Chlorine agent injection amount calculation method, chlorine agent injection amount calculation device, and water treatment system

Abstract

To provide a chlorine agent injection amount calculation method, a chlorine agent injection amount calculation device, and a water treatment system capable of calculating the amount of chlorine agent to be injected into water to be treated using a simple method, thereby reducing the burden on operators in charge of management.SOLUTION: In a water treatment plant that has a step for injecting chlorine agent into water to be treated, a chlorine agent injection amount calculation method includes a water area acquisition step for acquiring a water area of a water tank exposed to sunlight after chlorine agent is injected into the water to be treated, a temperature acquisition step for acquiring temperature near the water tank, and a chlorine agent injection amount calculation step for calculating the amount of chlorine agent injected into the water to be treated using a regression equation created by performing regression analysis using past operation data sets of the water treatment plant, with the product of the water area and temperature, and a flow rate of the water to be treated at a point where the chlorine agent is injected as explanatory variables, and the chlorine agent injection amount as a target variable.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a chlorine agent injection amount calculation method, a chlorine agent injection amount calculation device, and a water treatment system, and more particularly to a chlorine agent injection amount calculation method, a chlorine agent injection amount calculation device, and a water treatment system suitable for controlling the injection of chlorine agents in water purification plants. [Background technology]

[0002] In water treatment processes, chlorine agents are added to the water being treated in order to adjust the properties of the water, etc. For example, in water purification plants, there are three injection processes for injecting chlorine agents into the water being treated: pre-hypochlorite, intermediate hypochlorite, and post-hypochlorite.

[0003] Pre-hypochlorite is used to adjust the properties of raw water, for example to kill algae, and is often manually controlled based on the operator's judgment as to whether or not to inject. Post-hypochlorite is mainly used to adjust the hypochlorite concentration in the treated water to a target value when distributing the treated water outside the water treatment plant, and can be automatically adjusted using automatic feedback control, etc.

[0004] On the other hand, the intermediate hypochlorite treatment aims to adjust the hypochlorite concentration in the treated water in advance so that it falls within a concentration range that makes it easy to perform finishing adjustments in the post-treatment hypochlorite treatment, and is a chlorine injection treatment that is mainly carried out after treatment in a sedimentation tank. However, there are not many existing systems that can fully achieve this purpose, and many water purification plants rely on continuous monitoring and intermittent control by operators.

[0005] Various studies have been conducted on the control of chlorine agent injection into water to be treated. For example, Japanese Patent Application Laid-Open No. 2022-41456 (Patent Document 1) describes an example of a chlorine reduction amount calculation device that includes a first acquisition unit that acquires data on the gas phase near an open-top tank in a water treatment process that includes a step of injecting a chlorine agent into the water to be treated, a chlorine transfer amount calculation unit that uses the data on the gas phase to calculate the amount of chlorine contained in the water to be treated that transfers to the gas phase per unit time and unit area, and a chlorine reduction amount calculation unit that calculates the amount of chlorine reduction in the water to be treated based on the amount of transfer.

[0006] Patent Publication No. 7234012 (Patent Document 2) describes an example of a chlorine injection control device for a water purification process that includes a step of injecting a chlorine agent into the treated water. The device includes an acquisition unit that acquires an ultraviolet index as dose data related to the dose of ultraviolet light irradiated to the treated water, and an estimation unit that estimates the amount of chlorine decomposition in the treated water based on the amount of ultraviolet light for each wavelength acquired from the dose data. The estimation unit acquires the total amount of ultraviolet light dose irradiated to the treated water based on the intensity of ultraviolet light indicated by the ultraviolet index, and estimates the amount of ultraviolet light for each wavelength by applying this total amount to the spectral distribution of ultraviolet light.

[0007] Japanese Patent Publication No. 2023-23742 (Patent Document 3) describes an example of a method for determining the addition rate of a chemical for water treatment, in which prediction condition data including at least a first measurement value of the water quality of the water to be treated and a second measurement value of the water quality after the chemical has been added is input into a model constructed by machine learning using training data including at least a first past measurement value of the water quality of the water to be treated, a second past measurement value of the water quality after the chemical has been added, and the actual addition rate of the chemical associated with the first past measurement data and the second past measurement data, and the chemical addition rate is output from the model. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2022-41456 [Patent Document 2] Patent No. 7234012 [Patent Document 3] Japanese Patent Publication No. 2023-23742 Summary of the Invention [Problem to be solved by the invention]

[0009] As described in Patent Documents 1 to 3, various technologies related to the injection of chlorine agents into water to be treated in water purification plants have been conventionally studied. However, since the chlorine injected into the water to be treated is decomposed by a plurality of factors, it may be difficult to estimate the decomposition amount of chlorine in the water to be treated based on theories such as those in Patent Documents 1 to 3. In addition, there is also a problem that it is difficult to stably maintain the chlorine concentration in the water to be treated due to fluctuations in the properties of the raw water. Therefore, the management of the chlorine agent injection amount is often manually adjusted based on the experience or tacit knowledge of the operator, taking into account the characteristics of the entrusted water purification plant, but there is a problem that the burden on the operator in charge of management increases.

[0010] In view of the above problems, the present invention provides a chlorine agent injection amount calculation method, a chlorine agent injection amount calculation device, and a water treatment system that can calculate the chlorine agent injection amount to be injected into water to be treated by a simple method and can reduce the burden on the operator in charge of management.

Means for Solving the Problems

[0011] The present inventors earnestly studied to convert the tacit knowledge of the operator in charge of management into formal knowledge about various factors related to the decomposition of chlorine in the water to be treated and the chlorine agent injection amount in the water purification plant. As a result, a specific relationship, particularly, the product of the water surface area and the air temperature of a water tank that receives sunlight after the injection of the chlorine agent into the water to be treated, or the relationship of the product of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, etc. was found to be useful for estimating the chlorine agent injection amount.

[0012] In order to solve the above problems, in one aspect, the present invention provides a chlorine agent injection amount calculation method having a water surface area acquisition step of acquiring the water surface area of a water tank that receives sunlight after the injection of a chlorine agent into water to be treated in a water purification plant having a step of injecting a chlorine agent into the water to be treated, a temperature acquisition step of acquiring the air temperature in the vicinity of the water tank, and a regression equation created by performing regression analysis using the product of the water surface area and the air temperature and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables and the chlorine agent injection amount as the objective variable, using the past operation data set of the water purification plant, and a chlorine agent injection amount calculation step of calculating the chlorine agent injection amount to be injected into the water to be treated.

[0013] In one embodiment, the method for calculating the chlorine agent injection amount according to the present invention includes calculating the chlorine agent injection amount into the water to be treated by using a regression equation prepared by performing a regression analysis using the past operation data set of the water purification plant, with the product of the water surface area and the air temperature, the flow rate of the water to be treated at the location where the chlorine agent is injected, and the product of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables, and the chlorine agent injection amount as the target variable.

[0014] In another embodiment, the method for calculating the chlorine agent injection amount according to the present invention includes calculating the chlorine agent injection amount into the water to be treated by using a regression equation prepared by performing a regression analysis using the past operation data set of the water purification plant, with the product of the water surface area and the air temperature, the flow rate of the water to be treated at the location where the chlorine agent is injected, the product of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, and the product of the concentration of the component that consumes the chlorine agent pre - contained in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables, and the chlorine agent injection amount as the target variable.

[0015] In yet another embodiment, the method for calculating the chlorine agent injection amount according to the present invention includes calculating the chlorine agent injection amount into the water to be treated by using a regression equation prepared by performing a regression analysis using the past operation data set of the water purification plant, with the product of the water surface area and the air temperature, the flow rate of the water to be treated at the location where the chlorine agent is injected, the product of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, the product of the concentration of the component that consumes the chlorine agent pre - contained in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, and the product of the chlorine agent concentration in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables, and the chlorine agent injection amount as the target variable.

[0016] In yet another embodiment of the chlorine agent dosage calculation method according to the present invention, the chlorine agent dosage calculation step includes calculating the amount of chlorine agent to be injected into the water to be treated using a regression equation prepared by performing regression analysis using past operation data sets of the water purification plant, with the flow rate of the water to be treated at the point where the chlorine agent is injected and the product of the water temperature and the flow rate of the water to be treated at the point where the chlorine agent is injected as explanatory variables, and the chlorine agent dosage as a target variable.

