JPH07328398A - Treatment solution for atibacterial/antifungal separation membrane and separation membrane module filled with treatment solution - Google Patents

Abstract

PURPOSE:To provide a treatment soln. for a separation membrane harmless to a human body, not generating a problem of drainage and capable of preserv ing a separation membrane module over a long period of time by using a polylysine soln. as the treatment soln. CONSTITUTION:Polylysine is a polymer of lysine and obtained, for example, by separating polylysine after the culture of polylysine producing bacteria. Further, polylysine may contain other natural substance or synthetic chemical substance not damaging the separation effect of a membrane. An antibacterial agent such as polyalginin may be together used. This polylysine can suppress the propagation of a wide range of bacteria such as heat-resistant bacteria, lactic bacteria or yeast and can limit the growth of them to extremely low concn. Since it is difficult to strictly specify the concn. of polylysine of this preservation soln., the concn. of polylysine must be determined in consideration of an initial viable cell number or a preservation state and is 1-5000ppm, pref., 5-1000ppm, more pref., 10-500ppm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial and antifungal treatment liquid for a separation membrane and a separation membrane module filled with the treatment liquid.

[0002]

2. Description of the Related Art Membrane separation technology is used in various fields including the food industry, medical field, and water treatment field. There are several types of separation membranes, such as microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, pervaporation membranes, etc., depending on the purpose and application, and there are various types of membranes such as flat membrane type, tubular type and hollow fiber type. is there. However, these separation membranes are generally formed by a method called a wet method or a dry-wet method, and are usually stored in a wet state until the separation membrane is modularized and used. An important problem in the storage of separation membranes and separation membrane modules is contamination due to generation of fungi and mold on the surface of the separation membrane and in the separation membrane module, and deterioration of the performance due to the contamination. Conventionally, formaldehyde (JP-A-57-39848), glutaraldehyde, hypochlorite, chlorine, sodium hydrogen sulfite, chloramine (JP-A-3-115), ozone (JP-A-57-1).
94005) and the like are added and dissolved and stored in an aqueous solution, or the separation membrane module is heated and sterilized while being filled with sterilized ultrapure water (JP-A-63-24840).
7), or kept at a low temperature (Japanese Patent Laid-Open No. 62-16010).
6) and the like, or by immersing and drying a solution of an antibiotic in a membrane to carry it (JP-A-4-243530), or containing a fungicide or antifungal agent in the membrane (JP-A-4-214741) is doing.

[0003]

However, when the separation membrane module is stored in an aqueous solution containing a drug such as formaldehyde, glutaraldehyde, chloramine, etc., these drugs are completely toxic because they are toxic. It is necessary, and it takes a lot of time to clean the chemical, which is disadvantageous in terms of cost. Further, even if the chemicals could be completely removed, there remains a problem in drainage and the like. Hypochlorite, chlorine, ozone, etc. are not persistent in antibacterial / mildew resistance and may deteriorate the film. Sodium bisulfite is effective against aerobic bacteria but not against anaerobic bacteria. The method by heating is effective for general bacteria, but is ineffective for thermospores and deteriorates the membrane. The method of low-temperature storage has poor reliability for long-term storage and is inferior in economic efficiency. The method using antibiotics leads to abuse of antibiotics, and is not preferable especially for the separation membrane module used for food and beverage.
Antibacterial and antifungal agents are also usually toxic and are problematic for use in food and beverage processes.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned drawbacks of the prior art, the present invention is harmless to the human body, has no problem in drainage, etc., and can separate the separation membrane module from bacteria and mold for a long period of time. The purpose was to prevent proliferation and preserve the membrane without degrading it.

That is, the present invention provides a separation membrane treatment liquid comprising a solution of polylysine having an antibacterial or antifungal action.

The polylysine of the present invention is a polymer of lysine, which is a natural product or a chemically synthesized product, and is obtained, for example, by culturing and separating the polylysine-producing bacterium.

The polylysine used in the present invention may contain other natural or synthetic chemical substances as long as it does not impair the separation effect of the membrane. It may also be used in combination with an antibacterial agent such as polyarginine.

The separation membrane has various purposes and uses such as for microfiltration, ultrafiltration, reverse osmosis, permeation and pervaporation. Further, the form of the membrane includes flat membrane, tubular, hollow fiber and the like, and the material thereof includes polymer (cellulosic / polyamide / polysulfone / polyethylene etc.) and inorganic (ceramic). Further, the form of the separation membrane module includes a flat plate type, a spiral type, a pleated type, a tubular type, and a hollow fiber type (there are bundled hollow fibers into a modular form or a braided modular form).
The separation membrane and the separation membrane module of the present invention stored by the storage solution of the present invention are not limited to the types of the separation membrane and the separation membrane module described above.

