JP4492473B2 - Flocculant injection control device and method - Google Patents

Description

  The present invention relates to operation management of a water purification plant that appropriately injects a flocculant in response to the turbidity of raw water to obtain stable purified water.

  In Patent Document 1, in order to control the flocculant injection rate to an optimum value when the raw water turbidity frequently changes ([0010]), a weighting coefficient is obtained from the deviation of the streaming potential D, and a feedforward controller and It is configured to correct the output value of the flocculant injection rate of the feedback controller ([0049]). Further, the relationship between the coagulant injection rate and the flow potential is classified by turbidity so as to maintain a characteristic curve ([0046]), and the coagulant injection rate is determined as an exponential function using coefficients and constants. ([0079]).

JP 2003-284904 A

  In Patent Document 1, the coagulant injection rate is determined by an exponential equation and then corrected by a weighting factor. When automatically calculating the coagulant injection rate, all the influence factors of the coagulation sedimentation treatment are not considered.

  The present invention addresses the above-mentioned problems of the prior art, and the object of the present invention is to determine the coagulant injection rate with the turbidity removal coefficient, which is a coefficient including all influential factors of the coagulation sedimentation treatment, and is stable. Another object of the present invention is to provide a flocculant injection control capable of providing high quality coagulated sediment treated water.

  The present inventors diligently conducted a coagulation sedimentation experiment from a low turbidity to an ultrahigh turbidity of 10,000 degrees using the turbidity of river surface water. Although details will be described later, from the results of this experiment, in the range where the turbidity of the coagulated sediment treated water is good, the turbidity of the coagulated sediment treated water is correlated with the turbidity of the raw water and the injection rate of the coagulant at that time. Obtaining knowledge that can be expressed by the formula, the present invention has been achieved.

  Based on this knowledge, the present invention provides an index of the relationship between the turbidity of the coagulated sediment treated water, the raw water turbidity of the process in which the coagulated sediment treated water is injected with the coagulant, and the coagulant injection rate in the process. The index coefficient value is used as a turbidity removal coefficient, and a necessary flocculant injection rate is calculated based on the turbidity removal coefficient to control the flocculant injection amount.

  The turbidity removal coefficient includes all influencing factors of the coagulation sedimentation treatment, and has an effect of being able to determine the coagulant injection rate simply and appropriately and providing stable and high quality coagulation sedimentation water.

  The purpose of providing operation management of the water purification process that can inject the flocculant appropriately from low turbidity to ultra-high turbidity, the amount of flocculant injected based on the turbidity removal coefficient obtained by our experimental findings Realized by seeking. Hereinafter, embodiments will be described with reference to the drawings.

  A first embodiment of the present invention is shown in FIG.

  A first embodiment of the present invention is shown in FIG. In FIG. 1, the water purification process has a chemical mixing pond 2, a flock formation pond 3, and a settling basin 4 as main components. The raw water 1 containing turbidity is injected with the flocculant 9 from the flocculant injection facility 8 in the chemical mixing pond 2. 7 is a flocculant storage tank. As the aggregating agent, inorganic or high molecular materials such as aluminum and iron are used. In the chemical mixing pond 2, the flocculant is uniformly mixed with the raw water by the stirrer 201, and the suspended matter and the flocculant are combined to form a micro floc that becomes the core of the floc. The micro floc grows by the stirrer 301 operated at a slower speed than the stirrer 201 in the floc formation pond 3 and becomes a coarse floc. The coarse floc settles in the sedimentation basin 4, and the supernatant liquid (coagulated sediment treated water) 5 from which the turbidity has been removed is subjected to predetermined treatment (filtration and sterilization) in the subsequent stage and then distributed as purified water. The floc settled and separated in the settling basin 4 is discharged out of the system as a sludge.

In such a water purification process at the water purification plant, the coagulant injection control device 10 that controls the injection of the coagulant has a coagulant injection amount calculator 33, a controller 34, and a coagulant injection rate calculator 36. The flocculant injection control device 10 does not have the turbidity removal coefficient calculator 32 as described later in the second embodiment, and it is only necessary to use the turbidity removal coefficient. In order to simplify the description, an example having the turbidity removal coefficient calculator 32 will be described. The coagulant injection rate calculator 36 is a means for calculating the coagulant injection rate using the turbidity removal coefficient k1. There are several examples of its use, and an example in which the coagulant injection rate is directly obtained using the turbidity removal coefficient k1 is described in Example 1, and other examples are used without using the turbidity removal coefficient k1. Example 5 in which the flocculant basic injection rate is calculated using an arithmetic expression and the flocculant injection rate is corrected by correcting the flocculant basic injection rate using the turbidity removal coefficient k1 is described in Example 5. . There are various methods of using the turbidity removal coefficient as in Examples 1, 2, and 5.

