System and method for membrane treatment of water to be treated

Abstract

An object of the present invention is to provide a system and method for performing membrane treatment of water to be treated simply, with a low load, and continuously, without adding special chemicals. [Solution] The above-mentioned object can be achieved by a membrane treatment system for water to be treated, which includes an electrolysis tank, a membrane separation means, and a control means, wherein the electrolysis tank is capable of subjecting the water to be treated stored therein to electrolysis treatment, the membrane separation means is capable of subjecting the water to be treated that has been subjected to the electrolysis treatment to membrane separation treatment to produce treated water as permeate, and the control means controls the electrolysis treatment so that organic matter adhering to the membrane separation means can be decomposed by the water to be treated that has been subjected to the electrolysis treatment.

Description

[Technical Field]

[0001] The present invention relates to a system and method used for membrane treatment of water to be treated. [Background technology]

[0002] In the process of treating wastewater and other water to be treated and regenerating it into purified water, membrane separation using a membrane such as a reverse osmosis (RO) membrane is carried out to efficiently remove organic matter such as organic components of various molecular weights and microorganisms, in addition to insoluble components such as garbage and inorganic substances such as colored components.

[0003] However, many organic components are viscous and can penetrate into membrane pores, clogging and blocking them. Furthermore, when microorganisms adhere to the membrane, they grow on the membrane surface, forming a microbial layer that blocks the membrane pores. To prevent membrane contamination by these organic substances, a method is used in which chemicals are added to the water being treated to decompose the organic matter in the water.

[0004] Examples of chemicals used include combined chlorine-based oxidants such as chloramine and sodium chlorosulfamate, combined bromine-based oxidants, and isothiazolone compounds (see, for example, Patent Document 1). Various methods have been attempted to control the amount of chemicals added to the water being treated that is supplied to the RO membrane. For example, there is a method of controlling the amount of chemicals added based on the rate of change in the difference between the pressure of the water being treated flowing into the RO membrane device and the pressure of the concentrated water flowing out of the RO membrane device (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-224543 [Patent Document 2] Patent No. 7509039 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when using the chemical described in Patent Document 1, residual chemicals in the purified water become a problem. To solve this problem, the amount of chemicals injected must be controlled, but the method described in Patent Document 2 requires measuring the differential pressure and monitoring the rate of change in the differential pressure, which is complicated and requires a large burden.

[0007] Therefore, the problem that the present invention aims to solve is to provide a system and method for membrane treatment of water to be treated simply, with low load, and continuously, without adding special chemicals such as chloramine, sodium chlorosulfamate, or isothiazolone compounds. [Means for solving the problem]

[0008] The present inventors conducted extensive research to solve the above problems and came to the conclusion that if the water to be treated were subjected to electrolysis, it might be possible to generate a component that functions as an oxidant depending on the content of the components contained in the water to be treated. As a result of repeated trial and error, the present inventors found that by providing electrolysis before membrane separation and subjecting the water to the electrolysis to electrolysis and providing the electrolyzed water to membrane separation means, it was possible to decompose organic matter adhering to the membrane separation means.

[0009] Based on this idea, the inventor finally succeeded in creating a system and method for membrane treatment of water to be treated, which comprises an electrolysis tank, a membrane separation means, and a control means, in order to solve the problems of the present invention. The present invention was completed based on the idea and successful example first conceived by the inventor.

[0010] That is, according to each aspect of the present invention, the following embodiments are provided. [1] A membrane treatment system for water to be treated, The apparatus comprises an electrolysis tank, a membrane separation means, and a control means, The electrolysis tank is capable of subjecting the water to be treated stored therein to electrolysis treatment, The membrane separation means is capable of subjecting the water to be treated, which has been subjected to the electrolysis treatment, to membrane separation treatment to produce treated water as permeate; and the control means controls the electrolysis treatment so that the water to be treated that has been subjected to the electrolysis treatment can decompose organic matter adhering to the membrane separation means. The system. [2] The system according to item [1], wherein the membrane separation means is at least one water treatment membrane selected from the group consisting of a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, a nanofiltration (NF) membrane, and a reverse osmosis (RO) membrane. [3] The water to be treated contains halogen ions, and The system according to item [1], wherein the electrolysis tank is capable of generating a halogen oxygen acid by subjecting the stored water to electrolysis treatment. [4] The system according to any one of items [1] to [3], wherein the system is an autonomous circulation type water treatment system. [5] A membrane treatment method for water to be treated, comprising: A step of subjecting the water to be treated to electrolysis treatment; a step of subjecting the water to be treated that has been subjected to the electrolysis treatment to membrane separation treatment using a membrane separation means to produce treated water as permeate; Including, The water to be treated that has been subjected to the electrolysis treatment is used to decompose organic matter adhering to the membrane separation means. The method. [6] A method for suppressing clogging of a membrane separation means by organic matter, comprising: A step of subjecting the water to be treated to electrolysis treatment; decomposing organic matter adhering to the membrane separation means by the water to be treated that has been subjected to the electrolysis treatment; The method comprising: [7] The water to be treated contains halogen ions, and The method according to item [5] or [6], wherein the electrolysis treatment generates a halogen oxygen acid. [Effects of the Invention]

