JP6437394B2 - Water treatment method, water treatment facility, injected flocculant amount evaluation system and residual flocculant amount estimation device - Google Patents

Description

  Embodiments described herein relate generally to a water treatment method, a water treatment facility, an injected flocculant amount evaluation system, and a residual flocculant amount estimation device.

  Suspensions contained in treated water (raw water) such as river water, rain water, sewage, and industrial wastewater are generally negatively charged. As a treatment method for removing the suspension from the raw water, a method of injecting a flocculant that is positively charged in water into the raw water is known. In this method, the flocs, which are aggregates of the suspension, are generated by neutralizing the charge of the suspension in the raw water by the flocculant, and this is precipitated and removed. As the flocculant that is positively charged in water, polyaluminum chloride (PAC) and aluminum sulfate (sulfur sulfate) are widely used.

  In the water treatment method using this flocculant, the floc state of flocs changes depending on the amount of flocculant injected into the raw water. However, the amount of the flocculant injected to improve the floc aggregation state varies with 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.

  As a method for controlling the injection amount of the flocculant into the raw water, there is known a method for evaluating the floc aggregation state of the treated water and calculating the optimum injection amount using the result. 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. Also known is a method of classifying flocs from treated water and measuring the aluminum concentration of the treated water after the classification by absorptiometry using eriochrome cyanine red as a color reagent.

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. In the method of measuring the aluminum concentration by absorptiometry, it takes time until the measurement result of the aluminum concentration is obtained after the flocculant is injected, and the quality of the raw water sometimes fluctuates.
For this reason, even if the injection amount of the flocculant into the raw water is controlled using these indexes, the effect of controlling the injection amount may not be sufficiently obtained.

Japanese Patent No. 3522650 JP2013-198865A Japanese Patent No. 5131005 JP 2012-101171 A

  The problem to be solved by the present invention is a water treatment method, a water treatment facility, and an injection flocculant capable of controlling the amount of flocculant injected into water to be treated to an optimum amount in a short time and with high accuracy. It is to provide a quantity evaluation system and a residual flocculant quantity estimation device.

  In the water treatment method of the embodiment, treated water containing flocs is formed by injecting a flocculant charged positively in water into water to be treated containing a negatively charged suspension and aggregating the suspension. The amount of residual flocculant remaining in the treated water is compared with the amount of residual flocculant and the target residual amount. When the amount of the flocculant injected into the water to be treated is excessive, and when the amount of the residual flocculant is smaller than the target residual amount, the flocculant injected into the water to be treated And a step of judging that the amount of the agent is too small. The step of estimating the amount of the residual flocculant is a step of collecting a part of the treated water, separating and removing floc from the collected treated water, and preparing test water containing fine particles; Disposing an anode and a cathode, applying a voltage to the test water, and measuring a moving speed of fine particles moving in the direction of the cathode among the fine particles contained in the test water; and And a step of estimating a residual flocculant amount remaining in the treated water based on the moving speed of the fine particles moving in the direction.

The block diagram which shows an example of the water treatment facility of 1st Embodiment. Explanatory drawing for demonstrating the relationship between the microparticles | fine-particles in test water and the amount of residual flocculants when a voltage is applied to test water. The flowchart explaining the flow of the water treatment method implemented by the water treatment facility of 1st Embodiment. The block diagram which shows an example of the water treatment facility of 2nd Embodiment. Explanatory drawing for demonstrating the relationship between the dispersion value of the charge of the floc in process water, and the amount of residual flocculants. The flowchart explaining the flow of the setting method of the target residual amount of the coagulant | flocculant implemented by the water treatment facility of 2nd Embodiment.

  Hereinafter, a water treatment method, a water treatment facility, an injected flocculant amount evaluation system, and a residual flocculant amount estimation device according to embodiments will be described with reference to the drawings.

  In the present embodiment, a water treatment facility that can be used as a water purification plant will be described as an example of the water treatment facility. The suspension in the raw water (treated water) of the water purification plant is usually negatively charged. When a flocculant that is positively charged in water is injected into the raw water, the suspension in the raw water aggregates to form flocs. The negatively charged suspension and the positively charged flocculant adhere to each other, and the negative charge of the suspension is canceled, so that the surface charge of the suspension approaches 0 and the suspension is suspended. It is thought that the repulsion between things weakens and the formation of flocks progresses.

  If the injection amount of the flocculant is too small, the negative charge of the suspension is not sufficiently canceled out, the surface charge of the suspension remains negative, and floc formation does not proceed sufficiently. Therefore, it is preferable that the injection amount of the flocculant is slightly excessive so that the negative charge of the suspension is sufficiently canceled. On the other hand, if the injection amount of the flocculant becomes excessive, the surface charge of the suspension 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 the suspensions increases and the formation of flocs does not proceed.

  The present inventors pay attention to such a phenomenon, and remain in the treated water from the amount of fine particles that are positively charged among the fine particles that do not form flocs that are present in the treated water. It was found that the amount of the flocculant injected into the raw water can be determined by estimating the amount of the flocculant. The amount of positively charged microparticles is positively charged microparticles in test water using electrophoresis using test water containing microparticles prepared by separating and removing floc from treated water. It can be obtained by measuring the moving speed of.