[0017] In another aspect, the present invention provides In a water purification plant having a process of injecting a chlorine agent into water to be treated, The product of the chlorine concentration in the water to be treated and the flow rate of the water to be treated at the point where the chlorine is injected, The product of the concentration of the component that consumes the chlorine agent already contained in the water to be treated and the flow rate of the water to be treated at the point where the chlorine agent is injected, - The flow rate of the water to be treated at the point where the chlorine agent is injected, The product of the temperature of the water to be treated and the flow rate of the water to be treated at the point where the chlorine agent is injected, The product of the water surface area of the tank exposed to sunlight after chlorine injection and the air temperature By regression analysis with the amount of chlorine agent injection as the dependent variable, The following regression equation (X): [Amount of chlorine agent injected] = A [Concentration of chlorine agent in the water to be treated × Flow rate of the water to be treated at the point where chlorine agent is injected] + B [Concentration of components that consume chlorine agent already contained in the water to be treated × Flow rate of the water to be treated at the point where chlorine agent is injected] + C [Flow rate of the water to be treated at the point where chlorine agent is injected] + D [Temperature of the water to be treated × Flow rate of the water to be treated at the point where chlorine agent is injected] + E [Water surface area of the tank exposed to sunlight after chlorine agent injection × Air temperature] (X) and calculating the amount of chlorine agent to be injected into the water to be treated using the regression equation (X). (where A, B, C, D, E are coefficients, and the coefficients are - The specific water area of the water treatment plant; - The amount of chlorine added to the treated water obtained in the past, - Chlorine concentration of treated water obtained in the past, · The flow rate of the water to be treated at the location where the chlorine agent was injected in the past, · The concentration of the component that consumes the chlorine agent pre - contained in the water to be treated obtained in the past, · The water temperature of the water to be treated obtained in the past, · The air temperature obtained in the past, is a value derived by performing regression analysis using the dataset of these. )

[0018] In yet another embodiment of the chlorine agent injection amount calculation method according to the present invention, the concentration of the component that consumes the chlorine agent pre - contained in the water to be treated includes at least one of the concentrations of ammonia - nitrogen, reducing inorganic substances, and reducing organic substances.

[0019] In yet another aspect of the present invention, there is provided a chlorine agent injection amount calculation device for calculating the injection amount of the chlorine agent to be injected into the water to be treated, comprising: a water surface area acquisition unit for acquiring the water surface area of the water tank that receives sunlight after the injection of the chlorine agent into the water to be treated; an air temperature acquisition unit for acquiring the air temperature in the vicinity of the water tank; a storage device for storing the past operation dataset of the water purification plant equipped with the water tank; a regression equation creation unit for creating a regression equation by performing regression analysis using the product of the water surface area and the air temperature and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables and the chlorine agent injection amount as the objective variable; and a chlorine agent injection amount calculation unit for calculating the chlorine agent injection amount to be injected into the water to be treated using the regression equation.

[0020] In yet another aspect of the present invention, there is provided a water treatment system comprising: a chlorine agent injection device for injecting a chlorine agent into the water to be treated; a water tank for storing the water to be treated into which the chlorine agent has been injected; a regression equation creation unit for creating a regression equation by performing regression analysis using the product of the water surface area that is the area of the water tank receiving sunlight and the air temperature in the vicinity of the water tank and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables and the chlorine agent injection amount of the chlorine agent injection device as the objective variable, and a chlorine agent injection amount calculation unit for calculating the chlorine agent injection amount to be injected into the water to be treated by the chlorine agent injection device based on the regression equation.

Advantages of the Invention

[0021] According to the present invention, a chlorine agent injection amount calculation method, a chlorine agent injection amount calculation device, and a water treatment system can be provided that can calculate the amount of chlorine agent to be injected into the water to be treated using a simple method and reduce the burden on operators in charge of management. [Brief explanation of the drawings]

[0022]

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Embodiments for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The embodiments shown below are examples of devices and methods for embodying the technical idea of this invention, and the technical idea of this invention does not specify the structure, arrangement, etc. of the components as follows.

[0024] (Water Treatment Process) As a water treatment process suitable for this embodiment, an example of a purified water treatment process (purified water treatment step · wastewater treatment step) is shown in FIG. 1. In the purified water treatment step of the purified water treatment process, raw water (water to be treated) is taken in through the intake of the water intake facility provided in a river or the like, and in the grit chamber, treatment is performed to sink and remove sediment, sand, etc. The water to be treated flowing out from the grit chamber is sent to the intake well of the water purification plant via the water conveyance pump station. The intake well has the role of keeping the water level constant to the subsequent treatment facilities by suppressing the pressure change of the raw water due to water conveyance, and here, an alkaline agent such as activated carbon and caustic soda, and a pH adjuster such as sulfuric acid are injected as necessary, and treatment is performed to sink and remove soil and gravel in the water to be treated.

[0025] The water to be treated flowing out from the intake well is sent to the sedimentation tank via a chemical mixing tank, a flocculation formation tank, etc. (not shown). In the sedimentation tank, an inorganic flocculant such as PAC is injected and coagulation sedimentation treatment is performed. The sludge solid-liquid separated in the sedimentation tank is withdrawn as draw sludge from the sedimentation tank and sent to the wastewater treatment step. In the wastewater treatment step, the draw sludge is sent from the thickening tank to a filtration thickening device or the like for thickening treatment, and dehydration treatment is performed by a pressure dehydrator or the like, and the sludge with reduced water content is transported out of the treatment plant.

[0026] On the other hand, the water to be treated solid-liquid separated in the sedimentation tank is sent to sand filtration, and after further solid-liquid separation, the effluent water from the sand filtration device is stored in the distribution tank as purified water. The purified water stored in the distribution tank is pumped up to the water distribution pipe via the water distribution pump, and is sent to various external facilities such as homes, schools, and factories via the water distribution pipe and used as tap water.

[0027] In such a water purification process, there are generally three locations for injecting a chlorine agent into the water to be treated. The first location is the so-called "pre-hypochlorous" injection step, which aims to remove cyanobacteria, ammonia, etc. contained in the water to be treated immediately after water intake and adjust the water quality characteristics of the water to be treated. The second location is the so-called "mid-hypochlorous" injection step, which aims to perform manganese treatment, etc. on the water to be treated flowing out from the sedimentation tank (coagulation sedimentation treated water). The third location is the so-called "post-hypochlorous" injection step, which aims to inject a chlorine agent to disinfect and sterilize the purified water to be distributed.

[0028] The chlorine agent injection method according to the embodiment of the present invention can basically be applied to any of the pre-hypochlorous, mid-hypochlorous, and post-hypochlorous injection steps in a water purification plant. Among them, this embodiment is preferably applied to the mid-hypochlorous injection step in which the chlorine agent injection amount has conventionally been adjusted manually according to the operator's rule of thumb or tacit knowledge. Thereby, even in the mid-hypochlorous injection step where it has been difficult to optimize the management of the chlorine agent injection amount by feedback control or the like in the past, the chlorine agent injection amount can be calculated more appropriately. Therefore, it becomes possible to appropriately calculate the chlorine agent injection amount to be injected into the water to be treated without relying on the operator's rule of thumb or tacit knowledge.

[0029] In the following embodiments, the control flow of the chlorine agent injection amount in the mid-hypochlorous injection step will be described as an example, but this is not limited to this example, and it goes without saying that it is also applicable to the pre-hypochlorous or post-hypochlorous injection step and other chlorine agent injection steps.

[0030] After the chlorine agent is injected into the water to be treated, when the water to be treated stays in a water tank such as a filtration tank, for example, the chlorine in the water to be treated is decomposed under various influences, resulting in a decrease in the chlorine concentration. However, the mechanism of chlorine decomposition in the water to be treated has not been codified or formulated empirically, and has not yet been quantitatively expressed.

[0031] Operators engaged in the water purification process estimate the decomposition amount of chlorine in the water to be treated based on skills acquired through experience and then optimize the chlorine agent injection amount to be injected into the water to be treated from the estimation results. This skill is often the tacit knowledge of the operators and has not been converted into explicit knowledge. One of the reasons why tacit knowledge has not been converted into explicit knowledge is considered to be that the existing water purification facilities have always been in an environment where manual control can be carried out.

