阅读说明：本技术 反渗透膜装置的黏泥抑制方法 (Slime inhibition method for reverse osmosis membrane device ) 是由 远藤由彦 于 2019-08-22 设计创作，主要内容包括：本发明提供一种反渗透膜装置的黏泥抑制方法,其在短时间内能获得抑制黏泥(生物膜)产生的效果以及即使产生黏泥(生物膜)并附着于反渗透膜面也能去除黏泥(生物膜)的效果,该反渗透膜装置的黏泥抑制方法是应用于反渗透膜装置的黏泥抑制方法,其包括将被处理水通水于反渗透膜的通水工序,该通水工序包括第一通水工序,该第一通水工序将包含黏泥抑制剂X以及黏泥抑制剂Y的被处理水通水于所述反渗透膜,所述包含黏泥抑制剂X以及黏泥抑制剂Y的被处理水是在pH为10以下的被处理水中加入含有2,2-二溴-3-次氮基丙酰胺(DBNPA)的所述黏泥抑制剂X以及含有从由下述成分(A)～(D)(如说明书所记载)组成的组中选出的至少一种的所述黏泥抑制剂Y而成的。(The invention provides a slime control method for a reverse osmosis membrane apparatus, which can obtain the effect of inhibiting the generation of slime (biological membrane) and the effect of removing the slime (biological membrane) even if the slime (biological membrane) is generated and adhered to a reverse osmosis membrane surface in a short time, the slime control method for the reverse osmosis membrane apparatus comprises a water passing process of passing water to be treated to a reverse osmosis membrane, the water passing process comprises a first water passing process of passing the water to be treated including a slime inhibitor X and a slime inhibitor Y to the reverse osmosis membrane, the water to be treated including the slime inhibitor X and the slime inhibitor Y is added to the water to be treated with the pH value of 10 or less, wherein the slime inhibitor X containing 2, 2-dibromo-3-nitrilopropionamide (DBNPA) and the slime inhibitor X containing the following components (A) - (D) (described in the specification) are added At least one slime inhibitor Y selected from the group.)

1. A slime control method for a reverse osmosis membrane device, which is applied to the reverse osmosis membrane device, comprises a water passage step of passing water to be treated through a reverse osmosis membrane,

the water passing step includes a first water passing step of passing water to be treated containing a slime inhibitor X and a slime inhibitor Y through the reverse osmosis membrane, the water to be treated containing the slime inhibitor X and the slime inhibitor Y being obtained by adding the slime inhibitor X containing DBNPA that is 2, 2-dibromo-3-nitrilopropionamide and the slime inhibitor Y containing at least one selected from the group consisting of the following components (A) to (D) to water to be treated having a pH of 10 or less,

component (A): a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one, i.e., Cl-MIT, and 2-methyl-4-isothiazolin-3-one, i.e., MIT;

component (B): a chloramine compound;

component (C): a stabilizing bromide;

component (D): glutaraldehyde.

2. The slime suppressing method of a reverse osmosis membrane apparatus according to claim 1, wherein said chloramine compound as the component (B) is at least one selected from the group consisting of a component (B-1) and a component (B-2),

the component (B-1) is chloramine composed of ammonium salt and chlorine, and the component (B-2) is at least one selected from the group consisting of chloroaminosulfonic acid and chloroaminosulfonate.

3. The slime control method of a reverse osmosis membrane apparatus according to claim 1 or 2, wherein the water passing step further includes a second water passing step of passing the water to be treated, which does not contain the slime inhibitor X and the slime inhibitor Y, through the reverse osmosis membrane.

4. The slime control method of a reverse osmosis membrane apparatus according to any one of claims 1 to 3, wherein in the water passing step, the number of times of water passing in the first water passing step is 1 to 14 times per week, and the water passing time per one time of water passing is 1 hour or less.

5. The slime suppressing method of a reverse osmosis membrane apparatus according to claim 4, wherein the number of times of water passing in the first water passing step is once per day.

6. The slime control method of a reverse osmosis membrane apparatus according to any one of claims 1 to 5, wherein the first water passing step is performed under at least one condition selected from the group consisting of the following operation conditions 1 to 4,

operating conditions 1: operating conditions under which the permeate water and the concentrated water are not separated and are taken out only in the form of concentrated water;

operating conditions 2: operating conditions under which the permeate water and the concentrated water are separated and taken out separately and the permeate water is discarded;

operating conditions 3: operating conditions of raw water separated into permeate water and concentrate water, taken out separately, and returned to the reverse osmosis membrane apparatus;

operating conditions 4: the raw water is separated into the permeated water and the concentrated water, and the permeated water and the concentrated water are respectively taken out and returned to the reverse osmosis membrane device.

Technical Field

The present invention relates to a slime control method for a reverse osmosis membrane apparatus.

Background

A reverse osmosis membrane (RO membrane) provided in a reverse osmosis membrane apparatus is used for production of drinking water, production of pure water, reuse of drainage water, and the like. During operation of the reverse osmosis membrane apparatus, microorganisms such as bacteria contained in the water to be treated become slime (biofilm), and the microorganisms adhere to the reverse osmosis membrane surface and proliferate, resulting in a problem of membrane clogging.

Conventionally, as a method for removing slime adhering to a reverse osmosis membrane surface and growing thereon, a method has been performed in which an operation of a reverse osmosis membrane apparatus is stopped, and a reverse osmosis membrane is washed with a chemical such as caustic soda to remove the slime. However, this method hinders continuous operation of the reverse osmosis membrane apparatus, resulting in an increase in running cost.

In recent years, a method of removing slime (biofilm) adhering to a reverse osmosis membrane surface by injecting a slime inhibitor into a water system supplied to a reverse osmosis membrane apparatus without stopping the operation of the reverse osmosis membrane apparatus has been performed. In this method, various compounds have been studied as slime inhibitors, and many slime inhibition methods using the compounds have been proposed.

