OPERATING METHODS FOR REVERSE OSMOSIS MEMBRANE AND WATER TREATMENT EQUIPMENT

Abstract

The invention relates to a technique by which a reverse osmosis membrane water system can be operated stably for an extended period of time. The invention relates to a method of operating a reverse osmosis membrane system which comprises the following steps: firstly, intermittent addition of an oxidizing viscous inhibitor and intermittent supply of water to be treated containing the oxidizing viscous inhibitor to the reverse osmosis membrane system; and secondly, addition of an organic viscous inhibitor at least for a period different from the addition period of the first step, and the supply of water to be treated containing the organic viscous inhibitor to the reverse osmosis membrane system.

Description

Method for operating a reverse osmosis membrane device

[0001] The present invention relates to a method for operating a reverse osmosis membrane device, a slime control method applied to a reverse osmosis membrane device, and a water treatment device for carrying out the method.

[0002] Reverse osmosis membranes (RO membranes) provided in reverse osmosis membrane devices have traditionally been used to remove ions, organic matter, etc. from raw water in seawater desalination, ultrapure water production, industrial water treatment, wastewater recovery treatment, wastewater reuse, etc. In water systems equipped with reverse osmosis membrane devices, microorganisms such as bacteria and microalgae contained in the water to be treated secrete extracellular substances (e.g., extracellular polysaccharides) to form slime (biofilm), and this slime adheres to and accumulates on the reverse osmosis membrane during water supply, or the microorganisms contained in the slime adhered to the reverse osmosis membrane further increase the slime, causing problems such as biofouling (clogging of the membrane by slime, etc.).

[0003] Conventionally, the method for removing slime that has adhered to and grown on the reverse osmosis membrane surface has been to stop the operation of the reverse osmosis membrane device and wash the reverse osmosis membrane with chemicals such as caustic soda to remove the slime. However, this method interferes with the continuous operation of the reverse osmosis membrane device and increases running costs.

[0004] In recent years, a method has been used in which slime inhibitors are injected into the water system supplied to the reverse osmosis membrane device without stopping the operation of the reverse osmosis membrane device to remove slime (biofilm) adhering to the reverse osmosis membrane surface. For such methods, various types of compounds have been investigated as slime inhibitors, and many slime inhibition methods using these 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 membrane-treating the raw water containing the slime control agent to which the slime control agent has been added, an ultraviolet irradiation treatment step of ultraviolet-irradiating the membrane-treated water, and an ion exchange treatment step of ion-exchanging the ultraviolet-irradiated liquid.

[0006] Furthermore, Patent Document 2 discloses a slime suppression method for a membrane reverse osmosis membrane device, which is a slime suppression method applied to a water-passing step for treating water, and includes a first water-passing step in which 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 to the water-to-be-treated, the pH of which has been adjusted to 10 or less, and the water-to-be-treated is passed through a reverse osmosis membrane:

[0007] JP 2009-247992 A JP 2020-28865 A WO2011 / 125762

[0008] JS Vrouwenvelder et. al., "Biofouling of Spiral Wound Membrane Systems" IWA Publishing (2011).

[0009] Typically, when the reverse osmosis membrane device is operated for a long period of time, slime generated in the water system adheres to the reverse osmosis membrane provided in the reverse osmosis membrane device, and 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. However, the need to readjust the device when restarting the reverse osmosis membrane device after stopping it, and the increased frequency of membrane replacement or cleaning of the reverse osmosis membrane device, lead to increased running costs. For this reason, the inventors decided to consider operating the reverse osmosis membrane device for a long period of time by ensuring as many blocking days as possible so as to minimize the need to stop the operation of the reverse osmosis membrane device.

[0010] That is, a main object of the present invention is to provide a technology that enables a water system having a reverse osmosis membrane device to be operated for a longer period of time.

[0011] As a result of extensive research, the present inventors have discovered that in an aqueous system having a reverse osmosis membrane device, by combining a first step of intermittently adding an oxidizing slime inhibitor to the water to be treated with a second step of adding an organic slime inhibitor to the water to be treated and controlling the operation of these steps, the aqueous system having the reverse osmosis membrane device can be operated for a longer period of time. The present inventors have also found that this can more effectively reduce the amount of slime present in the reverse osmosis membrane of the reverse osmosis membrane device or more effectively suppress the increase of slime, thereby more effectively suppressing biofouling. The present inventors have then completed the present invention as follows.

[0012] The present invention provides a method for operating a reverse osmosis membrane apparatus, comprising: a first step of intermittently adding an oxidative slime inhibitor and intermittently supplying water to be treated containing the oxidative slime inhibitor to a reverse osmosis membrane apparatus; and 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 water to be treated containing the organic slime inhibitor to the reverse osmosis membrane apparatus. Note that the "at least" in "at least the period other than the addition period of the first step" means that the organic slime inhibitor is added during at least "all or part of the period other than the addition period of the first step" of the "addition period of the first step (first intermittent addition period)" and the "period other than the addition period of the first step (first non-addition period)." For example, the organic slime inhibitor may be added during both the first non-addition period and the first intermittent addition period, or may be added only during the first non-addition period (see, for example, Figures 1 and 2). The present invention provides a slime control method applicable to a reverse osmosis membrane device, comprising: a first step of intermittently adding an oxidative slime inhibitor and intermittently supplying water to be treated containing the oxidative slime inhibitor to a reverse osmosis membrane device; and 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 water to be treated containing the organic slime inhibitor to the reverse osmosis membrane device. The present invention also provides a water treatment device that implements the method for operating the reverse osmosis membrane device or the slime control method applicable to the reverse osmosis membrane device.

[0013] The concentration of the oxidative slime inhibitor may be adjusted to be higher than the concentration of the organic slime inhibitor. The oxidative slime inhibitor may be added one or more times during a three-day operating period. The oxidative slime inhibitor may be added for 10 minutes or more per addition. The oxidative slime inhibitor may be added to a total chlorine concentration of 0.1 mg / L or more. The organic slime inhibitor may be added to a total chlorine concentration of 0.01 mg / L or more.

[0014] According to the present invention, a technology can be provided that enables a water system having a reverse osmosis membrane device to be operated for a longer period of time. Note that 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.

[0015] FIG. 1 is a schematic diagram showing an example of control of the first and second addition steps according to an embodiment of the present invention. a1: In the first addition step, the oxidative slime inhibitor is added intermittently at equal intervals. b1: In the second addition step, the organic slime inhibitor is added continuously. At this time, the organic slime inhibitor is added at least during the period other than the addition period of the first addition step. The horizontal axis represents the operating period (hours), and the vertical axis represents the amount added. FIG. 1 is a schematic diagram showing an example of control of the first and second addition steps according to an embodiment of the present invention. a2: In the first addition step, the oxidative slime inhibitor is added intermittently at equal intervals. b2: In the second addition step, the organic slime inhibitor is added continuously during the period other than the addition period of the first addition step. The horizontal axis represents the operating period (hours), and the vertical axis represents the amount added. FIG. 2 is an example of a schematic diagram showing a water system having a reverse osmosis membrane device according to an embodiment of the present invention. In Test Example 2, this figure shows the change in differential pressure (kPa) for Comparative Example 2-1 (●) and Example 2-1 (◆) per water flow period (days). FIG. 10 is a graph showing the change in differential pressure (kPa) for Comparative Example 3-1 (●) and Example 3-1 (♦) over the water flow period (days) in Test Example 3.

[0016] Hereinafter, embodiments for carrying out the present invention will be described. Note that the embodiment described below shows one example of a typical embodiment of the present invention, and is not to be construed as limiting the scope of the present invention. Note that the upper and lower limit values ​​of the numerical values ​​can be arbitrarily combined as desired.

[0017] 1. Operating Method of a Reverse Osmosis Membrane Device According to the Present Invention The present invention provides a method for operating a reverse osmosis membrane device, comprising: a first step of intermittently adding an oxidative slime inhibitor and intermittently supplying the treated water containing the oxidative slime inhibitor to the reverse osmosis membrane device; and 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. As used herein, the term "slime inhibitor" refers to an agent capable of suppressing slime buildup, and may include agents capable of reducing or removing slime present in the membrane, agents capable of killing microorganisms (such as bactericides and algicides), and agents capable of suppressing microbial growth (such as antibacterial agents). Furthermore, the designations "first" and "second" used in the first step, second step, etc., are used for convenience of explanation, and the use of "first" and "second" does not limit the present invention in a narrow sense or in any particular way.

[0018] The oxidative slime inhibitor used in this embodiment is a component or agent that can at least inhibit slime derived from microorganisms (e.g., bacteria, fungi, microalgae, etc.) through an oxidation-reduction reaction, or an agent containing such an active ingredient, and can be detected by the DPD method. However, in this specification, a halocyanoacetamide compound (preferably DBNPA) is classified as an organic slime inhibitor because it has an enzyme metabolic function inhibitory effect.

[0019] The organic slime inhibitor used in this embodiment is a component or agent, or an agent containing such an active ingredient, that can inhibit biological functions by reacting with the metabolic functions (enzymes, etc.) of microorganisms and the cells (e.g., SH groups) of microorganisms, thereby at least suppressing slime derived from microorganisms (e.g., bacteria, fungi, microalgae, etc.).

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

[0021] 1-1-1. First Addition Step The first step is a step of intermittently adding an oxidative slime inhibitor to the water to be treated. This allows the water to be treated containing the oxidative slime inhibitor, and the water to be treated containing the oxidative slime inhibitor after the addition can be intermittently supplied to a reverse osmosis membrane device (see, for example, Figures 1 and 2).

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

[0023] The oxidative slime inhibitor is preferably added at least once within a predetermined period, preferably every 5 days, more preferably every 4 days, even more preferably every 3 days, even more preferably every 2 days, and even more preferably every 1 day. The "predetermined period" may be replaced by "at predetermined intervals," such as once every 3 days or once every 1 day. The oxidative slime inhibitor may also be added at one or more times per day, for example, every 1-2 days (more preferably every 1 day). The number of times the oxidative slime inhibitor is added is not particularly limited, but a suitable upper limit is preferably 10 times or less, more preferably 5 times or less, even more preferably 3 times or less, even more preferably 2 times or less, and even more preferably once. This number of additions may be "within a predetermined period" or "at predetermined intervals." A more preferred embodiment of the oxidative slime inhibitor addition frequency is preferably at least once per 3 days, more preferably at least once per 2 days, and even more preferably at least once per day.