The turbidity T in the raw water 1 measured by the turbidimeter 22 is input and stored in the turbidity removal coefficient calculator 32. The turbidity removal coefficient calculator 32 receives the turbidity t of the coagulated sediment treated water 5 measured by the turbidimeter 22B and the coagulant injection rate C stored in the coagulant injection rate calculator 36. In the turbidity removal coefficient calculator 32, the turbidity ta of the current coagulation sedimentation treated water 5, the raw water turbidity Ta when the coagulation agent 9 is injected into the coagulation sedimentation basin water, and the coagulant injection rate at that time Based on Ca, the turbidity removal coefficient k1 is calculated by an exponential expression of the expression (1) or a logarithmic expression of the expression (2) obtained by modifying the expression (1). Let τ be the time from when the flocculant is injected to the time when the current turbidity ta is measured. Ta inputs the raw water turbidity data at a time point that is τ later than the time when the current turbidity ta is measured.
For Ca, the data of the flocculant injection rate C at the time point that goes back by τ from the time when the current turbidity ta is measured is input.

ta = Ta · e ^{-k1 · Ca} (1)
k1 =-(ln (ta / Ta)) / Ca (2)
FIG. 2 shows the experimental results of the present inventors, in which the initial turbidity and the flocculant injection amount are changed, and the turbidity of the precipitate supernatant is measured. Generally, in the water purification process, the turbidity target value of the coagulated sediment treated water 5 is set to 10 degrees or less. From FIG. 2, when the turbidity becomes 10 degrees or less, the relationship between the supernatant turbidity t and the flocculant injection rate C is a straight line with the initial turbidity T as an intercept, that is, an exponential expression t =
It was found that T · e ^{−k · C} can be expressed. This relationship could be expressed in the same form even if the initial turbidity was different. By the way, the slope, which is the degree of turbidity reduction with respect to the flocculant injection rate, changes under the influence of the initial turbidity. This means that, for example, when the turbidity of the coagulation sedimentation treated water 5 is 10 degrees and correction is made to the target value of 1 degree, it is necessary to change the coagulation sedimentation characteristics. The slope is an exponential coefficient k in the exponential formula and is called a turbidity removal coefficient. The turbidity removal coefficient k is a coefficient that covers the influence of factors other than the raw water turbidity and the amount of the flocculant in the floc formation and precipitation process after the flocculant is injected. In other words, if the flocculant injection rate and the correction rate thereof are obtained based on the turbidity removal coefficient k, the flocculant injection management considering factors other than the raw water turbidity and the flocculant can be performed.

The flocculant injection rate calculator 36 calculates the turbidity removal coefficient k1 from the turbidity removal coefficient calculator 32, the current raw water turbidity Ti, and the preset turbidity target value tm of the coagulation sedimentation basin treatment water (2). Substituting it into the logarithmic expression of the expression (3), which is a modified expression of the expression), calculates the coagulant injection rate Cm necessary to maintain the turbidity target value tm.

Cm =-(ln (tm / Ti)) / k1 (3)
In the equation (3), the flocculant injection rate Cm for setting the raw water turbidity Ti to the target value tm is calculated with the turbidity removal coefficient k1, but it can also be corrected by the coagulation sedimentation basin treatment water turbidity ta and the target value tm. Since the treated water turbidity ta is set to the target value tm, the correction rate ΔCm is obtained by setting Ti in equation (3) to ta.

ΔCm = − (ln (tm / ta)) / k1 (4)
These operational concepts are shown in FIG. The flocculant injection rate is manipulated in the direction of increasing if the treated water turbidity ta is equal to or higher than the target value and decreasing if the treated water turbidity tb is equal to or lower than the target value.

The coagulant injection amount calculator 33 calculates the coagulant injection amount Qc by multiplying the coagulant injection rate Cm from the coagulant injection rate calculator 36 by the raw water flow rate Q from the flowmeter 21. The controller 34 adjusts the flocculant injection facility 8 based on the deviation between the calculated flocculant injection amount Qc and the flocculant injection operation amount Qc ′ output from the flowmeter 24. The flocculant injection equipment 8 is a valve or a variable flow rate pump.

