JPS587323B2 - How to clean selectively permeable membranes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides selective permeable membranes (such as ultrafiltration membranes and reverse osmosis models).
Selective permeable membrane cleaning that is effective in removing organic and other membrane surface contaminants that adhere to the permeable membrane and significantly reduce processing performance when processing liquids containing organic substances. It is about the method.

Conventionally, membrane separation methods such as reverse osmosis or ultrafiltration have been applied to separation, concentration and purification processes in the food, pharmaceutical, and petrochemical industries.
Certain organic substances in the liquid to be treated sometimes adhere to the membrane surface and reduce the treatment capacity (water permeation rate of the membrane).

For this reason, various cleaning methods have been proposed to remove organic membrane surface contaminants.

Currently, known cleaning compositions used in this cleaning method include surfactants typified by commercially available synthetic detergents, acidic solutions, alkaline solutions, and enzyme agents.

However, commercially available synthetic detergents are not sufficient to remove membrane surface contaminants.

In addition, cleaning with aqueous solutions of organic acids such as citric acid and oxalic acid, and inorganic acids such as hydrochloric acid and sulfuric acid, which are known as acidic solutions, is effective in removing inorganic membrane surface contaminants; Removal has no effect.

In addition, in alkaline cleaning with caustic soda, etc., membrane surface cleaning with a dilute alkaline solution does not sufficiently remove organic membrane surface contaminants, and with a concentrated alkaline solution,
It is not practical because it is limited by the chemical resistance of the membrane material and difficult to clean.

Alcozyme (trade name, manufactured by Alconotx), which contains protease and α-amylase as an enzyme agent, is known to effectively remove membrane surface contaminants in membrane treatment processes related to dairy farming, but Therefore, the cleaning time must be extremely long, which poses a practical problem.

Furthermore, because of the selectivity of the enzymatic reaction to organic substances, it has the disadvantage that it is not effective in cleaning a wide range of organic membrane surface contaminants.

The present inventors have discovered that the permeable membrane material is cellulose acetate,
Satisfies the chemical resistance and PH resistance limitations of reverse osmosis and ultrafiltration exemplified by cellulose derivatives, polyamides, polysulfones, polyvinyl alcohols, polyethylene-vinyl acetate partially saponified copolymers, and polyacrylonitrile systems, As a result of various studies on cleaning methods for selectively permeable membranes that are highly effective in removing organic membrane surface contaminants, we found that among surfactants, certain anionic surfactants and certain nonionic surfactants The present inventors have discovered that a combination of the above ranges is excellent in the cleaning effect of organic membrane surface contaminants on a permeable membrane, and have completed the present invention.

That is, the present invention comprises 1.00 parts by weight of an alkylbenzenesulfonate sodium-based (hereinafter referred to as ABS) anionic surfactant, 5 to 55 parts by weight of an alkylphenol polyoxyethylene ether-based nonionic surfactant, and 30 to 1 part by weight of a phosphate.
The present invention relates to a method for cleaning a selectively permeable membrane, which comprises cleaning the selectively permeable membrane with a detergent composition containing 0.00 parts by weight.

The ABS used in the present invention is preferably a branched-chain sodium alkylbenzene sulfonate or a linear sodium alkylbenzene sulfonate, and the alkyl group has an average of 12 to 14 carbon atoms.

The alkylphenol polyoxyethylene ether surfactant used in the present invention as a nonionic surfactant is
The alkyl group is preferably nonylphenol or octylphenol, and the number of moles of polyoxyethylene groups added is preferably n=4 to 30 (R represents an alkyl group).

Here, this nonionic surfactant has an HLB value, which is currently used as a guideline for surfactant usage [hydrophobicity/lipophilicity of surfactant - quantification of the properties of the bipolar structure regarding lipophilicity/hydrophobicity]. In 1959, AtlasPo
W. of wderCo (USA). D. According to the hydrophilicity-lipophilic balance proposed by Griffin, where the most hydrophilic surface activity is expressed as 20 and the weakest as 1], the HLB value can be suitably selected from 9 to 18. .

It is difficult to obtain a good cleaning effect with HLB values other than this.

In this case, two or more types of alkylphenol polyoxyethylene ether type nonionic surfactants can be optionally blended so that the HLB value is 9 to 18.

