JPH07185268A - Hollow fiber filter membrane element and module - Google Patents

Abstract

PURPOSE:To enhance the recovery of filtering capacity due to air scrubbing to a large extent and to also enhance maintenance properties, in a hollow fiber membrane element wherein an air introducing pipe is formed at the central part of hollow fiber membrane bundles, by forming introduced air jet orifices from the outside of the element to the lower part below the half of the total length of the element of the pipe. CONSTITUTION:In a hollow fiber membrane filter element 2 composed of an external pressure system passing raw water through hollow fiber membrane bundles 21 from the outside of hollow fiber membranes to the inside thereof to filter the same to take out transmitted water from the single ends of the hollow fiber membrane bundles 2 and having an air introducing pipe formed at the central part of the hollow fiber membrane bundles 21 thereof, introduced air jet orifices 25 from the outside of the element are formed to the lower part below the half of the total length of the element of the pipe. As a result, in the hollow fiber membrane filter element filtering a liquid containing fine particles or a suspended substance and a module, the recovery of filtering capacity due to air scrubbing is enhanced to a large extent. Especially, the effect at a time when air jet orifices are arranged in the hollow fiber membrane bundles by an air dispersing pipe or plate is large. Maintenance properties are also enhanced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to hollow fiber filtration membrane elements and modules for performing liquid filtration operations.

[0002]

2. Description of the Related Art General industrial water contains many SS components, fine particles, dust, bacteria, algae, etc. If used as it is, clogging of water pipes, bacterial growth, It is likely to cause problems such as scale accumulation in the line. Conventionally, various methods such as sand filtration, coagulation filtration, coagulation-precipitation treatment, and cartridge filter filtration have been used in order to remove these water-mixed components, depending on the application. As a new method replacing these general filtration methods, filtration using a porous hollow fiber membrane has recently been put into practical use. The water treatment and filtration using hollow fiber membranes have rapidly spread in recent years, and the fields of application thereof are also expanding year by year.

In the filtration of hollow fiber membranes, the hollow fiber membranes are processed into a hollow fiber membrane element having a shape in which thousands to tens of thousands are bundled into a bundle and the ends are fixed with an adhesive. Then, these elements are housed in a module container and processed into a product form are called a hollow fiber filtration membrane module or simply a module. Many types of hollow fiber filtration membrane modules capable of filtering liquid have been proposed in the past. In particular, the initial ones include a filtration module used in combination with an appropriate pretreatment means, seven for reverse osmosis filtration, and one for dialysis use. Many of these are mainly used for these uses. The module forms have been proposed, and the main ones thereof are, for example, Japanese Patent Publication No. 48-28380 and Japanese Patent Laid-Open No. 49-69550.
JP-A No. 53-100176, and the like. All of these were usually disposed of, or washed with clear water or chemical water or flushed at a stage where a certain amount or more of dirt adhered.

On the other hand, recently, a method has been tried in which the hollow fiber filtration membrane module shape is devised so that the adhered substances on the hollow fiber membrane surface are regularly removed by air to recover the performance of the hollow fiber membrane. Has been. JP-A 61-263605
Japanese Patent Laid-Open Publication No. 2005-242242 discloses a U-shaped hollow fiber membrane that is housed in a container for use. Periodically, air is introduced from an air inlet provided at the bottom of the container to scrub the hollow fiber membrane. To try to remove the deposits on the film surface. Further, JP-A-60-206415 is a both-end fixed type module in which hollow fiber membranes are arranged around a central pipe, which is incorporated in a container in the same manner as described above.
The deposit on the hollow fiber membrane surface is removed by air scrubbing. The practical application of these technologies has already started.

Further, Japanese Patent Laid-Open No. 48-34763 discloses a method in which fine particles adhering to a film are separated by compressed air and then backwashed with a filtrate or another liquid.

[0006]

In the water treatment by the hollow fiber filtration membrane module, it is a good method to remove the deposits on the surface of the hollow fiber membrane by air scrubbing or backwashing. By removing (washing) the deposit, the state before filtration can be almost restored, the filtration performance is also almost restored, and the life of the hollow fiber filtration membrane module is extended, which is economical. However, in the conventional air scrubbing, most of the types in which air is ejected only from the lower part of the module container, and in this method, especially when the diameter of the hollow fiber bundle becomes large, bubbles do not enter the inside of the hollow fiber bundle, It only removed the deposits near the surface of the yarn bundle. As an example of ejecting air from a portion other than the lower part of the module container, a method using a perforated air pressure feeding pipe having a large number of holes over its entire length has been devised, as in Japanese Utility Model Laid-Open No. 3-15627. However, especially when the total length of the module becomes long and the difference in water pressure between the upper part and the lower part of the module is large, air is pierced from the hole in the upper part of the pneumatic feed pipe to the part where air is accumulated in the upper part of the module. There was also a problem that almost no bubbles that are important for cleaning can be generated. In addition, the washed deposits are likely to accumulate near the air ejection port at the bottom of the module container, and the air ejection port is clogged, and the hollow fiber membrane cannot be sufficiently cleaned.
For this reason, there has been a demand for a module that can sufficiently clean the entire hollow fiber membrane bundle of the element and that does not clog the air ejection port.

