WO2019212004A1

WO2019212004A1 - Flocculant injection control device, flocculant injection control method, and computer program

Info

Publication number: WO2019212004A1
Application number: PCT/JP2019/017187
Authority: WO
Inventors: 良一有村; 諒難波; 卓毛受; 太黒川; 雄横山
Original assignee: 株式会社東芝; 東芝インフラシステムズ株式会社
Priority date: 2018-05-01
Filing date: 2019-04-23
Publication date: 2019-11-07
Also published as: JP7179486B2; JP2019193916A

Abstract

The flocculant injection control device according to the present invention has a flocculant injection control unit and a control target value determination unit. The flocculant injection control unit performs feedback control using, as a control quantity, an aggregation state of flocks in mixed water, which is to-be-treated water in which a flocculant has been injected, and using, as an operational quantity, an amount of the flocculant injected into the to-be-treated water. The control target value determination unit determines a target value of the control quantity used for the feedback control on the basis of the turbidity of a sedimentation basin in which the flocks in the mixed water are sedimented and a target turbidity value.

Description

Flocculant injection control device, flocculant injection control method, and computer program

Embodiments of the present invention relate to a flocculant injection control device, a flocculant injection control method, and a computer program.

In the water treatment plant, a flocculant injection control device that controls the injection amount of the flocculant into the raw water to be treated is used. However, when the control by the conventional flocculant injection control device cannot properly control the injection amount of the flocculant according to the quality of raw water and the needs of the operator, the water quality after treatment is not stable was there. In such a case, more than necessary flocculant is injected to stabilize the water quality, which may increase the operating cost.

Japanese Patent No. 3522650 Japanese Patent No. 5925005 Japanese Patent No. 5131005 Japanese Patent No. 5636263 Japanese Patent No. 4366244 Japanese Patent No. 6074340

The problem to be solved by the present invention is to provide a flocculant injection control device, a flocculant injection control method, and a computer program that can more appropriately control the injection amount of the flocculant.

The flocculant injection control device of the embodiment includes a flocculant injection control unit and a control target value determination unit. The flocculant injection control unit performs feedback control using the floc aggregation state in the water to be treated, into which the flocculant is injected, as the control amount, and the injection amount of the flocculant into the water to be treated as the operation amount. The control target value determination unit determines the target value of the control amount in the feedback control based on the turbidity of the sedimentation basin that precipitates flocs in the mixed water and the target value.

The figure which shows the specific example of a structure of the water treatment plant in 1st Embodiment. The flowchart which shows the flow of the process which controls the coagulant injection amount with which the coagulant injection control apparatus in 1st Embodiment is inject | poured into a rapid mixing basin. The figure explaining the example of the conventional control in 1st Embodiment. The figure explaining the example of the conventional control in 1st Embodiment. The figure which shows the specific example of a structure of the water treatment plant in 2nd Embodiment. The figure which shows the specific example of the cell provided in a fractionation flow path in 2nd Embodiment. The figure which shows the specific example of a structure of the water treatment plant in 3rd Embodiment. The figure which shows the specific example of a structure of the water treatment plant in 4th Embodiment. The figure which shows the specific example of a structure of the water treatment plant in 5th Embodiment. The figure explaining an example of the method by which the limit determination part in 5th Embodiment determines a limit value.

Hereinafter, the flocculant injection control device, the flocculant injection control method, and the computer program of the embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a specific example of a configuration of a water treatment plant 100 according to the first embodiment. A water treatment plant realizes a solid-liquid separation process in which solids such as suspensions contained in water to be treated are aggregated by a flocculant, and the solids are separated from the water to be treated by gravity sedimentation of the aggregated solids. Equipment. In the following, water to be treated by the water treatment plant or water being treated by the water treatment plant is referred to as “treated water”, and water that has been released by the water treatment plant and has become reusable after reuse. It is called “treated water”. Moreover, below, the water which flows in from the inside and outside of a water treatment plant as a to-be-processed water, especially the to-be-processed water immediately after inflow is called "raw water." In other words, the raw water can be said to be treated water in the initial state.

The water treatment plant to which the flocculant injection control device of the embodiment is applied is not limited to a specific facility as long as such a solid-liquid separation process is realized. For example, the water treatment plant to which the flocculant injection control device of the embodiment is applied may be a water purification plant, or may be a water treatment facility provided in various factories such as a paper mill or a food factory. For example, in a water purification plant, river water, dam lake water, ground water, rain water, sewage, and the like are raw water. In industrial plants such as paper mills and food factories, the industrial wastewater is used as raw water. FIG. 1 shows an example of a water treatment plant 100 that realizes a solid-liquid separation process in a water purification plant.

The water treatment plant 100 includes various facilities that realize a solid-liquid separation process, a flocculant injection control device 1, and a plant data storage unit 2 that stores plant data supplied to the flocculant injection control device 1. For example, the water treatment plant 100 includes, as various facilities for realizing a solid-liquid separation process, a landing well 3, a rapid mixing basin 4 (mixing basin), a flock formation pond 5, a sedimentation basin 6, a filtration basin 7, and a flocculant injection device 81. PH adjustment agent injection device 82 and activated carbon injection device 83 are provided.
The water to be treated is sent in the order of the landing well 3, the rapid mixing basin 4, the flock formation basin 5, the sedimentation basin 6, and the filtration basin 7. That is, the facility located most upstream with respect to the flow of water to be treated is the landing well 3, and the facility located most downstream is the filtration pond 7. The plant data is data indicating various physical quantities measured in various facilities of the water treatment plant 100. Plant data is collected by a data collection device (not shown) and stored in the plant data storage unit 2.

The landing well 3 is a water storage tank that stores raw water flowing into the water treatment plant 100. In the landing well 3, solids having a relatively large specific gravity such as plants and earth and sand are gravity settled, and the supernatant water is sent to the rapid mixing basin 4 in the subsequent stage as treated water.

The landing well 3 is provided with a raw water quality meter 31. The raw water quality meter 31 measures the quality of raw water stored in the landing well 3. Specifically, the raw water quality meter 31 measures an index value of water quality that may affect the processing result of the solid-liquid separation process. For example, the raw water quality meter 31 measures various amounts such as turbidity and chromaticity of raw water, water temperature, electrical conductivity, pH (hydrogen ion concentration index), alkalinity (acid consumption), and ultraviolet absorbance. The ultraviolet absorbance of the raw water can be used as an index value of the amount of organic substances contained in the raw water, and for example, ultraviolet light having a wavelength of 260 nm is used for the measurement. Various index values measured by the raw water quality meter 31 are stored in the plant data storage unit 2 as plant data.

