System and method for electrolyzing water to be treated

Abstract

The object of the present invention is to provide a system and method for electrolyzing water to be treated that can achieve a predetermined pathogen killing efficiency while suppressing the generation of by-products. [Solution] The above objective is achieved by an electrolysis system for treated water, which includes an electrolysis tank, conductivity measuring means, pH measuring means, and control means, wherein the control means sets the conditions for the electrolysis treatment based on the conductivity of the treated water before the electrolysis treatment and controls the electrolysis treatment by modifying the conditions based on the pH of the treated water after the electrolysis treatment.

Description

Technical Field

[0001] The present invention relates to a system and method used for electrolyzing treated water.

Background Art

[0002] In the process of subjecting treated water such as wastewater to water treatment for regeneration into purified water, a sterilization treatment for killing pathogens such as bacteria, viruses, and protozoa is performed. For example, by using an oxidizing agent, the cell membrane of the pathogen can be destroyed to kill the pathogen.

[0003] As a sterilization method using an oxidizing agent, in addition to the addition method of adding an oxidizing agent to the treated water, an electrolysis method is available in which halogen ions contained in the treated water are utilized and the treated water is sterilized with an oxidizing agent generated by subjecting the treated water to an electrolysis treatment. For example, when chloride is present in the treated water, hypochlorous acid (HClO) is generated from chloride ions according to the following reaction formula. 2Cl - →Cl2+2e - Cl2+H2O→HClO+H + +Cl -

[0004] Hypochlorous acid generated by electrolysis is a powerful oxidizing agent and can kill pathogens. Therefore, it is known that in the electrolysis treatment, the higher the applied voltage and the longer the applied time, the higher the killing efficiency of pathogens (for example, see Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

[0006] However, with electrolysis, the amount of chloride present in the treated water is unknown, and it is difficult to set the applied voltage and energizing time to obtain the desired pathogen killing efficiency (pathogen killing rate, pathogen removal rate). In addition, electrolysis of treated water can produce by-products, and it is not desirable to carry it out for a long time. Furthermore, multiple types of chloride may be present in the treated water, making it difficult to accurately determine the chloride concentration in the treated water.

[0007] Therefore, the problem that the present invention aims to solve is to provide a system and method for electrolyzing water to be treated that can achieve a predetermined pathogen killing rate while suppressing the generation of by-products. [Means for solving the problem]

[0008] To solve the above problems, the inventors diligently conducted research on how to estimate the concentration of chloride in the water to be treated and how to estimate the endpoint of the electrolysis treatment. As a result, the inventors found that there is a correlation between the conductivity of the water to be treated and the chloride concentration in the water to be treated, and that sterilization is completed when the pH of the water to be treated changes from decreasing to increasing during the electrolysis treatment.

[0009] After further trial and error, the inventors concluded that by setting the conditions for electrolysis treatment based on the conductivity of the water to be treated, and by monitoring the pH of the water to be treated during electrolysis and resetting the endpoint of the electrolysis treatment, it might be possible to efficiently sterilize the water to be treated while avoiding excessive electrolysis.

[0010] Based on these ideas, the inventor finally succeeded in creating a system and method for electrolyzing water to be treated based on conductivity and pH, thereby solving the problems of the present invention. This invention is completed based on the initial ideas and successful examples made by the inventor.

