JPH03284304A - Control method for injecting flocculant - Google Patents

Abstract

PURPOSE:To suppress the variations in the turbidity of treated water and to reduce the amt. of flocculant to be injected by determining the amt. in accor dance with the compared result between the determined streaming current difference command and the measured streaming current difference value. CONSTITUTION:When the operation of a flocculating and settling device 10 is started, the optimum streaming current difference is appropriately selected by a setting device 21 each time when the measured raw water pH value is supplied from a raw water pH meter 17, and the difference is outputted to a comparator 23 as the command for the streaming current difference. The raw water not supplied with the flocculant and the raw water supplied with the flocculant are measured by a streaming current meter 19, the results are inputted to an arithmetic device 22, and the measured streaming current differ ence value is obtained and outputted to the comparator 23. The difference between the command for the streaming current difference and the measured streaming current difference value is obtained by the comparator 23, the com pared result is outputted to a controller 24, and the amt. of flocculant to be injected is determined in accordance with the supplied compared result and outputted to a flocculant injector 16.

Description

Detailed Description of the Invention (1) Purpose of the Invention [Field of Industrial Application] The present invention provides a method for applying a flocculant to raw water in order to flocculate suspended matter from the raw water, remove the precipitate, and discharge it as treated water. Regarding a flocculant injection control method that controls the injection amount of flocculant according to the properties of raw water during injection, in particular, it is possible to control the flocculant injection amount from the set value of the flowing current difference according to at least 10,000 of the hydrogen ion concentration index and temperature of the raw water. The present invention relates to a flocculant injection control method in which the amount of flocculant to be injected is determined so that the measured value of the flowing current difference approaches the determined target value of the flowing current difference.

[Prior Art] Conventionally, this type of flocculant injection control method involves injecting a flocculant (inorganic flocculant or organic flocculant) into raw water to flocculate suspended solids and remove precipitates, and then use the treated water as treated water. When discharging, the amount of flocculant to be injected is determined by the control device so that the measured flow current approaches the flow target value, which is determined based on empirical rules according to the measurement results of the turbidity of the treated water. Something was being proposed.

[Problems to be solved] However, in the conventional flocculant injection control method, the measured value of the flowing current approaches the target value of the flowing current determined based on a rule of thumb according to the measurement result of the turbidity of the treated water. Even if the amount of flocculant to be injected was changed immediately when the turbidity of the treated water changed, the residence time in the rapid stirring tank, slow stirring tank, and sedimentation tank would be the same. There is a drawback that the injection control of the flocculant is delayed, and (ii) it is not possible to sufficiently suppress fluctuations in the turbidity of the treated water due to fluctuations in the raw water properties, resulting in (iii) In order to maintain the turbidity of the treated water at a desired level regardless of changes in properties, the injection amount of the flocculant must always be set to a large value.

Therefore, in order to eliminate these drawbacks, the present invention sets the flowing current difference to the target value of the flowing current difference determined from the set value of the flowing current difference according to at least one of the hydrogen ion concentration index and temperature of raw water. It is an object of the present invention to provide a flocculant injection control method in which the injection amount of flocculant is determined so that the measured values of .

(2) Structure of the Invention [Means for Solving the Problems] The first means for solving the problems provided by the present invention is as follows. In a flocculant injection control method comprising controlling the injection amount of flocculant according to the properties of the raw water when injecting the flocculant into the raw water, the method includes: (a) a first step of measuring a hydrogen ion concentration index of the raw water; (a second step of measuring the flowing current of the raw water into which the cl coagulant has been injected; a third step of measuring the flowing current of the raw water into which the cl flocculant has been injected; a fourth step of calculating the measured value of the flowing current difference by subtracting the measured value of the flowing current measured in the third step from the value; a fifth step of selecting a set value of the flowing current difference according to the set value and determining the set value of the flowing current difference as the target value of the flowing current difference;
A sixth step of comparing the measured value of the flowing current difference calculated in the step of (gl), and a seventh step of determining the amount of coagulant to be injected according to the results of the comparison in the sixth step. A coagulant injection control method characterized by comprising:

The second solution to the problem provided by the present invention is that ``When a flocculant is injected into raw water in order to flocculate suspended solids from the raw water, remove the precipitate, and discharge it as treated water, the properties of the raw water are changed. In a flocculant injection control method, the flocculant injection amount is controlled according to the flocculant injection amount.

(a) A first step of measuring the temperature of the raw water; (b) A second step of measuring the flowing current of the raw water; (c) A third step of measuring the flowing current of the raw water into which the flocculant has been injected. (dl) A fourth step of subtracting the measured value of the flowing current measured in the third step from the measured value of the flowing current measured in the second step to calculate the measured value of the flowing current difference, (f) A fifth step in which a set value for the flowing current difference is selected according to the temperature of the raw water measured in the first step and determined as a target value for the flowing current difference, and [f] Determined in the fifth step. (g) comparing the target value of the flowing current difference calculated in the fourth step with the measured value of the flowing current difference calculated in the fourth step; and a seventh step of determining the amount of injection of a flocculant.

A third solution to the problem provided by the present invention is that ``When a flocculant is injected into raw water in order to flocculate suspended solids from raw water, remove precipitates, and discharge as treated water, the properties of the raw water are In the flocculant injection control method, which controls the injection amount of the flocculant according to , (c) a third step of measuring the flowing current of the raw water; fd) a fourth step of measuring the flowing current of the raw water into which the flocculant has been injected; (e) the flow measured in the third step. a fifth step of calculating the measured value of the flowing current difference by subtracting the measured value of the flowing current measured in the fourth step from the measured value of the current; a sixth step of selecting a set value of the flowing current difference according to the concentration index and the temperature of the raw water measured in the second step and determining it as a target value of the flowing current difference; a seventh step of comparing the target value of the flowing current difference calculated in the fifth step with the measured value of the flowing current difference calculated in the fifth step; and an eighth step of determining the injection amount of coagulant injection.

[Function] The first flocculant injection control method according to the present invention is based on the properties of the raw water when injecting the flocculant into the raw water in order to flocculate suspended water from the raw water, remove the precipitate, and discharge it as treated water. The amount of coagulant to be injected is controlled by Since it is equipped with 7 steps, (1) it has the effect of determining the injection amount of flocculant in immediate response to changes in the hydrogen ion concentration index of raw water, and fii) it has the effect of suppressing fluctuations in the turbidity of treated water. None, together with fiii) acts to reduce the amount of coagulant to be injected.

The second flocculant injection control method according to the present invention is characterized in that when a flocculant is injected into raw water in order to flocculate suspended water from raw water, remove precipitates, and discharge it as treated water, the flocculant is injected into the raw water according to the properties of the raw water. In particular, as specified as the second solution in the middle part of problem solving means 1, the method includes the first to seventh steps listed in (a to (g)). Therefore, (1v) it acts to determine the amount of coagulant injection in immediate response to changes in the raw water temperature, and as a result, it achieves the effect of (ii) fiii) above in the same way as the first flocculant injection control method described above. Eggplant.

The third flocculant injection control method according to the present invention is characterized in that when a flocculant is injected into raw water in order to flocculate suspended solids from raw water, remove precipitates, and discharge as treated water, the flocculant is flocculated according to the properties of the raw water. The injection amount of the agent is controlled, and in particular, as specified as the third solution in the latter part of problem solving means 1, (al to (comprising the first to eighth steps listed in section h1) (vl) It acts to determine the amount of flocculant injection in immediate response to changes in the hydrogen ion concentration index of the raw water and changes in the raw water temperature, and in turn, to the above-mentioned first and second flocculant injection control methods. In comparison, the effect of 1ii1 (iii) above is made more preferable.

[Example] Next, the flocculant injection control method according to the present invention will be specifically explained by giving preferred examples thereof and referring to the attached drawings.

However, the examples described below are described to facilitate or accelerate understanding of the present invention, and are not described to limit the present invention.

In other words, each element disclosed in the embodiments described below includes all design changes and equivalent substitutions that fall within the spirit and technical scope of the present invention.

Nimengdu - Blood Ω Sarari 1 FIG. 1 is a conceptual diagram showing a flocculating sedimentation processing apparatus in which flocculant injection control is executed according to the first embodiment of the flocculant injection control method according to the present invention. It is a diagram.

FIG. 2 is an enlarged cross-sectional view showing an example of a flowing ammeter provided in the coagulation-sedimentation treatment apparatus shown in FIG. 1.

Figures 3 (al to c) are operation explanatory diagrams for explaining the embodiment shown in Figure 1, in which the optimum flowing current, raw water flowing current, and optimum flowing current difference are plotted for raw water pH, respectively. .

FIGS. 4(a) to fdl are operation explanatory diagrams for explaining a specific example of the embodiment shown in FIG. The amount of agent injected and the turbidity of the treated water are plotted.

FIG. 5 is a conceptual diagram showing a coagulation-sedimentation processing apparatus in which flocculant injection control is executed according to the second embodiment of the flocculant injection control method according to the present invention.

FIG. 6 (al to (cl) are operation explanatory diagrams for explaining the embodiment in FIG. 5, in which the optimum flowing current, the raw water flowing current, and the optimum flowing current difference are plotted with respect to the temperature of raw water, respectively. .

FIGS. 7(a) to fdl are operation explanatory diagrams for explaining a specific example of the embodiment in FIG. The amount of agent injected and the turbidity of the treated water are plotted.

FIG. 8 is a conceptual diagram showing a coagulation-sedimentation processing apparatus in which flocculant injection control is executed according to the third embodiment of the flocculant injection control method according to the present invention.

9(at) to (c) are operation explanatory diagrams for explaining the embodiment in FIG. 8, in which the optimum flowing current, the raw water flowing current, and the optimum flowing current difference are plotted for raw water pn, respectively. .

