JP2016030228A - Method for controlling flocculation conditions of floc, device for controlling flocculation conditions of floc, water treatment method and water treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling flocculation conditions of floc which makes adjustment of flocculation conditions of the floc suited for water quality after change in a short time irrespective of water quality of water containing the floc.SOLUTION: A method for controlling flocculation conditions of floc includes a moving speed measurement process, a dispersion value calculation process, an evaluation process and a parameter adjustment process. In the moving speed measurement process, moving speeds of a plurality of floc in test water are measured at every floc by applying a voltage to the test water containing the floc collected from a mixing basin. In the dispersion value calculation process, dispersion values in moving speed distributions of the plurality of floc are calculated. In the evaluation process, the quality of flocculation state of the floc is evaluated based on a dispersion value and a target value. In the parameter adjustment process, when the flocculation state of the floc is evaluated as poor, at least either one of injection rate of flocculant in the mixing basin, agitation strength in the mixing basin, dwell time of mixing water in the mixing basin and pH in the mixing basin is adjusted such that the dispersion value is made higher.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a floc aggregation condition control method, a floc aggregation condition control apparatus, a water treatment method, and a water treatment apparatus.

Conventionally, as a method of treating treated water (raw water) such as river water, rainwater, sewage, industrial wastewater, etc., the suspension contained in the raw water using flocculants is made into floc (flocculate), and this is set in a sedimentation basin. There is a method of removing by precipitation. In this method, the state of floc aggregation affects the quality of the treated water.
The floc aggregation state varies depending on the amount of flocculant injected into the raw water. However, the amount of flocculant injected to improve the floc aggregation state varies with fluctuations in the quality of the raw water. For this reason, a method of appropriately controlling the injection amount of the flocculant so as to improve the floc aggregation state in response to fluctuations in the quality of the raw water has been studied.

In order to control floc aggregation conditions such as the amount of flocculant injected into the raw water so that the floc aggregation state is good, it is necessary to evaluate the floc aggregation state. Conventionally, a flow current value, a filtration time index (STR), an average value of a floc surface potential, and the like are used as an index of the floc aggregation state.
However, since the optimum values of the flowing current value and the filtration time index greatly differ depending on the quality of raw water, they cannot be widely used. Further, the average value of the surface potential of the floc was difficult to determine whether or not the floc aggregation state was good. For this reason, even if the aggregation conditions of flocs are controlled using these indexes, the effect of controlling the aggregation conditions may not be sufficiently obtained.

  There is also a technique for controlling the injection amount of the flocculant into the mixing basin by evaluating the filtration time index of the basin outlet water, which is the supernatant water obtained by precipitating flocs in the basin. However, with this technology, it takes a long time to change to the floc aggregation conditions suitable for the water quality after the change according to the quality of the raw water, so it was difficult to obtain the effect of controlling the aggregation conditions. .

Japanese Patent No. 3522650 JP2013-198865A Japanese Patent No. 5131005

  The problem to be solved by the present invention is that flocs that can be adjusted to floc aggregation conditions suitable for the changed water quality in a short time when the water quality changes, regardless of the water quality of the floc-containing water. A coagulation condition control method, a floc coagulation condition control device, a water treatment method, and a water treatment device are provided.

The floc aggregation condition control method of the embodiment includes a moving speed measurement step, a dispersion value calculation step, an evaluation step, and a parameter adjustment step.
The moving speed measuring step is a step in which an anode and a cathode are arranged in test water containing flocks collected from the mixing pond, and a voltage is applied to the test water to measure the moving speeds of the plurality of flocks for each flock. The dispersion value calculating step assigns a first code when the vector of the moving speed of the floc includes a component in the anode direction, and assigns a second code when the vector includes a component in the cathode direction, In this step, the moving speed of the code and the moving speed of the second code are totaled for each predetermined size, and a variance value in the moving speed distribution of the plurality of flocks is calculated. An evaluation process is a process of evaluating the quality of the floc aggregation state based on the dispersion value and the target value. In the parameter adjustment step, when the floc aggregation state is evaluated as poor, the injection rate of the flocculant in the mixing pond, the stirring strength in the mixing pond, the residence time of the mixed water in the mixing pond, the mixing This is a step of adjusting any one or more parameters of pH in the pond so that the dispersion value becomes high.

It is explanatory drawing for demonstrating the principle of the floc aggregation condition control method. It is the graph which showed the relationship between the increase / decrease rate of the supply amount of raw | natural water, and the increase / decrease rate of a dispersion value. It is the graph which showed the relationship between the increase / decrease rate of stirring intensity | strength and the increase / decrease rate of a dispersion value. It is the graph which showed the relationship between the pH of the mixing water of a rapid mixing pond, and a dispersion value. It is the schematic which shows an example of a water treatment apparatus provided with the floc aggregation condition control apparatus of 1st Embodiment. It is explanatory drawing for demonstrating a part of floc aggregation condition control apparatus with which the water treatment apparatus shown in FIG. 5 was equipped. It is explanatory drawing for demonstrating an example of the water treatment method using the water treatment apparatus shown in FIG. It is explanatory drawing for demonstrating an injection rate setting process. It is the graph which showed the relationship between the collection place of the test water in a mixing basin, and the increase / decrease rate of a dispersion value.

  A floc aggregation condition control method, floc aggregation condition control apparatus, water treatment method and water treatment apparatus according to embodiments will be described below with reference to the drawings.

  Suspended matter in raw water, which is the water to be treated at a water purification plant, usually has a negative charge. When the flocculant is injected into the raw water, suspended substances in the raw water aggregate to form flocs. It is considered that the negative charge of the suspended substance is canceled by the flocculant having a positive charge, so that the surface charge of the suspended substance approaches 0 and the repulsion between the suspended substances weakens and the formation of flocs proceeds. ing.

  If the injection rate of the flocculant is too low, the negative charge of the suspended substance is not sufficiently canceled out, the surface charge of the suspended substance remains negative, and floc formation does not proceed sufficiently. On the other hand, if the injection rate of the flocculant is too high, the surface charge of the suspended substance has a positive value due to the positive charge of the flocculant. When the absolute value of the positive surface charge increases rapidly, the repulsion between suspended substances increases and the formation of flocs does not proceed.

  In addition, when a DC voltage is applied from a pair of electrodes to mixed water obtained by adding a flocculant to raw water, if the surface charge of the floc has a negative value, the floc moves toward the anode by electrophoresis. When the surface charge of the floc has a positive value, the floc moves toward the cathode by electrophoresis. In addition, the larger the absolute value of the surface charge of the floc, the stronger the influence of applying a voltage to the water mixture, so the moving speed of the floc increases. Therefore, the moving speed of the floc has a correlation with the absolute value of the surface charge of the floc.

  The surface charge of the floc is around 0 mV when the aggregation state is good. For this reason, when the flocs are well aggregated, even if a voltage is applied to the mixed water containing flocs, the movement of the flocs in the mixed water does not occur in one direction due to electrophoresis. Is mainly due to the movement of gravity and water flow in the water.

  The present inventors pay attention to such a phenomenon, measure the moving speed of a plurality of flocs in the admixture water when a DC voltage is applied to the admixture water, and calculate a plurality of flocs calculated by the following method. It was found that the quality of floc aggregated state can be evaluated by using the dispersion value in the moving speed distribution. Further, it was found that the evaluation result of the floc aggregation state can be suitably used when controlling the floc aggregation condition.

  The dispersion value in the movement speed distribution of a plurality of flocs was obtained as follows. When the movement speed of each floc is measured and the vector of the movement speed of the floc includes a component in the anode direction, a negative sign is given to the movement speed, and the vector of the movement speed of the floc includes a component in the cathode direction Is given a plus sign for its moving speed. Then, the negative moving speed and the positive moving speed were totaled for each predetermined size, and the variance value was calculated by a statistical method.

