JPH03284303A - 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 a fluocculant to be injected by comparing the command for a streaming current determined in accordance with the measured hydrogen ion temp. index of raw water and the measured streaming current value to determine the amt. of the flocculant to be injected. CONSTITUTION:When the operation of a flocculating-setting device 10 is started, raw water is supplied to a rapidly agitated basin 13, the pH of raw water is measured by a raw water pH meter 18, the measured value is inputted to a setting device 21, the optimum streaming current is appropriately obtained in conformity with the measured value, and the current is outputted to a comparator 22 as the command for the streaming current. The difference between the command for the streaming current supplied from the setting device 21 and the measured streaming current value supplied from a streaming current meter 19 is obtained by the comparator 22, and the result is outputted to a controller 23. The amt. of flocculant to be injected is determined by the controller 23 in accordance with the compared result supplied from the comparator 22, and the amt. is outputted to a flocculant injector 16 as an injection control signal for the flocculant.

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 the flocculant injection control method of controlling the injection amount of flocculant according to the properties of raw water during injection, in particular, the set value of the flowing current is selected according to at least one of the hydrogen ion concentration index and the temperature of the raw water. This invention relates to a flocculant injection control method in which the injection amount of flocculant is determined so that the flowing current value approaches the target value of the flowing current obtained by the method.

[Prior Art] Conventionally, this type of flocculant injection control method involves injecting a flocculant (inorganic flocculant or organic flocculant) into raw water to achieve a desired flocculating state, and then controlling the flow current (゛R The "optimal flowing current" is measured in advance and stored in the setting device as the set value of the flowing current, and the set value of the flowing current (that is, the optimal flowing current) is selected according to the measurement result of the turbidity of the treated water. It has been proposed that a control device determines the amount of coagulant to be injected so that the measured value of the flowing current approaches the determined target value of the flowing current and the turbidity of the treated water is maintained at a desired level.

[Problem to be solved 1 However, in the conventional flocculant injection control method, the amount of flocculant to be injected was determined while determining the target value of the flowing current based on the measurement results of the turbidity of the treated water. 1) Even if the amount of flocculant injection is changed immediately when the turbidity of the treated water changes, there is a drawback that the flocculant injection control will be delayed by the residence time in the rapid stirring tank, slow stirring tank, and sedimentation tank. Furthermore, (11) there is a drawback that it is not possible to sufficiently suppress fluctuations in treated water turbidity due to fluctuations in raw water properties, and as a result (iii) it is difficult to maintain the treated water turbidity at a desired level regardless of fluctuations in raw water properties. There was a drawback that the injection amount of flocculant had to be set at a large value in order to maintain the same.

Therefore, in order to eliminate these drawbacks, the present invention sets the flowing current to the target value of the flowing current obtained by selecting the set value of the flowing current according to at least one of the hydrogen ion concentration index and the temperature of the raw water. It is an object of the present invention to provide a flocculant injection control method that determines the flocculant injection amount so that the measured values are close to each other.

(2) Composition of the invention In the flocculant injection control method, which comprises controlling the injection amount of flocculant according to the properties of the raw water when injecting the flocculant into the raw water, ) A second step of measuring the flowing current of the raw water into which the flocculant has been injected, and a set value of the flowing current is selected according to the hydrogen ion concentration index of the raw water measured in the first step. a third step of determining the target value; (dl) the target value of the flowing current determined in the third step;
A fourth step of comparing the measured value of the flowing current measured in the step of tel, and a fifth step of determining the amount of coagulant to be injected according to the results of the comparison in the fourth step. A flocculant injection control method characterized by the following.

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 the flocculant injection control method, which controls the injection amount of the flocculant accordingly, (a first step of measuring the temperature of the Al raw water).

(b) A second step of measuring the flowing current of the raw water into which the flocculant has been injected, and selecting a set value of the flowing current according to the temperature of the raw water measured in the first step to set a target flowing current. a third step of determining the target value of the flowing current determined in the third step and a second
A fourth step of comparing the measured value of the flowing current measured in the step of (el), and a fifth step of determining the amount of coagulant to be injected according to the results of the comparison in the fourth step. ``A coagulant injection control method'' characterized by:

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 A third step of measuring the flowing current of the raw water into which the flocculant has been injected; a fourth step of selecting a set value of the flowing current according to the target value of the flowing current and determining it as a target value of the flowing current; and (e) selecting a set value of the flowing current determined in the fourth step and a third
+f) a sixth step of determining the amount of coagulant to be injected according to the results of the comparison in the fifth step; A coagulant injection control method characterized by comprising:

[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. In particular, as specified as the first solution in the previous section of [Means for solving the problem], the injection amount of the flocculant is controlled by Since it is equipped with fi) the function of determining the amount of coagulant to be injected in immediate response to changes in the hydrogen ion concentration index of raw water, and (11) the function of suppressing fluctuations in the concentration of treated water, and (iii) It 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, the method specified in the middle section of [Problem Solver 8] as the second solution (, 1iv) It acts to determine the injection amount of flocculant in immediate response to changes in the raw water temperature, and as a result, it has the effect of fii) and fiii) above in the same way as the first flocculant injection control method described above. to do.

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 problem E", (Vj) 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 as a result, it is effective for the first and second flocculant injection control methods described above. In comparison, the effects of (ii) and (iii) above are achieved more favorably.

[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.

Figure 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. It is.

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. 2 and FIG. 1;

FIGS. 3(a) to 3(fc) are operation explanatory diagrams for explaining the embodiment shown in FIG. 1, in which the optimum flowing current, the optimum injection amount of flocculant, and the concentration of treated water are plotted against the pH of the raw water, respectively. ing.

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

FIG. 5 is a schematic 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 tel are operation explanatory diagrams for explaining the embodiment in FIG. 5, in which the optimum flow current, the optimum injection amount of flocculant, and the turbidity of treated water are plotted against the temperature of raw water, respectively. ing.

FIG. 7 (at to (d+) is an operation explanatory diagram for explaining a specific example of the embodiment in FIG. The injection volume and treated water turbidity 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.

