JP3249094B2 - Hollow fiber membrane module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow fiber membrane module, and more particularly to a hollow fiber membrane module suitable for filtering a highly turbid (particularly organic turbid) liquid.

[0002]

2. Description of the Related Art Conventionally, hollow fiber membrane modules have been constructed using sterile water,
It has been widely used in the field of so-called microfiltration, such as the production of drinking water and high-purity water, and the purification of air. Various studies have been made for use in water treatment applications.

[0003] However, the hollow fiber membrane modules used in these fields are also of a cylindrical type in which hollow fiber membranes converged and arranged in a circular shape or concentric circles used in the field of conventional microfiltration. Was the most.
Even if improvements are made, there are many that only change the filling rate or filling form of the hollow fiber membrane.

[0004]

However, when such a conventional hollow fiber membrane module is used to filter high-polluting water (for example, SS ≧ 50 ppm, TOC ≧ 100 ppm), it is difficult to use the filter. The hollow fiber membranes are fixed (adhered) to each other through deposits such as organic substances attached to the surface of the hollow fiber membrane, thereby reducing the effective membrane area of the hollow fiber membrane in the module. A sharp decrease in the filtration flow rate was observed. In particular, this phenomenon was remarkable in the hollow fiber membrane at the center of the cylindrical module, and was more remarkable in a larger module.

[0005] In addition, even when the hollow fiber membrane module in which the hollow fiber membranes are fixed and integrated as described above is periodically cleaned and backwashed, the function of the module once fixed and integrated can be easily recovered. Instead, the cleaning efficiency was reduced.

An object of the present invention is to provide a hollow fiber membrane in a module that is difficult to be fixed and integrated even when used for filtration of highly polluted water, and that the module has a means for supplying air bubbles during backwashing. The recovery process of the reduced filtration function is easy,
An object of the present invention is to provide a hollow fiber membrane module that can be implemented efficiently.

That is, the present invention relates to a hollow fiber membrane module in which at least one end of the hollow fiber membrane is fixed by a fixing member while keeping its end in an open state. In addition to being configured as an aggregate of small bundles fixed in a state close to each other, a hydrophobic hollow fiber membrane and a hydrophilic hollow fiber membrane are provided as hollow fiber membranes, and are perpendicular to the hollow fiber membrane of the fixing member. A hollow fiber membrane module characterized in that the cross-sectional shape is elongated and substantially rectangular.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The hollow fiber membrane module of the present invention will be described below in more detail with reference to the drawings.

FIG. 1 is a perspective view showing an example of the hollow fiber membrane module of the present invention, and FIG. 2 is a sectional view thereof. The hollow fiber membrane module of the present invention basically includes a housing 1
And a fixing member 2 and two types of hollow fiber membranes 3. In addition to these, various accessory members such as the dispersing means 4 may be provided.

The housing 1 functions as a member for supporting the entire hollow fiber membrane module, and has an elongated, substantially rectangular opening. Any material may be used as long as it has mechanical strength and durability. For example, polycarbonate, polysulfone, polypropylene, acrylic resin, ABS
Resin, modified PPE resin and the like are exemplified. If incineration is required after use, it is preferable to use a hydrocarbon resin that can be completely burned without emitting toxic gas by combustion.

The opening of the housing 1 is required to have a shape in which the cross section perpendicular to the hollow fiber membrane of the fixing member filled and fixed with the hollow fiber membrane therein is elongated and substantially rectangular. The length of the short side of this rectangle is preferably 30 mm or less, particularly preferably 15 mm or less. As described above, by developing the arrangement mode of the hollow fiber membranes as a flat sheet, the entire hollow fiber membrane bundle is fixedly integrated into one rod shape, and the effective membrane area of the hollow fiber membrane rapidly decreases. Can be prevented. Even if the hollow fiber membranes are fixed to each other, the thickness of the fixing portion of the hollow fiber membrane is small, and the fixing state can be easily recovered because the hollow fiber membrane is provided in a sheet shape. In addition,
The length of the long side of the rectangle is not particularly limited. However, if the length is too short, the number of hollow fiber membranes that can be arranged in one hollow fiber membrane module decreases, which is not preferable. It is not preferable. Usually, the length of the long side is about 100 to 2000 mm.

The fixing member 2 is filled and fixed in the opening of the housing 1, and converges and fixes each end of the large number of hollow fiber membranes 3 while maintaining the open state. It functions as a member that partitions the water to be treated and the treated water in a liquid-tight manner. The fixing member 2 is usually formed by curing a liquid resin such as an epoxy resin, an unsaturated polyester resin, and polyurethane.