  Furthermore, the present inventors measured the dispersion value of the flock charge contained in the treated water and used the treated water when it was determined that the dispersion value of the flock charge was equal to or greater than the target value. It has been found that by setting the estimated amount of residual flocculant as the target residual amount of the residual flocculant, the floc state of flocs contained in the treated water can be favorably maintained.

  Next, embodiments of a water treatment method, a water treatment facility, an injected flocculant amount evaluation system, and a residual flocculant amount estimation device configured based on the above knowledge will be described.

(First embodiment)
FIG. 1 is a block diagram illustrating an example of a water treatment facility according to the first embodiment. The water treatment facility 1 a includes a landing well 10, a mixing basin 22, a sedimentation basin 40, a filtration basin 50, a parameter adjustment device 60, and an injected flocculant amount evaluation system 70.

First, the injected flocculant amount evaluation system 70 of this embodiment will be described.
The injected flocculant amount evaluation system 70 evaluates whether or not the amount of the flocculant injected into the raw water is an optimal amount. The injected flocculant amount evaluation system 70 includes a residual flocculant amount estimation device 80 and an injected flocculant amount determination device 90.

  The residual flocculant amount estimation device 80 is a device that estimates the amount of flocculant remaining in the treated water (residual flocculant amount). The residual flocculant amount estimation device 80 remains in the treated water, a preparation unit 81 that prepares test water containing fine particles, a measurement unit 82 that measures the movement speed of positively charged fine particles in the test water, and the treated water. And an estimation unit 83 for estimating the amount of the residual flocculant.

  The preparation unit 81 collects a part of the treated water, separates and removes flocs from the collected treated water, and prepares test water containing fine particles that have not formed flocs. As a method for separating and removing floc from the treated water, any of filtration, centrifugation and sedimentation can be used. Although the average particle diameter of the fine particles contained in the test water varies depending on the separation method, it is generally in the range of 1 to 10 μm.

  The measuring unit 82 measures the moving speed of positively charged fine particles in the test water by using electrophoresis. Specifically, the measurement unit 82 arranges an anode and a cathode in the test water, applies a voltage to the test water, and moves in the cathode direction among the fine particles contained in the test water. It measures the moving speed of. The voltage applied to the test water is generally in the range of 10-20V.

The measuring unit 82 includes, for example, a cell in which an anode and a cathode are opposed to each other, a voltage supply device that applies a voltage to the anode and the cathode in the cell, and a test water when a voltage is applied to the test water. And a speed measuring device for measuring the moving speed of the fine particles.
The cell contains test water and applies a voltage to the test water. The cell is preferably formed of a transparent material such as glass or acrylic.

  As a speed measuring device, when a voltage is applied to test water, the position of the fine particles moving in the cathode direction is measured for each fine particle at least at a first time and a second time after a predetermined time has elapsed from the first time. Things can be used. In this case, the measurement of the position of the fine particles may be performed a plurality of times every predetermined time (for example, every 1 second) or continuously for a predetermined time.

  The speed measuring device includes a light source that emits light toward the inside of the cell, a camera that captures flocks contained in the test water, and a display device that displays signals input by capturing using the camera. It is preferable to use one. Any light source may be used as long as it can irradiate the test water of the cell 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 where the anode and cathode of the cell are not installed. In this case, since the test water containing the fine particles in the cell is photographed through the wall surface of the cell, a cell formed of a transparent material is used. As the camera, for example, a camera that receives scattered light on the surface of fine particles obtained by irradiating fine particles in test water with a light source can be used.

The estimation unit 83 estimates the amount of the residual flocculant remaining in the treated water based on the moving speed of the fine particles moving in the cathode direction.
Here, the relationship between the movement of fine particles in the test water and the amount of the residual flocculant when a voltage is applied to the test water will be described with reference to FIG. As shown in FIG. 2, the test water 84 includes suspension particles 85 (black particles) and flocculant particles 86 (white particles). The suspension particle 85 is negatively charged. The flocculant particles 86 are positively charged. In FIG. 2, the arrows indicate the moving directions of the fine particles when a voltage is applied to the test water 84 using the anode 87 and the cathode 88.

  FIG. 2A shows the movement of the fine particles when a voltage is applied to the test water 84 prepared from the treated water in which the amount of the flocculant injected is less than the appropriate amount. In this case, since the coagulant particles 86 are not attached to the suspension particles 85 or the amount is small even if they are attached, the suspension particles 85 are negatively charged. Therefore, when a voltage is applied to the test water 84, the suspension particles 85 and the flocculant particles 86 quickly move toward the anode 87.

  FIG. 2B shows the movement of fine particles when a voltage is applied to test water prepared from treated water in which the amount of flocculant injected is appropriate. In this case, the suspension particles 85 are either slightly positively charged with the negative charge sufficiently canceled out by the flocculant particles 86, or have a neutral charge. Therefore, when a voltage is applied to the test water 84, the suspension particles 85 and the flocculant particles 86 move slowly toward the cathode 88 or move in an irregular direction.

