WO2004054692A1

WO2004054692A1 - Hollow fiber membrane module combined with air diffuser

Info

Publication number: WO2004054692A1
Application number: PCT/KR2003/002743
Authority: WO
Inventors: Hun-Hwee Park
Original assignee: Hun-Hwee Park
Priority date: 2002-12-14
Filing date: 2003-12-13
Publication date: 2004-07-01
Also published as: KR100544383B1; KR20040052192A; AU2003286946A1

Abstract

A hollow fiber membrane module combined with air diffusers comprises: a) a hollow fiber membrane (15); b) a lower structure including an air or oxygen inlet (7-a), air diffusers (1-a, 1-b) each formed with air or oxygen discharge holes (2) and hitched in a U-shape with hollow fiber membrane (15) in a U-shape, lower connectors (4-a, 4-b) each connecting a strut and the air diffusers, and legs (6); c) an upper hollow fiber membrane distribution structure (9) for dispersedly arranging distal ends of bundles of the hollow fiber membranes; d) a head (12) for sealing the upper hollow fiber to membrane distribution structure (9) and the hollow fiber membrane (15), and equipped with a filtered water outlet (13); and e) struts (8-a, 8-b) for connecting the upper hollow fiber membrane distribution structure (9) and the lower structure. The hollow fiber membrane combined with air diffusers is provided such that, when installed in a biological treating reactor, air or oxygen bubbles generated from air or oxygen discharge holes at the air diffusers of the hollow fiber membrane module directly clean the hollow fiber membrane (15) to prevent occurrence of impurities, thereby enabling to maintain a good permeation efficiency for a long period of time.

Description

HOLLOW FIBER MEMBRANE MODULE COMBINED WITH AIR DIFFUSER

FIELD OF THE INVENTION The present invention relates to a hollow fiber membrane module, which is deposited in a biological treating reactor for filtering and discharging only treated water except for solids containing an activated sludge. More particularly, the present invention relates to a hollow fiber membrane module combined with air diffusers, where hollow fiber membranes discharge treated water free of impurities or pollutant materials attached to the surface of the hollow fiber membrane when a hollow fiber membrane module filters and discharges treated water in a biological treating reactor.

A lower structure of the hollow fiber membrane module provided in the present invention is disposed with air diffusers containing holes for discharging air or oxygen, and hollow fiber membranes, each formed in a U-shape and hitched around the air diffusers, are directly cleansed by the air or oxygen discharged from the holes at the air diffusers.

In other words, the present invention provides a hollow fiber membrane module combined with air diffusers whereby hollow fiber membranes, hitched around the air diffusers and sealed to an upper distribution structure of hollow fiber membranes module, vibrate in a lateral direction to minimize the impurities attached to the hollow fiber membranes, thereby enabling to maintain a protracted permeation efficiency. BACKGROUND OF THE INVENTION

There is a problem in a flat membrane module or a hollow fiber membrane module according to the prior art in that activated sludge and other reaction by- products adhere to the surface of a membrane to deteriorate the permeation efficiency and life of the membrane when the membrane module filters and discharges treated water in a biological treating reactor.

In order to combat the aforementioned problem, chemicals such as NaOCl,

NaOH, H₂O and the like have been applied to the membrane module to prevent or inhibit the activated sludge and other by-products from adhering to the surface of the membrane, thereby maintaining the penetration performance of the membrane.

Meanwhile, most of the membrane modules are provided by installing a membrane that corresponds to a proper treatment capacity, and a round or a straight air diffuser is separately applied at the bottom of the membrane for inhibiting the impurities. However, even in most of these cases, there arises a problem in that the aforementioned chemicals are still required for eliminating activated sludge and the other by-products due to a severe occurrence of impurities at the membrane developed over a period of several months.

Meanwhile, a separate round or cylindrical air diffuser is installed at a framed structure in order to cleanse a membrane module and a membrane, giving rise to an increase in the entire volume of the frame. However, this has a drawback in that it is not easy to install a membrane module at a proper position. The present invention is thus disclosed to provide a hollow fiber membrane module integrally formed with air diffusers configured to inhibit the impurities of a hollow fiber membrane to enable to prevent deterioration of penetration efficiency even during a long period of use.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a hollow fiber membrane module integrated with air diffusers for supplying air or oxygen to the bottom surface of the hollow fiber membrane.