1O(a) to fcl are other operation explanatory diagrams for explaining the embodiment in FIG. 8, in which the optimum flowing current, the raw water flowing current and the optimum flowing current difference are respectively plotted against the temperature of the raw water. ing.

FIGS. 11(at to 11e) are operation explanatory diagrams for explaining a specific example of the embodiment in FIG. The target value of , flocculant injection amount, and treated water turbidity are plotted.

First Example First, with reference to FIGS. 1 and 2, the first embodiment of the flocculant injection control method according to the present invention will be described. The configuration will be explained in detail while explaining the configuration of the precipitation processing apparatus.

The notification is a coagulation-sedimentation treatment apparatus in which injection control of a coagulant is executed by the coagulant injection control method according to the present invention, and which uses suspended water such as tap water, sewage, nitrogen urine, or industrial wastewater as raw water below C°.゛Josei°.

2) is supplied from a raw water supply source (not shown) through a raw water supply pipe 11A as shown by arrow A, and large foreign substances contained in the raw water (i.e., suspended water) are precipitated. Raw water (that is, suspended water) is supplied from the receiving well 12 for removal through the raw water supply pipe 11B, and the flocculant injected by rapid stirring is mixed with the raw water (that is, suspended water). A rapid stirring pond 13 is used to flocculate suspended solids to form aggregates (i.e., flocs), and a flocculant is injected from the rapid stirring basin 13 and raw water (hereinafter referred to as "rapid stirring oil") in which flocculant is injected and rapidly stirred to form flocs. There is a slow stirring basin 14 for slowly agitating the rapidly agitated oil spilled water to enlarge the aggregates, and suspension water (hereinafter referred to as "effluent water") provided from the slow stirring basin 14. A flocculant (an inorganic flocculant or an organic flocculant) is applied to a sedimentation basin 15 for settling the flocculates by leaving the slowly and slowly agitated clear runoff water still, and a rapid stirring basin 13 for forming flocculates. The rapid stirring pond 13 is equipped with a coagulant injection device 16 for injecting the coagulant.
A stirring member 13B is provided which is driven to rotate rapidly (that is, driven to rotate at a relatively high speed) by the stirring member 13A.

The slow stirring pond 14 includes a driving source (for example, an electric motor) 14
A stirring member 14B that is slowly rotationally driven by A (that is, rotationally driven at a relatively low speed) is provided. A discharge pipe (not shown) is provided at the bottom of the settling tank 15 to remove the settled aggregates as sludge. The flocculant injection device 16 includes a flocculant storage tank 16A for holding the flocculant, and a metering pump 16B for metering and supplying the flocculant from the flocculant storage tank 16A to the rapid stirring pond 13. has been done.

The coagulation-sedimentation treatment device (■) is also equipped with a hydrogen ion concentration index meter (hereinafter referred to as raw water H-), which is installed with respect to the raw water supply pipe 11B and is used to measure the hydrogen ion concentration index of raw water (hereinafter also referred to as raw water H-). The raw water pH meter 17 (also referred to as raw water pH meter ° A flow current meter 19 is used to alternately measure the flow current (hereinafter referred to as "flocculation flow current") of the raw water (i.e., suspension water) into which the flocculant has already been injected, and the arrow B from the sedimentation tank 15. As shown in the figure, the turbidity of the treated water (hereinafter referred to as ``treated water turbidity'') is installed for the treated water discharge pipe 11C for discharging the treated water.
The flow ammeter 19 is equipped with a treated water turbidity meter 20 for measuring the raw water supply pipe 1.
1B and a water sampling vibrator 19a from the rapid stirring pond 13B,
19a'', 19a''a and the samples taken alternately through the water sampling pump 19a'' (specifically raw water into which the flocculant has not yet been injected and raw water into which the flocculant has already been injected). - The card container 19A, which is temporarily held and used for measurement of the raw water flowing current and the coagulated flowing current, and then discharged to the rapid stirring pond 13B via the drainage vibrator 19b, and the inner peripheral surface of the cylindrical container 19A are separated from each other. two electrodes 19B and 19C disposed inside the cylindrical container 19A, and a piston 19E that is reciprocated by a power source 19D located outside the card container 19A to forcibly move the sample. , are connected to electrodes 19B, 19C via connecting wires 19c, 19d, and the current generated between electrodes 19B, ], and 9C is measured and amplified appropriately when the sample moves with the reciprocating motion of piston 19E. It includes an ammeter 19F that outputs raw water flowing current or aggregated flowing current to the arithmetic unit 22.

The measured value of the flocculant flow current by the flow current meter 19 will decrease if the amount of flocculant injected is not increased when the raw water flow rate or raw water turbidity increases, and if the raw water flow rate or raw water turbidity decreases, the flocculant flow current will decrease. If the injection amount is not decreased, it will increase. Therefore, in the present invention, the result of subtracting the cohesive flowing current from the raw water flowing current (hereinafter referred to as ``measured value of flowing current difference'') is output from the setting device 21 as described below. By controlling the injection amount of the coagulant so as to match the target value of the dynamic current difference, the need to pay attention to the raw water flow rate and raw water turbidity is eliminated. Since the treated water turbidity meter 20 is provided only for evaluating the flocculant injection control method according to the present invention, it may be removed if desired.

The coagulation-sedimentation treatment apparatus 10 further uses the raw water pH measured in advance in an appropriate manner and the ``optimal flow current difference'' described below.

is set and maintains a correlation therebetween, and based on that correlation, an optimum flowing current difference (hereinafter referred to as "setting value of flowing current difference") is determined according to the measured value of raw water pH given from the raw water pH meter 17. a setting device 21 for selecting an appropriate value and outputting it as a "target value of flowing current difference"; and a flowing ammeter 1.
The raw water flowing current and the cohesive flowing current measured by the flowing ammeter 19 connected to the water current meter 19 are temporarily held, and the "measuring value of the flowing current difference" is calculated by subtracting the cohesive flowing current from the raw water flowing current. A computing device 22 is connected to the setting device 21 and the computing device 22 to calculate the “target value of the flowing current difference” given from the setting device 21 and the “flowing current difference target value” given from the computing device 22. The comparison circuit 23 is connected to the comparison circuit 23 for comparing the measured value with the measured value, and the comparison result of the comparison circuit 23 (i.e.,
A control device for determining the amount of flocculant to be injected according to the difference between the target value of the flowing current difference and the measured value of the flowing current difference, and giving it to the flocculant injection device 16 as a flocculant injection control signal. It is equipped with 24.

In addition, with reference to FIGS. 1 to 3(a) to (c), the first embodiment of the flocculant injection control method according to the present invention will be described, whereby the flocculant injection control is executed. The operation will be explained in detail while explaining the operation of the coagulation and sedimentation treatment apparatus.

Raw water supply pipe 11 as raw water from a raw water supply source (not shown)
Suspended water supplied as shown by arrow A through A is supplied to a rapid stirring basin 13 through a raw water supply pipe 11B after large foreign substances are precipitated and removed in a landing well 12.

The suspended water (that is, raw water) supplied to the rapid stirring pond 13 is mixed with an appropriate amount of flocculant injected from the flocculant injection device 16 by rapid stirring, and the suspended matter is flocculated. In suspended water, aggregates (ie, flocs) are formed as suspended solids aggregate. The raw water in which aggregates have been formed in the rapid stirring basin 13 is supplied to the slow stirring basin 14 as rapidly stirring oil spill water.

In the slow agitation pond 14, the rapidly agitated oil spill water is slowly agitated to enlarge the aggregates.

Rapidly agitated oil spill water that has been slowly agitated in the slowly agitated pond 14 is
The oil is supplied to the sedimentation basin 15 as slowly agitated oil spill water.

In the sedimentation tank 15, the slowly agitated oil spill water is allowed to stand still, thereby allowing the aggregates to settle. The aggregates precipitated in the settling tank 15 are removed as sludge through a discharge pipe (not shown) formed at the bottom of the settling tank 15. On the other hand, sedimentation pond 15
Slowly agitated oil spill water with aggregate sedimentation removed in
The treated water is discharged as indicated by arrow B through the treated water discharge pipe 11C, and is supplied to a subsequent treatment device (not shown), or is discharged or reused as is.

Setting operation Prior to starting the operation of the coagulation sedimentation treatment equipment 10, the pH of the raw water and the optimum flow current difference (that is, the raw water corresponding to the state in which no flocculant has been injected yet) are adjusted in an appropriate manner. The result of subtracting the optimal flowing current "corresponding to when the desired coagulation state is achieved by injecting an appropriate amount of flocculant" from the flowing current)
Understand the relationship between The relationship between the pH of the raw water and the optimum flow current difference may be achieved by pre-operating the coagulation and sedimentation treatment device pressure, or by creating a scaled-down model of the coagulation and sedimentation treatment device 10, but here The following description assumes that this is achieved using a pH meter, a jar test device, and a flow ammeter attached to the jar test device.

The raw water pH is measured by feeding the collected raw water to a pH meter.

The optimum flowing current difference is obtained by measuring the raw water flowing current and the optimum flowing current with a flowing ammeter while repeating the jar test using a jar test device (see Fig. 3 (at to fcl)).
reference). Incidentally, the flowing current corresponding to the optimum injection amount of flocculant determined by the jar test (i.e., the injection amount of flocculant that can achieve the desired flocculation state) is considered to be the optimal flowing current (Fig. 3). (see (a)).

Repeat measurements of the raw water pH, raw water flowing current, and optimal flowing current to determine the R suitable flowing current difference corresponding to various raw water pHs (see Figure 3 fcl).

After that, the raw water pH and the corresponding optimum flowing current difference are sequentially set as one set in the setting device 21, and the raw water P)
Correlation between l and optimal flowing current difference (Fig. 3 fc)
? 2) is held in the setting device 21. For convenience of explanation,
Here, the optimum flowing current difference set in the setting device 21 is the set value of the flowing current difference.