The polylysine of the present invention can exert the effect of suppressing the growth of microorganisms in a wide range of PH regions such as weak acidity, neutrality and alkalinity. Therefore, the solvent used for the treatment liquid is not particularly limited, but water is most preferable in view of the stability of the membrane, the economical efficiency, and the convenience at the start of the separation operation. Alternatively, use of a polyhydric alcohol such as glycerin or an aqueous solution thereof in order to prevent loss of the solvent during storage. Alternatively, a surfactant such as sodium lauryl sulfate may be added to these solutions as described above.

The water used in the treatment liquid of the present invention may be appropriately selected depending on the resistance of the membrane or the method of use. In order to maximize the effect of the polylysine, distilled water,
Reverse osmosis treated water, tap water, ion-exchanged water, etc. are preferred,
Furthermore, total organic carbon is 100 ppb or less, and viable cell count is 10
It is preferable to have a water quality of 0/100 ml or less, especially 50 ppb or less of total organic carbon, and 10 viable cells
It is more preferable to have a water quality of not more than 100 pieces / 100 ml. Total organic carbon serves as a nutrient source for the growth of fungi and mold, and the higher the concentration, the faster the growth rate of fungi and mold. Even if the total organic carbon concentration is low, if the number of viable bacteria is large in the initial stage, the growth amount of bacteria and mold will increase in the long term. Therefore, the smaller the total organic carbon and the viable cell count, the smaller the amount of polylysine added, which is economically advantageous and the effect lasts for a long time. The oxygen concentration is 5 ppm or less, preferably 3 pp
When water having a water quality of m or less, more preferably 0.5 ppm or less is used, the effect of preventing the growth of aerobic bacteria and mold can be enhanced. Since polylysine is highly effective against anaerobic fungi and mold, lowering the oxygen concentration can enhance the effect against both aerobic and anaerobic fungi and mold.

Generally, a polymer film is easily deteriorated by the influence of chemicals, and the film performance is also deteriorated accordingly. For example, a cellulose-based film is deteriorated by chlorine or hydrogen peroxide, and a polyamide-based film is deteriorated by chlorine. The membrane of polysulfone or polyether sulfone is deteriorated by hydrogen peroxide. Also, ozone affects almost all polymer films. Other chemicals may also be adsorbed to the membrane to reduce the membrane permeation performance, or so-called chemical fouling may occur. Therefore, any antibacterial / antifungal agent cannot be used as a preservative for separation membranes, and it is necessary to study the interaction with the membrane. However, when the interaction between the polylysine used in the present invention and the membrane was investigated and examined, it was found that it did not affect many separation membranes. In addition, polylysine is a natural substance that has antibacterial and antifungal effects, so it is highly safe. Even if it enters the body, it is a peptide and is decomposed into the essential amino acid L-lysine, which harms the human body. Never. Therefore, the drainage of the preservation solution of the present invention does not cause environmental problems.

The polylysine of the present invention is characterized in that it can suppress the growth of a wide range of microorganisms such as thermostable bacteria, lactic acid bacteria and yeasts and can inhibit the growth at an extremely low concentration.

The polylysine concentration of the preservation solution of the present invention is
It is economically advantageous that the amount is as small as possible without impairing the antifungal effect. However, the effects of sterilization, bacteriostatic, and bacteriostatic of bacteria, fungi, microorganisms, etc. vary depending on the initial viable cell count and the concentration of the drug, and also vary depending on the type and state of the fungus, fungus, microorganism. There are various types of separation membrane modules such as a hollow fiber membrane module with a relatively simple structure and a spiral module with a complicated structure. The situation is different. In addition, it is difficult to specify the viable cell count of the water used for the separation membrane preservation solution in a certain way, and it is generally not possible to quantitatively specify the initial viable cell count in the separation membrane module. In addition, it is difficult to specify the water quality of all organic carbon and the storage condition (temperature, period, etc.). Therefore, from the above, it is difficult to specify the polylysine concentration exactly, so the polylysine concentration should be determined in consideration of the initial viable cell count and the storage condition. However, approximately 1 to 5000 ppm, preferably 5 to 1000 pp
m, especially 10 to 500 ppm is preferred.

The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

[0015]

EXAMPLES In the Examples and Comparative Examples, total organic carbon (TOC) and viable cell count were measured by the following methods.

TOC; TOC automatic analyzer TOC-71
0 (manufactured by Toray Engineering Co., Ltd.) was used for the measurement.

Viable cell count: 100 ml of sample water was used to obtain a pore size of 0.
After filtering with a 45 micron membrane filter, M-TG
Culture in E medium at 35 ° C for 7 days. Count the number of colonies after culturing.