As the hollow fiber membrane 3, two types of hydrophobic hollow fiber membrane and hydrophilic hollow fiber membrane are used, and these are disposed in the same module. Various materials can be used as the material of the hydrophobic hollow fiber membrane and the hydrophilic hollow fiber membrane, and for example, those made of cellulose, polyolefin, polyvinyl alcohol, PMMA, polysulfone, and the like can be used. However, in consideration of the ease of processing into a knitted fabric, a material having a high strength and elongation such as polyethylene is preferable. The pore diameter, porosity, film thickness, outer diameter and the like are not particularly limited as long as they can be used as a filtration membrane.

As the hydrophilic hollow fiber membrane, either a primary hydrophilic membrane or a permanent hydrophilic membrane can be used, but a so-called permanent hydrophilic membrane having a hydrophilic group or the like on its surface is desirable.
Known methods such as a method for producing a hollow fiber membrane with a hydrophilic polymer such as polyvinyl alcohol or a method for hydrophilizing the surface of a hydrophobic polymer membrane can be used as a method for producing a permanent hydrophilic membrane. For example, examples of the hydrophilic polymer when a hydrophilic polymer is applied to the membrane surface to hydrophilize the hydrophobic hollow fiber membrane include:
Examples thereof include saponified ethylene-vinyl acetate copolymers and polyvinylpyrrolidone. As an example of the film surface hydrophilization by another method, there is a film surface polymerization method of a hydrophilic monomer, and examples of the monomer include diacetone acrylamide. As another method, there can be mentioned a method of spin-forming a film by blending a hydrophilic polymer with a hydrophobic polymer (for example, polyolefin). Examples of the hydrophilic polymer to be used include those described above. Can be

In order to store the hollow fiber membrane 3 in the elongated, substantially rectangular opening of the housing 1, it is necessary to use a laminate in which several knitted fabrics are formed by using the hollow fiber membrane as, for example, warps. It is suitable. In the case of the conventional cylindrical module, there was no difficulty in storing the hollow fiber membranes that had been skeined and bundled in the cylindrical housing. However, it is difficult to store the skeined hollow fiber membrane in the elongated rectangular opening,
The knitted fabric can be easily stored. When laminating knitted fabrics of hollow fiber membranes, hollow fiber membrane knitted fabrics having different performances can be used. For example, when a hollow fiber membrane module is produced by sandwiching a knitted fabric of a hydrophobic hollow fiber membrane with a knitted fabric of a hollow fiber membrane subjected to hydrophilic treatment and sandwiching the knitted fabric, a hydrophobic hollow fiber membrane layer is formed. Can be used as a means for supplying bubbles during backwashing.

Instead of using several knitted fabrics stacked, a knitted fabric in which a hollow fiber membrane knitted fabric is folded elongated in a zigzag shape (arranged in a meandering shape) may be used. By employing this storage method, it is possible to prevent uneven placement of the hollow fiber membrane in the fixing member when the filling density of the hollow fiber membrane is relatively low.

In the hollow fiber membrane module of the present invention,
The hollow fiber membranes are preferably bundled in a U-shape, and the U-shaped hollow fiber membrane is preferably configured as an aggregate of small bundles of the hollow fiber membranes. Here, the small bundle means a collection of hollow fiber membranes satisfying the following conditions. That is,
In the hollow fiber membrane included in one small bundle, the two fixing portions corresponding to the base of the U-shape are fixed in a state in which the fixing members are close to each other (preferably within 1 cm ² ), and Easily bundled (aligned) with the hollow fiber membrane belonging to the bundle
However, other hollow fiber membranes in the vicinity of the hollow fiber membranes belonging to other small bundles are in a state in which it is difficult to focus and bundle. More specifically, when only the hollow fiber membrane wound and converged on one skein is housed in one housing and fixed, all the hollow fiber membranes in the module are contained in the same bundle. Will be. On the other hand, for example, when this is housed and fixed in a housing using a hollow fiber membrane knitted fabric using ten plied hollow fiber membranes as wefts,
The whole of the previously bundled hollow fiber membranes constitutes one bundle, and the number of hollow fiber membranes contained in one bundle is 10
It becomes a book.