Also called.

■Injection control operation When the operation of the coagulation and sedimentation treatment equipment starts, the water landing well 12
The pH of the raw water starts to be measured for the suspension water given to the rapid stirring property 13 as raw water. The measured value of the raw water pu is given to the setting device 21.

In the setting device 21, each time the raw water pH measurement value is given from the raw water pH meter 17, the optimum flowing current difference (i.e., After the set value of the flowing current difference is appropriately selected, it is outputted to the comparison circuit 23 as the ``target value of the flowing current difference.

In addition, in the flowing ammeter 19, the water sampling pump 19a'' and the water sampling vibrator 19a, 19.
a'', 19a- are taken alternately from the raw water supply pipe 11B and the rapid agitator 13 and given as samples to the cylindrical container 19A, and after being held for a time, are discharged to the rapid agitator 13 via the drainage vibrator 19b. The sample held in the cylindrical container 19A is forcibly moved by the reciprocating motion of the piston 19H, and the sample is moved between the electrodes 19B and 19C.
A current is generated between the two. The current generated between the electrodes 19B and 19C is measured by an ammeter 19F, appropriately amplified, and then provided to the arithmetic unit 22 as a raw water flowing current and a cohesive flowing current.

In the calculation bag @22, since the raw water flowing current and the cohesive flowing current are alternately given from the flowing ammeter 19, they are -
Temporarily held, the cohesive flowing current is subtracted from the raw water flowing current to obtain the "measured value of the flowing current difference", and the comparison circuit 2
Output for 3.

In the comparison circuit 23, the difference between the "target value of the flowing current difference" given from the setting bag M21 and the "measured value of the flowing current difference" given from the arithmetic unit 22 is determined, and the control is performed as a result of the comparison. The signal is output toward the device 24.

In the control device 24, the injection amount of the flocculant is determined according to the comparison result given from the comparison circuit 23 (that is, the difference between the target value and the measured value of the flowing current difference), and the flocculant injection control signal is determined. It is outputted to the flocculant injection device 16 as a. Incidentally, the control circuit 24 determines the injection amount of the flocculant so that the comparison result given from the comparison circuit 23 becomes ◯. Further, the initial value of the injection amount of the flocculant is determined by experience or a jar test performed separately.

In the flocculant injection device 16, the metering pump 16B is operated according to the flocculant injection control signal given from the control device 24, and an appropriate amount of flocculant is injected from the flocculant storage tank 16A toward the rapid stirring property 13. be done.

As described above, according to the present invention, the raw water p has a rapid stirring property of 13.
Since the injection amount of flocculant can be immediately changed in response to changes in H, it is possible to reliably suppress fluctuations in the turbidity of treated water while avoiding unnecessary increases in the injection amount of flocculant. - Duality! ±1 In addition, with reference to FIGS. 1 and 4 [a] to (dl), in order to further deepen the understanding of the first embodiment of the flocculant injection control method according to the present invention, specific numerical values will be explained. will be explained in detail.

Here, dam storage water is used as raw water, and a first coagulation and sedimentation treatment apparatus in which injection control of a coagulant is executed by a coagulant injection control method according to the present invention, and a coagulant injection control method disclosed as a prior art The coagulant was supplied to a second coagulation and sedimentation processing device in which injection control of the coagulant was executed.

1st. The second coagulation and sedimentation treatment device is equipped with a rapid stirring tank, a slow stirring tank, and a settling tank, all of which have the same structure, and the residence time of the rapid stirring tank, slow stirring tank, and settling tank is 3 minutes, respectively. 27 minutes and 2 hours and 30 minutes, the throughput of raw water (ie suspended water) was 100 m 3 /h, and polyaluminum chloride (so-called ``PAC'') was used as flocculant.

The pH of raw water decreased to 7°5 over time from the start of operation.
and 6.5 as shown in Figure 4 (al). Incidentally, raw water turbidity and raw water temperature each
It was almost constant at 0°C and 25°C. Furthermore, the target turbidity of the treated water was 2 degrees.

! Give! 1 In the first stage (that is, the period from 0:00 to 1:00), the raw water p measured by the raw water pH meter and given to the setting device is
Since H was constant at 7.5 (see Figure 4 (al),
The set value of the flowing current difference selected in the setting device according to the pH of the raw water (here, 7.5) was output as the target value of the flowing current difference, and was given to the comparison circuit. Therefore, the target value of the flowing current difference was -2.1 (see FIG. 4 (bl)).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison result was that the target value of the flowing current difference was kept constant, so it was maintained at 0.

In the control device, since the comparison result was maintained at O, the flocculant injection amount was maintained at 20 mg71, and was given to the flocculant injection device as a flocculant injection control signal (Figure 4 (
cl). Incidentally, 20 mg/j was determined by a jar test performed separately.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, slowly agitated oil spill water was allowed to settle and remove aggregates. However, since the residence time in the settling tank was 2 hours and 30 minutes, the raw water given to the rapid stirring tank at the start of operation had not yet flowed out of the settling tank as treated water. Therefore, the measurement results of the treated water turbidity meter are not plotted (see Figure 4+d+).
.

In the second stage (i.e. the period from 1 o'clock to 5 o'clock), the raw water p measured by the raw water pH meter and given to the setting device is
H gradually decreased from 7.5 to 6.5 (Fig. 4 (al.
(see), the set value of the flowing current difference selected in accordance with the pH of the raw water in the setting device was output as the target value of the flowing current difference, and was given to the comparison circuit. Therefore, the target value of the flowing current difference gradually decreased from -2.1 to nearly 14 (see FIG. 4(b)).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison results showed that the target value of the flowing current difference gradually increased as the pH of the raw water decreased.

In the control device, since the comparison result gradually increased, the injection amount of the flocculant was gradually increased while varying from 20 mg/j to 25 mg/j during the period from 1 o'clock to 5 o'clock, and the flocculant injection control signal was given to the flocculant injection device as (4th
Figure (C1e).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling basin was measured with a treated water turbidity meter, and it was 2 degrees during the period from 3:00 to 4:00, which corresponds to the first stage, which corresponds to the early stage of the second stage. During the period from 4 o'clock to 5 o'clock, the temperature increased from 2 degrees to nearly 3 degrees, and then decreased again to nearly 2 degrees (See Figure 4, FDL wA).

In the third stage (i.e. the period from 5:00 to 13:00),
Since the raw water pH measured by the raw water pH meter and given to the setting device was 6.5 (see Figure 4), the setting value of the flowing current difference selected according to the raw water pH in the setting device was: It was output as the target value of the flowing current difference and given to the comparison circuit.Therefore, the target value of the flowing current difference is -
4 (see Figure 4 fb)).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison result was that the target value of the flowing current difference was kept constant, so it was maintained at 0.

In the control device, since the comparison result was maintained at O, the flocculant injection amount was maintained at 25 mg/j and was given to the flocculant injection device as a flocculant injection control signal (Figure 4 (
See C).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the coagulant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring water as rapidly stirred oil spill water.

In the slow agitation method, rapidly agitated oil spill water was slowly agitated and then fed to the settling basin as slowly agitated oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling basin was measured using a treated water turbidity meter, and it was found that the turbidity of the treated water was close to 2 degrees (from 1.8 After decreasing to nearly 3 degrees, it increased to nearly 3 degrees, and then from nearly 3 degrees to 1 degree.
After decreasing to nearly 8 degrees, it increased to nearly 2 degrees, and remained close to 2 degrees with almost no fluctuation during the period from 8M to 13:00, which corresponds to the early to middle stage of the third stage (Figure 4 (dl) reference).

In the fourth stage (i.e., the period from 13:00 to 17vf), the raw water pH measured by the raw water pH meter and given to the setting device gradually increased from 6.5 to 7.5 (see Figure 4 (a)). ), the set value of the flowing current difference selected in accordance with the raw water p)l in the setting device was outputted as the target value of the flowing current difference and given to the comparison circuit. Therefore, the target value of the flowing current difference gradually increased from -4 to -21 (see Fig. 4fb).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison results showed that the target value of the flowing current difference gradually decreased as the pH of the raw water increased.

In the control device, as the comparison result gradually decreased, the flocculant injection amount was gradually decreased from 25 mg/(fi to 20 mg/j), and the flocculant injection control signal was given to the flocculant injection device ( (See Figure 4 [c)).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the coagulant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring water as rapidly stirred oil spill water.

In the slow agitation method, rapidly agitated oil spill water was slowly agitated and then fed to the settling basin as slowly agitated oil spill water.

In the settling basin, the slowly agitated oil spill water was allowed to stand still in order to settle and remove aggregates, and then was discharged together with the treated water.

The turbidity of the treated water discharged from the settling basin was measured using a treated water turbidity meter, and it was found that the period from 13:00 to 16:00, which corresponds to the latter half of the third stage, and the period from 16:00, which corresponds to the early stage of the fourth stage, During the period from 17:00 to 17:00, the temperature remained close to 2 degrees with almost no fluctuation (see Figure 4 (d+)).

In the fifth stage (i.e. from 17:00 to 24:00),
Since the raw water pH measured by the raw water pH meter and given to the setting device was 7.5 (see Figure 4 (a) e), the setting value of the flowing current difference selected according to the raw water pH in the setting device was 7.5. , was output as the target value of the flowing current difference and given to the comparison circuit. Therefore, the target value of the flowing current difference is −
2.1 (see Figure 4 (bl)).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison result was that the target value of the flowing current difference was kept constant, so it was maintained at 0.

In the control device, since the comparison result was maintained at O, the flocculant injection amount was maintained at 20 mg/j and was given to the flocculant injection device as a flocculant injection control signal (Figure 4 (
c).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the sedimentation basin was measured using a treated water turbidity meter, and found that it fluctuated slightly around 2 degrees during the period from 17:00 to 20:00, which corresponds to the middle to late stage of the 4th stage. , from 20:00 to 24, corresponding to the early to middle stage of the fifth stage.
It was maintained at 2 degrees during the period up to (see Figure 4 (dl)).