[0007]

An object of the present invention is an external pressure type for filtering raw water from the outside of a hollow fiber membrane bundle to the inside of the hollow fiber and a method of taking out permeated water from one end. A hollow fiber membrane element having an air introduction pipe in the center, and having an introduction air jet port from the outside of the element below 1/2 of the total length of the element. Is basically achieved by

In the hollow fiber filtration membrane element and module of the present invention, one of physical cleaning of the hollow fiber filtration membrane element
Since the air jet for air scrubbing, which is one of the two, is provided in the yarn bundle, compared to the conventional air scrubbing from the bottom of the element, the film can be efficiently shaken to the inside of the yarn bundle. The recovery of the filtration performance has been greatly improved. In addition, since the air outlet is provided in the element that is regularly replaced, it is only necessary to replace the element periodically to deal with clogging of the air outlet, contributing to improved maintainability of the membrane treatment device. To do.

The present invention will be described below in detail with reference to the drawings, but the present invention is not limited to these drawings.

FIG. 1 shows an example of a module in which the element of the present invention, which is a hole formed in the vicinity of the lower end plate of an air introduction pipe having an air ejection port at the center, is incorporated in a module container. Claim 5
An air ejection port at the lower part of the module container described in 1. is also provided. The module container 1 has a removable cap so that the element can be easily replaced.
The element is incorporated in the container via a sealing material. Further, a raw water supply port 11 for supplying raw water to the module container, a drain port 12 for discharging the liquid in the module container,
An air vent 13, a permeate port 14, an air inlet 15 communicating with the air inlet pipe of the element, and a module container lower air inlet 16 used when air scrubbing from the lower part of the module container is used together are installed. The hollow fiber membrane element 2 is housed in the module container.

In the hollow fiber membrane element, one end or both ends of the hollow fiber bundle 21 are fixed with an adhesive. FIG. 1 shows an example of a hollow fiber membrane element with both ends fixed, but there is a lower end plate 22 and an upper end plate 23, and one end plate has a hollow fiber hole so that permeated water can be taken out. It has become. In the example of FIG. 1, the hollow fiber is opened in the upper end plate.
Further, the upper end plate and the lower end plate are connected by an air passage pipe 24, and the air passage pipe is airtightly connected to the air inlet of the module container.

In the example of FIG. 1, the hole formed in the lower portion of the air introduction pipe 24 is the air jet port 25, but the air jet port may be a slit shape instead of the hole of the example of FIG. .

Further, as shown in FIGS. 2 and 3, it may be provided in an air dispersion pipe branched from the air introduction pipe. The air dispersion pipe is connected to the air introduction pipe substantially vertically, but may be slightly deviated from the vertical as long as the effect of the present invention is not impaired. Further, the connected position is preferably below 1/4 of the total length of the element.

The number and length of the air dispersion tubes are not particularly limited, but the number is 2 or more, more preferably 3 or more, and further preferably 4 or more. Alternatively, when the hollow fiber membrane is divided into several membrane bundles, the number is preferably the same as the number of the hollow fiber membrane bundles or an integral multiple thereof. The length is preferably 1/2 or more of the element radius. This is because it is preferable that the air ejection port is located around ½ of the element radius.

Alternatively, it may be provided inside the lower end plate as shown in FIGS. 4 and 5, or may be provided on the air dispersion plate installed in the air introduction pipe as shown in FIGS. 6 and 7. . The air dispersion plate referred to here has the same outer shape as a bundling plate that bundles the hollow fiber membrane bundles, but has an air ejection port on the surface from which the air conducted from the air introduction pipe is It has a structure that erupts.

The forms are not particularly limited in these examples. In addition, in the drawings of FIGS. 2, 3, 4, and 5, the air ejection port is located at a portion between the hollow fiber membrane bundles where there is no hollow fiber, but the air ejection port is provided near the inside of the hollow fiber membrane bundle. It can be installed.

FIG. 8 shows an example in which the air inlet is located in the lower portion of the module container, and the air inlet pipe is airtightly connected to the air inlet in the lower portion of the module container. Others are the same as the example of FIG.

FIG. 9 shows an example in which the present invention is applied to an element for taking out one end in which a hollow fiber membrane is incorporated in a U shape.