In addition, a flow meter 32 is provided in the water distribution pipe between the landing well 3 and the rapid mixing basin 4. The flow meter 32 measures the flow rate of the water to be treated sent from the landing well 3 to the rapid mixing basin 4. The flow rate measured by the flow meter 32 is stored in the plant data storage unit 2 as plant data.

The rapid mixing basin 4 is a water storage tank for injecting a flocculant into the water to be treated sent from the landing well 3 and rapidly stirring the water to be treated into which the flocculant has been injected. The flocculant injected into the mixed water is, for example, a chemical such as polyaluminum chloride (PAC: PolyAluminum Chloride) or aluminum sulfate (sulfate), and is performed by the flocculant injection device 81.

The rapid mixing basin 4 is provided with a rapid stirrer 41. The rapid stirrer 41 stirs the water to be treated into which the flocculant is injected in the rapid mixing basin 4. For example, the rapid stirrer 41 is a flash mixer. The rapid stirrer 41 may operate at a constant stirring speed, or may be capable of adjusting the stirring speed by control of a motor. In the rapid mixing pond 4, fine flocs are formed in the water to be treated by the injection of the flocculant and the stirring by the rapid stirrer 41. And the to-be-processed water containing the minute floc formed in this way is sent to the flock formation pond 5 of a back | latter stage.

Further, the water distribution pipe between the rapid mixing basin 4 and the flock formation pond 5 is provided with a mixed water quality meter 42 (an example of a coagulation state measuring unit). The mixed water quality meter 42 measures the quality of water to be treated (hereinafter also referred to as “mixed water”) into which the flocculant has been injected. Specifically, the mixed water quality meter 42 measures an index value of a property that may affect the processing result of the solid-liquid separation process, and also indicates an index value (hereinafter referred to as “aggregation”) indicating a floc aggregation state in the mixed water. Measure state index value)).
For example, the mixed water quality meter 42 measures alkalinity, pH, and conductivity as an index value of the mixed water quality that may affect the processing result of the solid-liquid separation process. Further, the mixed water quality meter 42 measures values such as the zeta potential of the mixed water, the flowing current value, and the electrophoresis speed of floc as the aggregation state index value. Various index values measured by the mixed water quality meter 42 are stored as plant data in the plant data storage unit 2, and the aggregation state index value is input to the coagulant injection control device 1.

Usually, the surface of suspension in water is negatively charged. On the other hand, the flocculant is positively charged in water. Therefore, when the flocculant is injected into the water to be treated containing the suspension, the flocculant adheres to the suspension. The flocculant adhering to the suspension cancels the negative charge of the suspension (hereinafter referred to as “neutralization”), and brings the surface charge of the suspension close to 0 [mV]. As the surface charge of the suspension approaches 0 [mV], the zeta potential also approaches 0 [mV]. Thus, the flocculant weakens the repulsion between the suspensions and increases the number of collisions. Due to the action of the flocculant, the flocs that have collided gradually aggregate to form larger flocs.

In addition, in the rapid mixing pond 4, in addition to the injection of the flocculant, a pH adjuster or activated carbon is injected into the mixed water. The pH adjusting agent is injected by the pH adjusting agent injection device 82, and the activated carbon is injected by the activated carbon injection device 83. The injection of the pH adjusting agent or the activated carbon is not necessarily essential in the solid-liquid separation process, but can be a means for adjusting the quality of the water to be treated. For example, activated carbon is injected for the purpose of removing odorous substances and organic substances contained in the water to be treated, and a pH adjuster is injected for the purpose of promoting floc aggregation.

There are acidic and alkaline pH adjusters. For example, sulfuric acid and hydrochloric acid are acidic pH adjusters, and sodium hydroxide (also called caustic soda) is an alkaline pH adjuster. The pH adjuster injection device 82 determines which of the acidic or alkaline pH adjuster should be injected according to the quality of the water to be treated, and adjusts the pH and alkalinity of the mixed water to a predetermined value. Determine the amount of injection. For example, when an alkaline pH adjusting agent is injected, the pH adjusting agent injection device 82 determines the injection amount of the pH adjusting agent so that the alkalinity of the mixed water after injection becomes about 20 ± 5 [mg / l]. To do.

Further, activated carbon is generally injected in the form of powder or slurry, and the injection is often performed irregularly. For example, the injection of activated carbon is often performed in a season or a time zone where a lot of odorous substances and organic substances to be removed are contained in the water to be treated.

The flock formation pond 5 is a water storage tank for forming a larger flock in the water to be treated. The floc formation pond 5 is provided with a slow agitator, and further agglomeration of flocs is promoted by stirring the water to be treated by the slow agitator. For example, the flock formation pond 5 is divided into three

agitation ponds

51, 52 and 53 as shown in FIG. 1, and

slow agitators

54, 55 and 56 are respectively installed in the agitation ponds. For example, the

slow stirrers

54, 55 and 56 are flocculators. Among the agitation ponds, the agitation pond 51 is located on the most upstream side with respect to the flow of water to be treated, and the agitation pond 53 is located on the most downstream side.

The water to be treated sent from the rapid mixing basin 4 flows into the stirring basin 51. In the stirring basin 51, flocs having a larger particle diameter are formed by the fine flocs repeatedly colliding with the water to be treated by the slow stirrer 54. The water to be treated in the stirring basin 51 is sent to the subsequent stirring basin 52 after stirring for a predetermined time.

The treated water sent from the stirring basin 51 flows into the stirring basin 52. In the stirring basin 52, flocs having a larger particle diameter are formed by stirring the water to be treated by the slow stirrer 55. Here, if the stirring strength is too strong, the agglomerated flocs are destroyed, so the slow stirrer 55 stirs the water to be treated with a lower strength than the slow stirrer 54. This promotes further agglomeration of the floc. The water to be treated in the stirring basin 52 is sent to the subsequent stirring basin 53 after stirring for a predetermined time.

The treated water sent from the stirring basin 52 flows into the stirring basin 53. In the stirring basin 53, flocs having a larger particle size are formed by stirring the water to be treated by the slow stirrer 56. Again, the slow stirrer 56 stirs the water to be treated with a weaker strength than the slow stirrer 55 so that the agglomerated floc is not destroyed. This promotes further agglomeration of the floc. The water to be treated in the stirring basin 53 is sent to the subsequent settling basin 6 after stirring for a predetermined time.

The sedimentation basin 6 is a water storage tank for storing water to be treated flowing from the flock formation pond 5. By storing the water to be treated in the sedimentation basin 6 for a predetermined time, the flocs having a large particle size formed in the floc formation basin 5 are gravity settled. For example, the water to be treated is stored in the sedimentation basin 6 for about 3 hours. Thereby, a floc is isolate | separated from to-be-processed water and the supernatant water is sent to the filtration pond 7 of a back | latter stage. In addition, the most downstream part of the sedimentation basin 6 may be provided with equipment for performing ozone treatment, biological activated carbon treatment or the like on the water to be treated sent to the filtration basin 7. Further, the floc precipitated in the settling basin 6 is extracted as sludge and sent to a sludge treatment facility (not shown).