Comparison box 1 In the first stage (that is, the period from 0 o'clock to 1 o'clock), the raw water p measured by the raw water pH meter and given to the setting device is
H is 7.5 (see Figure 4 (al I)).

Since the elapsed time from the start of operation was less than the residence time (i.e. 3 hours) in the rapid stirring tank, slow stirring tank, and settling tank, and the turbidity of the treated water had not yet been measured as described below, the setting device did not output the turbidity. The target value of the flowing current applied to the comparator circuit was maintained at -3 based on a rule of thumb (see Figure 4 fb)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
It was decided to maintain it at 20 mg/j. The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal (see FIG. 4 (C1)).

Incidentally, 20 mg/j was determined by a jar test performed separately.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond according to the flocculant injection control signal.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, slowly agitated oil spill water was allowed to settle and remove aggregates. However, since the residence time in the settling tank was 2 hours and 30 minutes, the raw water given to the rapid stirring tank at the start of operation had not yet been discharged from the settling tank as treated water. Therefore, the measurement results of the treated water turbidity meter were not plotted and were not used to determine the target value of the flowing current (Figure 4 (d).
)reference).

In the second stage (i.e. the period from 1 o'clock to 5 o'clock), the raw water p measured by the raw water pH meter and given to the setting device is
H gradually decreased from 7.5 to 6.5 (Fig. 4 (al.
(Reference) Therefore, the target value of the flowing current output from the setting device and given to the comparison circuit is determined by the residence time (
In other words, during the period from 1 o'clock to 3 o'clock, when the treated water concentration had not yet been measured (as described below), it was maintained at -3 as in the first stage based on empirical rules, and the treatment was carried out in response to the first stage. During the period from 3 o'clock to 4 o'clock, when the water turbidity was 2 degrees as described below, it was maintained at -3 based on the empirical rule,
At 4 o'clock, when the turbidity of the treated water began to increase corresponding to the beginning of the stage, it was set to -2 based on empirical rules and was maintained until 5 o'clock (see Figure 4 (b)!!Q).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
20mg/j to 15mg/during the period from 1:00 to 4:00
It was determined that after decreasing monotonically to j, it increased from 15 mg/β to 17.5 mg/j during the period from 4 o'clock to 5 o'clock (see Fig. 4(C) I). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow agitation pond, the rapidly agitated oil effluent was slowly agitated and then fed to the settling basin as slowly agitated foam effluent.

In the settling basin, the slowly agitated foam effluent was allowed to stand still in order to precipitate and remove aggregates, and then was discharged as treated water.

The concentration of the treated water discharged from the settling pond was measured using a treated water turbidity meter, and was plotted because the raw water from the first stage had not yet been discharged as treated water during the period from 1:00 to 3:00. twice in the period from 3:00 to 4:00, corresponding to the first stage, and twice in the period from 3:00 to 4:00, corresponding to the first stage, and twice in the period from 3:00 to 4:00, corresponding to the first stage, and once at 4:00, corresponding to the beginning of the second stage.
It increased monotonically from 2 degrees to 4 degrees during the period from 5:00 to 5:00 (see Figure 4fd)).

In the third stage (i.e. the period from 5:00 to 13:00),
The raw water pI (raw water p measured by the meter and given to the setting device) was 6.5 (Figure 4 (B) Ip), but the turbidity of the treated water increased as described below due to the influence of the second stage. The temperature continued to increase from 4 degrees to nearly 95 degrees in the period from 5 o'clock to 7 o'clock, and continued to decrease from nearly 95 degrees to less than 1.5 degrees in the period from 7 o'clock to 13 o'clock, so the temperature was output from the setting device. The target value of the flowing current given to the comparator circuit at 5 o'clock is
After being set to -l based on 11, it was maintained until 6 o'clock, and at 6 o'clock, it was again set to ○ based on the empirical rule, and then it was maintained until 11 o'clock, and at 11 o'clock, it was again set to -1 based on the empirical rule, and then 13
(See Figure 4(b)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
17.5mg/j to 20m between 5:00 and 6:00
g/j and 20 mg between 6 and 7 p.m.
After increasing from 27.5 mg/l to 27.5 mg/l, it was maintained until 11 o'clock, and after 11 o'clock, it increased from 27.5 mg/l to 25 mg.
It was decided that after decreasing to /l, it would be maintained until 13:00 (see Figure 4fc). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow agitation pond, the rapidly agitated oil effluent was slowly agitated and then fed to the settling basin as slowly agitated foam effluent.

In the settling basin, the slowly agitated foam effluent was allowed to stand still in order to precipitate and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the sedimentation basin was measured with a treated water turbidity meter, and the turbidity ranged from 4 degrees to nearly 9.5 degrees during the period from 5 o'clock to 8 o'clock, which corresponds to the middle to late stage of the second stage. (Figure 4) dl l
'Sho).

In the fourth stage (i.e. the period from 13:00 to 17:00), the raw water pH measured by the raw water pH meter and given to the setting device gradually increased from 6.5 to 7.5 (Figure 4).
al), due to the effects of the latter half of the third stage or the early stage of the fourth stage, as described below (since the turbidity of the treated water was maintained at less than 2 degrees, the flow output from the setting device and given to the comparison circuit The target value of current was maintained at -1 based on the empirical rule from 13:00 to 16:00, decreased to -2 based on the empirical rule at 16:00, and then maintained until 17:00 (Figure 4 (bl) (I).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device. .

The control device adjusts the injection amount of coagulant depending on the comparison result.
It is maintained at 25+ag/j during the period from 13:00 to 14:00, and from 25■g/j to 3 during the period from 14:00 to 16:00.
It increased monotonically to nearly 7.5 mg/j, from 16:00 to 17:00.
from nearly 37.5 mg/j to 26 mg/j during the period up to
(Figure 4 (C)
1e). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling basin was measured using a treated water turbidity meter, and it was found that the period from 13:00 to 16:00, which corresponds to the latter half of the third stage, and the period from 16:00, which corresponds to the early stage of the fourth stage, The temperature remained below 2 degrees Celsius for both periods from 17:00 to 17:00.
Figure 4(d).

In the fifth stage (that is, the period from 17:00 to 24:00), the raw water pH measured by the raw water pH meter and given to the setting device was 7.5 (see Figure 4 (al)), and the influence of the fourth stage As described later, the turbidity of the treated water was maintained at less than 2 degrees, so the target value of the flowing current output from the setting device and given to the comparison circuit was - based on the empirical rule at 17:00.
After it was set to 2.5, it was maintained until 19:00, and at 19:00, it was again set to -3 based on empirical rules and maintained until 24:00 (see Figure 4 (bl-1)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
26mg/j to 20m during the period from 17:00 to 20:00
The amount of flocculant injected was determined to gradually decrease to 20 mg/j from 20:00 to 24:00 (see Figure 4(C)). This signal was given to the coagulant injection device as a control signal for injection of the agent.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

As measured by a treated water turbidity meter, the turbidity of the treated water discharged from the sedimentation pond decreased from less than 2 degrees to less than 1 degree during the period from 17:00 to 19:00, which corresponds to the middle to late stage of stage 4. It gradually decreases and gradually increases from 1 to 2 degrees during the period from 19:00 to 22:00, corresponding to the late stage 4 to early stage 5, and from 22:00, corresponding to the middle of stage 5. It was maintained at 2 degrees during the period up to 24 hours (Figure 4 f)
d)-Insho).

As is clear from the above description of 1 and 1, in Example 1, instead of the target value of flowing current and the measured value of flowing current of Comparative Example 1, a target value of flowing current difference and a measured value of flowing current difference were adopted. (ii) Compared to Comparative Example 1, it is possible to eliminate fluctuations in flowing current due to raw water properties, and (ii) compared to Comparative Example 1, the raw water pH can be reduced.
can suitably follow the fluctuations of fiii) Comparative Example 1
Compared to 5) Comparative Example 1, fluctuations in the turbidity of the treated water were reliably suppressed compared to 5) Comparative Example 1.

2. Also, with reference to FIGS. 5 to 7 (al to Cd), the second embodiment of the flocculant injection control method according to the present invention will be explained in which the flocculant injection control is executed. The structure and operation of the coagulation and sedimentation processing apparatus will be explained in detail.

As is clear from a comparison between FIG. 1 and FIG. 5, in the second embodiment, a raw water thermometer 18 is provided in place of the raw water pH meter 17, and the measured value of the raw water temperature and the difference in flowing current is calculated. This embodiment has substantially the same structure and operation as the first embodiment except for determining the amount of coagulant to be injected.

That is, in the second embodiment, the temperature of the raw water measured by the raw water thermometer 18 is equal to the raw water pn in the first embodiment.
It functions as an index equivalent to (Figure 6 (at~(c)
)reference).

Therefore, in order to simplify the explanation, we will explain the first
The same reference numerals as in the first embodiment are given to the same members as those included in the first embodiment, and detailed explanation thereof will be omitted.

In addition, in order to further deepen the understanding of the second embodiment of the flocculant injection control method according to the present invention, with reference to FIGS. This will be explained in detail by citing numerical values.

Here, dam storage water is used as raw water, and a first coagulation and sedimentation treatment apparatus in which injection control of a coagulant is executed by a coagulant injection control method according to the present invention, and a coagulant injection control method disclosed as a prior art The coagulant was supplied to a second coagulation and sedimentation processing device in which injection control of the coagulant was executed.