[0032] When analyzing in detail the tacit knowledge shared by the operators, in the water purification process with multiple chlorine agent injection points for the water to be treated, the calculation of the chlorine agent injection amount can be optimized by considering the following matters. (1) When performing pre-chlorite injection into the water to be treated for the purpose of algae killing, it is preferable to control the chlorine agent injection rate in the mid-chlorite injection to be lower than the set value of the injection amount. (2) When there are disturbing substances that are components consuming the chlorine agent pre-existing in the water to be treated, it is preferable to control the chlorine agent injection rate in the mid-chlorite injection to be higher than the set value of the injection amount. (3) When the flow rate of the injection point of the chlorine agent in the mid-chlorite injection changes, if the flow rate tends to be controlled above the set value, the residence time in the water tank decreases, so the amount of volatilization and decomposition of the chlorine agent from the water to be treated decreases. Therefore, it is preferable to control the chlorine agent injection rate in the mid-chlorite injection to be lower than the set value of the injection amount. On the other hand, if the flow rate of the injection point of the chlorine agent in the mid-chlorite injection tends to be controlled below the set value, the amount of volatilization and decomposition of the chlorine agent from the water to be treated increases. Therefore, it is preferable to control the chlorine agent injection rate in the mid-chlorite injection to be higher than the set value of the injection amount. (4) When the water temperature of the water to be treated changes with seasonal changes, when the water temperature rises, the amount of volatilization and decomposition of the chlorine agent from the water to be treated tends to increase. Therefore, it is preferable to control the chlorine agent injection rate in the mid-chlorite injection to be higher than the set value of the injection amount. On the other hand, when the water temperature drops, the amount of volatilization and decomposition of the chlorine agent from the water to be treated tends to decrease. Therefore, it is preferable to control the chlorine agent injection rate in the mid-chlorite injection to be lower than the set value of the injection amount. (5) When the solar radiation amount to the water to be treated changes depending on sunny days and bad weather, when the solar radiation amount increases, the amount of chlorine agent volatilized and decomposed from the water to be treated tends to increase. Therefore, it is preferable to control the chlorine agent injection rate in the intermediate hypochlorite injection above the set value of the injection amount. On the other hand, when the solar radiation amount decreases, the amount of chlorine agent volatilized and decomposed from the water to be treated tends to decrease. Therefore, it is preferable to control the chlorine agent injection rate in the intermediate hypochlorite injection below the set value of the injection amount. (6) Although the solar radiation amount has not been measured in many water purification processes, since there is a correlation between the solar radiation amount and the air temperature, the change in the solar radiation amount can be regarded as the change in the air temperature. Therefore, when the air temperature rises, since the amount of chlorine agent volatilized and decomposed from the water to be treated tends to increase, it is preferable to control the chlorine agent injection rate in the intermediate hypochlorite injection above the set value of the injection amount. On the other hand, when the air temperature drops, since the amount of chlorine agent volatilized and decomposed from the water to be treated tends to decrease, it is preferable to control the chlorine agent injection rate in the intermediate hypochlorite injection below the set value of the injection amount.

[0033] As a result of the inventors' intensive studies based on the above findings (1) to (6) by the operator, it was found that by creating a regression equation in consideration of the following matters, the chlorine agent injection amount can be expressed by a simple equation and calculated. (a) The product of the chlorine agent concentration in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, (b) The product of the concentration of the component that consumes the chlorine agent pre - contained in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, (c) The flow rate of the water to be treated at the location where the chlorine agent is injected, (d) The product of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, (e) The product of the water surface area of the water tank that receives solar radiation after the chlorine agent is injected into the water to be treated and the air temperature

[0034] Here, (a) "chlorine agent concentration in the water to be treated" is a variable that should be considered when chlorine is injected, for example, in the pre-hypochlorite injection process prior to the intermediate hypochlorite injection process. The "flow rate of the water to be treated at the point where the chlorine agent is injected" is the inflow amount of the water to be treated flowing through the tank or pipe where the injection point is located. (b) "concentration of components that consume the chlorine agent already contained in the water to be treated" is a variable that should be considered when the water to be treated originally contains a large amount of components that consume the chlorine agent (disturbing substances). The "concentration of components that consume the chlorine agent already contained in the water to be treated" refers to the concentration of at least one of ammonia nitrogen, reducing inorganic substances, and reducing organic substances, preferably all of them. Examples of reducing inorganic substances include iron, manganese, and sulfides. Examples of reducing organic substances include humic substances (humic acid, fulvic acid), amino acids, and protein-like substances.

[0035] The "flow rate of the water to be treated at the point where the chlorine agent is injected" in (c) is the average value when there are multiple injection points of the chlorine agent. The "temperature of the water to be treated" in (d) typically means the temperature of the water in the tank in the water purification plant that is exposed to sunlight after the injection of the chlorine agent into the water to be treated, but the temperature of the raw water may also be used.

[0036] (e) "The water surface area of the tank exposed to sunlight after chlorine injection into the treated water" is a variable that takes into account the fact that the treated water is exposed to sunlight from above when it is stored in an open-top tank for a certain period of time after chlorine injection, thereby decomposing the chlorine in the treated water. "Water surface area" refers to the surface area of the water surface in the tank exposed to sunlight after chlorine injection. If there are multiple tanks, it refers to the total surface area of all tanks. Water surface area can be obtained from the water purification plant's design documents or calculated from satellite or aerial photographs taken using commonly available map applications. Regarding temperature, it is preferable to use the temperature near the tank exposed to sunlight after chlorine injection if available, but many water purification plants do not have thermometers. Temperature data from the nearest point to the water purification plant provided by the Japan Meteorological Agency can also be used.

[0037] Among these variables (a) to (e), the variables that should be most considered for calculating the chlorine agent injection amount are (c) and (e), more preferably (c), (d), (e), still more preferably (b), (c), (d), (e), and even more preferably (a) to (e).

[0038] (First chlorine agent injection amount calculation method using the first regression equation) The first chlorine agent injection amount calculation method includes a water surface area acquisition step of acquiring the water surface area of a water tank that receives sunlight after injecting a chlorine agent into the water to be treated, a temperature acquisition step of acquiring the air temperature near the water tank, using the product of the water surface area and the air temperature and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables, and using the first regression equation created by performing regression analysis using the past operation data set of the water purification plant with the chlorine agent injection amount as the target variable, to calculate the chlorine agent injection amount into the water to be treated.

[0039] In the water surface area acquisition step, as described above, the water surface area of the water tank that receives sunlight after chlorine agent injection is acquired from the design drawings of the water purification plant or a map application, etc. For example, when the coagulated sedimentation treated water after coagulation sedimentation treatment is supplied to the filtration tank and a chlorine agent such as hypochlorous acid is injected in a storage tank for chlorine agent injection in front of the filtration tank or in the pipe upstream of the filtration tank, the water surface area of the filtration tank with the upper part open to the outside is acquired as the water tank that receives sunlight. If another water tank after the filtration tank also receives sunlight, the water surface area of that water tank is also taken into account. In the temperature acquisition step, the air temperature data near the water tank that receives sunlight is acquired.

[0040] In the chlorine agent injection amount calculation process, a provisional first regression equation (y = Cx3 + Ex5) is defined, with the product of the water surface area and the temperature (x5) and the flow rate of the water to be treated at the location where the chlorine agent is injected (x3) as explanatory variables, and the chlorine agent injection amount (y) as the target variable. Then, multiple regression analysis is performed using the past operation data set of the water purification plant as a sample to obtain the coefficients (C, E) of the first regression equation, thereby determining the first regression equation. By inputting the product of the water surface area and the temperature (x5) and the flow rate of the water to be treated at the location where the chlorine agent is injected (x3) obtained from the measurement data of the water purification plant into the first regression equation with the determined coefficients, the chlorine agent injection amount (y) to be injected into the water to be treated can be calculated.

[0041] Generally, the larger the number of data in the past operation data set, the higher the calculation accuracy of the chlorine agent injection amount. Therefore, it is preferable to prepare and use a past operation data set of, for example, 3 years or more, more preferably 5 years or more, and even more preferably 10 years or more. Furthermore, it is preferable to align the time interval of the calculation of the chlorine agent injection amount and the time interval of the past operation data set. For example, if it is desired to calculate the chlorine agent injection amount at 5-minute intervals, regression analysis is performed using a past operation data set with data at 5-minute intervals. If it is desired to calculate the chlorine agent injection amount at 1-hour intervals, regression analysis is performed using a past operation data set with data at 1-hour intervals, enabling a more accurate calculation. The shorter the time interval of the calculation, the more data is required, and the higher the calculation accuracy.

[0042] In the past operation data set, there may appear a plurality of singular points indicating that some abnormality has occurred due to the influence of sudden water quality fluctuations caused by meteorological variations or the like. In such cases, the calculation accuracy of the chlorine agent injection amount can be improved by performing pre-processing of the operation data set to remove the singular points from the past operation data set.

[0043] The analysis method for multiple regression analysis is not particularly limited, and known methods can be used. As a simple example, for example, sample past operating data is input into spreadsheet software, regression analysis items provided in a data analysis tool provided in the spreadsheet software are selected, and arbitrary ranges are specified for the explanatory variables (x3, x5) and the objective coefficient (y). This makes it possible to more easily obtain the results of multiple regression analysis using spreadsheet software or the like, without using machine learning or the like. Of course, known analysis tools or machine learning or the like may be used instead of spreadsheet software or the like.

[0044] According to the method for calculating the amount of chlorine agent to be injected into the water to be treated using the first regression equation of the embodiment of the present invention, the amount of chlorine agent to be injected into the water to be treated can be calculated with a simple method and with a relatively high degree of accuracy. In particular, the method for calculating the amount of chlorine agent to be injected using the first regression equation is suitable for use in winter (January to March) when there is little sunshine and little temperature fluctuation.