FIGS. 9(a) to 9(c) are operation explanatory diagrams for explaining the embodiment in FIG. 8, in which the optimum flowing current, the optimum injection amount of flocculant, and the turbidity of the treated water are respectively determined for the pH of the raw water. is plotted.

Fig. 1O (al to fcl are other operation explanatory diagrams for explaining the Fig. 8 embodiment, in which the optimum flowing current, the optimum injection amount of flocculant, and the turbidity of the treated water are respectively determined for the temperature of raw water. is plotted.

FIG. 11 (al to (el) are operation explanatory diagrams for explaining the specific example of the embodiment in FIG. , the amount of coagulant injected, and the turbidity of the treated water are plotted, respectively.

First, with reference to FIG. 1, the configuration of a coagulation-sedimentation processing apparatus in which flocculant injection control is executed by the first embodiment of the flocculant injection control method according to the present invention will be explained. The configuration will be explained in detail.

1O is a coagulation sedimentation treatment device in which injection control of a coagulant is executed by the coagulant injection control method according to the present invention, and the raw water is suspended water (hereinafter "°" The case of clean water (for example, water supply) is supplied from a raw water supply source (not shown) through the raw water supply pipe 11A as shown by arrow A, and large foreign objects contained in the raw water (i.e., suspended water) are Raw water (that is, suspended water) is supplied from the receiving well 12 through a raw water supply pipe 11B, and the flocculant injected by rapid stirring is fed into the raw water (that is, suspended water). a rapid stirring pond 13 for coagulating suspended solids to form aggregates (i.e., flocs);
Raw water in which flocculant is injected and rapidly stirred to form aggregates (hereinafter referred to as ``rapidly agitated oil spill water'') is provided, and the rapidly agitated oil spill water is slowly agitated to enlarge the aggregates. a settling tank 15 for allowing the suspended water C (hereinafter referred to as "slowly agitated oil spill water") given from the slow stirring tank 14 to settle to settle the aggregates; The rapid stirring pond 13 is equipped with a flocculant injection device 16 for injecting a flocculant (inorganic flocculant or organic flocculant) into the rapid stirring pond 13 to form a A stirring member 13B is provided with a stirring member 13B that is driven to rotate rapidly (that is, driven to rotate at a relatively high speed) by a drive source 13A.
In other words, the stirring member 1 is rotated at a relatively low speed.
4B is installed. A discharge pipe (not shown) is provided at the bottom of the settling tank I5 for removing 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 and sedimentation treatment equipment is also equipped with a hydrogen ion concentration index meter (hereinafter referred to as °° 18, a flow current meter 19 for measuring the flow current of the raw water (i.e. suspended water) in which a flocculant has been injected, which is disposed with respect to the rapid stirring pond 13; A treatment pipe is provided for the treated water discharge pipe 11c for discharging treated water from the pond 15 as shown by arrow B, and is used to measure the turbidity of the treated water (hereinafter also referred to as "treated water turbidity"). It is equipped with a water turbidity meter 20.

Incidentally, the flowing current meter 19 temporarily holds raw water injected with a flocculant collected from the rapid stirring pond 13B via a water sampling vibrator 19a and a water sampling pump 19a'' as a sample, and provides it for measuring flowing current. Thereafter, a cylindrical container 19A that discharges the sample (that is, raw water into which a flocculant has been injected) toward the rapid stirring pond 13B via a drainage vibrator 19b, and a cylindrical container 19A that is spaced apart from each other on the inner peripheral surface of the cylindrical container 19A are arranged. The two electrodes 19B and 19 are arranged inside the cylindrical container 19A and are caused to reciprocate by a power source 19D located outside the cylindrical container 19A, and the sample (that is, the raw water into which the flocculant has been injected) is transferred. The electrode 19B is connected to the moving piston 19E and the electrodes 19B and 19c via connecting wires 19c and 19d, and the sample (that is, the raw water injected with the flocculant) is moved as the piston 19E reciprocates.

It includes an ammeter 19F that measures the current generated between 190 and amplifies it appropriately and outputs it to the comparator circuit 22 as a current N current. The measured value of the flowing current by the flowing current meter 19 will decrease if the amount of coagulant injection 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 value of the flowing current will decrease if the flocculant injection amount is not increased. If the amount is not decreased, it will increase, so in the present invention, the amount of coagulant injected is controlled so that it matches the set value of the flowing current outputted by the setting device 21, thereby controlling the raw water flow rate and raw water turbidity. It eliminates the need for attention. Treated water turbidity meter 20
is provided only for evaluating the flocculant injection control method according to the present invention, and may be removed if desired.

The pressure of the coagulation and sedimentation treatment equipment is further determined by setting the raw water p) measured in advance in an appropriate manner and the optimum flowing current, maintaining a correlation therebetween, and giving the pressure from the raw water pH meter 18 based on the correlation. a setting device 21 for appropriately selecting an optimal flowing current (i.e., a set value of flowing current) according to the measured value of raw water pH and outputting it as a target value of flowing current; The measurement value of the flowing current given from the flowing ammeter 19 and the flowing current target given from the setting device 21 ([!! (
Comparison circuit 2 for comparing the optimum flowing current
2 and is connected to the comparison circuit 22 and the comparison circuit 2
A control device for determining the amount of coagulant to be injected according to the comparison result of No. 2 (i.e., the difference between the target value and the measured value of the flowing current) and giving it to the coagulant injection device 16 as a coagulant injection control signal. It is equipped with 23.

Furthermore, with reference to FIGS. 1 to 3 ia) to fc), the first embodiment of the flocculant injection control method according to the present invention will be described in which 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 IC, and is supplied to a subsequent treatment device (not shown).

Go! Prior to the start of operation of the ``Setting Operation Coagulation and Sedimentation Treatment Equipment'', the relationship between the raw water pH and the optimum flowing current (i.e., ``the corresponding flowing current when the desired flocculation state is achieved'') is determined in an appropriate manner. The relationship between the pH of the raw water and the optimum flowing current may be achieved by preliminary operation of the coagulation and sedimentation treatment equipment, or by creating a scaled-down model of the coagulation and sedimentation treatment equipment. However, here, explanation will be given assuming 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 is measured by repeating the jar test with a jar test device while measuring the flowing current with a flowing ammeter. That is, the flowing current corresponding to the optimum injection amount of the flocculant determined by the jar test (i.e., the injection amount of the flocculant that can achieve the desired flocculation state: Fig. 3 (see bHcl)) is defined as the optimum flowing current ( Figure 3 (see al).

