Operation method of reverse osmosis membrane device

Abstract

The present invention provides a technology that enables stable operation of a water system having a reverse osmosis membrane device for a longer period of time. The present invention provides a method for treating water containing an oxidative slime inhibitor by intermittently adding the oxidative slime inhibitor to a reverse osmosis membrane device. A method for operating a reverse osmosis membrane device can be provided, which includes a second step of adding an organic slime inhibitor at least during a period other than the addition period of the first step, and supplying the treated water containing the organic slime inhibitor to the reverse osmosis membrane device.

Description

Technical Field

[0001] The present invention relates to an operation method of a reverse osmosis membrane device, a slime control method applied to the reverse osmosis membrane device, and a water treatment device for implementing the method.

Background Art

[0002] A reverse osmosis membrane (RO membrane) provided in a reverse osmosis membrane device has conventionally been used for removing ions, organic substances, etc. in raw water in seawater desalination, ultrapure water production, industrial water treatment, wastewater recovery treatment, and wastewater reuse, etc. In an aqueous system having a reverse osmosis membrane device, microorganisms such as bacteria and microalgae contained in the water to be treated secrete extracellular substances (for example, extracellular polysaccharides, etc.) to form slime (biofilm), and this slime adheres to and accumulates on the reverse osmosis membrane during water supply, or the slime contained in the slime adhering to the reverse osmosis membrane further increases due to microorganisms, etc. As a result, biofouling (such as clogging of the membrane by slime, etc.) has been a problem.

[0003] Conventionally, as a method for removing slime adhering to and growing on the reverse osmosis membrane surface, the operation of the reverse osmosis membrane device has been stopped, and the reverse osmosis membrane has been washed with a chemical such as caustic soda to remove the slime. However, such a method has hindered the continuous operation of the reverse osmosis membrane device and increased the running cost.

[0004] In recent years, a method has been carried out in which, without stopping the operation of the reverse osmosis membrane device, a slime inhibitor is injected into the aqueous system supplied to the reverse osmosis membrane device to remove the slime (biofilm) adhering to the reverse osmosis membrane surface. For such a method, various types of compounds have been studied as slime inhibitors, and many slime control methods using them have been proposed.

[0005] For example, Patent Document 1 discloses a method for producing pure water, which includes a slime control agent addition step of adding a slime control agent to raw water, a membrane treatment step of subjecting the raw water containing the slime control agent to membrane treatment, an ultraviolet irradiation treatment step of subjecting the membrane-treated water to ultraviolet irradiation treatment, and an ion exchange treatment step of subjecting the ultraviolet irradiation-treated liquid to ion exchange treatment.

[0006] In addition, Patent Document 2 discloses a method for suppressing slime in a reverse osmosis membrane device, which is a method for suppressing slime applied to a water passage step of water to be treated. In the water to be treated with a pH of 10 or less, a slime inhibitor X containing 2,2-dibromo-3-nitrilopropionamide (DBNPA) and a slime inhibitor Y containing at least one selected from the group consisting of the following components (A) to (D) are added, and a first water passage step of passing this water to be treated through a reverse osmosis membrane is included.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0008]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] Generally, when operating continuously for a long time, slime generated in the water system adheres to the reverse osmosis membrane provided in the reverse osmosis membrane device, or the microorganisms adhering to the reverse osmosis membrane further increase the slime, so the operation of the reverse osmosis membrane device may be stopped for membrane replacement or cleaning of the reverse osmosis membrane device. However, after stopping the reverse osmosis membrane device, readjustment of the device during its restart operation, and an increase in the number of times of membrane replacement or cleaning of the reverse osmosis membrane device lead to an increase in running costs. For this reason, the inventors of the present invention decided to consider operating for a long time by ensuring the clogging days as long as possible so as not to stop the operation of the reverse osmosis membrane device as much as possible.

[0010] That is, the main object of the present invention is to provide a technique capable of operating a water system having a reverse osmosis membrane device for a longer period.

Means for Solving the Problems

[0011] As a result of intensive studies, the inventors of the present invention have found that in a water system having a reverse osmosis membrane device, by combining a first step of intermittently adding an oxidation-based slime inhibitor to the water to be treated and a second step of adding an organic-based slime inhibitor to the water to be treated and controlling and operating these steps, the water system having a reverse osmosis membrane device can be operated for a longer period. The inventors of the present invention have also found that at this time, the reduction of slime present on the reverse osmosis membrane of the reverse osmosis membrane device or the suppression of the increase in slime can be better achieved, and thereby biofouling can be better suppressed. Then, the inventors of the present invention completed the present invention as follows.

[0012] The present invention includes a first step of intermittently adding an oxidation-based slime inhibitor and intermittently supplying the water to be treated containing the oxidation-based slime inhibitor to a reverse osmosis membrane device, and a second step of adding an organic-based slime inhibitor at least during a period other than the addition period of the first step and supplying the water to be treated containing the organic-based slime inhibitor to the reverse osmosis membrane device, and provides an operation method of a reverse osmosis membrane device. The present invention includes a first step of intermittently adding an oxidation-based slime inhibitor and intermittently supplying the treated water containing the oxidation-based slime inhibitor to a reverse osmosis membrane device. A second step of adding an organic-based slime inhibitor at least during a period other than the addition period of the first step and supplying the treated water containing the organic-based slime inhibitor to the reverse osmosis membrane device, and provides a slime control method applicable to a reverse osmosis membrane device. The present invention provides a water treatment device that implements the operation method of the reverse osmosis membrane device or the slime control method applicable to the reverse osmosis membrane device.

[0013] The addition concentration of the oxidation-based slime inhibitor may be adjusted to be higher than the addition concentration of the organic-based slime inhibitor. The oxidation-based slime inhibitor may be added one or more times within a three-day operation period. The oxidation-based slime inhibitor may be added for 10 minutes or more each time. The oxidation-based slime inhibitor may be added at a total chlorine concentration of 0.1 mg / L or more. The organic-based slime inhibitor may be added at 0.01 mg / L or more.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a technology that can operate a water system having a reverse osmosis membrane device for a longer period. The effects of the present invention are not necessarily limited to the effects described herein, and may be any of the effects described in this specification.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments for carrying out the present invention will be described. The embodiments described below show examples of typical embodiments of the present invention, and the scope of the present invention is not limited or construed thereby. Note that the upper limit value and the lower limit value in numerical values can be arbitrarily combined as desired.

[0017] 1. Operation Method of Reverse Osmosis Membrane Device According to the Present Embodiment The present invention includes a first step of intermittently adding an oxidation-based slime inhibitor and intermittently supplying treated water containing the oxidation-based slime inhibitor to a reverse osmosis membrane device, A second step of adding an organic slime inhibitor at least during a period other than the addition period of the first step and supplying the treated water containing the organic slime inhibitor to the reverse osmosis membrane device can be provided, and a method for operating a reverse osmosis membrane device is provided. As used herein, a slime inhibitor is a chemical that can suppress the increase of slime, and may include a chemical that can reduce or remove slime present on the membrane, a chemical that can kill microorganisms (such as bactericides and algicides), and a chemical that can suppress the growth of microorganisms (such as antibacterial agents).

[0018] The oxidation-based slime inhibitor used in this embodiment is a component or chemical that can at least suppress slime derived from microorganisms (such as bacteria, fungi, microalgae, etc.) through an oxidation-reduction reaction, or a chemical containing these as active ingredients, and can be detected by the DPD method. However, in this specification, haloacetonitrile compounds (preferably DBNPA) are classified as organic slime inhibitors because they have an inhibitory effect on enzyme metabolic functions.

[0019] The organic slime inhibitor used in this embodiment is a component or chemical that can at least suppress slime derived from microorganisms (such as bacteria, fungi, microalgae, etc.) by inhibiting biological functions by reacting with the metabolic functions (such as enzymes) of microorganisms or the cells of microorganisms (such as SH groups), or a chemical containing these as active ingredients.

[0020] 1-1. First step of using an oxidation-based slime inhibitor The first step is preferably a step of intermittently adding an oxidation-based slime inhibitor and intermittently supplying the treated water containing the oxidation-based slime inhibitor to the reverse osmosis membrane device. Furthermore, the first step preferably has a first addition step of intermittently adding the oxidation-based slime inhibitor to the treated water and a first supply step of intermittently supplying the treated water containing the oxidation-based slime inhibitor after addition to the reverse osmosis membrane device.

[0021] 1-1-1. First addition step The first step is a step of intermittently adding an oxidation-based slime inhibitor to the water to be treated. Thereby, the water to be treated containing the oxidation-based slime inhibitor can be obtained, and the water to be treated containing the oxidation-based slime inhibitor after the addition can be intermittently supplied to the reverse osmosis membrane device (see, for example, FIGS. 1 and 2).

[0022] In the first addition step, it is preferable to intermittently add the oxidation-based slime inhibitor.

[0023] The addition frequency of the oxidation-based slime inhibitor is preferably one or more times within a predetermined period. As the predetermined period, preferably 5 days, more preferably 4 days, still more preferably 3 days, even more preferably 2 days, and most preferably 1 day. Note that the addition of the oxidation-based slime inhibitor may be performed at "predetermined intervals" instead of "within a predetermined period", for example, once every 3 days or once every 1 day. Also, it may be added one or more times a day, preferably once a day, with an interval of 1 to 2 days (more preferably 1 day). The number of additions of the oxidation-based slime inhibitor is not particularly limited, but as a preferable upper limit value, preferably 10 times or less, more preferably 5 times or less, still more preferably 3 times or less, even more preferably 2 times or less, and most preferably 1 time. This number of additions may be "within a predetermined period" or "at predetermined intervals". In terms of the addition frequency of the oxidation-based slime inhibitor, as a more preferable embodiment, it is preferably added one or more times within 3 days, more preferably added one or more times within 2 days, and still more preferably added one or more times within 1 day.

[0024] The addition period of the oxidation-based slime inhibitor is not particularly limited, but each time, as a preferable lower limit value, it is preferably 0.1 minute or more, more preferably 1 minute or more, still more preferably 10 minutes or more, and even more preferably 30 minutes or more. As a preferable upper limit value, it is preferably 1000 minutes or less, more preferably 500 minutes or less, still more preferably 300 minutes or less, and even more preferably 120 minutes or less. As the preferable numerical range, it is preferably 10 minutes or more and 300 minutes or less, and more preferably 30 minutes or more and 120 minutes or less. In this specification, the "addition period of the oxidation-based slime inhibitor" is also referred to as the "addition period of the first step" or the "first intermittent addition period".

[0025] In this specification, the "addition period of the oxidation-based slime inhibitor" refers to the "addition period from the start of the addition of the oxidation-based slime inhibitor to the end of the addition of the oxidation-based slime inhibitor", more preferably refers to the "period during which the oxidation-based slime inhibitor is continuously added within a range that does not impair the effects of the present invention", and in a narrower sense, refers to the "period during which the addition of the oxidation-based slime inhibitor is continuously added without interruption". In this specification, the "one period (specifically, the addition period from the start of the addition of the drug to the end of the addition of the drug)" of the "addition period of the oxidation-based slime inhibitor" may also be referred to as "one unit".

[0026] In this specification, the "period during which the oxidation-based slime inhibitor is not added" is also referred to as the "period other than the addition period of the oxidation-based slime inhibitor", the "period other than the addition period of the first step", or the "period other than the first intermittent addition period", and this period is also referred to as the "first non-addition period". In this specification, the "period during which the oxidation-based slime inhibitor is not added" refers to the "period from the end of the addition of the oxidation-based slime inhibitor to the start of the addition of the oxidation-based slime inhibitor (i.e., the non-addition period)", more preferably refers to the period during which the oxidation-based slime inhibitor is not continuously added within a range that does not impair the effects of the present invention, and in a narrower sense, refers to the period during which the addition of the oxidation-based slime inhibitor is not performed and the oxidation-based slime inhibitor is not continuously added. In this specification, the "one period (specifically, the non-addition period from the end of the addition of the agent to the start of the addition of the agent)" in the above "period during which no oxidation-based slime inhibitor is added" may be defined as "one unit".

[0027] The addition concentration (mg / 1 L of the aqueous system (as total chlorine concentration)) of the oxidation-based slime inhibitor to the aqueous system is not particularly limited. However, as the total chlorine concentration, a suitable lower limit is preferably 0.1 mg / L or more (more preferably 0.5 mg / L or more), more preferably 1 mg / L or more, still more preferably 2 mg / L or more, even more preferably 5 mg / L or more, more preferably 10 mg / L or more, and even more preferably 25 or 30 mg / L or more. Also, as a suitable upper limit, it is preferably 600 mg / L or less, more preferably 60 mg / L or less. As the suitable numerical range, it is preferably 0.1 to 600 mg / L, more preferably 2 to 60 mg / L.