The amount of the alkylphenol polyoxyethylene ether nonionic surfactant is limited to 25 to 55 parts by weight per 100 parts by weight of ABS.If the amount is less than 25 parts by weight or more than 55 parts by weight, the detergency against the membrane surface will be reduced. This is because ABS and alkylphenol polyoxyethylene ether surfactant have a synergistic effect when they are combined within a certain range.

The phosphoric acid used in the present invention has the general formula Mn+2Pn
O3n+1 (here M indicates sodium and potassium)
The following can be mentioned.

Here, n is usually a positive integer of 1 to 4.

Specifically, sodium orthophosphate (or potassium),
These include sodium (or potassium) pyrophosphate, sodium (or potassium) tripolyphosphate, and sodium (or potassium) tetraphosphate.

Further, a material represented by the general formula MnPn03n (where M represents sodium or potassium) can also be used.

Specifically, sodium polymetaphosphate (or potassium)
, sodium (or potassium) hexametaphosphate, etc.

In addition, as the phosphate in the present invention, M of the above general formula
It is also possible to use compounds in which part of (ie, sodium or potassium) is replaced by hydrogen, such as dibasic sodium (potassium) phosphate.

The amount of phosphate compounded is 30 to 1 per 100 parts by weight of ABS.
The reason why it is set at 00 parts by weight is that below 30 parts by weight, the phosphate has no effect as a cleaning aid, increasing the activity of the surfactant and improving the dispersibility of pollutants, such as emulsification and suspension. This is because the membrane surface cleaning effect is inferior because it does not cause
If the amount is more than 0 parts by weight, the solubility of the phosphate in water is limited and its effectiveness as a cleaning aid is reduced, resulting in a poor removal effect of membrane surface contaminants. The cleaning effect is fully exhibited within such a limited range.

In addition, when using the detergent composition of the present invention, it is preferable to use it in an alkaline region in order to obtain a good cleaning effect. It is added as appropriate to achieve a normal pH of 8. 5 to 13, and can be selected from alkalinizing agents such as caustic soda, soda carbonate, and sodium silicate.

Considering the cleaning effect and the PH resistance of the material of the permeable membrane, which is the base material to be cleaned, the pH is 8. 5 to 13 are preferred.

pH 8. If it is less than 5, it is difficult to obtain a cleaning effect, and p
If it is H13 or higher, there is a risk of deterioration of the cellulose acetate membrane and some permeable membrane materials.

The membrane cleaning detergent composition of the present invention can be used as long as it is a uniform aqueous solution, but it is usually 0.05 to 3.
The maximum cleaning effect can be obtained by washing with a 0% by weight aqueous solution, preferably a 0.1 to 1.0% by weight aqueous solution.

In addition, when using the detergent composition of the present invention, it is desirable to use physical cleaning elements such as heat, stirring force, frictional force, pressure, and ultrasonic waves in combination in order to efficiently remove membrane surface contaminants. The most suitable method can be selected depending on the type of separator, such as a replica or ultrafiltration membrane.

Here, the temperature of the cleaning solution is desirably as high as it does not adversely affect the membrane, and examples thereof include 40°C in the case of an acetylcellulose-based permeable membrane, 70°C in the case of a polysulfone-based permeable membrane, and 50°C in the case of a polyimide-based permeable membrane.

Further, the sponge ball cleaning method and the ultrasonic cleaning method, which are currently known as methods for removing contaminants from membrane surfaces, are effective means for maximizing the cleaning effect of the present invention.

The membrane surface cleaning detergent composition of the present invention is used to remove contaminants, mainly organic contaminants, that adhere to the permeable membrane surface when wastewater containing organic substances is treated with a reverse osmosis membrane or an ultrafiltration membrane. It has an outstanding effect in recovering membrane performance after deterioration caused by water damage.For example, it can be used to clean membrane surface contaminants in the membrane treatment of kitchen wastewater in restaurant buildings in large cities, and in the separation and concentration process of water-soluble cutting oil wastewater. It is suitably used for cleaning membrane surface contaminants that occur when applying treatment methods.

The present invention will be specifically explained below using examples.