The measurement of raw water pH and optimal flowing current is repeated, and the optimal flowing current corresponding to various raw water pHs is measured (Figure 3 (a)
reference).

After that, the raw water pH and the corresponding optimal flowing current are set as one set in sequence in the setting device 21, and the correlation between the raw water pH and the optimal flowing current (see Fig. 3 (al)) is set.
is held in the setting device 21. The optimum flowing current set in the setting device 21 is also referred to as the setting value of the flowing current.

■Injection control operation When the operation of the coagulation and sedimentation treatment equipment starts, the water landing well 12
The raw water pH meter 18 begins to measure the raw water [)H of the suspended water supplied to the rapid stirring pond 13 as raw water. The measured value of the raw water pH 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 pi meter 18, the optimum flowing current (i.e., flowing current ) is determined as appropriate and output to the comparator circuit 22 as the target value of the flowing current.

The comparison circuit 22 compares the target value of the flowing current (that is, the optimum flowing current) given from the setting device 21 with the flowing current meter 19.
The difference between the measured value of the flowing current given from and the measured value of the flowing current is determined and outputted to the control device 23 as a comparison result.

In the control device 23, the injection amount of the flocculant is determined according to the comparison result given from the comparison circuit 22 (i.e., the difference between the target value of the flowing current and its measured value), and is determined as the flocculant injection control signal. It is output toward the flocculant injection device 16.

Incidentally, the control circuit 23 determines the injection amount of the flocculant so that the comparison result given from the comparison circuit 22 is zero. 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 23, and the flocculant is injected from the flocculant storage tank 16A toward the rapid stirring pond 13.

As described above, according to the present invention, the raw water pn is
Since the amount of coagulant to be injected can be immediately changed in response to fluctuations in the amount of coagulant, it is possible to reliably suppress fluctuations in the turbidity of the treated water while avoiding unnecessary increases in the amount of coagulant to be injected.

In addition, with reference to FIG. 1 and FIGS. 4(a) to (di), in order to further deepen the understanding of the first embodiment of the flocculant injection control method according to the present invention, specific details will be explained. This will be explained in detail by giving 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 raw water pH changed between 75 and 6.5 as shown in FIG. 4(a) with the passage of time from the start of operation. Incidentally, the raw water turbidity and raw water temperature were approximately constant at 20°C and 25°C, respectively. Furthermore, the turbidity of the treated water was targeted at 2 degrees.

In the first stage (that is, from 0:00 to 1:00), the raw water pH measured by the raw water pH meter and given to the setting device is
Since H was constant at 7.5 (see Figure 4(a)),
The target value of the flowing current (optimal flowing current here) output from the setting device and given to the comparison circuit was -3 (
Figure 4(b)? (see).

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 (that is, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison result was that the target value of the flowing current was kept constant, so it was maintained at zero.

In the control device, since the comparison result was maintained at O, the flocculant injection amount was maintained at 10 mg/j and was given to the flocculant injection device as a flocculant injection control signal (Fig. 4 f).
c). Incidentally, 10 mg/A was determined by a jar test conducted 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 4(d) I).

In the second stage (i.e. the period from 1 o'clock to 5 o'clock),
The pH of the raw water measured by the raw water pH meter and given to the setting device gradually decreased from 7.5 to 65 (Figure 4 (a)
), the target value of the flowing current (optimal flowing current here) output from the setting device and given to the comparison circuit is 1
It gradually increased from -3 to -1 during the period from 4 o'clock to 4 o'clock, and was maintained at -1 during the period from 4 o'clock to 5 o'clock (see Fig. 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 (in this case, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison results showed that the target value of the flowing current gradually increased as the pH of the raw water decreased.

In the control device, as the comparison results gradually increased, the flocculant injection amount was gradually increased from 10 mg/j to 15 mg/j, and was given to the flocculant injection device as a flocculant injection control signal (4th (see figure fcl).

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 3 degrees, and then decreased to 2 degrees again (see Figure 4 Fdl).

In the third stage 1 (that is, the period from 5 o'clock to 13 o'clock), the raw water pH measured by the raw water pH meter and applied to the setting device was 65 (see Figure 4), so the setting The target value of the flowing current (in this case, the optimum flowing current) outputted from the device and given to the comparator circuit was maintained at -1 (see FIG. 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 (in this case, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison result was that the target value of the flowing current was kept constant, so it was maintained at zero.

In the control device, since the comparison result was maintained at 0, the flocculant injection amount was maintained at 15B/I and was given to the flocculant injection device as a flocculant injection control signal (Fig. 4 fc
(see l).

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 1.5 degrees to 3 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 increasing, the temperature decreased again to nearly 1.5 degrees, and was maintained at 2 degrees during the period from 8:00 to 13:00, which corresponds to the early to middle stage of the third stage (see Figure 4 (dl)).

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).
(see at), the target value of the flowing current (here, the optimum flowing current) output from the setting device and given to the comparison circuit gradually decreases from -1 to -3 during the period from 13:00 to 16:00. It was maintained at -3 during the period from 16:00 to 17:00 (see Figure 4 (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 (in this case, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison results showed that the target value of flowing current gradually decreased as the raw water pH increased.

In the control device, since the comparison result gradually decreased, the injection amount of flocculant was gradually decreased from 15 mg, # to 10 mg/j, and was given to the flocculant injection device as a flocculant injection control signal (No. 4 Figure (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.

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 was maintained at 2 degrees for both periods from 17:00 to 17:00.
(See 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)), so the pH of the raw water measured by the raw water pH meter and given to the setting device was 7.5. The target value of the flowing current outputted and given to the comparator circuit (in this case, the optimum flowing current) was maintained at -3 (see FIG. 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 (in this case, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison result was that the target value of the flowing current was kept constant, so it was maintained at zero.