1st. Both of the second coagulation and sedimentation treatment equipment include a rapid stirring pond and #i! The residence time of the rapid stirring tank and sedimentation tank is 3 each.
minutes, 27 minutes and 2 hours and 30 minutes, the treatment capacity of the suspended water was 100 m''7, and polyaluminum chloride (so-called 'PAC'i) was used as flocculant.

The temperature of the raw water increases as time passes from the start of operation.
℃ and 15℃ as shown in FIG. 7(a). By the way, raw water turbidity and raw water pn are each 2
It was almost constant at 0 degrees and 7.5 degrees. Furthermore, the turbidity of the treated water was targeted at 2 degrees.

During the first stage (that is, the period from 0:00 to 1:00), the temperature of the raw water measured by the raw water thermometer and fed to the setting device was 25°C (see Figure 7 [a)]. Therefore, the setting value of the flowing current difference selected in the setting device according to the temperature of the raw water (here, 25° C.) was output as the target value of the flowing current difference, and was given to the comparison circuit. Therefore, the target value of the flowing current difference was -3 (see Figure 7(b)).
.

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current measured by the flowing current meter and the coagulated flow T4 flow is compared with the target value of the flowing current difference given from the setting device. , the comparison result was given to the control device. The comparison result was that the target value of the flowing current difference was maintained at O because the target value was constant.

In the control device, since the comparison result was maintained at O, the flocculant injection amount was maintained at 15 mg 7N, and was given to the flocculant injection device as a flocculant injection control signal (see Fig. 7).
c)), by the way, 15 mg/j was determined by a jar test carried out separately.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, slowly agitated oil spill water was allowed to settle and remove aggregates. However, since the residence time in the settling tank was 2 hours and 30 minutes, the raw water given to the rapid stirring tank at the start of operation had not yet been discharged from the settling tank as treated water. Therefore, the measurement results of the treated water turbidity meter are not plotted (see Figure 7 (dl-9)).

In the second stage (i.e. the period from 1 o'clock to 5 o'clock), the temperature of the raw water measured by the raw water thermometer and given to the setting device gradually decreased from 25 °C to 15 °C (Fig. 7 (a)
), the setting value of the flowing current difference selected in the setting device according to the temperature of the raw water was output as the target value of the flowing current difference and given to the comparison circuit. Therefore, the target value of the flowing current difference was maintained at -3 (Fig. 7(b)
(see l).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison results showed that the target value of the flowing current difference gradually increased as the temperature of the raw water decreased.

In the control device, since the comparison result gradually increased, the amount of coagulant injection was gradually increased while fluctuating from 15 mg/j to nearly 21 mg/j71 during the period from 1 o'clock to 5 o'clock, and as a coagulant injection control signal. given to the flocculant injection device (
(See Figure 7(c)).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling basin was measured with a treated water turbidity meter, and it was 2 degrees during the period from 3:00 to 4:00, which corresponds to the first stage, which corresponds to the early stage of the second stage. During the period from 4 o'clock to 5 o'clock, the temperature increased from 2 to nearly 3 degrees (Fig. 7fd)? (see).

In the third stage (i.e. the period from 5:00 to 13:00),
Since the temperature of the raw water measured by the raw water thermometer and given to the setting device was 15°C (see Figure 7 (a)), the setting value of the flowing current difference selected in the setting device according to the temperature of the raw water was , and was outputted as a target value of the flowing current difference and given to the comparison circuit. The target value of the flowing current difference was maintained at -3 (see FIG. 7(b)).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison result was that the target value of the flowing current difference was kept constant, so it was maintained at 0.

In the control device, since the comparison result was maintained at O, the flocculant injection amount was maintained close to 201T1 g/i and was given to the flocculant injection device as a flocculant injection control signal (
Figure 7 (see cl).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

As measured by a treated water turbidity meter, the temperature of the treated water discharged from the sedimentation basin ranged from nearly 3 degrees to nearly 1.7 degrees during the period from 5:00 to 8:00, which corresponds to the middle to late stage of the second stage. After that, it increased to nearly 3 degrees, and then decreased slightly from around 3 degrees, and remained near 2 degrees with almost no fluctuation during the period from 8:00 to 13:00, which corresponds to the early to middle stage of the third stage. (See Figure 7 fdl) a In the fourth stage (i.e. the period from 13:00 to 17:00), the temperature of the raw water measured by the raw water thermometer and given to the setting device gradually increased from 15 °C to 25 °C. (See FIG. 7 (al)), so the set value of the flowing current difference selected according to the temperature of the raw water in the setting device was outputted as the target value of the flowing current difference and given to the comparison circuit. The target value of the flowing current difference was maintained at -3 (7th
(See Figure fb).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison results showed that the target value of the flowing current difference gradually decreased as the temperature of the raw water increased.

In the control device, since the comparison result gradually decreased, the injection amount of the flocculant was gradually decreased from nearly 20 mg/j to nearly 15 mg/j, and was given to the flocculant injection device as a flocculant injection control signal ( (See Figure 7(c)).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling basin was measured using a treated water turbidity meter, and it was found that the period from 13:00 to 16:00, which corresponds to the latter half of the third stage, and the period from 16:00, which corresponds to the early stage of the fourth stage, The temperature remained close to 2 degrees for both periods from 17:00 to 17:00 (see Figure 7 (di)).

In the fifth stage (that is, the period from 17:00 to 24:00), the temperature of the raw water measured by the raw water thermometer and given to the setting device was 25°C (see Figure 7 (a)), so
The set value of the flowing current difference selected in the setting device according to the temperature of the raw water was outputted as a target value of the flowing current difference and given to the comparison circuit. Therefore, the target value of the flowing current difference was maintained at -3 (see FIG. 7(b)).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison result was that the target value of the flowing current difference was kept constant, so it was maintained at 0.

In the control device, since the comparison result was maintained at O, the flocculant injection amount was maintained at around 15 mg/9, and was given to the flocculant injection device as a flocculant injection control signal (Fig. 7 fc). Reference) B In the flocculant injection device, the flocculant was injected into the rapid stirring pond according to the flocculant injection control signal given from the control device.

The raw water into which the coagulant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the sedimentation basin was measured with a treated water turbidity meter, and the turbidity was 3 degrees and 1.5 degrees during the period from 17:00 to 20:00, which corresponds to the middle to late stage of the 4th stage. 20, which corresponds to the early to middle stage of stage 5.
It was maintained at 2 degrees in the period from
(see figure fdl I).

In the first stage (that is, the period from 0:00 to 1:00), the temperature of the raw water measured by the raw water thermometer and given to the setting device is 25°C (see Figure 7 (a) 1). Since the elapsed time from the start of operation was less than the residence time (i.e. 3 hours) in the rapid stirring tank, slow stirring tank, and sedimentation tank and the turbidity of the treated water had not yet been measured as described below, the setting device did not output the turbidity. The target value of the flowing current given to the comparator circuit was maintained at -3 based on an empirical rule (see FIG. 7 (bl)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
It was decided to maintain the concentration at 15 mg/j (Figure 7 (C)
I! 'Sho). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

Incidentally, 15+ng/l was determined by a jar test performed separately.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond according to the flocculant injection control signal.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, slowly agitated oil spill water was allowed to settle and remove aggregates. However, since the residence time in the settling tank was 2 hours and 30 minutes, the raw water given to the rapid stirring tank at the start of operation had not yet been discharged from the settling tank as treated water. Therefore, the measurement results of the treated water turbidity meter were not plotted and were not used to determine the target value of the flowing current (see FIG. 7 [dl)].

In the second stage (i.e. the period from 1 o'clock to 5 o'clock), the temperature of the raw water measured by the raw water thermometer and given to the setting device gradually decreased from 25 °C to 15 °C (Fig. 7 (a)
Therefore, the target value of the flowing current output from the setting device and given to the comparison circuit is set when the elapsed time from the start of operation is less than the residence time (i.e. 3 hours) in the rapid stirring pond, slow stirring pond and sedimentation basin. During the period from 1 o'clock to 3 o'clock, when the turbidity of the treated water had not yet been measured as described below, it was maintained at -3 based on the empirical rule as in the first stage. As mentioned below, even during the period from 3 o'clock to 4 o'clock when it was 2 degrees, it was maintained at -3 based on empirical rules,
At 4 o'clock, when the turbidity of the treated water began to increase corresponding to the beginning of the second stage, it was set to -2.5 based on empirical rules and was maintained until 5 o'clock (see Figure 7 (bl)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
15 mg/g to 5 mg between 1:00 and 4:00, #
Monotonically decreasing until close to 5 mg in the period from 4 to 5
It was determined that the concentration should increase from around 10 mg/j to 10 mg/j (see Figure 7 fcl). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling pond was measured using a treated water turbidity meter, and the raw water from the first stage had not yet been discharged as treated water between 1:00 and 3:00, so the plot is twice in the period from 3 o'clock to 4 o'clock, corresponding to the first stage, and twice in the period from 3 o'clock to 4 o'clock, corresponding to the first stage, and at 4 o'clock, corresponding to the beginning of the second stage.
It increased monotonically from 2 to 3 degrees during the period from 5:00 to 5:00 (see Figure 7 (dl)).