In accordance with the object of the present invention, there is provided a hollow fiber membrane module combined with air diffusers, wherein the membrane module comprises: a) hollow fiber membranes (15); b) a lower structure including an air or oxygen inlet (7-a), air diffusers (1-a, 1-b) each formed with air or oxygen discharge holes (2) and hitched with the hollow fiber membranes (15) formed in a U- shape, lower connectors (4-a, 4-b) each connecting a strut and air diffusers, and legs (6); c) an upper hollow fiber membrane distribution structure (9) for dispersedly arranging distal ends of bundles of the hollow fiber membranes; d) a head (12) for sealing the upper hollow fiber membrane distribution structure (9) and the hollow fiber membrane (15) and equipped with a filtered water outlet (13); and e) struts (8-a, 8-b) for connecting the upper hollow fiber membrane distribution structure (9) and the lower structure. The present invention further comprises air diffuser connectors (3-a, 3-b) for connecting distal ends of the air diffusers.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the nature and objects of the present invention, reference should be made to the following detailed description with the accompanying drawings, in which:

FIG.1 shows one embodiment of a lower structure for hollow fiber membrane module according to the present invention;

FIG.2 shows one embodiment of an air or oxygen inlet at air diffusers according to the present invention;

FIG.3 illustrates a front view of an entire structure of a hollow fiber membrane module according to the present invention; FIG.4 shows one embodiment of an upper hollow fiber membrane distribution structure according to the present invention;

FIG.5 shows an upper surface of a head of a hollow fiber membrane module according to the present invention;

FIG 6 illustrates a side view of a hollow fiber membrane module combined with air diffusers according to the present invention;

FIG.7 shows one embodiment of a ventilation system of a hollow fiber membrane module combined with air diffusers according to the present invention; FIG.8 shows a waste water process chart using a hollow fiber membrane module combined with air diffusers according to the present invention;

FIG. 9 is a chart for illustrating a comparative result between a first embodiment and a comparative example; and FIG.10 is a chart for illustrating a comparative result between a second embodiment and a third embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiments of the present invention will now be described in detail with reference to the annexed FIGS. 1 to 8, where the present embodiments are not limiting the scope of the present invention but are given only as illustrative purposes.

The present invention relates to a hollow fiber membrane module integrally combined with air diffusers where bundles of the hollow fiber membranes (15) vibrate in a lateral direction by air or oxygen bubbles (17) generated from the air diffusers (1-a, 1-b), which hitch the U-shaped bundles to thereby minimize pollution of the hollow fiber membranes (15).

Furthermore, in the hollow fiber membranes according to the present invention, the air or oxygen bubbles (17) ascend inside and outside of the hollow fiber membrane module (see FIG. 6) to induce the diffusion of pollutant materials at the surface of the hollow fiber membrane (see FIG. 7) in order to remove the pollutant materials and maintain a prolonged penetration performance. In other words, the present invention provides an air diffuser-integrated hollow fiber membrane module (see FIG. 6), which dispenses with a separate installation of round or cylindrical air diffusers.

The hollow fiber membrane of the present invention may be a commonly used hollow fiber membrane. The hollow fiber membrane according to the present invention, having holes with diameters of 0.1-0.4μm, preferably in the range of 0.2μm, is applied or coated with more than one polymer out of Polyvinylidene Fluoride (PVDF), Polysulfone (PSf), Polyethersulfone (PES), Polypropylene (PP) and Polyethylene (PE) on the surface of hollow fibers constituting PP or PE. Each hollow fiber membrane has a tensile strength of more than 30,000 gf/fil, an external diameter of the membrane being 1.5-2.5 mm, preferably 2.0 mm, and a length of the membrane being 0.5-1.5m. A total number of 500-2000 membranes are used to cover an entire area of 5-15 square meters.

A lower structure of the hollow fiber membrane module includes air or oxygen inlets (7-a, 7-b), air diffusers (1-a, 1-b), legs (6), lower connectors (4-a, 4-b) for connecting a strut and air diffusers which are disposed at two trisected points in the lengthwise direction of the air diffusers.

The lower structure may further include air diffuser connectors (3-a, 3-b) for connecting both tip ends of the air diffusers, if necessary. The air or oxygen inlets may be equipped at the air diffusers or air diffuser connectors, and may be one, two or more in number thereof.