  (A) to (D) shown in FIG. 1 show surface potential (moving speed) distributions of a plurality of flocs prepared by applying a voltage to mixed water having different injection rates of the flocculant and by the same method as the dispersion value described above. It is an example of a histogram. Since the surface potential of the flock has a correlation with the absolute value of the moving speed of the flock as described above, the shape of the histogram of the surface potential distribution of the flock is the same as the histogram of the moving speed distribution of the flock. In the graphs (A) to (D) shown in FIG. 1, the horizontal axis indicates the magnitudes of a negative surface potential (moving speed) and a positive surface potential (moving speed). It is classified according to (moving speed). The vertical axis indicates the number of detections.

  When the floc state of the flocs in the mixed water is good, even if a voltage is applied to the mixed water, the flocs that are biased in one direction do not move. For this reason, the detected number is sparse in a wide range without being biased toward the positive region or the negative region. Accordingly, the variance value σ of the movement speed distribution of the flock is increased, and the histogram has a flat distribution shape (see, for example, the histograms (B) and (C) in FIG. 1).

  On the other hand, if the flocs in the admixed water are poorly aggregated, the floc movement direction is biased toward the cathode or anode, so the histogram of floc movement speed distribution is in the positive or negative area. A shape having a sharp peak is obtained (see histograms (A) and (D) in FIG. 1). Accordingly, the dispersion value σ of the floc moving speed distribution is small as compared with the case where the injection rate of the flocculant in the mixed water is appropriate.

  Thus, the dispersion value σ of the floc moving speed distribution tends to be large when the floc aggregation state in the mixed water is good and small when the floc aggregation state in the mixed water is poor. . Therefore, the quality of the floc aggregation state can be evaluated based on the dispersion value σ of the floc moving speed distribution.

In addition, as shown below, the present inventors compare the dispersion value σ of the floc moving speed distribution with a preset target value to determine whether the floc aggregation state is good or bad. I found out that I can judge.
For example, the graph of (E) in FIG. 1 shows the relationship between the dispersion value of the floc moving speed distribution and the injection rate of the flocculant in the mixed water. The points in the graph (E) in FIG. 1 correspond to the variance value σ of the movement speed distribution of the flock shown by the histograms (A) to (D) in FIG.

In the example shown in FIG. 1, the variance value σ of the histogram of (C) is equal to or greater than the target value in the graph of (E) in FIG. 1, and it is determined that the floc aggregation state is good.
Also, the variance value σ of the histograms (A) and (D) in FIG. 1 is very small compared to the target value in the graph (E) in FIG. 1, and it is determined that the floc aggregation state is poor. Is done.
Further, although the variance value σ of the histogram (B) in FIG. 1 is considerably larger than the variance value σ of the histograms (A) and (D), it is less than the target value, so the floc aggregation state is poor. It is judged that.

  Furthermore, the present inventors, as shown below, when the variance value of the floc moving speed distribution is less than the target value, depending on whether the average value of the floc moving speed distribution is greater than 0 or less than 0. The present inventors have found that it is possible to determine whether the injection rate of the flocculant in the mixed water is insufficient or excessive.

  Specifically, when the dispersion value is less than the target value and the average value is a negative value, it is determined that the injection rate of the flocculant in the mixed water is insufficient. When the dispersion value is less than the target value and the average value is a positive value, it is determined that the injection rate of the flocculant in the mixed water is excessive.

For example, the number of detections indicated by the histogram of (D) in FIG. 1 has a sharp peak in the positive region, and the average value of the distribution of floc moving speed is a positive value. Therefore, it is determined that the coagulant having a positive charge is excessively contained in the mixed water.
In addition, the number of detections shown in the histogram of FIG. 1A has a sharp peak in the negative region, and the average value of the distribution of floc moving speeds is a negative value. Therefore, it is judged that the flocculant having a positive charge is insufficient in the mixed water.

  Therefore, when the dispersion value is less than the target value and the average value is a negative value, the dispersion value can be increased by increasing the injection rate of the flocculant in the mixed water. Further, when the dispersion value is less than the target value and the average value is a positive value, the dispersion value can be increased by reducing the injection rate of the flocculant in the mixed water.

  In addition, when the dispersion value is less than the target value, the present inventors not only adjust the injection rate of the flocculant in the mixing pond from which the mixed water used for calculating the dispersion value is collected, but also the flocculant. In addition to the injection rate of the flocculant or together with the injection rate of the flocculant, the stirring strength in the mixing pond from which the mixed water used to calculate the dispersion value was collected, the residence time of the mixed water in the mixing pond, and the pH in the mixing pond It was found that the dispersion value can be increased by adjusting any one or more parameters.

  The residence time of the mixed water in the mixing pond from which the mixed water used for calculating the dispersion value is collected can be adjusted by the supply amount (flow rate) of the raw water supplied to the mixing pond. That is, if the supply amount of the raw water supplied to the mixing pond is reduced, the residence time (treatment time) of the mixed water in the mixing pond becomes longer, and the floc aggregation state of the mixed water in the mixing pond is improved. For this reason, a dispersion value becomes high.

FIG. 2 is a graph showing the relationship between the increase / decrease rate of the supply amount of raw water and the increase / decrease rate of the variance value σ of the floc moving speed distribution. The results shown in FIG. 2 are obtained by measuring the rate of increase / decrease of the dispersion value when the conditions other than the supply amount (flow rate) of raw water are the same.
As shown in FIG. 2, the dispersion value increases as the supply amount of raw water decreases. Accordingly, by reducing the amount of raw water supplied to the mixing basin and increasing the residence time of the mixing water in the mixing basin, the state of floc aggregation in the mixing water can be improved.

  Moreover, the aggregation state of flocs in the mixed water in the mixing pond can also be improved by increasing the stirring strength in the mixing pond from which the mixed water used for calculating the dispersion value is collected. For this reason, a dispersion value becomes high.

FIG. 3 is a graph showing the relationship between the increase / decrease rate of the stirring intensity and the increase / decrease rate of the dispersion value σ of the floc moving speed distribution. The results shown in FIG. 3 are obtained when the conditions other than the stirring strength in the mixing pond in which the mixed water used for calculation of the dispersion value is collected are the same for two types (◯ and □ in FIG. 3) having different raw water quality. This is a measurement of the rate of increase / decrease of the dispersion value of the movement speed distribution of the flock.
As shown in FIG. 3, although there is a difference in slope depending on the quality of the raw water, the dispersion value of the floc moving speed distribution increases with increasing the stirring intensity in the mixing pond regardless of the quality of the raw water. It has become. Therefore, the floc aggregation state in the mixed water can be improved by increasing the stirring strength in the mixing pond from which the mixed water used for calculating the dispersion value is collected.

  Thus, the dispersion value can be increased by increasing the stirring strength in the mixing basin and / or by increasing the residence time of the mixed water in the mixing basin.

  Moreover, the floc aggregation state in the mixed water in the mixing pond is improved by adjusting the pH in the mixing pond from which the mixed water used for calculating the dispersion value is collected within a predetermined range. For this reason, a dispersion value becomes high.

FIG. 4 is a graph showing the relationship between the pH of the mixed water in the mixing pond from which the mixed water used for calculation of the dispersion value was collected and the dispersion value σ of the floc moving speed distribution. The results shown in FIG. 4 are obtained by measuring the dispersion value of the floc moving speed distribution when the conditions other than the pH of the mixed water in the mixing pond in which the mixed water used for calculating the dispersion value was collected are the same.
As shown in FIG. 4, when the pH of the mixed water in the mixing pond is 6.5 to 7.0, the dispersion value of the floc moving speed distribution is high. Therefore, by adjusting the pH of the mixed water in the mixing basin so that the dispersion value of the movement speed distribution of the flocs is increased, the floc aggregation state in the mixed water in the mixing pond is improved. For this reason, a dispersion value becomes high.

Next, a water treatment apparatus provided with the floc aggregation condition control apparatus of the first embodiment shown in FIG. 5 will be described. In the present embodiment, a water treatment apparatus installed in a water purification plant will be described as an example of a water treatment apparatus including a floc aggregation condition control device.
The water treatment apparatus 1 includes a landing well 10, a mixing basin 22, a sedimentation basin 40, a filtration basin 50, and a floc aggregation condition control device 60.

