JPH11188246A - Washing method for hollow fiber membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and simple washing method for a hollow fiber membrane for alkali treating device removing transmission substance deposited on the inside of the hollow fiber membrane with an economical method and besides perfectly killing bacteria in the hollow fiber membrane disabled to remove them. SOLUTION: In a water treating device which has a water purifying part having the hollow fiber membrane 2 as one of the constitutional elements and an electrolysis bath 3 for producing electrolyzed water, electrolyzed acidic water and other adjusted water are continuously passed through the membrane 2 from the direction opposite to it at a time of water purification treatment, and the membrane 2 is washed by back-washing of the adjusted water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cleaning a hollow fiber membrane of a water purifier having a water purification treatment section having a hollow fiber membrane as one of constituent elements and a water electrolysis tank, and more particularly to an electrolytic acid water. And the other conditioned water is continuously passed through the hollow fiber membrane to extend the filtration life of the hollow fiber membrane.

[0002]

2. Description of the Related Art Conventional hollow fiber membrane modules are used in various fields such as food, medical, and water treatment fields. These hollow fiber membrane modules are formed into a module after being formed by a method called a wet method or a dry method. The hollow fiber membrane is generally used in a humid environment, and collects impurities and microorganisms in water in pores in the hollow fiber and removes them.

However, when used for a long period of time, deposits on the membrane wall surface such as contaminants and the growth of microorganisms in the module cause a reduction in processing capacity and a reduction in product quality. Therefore, it is necessary to remove the sediment or open the pores to restore the processing ability, and to provide a means for cleaning the hollow fiber membrane that prevents the growth of microorganisms such as bacteria and fungi.

Accordingly, as a method of using a chemical sterilizing solution as a cleaning solution, an aqueous solution of hypochlorous acid, sodium hydroxide or the like as disclosed in Japanese Patent Application Laid-Open No. 5-168873 is used. There have been proposed a method of passing water from the opposite direction to the case of performing water purification treatment, and a method of backwashing with a cleaning solution containing a natural antibacterial agent as disclosed in JP-A-9-52027.

[0005]

However, although a method using a chemical disinfectant as a cleaning solution can be expected to prevent the growth of microorganisms, these disinfectants are toxic to the human body. Must be completely removed so that they do not remain in the hollow fiber membrane.

Although a cleaning solution containing a natural antibacterial agent has low toxicity to the human body, the natural antibacterial agent is expensive, and it is doubtful whether its bactericidal activity is effective against all bacteria contained in water. .

According to the present invention, there is provided a hollow fiber membrane for water purification which removes filter substances deposited on the inner surface of the hollow fiber membrane by an economical method, and furthermore, completely eliminates various bacteria in the hollow fiber membrane which could not be removed. It is to provide a cleaning method.

[0008]

Means for Solving the Problems The method for cleaning a hollow fiber membrane according to the present invention is intended to achieve the above object, and the first invention is a water purification section having a hollow fiber membrane as one of the constituent elements. A water conditioner having an electrolysis tank that generates electrolyzed water, and continuously passes electrolyzed acidic water and other conditioned water through the hollow fiber membrane from the opposite direction of the water purification process. is there.

Further, the second invention is characterized in that when the hollow fiber membrane is backwashed with other conditioned water and then the electrolytic acid water is passed through, the deionized acidic water is applied to the hollow fiber membrane in the same direction as when using the water purification treatment. It allows water to flow.

[0010] In a third aspect of the present invention, the conditioning water for cleaning the hollow fiber membrane contains a biocompatible cleaning agent which is harmless to the human body, or simply uses tap water.

Further, in the fourth invention, the other adjusted water is 1
The type is not limited to the type, and any type may be used if necessary. That is, there are two or more types in combination with the electrolytic acidic water.

According to a fifth aspect of the present invention, the pH (acid, alkalinity) of the acidic water used for cleaning the hollow fiber membrane falls within the range of 2 to 6.

Further, in order to improve the sterilizing power of the electrolytic acidic water, salt is added to raw water supplied to the electrolytic cell as an electrolytic solution.

In the method for cleaning a hollow fiber membrane according to the present invention, the hollow fiber membrane is back-washed with a conditioning water for cleaning, so that the residue deposited on the side wall of the hollow fiber membrane and the pores of the hollow fiber membrane are collected. Impurities and microorganisms in the treated tap water are removed. At this time, if tap water is used as the conditioning water for washing, since the tap water contains residual chlorine, it is considered that some microorganisms that could not be completely removed by backwashing will die.

However, since microorganisms that cannot be completely removed and do not die remain in the hollow fiber membrane, electrolytic acid water is passed through the hollow fiber membrane in order to completely kill the microorganisms. When the electrolytic acid water is passed through the hollow fiber membrane, it may be from the opposite direction or the same direction as when using purified water, or from any direction. When passing the electrolytic acid water from the opposite direction, the residual microorganisms are simultaneously sterilized while performing back washing.

However, it is known that when the hollow fiber membrane is backwashed, the directionality of the pores on the side wall of the hollow fiber membrane is changed, so that some physical damage remains. Therefore, it can be expected that the life of the hollow fiber membrane can be further prolonged by performing the treatment from the forward direction using only the electrolytic acidic water. The pH of the electrolytic acid water used for the purpose of sterilizing microorganisms remaining in the hollow fiber membrane is adjusted to fall within a range of 2 to 6, and preferably around pH 2.7. Further, by adding salt to tap water supplied to the electrolytic cell as an electrolytic solution, it is possible to improve the electrolysis efficiency and improve the sterilizing power of the electrolyzed acidic water.

The characteristics of the sterilizing ability of the electrolytic acid water are that it has a broad antibacterial spectrum and that it is relatively safe for the human body because the raw material is only tap water or only tap water and salt. Furthermore, it is known that the duration of the sterilizing power of the electrolytic acid water is short. In other words, the sterilizing power of the electrolytic acidic water disappears after a certain period of time, so even if the sterilizing power of the electrolytic acidic water is concerned about the effect on the human body, the hollow fiber membrane may be washed by the method of the present invention for a while. If left untreated, the sterilizing power of the electrolyzed acidic water will completely disappear, and you can safely drink purified water.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method for cleaning a hollow fiber membrane of the present invention will be described below with reference to the drawings.

The first embodiment of the method for cleaning a hollow fiber membrane according to the present invention is directed to a water conditioner provided with a purifying section composed of activated carbon and a hollow fiber membrane and an electrolytic cell for electrolyzing purified water. The washing of the hollow fiber membrane in the above will be described with reference to FIGS. 1, 2 and 3. FIG.

FIG. 1 shows a water path when electrolytic water is generated by the water conditioner. When the electrolytic water is taken by the water conditioner, the water passes through the activated carbon 1 and the hollow fiber membrane 2. The water is electrolyzed. As shown in FIG. 1, this water conditioner has a three-way valve 11, an activated carbon 1 and a hollow fiber membrane 2 before an activated carbon 1.
Between the three-way valve 12 and the hollow fiber membrane 2 and the electrolytic cell 3, and three-way valves 13 and 14 between the hollow fiber membrane 2 and the electrolytic cell 3 for returning the electrolytic acid water generated as the electrolytic alkaline water is generated to the hollow fiber membrane 2. Three-way valve 1
5 are installed.

When the hollow fiber membrane of the water conditioner is washed, first, the hollow fiber membrane 2 is backwashed with tap water along the route shown in FIG.
Next, the hollow fiber membrane 2 is backwashed with electrolytic acid water along the route shown in FIG. Residues deposited on the side wall of the hollow fiber membrane 2 by backwashing with tap water and impurities in tap water collected in pores of the hollow fiber membrane 2 are washed away. In addition, by backwashing with electrolytic acid water, bacteria and microorganisms that cannot be completely removed by tap water backwash can be completely killed.

Next, a second embodiment of the method for cleaning a hollow fiber membrane according to the present invention is directed to a method for cleaning a hollow fiber membrane comprising a purifying section composed of activated carbon and hollow fiber and an electrolytic cell for electrolyzing purified water. About cleaning of the hollow fiber membrane in the water vessel, FIGS.
This will be described with reference to FIG.

FIG. 4 shows a water path when electrolyzed water is generated by the water conditioner. A three-way valve 16 is provided before the activated carbon 5 and three-way valves 17 and 18 are provided between the activated carbon 5 and the hollow fiber membrane. Hollow fiber membrane 6
Three-way valves 19 and 20 and a three-way valve 21 for returning electrolytic acid water generated as the alkaline water is generated toward the hollow fiber membrane 6 are provided between the electrolyzer 7 and the electrolytic cell 7.

When washing the hollow fiber membrane 6 of this water conditioner,
First, the hollow fiber membrane 6 is backwashed with tap water along the route shown in FIG. 5, and then electrolytic acidic water is supplied to the hollow fiber membrane 6 from the forward direction through the route shown in FIG.

In the case of the first embodiment, the electrolytic acid water is supplied from the opposite direction to the case where the hollow fiber membrane 2 is subjected to the water purification treatment. There is an advantage that bacteria and microorganisms that cannot be completely removed and are not killed are removed by backwashing and sterilized by the power of acidic water, but the pores of the hollow fiber membrane 2 are supplied in tap water supplied from the forward direction. There are many pores on the side wall of the hollow fiber membrane that have a directional property so that impurities can be easily collected. By performing backwashing, the directional property may change and physical damage may be avoided. I can't.

Therefore, in the second embodiment, the supply of electrolytic acid water from the forward direction suppresses the physical damage of the hollow fiber membrane 6 as compared with the case of the first embodiment. It can be expected that the film 6 will have a longer life.

In the above-mentioned method for cleaning the hollow fiber membrane, the sterilizing power of the electrolytic acidic water is limited to the condition that the organism is difficult to survive and the dissolved chlorine generated by the chloride ions present in the tap water undergoing electrolytic oxidation. And other chlorine active species are thought to contribute. Therefore, electrolytic acid water generated using water having a high chloride ion concentration can be expected to have a greater bactericidal effect.

FIG. 7 is a flow chart of tap water in the case where the hollow fiber membrane is backwashed with electrolytic acid water to which stronger sterilizing power is applied, and FIG. 8 is electrolytic water to which stronger sterilizing power is applied. Is a flow diagram of tap water when water is supplied to a hollow fiber membrane from a forward direction.

In the method for cleaning a hollow fiber membrane of the present invention, when the above-mentioned electrolytic acid water having a stronger sterilizing power is used, usually, the electrolytic alkaline water is obtained by a water conditioner having a water intake path shown in FIG. After the tap water backwash shown in FIG. 2 is performed on the hollow fiber membrane 2 of the water conditioner, the electrolytic acid water backwash shown in FIG. 7 is continuously performed. Alternatively, after the tap water backwash shown in FIG. 5 is performed on the hollow fiber membrane 6 of the water conditioner for obtaining electrolytic alkaline water with the water conditioner having the water intake path shown in FIG. May be performed continuously.

[0030]

Since the hollow fiber membrane cleaning method of the present invention has the above-described configuration, the hollow fiber membrane module is backwashed with raw water such as tap water and then treated with electrolytic acid water. Microorganisms such as bacteria and fungi in the hollow fiber membrane that could not be removed by the method can be sterilized. Electrolytic acid water has a broad antibacterial spectrum and is relatively safe for the human body because the raw material is only tap water or only tap water and salt.

Furthermore, the sterilizing power of the electrolytic acid water has a short duration, that is, the sterilizing power of the electrolytic acid water disappears after a certain period of time. Therefore, there is a concern that the sterilizing power of the electrolytic acid water may affect the human body. Even in this case, if the hollow fiber membrane is washed by the method of the present invention and left for a while, the sterilizing power of the electrolytic acid water completely disappears, and the purified water can be safely drunk. In addition, the electrolytic acid water can be easily prepared as long as it is a water conditioner provided with an electrolytic cell, and is therefore advantageous in terms of cost.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a water intake path of electrolytic alkaline water of an alkaline water conditioner, showing a first embodiment of a method for cleaning a hollow fiber membrane of the present invention.

FIG. 2 is an explanatory view of a water intake path of tap water back washing of the hollow fiber membrane of the alkaline water purifier, showing the first embodiment of the method for cleaning a hollow fiber membrane of the present invention.

FIG. 3 is an explanatory diagram of a water intake path for backwashing of the hollow fiber membrane of the alkaline water purifier with electrolytic acidic water, showing the first embodiment of the method for cleaning a hollow fiber membrane of the present invention.

FIG. 4 is an explanatory view of a water intake path of electrolytic alkaline water of an alkaline water conditioner, showing a second embodiment of the method for cleaning a hollow fiber membrane of the present invention.

FIG. 5 is an explanatory view of a water intake path of tap water backwashing of a hollow fiber membrane of an alkali water regulator, showing a second embodiment of the method for cleaning a hollow fiber membrane of the present invention.

FIG. 6 is an explanatory view of a water intake path when the hollow fiber membrane of the alkaline water purifier is washed with electrolytic acid water, showing the second embodiment of the method for cleaning a hollow fiber membrane of the present invention.

FIG. 7 is an explanatory view of a water intake path when the hollow fiber membrane of the alkaline water purifier of the first embodiment of the method for cleaning a hollow fiber membrane of the present invention is backwashed with electrolytic acid water having enhanced sterilizing power. is there.

FIG. 8 shows a water intake path when the hollow fiber membrane of the alkaline water purifier according to the second embodiment of the method for cleaning a hollow fiber membrane of the present invention is washed with electrolytic acid water having enhanced sterilizing power.

[Explanation of symbols]

1,5 Activated carbon 2,6 Hollow fiber membrane 3,7 Electrolyzer 11,12,13,14,15 Three-way valve of alkaline water regulator 16,17,18,19,20,21 Three-way valve of alkaline water regulator

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoko Fukushima 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Inside Sharp Corporation (72) Inventor Takeo Abe 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp (72) Inventor Rie Tamaru 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation

Claims (5)

[Claims] In a water purifier having a water purification section having a hollow fiber membrane as one of its constituent elements and an electrolytic tank for producing electrolytic water, electrolytic acid water and other conditioned water are subjected to water purification treatment. A method for cleaning a hollow fiber membrane, comprising continuously passing water through the hollow fiber membrane from a direction opposite to the direction in which the hollow fiber membrane is located. 2. In a water purifier having a water purification section having a hollow fiber membrane as one of the constituent elements and an electrolysis tank for producing electrolyzed water, firstly, conditioned water for washing the hollow fiber membrane is purified by water purification. Water is passed through the hollow fiber membrane from the opposite direction when
Next, a method for cleaning a hollow fiber membrane, comprising passing electrolytic acid water from the same direction as during the water purification treatment. 3. The method for cleaning a hollow fiber membrane according to claim 1, wherein raw water such as tap water is used as the conditioning water. 4. The pH of the electrolytic acidic water is 2.0 to 6.
The method for cleaning a hollow fiber membrane according to claim 1, wherein the adjustment is performed between 0 and 3. 5. The method for cleaning a hollow fiber membrane according to claim 1, wherein, when adjusting the electrolytic acid water, salt is added to raw water supplied to an electrolytic cell as an electrolytic solution.