For example, patent document 1 discloses a method for producing pure water including a slime inhibitor addition step, a membrane treatment step, an ultraviolet irradiation treatment step, and an ion exchange treatment step. In addition, patent document 1 describes that the membrane treatment step is reverse osmosis membrane treatment using 2, 2-dibromo-3-nitrilopropionamide as a slime inhibitor.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2009 and 247992.

Disclosure of Invention

Problems to be solved by the invention

However, the method of patent document 1 requires the use of a slime inhibitor alone and has two steps, i.e., an ultraviolet irradiation treatment step and an ion exchange treatment step. In the method of patent document 1, since the number of steps is large and a corresponding amount of labor and time are required, further studies are required from the viewpoint of obtaining an effect of suppressing the generation of slime in a short time.

Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a slime control method for a reverse osmosis membrane apparatus, which can obtain an effect of controlling slime (biofilm) generation and an effect of removing slime (biofilm) even if slime (biofilm) is generated and adheres to a reverse osmosis membrane surface in a short time.

Means for solving the problems

The present inventors have intensively studied in view of the above problems, and as a result, have found that: the present inventors have completed the present invention by using 2, 2-dibromo-3-nitrilopropionamide (DBNPA) as a slime inhibitor X in combination with a slime inhibitor Y specified in the present invention and by passing water to be treated containing the slime inhibitor X and the slime inhibitor Y through a reverse osmosis membrane to obtain an effect of inhibiting the generation of slime (biofilm) and an effect of removing slime (biofilm) even if slime (biofilm) is generated and adheres to the reverse osmosis membrane surface in a short time. Namely, the present invention is as follows.

[1] A slime control method for a reverse osmosis membrane apparatus, comprising a water passage step of passing water to be treated through a reverse osmosis membrane, wherein the water passage step comprises a first water passage step of passing water to be treated containing a slime inhibitor X and a slime inhibitor Y through the reverse osmosis membrane, the water to be treated containing the slime inhibitor X and the slime inhibitor Y being obtained by adding the slime inhibitor X containing 2, 2-dibromo-3-nitrilopropionamide (DBNPA) and the slime inhibitor Y containing at least one selected from the group consisting of the following components (A) to (D) to water to be treated having a pH of 10 or less,

component (A): a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT) and 2-methyl-4-isothiazolin-3-one (MIT);

component (B): a chloramine compound;

component (C): a stabilizing bromide;

component (D): glutaraldehyde.

[2] The slime control method for a reverse osmosis membrane apparatus according to the above [1], wherein the chloramine compound as the component (B) is at least one selected from the group consisting of a component (B-1) and a component (B-2), the component (B-1) is chloramine consisting of an ammonium salt and chlorine, and the component (B-2) is at least one selected from the group consisting of chloroaminosulfonic acid and chloroaminosulfonate.

[3] The method for inhibiting slime in a reverse osmosis membrane apparatus according to the above [1] or [2], wherein the water passing step further includes a second water passing step of passing water to be treated, which does not contain the slime inhibitor X and the slime inhibitor Y, through the reverse osmosis membrane.

[4] The slime controlling method of a reverse osmosis membrane apparatus according to any one of [1] to [3], wherein in the water passing step, the number of times of water passing in the first water passing step is 1 to 14 times per week, and the water passing time per one time of water passing is 1 hour or less.

[5] The method for inhibiting slime in a reverse osmosis membrane apparatus according to [4], wherein the first water passing step comprises passing water once a day.

[6] The slime controlling method of a reverse osmosis membrane apparatus according to any one of the above [1] to [5], wherein the first water passing step is performed under at least one condition selected from the group consisting of the following operation conditions 1 to 4,

operating conditions 1: operating conditions under which the permeate water and the concentrated water are not separated and are taken out only in the form of concentrated water;

operating conditions 2: operating conditions under which the permeate water and the concentrated water are separated and taken out separately and the permeate water is discarded;

operating conditions 3: operating conditions of raw water separated into permeate water and concentrate water, taken out separately, and returned to the reverse osmosis membrane apparatus;

operating conditions 4: the raw water is separated into the permeated water and the concentrated water, and the permeated water and the concentrated water are respectively taken out and returned to the reverse osmosis membrane device.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the slime control method of a reverse osmosis membrane device of the present invention, an effect of controlling slime (biofilm) generation and an effect of removing slime (biofilm) even if slime (biofilm) is generated and adheres to a reverse osmosis membrane surface are obtained in a short time.

Drawings

Fig. 1 is a diagram showing an application example of a slime control method in a reverse osmosis membrane apparatus according to the present invention.

Fig. 2 is a system diagram of an apparatus simulating a reverse osmosis membrane apparatus used in an evaluation test of slime-inhibiting effect.

FIG. 3 is a schematic view of a multi-well plate used for measuring the amount of microorganisms adhered.

Detailed Description

Next, a slime control method applied to a reverse osmosis membrane apparatus of the present invention including a water passing step of passing water to be treated through a reverse osmosis membrane will be described in detail.

[ slime control method for reverse osmosis membrane apparatus ]

A slime control method for a reverse osmosis membrane apparatus according to the present invention is a slime control method applied to a reverse osmosis membrane apparatus, comprising a water passage step of passing water to be treated through a reverse osmosis membrane, wherein the water passage step comprises a first water passage step of passing water to be treated containing a slime inhibitor X and a slime inhibitor Y through the reverse osmosis membrane, the water to be treated containing the slime inhibitor X and the slime inhibitor Y being obtained by adding the slime inhibitor X containing 2, 2-dibromo-3-nitrilopropionamide (DBNPA) and the slime inhibitor Y containing at least one selected from the group consisting of the following components (A) to (D) to water to be treated having a pH of 10 or less,

component (A): a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT) and 2-methyl-4-isothiazolin-3-one (MIT);

component (B): a chloramine compound;

component (C): a stabilizing bromide;

component (D): glutaraldehyde.

According to the slime control method of the reverse osmosis membrane device, the effect of controlling slime (biofilm) generation and the effect of removing slime (biofilm) even if slime (biofilm) is generated and attached to the reverse osmosis membrane surface can be obtained in a short time.

The detailed mechanism of the effect obtained by the present invention is not clear, and it is presumed that the function of removing the adhesive component surrounding the microorganisms in the slime (biofilm) is excellent even when the slime (biofilm) is generated by using 2, 2-dibromo-3-nitrilopropionamide (DBNPA) as the slime inhibitor X and the slime inhibitor Y specified in the present invention in combination and passing the water to be treated containing the slime inhibitor X and the slime inhibitor Y through the reverse osmosis membrane.

Fig. 1 shows an application example of the slime control method of the reverse osmosis membrane apparatus according to the present invention.

As shown in fig. 1, the method for inhibiting slime in a reverse osmosis membrane apparatus according to the present invention may include a pretreatment step before a water passing step of passing water to be treated through a reverse osmosis membrane of the reverse osmosis membrane apparatus.

As the pretreatment step, for example, a step of filtering raw water (water to be treated) in a raw water tank by a filter device and passing the filtered water through a filtration treatment tank and a safety filter may be mentioned.

The slime control method of the reverse osmosis membrane apparatus according to the present invention may include the pretreatment step, but is not essential, and even if the method does not include the pretreatment step, the method can obtain the effect of controlling the production of slime (biofilm) in a short time and the effect of removing the slime (biofilm) even if the slime (biofilm) is produced and adheres to the reverse osmosis membrane surface by passing through the water passing step specified in the present invention.

(1) Water passing step

The water passing step of the present invention may include a first water passing step of passing water to be treated containing the slime inhibitor X and the slime inhibitor Y through a reverse osmosis membrane, and may further include a second water passing step of passing water to be treated not containing the slime inhibitor X and the slime inhibitor Y through a reverse osmosis membrane.

(1-1) first Water-passing step

In the first water passing step, water to be treated containing the slime inhibitor X and the slime inhibitor Y is passed through a reverse osmosis membrane of a reverse osmosis membrane apparatus.

The damage of the reverse osmosis membrane by the slime inhibitor X and the slime inhibitor Y is within a negligible level or a tolerable range.

The method for adding the slime inhibitor X and the slime inhibitor Y to the water to be treated is not particularly limited, and the timing of adding the slime inhibitor X and the slime inhibitor Y may be appropriately varied in consideration of the fact that the slime inhibitor X and the slime inhibitor Y contained in the water to be treated reach the reverse osmosis membrane simultaneously.

For example, as shown in application example 1 shown in fig. 1, a method of adding the slime inhibitor X and then adding the slime inhibitor Y to the water to be treated which is passed through at a predetermined speed may be mentioned. As an example, a method of adding the slime inhibitor Y1, then adding the slime inhibitor X, and then adding the slime inhibitor Y2 to the water to be treated, which was passed through at a predetermined speed, as in application example 2 shown in fig. 1, may be mentioned. Here, the slime inhibitors Y1 and Y2 are specific slime inhibitors Y of different types in the present invention.

The order of adding the slime inhibitor X and the slime inhibitor Y is not particularly limited, and for example, as in application example 1 of fig. 1, the order of adding the slime inhibitor X and then adding the slime inhibitor Y may be reversed, or the slime inhibitor X and the slime inhibitor Y may be added almost simultaneously. In addition, as shown in application example 2 of fig. 1, two or more types of the slime inhibitor Y specified in the present invention may be used.

The timing of adding the slime inhibitor X and the slime inhibitor Y is not particularly limited as long as the slime inhibitor X and the slime inhibitor Y are contained in the water to be treated when the water to be treated comes into contact with the reverse osmosis membrane, and may be immediately after the start of the water flow of the water to be treated or immediately before the water to be treated comes into contact with the reverse osmosis membrane.

The pH of the water to be treated to which the slime inhibitor X and the slime inhibitor Y are added is 10 or less, preferably 9.0 to 3.0, and more preferably 8.0 to 5.0.

When the pH of the water to be treated is higher than the above range (pH is higher than 10), 2-dibromo-3-nitrilopropionamide (DBNPA) as the slime inhibitor X is hydrolyzed, and there is a possibility that the effect of inhibiting the generation of slime (biofilm) cannot be obtained.

The pH in the present specification means a pH value according to JIS Z8802: 2011 is a value obtained based on the operation of the glass electrode method.

The pH can be corrected by using each pH standard solution of phthalate, neutral phosphate, and carbonate.

< slime inhibitor X >

The slime inhibitor X in the present invention contains 2, 2-dibromo-3-nitrilopropionamide (DBNPA), and may contain other components.

Since 2, 2-dibromo-3-nitrilopropionamide (DBNPA) is a lipophilic powder and has low solubility in water, it is preferable to prepare a DBNPA mixture using a solvent having lipophilic and hydrophilic properties.

The solvent having lipophilic and hydrophilic properties to be mixed with DBNPA is not particularly limited, and examples thereof include glycols such as diethylene glycol, tetraethylene glycol, and polyethylene glycol; ethers such as diethylene glycol monomethyl ether.

In addition, for the purpose of making ignition difficult, pure water may be optionally added to 2, 2-dibromo-3-nitrilopropionamide (DBNPA) together with a solvent having lipophilic and hydrophilic properties as required.

When DBNPA is prepared as a DBNPA mixture using a solvent having lipophilic and hydrophilic properties and pure water, the DBNPA content is preferably 5 to 35 mass%, more preferably 10 to 30 mass%, and still more preferably 15 to 25 mass% in the total amount (100 mass%) of the DBNPA mixture.

The content of the lipophilic and hydrophilic solvent in the total amount (100 mass%) of the DBNPA mixture is preferably 30 to 80 mass%, more preferably 40 to 60 mass%, and still more preferably 45 to 55 mass%.

The pure water content is preferably 15 to 45 mass%, more preferably 20 to 40 mass%, and still more preferably 25 to 35 mass% of the total amount (100 mass%) of the DBNPA mixed solution.

When DBNPA is prepared as a DBNPA mixture using a solvent having lipophilic and hydrophilic properties without using pure water, the content of DBNPA in the total amount (100 mass%) of the DBNPA mixture is preferably 20 to 50 mass%, more preferably 25 to 45 mass%, and still more preferably 30 to 40 mass%.

The content of the lipophilic and hydrophilic solvent in the total amount (100 mass%) of the DBNPA mixture is preferably 50 to 80 mass%, more preferably 55 to 75 mass%, and still more preferably 60 to 70 mass%.

If DBNPA is present in the water to be treated having a high pH, hydrolysis proceeds, and the effect of inhibiting slime generation and the slime removing effect of the slime inhibitor X may be reduced. Therefore, the pH of the water to be treated used in the first water passage step needs to be 10 or less.

The slime inhibitor X is added to ensure that the concentration of DBNPA kept in the system is preferably 3-80 mg/L (calculated by DBNPA), more preferably 5-60 mg/L (calculated by DBNPA), and further preferably 10-40 mg/L (calculated by DBNPA).

In the present specification, the term "concentration maintained in the system" means the content of the target component contained in 1L of the water to be treated, which is passed at a predetermined flow rate, and the same applies hereinafter.

By maintaining the DBNPA concentration in the system within the above range, the effect of inhibiting the generation of slime (biofilm) and the effect of removing slime (biofilm) even if slime (biofilm) is generated and adheres to the reverse osmosis membrane surface can be easily obtained in a short time.

(other Components)

The slime inhibitor X in the present invention contains 2, 2-dibromo-3-nitrilopropionamide (DBNPA), and may contain other components such as an anti-scale component and pure water.

Examples of the scale inhibitor include polyacrylic acid or its sodium salt, a copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, a vinyl acetate-alkyl acrylate-maleic anhydride copolymer, a sodium salt of a 2-acrylamido-2-methylpropanesulfonic acid-acrylic acid-N-t-butylacrylamide terpolymer, phosphinocarboxylic acid, phosphonic acid, or a phosphonate.

< slime inhibitor Y >

The slime inhibitor Y in the present invention contains at least one selected from the group consisting of the following components (a) to (D), and may contain other components,

component (A): a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT) and 2-methyl-4-isothiazolin-3-one (MIT);

component (B): a chloramine compound;

component (C): a stabilizing bromide;

component (D): glutaraldehyde.

(component (A): a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT) and 2-methyl-4-isothiazolin-3-one (MIT))

The content of 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT) contained in the component (A) is preferably 0.3 to 14% by mass, more preferably 0.4 to 13% by mass, and still more preferably 0.5 to 12% by mass, based on the total amount of the component (A).

The content of 2-methyl-4-isothiazolin-3-one (MIT) in the total amount of the component (a) is preferably 0.09 to 4.2 mass%, more preferably 0.12 to 3.9 mass%, and still more preferably 0.15 to 3.6 mass%.

In the total amount (100 mass%) of the active ingredients of the component (a), the total amount of Cl-MIT and MIT is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and still more preferably 95 to 100 mass%.

The component (A) may be diluted with pure water or a solvent.

As the component (A), commercially available products can also be used.

Examples of commercially available component (A) include "KATHON WT" and "KATHON WTA" manufactured by Nippon Kagaku K.K. (ダウ, ケミカル, Japan K.K.). KATHON WT contains about 10.4 mass% Cl-MIT and about 3.5 mass% MIT. Further, KATHON WTA contains about 1.1 mass% of Cl-MIT and about 0.4 mass% of MIT.

The component (A) is added so that the concentration of Cl-MIT (as Cl-MIT) in the system is preferably 0.5 to 15mg/L, more preferably 1.0 to 5.0mg/L, and further preferably 1.0 to 2.0mg/L (as Cl-MIT). Here, the reason why the concentration of Cl-MIT is defined in the system is that the effect of suppressing slime of the component (A) is mainly attributed to Cl-MIT.

By maintaining the concentration of the component (a) in the system within the above range, the effect of inhibiting the generation of slime (biofilm) and the effect of removing slime (biofilm) by using DBNPA as a slime inhibitor X can be easily obtained in a short time even if slime (biofilm) is generated and adheres to the reverse osmosis membrane surface. The reason for this is considered to be that the slime-inhibiting effect of the heterogeneous membrane on the reverse osmosis membrane surface shows a synergistic effect.

(component (B): a chloramine compound)

The chloramine compound refers to a compound having a bond of at least one nitrogen atom to a chlorine atom (N — Cl bond).

The chloramine compound is at least one selected from the group consisting of component (B-1) and component (B-2), wherein component (B-1) is preferably chloramine consisting of ammonium salt and chlorine, and component (B-2) is preferably at least one selected from the group consisting of chloroaminosulfonic acid and chloroaminosulfonate.

Examples of the ammonium salt include ammonium sulfate, ammonium nitrate, and ammonium chloride. Among them, ammonium sulfate is preferable.

Chloroaminosulfonic acid means the substitution of sulfamic acid (H) with chlorine atom₂NSO₂OH) NH of₂At least one hydrogen atom in the radical. Examples of the chloroaminosulfonic acid include monochloroaminosulfonic acid and dichlorosulfamic acid.

Chlorosulfamate refers to the replacement of sulfamic acid (H) with a metal ion (e.g., lithium, sodium, potassium)₂NSO₂OH) at least one hydrogen atom in the OH group. Examples of the chloroaminosulfonate include lithium chloroaminosulfonate, sodium chloroaminosulfonate, potassium chloroaminosulfonate, and the like. Among them, sodium chloroaminosulfonate is preferable.

As another chloramine compound, chloramine T or the like can be used.

Examples of the production of sodium chloroaminosulfonate include the method described in example 1 of japanese patent No. 5720964.

The component (B-1), namely chloramine consisting of ammonium salt and chlorine, is added so that the concentration of chlorine (in terms of Cl) in the system is preferably 0.5-7.0 mg/L₂Calculated by Cl), more preferably 0.5 to 5.0mg/L (calculated by Cl)₂In terms of Cl), more preferably 1.0 to 3.0mg/L (in terms of Cl)₂Meter).

By maintaining the concentration of the component (B-1) in the system within the above range, the effect of suppressing the generation of slime (biofilm) and the effect of removing slime (biofilm) by using DBNPA as a slime inhibitor X can be easily obtained in a short time even if slime (biofilm) is generated and adheres to the reverse osmosis membrane surface.

Adding component (B-2), i.e. chloro-sulfamic acid orA chloroaminosulfonate so that the concentration of chlorine in the system is preferably 0.5 to 8.0mg/L (as Cl)₂Calculated by Cl), more preferably 0.5 to 6.0mg/L (calculated by Cl)₂In terms of Cl), more preferably 1.0 to 4.0mg/L₂Meter).

By maintaining the concentration of the component (B-2) in the system within the above range, the effect of inhibiting the generation of slime (biofilm) and the effect of removing slime (biofilm) by using DBNPA as a slime inhibitor X even if slime (biofilm) is generated and attached to the reverse osmosis membrane surface can be easily obtained in a short time. The reason for this is considered to be that the effect of inhibiting slime which is heterogeneous on the reverse osmosis membrane surface shows a synergistic effect.

(component (C): stabilized bromide)

The stabilized bromide is a bromide which is less likely to change in water due to decomposition or the like and in which the produced bromide is stably present in water.

Examples of the stabilized bromide include a reaction product of a "bromine-based oxidizing agent or a reaction product of a bromine compound and a chlorine-based oxide" and a "sulfamic acid compound".

Examples of the bromine-based oxidizing agent include bromine (liquid bromine), bromine chloride, bromic acid, bromate, and hypobromous acid.

Examples of the bromine compound include sodium bromide, potassium bromide, lithium bromide, ammonium bromide, and hydrobromic acid.

Examples of the chlorine-based oxide include chlorine gas, chlorine dioxide, hypochlorous acid or a salt thereof, chlorous acid or a salt thereof, chloric acid or a salt thereof, perchloric acid or a salt thereof, chloroisocyanuric acid or a salt thereof, and the like.

Examples of the hypochlorite include alkali metal hypochlorite such as sodium hypochlorite and potassium hypochlorite; alkali earth hypochlorite metal salts such as calcium hypochlorite and barium hypochlorite.

Examples of the chlorite include alkali metal chlorite salts such as sodium chlorite and potassium chlorite; alkaline earth metal chlorite salts such as barium chlorite; other metal salts of chlorous acid such as nickel chlorous acid.

Examples of the chlorate salt include ammonium chlorate; alkali metal chlorate such as sodium chlorate and potassium chlorate; alkaline earth metal chlorate such as calcium chlorate and barium chlorate, and the like.

Examples of the perchlorate include sodium perchlorate and potassium perchlorate.

Examples of the chloroisocyanurate include sodium chloroisocyanurate.

The sulfamic acid compound is a compound represented by the following general formula (1).

R₂NSO₂OH(1)

(in the formula (1), R is independently a hydrogen atom or an alkyl group having 1-8 carbon atoms.)

Examples of the sulfamic acid compound include sulfamic acid (amidosulfonic acid) in which both R groups are hydrogen atoms, or a salt thereof; sulfamic acid or a salt thereof in which one of two R groups, such as N-methylaminosulfonic acid, N-ethylaminosulfonic acid, N-propylaminosulfonic acid, N-isopropylaminosulfonic acid, and N-butylaminosulfonic acid, is a hydrogen atom and the other is an alkyl group having 1 to 8 carbon atoms; and sulfamic acids or salts thereof in which both R groups are alkyl groups having 1 to 8 carbon atoms, such as N, N-dimethylsulfamic acid, N-diethylaminosulfonic acid, N-dipropylaminosulfonic acid, N-dibutylaminosulfonic acid, N-methyl-N-ethylaminosulfonic acid, and N-methyl-N-propylsulfamic acid.

Examples of the sulfamate include alkali metal salts such as sodium salts and potassium salts; alkaline earth metal salts such as calcium salts, strontium salts, barium salts, etc.; manganese salt, copper salt, zinc salt, iron salt, cobalt salt, nickel salt and other metal salts; an ammonium salt; guanidine salts and the like.

An example of the production of the stabilized bromide is a method in which, for example, an aqueous sodium bromide solution and an aqueous sodium hypochlorite solution are mixed to form a mixed solution 1, while an aqueous sulfamic acid solution and an aqueous sodium hydroxide solution are mixed to form a mixed solution 2, and the mixed solution 1 and the mixed solution 2 are mixed.

The component (C), namely the stabilized bromide, is added so that the concentration of the compound to be maintained in the system is preferably 0.1 to 7.0mg/L (as Cl) in terms of the total chlorine concentration₂Calculated by Cl), more preferably 0.2 to 5.0mg/L (calculated by Cl)₂In terms of m), more preferably 0.3 to 3.0mg/L (as Cl)₂Meter).

By maintaining the concentration of the component (C) in the system within the above range, an effect of suppressing slime (biofilm) generation and an effect of removing slime (biofilm) by using DBNPA as a slime inhibitor X can be easily obtained in a short time even if slime (biofilm) is generated and adheres to the reverse osmosis membrane surface. The reason for this is considered to be that the effect of inhibiting slime which is heterogeneous on the reverse osmosis membrane surface shows a synergistic effect.

(component (D): glutaraldehyde)

For glutaraldehyde, it is preferable to use water as a glutaraldehyde solution in order to maintain the stability of the active ingredient.

When glutaraldehyde is prepared into a glutaraldehyde solution using water, the content of glutaraldehyde is preferably 5 to 70 mass%, more preferably 10 to 60 mass%, and still more preferably 15 to 55 mass% in the total amount (100 mass%) of the glutaraldehyde solution.

Commercially available glutaraldehyde solutions can also be used.

Examples of commercially available glutaraldehyde solutions include "glutaraldehyde solution (glutaraldehyde content: 50% by mass, water content: 50% by mass)" produced by shoita chemical corporation (KISHIDA CHEMICAL co., Ltd.).

The component (D) is added so that the concentration of glutaraldehyde in the system is preferably 10 to 200mg/L (based on glutaraldehyde), more preferably 20 to 150mg/L (based on glutaraldehyde), and still more preferably 30 to 100mg/L (based on glutaraldehyde).

By maintaining the concentration of the component (D) in the system within the above range, the effect of inhibiting the generation of slime (biofilm) and the effect of removing slime (biofilm) by using DBNPA as a slime inhibitor X can be easily obtained in a short time even if slime (biofilm) is generated and adheres to the reverse osmosis membrane surface. The reason for this is considered to be that the effect of inhibiting slime which is heterogeneous on the reverse osmosis membrane surface shows a synergistic effect.

(combination of 2 or more specific slime inhibitors Y of the present invention)

The specific slime inhibitor Y in the present invention contains at least one selected from the group consisting of the components (a) to (D), and may contain 2 or more selected from the group consisting of the components (a) to (D).

In the case where the specific slime inhibitor Y is contained in 2 or more selected from the group consisting of the components (a) to (D) in the present invention, the 2 or more slime inhibitors Y may be mixed in a solvent to prepare 1 kind of drug, or the 2 or more slime inhibitors Y may be mixed in different solvents to prepare 2 or more drugs.

(other Components)

The slime inhibitor Y in the present invention contains at least one selected from the group consisting of the following components (a) to (D), and may contain other components.

Examples of the other components include polyacrylic acid or a sodium salt thereof, a copolymer of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid, a vinyl acetate-alkyl acrylate-maleic anhydride copolymer, a sodium salt of a 2-acrylamide-2-methylpropanesulfonic acid-acrylic acid-N-t-butylacrylamide terpolymer, a phosphinocarboxylic acid, a phosphonic acid, a phosphonate, and other scale-preventing components.

(1-2) second Water passage Process

The water passing step of the present invention preferably includes a second water passing step of passing the water to be treated, which does not contain the slime inhibitor X and the slime inhibitor Y, through the reverse osmosis membrane without adding the slime inhibitor X and the slime inhibitor Y to the reverse osmosis membrane apparatus mainly intended for the production of drinking water, the production of pure water, and the like, in addition to the first water passing step.

The first water passing step is a step mainly aimed at suppressing the generation of slime, whereas the second water passing step is a step mainly aimed at the production of drinking water, the production of pure water, and the like, in which the addition of chemicals is stopped to avoid a trace amount of chemicals remaining in permeated water.

In the water passing step, when the number of times of water passing in the first water passing step of passing water to be treated through the reverse osmosis membrane is 1 to 14 times per week and the main purposes of production of drinking water, production of pure water, and the like are mainly concerned, the water passing time per one time of the water passing is preferably 1 hour or less, more preferably 0.7 hour or less, and further preferably 0.5 hour or less.

The number of times of water passage in the first water passage step is preferably once per day.

Even if the water passage time in the first water passage step is short, i.e., within the above range (1 hour or less), the effect of suppressing the generation of slime (biofilm) and the effect of removing slime (biofilm) even if slime (biofilm) is generated and adheres to the reverse osmosis membrane surface can be obtained.

When the water passage step includes the second water passage step, the water passage time in the second water passage step can be secured to a greater extent by setting the water passage time in the first water passage step to the above range (1 hour or less). Accordingly, more permeated water can be obtained by the separation step which is a subsequent step of the water passing step, and therefore, productivity of production of drinking water, production of pure water, and the like can be remarkably improved.

When the water passing step includes the second water passing step, the water to be treated which does not contain the slime inhibitor X and the slime inhibitor Y is passed through the reverse osmosis membrane in the second water passing step, and therefore the permeated water obtained by separating the water to be treated which has passed through the second water passing step can be suitably used for drinking water, pure water, and the like.

On the other hand, in the first water passing step included in the water passing step, the water to be treated containing the slime inhibitor X and the slime inhibitor Y is passed through the reverse osmosis membrane, and therefore, the water to be treated which has been subjected to the first water passing step is separated to obtain a water that is not desirable for use in drinking water, pure water, or the like.

Therefore, in the first water passing step, the operation is preferably performed under at least one condition selected from the group consisting of the following operation conditions 1 to 4.

Operating conditions 1: operating conditions under which the permeate water and the concentrated water are not separated and are taken out only in the form of concentrated water;

operating conditions 2: operating conditions under which the permeate water and the concentrated water are separated and taken out separately and the permeate water is discarded;

operating conditions 3: operating conditions of raw water separated into permeate water and concentrate water, taken out separately, and returned to the reverse osmosis membrane apparatus;

operating conditions 4: the raw water is separated into the permeated water and the concentrated water, and the permeated water and the concentrated water are respectively taken out and returned to the reverse osmosis membrane device.

The slime control method of a reverse osmosis membrane apparatus according to the present invention can also be realized by a control unit including a CPU or the like in an apparatus (for example, a personal computer) for managing the quality of water to be treated as a treatment target.

The slime control method of the reverse osmosis membrane device according to the present invention can be implemented by the control unit by storing the slime control method in a hardware resource including a recording medium (a nonvolatile memory (such as a USB memory), an HDD, a CD, or the like) as a program. The control unit may provide a slime control system of a reverse osmosis membrane apparatus that controls the amount, timing, and the like of adding the slime inhibitor X and the slime inhibitor Y to the water to be treated.

Examples

The present invention is further specifically illustrated by the following examples, but the present invention is not limited to these examples.

[ preparation of slime inhibition test ]

(1) Treated water

Tap water (hereinafter, referred to as "komatsu water") collected at 29.3.2016 of japan, yagi city of japan was used as raw water.

The quality of the wild street water at this time was such that the Total Organic Carbon (TOC) concentration was 0.93mg/L, the nitrate ion concentration was 11mg/L, and the orthophosphoric acid concentration in terms of phosphorus was 11.9 mass ppb.

Chlorine contained in the wakame city water was removed by an activated carbon filter filled with granular activated carbon ("Kuricole (クリコール) a-WG", manufactured by kukota industries co., ltd.) to obtain water to be treated. The pH of the water to be treated is 7.1 to 7.5.

The water to be treated was measured by the following [ measurement/evaluation method ]](1) Determination of Total chlorine concentrationAs a result, the total chlorine concentration was less than 0.05mg/L (as Cl)₂Meter) (less than detection lower limit).

(2) Nutrient agent

For the purpose of proliferating slime (biofilm) in a short period of time, the following nutrients were used in the system.

The nutrient was prepared using purified water such that acetic acid was 1063mg/L, potassium monohydrogen phosphate was 75mg/L, and sodium dihydrogen phosphate dihydrate was 19 mg/L.

(3) Slime inhibitor X

As the slime inhibitor X, the following reagents were used.

DBNPA reagent

A DBNPA reagent having DBNPA of 20 mass%, tetraethylene glycol of 50 mass%, and pure water of 30 mass% was prepared by mixing 2, 2-dibromo-3-nitrilopropionamide (DBNPA) with tetraethylene glycol as a solvent having lipophilic and hydrophilic properties, and pure water.

(4) Slime inhibitor Y

As the slime inhibitor Y, the following reagents were used.

(4-1) component (A): mixture reagent of Cl-MIT and MIT

As a mixture reagent of 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT) and 2-methyl-4-isothiazolin-3-one (MIT), "KATHON WT" manufactured by Tao chemical Japan K.K. (ダウ. ケミカル Japan K.K.) was used. The reagent contained about 10.4 mass% of Cl-MIT and about 3.5 mass% of MIT.

(4-2) component (B-1): chloramine reagent consisting of ammonium salt and chlorine

1.24g of ammonium sulfate (manufactured by Shoitan chemical Co., Ltd.) was added to 800mL of pure water and mixed, and 2.5g of an aqueous solution of sodium hypochlorite (manufactured by Asahi glass Co., Ltd.) having an effective chlorine concentration of 12 mass% was added and mixed to prepare a mixed solution. Finally, pure water was added to the mixed solution to prepare 1L of chloramine reagent consisting of ammonium salt and chlorine. The total chlorine concentration of this reagent was 300mg/L (as Cl)₂Meter).

(4-3) component (B-2): mono-chloro-amino-sodium sulfonate reagent

An aqueous sodium hydroxide solution was prepared using pure water so that sodium hydroxide (manufactured by shoitan chemical corporation) was 48% by mass. 19.5g of the aqueous sodium hydroxide solution prepared in advance was mixed with 7.5g of pure water, and 15.0g of sulfamic acid (manufactured by Shoitan chemical Co., Ltd.) was added and mixed. Then, 58.0g of sodium hypochlorite (manufactured by Asahi glass Co., Ltd.) having an effective chlorine concentration of 12 mass% was added thereto and mixed to prepare a monochloro sulfamic acid reagent. The total chlorine concentration of the reagent was 7 mass% (as Cl)₂Meter).

(4-4) component (C): stabilized bromide reagent

An aqueous sodium bromide solution was prepared using pure water so that sodium bromide (manufactured by seitan chemical corporation) was 45 mass%. Then, 63.6g of sodium hypochlorite (manufactured by Asahi glass company, Asahi glass Co., Ltd.) having a concentration of 12 mass% and 30.8g of a previously prepared sodium bromide aqueous solution were mixed to prepare a mixed solution 1.

An aqueous sodium hydroxide solution was prepared using pure water so that sodium hydroxide (manufactured by shoitan chemical corporation) was 48% by mass.

On the other hand, 14.4g of sulfamic acid (manufactured by Shoitan chemical Co., Ltd.) and 20.2g of pure water were mixed, and 20.7g of a previously prepared aqueous sodium hydroxide solution was further mixed to prepare a mixed solution 2.

Subsequently, the mixed solution 1 and the mixed solution 2 are mixed to prepare a stabilized bromide reagent. The total chlorine concentration of the reagent was 5 mass% (as Cl)₂Meter).

(4-5) component (D): glutaraldehyde reagent

As the glutaraldehyde reagent, "glutaraldehyde solution (glutaraldehyde content: 50 mass%, water content: 50 mass%) produced by Nikka chemical Co., Ltd" was used.

(5) Simulation device used in slime inhibition test

Fig. 2 is a system diagram of an apparatus simulating a reverse osmosis membrane apparatus used in an evaluation test of the effect of inhibiting slime.

With a commercially available 1/4 inch two-joint (diameter of inner diameter: 13.8mm, length: 26mm, inner surface area: about 11 cm)²) As a testThe sheet is housed within the column of the simulation device shown in figure 2. By the [ measuring/evaluating method ] described later](2) The method for measuring/evaluating the amount of microorganisms adhered to the inner surface of the test piece was carried out to evaluate the slime-inhibiting effect of examples 1 to 5 and comparative examples 1 to 2.

As shown in fig. 2, the simulation apparatus was operated without using the slime inhibitor X, Y in the first system (comparative example 1), with using only the slime inhibitor X in the second system (comparative example 2), and with using the slime inhibitor X, Y in the third system (examples 1 to 5).

(example 1)

The third system using the simulation apparatus shown in FIG. 2 was opened, and the water to be treated (raw water) prepared as described above was passed through the system for 7 days at a rate of 1.7L/min. Further, the above-prepared nutrient was added to the treated water under the condition of 1 mL/min for 7 consecutive days, and the above-prepared DBNPA reagent was added as a slime inhibitor X at a frequency of 30 minutes 1 time per day so that the in-system maintenance concentration of DBNPA was 10mg/L (in terms of DBNPA), and the above-prepared component (B-2) sodium monochlorosulfamate reagent was added as a slime inhibitor Y so that the in-system maintenance concentration was 2.4mg/L (in terms of Cl) in terms of total chlorine concentration₂Meter).

(example 2)

A water-passing step was carried out in the same manner as in example 1 except that the kind of the slime inhibitor Y in example 1 was changed to the component (a), i.e., the mixture reagent of Cl-MIT and MIT, and the concentration of the retained solution was changed to Cl-MIT and was 1.5mg/L (in terms of Cl-MIT), thereby obtaining a slime inhibition test in example 2.

(example 3)

The kind of slime inhibitor Y in example 1 was changed to a chloramine reagent consisting of an ammonium salt and chlorine as the component (B-1), and the concentration of the chloramine reagent was changed so that the system was maintained at 2.0mg/L (as Cl) in terms of the total chlorine concentration₂Except for the above), the water passage step was performed in the same manner as in example 1 to prepare a slime control test in example 3.

(example 4)

The kind of slime inhibitor Y in example 1 was changedThe stabilized bromide reagent which is the component (C) is further added, and the concentration of the stabilized bromide reagent is changed to 1.0mg/L (as Cl) in terms of the total chlorine concentration₂Except for the above), the water passage step was performed in the same manner as in example 1 to prepare a slime control test in example 4.

(example 5)

A water-passing step was carried out in the same manner as in example 1 except that the kind of the slime inhibitor Y in example 1 was changed to the glutaraldehyde reagent as the component (D) and the concentration of the retained water in the system was changed to glutaraldehyde 50.0mg/L (based on glutaraldehyde), thereby obtaining a slime inhibition test in example 5.

Comparative example 1

A water-passing step was performed in the same manner as in example 1 except that the system of example 1 was changed to the first system of the simulation apparatus shown in fig. 2 and the slime inhibitors X and Y were not added, to obtain a slime inhibition test of comparative example 1.

Comparative example 2

A water flow-through process was performed in the same manner as in example 1 except that in example 1, the second system of the simulation apparatus shown in fig. 2 was changed, and that a slime inhibitor X was added and a slime inhibitor Y was not added at a frequency of 1 time per day for 1 hour, thereby obtaining a slime inhibition test in comparative example 2.

[ measurement/evaluation methods ]

(1) Method for measuring total chlorine concentration

Total chlorine concentration (mg/L, as Cl) of chloramine compound, stabilized bromide₂Meter) can be measured by colorimetric analysis (DPD method) using potassium iodide and DPD reagents. In this example, the light absorption of the sample at a specific wavelength after 300 seconds by DPD (total amount) reagent as a total chlorine detecting reagent was measured by using a portable residual chlorine meter ("HACH 2470" manufactured by HACH corporation). The DPD method can measure total bromine in addition to total chlorine, and in the present specification, the total bromine concentration is calculated by converting the total bromine concentration into the total chlorine concentration.

(2) Method for measuring/evaluating microbial adhesion amount

After the water passage steps of examples 1 to 5 and comparative examples 1 to 2 were performed, the test pieces contained in the respective columns were taken out, and the effect of suppressing slime (biofilm) generation was evaluated by measuring the luminescence amount (RLU) according to the following steps 1 to 8. The results are shown in table 1.

The luminescence amount (RLU) indicates the amount of ATP (adenosine triphosphate), and the higher the number of surviving bacteria, the higher the value, and therefore, it can be used as an index indicating the amount of slime (biofilm) produced.

Step 1: 1mL of ultrapure water was injected into each of wells 1-1, 2-1, and 3-1 of a multi-well plate (manufactured by KANGNING corporation (コーニング Co., Ltd.) "a 24-well flat-bottom TC-treated multi-well cell culture plate") shown in FIG. 3.

Step 2: the slime adhered to the inner surface of each test piece was wiped off with a sterilized cotton swab.

And step 3: the swab was placed in hole 1-1 and shaken.

And 4, step 4: next, the swab is placed in hole 2-1 and shaken, and then the swab is placed in hole 3-1.

And 5: transfer 100. mu.L of the liquid in well 1-1 to well 1-2 for measurement, and transfer 100. mu.L of the liquid in well 1-1 to well 1-3 for measurement. Similarly, 100. mu.L of the liquid in well 2-1 was transferred to well 2-2 for measurement, and 100. mu.L of the liquid in well 2-1 was transferred to well 2-3 for measurement. Further, 100. mu.L of the liquid in the well 3-1 was transferred to the well 3-2 for measurement, and 100. mu.L of the liquid in the well 3-1 was transferred to the well 3-3 for measurement.

Step 6: to each of the wells 1-2, 1-3, 2-2, 2-3, 3-2 and 3-3 for measurement, 10. mu.L of an ATP luminescent reagent ("Lucifer 250Plus (ルシフェール 250 プラス)", manufactured by Kikkoman Biochemifa Company, キッコーマンバイオケミファ) was added.

And 7: the samples from each well were transferred to a test tube and placed in a vortex mixer and the samples were stirred.

And 8: a photometer ("Lumitester C-110", manufactured by Tortoise Shell Kamikamikawa K.K.) was used within 20 seconds after the stirring to measure 6 of each of wells 1-2, 1-3, 2-2, 2-3, 3-2, and 3-3The luminescence amount (relative light unit; RLU) of each internal liquid was measured, the average luminescence amount was obtained, and the average luminescence amount (RLU/cm) per unit internal surface area of the test piece was calculated²)。

The average luminescence amount per unit internal surface area (RLU/cm) of the test piece of comparative example 1²) As 100, the calculated values of the average luminescence amounts (RLU/cm) in examples 1 to 5 and comparative example 2 were each converted²) Indexing is performed.

The above average luminescence amount (RLU/cm)²) The smaller the index of (b), the higher the effect of inhibiting slime (biofilm) production can be evaluated.

TABLE 1

(summary of results)

The following can be seen from the evaluation results shown in table 1.

With comparative example 1, the absence of the slime inhibitor X and the slime inhibitor Y resulted in failure to obtain the effect of inhibiting the production of slime and the effect of removing slime.

On the other hand, in comparative example 2, although the effect of inhibiting the generation of slime and the effect of removing slime were obtained by using the slime inhibitor X, the time of addition per time under the condition of 1 pass/24 hours in the first water passing step was 1 hour.

In contrast, in examples 1 to 5, it was confirmed that: the combined use of the slime inhibitor X and the slime inhibitor Y can obtain an effect of inhibiting the production of slime and an effect of removing slime, although the time per addition under the condition of 1 time/24 hours of the first water passing process is half of the time in comparative example 2, that is, 30 minutes, and the obtained effect is equal to or higher than the level of comparative example 2.