[0011] In other words, according to each aspect of the present invention, the following embodiments are provided. [1] An electrolysis system for water to be treated, The system comprises an electrolysis cell, conductivity measuring means, pH measuring means, and control means. The electrolysis tank is capable of subjecting the contained water to be treated to electrolysis treatment. The conductivity measuring means is capable of measuring the conductivity of the water to be treated. The pH measuring means is capable of measuring the pH of the water to be treated. The control means sets the conditions for the electrolysis treatment based on the conductivity of the water to be treated before the electrolysis treatment, and controls the electrolysis treatment to modify the conditions based on the pH of the water to be treated after the electrolysis treatment. The aforementioned system. [2] The system according to item [1], wherein the conditions for the electrolysis treatment are at least one condition selected from the group consisting of voltage, current value and time. [3] The water to be treated contains halogen ions, and The electrolysis tank is capable of generating halogenated oxygen acids by subjecting the contained water to be treated to electrolysis, according to the system described in item [1] or [2]. [4] The system according to item [3], wherein the control means sets the conditions for the electrolysis treatment based on the conductivity of the water to be treated before the electrolysis treatment, and modifies the set conditions based on the pH of the water to be treated after the electrolysis treatment, thereby controlling the electrolysis treatment so that the amount of halogen oxygen acid produced is a predetermined amount. [5] The amount of halogenated oxygen acid produced is such that the rate of killing pathogens in the treated water reaches a predetermined value, as described in item [4]. [6] The system described in item [5] is a pathogen killing system for killing pathogens in treated water. [7] A method for electrolyzing water to be treated, A process for measuring the conductivity of the water to be treated, A step of subjecting the treated water, whose conductivity has been measured, to electrolysis treatment, A step of measuring the pH of the water to be treated that has been subjected to electrolysis treatment, and including the conditions of the electrolysis treatment are set based on the conductivity and corrected based on the pH said method. [8] A method for killing pathogens in water to be treated, comprising: a step of measuring the conductivity of the water to be treated, a step of subjecting the water to be treated having the conductivity measured to electrolysis treatment, a step of measuring the pH of the water to be treated that has been subjected to electrolysis treatment, and including the conditions of the electrolysis treatment are set based on the conductivity and corrected based on the pH said method. [9] The water to be treated contains halogen ions, and the electrolysis treatment produces halogen oxyacids, the method according to item [8] or [9]. [Advantages of the Invention]

[0012] According to the present invention, by killing pathogens in the water to be treated while suppressing the generation of by-products, the water to be treated can be efficiently sterilized. Further, according to the present invention, by performing electrolysis treatment based on the conductivity and pH of the water to be treated, the water to be treated can be sterilized more simply. [Brief Description of the Drawings]

[0013] [Figure 1] FIG. 1 is a layout diagram of an electrolysis system 1 for water to be treated. [Figure 2] FIG. 2 is a diagram showing the relationship between the chloride ion concentration and the conductivity in water to be treated. [Figure 3] FIG. 3 is a diagram showing the change over time of the pH of water to be treated during electrolysis treatment. [Figure 4] FIG. 4 is a block diagram showing the functional configuration of the control means 5. [Figure 5] FIG. 5 is a flowchart of a method of electrolysis treatment by an electrolysis system for water to be treated. [Figure 6] Figure 6 is a layout diagram of the electrolysis system 10 for the water to be treated. [Figure 7] Figure 7 is a layout diagram of the wastewater treatment system 100 incorporating the electrolysis system 1 for the water to be treated. [Modes for carrying out the invention]

[0014] The details of each aspect of the present invention will be described below, but the present invention can take various forms insofar as it achieves its objective.

[0015] In this specification, unless otherwise specified, each term is used in the sense commonly used by those skilled in the art, such as in the field of water treatment, and should not be interpreted as having an unreasonably restrictive meaning. Furthermore, since the assumptions and theories made herein are based on the inventors' prior knowledge and experience, the present invention is not limited solely to such assumptions and theories.

[0016] "Comprise," "contain," and "include" mean that elements other than those explicitly included can be added (synonymous with "at least include"), but they also encompass "consist of" and "essentially consist of." In other words, "comprise" can mean including the explicitly included elements and any one or more of those elements, consisting of the explicitly included elements, or essentially consisting of the explicitly included elements. "Have" is synonymous with "comprise." Elements include limitations such as parts, means, components, processes, conditions, and parameters. "and / or" and its abbreviated form " / " mean any one, any combination of two or more, or all combinations of the listed related items. Throughout this specification, unless the context clearly indicates a singular term, the terms are to be plural. As used herein, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" encompasses both the meanings of "based solely on" and "based at least on." A "pathogen" is an organism or part thereof that exhibits or is likely to exhibit pathogenicity to the human body, and examples include microorganisms such as bacteria, viruses, and protozoa, as well as organic substances such as lipopolysaccharide proteins which are parts of these microorganisms. "Eliminating pathogens" means reducing the number of pathogens or inactivating their pathogenicity, and includes killing and decomposing pathogens, as well as inhibiting their proliferation. "Sterilization of treated water" means treating the water in a way that kills pathogens.