The hollow fiber filtration membrane element used here filters raw water through innumerable fine pores on the surface of the hollow fiber membrane, and only clear water from which SS components, fine particles, dust, bacteria and the like are removed. It permeates into the hollow fiber membrane and is taken out as filtered water from the filtered water outlet. The hollow fiber membrane element is used not only for such applications as microfiltration and ultrafiltration, but also for dialysis and reverse osmosis of substances through hollow fiber membranes, and for mass transfer between liquids and gases in addition to mass transfer between liquids. Use,
There are a wide variety of types and applications, including applications for mass transfer between gases. Usually, in filtration of a hollow fiber filtration membrane element, the larger the raw water pressure, the larger the filtration water amount, but with the passage of filtration time, the SS components, fine particles, etc. adhere to the membrane surface and the hollow fiber membrane is clogged more or less. It is usual that the amount of filtered water per the same pressure gradually decreases. Therefore, at an appropriate time when the amount of filtered water decreased due to the progress of clogging of the hollow fiber membrane, a washing operation such as backwashing or air scrubbing was performed, and the filtered water amount of the hollow fiber membrane was brought to a level close to that before clogging. Will need to be recovered.

The method of using the module incorporating the hollow fiber filtration membrane element is not limited and can be set according to the user's wish. As an example of the operating method, an operating method of changing the amount of filtered water while keeping the pressure constant,
Examples of the method include a method of operating while keeping the amount of filtered water constant while controlling the pressure automatically or manually, and a method of connecting the module to an appropriate source of raw water and operating the pressure as it is.

The inventors of the present invention have found out the present invention as a result of earnestly investigating a method of improving the membrane cleaning efficiency by air scrubbing and the module maintainability in cleaning the hollow fiber filtration membrane element.

The hollow fiber filtration membrane element and module of the present invention may be of any type as long as they are filtration elements using a bundle of porous hollow fiber membranes as a filtering material. The preferred shape of the hollow fiber filtration membrane element is a structure in which a hollow fiber membrane is opened by cutting both ends of a bundle of a large number of hollow fiber membranes with an adhesive and cutting one end of this adhesive seal portion. Usually, it is housed inside the module container as an element built-in type. As an assembling method, the element and the container are assembled via a sealing material, and a container built-in type in which the element can be arbitrarily removed from the container is preferable, but adopt a structure in which the element and the container are integrally bonded with an adhesive or the like. You can also

The hollow fiber membrane material constituting the hollow fiber filtration membrane element used in the present invention is not particularly limited as long as it is a porous hollow fiber membrane, but polyethylene, polypropylene, polysulfone, polyether sulfone, polyvinyl alcohol, Cellulose acetate, polyacrylonitrile, and other materials can be selected. Among them, as a particularly preferable hollow fiber membrane material, a hollow fiber membrane made of a polymer containing at least one component of acrylonitrile is suitable from the viewpoint of having sufficient mechanical strength against air scrubbing. The most preferable acrylonitrile-based polymer is at least 50 mol% or more of acrylonitrile, preferably 60 mol% or more and 50% or less of one or more vinyl compounds having copolymerizability with the acrylonitrile. Is an acrylonitrile polymer composed of 0 to 40 mol%. Further, a mixture of two or more kinds of these acrylonitrile-based polymers and further another polymer may be used. The vinyl compound may be any known compound having copolymerizability with acrylonitrile, and is not particularly limited, but preferable copolymer components include acrylic acid, itaconic acid, methyl acrylate, methyl methacrylate, Examples thereof include vinyl acetate, sodium allyl sulfonate, sodium p-styrene sulfonate, and the like.

The next preferable hollow fiber material is
It is composed of one or more kinds of olefin polymers such as ethylene propylene or 4-methylpentene, and has a hollow fiber membrane shape with a major axis of 0.1 to 10 μm and a minor axis of 0.0.
Those having slit-shaped pores of 1 to 1.0 μm are suitable.

[0025]

【Example】

Example 1 As a hollow fiber membrane element of the present invention, an outer diameter of 470 μm,
Both ends of a hollow fiber membrane consisting of 20,000 polyacrylonitrile porous hollow fiber membranes with an inner diameter of 350 μm and an average pore size of 0.01 μm are fixed with urethane adhesive together with an air introduction pipe having an air ejection port, and then the adhesive is fixed. A hollow fiber membrane was opened by cutting one end of the part. This element was subjected to a filtration experiment using a hollow fiber filtration membrane module housed in a module container having a diameter of 17 cm and a length of 120 cm.

In the filtration experiment, raw water prepared by adding 5 ppm of polyaluminum chloride (PAC) to lake water was used, and the flow rate in the filtration process was adjusted to 8 liters / minute by automatically adjusting the pressure. Even if the element is clogged, the pressure rises according to the degree and a predetermined flow rate is maintained. Further, when the supply pressure reached 1.0 kgf / cm ² , backwashing with permeated water, air scrubbing from the air introducing pipe and the lower part of the module were performed, and after draining, the cycle of returning to normal operation was repeated. In this experiment, it was possible to smoothly filter even after 1000 hours, and the hollow fibers did not adhere to the inside of the hollow fiber bundle or near the lower end plate of the hollow fiber bundle due to deposits.