  In this way, the relationship between the turbidity of the treated water in the coagulation sedimentation basin at a certain point in time, the turbidity of the raw water at a certain point in time from a certain point in time, and the flocculant injection rate of the flocculant at a certain point in time from a certain point in time. By calculating the coagulant injection rate using the turbidity removal coefficient of the water purification process expressed as an exponential expression or logarithmic expression, and calculating the coagulant injection rate using this turbidity removal coefficient, Thus, the coagulant injection rate can be determined easily and appropriately.

  A second embodiment of the present invention is shown in FIG. If the equation (2) is substituted into the equation (3), the coagulant injection rate Cm can be directly calculated based on the equation (5) considering the turbidity removal coefficient k1 without installing the turbidity removal coefficient calculator 32. . The coagulant injection rate calculator 36 has a function of storing the past coagulant injection rate and turbidity value, and calculates the coagulant injection rate Cm necessary to maintain the turbidity target value tm by the equation (5). .

Cm = Ca (ln (tm / Ti)) / (ln (ta / Ta)) (5)
The processing after the coagulant injection amount calculator 33 is the same as that of the second embodiment. Even if the turbidity removal coefficient is incorporated in the calculation of the flocculant injection rate as shown in the equation (5), as in the case of Example 1, it includes the influence factors of the coagulation sedimentation treatment and is simple and appropriate. Can be determined.

A third embodiment of the present invention is shown in FIG. 50 is a batch type coagulating sedimentation apparatus in which a part 1B of the raw water 1 is introduced. FIG. 6 shows a configuration example of the batch type coagulation sedimentation apparatus 50. Reference numeral 503 denotes a coagulation sedimentation step, in which a predetermined amount v of the feed water 1B is put into the container J1 having a predetermined volume by operating the valves V1 and V2. A predetermined amount of the flocculant 9B is injected by operating the valve V3 while the stirrer M1 is in operation. After the injection, the stirrer M1 is stopped after a predetermined number of rotations and time. After the stop, the valve V4 is opened after a lapse of a predetermined time, and the turbidity t2 of the sediment supernatant is measured with the turbidimeter 22C. The turbidity meter 22C also measures the turbidity t1 before injecting the flocculant into which the raw water 1B is introduced. Further, the flocculant injection amount q is measured by the flow meter 24B. After the turbidity t2 of the sediment supernatant is measured, the valve V5 is operated to discharge the internal liquid in the container J1, and the above operation is repeated to periodically implement the coagulation sedimentation characteristics. These operations are executed by the sequence circuit 502 in response to an operation command from the timing adjustment circuit 501.

  The measured values of the turbidimeter 22C and the flow meter 24B are stored in the database 504. The stored data is input to the turbidity removal coefficient calculator 505 by the timing adjustment circuit 501, and the turbidity removal coefficient k2 is calculated by equation (6). The coagulant injection rate C is determined by q / v.

k2 =-(ln (t2 / t1)) / C (6)
The flocculant injection rate calculator 36 receives the turbidity removal coefficient k2 from the turbidity removal coefficient calculator 505 and the current raw water turbidity Ti from the turbidimeter 22, and sets the coagulation sedimentation basin water set in advance. Based on the turbidity target value tm, the coagulant injection rate Cm necessary to maintain the turbidity target value tm is calculated by the equation (7).

Cm =-(ln (tm / Ti)) / k2 (7)
The processing after the coagulant injection amount calculator 33 is the same as that of the first embodiment.

  The turbidity removal coefficient calculator 505 of the batch type coagulating sedimentation apparatus 50 can be configured as the coagulant injection control apparatus 10. Other timing adjustment circuit 501, sequence circuit 502, and database 504 can also be configured as the coagulant injection control apparatus 10.

As in this example, a portion of raw water is introduced into a container of a predetermined volume, and the turbidity before injection of the flocculant in the batch type coagulation sedimentation apparatus in which the flocculant is injected, stirred and allowed to stand, and after standing for a predetermined time. A batch formula that calculates the turbidity removal coefficient of batch-type coagulation sedimentation expressed as an exponential expression or logarithmic expression of the relationship between the turbidity of the sediment supernatant and the flocculating agent injection rate in the process of obtaining this supernatant turbidity Provide turbidity removal coefficient calculation means,
The flocculant injection rate calculation means is used to calculate the turbidity removal coefficient of batch-type coagulation sedimentation, the turbidity removal rate of raw water at a certain point in time, and the calculation formula composed of preset target values of the turbidity of treated water. By calculating the rate, the flocculant injection corresponding to the current raw water quality and turbidity can be carried out, and time delay can be prevented.