[0045] (Second chlorine agent dosage calculation method using second regression equation) The second chlorine agent dosage calculation method is a technique for calculating the dosage of chlorine agent to be treated using a regression equation (second regression equation) created by performing regression analysis using past operation data sets of the water purification plant, with the product of water surface area and air temperature, the flow rate of the water to be treated at the point where the chlorine agent is injected, and the product of the water temperature and the flow rate of the water to be treated at the point where the chlorine agent is injected as explanatory variables instead of the first regression equation in the chlorine agent dosage calculation step, and the chlorine agent dosage as a response variable.The second chlorine agent dosage calculation method preferably further includes a water temperature acquisition step of acquiring the water temperature of the water to be treated before the chlorine agent dosage calculation step using the second regression equation.

[0046] In the water temperature acquisition step, the temperature of the water to be treated in the tank that is exposed to sunlight after the chlorine agent is injected is acquired. The water temperature is preferably measured using a water thermometer or the like placed in the tank, but if the water temperature is not measured, water temperature data from a nearby treatment tank or the like can be used.

[0047] In the chlorine agent injection amount calculation process, the flow rate of the water to be treated (x3) at the location where the chlorine agent is injected, the product (x4) of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, and the product (x5) of the water surface area and the air temperature are used as explanatory variables, and the chlorine agent injection amount (y) is used as the target variable to define the second regression equation (y = Cx3 + Dx4 + Ex5). Then, by performing multiple regression analysis using the past operation data set of the water purification plant as a sample and obtaining the coefficients (C, D, E) of the second regression equation, the second regression equation is determined. By inputting the flow rate of the water to be treated (x3) at the location where the chlorine agent is injected, the product (x4) of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, and the product (x5) of the water surface area and the air temperature, which are obtained from the measurement data of the water purification plant, into the second regression equation, the chlorine agent injection amount (y) to be injected into the water to be treated can be calculated.

[0048] According to the chlorine agent injection amount calculation method using the second regression equation according to the embodiment of the present invention, it can be performed with higher accuracy than when using the first regression equation. According to the chlorine agent injection amount calculation method using the second regression equation, since the water temperature of the water to be treated is also considered, the calculation of the chlorine agent injection amount can be suitably performed throughout the year regardless of the season, and the calculation accuracy is further improved in winter (January to March) when the sunshine amount is small and the temperature fluctuation is small.

[0049] (Third chlorine agent injection amount calculation method using the third regression equation) The third chlorine agent dosage calculation method is a technique for calculating the dosage of a chlorine agent to be treated using a regression equation (third regression equation) created by performing regression analysis using a past operating data set of the water purification plant, with the following explanatory variables instead of the first or second regression equation in the chlorine agent dosage calculation step: the product of the water surface area and air temperature, the flow rate of the water to be treated at the point where the chlorine agent is injected, the product of the water temperature and the flow rate of the water to be treated at the point where the chlorine agent is injected, and the product of the concentration of a component that consumes the chlorine agent already contained in the water to be treated and the flow rate of the water to be treated at the point where the chlorine agent is injected as the objective variable, and the chlorine agent dosage as the target variable.The third chlorine agent dosage calculation method preferably further includes a disturbance substance component concentration acquisition step for acquiring the concentration of the component that consumes the chlorine agent already contained in the water to be treated before the chlorine agent dosage calculation step using the third regression equation.

[0050] In the disturbance substance component concentration acquisition step, the concentrations of components (disturbance substances) that consume the chlorine agent and are already contained in the water to be treated are acquired. The concentrations of the disturbance substance components may be measured directly, but since this may take time, for example, water quality data of the raw water may be used.

[0051] In the chlorine dosage calculation step, a third regression equation (y = Bx2 + Cx3 + Dx4 + Ex5) is defined using (b) the product (x2) of the concentration of chlorine-consuming components already contained in the water being treated and the flow rate of the water being treated at the point where the chlorine is injected, (c) the flow rate (x3) of the water being treated at the point where the chlorine is injected, (d) the product (x4) of the water temperature and the flow rate of the water being treated at the point where the chlorine is injected, and (e) the product (x5) of the water surface area and the air temperature as explanatory variables, and the chlorine dosage amount (y) as the response variable. Then, a multiple regression analysis is performed using the water treatment plant's past operating data set as a sample to determine the coefficients (B, C, D, E) of the third regression equation, thereby determining the third regression equation. The dosage amount of chlorine to be injected into the water being treated can be calculated by inputting measurement data from the water treatment plant into the third regression equation.

[0052] If there are disturbing substances that consume chlorine, such as ammoniacal nitrogen, as components that consume the chlorine agent pre - contained in the water to be treated, as a result of the consumption of chlorine by the disturbing substances, a calculation result may be obtained in which the calculated value of the chlorine agent injection amount is less than the injection amount that should be originally injected. According to the chlorine agent injection amount calculation method using the third regression equation according to the embodiment of the present invention, by using the third regression equation obtained by performing multiple regression analysis taking into account the concentration of disturbing substances that consume chlorine, such as ammoniacal nitrogen, regardless of the properties of the water to be treated, a relatively accurate calculation of the chlorine agent injection amount can be performed.

[0053] (The Fourth Chlorine Agent Injection Amount Calculation Method Using the Fourth Regression Equation) In the fourth chlorine agent injection amount calculation method, in the above - mentioned chlorine agent injection amount calculation step, instead of the first to third regression equations, the product of the water surface area and the air temperature, the flow rate of the water to be treated at the location where the chlorine agent is injected, the product of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, the product of the concentration of the component that consumes the chlorine agent pre - contained in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, and the product of the chlorine agent concentration in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected are used as explanatory variables, and the chlorine agent injection amount is used as the target variable. The regression equation (the fourth regression equation (X)) prepared by performing regression analysis using the past operation data set of the water purification plant is used to calculate the chlorine agent injection amount into the water to be treated.

[0054] In the chlorine agent injection amount calculation process, the following are used as explanatory variables: (a) the product (x1) of the chlorine agent concentration in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected; (b) the product (x2) of the concentration of the component that consumes the chlorine agent pre - contained in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected; (c) the flow rate (x3) of the water to be treated at the location where the chlorine agent is injected; (d) the product (x4) of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected; (e) the product (x5) of the water surface area and the air temperature. With the chlorine agent injection amount (y) as the target variable, a fourth regression equation (y = Ax1 + Bx2 + Cx3 + Dx4 + Ex5) is defined. Then, by performing a multiple regression analysis using the past operation data set of the water treatment plant as a sample to obtain the coefficients (A, B, C, D, E) of the fourth regression equation, the fourth regression equation is determined. By inputting the measurement data of the water treatment plant into the fourth regression equation, the chlorine agent injection amount to be injected into the water to be treated can be calculated.

[0055] That is, in the fourth chlorine agent injection amount calculation method, in a water treatment plant having a process of injecting a chlorine agent into the water to be treated, · the product of the chlorine agent concentration in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, · the product of the concentration of the component that consumes the chlorine agent pre - contained in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, · the flow rate of the water to be treated at the location where the chlorine agent is injected, · the product of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, · the product of the water surface area of the water tank receiving solar radiation after the injection of the chlorine agent and the air temperature are used as explanatory variables, and through a regression analysis with the chlorine agent injection amount as the target variable, the following regression equation (X): [Chlorine agent injection amount] y = A [Chlorine agent concentration in the water to be treated × Flow rate of the water to be treated at the location where the chlorine agent is injected] + B [Concentration of the component that consumes the chlorine agent pre - contained in the water to be treated × Flow rate of the water to be treated at the location where the chlorine agent is injected] + C [Flow rate of the water to be treated at the location where the chlorine agent is injected] + D [Water temperature of the water to be treated × Flow rate of the water to be treated at the location where the chlorine agent is injected] + E [Water surface area of the water tank receiving solar radiation after the injection of the chlorine agent × Air temperature] ··· (X) It is produced. And it has a chlorine agent injection amount calculation step of calculating the amount of chlorine agent to be injected into the water to be treated using the regression equation (X).

[0056] A, B, C, D, and E are coefficients obtained by regression analysis, and each coefficient is · The water surface area unique to the water purification plant [m 2 , · The amount of chlorine agent injected into the water to be treated obtained in the past [g / hr], · The chlorine agent concentration of the water to be treated obtained in the past [g / m 3 , · The flow rate of the water to be treated at the location where the chlorine agent is injected obtained in the past [m 3 / hr], · The concentration of the component that consumes the chlorine agent pre - contained in the water to be treated obtained in the past [g / m 3 , · The water temperature of the water to be treated obtained in the past [°C], · The air temperature obtained in the past [°C], values derived by performing regression analysis using the data set of. The data obtained in the past can be appropriately extracted from the above - mentioned past operation data set.