In the control device, since the comparison result was maintained at O, the flocculant injection amount was maintained at 10 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 with rapid stirring in response to a flocculant injection control signal given from the control device.

The rapidly agitated raw water into which the flocculant was injected was rapidly agitated and then fed to the slow agitator pond as rapidly agitated oil spill water.

In the slow agitation basin, the rapidly agitated oil spill water was slowly agitated and then fed to the settling basin as slowly agitated oil flow pressure 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 it fluctuated around 2 degrees during the period from 17:00 to 20:00, which corresponds to the middle to late stage of the 4th stage. It was maintained at 2 degrees during the period from 20:00 to 24:00, which corresponds to the early to middle stage of stage 5 (see Figure 4 (d)).
.

In the first stage (i.e., 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 7.5 (see Figure 4 (a)), and the turbidity of the treated water decreases when the elapsed time from the start of operation is less than the residence time (i.e. 3 hours) in the rapid stirring acid, slow stirring tank and sedimentation tank. As will be described later, since no measurement had been made yet, the target value of the flowing current output from the setting device and given to the comparator circuit was maintained at -3 (see FIG. 4 Fbl).

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 provided 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 10 mg/j (Figure 4f).
c) Reference). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal. By the way, l
Omg/j was determined by a separately performed jar test.

(The flocculant injection device injected the flocculant with rapid stirring according to the flocculant injection control signal.

The rapidly agitated raw water into which the flocculant was injected was rapidly agitated and then fed to the slow agitator pond as rapidly agitated 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 to settle and remove aggregates. However, since the residence time in the sedimentation tank was 2 hours and 30 minutes, the raw water that was given rapid agitation at the start of operation had not yet been discharged from the sedimentation 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)).
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 75 to 6.5 (see Figure 4 ia)), but the target value of the flowing current output from the setting device and given to the comparator circuit was The turbidity of the treated water was maintained at −3 during the period from 1:00 to 3:00, as the turbidity of the treated water was not yet measured as described below at a residence time of less than 3 hours (i.e., 3 hours) in the stirred acid, slow stirring basin, and sedimentation basin. Since the turbidity of the treated water was constant during the period from 3 o'clock to 4 o'clock, which corresponds to the fiil first stage, -
3 and fiii) 4 corresponding to the beginning of the second stage.
At that time, the turbidity of the treated water began to increase, so it was set to -2 and maintained until 5 o'clock (see Figure 4, tb+).

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.

In the control device, the amount of coagulant to be injected is adjusted according to the comparison results.
10mg/l to 5mg/j between 1:00 and 4:00
It was determined to gradually decrease to 7.5 mg/j at 4 o'clock and maintain it until 5 o'clock (Fig. 4 (C1t)).
- 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 from 2 degrees to 4 degrees during the period from 10:00 to 05:00 (see Figure 4, 1dl).

In the third stage (i.e. the period from 5:00 to 13:00),
The raw water pH measured by the raw water pH meter and given to the setting device was 6.5 (see Figure 4 (al.)), but the
As the turbidity of the treated water was fluctuating as described below due to the influence of the stages, the target value of the flowing current output from the setting device and given to the comparison circuit was set to -1 at 5:00 and was maintained until 6:00. After being declared O at 6 o'clock, it was maintained until 11 o'clock, and 11 o'clock.
After being set to -1 at the time, it was maintained until 13:00 (Figure 4 (
(see 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.

In the Control I device, the injection amount of flocculant varies from 7.5 n+g/l to 1 in the period from 5 o'clock to 6 o'clock, depending on the comparison result.
10 mg/j between 6:00 and 7:00.
mg/l to 17.5 mg#, maintained until 11 o'clock, decreased to 15 mg/l at 11 o'clock, and then 13
It was decided to maintain the system until the end of 2008 (see Figure 4 (cl.)).

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 increased from 4 degrees to 9 degrees during the period from 5 o'clock to 8 o'clock, corresponding to the middle to late stage of the second stage, as measured by a treated water turbidity meter. Later, it decreased again to nearly 6 degrees, and gradually decreased from 4 degrees to less than 2 degrees during the period from 8:00 to 13:00, which corresponds to the early to middle stage of the third stage (see Figure 4, 1dl).

In the fourth stage (i.e. the period from 13:00 to 17:00), the raw water po measured by the raw water pH meter and given to the setting device gradually increased from 6.5 to 7.5 (Fig.
At), as explained later, the turbidity of the treated water was maintained at less than 2 degrees due to the influence of the late stage 3 or early stage 4, so the flow output from the setting device and given to the comparison circuit was The target value of the current was maintained at -1 during the period from 13:00 to 16:00, set to -2 at 16:00, and then maintained until 17:00 (see Fig. 4 (bl)).

In the comparison circuit, the measured value of the flowing current by the flowing current meter is compared with the target value of flowing current given from the setting device, and the comparison result is given to the control device. 1 in the period from 13:00 to 14:00 depending on the! ong/j, monotonically increasing from 15 mg/j to 25 mg/l during the period from 14:00 to 16:00, and rapidly increasing from 25 mg/j to 12.5 mg/j during the period from 16:00 to 17:00. The injection amount of flocculant determined to be decreased (see Figure 4fc) was given to the flocculant injection device as a signal on the flocculant injection side.

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

The raw water into which flocculant was injected into the rapid agitator was rapidly agitated and then fed to the slow agitator as rapidly agitated oil spill water.

In the case of slow agitation, 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 sedimentation basin was measured using a treated water turbidity meter, and it was found that the concentration of the treated water flowing out from the settling basin was measured from 13:00 to 16:00, which corresponds to the latter half of the third stage, and from 16:00, which corresponds to the early stage of the fourth stage. During the period up to 17:00, the temperature remained below 2 degrees, with almost no change (see 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 pFl meter and given to the setting device was 745 (see Figure 4 (a)), and due to the influence of the fourth stage. As described below, 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 set to -2.5 at 17:00 and maintained until 19:00. It was set to -3 at 19:00 and maintained until 24:00 (see Figure 4, tb+).