[0028] As a preferred embodiment of the present invention, it is preferable to adjust the addition concentration of the oxidation-based slime inhibitor to be higher than the addition concentration of the organic-based slime inhibitor described below. When the addition concentration of the organic-based slime inhibitor is 1 mg / L (as the drug mass concentration), the addition concentration (mg / L (as total chlorine concentration)) of the oxidation-based slime inhibitor has a suitable lower limit that is preferably 1 or more, more preferably 1.5 or more, still more preferably 2 or more, and even more preferably 3 or more. Also, as a suitable upper limit, it is preferably 100 or less, more preferably 50 or less, still more preferably 40 or 30 or less. As the suitable numerical range, when the addition concentration of the organic-based slime inhibitor is 1 mg / L (as the drug mass), the addition concentration (mg / L (as total chlorine concentration)) of the oxidation-based slime inhibitor is preferably 2 to 50, more preferably 3 to 40.

[0029] The absolute amount (mg / (L / h)) of the oxidation-type slime inhibitor added to the aqueous system per addition period is not particularly limited, but can be calculated from "the addition period of the oxidation-type slime inhibitor per unit × the addition concentration of the oxidation-type slime inhibitor at that time (mg / L (as total chlorine concentration))". As the total chlorine concentration, as a preferable lower limit value, preferably it is 0.05 mg / (L / h) or more, more preferably 0.1 mg / (L / h) or more, still more preferably 0.5 mg / (L / h) or more, even more preferably 1 mg / (L / h) or more, more preferably 2.5 mg / (L / h) or more, more preferably 5 mg / (L / h) or more, more preferably 10 mg / (L / h) or more, more preferably 20 mg / (L / h) or more, more preferably 25 mg / (L / h) or more, more preferably 30 mg / (L / h) or more. Also, as a preferable upper limit value, preferably it is 10000 mg / (L / h) or less, more preferably 10000 mg / (L / h) or less, still more preferably 5000 mg / (L / h) or less, even more preferably 1000 mg / (L / h) or less, more preferably 500 mg / (L / h) or less. As the preferable numerical range, preferably it is 0.05 - 10000 mg / (L / h), more preferably 2.5 - 5000 mg / (L / h), more preferably 2.5 - 1000 mg / (L / h).

[0030] Also, in the first addition step, by intermittently adding the oxidation-type slime inhibitor, it has a period during which the oxidation-type slime inhibitor is added to the aqueous system (hereinafter, also referred to as "the first intermittent addition period") and a period during which the oxidation-type slime inhibitor is not added (hereinafter, also referred to as "the first non-addition period"), and it is preferable that these periods are carried out sequentially or in any order. It is preferable to carry out sequentially. In this case, either the first intermittent addition period or the first non-addition period may come first, and it may be either the first intermittent addition period followed by the first non-addition period or the first non-addition period followed by the first intermittent addition period. Also, the number of times of the first intermittent addition period and the first non-addition period during the entire operation period of the aqueous system may be single or plural.

[0031] One unit of the first intermittent addition period is not particularly limited, but the configuration and the like of the description of the above "addition period of the oxidation-based slime inhibitor" can be adopted. As a preferable numerical range, it is preferably 1 to 1000 minutes, more preferably 10 to 300 minutes.

[0032] One unit of the first non-addition period is not particularly limited, but as a preferable lower limit value, it is preferably 1 hour or more, more preferably 3 hours or more, still more preferably 5 hours or more, and even more preferably 10 hours or more. Also, as a preferable upper limit value, it is preferably 200 hours or less, more preferably 150 hours or less, still more preferably 100 hours or less, and even more preferably 50 hours or less. As the preferable numerical range, it is preferably 5 to 100 hours, more preferably 10 to 50 hours.

[0033] The period ratio of the first intermittent addition period per unit and the first non-addition period per unit during the total period of "the first intermittent addition period per unit and the first non-addition period per unit" is not particularly limited, but it is preferable that the first intermittent addition period per unit is shorter than the first non-addition period per unit from the viewpoint of stably operating the water system in the long term while reducing the amount of additive used in the water system. The period ratio of the first intermittent addition period per unit to the first non-addition period per unit is preferably 1:2 to 500, more preferably 1:3 to 200, still more preferably 1:5 to 100, and even more preferably 1:7 to 50.

[0034] Note that the first intermittent addition period per unit may be the average value obtained by dividing the total period (days, hours, etc.) of the first intermittent addition period during a certain operation period by the number of the first intermittent addition periods during this operation period. Also, the first non-addition period per unit may be the average value obtained by dividing the total period (days, hours, etc.) of the first non-addition period during a certain operation period by the number of the first non-addition periods during this operation period. In addition, the operation period of the first addition step in the present embodiment may be a single period of "the first intermittent addition period per unit and the first non-addition period per unit", or a period constituted by combining a plurality of the same or different "the first intermittent addition period per unit and the first non-addition period per unit".

[0035] <Oxidation-based slime inhibitor> The oxidation-based slime inhibitor or this component is not particularly limited, and examples thereof include, for example, bound halogen compounds. The oxidation-based slime inhibitor may be a drug containing a bound halogen compound, and examples of the halogen include chlorine, bromine, and the like. Examples of the bound halogen compound include bound chlorine compounds, bound bromine compounds, etc., and one or more selected from these can be used. Examples of the bound chlorine compound include stabilized chlorine compounds typified by halogenated hydantoin compounds, chloramine compounds, etc., and examples of the bound bromine compound include stabilized bromides, halogenated hydantoin compounds, etc., but are not limited thereto, and one or more selected from these can be used. The oxidation-based slime inhibitor or the compound used for the oxidation-based slime inhibitor may be a commercially available product or a product obtained by a known production method.

[0036] Note that salts of bound halogen compounds such as salts of chloramine compounds and salts of stabilized bromides are not particularly limited, and examples thereof include alkali metal salts such as sodium salts and potassium salts; alkaline earth metal salts such as calcium salts, strontium salts, and barium salts; other metal salts such as manganese salts, copper salts, zinc salts, iron salts, cobalt salts, and nickel salts; ammonium salts, organic ammonium salts, etc.; amino acid salts such as guanidine salts; etc., and one or more selected from these can be used.

[0037] <Chloramine compound> The chloramine compound refers to a compound having at least one bond between a nitrogen atom and a chlorine atom (N-Cl bond). Examples of chloramine compounds include chloramine, chlorosulfamic acid compounds, and other chloramine compounds, and one or more selected from these can be used. Examples of chloramine compounds include stabilized chlorine compounds produced from those containing a stabilizer and a chlorine-based oxide; chlorosulfamic acid compounds produced from those containing a sulfamic acid compound and a chlorine-based oxide; etc., and one or more selected from these can be used.

[0038] The stabilizer is not particularly limited as long as it can generate a bound halogen (preferably, a stabilized bound halogen), and preferably includes compounds having an amino group such as ammonium salts and sulfamic acid compounds, and one or more selected from these can be used. In the present specification, a monovalent functional group (-NH2, -NHR, -NRR') obtained by removing hydrogen from ammonia, a primary amine, or a secondary amine is referred to as an "amino group".

[0039] Examples of ammonium salts include ammonium sulfate, ammonium nitrate, ammonium chloride, etc., and one or more selected from these can be used. Among these, ammonium sulfate is preferred.

[0040] The sulfamic acid compound constituting the chlorosulfamic acid compound is preferably a compound represented by R 1 R 2 NSO3H ··· [1]. In the general formula [1], R 1 and R 2 are each independently preferably H or an alkyl group having 1 to 8 carbon atoms or a functional group containing a benzene ring. Examples of sulfamic acid compounds include those having two R 1 groups and R 2Sulfamic acid (sulfuric acid amide) in which both groups are hydrogen atoms or a salt thereof; two Rs such as N-methylsulfamic acid, N-ethylsulfamic acid, N-propylsulfamic acid, N-isopropylsulfamic acid, N-butylsulfamic acid 1 groups and R 2 Sulfamic acid or a salt thereof in which one of the two Rs is a hydrogen atom and the other is an alkyl group having 1 to 8 carbon atoms; N,N-dimethylsulfamic acid, N,N-diethylsulfamic acid, N,N-dipropylsulfamic acid, N,N-dibutylsulfamic acid, N-methyl-N-ethylsulfamic acid, N-methyl-N-propylsulfamic acid, etc. 1 groups and R 2 Sulfamic acid or a salt thereof in which both groups are alkyl groups having 1 to 8 carbon atoms; etc., but not limited thereto. One or more selected from these can be used.

[0041] The chlorine-based oxide is not particularly limited, and examples thereof 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, chlorinated isocyanuric acid or a salt thereof, etc. One or more selected from these can be used. Examples of hypochlorite include alkali metal hypochlorites such as sodium hypochlorite and potassium hypochlorite; alkaline earth metal hypochlorites such as calcium hypochlorite and barium hypochlorite; etc. One or more selected from these can be used. Examples of chlorite include alkali metal chlorites such as sodium chlorite and potassium chlorite; alkaline earth metal chlorites such as barium chlorite; other metal chlorites such as nickel chlorite; etc. One or more selected from these can be used. Examples of chlorate include ammonium chlorate; alkali metal chlorates such as sodium chlorate and potassium chlorate; alkaline earth metal chlorates such as calcium chlorate and barium chlorate; etc. One or more selected from these can be used. Examples of the perchlorate include sodium perchlorate, potassium perchlorate, etc., and one or more selected from these can be used. Examples of the chlorinated isocyanurate include sodium chlorinated isocyanurate, etc., and one or more selected from these can be used.

[0042] As an example of the production of the chloramine compound, for example, a method of mixing an aqueous solution of a stabilizer (for example, an aqueous solution of a sulfamic acid compound, etc.) and an aqueous solution of a chlorine-based oxide (for example, an aqueous solution of sodium hypochlorite, etc.) in the presence of an alkali can be mentioned, and the chloramine compound can be produced from at least a stabilizer and a chlorine-based oxide. The pH of the agent containing the produced chloramine compound is preferably 12 or more, more preferably 13 or more. For example, as an example of the production of sodium chlorosulfamate, the method described in [Examples] of Patent No. 5720964 can be referred to. The usage ratio of the chlorine-based oxide and the stabilizer (for example, ammonium salt, sulfamic acid compound, etc.) is not particularly limited, but it is preferable that the chlorine stabilizer (preferably a sulfamic acid compound) is 0.5 to 5.0 moles, more preferably 0.5 to 2.0 moles, and even more preferably 1.0 to 1.5 moles with respect to 1 mole of the total chlorine concentration (Cl2) of the chlorine-based oxidizer. The said usage ratio may be the content ratio in the agent. The usage ratio of the alkali and the chlorine-based oxide is preferably 0.3 to 0.4, more preferably 0.30 to 0.36 in terms of Cl / alkali metal (molar ratio), and the said usage ratio may be the content ratio in the agent.

[0043] As the sulfamic acid compound, R 1 、R 2Narrower sulfamic acid where each is H is more preferred, but N-methylsulfamic acid, N,N-dimethylsulfamic acid, N-phenylsulfamic acid, chloramine T, etc. can also be used. The sulfamic acid compound may use these sulfamic acids in the state of free (powdered) acids, or may be a salt such as an alkali metal salt like sodium salt, potassium salt, lithium salt, etc.

[0044] Chlorosulfamic acid refers to a compound in which at least one hydrogen atom of the NH2 group possessed by sulfamic acid (H2NSO2OH) is substituted with a chlorine atom. Examples of chlorosulfamic acid include monochlorosulfamic acid, dichlorosulfamic acid, etc.

[0045] Chlorosulfamate refers to a compound in which at least one hydrogen atom of the OH group possessed by sulfamic acid (H2NSO2OH) is substituted with a metal ion (for example, an alkali metal ion such as lithium ion, sodium ion, potassium ion, etc.). Examples of chlorosulfamates include lithium chlorosulfamate, sodium chlorosulfamate, potassium chlorosulfamate, etc., and one or more selected from these can be used. Among these, sodium chlorosulfamate is preferred. Also, as other chloramine compounds, chloramine T, etc. can be used.