[0017] One aspect of the present invention is an electrolysis system for water to be treated. An electrolysis system according to one aspect of the present invention comprises an electrolysis tank, conductivity measuring means, pH measuring means, and control means. The electrolysis tank is capable of subjecting the contained water to be treated to electrolysis treatment. The conductivity measuring means is capable of measuring the conductivity of the water to be treated. The pH measuring means is capable of measuring the pH of the water to be treated. The control means sets the conditions for the electrolysis treatment based on the conductivity of the water to be treated before electrolysis treatment and controls the electrolysis treatment to modify the conditions based on the pH of the water to be treated after electrolysis treatment.

[0018] Another aspect of the present invention is a method for electrolyzing water to be treated. An electrolysis method according to one embodiment of the present invention includes the steps of measuring the conductivity of the water to be treated, subjecting the water to be treated whose conductivity has been measured to an electrolysis treatment, and measuring the pH of the water to be treated after the electrolysis treatment. The conditions for the electrolysis treatment are set based on the conductivity and modified based on the pH.

[0019] Another aspect of the present invention is a method for killing pathogens in treated water. One embodiment of the present invention includes the steps of measuring the conductivity of the treated water, subjecting the treated water whose conductivity has been measured to electrolysis, and measuring the pH of the treated water after electrolysis. The conditions for the electrolysis are set based on the conductivity and modified based on the pH.

[0020] The following describes various aspects and embodiments of the present invention with reference to the drawings. In each drawing, elements 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.

[0021] Figure 1 is a layout diagram of an electrolysis system 1 for water to be treated, which is an embodiment of an electrolysis system according to one aspect of the present invention. The electrolysis system 1 for water to be treated comprises an electrolysis tank 2, a conductivity measuring means 3, a pH measuring means 4, and a control means 5. The water to be treated WW is received into the electrolysis tank 2 via the conductivity measuring means 3, subjected to electrolysis treatment, and then discharged from the electrolysis tank 2 as electrolyzed water EW.

[0022] The electrolysis tank 2 is equipped with a pair of electrodes 6, consisting of an anode and a cathode, and is capable of subjecting the contained water to be treated WW to electrolysis treatment. Based on input signals from the control means 5, the electrodes 6 are energized by a power source such as a DC power supply to electrolyze the water to be treated WW contained in the electrolysis tank 2.

[0023] When the water to be treated contains halides such as chlorides, halogenated oxygen acids are generated from halogen ions. Halogenated oxygen acids function as oxidizing agents with activity to kill pathogens. Examples of halogenated oxygen acids include hypohalous acid, halogenous acid, hydrohalic acid, and perhalic acid. Specifically, examples include hypochlorous acid, chlorous acid, hypobromite, hydrochloric acid, perchloric acid, and monobasic fluorine-containing oxyacids, but hypochlorous acid, which has strong activity to kill pathogens, is preferred. When chloride ions (Cl) are present in the water to be treated WW, - If ) is present, hypochlorous acid (HClO) will be generated by electrolysis of the treated water WW.

[0024] Electrode 6 can be appropriately configured depending on the type of oxidizing agent to be generated, but it is preferable that the electrode generates halogen oxygen acids from halides in the treated water when an electric current is applied. To increase the efficiency of halogen oxygen acid generation, electrode 6 is preferably coated with a catalyst such as iridium, ruthenium, platinum, or tantalum, or an alloy thereof, such as titanium. Specific examples of electrode 6 include electrodes coated with iridium and ruthenium on titanium.

[0025] The conductivity measuring means 3 is capable of measuring the conductivity (electrical conductivity, electrical conductivity) of the treated water WW, which is expressed in Siemens per unit length, and specifically in units of μS / cm. The inventors have found that there is a correlation between halogen ions contained in wastewater or treated water obtained by subjecting wastewater to water treatment and conductivity.

[0026] For example, as shown in Figure 2, when domestic wastewater was subjected to biological treatment and then passed through a microfiltration (MF) membrane, the chloride ion content and conductivity of the treated water were measured, and a correlation was found between the two. Therefore, by measuring the conductivity of the treated water WW, the chloride ion concentration in the treated water WW can be estimated. If the conductivity of the treated water WW is low and the halogen ion concentration is estimated to be low, halogen oxygen salts such as sodium salts may be added to the treated water WW.