Therefore, when the U-shaped hollow fiber membrane is configured as an aggregate of small bundles of hollow fiber membranes, the hollow fiber membranes are bundled for each small bundle and this is bundled with another small bundle. Since the hollow fiber membrane module can be easily separated from the body, forced uniform dispersion and fixation of the hollow fiber membrane can be easily performed when using the hollow fiber membrane module. The number of hollow fiber membranes included in one of the small bundles depends on the thickness of the hollow fiber membrane, but is preferably 100 or less, more preferably 50 or less.

The method for producing the hollow fiber membrane module of the present invention is not particularly limited, but the following method is preferred. First, a knitted fabric using a hollow fiber membrane as a weft as shown in FIG. 3 is prepared. The specific method is described in, for example, JP-A-62-57965,
It is disclosed in 266258. Several sheets obtained by cutting the sheet-shaped knitted fabric into appropriate lengths are laminated. Here, the term “lamination of knitted fabric” also includes a fabric obtained by folding and knitting a knitted fabric to an appropriate length without cutting it. The number of layers (folding) of the knitted fabric varies depending on the thickness of the knitted fabric, that is, the thickness of the hollow fiber membrane and the number of hollow fiber membranes when knitting the knitted fabric. It is preferable that the fixing member be configured so as to satisfy the limitation on the length of the short side of the rectangular cross section of the fixing member. One side of this knitted laminate is housed in a housing having an elongated, substantially rectangular opening, and the housing is hardened and fixed with a liquid resin (hereinafter referred to as potting). Cut the cured resin so that it appears. In addition, as described above, a knitted fabric using a hollow fiber membrane as a weft may be folded into a zigzag shape to form a folded knitted fabric, and one side of the folded knitted fabric may be stored in the opening of the housing. In manufacturing a hollow fiber membrane module, a method utilizing centrifugal force is generally employed as a method for filling a liquid resin without gaps between hollow fiber membranes. However, when a hollow fiber membrane is potted in a housing having an elongated rectangular opening, a large and special shape such as a bucket used for centrifugal potting is required. Therefore, it is preferable to use potting using the vibration method described below, which is less affected by the size and shape of the housing. That is, the knitted fabric of the hollow fiber membrane is housed in a housing, and the housing is filled with a liquid resin. At that time, as in the case of the conventional method for manufacturing a hollow fiber membrane module, it is necessary to seal the end portion of the hollow fiber membrane bundle and perform processing so that the liquid resin does not enter the hollow portion of the hollow fiber membrane. Needless to say. Liquid resin is
Those having a viscosity of about 1000 to 2500 centipoise are optimal. While the liquid resin has fluidity,
The housing containing the hollow fiber membrane bundle and the liquid resin is mechanically vibrated to uniformly fill the resin. Its frequency is
Although about 500 to 12000 cycles are appropriate, vibration in the ultrasonic range may be applied. Details of the potting by the vibration method are disclosed in JP-A-3-114515. By using this potting method, the liquid resin is uniformly dispersed in the housing, and peeling between the hollow fiber membrane and the cured resin (fixing member) and leakage of the filtration fluid at the fixing member are prevented. The cutting of the end face after the liquid resin has hardened (the formation of the open end of the hollow fiber membrane) and the like can be performed according to a general hollow fiber membrane module processing method.

In the use of the hollow fiber membrane module of the present invention, a so-called pressure filtration method in which the module is disposed in a closed vessel and the water to be treated is pressurized to allow the hollow fiber membrane to permeate can be employed. It is preferable to dispose a hollow fiber membrane module in a tank or a settling tank or the like, and to use the module by a suction filtration method in which a side for collecting treated water permeated through the hollow fiber membrane is suctioned. In particular, by adopting a so-called intermittent suction operation method in which temporary suction is periodically stopped, it is possible to efficiently prevent the membrane surface deposits from entering the inside of the membrane surface, and to recover the function of the hollow fiber membrane module. Processing frequency can be reduced.

The water to be treated in the suction filtration method is made to flow almost perpendicularly to the direction in which the hollow fiber membrane is arranged (the direction of the fiber axis), so that the effect of cleaning the membrane surface of the hollow fiber membrane is improved. Is preferred.