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.
12.5B/j to 10 during the period from 17:00 to 20:00
It was decided to gradually decrease to L mg/j and maintain L mg/l during the period from 20:00 to 24:00 (4th
(see figure fc)). 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 with rapid stirring in response to a flocculant injection control signal given from the control device.

The raw water into which flocculant was injected into the rapid agitator was rapidly agitated and then fed to the slow agitator as rapidly agitated oil spill water.

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

In the sedimentation basin, the slowly agitated foam effluent was allowed to stand still in order 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 settling pond gradually decreased from 2 degrees to 1 degree during the period from 17:00 to 19:00, which corresponds to the middle to late stage of the 4th stage. It gradually increases from 1 to 2 degrees during the period from 19:00 to 22:00, which corresponds to the late stage 4 or early stage 5, and from 22:00, which corresponds to the middle of stage 5. 24
It was maintained at 2 degrees during the period up to (see Figure 4(d)).

Shio 11 ri! As is clear from the above description, compared to Comparative Example 1, in Example 1, the target value of the flowing current given to the comparison circuit can better follow the fluctuations in the pH of the raw water, and as a result, the amount of coagulant injected is not excessive. There were not many shortages, and as a result, we were able to reliably suppress fluctuations in the turbidity of treated water.

(Second Example) Also, with reference to FIGS. 5 to 7(a) to (d), the second embodiment of the flocculant injection control method according to the present invention will be described. The configuration and operation of the coagulation-sedimentation processing apparatus in which injection control is performed 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 18A is provided in place of the raw water pH meter 18, and the aggregation is performed based on the raw water temperature and the measured value of the flowing current. This embodiment has substantially the same structure and operation as the first embodiment except for determining the injection amount of the agent.

That is, in the second embodiment, the temperature of the raw water measured by the raw water thermometer 18A is equal to the raw water p in the first embodiment.
It functions as an index equivalent to H (Figure 6(a)-(
cl).

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, with reference to FIGS. 5 to 7 (al to (d)), in order to further deepen the understanding of the second embodiment of the flocculant injection control method according to the present invention, specific details will be explained. This will be explained in detail by giving 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 sedimentation treatment device has a residence time of 3 minutes each in the rapid stirring pond, slow stirring pond, and settling pond.
27 minutes and 2 hours and 30 minutes, the suspension water throughput was 100 ms/h, and polyaluminum chloride (so-called "PAC") 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 pH 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 target value of the flowing current (here, the optimum flowing current) output from the setting device and given to the comparison circuit was -3 (7th
(see figure fbl I).

In the comparison circuit, the measured value of the flow II flow by the flow N current meter is compared with the target value of the flow current (that is, the optimum flow current) given by the setting device, and the comparison result is the control bag! given to. The comparison result was that the target value of the flowing current was kept constant, so it was maintained at zero.

In the control device, the comparison result was maintained at 0, so the injection amount of flocculant was 15 mg/j k: lI! held,
This signal was given to the flocculant injection device as a flocculant injection control signal (see FIG. 7fcl). Incidentally, 15 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 been discharged from the settling tank as treated water. Therefore, the measurement results of the treated water turbidity meter are not plotted (Fig. 7(d) e).

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 (in this case, the optimum flowing current) is output from the setting device and given to the comparison circuit.
gradually increased from -3 to -2 during the period from 1:00 to 4:00 and remained at -2 during the period from 4:00 to 5:00 (see Figure 7, 1b)).

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 (in this case, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison results showed that the target value of the flowing current gradually increased as the temperature of the raw water decreased.

In the control device, as the comparison results gradually increased, the flocculant injection amount was gradually increased from 15 mg/j to 20 mg/l and was given to the flocculant injection device as a flocculant injection control signal. (See Figure 7 fc)).

In the flocculant injection device, the flocculant was injected into the rapid stirring pond in response to the flocculant injection control signal given from the control 1 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. It increased from 2 degrees to 25 degrees during the period from 4 o'clock to 5 o'clock (7th
(See figure (d)).

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 Section 7 (a)), the target value of the flowing current output from the setting device and given to the comparison circuit (here In this case, the optimum flowing current) was maintained at -2 (see Fig. 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 (in this case, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison result was that the target value of the flowing current was kept constant, so it was maintained at zero.

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 (Fig. 7 t).
(see el).

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 the turbidity ranged from 2.5 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 almost 2 degrees, it increased again to almost 2 degrees, and 2 degrees in the period from 8:00 to 13:00, which corresponds to the early to middle stage of the third stage.
(Fig. 7 (d) Vertical light).

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 (Fig. 7 (a + If, ) Therefore, the target value of the flowing current (optimal flow amount FM in this case) output from the setting device and given to the comparison circuit is -2 to -3 during the period from 13:00 to 16:00.
It gradually decreased to -3 during the period from 16:00 to 17:00.
(see Figure 7 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 (in this case, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison results showed that the target value of flowing current gradually decreased as the raw water temperature increased.

In the control device, since the comparison result gradually decreased, the injection amount of the flocculant was gradually decreased from 2 [] mg/β to 15 mg/j, and the signal was given to the flocculant pouring device as a flocculant injection control signal. (See Figure 7 fcl).

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 IIl 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 was maintained at 2 degrees for both periods from 17:00 to 17:00.
Figure 7 (dl-t').

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 (at)), so
The target value of the flowing current (in this case, the optimum flowing current) outputted from the setting device and given to the comparison circuit was maintained at -3 (see Figure 7).

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 (in this case, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison result was that the target value of the flowing current was kept constant, so it was maintained at zero.

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 7 (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.

The turbidity of the treated water discharged from the sedimentation basin was measured with a treated water turbidity meter, and it fluctuated around 2 degrees during the period from 17:00 to 20:00, which corresponds to the middle to late stage of the 4th stage. It was maintained at 2 degrees during the period from 20:00 to 24:00, which corresponds to the early to middle stage of stage 5 (see Figure 7 + dl).
.

In the first stage (i.e., 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 is 25°C (Fig. 7(a)). ), 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 output from the setting device The target value of the flowing current given to the comparator circuit was maintained at -3 (see Figure 7).
.