  The landing well 10 contains raw water to be treated by the water treatment apparatus 1. The landing well 10 is connected to the rapid mixing basin 20 of the mixing basin 22 by piping. The piping connecting the landing well 10 and the rapid mixing basin 20 includes a flow meter 63 that measures the flow rate of raw water that passes through the piping and is supplied to the mixing basin 22, and a pH measurement device 74 that measures pH. is set up.

The mixing pond 22 contains mixed water containing flocks (aggregates) generated by mixing raw water and a flocculant. The raw water introduced into the landing well 10 is continuously supplied to the rapid mixing basin 20 of the mixing basin 22 at a predetermined flow rate by a flow rate adjusting valve 72 through a pipe.
The mixing basin 22 has a rapid mixing basin 20 and a flock formation pond 30 connected to the rapid mixing basin 20 by piping.
The rapid mixing basin 20 of the mixing basin 22 includes raw water supplied from the landing well 10, a flocculant injected by the flocculant injection device 70, and a pH adjuster injected by the pH adjuster injection device 71 as necessary. And to accommodate. In the rapid mixing pond 20, suspended substances contained in the raw water are flocked by the flocculant, and mixed water containing flocks is generated.

  The flock formation pond 30 is for growing flocs in the mixing water supplied from the rapid mixing pond 20. The flock formation pond 30 has three agitation ponds 31, 32 and 33. The mixed water generated in the rapid mixing basin 20 is supplied to the first stirring basin 31 of the flock formation pond 30. The mixed water that has passed through the first stirred basin 31 is supplied to the second stirred basin 32, and the mixed water that has passed through the second stirred basin 32 is supplied to the third stirred basin 33.

  The rapid mixing basin 20, the first agitation basin 31, the second agitation basin 32, and the third agitation basin 33 are respectively provided with agitation devices 21, 34, 35, and 36 driven by a motor, for example. The stirring devices 21, 34, 35, and 36 are set so that the stirring strength of the mixed water in each pond forming the mixing pond 22 decreases stepwise from the upstream side toward the downstream side. As the stirring device 21, for example, a flash mixer can be used. As the stirring devices 34, 35, and 36, for example, flocculators can be used.

The sedimentation basin 40 is provided downstream of the third stirring basin 33. The sedimentation basin 40 accommodates mixed water containing flocs supplied from the blending basin 22 and precipitates flocs.
The filtration basin 50 is provided downstream of the sedimentation basin 40. The filtration basin 50 is supplied with the supernatant water obtained by retaining the mixing water supplied from the mixing basin 22 in the sedimentation basin 40 for a predetermined time or more. The filtration basin 50 is, for example, a sand filtration device. When the supernatant water supplied to the filtration basin 50 passes through the filtration basin 50, the fine flocs that have not been removed by the sedimentation basin 40 are removed and discharged as clean water (treated water).

Next, the floc aggregation condition control device 60 of this embodiment will be described. In this embodiment, test water is collected from the mixing basin 22 of the water purification plant, the aggregation state of the mixed water in the mixing basin 22 is evaluated, and the floc aggregation condition in the mixing basin 22 is determined using the evaluation result. The case of controlling will be described as an example.
The floc aggregation condition control device 60 includes a moving speed measurement device 80, a dispersion value calculation device 81, an evaluation device 90, a parameter adjustment device 91, and an injection rate determination device 73.

  The moving speed measuring device 80 includes a cell 61 (FIG. 6) that stores test water containing floc collected from the mixing pond 22, a voltage supply device 62 (FIG. 6) that applies a voltage to the test water in the cell 61, And a flock tracking device 65 (FIG. 7) for measuring the position of the flock in the test water when a voltage is applied to the test water.

The cell 61 contains test water. The cell 61 is preferably formed of a transparent material such as glass or acrylic.
The voltage supply device 62 applies a voltage to the test water in the cell 61 by an anode 62 a and a cathode 62 b that are disposed opposite to each other in the cell 61. The voltage supply device 62 preferably applies a voltage of 10 to 20 V to the test water.

  The flock tracking device 65 flocks the position of the plurality of flocks in the test water when a voltage is applied to the test water by the voltage supply device 62 at least at a first time and a second time after a predetermined time has elapsed from the first time. It is measured every time. The flock tracking device 65 may be any device that can measure the position of the flock at least at the first time and the second time so that the movement speed of the plurality of flocks can be calculated. Further, it may be performed a plurality of times every predetermined time, or may be performed continuously for a predetermined time. When the measurement of the position of the flock is performed a plurality of times every predetermined time, for example, the position of the flock may be measured every second.

  As the flock tracking device 65, a light source that emits light toward the inside of the cell 61, a camera that photographs flocks contained in the test water, and a display device 65a that displays a signal input by photographing using the camera. It is preferable to use what has these.

  Any light source may be used as long as it can irradiate the test water in the cell 61 with light. It is preferable to use a light source that can adjust the intensity of light. Moreover, what irradiates a laser beam, for example can be used as a light source.

The camera is preferably installed on the outer surface of the side surface of the cell 61 where the anode 62a and the cathode 62b are not installed. In this case, since the test water including the floc in the cell 61 is photographed through the wall surface of the cell 61, the cell 61 made of a transparent material is used.
As the camera, for example, a camera that receives scattered light on the surface of the floc obtained by irradiating the floc in test water with a light source can be used.

  The variance value calculation device 81 receives the signals of the positions of a plurality of flocks included in the test water measured by the flock tracking device 65, and generates a vector of the moving speed of each flock. Further, the variance value calculation device 81 gives a minus (first sign) when the generated vector includes a component in the anode 62a direction, and gives a plus (second sign) when the generated vector contains a component in the cathode 62b direction. To do. Further, the variance value calculation device 81 calculates a variance value in the movement speed distribution of a plurality of flocks by totaling the negative movement speed and the positive movement speed for each predetermined size.

The variance value calculation device 81 uses all of the negative movement speeds (all the components of the vector of the movement speed) as the negative movement speeds used for the aggregation, and the positive movement speed as the positive movement speed used for the aggregations. (All moving velocity vector components) can be used.
Further, the variance value calculation device 81 uses only the movement speed of the component in the direction of the anode 62a included in the movement speed vector of each flock among the negative movement speeds as the negative movement speed used for the aggregation, and the aggregation. As the positive moving speed used for the above, only the moving speed of the component in the cathode 62b direction included in the vector of the moving speed of each floc among the positive moving speeds may be used.

It is preferable that the variance value calculation device 81 calculates an average value of the negative movement speed and the positive movement speed of the movement speeds of the plurality of flocks.
In addition, the dispersion value calculation device 81 sets the moving speed having no velocity component in the cathode direction and the anode direction to zero.

  The function of calculating the variance value of the variance value calculation device 81 and the function of calculating the average value of the minus movement speed and the plus movement speed of the movement speeds of a plurality of flocks are provided, for example, in a central processing unit of a computer. Realized by function.

The evaluation device 90 evaluates the quality of the floc aggregation state based on the dispersion value and the target value calculated by the dispersion value calculation device 81.
Based on the dispersion value calculated by the dispersion value calculation device 81, the evaluation device 90 determines that the floc aggregation state is good when the dispersion value is equal to or greater than the target value, and the dispersion value is less than the target value. In this case, the floc aggregation state is judged to be defective. The target value of the dispersion value is a measured value of the dispersion value in a beaker test using a plurality of beakers and the flocculant injection rate as a parameter, or a filtration time index (Suction time ratio: STR) discharged from the sedimentation basin 40. ) In advance.

When the evaluation of the floc aggregation state is poor, the evaluation device 90 is based on the average value of the negative movement speed and the positive movement speed of the movement speeds of the plurality of flocks calculated by the variance value calculation apparatus 81. The floc aggregation state and the flocculant excess / deficiency state are preferably evaluated.
Specifically, the evaluation device 90 determines that the flocculant state in the test water is insufficient when the floc aggregation state is evaluated as poor and the average value is negative. It is preferable.
The evaluation device 90 preferably determines that the flocculant injection rate in the test water is excessive when the floc aggregation state is evaluated as poor and the average value is a positive value.