[0027] The pH measuring means 4 is capable of measuring the pH (hydrogen ion concentration index) of the treated water WW contained in the electrolysis tank 2. The inventors have found that when wastewater or treated water obtained by treating wastewater is subjected to electrolysis treatment, the pH fluctuates over time.

[0028] For example, when domestic wastewater was subjected to biological treatment, and then the treated water obtained by passing it through a microfiltration (MF) membrane was subjected to electrolysis, it was found that the pH trend shown in Figure 3 could be obtained by measuring the pH over time. Electrolysis increases hypochlorous acid and raises the pH, but it is consumed by killing pathogens in the treated water, causing the pH to decrease to near neutral. However, as the number of pathogens in the treated water decreases, the decomposition of hypochlorous acid stops (as shown in Figure 3). o ) marks the point where the pH begins to rise. Therefore, the turning point t o The endpoint of the electrolysis process can be inferred from this.

[0029] The conductivity measuring means 3 and pH measuring means 4 convert the measured conductivity and pH values ​​into appropriate signals and input them to the control means 5. Preferably, the conductivity measuring means 3 / pH measuring means 4 are, for example, conductivity sensors and pH sensors that transmit conductivity and pH values ​​as electrical signals to the control means 5. The conductivity measuring means 3 / pH measuring means 4 may also be devices having detection probes such as electrodes.

[0030] The conductivity and pH of the treated water WW measured by the conductivity measuring means 3 and the pH measuring means 4 may be measured independently, once or two or more times, and if two or more times, they may be continuous or intermittent. In particular, the conductivity of the treated water WW measured by the conductivity measuring means 3 may be measured once or two or more times, but it is preferable that the pH of the treated water WW measured by the pH measuring means 4 be measured two or more times, and moreover, that they be continuous.

[0031] The control means 5 functions to set and modify the conditions for the electrolysis treatment in the electrolysis tank 2. Specifically, the control means 5 sets the conditions for the electrolysis treatment in the electrolysis tank 2 based on the conductivity of the water to be treated WW before electrolysis, as measured by the conductivity measuring means 3, and controls the electrolysis treatment to modify the conditions based on the pH of the water to be treated WW during electrolysis, as measured by the pH measuring means 4. The control means 5 may also control the water to be treated inlet valve 7a, which restricts the inflow of the water to be treated WW by opening and closing, and the electrolyzed water outlet valve 7b, which restricts the outflow of electrolyzed water EW by opening and closing, in order to subject the water to be treated WW to electrolysis treatment for a predetermined time.

[0032] The conditions for electrolysis treatment are determined by estimating the halogen ion concentration in the water to be treated WW through its conductivity, and then determining the voltage applied to electrode 6, the current flowing through electrode 6, and the duration of current flow to electrode 6. As shown in Fig. 2(a) of Non-Patent Literature 1, the amount of oxidizing agent produced tends to increase as the voltage applied to electrode 6 increases and the current flowing time increases. Therefore, if the conductivity of the water to be treated WW is low and the halogen ion concentration is estimated to be low, the conditions for electrolysis treatment are set to increase the voltage applied to electrode 6, increase the current flowing through electrode 6, and / or increase the duration of current flow to electrode 6. Conversely, if the conductivity of the water to be treated WW is high and the halogen ion concentration is estimated to be high, the conditions for electrolysis treatment are set to decrease the voltage applied to electrode 6, decrease the current flowing through electrode 6, and / or decrease the duration of current flow to electrode 6.

[0033] Furthermore, it is preferable to set the electrolysis treatment conditions taking into account the types and numbers of pathogens in the treated water WW. For example, if the number of pathogens in the treated water WW is large, it is preferable to set the electrolysis treatment conditions so that the amount of halogenated oxygen acids produced increases accordingly, and if the number of pathogens in the treated water WW is small, it is preferable to set the electrolysis treatment conditions so that the amount of halogenated oxygen acids produced does not become excessive. Note that, as shown in Fig. 3(a) of Non-Patent Literature 1, the log reduction rate differs depending on the microbial species, and if most of the pathogens contained in the treated water WW are bacteria, the electrolysis treatment time can be set to a relatively short time.