[0011] According to the present invention, purified water can be obtained as permeate by simple, low-load, and sustained membrane treatment of water to be treated. Furthermore, according to the present invention, clogging of the membrane separation means for membrane treatment can be suppressed without using special chemicals such as chloramine, sodium chlorosulfamate, or isothiazolone compounds. As a result, purified water that does not contain these chemicals and has reduced health impacts on the user's body can be produced. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a layout diagram of a membrane treatment system 1 for water to be treated. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the control means 5. [Figure 3] FIG. 3 is a flowchart of a membrane treatment method using the membrane treatment system for water to be treated. [Figure 4] FIG. 4 is a layout diagram of the membrane treatment system 10 for water to be treated. [Figure 5] FIG. 5 is a layout diagram of a wastewater treatment system 100 incorporating the membrane treatment system 10 for water to be treated. DETAILED DESCRIPTION OF THE INVENTION

[0013] Each aspect of the present invention will be described in detail below, but the present invention can take various forms as long as it achieves its object.

[0014] Unless otherwise specified, each term in this specification is used in the sense commonly used by those skilled in the art of water treatment and the like, and should not be construed as having an unduly limiting meaning. Furthermore, the speculations and theories made in this specification are based on the inventors' knowledge and experience to date, and therefore the present invention is not limited solely to such speculations and theories.

[0015] "Comprise," "contain," and "include" mean that elements other than those explicitly stated as included may be added (same meaning as "comprise at least"), but also encompass "consist of" and "essentially consist of." That is, "comprise" can mean including the explicitly stated elements and any one or more elements, consisting of the explicitly stated elements, or essentially consisting of the explicitly stated elements. "Have" is synonymous with "include." Elements include parts, means, ingredients, steps, conditions, parameters, and other limitations. "And / or" means any one or any or all combinations of two or more of the associated listed items. Throughout this specification, the plural is intended to be included unless the singular is clearly indicated by the context. As used herein, the phrase "based on" does not mean "based only on," unless expressly specified otherwise. In other words, the phrase "based on" encompasses both "based only on" and "based at least on."

[0016] One aspect of the present invention is a membrane treatment system for water to be treated. The membrane treatment system of one aspect of the present invention includes an electrolysis tank, a membrane separation means, and a control means. The electrolysis tank is capable of subjecting the stored water to electrolysis treatment. The membrane separation means is capable of subjecting the water to be treated that has been subjected to electrolysis treatment to membrane separation treatment to produce treated water as permeate. The control means controls the electrolysis treatment so that organic matter adhering to the membrane separation means can be decomposed by the water to be treated that has been subjected to electrolysis treatment.

[0017] Another aspect of the present invention is a membrane treatment method for water to be treated. The membrane treatment method of one aspect of the present invention includes a step of subjecting the water to be treated to electrolysis treatment, and a step of subjecting the water to membrane separation treatment using a membrane separation means to produce treated water as permeate, and organic matter adhering to the membrane separation means is decomposed by the water to be treated after being subjected to the electrolysis treatment.

[0018] Another aspect of the present invention is a method for suppressing clogging of a membrane separation means by organic matter. The method for suppressing clogging of a membrane separation means according to one aspect of the present invention includes the steps of subjecting water to electrolysis treatment and decomposing organic matter adhering to the membrane separation means by the water to be treated that has been subjected to the electrolysis treatment.

[0019] Below, each aspect of the present invention and its embodiments will be described with reference to the drawings. In each drawing, parts that are less relevant to the present invention are omitted. In the drawings, solid arrows (→) indicate the direction of water flow, and dotted arrows (- - →) indicate the direction of input and output.