  The evaluation device 90 preferably generates a histogram of the movement speed distribution of the flocks based on the total result of the variance value calculation device 81 and displays the histogram on the display device. Furthermore, the evaluation device 90 evaluates the floc aggregation state, determines whether the floc aggregation state is good or bad, and whether the flocculant injection rate is insufficient or excessive. One or more results may be displayed on the display device among the determination result and the real-time image or moving image of the display device included in the flock tracking device 65.

The evaluation device 90 may display the histogram and / or any of the above results on the display device 65a included in the flock tracking device 65, or a display different from the display device 65a of the flock tracking device 65. It may be displayed on a device.
When the evaluation apparatus 90 of the present embodiment determines that the evaluation of the floc aggregation state is poor, the evaluation apparatus 90 inputs a signal indicating the result of the determination that the evaluation of the floc aggregation state is poor to the parameter adjustment apparatus 91. It is. Further, the evaluation device 90 of the present embodiment is a parameter adjusting device when it is determined that the injection rate of the flocculant in the test water is insufficient or when it is determined that the injection rate of the flocculant in the test water is excessive. In 91, a signal indicating that the injection rate of the flocculant is insufficient or a signal indicating that the injection rate of the flocculant in the test water is excessive is input.

  A function of evaluating the floc aggregation state of the evaluation device 90, a function of determining whether the floc aggregation state is good or bad, a function of determining whether the injection rate of the flocculant is insufficient or excessive, The function of generating the histogram of the flock movement speed distribution is realized, for example, by a function provided in the central processing unit of the computer.

When the evaluation device 90 evaluates that the floc aggregation state is poor, the parameter adjustment device 91 is configured such that the flocculant injection rate in the mixing pond 22 from which the test water is collected, the stirring strength in the mixing pond 22, and the mixing One or more parameters of the mixing water residence time in the pond 22 and the pH in the mixing pond 22 are adjusted so that the dispersion value becomes high.
The parameter adjustment device 91 controls the stirring strength in the mixing basin 22 to be increased and / or the mixed water in the mixing basin 22 when the evaluation of the floc aggregation state by the evaluation device 90 is poor. It is preferable to control the residence time to be longer.

When adjusting the injection rate of the flocculant in the mixing basin 22, the parameter adjusting device 91 controls the injection amount of the flocculant injected from the flocculant injection device 70 into the mixing basin 22, thereby aggregating in the mixing basin 22. Adjust the injection rate of the agent.
The parameter adjusting device 91 receives the signal indicating that the injection rate of the flocculant in the test water is insufficient from the evaluation device 90, and thereby determines the injection amount of the flocculant injected from the flocculant injection device 70 into the mixing basin 22. It is preferable to control and adjust so as to increase the injection rate of the flocculant in the mixing water in the mixing pond 22 from which the test water is collected.
Further, the parameter adjusting device 91 receives a signal indicating that the injection rate of the flocculant in the test water is excessive from the evaluation device 90, whereby the injection amount of the flocculant injected from the flocculant injection device 70 into the mixing basin 22 is input. Is preferably adjusted so as to lower the injection rate of the flocculant in the mixing water in the mixing pond 22 from which the test water is collected.

  The parameter adjusting device 91 is provided in each of the rapid mixing basin 20, the first stirring basin 31, the second stirring basin 32, and the third stirring basin 33 when adjusting the stirring intensity in the mixing basin 22 from which the test water is collected. It is performed by controlling the stirring intensity of any one or more of the stirring devices 21, 34, 35 and 36. The parameter adjusting device 91 adjusts the mixing basin so that the dispersion value becomes high based on the relationship between the increase / decrease ratio of the stirring intensity measured in advance and the increase / decrease ratio of the dispersion value of the movement speed distribution of the flock (see FIG. 3 for example) It is preferable to adjust the stirring strength in the inside 22.

  The parameter adjusting device 91 is supplied by the flow rate adjusting valve 72 based on the flow rate of the raw water input from the flow meter 63 when adjusting the residence time of the mixed water in the mixing pond 22 from which the test water is collected. Adjust the amount of raw water supplied. The parameter adjustment device 91 determines the relationship between the increase / decrease rate of the raw water supply amount (the residence time of the admixture water in the mixing pond) and the increase / decrease rate of the dispersion value of the floc moving speed distribution (see, for example, FIG. 2). Based on this, it is preferable to adjust the supply amount (flow rate) of the raw water supplied to the mixing basin 22 so that the dispersion value becomes high.

  The parameter adjusting device 91 is injected by the pH adjusting agent injection device 71 based on the measured value of the pH of the raw water input from the pH measuring device 74 when adjusting the pH in the mixing pond 22 from which the test water is collected. The type and injection amount of the pH adjuster are controlled to adjust the pH of the mixed water in the mixing pond 22. The parameter adjusting device 91 adjusts the mixing in the mixing basin 22 so that the dispersion value becomes high based on the relationship between the pH of the mixing water measured in advance and the dispersion value of the movement speed distribution of the floc (see, for example, FIG. 4). It is preferable to adjust the pH in water.

  Any one or more of the injection rate of the flocculant in the mixing basin 22 by the parameter adjusting device 91, the stirring strength in the mixing basin 22, the residence time of the mixed water in the mixing basin 22, and the pH in the mixing basin 22 The function of adjusting the parameters is realized by, for example, a function provided in the central processing unit of the computer.

  Next, an example of a water treatment method using the water treatment apparatus 1 shown in FIG. 5 will be described with reference to the drawings. The water treatment method of the present embodiment includes a flocculant injection step of injecting a flocculant into raw water to generate mixed water containing floc, a separation step of separating flocs to obtain supernatant water from the mixed water, And a floc control step for controlling agglomeration conditions.

  In the flocculant injection step, first, raw water to be treated by the water treatment device 1 is introduced into the landing well 10. Next, raw water is supplied from the landing well 10 to the rapid mixing basin 20 of the mixing basin 22 through a pipe. Next, a flocculant and a pH adjuster are injected into the raw water continuously supplied to the rapid mixing basin 20 to generate mixed water containing floc. Next, mixed water containing flocs generated in the rapid mixing basin 20 is supplied to the first stirring basin 31 of the floc forming pond 30. The mixed water supplied to the first stirring basin 31 passes through the first stirring basin 31, the second stirring basin 32, and the third stirring basin 33 in this order.

The supply of raw water from the landing well 10 to the rapid mixing basin 20 in the flocculant injection step is continuously performed by a flow rate adjusting valve 72 at a predetermined supply amount.
The flow rate of the raw water supplied to the rapid mixing basin 20 is measured by a flow meter 63 installed in a pipe connecting the landing well 10 and the rapid mixing basin 20 and is input to the parameter adjusting device 91.
Further, the pH of the raw water supplied to the rapid mixing basin 20 is measured using a pH measuring device 74 installed in a pipe connecting the landing well 10 and the rapid mixing basin 20 and is input to the parameter adjusting device 91.
The measurement of the flow rate of raw water and the measurement of pH may be performed continuously from the start to the end of supply of raw water, or may be performed at predetermined time intervals.

  The flocculant is continuously supplied to the rapid mixing basin 20 at a predetermined supply amount by the flocculant injection device 70. As the flocculant, aluminum-based inorganic flocculants, iron-based inorganic flocculants, polymer flocculants, and the like can be used. Examples of the aluminum-based inorganic flocculant include polyaluminum chloride (PAC) and aluminum sulfate (sulfur sulfate).

  The pH adjusting agent is continuously supplied to the rapid mixing basin 20 by a pH adjusting agent injection device 71 in a predetermined type and injection amount. As the pH adjuster, an acidic one such as sulfuric acid or hydrochloric acid or an alkaline one such as sodium hydroxide is used depending on the pH of the raw water. When an alkaline substance such as sodium hydroxide is injected as the pH adjuster, it is preferable to control the injection amount of the pH adjuster so that the alkalinity of the raw water is 15 to 25 degrees, preferably about 20 degrees. .

  In the mixing basin 22, the mixing water containing flocs is stirred by the stirring devices 21, 34, 35, and 36. The agitation strength is maximized in the rapid mixing basin 20 and gradually decreased in the order of the first agitation basin 31, the second agitation basin 32, and the third agitation basin 33. By passing through the mixing basin 22, the raw water and the flocculant mix, and flocs are generated and grow.