[0034] Modification of the electrolysis treatment is made based on the pH of the treated water WW during the electrolysis treatment as measured by the pH measuring means 4. The conditions of the electrolysis treatment are modified to reduce the degree of electrolysis treatment of the treated water WW or to stop the electrolysis treatment, using the turning point where the pH of the treated water WW changes from decreasing to increasing as an indicator. Modification of the electrolysis treatment may also be made using the indicator that the pH of the treated water WW has sufficiently decreased, for example, the rate of decrease from the initial pH. In other words, modification of the electrolysis treatment may be made using the desired pathogen killing rate as an indicator.

[0035] The control means 5 preferably has a processing unit that functions to set and modify the conditions of the electrolysis process in the electrolysis tank 2. As a specific embodiment of the control means 5 having a processing unit, a block diagram showing the functional configuration of the control means 5 is illustrated in Figure 4.

[0036] As shown in Figure 4, the control means 5 comprises a processing unit 51, a storage unit 52, and an input / output unit 53. The control means 5 may further include a display unit. The display unit displays the conductivity detected by the conductivity measuring means 3, the pH detected by the pH measuring means 4, the conditions of the electrolysis treatment, etc. Each component is connected to the others so as to be able to communicate with each other via a bus 54.

[0037] The processing unit 51 is configured to acquire signals from the conductivity measuring means 3 / pH measuring means 4 as input values ​​and to issue commands to the electrode 6, the water to be treated inlet valve 7a, and the electrolyzed water outlet valve 7b as output values. Based on the signals from the conductivity measuring means 3 / pH measuring means 4, the processing unit 51 sets and modifies the conditions for the electrolysis process by comparing them with an index value 521, past or current signal history 522, etc., or by using a setting program 523 / modification program 524.

[0038] The memory unit 52 is composed of a storage device and stores the index value 521, signal history 522, setting program 523, correction program 524, etc. The memory unit 52 may also store signals from the conductivity measuring means 3 / pH measuring means 4 that have just been acquired by the control means 5, output values ​​which are the setting / correction results from the processing unit 51, etc. The setting program 523 functions to cause the processing unit 51 to set the conditions for the electrolysis process based on the signal from the conductivity measuring means 3 and the index value 521 and / or signal history 522. The correction program 524 functions to cause the processing unit 51 to correct the conditions for the electrolysis process based on the signal from the pH measuring means 4 and the index value 521 and / or signal history 522.

[0039] The input / output unit 53 is configured to transmit signals from the conductivity measuring means 3 / pH measuring means 4 to the processing unit 51, and to transmit commands to control the electrode 6 (and the power supply connected to it) according to the conditions of the electrolysis process based on the settings / corrections of the processing unit 51.

[0040] Examples of control means 5 include control circuits, microcontrollers, single-board computers, personal computers (notebook PCs, desktop PCs), tablet terminals, and smartphones.

[0041] Each device connected to the control means 5 via the input / output unit 53 may be independently connected by wire, or may be connected wirelessly via a router or the like, or without such a device. The control means 5 may control the electrolysis process immediately or with a delay based on signals from the conductivity measuring means 3 / pH measuring means 4.

[0042] 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 conductivity measurement means 3 / pH measurement means 4. A non-limited specific example of controlling the electrolysis process using a machine learning model with AI is described below. The 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.

[0043] Controlling electrolysis processes using machine learning models is divided into a learning phase and an inference phase. In the learning phase, the model is trained. Model training is performed using integrated data as input data, which includes the conductivity and halogen ion concentration of the treated water (WW) stored in a database in the memory of a PC or other device, the pH trend during electrolysis of the treated water (WW), the current value (current density), the treatment time, and the pathogen killing rate. The integrated data may also include pre-configured data and standard data that correct or complement the above data. Examples of such data include past electrolysis treatment condition setting data, arbitrary pre-configured data, and past electrolysis treatment result data. During model training, the parameter values ​​constituting the model are adjusted so that the output training result data is suitable for the input data. The training result data is the data of the training results for the electrolysis treatment conditions.

[0044] In the inference phase, the trained model, i.e., the updated model, is input with integrated data including input data based on the conductivity and pH of the treated water WW, as well as the trained result data. Inference processing is then performed to obtain inference result data. The inference result data is the data of the inference results for the electrolysis treatment conditions. The inference processing can be performed using the algorithms described above.