  A fourth embodiment of the present invention is shown in FIG. FIG. 7 shows an example of correcting the flocculant injection rate with the turbidity ta of the coagulation sedimentation treated water 5 in the configuration of the third embodiment. In addition to the equation (7), the coagulant injection rate calculator 36 calculates the equations (2) and (4) to obtain the correction rate ΔCm. The coagulant injection amount calculator 33 outputs an injection rate Cm * obtained by adding Cm in Expression (7) and ΔCm in Expression (4). The processing after the coagulant injection amount calculator 33 is the same as that of the first embodiment.

  With this correction, appropriate coagulant injection management can be performed in consideration of the influence of factors different from the batch type coagulation sedimentation apparatus, such as the stirring and mixing state of the water purification process, the reaction, and the residence time.

A fifth embodiment of the present invention is shown in FIG. The coagulant injection control apparatus 10 includes a basic injection rate calculator 37 and an injection rate correction calculator 38 in addition to the coagulant injection amount calculator 33, the controller 34, and the coagulant injection rate calculator 36. The basic injection rate calculator 37 receives a flocculant injection rate calculation formula corresponding to the quality of the raw water 1. Typical water qualities that are factors affecting the coagulation sedimentation include turbidity Ti, alkalinity AL, pH, water temperature Th, and the like. These are measured by the water quality meters 22, 25, 26 and 27 and input to the basic injection rate calculator 37. The basic injection rate calculator 37 is preliminarily inputted with, for example, an injection model equation (8) corresponding to these water qualities, and calculates a basic coagulant injection rate Cm. a, b, c, and d are constants.

Cm = a.Ti + b.AL + c.pH + d.Th (8)
The injection rate correction calculator 38 receives the raw water turbidity Ti, the coagulation sedimentation basin treatment water turbidity ta, and the coagulant injection rate Cm ′ operated for a predetermined time from the coagulant injection rate calculator 36 ( 2) Calculate the turbidity removal coefficient k1 by the equation. Further, the correction rate ΔCm is obtained by the equation (4). The coagulant injection rate calculator 36 adds the basic coagulant injection rate Cm and the correction rate ΔCm to obtain the coagulant injection rate Cm * to be operated and outputs it to the coagulant injection amount calculator 33. The processing after the coagulant injection amount calculator 33 is the same as that of the first embodiment. The correction factor ΔCm can also be obtained using the batch-type turbidity removal coefficient k2 of the fourth embodiment.

  As in this example, when the flocculant injection rate is calculated with a representative water quality that is an influence factor of the coagulation sedimentation, and when feedforward control of the flocculant is performed at this injection rate, the turbidity with respect to the calculated injection rate By adding a correction based on the removal coefficient, flocculant injection management that reflects unintended water quality, turbidity properties, and process-derived influence factors at the flocculant injection rate calculated as a representative water quality can be performed.

A trial calculation example of the coagulant injection rate will be described below with reference to FIG. As a trial calculation procedure of the flocculant injection rate, the raw water turbidity is set (FIG. 9 (A)), the treated water turbidity is set (FIG. 9 (B)), and the calculation of the flocculant injection rate by the exponential function described later is performed. Trial calculation using the equation (FIG. 9C), calculating the removal coefficient K of the above-described embodiment (FIG. 9D), and using the removal coefficient of FIG. 9D, the coagulant injection rate Cm of the above-described embodiment. Is calculated (FIG. 9C), and ΔCm of the above-described embodiment is calculated (FIG. 9C). 9A to 9D represents the time (h).

  FIG. 9A shows the daily fluctuation of the raw water turbidity, which was changed in the range of 5 to 30 degrees.

  Fig. 9 (B) shows the turbidity of the coagulated sediment treated water, which is linked to the change in the raw water with a delay in the residence time, and changes in the range of 0.5 to 1.5 degrees (average 1 degree). It was. The well-known injection rate calculation formula to be compared with the trial calculation is the following formula depending on the raw water turbidity Ti.