As one of preferred uses of the hollow fiber membrane module of the present invention, each of the small bundles 5 of the hollow fiber membrane described above is provided with a dispersing means 4 for expanding and holding and fixing each of the U-shaped tops. An embodiment shown in FIG. 4 in which filtration is performed while holding is exemplified. At that time, the U-shaped top temporary fixing 6 by the warp at the time of forming the hollow fiber membrane knitted fabric is utilized as it is,
The mode shown in FIG. 5 in which the character-shaped top is engaged with the dispersing means 4 is simple and preferable. Of course, the warp during knitting of the knitted fabric for temporary fixing may be removed from the hollow fiber membrane module. The dispersing means 4 may be provided separately from the hollow fiber membrane module, or may be provided integrally with the hollow fiber membrane module. Further, the dispersing means is not limited to the hook-shaped one as shown in the figure, and may be a rod-shaped one having a partition distribution plate, or may have a number of strings, and tie the U-shaped top with this string. It may be fixed. By disposing this dispersing means, even if the hollow fiber membrane module of the present invention is used for filtering highly polluted water, a high degree of dispersibility of the hollow fiber membrane can be maintained for a longer period of time.

Further, as one preferable method of using the hollow fiber membrane module of the present invention, there is a method of arranging this module on a rotating body and performing filtration while rotating the module. As a method of attaching the module to the rotating body, the module housing is arranged so as to extend radially in the horizontal direction around the rotating body, and the hollow fiber membrane is hung downward from each housing, or is arranged vertically. There is a mode in which housings of a plurality of modules are arranged so as to be oriented in the vertical direction with the provided rotating body as an axis, and the hollow fiber membranes extend radially in the horizontal direction from each of the modules.

The hollow fiber membrane module of the present invention is particularly suitable for filtration of highly polluted water. Specific application fields include filtration of river water, filtration of industrial water, solid-liquid separation of sewage, and wastewater treatment ( For example, treatment in a combined septic tank).

As a method for recovering the function of the hollow fiber membrane module of the present invention, a backwashing method can be easily carried out similarly to the case of a normal module. By sending, bubbles for cleaning the hollow fiber membrane module can be generated from the hydrophobic hollow fiber membrane. Further, as another function recovery processing method, a method of physically cleaning the film surface using a sponge ball or the like, or a method using ultrasonic waves or the like can be efficiently performed due to the physical form of the module.

[0026]

According to the hollow fiber membrane module of the present invention, since more hollow fiber membranes are in direct contact with the water to be treated, the accumulation of organic substances between the hollow fiber membranes is suppressed, and the solidification between the hollow fiber membranes is achieved. In particular, high filtration efficiency can be maintained over a long period of time in filtration of highly polluted water. In addition, since the hydrophobic hollow fiber membrane functions as a means for supplying air bubbles at the time of back washing, the filtration function recovery processing by washing can be efficiently performed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a hollow fiber membrane module of the present invention.

FIG. 2 is a cross-sectional view of the module of FIG.

FIG. 3 is a plan view showing a hollow fiber membrane knitted fabric suitable for use in manufacturing the hollow fiber membrane module of the present invention.

FIG. 4 is a perspective view showing an example of a method for using the hollow fiber membrane module of the present invention.

FIG. 5 is a partially enlarged view showing an example of a use state of the hollow fiber membrane module of the present invention.

FIG. 6 is a diagram showing a wastewater treatment flow when the hollow fiber membrane module of the present invention is used for wastewater treatment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Fixing member 3 Hollow fiber membrane 4 Dispersing means 5 Small bundle 6 Temporary fixing 7 Hook

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Akira Hoshide 2-3-1 Kyobashi, Chuo-ku, Tokyo Inside Mitsubishi Rayon Co., Ltd. (56) References JP-A-60-232208 (JP, A) 61-106306 (JP, U) Actually open 1987-87702 (JP, U) Actually open 60-171511 (JP, U) Actually open 60-171509 (JP, U) Actually open 60-171508 (JP, U) U) Fully open sho 60-171507 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 1/00-71/82 510 C02F 1/44

Claims (2)

(57) [Claims] At least one end of a hollow fiber membrane is fixed by a fixing member while its end is kept open.
A hollow fiber membrane module, wherein the hollow fiber membrane is
As a set of small bundles fixed in close proximity
In addition, a hydrophobic hollow fiber membrane and a hydrophilized hollow fiber membrane are provided as hollow fiber membranes, and the shape of a cross section perpendicular to the hollow fiber membrane of the fixing member is elongated and substantially rectangular. Hollow fiber membrane module. 2. The method according to claim 1, wherein the small focusing body is 1 cm
^2. The method according to claim 1, wherein the fixing means is fixed in a state of being close to each other within the range of ^2.
Onboard hollow fiber membrane module.