Example 1 A polyacrylonitrile hollow fiber membrane having a length of about 1 m was used as 100
After measuring the membrane permeation flux of a hollow fiber membrane module having a bundle of 00 and an effective area of 12 m ² , the module was filled with a preservative solution containing 100 ppm of polylysine. TOC in distilled water used as pure water of preservation solution is 100pp
b, the viable cell count was 6/100 ml. After storing this module at room temperature for one month, the viable cell count and membrane permeation flux were measured. The viable cell count was 2 cells / 100 ml. The membrane permeation flux was changed from 0.186 m ³ / m ² / hr / Kg to 0.183 m ³ / m ² / hr / atm, and almost no change was observed.

Comparative Example 1 The same distilled water without the addition of polylysine in Example 1 was filled in another module produced simultaneously under the same conditions. After storing this module at room temperature for 1 month, a part of the filling liquid was taken out and the viable cell count was measured to be 230 /
It was 100 ml. Membrane permeation flux is 0.149 m ³
/ M ² / hr / atm, which was about 20% lower.

Example 2 After measuring the membrane permeation flux of a small hollow fiber membrane module in which 10 hollow fiber membranes made of polyphenylene sulfone having a length of about 20 cm were bundled, the same preservative solution as used in Example 1 was filled. did. After storing this module at room temperature for one month, the viable cell count and the membrane permeation flow rate were measured. The number of viable bacteria is 3/10
It was 0 ml. Membrane permeation flux was 0 even after storage for 1 month.
It remained unchanged at 86 m ³ / m ² / day / atm.

Comparative Example 2 Two small hollow fiber membrane modules of Example 2 were added to the distilled water of Example 1 with sodium hypochlorite (10 p) instead of polylysine.
The stock solution added with pm was filled. One of the modules was stored at room temperature for one week and the other for one month, and the sodium hypochlorite concentration, viable cell count, and membrane permeation flux were measured. The viable cell count of the module stored for 1 week is 5/10
Almost no change was observed at 0 ml, but the sodium hypochlorite concentration was 0.4 ppm. The membrane permeation flux was 0.85 m ³ / m ² / day / atm, which was almost unchanged. The module stored for 1 month has almost no sodium hypochlorite, and the filling liquid contains 1 viable cells.
It was 60 pieces / 100 ml. Membrane permeation flux is also 0.6
It was 0 m ³ / m ² / day / atm, which was about 30% lower.

Example 3 A stock solution prepared by adding 100 ppm of polylysine to reverse osmosis treated water having a water quality of total organic carbon of 40 ppm and a viable cell count of 0/100 ml was applied to a reverse osmosis membrane element SC-1100 manufactured by Toray Industries, Inc. Filled. After this module was stored at room temperature for 3 months, the number of viable bacteria in the filled water, the amount of permeated water, and the salt removal rate were measured. The viable cell count was 1/100 ml. Both the amount of permeated water and the salt rejection rate are 5.7 m ³ /
The m ² / day (operating pressure 30 kg / cm ² ) and 95% were maintained.

Comparative Example 3 Example 3 in which polylysine was not added in Example 3.
A completely similar experiment was conducted except that the element was filled with the same reverse osmosis treated water used for the stock solution of. The viable cell count increased so much that it could not be measured under the same measurement conditions as in Example 3. Although the salt removal rate did not change, the amount of permeated water was 4.5 m ³ / m ² / day, which was about 20% or less.

Example 4 The wholly aromatic crosslinked polyamide composite membrane was sealed in a polyethylene bag filled with the preservative solution of Example 3 and stored at room temperature for 3 months. No change in appearance was observed. , The amount of permeated water, and the salt removal rate were almost the same as the initial performance.

Comparative Example 4 In the same experiment as in Example 4 except that sodium bisulfite was added in an amount of 2000 ppm in place of polylysine, the surface of the film turned brown, and when opened, it was found to be produced by anaerobic bacteria. It had a strong offensive odor.

[0026]

EFFECTS OF THE INVENTION Since the preservative solution for antibacterial and antifungal separation membranes of the present invention uses an aqueous solution of polylysine which is a natural antibacterial substance, it is harmless to the human body even when it is filled in a separation membrane module for food and beverage processes. Therefore, even if drained, no environmental problems will occur. In addition, the antibacterial and antifungal effects also continue for a long time, and the separation membrane and the separation membrane module can be stored without deteriorating the membrane performance.

Claims (7)

[Claims] 1. A treatment liquid for a separation membrane, which comprises a solution of polylysine. 2. The treatment liquid for a separation membrane according to claim 1, wherein the polylysine is a natural product type. 3. The treatment liquid for a separation membrane according to claim 1, wherein the solvent of the solution is water. 4. The concentration of polylysine is 1 to 5000 ppm.
The treatment liquid for a separation membrane according to claim 1, wherein 5. A separation membrane, which is immersed in a solution of polylysine. 6. A separation membrane module, which is filled with the treatment liquid according to claim 1. 7. A method for treating a separation membrane, which comprises immersing the separation membrane in a solution of polylysine.