In addition, a sedimentation basin water quality meter 61 is provided downstream of the sedimentation basin 6. The sedimentation basin water quality meter 61 measures the quality of water to be treated sent to the filtration pond 7. Specifically, the sedimentation basin water quality meter 61 measures an index value representing the processing result of the solid-liquid separation process. For example, the sedimentation basin water quality meter 61 measures the turbidity and chromaticity of the water to be treated as an index value representing the treatment result of the solid-liquid separation process. Various index values measured by the settling pond water quality meter 61 are stored in the plant data storage unit 2 as plant data.

The filtration basin 7 is a reservoir provided with a filtration facility for the water to be treated flowing from the sedimentation basin 6.
In the filtration pond 7, minute solids remaining in the water to be treated are separated by filtration. The filtered water to be treated is discharged or reused as treated water.

In the water treatment plant 100 having such various facilities, the flocculant injection control device 1 uses the flocculant injection amount injected by the flocculant injection device 81 based on the plant data supplied from the plant data storage unit 2 (hereinafter, “ This is referred to as “flocculating agent injection amount”). Generally, the flocculant injection amount is expressed by the amount of the flocculant injected per unit time. Further, the coagulant injection amount is converted into the coagulant injection rate (hereinafter referred to as “coagulant injection rate”) using the flow rate of the water to be treated per unit time. Hereinafter, although the structure of the flocculant injection control device 1 of the present embodiment will be described in detail, the flocculant injection amount can be appropriately replaced with the flocculant injection rate.

The flocculant injection control device 1 includes a CPU (Central Processing Unit) connected via a bus, a memory, an auxiliary storage device, and the like, and executes a program. The flocculant injection control device 1 functions as a device including a turbidity target value input unit 11, a control target value determination unit 12, and a flocculant injection control unit 13 by executing a program. All or part of each function of the flocculant injection control device 1 is realized by using hardware such as ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), and FPGA (Field Programmable Gate Array). Also good. The program may be recorded on a computer-readable recording medium. The computer-readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in the computer system. The program may be transmitted via a telecommunication line.

The turbidity target value input unit 11 inputs a target value related to the quality of treated water obtained by the solid-liquid separation process. In general, the water quality required for the solid-liquid separation process differs depending on the use and operation policy of the water treatment plant 100, and the validity of the treatment result is the turbidity of the treated water sent from the sedimentation basin 6 to the filtration basin 7 (hereinafter referred to as the turbidity) This is often referred to as “sedimentation pond turbidity”. Therefore, here, the turbidity target value input unit 11 uses the target value (hereinafter referred to as “turbidity target value”) of the settling pond turbidity determined by the operator of the water treatment plant 100 as the target value related to the water quality of the treated water. "). The turbidity target value input unit 11 may be configured as an input device such as a keyboard or a touch panel that receives input of the turbidity target value, or is configured as a communication device that acquires the turbidity target value via a communication line. Also good. The turbidity target value input unit 11 outputs the input turbidity target value to the control target value determination unit 12.

The control target value determination unit 12 determines a control target value for determining the coagulant injection rate of the coagulant injection device 81 by the feedback control method. The feedback control is a control method for controlling the control amount to the control target value by changing the operation amount based on the deviation between the control amount and the control target value. In the present embodiment, the control target value determining unit 12 sets the target value of the aggregation state index value (hereinafter referred to as “aggregation state target value”) for the purpose of controlling the sedimentation turbidity to the turbidity target value. Determine as value. The control target value determination unit 12 outputs the determined aggregation state target value to the coagulant injection control unit 13.

The coagulant injection control unit 13 determines the coagulant injection rate of the coagulant injection device 81 based on the aggregation state target value determined by the control target value determination unit 12 and the plant data supplied from the plant data storage unit 2. Determined as manipulated variable. The coagulant injection control unit 13 notifies the coagulant injection device 81 of the determined coagulant injection rate. The control cycle of the flocculant injection rate is performed at a cycle of 10 minutes, for example.

Specifically, the flocculant injection control unit 13 performs the feedback control operation amount based on the aggregation state target value determined by the control target value determination unit 12 in feedback control using the aggregation state index value as a control amount. The coagulant injection rate is determined. For example, the flocculant injection control unit 13 executes feedback control such as P control (proportional control: Proportional Controller), PI control (Proportional-Integral Controller), PID control (Proportional-Integral-Differential Controller), and the like. . Here, it is assumed that the aggregation state index value is acquired from the plant data storage unit 2, but the aggregation state index value is directly input to the coagulant injection control unit 13 without going through the plant data storage unit 2. It may be entered.

Subsequently, the configuration of the control target value determination unit 12 will be described more specifically. The control target value determination unit 12 includes a parameter identification unit 121 and a target value determination unit 122 as a configuration for determining the aggregation state target value.

The parameter identification unit 121 identifies a parameter (hereinafter referred to as “prediction parameter”) constituting a prediction formula for the sedimentation turbidity based on the past plant data acquired from the plant data storage unit 2. Specifically, the parameter identification unit 121 describes various amounts indicating the state of the water to be treated before the flocculant is injected and various amounts indicating the state of the water to be treated after the flocculant is injected. In addition, the prediction parameters are identified by performing multiple regression analysis with sedimentation turbidity as the objective variable.

For example, the state of the water to be treated before the flocculant is injected includes various conditions such as turbidity, pH, alkalinity, water temperature, conductivity, chromaticity, ultraviolet absorbance, and flow rate measured by the raw water quality meter 31. Expressed by quantity. On the other hand, the state of the water to be treated after the flocculant is injected is the pH, alkalinity, conductivity, flocculant injection rate, pH adjuster injection rate, activated carbon injection measured by the mixed water meter 42. It is represented by various quantities such as rate and stirring intensity. Each injection rate can be acquired from each of the injection devices 81 to 83, and the stirring intensity can be acquired from the rapid stirrer 41 or each of the slow stirrers 54 to 56.

For example, plant data acquired in a past predetermined period (for example, one week to one month) is used for identification of a prediction parameter. In contrast, plant data is acquired in the plant data storage unit 2 at short time intervals of, for example, about 1 minute. In addition, when the water quality change of raw | natural water is gentle, plant data may be acquired by a longer time interval (for example, 1 hour). In addition, since various measurement data acquired as plant data may include an abnormal value, it is desirable that the plant data be subjected to a process for removing the abnormal value or a process for reducing the influence of the abnormal value. These functions may be provided in the flocculant injection control device 1 or may be provided in the above-described data collection device.