The air diffusers (1-a, 1-b) are disposed with air or oxygen discharge holes and hitched with the hollow fiber membranes (15) formed in a U-shape.

The air diffusers (1-a, 1-b) may be formed into a square or a round shape and are empty therein. The diameter of each air or oxygen discharge hole (2) is preferably in a range of 0.5-4 mm, more preferably 2-3 mm. The size of the hole at one air diffuser may be identical or different.

For example, the hole (2) for generating air or oxygen may gradually grow larger as it is distanced from the air or oxygen inlet. The distance between the air or oxygen discharge holes (2) may be in the range of 1-5 cm. The air or oxygen discharge holes (2) may be equipped at any one or more positions out of vertical and horizontal positions of the air diffusers, and the number of the holes may be in the range of 2-8 between the legs (6).

The amount of air or oxygen generating from the air or oxygen discharge holes (2) is preferably in a range of 0.5-3.5m/h per unit area of the hollow fiber membrane, more preferably in the range of 0.8-2.5m/h.

The lower connectors (4-a, 4-b) each connecting a strut and air diffusers are disposed with lower strut insertion holes (5-a, 5-b) at the lower structure (see FIG. 1).

Struts (8-a, 8-b) may be connected from the lower strut insertion holes (5-a, 5- b) to upper strut insertion holes (10-a, 10-b) of an upper hollow fiber membrane distribution structure (9).

The struts (8-a, 8-b) may be in the form of a round, an oval or a square shape but are recommended to be in the form of a round or an oval shape with each diameter in the range of 1-3 cm. The length of each strut is preferably in the range of 0.2-1 m in consideration of the length of the hollow fiber membrane (15). Meanwhile, the struts may be positioned outside of the hollow fiber membrane module.

The number of hollow fiber membrane distribution holes (11) at the upper hollow fiber membrane distribution structure (9) for dispersibly arranging both ends of the hollow fiber membrane (15) stretched in a U-shape at the air diffusers (1-a, 1-b) is in the range of 6-12. The number of hollow fiber membranes (15) inserted into each distribution hole (11) may be in the range of 100-300.

The upper strut insertion holes (10-a, 10-b) at the upper hollow fiber membrane distribution structure (9) may be disposed at two trisected positions in the lengthwise direction of the upper hollow fiber membrane distribution structure (9).

Furthermore, a head (12) is provided for sealing the upper hollow fiber membrane distribution structure (9), which includes the hollow fiber membranes (15). The head (12) is equipped with a filtered water outlet (13) for discharging the filtered treated water processed by the hollow fiber membranes (15) and is also disposed with frame fixing grooves (14-a, 14-b) for connecting and fixing the hollow fiber membrane module (see FIG. 6) to a frame. The frame fixing grooves (14-a, 14-b) may be equipped at one side of the head or at both sides of the head.

The head (12) for sealing the upper hollow fiber membrane distribution structure (9) and the lower structure (see FIG. 1) are preferably of the same length while the widths thereof are of the same or are in the ratio of 1 :-l-l :2.5. The hollow fiber membrane module combined with air diffusers (see FIG. 6) provided in a width ratio of 1 : 1.5 has a trapezoidal appearance when seen from a lateral surface thereof.

Now referring to FIG 7, the air or oxygen bubbles (17) generated from the air or oxygen discharge holes (2) horizontally vibrate the bundles of the U-shaped hollow fiber membranes (15) and vibrate both ends of the hollow fiber membranes (15) stretched over the upper distribution structure and the lower structure (see FIG. 1), thereby contributing to minimization of the pollutant elements.

Furthermore, the centrally rising air bubbles (17) ascend inside and outside of the hollow fiber membrane to induce expansion of polluted materials on the surface of the hollow fiber membrane (see FIG. 7) and provide an effect of removing potential pollutant materials, thereby enabling to maintain a penetration performance for a long period of time.

Now referring to FIG. 8, when waste water flows in, the hollow fiber membrane module combined with air diffusers (see FIG. 6) filters and discharges the treated water along a filtered treated water line (20) according to the driving of a suction pump (21), where air or oxygen bubbles (17) are continuously provided through an air line (23) and air or oxygen inlets (7-a, 7-b) of the module according to a blower (24) for introducing the air. The flux of the treated water from the hollow fiber membrane module combined with air diffusers according to the present invention is 30-45 LMH (l/m²-hr).