[0024] The addition period of the oxidative slime inhibitor is not particularly limited, but a suitable lower limit per addition (period) is preferably 0.1 minute or more, more preferably 1 minute or more, even more preferably 10 minutes or more, and even more preferably 30 minutes or more, and a suitable upper limit is preferably 1000 minutes or less, more preferably 500 minutes or less, even more preferably 300 minutes or less, and even more preferably 120 minutes or less. The suitable numerical range 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 oxidative 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 oxidative slime inhibitor" refers to "the addition period from the start of addition of the oxidative slime inhibitor to the end of addition of the oxidative slime inhibitor," more preferably refers to "the period during which the oxidative 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 oxidative slime inhibitor is continuously added without being stopped." In this specification, "one period (specifically, the addition period from the start of addition of the agent to the end of addition of the agent)" of the "addition period of the oxidative slime inhibitor" may also be considered as "one unit."

[0026] In this specification, the "period during which no oxidative slime inhibitor is added" is also referred to as "a period other than the period during which the oxidative slime inhibitor is added," "a period other than the period during which the first step is added," or "a 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 no oxidative slime inhibitor is added" refers to "the period from the end of the addition of the oxidative slime inhibitor to the start of the addition of the oxidative slime inhibitor (i.e., the non-addition period)," more preferably refers to a period during which the oxidative 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 "a period during which no oxidative slime inhibitor is added and no oxidative slime inhibitor is continuously added." In this specification, "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)" of the above "period during which no oxidative slime inhibitor is added" may be considered as "one unit."

[0027] The concentration of the oxidizing slime inhibitor added to the aqueous system (mg / 1 L of aqueous system (as total chlorine concentration)) is not particularly limited, but as a 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, even 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, and a suitable upper limit is preferably 600 mg / L or less, more preferably 60 mg / L or less. The suitable numerical range is preferably 0.1 to 600 mg / L, more preferably 2 to 60 mg / L.

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

[0029] The absolute amount (mg / (L / h)) of the oxidizing slime inhibitor to be added to the water system per addition period is not particularly limited, but may be calculated by multiplying the addition period of the oxidizing slime inhibitor per unit by the addition concentration of the oxidizing slime inhibitor at that time (mg / L (as Total chlorine concentration))) As a total chlorine concentration, a suitable lower limit is preferably 0.05 mg / (L / h) or more, more preferably 0.1 mg / (L / h) or more, even 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, and a suitable upper limit is preferably 10000 mg / (L / h) or less, more preferably 10000 mg / (L / h) or less, even 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. The preferred numerical range is preferably 0.05 to 10,000 mg / (L / h), more preferably 2.5 to 5,000 mg / (L / h), and even more preferably 2.5 to 1,000 mg / (L / h).

[0030] Furthermore, the first addition step includes a period during which the oxidative slime inhibitor is added to the aqueous system by intermittently adding the oxidative slime inhibitor (hereinafter also referred to as the "first intermittent addition period") and a period during which the oxidative slime inhibitor is not added (hereinafter referred to as the "first non-addition period"), and it is preferable that these periods be carried out sequentially or in any order. Sequential carrying out is preferable, and in this case, either the first intermittent addition period or the first non-addition period may come first, and either the first intermittent addition period may be followed by the first non-addition period, or the first non-addition period may be followed by the first intermittent addition period. Furthermore, the number of first intermittent addition periods and first non-addition periods during the entire operating period of the aqueous system may each be one or more.

[0031] One unit of the first intermittent addition period is not particularly limited, but the configuration described above in the "Oxidative Slime Inhibitor Addition Period" can be adopted, and the preferred numerical range is preferably 1 to 1000 minutes, more preferably 10 to 300 minutes.

[0032] One unit of the first addition-free period is not particularly limited, but a suitable lower limit is preferably 1 hour or more, more preferably 3 hours or more, even more preferably 5 hours or more, and even more preferably 10 hours or more, and a suitable upper limit is preferably 200 hours or less, more preferably 150 hours or less, even more preferably 100 hours or less, and even more preferably 50 hours or less. The suitable numerical range is preferably 5 to 100 hours, and more preferably 10 to 50 hours.

[0033] The ratio of the first intermittent addition period per unit to 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 from the perspective of reducing the amount of added chemicals used in the aqueous system while stably operating the aqueous system over the long term, it is preferable that the first intermittent addition period per unit be shorter than the first non-addition period per unit. The 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, even more preferably 1:5 to 100, and even more preferably 1:7 to 50.

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

[0035] <Oxidative Slime Inhibitor> The oxidative slime inhibitor or its components are not particularly limited, but examples thereof include bonded halogen compounds. The oxidative slime inhibitor may be a chemical containing a bonded halogen compound, with examples of halogens including chlorine and bromine. Examples of the bonded halogen compound include bonded chlorine compounds and bonded bromine compounds, and one or more selected from these may be used. Examples of the bonded chlorine compounds include stabilized chlorine compounds, such as halogenated hydantoin compounds, and chloramine compounds. Examples of the bonded bromine compounds include stabilized bromides and halogenated hydantoin compounds, but are not limited thereto, and one or more selected from these may be used. The oxidative slime inhibitor or the compounds used in the oxidative slime inhibitor may be commercially available products, or may be obtained by known manufacturing methods.

[0036] The 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 and organic ammonium salts; and amino acid salts such as guanidine salts. One or more selected from these may be used.

[0037] <Chloramine Compound> A 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 a material containing a stabilizer and a chlorine-based oxide; chlorosulfamic acid compounds produced from a material containing a sulfamic acid compound and a chlorine-based oxide; 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 preferred examples include compounds having an amino group such as ammonia salts and sulfamic acid compounds, and one or more selected from these can be used. In this 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, and ammonium chloride, 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 R １ R ２ NSO ３ It is preferable that the compound is represented by the general formula [1]. １ , R ２ are preferably each independently H or an alkyl group having 1 to 8 carbon atoms or a functional group containing a benzene ring. １ Groups and R ２Sulfamic acid (amidosulfuric acid) or its salts in which both R groups are hydrogen atoms; N-methylsulfamic acid, N-ethylsulfamic acid, N-propylsulfamic acid, N-isopropylsulfamic acid, N-butylsulfamic acid, etc. １ Groups and R ２ sulfamic acid or a salt thereof in which one of the groups is a hydrogen atom and the other is an alkyl group having 1 to 8 carbon atoms; sulfamic acid or a salt thereof in which two R groups are hydrogen atoms and the other is an alkyl group having 1 to 8 carbon atoms, such as N,N-dimethylsulfamic acid, N,N-diethylsulfamic acid, N,N-dipropylsulfamic acid, N,N-dibutylsulfamic acid, N-methyl-N-ethylsulfamic acid, and N-methyl-N-propylsulfamic acid; １ Groups and R ２ sulfamic acid or a salt thereof, both of whose groups are alkyl groups having 1 to 8 carbon atoms; etc. One or more selected from these may be used.

[0041] The chlorine-based oxide is not particularly limited, but for example, chlorine gas, chlorine dioxide, hypochlorous acid or its salt, chlorous acid or its salt, chloric acid or its salt, perchloric acid or its salt, chlorinated isocyanuric acid or its salt, etc., can be selected from these, or two or more can be used. Examples of hypochlorites include alkali metal hypochlorites such as sodium hypochlorite and potassium hypochlorite; alkaline earth metal hypochlorites such as calcium hypochlorite and barium hypochlorite; and one or two or more can be used. Examples of chlorites 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; and one or two or more can be used. Examples of chlorates include ammonium chlorate; alkali metal chlorates such as sodium chlorate and potassium chlorate; alkaline earth metal chlorates such as calcium chlorate and barium chlorate; and one or more selected from these can be used. Examples of perchlorates include sodium perchlorate and potassium perchlorate, and one or more selected from these can be used. Examples of chlorinated isocyanurates include chlorinated sodium isocyanurate, and one or more selected from these can be used.

[0042] An example of a method for producing a chloramine compound is to mix an aqueous solution of a stabilizer (e.g., an aqueous solution of a sulfamic acid compound) with an aqueous solution of a chlorine-based oxide (e.g., an aqueous solution of sodium hypochlorite) in the presence of an alkali. The chloramine compound can be produced from at least the stabilizer and the chlorine-based oxide. The pH of the produced agent containing the chloramine compound is preferably 12 or higher, more preferably 13 or higher. For example, a method described in the Examples of Patent Document 3 (WO 2011 / 125762; Japanese Patent Publication No. 5720964) can be referred to as an example of producing sodium chlorosulfamate. The ratio of the chlorine-based oxide to the stabilizer (e.g., an ammonia salt, a sulfamic acid compound, etc.) is not particularly limited, but the total chlorine concentration (Cl ) of the chlorine-based oxidizing agent can be adjusted. ２ The amount of the chlorine stabilizer (suitably a sulfamic acid compound) is preferably 0.5 to 5.0 moles, more preferably 0.5 to 2.0 moles, and even more preferably 1.0 to 1.5 moles per mole of alkali metal. This ratio may be the content ratio in the chemical. The ratio of alkali to chlorine-based oxide used is preferably 0.3 to 0.4, more preferably 0.30 to 0.36, in terms of Cl / alkali metal (molar ratio), and this ratio may be the content ratio in the chemical.

[0043] As the sulfamic acid compound, R １ , R ２ Sulfamic acid in the narrow sense, where each of the groups 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 be used in the form of a free (powdered) acid, or may be a salt such as an alkali metal salt, e.g., sodium salt, potassium salt, or lithium salt. One or more types selected from these may be used.

[0044] Chlorosulfamic acid is sulfamic acid (H ２ NSO ２ NH ２It refers to a group in which at least one hydrogen atom is substituted with a chlorine atom. Examples of chlorosulfamic acids include monochlorosulfamic acid and dichlorosulfamic acid.