Example 1 A tubular ultrafiltration membrane module (manufactured by Nitto Denko NTU-3020) made of polysulfone material was used to recycle general wastewater from office buildings including restaurants in the city for use as gray water.
-P18B), when pressurized operation was performed for 300 hours, the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this ultrafiltration membrane, the water permeation rate of tap water through the membrane was 1.0 at an operating pressure of 3 kg/cm2. 80m3/m
0 if membrane surface contamination progresses due to the above operation in 2 days.
．． 30 m3/m2. It was day.

When cleaning ultrafiltration membranes contaminated with organic substances, etc., use sodium dodecylbenzenesulfonate (
Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "Neogen R" 140
g, polyethylene glycol nonyl phenyl ether (
Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "EA170" HLB
A 0.3% by weight aqueous solution (pH
9.0) was prepared as a cleaning solution, and this cleaning solution was circulated at 30° C. for 1 hour at an inlet pressure of 0.5 kg/cm 2 .

As a result, the water permeation rate of the membrane was 1.75 m under the same conditions as above.
3/m2. He recovered on the same day.

This was a recovery rate of 97.2% relative to the initial water permeation rate.

Example 2 A tubular reverse osmosis membrane module (NTR-1130 manufactured by Nitto Denko Corporation) made of cellulose acetate material was used to recycle the general wastewater of an office building including restaurants in a certain city for use as gray water.
-P18A), when pressurized operation was performed for 300 hours, the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this reverse osmosis membrane, the water permeation rate of tap water through the membrane is 1.30 m3/m2 at an operating pressure of 20 kg/cm2.
．． 0 if membrane surface contamination progresses due to the above operation.
．． It became 85m3/m2day.

When cleaning reverse osmosis membranes contaminated with organic substances, etc., use sodium dodecylbenzenesulfonate (
Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "Neogen R") 13
0g, polyethylene glycol octyl phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "EA142" H
LB number 14) 65g and hexametaphosphoric acid, soda 1
A 0.3% by weight aqueous solution (pH 10) was prepared by dissolving 0.5g of
The cleaning solution was circulated for an hour at an inlet pressure of 0.5 kg/cm2.

As a result, the water permeation rate of the membrane was 1.24 m under the same conditions as above.
3/m2. He recovered on the same day.

This was a recovery rate of 95.4% relative to the initial water permeation rate.

Example 3 In the same water treatment as in Example 1, a tubular ultrafiltration membrane module made of the same polysulfone material (Nitto Denko N
When TU-30201P 18A) was operated under pressure for 400 hours, the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this ultrafiltration membrane, the water permeation rate of tap water through the membrane was 1.0 at an operating pressure of 3 kg/cm2. 85m3/m
2. 1 day, when membrane surface contamination progresses due to the above operation.
is 0. 2 5 m3/m2. It was day.

When cleaning ultrafiltration membranes contaminated with organic substances, etc., use sodium n-dodecylbenzenesulfonate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name "Neogen SC").
J” 128g, polyethylene glycol nonyl phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “EA17”)
0” HLB value 17) 45g and sodium pyrophosphate 12
A 0.3% by weight aqueous solution (pH 13) was prepared by dissolving 7 g in 100 liters of water to prepare a cleaning solution, and the cleaning solution was circulated at 45° C. for 2 hours at an inlet pressure of 0.5 kg/cm 2 .

As a result, the water permeation rate of the membrane was 1.72 m under the same conditions as above.
3/m2. He recovered on the same day.

This was a recovery rate of 93.0% relative to the initial water permeation rate.

Example 4 In the same water treatment as in Example 1, a tubular reverse osmosis membrane module made of cellulose acetate material (NTR-
1150-P18A) was operated under pressure for 400 hours, the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this reverse osmosis membrane, the water permeation rate of tap water through the membrane is 0.95 m3/m2 at an operating pressure of 20 kg/cm2.
．． If membrane surface contamination progresses due to the above operation on day, 0.
60m3/m2. It was day.