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 provided 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 (
cl I'sho). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal. By the way, 1
5 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 7 (d).
)reference).

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 target value of the flowing current that is output from the setting device and given to the comparison circuit is that the elapsed time from the start of operation is the residence time in the rapid stirring tank, slow stirring tank, and settling tank (i.e. 3 Since the turbidity of the treated water had not yet been measured as described below, it was maintained at -3 during the period from 1:00 to 3:00, and from 3:00 to 4:00, which corresponds to the first stage (11) Since the turbidity of the treated water remained constant during the period, it was maintained at -3; It 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.
It was decided to gradually decrease from t5mg/j to 5B/j during the period from 1 o'clock to 4 o'clock, increase to 10 mg/j at 4 o'clock, and maintain it until 5 o'clock (see Figure 7, tc+?).
. The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal.

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, the slowly stirred oil spill water was allowed to stand to settle 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 3 degrees during the period from 5:00 to 5:00 (see Figure 7 [d]).

In the third stage (i.e. the period from 5:00 to 13:00),
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)), but the turbidity of the treated water fluctuated as described below due to the influence of the second stage. Therefore, the target value of the flowing current outputted from the setting device and given to the comparator circuit was set to -2 at 5 o'clock and maintained until 6 o'clock, and after set to -1 at 6 o'clock, it was maintained until 11 o'clock.
After being changed to -2 at 11 o'clock, it remained until 13 o'clock (7th
Figure (see 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.
Increased to 15 mg/j at 5 o'clock and maintained until 6 o'clock;
It was decided that the dose would be increased to 22.5 mg/j and maintained until 11 o'clock, decreased to 20 mg/j at 11 o'clock, and then maintained until 13 o'clock (see Fig. 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.

The turbidity of the treated water discharged from the settling pond 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, as measured by a treated water turbidity meter. Later, it decreased again to nearly 4 degrees, and gradually decreased from 4 degrees to less than 2 degrees during the period from 8:00 to 13:00, which corresponds to the early to middle stage of the third stage (see Figure 7 (dl)).

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 (see Figure 7 (at) However, due to the influence of the late stage 3 or early stage 4, the turbidity of the treated water was maintained at less than 2 degrees as described below, so the target value of the flowing current output from the setting device and given to the comparison circuit is maintained at -2 during the period from 13:00 to 16:00, set to -3,5 at 16:00, and then changed to 17:00.
(See Figure 7 fbl).

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 was maintained at 20 mg/l during the period from 13:00 to 14:00, and from 20 mg/l to 22 mg/l during the period from 14:00 to 16:00.
．． Monotonically increasing to 5 mg/j, then 20 mg/j at 16:00
It was decided that the temperature would rapidly decrease until 17:00 and be maintained until 17:00 (see Fig. 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.

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 (dl)].

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 (Fig. As explained below, the turbidity of the treated water was maintained at less than 2 degrees due to the influence of It was maintained, and it was changed to -3 at 19:00 to 2
It was maintained until 4 o'clock (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 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.
The concentration decreased to 17.5 mg/l at 17:00 and was maintained until after 19:00, and then decreased to 15 mg/l after 19:00.
It was decided that it would be maintained until 4 o'clock (Fig. 7 tc+
reference). 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 gradually decreased from 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 the 4th stage. It gradually increases from less than 1 degree to 2 degrees in 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 7 (
d)? (see).

As is clear from the above description of 2 and 2, in Example 2, compared to Comparative Example 2, the target value of the flowing current given to the comparison circuit can suitably follow the fluctuations in the temperature of the raw water, and as a result, the amount of coagulant injected can be adjusted. As a result, fluctuations in the turbidity of the treated water were reliably suppressed.

3. In addition, with reference to FIGS. 8 to 11(a) to (el), the third embodiment of the flocculant injection control method according to the present invention will be explained, thereby controlling the flocculant injection. 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 an additional raw water thermometer of 18A compared to the first embodiment to measure raw water pH, raw water temperature, and 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.

That is, in the third embodiment, the raw water pH measured by the raw water p)I meter 18 and the raw water temperature measured by the raw water thermometer 18A function as indicators equivalent to the raw water pH in the first embodiment. (Figure 9(a) to fc
) and FIGS. 1O(a) to (cl).

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, while referring to FIGS. 8 to 11 (al to (e)), in order to further deepen the understanding of the third embodiment of the flocculant injection control method according to the present invention, This 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 throughput of the raw water (i.e. suspension water) was given as room''/hour, 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 65 as shown in FIG. 11(a).

Further, the temperature of the raw water changed between 25° C. and 15° C. as shown in FIG. 11(a) with the passage of time from the start of operation. Incidentally, the raw water concentration was almost constant at 20 degrees. Furthermore, the turbidity of the treated water was targeted at 2 degrees.

In the first stage of bleed soil (that is, from 0:00 to 1:00), 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 temperature of the raw water measured by the raw water thermometer and given to the setting device is 25 °C.
(See Figure 10 +b+) Therefore, the target value of the flowing current (optimal flowing current in this case) output from the setting device and given to the comparison circuit was -3 (see 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 (that is, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison result was that the target value of the flowing current was kept constant, so it was maintained at zero.

In the control device, since the comparison result was maintained at 0, the flocculant injection amount was maintained at 8 tag/l and was given to the flocculant injection device as a flocculant injection control signal (Fig. 11(d)). ), by the way, 811 g/l was determined by a separately carried out jar test.

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 (Figure 11 (el e
(see).

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 given to the setting device measured by the raw water thermometer gradually decreased from 25°C to 15°C (see Figure 11 (bl)), so the temperature of the raw water given to the setting device as measured by the raw water thermometer gradually decreased from 25°C to 15°C (see Fig. The target value of the given flowing current (optimal flowing current here) is from -3 to 0 during the period from 1 o'clock to 5 o'clock.
(see Fig. 11 (cl)).

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 (in this case, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison results showed that the target value of flowing current gradually increased as the raw water pH decreased and the raw water temperature decreased.