Example 2 An example except that a hollow fiber membrane element was used in which the air ejection holes were provided on an air dispersion pipe vertically connected to the air introduction pipe as shown in FIGS. 2 and 3. The same experiment as in 1 was performed. In this experiment, as in the case of Example 1, it was possible to smoothly pass through 1000 hours, and the accumulation of dirt on the hollow fiber membrane bundle near the lower end plate was more effective than that of Example 1 due to the effect of the air dispersion pipe. There were few.

Comparative Example 1 The hollow fiber filtration membrane element, raw water, and operating conditions were the same as in the example, and air was supplied only from the lower part of the module during air scrubbing as in the conventional element, and from the air jet port of the element. Did not supply. It was found that, after 1000 hours had passed since the start of the experiment, the hollow fiber bundle was fixed due to deposits inside the hollow fiber membrane bundle, particularly near the lower end plate, and the effective membrane area was reduced.

[0029]

EFFECTS OF THE INVENTION According to the present invention, recovery of filtration performance by air scrubbing is significantly improved in a hollow fiber filtration membrane element and module for filtering a liquid containing fine particles and suspended substances. In particular, the effect is great when the air jets are arranged in the hollow fiber membrane bundle with an air dispersion pipe or an air dispersion plate. Further, a hollow fiber filtration membrane element and module having improved maintainability are provided.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an example of a module in which a hollow fiber filtration membrane element including an element air introduction pipe of the present invention and an air ejection unit is incorporated in a module container.

FIG. 2 is a cross-sectional view of an example of a module in which a hollow fiber filtration membrane element having an air dispersion pipe of the present invention is incorporated in a module container.

FIG. 3 is a vertical cross-sectional view of the vicinity of an air ejection port of an example of a module in which a hollow fiber filtration membrane element having an air dispersion pipe of the present invention is incorporated in a module container.

FIG. 4 is a transverse cross-sectional view of an example of a module in which a hollow fiber filtration membrane element having air ejecting means on a lower end plate of the present invention is incorporated in a module container.

FIG. 5 is a vertical cross-sectional view around an air ejection port of an example of a module in which a hollow fiber filtration membrane element provided with air ejection means on a lower end plate of the present invention is incorporated in a module container.

FIG. 6 is a cross-sectional view of an example of a module in which a hollow fiber filtration membrane element including an air dispersion plate of the present invention is incorporated in a module container.

FIG. 7 is a vertical cross-sectional view in the vicinity of an air ejection port of an example of a module in which a hollow fiber filtration membrane element having an air dispersion plate of the present invention is incorporated in a module container.

FIG. 8 is a vertical cross-sectional view of an example of a hollow fiber filtration membrane module provided with air ejection means at the bottom of the module container of the present invention.

FIG. 9 is a vertical cross-sectional view of an example in which the present invention is applied to a module in which a U-shaped hollow fiber membrane element is incorporated in a module container.

[Explanation of symbols]

 1: Module container 2: Hollow fiber membrane element 11: Raw water supply port 12: Drainage port 13: Air vent port 14: Permeate water port 15: Air inlet port 16: Module lower air inlet port 21: Hollow fiber membrane bundle 22: Lower end Plate 23: Upper end plate 24: Air introduction pipe 25: Air jet

Claims (6)

[Claims] 1. An external pressure type for filtering raw water from the outside of a hollow fiber membrane bundle into the inside of a hollow fiber and a method of taking out permeated water from one end, wherein an air introduction pipe is provided at the center of the hollow fiber membrane bundle. A hollow fiber membrane element, which is a hollow fiber membrane element having an introduction air jet port from the outside of the element below ½ of the total length of the element. 2. The hollow fiber filtration membrane element according to claim 1, wherein the air ejection port is a hole provided on the lower surface of the air introducing pipe. 3. The hollow fiber filtration membrane element according to claim 1, wherein the air jet port is provided on an air dispersion plate or an air dispersion pipe which is substantially vertically connected to the air introduction pipe. . 4. The hollow fiber filtration membrane element according to claim 1, wherein the lower end plate is provided with air jetting means, and the air jetting means is airtightly connected to the air introducing pipe. 5. The module according to claim 1, which is incorporated in a module container having a raw water outlet, an air vent, a drainage outlet, a permeate outlet, and an air inlet through a sealing material. A characteristic hollow fiber filtration membrane module. 6. The hollow fiber filtration according to claim 5, wherein an air ejection port is provided in the lower portion of the module container, and scrubbing air can be ejected from both the element and the lower portion of the module container during air scrubbing cleaning. Membrane module.