[0045] Chlorosulfamate is sulfamic acid (H ２ NSO ２ Chlorosulfamate refers to a compound in which at least one hydrogen atom of the OH group of a chloramine compound (chloramine ion) has been substituted with a metal ion (e.g., an alkali metal ion such as a lithium ion, a sodium ion, or a potassium ion). Examples of chlorosulfamates include lithium chlorosulfamate, sodium chlorosulfamate, and potassium chlorosulfamate, and one or more selected from these can be used. Among these, sodium chlorosulfamate is preferred. Another chloramine compound that can be used is chloramine T. One or more selected from these can be used.

[0046] <Stabilized Bromide> A stabilized bromide refers to a compound having at least one nitrogen atom (N—Cl bond) or a bond between a carbon atom and a bromine atom (C—Br bond). A stabilized bromide is preferably a bromide that is unlikely to undergo changes such as decomposition in water and that can produce a bromide that can exist stably in water. Examples of stabilized bromides include, but are not limited to, the reaction product of a "reaction product of a bromine-based oxidizing agent or a bromine compound with a chlorine-based oxide" and a "sulfamic acid compound." The pH of the reaction product is preferably alkaline, more preferably 11 or higher, even more preferably 12 or higher, and even more preferably 13 or higher. These may be commercially available products, or products obtained by known production methods may be used.

[0047] The bromine-based oxidizing agent is not particularly limited, but examples thereof include bromine (liquid bromine), bromine chloride, bromic acid, bromates, and hypobromous acid, and one or more selected from these may be used.

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

[0049] The chlorine-based oxides used in the stabilized bromides (e.g., hypochlorite, chlorite, chlorate, perchlorate, chlorinated isocyanurate, etc.) are the same as those described above in the section on "chlorine-based oxides" in <Chloramine Compounds>, ​​and the structures and the like of the same description can be appropriately adopted. Among these, hypochlorite (e.g., sodium hypochlorite) is preferred.

[0050] The "sulfamic acid compound" refers to the sulfamic acid compound constituting the "chlorosulfamic acid compound" in the above <Chloramine compound>. １ R ２ NSO ３ The explanation of "sulfamic acid compound" in "compound represented by H...[1]" applies to these compounds, and the structure of the explanation can be appropriately adopted. Among "sulfamic acid compounds", sulfamic acid or a salt thereof is preferred.

[0051] An example of a method for producing a stabilized bromide is to mix an aqueous sodium bromide solution with sodium hypochlorite to prepare mixed solution 1, and then mix an aqueous sulfamic acid solution with an aqueous sodium hydroxide solution to prepare mixed solution 2, and then mix mixed solution 1 and mixed solution 2 in the presence of an alkali. For example, bromamine, bromosulfamic acid, and bromosulfamate, which are composed of an ammonium salt and bromine, or other compounds such as DBNPA can be used.

[0052] <Halogenated Hydantoin Compound> Examples of halogenated hydantoin compounds 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, and one or more selected from these can be used. Of these, BCDMH and 1,3-dichloro-5,5-dimethylhydantoin are preferred from the viewpoints of the balance of the dissolution rate with the solid preparation (B) when contacted with water, ease of availability, and the like.

[0053] The halogenated hydantoin compound may be a commercially available product or may be obtained by a known production method. For example, a hydantoin compound (e.g., hydantoin (chemical formula: C ３ H ４ N ２ O ２ ) or the like) as a stabilizer, and reacting the stabilizer with the chlorine-based oxide and / or bromine-based oxidizing agent. Examples of the hydantoin compound include compounds having a hydantoin skeleton. Examples of the hydantoin compound include hydantoin and 5,5-dialkylhydantoins (e.g., 5,5-dimethylhydantoin, 5-methylethylhydantoin, 5-methylbutylhydantoin, and 5-ethylbutylhydantoin). One or more selected from these can be used. The "dialkyl" may be the same or different alkyl groups. Examples of the alkyl groups include those having 1 to 5 carbon atoms (preferably 1 to 3 carbon atoms). These alkyl groups may be linear or branched, and examples include methyl, ethyl, and butyl groups. One or more selected from these can be used.

[0054] The oxidative slime inhibitor may contain optional components or optional chemicals as long as they do not impair the effects of the present invention. Examples of optional components or optional chemicals include, but are not limited to, anticorrosive agents (corrosion inhibitors), scale inhibitors, slime control agents, solvents or dispersion media such as water, dispersant enzymes, bactericides, and antifoaming agents. Various chemicals generally used in water treatment may also be used. One or more of these optional components or optional chemicals may be appropriately selected. Furthermore, in the first step of this embodiment, in addition to the addition or use of the oxidative slime inhibitor, additional optional components or optional chemicals 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 oxidizing slime inhibitor to the reverse osmosis membrane device. By combining this first supply step with the second supply step in the second step described below, the water system can be operated for a longer period of time. In a more preferred embodiment, biofouling that occurs in the reverse osmosis membrane provided in the reverse osmosis membrane device can be suppressed, and by suppressing this biofouling, the water system can be operated stably for a long period of time.

[0056] In the first supply process, when the treated water containing an oxidative slime inhibitor is intermittently supplied to the reverse osmosis membrane device, there is a period during which the treated water containing the oxidative slime inhibitor is supplied (also referred to as the "first intermittent supply period") and a period during which the treated water containing the oxidative slime inhibitor is not supplied (also referred to as the "first non-supply period").

[0057] The various conditions in the first supply step can be appropriately selected from the configurations described above in "1-1-1. First Addition Step." For example, the supply frequency and predetermined period, number of supplies, supply frequency, supply period, supply concentration of the oxidative slime inhibitor relative to the aqueous system, absolute amount of the oxidative slime inhibitor supplied to the aqueous system per supply period, one unit of the first supply period, and the ratio of the first intermittent supply period per unit to the first non-supply period per unit, etc., in the first supply step can be appropriately selected from the addition frequency and predetermined period, number of supplies, addition frequency, addition period, addition concentration of the oxidative slime inhibitor relative to the aqueous system, absolute amount of the oxidative slime inhibitor added to the aqueous system per addition period, one unit of the first addition period, and the ratio of the first intermittent supply 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 the oxidative slime inhibitor is not particularly limited, but is preferably supplied at least once within a predetermined period, and more preferably once within the predetermined period. This supply frequency may be "within a predetermined period" or "at predetermined intervals." The number of times the oxidative slime inhibitor is supplied is not particularly limited, but a preferred upper limit is more preferably two times or less, and even more preferably once. The supply frequency of the water to be treated containing the oxidative slime inhibitor is preferably supplied at least once within three days, more preferably once within two days (more preferably every other day), and even more preferably once or more within a day. Furthermore, this supply frequency may be "within a predetermined period" or "at predetermined intervals." A more preferred embodiment of the supply frequency of the oxidative slime inhibitor is preferably supplied at least once within three days, and more preferably once or more within a day.

[0059] The supply period of the treated water containing the oxidative slime inhibitor is not particularly limited, but a suitable numerical range per supply (period) 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 water to be treated containing an oxidative slime inhibitor" refers to the "supply period from the start of supply of the oxidative slime inhibitor to the end of supply of the oxidative slime inhibitor," and in a narrower sense, refers to the "period during which the supply of the oxidative slime inhibitor is continuously supplied without being stopped." Furthermore, in this specification, the "supply period of water to be treated containing an oxidative slime inhibitor" is also referred to as the "supply period of the first step" or the "first intermittent supply period." Furthermore, in this specification, "one period (specifically, the supply period from the start of supply of the agent to the end of supply of the agent)" of the "supply period of water to be treated containing an oxidative slime inhibitor" may be considered to be "one unit."

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

[0062] The supply concentration of the oxidative slime inhibitor to the aqueous system (mg of agent / L of aqueous system) is not particularly limited, but as a 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, even more preferably 2 mg / L or more, still more preferably 5 mg / L or more, more preferably 10 mg / L or more, and even more preferably 25 mg / L or more, and a suitable numerical range is preferably 5 to 500 mg / L, more preferably 25 to 300 mg / L.

[0063] The absolute amount (mg x hour) of the oxidative 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 oxidative slime inhibitor per unit x the supply concentration of the oxidative slime inhibitor at that time", and the preferred lower limit of the total chlorine concentration is preferably 0.05 mg / (L / h) or more, more preferably 0.1 mg / (L / h) or more, even 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, and even more preferably 25 mg / (L / h) or more, and also, as a preferred numerical range, preferably 0.05 to 10,000 mg / (L / h), more preferably 2.5 to 5,000 mg / (L / h), more preferably 10 to 1,000 mg / (L / h).

[0064] Furthermore, the first supply step includes a period in which the water to be treated containing the oxidative slime inhibitor is supplied to the reverse osmosis membrane device by supplying the water to be treated containing the oxidative slime inhibitor to the reverse osmosis membrane device (hereinafter also referred to as the "first intermittent supply period"), and a period in which the water to be treated containing the oxidative slime inhibitor is not supplied to the reverse osmosis membrane device (hereinafter also referred to as the "first non-supply period"). These periods are preferably carried out sequentially or in random order. Sequential operation is preferable. The order of the first intermittent supply period and the first non-addition supply period is preferably based on the order of the first intermittent addition period and the first non-addition period described above. Furthermore, the number of times each of the first intermittent supply period and the first non-supply period occurs during the entire operating period of the water system may be one or more.

[0065] One unit of the first intermittent supply period is not particularly limited, but a suitable numerical range is preferably 1 to 1,000 minutes, more preferably 10 to 300 minutes. One unit of the first non-supply period is not particularly limited, but a suitable numerical range is preferably 5 to 100 hours, more preferably 10 to 50 hours.

[0066] The ratio of the first intermittent supply period per unit to the first non-supply period per unit within 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 supply period per unit be shorter than the first non-supply period per unit, and even more preferably 1:7 to 1:50. The first intermittent supply period per unit may be an average value obtained by dividing the total period (e.g., days) of the first intermittent supply periods during a certain operating period by the number of first intermittent supply periods during this operating period. The first non-supply period per unit may be an average value obtained by dividing the total period (e.g., days) of the first non-supply periods during a certain operating period by the number of first non-supply periods during this operating period. 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 may be a period constituted by combining a plurality of the same or different "first intermittent supply periods per unit and the first non-supply period per unit." This single period or a combination of multiple periods is preferably based on the single period or a combination of multiple periods of the above-mentioned "first intermittent addition period per unit and first non-addition period per unit."