For example, by taking an average value of plant data every predetermined time and using the average value group for identification of prediction parameters, the possibility that abnormal values included in plant data will reduce the identification accuracy of prediction parameters is reduced. Can do. In addition, all of the plant data within a predetermined time may be used for calculation of the average value, or plant data excluding data with low reliability (that is, a large variance) every predetermined time may be used. Good. A method of extracting highly reliable data from sample data and taking an average is generally called a trimmed average.

In the solid-liquid separation process, the water to be treated is treated through a plurality of stages. Therefore, when identifying a prediction parameter using plant data acquired at different stages, it is necessary to consider a time delay due to processing time at each stage. For example, it takes about 4 hours for the response of the water quality change in the rapid mixing basin 4 to appear as the water quality change in the sedimentation basin 6. In addition, it takes about 5 hours for the response of the water quality change in the landing well 3 to appear as the water quality change of the sedimentation basin 6. Therefore, in this case, in order to identify the prediction parameter using the data indicating the water quality of the sedimentation basin 6 at a certain time point, the data indicating the water quality of the rapid mixing basin 4 at a time point about 4 hours before the time point, Data indicating the water quality of the landing well 3 at about 5 hours before the time is required.

This means that as a precondition for performing multiple regression analysis, it is necessary to create a data set reflecting the time delay between plant data acquired at different stages. Therefore, the parameter identification unit 121 generates a data set reflecting the time delay between the plant data as preprocessing of the multiple regression analysis. Specifically, the parameter identification unit 121 estimates the time delay in each stage based on the volume of each reservoir and the flow rate of the treated water sent between the reservoirs, and according to the stage where each plant data is acquired. Generate multiple data sets that are combined by shifting the delay time.

Each data set generated in this way may include data when a preferable processing result is obtained for the solid-liquid separation process, and may include data when it is not preferable. Even if the processing results are good or bad, these are obtained as a result of analyzing the relationship between the explanatory variable and the objective variable, so it is usually not necessary to select the data set based on the quality of the processing results. . Rather, in order to estimate a more accurate relationship between explanatory variables and objective variables, it is desirable that each data set includes data for various cases. However, when the quality of raw water is significantly different from normal, such as when a typhoon or guerrilla heavy rain occurs, manual control is often performed instead of automatic control. Therefore, the parameter identification unit 121 may be configured to exclude data acquired at the time of such abnormality from plant data used for multiple regression analysis. For example, the parameter identification unit 121 may be configured to store a raw water turbidity threshold (for example, 30 degrees) in advance and exclude data indicating turbidity equal to or higher than the threshold from plant data related to raw water.

Here, a specific example of the prediction formula estimated by the parameter identification unit 121 is shown in the following formula (1).

In equation (1), Y represents the sedimentation pond turbidity to be predicted. km (m is an integer of 0 or more) represents a prediction parameter identified by the parameter identification unit 121. xn (n is an integer greater than or equal to 1) is an input variable of a prediction formula, and represents each value that may affect the sedimentation pond turbidity. For example, the input variables include various index values indicating the water quality of raw water and mixed water, values such as the coagulant injection rate and aggregation state index value, or values calculated based on these values (for example, the amount of change, Change rate). In addition to these values, the input variables are calculated based on the activated carbon injection rate, the pH adjusting agent injection rate, the stirring speed in the rapid mixing basin 4 or the flock formation basin 5, or the like. May be included.

The parameter identification unit 121 uses the sedimentation pond turbidity as an objective variable, each input variable of the prediction formula as an explanatory variable, and performs multiple regression analysis using the plant data corresponding to the objective variable and the explanatory variable. The prediction parameter of equation (1) that uniquely determines the relationship with the explanatory variable is determined. The parameter identification unit 121 outputs the prediction parameter identified in this way to the target value determination unit 122. Note that the plant data corresponding to the objective variable and the explanatory variable is supplied from the plant data storage unit 2 as time-series data for a predetermined period in the past.

The target value determination unit 122 determines the aggregation state target value using the prediction parameter identified by the parameter identification unit 121. Specifically, the target value determination unit 122 inputs the current value of each value as an input variable to the prediction model determined by the prediction parameter, thereby predicting the response of the settling turbidity to the input. As mentioned above, there is a time delay of about 1 hour for the response to changes in the quality of the raw water to appear as a change in the quality of the mixed water. The variable may be given a value one hour before the current time. However, since the change in water quality occurring in about one hour is small, the current values may be given to all input variables.

The target value determination unit 122 determines the aggregation state target value (control target value) based on the difference between the calculated predicted value of the sedimentation pond turbidity and the turbidity target value input by the turbidity target value input unit 11. To do. Specifically, when the predicted value of the sedimentation pond turbidity is higher than the turbidity target value, it is predicted that the flocculant is insufficient and the water quality of the sedimentation basin 6 is deteriorated. Therefore, in this case, the target value determination unit 122 determines the aggregation state target value so as to increase the coagulant injection rate.

On the other hand, when the predicted value of the sedimentation pond turbidity is lower than the turbidity target value, it is predicted that the flocculant will be excessive and the water quality of the sedimentation basin 6 will be excessively improved. Therefore, in this case, the target value determination unit 122 determines the aggregation state target value so as to decrease the coagulant injection rate. Such processing for determining the aggregation state target value may be realized by P control or PI control based on a deviation between the predicted value of the settling turbidity and the turbidity target value. As described above, since it takes about 3 to 5 hours for the control response to appear in the sedimentation basin 6 after the control of the coagulant injection rate, the change of the control target value has a time delay. In consideration of this, it is desirable to carry out at a certain time interval.

For example, the identification of the prediction parameter may be performed on a daily basis, or may be performed on a weekly basis when there is no significant change in the quality or condition of the raw water. For example, it is known that the quality of raw water changes seasonally, and the change in water temperature has a large seasonal influence. Therefore, when there are no factors that change the quality and state of raw water faster than seasonal changes, prediction parameters may be identified on a monthly basis. Thus, the identification frequency of a prediction parameter is good to be defined according to the magnitude | size of the water quality fluctuation | variation of raw | natural water in the water treatment plant of an application destination. The target value determination unit 122 outputs the aggregation state target value determined in this way to the coagulant injection control unit 13.

FIG. 2 is a flowchart showing a flow of processing for controlling the amount of flocculant injected into the rapid mixing basin 4 by the flocculant injection control device 1 in the first embodiment. First, the turbidity target value input unit 11 receives an input of a turbidity target value (step S101). The turbidity target value input unit 11 outputs the input turbidity target value to the control target value determination unit 12.