[0046] <Stabilized bromide> Stabilized bromide refers to a compound having at least one bond between a nitrogen atom (N-Cl bond) or a carbon atom and a bromine atom (C-Br bond). As the stabilized bromide, a bromide that hardly undergoes changes such as decomposition in water and in which the generated bromide can stably exist in water is preferred. Examples of the stabilized bromide include, but are not limited to, reaction products of "reaction products of bromine-based oxidants or bromine compounds and chlorine-based oxides" and "sulfamic acid compounds". The pH of the reaction product is preferably alkaline, more preferably 11 or more, still more preferably 12 or more, and even more preferably 13 or more. These may be commercially available products or those obtained by known production methods.

[0047] The bromine-based oxidant is not particularly limited, and examples thereof include bromine (liquid bromine), bromine chloride, bromic acid, bromate, and hypobromous acid. One or more selected from these can be used.

[0048] The bromine compound is not particularly limited, and examples thereof include alkali metal bromide salts such as sodium bromide, potassium bromide, and lithium bromide, ammonium bromide salts such as ammonium bromide, and hydrobromic acid. One or more selected from these can be used.

[0049] The chlorine-based oxides (for example, hypochlorite, chlorite, chlorate, perchlorate, chlorinated isocyanurate, etc.) used in the stabilized bromide are applicable to the descriptions such as the "chlorine-based oxides" of the above <chloramine compound>, and the configurations and the like of the descriptions can be appropriately adopted. Among these, hypochlorite (for example, sodium hypochlorite) is preferred.

[0050] The "sulfamic acid compound" is applicable to the descriptions such as the "sulfamic acid compound" in the "sulfamic acid compound constituting the chlorosulfamic acid compound of the above <chloramine compound> is represented by R 1 R 2 NSO3H ··· [1]". The configurations and the like of the descriptions can be appropriately adopted. Among the "sulfamic acid compounds", sulfamic acid or its salt is preferred.

[0051] As an example of the production of a stabilized bromide, for example, an aqueous sodium bromide solution and sodium hypochlorite are mixed to form a mixed solution 1. On the other hand, an aqueous sulfamic acid solution and an aqueous sodium hydroxide solution are mixed to form a mixed solution 2. A method of mixing the mixed solution 1 and the mixed solution 2 in the presence of an alkali can be mentioned. For example, bromamine or bromosulfamic acid composed of an ammonium salt and bromine, and bromosulfamate, and other compounds such as DBNPA can be used.

[0052] <Halogenated hydantoin compound> Examples of the halogenated hydantoin compound include 1-bromo-3-chloro-5,5-dimethylhydantoin (also referred to as "BCDMH"), 1,3-dichloro-5,5-dimethylhydantoin, 1,3-dibromo-5,5-dimethylhydantoin, 1-bromo-3-chloro-5,5-diethylhydantoin, 1,3-dichloro-5,5-diethylhydantoin, and 1-bromo-3-chloro-5-methyl-5-ethylhydantoin, etc. One or more selected from these can be used. Among these, from the viewpoints of the balance with the solid agent (B) of the elution rate when in contact with water and the availability, etc., BCDMH and 1,3-dichloro-5,5-dimethylhydantoin are preferred.

[0053] The halogenated hydantoin compound may be a commercially available product or can be obtained by a known production method. For example, a hydantoin compound (such as hydantoin (chemical formula: C3H4N2O2), etc.) can be used as a stabilizer, and the stabilizer is reacted with the above chlorine-based oxide and / or bromine-based oxidant to obtain it. The hydantoin compound includes compounds having a hydantoin skeleton. Examples of the hydantoin compound include hydantoin, 5,5-dialkylhydantoin (such as 5,5-dimethylhydantoin, 5-methylethylhydantoin, 5-methylbutylhydantoin, and 5-ethylbutylhydantoin, etc.), and one or more selected from these can be used. The "dialkyl" may be the same or different alkyl groups. Examples of the alkyl group include those having 1 to 5 carbon atoms (preferably 1 to 3 carbon atoms), and may be linear or branched, such as a methyl group, an ethyl group, a butyl group, etc.

[0054] In addition, the oxidation-based slime inhibitor may appropriately contain optional components or optional agents within a range that does not impair the effects of the present invention. Examples of the optional components or optional agents include corrosion inhibitors, scale inhibitors, slime control agents, solvents or dispersion media such as water, dispersant enzymes, bactericides, and antifoaming agents, but are not limited thereto, and various agents generally used for water treatment may also be used. One or more can be appropriately selected from these optional components or optional agents. In addition, in the first step of this embodiment, separately from the addition or use of the oxidation-based slime inhibitor, optional components or optional agents may be appropriately added or used.

[0055] 1-1-2. First supply step The first supply step is preferably a step of intermittently supplying the water to be treated containing an oxidation-based slime inhibitor to the reverse osmosis membrane device. By combining this first supply step with the second supply step in the following second step, the water system can be operated for a longer period. As a more preferred embodiment, it is possible to suppress biofouling generated in the reverse osmosis membrane provided in the reverse osmosis membrane device, and by suppressing the biofouling, the water system can be stably operated for a long period.

[0056] In the first supply step, when intermittently supplying the water to be treated containing an oxidation-based slime inhibitor to the reverse osmosis membrane device, it has a period during which the water to be treated containing the oxidation-based slime inhibitor is supplied (also referred to as the "first intermittent supply period") and a period during which the water to be treated containing the oxidation-based slime inhibitor is not supplied (also referred to as the "first non-supply period").

[0057] For various conditions in the first supply step, the configurations and the like in the description of the above "1-1-1. First addition step" can be appropriately adopted. For example, the supply frequency and its predetermined period, the number of supply times, the supply frequency, the supply period, the supply concentration of the oxidation-based slime inhibitor to the water system, the absolute amount of the oxidation-based slime inhibitor supplied to the water system per supply period, one unit of the first supply period, the period ratio of the first intermittent supply period per unit to the first non-supply period per unit, etc. can appropriately adopt the addition frequency and its predetermined period, the number of addition times, the addition frequency, the addition period, the addition concentration of the oxidation-based slime inhibitor to the water system, the absolute amount of the oxidation-based slime inhibitor added to the water system per addition period, one unit of the first addition period, the period ratio of the first intermittent addition period per unit to the first non-addition period per unit, etc. in the above "1-1-1. First addition step".

[0058] The supply frequency of the water to be treated containing an oxidation-based slime inhibitor is not particularly limited, but it is preferably supplied one or more times within a predetermined period, and more preferably once as the predetermined period. This supply frequency may be "within a predetermined period" or "at each predetermined interval". The number of times of supplying the oxidation-based slime inhibitor is not particularly limited, but as a preferable upper limit value, more preferably it is 2 times or less, and even more preferably it is 1 time. The supply frequency of the treated water containing the oxidation-based slime inhibitor is preferably at least once within 3 days, more preferably at least once within 2 days (more preferably every other day), and even more preferably once or more within 1 day. Also, this number of supply times may be "within a predetermined period" or "at each predetermined interval". In terms of the supply frequency of the oxidation-based slime inhibitor, as a more preferable embodiment, it is preferably supplied at least once within 3 days, and more preferably supplied at least once within 1 day.

[0059] The supply period of the treated water containing the oxidation-based slime inhibitor is not particularly limited, but for each supply, as a preferable numerical range, it is preferably 10 minutes or more and 300 minutes or less, and more preferably 30 minutes or more and 120 minutes or less.

[0060] In this specification, the "supply period of the treated water containing the oxidation-based slime inhibitor" refers to the "supply period from the start of the supply of the oxidation-based slime inhibitor to the end of the supply of the oxidation-based slime inhibitor", and in a narrower sense, it refers to the "period during which the supply of the oxidation-based slime inhibitor is continuously supplied without interruption". Also, in this specification, the "supply period of the treated water containing the oxidation-based slime inhibitor" is also referred to as the "supply period of the first step" or the "first intermittent supply period". Also, in this specification, the "one period (specifically, the supply period from the start of the supply of the chemical agent to the end of the supply of the chemical agent)" of the "supply period of the treated water containing the oxidation-based slime inhibitor" may be referred to as "one unit".

[0061] In this specification, the "period during which the treated water containing the oxidation-based slime inhibitor is not supplied" is also referred to as the "period other than the supply period of the treated water containing the oxidation-based slime inhibitor", the "period other than the supply period of the first step", or the "period other than the first intermittent supply period", and this period is also referred to as the "first non-supply period". In this specification, the "period during which treated water containing an oxidation-based slime inhibitor is not supplied" refers to the "non-supply period from the end of the supply of the oxidation-based slime inhibitor to the start of the supply of the oxidation-based slime inhibitor", and more narrowly, refers to the "period during which the oxidation-based slime inhibitor is not supplied to the reverse osmosis membrane device and is not continuously supplied". In this specification, the "one period (specifically, the non-supply period from the end of the supply of the chemical agent to the start of the supply of the chemical agent)" of the above "period during which treated water containing an oxidation-based slime inhibitor is not supplied" may be defined as "one unit".

[0062] The supply concentration of the oxidation-based slime inhibitor to the aqueous system (mg of chemical agent / 1 L of aqueous system) is not particularly limited. As the total chlorine concentration, the preferred lower limit is preferably 0.1 mg / L or more (more preferably 0.5 mg / L or more), more preferably 1 mg / L or more, still more preferably 2 mg / L or more, even more preferably 5 mg / L or more, more preferably 10 mg / L or more, still more preferably 25 mg / L or more. Also, as a preferred numerical range, it is preferably 5 to 500 mg / L, more preferably 25 to 300 mg / L.

[0063] The absolute amount (mg×hour) of the oxidation-based slime inhibitor supplied to the reverse osmosis membrane device per supply period is not particularly limited, but can be calculated from "the supply period of the treated water containing the oxidation-based slime inhibitor per unit × the supply concentration of the oxidation-based slime inhibitor at that time". As the total chlorine concentration, the preferred lower limit is preferably 0.05 mg / (L / h) or more, more preferably 0.1 mg / (L / h) or more, still more preferably 0.5 mg / (L / h) or more, even more preferably 1 mg / (L / h) or more, more preferably 2.5 mg / (L / h) or more, more preferably 10 mg / (L / h) or more, still more preferably 25 mg / (L / h) or more. Also, as a preferred numerical range, it is preferably 0.05 to 10000 mg / (L / h), more preferably 2.5 to 5000 mg / (L / h), more preferably 10 to 1000 mg / (L / h).

[0064] In addition, in the first supply step, the water to be treated containing the oxidation-based slime inhibitor is supplied to the reverse osmosis membrane device, and there are a period during which the water to be treated containing the oxidation-based slime inhibitor is supplied to the reverse osmosis membrane device (hereinafter, also referred to as the "first intermittent supply period") and a period during which the water to be treated containing the oxidation-based slime inhibitor is not supplied to the reverse osmosis membrane device (hereinafter, also referred to as the "first non-supply period"), and it is preferable that these periods are performed sequentially or in any order. It is preferably performed sequentially. The order of these first intermittent supply periods and first non-addition supply periods is preferably based on the order of the first intermittent addition period and first non-addition period described above. Also, the number of times of each of the first intermittent supply period and first non-supply period during the entire operation period of the water system may be single or plural.

[0065] One unit of the first intermittent supply period is not particularly limited, but as a preferable numerical range, it is preferably 1 to 1000 minutes, more preferably 10 to 300 minutes. One unit of the first non-supply period is not particularly limited, but as a preferable numerical range, it is preferably 5 to 100 hours, more preferably 10 to 50 hours.

[0066] The period ratio of the first intermittent supply period per unit to the first non-supply period per unit during the total period of "the first intermittent supply period per unit and the first non-supply period per unit" is not particularly limited, but it is preferable that the first intermittent addition period per unit is shorter than the first non-addition period per unit, and even more preferably 1:7 to 50. Note that the first intermittent supply period per unit may be an average value obtained by dividing the total period (such as days) of the first intermittent supply period during a certain operation period by the number of the first intermittent supply periods during this operation period. Also, the first non-supply period per unit may be an average value obtained by dividing the total period (such as days) of the first non-supply period during a certain operation period by the number of the first non-supply periods during this operation period. In addition, the operating period of the first supply step in this embodiment may be a single period of "the first intermittent supply period per unit and the first non-supply period per unit", or a period composed of a plurality of combinations of the same or different "the first intermittent supply period per unit and the first supply period per unit". It is preferable that this single period or the periods of the plurality of combinations are based on the single period or the periods of the plurality of combinations of the above-mentioned "the first intermittent addition period per unit and the first non-addition period per unit".

[0067] 1-2. Second Step of Using Organic Slime Suppressant In the second step, it is preferable to add the organic slime suppressant at least during a period other than the addition period of the first step, and supply the treated water containing the organic slime suppressant to the reverse osmosis membrane device. Furthermore, it is preferable that the second step includes a second addition step of adding the organic slime suppressant and a second supply step of supplying the treated water containing the organic slime suppressant after the addition to the reverse osmosis membrane device.