[0067] 1-2. Second step using organic slime inhibitor In the second step, it is preferable to add an organic slime inhibitor at least during a period other than the addition period of the first step, and supply the water to be treated containing the organic slime inhibitor to a reverse osmosis membrane device. Furthermore, it is preferable that the second step has a second addition step of adding the organic slime inhibitor, and a second supply step of supplying the water to be treated containing the added organic slime inhibitor to the reverse osmosis membrane device.

[0068] 1-2-1. Second Addition Step The second step is a step of adding an organic slime inhibitor at least during a period other than the addition period of the first step. This allows for the production of water to be treated containing the organic slime inhibitor, and the water to be treated containing the added organic slime inhibitor can be supplied to a reverse osmosis membrane device (see, for example, Figures 1 and 2).

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

[0070] Here, "adding at least during a period other than the addition period of the first step" in the second step can also be interpreted as "adding the organic slime inhibitor during at least the first non-addition period," but the organic slime inhibitor may be added during both the first non-addition period and the first intermittent addition period, or may be added only during the first non-addition period (see, for example, Figures 1 and 2). In the second step, the addition of the organic slime inhibitor during the first non-addition period may be addition of the organic slime inhibitor during the entire first non-addition period or a portion of the first non-addition period. Furthermore, in the second step, the addition of the organic slime inhibitor during the first intermittent addition period may be addition of the organic slime inhibitor during the entire first intermittent addition period or a portion of the first intermittent addition period.

[0071] In the second step, it is preferable to add an organic slime inhibitor for the entire first non-addition period or a part of the first non-addition period. The part of the first non-addition period is preferably 50% or more, more preferably 70% or more, even more preferably 90% or more, even more preferably 95% or more, more preferably 98% or more, even more preferably 99% or more, and even more preferably 100% (also referred to as the entire period) of the entire 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 a period other than the addition period of the first step," but continuous addition is even more preferable, and constant addition is even more preferable. Also, in the second step, it is more preferable to add the organic slime inhibitor continuously or discontinuously during at least the "first non-addition period per unit," but continuous addition is even more preferable.

[0073] In this specification, "discontinuous" means that there may be periods during which the organic slime inhibitor is added and periods during which it is stopped, as long as the effects of the present invention are not impaired. However, it is preferable that the period during which the addition is made is longer than the period during which it is stopped, and the period during which it is stopped is preferably within 1 / 10 of the period of addition, more preferably within 5 / 100, even more preferably within 2.5 / 100, and even more preferably within 1 / 500.

[0074] In this specification, the period during which the organic slime inhibitor is "continuously" added refers to "the period from the start of addition of the organic slime inhibitor to the end of addition of the organic slime inhibitor," more preferably refers to "the period during which the organic 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 organic slime inhibitor is continuously added without being stopped," which is also referred to as "a period of constant addition." An example of this "period of constant addition" is "0 minutes of non-addition period and 60 minutes of addition period" for a 60-minute operation period.

[0075] As used herein, "continuously" may include a period during which the drug is stopped, as long as the period is within the same range of effect as the constant addition of the present invention, and in a more specific preferred embodiment, the period during which the drug is stopped within one day is preferably 60 minutes or less, more preferably 30 minutes or less, even more preferably 15 minutes or less, even more preferably 5 minutes or less, and more preferably 0 minutes (also referred to as the "period of constant addition"). Also, the period during which the drug is stopped within one hour of operation is preferably 5 minutes or less, more preferably 1 minute or less, even more preferably 5 minutes or less, and more preferably 0 minutes (also referred to as the "period of constant addition").

[0076] The addition period of the organic slime inhibitor is not particularly limited, and may be, for example, the entire operation period of the reverse osmosis membrane device or the entire period of the first step, but in a more specific embodiment, the suitable lower limit per one time (one period) is preferably 0.1 day or more, more preferably 0.3 day or more, even more preferably 0.5 day or more, and even more preferably 1 day or more, and the suitable upper limit is preferably 30 days or less, more preferably 10 days or less, even more preferably 7 days or less, and even more preferably 3 days or less. The suitable numerical range is preferably 0.5 days or more and 7 days or less, and more preferably 1 day or more and 3 days or less.

[0077] The concentration of the organic slime inhibitor added to the aqueous system (mg (as chemical mass) / 1 L of aqueous system) is not particularly limited, but as a chemical mass, a suitable lower limit is preferably 0.001 mg / L or more, more preferably 0.01 mg / L or more, even more preferably 0.05 mg / L or more, and even more preferably 0.1 mg / L or more, and a suitable upper limit is preferably 10,000 mg / L or less, more preferably 1,000 mg / L or less, even more preferably 100 mg / L or less, and even more preferably 50 mg / L or less. The suitable numerical range is preferably 0.01 to 100 mg / L, more preferably 0.1 to 50 mg / L.

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

[0079] <Organic Slime Inhibitor> The organic slime inhibitor or its components are not particularly limited, but examples thereof include isothiazolinone compounds, halocyanoacetamide compounds, aldehyde compounds, and oxime compounds such as tetrazolyl oxime and dichloroglyoxime, and one or more of these can be used. The organic slime inhibitor may also be a drug containing one or more compounds selected from these. The organic slime inhibitor or the compound used in the organic slime inhibitor may be a commercially available product, or may be one obtained by a known manufacturing method.

[0080] <Isothiazoline Compound> The isothiazoline compound is not particularly limited, and examples thereof 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, and 4,5-dichloro-2-cyclohexyl-4-isothiazolin-3-one, and one or more of these may be used. In addition, the isothiazoline compound may be a complex compound of the above-mentioned isothiazoline compound with magnesium chloride, magnesium nitrate, copper chloride, copper nitrate, calcium chloride, or the like. One or more selected from these can be used. Among the isothiazoline compounds, 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT), 2-methyl-4-isothiazolin-3-one (MIT), or a mixture thereof is preferred.

[0081] <Halocyanoacetamide Compound> The halocyanoacetamide compound is not particularly limited, and examples thereof include 2-halo-3-nitrilopropionamides such as 2-chloro-3-nitrilopropionamide and 2-bromo-3-nitrilopropionamide; 2,2-dihalo-3-nitrilopropionamides such as 2,2-dichloro-3-nitrilopropionamide, 2,2-dibromo-3-nitrilopropionamide (DBNPA), and 2-chloro-2-bromo-3-nitrilopropionamide; N-methyl-2- Examples include N-C1-3 alkyl-2-halo-3-nitrilopropionamides such as chloro-3-nitrilopropionamide and N-methyl-2-bromo-3-nitrilopropionamide; and N-C1-3 alkyl-2,2-dihalo-3-nitrilopropionamides such as N-methyl-2,2-dichloro-3-nitrilopropionamide and N-methyl-2,2-dibromo-3-nitrilopropionamide, and one or more selected from these can be used. The halocyanoacetamide compound is NC-CX １ X ２ -(C=O)-NHR ３ In the general formula [2], X １ , X ２ each independently represents a halogen atom or a hydrogen atom; X １ , X ２ At least one of R is a halogen atom. ３ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of halogen atoms include a chlorine atom and a bromine atom, with a bromine atom being preferred. Examples of C1-3 alkyl groups include linear or branched chain alkyl groups, such as methyl, ethyl, n-propyl, and isopropyl groups. One or more groups selected from these groups can be used.

[0082] Among the halocyanoacetamide compounds, dihalonitrilopropionamides are preferred, and among these, 2,2-dibromo-3-nitrilopropionamide (DBNPA) is more preferred.

[0083] <Aldehyde Compound> The aldehyde compound is not particularly limited, but examples thereof include monoaldehyde compounds such as acetaldehyde; dialdehyde compounds such as glyoxal and orthophthalaldehyde; 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> The oxime compound is not particularly limited, but may be a compound having a tetrazole ring (CH ２ N ４ ) (e.g., tetrazolyl oxime, etc.), and halogenated oxime compounds (e.g., dichloroglyoxime, etc.), and one or more compounds selected from these can be used. The oxime compound is a compound having a structure represented by >C=N-OH in the molecule. An example of an oxime compound having a tetrazole ring is picarbutrazox (molecular formula: C ２０ H ２３ N ７ O ３ , molecular weight: 409.44, CAS No. 500207-04-5). Examples of the halogenated oxime compound include dichloroglyoxime, α-chlorobenzaldoxime, α-chlorobenzaldoxime acetate, 4-hydroxyphenyl-α-ketoacetohydroxime acid chloride (also known as Paracrox), and one or more compounds selected from these may 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] The organic slime inhibitor may contain optional components or optional chemicals as long as the effects of the present invention are not impaired. Furthermore, in the second step of this embodiment, in addition to the addition or use of the organic slime inhibitor, additional optional components or optional chemicals may be added or used as appropriate. The optional components or optional chemicals may be any of various chemicals that can generally be used in water treatment, and the structure of the "optional components or optional chemicals" described above in the "Oxidative Slime Inhibitor" section 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 an organic slime inhibitor to a reverse osmosis membrane device. By combining this second supply step with the first supply step in the first step, the water system can be operated for a longer period of time. In a more preferred embodiment, biofouling occurring in the reverse osmosis membrane provided in the reverse osmosis membrane device can be suppressed, and by suppressing this biofouling, the water system can be operated stably for a long period of time.

[0088] The various conditions in the second supply step can be appropriately selected from the configurations described above in "1-2-1. Second Addition Step." For example, the supply period in the second supply step, the supply concentration of the organic slime inhibitor relative to the aqueous system, the absolute amount of the organic slime inhibitor supplied to the aqueous system per supply period, and the like can be appropriately selected from the addition period, addition concentration of the organic slime inhibitor relative to the aqueous system, and the absolute amount of the organic slime inhibitor added to the aqueous system per addition period described above in "1-2-1. Second Addition Step."