  (C) of FIG. 2 represents the movement of fine particles when a voltage is applied to test water prepared from treated water in which the amount of flocculant injected is excessive than the appropriate amount. In this case, an excess of the flocculant particles 86 is attached to the suspension particles 85, and a single flocculant particle 86 is also present. For this reason, when a voltage is applied to the test water 84, the suspension particles 85 and the flocculant particles 86 quickly move toward the cathode 88.

  Thus, the moving speed of the fine particles (positively charged fine particles) moving in the direction of the cathode 88 among the fine particles contained in the test water 84 when a DC voltage is applied to the test water 84 is the same as that of the treated water. Closely related to the amount of flocculant remaining. To estimate the amount of residual flocculant, prepare test water with a known amount of flocculant, measure the movement speed of fine particles in this test water, and create a standard curve for the flocculant concentration and movement speed of the fine particles. The amount of the flocculant is calculated from the movement speed of the fine particles measured based on the standard curve, the charge amount of the fine particles is calculated from the movement speed, and the calculated charge amount is converted into the amount of the flocculant as the charge amount of the flocculant. Can be used. The estimation of the residual flocculant amount is realized by, for example, a function provided in the central processing unit of the computer.

  The injected flocculant amount determination device 90 compares the residual flocculant amount with the target residual amount. When the residual flocculant amount is larger than the target residual amount, the amount of flocculant injected into the raw water is excessive. If the amount of the residual flocculant is smaller than the target residual amount, it is determined that the amount of the flocculant injected into the raw water is too small. These determinations are realized by, for example, functions provided in the central processing unit of the computer.

  Next, regarding the water treatment device of the first embodiment, the configuration other than the injection flocculant amount evaluation system 70, that is, the landing well 10, the mixing basin 22, the sedimentation basin 40, the filtration basin 50, and the parameter adjustment device. 60 will be described.

The landing well 10 accommodates raw water (treated water) to be treated by the water treatment facility 1a.
The mixing pond 22 contains treated water (mixed water) containing flocs (aggregates) generated by mixing raw water and a flocculant. The mixing basin 22 has a rapid mixing basin 20 connected to the landing well 10 by piping and a flock formation pond 30 connected to the rapid mixing basin 20 by piping. The floc formation pond 30 is for growing flocs in the treated water supplied from the rapid mixing basin 20. The flock formation pond 30 has three agitation ponds 31, 32 and 33. The treated water generated in the rapid mixing basin 20 is supplied to the first stirring basin 31 of the flock formation pond 30. The treated water that has passed through the first stirred basin 31 is supplied to the second stirred basin 32, and the treated water that has passed through the second stirred basin 32 is supplied to the third stirred basin 33.

  A pipe between the landing well 10 and the rapid mixing basin 20 is provided with a flow rate adjusting valve 61, a flow meter 62, and a pH measuring device 63. The rapid mixing basin 20 includes a pH adjusting agent injection device 64 and a flocculant injection device 65.

  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 such that the stirring strength of the treated 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 treated water containing flocs supplied from the mixing basin 22 and precipitates flocs.
The filtration basin 50 is provided downstream of the sedimentation basin 40. The filtration basin 50 is supplied with supernatant water obtained by retaining the treated 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.

  The parameter adjusting device 60 is connected to the flow rate adjusting valve 61, the flow meter 62, the pH measuring device 63, the pH adjusting agent injecting device 64, the coagulant injecting device 65, and the injecting coagulant amount determining device 90. The parameter adjusting device 60 has a function of controlling the injection amount of the flocculant injected from the flocculant injection device 65, a function of controlling the flow rate of raw water, a function of controlling the type and injection amount of the pH adjusting agent, the stirring device 21, It has a function of adjusting the stirring intensity of 34, 35, and 36. The injection amount of the flocculant is controlled by inputting a signal indicating that the flocculant in the treated water is insufficient or a signal indicating that the flocculant is excessively injected in the test water from the injected flocculant amount determination device 90. These controls are realized, for example, by functions provided in the central processing unit of the computer.

Next, a water treatment method using the water treatment facility 1a will be described.
In the water treatment method of the present embodiment, first, raw water to be treated by the water treatment facility 1 a is introduced into the landing well 10. The raw water introduced into the landing well 10 is supplied to the rapid mixing basin 20 of the mixing basin 22 via a pipe. The supply of raw water from the landing well 10 to the rapid mixing basin 20 is continuously performed at a predetermined supply amount by the flow rate adjusting valve 61. The flow rate of raw water supplied to the rapid mixing basin 20 is measured by a flow meter 62 installed in a pipe connecting the landing well 10 and the rapid mixing basin 20 and is input to the parameter adjusting device 60. The pH of the raw water supplied to the rapid mixing basin 20 is measured using a pH measuring device 63 installed in a pipe connecting the landing well 10 and the rapid mixing basin 20 and is input to the parameter adjusting device 60. 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.