[0020] 1 is a layout diagram of a membrane treatment system 1 for water to be treated, which is an embodiment of a membrane treatment system according to one aspect of the present invention. The membrane treatment system 1 for water to be treated comprises an electrolysis tank 2, a membrane separation means 3, and a control means 5. The water to be treated WW is contained in the electrolysis tank 2 and subjected to electrolysis treatment, and then sent from the electrolysis tank 2 to the membrane separation means 3 as electrolyzed water EW. The electrolyzed water EW is then separated by the membrane separation means 3 into permeate water PW and concentrate water CW, with the permeate water PW being used as treated water and the concentrate water CW being returned to the electrolysis tank 2 or discharged outside the system.

[0021] The electrolytic tank 2 is equipped with a pair of electrodes 6 consisting of an anode and a cathode, and is capable of subjecting the stored water to be treated WW to electrolysis treatment. The electrodes 6 are energized by a power source such as a DC power source based on an input signal from the control means 5, and electrolyze the water to be treated WW stored in the electrolytic tank 2.

[0022] When the water to be treated contains halides, halogen oxyacids are generated from the halogen ions. The halogen oxyacids function as oxidizing agents that have decomposition activity against organic matter, including microorganisms. Examples of halogen oxyacids include hypohalous acids, halogenous acids, hydrohalic acids, and perhalogen acids. Specific examples include hypochlorous acid, chlorous acid, hypobromite, hydrochloric acid, perchloric acid, and monobasic fluorine-containing oxyacids. However, hypochlorous acid is preferred because of its high decomposition activity against organic matter, including microorganisms. When chloride ions (Cl) are added to the water to be treated, - ), hypochlorous acid (HClO) is produced by electrolysis of the water to be treated WW.

[0023] The electrode 6 may be appropriately selected depending on the type of oxidant to be generated, but is preferably an electrode that generates a halogen oxyacid from a halide in the water to be treated when current is applied. To increase the efficiency of generating a halogen oxyacid, the electrode 6 is preferably titanium or the like coated with a catalyst such as iridium, ruthenium, platinum, or tantalum, or an alloy thereof. A specific example of the electrode 6 is a titanium electrode coated with iridium and ruthenium.

[0024] The membrane separation means 3 may be any membrane having a size exclusion mechanism that does not allow substances with a specific diameter or larger to pass through, such as a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, a nanofiltration (NF) membrane, a reverse osmosis (RO) membrane, etc. The membrane separation means 3 may be any one of these membranes alone or a combination of two or more of them.

[0025] If the water to be treated WW contains organic matter such as viscous organic components or microorganisms, the membrane pores of the membrane separation means 3 will become clogged, significantly reducing the efficiency of the membrane separation process. However, in the present invention, the water to be treated is subjected to electrolysis to obtain electrolyzed water, which is then supplied to the membrane separation means 3. The organic matter is decomposed by the oxidizing agents, such as halogen oxygen acids, contained in the electrolyzed water, thereby preventing clogging of the membrane pores of the membrane separation means 3. As a result, the water to be treated WW can be efficiently subjected to membrane separation, and treated water can be stably obtained as permeate PW.

[0026] The control means 5 controls the electrolysis process in the electrolysis tank 2 so that the organic matter adhering to the membrane separation means 3 can be decomposed by the electrolyzed water. The control means 5 controls the electrolysis process by appropriately setting parameters such as the voltage applied to the electrode 6, the current value flowing through the electrode 6, and the time for which current is passed through the electrode 6. For example, as shown in Fig. 2(a) in Huang et al.'s (Xiao Huang et al., Water Research, Volume 92, April 1, 2016, Pages 164-172), the amount of oxidant generated tends to increase as the voltage applied to the electrode 6 increases and the time for which current is passed through the electrode 6 increases. Therefore, to increase the amount of oxidant generated, the electrolysis process is controlled so that the voltage applied to the electrode 6 is increased, the current value flowing through the electrode 6 is increased, and / or the time for which current is passed through the electrode 6 is extended. On the other hand, to decrease the amount of oxidant generated, the electrolysis process is controlled so that the voltage applied to the electrode 6 is decreased, the current value flowing through the electrode 6 is decreased, and / or the time for which current is passed through the electrode 6 is shortened.