C = a · Ti ⁿ + b (a, b: constant, n: exponential constant)
FIG. 9C shows the result of trial calculation of the injection rate C under the conditions of constants a = 2, b = 3, and n = 0.5. Since all except the raw water turbidity Ti are constants, the injection rate C is synchronized with the turbidity Ti.

  FIG. 9D shows the result of obtaining the turbidity removal coefficient k using the raw water turbidity taking account of the residence time (3h), the coagulation precipitation water turbidity, and the injection rate C. In this trial calculation, it was assumed that the flocculant was injected at the injection rate C of FIG. 9C with respect to the raw water turbidity of FIG. It can be seen that the turbidity removal coefficient k varies.

The injection rate Cm of the present invention was estimated using this turbidity removal coefficient k. Further, the treated water turbidity target value tm was set to 1, the correction rate ΔCm was obtained, and the corrected injection rate Cm + ΔCm was estimated. The results of Cm and Cm + ΔCm are also shown in FIG. The average of the three types of injection rates is not very different, but if the turbidity removal coefficient k is used, the change in the injection rate is large, and the injection rate reflecting the various factors affecting the turbidity of the treated water, that is, the cohesiveness, is set. Has been.

  In addition, various flocculant injection methods corresponding to changes in turbidity of raw water have been proposed. For example, there is a method of operating based on a flocculation agent injection method created in consideration of turbidity of raw water, and also flocculation factors such as alkalinity, pH, and water temperature of raw water in addition to raw water turbidity. Although this method can deal with fluctuations in raw water quality with feedforward, it treats the nature of turbidity as a universal one, and it is difficult to maintain an appropriate injection rate continuously. In particular, it cannot cope with changes in properties such as during rainfall.

  As another conventional example, there is a method in which different injection types are prepared and operated for low turbidity (up to several tens of degrees) such as in fine weather and high turbidity (several tens to several hundred degrees) during rainy days. . This method also treats the nature of turbidity as universal in the turbidity range of a specific injection type, and it is difficult to continuously maintain an appropriate injection rate. In particular, since the injection rate is discontinuous in the vicinity of the turbidity at the boundary, proper coagulation sedimentation is impaired.

In addition, as another conventional example, in order to reflect the difference in floc formation state and coagulation sedimentation characteristics due to changes in turbid properties, an injection type coagulant injection rate calculation value considering the floc formation factors of raw water quality such as turbidity is calculated. There is a feedback addition method in which the turbidity of coagulated sediment treated water and the floc shape feature amount after injecting the coagulant are measured, and the injection rate is corrected by deviation from the target value. The correction method is
PID control and deviation amount are multiplied by a certain coefficient to make them proportional. However, there are various kinds of water quality such as river surface water, which affects floc formation and coagulation sedimentation characteristics. Many substances that are not considered in the injection type also affect the turbidity of coagulated sediment treated water. PID control and deviation ratio correction do not truly reflect the quality of raw water and turbidity, but are always appropriate. Can not maintain the correct flocculant injection control.

  In addition, as another conventional example, in response to ultra high turbidity (several hundred to several thousand degrees) raw water, a flocculant is pre-injected into the raw water supply line to the water purification plant, and water to be injected in the field A two-stage injection method for reducing the turbidity to a predetermined range has also been proposed, but there is no consideration of the turbidity properties, and it is difficult to continuously maintain an appropriate injection rate.

  In addition, as other conventional examples, the turbid particle size and number of raw water and coagulation sedimentation treatment water are measured with a fine particle counter and the coagulant is operated, and the turbidity and conductivity of raw water and the flow immediately after the coagulant injection There is a method of operating the flocculant by measuring the current. However, fine particle counters and flow ammeters are not applicable to high turbidity or ultra-high turbidity liquids because the measurement error increases as the turbid particles become denser. In addition, these measuring instruments need to guide the liquid to be measured to a narrow detection section, which causes blockage of the piping system and adhesion of turbidity to the detection section, resulting in major problems in terms of measurement accuracy degradation and maintenance. .

  Compared to these conventional examples, the above example can determine the coagulant injection rate with the turbidity removal coefficient, which is a coefficient that includes all the influence factors of the coagulation sedimentation treatment, and provides stable and high quality coagulation sedimentation treatment water. Possible flocculant injection control.