In the third stage 1 (that is, the period from 5 o'clock to 13 o'clock), the temperature of the raw water measured by the raw water thermometer and given to the setting device was 15 °C (see Figure 7 (a)). Due to the effects of the second stage, as described below, the turbidity of the treated water continued to increase from 3 degrees to nearly 5 degrees from 5 o'clock to 7 o'clock, and from nearly 5 degrees to 1.5 degrees from 7 o'clock to 1 p.m. The target value of the flowing current output from the setting device and given to the comparator circuit was set to -2 based on the empirical rule at 5 o'clock, and was maintained until 6 o'clock, and then again at 6 o'clock based on the empirical rule. Based on this, the value was set to -1, which was then maintained until 11 o'clock, and at 11 o'clock, it was again set to -2 based on the empirical rule, and which was maintained until 13:00 (see Figure 7 (bl)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
lomg/j to 15mg/ between 5:00 and 6:00.
15 mg/j between 6:00 and 7:00.
It was decided that the dose would increase from 22.5mg/i to 22.5mg/i and maintain it until 11:00, decrease from 22.5B/j to 20mg/i at 11:00, and then maintain it until 1:00pm (District 7 fc)? (see). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the coagulant was injected in the rapid stirring pond was rapidly stirred and then fed to the Enen stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

As measured by a treated water turbidity meter, the concentration of the treated water discharged from the settling basin increased from 3 to 5 degrees during the period from 5 o'clock to 8 o'clock, which corresponds to the middle to late stage of the second stage. It decreased again to nearly 4 degrees, and from 4 degrees to 1.5 degrees during the period from 8:00 to 13:00, which corresponds to the early to middle stage of the third stage.
(Fig. 7fd] Sanoka).

In the fourth stage (i.e. the period from 13:00 to 17:00), the temperature of the raw water measured by the raw water thermometer and fed to the setting device gradually increased from 15°C to 25°C (Figure 7(a)! However, due to the late stage 3 or early stage 4, the concentration of the treated water was maintained at less than 2 degrees as described below, so the target flow current output from the setting device and given to the comparison circuit was The value was maintained at -2 based on experience point 1] during the period from 13:00 to 16:00, was reduced to -35 based on the empirical rule at 16:00, and was maintained until 17:00 (Figure 7 (b) reference).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
Maintained at 20B/R during the period from 13:00 to 14:00,
20mg/j to 225 between 14:00 and 16:00
It was determined that the concentration would monotonically increase to 20 mg/j at 16:00, and then rapidly decrease to 20 mg/j and be maintained until 17:00 (see FIG. 7, ICL). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling basin was measured using a treated water turbidity meter, and it was found that the period from 13:00 to 16:00, which corresponds to the latter half of the third stage, and the period from 16:00, which corresponds to the early stage of the fourth stage, During the period from 17:00 to 17:00, the temperature remained below 2 degrees with almost no change (see Figure 7(d)).

In the fifth stage (that is, the period from 17:00 to 24:00), the temperature of the raw water measured by the raw water thermometer and given to the setting device is 25°C (see Figure 7(a) 1),
Because the turbidity of the treated water was maintained at less than 2 degrees due to the influence of the stage, the target value of the flowing current output from the setting device and given to the comparison circuit was set to -3 based on the empirical rule at 17:00. It was maintained until 24:00 (see Figure 7(b)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
It decreased from 20 mg/j to 17.5 mg/j at 17:00 and was maintained until after 19:00, and 17.5 mg after 19:00.
/j to 15mg/j and maintained until 24 hours (see Figure 7(c)). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

As measured by a treated water turbidity meter, the turbidity of the treated water discharged from the sedimentation pond decreased from less than 2 degrees to less than 1 degree during the period from 17:00 to 19:00, which corresponds to the middle to late stage of stage 4. It gradually decreases and gradually increases from less than 1 degree to 2 degrees in the period from 19:00 to 22:00, which corresponds to the late stage 4 to early stage 5, and increases to 22 degrees, which corresponds to the middle of stage 5.
It was maintained at 2 degrees in the period from
Figure (dl!sho).

j2 and L r of Example 2 As is clear from the above, in Example 2, the target value of the flowing current difference and the measured value of the flowing current difference are used instead of the target value of the flowing current and the measured value of the flowing current of Comparative Example 2. (1) Compared to Comparative Example 2, it is possible to eliminate fluctuations in the flowing current due to the raw water properties, and (ii) Compared to Comparative Example 2, it is possible to better follow fluctuations in the temperature of the raw water. (Compared to Comparative Example 2, there was no apparent excess or deficiency in the amount of coagulant injected, and as a result, fluctuations in the turbidity of the treated water could be reliably suppressed compared to Comparative Example 2.)

With reference to FIGS. 8 to 11 (al to (e)), the third embodiment of the flocculant injection control method according to the present invention will be described. The structure and operation of the coagulation and sedimentation processing apparatus will be explained in detail while explaining the coagulation and sedimentation processing apparatus that is being implemented.

As is clear from a comparison between FIG. 1 and FIG. 8, the third embodiment has a raw water thermometer 18 added to the first embodiment to measure the pH of the raw water, the temperature of the raw water, and the difference in flowing current. This embodiment has substantially the same structure and operation as the first embodiment, except that the amount of coagulant to be injected is determined from the measured value of .

That is, in the third embodiment, the raw water pH measured by the raw water PU meter 17 and the raw water temperature measured by the raw water thermometer 18 function as indicators equivalent to the raw water pn in the first embodiment. [See Figure 9 [a] to (cl) and Section 10 (a) to (c)).

Therefore, in order to simplify the explanation, we will explain the first
The same reference numerals as in the first embodiment are given to the same members as those included in the first embodiment, and detailed explanation thereof will be omitted.

In order to further deepen the understanding of the third embodiment of the flocculant injection control method according to the present invention, with reference to FIGS. 8 to 11 (a) to (e). will be explained in detail by citing specific numerical values.

Here, dam storage water is used as raw water, and a first coagulation and sedimentation treatment apparatus in which injection control of a coagulant is executed by a coagulant injection control method according to the present invention, and a coagulant injection control method disclosed as a prior art The coagulant was supplied to a second coagulation and sedimentation processing device in which injection control of the coagulant was executed.

1st. The second coagulation and sedimentation treatment equipment is equipped with a rapid stirring tank, a slow stirring tank, and a settling tank, all of which have the same structure, and the residence times of the rapid stirring tank, slow stirring tank, and settling tank are 3 minutes and 27 minutes, respectively. minutes and 2 hours and 30 minutes, the raw water (i.e. suspension water) throughput was set at 100 m2 and polyaluminum chloride (so-called 'PAC') was used as the flocculant.

The pH of raw water decreased to 7.5 over time after the start of operation.
and 6.5 as shown in FIG. 11(a). In addition, the temperature of raw water changed between 25°C and 15°C as shown in Figure 11 (a) as time passed from the start of operation.By the way, the turbidity of raw water was approximately 20°C. The turbidity of the treated water was set at 2 degrees.

In the first stage (that is, the period from 0:00 to 1:00), the raw water pH measured by the raw water pH meter and given to the setting device is
H is 75 (Figure 11 (a+? light)), and the temperature of the raw water measured by the raw water thermometer and given to the setting device is 2.
Since the temperature was 5°C (see Figure 11 tb+), the pH of the raw water (here 7.5) and the temperature of the raw water (
Here, the set value of the flowing current difference selected according to the temperature (25° C.) was outputted as the target value of the flowing current difference and given to the comparison circuit. Therefore, the target value of the flowing current difference is -1,9
(See Figure 11 fc)).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison result was that the target value of the flowing current difference was maintained at O because the target value was constant.

In the control device, since the comparison result was maintained at O, the flocculant injection amount was maintained at 8 mg/j and was given to the flocculant injection device as a flocculant injection control signal (Fig. 11 f).
See d)) @Incidentally, 8 mg/j was determined by a separately performed jar test.

In the flocculant injection device, flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, slowly agitated oil spill water was allowed to settle and remove aggregates. However, since the residence time in the settling tank was 2 hours and 30 minutes, the raw water given to the rapid stirring tank at the start of operation had not yet been discharged from the settling tank as treated water. Therefore, the measurement results of the treated water turbidity meter are not plotted (Fig. 11 te+1
1).

In the second stage (i.e. the period from 1 o'clock to 5 o'clock), the raw water p measured by the raw water pH meter and given to the setting device is
As H gradually decreases from 7.5 to 6.5, Figure 11 (al
The temperature of the raw water supplied to the setting device as measured by the raw water thermometer gradually decreased from 25°C to 15°C (see Figure 11(b)), so the pH of the raw water was adjusted in the setting device. The set value of the flowing current difference selected according to the temperature of the raw water was outputted as a target value of the flowing current difference and given to the comparison circuit. Therefore, the target value of the flowing current difference monotonically decreased from -1,9 to nearly -4 (11th
Figure (see cl).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison results showed that the target value of the flowing current difference gradually increased as the pH of the raw water and the temperature of the raw water decreased.

In the control device, as the comparative results gradually increased, the amount of coagulant injection increased from 8 mg to 7 g during the period from 1 o'clock to 5 o'clock.
The amount was gradually increased to 5 mg/j and given to the flocculant injection device as a flocculant injection control signal (see FIG. 11(d)).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling basin was measured with a treated water turbidity meter, and it was 2 degrees during the period from 3:00 to 4:00, which corresponds to the first stage, which corresponds to the early stage of the second stage. During the period from 4 o'clock to 5 o'clock, the temperature increased from 2 degrees to nearly 3 degrees, and then decreased to 2 degrees again (see Figure 11(e)).

In the third stage (i.e. the period from 5:00 to 13:00),
The pH of the raw water measured by the raw water pH meter and given to the setting device is 65 (see Figure 11 (al)), and the temperature of the raw water measured by the raw water thermometer and given to the setting device is 1.
5°C (see Figure 11 (bl)), the setting value of the flowing current difference selected in the setting device according to the raw water pH and raw water temperature is output as the target value of the flowing current difference and sent to the comparison circuit. Therefore, the target value of the flowing current difference was maintained at -4 (see Fig. 11 (cl)).
.

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison result was that the target value of the flowing current difference was kept constant, so it was maintained at 0.