[0027] Furthermore, it is preferable to set the conditions for the electrolysis treatment taking into account the type (e.g., microbial species, etc.) and concentration of organic matter in the water to be treated WW. For example, when the organic matter concentration in the water to be treated WW is high, it is preferable to control the electrolysis treatment so that the amount of oxidant produced is large, and when the organic matter concentration in the water to be treated WW is low, it is preferable to control the electrolysis treatment so that the amount of oxidant produced is not excessive. Note that, as shown in Figure 3(a) in the Huang et al. publication, the kill rate (Log Reduction) varies depending on the microbial species, and when most of the organic matter in the water to be treated WW is bacteria, the electrolysis treatment time can be set to a relatively short time.

[0028] If the amount of oxidizing agent contained in the electrolyzed water EW is large, depending on the type, it may damage the membrane separation means 3, causing the membrane to deteriorate, which is undesirable. Therefore, it is preferable that the control means 5 controls the electrolysis process so that the oxidizing agent is present in the electrolyzed water EW to an extent that clogging of the membrane pores by the membrane separation means 3 is not observed. For this reason, the control means 5 may control the electrolysis process using the degree of clogging of the membrane pores in the membrane separation means 3 as a parameter (for example, transmembrane pressure difference).

[0029] The control means 5 preferably has a processing section that functions to control the electrolysis treatment so that the water to be treated WW subjected to the electrolysis treatment can decompose organic matter adhering to the membrane separation means 3. As a specific embodiment of the control means 5 having a processing section, a block diagram showing the functional configuration of the control means 5 is illustrated in FIG.

[0030] 2, the control means 5 includes a processing unit 51, a memory unit 52, and an input / output unit 53. The control means 5 may further include a display unit. The display unit displays the conditions of the electrolysis treatment, parameters indicating the degree of membrane pore clogging in the membrane separation means 3, and the like. Each component is connected to each other via a bus 54 so as to be able to communicate with each other.

[0031] The processing unit 51 is configured to be able to issue commands as output values ​​to the electrodes 6 (power sources connected to the electrodes 6). Furthermore, when the membrane separation means 3 is capable of outputting a signal, the processing unit 51 can acquire a signal from the membrane separation means 3 as an input value. The processing unit 51 sets the conditions for the electrolysis treatment by using a setting value 521 in which the conditions for the electrolysis treatment are set in advance, or by using a setting program 523.

[0032] The memory unit 52 is composed of a storage device and stores setting values ​​521, setting program 523, etc. The memory unit 52 may store signals from the membrane separation means 3 if the membrane separation means 3 is equipped with a pressure detection device or the like, a setting log of the electrolysis treatment conditions from the processing unit 51, etc. The setting program 523 functions to cause the processing unit 51 to set the conditions of the electrolysis treatment based on the signals from the membrane separation means 3 and the setting values ​​521. For example, if the pressure (transmembrane pressure difference) detected by the membrane separation means 3 is high, it is possible that the membrane pores are clogged with organic matter, and therefore the conditions of the electrolysis treatment are set so that the amount of oxidant produced is large. On the other hand, if the pressure detected by the membrane separation means 3 is low, it is possible that there is little organic matter on the membrane surface, and therefore the conditions of the electrolysis treatment are set so that the amount of oxidant produced is small.

[0033] The input / output unit 53 is configured to be able to transmit a command to control the electrodes 6 in accordance with the conditions of the electrolysis process based on the setting result of the processing unit 51. Optionally, the input / output unit 53 is configured to be able to transmit a signal from the membrane separation means 3 to the processing unit 51.

[0034] Examples of the control means 5 include a control circuit, a microcontroller, a single-board computer, a personal computer (notebook PC, desktop PC), a tablet terminal, and a smartphone.

[0035] Each device connected to the control means 5 via the input / output unit 53 may be connected independently by wire, or may be connected wirelessly with or without a router etc. When the control means 5 controls the electrolysis treatment based on a signal from the membrane separation means 3, the control means 5 may control the electrolysis treatment in real time or with a delay.

[0036] The control of the electrolysis process by the control means 5 may be controlled using AI (Artificial Intelligence) or the like based on signals from the membrane separation means 3. Non-limiting specific examples of control of the electrolysis process using a machine learning model that utilizes AI are described below. Note that algorithms used for learning and inference include, but are not limited to, unsupervised learning models such as k-means clustering and lazy learning algorithms such as k-nearest neighbors.