  A method for treating the raw water supplied to the rapid mixing basin 20 will be described with reference to FIG. FIG. 3 is a flowchart for explaining the flow of the water treatment method performed by the water treatment facility 1a of the first embodiment.

  In the water treatment method of the present embodiment, first, the amount of flocculant to be charged into raw water is determined (step S10). Next, the determined amount of flocculant is added to the raw water (step S12). As a result, the suspension in the raw water aggregates and flocs are formed, and treated water containing flocs is generated. The amount of residual flocculant remaining in the generated treated water is estimated (step S14). Then, the residual flocculant amount is compared with the target residual amount to determine whether or not the residual flocculant amount is within the target residual amount range (step S16). Here, when the amount of the remaining flocculant is within the range of the target residual amount (step S16: YES), the amount of flocculant is maintained and the amount of flocculant is charged into the raw water. On the other hand, when the residual flocculant amount is not within the target residual amount range (step S16: NO), the flocculant input amount is reset so that the residual flocculant amount is within the target residual amount range. .

  The step of determining the input amount of the flocculant to be supplied to the raw water in step S10 is executed by the parameter adjusting device 60. The parameter adjusting device 60 can determine the input amount of the flocculant based on information such as the amount of raw water, pH, and turbidity. Alternatively, the operator may determine the amount of flocculant to be input and input this to the parameter adjustment device 60.

  The step of adding the flocculant in step S12 to the raw water (hereinafter, this step is referred to as a treated water generation step) is executed by the parameter adjustment device 60. As the flocculant, for example, an aluminum-based inorganic flocculant, an iron-based inorganic flocculant, and a polymer flocculant can be used. Examples of the aluminum-based inorganic flocculant include polyaluminum chloride (PAC) and aluminum sulfate (a sulfate).

  In the treated water generation step, a pH adjuster may be injected into the raw water together with the flocculant. The pH adjuster is supplied by the pH adjuster injection device 64 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. .

  Treated water containing flocs generated in the treated water generating step is supplied to the first agitation pond 31 of the flock formation pond 30. The treated 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. In the mixing basin 22, the treated water containing floc 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.

  The treated water containing flocs produced in the treated water producing step is then supplied to the settling basin 40 and treated by a separation step in which the flocs are settled and separated. In the separation step, the treated water containing floc is retained in the sedimentation basin 40 for a predetermined time or longer, for example, about 3 hours. As a result, flocs in the treated water settle and settle. The floc precipitated in the sedimentation basin 40 is treated as sludge. The treated water from which the floc has been separated by sedimentation is supplied to the filtration basin 50 as supernatant water.

  The supernatant water supplied to the filtration basin 50 is taken out as clean water after passing through the filtration basin 50. The clean water taken out from the filtration basin 50 is sent to the water purification pond, sterilized with chlorine, etc., and taken out 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.

  The step of estimating the amount of residual coagulant remaining in the treated water in step S14 (hereinafter, this step is referred to as residual coagulant amount estimation step) is executed by the residual coagulant amount estimation device 80. In the residual flocculant amount estimation step, the amount of flocculant remaining in the treated water is estimated from the amount of positively charged fine particles present in the treated water that do not form floc. To do. The residual coagulant amount estimation step is a step of separating and removing flocs from the collected treated water to prepare test water containing fine particles (hereinafter referred to as test water preparation step), and the amount of fine particles when voltage is applied to the test water. A step of measuring the moving speed (hereinafter referred to as a moving speed measuring step) and a step of estimating the amount of the residual flocculant remaining in the treated water based on the moving speed of the fine particles (hereinafter referred to as an estimating step).

  The test water preparation step is performed in the preparation unit 81. In the test water preparation step, first, treated water used as test water is collected from the mixing basin 22. Next, the floc is separated and removed from the collected treated water to prepare test water containing fine particles. The place where the treated water is collected may be any of the piping between the rapid mixing basin 20 and the first stirring basin 31, the first stirring basin 31, the second stirring basin 32, and the third stirring basin 33. As a method for separating and removing floc from the treated water, any one of filtration, centrifugal separation and sedimentation separation can be used.

  The moving speed measurement step is performed by the measurement unit 82. In the moving speed measurement step, the moving speed of the positively charged fine particles in the test water is measured using electrophoresis. In the moving speed measurement step, test water is injected into a cell in which an anode and a cathode are arranged to face each other. Next, a voltage is applied to the anode and cathode in the cell. Then, the moving speed of the fine particles moving in the cathode direction among the fine particles contained in the test water is measured by the speed measuring device. 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.

  The estimation process is performed by the estimation unit 83. In the estimation step, the amount of the remaining flocculant remaining in the treated water is estimated based on the moving speed of the fine particles moving in the cathode direction (positively charged fine particles).

  The step of determining whether or not the residual flocculant amount in step S16 is within the range of the target residual amount (hereinafter, this step is referred to as an injected flocculant amount determination step) is executed by the injected flocculant amount determination device 90. In the injected flocculant amount determination step, the residual flocculant amount is compared with the target residual amount. If the residual flocculant amount is larger than the target residual amount, it is determined that the amount of flocculant injected into the raw water is excessive. When the amount of the residual flocculant is smaller than the target residual amount, it is determined that the amount of the flocculant injected into the raw water is too small. The target residual amount can be, for example, the residual flocculant amount measured using test water prepared from treated water in which the amount of flocculant injected has been determined to be appropriate.

  The parameter adjusting device 60 reduces the amount of the flocculant charged into the raw water when it is determined that the amount of the flocculant is excessive, and the raw water when it is determined that the amount of the flocculant is excessive. It is decided to increase the amount of the flocculant to be charged. Then, the determined amount of the flocculant is added to the raw water.

  According to this embodiment, the amount of flocculant remaining in the treated water containing floc was measured using electrophoresis using test water prepared by separating and removing floc from the treated water. Since the estimation is based on the moving speed of the positively charged fine particles, it is possible to determine at an early stage whether the coagulant injected into the raw water (treated water) is excessive or insufficient. Moreover, since test water prepared by separating and removing flocs from the treated water is used, the amount of the remaining flocculant can be estimated with high accuracy even when the turbidity of the treated water is high. For this reason, according to this embodiment, it is possible to accurately determine whether the amount of the flocculant injected into the raw water is excessive or insufficient in a short time.

(Second Embodiment)
FIG. 4 is a block diagram illustrating an example of a water treatment facility according to the second embodiment. In the second embodiment, differences from the first embodiment will be mainly described, and the same components as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

  In the water treatment facility 1b according to the second embodiment, the injection flocculant amount evaluation system 70 is a device that measures the dispersion value of the flock charge contained in the treated water (hereinafter referred to as a floc charge dispersion value measurement device). 100. Also, the injected flocculant amount determination device 90 performs the same processing as when the target residual amount of flocculant is determined that the flock charge dispersion value measured by the flock charge dispersion value measurement device 100 is greater than or equal to the target value. The amount of residual flocculant estimated by the residual flocculant amount estimating device 80 can be changed using water.

The floc charge dispersion value measuring apparatus 100 includes a measurement unit 101 that measures the movement speed of flocs, and a calculation unit 102 that calculates the distribution of flock charges.
The measurement part 101 measures the distribution of the flock charge in the treated water as the movement speed of the flock using electrophoresis. Specifically, the measurement part 101 arrange | positions an anode and a cathode in the treated water containing a flock, applies a voltage to treated water, and measures the moving speed of several flocs for every flock.

The measurement unit 101 includes, for example, a cell in which an anode and a cathode are opposed to each other, a voltage supply device that applies a voltage to the anode and the cathode in the cell, and treated water when a voltage is applied to test water. And a speed measuring device for measuring the moving speed of the floc.
The same cell as that used in the residual flocculant amount measuring device can be used.

  Since the floc in the treated water has a larger particle diameter than the fine particles in the test water used in the residual flocculant amount estimation device 80, it is difficult to move in the water. For this reason, the applied voltage of the voltage supply device used in the floc charge dispersion value measuring device 100 is usually higher than the voltage supply device used in the residual coagulant amount estimation device 80. The applied voltage of the voltage supply device used in the floc charge dispersion value measuring device 100 is generally a voltage of 10 to 20V.

  As the velocity measuring device, a device that measures the position of the floc in the test water when a voltage is applied at least at the first time and the second time after a predetermined time has elapsed from the first time can be used. . The velocity measuring device used in the floc charge dispersion value measuring device 100 uses a device that can measure the position of both the floc moving to the anode of the cell and the floc moving to the cathode. In this case, the measurement of the position of the fine particles may be performed a plurality of times every predetermined time (for example, every 1 second) or continuously for a predetermined time.

  The speed measuring device includes a light source that emits light toward the inside of the cell, a camera that captures flocks contained in the test water, and a display device that displays signals input by capturing using the camera. It is preferable to use one. Any light source may be used as long as it can irradiate the treated water of the cell. 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 where the anode and cathode of the cell are not installed. In this case, since the test water containing the fine particles in the cell is photographed through the wall surface of the cell, a cell formed of a transparent material is used. As the camera, for example, a camera that receives scattered light on the surface of fine particles obtained by irradiating fine particles in test water with a light source can be used.

  The calculation unit 102 receives the signals of the positions of a plurality of flocks included in the treated water measured by the speed measurement device, and generates a moving speed vector of each flock. The calculation unit 102 gives a minus (first sign) when the generated vector includes a component in the anode direction, and gives a plus (second sign) when the generated vector contains a component in the cathode direction. Furthermore, the calculation unit 102 calculates a variance value in the movement speed distribution of a plurality of flocks by counting the negative movement speed and the positive movement speed for each predetermined size. The movement speed of the floc has a close relationship with the charge of the floc. Accordingly, the variance value in the floc moving speed distribution is the same as the variance value of the floc charge.

The calculation unit 102 uses all of the negative movement speeds (all of the components of the vector of the movement speed) as the negative movement speeds used for the aggregation, and all the positive movement speeds as the positive movement speeds used for the aggregation. (All moving velocity vector components) can be used.
Further, the calculation unit 102 uses only the moving speed of the component in the anode direction included in the moving speed vector of each flock among the negative moving speeds as the negative moving speed used for the tabulation, and the plus used for the tabulation. Of the positive movement speeds, only the movement speed of the component in the cathode direction included in the movement speed vector of each floc may be used.

The calculation unit 102 preferably calculates an average value of the negative movement speed and the positive movement speed among the movement speeds of the plurality of flocks.
Note that the calculation unit 102 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 calculation unit 102 and the function of calculating the average value of the negative movement speed and the positive movement speed of the movement speeds of the plurality of flocks are, for example, functions provided in the central processing unit of the computer. Realized.

FIG. 5 is a diagram showing the relationship between the dispersion value of the floc charge and the amount of residual flocculant.
In FIG. 5, (A) to (D) are examples of histograms of charge distributions of a plurality of flocs created by applying a voltage to treated water with different amounts of flocculant injected, and using the same method as the dispersion value described above. . Since the floc charge (surface potential) has a correlation with the absolute value of the floc moving speed as described above, the shape of the floc charge distribution histogram is the same as that of the floc moving speed distribution. . In the graphs of (A) to (D) shown in FIG. 5, the horizontal axis indicates the magnitude of negative charge and positive charge, and is classified for each predetermined surface potential with the center as 0. The vertical axis indicates the number of detections.

  When the charge of floc in the treated water is neutral, even if a voltage is applied to the treated water, the floc is not moved in one direction. For this reason, the detected number is sparse in a wide range without being biased toward the positive region or the negative region. Therefore, the variance value σ of the movement speed distribution of the flock becomes large, and the histogram thereof has a flat distribution shape (for example, see the histograms (B) and (C) in FIG. 5).

  On the other hand, if the charge of floc in the treated water is positive or negative, the floc moving direction is biased toward the cathode or anode, so the histogram of floc moving speed distribution is a positive region or a negative region. (See the histograms of (A) and (D) in FIG. 5). Accordingly, the floc dispersion value σ when the charge is positive or negative is smaller than that when the charge is neutral (when the injection amount of the flocculant is appropriate).

  Thus, the dispersion value σ of the floc charge state tends to be large when the floc aggregation state in the treated water is good and small when the floc aggregation state in the treatment water is poor. Therefore, it is possible to evaluate the dispersion state of the flock charge based on the dispersion value σ of the floc moving speed distribution.

  The graph of FIG. 5E shows the relationship between the dispersion value of the flock charge and the residual flocculant amount with respect to the amount of flocculant injected into the raw water (injected flocculant amount). Each point in the dispersion value graph of (E) in FIG. 5 corresponds to the dispersion value σ of the flock charge distribution shown by the histograms of (A) to (D) in FIG.

  As shown in FIG. 5E, when the dispersion value σ is low (when the floc is negatively charged), the dispersion value σ of the charged state of floc and the amount of residual flocculant in the treated water are small. When the amount of the agent is low and the dispersion value σ is high (when the floc is positively charged), there is a relationship that the amount of the residual flocculant is high. Therefore, it can be seen that by setting the target value of the residual flocculant amount so that the dispersion value σ is equal to or greater than the target value, the state of aggregation of flocs generated in the treated water can be satisfactorily maintained.

  A method for setting the target residual amount of the flocculant will be described with reference to FIG. FIG. 6 is a flowchart for explaining the flow of the method for setting the target residual amount of flocculant implemented by the water treatment facility of the second embodiment.

  In the target residual amount setting method of the present embodiment, first, the parameter adjusting device 60 determines the amount of flocculant to be charged into the raw water (step S20). Next, the determined amount of the flocculant is added to the raw water (step S22). As a result, the suspension in the raw water aggregates and flocs are formed, and treated water containing flocs is generated. The amount of residual flocculant remaining in the generated treated water is estimated (step S24). At the same time, the dispersion value of the charge of the floc contained in the treated water is measured (step S26). Next, it is determined whether or not the flock charge dispersion value is equal to or greater than a target value (step S28). If the dispersion value is equal to or greater than the target value (step S28: YES), the target residual amount is set to the estimated residual coagulant amount value simultaneously with the measurement of the dispersion value (step S30). On the other hand, when the dispersion value is not equal to or greater than the target value (step S28: NO), the flocculant input amount is reset so that the dispersion value is equal to or greater than the target value.

  In the above method for setting the target residual amount of flocculant, the step of determining the input amount of the flocculant in step S20, the step of adding the flocculant to the raw water in step S22, and the step of estimating the residual flocculant amount in step S24 These are the same as the steps S10, S12, and S14 described above.

  The step of measuring the moving speed of the flock in step S26 (hereinafter, this step is referred to as a flock charge dispersion value measurement step) is executed by the flock charge dispersion value measurement apparatus 100. The floc charge dispersion value measuring step includes a step of measuring the moving speed of the floc (hereinafter referred to as the moving speed measuring step) and a step of calculating a dispersion value in the moving speed distribution of the floc (hereinafter referred to as the dispersion value). A calculation step).

  The moving speed measurement process is performed by the measurement unit 101. In the moving speed measuring step, the moving speed of floc in the treated water is measured using electrophoresis. The treated water used as a measurement target in the measurement unit 101 is preferably collected at the same place and time as the treated water used in the residual flocculant amount estimation device 80. In the moving speed measurement step, the treated water is injected into a cell in which an anode and a cathode are arranged to face each other. Next, a voltage is applied to the anode and cathode in the cell. Then, the moving speed of the plurality of flocs contained in the treated water is measured for each floc by the speed measuring device. In the moving speed measurement step, the time for applying the voltage to the treated water can be freely set, and can be, for example, 3 to 5 minutes.

  The variance value calculation step is performed by the calculation unit 102. In the dispersion value calculating step, the first code is assigned when the vector of the moving speed of each floc includes a component in the anode direction, and the second code is added when the vector in the cathode direction includes a component in the cathode direction. And the second code moving speed are totaled for each predetermined size, and a variance value in the moving speed distribution of the plurality of flocks is calculated.

  The step of determining whether or not the dispersion value in step S28 is greater than or equal to the target value and the step of setting the target residual amount in step S30 to the value of the residual flocculant amount are executed by the injected flocculant amount determination device 90. .

  The change in the target residual amount using the dispersion value of the flock charge is, for example, when there is a change in raw water quality or water temperature, when the flocculant is changed, when the flocculant is newly prepared, It is performed when the turbidity of the supernatant water taken out from 40 and the filtration time index (STR) rise.

  According to the present embodiment, the target value of the residual flocculant amount can be set according to the dispersion state of the flock charge contained in the treated water, so that the amount of suspension to be injected into the raw water can be more accurately determined. It is possible to optimize the floc state of flocs generated in the treated water.

  According to at least one embodiment described above, it is possible to accurately determine whether the amount of the flocculant injected into the raw water is excessive or insufficient in a short time. For this reason, the amount of flocculant injected into the raw water can be optimized accurately in a short time, and the suspension contained in the raw water can be efficiently removed using the flocculant.

  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 1a ... Water treatment facility, 1b ... Water treatment facility, 10 ... Water well, 20 ... Rapid mixing pond, 21, 34, 35, 36 ... Stirrer, 22 ... Mixing pond, 30 ... Flock formation pond, 31 ... First stirring Pond, 32 ... second stirring pond, 33 ... third stirring pond, 40 ... precipitation basin, 50 ... filtration basin, 60 ... parameter adjusting device, 61 ... flow rate adjusting valve, 62 ... flow meter, 63 ... pH measuring device, 64 ... pH adjuster injection device, 65 ... flocculant injection device, 70 ... injection flocculant amount evaluation system, 80 ... residual flocculant amount estimation device, 81 ... preparation section, 82 ... measurement section, 83 ... estimation section, 84 ... test Water, 85 ... Suspension particles, 86 ... Flocculant particles, 87 ... Anode, 88 ... Cathode, 90 ... Injected flocculant amount determination device, 100 ... Flock charge dispersion value measurement device, 101 ... Measurement unit, 102 ... Calculation unit

Claims (14)

A step of injecting a flocculant that is positively charged in water into water to be treated containing a negatively charged suspension and aggregating the suspension to generate treated water containing floc;
Estimating the amount of residual flocculant remaining in the treated water;
When the residual flocculant amount is compared with the target residual amount and the residual flocculant amount is larger than the target residual amount, it is determined that the amount of the flocculant injected into the water to be treated is excessive. Determining that the amount of the flocculant injected into the water to be treated is too small when the amount of the residual flocculant is smaller than the target residual amount;
The step of estimating the amount of residual flocculant remaining in the treated water,
Collecting a part of the treated water, separating and removing floc from the collected treated water, and preparing test water containing fine particles;
Disposing an anode and a cathode in the test water, applying a voltage to the test water, and measuring a moving speed of the fine particles moving in the direction of the cathode among the fine particles contained in the test water When,
And a step of estimating the amount of the remaining flocculant remaining in the treated water based on the moving speed of the fine particles moving in the direction of the cathode.   The water treatment method according to claim 1, wherein in the step of preparing the test water, the method for separating and removing floc from the treated water is filtration, centrifugation, or sedimentation separation. Furthermore, it has a step of measuring the dispersion value of the charge of the floc contained in the collected treated water,
Residual aggregation estimated using the treated water when the target residual amount is determined that the flock charge dispersion value measured in the step of measuring the flock charge dispersion value is greater than or equal to the target value The water treatment method according to claim 1, wherein the amount is an agent amount. Measuring the dispersion value of the electric charge of the floc,
Placing an anode and a cathode in the collected treated water, applying a voltage to the treated water, and measuring a moving speed of the plurality of flocs for each floc;
When the vector of the moving speed of each floc includes a component in the direction of the anode, a first code is assigned, and when the vector of the vector in the direction of the cathode includes a component in the direction of the cathode, a second code is assigned. 4. The water treatment method according to claim 3, further comprising: calculating the dispersion value in the movement speed distribution of the plurality of flocks by counting the movement speed of the second code for each predetermined size. A mixing pond that generates treated water containing flocs by injecting a flocculant that is positively charged in water into the water to be treated containing the negatively charged suspension, and aggregating the suspension.
An apparatus for estimating the amount of residual flocculant remaining in the treated water;
When the residual flocculant amount is compared with the target residual amount and the residual flocculant amount is larger than the target residual amount, it is determined that the amount of the flocculant injected into the water to be treated is excessive. And when the amount of the residual flocculant is smaller than the target residual amount, the apparatus determines that the amount of the flocculant injected into the water to be treated is too small,
An apparatus for estimating the amount of the residual flocculant is:
A part for collecting a part of the treated water, separating and removing flocs from the collected treated water, and preparing a test water containing fine particles;
Measurement in which an anode and a cathode are arranged in the test water, a voltage is applied to the test water, and the moving speed of the fine particles moving in the direction of the cathode among the fine particles contained in the test water is measured. And
A water treatment facility comprising: an estimation unit that estimates the amount of residual coagulant remaining in the treated water based on the moving speed of the fine particles moving in the direction of the cathode.   The water treatment facility according to claim 5, wherein in the preparation unit, the method for separating and removing floc from the treated water is filtration, centrifugation, or sedimentation. Furthermore, it has a device for measuring a dispersion value of the charge of the floc contained in the collected treated water,
Residual coagulation estimated using the treated water when the target residual amount is determined that the flock charge dispersion value measured by the apparatus for measuring the flock charge dispersion value is greater than or equal to the target value The water treatment facility according to claim 5, which is a dosage. An apparatus for measuring the dispersion value of the charge of the floc is
A measuring unit that arranges an anode and a cathode in the collected treated water, applies a voltage to the treated water, and measures a moving speed of the plurality of flocs for each floc,
When the vector of the moving speed of each floc includes a component in the direction of the anode, a first code is assigned, and when the vector of the vector in the direction of the cathode includes a component in the direction of the cathode, a second code is assigned. The water treatment facility according to claim 7, further comprising: a calculation unit that counts the moving speed of the second code for each predetermined size and calculates a dispersion value in the moving speed distribution of the plurality of flocks. A coagulant that is charged positively in water is injected into the water to be treated containing a negatively charged suspension, and remains in the treated water containing flocs generated by aggregating the suspension. A device for estimating the amount of residual flocculant;
When the residual flocculant amount is compared with the target residual amount and the residual flocculant amount is larger than the target residual amount, it is determined that the amount of the flocculant injected into the water to be treated is excessive. And when the amount of the residual flocculant is smaller than the target residual amount, the apparatus determines that the amount of the flocculant injected into the water to be treated is too small,
An apparatus for estimating the amount of the residual flocculant is
A part for collecting a part of the treated water, separating and removing flocs from the collected treated water, and preparing a test water containing fine particles;
Measurement in which an anode and a cathode are arranged in the test water, a voltage is applied to the test water, and the moving speed of the fine particles moving in the direction of the cathode among the fine particles contained in the test water is measured. And
An injection flocculant amount evaluation system including an estimation unit that estimates an amount of residual flocculant remaining in the treated water based on the moving speed of the fine particles moving in the direction of the cathode.   The injection flocculant amount evaluation system according to claim 9, wherein the method for separating and removing floc from the treated water in the preparation unit is filtration, centrifugation, or sedimentation separation. Furthermore, it has a device for measuring a dispersion value of the charge of the floc contained in the collected treated water,
Residual coagulation estimated using the treated water when the target residual amount is determined that the flock charge dispersion value measured by the apparatus for measuring the flock charge dispersion value is greater than or equal to the target value The injected flocculant amount evaluation system according to claim 9, wherein the amount is an agent amount. An apparatus for measuring the dispersion value of the charge of the floc is
A measuring unit that arranges an anode and a cathode in the collected treated water, applies a voltage to the treated water, and measures a moving speed of the plurality of flocs for each floc,
When the vector of the moving speed of each floc includes a component in the direction of the anode, a first code is assigned, and when the vector of the vector in the direction of the cathode includes a component in the direction of the cathode, a second code is assigned. And a calculation unit for calculating a dispersion value in the movement speed distribution of the plurality of flocs by totalizing the movement speeds of the second code for each predetermined size. system. A portion of the treated water containing flocs produced by aggregating the suspension is injected by injecting a positively charged flocculant into the water to be treated containing the negatively charged suspension. Separating the floc from the collected treated water and preparing a test water containing fine particles;
Measurement in which an anode and a cathode are arranged in the test water, a voltage is applied to the test water, and the moving speed of the fine particles moving in the direction of the cathode among the fine particles contained in the test water is measured. And
A residual coagulant amount estimation device including an estimation unit that estimates the amount of residual coagulant remaining in the treated water based on the moving speed of the fine particles moving in the direction of the cathode.   The residual flocculant amount estimation device according to claim 13, wherein the method for separating and removing floc from the treated water in the preparation unit is filtration, centrifugation, or sedimentation separation.

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