Next, a separation process is performed. In the separation step, the mixed water containing floc that has passed through the mixing basin 22 supplied to the settling basin 40 is retained in the settling basin 40 for a predetermined time or more, for example, about 3 hours. As a result, the floc in the mixed water settles and precipitates.
The floc precipitated in the sedimentation basin 40 is treated as sludge. The supernatant water obtained after the floc in the mixed water is settled and separated in the sedimentation basin 40 is sent to the filtration basin 50.

The supernatant water supplied to the filter basin 50 is discharged as clean water after passing through sand filtration. The clean water discharged from the filtration basin 50 is sent to the water purification pond, sterilized with chlorine, etc., and discharged from the water purification pond.
Furthermore, ozone treatment and / or biological activated carbon treatment may be performed on the clean water that has passed through the filtration pond 50. Further, before passing the supernatant water through the filtration basin 50, the supernatant water may be subjected to ozone treatment and / or biological activated carbon treatment.

Next, the flock control process will be described. In the present embodiment, as the flock control step, a floc aggregation condition control method using the floc aggregation condition control device 60 is performed.
In the floc coagulation condition control method, a moving speed measuring step for measuring the moving speed of a plurality of flocs in the test water including the floc collected from the mixing pond 22 for each floc, and a dispersion value in the moving speed distribution of the plural flocs are calculated. Parameters are adjusted so as to increase the dispersion value based on the dispersion value calculation step, the evaluation step for evaluating the quality of the floc aggregation state based on the dispersion value and the target value, and the evaluation result in the evaluation step The parameter adjustment process is performed.

In the moving speed measurement step, first, test water containing floc collected from the mixing basin 22 of the water purification plant is injected into the cell 61.
Next, as shown in FIG. 6, the anode 62a and the cathode 62b of the voltage supply device 62 are arranged in the test water in the cell 61, and a voltage of, for example, 5V to 30V, preferably 10V to 20V is applied to the test water. To do. Then, the movement speed of the plurality of flocks in the test water is measured for each flock by the flock tracking device 65.
In the moving speed measurement step, the time for applying the voltage to the test water can be freely set, for example, 3 to 5 minutes.

  In the present embodiment, in the moving speed measurement step, a light source that irradiates the cell 61 with laser light, a camera installed on the outer surface of the cell 61 where the anode 62a and the cathode 62b are not installed, and a camera are used. A flock tracking device 65 having a display device 65a for displaying a signal input by photographing is used. As the cell 61, a cell made of a transparent material is used.

Then, for example, while irradiating laser light into the cell 61, the positions of a plurality of flocks in the test water when a voltage is applied to the test water are photographed continuously using a camera for a predetermined time. The information on the position of the plurality of flocks continuously obtained for the predetermined time thus obtained is the information on the movement distance within the predetermined time in each of the plurality of flocks as the information on the movement speed for each flock of the plurality of flocks. Is included.
In the moving speed measurement step, the positions of the plurality of flocks in the test water when a voltage is applied to the test water may be photographed a plurality of times at predetermined time intervals using a camera. Also in this case, by performing the moving speed measurement step, information on the moving distance within a predetermined time in each of the plurality of flocks can be obtained as information on the moving speed for each flock of the plurality of flocks.

A plurality of continuous flock position signals obtained by photographing with the camera for a predetermined time are input to the display device 65a for display and also input to the variance value calculation device 81.
FIG. 7 is a photograph in which the positions of a plurality of continuous flocks taken by the camera for a predetermined time are displayed on the display device 65a. In the image displayed on the display device 65a, the right side is the cathode side and the left side is the anode side.

  In the variance value calculation step, the variance value calculation device 81 generates a vector of the moving speed of each flock from the signals of the positions of a plurality of flocks included in the test water measured by the flock tracking device 65. Then, the variance value calculation device 81 gives a minus value when the vector of the moving speed of each floc includes a component in the anode 62a direction, and gives a plus value when it includes a component in the cathode 62b direction. Next, the variance value calculation device 81 aggregates the negative movement speed and the positive movement speed for each predetermined size, and calculates the variance value in the movement speed distribution of the plurality of flocks.

In the variance value calculation step, the number of floc moving speeds used for calculating the variance value is not particularly limited, but in order to improve the evaluation accuracy of the floc aggregation state, it is preferably as large as possible and 500 or more. preferable.
In the variance value calculating step, the moving speeds of all the flocks that can be recognized on the image taken with the camera may be used for calculating the variance value, or only the moving speeds of some of the flocks may be used. When only the moving speed of some of the flocks is used to calculate the variance value, for example, in an image shot multiple times at a predetermined time using a camera, the number of times recognized can be greater than or equal to the predetermined number Only the movement speed of a certain flock may be used.

In the variance calculation step, all of the negative movement speeds (all of the vector components of the movement speed) are used as the negative movement speeds used for the aggregation, and the positive movement speed is used as the positive movement speed used for the aggregation. All (all of the components of the moving speed vector) can be used.
Further, in the variance value calculating step, as the negative movement speed used for the aggregation, only the movement speed of the component in the direction of the anode 62a included in the vector of the movement speed of each flock is used as the negative movement speed, and the aggregation is used for the aggregation. As the positive movement speed to be used, only the movement speed of the component in the cathode 62b direction included in the movement speed vector of each floc may be used among the positive movement speeds.

In the present embodiment, in the variance value calculation step, it is preferable that the variance value calculation device 81 calculates the average value of the minus and minus movement speeds of the movement speeds of the plurality of flocks.
In the variance value calculating step, the calculated variance value or the variance value and the average value are input to the evaluation device 90.

Next, the evaluation device 90 performs an evaluation process for evaluating the quality of the floc aggregation state based on the dispersion value and the target value calculated by the dispersion value calculation device 81.
In the evaluation step, if the dispersion value is equal to or greater than the target value, it is determined that the floc aggregation state is good, and if the dispersion value is less than the target value, it is determined that the floc aggregation state is poor.

In the evaluation step, when the evaluation of the floc aggregation state is poor, based on the average value of the negative movement speed and the positive movement speed of the movement speeds of the plurality of flocks calculated in the dispersion value calculation step, It is preferable to evaluate the floc aggregation state.
Specifically, in the evaluation step, when the floc aggregation state is evaluated as poor and the average value is a negative value, it is determined that the injection rate of the flocculant in the test water is insufficient. preferable.
In the evaluation step, when the floc aggregation state is evaluated as poor and the average value is a positive value, it is preferable to determine that the injection rate of the flocculant in the test water is excessive.

In the present embodiment, in the evaluation process, it is preferable that the evaluation device 90 generates a histogram of the movement speed distribution of the flock and displays the histogram on the display device.
Furthermore, in the evaluation process, the result of evaluating the floc aggregation state by the evaluation device 90, the result of determining whether the floc aggregation state is good or bad, and whether the injection rate of the flocculant is insufficient. Any one or more results of the result of determining whether it is excessive or the real-time image or moving image of the display device included in the flock tracking device 65 may be displayed on the display device.

  In the present embodiment, in the evaluation process, when the evaluation unit 90 evaluates that the floc aggregation state is defective, the parameter adjustment device 91 receives a signal indicating that the evaluation of the floc aggregation state is poor. . Further, in the evaluation process, when the evaluation device 90 determines that the injection rate of the flocculant in the test water is insufficient or when it is determined that the injection rate of the flocculant in the test water is excessive, the parameter adjustment device 91. In addition, a signal indicating that the injection rate of the flocculant is insufficient or a signal indicating that the injection rate of the flocculant in the test water is excessive is input.

  Next, the parameter adjustment process will be described. The parameter adjustment step is a step performed when the evaluation of the floc aggregation state is poor. Therefore, the parameter adjustment step is not performed when it is determined in the evaluation step that the floc aggregation state is good.