[0068] 1-2-1. Second Addition Step The second step is a step of adding the organic slime suppressant at least during "a period other than the addition period of the first step". Thereby, the treated water containing the organic slime suppressant can be obtained, and the treated water containing the organic slime suppressant after the addition can be supplied to the reverse osmosis membrane device (see, for example, FIGS. 1 and 2).

[0069] In the second addition step, it is preferable to add the organic slime suppressant at least during "a period other than the addition period of the first step".

[0070] Here, "adding at least during 'a period other than the addition period of the first step' in the second step" also means "adding the organic slime suppressant at least during the first non-addition period", but the organic slime suppressant may be added during both the first non-addition period and the first intermittent addition period, or the organic slime suppressant may be added only during the first non-addition period. In the second step, the addition of the organic slime inhibitor during the first non-addition period may be the addition of the organic slime inhibitor during the entire period or a partial period of the first non-addition period. Also, in the second step, the addition of the organic slime inhibitor during the first intermittent addition period may be the addition of the organic slime inhibitor during the entire period or a partial period of the first intermittent addition period.

[0071] Also, in the second step, it is preferable to add the organic slime inhibitor during the entire period of the first non-addition period or a partial period of the first non-addition period. Note that the partial period of the first non-addition period is preferably 50% or more, more preferably 70% or more, still more preferably 90% or more, even more preferably 95% or more, more preferably 98% or more, still more preferably 99% or more, and even more preferably 100% (also referred to as the entire period) with respect to the entire period of the first non-addition period.

[0072] In the second step, it is more preferable to add the organic slime inhibitor continuously or discontinuously during "at least the period other than the addition period of the first step", and it is even more preferable to add it continuously, and it is even more preferable to add it constantly. Also, in the second step, it is more preferable to add the organic slime inhibitor continuously or discontinuously at least during "the first non-addition period per unit", and it is even more preferable to add it continuously.

[0073] In this specification, "discontinuous" means that as long as the effects of the present invention are not impaired, there may be a period of adding the organic slime inhibitor and a period of stopping, but it is preferable that the period of adding is longer than the period of stopping. The period of stopping is preferably within 1 / 10 of the period of adding, more preferably within 5 / 100 of the period of adding, still more preferably within 2.5 / 100, and even more preferably within 1 / 500 of the period of adding.

[0074] In this specification, the period during which the organic slime inhibitor is "continuously" added refers to the "addition period from the start of the addition of the organic slime inhibitor to the end of the addition of the organic slime inhibitor", more preferably the "period during which the organic slime inhibitor is continuously added within the range that does not impair the effects of the present invention", and more narrowly, the "period during which the addition of the organic slime inhibitor is continuously added without interruption", which is also referred to as the "period of continuous addition". As this "period of continuous addition", for example, for an operation period of 60 minutes, there is "no addition period of 0 minutes and an addition period of 60 minutes".

[0075] In this specification, "continuously" may have a period during which the drug is stopped as long as it is within the range of effects similar to the continuous addition of the present invention. As a more specific preferred embodiment, as the period during which the drug is stopped during the day, it is preferably within 60 minutes, more preferably within 30 minutes, still more preferably within 15 minutes, even more preferably within 5 minutes, and more preferably 0 minutes (also referred to as the "period of continuous addition"). Also, as the period during which the drug is stopped during one hour of operation, it is preferably within 5 minutes, more preferably within 1 minute, still more preferably within 5 minutes, and more preferably 0 minutes (also referred to as the "period of continuous addition").

[0076] The addition period of the organic slime inhibitor is not particularly limited. For example, the entire operation period or the entire first process period of the reverse osmosis membrane device may be set as the addition period of the organic slime inhibitor. As a more specific embodiment, each time, as a preferable lower limit value, it is preferably 0.1 day or more, more preferably 0.3 day or more, still more preferably 0.5 day or more, and even more preferably 1 day or more. Also, as a preferable upper limit value, it is preferably 30 days or less, more preferably 10 days or less, still more preferably 7 days or less, and even more preferably 3 days or less. As this preferable numerical range, it is preferably 0.5 day or more and 7 days or less, and more preferably 1 day or more and 3 days or less.

[0077] The addition concentration (mg (as drug mass) / 1 L of water system) of the organic slime inhibitor to the water system is not particularly limited. However, as the drug mass, the preferable lower limit is preferably 0.001 mg / L or more, more preferably 0.05 mg / L or more, still more preferably 0.01 mg / L or more, and even more preferably 0.1 mg / L or more. Also, as the preferable upper limit, it is preferably 10,000 mg / L or less, more preferably 1,000 mg / L or less, still more preferably 100 mg / L or less, and even more preferably 50 mg / L or less. As the preferable numerical range, it is preferably 0.01 to 100 mg / L, and more preferably 0.1 to 50 mg / L.

[0078] The absolute amount (mg (as drug mass)) of the organic slime inhibitor added to the water system per addition period is not particularly limited, but can be calculated from "the addition period of the organic slime inhibitor × the addition concentration of the organic slime inhibitor at that time". As the preferable lower limit, it is preferably 0.002 mg / (L / h) or more, more preferably 0.02 mg / (L / h) or more, still more preferably 0.2 mg / (L / h) or more, and even more preferably 2 mg / (L / h) or more. Also, as the preferable upper limit, it is preferably 6,000,000 mg / (L / h) or less, more preferably 300,000 mg / (L / h) or less, still more preferably 30,000 mg / (L / h) or less, and even more preferably 3,000 mg / (L / h) or less. As the preferable numerical range, it is preferably 0.2 to 30,000 mg / (L / h), and more preferably 2 to 3,000 mg / (L / h).

[0079] <organic slime inhibitor> The organic slime inhibitor or a component thereof is not particularly limited, and examples include isothiazoline compounds, halocyanacetamide compounds, aldehyde compounds, and oxime compounds represented by tetrazolyloxime and dichloroglyoxime. One or more of these can be used. Further, the organic slime inhibitor may be a drug containing one or more compounds selected from these. As the organic slime inhibitor or the compound used for the organic slime inhibitor, commercially available products may be used, or those obtained by known production methods may be used.

[0080] <Isothiazoline compound> The isothiazoline compound is not particularly limited, and examples include 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT), 2-methyl-4-isothiazolin-3-one (MIT), 2-ethyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-ethyl-4-isothiazolin-3-one, 5-chloro-2-t-octyl-4-isothiazolin-3-one, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, 4,5-dichloro-2-cyclohexyl-4-isothiazolin-3-one, etc. One or more of these can be used. Further, as the isothiazoline compound, a complex compound of the above-mentioned isothiazoline compound and magnesium chloride, magnesium nitrate, copper chloride, copper nitrate, calcium chloride, etc. may be used. Among the isothiazoline compounds, 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT), and 2-methyl-4-isothiazolin-3-one (MIT) or a mixture thereof are preferable.

[0081] <Halocyanacetamide compound> As the halo cyanoacetamide compound, although not particularly limited, for example, 2-halo-3-cyano propionamides such as 2-chloro-3-cyano propionamide and 2-bromo-3-cyano propionamide; 2,2-dihalo-3-cyano propionamides such as 2,2-dichloro-3-cyano propionamide, 2,2-dibromo-3-cyano propionamide (DBNPA), and 2-chloro-2-bromo-3-cyano propionamide; N-C1-3 alkyl-2-halo-3-cyano propionamides such as N-methyl-2-chloro-3-cyano propionamide and N-methyl-2-bromo-3-cyano propionamide; N-C1-3 alkyl-2,2-dihalo-3-cyano propionamides such as N-methyl-2,2-dichloro-3-cyano propionamide and N-methyl-2,2-dibromo-3-cyano propionamide, etc. can be mentioned. Incidentally, the halo cyanoacetamide compound is NC-CX 1 X 2 -(C=O)-NHR 3 ··· It may also be a compound represented by [2]. In the general formula [2], X 1 , X 2 each independently represents a halogen atom or a hydrogen atom, and at least one of X 1 , X 2 is a halogen atom. R 3 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of the halogen atom include a chlorine atom and a bromine atom, and a bromine atom is preferred. C1-3 alkyl may be either linear or branched, and examples include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, etc.

[0082] Among the halo cyanoacetamide compounds, dihalo cyano propionamide is preferred, and among these, 2,2-dibromo-3-cyano propionamide (DBNPA) is more preferred.

[0083] <Aldehyde compound> As the aldehyde compound, although not particularly limited, for example, monoaldehyde compounds such as acetaldehyde; dialdehyde compounds such as glyoxal and orthophthalaldehyde, etc. can be mentioned, and one or more selected from these can be used. Among the aldehyde compounds, dialdehyde compounds are preferred, and among the dialdehyde compounds, glutaraldehyde is preferred from the viewpoint of high safety.

[0084] <Oxime compound> As the oxime compound, although not particularly limited, oxime compounds having a tetrazole ring (CH2N4) (for example, tetrazolyloxime, etc.), and halogenated oxime compounds (for example, dichloroglyoxime, etc.) can be mentioned, and one or more selected from these can be used. The oxime compound is a compound having a structure represented by >C=N-OH in the molecule. As the oxime compound having a tetrazole ring, for example, picarbutrazox (molecular formula :C 20 H 23 N7O3, molecular weight: 409.44, CAS No. 500207-04-5, etc.) can be mentioned. As the halogenated oxime compound, for example, dichloroglyoxime, α-chlorobenzaldoxime, α-chlorobenzaldoxime acetate, 4-hydroxyphenyl-α-ketoacetohydroximic acid chloride (alias paraclox), etc. can be mentioned, and one or more selected from these can be used.

[0085] Among the organic slime inhibitors, one or more selected from 2,2-dibromo-3-nitrilopropionamide (DBNPA), 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT), and 2-methyl-4-isothiazolin-3-one (MIT), or a mixture thereof, glutaraldehyde, etc. are preferred.

[0086] In addition, the organic slime inhibitor may appropriately contain optional components or optional chemicals as long as the effects of the present invention are not impaired. Further, in the second step of the present embodiment, separate from the addition or use of the organic slime inhibitor, optional components or optional chemicals may be further added or used as appropriate. As the optional components or optional chemicals, various chemicals generally used for water treatment may be used, and the configuration of the description of "optional components or optional chemicals" of the above <oxidizing slime inhibitor> may be appropriately adopted.

[0087] 1-2-2. Second Supply Step The second supply step is preferably a step of supplying the water to be treated containing the organic slime inhibitor to the reverse osmosis membrane device. By combining this second supply step with the first supply step in the above first step, the water system can be operated for a longer period. As a more preferred embodiment, it is possible to suppress biofouling generated in the reverse osmosis membrane provided in the reverse osmosis membrane device, and by suppressing the biofouling, the water system can be stably operated for a long period.

[0088] Regarding various conditions in the second supply step, the configuration of the description of the above "1-2-1. Second Addition Step" can be appropriately adopted. For example, the supply period in the second supply step, the supply concentration of the organic slime inhibitor with respect to the water system, the absolute amount of the organic inhibitor supplied to the water system per supply period, etc. can appropriately adopt the addition period of the above "1-2-1. Second Addition Step", the addition concentration of the organic slime inhibitor with respect to the water system, the absolute amount of the organic slime inhibitor added to the water system per addition period, etc.

[0089] In the second supply step, it is preferable that the water to be treated containing the organic slime inhibitor is supplied to the reverse osmosis membrane device during "at least a period other than the supply period of the first step". The water to be treated containing the organic slime inhibitor is preferably supplied continuously or discontinuously to the reverse osmosis membrane device during the operation period, more preferably continuously supplied, and even more preferably constantly supplied. In this specification, the period during which the organic slime inhibitor is "continuously" supplied refers to the "supply period from the start of the supply of the organic slime inhibitor to the end of the supply of the organic slime inhibitor". More narrowly, it refers to the "period during which the supply of the organic slime inhibitor is continuously supplied without interruption", and this narrow sense is defined as the "period of continuous supply".

[0090] The supply period of the organic slime inhibitor is not particularly limited, and the entire operation period of the reverse osmosis membrane device or the entire period of the first step may be set as the supply period of the organic slime inhibitor. However, as a more specific embodiment, each time, as a preferable numerical range, it is preferably 0.5 days or more and 7 days or less, more preferably 1 day or more and 3 days or less.

[0091] The supply concentration (mg / 1 L of water system (as the drug mass concentration)) of the organic slime inhibitor to the reverse osmosis membrane device is not particularly limited, but as a preferable numerical range, it is preferably 0.01 to 100 mg / L, more preferably 0.1 to 50 mg / L.