[0057] Table 1 shows the units of the coefficients and variables of the regression equation defined by the regression equation (X). Note that the units of the coefficients A, B, C, D of the above - mentioned first to third regression equations and the variables are also the same as those in Table 1. Note that "chlorine agent injection amount" in Table 1 means the chlorine agent injection flow rate.

[0058]

Table 1

[0059] According to the fourth regression formula (X), in the first term on the right side, by further considering the amount of chlorine agent injected in the previous hypochlorite injection step that is injected before the middle hypochlorite injection step, the amount of chlorine agent injected in the middle hypochlorite injection step can be calculated. Therefore, since the fourth regression formula (X) can reflect the influence of the process of injecting the chlorine agent in the previous hypochlorite injection step into the regression formula, it is possible to estimate the amount of chlorine agent injected with higher accuracy compared to the first to third regression formulas.

[0060] Also, according to the method for calculating the amount of chlorine agent injection using the fourth regression formula (X), the process of estimating the supply rate, consumption rate, decomposition and dispersion rate of the chlorine agent can be formulated by the fourth regression formula (X). For the coefficients A, B, C, D, and E of this fourth regression formula (X), the past operation data of the water purification plant to be used and the scale of the water purification plant (the water surface area of the water tank that receives sunlight after chlorine agent injection) are taken into consideration in the calculation, so it can be used regardless of the scale and operating conditions of the water purification plant. Also, even in the same water purification plant, the water surface area of the water tank (for example, the rapid filtration tank) that receives sunlight may change due to renewal or inspection work, but the method according to the embodiment of the present invention can also cope with such changes in the operating status of the equipment. Thereby, it can be widely used in any water purification plant across the country. That is, in each water purification plant, the past operation data set of each water purification plant is input into, for example, spreadsheet software to obtain the coefficients of the fourth regression formula (X). Then, by simply substituting various information (measurement values) such as the water surface area, volume, air temperature, and water temperature unique to the water purification plant obtained in real time into the fourth regression formula (X), the amount of chlorine agent injected into the water to be treated can be calculated, thus reducing the burden on the operators and enabling a simpler calculation of the amount of chlorine agent injection.

[0061] (Chlorine agent injection amount calculation device) An example of a chlorine agent injection amount calculation device 10 that calculates the injection amount of the chlorine agent to be injected into the water to be treated is shown in FIG. 2. As shown in FIG. 2, the chlorine agent injection amount calculation device 10 according to the embodiment of the present invention can be configured by a general-purpose computer or the like including a control unit 100 that controls various arithmetic processes, a storage device 140 that stores information necessary for the calculation, an input unit 150 that receives various data, and an output unit 160 that can output the calculation result by the control unit 100.

[0062] The control unit 100 includes a data acquisition unit 110, a regression equation creation unit 120, and a chlorine agent injection amount calculation unit 130. The data acquisition unit 110 includes a water area acquisition unit 101, an air temperature acquisition unit 102, a water temperature acquisition unit 103, a disturbance substance concentration acquisition unit 104, and a chlorine concentration acquisition unit 105.

[0063] The water area acquisition unit 101 acquires the water area of the tank that will be exposed to sunlight after the injection of chlorine into the water to be treated from the design drawings or map information of the water purification plant, for example. The water area acquisition unit 101 can measure the water area of the tank from, for example, the design drawings or map information of the water purification plant input via the input unit 150. The temperature acquisition unit 102 acquires the air temperature near the tank that will be exposed to sunlight after the injection of chlorine into the water to be treated. If a thermometer or other device is installed at the water purification plant, the temperature measurement value of the thermometer may be used as the air temperature near the tank. However, if the water purification plant or other device does not have equipment for measuring air temperature, temperature data distributed by the Japan Meteorological Agency or the like may be used. In this case, the air temperature acquisition unit 102 acquires the air temperature data at the point closest to the water purification plant, distributed by the Japan Meteorological Agency, via the input unit 150. The water temperature acquisition unit 103 acquires the water temperature of the tank that will be exposed to sunlight after the injection of chlorine into the water to be treated. The disturbance substance concentration acquisition unit 104 acquires the concentration of disturbance substances that consume chlorine in the water to be treated. The chlorine concentration acquisition unit 105 acquires the chlorine concentration previously contained in the water to be treated. For example, the chlorine concentration acquisition unit 105 calculates the chlorine concentration of the water to be treated before the intermediate hypochlorite injection treatment from the chlorine agent concentration and flow rate injected by a pre-hypochlorite injection step or the like before the intermediate hypochlorite injection treatment.

[0064] The regression equation creation unit 120 creates regression equations (first to fourth regression equations) for calculating the amount of chlorine agent to be injected by performing regression analysis using past operation data sets of the water purification plant, including at least the product of the water surface area of the tank that receives solar radiation after the injection of chlorine agent into the water to be treated and the air temperature, and the flow rate of the water to be treated at the point where the chlorine agent is injected as explanatory variables, and using the amount of chlorine agent to be injected as a response variable.The chlorine agent injection amount calculation unit 130 calculates the amount of chlorine agent to be injected into the water to be treated using measurement data from the water purification plant.

[0065] According to the chlorine agent dosage calculation device 10 of the embodiment of the present invention, using past operating data of the water purification plant to be measured, regression analysis is performed with predetermined variables as explanatory variables and the chlorine agent dosage as the response variable to create first to fourth regression equations. By inputting measurement data such as the flow rate of water to be treated, which is generally measured at water purification plants, and easily available data such as temperature into these first to fourth regression equations, the chlorine agent dosage can be easily calculated without using variables that are difficult to measure, such as solar radiation and ultraviolet data.

[0066] (Water treatment system) As shown in FIG. 3, an example of a water treatment system according to an embodiment of the present invention includes a chlorine agent injection device 2 that injects a chlorine agent, a water tank 1 that stores the water to be treated into which the chlorine agent has been injected, and a chlorine agent injection control device 1000 that includes a chlorine agent injection amount calculation unit 1100 that calculates the amount of chlorine agent to be injected by the chlorine agent injection device 2 into the water to be treated.

[0067] Various tanks in a water purification plant can be used as the water tank 1. For example, when a chlorine agent is supplied to the coagulation-sedimentation-treated water in the intermediate hypochlorite injection step, a filter basin, which is a typical destination of the coagulation-sedimentation-treated water, can be used. The configuration of the chlorine agent injection device 2 is not particularly limited. The chlorine agent injected by the chlorine agent injection device 2 is also not particularly limited, but sodium hypochlorite is generally used.

[0068] The chlorine agent injection control device 1000 is a device for automatically controlling the injection of a chlorine agent by the chlorine agent injector 2, and can be configured, for example, by a general-purpose computer, etc. The chlorine agent injection control device 1000 includes a flow rate, water temperature, and air temperature data acquisition unit 1001, a chlorine agent injection amount data acquisition unit 1002, a set value manual input unit 1003, a chlorine agent injection amount calculation unit 1100, a chlorine agent injection amount output unit 1004, and a memory device 1400.

[0069] The flow rate, water temperature, and air temperature data acquisition unit 1001 acquires measurement data from the water purification plant, such as the flow rate of the water to be treated at the point where chlorine is injected, the water temperature in tank 1, and the air temperature near tank 1. The flow rate, water temperature, and air temperature data acquisition unit 1001 can sequentially acquire these data obtained at the water purification plant. The chlorine agent injection amount data acquisition unit 1002 can sequentially acquire data on the injection amount of chlorine agent injected by the chlorine agent injection device 2. The storage device 1400 stores various data acquired by the flow rate, water temperature, and air temperature data acquisition unit 1001 and the chlorine agent injection amount data acquisition unit 1002. The set value manual input unit 1003 accepts set values for the chlorine agent injection device 2 manually input by an operator or the like, and outputs the set values to the chlorine agent injection amount output unit 1004. The set value manual input unit 1003 also allows the operator to manually control the chlorine agent injection amount.

[0070] The chlorine agent dosage calculation unit 1100 is a calculation module that calculates the dosage of chlorine agent to be injected into the water to be treated using the sequential data acquired by the flow rate, water temperature, and air temperature data acquisition unit 1001 and pre-stored analytical formulas, etc. The chlorine agent dosage calculation unit 1100 stores the above-mentioned first to fourth regression formulas that are determined in advance using past operation data sets, and is configured to be able to calculate the dosage of chlorine agent using any of the above-mentioned first to fourth regression formulas. The chlorine agent dosage output unit 1004 outputs to the chlorine agent dosing device 2 the chlorine agent dosing rate at which the chlorine agent dosing device 2 injects a chlorine agent into the water to be treated, based on the calculation result of the chlorine agent dosage calculation unit 1100.

[0071] In a water treatment system using the chlorine agent injection control device 1000 according to the embodiment of the present invention, the chlorine agent injection amount calculation unit 1100 automatically calculates the chlorine agent injection amount, which has conventionally been manually adjusted by an operator, using the first to fourth regression equations, and outputs the calculated amount to the chlorine agent injection device 2. As a result, the chlorine agent injection amount can be automatically optimized without relying on the operator's empirical rule. Furthermore, according to this embodiment, the chlorine agent injection amount can be easily optimized simply by modifying the calculation algorithm (analysis formula) of the chlorine agent injection amount calculation unit 1100 of the chlorine agent injection control device 1000 installed in an existing water purification plant. Therefore, there is no need to install new equipment for optimizing the chlorine agent injection amount, which also leads to the miniaturization and simplification of the water treatment system.

[0072] Figure 4 shows a modified example of the water treatment system according to the embodiment of the present invention. The water treatment system shown in Figure 4 differs from the water treatment system shown in Figure 3 in that it further includes the chlorine agent dosage calculation device 10 of Figure 2. In the example of Figure 3, the chlorine agent dosage calculation unit 1100 calculates the chlorine agent dosage rate based on the first to fourth regression equations optimized in advance and the sequential data acquired from the flow rate, water temperature, and air temperature data acquisition unit 1001. Therefore, the coefficients (A, B, C, D, E) of the first to fourth regression equations basically use the same analytical formula until new first to fourth regression equations are input to the chlorine agent dosage calculation unit 1100.

[0073] In contrast, according to the water treatment system shown in Fig. 4, the chlorine agent dosage calculation device 10 sequentially obtains new first to fourth regression equations that take into consideration not only past operating data but also sequential data acquired from the flow rate, water temperature, and air temperature data acquisition unit 1001. Then, the chlorine agent dosage calculation device 10 inputs the new first to fourth regression equations to the chlorine agent dosage calculation unit 1100. The chlorine agent dosage calculation unit 1100 receives input of the calculation results of the first to fourth regression equations based on the latest data that is sequentially input at a predetermined timing, and can calculate the chlorine agent dosage based on the new first to fourth regression equations, so that the chlorine agent dosage can always be calculated based on the latest data.

[0074] Although the present invention has been described with reference to the above-described embodiments, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. The present disclosure is not limited to the above-described embodiments, and components can be combined and modified to be embodied within the scope of the gist of the present disclosure.

[0075] (Fifth chlorine agent dosage calculation method using fifth regression equation) The fifth chlorine agent injection method described below is a technique for calculating the amount of chlorine agent to be injected into the water to be treated by using a regression equation (fifth regression equation) created by performing regression analysis using past operating data sets of the water purification plant, with the flow rate of the water to be treated at the point where the chlorine agent is injected and the product of the water temperature and the flow rate of the water to be treated at the point where the chlorine agent is injected as explanatory variables instead of the first to fourth regression equations in the chlorine agent injection amount calculation step described above, and the chlorine agent injection amount as the target variable.

[0076] In the chlorine agent dosage calculation step, a fifth regression equation (y = Cx3 + Dx4) is defined using (c) the flow rate of the treated water at the chlorine agent injection point (x3) and (d) the product (x4) of the water temperature and the flow rate of the treated water at the chlorine agent injection point as explanatory variables, and the chlorine agent dosage amount (y) as the response variable. Then, a multiple regression analysis is performed using the water treatment plant's past operating data set as a sample to determine the coefficients (C, D) to determine the fifth regression equation. The dosage amount (y) of chlorine agent to be injected into the treated water can be calculated by inputting (c) the flow rate of the treated water at the chlorine agent injection point (x3) and (d) the product (x4) of the water temperature and the flow rate of the treated water at the chlorine agent injection point, which are obtained from the water treatment plant's measurement data, into the fifth regression equation.

[0077] According to the fifth chlorine agent dosage calculation method using the fifth regression equation, the dosage of chlorine agent to be injected into the treated water can be calculated in a simple manner, as with the chlorine agent dosage calculation methods using the first to fourth regression equations, and it is possible to reduce the burden on the operator in charge of management. [Example]

[0078] Examples of the present invention are given below, but these examples are provided for a better understanding of the present invention and its advantages, and are not intended to limit the invention.

[0079] (Example 1: Calculation by the first regression equation) At Water Treatment Plant A, which has pre-, intermediate, and post-secondary chlorine injection processes, a regression analysis was carried out using spreadsheet software with a historical operational dataset from April 1, 2018 to March 31, 2022, regarding chlorine injection in the intermediate secondary chlorine injection process. The operational dataset included the intermediate secondary chlorine injection rate (L / h), which indicates the amount of chlorine injected in the intermediate secondary chlorine injection process at Water Treatment Plant A, the pre-secondary chlorine injection rate (L / h), which indicates the amount of chlorine injected in the pre-secondary chlorine injection process, and the inflow treated water volume (m ), which indicates the flow rate of the treated water at the point where chlorine is injected. 3 / h), the temperature of the treated water (℃) and the amount of inflowing treated water (m 3 / h) product (℃ m 3 / h) and the product of the temperature (℃) and the water surface area (℃ m 3 / h), disturbance substance concentration (ammonia nitrogen) (mg / L), the product of disturbance substance concentration and inflow treatment water volume (g / h), raw water temperature (℃), and air temperature (℃) were used.

[0080] In Example 1, a first regression equation (y = Cx3 + Ex5) was defined using the operational dataset, with (e) the product of water surface area and temperature (x5) and (c) the flow rate of the water to be treated at the point where chlorine is injected (x3) as explanatory variables, and the chlorine injection rate (y) as the objective variable. Multiple regression analysis was performed using the past operational dataset of Water Purification Plant A as a sample to determine the coefficients (C, E) of the first regression equation, and the first regression equation was determined. The operational dataset was collected every hour. The coefficient C of the first regression equation was 0.0058, and the coefficient E was 0.00018.

[0081] Operational data from Water Purification Plant A from January 1, 2022 to September 27, 2022 was used as verification data and substituted into the first regression equation, and the calculated value (dotted line) was compared with the actual operating value (solid line). A portion of the comparison results (August 4 to August 8, 2022) is shown in Figure 5. The vertical axis of Figure 5 represents the amount of chlorine agent injected, and the horizontal axis represents time. As shown in Figure 5, by using the first regression equation, it was possible to calculate a chlorine agent injection amount that was close to the actual operating value, even in August, when temperatures were high.

[0082] (Example 2: Calculation by the second regression equation) In Example 2, similar to Example 1, a regression analysis was performed using a spreadsheet software on the historical operational data set from April 1, 2018 to March 31, 2022, regarding the chlorine agent injection in the intermediate hypochlorite injection process at the A water purification plant. In Example 2, from the operational data set, (c) the flow rate of the treated water at the point where the chlorine agent is injected (x3), (d) the product of the water temperature and the flow rate of the treated water at the point where the chlorine agent is injected (x4), and (e) the product of the water surface area and the air temperature (x5) were used as explanatory variables, and the chlorine agent injection amount (y) was used as the objective variable. A multiple regression analysis was then performed using the historical operational data set of the A water purification plant as a sample to determine the coefficients (C, D, E) of the second regression equation, and the second regression equation was determined. The operational data set was taken every hour. The coefficient C of the second regression equation was 0.0045, the coefficient D was 0.00009, and the coefficient E was 0.00014.

[0083] Operational data from January 1, 2022 to September 27, 2022 at Water Purification Plant A was substituted into the second regression equation as verification data, and the calculated value (dotted line) was compared with the actual operating value (solid line). A portion of the comparison results (August 4 to August 8, 2022) is shown in Figure 6. The vertical axis of Figure 6 represents the chlorine agent dosage amount, and the horizontal axis represents time. As shown in Figure 6, by using the second regression equation, the calculated value can be brought closer to the actual operating value than in Example 1, and it was found that the chlorine agent dosage amount can also be calculated in Example 2. The results of Example 2 revealed that, with regard to the chlorine dosage amount, the influence of the product of the water temperature of the treated water and the flow rate of the treated water at the point where the chlorine agent is injected is greater than the influence of the product of the water surface area and air temperature.

[0084] (Example 3: Calculation by the third regression equation) For water to be treated containing 0.10 mg / L of ammonia nitrogen in March 2022, the second regression equation determined in Example 2 was used, and the operational data for March 2022 at Water Purification Plant A was substituted into the second regression equation as verification data to calculate the chlorine dosage. Figure 7 shows the actual operating values (solid line) and calculated values (dotted line) from March 4 to March 8, 2022. As shown in Figure 7, the actual operating values and calculated values showed similar trends in the increase and decrease in the chlorine dosage, but the calculated results showed that the chlorine dosage was lower during the calculation than the actual operating values.