[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 to the reverse osmosis membrane device continuously or discontinuously during the operation period, more preferably continuously, and even more preferably constantly. In this specification, the period during which the organic slime inhibitor is "continuously" supplied means "the supply period from the start of supply of the organic slime inhibitor to the end of supply of the organic slime inhibitor," and in a narrower sense, means "the period during which the supply of the organic slime inhibitor is continuously supplied without being stopped," and this narrower sense is referred to as "the period of constant supply."

[0090] The supply period of the organic slime inhibitor is not particularly limited, and may be the entire operation period of the reverse osmosis membrane device or the entire period of the first step, but in a more specific embodiment, the suitable numerical range per one time (one period) 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 of the organic slime inhibitor to the reverse osmosis membrane device (mg / 1 L of aqueous system (as drug mass concentration)) is not particularly limited, but a suitable numerical range 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 a suitable numerical range is preferably 0.2 to 30,000 mg / (L / h), more preferably 2 to 3,000 mg / (L / h).

[0093] 1-3. Control of the First and Second Steps in the Present Embodiment In the method of the present embodiment, it is preferable to control the first and second steps, thereby enabling the operation of an aqueous system having a reverse osmosis membrane device for a longer period of time. In the method of the present embodiment, a more preferable aspect is to control the first and second addition steps, thereby enabling the water to be treated containing an oxidative slime inhibitor and / or an organic slime inhibitor to be supplied to the reverse osmosis membrane device more efficiently, thereby enabling the aqueous system having a reverse osmosis membrane device to be operated stably for a longer period of time. Furthermore, by controlling the first and second addition steps, it is possible to more effectively reduce the amount of slime present in the reverse osmosis membrane of the reverse osmosis membrane device or suppress the increase of slime, thereby more effectively suppressing biofouling.

[0094] In the method of this embodiment, the first and second steps can be carried out simultaneously or at different times, and it is more preferable to carry them out simultaneously. Also, in the method of this embodiment, the first and second steps may be carried out in parallel or in series, but it is preferable to carry them out in parallel. In a more preferable embodiment of the method of this embodiment, it is more preferable to carry out the first and second steps simultaneously and in parallel. Also, in the method of this embodiment, while the oxidative slime inhibitor of the first step is being added (preferably while it is being added continuously), the organic slime inhibitor of the second step may be added or its addition may be stopped, and further, while the oxidative slime inhibitor of the first step is not being added, it is preferable to continuously add the organic slime inhibitor of the second step.

[0095] In the method of this embodiment, it is more preferable to control the first step and / or the second step based on the operation starting point of the first step and / or the second step, and each operation starting point may be the same or different. The operation starting point is not particularly limited and may be set arbitrarily, but examples include a date (year, month, day, hour, minute, second) and the operation status of the first step and / or the second step (e.g., at the start of operation, at the restart of operation, at the time of adding an agent, an arbitrary period setting, etc.), and one or a combination of two or more selected from these can be used.

[0096] As a more specific preferred embodiment of the operation start point, for example, the start of the first intermittent addition or the start of the first no-addition in the first step may be the operation start point, or the start of the second addition period in the second step may be the operation start point within the second addition period in the second step and the start of the first intermittent addition or the start of the first no-addition in the first step. Furthermore, when both the first step and the second step are in a no-addition period (for example, for maintenance, to adjust the addition timing of both steps, or both are stopped), the start of addition of at least one of the chemicals in the first step or the second step (when addition is resumed) may be the operation start point, or the simultaneous addition of both chemicals in the first step and the second step may be 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 and second addition steps according to an embodiment of the present invention. Example 1 a1: In the first addition step, an oxidative slime inhibitor is intermittently added at equal intervals. Example 1 b1: In the second addition step, an organic slime inhibitor is constantly added. In this case, the organic slime inhibitor is added during at least a period other than the addition period of the first addition step. The horizontal axis represents the operation period (hours), and the vertical axis represents the amount added. Furthermore, 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 set as the starting point of operation. Note that the intermittent addition periods in the first addition step may be the same or different periods, and the intermittent addition amounts may be the same or different amounts. Furthermore, the intervals between the intermittent additions may be the same or different intervals.

[0099] Control Example 1 in this embodiment can produce treated water containing an oxidative slime inhibitor and / or an organic slime inhibitor. Furthermore, Control Example 1 in this embodiment can produce treated water containing an oxidative slime inhibitor and / or an organic slime inhibitor, which is supplied to a reverse osmosis membrane device in the first and second supply steps. In this case, the treated water containing an oxidative slime inhibitor and / or an organic slime inhibitor can be supplied to the reverse osmosis membrane device in a pattern similar to the addition pattern a1 and b1 shown in FIG. 1 . As a more specific example, the treated water containing only an organic slime inhibitor, the treated water containing both an oxidative slime inhibitor and an organic slime inhibitor, and so on are supplied to the reverse osmosis membrane device in this order. This allows for more stable operation of the water system including the reverse osmosis membrane device over a longer period of time. This can better reduce slime present in the reverse osmosis membrane of the reverse osmosis membrane device or better suppress slime increase, thereby better suppressing biofouling.

[0100] FIG. 2 is a schematic diagram illustrating Example 2 of the control of the first and second addition steps according to an embodiment of the present invention. Example 2, a2: In the first addition step, the oxidative slime inhibitor is added intermittently at equal intervals. Example 2, b2: In the second addition step, the organic slime inhibitor is added continuously during the "period other than the addition period of the first addition step." The horizontal axis represents the operation period (hours), and the vertical axis represents the amount added. Furthermore, 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 set as the starting points of operation, respectively. The overlapping portions in the description of FIG. 1 above will be omitted as appropriate. Note that the intermittent addition periods in the first addition step may be the same or different periods, and the intermittent addition amounts may be the same or different amounts. Furthermore, the intervals between the intermittent additions may be the same or different intervals. Furthermore, in the second addition step, the organic slime inhibitor may be added continuously for the entire period or a portion of the "period other than the addition period of the first addition step." Furthermore, in the second addition step, the organic slime inhibitor may be added discontinuously.

[0101] Furthermore, as Control Example 3 of the first addition step and the second addition step according to this embodiment, Control Example 1 and Control Example 2 may be combined, or Control Example 1 and Control Example 2 may be performed repeatedly or in any order. For example, Control Example 1 may be performed followed by Control Example 2, or Control Example 2 may be performed followed by Control Example 1, or Control Example 1, Control Example 2, and Control Example 2 may be performed in that order.

[0102] Control Example 2 in this embodiment can produce treated water containing an oxidative slime inhibitor and / or an organic slime inhibitor. Furthermore, Control Example 2 in this embodiment can produce treated water containing an oxidative slime inhibitor and / or an organic slime inhibitor, which is supplied to a reverse osmosis membrane device in the first and second supply steps. In this case, the treated water containing an oxidative slime inhibitor and / or an organic slime inhibitor can be supplied to the reverse osmosis membrane device in a pattern similar to the addition patterns a2 and b2 shown in FIG. 2 . As a more specific example, the treated water containing only an organic slime inhibitor, followed by the treated water containing only an oxidative slime inhibitor, etc., can be supplied to the reverse osmosis membrane device in this order. This allows for more stable operation of the water system including the reverse osmosis membrane device over a longer period of time. This can better reduce slime present in the reverse osmosis membrane of the reverse osmosis membrane device or suppress slime increase, thereby better suppressing biofouling.

[0103] The locations of addition of the oxidative slime inhibitor and / or organic slime inhibitor may be the same or different (see, for example, Figure 3). The location of addition is preferably the reverse osmosis membrane device that performs reverse osmosis membrane treatment or upstream thereof. Furthermore, when a safety filter device is provided before the reverse osmosis membrane device to perform safety filtration of the water to be treated to be supplied to the reverse osmosis membrane device, the location of addition of the oxidative slime inhibitor and / or organic slime inhibitor is preferably the safety filter device or before or after it. Furthermore, it is preferably provided at the safety filter device or upstream thereof. More specifically, it is more preferably provided in the addition flow path between the safety filter device and the treatment device upstream thereof. The safety filter device can perform the turbidity membrane treatment process described below and may be a turbidity membrane device. The safety filter device can appropriately use a membrane (e.g., MF membrane) that can be used in a turbidity membrane device as a safety filter. This suppresses slime in the safety filter treatment device and also suppresses slime in the downstream reverse osmosis membrane device. Furthermore, biofouling in these membrane devices can be suppressed, further suppressing biofouling in reverse osmosis membrane devices, allowing for stable operation of the water system over a longer period of time.

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

[0105] The operating method of 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, an aqueous system, an apparatus, or a system. The process of this embodiment can be applied to an apparatus or a system. For example, the first process and the second process may be referred to as a first method and a second method, a first apparatus and a second apparatus, or a first system and a second system, respectively. The operating method of this embodiment can be applied to an aqueous system having at least a reverse osmosis membrane device.

[0106] Examples of water systems equipped with reverse osmosis membrane devices include, but are not limited to, water treatment systems; circulating water systems such as cooling towers; process water systems such as those used in paper pulp production; service water systems; and wastewater recovery systems.

[0107] An example of an aqueous system equipped with a reverse osmosis membrane device may include a coagulation treatment step in which raw water flows in and a coagulant is injected into the raw water to coagulate or form flocs of turbidity and the like, a solid-liquid separation step in which the coagulated water to be treated is separated into a precipitate and a 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, arranged in any order. Furthermore, these treatment steps may be performed using a treatment device or a processing unit configured to perform each of the treatment steps.

[0108] An example of an aqueous system equipped with a reverse osmosis membrane device will be described with reference to the aqueous system 1 shown in Figure 3, but the aqueous system according to this embodiment is not limited thereto. The aqueous system 1 includes a raw water inflow and a coagulation process performed by a coagulation treatment device 5 configured to inject a coagulant into the raw water to form coagulation or flocculation of turbidity and the like; a solid-liquid separation process performed by a solid-liquid separator 4 configured to separate the coagulated water into a precipitate and a supernatant; a pretreatment process performed by a safety filter 3 configured to perform a turbidity removal membrane treatment to further remove turbidity and the like from the inflowing supernatant before reverse osmosis membrane treatment; and a reverse osmosis membrane treatment process performed by the reverse osmosis membrane device 2 to which the pretreated water containing an oxidative slime inhibitor and / or an organic slime inhibitor is supplied. The reverse osmosis membrane treatment process separates the concentrated water and the permeated water.