[PREFERRED EMBODIMENTS]

The preferred embodiments of the present invention will now be described in detail. It should be noted that the embodiments are not intended to be exhaustive or to limit the invention and description. The flux is measured by an average quantity (l/m².hr) of treated water obtained per unit area of the hollow fiber membrane and per unit time.

[FIRST EMBODIMENT]

The first embodiment was carried out as shown in FIG. 8 using the hollow fiber membrane module combined with air diffusers according to the present invention. The provided quantity of air is 0.8 rn/hr per unit area of the hollow fiber membrane, and the diameter of each hole of the air diffusers was 2.5mm. The number of holes between legs (6) was 5 and a total of 15 at one side of the air diffuser. The quantity of flux treated by the membrane is given in TABLE 1 and FIG. 9.

[FIRST COMPARATIVE EXAMPLE] A first comparative example was performed with a separate installation of a round air diffuser as was done in the first embodiment, and the same hollow fiber membrane module of the present invention, except the combined air diffusers, was used. The quantity of flux is shown in TABLE 1 and FIG. 9.

[SECOND EMDODIMENT]

The diameter of each hole of the air diffusers at the hollow fiber membrane module combined with air diffusers was measured at 2.5mm and the number of holes between the legs (6) was 3. The provided quantity of air was lm/hr per area of the hollow fiber membrane. The quantity of flux is shown in TABLE 1 and FIG. 10.

[THIRD EMBODIMENT] The diameter of each hole of the air diffusers at the hollow fiber membrane module combined with air diffusers is set at 2.5mm, and the number of holes between the legs (6) was 3. The provided quantity of air was 1.5m hr and the quantity of flux is shown in TABLE 1 and FIG. 10.

[FOURTH EMBODIMENT]

One air or oxygen inlet at the hollow fiber membrane module combined with air diffusers was equipped at an air diffuser connector, and the diameter of each hole was set at 0.5-2.5mm, while the diameter of each air or oxygen discharge hole was gradually enlarged as it was distanced from the air or oxygen inlet. The number of air or oxygen discharge holes was established at 3 between the legs (6), and a total number of 9 holes were equipped at one side of an air diffuser. The quantity of provided air was given at 1.5m/hr per area of the hollow fiber membrane. The quantity of flux is shown in TABLE 1.

[T AB L E 1]

As evidenced in the foregoing, there is an outstanding effect in the hollow fiber membrane module combined with air diffusers according to the present invention thus described in that the impurities are minimized when the hollow fiber membrane module (see FIG. 6) filters and discharges the treated water in a biological treating reactor by way of air or oxygen bubbles (17) generated from the air or oxygen discharge holes (2) at the air diffusers (1-a, 1-b).

In other words, there is a great effect in that the air or oxygen bubbles generated from the air diffusers (1-a, 1-b) horizontally vibrates the hollow fiber membranes (15) arranged in a U-shape at the air diffuser, and the rising air or oxygen bubbles (17) centrally ascend to again pass through or pass by the hollow fiber membranes (15) and are diverged outside. The ventilation system (see FIG 7) for inducing diffusion of pollutant materials on the surface of the hollow fiber membrane results in an excellent maintenance of penetration performance for a long period of time.

[APPLICABILITY FOR INDUSTRIAL USE]

In the hollow fiber membrane module combined with air diffusers according to the present invention thus described, the impurities are minimized when the hollow fiber membrane module filters and discharges the treated water in a biological treating reactor by way of air or oxygen bubbles generated from the air or oxygen discharge holes at the air diffusers, thereby resulting in a good maintenance of protracted penetrating capability.

The foregoing description of the preferred embodiments of the present invention has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A hollow fiber membrane module combined with air diffusers, wherein the module comprises: hollow fiber membranes (15); a lower structure including an air or oxygen inlet (7-a), air diffusers (1-a, 1-b) each formed with air or oxygen discharge holes (2) and hitched with said hollow fiber membranes (15) formed in a U-shape, lower connectors (4-a, 4-b) each connecting a strut and said air diffusers, and legs (6); an upper hollow fiber membrane distribution structure (9) for dispersedly arranging distal ends of bundles of said hollow fiber membranes; a head (12) for sealing said upper hollow fiber membrane distribution structure (9) and said hollow fiber membranes (15), and equipped with a filtered water outlet (13); and struts (8-a, 8-b) for connecting said upper hollow fiber membrane distribution structure (9) and said lower structure (see FIG. 1).