When cleaning reverse osmosis membranes contaminated with organic substances, etc., use sodium dodecylbenzenesulfonate (
Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "Neogen R" 140
g, polyethylene glycol nonyl phenyl ether (
Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "EA-80" HLB
Value 10) 21g, polyethylene glycol nonyl phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “EA-
170'' HLB value 17) 56 g and sodium hexametaphosphate 83.9 were dissolved in 100 liters of water to prepare a 0.3% by weight aqueous solution (pH 9.5) as a cleaning solution.
The wash solution was circulated at an inlet pressure of 0.5 kg/ffl for 1 hour at °C.

As a result, the water permeation rate of the membrane was 0.92i under the same conditions as above.
/m. He recovered on the same day.

This was a recovery rate of 96.8% relative to the initial water permeation rate.

Example 5 In the same water treatment as Example 1, a tubular ultrafiltration membrane module (NTU-2020-P18B manufactured by Nitto Denko) made of a hydrophilic polyolefin synthetic polymer material was used to
During pressurized operation for hours, the water permeation rate decreased as shown below due to membrane surface contamination.

Before using this ultrafiltration membrane, the water permeation rate of tap water through the membrane is 1.85 m3/m2 at an operating pressure of 2 kg/cm2.
．． If membrane surface contamination progresses due to the above operation on day, 0.
48m3/m2. It was day.

When cleaning an ultrafiltration membrane contaminated with organic substances, use sodium n-dodecylbenzenesulfonate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Neogen SC" 2).
48g, polyethylene glycol nonyl phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "EA80JHL"
B number 10) 65.9 and sodium orthophosphate 87.9
0.4% by weight aqueous solution (p
H12) was prepared as a cleaning solution, and this cleaning solution was circulated at 35° C. for 0.8 hours at an inlet pressure of 0.5 kg/cm.

As a result, the water permeation rate of the membrane was 1.84 m under the same conditions as above.
3/m2. He recovered on the same day.

This was a 99.5% recovery rate relative to the initial water permeation rate.

Comparative Example 1 A tubular ultrafiltration membrane module made of the same polysulfone material (NTV manufactured by Nitto Denko) was used for the same water treatment purpose as in Example 1.
-3020-P18B), when pressurized operation was performed for 300 hours, the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this ultrafiltration membrane, the water permeation rate of tap water through the membrane is 1.80 m3/m2 at an operating pressure of 3 kg/cm2.
．． If membrane surface contamination progresses due to the above operation on day, 0.
30m3/m2. It was day.

When cleaning an ultrafiltration filter whose membrane surface is contaminated with organic substances, etc., for comparison, we used only water as the cleaning liquid and the inlet pressure was 0. It was circulated for 1 hour at 5 kg/cm2.

As a result, the water permeation rate of the membrane was 0.0% under the same conditions as above. 35
m3/m2. It was day.

This was a recovery rate of 19.4% relative to the initial water permeation rate.

Comparative Example 2 Tubular reverse osmosis membrane module made of cellulose acetate material (
When the Nitto Denko NTR-1130-P18A) was operated under pressure for 300 hours, the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this reverse osmosis membrane, the water permeation rate of tap water through the membrane is 1.34 m3/m2 at an operating pressure of 20 kg/cm2.
．． If membrane surface contamination progresses due to the above operation on day, 0.
86m3/m2. It was day.

When cleaning a reverse osmosis membrane whose membrane surface has been contaminated with organic substances, etc., 300 g of a commercially available synthetic kitchen detergent (manufactured by Kao Soap Co., Ltd., trade name "Celina J") is mixed into a 0.3% by weight aqueous solution (pH 9). A cleaning solution was prepared and the cleaning solution was circulated at 40° C. for 1 hour at an inlet pressure of 0.5 kg/cm 2 .

As a result, the water permeation rate of the membrane was 0.89 m under the same conditions as above.
3/m2. He recovered on the same day.

This was a recovery rate of 66.4% relative to the initial water permeation rate.

Example 6 When concentrating water-soluble cutting oil waste liquid used by a machine processing manufacturer using an ultrafiltration membrane, a tubular ultrafiltration membrane module (NTU-2 manufactured by Nitto Denko Corporation) made of the same membrane material as in Example 5 was used.
020-P18), when pressurized operation was performed for 200 hours, the water permeation rate decreased as follows due to membrane surface contamination.