[0037] Control of the electrolysis process using a machine learning model is divided into a learning phase and an inference phase. In the learning phase, model learning is performed. Model learning is performed using integrated data based on the pressure of the membrane separation means 3, the current value (current density), the treatment time, and the organic matter removal rate stored in a database in the memory of a PC or the like as input data. The integrated data may include preset data and standard data that correct or complement the above data. Examples of such data include past pressure of the membrane separation means 3 and electrolysis treatment condition setting data, arbitrary preset data, and past electrolysis treatment result data. In model learning, the parameter values ​​that make up the model are adjusted so that the learning result data output is appropriate for the input data. The learning result data is data resulting from learning the electrolysis treatment conditions.

[0038] In the inference phase, integrated data including input data based on the pressure value of the membrane separation means 3 just obtained and learning result data are input to the trained model, i.e., the updated model, and inference processing is performed to obtain inference result data. The inference result data is data on the inference results of the electrolysis processing conditions. The inference processing can be performed using the above-mentioned algorithm, etc.

[0039] By using the membrane treatment system 1 for water to be treated, the water to be treated can be efficiently treated by membrane treatment while suppressing clogging of the membrane pores in the membrane separation means 3. Furthermore, by inputting the pressure of the membrane separation means 3 as a set value, it is possible to control the conditions for the electrolysis treatment so that the pressure is achieved.

[0040] The water to be treated WW may be any water capable of generating an oxidant through electrolysis, including, for example, domestic wastewater discharged from drainage facilities such as washrooms, toilets, kitchens, bathrooms, and laundry rooms, urban wastewater, commercial wastewater, agricultural wastewater, and industrial wastewater, as well as sewage, rainwater, surface water, seawater, and clean water, as well as treated water obtained by chemical, biological, or filtration treatments. The water to be treated WW preferably contains a halide so that a halogen oxygen acid can be generated through electrolysis. If the water to be treated WW does not contain a halide, or if it contains only a small amount of a halide, a halide (e.g., NaCl) may be added to the water to be treated WW. Furthermore, organic matter in the water to be treated WW can also be decomposed through electrolysis of the water to be treated WW.

[0041] Electrolyzed water EW is water containing an oxidant obtained by subjecting the water to be treated WW to electrolysis treatment, and it is preferable that it be subjected to optimal electrolysis treatment based on the water quality information of the water to be treated WW (pH, EC value, turbidity, BOD, COD, TOC, SS, total nitrogen, total phosphorus, etc.).

[0042] An example of a membrane treatment method for water to be treated using the membrane treatment system 1 will be described with reference to the flowchart shown in FIG.

[0043] As illustrated in Figure 3, the control means 5 sets conditions for the electrolysis treatment of the water to be treated WW in the electrolysis tank 2 (S101). Next, the water to be treated WW is electrolyzed in the electrolysis tank 2 under the set conditions for the electrolysis treatment (S102). The electrolyzed water to be treated WW is fed from the electrolysis tank 2 to the membrane separation means 3 (S103). The water to be treated WW fed at this time may be electrolyzed water EW that has already been electrolyzed, or may be water to be treated WW that is currently being electrolyzed.

[0044] Next, the water WW to be treated is subjected to membrane separation treatment in the membrane separation means 3 (S104). If clogging of the membrane separation means 3 is detected by detecting the pressure or the like during the execution of the membrane separation treatment, the water supply from the electrolysis tank 2 to the membrane separation means 3 is stopped, and the water WW to be treated that has been supplied to the membrane separation means 3 is returned to the electrolysis tank 2, or the electrolysis treatment conditions are set so that a larger amount of oxidant is produced in the electrolysis tank 2 without returning it, and the electrolysis treatment is restarted.

[0045] If no clogging is found in the membrane separation means 3, membrane treatment using the membrane separation means 3 is continued. The permeate water PW obtained as a result of the membrane treatment is discharged outside the system as treated water (S106). On the other hand, the concentrated water CW that did not permeate the membrane pores is returned to the electrolysis tank 2 or the like and is subjected to electrolysis treatment again.

[0046] Fig. 4 is a layout diagram of a membrane treatment system 10 for water to be treated according to another embodiment of the present invention. In the membrane treatment system 10 for water to be treated, an intermediate tank 7 is provided between the electrolysis tank 2 and the membrane separation means 3. Electrolyzed water EW from the electrolysis tank 2 is stored in the intermediate tank 7 and then sent to the membrane separation means 3. As shown in Fig. 4, concentrated water CW obtained by subjecting the electrolyzed water EW to the membrane separation means 3 may be sent to the electrolysis tank 2, the intermediate tank 7, or outside the system.