[0045] By using the electrolysis system 1 for treated water, the electrolysis treatment of the treated water can be appropriately performed based on conductivity and pH, achieving the elimination of pathogens and preventing excessive electrolysis that would generate by-products even after the pathogens have been eliminated. Furthermore, by inputting a desired pathogen elimination rate as a set value, it is possible to control the electrolysis treatment conditions to set and modify them so that the pathogen elimination rate is achieved.

[0046] The water to be treated (WW) can be any water containing pathogens that can be killed by electrolysis. Examples include domestic wastewater discharged from drainage facilities such as washrooms, toilets, kitchens, bathrooms, and laundry rooms, as well as urban wastewater, commercial wastewater, agricultural wastewater, industrial wastewater, sewage, rainwater, surface water, seawater, tap water, and treated water obtained by chemical treatment, biological treatment, filtration, etc. It is preferable that the water to be treated (WW) contains halides so that halogenated oxygen acids can be generated by electrolysis. If the water to be treated (WW) does not contain halides, or contains only a small amount, halides (e.g., NaCl) may be added to the water to be treated (WW). Organic compounds can also be decomposed by electrolysis of the water to be treated (WW).

[0047] Electrolyzed water EW is water obtained by subjecting water to be treated WW to electrolysis treatment, and is water in which the number of pathogens in the water to be treated WW has been reduced, preferably water in which the number of pathogens is 1 / 100 to 1 / 1,000,000 (log2 to log6 reduction) compared to the number in the water to be treated WW.

[0048] An example of the electrolysis treatment method using the electrolysis system 1 for the water to be treated will be explained using the flowchart shown in Figure 5.

[0049] As illustrated in Figure 5, the control means 5 controls the treated water inlet valve 7a to open so that the treated water WW flows into the electrolysis tank 2 (S101). Next, the control means 5 obtains the value obtained by the conductivity measuring means 3 from measuring the conductivity of the treated water WW (S102). Based on this conductivity value, the control means 5 sets the conditions for the electrolysis treatment of the treated water WW in the electrolysis tank 2 (S103).

[0050] Next, the inflow of the water to be treated WW into the electrolysis tank 2 is stopped (S104), and the water to be treated WW is subjected to electrolysis in the electrolysis tank 2 under the electrolysis conditions set above (S105). While the electrolysis is being performed, the control means 5 acquires the pH of the water to be treated WW measured by the pH measuring means 4 (S106). The control means 5 modifies the conditions of the electrolysis according to the pH trend of the water to be treated WW (S107). For example, if the pH of the water to be treated WW is on a downward trend, the electrolysis is continued as is; if the pH of the water to be treated WW has plateaued after decreasing, the amount of current supplied to the electrode 6 is reduced; and if the pH of the water to be treated WW is on an upward trend after decreasing, the supply of current to the electrode 6 is stopped and the electrolysis is terminated (S108). In addition, if no change is observed in the pH of the water to be treated WW after the electrolysis is started, the voltage applied to the electrode 6 may be increased to increase the amount of current.

[0051] After the electrolysis process is completed, the electrolyzed water outlet valve 7b is opened to discharge the electrolyzed water EW obtained by the electrolysis process from the electrolysis tank 2 (S109).

[0052] Figure 6 is a layout diagram of an electrolysis system 10 of water to be treated according to another embodiment of the present invention. In the electrolysis system 10 of water to be treated, the conductivity measuring means 3 and the pH measuring means 4 are integrally incorporated into the electrolysis tank 2. Therefore, in the electrolysis system 10 of water to be treated, the conductivity and pH of the water to be treated WW can be measured before, during, and after the electrolysis treatment.

[0053] An electrolysis system for water to be treated according to one aspect of the present invention can be incorporated, for example, into a wastewater treatment system. Figure 7 is a layout diagram of a wastewater treatment system 100 incorporating the electrolysis system 1 for water to be treated. The wastewater treatment system 100 sends wastewater through a wastewater tank to a treatment tank (chemical treatment tank, biological treatment tank, etc.) for wastewater treatment. The primary treated water treated in the treatment tank is then sent to the electrolysis system 1 for water to be treated via a separation membrane. The electrolyzed water obtained by electrolysis treatment in the electrolysis system 1 for water to be treated is sent to a membrane separation means via an intermediate tank. The permeate from the membrane separation means is stored in a treated water layer and used as purified water.