  Note that the flocculant injection control apparatus of the above embodiment is configured by a computer having a CPU, a memory, an input / output unit, and the like, and a program for performing the above-described arithmetic processing is executed by the CPU.

  In the above embodiment, various arithmetic units have a data storage function. However, a database for separately storing measured values and arithmetic values may be installed and output to the arithmetic units as necessary.

  Moreover, although the turbidity and the flocculant injection rate have been described in terms of the point measurement value and the calculation value, a moving average value for a predetermined time may be used.

  The present invention is a process for producing industrial water in addition to a general water purification process composed of a flocculant admixing basin, a flock formation pond and a sedimentation basin, and a water purification process having sand filtration and membrane-based filtration equipment in the subsequent stage of the sedimentation basin. Furthermore, it can be applied to a water purification process in which advanced treatment equipment such as ozone treatment is added to the subsequent stage.

It is a block diagram explaining 1st Example of this invention. It is a figure explaining the relationship between the turbidity and the flocculant injection rate in 1st Example of this invention. It is a figure which shows the relationship between the turbidity and the coagulant injection rate which are supplementarily demonstrated in 1st Example of this invention. It is a block diagram explaining 2nd Example of this invention. It is a block diagram explaining 3rd Example of this invention. It is a block diagram explaining the batch type coagulation sedimentation apparatus part in 3rd Example of this invention. It is a block diagram explaining 4th Example of this invention. It is a block diagram explaining 5th Example of this invention. It is a trial calculation example of the flocculant injection rate explaining the 6th example of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1B ... Raw water, 2 ... Chemical mixing pond, 3 ... Flock formation pond, 4 ... Sedimentation basin, 5 ... Coagulation sedimentation water, 6 ... Waste mud liquid, 7 ... Coagulant storage tank, 8 ... Coagulant injection equipment, 9 , 9B ... flocculant, 10 ... flocculant injection control device, 21, 24, 24B ... flow meter, 22, 22B, 22C ... turbidity meter, 25, 26, 27 ... water quality meter, 32, 505 ... turbidity removal coefficient Calculation unit, 33 ... flocculant injection amount calculation unit, 34 ... controller, 36 ... flocculant injection rate calculation unit, 37 ... basic injection rate calculation unit, 50 ... batch type coagulation sedimentation apparatus.

Claims (10)

In the flocculant injection control device that performs the injection control of the flocculant for the water purification process of injecting the flocculant and coagulating and sedimenting the turbidity of the raw water in the coagulation sedimentation basin,
The turbidity of the treated water in the coagulation sedimentation basin at a certain point in time, the turbidity of the raw water at a point that is earlier than the certain point in time, and the flocculating agent injection rate of the flocculant at the point that is a certain point later than the certain point in time A flocculant injection rate calculating means for calculating the flocculant injection rate using the turbidity removal coefficient of the water purification process in which the relationship is represented by an exponential expression or logarithmic expression;
A flocculant injection amount calculating means for calculating the flocculant injection amount by multiplying the flocculant injection rate calculated by the flocculant injection rate calculating means and the flow rate of the raw water at a certain time;
Control means for controlling the flocculant injection facility based on the flocculant injection amount;
A flocculant injection control device comprising: In the flocculant injection control device according to claim 1,
When the flocculant injection rate calculating means calculates the flocculant injection rate using the turbidity removal coefficient of the water purification process, the turbidity removal coefficient of the water purification process, the turbidity of the raw water at a certain point in time, and A flocculant injection control apparatus that calculates the flocculant injection rate based on an arithmetic expression having a preset target value of the turbidity of the treated water. In the flocculant injection control device according to claim 1,
A portion of the raw water is introduced into a container of a predetermined volume, and the turbidity before injection of the flocculant in the batch type coagulation settling apparatus in which the flocculant is injected, stirred and left standing, and the turbidity of the precipitate supernatant after standing for a predetermined time. A batch-type turbidity removal coefficient calculation means for calculating the turbidity removal coefficient of batch-type coagulation sedimentation expressed by an exponential expression or logarithmic expression in relation to the degree of turbidity and the coagulant injection rate in the process of obtaining this supernatant liquid turbidity Have
The flocculant injection rate calculating means is based on an arithmetic expression configured with a preset target value of the turbidity removal coefficient of the batch-type coagulation sedimentation, the turbidity of the raw water at a certain time, and the turbidity of the treated water. And calculating a coagulant injection rate. In the flocculant injection control device according to claim 3,
The flocculant injection rate calculating means is based on an arithmetic expression comprising the turbidity removal coefficient of the water purification process, the turbidity of treated water in the coagulation sedimentation basin at a certain time, and the preset target value. The correction value of the flocculant injection rate to be maintained at the target value is calculated, and the flocculant injection rate calculated by including the turbidity removal coefficient of the batch type coagulation sedimentation is corrected by the correction value of the flocculant injection rate. A flocculant injection control device characterized by calculating an injection rate. In the flocculant injection control device according to claim 1,
For the water purification process in which the flocculant is injected and the turbidity of the raw water is coagulated and settled in the coagulation sedimentation basin, the basic coagulant injection rate is calculated based on the pre-set flocculant injection formula taking into account the turbidity of the raw water Agent basic injection rate calculation means,
The flocculant injection rate calculating means is based on an arithmetic expression configured with a preset target value of the turbidity removal coefficient, the turbidity of the treated water in the coagulation sedimentation basin at a certain time, and the turbidity of the treated water. A coagulant injection control device, wherein a coagulant injection rate correction value maintained at the target value is calculated, and the coagulant injection rate is calculated by correcting the coagulant basic injection rate with the correction value. . In the flocculant injection control method of the water purification process in which the flocculant is injected and the turbidity of raw water is agglomerated and settled in the coagulation sedimentation basin,
The turbidity of the treated water in the coagulation sedimentation basin at a certain point in time, the turbidity of the raw water at a point that is earlier than the certain point in time, and the flocculating agent injection rate of the flocculant at the point that is a certain point later than the certain point in time Calculate the coagulant injection rate using the turbidity removal coefficient of the water purification process, which expresses the relationship as an exponential expression or logarithmic expression,
Multiplying the calculated flocculant injection rate and the raw water flow rate at a certain point in time to calculate the flocculant injection amount,
A flocculant injection control method, wherein the flocculant injection equipment is controlled based on the flocculant injection amount. In the flocculant injection control method according to claim 6,
When calculating the coagulant injection rate using the turbidity removal coefficient of the water purification process, the turbidity removal coefficient of the water purification process, the turbidity of the raw water at a certain point in time, and the turbidity of the treated water are preset. A flocculant injection control method, wherein the flocculant injection rate is calculated based on an arithmetic expression having a target value. In the flocculant injection control method according to claim 6,
A portion of the raw water is introduced into a container of a predetermined volume, and the turbidity before injection of the flocculant in the batch type coagulation settling apparatus in which the flocculant is injected, stirred and left standing, and the turbidity of the precipitate supernatant after standing for a predetermined time. The turbidity removal coefficient of batch-type coagulation sedimentation expressed by an exponential expression or logarithmic expression, and the relationship between the degree and the coagulant injection rate in the process of obtaining this supernatant liquid turbidity,
When calculating the flocculating agent injection rate, the turbidity removal coefficient of the batch-type coagulation sedimentation, the turbidity of the raw water at a certain point in time, and an arithmetic expression configured with preset target values of the turbidity of the treated water The flocculant injection control method is characterized in that the flocculant injection rate is calculated based on the above. The flocculant injection control method according to claim 8,
When calculating the flocculating agent injection rate, based on the calculation formula configured with the turbidity removal coefficient of the water purification process, the turbidity of the treated water in the flocculation sedimentation basin at the certain time, and the preset target value Calculating the correction value of the flocculant injection rate to be maintained at the target value, and correcting the calculated flocculant injection rate including the turbidity removal coefficient of the batch type coagulation sedimentation with the correction value of the flocculant injection rate A flocculant injection control method characterized by calculating a flocculant injection rate. In the flocculant injection control method according to claim 6,
For the water purification process of injecting the flocculant and coagulating sedimentation of the raw water turbidity in the coagulation sedimentation basin, calculating the basic coagulant injection rate based on the preset flocculant injection formula taking into account the turbidity of the raw water,
When calculating the flocculating agent injection rate, the turbidity removal coefficient, the turbidity of the treated water in the coagulation sedimentation basin at a certain point in time, and an arithmetic expression composed of preset target values of the turbidity of the treated water A coagulant injection rate is calculated by calculating a correction value of the coagulant injection rate to be maintained at the target value, and correcting the coagulant basic injection rate with the correction value to calculate the coagulant injection rate Control method.

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