In the parameter adjusting step, when the floc aggregation state is evaluated as poor, the parameter adjusting device 91 causes the flocculant injection rate in the mixing basin 22, the stirring intensity in the mixing basin 22, and the mixing in the mixing basin 22. Any one or more parameters of the residence time of water and the pH in the mixing basin 22 are adjusted so that the dispersion value becomes high.
The parameter adjustment step preferably includes at least one step selected from a step of increasing the stirring strength in the mixing basin 22 and a step of increasing the residence time of the mixed water in the supply to the mixing basin 22.

When adjusting the injection rate of the flocculant in the mixing basin 22 in the parameter adjustment step, the amount of the flocculant injected from the flocculant injection device 70 into the mixing basin 22 is controlled to control the flocculant in the mixing basin 22. Adjust the injection rate.
In the parameter adjustment step, a signal indicating that the injection rate of the flocculant in the test water is insufficient is input from the evaluation device 90, thereby controlling the injection amount of the flocculant injected from the flocculant injection device 70 into the mixing basin 22. Thus, it is preferable to increase the injection rate of the flocculant in the mixing water in the mixing pond 22 from which the test water is collected.
Further, in the parameter adjustment step, when the signal indicating that the injection rate of the flocculant in the test water is excessive is input from the evaluation device 90, the injection amount of the flocculant injected from the flocculant injection device 70 into the mixing basin 22 is determined. It is preferable to control to lower the injection rate of the flocculant in the mixing water in the mixing pond 22 from which the test water is collected.

In the parameter adjustment step, when adjusting the stirring strength in the mixing pond 22 from which the test water is collected, the rapid mixing pond 20, the first stirring pond 31, the second stirring pond 32, and the third stirring pond 33 are provided. This is performed by controlling the stirring intensity of any one or more of the stirring devices 21, 34, 35 and 36.
In the water treatment apparatus 1, even after adjusting the mixing strength of the mixed water in the mixing pond 22, the mixing strength of the mixed water in each pond forming the mixing pond 22 is stepwise from the upstream side toward the downstream side. It is preferable to be smaller.

  Further, in the parameter adjustment step, when adjusting the residence time of the mixed water in the mixing pond 22 where the test water is collected, it is supplied by the flow rate adjustment valve 72 based on the flow rate of the raw water input from the flow meter 63. Adjust the supply of raw water.

  In the parameter adjustment step, when adjusting the pH in the mixing pond 22 from which the test water has been collected, the pH adjusting agent injected by the pH adjusting agent injecting device 71 based on the pH of the raw water input from the pH measuring device 74. The type and injection amount are controlled, and the pH of the mixing water in the mixing pond 22 is adjusted.

  In the present embodiment, the flock control step may be performed as appropriate according to changes in water quality due to weather or the like, or may be performed every predetermined time. In the case where the flock control step is performed every predetermined time, it is preferable to perform the flock control step every 10 to 20 minutes, for example. By performing the floc control step every time as described above, the floc aggregation conditions can be controlled with high accuracy so that the floc aggregation state in the mixed water 22 becomes good in response to fluctuations in the quality of the raw water.

Next, the injection rate determining step will be described. The injection rate determination step is a step performed as necessary before the flocculant injection step. The injection rate determination step is performed to determine the control range of the injection rate of the flocculant injected into the mixed water in the mixing pond 22 by the flocculant injection device 70.
The injection rate determination step is performed using an injection rate determination device 73 included in the floc aggregation condition control device 60. The injection rate determination device 73 determines a control range of the injection rate of the flocculant based on the dispersion values of the plurality of target value setting admixture water calculated by the dispersion value calculation device 81.

  FIG. 8 is an explanatory diagram for explaining the injection rate setting step. As shown in FIG. 8, in the injection rate setting step, the flocculant is injected into the raw water collected in a container such as a beaker 17 and stirred, and a plurality of target value setting admixtures 11 and 12 having different injection rates of the flocculant are obtained. , 13, 14, and 15 are generated. Then, similarly to the movement speed measurement step and the dispersion value calculation step in the floc aggregation condition control method described above, a plurality of movement speed measurement devices 80 and dispersion value calculation devices 81 of the floc aggregation condition control device 60 are used. For each of the target value setting admixtures 11, 12, 13, 14, and 15, a dispersion value in the movement speed distribution of a plurality of flocs is calculated. The dispersion value of each of the plurality of water for setting target values calculated by the dispersion value calculation device 81 is input to the injection rate determination device 73.

Next, the injection rate determination device 73 determines the control range of the injection rate of the flocculant based on the dispersion value calculated by the dispersion value calculation device 81.
The injection rate determination device 73 controls the injection rate of the flocculant based on the injection rate of the flocculant of the target value setting admixture of which the dispersion value is equal to or greater than the target value among the plurality of target value setting water blends Determine the range. The control range of the flocculant injection rate determined by the injection rate determination device 73 is input to the parameter adjustment device 91.

When the injection rate setting step is performed before the flocculant injection step, the parameters are set so that the injection rate of the flocculant in the mixed water in the mixing basin 22 is within the control range in the flocculant injection step. The adjusting device 91 controls the flocculant injection device 70 to inject the flocculant into the mixing basin 22.
In this embodiment, by performing the injection rate determination step before the flocculant injection step, the injection amount of the flocculant in the mixing water in the mixing pond 22 at the start of the flocculant injection step is appropriate for the raw water. It will be a thing.

  In the floc aggregation condition control method of the present embodiment, the anode 62a and the cathode 62b are arranged in the test water containing the floc collected from the mixing basin 22, and a voltage is applied to the test water to move the movement speed of the plurality of flocs in the test water. The moving speed measuring step for measuring each floc and the moving speed vector of each floc gives a minus if it contains a component in the anode 62a direction, and gives a plus if it contains a component in the cathode 62b direction, minus The movement speed and the positive movement speed are totaled for each predetermined size, and a dispersion value calculation step of calculating a dispersion value in the movement speed distribution of the plurality of flocks is performed. Then, based on the dispersion value and the target value, an evaluation step for evaluating the quality of the floc aggregation state, and when the floc aggregation state is evaluated as poor, the injection rate of the flocculant in the mixing pond 22 and the mixing pond A parameter adjustment step of adjusting any one or more of the stirring intensity in 22, the residence time of the mixed water in the mixing basin 22, and the pH in the mixing basin 22 so as to increase the dispersion value is performed. For this reason, the effect shown below is acquired.

  In the floc aggregation condition control method of the present embodiment, the floc aggregation state in the test water is evaluated using the dispersion value in the evaluation step. Regardless of the quality of the test water, the dispersion value σ of the floc moving speed distribution tends to be large when the floc aggregation state is good and small when the floc aggregation state is poor. Therefore, in the present embodiment, whether or not the flocs are aggregated in the test water can be determined with high accuracy regardless of the quality of the test water in the evaluation step. In the present embodiment, the one or more parameters that can be adjusted for the dispersion value are adjusted based on the evaluation in the evaluation process so that the dispersion value becomes high. Aggregation conditions can be controlled with high accuracy so that the flocs are in an excellent aggregated state.

  Further, in the floc aggregation condition control method of the present embodiment, the floc aggregation condition in the mixing basin 22 is determined based on the quality of the floc aggregation state evaluated using the test water containing floc collected from the mixing basin 22. Can be controlled. Therefore, when the optimum floc aggregation condition in the mixing basin 22 changes due to fluctuations in the quality of raw water, the floc aggregation condition in the mixing basin 22 can be adjusted to a condition suitable for the changed water quality in a short time. .

  In contrast, when the floc aggregation state is evaluated using the supernatant water obtained by precipitating the floc in the sedimentation basin, the floc aggregation state cannot be evaluated unless the floc is removed. That is, in order to evaluate the aggregation state of flocs, it takes time to settle flocs in a sedimentation basin. Therefore, for example, in order to control the floc aggregation condition in the mixing pond of the water purification plant, when the floc aggregation state is evaluated using the filtration time index of the sedimentation basin outlet water, the evaluation result of the floc aggregation state is mixed. It took a lot of time to reflect the floc aggregation conditions in the pond.

  Further, in the floc aggregation condition control method of the present embodiment, floc aggregation conditions can be controlled with high accuracy, so that it is possible to prevent the flocculant from being excessively injected. Therefore, injecting the flocculant excessively does not increase the amount of sludge, prevent reuse of sludge, or increase the frequency of cleaning the filtration pond 50.