[0054] A wastewater treatment system is any system that treats wastewater flowing in from outside the system and then supplies the resulting treated water as purified water to the outside. A wastewater treatment system may be a building wastewater treatment system installed in a residence, small commercial facility, factory plant, temporary facility, etc., or it may be a portable wastewater treatment system that can be moved. Among wastewater treatment systems, a device that connects to the drainage system of a building, treats the wastewater flowing in from the drainage system, and returns the resulting treated water as purified water to the drainage system, that is, a device that regenerates and circulates water between the building's drainage system and the wastewater treatment system, is called a self-sustaining circulating wastewater treatment system, and when the building is a residence such as a house, it is called a self-sustaining circulating residential wastewater treatment system.

[0055] It should be noted that the present invention is not limited to any of the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components from all the components shown in the embodiments may be modified by addition, deletion, substitution, etc. Moreover, components and forms from different embodiments may be appropriately combined. [Industrial applicability]

[0056] An electrolysis system, electrolysis method, and pathogen elimination method according to one aspect of the present invention can be used to eliminate pathogens contained in treated water, thereby producing water with a reduced number of pathogens or water free of pathogens. These systems and methods can be used to supply water users with safe and reliable water. [Explanation of Symbols]

[0057] 1. 10 Electrolysis system for treated water 2. Electrolysis cell 3 Conductivity measurement means 4 pH measuring means 5. Control means 51 Processing Unit 52 Storage section 521 Index Values 522 Signal History 523 Configuration Program 524 Update 53 Input / output section 54 bus 6 electrodes 7a Inlet valve for treated water 7b Electrolyzed water outlet valve

Claims

1. An electrolysis system for water to be treated, The system comprises an electrolysis cell, conductivity measuring means, pH measuring means, and control means. The electrolysis tank is capable of subjecting the contained water to be treated to electrolysis treatment. The conductivity measuring means is capable of measuring the conductivity of the water to be treated. The pH measuring means is capable of continuously measuring the pH of the water to be treated contained in the electrolysis tank. The control means sets the conditions for the electrolysis treatment based on the conductivity of the water to be treated before the electrolysis treatment, and controls the electrolysis treatment to terminate based on the pH turning point of the water to be treated, which is continuously measured in the electrolysis tank. The aforementioned system.

2. The system according to claim 1, wherein the conditions for the electrolysis treatment are at least one condition selected from the group consisting of voltage, current value, and time.

3. The water to be treated contains halogen ions, and The system according to claim 1 or 2, wherein the electrolysis tank is capable of generating halogenated oxygen acids by subjecting the water to be treated to electrolysis.

4. The system according to claim 3, wherein the control means sets the conditions for the electrolysis treatment based on the conductivity of the water to be treated before subjecting it to the electrolysis treatment, and terminates the electrolysis treatment based on the pH turning point of the water to be treated, which is continuously measured in the electrolysis tank, and controls the electrolysis treatment so that the amount of halogen oxygen acid produced is a predetermined amount.

5. The system according to claim 4, wherein the amount of halogenated oxygen acid produced is such that the rate of killing pathogens in the treated water reaches a predetermined value.

6. The system according to claim 5, wherein the system is a pathogen killing system for killing pathogens in water to be treated.

7. A method for electrolyzing water to be treated, A process for measuring the conductivity of the water to be treated, A step of subjecting the water to be treated, whose conductivity has been measured, to electrolysis treatment in an electrolysis tank, A process of continuously measuring the pH of the water to be treated contained in the electrolysis tank. Includes, The conditions for the electrolysis treatment are set based on the conductivity, and the electrolysis treatment is terminated based on the pH transition point. The aforementioned method.

8. A method for killing pathogens in treated water, A process for measuring the conductivity of the water to be treated, A step of subjecting the water to be treated, whose conductivity has been measured, to electrolysis treatment in an electrolysis tank, A process of continuously measuring the pH of the water to be treated in the electrolysis tank and Includes, The conditions for the electrolysis treatment are set based on the conductivity, and the electrolysis treatment is terminated based on the pH transition point. The aforementioned method.

9. The water to be treated contains halogen ions, and The method according to claim 8, wherein the electrolysis treatment generates a halogenated oxygen acid.

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