Before using this ultrafiltration membrane, the water permeation rate of tap water through the membrane was 2.1 m3/m2 at an operating pressure of 3 kg/cm2.
0.5 when membrane surface contamination progresses due to the above operation on day.
4m3/m2. It was day.

When cleaning ultrafiltration membranes contaminated with organic substances, etc., use sodium n-dodecylbenzenesulfonate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Neogen SC").
) 300g, polyethylene glycol nonyl phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "EA170")
'HLB value 17) 150g and sodium pyrophosphate 15
A 0.6% by weight aqueous solution (pH 10.5) was prepared by dissolving 0g in 100L of water to prepare a cleaning solution, and the solution was heated to 0.0% at 40°C.
This cleaning solution was circulated for 5 hours at an inlet pressure of 0.5 kg/cm2.

As a result, the water permeation rate of the membrane was 1.95 m under the same conditions as above.
3/m2. He recovered on the same day.

This was a recovery rate of 92.9% relative to the initial water permeation rate.

Example 7 In the same water treatment as in Example 6, a tubular ultrafiltration membrane module (NTU-201 manufactured by Nitto Denko Corporation) made of the same membrane material was used.
When pressurized operation was performed for 200 hours with 00-P18A), the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this ultrafiltration membrane, the water permeation rate of tap water through the membrane was 3.0 at an operating pressure of 3 kg/cm2. 5 m3/m
2. 0 if membrane surface contamination progresses due to the above operation on day
．． 59m3/m. It was day.

When cleaning ultrafiltration membranes contaminated with organic substances, etc., use sodium dodecylbenzenesulfonate (
Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "Neogen R") 93
g, polyethylene glycol nonyl phenyl ether (
Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "EA160" HLB
16) 42g and 65g of sodium orthophosphate to 10
0.2% by weight aqueous solution (pH 11) dissolved in 0l of water
) was prepared as a cleaning solution, and this cleaning solution was circulated at 50° C. for 1 hour at an inlet pressure of 0.5 kg/cm 2 .

As a result, the water permeation rate of the membrane was 3.20 m under the same conditions as above.
3/m2. He recovered on the same day.

This was a recovery rate of 91.4% relative to the initial water permeation rate.

Example 8 In the same water treatment as in Example 6, a tubular ultrafiltration membrane module (NTU-202 manufactured by Nitto Denko) made of the same membrane material was used.
When pressurized operation was performed for 400 hours at 0-P 18), the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this ultrafiltration membrane, the water permeation rate of tap water through the membrane was 2.0 at an operating pressure of 3 kg/cm2. Om3/m2
．． If membrane surface contamination progresses due to the above operation on day, 0.
51m3/m2. It was day.

When cleaning ultrafiltration membranes contaminated with organic substances, etc., use sodium n-dodecylbenzenesulfonate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Neogen SC").
206g, polyethylene glycol nonyl phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "EA110")
HLB value 11) 109g and sodium tripolyphosphate 1
A 0.5% by weight aqueous solution (pH 12) was prepared by dissolving 85g in 100L of water to prepare a cleaning solution, and the cleaning solution was heated at 30°C for 1 hour at an inlet pressure of 0. It was circulated at 5 kg/cm2.

As a result, the water permeation rate of the membrane was 1.86 m under the same conditions as above.
3/m2. He recovered on the same day.

This was a 93% recovery rate relative to the initial water permeation rate.

Example 9 In the same water treatment as in Example 6, a tubular reverse osmosis membrane module made of cellulose acetate material (NTR-1 manufactured by Nitto Denko) was used.
When pressurized operation was performed for 300 hours with 0 95-P 18), the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this reverse osmosis membrane, the water permeation rate of tap water through the membrane is 0.85 m3/m2 at an operating pressure of 42 kg/cm2.
．． If membrane surface contamination progresses due to the above operation on day, 0.
12m3/m2. It was day.

When cleaning a reverse osmosis membrane whose membrane surface is contaminated with organic substances, etc., use sodium n-dodecylbenzenesulfonate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Neogen SC").
539g, polyethylene glycol nonyl phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "EA130T")
0.9% by weight obtained by dissolving 146g of HLB value 13) and 216g of sodium hexametaphosphate in 100L of water.
An aqueous solution (pH 8.5) was prepared as a cleaning solution, and the cleaning solution was circulated at 35° C. for 1 hour at an inlet pressure of 0.5 kg/cm 2 .