In the evaluation process of the floc aggregation condition control method of the present embodiment, when a histogram of floc moving speed distribution is generated and displayed on the display device, the operator is in a good or bad floc aggregation state. When determining whether or not there is, the shape of the histogram displayed on the display device can be used.
In the water treatment method of the present embodiment, the floc aggregation condition control method using the floc aggregation condition control device 60 described above is used to control the floc aggregation condition so that the floc is in a good aggregation state. High quality treated water can be obtained.

  The floc aggregation condition control device 60 according to the present embodiment includes a cell 61 that contains test water containing floc collected from the mixing basin 22, and an anode 62 a and a cathode 62 b that are opposed to each other in the cell 61. A voltage supply device for applying a voltage to the test water, and a position of the floc in the test water when the voltage is applied to the test water at least at a first time and a second time after a predetermined time has elapsed from the first time. A moving speed measuring device 80 having a flock tracking device 65 for measuring each flock is provided. Further, by inputting signals of the positions of a plurality of flocs in the test water measured by the floc tracking device 65, a vector of the moving speed of each floc is generated. If the vector includes a component in the direction of the anode 62a, the vector is negative. Is added when the component in the direction of the cathode 62b is included, the negative moving speed and the positive moving speed are totaled for each predetermined size, and the dispersion value in the moving speed distribution of the plurality of flocs A variance value calculation device 81 is calculated. Furthermore, based on the dispersion value and the target value, an evaluation device 90 that evaluates the quality of the floc aggregation state, and when the floc aggregation state is evaluated to be poor, the injection rate of the flocculant in the mixing pond 22 A parameter adjusting device that adjusts any one or more parameters of the stirring intensity in the pond 22, the residence time of the mixed water in the mixing basin 22, and the pH in the mixing basin 22 so as to increase the dispersion value; For this reason, when the floc aggregation condition is controlled using the floc aggregation condition control method of the present embodiment, the floc aggregation condition in the mixing basin 22 is good regardless of the water quality of the mixing basin 22 including the floc. Can be controlled with high accuracy so as to achieve a stable aggregation state. Moreover, in the floc aggregation condition control apparatus of this embodiment, the floc aggregation condition in the mixing basin 22 is determined based on the quality of the floc aggregation state evaluated using the test water containing floc collected from the mixing basin 22. Therefore, when the optimum floc aggregation condition in the mixing basin 22 is changed due to fluctuations in the quality of raw water, the floc aggregation condition in the mixing basin 22 is changed to a condition suitable for the changed water quality in a short time. Can be adjusted.

  Since the water treatment apparatus of the present embodiment has the floc aggregation condition control apparatus 60 of the present embodiment, the floc aggregation conditions are controlled so that the floc is in an excellent aggregation state in response to changes in water quality. High quality treated water can be obtained.

  In the embodiment described above, the mixed water collected from the mixing pond of the water purification plant has been described as an example as the test water including the floc for evaluating the aggregation state. However, the floc aggregation condition control method and floc of the embodiment are described. The test water used using the coagulation condition control device is not limited to the mixed water collected from the mixing pond of the water purification plant. Further, the mixing basin 22 for collecting the test water may be any of the rapid mixing basin 20, the first stirring basin 31, the second stirring basin 32, and the third stirring basin 33 shown in FIG.

  In the floc control process of the present embodiment, the test water including the floc for evaluating the aggregation state is mixed water collected from the rapid mixing basin 20 of the mixing basin 22 in order to cope with fluctuations in the raw water in a shorter time. Is preferred. However, the floc aggregation state varies depending on the strength (G value) of stirring in the mixing basin 22 and the time during which stirring is applied. In consideration of this change, in order to control the floc aggregation conditions with high accuracy, it is preferable to collect the test water used in the floc control process from the floc formation pond 30, and it is installed downstream of the flock formation pond 30. It is preferable to collect from the third stirring basin 33.

  Further, the particle size of the floc grows gradually in the mixing basin 22 and becomes enormous. The floc moving speed measured in the above moving speed measuring step is easier to measure as the floc has a larger particle size. For this reason, a difference may occur in the accuracy of the evaluation result of the floc aggregation state depending on the floc particle size. In addition, the particle size of the floc varies depending on the quality of the raw water. Therefore, depending on the quality of the raw water, the location where the test water is collected from which a highly accurate evaluation result of the floc aggregation state may be different.

  Moreover, since the mixing water in the rapid mixing basin 20 is insufficiently stirred, the state of floc aggregation in the mixing basin 22 may change. Therefore, when the mixed water collected from the rapid mixing basin 20 is used as test water, the difference between the evaluation results of the floc aggregation state between the mixed water in the rapid mixing basin 20 and the precipitation basin outlet water should be sufficiently small. It is preferable to confirm.

  FIG. 9 is a graph showing the relationship between the sampling location of the test water in the mixing basin 22 and the rate of increase / decrease of the variance value σ of the floc moving speed distribution. The results shown in FIG. 9 are obtained by measuring the rate of increase / decrease in the dispersion value of the floc moving speed distribution under the same conditions for three types of raw water having different water qualities.

In the water quality of (a) shown in FIG. 9, the dispersion value of the rapid mixing basin 20 exceeds the target value, and in any of the first stirring basin 31, the second stirring basin 32, and the third stirring basin 33, the dispersion value Exceeds the target value.
In the water quality of (a), it was found that the change in floc aggregation state in the mixing basin 22 was small by collecting test water from a plurality of locations in the mixing basin 22. As a result, it was found that in the water quality of (a), it is preferable to perform the flock control process using the test water collected from the rapid mixing basin 20 in order to cope with the fluctuation of the raw water in a short time.

In the water quality of (b) shown in FIG. 9, the dispersion value of the rapid mixing basin 20 and the first stirring basin 31 is less than the target value. However, in the water quality of (b) shown in FIG. 9, the floc aggregation state is improved in the mixing basin 22, and the dispersion values of the second agitation basin 32 and the third agitation basin 33 exceed the target values. In the water quality of (b), when the floc control process was performed using the test water collected from the rapid mixing basin 20, the parameters were changed even though the water quality of the sedimentation basin outlet water was good, and the floc aggregation conditions There is a risk of adverse effects.
In the water quality of (b), it was found that the improvement of the floc aggregation state in the mixing basin 22 was significant by collecting test water from a plurality of locations in the mixing basin 22. Further, in the water quality of (b), by using the test water collected from the second stirring basin 32 or the third stirring basin 33, unnecessary parameter change is prevented, and the flocs coagulation condition is more appropriately set. It was found that can be controlled.

In the water quality of (c) shown in FIG. 9, the dispersion value of the rapid mixing basin 20 is less than the target value, and the floc aggregation state in the mixing basin 22 is gradually improved. The dispersion value gradually increases in the order of the second stirring basin 32 and the third stirring basin 33. However, in the water quality of (c), the dispersion value of the third stirring basin 33 is also less than the target value.
In the water quality of (c), by collecting test water from a plurality of locations in the mixing basin 22, the floc aggregation state has been improved in the mixing basin 22. I found it necessary. Therefore, in the water quality of (c), the floc aggregation condition can be improved by controlling the floc aggregation condition using the floc aggregation condition control method of the embodiment.

  As shown in FIG. 9, for the test water collected from a plurality of locations in the mixing basin 22, the dispersion value σ of the movement speed distribution of each floc is calculated, thereby changing the floc aggregation state in the mixing basin 22. Can be evaluated. And based on the change of the floc aggregation state in the mixing basin 22, the floc aggregation condition can be appropriately controlled with higher accuracy by collecting from an appropriate test water collection point.

  In the above embodiment, the case where the floc coagulation condition control device is provided in the water treatment device installed in the water purification plant has been described as an example, but the floc coagulation condition control device and the floc coagulation condition control method Application is not limited to water purification plants, and they may be installed in sewage treatment plants, industrial wastewater treatment facilities, and the like. Moreover, although the case where a central processing unit of a computer such as a central monitoring control system in a water purification plant is used has been described as an example, a portable device such as a tablet terminal may be used.