2. The module as defined in claim 1, wherein the shape of said air diffusers (1-a, 1-b) is round or cylindrical and the diameter of each said air or oxygen discharge hole (2) is set in the range of 0.5-4mm, and the number of holes between said legs (6) is in the range of 2- 8.

3. The module as defined in claim 2, wherein the space between said air or oxygen discharge holes (2) is in the range of l-5cm.

4. The module as defined in claim 1, wherein said hollow fiber membranes are applied or coated with more than one polymer out of Polyvinylidene Fluoride (PVDF), Polysulfone (PSf), Polyethersulfone (PES), Polypropylene (PP) and Polyethylene (PE) on the surface of hollow fibers constituting PP or PE, and each said hollow fiber membrane has a tensile strength of more than 30,000 gf/fil.

5. The module as defined in claim 4, wherein each hole of said hollow fiber membranes (15) has a diameter in the range of 0.1-0.4μm, and an external diameter thereof is in the range of 1.5-2.5mm.

6. The module as defined in claim 1, wherein each length of said hollow fiber membranes is in the range of 0.5-1.5m, and a total number of 500-2000 membranes are used to cover an entire area of 5-15 square meters.

7. The module as defined in claim 1 or 2, wherein the amount of air or oxygen generated from said air diffusers (1-a, 1-b) is in the range of 0.5-3.5m/h per unit area of said hollow fiber membranes.

8. The module as defined in claim 1, wherein said lower structure further comprises air diffuser connectors (3-a, 3-b) for connecting both tip ends of said air diffusers, and one or more than one air or oxygen inlet is equipped at said air diffuser connecting bar.

9. The module as defined in claim 1, wherein said struts (8-a, 8-b) stretch from lower strut insertion holes (5-a, 5-b) to upper strut insertion holes (10-a, 10-b) of said upper hollow fiber membrane distribution structure (9), and each said strut (8-a, 8-b) has a round or oval shape, and the diameter of each said strut is in the range of 1-3 cm and the length of each said strut is in the range of 0.2-1 m.

10. The module as defined in claim 1, wherein the number of said hollow fiber membrane distribution holes (11) at said upper hollow fiber membrane distribution structure (9) is in the range of 6-12, and the number of said hollow fiber membranes (15) inserted into each said distribution hole (11) is in the range of 100-300.

11. The module as defined in claim 1, wherein a head (12) is disposed with frame fixing grooves (14-a, 14-b) for further connecting and fixing said hollow fiber membrane module to a frame.

12. The module as defined in claim 12, wherein said frame fixing grooves (14-a, 14-b) are positioned at 2-4 places of said head (12).

13. The module as defined in claim 1, wherein said head (12) for sealing said upper hollow fiber membrane distribution structure (9) and said lower structure are of the same length while the widths thereof are in the ratio of 1 : 1-1:2.5.

14. The module as defined in claim 13, wherein the width of said lower structure and said head (12) for sealing said hollow fiber membranes given in the ratio of 1 : 1.5-

1 :2.5 has a trapezoidal appearance when seen from a lateral surface thereof.

15. A ventilation system of a hollow fiber membrane module combined with air diffusers according to claim 1, wherein said air or oxygen bubbles (17) generated from said air or oxygen discharge holes (2) vibrate both ends of said hollow fiber membranes (15) stretched over said upper distribution structure and said lower structure (see FIG. 1), and said centrally rising air bubbles (17) ascend inside and outside of the hollow fiber membrane to induce expansion of polluted materials on the surface of said hollow fiber membranes, thereby contributing to minimization of impurities of said hollow fiber membranes.

16. A waste water treating method of continuously providing air or oxygen bubbles (17) through an air line and an inlet (7-a) of a module by way of a blower (24) for introducing air or oxygen, and using said hollow fiber membrane module combined with air diffusers according to claim 1 for filtering and discharging treated water by way of a suction pump.