[0109] Another example of a water system equipped with a reverse osmosis membrane device is a water treatment device (preferably an ultrapure water treatment device) that includes a raw water supply channel configured to supply raw water, and a reverse osmosis membrane device configured to separate the raw water supplied from the raw water supply channel into permeate and concentrated water.

[0110] An example of a water system equipped with a reverse osmosis membrane device is a water treatment system including a raw water supply line configured to supply raw water, a filtration device and a filtration treatment tank configured to filter the raw water supplied from the raw water supply line, a safety filter device configured to treat the filtered water as a pretreatment for the reverse osmosis membrane treatment, and the reverse osmosis membrane device. The above-mentioned turbidity removal treatment may be performed in the safety filter device.

[0111] The raw water (e.g., water to be treated) used in this embodiment is not particularly limited, and examples thereof include industrial wastewater containing organic matter, seawater / brine water, fresh water (river water, lake water, etc.), industrial water / city water, etc.

[0112] The pH of the raw water or the 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 temperature of the raw water or the water to be treated is not particularly limited, but is preferably 4 to 50°C, and even more preferably 10 to 40°C. The TOC of the raw water or the 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 the 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 is preferably configured to be able to remove ions, organic matter, and the like from 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 wastewater reuse. Furthermore, the reverse osmosis membrane device may include one or more units having a reverse osmosis membrane. Furthermore, the water system may include one or more reverse osmosis membrane devices.

[0114] <Reverse Osmosis Membrane> The membrane used in this embodiment is a reverse osmosis membrane (hereinafter also referred to as an "RO membrane"), a nanofiltration membrane (hereinafter also referred to as an "NF membrane"), or the like. The RO membrane is not particularly limited, and examples thereof include polyamide-based, polyethersulfone-based, polysulfone-based, polyimide-based, polyethyleneimine-based, polyethylene oxide-based, and cellulose acetate-based membranes. Among these, polyamide-based RO membranes have the advantage of being suitable for use because they have a high rejection rate for 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 set appropriately depending on the processing capacity or purpose of the reverse osmosis membrane device or the reverse osmosis membrane process, but are not particularly limited.

[0116] The water to be treated (feed water) supplied to the reverse osmosis membrane device may be, for example, pH of the feed water, amount of the feed water, temperature of the feed water, pressure of the feed water (MPa), TOC (Total Organic Carbon) of the feed water, or oxidation-reduction potential (ORP) of the feed water. One or more of these conditions may 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." However, this feed water refers to water introduced into the reverse osmosis membrane device and subjected to reverse osmosis membrane treatment, and typically corresponds to the inlet water of the reverse osmosis membrane device.

[0117] 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. The amount of 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 even 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 feed water is preferably 200 to 600 mV, and more preferably 200 to 400 mV. The flow rate of the feed water is 3 to 10 m / s per 8-inch spiral module. ３ / h is preferred.

[0118] In a more preferred embodiment of this embodiment, a pretreatment step may be included in which organic matter and turbidity are removed from the water to be treated in a pretreatment section before the water is supplied to the reverse osmosis membrane device. The water to be treated to be supplied to the reverse osmosis membrane device is preferably pretreated using a safety filter device. For example, a pretreatment step may involve filtering raw water (water to be treated) using a filtration device, and passing the filtered water through a filtration tank and a safety filter. This allows for the production of pretreated water to be supplied to the reverse osmosis membrane device or reverse osmosis membrane process. The safety filter is not particularly limited, but examples include single or multiple microfiltration membrane (MF) membrane treatments and single or multiple ultrafiltration membrane (UF) membrane treatments. One or more of these may be used, or these may be combined as appropriate. This reduces impurities such as turbidity in the water to be treated to be supplied to the reverse osmosis membrane device.

[0119] In this embodiment, the treated water supplied to the reverse osmosis membrane device contains a better amount of oxidative slime inhibitor and / or organic slime inhibitor, which can more effectively suppress biofouling that occurs in the reverse osmosis membrane device, and can also more effectively and efficiently exhibit the effects (e.g., antibacterial, bactericidal, algicidal, microbial growth inhibition, microbial metabolism inhibition, etc.) that are attributable to the oxidative slime inhibitor and / or organic slime inhibitor. This can be expected to have an effect of suppressing biofouling that occurs in the reverse osmosis membrane device, as well as the effects of the chemicals used.

[0120] 1-5. Measurement Methods <Calculation Method of Total Residual Chlorine Concentration> The total residual chlorine concentration is calculated based on the following method. JIS K 0400-33-10:1999 can be referenced. Total residual chlorine concentration = free chlorine concentration + activated combined chlorine concentration + stabilized combined chlorine concentration. Free chlorine concentration: free chlorine concentration measured by the DPD method (pocket residual chlorine meter, manufactured by HACH) [wherein the free chlorine concentration measured by the DPD method is the chlorine concentration measurement result (mg-Cl) after 5 to 30 seconds using a DPD (Free) reagent, which is a reagent for measuring free chlorine] ２ / L)]. Activated combined chlorine concentration: The chlorine concentration measurement result after 300 seconds using a DPD (Free) reagent, which is a reagent for measuring free chlorine (mg-Cl ２ / L), the free chlorine concentration (mg-Cl ２ / L) after 180 seconds. Stabilized combined chlorine concentration: The chlorine concentration measurement result (mg-Cl) after 180 seconds using the DPD (Total) reagent, which is a reagent for measuring total chlorine. ２ / L), the chlorine concentration measurement result (mg-Cl) after 300 seconds using the DPD (Free) reagent, which is a reagent for measuring free chlorine, was calculated. ２ / L) is subtracted. Free chlorine ratio (%) = (free chlorine concentration / total residual chlorine concentration) x 100 Stabilized combined chlorine ratio (%) = (stabilized combined chlorine concentration / total residual chlorine concentration) x 100 The temperature of the test environment is 25°C.

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

[0122] The method for operating a reverse osmosis membrane device according to this embodiment may be a treatment method for a reverse osmosis membrane. The method for operating a reverse osmosis membrane device according to this embodiment may be applied to a device or a system. Regarding the method for operating a reverse osmosis membrane device according to this embodiment, the explanations of the first step, the second step, the oxidative slime inhibitor, the organic slime inhibitor, and other components that overlap with the components in "2." and "3." below will be omitted as appropriate. However, the explanations in "2." and "3." also apply to this embodiment, and the components and the like described therein can be adopted as appropriate.

[0123] 2. Slime Control Method Applied to the Reverse Osmosis Membrane Device According to the Present Embodiment In the slime control method applied to the reverse osmosis membrane device according to the present invention, explanations of the first step, second step, oxidative slime inhibitor, organic slime inhibitor, etc., which overlap with the configurations in "1." above and "3." below, etc., will be omitted as appropriate, but the explanations in "1.", "3.", etc. also apply to the present embodiment, and the configurations, etc. described therein can be adopted as appropriate. Furthermore, the slime control method according to the present embodiment can be applied to an apparatus or system.

[0124] The slime control method to be applied to the reverse osmosis membrane device of this embodiment preferably comprises a first step of intermittently adding an oxidative slime inhibitor and intermittently supplying the treated water containing the oxidative slime inhibitor to the reverse osmosis membrane device, and 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.

[0125] It is preferable to adjust the addition concentration of the oxidative slime inhibitor in one addition period to be higher than the addition concentration of the organic slime inhibitor in one addition period.It is preferable to add the oxidative slime inhibitor at least once during a three-day operating period.It is preferable to add the oxidative slime inhibitor for 10 minutes or more per addition.It is preferable to add the oxidative slime inhibitor to a total chlorine concentration of 0.1 mg / L or more.It is preferable to add the organic slime inhibitor at 0.01 mg / L or more.

[0126] 3. Water Treatment Device According to the Present Embodiment The explanation of the water treatment device according to the present embodiment, such as the first step, the second step, the oxidative slime inhibitor, and the organic slime inhibitor, which overlap with the above-mentioned configurations of "1." and "2.", will be omitted as appropriate, but the explanations of "1." and "2." also apply to this embodiment, and the configurations described therein can be adopted as appropriate. Furthermore, the water treatment device according to this embodiment may be a water treatment device or water system having at least a reverse osmosis membrane device. The water treatment device may be a water treatment water system or a water treatment system.

[0127] The water treatment device according to this embodiment is preferably a water treatment device that implements the method of this embodiment, which includes: a first step of intermittently adding an oxidative slime inhibitor and intermittently supplying the water to be treated containing the oxidative slime inhibitor to a reverse osmosis membrane device; and 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 water to be treated containing the organic slime inhibitor to the reverse osmosis membrane device.The water treatment device according to this embodiment is preferably a water treatment device that implements the method of operating the reverse osmosis membrane device of this embodiment or the slime control method applied to the reverse osmosis membrane device of this embodiment.

[0128] The water treatment device according to this embodiment preferably includes a first chemical addition unit, a second chemical addition unit, and a reverse osmosis membrane unit, and a control unit for controlling these units. It is also preferable that the water treatment device further includes a safety filter unit as a pretreatment unit before 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 safety filter unit and a flow path upstream of the reverse osmosis membrane unit, thereby allowing each chemical to be added to the water to be treated and for the water to be treated containing each chemical to be supplied to the reverse osmosis membrane device. Furthermore, each of these units may be singular or plural, and these units may also be devices.

[0129] An example of an implementation of this embodiment is shown below, but the implementation of this embodiment is not limited to this. In addition, this embodiment may be implemented by a control unit, a water treatment control device, a water treatment device, a water treatment system, a water system, or the like.

[0130] As an example of this embodiment, a control unit configured to perform the first and second steps, or an apparatus equipped with such a control unit, is preferred. This allows the method of this embodiment to be implemented more effectively. The control unit can control and perform the first and second steps by instructing the first and second chemical addition units on the chemical addition conditions (addition timing (e.g., intermittent, continuous), addition amount, etc.) of the oxidative slime inhibitor and organic slime inhibitor to be added to the water to be treated. Furthermore, in the first and second steps, the control unit may monitor the supply status of the chemical-containing water to the reverse osmosis membrane device using various measuring devices, and can feed back the measurement results to the first and second addition steps as necessary to control them.