In the control device, since the comparison result was maintained at 0, the flocculant injection amount was maintained at 15 mg/j and was given to the flocculant injection device as a flocculant injection control signal (see Figure 11 (dl)). ).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

As measured by a treated water turbidity meter, the turbidity of the treated water discharged from the sedimentation pond ranged from nearly 2 degrees to 1.5 degrees during the period from 5 o'clock to 8 o'clock, which corresponds to the middle to late stage of the second stage. After decreasing to about 1.5 degrees, it increased from about 1.5 degrees to about 2.5 degrees, and was maintained at about 2 degrees during the period from 8:00 to 13:00, which corresponds to the early to middle stage of the 3rd stage (11th Figure (e
) reference).

In the fourth stage (that is, the period from 13:00 to 17:00), the raw water pH measured by the raw water pH meter and given to the setting device gradually increases from 6.5 to 7.5 (see Figure 11).
a)), and the temperature of the raw water measured by the raw water thermometer and given to the setting device gradually increased from 15°C to 25°C (see Figure 11(b) I), so the temperature of the raw water p The set value of the flowing current difference selected according to the temperature of the raw water and the temperature of the raw water was outputted as a target value of the flowing current difference and given to the comparison circuit.

Therefore, the target value of the flowing current difference gradually increased from -4 to -1,9 during the period from 13:00 to 17:00 (first
(See Figure 1(c)).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison results showed that the target value of the flowing current difference gradually decreased as the pH of the raw water increased and the temperature of the raw water increased.

In the control device, since the comparison results gradually decreased, the injection amount of coagulant was increased to 15 mg/j during the period from 13:00 to 17:00.
It was gradually decreased from
reference).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling pond was measured using a treated water turbidity meter, and it was found to be 31'Qll! 1 corresponding to the latter half of
It was maintained at 2 degrees during the period from 3:00 to 16:00, increased from 2 degrees to nearly 2.5 degrees during the period from 16:00 to 17:00, which corresponds to the beginning of the fourth stage, and then decreased to 2 degrees. (
Figure 1I (el a).

In the fifth stage (i.e., the period from 17:00 to 24:00), the raw water pH measured by the raw water pH meter and given to the setting device is 75 (see Figure 11 (a)), and the raw water pH measured by the raw water thermometer is 75. Since the temperature of the raw water given to the setting device was 25°C (see Figure 11 tb+), the setting value of the flowing current difference selected in the setting device according to the pH of the raw water and the temperature of the raw water was the same as that of the flowing current difference. It was output as a target value and given to the comparison circuit. Therefore, the target value of the flowing current difference was maintained at -1.9 (Fig. 11 fc)
reference).

In the comparison circuit, the measured value of the flowing current difference obtained by the calculation device from the raw water flowing current and the aggregated flowing current measured by the flowing ammeter is compared with the target value of the flowing current difference given from the setting device, The comparison results were provided to the controller. The comparison result was that the target value of the flowing current difference was maintained at O because the target value was constant.

In the control device, since the comparison result was maintained at O, the flocculant injection amount was maintained at 8 mg/j and was given to the flocculant injection device as a flocculant injection control signal (Figure 11 (
d)).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the sedimentation basin was measured using a treated water turbidity meter, and the turbidity of the treated water was approximately 2 degrees and 2.5 degrees during the period from 17:00 to 20:00, which corresponds to the middle to late stage of the 4th stage. 20, which corresponds to the early to middle stages of stage 5.
The temperature was maintained at approximately 2 degrees Celsius between 24:00 and 24:00.
Figure 11 (see el).

In the first stage of comparison (that is, from 0:00 to 1:00), the raw water p measured by the raw water pH meter and given to the setting device is
H is 7.5 (see Figure 11 (a)), and the temperature of the raw water measured by the raw water thermometer and given to the setting device is 2.
5°C (see Figure 11 (bl)), and the time elapsed from the start of operation was less than the residence time (i.e., 3 hours) in the rapid stirring tank, slow stirring tank, and sedimentation tank, and the turbidity of the treated water was still low as described below. Since it was not measured, the target value of the flowing current output from the setting device and given to the comparison circuit was maintained at -3 based on empirical rules (Figure 11 (c)
reference).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
It was decided to maintain the concentration at 8 mg/j (Figure 11(d)
)reference). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

Incidentally, 8 mg/j was determined by a jar test performed separately.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond according to the flocculant injection control signal.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, slowly agitated oil spill water was allowed to settle and remove aggregates. However, since the residence time in the settling tank was 2 hours and 30 minutes, the raw water given to the rapid stirring tank at the start of operation had not yet been discharged from the settling tank as treated water. Therefore, the measurement results of the treated water turbidity meter were not plotted and were not used to determine the target value of the flowing current (see Figure 11).
(see el).

In the second stage (i.e. the period from 1 o'clock to 5 o'clock), the raw water p measured by the raw water pH meter and given to the setting device is
As H gradually decreases from 7.5 to 6.5, Figure 11 (al
), and the temperature of the raw water measured by the raw water thermometer and given to the setting device gradually decreased from 25°C to 15°C (see Figure 11 (bl)), so the temperature of the raw water measured by the raw water thermometer and given to the setting device gradually decreased from 25°C to 15°C (see Figure 11 (bl)). The target value for the flowing current is that the elapsed time from the start of operation is less than the residence time (i.e. 3 hours) in the rapid stirring tank, slow stirring tank, and sedimentation tank, and the turbidity of the treated water has not yet been measured as described below. During the period from 1 o'clock to 3 o'clock, the turbidity of the treated water was maintained at -3 as in the first stage based on empirical rules, and the turbidity of the treated water increased to 2 as described below.
Based on the empirical rule, it was maintained at -3 even during the period from 3 o'clock to 4 o'clock when the turbidity was high, and it was maintained at -2 based on the empirical rule at 4 o'clock when the turbidity of the treated water started to increase, corresponding to the beginning of the second stage. 5 after being
(See Figure 11(c)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
8 mg/j to 4 mg during the period from 1 o'clock to after 4 o'clock
It was determined to decrease monotonically from 4 mg/l to 7.5 mg in the period from 4:00 to 5:00 (see Figure 11fd)). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling pond was measured using a treated water turbidity meter, and the raw water from the first stage had not yet been discharged as treated water between 1:00 and 3:00, so the plot is twice in the period from 3 o'clock to 4 o'clock, corresponding to the first stage, and twice in the period from 3 o'clock to 4 o'clock, corresponding to the first stage, and at 4 o'clock, corresponding to the beginning of the second stage.
The temperature increased monotonically from 2 degrees to 4.5 degrees during the period from 5:00 to 5:00 (see Fig. 11(e)).

In the third stage (i.e. the period from 5:00 to 13:00),
The pH of the raw water measured by the raw water pH meter and given to the setting device was 6.5 (see Figure 11 (a)), and the temperature of the raw water measured by the raw water concentration meter and given to the setting device was 15°C. However, due to the influence of the second stage, the turbidity of the treated water continued to increase from 4.5 degrees to nearly 9 degrees during the period from 5 o'clock to 7 o'clock. Since the current value continued to decrease from nearly 9 degrees to less than 1.5 degrees during the period from 5:00 to 13:00, the target value of the flowing current output from the setting device and given to the comparator circuit was -1 based on the empirical rule at 5:00. After that, it was maintained until 6 o'clock, and at 6 o'clock it was again set to O based on the empirical rule, and it was maintained until 7 o'clock, and at 7 o'clock it was again set to 0.5 based on the empirical rule, and it was maintained until 12 o'clock, and 12 o'clock.
At that time, it was again set to 0 based on empirical rules and was maintained until 13:00 (see Figure 11 fc)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
7.5 mg/j to 10r between 5:00 and 6:00
ag/j and 10m between 6:00 and 7:00.
g/j to 15 mg/j and increased from 15 mg/j to 18 mg/j between 7:00 and 8:00 to 1
It was maintained until 2 o'clock, and after 12 o'clock it increased from 18 mg/j to 15
It was decided to decrease the concentration to mg/ε and maintain it until 13:00 (see FIG. 11(d)). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the sedimentation basin was measured with a treated water turbidity meter, and the turbidity ranged from 4.5 degrees to nearly 9 degrees during the period from 5 o'clock to 8 o'clock, which corresponds to the middle to late stage of the second stage. After that, the temperature decreased again to nearly 6 degrees, and then monotonically decreased from 6 degrees to nearly 1.5 degrees during the period from 8:00 to 10:30, which corresponds to the early to middle stage of the third stage. 15 in the period from 10:30 to 13:00, which corresponds to the middle period.
The angle was maintained close to 5 degrees (see FIG. 11(e)).

In the fourth stage (that is, the period from 13:00 to 17:00), the raw water pH measured by the raw water pH meter and given to the setting device gradually increases from 6.5 to 7.5.
al), and the temperature of the raw water measured by the raw water thermometer and given to the setting device gradually increased from 15°C to 25°C (see Figure 11(b)), but from the latter half of the third stage to the fourth stage. Due to the influence of the initial stage (as described later) (the turbidity of the treated water was maintained below 2 degrees, the target value of the flowing current output from the setting device and given to the comparison circuit was is maintained at O based on the rule of thumb during the period, and 1
After being set to -1 at 6 o'clock based on the empirical rule, it was maintained until 17 o'clock (see Fig. 11(c)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
g/j 15 times during the period from 13:00 to after 15:30
The concentration increased monotonically from 15:30 to 17:00, and then increased to nearly 40mg/l (from 30:30 to 3:30 p.m.).
mg/l (see FIG. 11 1c)). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

The turbidity of the treated water discharged from the settling basin was measured using a treated water turbidity meter, and it was found that the period from 13:00 to 16:00, which corresponds to the latter half of the third stage, and the period from 16:00, which corresponds to the early stage of the fourth stage, During the period from 17:00 to 17:00, the temperature remained below 2 degrees, with almost no change (see Fig. 11 (el)).

