JPH05228470A - Water purifier - Google Patents

Abstract

PURPOSE:To lower the adsorptivity of hydrocarbon-based organic substances in water by using a polysulfone-based hollow yarn membrane as a filter and to improve back washing efficiency by contriving the shapes of fine pores. CONSTITUTION:As a hollow yarn membrane 5, a polysulfone-based one is used and a back washing system to clean out impurities adhering to the external surface of the hollow yarn membrane 5 by causing clean water to flow reversely from the hollow inside route 53 side to the outside is installed and the pore diameter of the micropores 52 in the inner surface of the membrane wall 51 is made larger than the pore diameter in the outer surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water purifier, and more particularly to one using a hollow fiber membrane.

[0002]

2. Description of the Related Art In a conventional water purifier using a hollow fiber membrane of this type, raw water of a tap water is passed through the fine holes in the membrane wall of the hollow fiber membrane to the passage side of the hollow interior to remove organic substances in the raw water of the tap water. Impurities are captured and removed by the fine holes.

[0003]

However, in the conventional water purifier, impurities are deposited on the outer surface of the hollow fiber membrane with time and the fine pores are clogged, so that the flow rate of the water purifier decreases. There was a drawback.

In order to cover this drawback, filtered purified water is caused to flow backward from the outlet side of the hollow fiber membrane into the hollow internal passage,
It is considered that impurities such as organic substances attached to the hollow fiber membrane are washed by permeating from the inner surface to the outer surface side of the membrane wall to extend the life of the water purifier.

However, the effect of the conventional hollow fiber membrane was small even if it was backwashed. It was found that the cause depends largely on the material of the hollow fiber membrane. That is, conventional hollow fiber membranes use polyolefin polymers such as polyethylene. Since such a polyolefin-based polymer is a hydrocarbon-based polymer in which hydrogen is bonded to a carbon chain, it tends to be adsorbed when organic matter in water is a hydrocarbon-based polymer. Therefore, the organic substances attached to the surface of the hollow fiber membrane are difficult to separate and the backwashing efficiency is low.

In order to increase the backwash efficiency, the pore size of the fine pores in the membrane wall may be increased, but in polyethylene and the like, the inner and outer surfaces of the hollow fiber membrane have the same structure because the spinning method is the stretching method, and the fine pores If it is too large, the filtration performance will be deteriorated, and it is not suitable for backwashing.

The present invention has been made in order to solve the above-mentioned problems of the prior art. The object of the present invention is to use a polysulfone-based hollow fiber membrane as a filter medium to obtain a hydrocarbon-based organic substance in water. It is to reduce the adsorption power of and improve the backwash efficiency.

Another object is to improve the backwash efficiency in terms of shape by devising the shape of the fine holes.

[0009]

In order to achieve the above object, in the present invention, a hollow fiber membrane is used as a filter medium,
A water purifier that removes impurities by allowing raw water of tap water to permeate from the outer surface to the passage side of the hollow interior through fine pores in the membrane wall of the hollow fiber membrane, using a polysulfone-based hollow fiber membrane as the hollow fiber membrane. And a backwashing mechanism for washing impurities adhering to the outer surface of the hollow fiber membrane by backflowing purified water from the hollow inner passage side of the hollow fiber membrane toward the outside.

It is effective to make the pore diameter of the inner surface of the fine pores of the membrane wall of the polysulfone hollow fiber membrane larger than the pore diameter of the outer surface.

Further, it is preferable to use a nonionic surfactant as a surfactant for hydrophilically treating the hollow fiber membrane.

[0012]

In the water purifier having the above structure, since the organic substance in the water is not adsorbed unlike the conventional polyolefin type hollow fiber membrane by using the polysulfone type hollow fiber membrane, the impurities accumulated during back washing Easily separates from the hollow fiber membrane.

Impurities are trapped on the outer surface side by making the inner diameter of the fine pores of the membrane wall larger on the inner surface side than on the outer surface side. On the other hand, at the time of back washing, purified water flows into the fine holes from the fine hole openings on the inner surface side of the large diameter, so that the back washing efficiency can be improved.

If a nonionic surfactant is used as the hydrophilic treatment surface, the adsorption of organic substances can be prevented more effectively.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments. In FIG. 2 showing a water purifier according to an embodiment of the present invention, the water purifier 1 comprises activated carbon 2 for removing off-flavors such as odor of chlorine and hollow fiber membrane module for removing particle components such as turbidity and bacteria. 3 and a backwashing mechanism 4 for washing impurities adhering to the outer surface of the hollow fiber membrane.