  In the above embodiment, the dispersion value of the movement speed distribution of the flock is used to determine whether the floc aggregation state is good or bad. Instead of the dispersion value, the kurtosis representing the sharpness of the frequency distribution is used. May be used.

In the above embodiment, the case where the rapid mixing basin 20 and the floc-forming pond 30 are connected by piping has been described as an example. However, the rapid mixing basin 20 and the flock-forming pond 30 are integrated with each other. It may be an area partitioned by a partition in 22.
In the above embodiment, the case where the flock formation pond 30 has three agitation ponds has been described as an example. However, the flock formation pond has two or four or more agitation ponds having different agitation strengths of mixed water. It may be. Moreover, as a floc formation pond, you may have one cohesion growth pond which agitates the inside of a flock formation pond using the flow of water without using a stirrer, and grows a floc.

In the above embodiment, the case where the pH measuring device 74 is installed in the pipe connecting the landing well 10 and the rapid mixing basin 20 has been described as an example, but the pH measuring device may be installed in the mixing basin 22. Good.
Moreover, the water treatment apparatus of the said embodiment may have a measuring apparatus for measuring water quality, such as turbidity, alkalinity, and organic substance density | concentration of raw | natural water or the mixing pond 22.

  According to at least one embodiment described above, an anode and a cathode are arranged in test water containing flocs collected from a mixing pond, and a voltage is applied to the test water so that the moving speed of the plurality of flocs is set for each floc. When the moving speed measuring step to measure and the vector of the moving speed of the floc includes a component in the anode direction, a first code is given, and when a vector in the cathode direction is included, a second code is given, A dispersion value calculating step of calculating a dispersion value in the movement speed distribution of the plurality of flocks by counting the movement speed of the first code and the movement speed of the second code for each predetermined size; Based on a target value, an evaluation process for evaluating the quality of the floc aggregation state, and when the floc aggregation state is evaluated as poor, the injection rate of the flocculant in the mixing basin, A parameter adjustment step of adjusting any one or more of the stirring intensity in the mixing pond, the residence time of the mixed water in the mixing pond, and the pH in the mixing pond so that the dispersion value becomes high, When the water quality changes, it is possible to adjust the floc aggregation conditions suitable for the changed water quality in a short time, and the floc aggregation conditions can be controlled regardless of the water quality of the mixing pond containing the floc.

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

  DESCRIPTION OF SYMBOLS 1 ... Water treatment apparatus, 10 ... Receiving well, 20 ... Rapid mixing pond, 21, 34, 35, 36 ... Stirring apparatus, 22 ... Mixing pond, 30 ... Flock formation pond, 31 ... First stirring pond, 32 ... Second Stirring basin 33 ... third stirring basin 40 ... precipitation basin 50 ... filtration basin 60 ... floc coagulation condition control device 61 ... cell 62 ... voltage supply device 62a ... anode 62b ... cathode 63 ... flow rate 65 ... Flock tracking device, 70 ... Flocculant injection device, 71 ... pH adjuster injection device, 72 ... Flow rate adjustment valve, 74 ... pH measurement device, 80 ... Movement speed measurement device, 81 ... Dispersion value calculation device, 90 ... Evaluation device, 91 ... Parameter adjustment device

Claims (10)

A moving speed measuring step of arranging an anode and a cathode in test water containing flocks collected from a mixing pond, applying a voltage to the test water, and measuring a plurality of flock moving speeds for each flock;
When the vector of the movement speed of the flock includes a component in the anode direction, a first code is assigned, and when the vector of the floc movement includes a component in the cathode direction, a second code is assigned, and the movement speed of the first code and the A dispersion value calculating step of calculating the dispersion value in the movement speed distribution of the plurality of flocks by totaling the movement speeds of the second code for each predetermined size;
Based on the dispersion value and the target value, an evaluation step for evaluating the quality of the floc aggregation state;
When the floc aggregation state is evaluated to be poor, any one of the injection rate of the flocculant in the mixing pond, the stirring strength in the mixing pond, the residence time of the mixed water in the mixing pond, and the pH in the mixing pond And a parameter adjusting step of adjusting the one or more parameters so as to increase the dispersion value.   2. The floc of claim 1, wherein the parameter adjustment step includes one or more steps selected from a step of increasing the stirring strength in the mixing basin and a step of increasing the residence time of the mixed water in the mixing basin. Aggregation condition control method. In the variance value calculating step, an average value of the moving speed of the first code and the moving speed of the second code of the moving speeds of the plurality of flocks is calculated,
In the evaluation step, when the floc aggregation state is evaluated as poor and the average value is the first sign, it is determined that the injection rate of the flocculant in the mixed water is insufficient,
The floc aggregation condition control method according to claim 1, wherein the parameter adjustment step includes a step of increasing an injection rate of the flocculant in the mixing pond. In the variance value calculating step, an average value of the moving speed of the first code and the moving speed of the second code of the moving speeds of the plurality of flocks is calculated,
In the evaluation step, when the floc aggregation state is evaluated as poor and the average value is a second sign, it is determined that the injection rate of the flocculant in the mixed water is excessive,
The floc aggregation condition control method according to claim 1, wherein the parameter adjustment step includes a step of reducing an injection rate of the flocculant in the mixing pond. A flocculant injecting step for injecting flocculant into raw water in the mixing pond to generate mixed water containing floc;
Separating the flocs by settling and obtaining supernatant water from the mixed water;
A floc control step for controlling the floc aggregation conditions,
The water treatment method according to claim 1, wherein the floc control step is a floc aggregation condition control method according to claim 1. A cell containing test water containing floc collected from the mixing pond;
A voltage supply device for applying a voltage to the test water in the cell by means of an anode and a cathode arranged opposite to each other in the cell;
A flock tracking device for measuring the position of the floc in the test water when a voltage is applied to the test water at least every first flock and at a second time after a predetermined time has elapsed from the first time; A moving speed measuring device;
By inputting signals of the positions of a plurality of flocs in the test water measured by the floc tracking device, a vector of the moving speed of each floc is generated, and the vector includes a component in the anode direction. 1 code is provided, a second code is provided when the component in the cathode direction is included, the moving speed of the first code and the moving speed of the second code are totaled for each predetermined size, A dispersion value calculating device for calculating a dispersion value in the movement speed distribution of a plurality of flocks;
An evaluation device that evaluates the quality of the floc aggregation state based on the dispersion value and the target value;
When the floc aggregation state is evaluated to be poor, any one of the injection rate of the flocculant in the mixing pond, the stirring strength in the mixing pond, the residence time of the mixed water in the mixing pond, and the pH in the mixing pond A floc coagulation condition control device comprising a parameter adjustment device for adjusting the one or more parameters so that the dispersion value is increased.   The parameter adjustment device performs any one or more controls selected from controlling to increase the stirring intensity in the mixing basin and controlling to increase the residence time of the mixed water in the mixing basin. Item 7. The floc aggregation condition control device according to Item 6. The variance value calculating device calculates an average value of the moving speed of the first code and the moving speed of the second code of the moving speeds of the plurality of flocks;
The evaluation device determines that the floc aggregation state is poor, and when the average value is the first sign, determines that the injection rate of the flocculant in the mixed water is insufficient,
The floc aggregation condition control device according to claim 6, wherein the parameter adjusting device controls the injection rate of the flocculant in the mixing pond to be high. The variance value calculating device calculates an average value of the moving speed of the first code and the moving speed of the second code of the moving speeds of the plurality of flocks;
When the evaluation device evaluates that the floc aggregation state is poor and the average value is a second sign, it determines that the injection rate of the flocculant in the mixed water is excessive,
The floc aggregation condition control apparatus according to claim 6, wherein the parameter adjustment device controls the injection rate of the flocculant in the mixing pond to be low. A mixing pond containing mixing water containing flock and equipped with a stirring device for stirring the mixing water;
Containing a mixing water supplied from the mixing pond, and a sedimentation basin for precipitating the floc;
A floc control device for controlling the floc aggregation conditions,
A water treatment apparatus, wherein the floc control apparatus is the floc aggregation condition control apparatus according to any one of claims 6 to 9.