In the fifth stage (that is, the period from 17:00 to 24:00), the raw water pH measured by the raw water pH meter and given to the setting device is 7.5 (see Figure 11 (a)), and the raw water pH measured by the raw water thermometer is 7.5. The temperature of the raw water measured and given to the setting device was 25°C (see Figure 11 (bl)), and as will be explained later due to the influence of the fourth stage (the turbidity of the treated water was maintained below 2°C, The target value of the flowing current output from the setting device and given to the comparator circuit is set to -2 based on the empirical rule at 17:00 and is maintained until 19:00, and at 19:00 it is set to -3 again based on the empirical rule and set at 24:00. It was maintained until (Fig. 11 (
Ol e light).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the target value of the flowing current given from the setting device, and the comparison result was given to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
2 from nearly 30mg/j during the period from 17:00 to 18:00.
It was decided that the concentration would rapidly decrease to nearly 0 mg/j and be maintained until 19:00, and then rapidly decrease from close to 1 mg/j to 8 mg/l and be maintained until 24:00 at 19:00 (Fig. 11, 1cl). ).The flocculant injection amount was given to the flocculant injection device as a flocculant injection control signal.

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to a flocculant injection control signal given from the control device.

The raw water into which the flocculant was injected in the rapid stirring pond was rapidly stirred and then fed to the slow stirring pond as rapidly stirred oil spill water.

In the slow stirring pond, the rapidly stirred oil spill water was slowly stirred and then fed to the settling pond as slowly stirred oil spill water.

In the settling basin, the slowly stirred oil spill water was allowed to stand to settle and remove aggregates, and then was discharged as treated water.

As measured by a treated water turbidity meter, the turbidity of the treated water discharged from the sedimentation pond ranged from 1 degree to 0.5 degree during the period from 17:00 to 18:30, which corresponds to the middle to late stage of the 4th stage. It gradually decreases to nearly 0.5 degrees, and gradually increases from nearly 0.5 degrees to 2 degrees during the period from 18:30 to 22:00, which corresponds to the late stage 4 or early stage 5. It was maintained at 2 degrees during the period from 22:00 to 24:00, which corresponds to the middle period (see Fig. 11 (el)).

Comparison of Example 13 and Comparative Example 3 As is clear from the above, in Example 3, instead of the target value of flowing current and the measured value of flowing current of Comparative Example 3, the target value of flowing current difference and the measurement of flowing current difference were used. Since this value is adopted, it is possible to eliminate fluctuations in the flowing current due to the raw water properties compared to il Comparative Example 3, and to reduce the raw water pH compared to fil Comparative Example 3.
It is possible to suitably follow fluctuations in the temperature of raw water and (
Compared to III Comparative Example 3, there was no apparent excess or deficiency in the amount of coagulant injected, and as a result, fluctuations in the turbidity of the treated water could be reliably suppressed (compared to IV Comparative Example 3).

(3) Effects of the Invention As is clear from the above, the first flocculant injection control method according to the present invention coagulates suspended water from raw water, removes precipitates, and discharges the raw water as treated water. When injecting the coagulant, the amount of coagulant to be injected is controlled according to the properties of the raw water.
As clearly stated as a means of solving
It has the effect of being able to determine the amount of flocculant to be injected in immediate response to changes in the hydrogen ion concentration index of the raw water, and has the effect of suppressing fluctuations in the turbidity of the treated water. This has the effect of reducing the amount of injection.

The second flocculant injection control method according to the present invention is characterized in that when a flocculant is injected into raw water in order to flocculate suspended water from raw water, remove precipitates, and discharge it as treated water, the flocculant is injected into the raw water according to the properties of the raw water. In particular, as specified as the second solution in the middle section of [Means for solving problems], the first to seventh steps listed in items (a) to (g) are controlled. (iv) It has the effect of being able to determine the injection amount of flocculant in immediate response to changes in the raw water temperature, and as well as the above-mentioned first flocculant injection control method, (ii) and (iii) It has the effect of

The third flocculant injection control method according to the present invention is characterized in that when a flocculant is injected into raw water in order to flocculate suspended solids from raw water, remove precipitates, and discharge as treated water, the flocculant is flocculated according to the properties of the raw water. The injection amount of the agent is controlled, and in particular, as specified as the third solution in the latter part of [Means for solving the problem], the first to eighth steps listed in items (a) to (h) are (v) It has the effect of being able to determine the amount of coagulant to be injected in response to changes in the hydrogen ion concentration index of raw water and changes in raw water temperature. Compared to the second flocculant injection control method, this method preferably has the effects (ii) and (iii) above.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing a coagulation-sedimentation processing apparatus in which flocculant injection control is executed according to the first embodiment of the flocculant injection control method according to the present invention, and FIG. 2 is similar to FIG. An enlarged cross-sectional view for showing a part of the illustrated coagulation and sedimentation processing apparatus in an enlarged manner, FIGS. 3(a) to fcl are operation explanatory diagrams for explaining the embodiment in FIG. 1, and FIGS. (d) is the first
FIG. 5 is an operation explanatory diagram for explaining a specific example of the embodiment. FIG. 6(a) to (c) are operational explanatory diagrams for explaining the embodiment in FIG. 5, and FIG. 7(a)
) to (d) are operation explanatory diagrams for explaining a specific example of the embodiment shown in FIG. 5, and FIG. A conceptual diagram showing the coagulation sedimentation processing apparatus being executed, FIG. 9 (al to fc) is an operation explanatory diagram to explain the embodiment in FIG. 8, and FIG. 10 (a) to fcl are FIG. 8. Other operation explanatory diagrams for explaining the embodiment, FIGS. 11(a) to (e) are operation explanatory diagrams for explaining a specific example of the embodiment of FIG. 0 11A IIB 1C 2 13... 3A 13B... 4 4A 14B... 5 6A 6B Coagulation and precipitation treatment equipment Raw water supply pipe Treated water discharge pipe Water landing well Rapid stirring pond Drive source Stirring member Slow stirring pond/drive source Stirring Parts: Sedimentation tank, coagulant injection device, coagulant storage tank, measuring bomb 17, raw water pH meter, 18, etc. ......Raw water thermometer 19......Flowing ammeter 19a, 19a", 19a"---Water sampling vibrator 19a
4...Water sampling pump 19b...
...... Drain pipes 19c, 19d...
・・・・・・・・・Connection line 19A・・・・・・・・・・・・
...Cylindrical containers 19B, 19C...
Electrode 19D...... Power source 19E...
・・・・・・・・・・・・Piston 19F・・・・・・
・・・・・・Ammeter 20・・・・・・・・・・・・・・・
・・・・Treatment water turbidity meter 21・・・・・・・・・・・・・
・・・・Setting device 22・・・・・・・・・・・・・・・
...Arithmetic unit 23......
・Comparison circuit 24・・・・・・・・・・・・・・・・・・
Control device Raw water pH 6 0 Temperature of raw water Figure 7 Raw water pH Raw water pH Raw water p) -1 0 Temperature of raw water Okimoto's temperature Temperature of * Temperature 0 Figure

Claims (3)

[Claims] (1) A flocculant made by controlling the amount of flocculant injected into raw water according to the properties of the raw water when injecting the flocculant into raw water to flocculate suspended solids, remove precipitates, and discharge as treated water. In the injection control method, (a) a first step of measuring the hydrogen ion concentration index of the raw water, (b) a second step of measuring the flowing current of the raw water, and (c) a step of measuring the raw water into which the flocculant has been injected. a third step of measuring the flowing current; (d) a measured value of the flowing current difference by subtracting the measured value of the flowing current measured in the third step from the measured value of the flowing current measured in the second step; (e) a fifth step of selecting a set value of the flowing current difference according to the hydrogen ion concentration index of the raw water measured in the first step and determining it as a target value of the flowing current difference; (f) a sixth step of comparing the target value of the flowing current difference determined in the fifth step and the measured value of the flowing current difference calculated in the fourth step; A flocculant injection control method comprising: a seventh step of determining the amount of flocculant to be injected according to the results compared in step 6. (2) A flocculant made by controlling the amount of flocculant injected into raw water according to the properties of the raw water when injecting the flocculant into raw water to flocculate suspended solids, remove precipitates, and discharge as treated water. In the injection control method, (a) a first step of measuring the temperature of the raw water, (b) a second step of measuring the flowing current of the raw water, and (c) a flowing current of the raw water into which the flocculant has been injected. (d) calculating the measured value of the flowing current difference by subtracting the measured value of the flowing current measured in the third step from the measured value of the flowing current measured in the second step; a fourth step; (e) a fifth step of selecting a set value for the flowing current difference according to the temperature of the raw water measured in the first step and determining it as a target value for the flowing current difference; ) a sixth step of comparing the target value of the flowing current difference determined in the fifth step and the measured value of the flowing current difference calculated in the fourth step; and a seventh step of determining the amount of coagulant to be injected according to the result. (3) A flocculant made by controlling the amount of flocculant injected according to the properties of the raw water when injecting the flocculant into the raw water in order to flocculate suspended matter from the raw water, remove precipitates, and discharge it as treated water. In the injection control method, (a) a first step of measuring the hydrogen ion concentration index of the raw water, (b) a second step of measuring the temperature of the raw water, and (c) a third step of measuring the flowing current of the raw water. (d) a fourth step of measuring the flowing current of the raw water into which the flocculant has been injected; and (e) measuring the flowing current measured in the fourth step from the measured value of the flowing current measured in the third step. a fifth step of calculating the measured value of the flowing current difference by subtracting the measured value of the flowing current; (f) the hydrogen ion concentration index of the raw water measured in the first step and the hydrogen ion concentration index of the raw water measured in the second step; (g) selecting a set value of the flowing current difference according to the temperature of the raw water and determining it as a target value of the flowing current difference; (h) a seventh step of comparing the measured value of the flowing current difference calculated in step 5; and (h) an eighth step of determining the amount of coagulant to be injected according to the results of the comparison in the seventh step. A flocculant injection control method comprising: