Operation management device, operation management method and computer program

Abstract

To provide an operation management device which supports a manager setting an appropriate coagulation condition on the basis of a value obtained by quantizing the property of a floc.SOLUTION: An operation management device includes: an optical device 21 for acquiring image information on a floc collected from water to be treated after a coagulant has been added to the water to be treated in a water treatment process including a step of adding the coagulant to the water to be treated; a hue analysis part 22 for performing image analysis using the image information, and calculating a hue index using hue frequency obtained by the image analysis; and an appropriate value calculation part 23 for calculating an appropriate value of a coagulation condition in the water treatment process, on the basis of the hue index.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to an operation management device, an operation management method, and a computer program.

Background Art

[0002] Coagulation is a technique widely used for clarifying water, such as in water purification facilities and industrial wastewater treatment. Taking a water supply facility as an example, suspended substances in water such as clay minerals and plankton are in a dispersed state in water. However, by adding chemicals such as a coagulant, a pH adjuster, and salts, the charge state on the particle surface is neutralized, and the particles are brought into a surface state where they easily come into contact with each other. Further, a shearing force due to stirring is applied to promote the collision and coalescence of the particles, causing them to agglomerate and grow into large aggregates (flocs). The grown flocs are separated by gravitational sedimentation, and the supernatant water becomes clarified water through a separation process such as sand filtration.

[0003] Since the flocs change in particle size and density under the influence of chemical water quality factors such as the injection rate of the coagulant and pH, and hydraulic conditions due to the stirring intensity, it is necessary to adjust the injection rate of the coagulant, pH, and stirring intensity in accordance with fluctuations in the quality of the influent raw water. When the injection rate of the coagulant is increased, the particle size of the flocs increases, but at the same time the density decreases. Therefore, the injection rate of the coagulant and the stirring intensity that appropriately maintain the sedimentation rate related to gravitational sedimentation in the sedimentation tank change in real time.

[0004] The current operation management of water supply facilities is carried out based on the experience values of skilled technicians and the past operation results. However, it has become an issue that it is difficult to inherit the technology, and there are water quality fluctuations without experience accompanying climate change, such as the generation of odors and algae. In order to automate the operation management of water supply facilities, particularly the setting of the injection rate of the coagulant, it is necessary to extract appropriate coagulation conditions for fluctuations in the quality of the raw water.

[0005] Generally, as a means of grasping water quality for the purpose of setting appropriate flocculation conditions, sensors that can output on-line signals such as turbidity meters and pH meters are used. However, there are also water quality items that cannot be detected by existing on-line sensors in water quality.

[0006] Therefore, in addition to grasping water quality, a technique has been proposed in which flocs are detected by taking images, and the image analysis results are reflected in the setting of appropriate flocculation conditions. Water containing flocs in a mixing tank or a floc formation tank is sampled, and an image of the flocs is taken. It is disclosed that from the image analysis results, the roundness and fractal dimension of the flocs are calculated, and the coagulant injection rate and stirring intensity are adjusted so that the roundness or fractal dimension is a certain value or more.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] Physical properties such as the size and density of flocs affect the sedimentation rate and are related to the clarity of the treated water quality. However, it has been difficult to obtain substance information such as floc diameter and density from flocs in water and utilize it for the operation management of water treatment facilities. This is partly because flocs exist in water and cannot maintain their structure in the air and deteriorate, so it is necessary to measure the physical information of flocs while they exist in water. For example, since it is common to estimate the floc density from the sedimentation rate, it can be seen that a direct measurement method for floc density has not been established.

[0009] Embodiments of the present invention have been made in view of the above circumstances, and an object is to provide an operation management device, an operation management method, and a computer program that assist a manager in setting appropriate flocculation conditions based on a value obtained by quantifying the properties of flocs.

Means for Solving the Problem

[0010] The operation management device according to the embodiment includes an optical device that acquires image information of flocs collected from treated water after adding a flocculant in a water treatment process including a step of adding a flocculant to the treated water, an image analysis unit that performs image analysis using the image information and calculates a hue index using the hue frequency obtained by the image analysis, and an appropriate value calculation unit that calculates an appropriate value of the flocculation condition in the water treatment process based on the hue index.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0012] Hereinafter, an operation management device, an operation management method, and a computer program according to an embodiment will be described with reference to the drawings. The operation management device, operation management method, and computer program according to the following embodiments manage a water treatment process including, for example, a step of adjusting the flow rate of raw water flowing into a mixing basin, a step of adding a flocculant to the water to be treated in the mixing basin, a step of adding a pH adjuster to the water to be treated in the mixing basin, a step of stirring the water to be treated after the addition of the flocculant in the mixing basin, a step of stirring the water to be treated in each of a plurality of tanks of a floc formation basin arranged downstream of the mixing basin into which the water to be treated sequentially flows (floc formation step), and a step of adding and stirring a flocculant to the stirred water to be treated (two-stage flocculant injection step and two-stage flocculation stirring step).

[0013] FIG. 1 is a diagram schematically showing a configuration example of a facility managed using the operation management device according to one embodiment. The facility shown in FIG. 1 is a water purification facility including an intake well 1, a mixing basin 2, a floc formation basin 3, a sedimentation basin 4, a two-stage flocculation basin 5, a filtration basin 6, and a water distribution basin 7.

[0014] The intake well 1 is a facility for temporarily storing raw water taken from a water source. The raw water contains suspended substances composed of clay, plankton, etc., and is separated into clarified water and sediment sludge by subsequent coagulation sedimentation.

[0015] The intake well 1 is provided with a raw water pH meter 8 and a raw water pH adjuster injector 16. In the intake well 1, acids such as sulfuric acid and hydrochloric acid, carbon dioxide gas, and bases such as caustic soda and slaked lime are injected into the raw water so that the pH of the raw water becomes an appropriate value (pH range) with respect to the flocculant injected in the subsequent mixing basin 2, thereby adjusting the pH.

[0016] The raw water pH adjuster injector 16 injects a pH adjuster into the raw water based on the pH value of the raw water measured by the raw water pH meter 8. The raw water pH adjuster injector 16 can be a pump whose discharge amount can be adjusted, or a valve whose opening degree can adjust the injection amount of the pH adjuster. The raw water pH meter 8 may be installed not only in the intake well 1 but also in the pipe or storage tank between the intake well 1 and the mixing basin 2.

[0017] A flow meter 9 and a flow control valve 12 are installed between the intake well 1 of the water purification facility and the mixing tank 2. The flow meter 9 measures the flow rate of the raw water, and the flow control valve 12 adjusts the flow rate of the raw water. The opening degree of the flow control valve 12 can be adjusted based on the raw water flow rate (the opening degree of the flow control valve 12) or the adjusted value of the raw water flow rate supplied from the operation management device described later.

[0018] The raw water flow rate affects the residence time of each of the mixing tank 2, the floc formation tank 3, the sedimentation tank 4, and the two-stage coagulation tank 5. For example, when the coagulation is not very good, the growth of the flocs can be promoted by reducing the raw water flow rate. The flow control valve 12 does not necessarily have to be a valve, and any configuration having a function of adjusting the flow rate of the raw water, such as a pump with a variable discharge amount or a branch to a temporary storage tank, may be used.

[0019] The mixing tank 2 is equipped with a mixing tank pH meter 10, a mixing tank agitator 13, a flocculant injector 17, and a mixing tank pH adjuster injector 18. In the mixing tank 2, the suspended substances in the raw water and the flocculant are stirred and mixed, and the suspended substances are coagulated. The stirring is performed by the mixing tank agitator 13.

[0020] The mixing tank agitator 13 is mechanically driven by energy consumption, and is a device that performs stirring by the vibration or rotation of stirring blades such as a flash mixer or an impeller type agitator, and the stirring intensity can be adjusted. The mixing tank agitator 13 adjusts the stirring intensity based on the stirring intensity or the value of the adjusted amount of the stirring intensity supplied from the operation management device described later.

[0021] The flocculant injector 17 injects a flocculant into the raw water in the mixing tank 2. The flocculant may be, for example, not only aluminum-based flocculants such as polyaluminum chloride (PAC), high basicity PAC, and sulfuric acid band, but also iron-based flocculants such as polyferric sulfate, ferric chloride, and polysilicate iron (PSI). When a flocculant is added to the raw water, the pH of the raw water decreases due to the nature of the flocculant itself. The flocculant injector 17 can adjust the flocculant injection rate based on the flocculant injection rate or the value of the adjusted amount of the flocculant injection rate supplied from the operation management device described later.

[0022] The mixing tank pH adjuster injector 18 injects a pH adjuster into the raw water in the mixing tank 2 based on the measured value of the mixing tank pH meter 10. For example, when the pH of the raw water has increased due to the growth of algae, the raw water pH value may not be fully adjusted to an appropriate value at the intake well 1. Therefore, based on the measured value of the mixing tank pH meter 10, the mixing tank pH adjuster injector 18 adjusts the pH of the raw water in the mixing tank 2 to a pH range where the flocculant acts efficiently using an acid or a base. The mixing tank pH adjuster injector 18 can adjust the pH adjuster injection rate based on the value of the pH adjuster injection rate or the adjustment amount of the pH adjuster injection rate supplied from the operation management device described later.

[0023] The properties of the flocs formed in the mixing tank 2 are affected by physical conditions such as the stirring intensity of the mixing tank stirrer 13 and the residence time of the raw water (water to be treated) in the mixing tank 2, in addition to water quality conditions such as the flocculant injection rate of the flocculant injector 17, pH, and water temperature.

[0024] The floc formation tank 3 includes a plurality of tanks (first formation tank, second formation tank, third formation tank), and slow stirring is performed in each tank to promote the collision and coalescence of the flocs and agglomerate them into larger flocs. The floc formation tank 3 is often composed of, for example, three tanks with gradually reduced stirring intensity. However, in this embodiment, the number of tanks in the floc formation tank 3 is not limited to three. The floc formation tank 3 may consist of one or two tanks, may include four or more formation tanks, or may have a tank where the water to be treated stays without stirring.

[0025] The flocculation formation tank 3 is equipped with flocculation formation tank agitators 14A - 14C. Each of the flocculation formation tank agitators 14A - 14C is arranged in each of the plurality of tanks of the flocculation formation tank 3. The flocculation formation tank agitators 14A - 14C can each individually adjust the agitation intensity. The growth of flocs in the flocculation formation tank 3 is greatly affected by the agitation intensity by the flocculation formation tank agitators 14A - 14C. The flocculation formation tank agitators 14A - 14C may be those driven mechanically with an inverter and a speed reducer mounted on a paddle - type agitator to adjust the agitation intensity, or those that utilize the force of the flow of water such as a cross - flow type, and adjust the agitation intensity by adjusting the flow rate. The flocculation formation tank agitators 14A - 14C can adjust the agitation intensity based on the value of the agitation intensity or the adjustment amount of the agitation intensity supplied from the operation management device described later.

[0026] In the sedimentation tank 4, the flocs that have grown significantly in the flocculation formation tank 3 are sedimentation - separated. Depending on the properties of the flocs and the residence time of the sedimentation tank 4 that changes according to the raw water flow rate adjusted by the flow rate adjustment valve 12, the flocs that have not sedimented flow out from the outlet of the sedimentation tank 4.

[0027] A sedimented water turbidimeter 11 is installed near the outlet of the sedimentation tank 4. The flocs flowing out from the sedimentation tank 4 become turbidity of the sedimented water and are measured as turbidity by the sedimented water turbidimeter 11. The turbidity of the sedimented water measured by the sedimented water turbidimeter 11 increases or decreases depending on the raw water pH in the intake well 1 measured by the raw water pH meter 8, the raw water flow rate adjusted by the flow rate adjustment valve 12, the injection rate of the flocculant injected by the flocculant injector 17 in the mixing tank 2, the pH adjusted by the pH adjuster injected by the mixing tank pH adjuster injector and measured by the mixing tank pH meter 10, the agitation intensity adjusted by the mixing tank agitator 13, the agitation intensity adjusted by the flocculation formation tank agitators 14A - 14C, and the quality of the flocculation conditions due to the residence time of the water to be treated in the sedimentation tank 4, and is used as a management index for operation management.

[0028] The secondary flocculation basin 5 is equipped with a secondary flocculant injector 19, a secondary flocculation pH adjuster injector 20, and a secondary flocculation agitator 15. The secondary flocculation basin 5 stores the sedimentation water that has flowed out from the sedimentation basin 4. The sedimentation water flowing into the secondary flocculation basin 5 has a flocculant added by the secondary flocculant injector 19, a pH adjuster injected by the secondary flocculation pH adjuster injector 20, and is stirred and mixed by the secondary flocculation agitator 15. The secondary flocculant injector 19 can adjust the flocculant injection rate based on the value of the flocculant injection rate or the adjustment amount of the flocculant injection rate supplied from the operation management device described later. The secondary flocculation agitator 15 can adjust the agitation intensity based on the value of the agitation intensity or the adjustment amount of the agitation intensity supplied from the operation management device described later.

[0029] In the secondary flocculation basin 5, the fine flocs that have flowed out from the sedimentation basin 4 are re-flocculated by the chemical action of the flocculant and the collision and coalescence of the flocs due to agitation. The type of flocculant injected into the sedimentation water in the secondary flocculation basin 5 is not limited, and generally, the same flocculant as that injected into the raw water in the mixing basin 2 is used. When using secondary flocculation, it is common practice to reduce the flocculant injection rate in the mixing basin 2. Although the pH of the sedimentation water decreases due to the action of the flocculant, a pH adjuster is used to maintain the pH of the sedimentation water in the secondary flocculation basin 5 within the flocculation range of the flocculant (the pH range in which the flocculant acts efficiently). Note that the secondary flocculation basin 5 is not an essential component in the water purification facility and may be omitted.

[0030] In the filtration basin 6, the sedimentation water containing the re-flocculated flocs in the secondary flocculation basin 5 is adsorption-filtered, and the flocs contained in the sedimentation water are solid-liquid separated. The filtration basin 6 assumes sand filtration such as single-layer filtration or multi-layer filtration. Filter media such as filtration sand, anthracite, garnet, and manganese sand can be used. By being filtered in the filtration basin 6, the turbidity is reduced, and the clarified treated water is stored in the distribution basin 7 and then distributed after adding chlorine such as sodium hypochlorite.

[0031] Here, in order to keep the treated water quality clear against water quality fluctuations in the water source, it is necessary to grow the suspended substances into flocs of a size that can be separated in the mixing tank 2 and the floc formation tank 3, and then perform sedimentation separation in the sedimentation tank 4. The properties of the flocs change under the influence of raw water quality, flocculant injection rate, pH, stirring intensity, residence time, etc. From the perspective of water treatment, it is important to maintain the sedimentation rate of the flocs above a certain level. The sedimentation rate formula of the flocs uses Stokes' sedimentation equation (Equation 1) applied based on the experimental results of rigid particles with unchanging shapes. Rigid particles have the property that their density is uniform, their shape is unchanged, and the larger the particle size, the greater the sedimentation rate.

[0032] However, since flocs with a fractal structure have a network structure that encloses moisture, they have the property that the larger the floc diameter, the lower the apparent density in water. The relationship between this floc diameter and density is represented by the floc density function (Equation 2). Equation 2 shows that the effective density Δρ decreases in relation to the power of the floc diameter d.

[0033]

Equation

[0034] FIG. 2 is a diagram schematically showing a configuration example of the operation management device of the first embodiment. The operation management device of the present embodiment is an arithmetic device including at least one processor and a memory storing a program executed by the processor. The operation management device can realize various functions described below by software or a combination of software and hardware.

[0035] The operation management device of the present embodiment may include an input unit (not shown) into which various information is input by an administrator's operation, an output unit (not shown) that outputs a value calculated by the processor, and a communication unit (not shown) that communicates with the outside via a network such as the Internet. The administrator can input various information into the operation management device through the input unit and adjust the operation amount of the facility to be managed. The output unit may include, for example, a display unit such as a monitor on which information for the administrator to monitor the state of the facility to be managed is displayed, and the value calculated by the processor may be presented to the administrator by being displayed on the display unit such as a monitor.

[0036] Further, the operation management device may be connected so as to be accessible to a database in which, for example, past management data (actual values) of the facility to be managed is accumulated, and the processor can realize various functions using the data accumulated in the database.

[0037] The operation management device of this embodiment includes an optical device 21, a hue analysis unit 22, and an appropriate value calculation unit 23. The appropriate value calculation unit 23 includes a flocculant injection rate calculation unit 24, a pH adjuster injection rate calculation unit 25, a stirring intensity calculation unit 26, and a flow rate adjustment calculation unit 27.

[0038] The optical device 21 is supplied with flocs collected from at least one of the mixing tank 2, the outlet of the floc formation tank 3, the outlet of the sedimentation tank 4, and the two-stage flocculation tank 5. When collecting flocs in the floc formation tank 3 and the two-stage flocculation tank 5, etc., a method that does not break the flocs as much as possible is used. Examples of the method for collecting flocs include a method of collecting the flocs together with the surrounding water by the water level height difference using natural flow or a siphon, a method of pumping by a constant volume pump such as a uniaxial screw pump, a method of branching the flow path and passing water through the optical device 21, and a method of immersing an underwater camera in the mixing tank 2, the floc formation tank 3, the sedimentation tank 4, and the two-stage flocculation tank 5.

[0039] The optical device 21 acquires the image of the supplied flocs by taking pictures. The optical device 21 may distinguish the supplied flocs for each place where they are collected and take pictures of the floc images corresponding to each place. The optical device 21 may take pictures of the floc images by the bright-field observation method or the dark-field observation method.

[0040] In the case of bright-field observation method, the optical device 21 includes an image sensor composed of an imaging element, a lens for adjusting the focal position and depth of focus, a flock to be photographed, and a light source for illuminating the object to be photographed. The image sensor may be, for example, a high-speed camera, a web camera, an industrial monitoring camera, a machine vision camera, or a CCD camera. The light source may be any device that can increase the illuminance, such as an LED light source, a halogen lamp, a fluorescent lamp, or a device having a light-emitting part such as an optical fiber. It is desirable that the wavelength and illuminance can be selected and adjusted according to the particle concentration and color of the measurement object. The shape of the light source may be a linear light source with lamps arranged horizontally or a flat light source. If necessary, a diffuser plate can be used in combination to equalize the illuminance and widen the irradiation range where the light is irradiated.

[0041] In the case of dark-field observation method, the optical device 21 irradiates light on the flock from an oblique direction (a direction intersecting the vertical and horizontal directions), and only a part of the light scattered by the flock is detected by the image sensor. Among the dark-field observation methods, the optical device 21 based on the Schlieren method includes a collimating lens, a light source, an image sensor, and a light shield. The optical device 21 irradiates parallel light through the collimating lens on the flock, uses a light shield that blocks a part of the transmitted light, and detects only a part of the light scattered or diffracted by the flock with the image sensor. The dark-field observation method is used when photographing an object with low contrast, is derived from PAC, and is also effective for detecting a transparent gel-like polymer of aluminum hydroxide that forms a cross-linked structure of the flock.

[0042] The image information of the image photographed by the optical device 21 is sent to the hue analysis unit 22. The image information output from the optical device 21 includes at least image data, and may further include information for identifying the location where the photographed flock was collected, date and time information, etc. Note that the operation management device only needs to be able to acquire the image information of the flock photographed by the optical device 21, and the optical device 21 may have a configuration outside the operation management device.

[0043] The hue analysis unit 22 acquires the image information supplied from the optical device 21 and performs image analysis using the image information. FIG. 3 is a diagram schematically showing an example of the hue frequency measured by the optical device of the operation management device according to an embodiment.

[0044] The hue frequency (hue histogram) measured by the image analysis of the hue analysis unit 22 is detected as shown in FIG. 3, for example. In FIG. 3, the vicinity of 0.0 on the horizontal axis corresponds to red, and the vicinity of 0.6 on the horizontal axis corresponds to blue. The vertical axis of the graph shown in FIG. 3 indicates the number of pixels having the hue value as the frequency. In this example, the hue frequencies obtained as a result of image analysis of objects (samples) of three types of flocks (objects to be inspected) having different density ratios ρ are shown. Here, the density ratio ρ can be defined as follows in Equation 3 using the concentration of the suspended substance that generated the flock (object to be inspected) and the concentration of the flocculant. ρ = (concentration of flocculant [mg / L]) / (concentration of suspended substance [mg / L])... Equation 3

[0045] According to the graph shown in FIG. 3, it can be seen that the hue frequency of the image obtained by photographing the flock has two peaks, and the peak values are correlated with the density ratio ρ. Here, among the two peaks, the one with the smaller hue value will be described as the first peak, and the one with the larger hue value will be described as the second peak. When the injection rate of the flocculant injected into the water to be treated is changed, the magnitude relationship between the two peaks of the hue frequency graph changes.

[0046] The hue analysis unit 22 calculates a flock hue index using, for example, the heights (frequency values) of the two peaks of the hue frequency from the detection result of the hue frequency. The flock hue index γ can be calculated by, for example, the ratio of the heights of the two peaks of the hue frequency as shown in the following Equation 4. γ(-) = (height of the second peak of the hue frequency) / (height of the first peak of the hue frequency)... Equation 4 Further, the hue analysis unit 22 defines, for example, two regions in the graph of hue frequencies. In the present embodiment, the hue analysis unit 22 defines a first region including the first peak and a second region including the second peak before and after, with the hue value near the center of the two peaks (for example, the hue value with the smallest frequency) as the boundary. Around the peak of the first region, the higher the density ratio ρ, the lower the frequency. Around the peak of the second region, the higher the density ratio ρ, the higher the frequency.

[0047] The hue analysis unit 22 may calculate, for example, the area of the histogram (the integrated value of the frequency values) in each of the first region and the second region, and use the area ratio as the value of the flock hue index γ as shown in the following formula 5. γ(−)=(Area of the second region) / (Area of the first region) … Formula 5

[0048] Note that the above formulas 4 and 5 are examples of formulas for calculating the flock hue index γ. The hue index γ may be any value that represents the characteristics of the hue frequency detected from the image information of the flock, and may be a value calculated by combining the heights of the two peaks, the areas of the first region and the second region, etc.

[0049] The size of the flock, the hue frequency of the flock, and the flock hue index γ obtained as a result of the image analysis in the hue analysis unit 22 are supplied to the appropriate value calculation unit 23. When the hue analysis unit 22 analyzes the images of the flocks collected at a plurality of locations, the size of the flock, the hue frequency of the flock, and the flock hue index γ corresponding to each of the plurality of flocks are supplied to the appropriate value calculation unit 23.

[0050] The appropriate value calculation unit 23 calculates various appropriate values for appropriately operating the water purification facility using the results of image analysis supplied from the hue analysis unit 22. Since the floc hue index γ can be an index for determining the state of the floc, for example, based on the residence time of the water to be treated in the water purification facility (the time from when the raw water flows into the facility until it is discharged as treated water), the number of tanks in the floc formation tank 3, the reference value that the treated water should fill, etc., the range of the appropriate value of the floc hue index γ can be set. The appropriate value calculation unit 23 can adjust the chemical injection rate, the agitation intensity, and the raw water flow rate so that the floc hue index γ falls within the range of the appropriate value. Note that the appropriate value (target value γ SV ) of the floc hue index γ can be determined by performing a simple test such as a jar test in advance or adopting the measurement result (operation actual value) of the floc during appropriate operation.

[0051] The appropriate value calculation unit 23 calculates the appropriate values of the coagulant injection rate, the pH adjuster injection rate, the agitation intensity, and the raw water flow rate so that the hue index γ becomes the previously obtained hue index target value γ SV and the measured value of the hue index γ matches the hue index target value γ SV . The appropriate value calculation unit 23 can output the calculated appropriate values so that they can be displayed on the screen of an HMI (Human Machine Interface) or a PC (personal computer), present them to the administrator of the water purification facility, and use them for operation support.

[0052] The appropriate value calculation unit 23 may perform automatic control using, for example, the floc hue index γ and the target value γ SV . The appropriate value calculation unit 23 can calculate the manipulated variable MV from the deviation e between the measured value of the hue index γ SV shown in the following formulas 6 and 7 and the hue index target value, and adjust the manipulated variable by PI control. The manipulated variables adjusted by the appropriate value calculation unit 23 are the coagulant injection rate, the pH adjuster injection rate, the agitation intensity, the raw water flow rate, etc.

[0053]

Equation

[0054] Figure 4 is a diagram schematically showing an example of the relationship between the floc hue index, the coagulant injection rate, and the pH. In Figure 4, with the horizontal axis representing the coagulant injection rate and the vertical axis representing the floc hue index γ, an example of the relationship between the coagulant injection rate and the floc hue index γ is shown for the case where the pH of the water to be treated is appropriate, the case where the pH is higher than the appropriate value, and the case where the pH is lower than the appropriate value. The coagulant injection rate on the horizontal axis refers to the coagulant injection rate injected in the mixing tank 2 or the coagulant injection rate injected in the two-stage coagulation tank 5. The pH is either the pH of the mixing tank 2 measured by the mixing tank pH meter 10 or the pH of the two-stage coagulation tank 5.

[0055] Flocs are mainly composed of a part of suspended substances containing sand, plant fragments, dead plankton, etc., and a transparent gel part composed of a polymer of aluminum hydroxide that binds them together like glue. When the coagulant injection rate increases, the proportion of the transparent gel part constituting the flocs increases, and the suspended substances become relatively coarser, so the hue index γ changes.

[0056] There is an appropriate pH range in which charge neutralization and cross-linking action are likely to occur in the coagulant. Depending on the nature of the turbidity contained in the raw water, for example, in the case of PAC, it is around pH 6.8 - 7.2. This is due to the influence of the valence change caused by the change in the ionization state of aluminum ions, which are the main components of PAC, and the fact that the pH at which insoluble aluminum hydroxide is likely to precipitate is around 8.0. When the pH is high, coarse flocs with a large amount of the transparent gel part are formed, and when the pH is low, dense flocs with a small amount of the transparent gel part are formed. Therefore, in addition to the coagulant injection rate, the hue index γ changes according to the pH. Such a relationship between the coagulant injection rate and the hue index γ varies depending on the type of coagulant.

[0057] As described above, the flocculant injection rate calculation unit 24 and the pH adjuster injection rate calculation unit 25 can adjust the flocculant injection rate and the pH adjuster injection rate so that the value of the hue index γ falls within an appropriate range. The flocculant injection rate calculation unit 24 and the pH adjuster injection rate calculation unit 25, for example, make the difference between the hue index γ and the appropriate value (target value γ SV ) of the hue index γ zero (so that the hue index γ follows the target value γ SV ), and calculate the adjustment amounts of the flocculant injection rate and the pH adjuster injection rate by, for example, proportional control or proportional integral control, thereby adjusting the flocculant injection rate and the pH adjuster injection rate.

[0058] The flocculant injection rate calculation unit 24 supplies the corresponding adjusted flocculant injection rate (or the adjustment amount of the flocculant injection rate) to each of the flocculant injector 17 and the two-stage flocculant injector 19. The pH adjuster injection rate calculation unit 25 supplies the corresponding adjusted pH adjuster injection rate (or the adjustment amount of the pH adjuster injection rate) to each of the raw water pH adjuster injector 16, the mixing tank pH adjuster injector 18, and the two-stage flocculation pH adjuster injector 20.

[0059] FIG. 5 is a diagram schematically showing an example of the relationship between the floc hue index and the floc diameter. Here, an example of the relationship between the diameter of flocs collected from two types of water to be treated with different flocculant injection rates (flocculant injection rate A and flocculant injection rate B) in the mixing tank 2 or the two-stage flocculation tank 5 and the floc hue index γ of the image of the flocs is shown.

[0060] If the density ρ s of the flocs is defined as the ratio of the suspended solid portion to the transparent gel portion, the relationship between the hue index γ and the floc diameter d can be expressed by the following formula 8 or formula 9. The floc diameter is a value determined by the flocculant injection rate and the stirring intensity, and affects the sedimentation rate of the flocs in the sedimentation tank 4. Therefore, it is also possible to calculate a predicted value of the solid-liquid separation efficiency in the sedimentation tank 4 from the floc hue index γ.

[0061]

Equation

[0062] From the above, the flocculant injection rate calculation unit 24 and the agitation intensity calculation unit 26 can adjust the flocculant injection rate and the agitation intensity so as to be within an appropriate range based on the value of the hue index γ (the value of the floc diameter corresponding to the value of the hue index γ).

[0063] The flocculant injection rate calculation unit 24 and the agitation intensity calculation unit 26, for example, make the difference between the measured value of the hue index γ and the appropriate value of the hue index γ (target value γ SV ) zero (so that the hue index γ follows the target value γ SV ), and calculate the adjustment amounts of the flocculant injection rate and the agitation intensity by, for example, proportional control or proportional-integral control, thereby adjusting the flocculant injection rate and the agitation intensity. When the target value γ SV of the hue index γ changes depending on the values of the flocculant injection rate and the agitation intensity, for example, after the flocculant injection rate calculation unit 24 determines an appropriate flocculant injection rate in relation to pH, the value of the hue index γ corresponding to the appropriate floc diameter at the appropriate flocculant injection rate may be used as the target value γ SV and the appropriate agitation intensity may be calculated by the agitation intensity calculation unit 26.

[0064] When the agitation intensity of each of the agitators 14A - 14C installed in each of the plurality of tanks of the floc formation tank 3 can be set individually, the agitation intensity calculation unit 26 may set the target value γ SV of the hue index γ for each of the agitators 14A - 14C and calculate the appropriate agitation intensity, or after setting the target value γ SV of the hue index γ for any one of the agitators 14A - 14C and calculating the appropriate agitation intensity, the agitation intensity of the other agitators may be adjusted according to the calculated appropriate value.

[0065] For example, when gradually decreasing the agitation intensity in the plurality of tanks of the floc formation tank 3, the agitation intensity calculation unit 26 sets the target value γ of the hue index γ for the largest agitation intensity, the smallest agitation intensity, or the average value of the agitation intensitySV Set it so that the measured value of the hue index γ follows the target value γ SV Calculate the adjustment amount of the stirring intensity so as to follow, and adjust a plurality of stirring intensities using the calculated adjustment amount.

[0066] The stirring intensity calculation unit 26 supplies the corresponding adjusted stirring intensity (or the adjustment amount of the stirring intensity) to each of the mixing tank stirrer 13, the floc formation tank stirrers 14A - 14C, and the two-stage aggregation stirrer 15.

[0067] Figure 6 is a diagram schematically showing an example of the relationship between the floc hue index and the stirring intensity. When the stirring intensity of the stirrers 14A - 14C in the floc formation tank 3 is large, the water contained in the flocs is squeezed out and the structure has a large ratio of suspended substances. When the stirring intensity is small, the flocs have a swollen structure containing a large amount of water. Since the floc hue index γ is related to the ratio of the suspended substances and the transparent gel part in the flocs, for example, as shown in Figure 6, when the stirring intensity decreases, the hue index γ decreases, and when the stirring intensity increases, the hue index γ tends to increase.

[0068] From the above, the stirring intensity calculation unit 26 can adjust the stirring intensity so that it falls within an appropriate range based on the value of the hue index γ (the structure of the flocs corresponding to the value of the hue index γ). The stirring intensity calculation unit 26, for example, makes the difference between the measured value of the hue index γ and the appropriate value of the hue index γ (target value γ SV ) corresponding to the appropriate floc structure zero (so that the measured value of the hue index γ follows the target value γ SV ) and calculates the adjustment amount of the stirring intensity by, for example, proportional control or proportional integral control, thereby adjusting the stirring intensity.

[0069] The stirring intensity calculation unit 26 supplies the corresponding adjusted stirring intensity (or the adjustment amount of the stirring intensity) to each of the mixing tank stirrer 13, the floc formation tank stirrers 14A - 14C, and the two-stage aggregation stirrer 15.

[0070] Figure 7 is a diagram schematically showing an example of the relationship between the floc hue index and the raw water flow rate. The raw water flow rate adjusted by the flow rate adjustment valve 12 affects the residence time of the water to be treated in the mixing tank 2, the floc formation tank 3, and the sedimentation tank 4. Due to these residence times, the frequency of floc collision and coalescence changes, and the floc diameter tends to increase by taking in fine particles. As described above, since the floc density decreases in a power-law relationship with respect to the floc diameter, when the residence time is sufficiently ensured, the floc diameter increases, resulting in coarse flocs with a reduced suspended substance ratio. The floc color phase index γ is a value that reflects the ratio of the suspended substances and the transparent gel portion in the floc, and it is possible to determine whether the residence time of the water to be treated and the raw water flow rate are appropriate based on the floc color phase index γ.

[0071] From the above, the flow rate adjustment calculation unit 27 can adjust the raw water flow rate (the opening degree of the flow rate adjustment valve 12) to an appropriate value based on the value of the color phase index γ. For example, the flow rate adjustment calculation unit 27 SV makes the difference between the measured value of the color phase index γ and the appropriate value (target value γ SV ) of the color phase index γ corresponding to an appropriate raw water flow rate zero (so that the measured value of the color phase index γ follows the target value γ

[0072] The flow rate adjustment calculation unit 27 supplies the adjusted raw water flow rate (or the adjusted value of the raw water flow rate) to the flow rate adjustment valve 12.

[0073] Next, the effects of the operation management device, operation management method, and computer program of the present embodiment will be described. Generally, the turbidity at the outlet of the sedimentation tank is used as an operation management index in a water purification plant. That is, in many general water purification plants, the turbidity of the sedimentation water measured by the sedimentation water turbidimeter 11 is used as the operation management index. The turbidity at the outlet of the sedimentation tank is what is detected as turbidity due to the fine suspended substances that flowed out without settling in the sedimentation tank. Whether the flocculation conditions are appropriate or not is often judged by the magnitude of the turbidity at the outlet of the sedimentation tank. The residence time of the combined flocculation formation tank 3 and sedimentation tank 4 depends on the raw water flow rate, but is about 2 to 4 hours. Therefore, whether the flocculant injection rate, pH, and agitation intensity are appropriate for the fluctuating raw water quality can only be judged when the turbidity of the sedimentation water turbidimeter 11 rises above the control value several hours after injecting the flocculant into the water to be treated.

[0074] If the flocculation conditions are not appropriate, the flocculation conditions are immediately changed, but there is a time lag of several hours, and for about several hours thereafter, the water to be treated treated under inappropriate flocculation conditions continues to flow, increasing the processing load on the subsequent sedimentation tank 4 and filtration tank 6. Thus, it is important to detect whether the flocculation conditions are appropriate or not at the earliest stage after injecting the flocculant.

[0075] In contrast, according to the operation management device of the present embodiment, it is possible to judge whether the flocculation conditions are appropriate or not from the substance information of the flocs in the mixing tank 2, the flocculation formation tank 3, etc. As a result, since it is possible to judge the flocculation conditions in the process on the raw water side before the outlet of the sedimentation tank, it is possible to shorten the time loss from adjusting the flocculation conditions until the influence on the water quality appears. If the flocculation conditions are inappropriate, it is possible to reduce the amount of poor-quality water generated.

[0076] That is, according to the operation management device of the present embodiment, using the hue index γ of the flocs obtained as a result of analyzing the image of the flocs collected in the mixing tank 2 or the flocculation formation tank 3, it is possible to calculate the appropriate values of the flocculant injection rate, pH, agitation intensity, and raw water flow rate (residence time). Thereby, it is possible to judge whether the flocculation conditions are appropriate at an early stage after injecting the flocculant into the water to be treated, and it becomes possible to adjust the flocculation conditions without time loss.

[0077] In addition, since the turbidity at the sedimentation tank outlet is the result of the coagulation sedimentation process, it is not clear which process in the water purification treatment had inappropriate coagulation conditions. However, in this embodiment, by obtaining the substance information of the flocs following the coagulation process, such as in the mixing tank 2, the floc formation tank 3, and the sedimentation tank 4, it is also possible to narrow down the locations where the coagulation conditions need to be changed.

[0078] Moreover, according to this embodiment, by using the hue index γ of the flocs, the substance information of the flocs can be quantified, and the raw water quality and the substance information of the flocs can be accumulated together as the operation management results. Also, operation management such as adjusting the coagulation conditions can be performed without relying on the subjective judgment of the operator, and technical inheritance can be supported when the person in charge changes. Further, according to the floc hue index γ, since the properties of the flocs rather than the water quality can be quantified, the relationship between the coagulation conditions and the coagulation state of the flocs can be clearly grasped, leading to a reduction in the burden on the operator.

[0079] As described above, according to this embodiment, it is possible to provide an operation management device, an operation management method, and a computer program that assist an administrator in setting appropriate coagulation conditions based on the quantified value of the properties of the flocs.

[0080] Note that the coagulant is generally added in the mixing tank 2, but the coagulant may also be added to the water at the sedimentation tank outlet (settled water), which is called two-stage coagulation treatment. The purpose of the two-stage coagulation treatment is to re-coagulate the fine flocs flowing out of the sedimentation tank, suppress the increase in the filtration resistance in the subsequent filtration tank, increase the capture efficiency, and reduce the total coagulant injection rate obtained by adding the coagulant injection rate in the mixing tank 2 and the coagulant injection rate at the outlet of the sedimentation tank 4.

[0081] However, since the flocs contained in the sedimentation water are fine and few in number, they are difficult to aggregate, and it is difficult to adjust the aggregation conditions. Therefore, if the operation management device of this embodiment can measure the substance information of the flocs by secondary aggregation in which the sedimentation water is re-aggregated, the appropriate value of the aggregation conditions in the secondary aggregation will be clarified, leading to a reduction in the load of operation management. In this way, by calculating the appropriate value of the aggregation conditions, not only the burden on the operator can be reduced, but also the running costs such as chemical costs, sludge disposal costs, and power costs can be reduced, while ensuring the treated water quality against fluctuations in the raw water quality.

[0082] Next, the operation management device, operation management method, and computer program of the second embodiment will be described. In the operation management device of this embodiment, for the flocs in the mixing tank 2 and the flocs in the floc formation tank 3, image capturing is performed by the optical device 21, and the hue frequency γ is calculated by the hue analysis unit 22. For example, the hue index value γ of the flocs in the mixing tank 2 calculated by the hue analysis unit 22 is γ M , and the hue index values γ of the flocs in the three tanks (the first formation tank, the second formation tank, and the third formation tank) of the floc formation tank 3 are γ f1 , γ f2 , γ f3 , respectively.

[0083] Generally, since the flocs grow between the mixing tank 2 and the outlet of the floc formation tank 3, it is assumed that the floc structure gradually changes from fine to coarse between the mixing tank 2 and the outlet of the floc formation tank 3. Therefore, for example, if γ M <γ f1 , it can be seen that the current aggregation conditions are within the operable range. For example, if γ M >γ f1 , it can be seen that the ratio of suspended substances constituting the flocs increases between the mixing tank 2 and the floc formation tank 3, and the internal structure of the flocs is dense. In this case, there is a possibility that the flocs are not growing in the flow from the mixing tank 2 to the floc formation tank 3, and it should be considered to review and adjust the coagulant injection rate, pH, stirring intensity, and raw water flow rate in the mixing tank 2. That is, the appropriate value calculation unit 23 determines that γ M <γ f1If not, the administrator should be informed that the coagulant injection rate, pH, stirring intensity, and raw water flow rate in the mixing tank 2 should be reviewed and adjusted, and the administrator can be assisted.

[0084] Also, in the floc formation tank 3, it is common practice to gradually reduce the stirring intensity from the first tank (the inlet - side tank) to the third tank (the outlet - side tank). Therefore, the magnitude relationship of the floc color index γ is usually γ f1 ≦γ f2 ≦γ f3 as follows.

[0085] On the other hand, if the magnitude relationship of the floc color index γ is different from the normal situation such as γ f1 ≧γ f2 ≧γ f3 it is possible that the stirring intensity of the stirrers 14A - 14C or the coagulation conditions in the mixing tank 2 are inappropriate. Therefore, it should be considered to review and adjust the coagulant injection rate, pH, stirring intensity, and raw water flow rate in the mixing tank 2. That is, when the appropriate value calculation unit 23 determines that γ f1 ≦γ f2 ≦γ f3 is not satisfied, it can inform the administrator that the coagulant injection rate, pH, stirring intensity, and raw water flow rate in the mixing tank 2 should be reviewed and adjusted, and assist the administrator.

[0086] From the above, in the operation management device of this embodiment, the appropriate value calculation unit 23 compares the hue index value γ of the flocs in the mixing tank 2 M with the hue index values γ f1 、γ f2 、γ f3 of the flocs in the three tanks of the floc formation tank 3, and can determine whether to review and adjust the floc coagulation conditions. When the appropriate value calculation unit 23 determines that the floc coagulation conditions should be reviewed and adjusted, it can assist the administrator, for example, by presenting the coagulation conditions to be adjusted on the screen of a PC.

[0087] For example, the hue target value γ based on operation results SVWhen time for accumulating data is required to obtain [something], according to the operation management device of the present embodiment, even in a situation where the target value γ SV cannot be set, it is possible to determine the suitability or unsuitability of the flocculation conditions and assist the administrator.

[0088] That is, according to the present embodiment, the same effects as those of the above-described first embodiment can be obtained, and an operation management device, an operation management method, and a computer program for assisting an administrator in setting appropriate flocculation conditions based on a value obtained by quantifying the properties of the flock can be provided.

[0089] The program according to the present embodiment may be transferred in a state stored in an electronic device, or may be transferred in a state not stored in the electronic device. In the latter case, the program may be transferred via a network, or may be transferred in a state stored in a storage medium. The storage medium is a non-temporary tangible medium. The storage medium is a computer-readable medium. The storage medium may be any medium that can store a program such as a CD-ROM or a memory card and is readable by a computer, regardless of its form.

[0090] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0091] 1... water well, 2... mixing tank, 3... floc formation tank, 4... sedimentation tank, 5... two-stage coagulation tank, 6... filtration tank, 7... water distribution tank, 8... raw water pH meter, 9... flow meter, 10... mixing tank pH meter, 11... sedimentation water turbidity meter, 12... flow control valve, 13... mixing tank agitator, 14A - 14C... floc formation tank agitators, 15... two-stage coagulation agitator, 16... raw water pH adjuster injector, 17... coagulant injector, 18... mixing tank pH adjuster injector, 19... two-stage coagulant injector, 20... two-stage coagulation pH adjuster injector, 21... optical device, 22... hue analysis unit, 23... appropriate value calculation unit, 24... coagulant injection rate calculation unit, 25... pH adjuster injection rate calculation unit, 26... agitation intensity calculation unit, 27... flow control calculation unit

Claims

1. An optical device that acquires image information of flocs collected from treated water after adding a flocculant in a water treatment process including a step of adding a flocculant to the water to be treated, a hue analysis unit that performs image analysis using the image information and calculates a hue index using the hue frequency obtained by the image analysis, and an appropriate value calculation unit that calculates an appropriate value of the flocculation conditions in the water treatment process based on the hue index. A driving management device comprising:

2. The appropriate value calculation unit calculates an appropriate value of the flocculation conditions so that the hue index follows a target value of the hue index set in advance. The operation management device according to claim 1.

3. The hue frequency includes a first peak and a second peak, and the hue index is a ratio between the frequency value at the first peak and the frequency value at the second peak. The operation management device according to claim 1.

4. The hue frequency includes a first peak and a second peak, and the hue index is a ratio between an integrated value of frequency values in a first region of the hue frequency including the first peak and an integrated value of frequency values in a second region of the hue frequency including the second peak, with the hue value between the first peak and the second peak of the hue frequency as a boundary. The operation management device according to claim 1.

5. The water treatment process includes a step of adjusting the raw water flow rate flowing into the water treatment process, a step of adding a pH adjuster to the water to be treated, and a step of stirring the water to be treated after adding the flocculant, and the flocculation conditions are at least any one of a flocculant injection rate, a pH adjuster injection rate, a raw water flow rate, and a stirring intensity. The operation management device according to claim 1.

6. The water treatment process further includes a two-stage flocculant injection step of injecting the flocculant into the water to be treated after the stirring step and a two-stage flocculation stirring step of stirring the water to be treated, and the flocculation conditions further include at least any one of a flocculant injection rate in the two-stage flocculant injection step and a stirring intensity in the two-stage flocculation stirring step. The operation management device according to claim 5.

7. The water treatment process includes a step of stirring the water to be treated in a mixing tank where the flocculant is added to the water to be treated, and a floc formation step of stirring the water to be treated in each of a plurality of tanks through which the water to be treated contained in a floc formation tank installed downstream of the mixing tank sequentially flows. The optical device acquires the image information of the plurality of flocs collected from each of the plurality of the mixing tank and the floc formation tanks, The hue analysis unit calculates a plurality of hue indexes using the hue frequencies obtained by the image analysis of each of the image information of the plurality of flocs, The appropriate value calculation unit determines whether or not the flocculation conditions should be adjusted according to the result of comparing the hue index corresponding to the floc collected from the mixing tank with the hue indexes corresponding to each of the flocs collected from the plurality of the floc formation tanks. The operation management device according to claim 1.

8. Acquire the image information of the flocs collected from the treated water after adding the flocculant in the water treatment process including the step of adding the flocculant to the water to be treated, Perform image analysis using the image information, calculate a hue index using the hue frequency obtained by the image analysis, An operation management method for calculating an appropriate value of the flocculation conditions in the water treatment process based on the hue index.

9. A computer program for causing a computer to execute the operation management method according to claim 8.

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