The hollow fiber membrane module 3 is U in this embodiment.
A large number of hollow fiber membranes 5 bent in a letter shape are bundled and housed in a module case 10, and both ends thereof are connected to the module case 10.
This is a dead end filtration type module fixed to the open end of the with a potting material 11.

The hollow fiber membrane 5 is made of a polysulfone-based polymer, and as shown in FIG. 1, the pore diameter d of the inner surface of the micropores 52 of the membrane wall 51 of the polysulfone-based hollow fiber membrane 5 is d.
1 is larger than the hole diameter d2 on the outer surface. The hole diameter d2 on the outer surface side of the fine holes 52 corresponds to the impurities 1 to be removed.
An appropriate size is selected according to the size of 2, and the hole diameter d1 on the inner surface side is formed larger than that. As the surfactant for hydrophilically treating the hollow fiber membrane 5, a nonionic surfactant is used.

The hollow fiber membrane module 3 and the activated carbon 2 are integrally assembled in the housing 13. That is,
The hollow fiber membrane module 3 is arranged in the center of the housing 13, and the activated carbon 2 is filled so as to surround the periphery of the hollow fiber membrane module 3. An inflow pipe 14 for inflowing raw water into the housing 13 and an outflow pipe 15 for outflowing purified water after filtration project to the side surface of the housing 13. One end of the inflow pipe 14 is connected to the faucet 20 of the water supply through the connection tube 16, and the other end of the inflow pipe 14 faces the activated carbon 2 in the housing 13 and opens.
Further, one end of the outflow pipe 15 is the hollow fiber membrane module 13
It is connected to a purified water tank 21 provided on the purified water outflow end face side, and the other end is open to the outside of the housing 13.

The backwashing mechanism 4 is composed of a cylinder 22 and a piston 23 for applying pressure to the purified water accumulated in the purified water tank 21. In this embodiment, the water pressure of tap water is used as the backwash pressure, and the water pressure is supplied to the cylinder 2 via the pressure introduction pipe 24 branched from the inflow pipe 14.
Introduced in 2. A first switching valve 25 is provided at a branch portion between the pressure introducing pipe 24 and the inflow pipe 14 to switch between filtering and washing.

Further, the housing 13 is provided with a second switching valve 26 for discharging the cleaning water, and the water which has been cleaned by interlocking the first switching valve 25 and the second switching valve 26 with each other. Is discharged from the second switching valve 26.

In the water purifier having the above-mentioned structure, during filtration, the raw water of the tap water flows into the housing 13 through the inflow pipe 24 and passes through the activated carbon 2 to adsorb and remove the offensive odor such as chlorine. .. After passing through the hollow fiber membrane module 3, solid particle components such as bacteria and suspended matter are separated and removed, and the water purification tank 2
1 is temporarily stored and flows out from the outflow pipe 15.

At the time of cleaning, the first switching valve 25 is switched so that the raw water of the tap water is supplied to the cylinder 2 through the pressure introducing pipe 24.
Installed in 2 Due to this water pressure, the piston 23 is pressed and moved toward the end face of the hollow fiber membrane module 3.
At that time, the outer peripheral surface of the moved piston 23 closes the opening of the outflow pipe 15, the purified water in the purified water tank 21 is compressed, and the purified water flows from the outlet side end surface opening of the hollow fiber membrane module 3 to the hollow internal passage 53. Flowing into the hollow fiber membrane 3 of the membrane wall 5
It flows back to the outside activated carbon 2 side through the first fine hole 52, and is discharged to the outside from the second switching valve 26.

In this backwashing, since the hollow fiber membrane 5 is made of polysulfone, it does not adsorb organic matter in the water like the conventional polyolefin hollow fiber membranes. Easily separate from the hollow fiber membrane 5.

Impurities are trapped on the outer surface side by making the inner diameter of the fine pores 52 of the membrane wall 51 larger on the inner surface side than on the outer surface side. On the other hand, at the time of back washing, purified water flows into the fine holes 52 from the opening of the fine holes 52 on the inner surface side having a large diameter, so that the back washing efficiency can be improved.

If a nonionic surfactant is used for the hydrophilic treatment, the adsorption of organic substances can be prevented more effectively.

To confirm the effect of the present invention, FIG.
The test was conducted by setting up a test device as shown in.

The test apparatus will be briefly described below.
As samples, a polysulfone-based hollow fiber membrane module S1 using the polysulfone-based hollow fiber membrane of the present invention and a polyolefin-based hollow fiber membrane module S2 composed of a conventional polyolefin-based hollow fiber membrane were prepared. The membrane modules S1 and S2 are connected in parallel, and the pump P is provided on the upstream side.
O is connected, the purified water tank T which stores the filtered purified water on the downstream side is respectively connected, and the flow meter F and the pressure gauge P which measure the flow rate which passes each hollow fiber membrane module S1, S2 are attached. Then, two first and third electromagnetic switching valves V1 and V3 are provided between the upstream-side pump PO and the hollow fiber membrane modules S1 and S2, and further, downstream second and fourth electromagnetic switching valves V2. , V4 are provided.

During filtration, the water supplied from the pump PO passes through the first electromagnetic switching valve V1 (open) and the polysulfone-based and polyolefin-based hollow fiber membrane modules S1 and S2, and temporarily accumulates in the tank T, and the second electromagnetic It is discharged from the outlet through the switching valve V2. The tank T has a capacity of 1 liter.

On the other hand, at the time of backwashing, air passes through the fourth electromagnetic switching valve V4 and pushes the water in the tank T to backflow in the polysulfone-based and polyolefin-based hollow fiber membrane modules S1 and S2, and is discharged from the outlet. It

The membrane area of each hollow fiber membrane module S1, S2 was about 0.6 to 0.7 square meters. Then, a cycle of filtering for 1 hour and backwashing for 10 seconds (translation: 500 cc) was repeated by a timer.

The results are shown in FIGS. 4 and 5. Of these, Figure 4
Shows the flow rate characteristics of the polyolefin-based hollow fiber membrane module S2 and the polysulfone-based hollow fiber membrane module S1, respectively, and FIG. 5 shows the results of the backwash test. As is clear from FIG. 5, the polysulfone-based hollow fiber membrane module S1 has a good flow rate recovery property due to backwashing and a good washing efficiency.

Next, FIG. 6 to FIG. 13 show more specific structural examples of such a water purifier with a backwash mechanism. That is, as shown in the figure, this water purifier includes a case 6, a main cartridge 7 and a pre-cartridge 8 housed in the case 6, a stand 500, and an exterior cover 50.
1 and 502. The stand 500, to which the lower part of the case 6 is fixed by screws, is connected to the stand 500 by hooks (not shown). In the figure, 506 is a suction cup.

The case 6 includes a lower case 60 and an upper case 6.
1, and the cylinder portion 6 disposed on the upper case 61
2, a lid 63 that closes the upper surface opening of the cylinder portion 62, and the main cartridge 7 and the pre-cartridge 8 are housed in the space surrounded by the lower case 60 and the upper case 61. Further, the switching valve 9 is arranged in the bottom of the lower case 60.

The switching valve 9 has a housing 90 fixed to the bottom plate of the lower case 60, covers 94 and 97 for closing both ends of the housing 90, and a rotatably housed inside the housing 90 and one end penetrating the cover 94. 7 and 9 (a), the housing 90 includes three ports 900, 901, 903, and a cover 97 side. Long continuous water passage 9 in the axial direction
02 and 904, the cover 97 has two ports 800 and 801 on the peripheral surface and a connection port 98 on the end surface, as shown in FIG. 9B.

Here, the port 900 is connected to the pre-cartridge 8, and the port 901 is connected via the L-shaped tube 906 and the tube 18 shown in FIG.
, The port 903 is connected to the drainage tube 907 through the T-tube 905, and the water passage 902 is connected to the port 90.
1 and the port 801 are connected, and the water passage 904 is connected to the port 9
03 and the port 800 are connected.

As shown in FIGS. 9 and 10, the valve body 91 is provided with a communication hole 92 in the portion where the ports 900, 901 and 903 are located, and is L-shaped in the portion where the ports 800 and 801 are located. There is a communication hole 93 that is provided and communicates with the connection port 98. Further, the valve body 91 is formed with two concave portions 601 arranged in the circumferential direction, and both concave portions 601 are separated from a cylinder provided in the lower case 60 by being biased by a spring 602, as shown in FIG. The projecting ball 603 is selectively engaged according to the rotation of the valve body 91, and the rotation of the valve body 91 by the lever 95 is clicked at two positions to perform positioning. Reference numeral 604 in FIG. 10 denotes communication holes 92, 9
3 is a seal plate that is mounted in the recess 605 around 3.

The main cartridge 7 has a cylindrical case 72 whose bottom opening is closed by a bottom cover 74, a cylindrical holder 73 fixed to the upper end of the cylindrical case 72, and a holder 7.
3 is composed of activated carbon 70 filled in the space between the outside and the inner surface of the tubular case 72. The bottom cover 74 and the tubular case 2
A non-woven fabric 75 for preventing leakage of the activated carbon 70 is disposed at a joint portion by screwing with the non-woven fabric 77. Are welded by ultrasonic welding to prevent the activated carbon 70 from leaking through the passage hole 76.

The main cartridge 7 has a holder 7 protruding upward from the center of the upper surface of the cylindrical case 72.
The upper end portion of 3 is screwed and connected to the top plate portion of the upper case 61 to be disposed in the case 6.

The pre-cartridge 8 disposed directly above the port 900 of the switching valve 9 has a case 80 whose bottom surface is formed by a perforated plate, a perforated lid 82, and a case 80 inside the case 80. Filtering agent 8 such as activated carbon filled in a state where the upper and lower parts are sandwiched by nonwoven fabrics 700, 700
Of the upper and lower nonwoven fabrics 700 that prevent the filtering agent 83 from leaking, the upper one is welded to the lid 82 by ultrasonic waves or the like.

The main cartridge 7 and the pre-cartridge 8 can be replaced by disassembling the lower case 60 and the upper case 61 which are connected by screwing.

The cylinder portion 62, which is disposed on the upper case 61 and whose top opening is closed by a lid 63, has a purified water discharge port 64 on the side surface of the central portion in the vertical direction. It is rotatable around a vertical axis and is prevented from coming off by a retaining ring 65, and a piston 67 is arranged inside. A packing 67 is attached to the outer peripheral surface, and a piston 67 that opens and closes the purified water discharge port 64 in accordance with the vertical movement is urged upward by a spring 69 and is operated by the lever 95. Is in the purified water position, it is in a position in which the purified water discharge port 64 is opened as shown in FIG.

Also, the plug 100 penetrating the lid 63.
Is connected to the other end of a tube 99, one end of which is connected to the connection port 98 of the switching valve 9. In addition, the plug 10 that penetrates the lid 63 and is attached by the snap ring 68
0 is rotatable about the vertical axis with respect to the lid 63. Further, the nozzle 503 connected to the purified water discharge port 64 of the cylinder portion 62 has the exterior covers 501, 50.
Although it projects to the outside through the opening 504 formed between the two, when the cylinder portion 622 is rotated, the direction of the nozzle 503 can be changed within the range of the opening 504. , At this time, tube 9
9 is not rotated by the rotation stopper 507 shown in FIG. 8 provided in the lower case 60.

However, in the switching valve 9 of the purification unit A of this water purifier, as shown in FIGS. 7 and 9, the port 901 and the port 900 communicate with each other through the communication hole 92, and the connection port 98 has the communication hole 93. And port 9 through waterway 904
When the raw water supplied from the faucet is sent to the water purification unit A side through the tube 18 in the state of communicating with 03, this raw water enters the pre-cartridge 8 through the port 900, and the nonwoven fabric 700 and the filtering agent 83 After relatively large particles are removed and residual chlorine is removed by the method, after entering the cylindrical case 72 through the passage hole 76 in the upper part of the main cartridge 7 and contacting the activated carbon 70, the polysulfone-based hollow fiber membrane 71 is used. Upon receiving the filtration, it enters the purified water storage water α which is a space below the piston 67 in the cylinder portion 62, and then flows out to the outside through the purified water discharge port 64 and the nozzle 503.

From the purified water discharge state, the lever 95 is rotated so that the port 900 and the port 903 in the switching valve 9 communicate with each other as shown in FIGS.
8 is a port 901 through a communication hole 93 and a water passage 902.
The raw water sent from the switching unit B enters the space β between the piston 67 and the lid 63 through the water passage 902 and the connection port 98, and the piston 67 is spring 69 by the water pressure. Push down against.

For this reason, the purified water stored in the purified water storage portion α, which is the space below the piston 67, is partially discharged from the purified water discharge port 64 at the beginning of the descent of the piston 67, but the piston 67 is purified water. From the time when the outlet 64 is closed, the foreign matters adhering to the outer wall of the hollow fiber membrane 71 flow in the opposite direction in the main cartridge 7 and are washed away. From the port 903 connected to the port 900 through the pre-cartridge 8. Drainage tube 907 via L-shaped tube 906
Is discharged to the outside through.

After the backwashing is completed, the lever 95 is returned to the clean water position, and the switching valve 9 returns to the state shown in FIGS. At this time, the piston 67 is returned upward by the spring 69 (under the bias of the water pressure when the switching unit B is still in the water supply state to the purification unit A side), and therefore, in the space β. The water used as the backwashing power is pushed back and discharged from the drainage tube 907 from the connection port 98, the water passage 904 and the port 903, and the L-shaped pipe 906.

[0047]

EFFECTS OF THE INVENTION The present invention has the above-mentioned constitution and action, and by using a polysulfone-based hollow fiber membrane, it does not adsorb organic matter in water unlike conventional polyolefin-based hollow fiber membranes. Impurities deposited at that time can easily separate from the hollow fiber membrane, and the backwash efficiency can be enhanced.

Further, the backwash efficiency can be enhanced while maintaining the filtering performance by making the inner surface side of the fine pores of the membrane wall larger than the outer surface side.

Furthermore, if a nonionic surfactant is used as the hydrophilic treatment surface, the adsorption of organic substances can be prevented more effectively.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional configuration diagram of a hollow fiber membrane of a water purifier according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a water purifier in which the hollow fiber membrane having the configuration of FIG. 1 is used.

FIG. 3 is a schematic configuration diagram of a test apparatus for carrying out a cleaning performance test of the present invention and a conventional water purifier.

FIG. 4 is a graph showing flow rate characteristics of the water purifier of the present invention and the conventional water purifier.

FIG. 5 is a graph showing backwashing characteristics of the water purifier of the present invention and the conventional water purifier.

FIG. 6 is a vertical cross-sectional view showing a more specific structure of the water purifier of the present invention at the time of discharging purified water.

FIG. 7 is a central longitudinal sectional view of FIG.

FIG. 8 is a cutaway bottom view of the water purifier of FIG. 6.

9 (a) and 9 (b) are partial cross-sectional views of the water purifier of FIG.

10 (a) is a perspective view of a valve body of the switching valve of FIG. 6, and FIG. 10 (b) is a perspective view of a seal plate.

FIG. 11 is a vertical cross-sectional view of the water purifier of FIG. 6 during backwashing.

12 is a central vertical cross-sectional view of FIG.

13 (a) and 13 (b) are partial cross-sectional views of FIG.

[Explanation of symbols]

 1 Water Purifier 2 Activated Carbon 3 Hollow Fiber Membrane Module 4 Backwash Mechanism 5 Hollow Fiber Membrane 51 Membrane Wall 52 Micropore 53 Hollow Internal Passage 10 Module Case 11 Potting Material 12 Impurity 13 Housing 14 Inflow Pipe 15 Outflow Pipe 16 Connection Tube 20 Faucet 21 Water purification tank 22 Cylinder 23 Piston 24 Pressure introduction pipe 25, 26 First and second switching valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Gen Nakano Genki 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Toru Watanabe, 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works In-house (72) Inventor Ryusuke Nakanishi 1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.In-company (72) Ino Ryoi Itoh, 1048, Kadoma, Kadoma, Osaka

Claims (3)

[Claims] 1. A water purifier that uses a hollow fiber membrane as a filter medium and removes impurities by allowing raw water of the tap water to permeate from the outer surface to the passage side of the hollow interior through the fine pores in the membrane wall of the hollow fiber membrane. Using a polysulfone-based hollow fiber membrane, a backwash mechanism is provided to wash impurities adhering to the outer surface of the hollow fiber membrane by backflowing purified water from the hollow internal passage side of the hollow fiber membrane to the outside. A water purifier characterized by that. 2. The water purifier according to claim 1, wherein the pore diameter of the inner surface of the fine pores of the membrane wall of the polysulfone-based hollow fiber membrane is larger than the pore diameter of the outer surface. 3. The water purifier according to claim 1, wherein a nonionic surfactant is used as a surfactant for hydrophilically treating the hollow fiber membrane.