[0092] The absolute amount (mg) of the organic slime inhibitor supplied to the reverse osmosis membrane device per supply period is not particularly limited, but as a preferable numerical range, it is preferably 0.2 to 30000 mg / (L / h), more preferably 2 to 3000 mg / (L / h).

[0093] 1-3. Control of the first step and the second step in this embodiment In the method of this embodiment, it is preferable to control the first step and the second step, whereby the water system having the osmosis membrane device can be operated for a longer period. In the method of this embodiment, as a more preferable aspect, it is to control the first addition step and the second addition step. Thereby, the water to be treated containing the oxidation-based slime inhibitor and / or the organic-based slime inhibitor can be favorably supplied to the reverse osmosis membrane device, and thus the water system having the osmosis membrane device can be stably operated for a longer period. Furthermore, by controlling the first addition step and the second addition step, it is possible to more favorably reduce the slime present on the reverse osmosis membrane of the reverse osmosis membrane device or suppress the increase in slime, and thereby it is also possible to more favorably suppress biofouling.

[0094] In the method of this embodiment, the first step and the second step can be carried out simultaneously or at separate times, and it is more preferable to carry them out simultaneously. Also, in the method of this embodiment, the first step and the second step may be carried out in parallel or in series, but it is preferable to carry them out in parallel. In the method of this embodiment, as a more preferable aspect, it is more preferable to carry out the first step and the second step simultaneously and in parallel. Also, in the method of this embodiment, during the addition of the oxidation-based slime inhibitor in the first step (preferably, during continuous addition), the organic-based slime inhibitor in the second step may be added or the addition may be stopped. Furthermore, it is preferable to continuously add the organic-based slime inhibitor in the second step while the oxidation-based slime inhibitor in the first step is not being added.

[0095] In the method of this embodiment, as a more preferable aspect, it is more preferable to control the first step and / or the second step based on the start point of operation of the first step and / or the second step, and the start points of operation for each may be the same or different. The start point of operation is not particularly limited and may be arbitrarily set. For example, it includes the date (year / month / day / hour / minute / second), and the operating conditions of the first step and / or the second step (for example, at the start of operation, when restarting operation, when adding chemicals, any period setting, etc.). One or a combination of two or more selected from these can be used.

[0096] As a preferred embodiment of a more specific operation start point, for example, the start of the first intermittent addition or the start of the first non-addition in the first step may be used as the operation start point, or anywhere within the second addition period of the second step may be used as the operation start point, or the start of the first intermittent addition or the start of the first non-addition in the first step within the second addition period of the second step may be used as the operation start point. Further, when both the first step and the second step are in a non-addition period (for example, maintenance, for the purpose of adjusting the addition timing of both steps, both stopped, etc.), the start of the addition (resumption of addition) of at least one of the agents in the first step and the second step may be used as the operation start point, or the simultaneous addition of the agents in both the first step and the second step may be used as the operation start point.

[0097] The control of the first addition step and the second addition step in this embodiment will be described with reference to FIGS. 1 and 2, but this embodiment is not limited thereto.

[0098] FIG. 1 is a schematic diagram showing Example 1 of the control of the first addition step and the second addition step according to an embodiment of the present invention. a1 in Example 1: In the first addition step, an oxidation-based slime inhibitor is intermittently added at equal intervals. b1 in Example 1: In the second addition step, an organic-based slime inhibitor is continuously added. At this time, the organic-based slime inhibitor is added at least during a period other than the addition period of the first addition step. The horizontal axis is the operation period (hours), and the vertical axis is the addition amount. Further, the The operation period of 0 h in the first addition step and the operation period of 0 h in the second addition step may each be used as the operation start point. Note that each intermittent addition period in the first addition step may be the same or different, and each intermittent addition amount may be the same or different. Also, each interval of the intermittent addition may be the same or different.

[0099] According to Example 1 of the control in this embodiment, the water to be treated can contain an oxidation-based slime inhibitor and / or an organic-based slime inhibitor. And, according to Example 1 of the control in this embodiment, the water to be treated containing an oxidation-based slime inhibitor and / or an organic-based slime inhibitor is supplied to the reverse osmosis membrane device as the first supply step and the second supply step. At this time, the water to be treated containing an oxidation-based slime inhibitor and / or an organic-based slime inhibitor can be supplied to the reverse osmosis membrane device in a pattern similar to the addition patterns of a1 and b1 as shown in FIG. 1. As a more specific example, the water to be treated containing only the organic-based slime inhibitor, the water to be treated containing the oxidation-based slime inhibitor and the organic-based slime inhibitor,... are supplied to the reverse osmosis membrane device in this order. Thereby, the water system having the reverse osmosis membrane device can be stably operated for a longer period. The reduction of slime present on the reverse osmosis membrane of the reverse osmosis membrane device or the suppression of the increase in slime can be better achieved, and thereby biofouling can also be better suppressed.

[0100] FIG. 2 is an example of a schematic diagram showing Example 2 of the control of the first addition step and the second step according to an embodiment of the present invention. a2 of Example 2: In the first addition step, the oxidation-based slime inhibitor is intermittently added at equal intervals. b2 of Example 2: In the second addition step, the organic-based slime inhibitor is continuously added during the period "other than the addition period of the first addition step". The horizontal axis is the operation period (hours), and the vertical axis is the addition amount. Further, the operation period of 0 h in the first addition step and the operation period of 0 h in the second addition step may be used as the operation starting points, respectively. Regarding the overlapping parts in the description of FIG. 1 above, they will be omitted as appropriate. Note that each intermittent addition period in the first addition step may be the same or different periods, and each intermittent addition amount may be the same or different amounts. Also, each interval of the intermittent addition may be the same or different intervals. Also, in the second addition step, the organic-based slime inhibitor may be continuously added during the entire period or a partial period of the period "other than the addition period of the first addition step". Also, in the second addition step, the organic-based slime inhibitor may be added discontinuously.

[0101] Further, as Example 3 of the control of the first addition step and the second addition step according to the present embodiment, Example 1 of the above control and Example 2 of the above control may be combined, and Example 1 of the above control and Example 2 of the above control may be repeated or performed in any order. For example, it may be performed in the order of Example 1 of the above control followed by Example 2 of the above control, or in the order of Example 2 of the above control followed by Example 1 of the above control, or in the order of Example 1 of the above control, Example 2 of the above control, and Example 2 of the above control.

[0102] By Example 2 of the control in the present embodiment, the water to be treated can contain an oxidation-based slime inhibitor and / or an organic-based slime inhibitor. Then, by Example 2 of the control in the present embodiment, the water to be treated containing an oxidation-based slime inhibitor and / or an organic-based slime inhibitor is supplied to the reverse osmosis membrane device as the first supply step and the second supply step. At this time, the water to be treated containing an oxidation-based slime inhibitor and / or an organic-based slime inhibitor can be supplied to the reverse osmosis membrane device in a pattern similar to the addition patterns of a2 and b2 as shown in FIG. 2. As a more specific example, the water to be treated containing only the organic-based slime inhibitor, the water to be treated containing only the oxidation-based slime inhibitor,... are supplied to the reverse osmosis membrane device in this order. Thereby, the water system having the reverse osmosis membrane device can be stably operated for a longer period. The reduction of slime present on the reverse osmosis membrane of the reverse osmosis membrane device or the suppression of the increase in slime can be better achieved, and thereby biofouling can also be better suppressed.

[0103] The addition location of the oxidation-based slime inhibitor and / or the organic-based slime inhibitor may be the same or different (see, for example, FIG. 3). The addition location is preferably upstream of the reverse osmosis membrane device where reverse osmosis membrane treatment is performed and before that. When a security filter device is provided in front of the reverse osmosis membrane device in order to subject the water to be treated supplied to the reverse osmosis membrane device to security filter treatment, the addition location of the oxidation-based slime inhibitor and / or the organic-based slime inhibitor is preferably the security filter device or before and after it. Further, it is preferably provided in the security filter device and upstream thereof. More specifically, it is more preferably provided in the flow path for addition between the security filter device and the treatment device upstream thereof. The security filter device can perform the turbidity removal membrane treatment process described later and may be a turbidity removal membrane device. As the security filter device, a membrane (for example, an MF membrane etc.) that can be used for the turbidity removal membrane device can be appropriately adopted as the security filter. Thereby, slime in the security filter treatment device can be suppressed, and slime in the reverse osmosis membrane device downstream thereof can also be suppressed. Also, biofouling of these membrane devices can be suppressed, and more specifically, biofouling of the reverse osmosis membrane device can be suppressed. For this reason, the water system can be stably operated for a longer period.

[0104] 1-4. Application of the operation method in this embodiment

[0105] The operation method in this embodiment can be applied to a reverse osmosis membrane device. The method of this embodiment can be applied to a slime suppression method, a biofouling suppression method, a water system, a device or a system. The process according to this embodiment can be applied to a device or a system. For example, the first process and the second process may be the first method and the second method, the first device and the second device, the first system and the second system, respectively. The operation method in this embodiment can be applied to a water system having at least a reverse osmosis membrane device.

[0106] The water system equipped with the reverse osmosis membrane device is not particularly limited, and examples include a water treatment water system; a circulating water system such as a cooling tower; a process water system such as paper pulp production, a water supply system, and wastewater recovery.

[0107] As an example of an aqueous system equipped with a reverse osmosis membrane device, there may be provided, in any order or sequence, a coagulation treatment step in which raw water flows in and a coagulant is injected into the raw water to form aggregates or flocs of turbidity and the like, a solid-liquid separation step in which the treated water containing the aggregates is separated into sediment and supernatant, and a turbidity removal membrane treatment step in which turbidity and the like are further removed from the inflowing supernatant before reverse osmosis membrane treatment. Further, these treatment steps may be performed using a treatment device or treatment unit configured to perform each treatment step.

[0108] As an example of an aqueous system equipped with a reverse osmosis membrane device, for example, referring to the aqueous system 1 shown in FIG. 3, the aqueous system according to the present embodiment is not limited thereto. In the aqueous system 1 equipped with the reverse osmosis membrane device 2, there are included a coagulation step performed by a coagulation treatment device 5 configured to inject a coagulant into the raw water flowing in to form aggregates or flocs of turbidity and the like, a solid-liquid separation step performed by a solid-liquid separation device 4 configured to separate the treated water containing the aggregates into sediment and supernatant, a pretreatment step performed by a security filter 3 configured to further remove turbidity and the like from the inflowing supernatant before reverse osmosis membrane treatment, and a reverse osmosis membrane treatment step performed by the reverse osmosis membrane device 2 to which the pretreated treated water containing an oxidation-based slime inhibitor and / or an organic-based slime inhibitor is supplied. In the reverse osmosis membrane treatment step, it is separated into concentrated water and permeated water.

[0109] Further, as an example of an aqueous system equipped with a reverse osmosis membrane device, there may be mentioned a water treatment device (preferably an ultrapure water device) including a raw water supply path configured to supply raw water and a reverse osmosis membrane device configured to separate the raw water supplied from the raw water supply path into permeated water and concentrated water.

[0110] Further, as an example of an aqueous system equipped with a reverse osmosis membrane device, there may be mentioned a water treatment device including a raw water supply path configured to supply raw water, a filtration device and a filtration treatment water tank configured to filter the raw water supplied from the raw water supply path, a security filter device configured as a pretreatment for reverse osmosis membrane treatment of the filtered treated water, and a reverse osmosis membrane device. The above-described turbidity removal membrane treatment may be performed by the security filter device.

[0111] 1-4-1. Raw water The raw water (for example, water to be treated) used in this embodiment is not particularly limited, and examples thereof include industrial wastewater containing organic substances, seawater and brackish water, fresh water (such as river water and lake water), industrial water and municipal water.

[0112] The pH of the raw water or water to be treated is not particularly limited, but is preferably 3 to 9, more preferably 4 to 8, and even more preferably 5 to 8. The pH may be adjusted with a pH adjuster. The water temperature of the raw water or water to be treated is not particularly limited, but is preferably 4 to 50°C, and more preferably 10 to 40°C. The TOC of the raw water or water to be treated is not particularly limited, but is preferably 1 to 100 mg / L, more preferably 1 to 50 mg / L, and even more preferably 1 to 10 mg / L. The ORP of the raw water or water to be treated is preferably 200 to 600 mV, and more preferably 200 to 400 mV.