[0131] In a preferred embodiment, the control unit can control and carry out the first and second steps by instructing the first and second chemical addition units on the most appropriate chemical addition conditions (addition timing (e.g., intermittent, continuous), addition concentration, etc.) based on the supply status. This allows the water system having the reverse osmosis membrane device to operate stably for a longer period of time. Furthermore, this can better reduce slime present in the reverse osmosis membrane of the reverse osmosis membrane device or suppress its increase, thereby better suppressing biofouling.

[0132] In a more preferred embodiment, the control unit preferably executes steps 11 and 21 in parallel at the same time, and even more preferably executes steps 12 and 22 in parallel at the same time. Furthermore, the control unit can prepare water to be treated containing an oxidative slime inhibitor and / or an organic slime inhibitor by adjusting the amounts of the oxidative slime inhibitor and the oxidative slime inhibitor added to the water to be treated, as well as the timing and duration of addition, in the first and second addition steps. In the first and second supply steps, the control unit can supply the water to be treated containing the oxidative slime inhibitor and / or the organic slime inhibitor prepared in the first and second addition steps to the reverse osmosis membrane device. In this way, the control unit can operate the water system including the reverse osmosis membrane device stably for a longer period of time. This can also suppress biofouling and other problems that occur in the reverse osmosis membrane device.

[0133] In step 11 of the first process, the control unit controls the first chemical addition unit to intermittently add an oxidative slime inhibitor to the aqueous water to be treated. In response to instructions from the control unit, the first chemical addition unit intermittently adds the oxidative slime inhibitor to the aqueous water to be treated. In step 12 of the first process, the control unit controls the water to be treated containing the oxidative slime inhibitor to be intermittently supplied to the reverse osmosis membrane device after the addition. In step 21 of the second process, the control unit controls the second chemical addition unit to add the organic slime inhibitor at least during a period other than the addition period of the first process. In response to instructions from the control unit, the second chemical addition unit adds the organic slime inhibitor at least during a period other than the addition period of the first process. In step 22 of the second process, the control unit controls the water to be treated containing the organic slime inhibitor to be supplied 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 of the oxidative slime inhibitor (as total chlorine concentration) so that it is higher than the addition concentration of the organic slime inhibitor (as chemical mass concentration), thereby achieving the desired chemical addition amount. The control unit also preferably instructs the first chemical addition unit to add the oxidative slime inhibitor at least once during the three-day operating period, thereby achieving the desired addition period. The control unit also preferably instructs the first chemical addition unit to add the oxidative slime inhibitor for at least 0.1 minutes per addition, thereby achieving the desired addition period.

[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 a water system having a reverse osmosis membrane device. The control unit can instruct the first chemical addition device 10 to add an oxidative slime inhibitor upstream of the safety filter 3 or the reverse osmosis membrane device 2 in accordance with a first process. The control unit can instruct the second chemical addition device 20 to add an organic slime inhibitor upstream of the safety filter 3 or the reverse osmosis membrane device 2 in accordance with a second process. In this way, the control unit can supply the water to be treated containing an oxidative slime inhibitor and / or an organic slime inhibitor to the reverse osmosis membrane device 2. In this way, the control unit can control and perform the first and second addition processes, thereby enabling the water system having a reverse osmosis membrane device to operate stably over a longer period of time.

[0136] The method of this embodiment can also be realized by a device for implementing or managing the above-mentioned reverse osmosis membrane device operation method, slime control method, and other methods (for example, the methods described in "1." and "2." above) or a control unit (the control unit includes a CPU or processor, etc.) provided in the device, and these devices or control units can be provided. Examples of the device for implementing or managing the method include computers, laptops, desktop computers, tablet PCs, PLCs, servers, cloud services, and the like. Furthermore, the device for implementing or managing the method may be appropriately equipped with an input unit such as a touch panel or keyboard, a communication unit such as a transmission / reception unit between each unit, a network, a network access unit, and a display unit such as a touch panel or display. This allows the method of this embodiment to be implemented. The device for implementing or managing the method may be appropriately equipped with, for example, a CPU, RAM, a memory unit, a display unit, and a communication unit, and these components may be connected, as necessary, by a bus, for example, as a data transmission path.

[0137] The method of this embodiment can also be stored as a program in hardware resources including a storage medium (non-volatile memory (such as a USB memory), a solid state drive (SSD), a hard disk drive (HDD), a CD, a DVD, a Blu-ray, etc.) and implemented 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. This allows the method of this embodiment to be implemented.

[0138] Furthermore, it is possible to provide an apparatus, water treatment device, system, or aqueous system for operating a reverse osmosis membrane device or controlling slime in the reverse osmosis membrane device, which includes the control unit, the storage medium, or the program. This allows the method of this embodiment to be implemented. These apparatus, water treatment device, system, or aqueous system may be configured to respond appropriately to the purpose.

[0139] As an example of this embodiment, a computer program for implementing the operation or slime control of a reverse osmosis membrane device can be provided, including, but not limited to, a first function configured to intermittently add an oxidative slime inhibitor and intermittently supply the treated water containing the oxidative slime inhibitor to the reverse osmosis membrane device, and a second function configured to add an organic slime inhibitor at least during a period other than the addition period of the first step and supply the treated water containing the organic slime inhibitor to the reverse osmosis membrane device. This allows the method of this embodiment to be implemented.

[0140] In the program according to this embodiment, explanations of the first step, second step, oxidative slime inhibitor, organic slime inhibitor, etc., which overlap with the above-mentioned "1." and "2.", will be omitted as appropriate, but the explanations of "1." and "2.", etc. also apply to this embodiment, and the configurations etc. described therein can be adopted as appropriate.

[0141] The present technology can employ the following configurations: - [1] A method for operating a reverse osmosis membrane device, comprising: a first step of intermittently adding an oxidative slime inhibitor and intermittently supplying water to be treated containing the oxidative slime inhibitor to a reverse osmosis membrane device; and 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 water to be treated containing the organic slime inhibitor to the reverse osmosis membrane device. - [2] A slime control method applied to a reverse osmosis membrane device, comprising: a first step of intermittently adding an oxidative slime inhibitor and intermittently supplying water to be treated containing the oxidative slime inhibitor to the reverse osmosis membrane device; and 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 water to be treated containing the organic slime inhibitor to the reverse osmosis membrane device.

[0142] [3] The method according to [1] or [2], wherein the concentration of the oxidative slime inhibitor added is adjusted to be higher than the concentration of the organic slime inhibitor added. [4] The method according to any one of [1] to [3], wherein the oxidative slime inhibitor is added at least once during a three-day operating period. [5] The method according to any one of [1] to [4], wherein the oxidative slime inhibitor is added for at least 10 minutes each time. [6] The method according to any one of [1] to [5], wherein the oxidative slime inhibitor is added to a total chlorine concentration of at least 0.1 mg / L. [7] The method according to any one of [1] to [6], wherein the organic slime inhibitor is added at at least 0.01 mg / L. [8] The method according to any one of [1] to [7], wherein the oxidative slime inhibitor is a bonded halogen agent, preferably one or more selected from chloramine compounds, stabilized bromides, and halogenated hydantoin compounds, more preferably chloramine compounds and / or stabilized bromides. [9] The method according to any one of [1] to [8], wherein the organic slime inhibitor is one or more selected from isothiazolin compounds, halocyanoacetamide compounds, aldehyde compounds, and oxime compounds, 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.

[0143]

[10] A water treatment device or water treatment system that implements the method for operating a reverse osmosis membrane device described in any one of [1] and [3] to [9] above, or the slime control method applicable to a reverse osmosis membrane device described in any one of [2] to [9] above. The water treatment device or water treatment system preferably includes at least a reverse osmosis membrane device and further includes a safety filter device upstream of the reverse osmosis membrane device. It is also preferable to include a safety filter device for pretreating the water before supplying it to the reverse osmosis membrane device, thereby enabling the water to be treated that has been safety filtered to be supplied to the reverse osmosis membrane device.

[11] A water treatment device or water treatment system, or a control unit or controller configured to implement the method described in any one of [1] to [9] above, may be provided. The control unit may include a CPU, and the controller is preferably a computer device. The water treatment device or water treatment system may include the control unit or the controller.

[0144]

[12] An operating system for an osmosis membrane device or a slime control system applied to a reverse osmosis membrane device, causing a computer to implement the method described in any one of [1] to [9] above.

[13] A program causing a computer to implement the method described in any one of [1] to [9] above.

[14] A program for operating a reverse osmosis membrane device, comprising: a first function for executing a first step of intermittently adding an oxidative slime inhibitor and intermittently supplying water to be treated containing the oxidative slime inhibitor to a reverse osmosis membrane device; and a second function for executing 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 water to be treated containing the organic slime inhibitor to a reverse osmosis membrane device, or a computer-readable medium storing the program, or a device including the program or the medium. A control unit, water treatment device, control system, or water treatment system configured to execute the program.

[0145] The following examples and comparative examples will be used to explain the embodiments of the present invention, but the scope of the present invention is not limited to these examples.

[0146] Test Example 1: Substrates were added to raw water to promote microbial biofouling. Specifically, the raw water was treated with the following substrates: ethanol 50 mg / L as C, ammonium chloride 10 mg / L as N, and sodium dihydrogen phosphate 0.5 mg / L as P. The raw water (water to be treated) had a pH of 6-8, a TOC of 1 mg / L, an ORP of 300 mV, and a water temperature of 25°C. This water to be treated was pressurized to 1.5 MPa with a pump and supplied as feed water (water flow rate 100 mL / min, water pressure 0.2 MPa, water temperature 25°C) to the concentrate chamber of an RO membrane device for RO membrane treatment. The RO membrane device used was a vessel packed with a 4-inch spiral-wound RO membrane element (manufactured by Nitto Denko Corporation, ES20) made of aromatic polyamide RO membrane. The flow rate of the supplied water is 3 to 10 m per 8-inch spiral module. ３ The change in differential pressure means the change in the difference between the pressure at the start of measurement, which was set to 0 kPa, and the pressure at each time water was passed after the start of measurement.