[0085] Therefore, in Example 3, from the operating data set, (b) the product (x2) of the concentration of the component that consumes the chlorine agent already contained in the treated water and the flow rate of the treated water at the point where the chlorine agent is injected, (c) the flow rate (x3) of the treated water at the point where the chlorine agent is injected, (d) the product (x4) of the water temperature and the flow rate of the treated water at the point where the chlorine agent is injected, and (e) the product (x5) of the water surface area and the air temperature were used as explanatory variables, and the chlorine agent injection amount (y) was used as the objective variable. A multiple regression analysis was performed using the past operating data set of the A water purification plant as a sample to determine the coefficients (B, C, D, E) of the third regression equation, and the third regression equation was determined. The coefficient B of the third regression equation was 0.035, the coefficient C was 0.0038, the coefficient D was 0.00018, and the coefficient E was 0.00008. A portion of the comparison results (March 4th to March 8th, 2022) is shown in Figure 8. As shown in Figure 8, when the water to be treated contains disturbing substances such as ammonia nitrogen, the calculated value becomes closer to the actual operating value by using the third regression equation.

[0086] (Example 4: Calculation by the fourth regression equation) In Example 4, as in Examples 1 to 3, a regression analysis was performed using a spreadsheet software on past operating data sets from April 1, 2018 to March 31, 2022, regarding the chlorine agent injection in the intermediate hypochlorite injection process at the A water purification plant. In Example 4, from the operating data set, (a) the product (x1) of the chlorine agent concentration in the treated water and the flow rate of the treated water at the point where the chlorine agent is injected, (b) the product (x2) of the concentration of the component that consumes the chlorine agent already contained in the treated water and the flow rate of the treated water at the point where the chlorine agent is injected, (c) the flow rate of the treated water at the point where the chlorine agent is injected (x3), (d) the product (x4) of the water temperature of the treated water and the flow rate of the treated water at the point where the chlorine agent is injected, and (e) the product (x5) of the water surface area and the air temperature were used as explanatory variables, and the chlorine agent injection amount (y) was used as the objective variable. A fourth regression equation (y = Ax1 + Bx2 + Cx3 + Dx4 + Ex5) was defined. Then, a multiple regression analysis was performed using the past operating data set of Water Purification Plant A as a sample to find the coefficients (A, B, C, D, E) of the fourth regression equation, and the fourth regression equation was determined. The coefficient A of the fourth regression equation was -0.44, coefficient B was 0.042, coefficient C was 0.0042, coefficient D was 0.00017, and coefficient E was 0.00008.

[0087] Operational data from January 1, 2022 to September 27, 2022 at Water Treatment Plant A was used as verification data and substituted into the fourth regression equation, and the calculated value (dotted line) was compared with the actual operating value (solid line). A portion of the comparison results (August 4 to August 8, 2022) is shown in Figure 9. It can be seen that by taking into account all of variables (a) to (e) in the fourth regression equation, it is possible to calculate the amount of chlorine agent to be dosed with greater accuracy.

[0088] (Example 5: Calculation by the fifth regression equation) In Example 5, similar to the first to fourth examples, regression analysis was performed using spreadsheet software with the past operation data set from April 1, 2018 to March 31, 2022 regarding the chlorine agent injection in the intermediate hypochlorite injection process at Water Purification Plant A. In Example 5, from the operation data set, (c) the flow rate of the water to be treated (x3) at the location where the chlorine agent is injected and (d) the product (x4) of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected were used as explanatory variables, and the chlorine agent injection amount (y) was used as the objective variable to define the fifth regression equation (y = Cx3 + Dx4). Then, multiple regression analysis was performed using the past operation data set of Water Purification Plant A as a sample to obtain the coefficients (C, D) of the fifth regression equation and determine the fifth regression equation. The operation data set was taken every hour. The coefficient C of the fifth regression equation was 0.0044, and the coefficient D was 0.00021.

[0089] The operation data from January 1, 2022 to September 27, 2022 at Water Purification Plant A was substituted into the fifth regression equation as verification data, and the calculated values (dotted line) and the actual operation values (solid line) were compared. A part of the comparison results (from August 4 to August 8, 2022) is shown in FIG. 10. The vertical axis in FIG. 10 represents the chlorine agent injection amount, and the horizontal axis represents time. As shown in FIG. 10, by using the fifth regression equation, the calculated values can be made closer to the actual operation values, and it was found that the chlorine agent injection amount can also be calculated in Example 5.

[0090] (Example 6: Calculation of Chlorine Injection Amount by Water Purification Plant B (System 1)) In Example 6, regression analysis of the fourth regression equation was performed using spreadsheet software with the past operation data set from March 1, 2018 to January 31, 2023 regarding the chlorine agent injection in the intermediate hypochlorite injection process at Water Purification Plant B (System 1), which is different from Water Purification Plant A, to obtain the coefficients (A, B, C, D, E), and the coefficients of the fourth regression equation were determined using the operation data from March 1, 2018 to January 31, 2023 as verification data. A part of the comparison results (March 2018) is shown in FIG. 11. In Example 6, since it was derived without using the foreign substance data, the coefficient B does not function substantially, but there was not much divergence tendency between the actual operation values and the calculated values even at Water Purification Plant B (System 1), which is different from Water Purification Plant A.

[0091] (Example 7: Chlorine Injection Rate Calculation by Water Purification Plant B (System 2)) In Example 7, regression analysis of the fourth regression equation was performed using spreadsheet software with the past operation data set from March 1, 2018 to January 31, 2023 regarding the chlorine agent injection in the intermediate hypochlorite injection process at Water Purification Plant B (System 2) to obtain the coefficients (A, B, C, D, E), and the coefficients of the fourth regression equation were determined using the operation data from March 1 to March 31, 2018 as verification data. A part of the comparison results (March 2018) is shown in Fig. 12. In Example 7, since the coefficient B was derived without using the foreign substance data, it did not substantially function, but even in Water Purification Plant B (System 2) different from Water Purification Plant A, the deviation tendency between the actual operation value and the calculated value was not observed much.

[0092] (Example 8: Analysis of the Determination Coefficient (R2) between the Actual Operation Value and the Calculated Value) For the existing water purification treatment processes (Water Purification Plant A, Water Purification Plant B (System 1), Water Purification Plant B (System 2)), a fourth regression equation for calculating the chlorine agent injection rate at one-hour intervals was created, and the comparison and evaluation between the calculated value obtained by the fourth regression equation and the actual operation value were performed. Table 2 shows the results of calculating the determination coefficient (R2) using the operation data from 2018 to 2021 as verification data.

[0093]

Table 2

[0094] For all of Water Purification Plants A, B (System 1), and B (System 2), the determination coefficient R2 was as high as 0.859 to 0.926. Thus, according to the chlorine agent injection rate calculation method according to the embodiment of the present invention, a calculation result of the chlorine agent injection rate having substantially the same tendency as the tacit knowledge of a skilled operator who manually controls the chlorine agent injection rate can be obtained. Thereby, the chlorine agent injection rate calculation method according to the embodiment of the present invention is very useful in that an appropriate chlorine agent injection rate can always be set without relying on the operator's rule of thumb.

[0095] (Example 8: Calculation Comparison Considering Changes in the Number of Water Tanks due to Equipment Updating and Inspection Work) In the case where the number of tanks in a water purification plant changes due to equipment renewal or inspection work, it was verified whether the chlorine agent dosage calculation method according to the embodiment of the present invention can properly calculate the dosage of chlorine agent to be injected into the water to be treated. The verification procedure was as follows. (i) Using the operating data set (actual values) from December 2nd to December 3rd, 2024 regarding the injection of chlorine into tanks in the intermediate hypochlorite injection process at Water Purification Plant A, where the number of tanks exposed to sunlight was set to 20, a regression analysis of the fourth regression equation was performed using spreadsheet software, and the coefficients of the fourth regression equation (A, B, C, D, E) were calculated. (b) Using the operating data set (actual values) for December 2nd to December 3rd, 2022 and December 2nd to December 3rd, 2023 regarding the injection of chlorine into tanks in the intermediate hypochlorite injection process at Water Purification Plant A, where the number of tanks exposed to sunlight was set to 24, a regression analysis of the fourth regression equation was performed using spreadsheet software, and the coefficients (A, B, C, D, E) of the fourth regression equation were calculated. (c) Using the coefficients calculated in (a) above, the number of tanks receiving solar radiation was set to "20," and the operating data set (actual values) from December 2nd to December 3rd, 2024 was substituted into the fourth regression equation as verification data to calculate the amount of chlorine injection. (iv) Using the coefficients calculated in (b) above, the number of tanks receiving solar radiation was set to "24," and the operating data set (actual values) from December 2nd to December 3rd, 2024 was substituted into the fourth regression equation as verification data to calculate the amount of chlorine injection.

[0096] Figure 13 shows the comparison results between the actual values from December 2nd to December 3rd, 2024 and the calculated values in (c) and (d) above. In Figure 13, "Actual Value (Number of Tanks: 20)" indicates the actual value from December 2nd to December 3rd, 2024, when the number of tanks receiving solar radiation was set to "20." "Calculated Value (Number of Tanks: 20)" corresponds to the calculation in (c) above and indicates the calculated value obtained by setting the number of tanks receiving solar radiation to "20" and using the operating data set from December 2nd to December 3rd, 2024, as verification data. "Calculated Value (Number of Tanks: 24)" corresponds to the calculation in (d) above and indicates the calculated value obtained by setting the number of tanks receiving solar radiation to "24" and using the operating data set from December 2nd to December 3rd, 2024, as verification data.

[0097] As shown in Fig. 13, with the number of water tanks being 20, the "calculated value (number of water tanks 20)" using coefficients A to E obtained from the regression calculation using the operation data set from December 2, 2024 to December 3, 2024 was in good agreement with the "actual value (number of water tanks 20)". When the number of water tanks was 24, the "calculated value (number of water tanks 24)" calculated using the coefficients A to E obtained from the regression calculation using the data from December 2, 2022 to December 3, 2022 and from December 2, 2023 to December 3, 2023 with the operation data set from December 2, 2024 to December 3, 2024 as verification data did not match the "actual value (number of water tanks 20)", but as the number of water tanks was larger, the increase in the calculated value of the chlorine injection amount was also reflected. That is, according to the calculation method according to the embodiment of the present invention, since the scale of the water purification plant (the water surface area of the water tanks receiving solar radiation after the injection of the chlorine agent) is taken into account, even when there is a change in the water surface area of the water tanks receiving solar radiation (for example, rapid filtration tanks) for renewal or inspection work, the chlorine injection amount can be appropriately calculated using the fourth regression formula.

Explanation of Signs

[0098] 1: Water tank 2: Chlorine agent injection device 10: Chlorine agent injection amount calculation device 100: Control unit 101: Water surface area acquisition unit 102: Air temperature acquisition unit 103: Water temperature acquisition unit 104: Concentration of foreign substances acquisition unit 105: Chlorine concentration acquisition unit 110: Data acquisition unit 120: Regression formula creation unit 130: Chlorine agent injection amount calculation unit 140: Storage device 150: Input unit 160: Output unit 1000: Chlorine agent injection control device 1001: Air temperature data acquisition unit 1002: Chlorine agent injection amount data acquisition unit 1003: Set value manual input unit 1004: Chlorine agent injection amount output unit 1100: Chlorine agent injection amount calculation unit 1400: Storage device

Claims

1. In a water purification plant having a step of injecting a chlorine agent into the water to be treated, a water surface area acquisition step of acquiring the water surface area of a water tank that receives sunlight after the injection of the chlorine agent into the water to be treated; an air temperature acquisition step of acquiring the air temperature in the vicinity of the water tank; Using the product of the water surface area and the air temperature and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables, and the chlorine agent injection amount as the target variable, a regression equation prepared by performing regression analysis using the past operation data set of the water purification plant is used to calculate the chlorine agent injection amount into the water to be treated. A chlorine agent injection amount calculation step A chlorine agent injection amount calculation method having the above steps.

2. The chlorine agent injection amount calculation step is Using the product of the water surface area and the air temperature, the flow rate of the water to be treated at the location where the chlorine agent is injected, the water temperature of the water to be treated, and the product of the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables, and the chlorine agent injection amount as the target variable, a regression equation prepared by performing regression analysis using the past operation data set of the water purification plant is used to calculate the chlorine agent injection amount into the water to be treated. The chlorine agent injection amount calculation method according to claim 1, including

3. The chlorine agent injection amount calculation step is Using the product of the water surface area and the air temperature, the flow rate of the water to be treated at the location where the chlorine agent is injected, the water temperature of the water to be treated, and the product of the flow rate of the water to be treated at the location where the chlorine agent is injected, and the product of the concentration of the component that consumes the chlorine agent pre - contained in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables, and the chlorine agent injection amount as the target variable, a regression equation prepared by performing regression analysis using the past operation data set of the water purification plant is used to calculate the chlorine agent injection amount into the water to be treated. The chlorine agent injection amount calculation method according to claim 1, including

4. The chlorine agent injection amount calculation step is Using, as explanatory variables, the product of the water surface area and the air temperature, the flow rate of the water to be treated at the location where the chlorine agent is injected, the product of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, the product of the concentration of the component that consumes the chlorine agent pre - contained in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, and the product of the chlorine agent concentration in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, and using the chlorine agent injection amount as the objective variable, performing a regression analysis using the past operation data set of the water purification plant, and calculating the chlorine agent injection amount into the water to be treated by using the regression equation thus produced. The chlorine agent injection amount calculation method according to claim 1.

5. The chlorine agent injection amount calculation step is Using, as explanatory variables, the flow rate of the water to be treated at the location where the chlorine agent is injected and the product of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, and using the chlorine agent injection amount as the objective variable, performing a regression analysis using the past operation data set of the water purification plant, and calculating the chlorine agent injection amount into the water to be treated by using the regression equation thus produced. The chlorine agent injection amount calculation method according to claim 1.

6. In a water purification plant having a step of injecting a chlorine agent into water to be treated, - The product of the chlorine agent concentration in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, - The product of the concentration of the component that consumes the chlorine agent pre - contained in the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, - The flow rate of the water to be treated at the location where the chlorine agent is injected, - The product of the water temperature of the water to be treated and the flow rate of the water to be treated at the location where the chlorine agent is injected, - The product of the water surface area and the air temperature of the water tank that receives solar radiation after the injection of the chlorine agent As explanatory variables, and by regression analysis with the chlorine agent injection amount as the objective variable, The following regression equation (X); [Chlorine agent injection amount]=A[Chlorine agent concentration in the water to be treated×Flow rate of the water to be treated at the location where the chlorine agent is injected]+B[Concentration of the component that consumes the chlorine agent pre - contained in the water to be treated×Flow rate of the water to be treated at the location where the chlorine agent is injected]+C[Flow rate of the water to be treated at the location where the chlorine agent is injected]+D[Water temperature of the water to be treated×Flow rate of the water to be treated at the location where the chlorine agent is injected]+E[Water surface area of the water tank that receives solar radiation after the injection of the chlorine agent×Air temperature]...(X) A chlorine agent injection amount calculation method characterized by having a chlorine agent injection amount calculation step of producing the regression equation (X) and calculating the chlorine agent injection amount into the water to be treated by using the regression equation (X). (Here, A, B, C, D, and E are coefficients, and the coefficients are · the water surface area specific to the water purification plant, · the amount of chlorine agent injected into the water to be treated obtained in the past, · the chlorine agent concentration of the water to be treated obtained in the past, · the flow rate of the water to be treated at the location where the chlorine agent is injected obtained in the past, · the concentration of components that consume the chlorine agent pre - contained in the water to be treated obtained in the past, · the water temperature of the water to be treated obtained in the past, · the air temperature obtained in the past, values derived by performing regression analysis using a dataset of these.) **Claim 7** The chlorine agent injection amount calculation method according to any one of claims 3, 4, or 6, wherein the concentration of components that consume the chlorine agent pre - contained in the water to be treated includes at least one of the concentrations of ammonia - nitrogen, reducing inorganic substances, and reducing organic substances. **Claim 8** A chlorine agent injection amount calculation device for calculating the injection amount of a chlorine agent to be injected into water to be treated, a water surface area acquisition unit that acquires the water surface area of a water tank that receives sunlight after the chlorine agent is injected into the water to be treated; an air temperature acquisition unit that acquires the air temperature in the vicinity of the water tank; a storage device that stores a dataset of past operation data of a water purification plant equipped with the water tank; a regression equation creation unit that creates a regression equation by performing regression analysis using the product of the water surface area and the air temperature and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables and the chlorine agent injection amount as the objective variable, using the dataset of past operation data of the water purification plant; and a chlorine agent injection amount calculation unit that calculates the injection amount of the chlorine agent to be injected into the water to be treated using the regression equation. A chlorine agent injection amount calculation device comprising the above. **Claim 9** A chlorine agent injection device that injects a chlorine agent into water to be treated, a water tank that stores the water to be treated into which the chlorine agent has been injected, a chlorine agent injection control device comprising a chlorine agent injection amount calculation unit that creates a regression equation by performing regression analysis using the product of the water surface area, which is the area of the water tank that receives sunlight, and the air temperature in the vicinity of the water tank and the flow rate of the water to be treated at the location where the chlorine agent is injected as explanatory variables and the chlorine agent injection amount of the chlorine agent injection device as the objective variable, using a dataset of past operation data of a water purification plant equipped with the water tank, and calculates the chlorine agent injection amount that the chlorine agent injection device injects into the water to be treated based on the regression equation. A water treatment system comprising the above.

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