[0047] A membrane treatment system for water to be treated according to one embodiment of the present invention can be incorporated, for example, into a part of a wastewater treatment system. FIG. 5 is a layout diagram of a wastewater treatment system 100 incorporating a membrane treatment system 10 for water to be treated. The wastewater treatment system 100 sends wastewater via a wastewater tank to a treatment tank (such as a chemical treatment tank or a biological treatment tank) for wastewater treatment. The primary treated water treated in the treatment tank is then sent via a separation membrane to the membrane treatment system 10 for water to be treated. Electrolyzed water obtained by subjecting the water to electrolysis treatment in the membrane treatment system 10 for water to be treated is sent via an intermediate tank to a membrane separation means. The permeate from the membrane separation means is stored in a treated water layer and used as purified water. Alternatively, as shown in FIG. 5, concentrated water may be sent to the treatment tank.

[0048] A wastewater treatment system may be any system that treats wastewater flowing in from outside the system and then supplies the resulting treated water as purified water to the outside. The wastewater treatment system may be a building wastewater treatment system installed in a residence, small commercial facility, factory plant, temporary facility, etc., or a portable wastewater treatment system that is movable. Among wastewater treatment systems, a system that is connected to a building's drainage system, treats the wastewater flowing in from the drainage system, and returns the resulting treated water as purified water to the drainage system is called an autonomous circulation type wastewater treatment system. If the building is a residence such as a house, it is called an autonomous circulation type residential wastewater treatment system.

[0049] The present invention is not limited to any of the above-described embodiments, and can be embodied by modifying the components within the scope of the gist of the present invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above embodiments. For example, some of the components shown in the embodiments may be modified, such as by addition, deletion, or substitution. Furthermore, the components and forms of different embodiments may be appropriately combined. [Industrial Applicability]

[0050] The membrane treatment system, membrane treatment method, and clogging suppression method of one aspect of the present invention can be used to suppress clogging of a membrane separation means for membrane treatment, continuously perform membrane treatment on water to be treated, and obtain purified water as permeate. These systems and methods can be used to supply water users with safe and reliable water. [Explanation of symbols]

[0051] 1, 10 Membrane treatment system for treated water 2. Electrolysis tank 3 Membrane separation means 5. Control measures 51 Processing section 52 Storage section 521 setting value 523 Configuration Program 53 Input / output section 54 Bus 6 electrodes 7 Intermediate tank

Claims

1. A membrane treatment system for water to be treated, The apparatus comprises an electrolysis tank, a membrane separation means, and a control means, The electrolysis tank is capable of subjecting the water to be treated stored therein to electrolysis treatment, The membrane separation means can subject the water to be treated, which has been subjected to the electrolysis treatment, to membrane separation treatment to produce treated water as permeate, The control means controls the electrolysis treatment so that organic matter adhering to the membrane separation means can be decomposed by the water to be treated that has been subjected to the electrolysis treatment; and The membrane separation means exists independently of the electrolysis tank and is disposed downstream of the electrolysis tank. The system.

2. 2. The system according to claim 1, wherein the membrane separation means is at least one water treatment membrane selected from the group consisting of a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, a nanofiltration (NF) membrane, and a reverse osmosis (RO) membrane.

3. The water to be treated contains halogen ions, and The system according to claim 1 , wherein the electrolysis tank is capable of generating a halogen oxygen acid by subjecting the water to be treated stored therein to electrolysis treatment.

4. The system according to any one of claims 1 to 3, wherein the system is an autonomous circulation type water treatment system.

5. A membrane treatment method for water to be treated, comprising: subjecting the water to be treated to electrolysis treatment in an electrolysis tank; a step of subjecting the water to be treated that has been subjected to the electrolysis treatment to membrane separation treatment using a membrane separation means to produce treated water as permeate; Including, Decomposing organic matter adhering to the membrane separation means by the water to be treated after being subjected to the electrolysis treatment; and The membrane separation means exists independently of the electrolysis tank and is disposed downstream of the electrolysis tank. The method.

6. The water to be treated contains halogen ions, and The method of claim 5 , wherein the electrolysis process produces a halogen oxygen acid.

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