[0147] <Method for evaluating slime suppression for reverse osmosis membranes> When evaluating slime suppression for reverse osmosis membranes, a membrane fouling simulator described in Non-Patent Document 1 (J.S. Vrouwenvelder et. al.) was used to measure the number of days it took for the differential pressure to increase by 100 kPa under the conditions shown in Table 1, and the day on which this differential pressure was reached was defined as the day on which biofouling occurred, i.e., the day on which clogging occurred. The longer the number of days until clogging occurred, the better slime suppression was evaluated.

[0148] [Comparative Example 1-1]: No chemicals added. [Comparative Example 1-2]: Sodium monochlorosulfamate was added continuously at a total chlorine concentration (T-Cl) of 1.5 mg / L from day 0 until clogging occurred. Comparative Example 3: Cl-MIT was added continuously at a Cl-MIT concentration of 0.15 mg / L from day 0 until clogging occurred. [Example 1-1]: The first step of <J1-1> and the second step of <J2-2> were carried out in parallel. In <J1-1>, the oxidative slime inhibitor sodium monochlorosulfamate was added to the water to be treated at a concentration of 6 mg / L as T-Cl for two hours every day from 8:00 a.m., starting from day 0, and the water to be treated containing the agent was supplied to an RO membrane device. In <J2-2>, from day 0, the organic slime inhibitor Cl-MIT (5-chloro-2-methyl-4-isothiazolin-3-one) was continuously added at 0.15 mg / L as chemical mass (Cl-MIT), and the water to be treated containing the chemical was supplied to the RO membrane device. In the case of continuous addition, the chemical was added to the water to be treated from day 0 onwards, and the chemical was continuously added to the water to be treated without stopping the addition until clogging occurred, and the water to be treated containing the chemical was supplied to the reverse osmosis membrane. During the period when the addition times of <J1-1> and <J2-2> overlapped, the water to be treated containing these was supplied to the RO membrane device.

[0149] <Preparation of a drug containing sodium monochlorosulfamate> A sodium hydroxide aqueous solution was prepared using pure water so that sodium hydroxide (manufactured by Kishida Chemical Co., Ltd.) was 48% by mass. 19.5 g of this previously prepared sodium hydroxide aqueous solution was mixed with 7.5 g of pure water, and then 15.0 g of amidosulfuric acid (sulfamic acid) (manufactured by Kishida Chemical Co., Ltd.) was added and mixed. 58.0 g of sodium hypochlorite (manufactured by Asahi Glass Co., Ltd.) with an effective chlorine concentration of 12% by mass was then added and mixed to prepare a monochlorosulfamic acid reagent. The total chlorine concentration of this drug was 7% by mass as Cl ２ is.

[0150]

[0151] The following was confirmed from these water flow results shown in Table 1. It was confirmed that it is better to add different types of slime inhibitors alternately every few days than to add a single slime inhibitor all the time. It was confirmed that by performing the first addition process, in which an oxidative slime inhibitor is intermittently added for two hours once a day, and the second addition process, in which an organic slime inhibitor is constantly added, in parallel, the number of days of blockage was extended and the slime inhibition effect was better.

[0152] <Test Example 2> A test was conducted under the same conditions as in <Test Example 1> above, except that the raw water was treated with added IPA as substrates to give 1.4 mg / L as C and sodium dihydrogen phosphate as substrates to give 0.02 mg / L as P, the temperature of the water to be treated was adjusted to 30°C, and the following conditions were used for the addition of the disinfectant:

[0153] Comparative Example 2-1: The organic slime inhibitor Cl-MIT was continuously added at 0.1 mg / L as the agent mass (Cl-MIT) and the water was continuously passed through an RO membrane device. As a result, the water to be treated containing the agent was continuously passed through the downstream RO membrane device.

[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 oxidative slime inhibitor in the first step was continuously added for a "certain period of time." This was repeated in this order. As a result, the oxidative slime inhibitor was added intermittently, and the water to be treated containing the oxidative slime inhibitor was continuously passed through the reverse osmosis membrane device for a "certain period of time." On the other hand, the organic slime inhibitor was continuously added during a "period other than the addition period of the first step," and the water to be treated containing the organic slime inhibitor was continuously passed through the reverse osmosis membrane device during a "period other than the addition period of the first step."

[0155] Specifically, the organic slime inhibitor Cl-MIT used in the second step was added at 0.1 mg / L as chemical mass (Cl-MIT) for a period of 23.5 hours from 9:30 every day to 9:00 the next day, and the water was continuously passed through the downstream RO membrane device for this predetermined period, and (2) the oxidative slime inhibitor monochlorosulfamic acid used in the first step was 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 water was continuously passed through the downstream RO membrane device for this predetermined period. As a result, the treated water containing the organic slime inhibitor, the treated water containing the oxidative slime inhibitor, the treated water containing the organic slime inhibitor, etc. are supplied to the reverse osmosis membrane device in this order.

[0156] The results of the change in differential pressure (kPa) up to 6 days in Example 2-1 and Comparative Example 2-1 are shown in Figure 4. The increase in differential pressure was clearly slower in Example 2-1, so the results suggest that the method of Example 2-1 has an excellent slime suppression function. Furthermore, in Example 2-1, both the organic slime inhibitor and the oxidative slime inhibitor were used at low concentrations, but the change in differential pressure was 10 KPa or less even after 6 days, so very good slime suppression was obtained. This confirmed the effectiveness of being able to exhibit good slime suppression function even at low concentrations of both the organic slime inhibitor and the oxidative slime inhibitor.

[0157] Test Example 3 A test was conducted under the same conditions as Test Example 1 above, except that the raw water used was treated with added substrates of ethanol 50 mg / L as C, ammonium chloride 20 mg / L as N, and sodium dihydrogen phosphate 1.0 mg / L as P, and the following conditions were used for the disinfectant addition.

[0158] Comparative Example 3-1: The organic slime inhibitor Cl-MIT was continuously added at 0.5 mg / L as the agent mass (Cl-MIT) and the water was continuously passed through the RO membrane device. As a result, the water to be treated containing the agent was continuously passed through the downstream RO membrane device.

[0159] Example 3-1: The organic slime inhibitor in the second step was continuously added "at regular intervals" and the oxidative slime inhibitor in the first step was continuously added "for a fixed period of time." This was done in parallel. The oxidative slime inhibitor was added intermittently, and the water to be treated containing the oxidative slime inhibitor was continuously passed through the reverse osmosis membrane device for a fixed period of time. On the other hand, the organic slime inhibitor was continuously added "at regular intervals" at least during the "period other than the addition period of the first step," and the water to be treated containing the organic slime inhibitor was continuously passed through the reverse osmosis membrane device for a fixed period of time. This meant that the water to be treated containing the organic slime inhibitor, the water to be treated containing both the oxidative slime inhibitor and the organic slime inhibitor, and the water to be treated containing the organic slime inhibitor were supplied to the reverse osmosis membrane device in this order.

[0160] Specifically, the organic slime inhibitor Cl-MIT used in the second step is continuously passed through the water at 0.5 mg / L as chemical mass (Cl-MIT), and the water to be treated containing this agent is continuously passed through the downstream RO membrane device. In the first step, the oxidative slime inhibitor monochlorosulfamic acid is continuously added at 25 mg / L as T-Cl for one hour from 9:00 to 10:00 every other day, and the water to be treated containing this agent is continuously passed through the downstream RO membrane device for a predetermined period of time.

[0161] The results up to the 19th day for Example 3-1 and Comparative Example 3-1 are shown in Figure 5. The increase in differential pressure was clearly slower in Example 3-1, so the results suggest that the method of Example 3-1 has an excellent slime suppression function. Furthermore, in Example 3-1, the oxidative slime inhibitor was used at a high concentration, but the change in differential pressure was 10 KPa or less even after 16 days, so very good slime suppression was obtained, and it was confirmed that the slime suppression function can be effectively demonstrated.

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

[0163] In the "Intermittent addition (9:00-9:30 every day)" in Table 2, the oxidative slime inhibitor was added continuously between 9:00-9:30 every day, and was not added between 9:30 and 9:00 the next day. The oxidative slime inhibitor was added continuously for "30 minutes," and the water to be treated containing the agent was passed continuously through the downstream RO membrane device for "30 minutes."

[0164] In the "Intermittent addition (21:00-21:30 every day)" in Table 2, the organic slime inhibitor was added continuously between 21:00 and 21:30 every day, but was not added during the other periods between 21:30 and 21:00 the next day. The organic slime inhibitor was added continuously for "30 minutes," and the water to be treated containing the agent was continuously passed through the downstream RO membrane device for "30 minutes."

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

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

[0167] Table 2 below 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 results suggest that the treatment in which the first addition step, in which an oxidative slime inhibitor is intermittently added, and the second addition step, in which an organic slime inhibitor is constantly added, were performed in parallel resulted in the longest number of days to blockage and had the best slime inhibition effect.

[0168]

[0169] 1 Water system; 2 Reverse osmosis membrane device; 3 Safety filter; 4 Solid-liquid separation device; 5 Condenser; 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; 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 treated water containing the organic-based slime inhibitor to the reverse osmosis membrane device. A method for operating a reverse osmosis membrane device.

2. The method for operating a reverse osmosis membrane device according to claim 1, 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.

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

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

5. The method for operating a reverse osmosis membrane device according to any one of claims 1 to 4, wherein the oxidation-based slime inhibitor is added at a total chlorine concentration of 0.1 mg / L or more.

6. The method for operating a reverse osmosis membrane device according to any one of claims 1 to 5, wherein the organic-based slime inhibitor is added at 0.01 mg / L or more.

7. 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; 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 treated water containing the organic-based slime inhibitor to the reverse osmosis membrane device. A slime control method applied to a reverse osmosis membrane device.

8. A water treatment device that implements the method for operating a reverse osmosis membrane device according to any one of claims 1 to 6, or the slime control method applied to the reverse osmosis membrane device according to claim 7.

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