In the control device, as the comparison results gradually increased, the flocculant injection amount was gradually increased from 8111 g/l to 15 B/j, and was given to the flocculant injection device as a flocculant injection control signal (11th Figure (see 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.

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 3 degrees, and then decreased to 2 degrees again (see Figure 11 (el)).

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 (Figure 11 (a) 4 towns, and the temperature of the raw water measured by the raw water thermometer and given to the setting device is 15.
℃ (see Figure 11 (bl)), the target value of the flowing current output from the setting device and given to the comparator circuit (
Here the optimal flowing current) was kept at 0 (the first
Figure 1 fcl t=).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter is compared with the target value of the flowing current (in this case, the optimum flowing current) given by the setting device, and the comparison result is given to the control fi1 device.
It was done. The comparison result was that the target value of the flowing current was maintained at O because it was constant.

In the control device, since the comparison result was maintained at O, 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.

The turbidity of the treated water discharged from the settling basin was measured with a treated water turbidity meter, and the turbidity ranged from 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, it increased from 1.5 degrees to 3 degrees, and was maintained at 2 degrees during the period from 8:00 to 13:00, which corresponds to the early to middle stage of the third stage (see Figure 11(e)).

In the fourth stage (that is, the period from 13:00 to 17:00), the raw water p)I measured by the raw water pH meter and given to the setting device gradually increases from 6.5 to 7.5. As 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+bl), 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+bl), so the temperature of the raw water was output from the setting device and given to the comparison circuit. The target value of the flowing current (here the optimum flowing current) was gradually decreased from 0 to -3 (see Figure 11 fc)).

In the comparison circuit, the measured value of the flowing current by the flowing ammeter was compared with the flowing current target (i (in this case, the optimum flowing current)) given by the setting device, and the comparison result was given to the control device. , since the target value of flowing current gradually decreased as the raw water pH increased and the raw water temperature increased;
It gradually decreased.

In the control device, since the comparison result gradually decreased, the injection amount of the flocculant was gradually decreased from 15 mg/l to 8 mg71, and was given to the flocculant injection device as a flocculant injection control signal (Fig. 11 ( d) e-sho).

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 was maintained at 2 degrees during the period from 13:00 to 16:00, which corresponds to the latter half of the third stage, and during the fourth stage. During the period from 16:00 to 17:00, which corresponds to the initial period, the temperature increased from 2 degrees to nearly 3 degrees, and then decreased to 2 degrees (Fig. 11(e)
(see l).

In the fifth stage (that is, the period from 17:00 to 24:00), the raw water PTI measured by the raw water pH meter and given to the setting device is 75 (see Figure 11 (a)), and the raw water PTI 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(b)), the flow current output from the setting device and given to the comparator circuit was m.
(at here the optimal flowing current) was maintained at −3 (see FIG. 11 (cl)).

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 (in this case, the optimum flowing current) given by the setting device, and the comparison result was given to the control device. The comparison result was that the target value of the flowing current was kept constant, so it was maintained at zero.

In the control device, since the comparison result was maintained at 0, the flocculant injection amount was maintained at 81T1 g/i, and was given to the flocculant injection device as a flocculant injection control signal (11th
(See figure (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 rapid stirring pond flow specific water was slowly stirred and then fed to the settling pond as slowly stirring 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 it fluctuated around 2 degrees during the period from 17:00 to 20:00, which corresponds to the middle to late stage of the 4th stage. It was maintained at 2 degrees during the period from 20:00 to 24:00, which corresponds to the early to middle stage of the fifth stage (see FIG. 11(e)).

In the first stage (i.e. 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 7.5 (see Figure 11 (al)), 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 fb)), and if 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, the turbidity of the treated water will be as described below ( Since it has not been measured yet, the target value of the flowing current output from the setting device and given to the comparison circuit is
-3 (Figure 11 (CI!)).

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 provided to the control device.

The control device adjusts the injection amount of coagulant depending on the comparison result.
Bmg/l (Fig. 11).
(see a+). The injection amount of the flocculant was given to the flocculant injection device as a flocculant injection control signal. By the way, 8m
g/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 set value of the flowing current (see Figure 11).
(see e)).

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 measured by the raw water thermometer and given to the setting device gradually decreased from 25°C to 15°C (
As shown in Figure 11 (bl ?), the target value of the flowing current output from the setting device and given to the comparator circuit is determined by the elapsed time from the start of operation, the retention time ( In other words, the turbidity of the treated water was maintained at -3 during the period from 1:00 to 3:00, when it had not yet been measured as described below, and during the period from 3:00 to 4:00, which corresponds to the first stage. It was maintained at -3, and then changed to -2 at 4:00, which corresponds to the beginning of the second stage, and then maintained until 5:00 (
Figure 11fcl? (see).

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/l to 4 mg/l during the period from 1 o'clock to after 4 o'clock
It was determined that the amount of coagulant injected was to gradually decrease to 7.5 mg/j after 4 o'clock, increase to 7.5 mg/j after 4 o'clock, and maintain it until 5 o'clock (see Figure 11). 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.

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 (el)).

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 fed to the setting device was 65 (see Figure 11 (al)), and the temperature of the raw water measured by the raw water thermometer and fed to the setting device was 15°C (see Figure 11 (al)). Figure 11(b) (see Figure 11(b)) shows that the turbidity of the treated water fluctuated as explained below due to the influence of the second stage.
The target value of the flowing current output from the setting device and given to the comparator circuit is set to -1 at 5 o'clock, maintained until 6 o'clock, set to O at 6 o'clock, maintained until 7 o'clock, and set to 0 at 7 o'clock.
After being set to 5, it was maintained until 12:00, and when it was set to 0 at 12:00, it was also maintained until 13:00 (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.
Increased to 121T1g/l at 5 o'clock and maintained until 6 o'clock, increased to 15 mg/j at 6 o'clock and maintained until 7 o'clock,
It was decided that the dose would increase to 17.5 mg/j at 7:00 and be maintained until 12:00, and then decrease to 15 mg/j at 12:00 and be maintained until 1:00 pm (see Figure 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.