As a result, the water permeation rate of the membrane was 0.0% under the same conditions as above. 82
m3/m2. He recovered on the same day.

This was a 96.5% recovery rate relative to the initial water permeation rate.

Example 10 In the same water treatment as in Example 6, a tubular reverse osmosis membrane module (manufactured by Nitto Denko NTR-
1097-P18) was operated under pressure for 300 hours, the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this reverse osmosis membrane, the water permeation rate of tap water through the membrane is 0.70 m3/m2 at an operating pressure of 42 kg/cm2.
．． If membrane surface contamination progresses due to the above operation on day, 0.
10 m3/m2. It was day.

When cleaning a reverse osmosis membrane whose membrane surface has been contaminated with organic substances, etc., use sodium dodecylbenzenesulfonate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name "Neogen SC") 27
8g, polyethylene glycol octyl phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "EA92" HL
B value 9) 144g and sodium hexametaphosphate 278g
0.7% by weight aqueous solution (
A cleaning solution with a pH of 9) was prepared and the cleaning solution was heated at 30°C for 0.7 hours at an inlet pressure of 0. It was circulated at 5 kg/cm2.

As a result, the water permeation rate of the membrane was 0.0% under the same conditions as above. 65
m3/m2. He recovered on the same day.

This was a recovery rate of 92.9% relative to the initial water permeation rate.

Comparative Example 3 A tubular ultrafiltration membrane module (NTU-2020-P18 manufactured by Nitto Denko) made of a hydrophilic polyolefin material
When pressurized operation was performed for 0 hours, the water permeation rate decreased as follows due to membrane surface contamination.

Before starting to use this ultrafiltration membrane, the water permeation rate of tap water through the membrane was 2.0 at an operating pressure of 3 kg/cm2. 5m3/m2
．． If membrane surface contamination progresses due to the above operation on day, 0.
56m3/m2. It was day.

When cleaning ultrafiltration membranes contaminated with organic substances, etc., use sodium dodecylbenzenesulfonate (
Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "Neogen R") 40
0g, and 200g of sodium tripolyphosphate in 100L
A 0.6% by weight aqueous solution (pH 10.5)
) was prepared as a cleaning solution, and the cleaning solution was heated at 40°C for 0.5 hours at an inlet pressure of 0. It was circulated at 5 kg/cm2.

As a result, the water permeation rate of the membrane was 1. 2m
3/m2. He recovered on the same day.

This was a 48% recovery rate relative to the initial water permeation rate.

Comparative Example 4 For comparison with Example 9, when a tubular reverse osmosis membrane module made of cellulose acetate material (NTR-1095-P18A manufactured by Nitto Denko) was operated under pressure for 300 hours in the same water treatment, membrane surface contamination was observed. The water permeation rate decreased as follows.

Before starting to use this reverse osmosis membrane, the water permeation rate of tap water through the membrane is 0.87 m3/m2 at an operating pressure of 42 kg/cm2.
．． If membrane surface contamination progresses due to the above operation on day, 0.
14m3/m2. It was day.

When cleaning a reverse osmosis membrane contaminated with organic substances, etc., use polyethylene glycol nonyl phenyl ether (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name "EA13").
A 0.9% by weight aqueous solution (pH 8.5) was prepared by dissolving 345 g of "0T" HLB value 13) and 555 g of sodium hexamecrate in 100 liters of water to prepare a cleaning solution of 35
The washing solution was circulated at an inlet pressure of 0.5 kg/cm2 for 1 hour at .degree.

As a result, the water permeation rate of the membrane was 0.0% under the same conditions as above. 45
m3/m2. He recovered on the same day.

This was a recovery rate of 51.7% relative to the initial water permeation rate.

Claims (1)

[Claims] 1 Selective permeation with a detergent composition containing 100 parts by weight of a sodium alkylbenzene sulfonate anionic surfactant, 25 to 55 parts by weight of an alkylphenol polyoxyethylene ether nonionic surfactant, and 30 to 100 parts by weight of a phosphate. A method for cleaning a selectively permeable membrane, the method comprising cleaning the membrane.