter, and always maintains a value close to 100%. It shows.

In addition, the measurement results shown in Figure 6 indicate that the hollow fiber membrane filter of the example has a lower rate of increase in filtration differential pressure than conventional filters, and that the filtration differential pressure recovers better after backwashing. Recognize.

Therefore, according to the hollow fiber membrane filter of the example,
It can be seen that a large amount of filtration can be achieved per cycle (the filtration operation time between washings can be extended).

In addition, in the above embodiment, a structure in which a cylindrical support was fitted to the lower non-focusing end of the module to secure a void was described, but the hollow fiber membrane filter of the present invention has such a structure. The structure is not limited, and for example, as shown in FIG. 7, an annular lower support 9 may be inserted through each folded end of the hollow fiber membrane 7 to support the lower end of the module 6.

[Effects of the Invention] As is clear from the above examples, the hollow fiber membrane filter according to the present invention is excellent in filtration characteristics, backwashing efficiency by blowing out bubbles, and dischargeability of backwashing liquid.

Therefore, with this hollow fiber membrane filter, the amount of filtration per cycle is increased compared to conventional filters, and not only the operating time is extended, but also the life of the hollow fiber membrane itself is extended.

[Brief explanation of the drawing]

Fig. 1 is a front view of a conventional hollow fiber membrane filter, Fig. 2 is a front view of an embodiment of the present invention, and Fig. 3 is a front view of a conventional hollow fiber membrane filter.
FIG. 4 is a piping system diagram showing the filtration and backwashing device using the hollow fiber membrane filter of the example, and FIGS. 5 and 6 are graphs showing the effects of the example. , FIG. 7 is a bottom view of another embodiment of the present invention. 6...Module, 7...Hollow fiber membrane, 8...Seal portion, 9...Lower support, 10...Main support,
12... Storage container, 13... Stock solution tank, 17...
... Overflow tank, 22 ... Filtrate reservoir, 23
...filtrate tank, 25 ...pressurized air tank, 27
... Bubble generating nozzle, 28 ... Concentrate tank.

Claims (1)

[Scope of Claims] 1. Seal-fixing the base of a module in which a large number of hollow fiber membranes are bundled with both ends facing in the same direction, and the outer part of the module is disposed parallel to the module. The module is supported by a main support that supports the module, and a lower support that is attached to the main support and supports the non-focusing end of the module with a hollow part provided in its center. Hollow fiber membrane filter. 2. Claim 1, wherein the support is a plastic composed of carbon, hydrogen, and oxygen atoms.
Hollow fiber membrane filter as described in .