As measured by a treated water turbidity meter, the turbidity of the treated water flowing out of the Gadeen pond increased from 4 to 9 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 decreased again to nearly 6 degrees, and then monotonically decreased from 4 degrees to less than 2 degrees during the period from 8:00 to 10:30, corresponding to the early to middle stage of the third stage, corresponding to the middle stage of the third stage. During the period from 10:30 to 13:00, the temperature was maintained at less than 2 degrees Celsius (see Figure 11(e)).

In the fourth stage (i.e. the period from 13:00 to 17:00), the raw water p)I measured by the raw water p)l meter and fed to the setting device gradually increased from 65 to 7.5 (11th
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 section 11 fbl), but in the latter half of the third stage Because the turbidity of the treated water was maintained at less than 2 degrees due to the initial influence of the fourth stage, as described below, the target value of the flowing current output from the setting device and given to the comparison circuit was 1.
It is maintained at O during the period from 3:00 to 16:00, and - at 16:00.
1 and then maintained until 17:00 (Figure 11 fc)
? (see).

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 increased monotonically from 15 mg/j to 40 mg/l during the period from 13:00 to 15:30, and from 15:30 to 14:00
It was determined that the injection amount of the flocculant was decreased from 40 mg/l to 30 mg/l during the period up to 17:00 and maintained until 17:00 (see Fig. 11 (see C11')). as given to the flocculant injection device.

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 (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 7.5 (see Figure 11 (al)), and the raw water pH measured by the raw water thermometer is 7.5. The concentration of the raw water supplied to the setting device was 25°C (see Figure 11 (b)), and as will be explained later due to the influence of the fourth stage (the turbidity of the treated water was maintained at less than 2°C, The target value of the flowing current outputted from the setting device and given to the comparator circuit is set to -2 at 17:00 and maintained until 19:00, then set to -3 at 19:00 and maintained until 24:00 (C). ) reference).

In the comparison circuit, the measured value of the flowing current by the flowing current meter is compared with the target value of flowing current given from the setting device, and the comparison result is given to the control device. According to , decided (11th
Figure (see 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.

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 (Figure 11 (e) 4 towns.

As is clear from the above description of Example 3 and f913, in Example 3, compared to Comparative Example 3, the target value of the flowing current given to the comparison circuit can suitably follow the fluctuations in raw water pH and raw water temperature, and as a result, the flocculation There were no problems with the injection amount of the agent, and as a result, fluctuations in the turbidity of the treated water were reliably suppressed.

(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 depending on the properties of the raw water.
As clearly stated as a means of solving
(t) It has the effect of being able to determine the injection amount of the flocculant 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 (iii). 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 part of [Problem Solution 1], (at to fiv) It has the effect of being able to determine the injection amount of the flocculant in response to changes in the raw water temperature, and as a result, it has the effect of the above [iil (iii) as well as the first flocculant injection control method described above.

The third 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 matter from the raw water, remove the precipitate, and discharge it as treated water. In particular, as specified as the third solution in the latter part of [Means for solving the problem],
(v) It has the effect of being able to determine the amount of coagulant to be injected in immediate 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 drawings]

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. (di is the first
FIG. 5 is an operation explanatory diagram for explaining a specific example of the embodiment. FIG. 6(a) to (C+ is an operational explanatory diagram for explaining the embodiment in FIG. 5, and FIG. 7(a)
1 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 in operation, FIGS. 9(a) to (c) are operation explanatory diagrams for explaining the embodiment in FIG. 5, and FIGS. 10(al to c) are Other operation explanatory diagrams for explaining the embodiment in FIG. 8, and FIGS. 11(a) to (e) are operation explanatory diagrams for explaining a specific example of the embodiment in FIG. 8. 10.・・・ 11A, 11B llC... 2 3 3A 3B 4 14A ・・・ 14B ・・・・・・ 15・・・・・・・・・ 16... 16A ・・・ 16B ・・・ ・・・18... 18A... Coagulation sedimentation treatment equipment, raw water supply pipe, treated water discharge pipe, landing well, rapid stirring pond, driving source, stirring member, slow stirring pond, driving source, stirring member, settling tank. ...Coagulant injection device Coagulant storage tank metering pump Raw water p) I meter Raw water thermometer l9 ......Flowing current meter 19a...
・・・・・・Water sampling vibrator 19a゛・・・・・・Water sampling pump 19b...
...Drainage pipes 19c, 19d...
Connection wire 19A...... Cylindrical container 19B, 19C... Electrode 190... Power source 19E... Piston 19F・・・・・・・・・Ammeter 20・・・・・・・・・・・・Treatment water turbidity meter 21・・
.........Setting device 22...
......Comparison circuit 23...
・Control device engineer

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 a hydrogen ion concentration index of raw water; (b) a second step of measuring a flowing current of raw water into which a flocculant has been injected; (c) a first step. a third step of selecting a set value of the flowing current according to the hydrogen ion concentration index of the raw water measured in the step of (d) determining the set value of the flowing current as a target value of the flowing current; a fourth step of comparing the target value of current and the measured value of the flowing current measured in the second step; (e) determining the amount of coagulant to be injected according to the results of the comparison in the fourth step; A flocculant injection control method characterized by comprising a fifth step of: (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 into which a flocculant has been injected; (c) in the first step. (d) selecting a set value of the flowing current according to the measured raw water temperature and determining it as the target value of the flowing current; (d) comparing the target value of the flowing current determined in the third step with the set value of the flowing current; a fourth step of comparing the measured value of the flowing current measured in step 2, and (e) a fifth step of determining the amount of coagulant to be injected according to the results of the comparison in the fourth step. A flocculant injection control method comprising: (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 flow of the raw water into which the flocculant has been injected. a third step of measuring the current; (d) selecting a set value for the flowing current according to the hydrogen ion concentration index of the raw water measured in the first step and the concentration of the raw water measured in the second step; and (e) comparing the target value of the flowing current determined in the fourth step with the measured value of the flowing current measured in the third step. A flocculant injection control method comprising: a fifth step; and (f) a sixth step of determining the amount of flocculant to be injected according to the results compared in the fifth step.