[0113] 1-4-2. Reverse osmosis membrane device The reverse osmosis membrane device used in this embodiment is not particularly limited, and it is preferably configured to be able to remove ions, organic substances, etc. in the raw water using a reverse osmosis membrane. The reverse osmosis membrane device is preferably configured to be able to perform seawater desalination, ultrapure water production, industrial water treatment, wastewater recovery treatment, and reuse of wastewater. Further, the reverse osmosis membrane device may include one or more units having a reverse osmosis membrane. Also, the water system may have one or more reverse osmosis membrane devices.

[0114] <Reverse osmosis membrane> The membranes used in this embodiment are reverse osmosis membranes (hereinafter also referred to as "RO membranes") and nanofiltration membranes (hereinafter also referred to as "NF membranes"). The RO membrane is not particularly limited, and examples thereof include polyamide-based, polyethersulfone-based, polysulfone-based, polyimide-based, polyethyleneimine-based, polyethyleneoxide-based, and cellulose acetate-based membranes. Among these, polyamide-based RO membranes have the advantage that they can be preferably used because they have a high rejection rate of ionic substances and a large flux.

[0115] The conditions of the water to be treated (hereinafter also referred to as "feed water") supplied to the reverse osmosis membrane device in this embodiment can be appropriately set according to the treatment capacity or purpose of the reverse osmosis membrane device or the reverse osmosis membrane process, but are not particularly limited.

[0116] Examples of the water to be treated (feed water) supplied to the reverse osmosis membrane device include feed water pH, feed water flow rate, feed water temperature, feed water pressure (MPa), feed water TOC (Total Organic Carbon), and feed water oxidation-reduction potential (ORP). One or more of these conditions can be selected. The organic matter in the feed water is defined as TOC. In the present invention, the "water to be treated supplied to the reverse osmosis membrane device" is also referred to as "feed water". The feed water refers to the water introduced into the reverse osmosis membrane device and subjected to reverse osmosis membrane treatment, and usually corresponds to the inlet water of the reverse osmosis membrane device. The pH of the feed water is not particularly limited, but is preferably 3 to 9, more preferably 4 to 8, and even more preferably 5 to 8. The pH may be adjusted with a pH adjuster.

[0117] The flow rate of the feed water is not particularly limited, but is preferably 5 to 200 mL / min. The pressure of the feed water is not particularly limited, but is preferably 0.1 to 10 MPa. The temperature of the feed water is not particularly limited, but is preferably 4 to 50 °C, and more preferably 10 to 40 °C. The TOC of the feed water is not particularly limited, but is preferably 1 to 100 mg / L, more preferably 1 to 50 mg / L, and even more preferably 1 to 10 mg / L. ​ The ORP of the supply water is preferably 200 to 600 mV, more preferably 200 to 400 mV. Also, the flow rate of the supply water is preferably 3 to 10 m 3 / h per 8-inch spiral module.

[0118] In this embodiment, as a more suitable mode, a pretreatment step of removing organic substances, turbidity, etc. from the water to be treated in a pretreatment section may be included before supplying the water to be treated to the reverse osmosis membrane device. It is preferable to pretreat the water to be treated supplied to the reverse osmosis membrane device with a security filter device. For example, as a pretreatment step, raw water (water to be treated) is filtered by a filtration device, and the filtered treated water passes through a filtration treatment water tank and a security filter. Thereby, the water to be treated for supplying to the pretreated reverse osmosis membrane device or the reverse osmosis membrane process can be obtained. The security filter is not particularly limited. For example, it includes single or multiple microfiltration membrane (MF membrane) treatments, single or multiple ultrafiltration membrane (UF) treatments, etc. One or more of these can be used, and these can be appropriately combined. Thereby, impurities such as turbidity of the water to be treated supplied to the reverse osmosis membrane device can be reduced.

[0119] In this embodiment, since the water to be treated supplied to the reverse osmosis membrane device contains an oxidation-based slime inhibitor and / or an organic-based slime inhibitor better, biofouling occurring in the reverse osmosis membrane device can be better suppressed as appropriate, and also, the effects (for example, antibacterial, bactericidal, algicidal, microbial growth inhibition, microbial metabolism inhibition, etc.) caused by the oxidation-based slime inhibitor and / or the organic-based slime inhibitor can be better and more efficiently exerted as appropriate. Thereby, the effect of suppressing biofouling occurring in the reverse osmosis membrane device and the effect of the chemical used can be expected.

[0120] 1 - 5. Each measurement method <Calculation method of total residual chlorine concentration> The total residual chlorine concentration is calculated based on the following method. Note that JIS K 0400-33-10:1999 can be referred to. Total residual chlorine concentration = Free chlorine concentration + Activated bound chlorine concentration + Stabilized bound chlorine concentration. Free chlorine concentration: The free chlorine concentration by the DPD method (pocket residual chlorine meter, manufactured by HACH). Here, the free chlorine concentration by the DPD method is the chlorine concentration measurement result (mg-Cl2 / L) after 5 to 30 seconds by the DPD(Free) reagent, which is a reagent for measuring free chlorine. Activated bound chlorine concentration: The value obtained by subtracting the measurement result of the above free chlorine concentration (mg-Cl2 / L) from the chlorine concentration measurement result (mg-Cl2 / L) after 300 seconds by the DPD(Free) reagent, which is a reagent for measuring free chlorine. Stabilized bound chlorine concentration: The value obtained by subtracting the chlorine concentration measurement result (mg-Cl2 / L) after 300 seconds by the DPD(Free) reagent, which is a reagent for measuring free chlorine, from the chlorine concentration measurement result (mg-Cl2 / L) after 180 seconds by the DPD(Total) reagent, which is a reagent for measuring total chlorine. Free chlorine ratio (%) = (Free chlorine concentration / Total residual chlorine concentration) × 100 Stabilized bound chlorine ratio (%) = (Stabilized bound chlorine concentration / Total residual chlorine concentration) × 100 Note that the temperature of the test environment is 25°C.

[0121] The pH (25°C) of the water to be treated can be measured with a handy pH meter manufactured by HRIBA. Also, the TOC of the water to be treated can be measured with a TOC meter. The ORP of the water to be treated can be measured with an ORP meter.

[0122] Note that the operation method of the reverse osmosis membrane device according to this embodiment may be a treatment method of the reverse osmosis membrane. Also, the operation method according to this embodiment can be applied to an apparatus or a system. In addition, regarding the operation method of the reverse osmosis membrane device according to the present invention, descriptions of each component such as the first step, the second step, the oxidation-based slime inhibitor, and the organic-based slime inhibitor, which overlap with the components such as "2." and "3." below, will be appropriately omitted. However, the descriptions such as "2." and "3." also apply to this embodiment, and the components and the like of the descriptions can be appropriately adopted.

[0123] 2. Slime control method applicable to the reverse osmosis membrane device according to this embodiment Regarding the slime control method applicable to the reverse osmosis membrane device according to the present invention, descriptions of each component such as the first step, the second step, the oxidation-based slime inhibitor, and the organic-based slime inhibitor, which overlap with the components such as "1." below and "3." below, will be appropriately omitted. However, the descriptions such as "1." and "3." also apply to this embodiment, and the components and the like of the descriptions can be appropriately adopted. In addition, the slime control method according to this embodiment can be applied to a device or a system.

[0124] The slime control method applicable to the reverse osmosis membrane device according to this embodiment includes a first step of intermittently adding an oxidation-based slime inhibitor and intermittently supplying the treated water containing the oxidation-based slime inhibitor to the reverse osmosis membrane device, and a second step of adding an organic-based slime inhibitor at least during a period other than the addition period of the first step and supplying the treated water containing the organic-based slime inhibitor to the reverse osmosis membrane device, which is preferably adopted.

[0125] It is preferable to adjust so that the addition concentration of the oxidation-based slime inhibitor during one addition period is higher than the addition concentration of the organic-based slime inhibitor during one addition period. It is preferable to add the oxidation-based slime inhibitor one or more times within 3 days of the operation period. It is preferable to add the oxidation-based slime inhibitor for 10 minutes or more each time. It is preferable to add the oxidation-based slime inhibitor with a total chlorine concentration of 0.1 mg / L or more. It is preferable to add the organic-based slime inhibitor at 0.01 mg / L or more.

[0126] 3. Water treatment apparatus according to this embodiment The water treatment apparatus according to the present invention omits the descriptions of each component such as the first step, the second step, the oxidation-based slime inhibitor, and the organic-based slime inhibitor that overlap with the configurations such as the above "1." and "2." as appropriate. However, the descriptions such as the above "1." and "2." are also applicable to this embodiment, and the configurations and the like of the descriptions can be adopted as appropriate. In addition, the water treatment apparatus according to this embodiment may be a water treatment apparatus or a water system having at least a reverse osmosis membrane apparatus. The water treatment apparatus may be a water treatment water system or a water treatment system.

[0127] The water treatment apparatus according to this embodiment A first step of intermittently adding an oxidation-based slime inhibitor and intermittently supplying the treated water containing the oxidation-based slime inhibitor to a reverse osmosis membrane apparatus; A second step of adding an organic-based slime inhibitor at least during a period other than the addition period of the first step and supplying the treated water containing the organic-based slime inhibitor to a reverse osmosis membrane apparatus. A water treatment apparatus for implementing the method of this embodiment is preferably used. The water treatment apparatus according to this embodiment preferably implements the operation method of the reverse osmosis membrane apparatus of this embodiment or the slime control method applied to the reverse osmosis membrane apparatus of this embodiment.

[0128] The water treatment apparatus according to this embodiment preferably includes a first chemical addition unit, a second chemical addition unit, and a reverse osmosis membrane unit, and includes a control unit for controlling these units. It is preferably further provided with a security filter unit as a pretreatment unit in front of the reverse osmosis membrane unit. The first chemical addition unit and the second chemical addition unit are preferably connected to a flow path upstream or downstream of the security filter unit or a flow path upstream of the reverse osmosis membrane unit, whereby each chemical can be added to the treated water and the treated water containing each chemical can be supplied to the reverse osmosis membrane apparatus. In addition, each of these units may be singular or plural, and each of these units may be an apparatus.

[0129] An example of the implementation of this embodiment is shown below, but the implementation of this embodiment is not limited thereto. Further, the implementation of this embodiment may be carried out by a control unit, or may be carried out by a water treatment control device, a water treatment device, a water treatment system, a device such as a water system, etc.

[0130] As an example in this embodiment, a control unit configured to be able to carry out the first step and the second step, or a device provided with such a control unit is preferable. Thereby, the method of this embodiment can be implemented better. The control unit can control and implement the first step and the second step by instructing the first chemical addition unit and the second chemical addition unit about the chemical addition conditions (addition timing (for example, intermittent, continuous), addition amount, etc.) of the oxidation-based slime inhibitor and the organic-based slime inhibitor added to the water to be treated. Further, in the first step and the second step, the control unit may monitor the supply state of the water to be treated containing chemicals to the reverse osmosis membrane device using various measuring devices, and if necessary, feedback this measurement result to the first addition step and the second addition step, and can also control them.

[0131] As a preferred aspect, the control unit can control and implement the first step and the second step by instructing the first chemical addition unit and the second chemical addition unit about more suitable chemical addition situations (addition timing (for example, intermittent, continuous), addition concentration, etc.) respectively based on the supply state. Thereby, a water system having a reverse osmosis membrane device can be operated more stably in the long term. Further, thereby, the reduction of slime existing on the reverse osmosis membrane of the reverse osmosis membrane device or the suppression of the increase of slime can be better achieved, and thereby biofouling can also be better suppressed.

[0132] As a more preferred embodiment, it is preferable that the control unit simultaneously and parallelly executes the following step 11 and step 21, and it is more preferable to simultaneously and parallelly execute step 12 and step 22. Further, the control unit can prepare the treated water containing the oxidation-based slime inhibitor and / or the organic-based slime inhibitor while adjusting the addition amount of the oxidation-based slime inhibitor and the oxidation-based slime inhibitor to the treated water, the addition timing, the addition period, etc. in the first addition step and the second addition step. The control unit can supply the treated water containing the oxidation-based slime inhibitor and / or the organic-based slime inhibitor prepared in the first addition step and the second addition step to the reverse osmosis membrane device in the first supply step and the second supply step. In this way, the control unit can operate the water system having the reverse osmosis membrane device more stably for a longer period. Thereby, biofouling generated in the reverse osmosis membrane device can also be suppressed.

[0133] As step 11 of the first step, the control unit controls the first chemical addition unit so as to intermittently add an oxidation-based slime inhibitor to the treated water in the water system. In accordance with the instruction of the control unit, the first chemical addition unit intermittently adds an oxidation-based slime inhibitor to the treated water in the water system. As step 12 of the first step, after the addition, the control unit controls so as to intermittently supply the treated water containing the oxidation-based slime inhibitor to the reverse osmosis membrane device. As step 21 of the second step, the control unit controls the second chemical addition unit so as to add an organic-based slime inhibitor at least in a period other than the addition period of the first step. In accordance with the instruction of the control unit, the second chemical addition unit adds an organic-based slime inhibitor at least in a period other than the addition period of the first step. As step 22 of the second step, the control unit controls so as to supply the treated water containing the organic-based slime inhibitor to the reverse osmosis membrane device after the addition.

[0134] The control unit preferably instructs the first chemical addition unit and the second chemical addition unit to adjust the addition concentration (as total chlorine concentration) of the oxidation-based slime inhibitor to be higher than the addition concentration (as chemical mass concentration) of the organic-based slime inhibitor, whereby the desired chemical addition amounts can be achieved for each. Also, it is preferable that the control unit instructs the first chemical addition unit to add the oxidation-based slime inhibitor at least once within a three-day operation period, whereby the desired addition period can be achieved. Also, it is preferable that the control unit instructs the first chemical addition unit to add the oxidation-based slime inhibitor for at least 0.1 minutes per addition, whereby the desired addition period can be achieved.

[0135] As an example, as shown in FIG. 3, a control unit (not shown) can control a first chemical addition device 10 and a second chemical addition device 20 provided in an aqueous system having a reverse osmosis membrane device. The control unit can instruct the first chemical addition device 10 to add the oxidation-based slime inhibitor upstream of the security filter 3 or the reverse osmosis membrane device 2 in accordance with the first step. The control unit can instruct the second chemical addition device 20 to add the organic-based slime inhibitor upstream of the security filter 3 or the reverse osmosis membrane device 2 in accordance with the second step. In this way, the control unit can supply the water to be treated containing the oxidation-based slime inhibitor and / or the organic-based slime inhibitor to the reverse osmosis membrane device 2. In this way, by controlling and implementing the first addition step and the second addition step, the control unit can operate the aqueous system having the reverse osmosis membrane device more stably for a longer period.

[0136] Note that the method of this embodiment can also be realized by an apparatus for implementing or managing methods such as the operation method of the reverse osmosis membrane apparatus and the slime control method described above (for example, the methods described in the above "1." and "2."), or a control unit provided in the apparatus (the control unit includes a CPU or a processor, etc.), and these apparatuses or control units can be provided. Examples of the apparatus for the implementation or management include a computer, a notebook computer, a desktop computer, a tablet PC, a PLC, a server, a cloud service, and the like. Further, the apparatus for the implementation or management, etc. may be appropriately provided with an input unit such as a touch panel or a keyboard, a communication unit such as a transmission / reception unit between each unit, a network, and a network access unit, and a display unit such as a touch panel or a display. Thereby, the method of this embodiment can be implemented. The apparatus for the implementation or management can be appropriately provided with, for example, a CPU, a RAM, a storage unit, a display unit, and a communication unit as a configuration, and the configuration may be connected by a bus as a data transmission path, for example, as necessary.

[0137] Also, the method of this embodiment can be stored as a program in a hardware resource provided with a storage medium (non-volatile memory (such as a USB memory), SSD (Solid State Drive), HDD (Hard Disk Drive), CD, DVD, Blu-ray, etc.), and realized by the control unit. The method of this embodiment can be provided as a program. A storage medium storing the method of this embodiment can be provided. Thereby, the method of this embodiment can be implemented.

[0138] In addition, an apparatus, a water treatment apparatus, a system, a water-based system, or the like for performing operations such as operation of a reverse osmosis membrane apparatus or slime control of a reverse osmosis membrane apparatus, which is configured to be able to operate a reverse osmosis membrane apparatus or control slime of a reverse osmosis membrane apparatus, including the control unit, the storage medium, the program, etc., can be provided. Thereby, the method of the present embodiment can be implemented. These apparatuses, water treatment apparatuses, systems, water-based systems, or the like may be configured to be adaptable as appropriate according to the purpose.

[0139] Also, as an example in the present embodiment, a computer is configured to intermittently add an oxidation-based slime inhibitor and intermittently supply treated water containing the oxidation-based slime inhibitor to a reverse osmosis membrane apparatus, and a second function of adding an organic-based slime inhibitor at least during a period other than the addition period of the first step and supplying treated water containing the organic-based slime inhibitor to the reverse osmosis membrane apparatus. A program for realizing operations such as operation of a reverse osmosis membrane apparatus or slime control can be provided, and the present invention is not limited thereto. Thereby, the method of the present embodiment can be implemented.

[0140] Note that in the program according to the present embodiment, descriptions of each configuration such as the first step, the second step, the oxidation-based slime inhibitor, and the organic-based slime inhibitor that overlap with the configurations such as "1.", "2.", etc. are appropriately omitted, but the descriptions such as "1.", "2.", etc. are also applicable to the present embodiment, and the configurations and the like of the descriptions can be appropriately adopted.

[0141] This technology can adopt the following configurations. 〔1〕 A first step of intermittently adding an oxidation-based slime inhibitor and intermittently supplying treated water containing the oxidation-based slime inhibitor to a reverse osmosis membrane apparatus; A second step of adding an organic-based slime inhibitor at least during a period other than the addition period of the first step and supplying treated water containing the organic-based slime inhibitor to the reverse osmosis membrane apparatus, the method for operating a reverse osmosis membrane apparatus. 〔2〕 A first step of intermittently adding an oxidation-based slime inhibitor and intermittently supplying treated water containing the oxidation-based slime inhibitor to a reverse osmosis membrane device; A second step of adding an organic-based slime inhibitor at least during a period other than the addition period of the first step and supplying treated water containing the organic-based slime inhibitor to a reverse osmosis membrane device, and a slime control method applied to a reverse osmosis membrane device.

[0142] 〔3〕 The method according to 〔1〕 or 〔2〕, wherein the addition concentration of the oxidation-based slime inhibitor is adjusted to be higher than the addition concentration of the organic-based slime inhibitor. 〔4〕 The method according to any one of 〔1〕 to 〔3〕, wherein the oxidation-based slime inhibitor is added one or more times within 3 days of the operation period. 〔5〕 The method according to any one of 〔1〕 to 〔4〕, wherein the oxidation-based slime inhibitor is added for 10 minutes or more each time. 〔6〕 The method according to any one of 〔1〕 to 〔5〕, wherein the oxidation-based slime inhibitor is added at a total chlorine concentration of 0.1 mg / L or more. 〔7〕 The method according to any one of 〔1〕 to 〔6〕, wherein the organic-based slime inhibitor is added at 0.01 mg / L or more. 〔8〕 The method according to any one of 〔1〕 to 〔7〕, wherein the oxidation-based slime inhibitor is a bound halogen agent, preferably one or more selected from chloramine compounds, stabilized bromides, and halogenated hydantoin compounds, more preferably a chloramine compound and / or a stabilized bromide. 〔9〕 The organic slime inhibitor is one or more selected from isothiazoline compounds, halocyanacetamide compounds, aldehyde compounds, and oxime compounds, and preferably, one or more selected from 2,2-dibromo-3-nitrilopropionamide (DBNPA), 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT), 2-methyl-4-isothiazolin-3-one (MIT), and glutaraldehyde, the method according to any one of [1] to [8] above.

[0143]

[10] A water treatment apparatus or a water treatment water system that implements the operation method of the reverse osmosis membrane apparatus according to any one of [1] and [3] to [9] above, or the slime control method applied to the reverse osmosis membrane apparatus according to any one of [2] to [9] above. The water treatment apparatus or the water treatment water system preferably has at least a reverse osmosis membrane apparatus, and further preferably has a security filter apparatus upstream of the reverse osmosis membrane apparatus. Also, it is preferable to have a security filter apparatus for pretreatment before supplying to the reverse osmosis membrane apparatus, whereby the water to be treated that has been subjected to the security filter treatment can be supplied to the reverse osmosis membrane apparatus.

[11] A water treatment apparatus or a water treatment water system, or a control unit or a control device may be provided so as to implement the method according to any one of [1] to [9] above. The control unit may be provided with a CPU, and the control device is preferably a computer device. It may be a water treatment apparatus or a water treatment water system having the control unit or the control device.

[0144]

[12] An operation system of a permeation membrane apparatus or a slime control system applied to a reverse osmosis membrane apparatus that causes a computer to implement the method according to any one of [1] to [9] above.

[13] A program that causes a computer to implement the method according to any one of [1] to [9] above.

[14] A first function that causes a computer to intermittently add an oxidation-based slime inhibitor and intermittently supply treated water containing the oxidation-based slime inhibitor to a reverse osmosis membrane device, A second function that adds an organic-based slime inhibitor at least during a period other than the addition period of the first step and supplies treated water containing the organic-based slime inhibitor to the reverse osmosis membrane device, and a program for realizing the operation of the reverse osmosis membrane device or a computer-readable medium storing the program, or a device including the program or the medium. A control unit, a water treatment device, a control system, or a water treatment water system configured to execute the program.

Example

[0145] The embodiments of the present invention will be described with reference to the following examples and comparative examples. Note that the scope of the present invention is not limited to the examples.

[0146] <Test Example 1> A substrate was added to the raw water to promote the biofouling effect by microorganisms. Specifically, the raw water was used as treated water by adding ethanol 50 mg / L as C, ammonium chloride 10 mg / L as N, and sodium dihydrogen phosphate 0.5 mg / L as P as substrates. The pH of the raw water (treated water) was 6 - 8, the TOC was 1 mg / L, the ORP was 300 mV, and the water temperature was 25°C. This treated water was pressurized to 1.5 MPa with a pump and supplied as feed water (water volume: 100 mL / min, water pressure: 0.2 MPa, water temperature: 25°C) to the concentrate chamber of the RO membrane device for RO membrane treatment. The RO membrane device used a 4-inch spiral type RO membrane element of aromatic polyamide-based RO membrane (manufactured by Nitto Denko Corporation, ES20) filled in one vessel. The flow rate of the feed water was 3 - 10 m 3 / h per 8-inch spiral module. The change in differential pressure means that the pressure at the start of measurement was set to 0 kPa, and the change in the difference between the pressure at each water passage time after the start was measured.

[0147] <Method for Evaluating Slime Inhibition against Reverse Osmosis Membrane> When evaluating slime inhibition against a reverse osmosis membrane, using the membrane fouling simulator described in Non-Patent Document 1 (J. S. Vrouwenvelder et. al.), measure the number of days required for the differential pressure to increase by 10 0 kPa under the conditions shown in Table 1. The day when this differential pressure is reached is defined as the day when biofouling has occurred, that is, the blocking day. The longer the number of days until this blockage occurs, the more effective the slime inhibition is evaluated to be.

[0148] 〔Comparative Example 1-1〕: No chemical added 〔Comparative Example 1-2〕: Sodium monochlorosulfamate at 1.5 mg / L as total chlorine concentration (T-Cl) was continuously added from the start day until blockage. Comparative Example 3: Cl-MIT at 0.15 mg / L as Cl-MIT was continuously added from the start day until blockage. 〔Example 1-1〕: <j1-1>The first step and <j2-2>The second step was carried out in parallel together with it. <j1-1>From the start date, every day from 8:00 am for 2 hours, sodium monochlorosulfamate, an oxidation-type slime inhibitor, was added to the water to be treated at 6 mg / L as T-Cl, and the water to be treated containing the chemical was supplied to the RO membrane device. <j2-2>From the start day, Cl-MIT (5-chloro-2-methyl-4-isothiazolin-3-one), an organic slime inhibitor, was constantly added at 0.15 mg / L as the drug mass (Cl-MIT), and the treated water containing the drug was supplied to the RO membrane device. In the case of continuous addition, after starting the addition of the drug to the treated water from day 0, until it became blocked, the addition of the drug was continuously added to the treated water without stopping, and the treated water containing the drug was supplied to the reverse osmosis membrane. <j1-1>and <j2-2>Regarding the period in which the addition times overlap, the treated water containing these was supplied to the RO membrane device.

[0149] <Preparation of Chemical Agent Containing Sodium Monochlorosulfamate> An aqueous sodium hydroxide solution was prepared using pure water so that sodium hydroxide (manufactured by Kishida Chemical Co., Ltd.) was 48% by mass. After mixing 19.5 g of this pre-prepared aqueous sodium hydroxide solution and 7.5 g of pure water, 15.0 g of amidosulfuric acid (sulfamic acid) (manufactured by Kishida Chemical Co., Ltd.) was added and mixed. Then, 58.0 g of sodium hypochlorite (manufactured by Asahi Glass Co., Ltd.) with an available chlorine concentration of 12% by mass was further added and mixed to prepare a sodium monochlorosulfamate reagent. The total chlorine concentration of this chemical agent is 7% by mass as Cl2.

[0150]

Table 1

[0151] From these water passing results shown in Table 1, the following could be confirmed. It was confirmed that it is better to alternately add slime inhibitors of different strains every few days than to constantly add a single slime inhibitor. It was confirmed that by performing, in parallel, a first addition step of intermittently adding an oxidation-based slime inhibitor once a day for 2 hours and a second addition step of constantly adding an organic-based slime inhibitor, the number of blocked days became longer and the slime inhibition effect was more excellent.

[0152] <Test Example 2> IPA 1.4 mg / L as C and sodium dihydrogen phosphate were added to the raw water as substrates The test was carried out under the same conditions as in the above <Test Example 1> except that the treated water added so as to be 0.02 mg / L as P was used, the water temperature of the treated water was set and adjusted to 30°C, and the following conditions were adopted as the biocide addition conditions.

[0153] 〔Comparative Example 2-1〕 The organic slime inhibitor Cl-MIT was continuously added at 0.1 mg / L as the drug mass (Cl-MIT), and the RO membrane device was continuously supplied with water. As a result, the water to be treated containing the drug was continuously supplied with water to the RO membrane device downstream thereof.

[0154] 〔Example 2-1〕 The organic slime inhibitor in the second step was continuously added for a "certain period of time", and then, during the period when the addition of the organic slime inhibitor in the second step was stopped, the oxidation-based slime inhibitor in the first step was continuously added for a "certain period of time" in this order, and this was repeated. As a result, the oxidation-based slime inhibitor was intermittently added, and the water to be treated containing the oxidation-based slime inhibitor was continuously supplied with water to the reverse osmosis membrane device for a "certain period of time". On the other hand, the organic slime inhibitor was continuously added during the "period other than the addition period in the first step", and the water to be treated containing the organic slime inhibitor was continuously supplied with water to the reverse osmosis membrane device during the "period other than the addition period in the first step".

[0155] Specifically, Cl-MIT, which is the organic slime inhibitor used in the second step, was continuously added at 0.1 mg / L as the drug mass (Cl-MIT) for a period of 23.5 hours from 9:30 every day to 9:00 the next day, and the RO membrane device downstream thereof was continuously supplied with water for this predetermined period. And (2) monochlorosulfamic acid, which is the oxidation-based slime inhibitor used in the first step, was continuously added at 5 mg / L as T-Cl for a period of 0.5 hours from 9:00 to 9:30 every day, and the RO membrane device downstream thereof was continuously supplied with water for this predetermined period. As a result, the water to be treated containing the organic slime inhibitor, the water to be treated containing the oxidation-based slime inhibitor, the water to be treated containing the organic slime inhibitor... were supplied to the reverse osmosis membrane device in this order.

[0156] The results of the differential pressure changes (kPa) up to 6 days in Example 2-1 and Comparative Example 2-1 are shown in FIG. 4. Clearly, in Example 2-1, the increase in differential pressure was blunted, suggesting that the method of Example 2-1 has a very excellent slime suppression function. Furthermore, in Example 2-1, both the organic slime inhibitor and the oxidation slime inhibitor are implemented at low concentrations. However, since the change in differential pressure is below 10 KPa even after 6 days, very good slime suppression is obtained. As a result, it was also confirmed that both the organic slime inhibitor and the oxidation slime inhibitor can exhibit a good slime suppression function even at low concentrations.

[0157] <Test Example 3> The test was carried out under the same conditions as in the above <Test Example 1>, except that the raw water was treated water added with ethanol 50 mg / L as C, ammonium chloride 20 mg / L as N, and sodium dihydrogen phosphate 1.0 mg / L as P as substrates, and the following conditions were adopted as the biocide addition conditions.

[0158] 〔Comparative Example 3-1〕 The organic slime inhibitor Cl-MIT was continuously added at 0.5 mg / L as the drug mass (Cl-MIT), and the RO membrane device was continuously supplied with water at all times. As a result, the treated water containing the drug was continuously supplied to the downstream RO membrane device.

[0159] 〔Example 3-1〕 The continuous addition of the organic slime inhibitor in the second step "at all times" and the continuous addition of the oxidation slime inhibitor in the first step "at regular intervals for a certain period of time" were carried out in parallel. Thus, an oxidation-based slime inhibitor is intermittently added, and the treated water containing the oxidation-based slime inhibitor is continuously passed through the reverse osmosis membrane device for a "certain period of time". On the other hand, an organic-based slime inhibitor is continuously added at all times at least "during the period other than the addition period of the first step", and the treated water containing the organic-based slime inhibitor is continuously passed through the reverse osmosis membrane device at all times. As a result, the treated water containing the organic-based slime inhibitor, the treated water containing both the oxidation-based slime inhibitor and the organic-based slime inhibitor, the treated water containing the organic-based slime inhibitor... are supplied to the reverse osmosis membrane device in this order.

[0160] Specifically, Cl-MIT, which is an organic-based slime inhibitor used in the second step, is continuously passed through at a constant rate of 0.5 mg / L as the drug mass (Cl-MIT), and the treated water containing the drug is continuously passed through the RO membrane device downstream at all times. In addition, monochlorosulfamic acid, which is an oxidation-based slime inhibitor in the first step, is continuously added at 25 mg / L as T-Cl for 1 hour from 9:00 to 10:00 every other day, and the treated water containing the drug is continuously passed through the RO membrane device downstream for a predetermined period.

[0161] The results up to the 19th day in Example 3-1 and Comparative Example 3-1 are shown in FIG. 5. Clearly, the increase in differential pressure was blunted in Example 3-1, suggesting that the method in Example 3-1 has a very excellent slime inhibition function. Furthermore, in Example 3-1, the oxidation-based slime inhibitor was implemented at a high concentration, but since the change in differential pressure was below 10 KPa even after 16 days, very good slime inhibition was obtained, and it was also confirmed that the slime inhibition function can be exerted well.

[0162] <Test Example 4> The treated water obtained by adding to raw water the following substances as substrates: 30 mg / L of ethanol as C, 10 mg / L of ammonium chloride as N, and 0.5 mg / L of sodium dihydrogen phosphate as P was used. The temperature of the treated water was set and adjusted to 20°C. A test was conducted under the same conditions as in the above <Test Example 1>, except that the addition period and addition concentration of the slime inhibitor were set as shown in Table 2.

[0163] In the case of "intermittent addition (daily from 9:00 to 9:30)" in Table 2, the oxidation-based slime inhibitor was continuously added from 9:00 to 9:30 every day, and no addition was made during the period from 9:30 to 9:00 the next day. The oxidation-based slime inhibitor was continuously added for "30 minutes", and the treated water containing the chemical was continuously passed through the downstream RO membrane device for "30 minutes".

[0164] In the case of "intermittent addition (daily from 21:00 to 21:30)" in Table 2, the organic-based slime inhibitor was continuously added from 21:00 to 21:30 every day, and no addition was made during the period from 21:30 to 21:00 the next day. The organic-based slime inhibitor was continuously added for "30 minutes", and the treated water containing the chemical was continuously passed through the downstream RO membrane device for "30 minutes".

[0165] In the case of "continuous addition" in Table 2, the chemical was continuously added "constantly" from the start to the end of the test. During this period, the chemical was continuously added "constantly", and the treated water containing the chemical was continuously passed through the RO membrane device "constantly".

[0166] Also, in Comparative Examples 4-6, Comparative Example 4-7, and Example 4-1, as shown in Table 2, the first step and the second step were performed in parallel.

[0167] The following Table 2 shows the chemical addition conditions and the number of days required for the differential pressure to reach 100 kPa. As shown in Table 2, the result was obtained, suggesting that the treatment process of performing the first addition step of intermittently adding the oxidation-based slime inhibitor and the second addition step of constantly adding the organic-based slime inhibitor in parallel had the longest clogging days and the most excellent slime inhibition effect.

[0168]

Table 2

Explanation of Symbols

[0169] 1 water system; 2 reverse osmosis membrane device; 3 security filter; 4 solid-liquid separation device; 5 condensation device; 10 First chemical addition device; Second chemical addition device

Claims

1. A first step of intermittently adding an oxidation-based slime inhibitor and intermittently supplying treated water containing the oxidation-based slime inhibitor to a reverse osmosis membrane device; A second step of adding an organic-based slime inhibitor at least during a period other than the addition period of the first step and supplying treated water containing the organic-based slime inhibitor to the reverse osmosis membrane device, and having, In the first step, the addition period of the oxidation-based slime inhibitor and the non-addition period of the oxidation-based slime inhibitor are repeated, and the non-addition period of the oxidation-based slime inhibitor is longer than the addition period of the oxidation-based slime inhibitor. In the first step, the supply of the oxidation-based slime inhibitor to the reverse osmosis membrane device is not continuous and includes a non-supply period during which the oxidation-based slime inhibitor is not supplied. When the organic-based slime inhibitor in the second step is continuously added, the oxidation-based slime inhibitor is intermittently added, or When the second step has a non-addition period and an addition period of the organic-based slime inhibitor, the oxidation-based slime inhibitor is added during the non-addition period of the organic-based slime inhibitor and not added during the addition period of the organic-based slime inhibitor. Adjust the addition concentration of the oxidation-based slime inhibitor to be higher than the addition concentration of the organic-based slime inhibitor. The addition concentration of the oxidation-based slime inhibitor is 0.1 to 600 mg / L in terms of total chlorine concentration, and the addition concentration of the organic-based slime inhibitor is 0.01 to 100 mg (as drug mass) / L. The oxidation-based slime inhibitor is a drug containing a bound halogen compound (excluding halocyanoacetamide compounds), and the organic-based slime inhibitor is an organic-based slime inhibitor other than the bound halogen compound (excluding halocyanoacetamide compounds). A method for operating a reverse osmosis membrane device for obtaining permeated water obtained by treating treated water containing the oxidation-based slime inhibitor and / or the organic-based slime inhibitor with a reverse osmosis membrane.

2. The method for operating a reverse osmosis membrane device according to Claim 1, wherein the oxidation-based slime inhibitor is added one or more times within 3 days of the operation period.

3. The method for operating a reverse osmosis membrane device according to Claim 1 or 2, wherein the oxidation-based slime inhibitor is added for 10 minutes or more each time.

4. The method for operating a reverse osmosis membrane device according to Claim 1 or 2, wherein the non-addition period of the oxidation-based slime inhibitor is 10 minutes or more and 300 minutes or less.

5. A first step of intermittently adding an oxidation-based slime inhibitor and intermittently supplying treated water containing the oxidation-based slime inhibitor to a reverse osmosis membrane device; A second step of adding an organic-based slime inhibitor at least during a period other than the addition period of the first step and supplying treated water containing the organic-based slime inhibitor to the reverse osmosis membrane device, and having, In the first step, the addition period and the non-addition period of the oxidation-based slime inhibitor are repeatedly performed, and the non-addition period of the oxidation-based slime inhibitor is longer than the addition period of the oxidation-based slime inhibitor. In the first step, the supply of the oxidation-based slime inhibitor to the reverse osmosis membrane device is not continuously performed, and includes a non-supply period during which the oxidation-based slime inhibitor is not supplied. When the organic-based slime inhibitor in the second step is continuously added, the oxidation-based slime inhibitor is intermittently added, or When the second step has a non-addition period and an addition period of the organic-based slime inhibitor, the oxidation-based slime inhibitor is added during the non-addition period of the organic-based slime inhibitor and not added during the addition period of the organic-based slime inhibitor. The addition concentration of the oxidation-based slime inhibitor is adjusted to be higher than the addition concentration of the organic-based slime inhibitor. The addition concentration of the oxidation-based slime inhibitor is 0.1 to 600 mg / L in terms of total chlorine concentration, and the addition concentration of the organic-based slime inhibitor is 0.01 to 100 mg (as drug mass) / L. The oxidation-based slime inhibitor is a drug containing a bound halogen compound (excluding halocyanoacetamide compounds), and the organic-based slime inhibitor is an organic-based slime inhibitor other than a bound halogen compound (excluding halocyanoacetamide compounds). A slime control method applicable to a reverse osmosis membrane device for obtaining permeated water obtained by treating treated water containing the oxidation-based slime inhibitor and / or the organic-based slime inhibitor with a reverse osmosis membrane.

6. A water treatment device that implements the operation method of the reverse osmosis membrane device according to any one of claims 1 to 4 or the slime control method applicable to the reverse osmosis membrane device according to claim 5.

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