Subsequently, the parameter identification unit 121 identifies a prediction parameter for determining a precipitation turbidity prediction formula using past plant data (step S102). The parameter identification unit 121 outputs the identified prediction parameter to the target value determination unit 122.

Subsequently, the target value determination unit 122 applies the prediction parameter identified by the parameter identification unit 121 to the prediction formula, and predicts the control response of the sedimentation pond turbidity depending on the current amount of the flocculant injected (step S103). The target value determination unit 122 determines the coagulation state target value of the mixed water based on the turbidity target value input via the turbidity target value input unit 11 and the predicted value of the settling pond turbidity (step S104). ). The target value determination unit 122 outputs the determined aggregation state target value to the coagulant injection control unit 13.

Subsequently, the coagulant injection control unit 13 determines the coagulant injection rate instructed to the coagulant injection device 81 based on the current aggregation state and the aggregation state target value determined by the target value determination unit 122. (Step S105). The coagulant injection control unit 13 notifies the coagulant injection device 81 of the determined coagulant injection rate (step S106).

The flocculant injection control device 1 of the first embodiment configured as described above predicts the sedimentation turbidity that changes with a time delay with respect to the flocculant injection, and the predicted value and the sedimentation turbidity The flocculant injection amount is determined based on the target value (turbidity target value). For this reason, according to the coagulant | flocculant injection | pouring control apparatus 1 of 1st Embodiment, the coagulant | flocculant injection | pouring amount with respect to to-be-processed water can be controlled more appropriately.

In many conventional water treatment plants, information indicating the correspondence between the turbidity of raw water and the amount of flocculant to be injected (hereinafter referred to as “corresponding information”) is generated in advance, and the current value of turbidity is obtained. And the corresponding information have been used to determine the flocculant injection amount. This correspondence information is represented, for example, as data in the table format shown in FIG. 3 or data in the function format shown in FIG. Such a control method is generally called feedforward control. In this case, it is necessary to generate correspondence information in advance, and the correspondence information must be in accordance with the application and characteristics of the target water treatment plant. Therefore, in the conventional control method, work for generating correspondence information for each water treatment plant to be applied occurs, and the control method is not necessarily highly versatile.

In addition, this conventional control method assumes that the control accuracy will be improved by updating the corresponding information based on the plant operation experience, so enough know-how is accumulated after the start of operation. A high control accuracy is not always achieved at a stage where the control is not performed.
Furthermore, in the conventional feedforward control method, when the quality of the raw water changes, the change cannot be handled unless the cause of the change is specified and reflected in the corresponding information.

In contrast, the flocculant injection control device 1 according to the first embodiment takes in the influence due to the change in the quality of the raw water as the aggregation state index value, and performs a multiple regression analysis including the aggregation state index value as an explanatory variable. Estimate the prediction formula of sedimentation pond turbidity. Therefore, according to the flocculant injection control device 1 of the first embodiment, it is possible to determine the flocculant injection rate corresponding to the change in the quality of the raw water.

Furthermore, the flocculant injection control device 1 performs multiple regression analysis in consideration of the time delay until the control response of the flocculant injection rate appears in the settling pond turbidity, and thus controls the injection amount of the flocculant more appropriately. It becomes possible.

Moreover, since the flocculant injection control apparatus 1 of 1st Embodiment performs feedback control using the prediction formula which contains an aggregation state index value as a variable, even if it is a case where the quality of raw | natural water changes, the change Without specifying the factor, the flocculant injection rate can be controlled so that the turbidity of the sedimentation basin follows the turbidity target value.

Further, the flocculant injection control device 1 of the first embodiment determines the flocculant injection amount based on the target value of the sedimentation turbidity. For this reason, according to the flocculant injection control device 1 of the first embodiment, even when the target value of the sedimentation turbidity varies from plant to plant, the flocculant injection rate is automatically set according to the turbidity target value of each plant. Can be controlled.

Further, the flocculant injection control device 1 of the first embodiment estimates a prediction formula for the sedimentation turbidity including the flow rate of the water to be treated as a variable. For this reason, according to the flocculant injection control device 1 of the first embodiment, the control target value (aggregation state target) in consideration of the flow rate of the water to be treated also in the plant in which the fluctuation of the flow rate greatly affects the sedimentation turbidity. Value) can be set. Here, the degree of change of each value corresponding to the variable of the prediction formula differs depending on the plant, and some of them do not change greatly. For example, the stirring intensity of the water to be treated does not change when the stirrer operates at a constant rotational speed. As described above, when it is known in advance that the change is small with respect to a certain value, a variable corresponding to the value may be excluded from the prediction formula. Which value is used for the variable of the prediction formula for predicting the sedimentation pond turbidity may be arbitrarily determined according to the use and characteristics of each plant.

Hereinafter, modifications of the flocculant injection control device 1 of the first embodiment will be described. The parameter identification unit 121 may estimate a prediction formula including a variable based on a difference between the quality of the water to be treated before the flocculant is injected and the quality of the water to be treated after the flocculant is injected. For example, when the pH value of the raw water is A and the pH value of the mixed water is B, the parameter identification unit 121 identifies the prediction parameter of the prediction formula including the variable x _AB based on the difference between A and B. In this case, for example, the variable x _AB is a value represented by the following equation (2).

In this case, specifically, the parameter identification unit 121 uses the plant data indicating the pH of the raw water and the plant data indicating the pH of the admixed water to time-series the difference between the pH of the raw water and the admixed water. Calculate and include the calculated values in the corresponding data sets to perform multiple regression analysis. Here, the parameter identification unit 121 may calculate a difference in consideration of the time delay, similarly to other index values. As described above, the flocculant injection control apparatus estimates the prediction formula including the variable based on the quality of the water to be treated before injecting the flocculant and the quality of the water to be treated after the flocculant is injected. 1 can predict the sedimentation turbidity more accurately.

Specifically, the injection effect of the flocculant may vary depending on the pH of the raw water, the pH of the admixed water, and the magnitude of the difference. In such a case, it is possible to improve the accuracy of the prediction formula by estimating the prediction formula including a variable as shown in Formula (2). Here, although the case where the variable which shows the difference about the pH of raw | natural water and mixed water was included in the prediction formula was demonstrated, the index value which takes a difference is not limited to pH. For example, when the aggregation state index value is measured before and after the injection of the flocculant, a variable based on the difference in the aggregation state index value may be included in the variable of the prediction formula.

For example, when measuring the aggregation state index value by a method described later in the second embodiment, a preparatory flow path is provided for each of the water to be treated before the flocculant injection and the water to be treated after the flocculant injection, What is necessary is just to install a measuring apparatus (analysis part) in the position which can image the cell provided in each preparatory flow path. According to the method for measuring the aggregation state index value in the second embodiment, the aggregation state index value can be measured without providing separate measuring devices before and after the injection of the aggregating agent.

In this way, for index values that may affect the turbidity of the sedimentation basin before and after the flocculant injection, the difference is taken into the variables of the prediction formula, and the prediction parameters are identified, so that more accurate precipitation can be achieved. It becomes possible to estimate the prediction formula of pond turbidity.

(Second Embodiment)
FIG. 5 is a diagram illustrating a specific example of the configuration of the water treatment plant 100a according to the second embodiment. The water treatment plant 100a differs from the water treatment plant 100 in the first embodiment in that it includes an analysis unit 9 (an example of an aggregation state measurement unit) as an example of a specific means for measuring an aggregation state index value. The flocculant injection control apparatus 1 in the second embodiment is different from the flocculant injection control apparatus 1 in the first embodiment in that the aggregation state index value measured by the analysis unit 9 is used for the determination of the aggregation state target value. Although different, the functional configuration for determining the coagulant injection rate is the same as that of the coagulant injection control device 1 in the first embodiment.

The analysis unit 9 is a device that analyzes a part of the mixed water that has been collected and measures the aggregation state index value. FIG. 5 shows a configuration in which a part of the mixed water is separated from the water distribution pipe between the rapid mixing basin 4 and the flock formation pond 5. This configuration is an example, and the mixing water does not necessarily have to be separated from the water distribution pipe between the rapid mixing basin 4 and the flock formation pond 5. For example, the mixing water may be collected from the rapid mixing pond 4 or may be obtained from the flock formation pond 5. In addition, when the sorting flow path cannot be provided, the mixing of the mixed water may be performed manually. In the present embodiment, the mixing of the mixed water is realized by flowing a part of the mixed water flowing through the water distribution pipe into a flow path (hereinafter referred to as “sort flow path”) different from the water distribution pipe. And

The analysis unit 9 includes a light source unit 91, an imaging unit 92, and a speed measurement unit 93 as a configuration for measuring the aggregation state index value. The light source unit 91 irradiates the mixed water flowing through the sorting channel with light. The light source unit 91 is a light source that emits laser light or visible light, for example. The light source unit 91 may be configured to be able to change the intensity and wavelength of the irradiated light. A part of the light emitted from the light source unit 91 is scattered on the surface of the floc in the mixed water, and the other part is transmitted through the mixed water and received by the optical system of the imaging unit 92.

The imaging unit 92 is configured using an imaging device such as a camera. The imaging part 92 is arrange | positioned in the position which can image the mixing water which flows through a fractionation flow path. For example, a transparent container called a cell is installed in the middle of the sorting channel, and the light source unit 91 and the imaging unit 92 are arranged so as to face each other with the cell sandwiched from the direction of the mixed water from the vertical direction. . With such an arrangement, the mixed water flowing through the cell is irradiated with light from a direction perpendicular to the flow, and the imaging unit 92 receives the light transmitted through the cell.
The imaging unit 92 generates image data of the mixed water passing through the cell by converting the intensity of the received light into a digital value. The imaging unit 92 images the mixed water passing through the cell at a predetermined imaging cycle (for example, a 1/3 second cycle), and outputs the generated image data to the speed measuring unit 93 in time series.

The speed measurement unit 93 measures a value (aggregation state index value) indicating the aggregation state of the floc in the mixed water based on the image data output from the imaging unit 92. Specifically, the speed measuring unit 93 measures the electrophoresis speed of floc as an aggregation state index value. The speed measuring unit 93 measures the electrophoretic speed of floc in the mixed water using the time-series image data output from the imaging unit 92, and outputs the measured electrophoretic speed to the parameter identifying unit 121 in time series.

FIG. 6 is a diagram illustrating a specific example of a cell provided in the sorting flow path in the second embodiment. FIG. 6 shows an example of a cell through which admixed water flowing from the negative y-axis direction passes in the positive y-axis direction. The cell C includes a positive electrode EP and a negative electrode EN that form an electric field in a direction perpendicular to the mixed water flow, and a power source PS that applies a voltage to the positive electrode EP and the negative electrode EN. When the power supply PS passes mixed water in a state where a voltage is applied to the positive electrode EP and the negative electrode EN, electrophoresis of flocs in the mixed water occurs in the cell C.

Specifically, a floc having a negative surface charge moves in the positive EP direction (that is, the negative direction of the x axis) by applying a voltage. Therefore, the average value of the electrophoresis speed of flocs having a negative surface charge is negative. On the other hand, the floc having a positive surface charge moves in the negative electrode EN direction (that is, the positive direction of the x axis) by applying a voltage. Therefore, the average value of the electrophoresis speed of flocs having a positive surface charge is positive.

In contrast, flocs with neutralized surface charges are not affected by the electric field. Therefore, the moving direction of the floc in which the surface charge is neutralized is not constant even in the situation where a voltage is applied. Therefore, the variation in the moving speed of individual flocs increases, and the variance value of the moving speed increases. Therefore, it is considered that the dispersion value of the moving speed of the floc whose surface charge is neutralized is a predetermined value or more. Therefore, it is possible to grasp whether or not the surface charge of the floc is neutralized by comparing the predetermined value as a threshold value with the variance value of the moving speed of the floc.

The speed measuring unit 93 detects flocs in the image by performing image analysis processing by software on the image in which the mixed water passing through the cell C is imaged, and obtains the moving speed of each detected floc. The moving speed is obtained based on the position of the flock between images taken continuously and the imaging cycle. The speed measuring unit 93 measures the moving speed for each detected flock, and calculates the average value (hereinafter referred to as “average moving speed”) of the moving speed of each flock.

The speed measuring unit 93 may take a moving average of the moving speeds obtained for each flock and calculate a value obtained by averaging the moving average values of the respective flocks as the average moving speed. The speed measurement unit 93 outputs the time series data of the average moving speed calculated in this way to the parameter identification unit 121 as the aggregation state index value. The average moving speed is not limited to the average value as long as it indicates an average value of the electrophoresis speed of each floc, and may be replaced with another statistical value.

The water treatment plant 100a of the second embodiment configured as described above is more accurate with respect to the flocculant injection control device 1 by including the analysis unit 9 that measures the average movement speed of flocs by image analysis processing. Aggregation state index values can be supplied.

In addition, in 2nd Embodiment, although the water treatment plant 100a provided with the analysis part 9 as another apparatus different from the coagulant | flocculant injection control apparatus 1 was demonstrated, the analysis part 9 is not necessarily separate from the flocculant injection control apparatus 1. It may not be necessary to be configured as a part of the flocculant injection control device 1.

Moreover, in 2nd Embodiment, although the analysis part 9 which measures the electrophoresis speed of a floc was demonstrated as an example of the apparatus which measures an aggregation state index value, the analysis part 9 is an apparatus which measures another aggregation state index value May be replaced. For example, the water treatment plant 100a is replaced with another device that measures an index value indicating the flock charge state, such as the zeta potential of flock, the flow current value of mixed water, or the amount of colloidal charge, instead of the analysis unit 9. Also good.

(Third embodiment)
FIG. 7 is a diagram illustrating a specific example of the configuration of the water treatment plant 100b according to the third embodiment. The water treatment plant 100b is different from the water treatment plant 100 in the first embodiment in that the flocculant injection control device 1b is provided instead of the flocculant injection control device 1 and the plant data storage unit 2 is not provided. The flocculant injection control device 1b is different from the flocculant injection control device 1 of the first embodiment in that a control target value determination unit 12b is provided instead of the control target value determination unit 12. The control target value determination unit 12b is different from the control target value determination unit 12 in the first embodiment in that the parameter identification unit 121 is not provided and the target value determination unit 122b is provided instead of the target value determination unit 122. Other configurations of the water treatment plant 100b are the same as those in the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals as those in FIG.

The target value determination unit 122b is the same as the target value determination unit 122 in the first embodiment in that the aggregation state target value is determined based on the difference between the measured value of the sedimentation turbidity and the turbidity target value. The target value determination unit 122 in the first embodiment is different from the target value determination unit 122 in the first embodiment in that the predicted value of the sedimentation pond turbidity based on the current injection amount of the flocculant is not used to determine the target value of the aggregation state.

Specifically, when the actual measurement value is lower than the turbidity target value, the target value determination unit 122b determines the aggregation state target value so as to reduce the coagulant injection rate, and the actual measurement value is the turbidity target value. If the value exceeds the value, the aggregation state target value is determined so as to increase the flocculant injection rate. Such a control method is effective in a plant in which the quality of raw water gradually changes. Specifically, the quality of the raw water changes after the flocculant is injected into the water to be treated in the rapid mixing basin 4 until the sedimentation turbidity of the water to be treated is measured in the sedimentation basin 6. It is effective when the time is shorter.

The water treatment plant 100b according to the third embodiment configured as described above has the same effects as the water treatment plant 100 according to the first embodiment with a simpler configuration.

(Fourth embodiment)
FIG. 8 is a diagram illustrating a specific example of the configuration of the water treatment plant 100c according to the fourth embodiment. The water treatment plant 100c is different from the water treatment plant 100b in the third embodiment in that a flocculant injection control device 1b is provided instead of the flocculant injection control device 1b. The flocculant injection control device 1c is different from the flocculant injection control device 1b of the third embodiment in that it further includes a limit input unit 14 and a target value adjustment unit 15. Other configurations of the water treatment plant 100c are the same as those of the third embodiment. Therefore, the same components as those in the third embodiment are denoted by the same reference numerals as those in FIG.

The limit input unit 14 receives an input of a limit value for the control target value (aggregation state target value) determined by the target value determination unit 122b. The limit value is a value indicating an allowable range of the control target value input to the flocculant injection control unit 13. The limit value is represented by an upper limit value, a lower limit value, or both of the control target values, and is determined by, for example, an operator of the water treatment plant 100c. The limit input unit 14 outputs the input limit value to the target value adjustment unit 15.

The target value adjusting unit 15 adjusts the control target value determined by the target value determining unit 122b based on the limit value. Specifically, the target value adjustment unit 15 determines whether or not the control target value determined by the control target value determination unit 12b is within the range indicated by the limit value, and the control target value is determined according to the determination result. Is adjusted to a value within the above range. The target value adjustment unit 15 outputs the adjusted control target value to the coagulant injection control unit 13.

For example, when the zeta potential of admixed water is measured as the aggregation state index value, it is assumed that a limit value having an upper limit value of 10 mV and a lower limit value of −10 mV is input. In this case, when the target value of the zeta potential determined by the target value determination unit 122b is within the range of −10 mV to 10 mV, the target value adjustment unit 15 determines the target of the zeta potential determined by the target value determination unit 122b. The value is output to the coagulant injection control unit 13 as it is.

On the other hand, when the target value of the zeta potential is less than −10 mV, the target value adjusting unit 15 outputs the lower limit value of −10 mV to the flocculant injection control unit 13 as a control target value. When the target value of the zeta potential exceeds 10 mV, the target value adjustment unit 15 outputs 10 mV, which is the upper limit value, to the flocculant injection control unit 13 as a control target value.

According to the flocculant injection control device 1 of the fourth embodiment configured as described above, it is possible to suppress the floc aggregation state in the mixed water from being controlled outside the expected range.

(Fifth embodiment)
FIG. 9 is a diagram illustrating a specific example of the configuration of the water treatment plant 100d according to the fifth embodiment. The water treatment plant 100d differs from the water treatment plant 100c in the fourth embodiment in that it includes a flocculant injection control device 1d instead of the flocculant injection control device 1c. The flocculant injection control device 1d is different from the flocculant injection control device 1c of the fourth embodiment in that a limit determination unit 16 is provided instead of the limit input unit 14. Other configurations of the water treatment plant 100d are the same as those in the fourth embodiment. Therefore, the same components as those in the fourth embodiment are denoted by the same reference numerals as those in FIG.

The limit determination unit 16 determines a limit value to be input to the target value adjustment unit 15 based on the quality of raw water. Specifically, the limit determination unit 16 acquires measured values such as pH and water temperature of raw water from the raw water quality meter 31, and determines limit values according to the acquired water quality such as pH and water temperature. The limit determination unit 16 outputs the determined limit value to the target value adjustment unit 15.

FIG. 10 is a diagram for explaining an example of a method by which the limit determination unit 16 in the fifth embodiment determines a limit value. FIG. 10 is a diagram showing a control target value range (hereinafter referred to as “control target value range”) that can be determined when the zeta potential of the admixed water is a control amount. The horizontal axis in FIG. 10 represents the pH of the raw water, and the vertical axis represents the target value of the zeta potential that can be determined. A range R1 represents a control target value range of the zeta potential when the water temperature of the raw water is 10 degrees and the pH is 7.0. The range R2 represents the control target value range of the zeta potential when the water temperature of the raw water is 20 degrees and the pH is 7.0.

The limit determination unit 16 stores in advance setting information indicating a control target value range corresponding to the quality of the raw water, and the control target to be applied based on the setting information and the actual measured value of the quality of the raw water. Select a value range. In this case, the limit determination unit 16 outputs the selected control target value range to the target value adjustment unit 15 as limit information.

In the example of the setting information shown in FIG. 10, the slope of each control target value range is negative. This indicates that it is better to change the target value of the zeta potential to the positive side as the pH of the raw water becomes lower. In the example of FIG. 10, the control target range shifts to the positive side of the vertical axis as the temperature of the raw water decreases. This generally indicates that the progress of the agglomeration reaction becomes slower as the water temperature becomes lower, so it is better to increase the injection amount of the coagulant as the water temperature of the raw water becomes lower.

Note that FIG. 10 shows only the control target value range when the pH of the raw water is 7.0, but actually, the setting information shows the water quality that the raw water can take (here, the water temperature and pH). Information indicating the control target value range for each combination.

Moreover, the limit determination part 16 may be provided with the function which produces | generates setting information instead of storing setting information beforehand. For example, the control target range shown in FIG. 10 is uniquely determined by the line segment indicating the minimum value of the target value at each pH and the width in the normal direction of the line segment. For example, the control target range R1 in FIG. 10 is determined by the line segment W on the straight line L and the width H. Here, considering that the agglomeration state target value is determined to change the current settling tank turbidity to the turbidity target value, and considering that the settling tank turbidity is greatly influenced by the quality of raw water and mixed water, The target value is considered to correlate with the influence of the current water quality of raw water and admixed water on sedimentation turbidity.
The degree of influence is represented by the prediction parameter identified by the parameter identification unit 121. Therefore, it is considered that each control target range can be expressed as a function of the prediction parameter identified for the prediction formula of the sedimentation pond turbidity.

For example, the limit determination unit 16 determines each element (for example, the slope and intercept of the straight line L, the coordinates of one end of the line segment W, the length of the line segment W, etc.) and the width H to determine the line segment W. The prediction parameter is expressed as a function having a variable, and the value of each element is calculated by substituting the prediction parameter identified by the parameter identification unit 121 into this function. The coefficient for converting the value determined by the current water quality and the prediction parameter into the value of each element may be set manually by an operator or the like, or may be obtained by regression analysis using past plant data. . Thereby, the limit determination part 16 can determine the control target range according to the present water quality of raw | natural water and mixed water.

Each element is considered to be expressed as a function with the current water quality of raw water and admixed water as a variable.
Therefore, similarly to the parameter identification unit 121, the limit determination unit 16 estimates a function representing the line segment W and the width H by performing multiple regression analysis using past plant data, and each variable of the estimated function. The control target range may be determined by substituting a value indicating the current water quality of raw water and mixed water into.

The flocculant injection control apparatus 1d of the fourth embodiment configured as described above can determine the limit value of the control target value according to the water quality of the raw water and the mixed water, so that the flocculant injection rate is more accurate. It is possible to make a good decision. Specifically, the flocculant injection control device 1d can control the flocculant injection rate so that the flocculant state does not deviate from the range in which floc aggregation proceeds appropriately. Even if it exists, the processed water of the stable water quality can be produced | generated.

According to at least one embodiment described above, feedback control is performed with the floc aggregation state in the water to be treated, into which the flocculant is injected, as the control amount, and the injection amount of the flocculant into the water to be treated as the operation amount. Control target value determination that determines the target value of the control amount in the feedback control and the coagulant injection control unit that performs the control based on the quality of the raw water that is the treated water before the coagulant is injected and the quality of the mixed water The amount of the flocculant injected can be controlled more appropriately.

Note that the mixed water quality meter 42 is not necessarily provided in the water distribution pipe between the rapid mixing basin 4 and the flock formation pond 5 as long as the water quality of the mixed water can be measured. For example, the mixed water quality meter 42 may be provided in the vicinity of the outflow portion of the rapid mixing pond 4. Further, the pH adjusting agent and the activated carbon may be injected into the water to be treated in a water distribution pipe between the landing well 3 and the rapid mixing basin 4.

Further, the limit input unit 14, the target value adjustment unit 15, and the limit determination unit 16 may be provided in the flocculant injection control device 1 of the first embodiment and the second embodiment.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

Claims

A flocculant injection control unit that performs feedback control with the amount of flocculant injected into the water to be treated as a control amount, and the amount of flocculant injected into the water to be treated as an operation amount;
A control target value determining unit that determines a target value of the control amount in the feedback control based on the turbidity of the sedimentation basin for sedimenting flocs in the mixed water and its target value;
A flocculant injection control device.
The control target value determination unit changes according to the current injection amount of the flocculant based on the current state of the raw water that is the water to be treated before the flocculant is injected and the current state of the mixed water. Predict turbidity of sedimentation basin by multiple regression analysis,
The flocculant injection control device according to claim 1.
The state of the raw water is represented by turbidity, pH, alkalinity, water temperature, conductivity, chromaticity, ultraviolet absorbance or flow rate of the raw water,
The state of the mixed water is represented by the pH, alkalinity, conductivity, flocculant injection rate, activated carbon injection rate or stirring strength of the mixed water, and the floc state of the floc.
The flocculant injection control device according to claim 2.
The control target value determining unit includes the variable based on the deviation of the water quality of the water to be treated before and after injecting the flocculant as an explanatory variable, and performs the multiple regression analysis.
The flocculant injection control device according to claim 2.
The control target value determining unit determines a target value of the control amount based on a deviation between an actual measurement value of the turbidity of the sedimentation basin and a predetermined target value of the turbidity.
The flocculant injection control device according to claim 1.
It is determined whether or not the control target value determined by the control target value determination unit is within a predetermined range. If the control target value is outside the range, the control target value is set to the range. A target value adjustment unit that adjusts to a value within and outputs to the flocculant injection control unit,
The flocculant injection control device according to claim 1.
A limit determination unit that determines the range related to the adjustment of the control target value based on the temperature of the water to be treated and the pH or alkalinity;
The flocculant injection control device according to claim 6.
An agglomeration state measurement unit that measures the aggregation state of flocs in the mixed water based on the electrophoresis speed of flocs contained in the mixed water;
The flocculant injection control device according to claim 1.
An agglomeration state measurement unit that measures the aggregation state of floc in the admixture water based on the zeta potential of the admixture water, the flowing current value or the amount of colloidal charge;
The flocculant injection control device according to claim 1.
A flocculant injection control step in which the floc aggregation state in the water to be treated into which the flocculant is injected is a control amount, and the amount of flocculant injected into the water to be treated is an operation amount to perform feedback control;
A control target value determining step for determining a target value of the control amount in the feedback control based on the turbidity of the sedimentation basin for sedimenting flocs in the mixed water and the target value;
A flocculant injection control method.
A flocculant injection control step in which the floc aggregation state in the water to be treated into which the flocculant is injected is a control amount, and the amount of flocculant injected into the water to be treated is an operation amount to perform feedback control;
A control target value determining step for determining a target value of the control amount in the feedback control based on the turbidity of the sedimentation basin for sedimenting flocs in the mixed water and the target value;
A computer program for causing a computer to execute.