JP2014002050A - Aggregation state detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aggregation state detection device capable of detecting an aggregation state of treatment water in the process of water purification quickly and accurately.SOLUTION: An aggregation state detection device includes: an aggregation sedimentation separation means 100 which classifies flocks in aggregation sedimentation treatment water in which a coagulant containing aluminum is added by a grain size of the flock; an addition means which adds a reagent for measuring aluminum and a buffer solution to the classification treatment water acquired in the aggregation sedimentation separation means; a mixing means which mixes the classification treatment water; an absorbance meter which measures absorbance of a reaction liquid; and a conversion means which converts the absorbance of the reaction liquid measured by the absorbance meter into an aluminum concentration in the reaction liquid. The aggregation sedimentation separation means 100 is an inclined tube 100 in which a cylindrical tube provided with an inlet port 110 of the aggregation sedimentation treatment water at a lower part and an outlet port 120 of the classification treatment water at an upper part is installed being inclined with respect to the gravitational direction.

Description

  The present invention relates to an aggregation state detection device that detects an aggregation state of treated water during a water purification process.

  In the water purification plant, a flocculant is injected into the collected raw water to agglomerate turbid components in the raw water to form flocs, and a coagulation sedimentation process is performed in which the generated flocs are settled and separated in a sedimentation basin. The coagulated sediment treated water from which the floc has been settled and separated is introduced into a filtration basin, which is the next water purification facility, and filtered. When surface water such as rivers and lakes is used as raw water, the quality of the raw water fluctuates due to factors such as weather conditions and seasons, so an appropriate flocculant injection rate is required to obtain clean water below the set turbidity. (Or the flocculant injection amount) needs to be determined. That is, in the coagulation sedimentation treatment, the coagulant injection rate determined according to the raw water quality is important.

  In the flocculant injection control method, the flocculant injection rate is calculated according to a preset flocculant injection model formula from the measurement results of raw water quality (turbidity, alkalinity, pH, etc.), and the flocculant injection rate is calculated based on this flocculant injection rate. There is a feed-forward control that injects the agent. However, in the feedforward control, when the raw water quality changes and it becomes impossible to match the coagulant injection model formula created in the past, the coagulant injection amount becomes inappropriate. As a result, for example, when the flocculant becomes excessive, the amount of sludge discharged increases, and conversely, when the flocculant becomes insufficient, the turbidity at the sedimentation basin outlet becomes high and the turbidity is high. Is introduced into the filter basin, the problem arises that the frequency of backwashing of the filter basin increases.

  In contrast to feedforward control, there is feedback control that corrects the amount of flocculant injected based on the measurement result of turbidity at the sedimentation tank outlet. In feedback control, even if the raw water quality changes, the effect is measured as a change in turbidity at the outlet of the sedimentation basin. However, it takes about 3 to 4 hours until the result of injecting the flocculant into the raw water becomes turbidity at the sedimentation tank outlet, and a time delay occurs in correcting the flocculant injection amount.

  Since feedforward control and feedback control have their respective disadvantages, combining each control method, first calculate the basic flocculant injection rate from the raw water quality, and correct the calculated value using the turbidity at the sedimentation tank outlet There is feed-forward feedback control. The feedforward / feedback control can maintain the amount of the flocculant injected appropriately because the feedback works even when the consistency of the coagulant injection model equation cannot be obtained as compared with the feedforward control. However, since the time delay, which is a problem of feedback control, has not been solved, it is difficult to cope with unsteady times when the raw water quality changes rapidly.

  Therefore, in order to shorten the time delay, a flocculant injection control method using a floc having a small particle diameter after injection of the flocculant (micro floc) as an index has been proposed. In this control method, the raw water into which the flocculant has been injected is collected at an earlier stage than the conventional sedimentation basin outlet, thereby shortening the feedback correction time delay, and even if the raw water quality changes, the flocculant is injected at an early stage. The rate can be corrected.

  If a lot of micro flocs are formed in the raw water into which the flocculant has been injected, the subsequent floc growth slows down, resulting in high turbidity at the sedimentation tank outlet. Therefore, the state of aggregation in the sample water can be detected by classifying the minute flocs by a classifying means such as a filter and measuring the amount thereof. By using the detection result of the aggregation state, it is possible to correct the flocculant injection rate with high accuracy. Here, the minute floc can be quantified by measuring the aluminum concentration of the solid component.

Examples of the method for measuring the aluminum concentration in the sample water include atomic absorption spectrophotometry, ICP emission spectroscopic analysis, ICP mass spectrometry, and spectrophotometry. Among these, as a spectrophotometric method, there is a method of using eriochrome cyanine red (C ₂₃ H ₁₅ Na ₃ O ₉ S, hereinafter referred to as ECR) as a color reagent. This is one in which a soluble aluminum causes a color reaction with an ECR reagent in the region of pH 4.6 to 5.6 to form a complex, and its absorbance is determined and quantified.

  As a method for measuring the aluminum concentration using an ECR reagent, for example, Patent Document 1 discloses a metal ion concentration measuring device capable of adjusting the temperature of sample water. Patent Document 2 discloses an aluminum automatic measuring apparatus capable of measuring aluminum in a flock.

JP 2008-096396 A JP 2012-047657 A

  Since the techniques described in Patent Documents 1 and 2 are not particularly focused on micro flocs in water purification plants, even if the aluminum concentration is measured by the method described in Patent Documents 1 and 2, the aggregation state of the sample water There is a problem that it may not be able to be detected accurately. In addition, as a means for classifying floc in sample water, there are filters, hydrocyclones, sedimentation separators, flotation separators, etc., but with these methods, the measurement accuracy decreases or the water purification plant There is a problem that the operation cost and installation cost of the system become high.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a coagulation state detection device that can quickly and accurately detect the coagulation state of treated water during a water purification process.

  In order to solve the above-described problems and achieve the object, the aggregate state detection device according to the present invention is a coagulation precipitate that classifies flocs in coagulation sedimentation treated water to which an aggregating agent containing aluminum is added, according to the particle size of the flocs. Separation means, addition means for adding an aluminum measuring reagent and a buffer to the classified water obtained by the coagulation sediment separation means, mixing for mixing the classified water, the aluminum measuring reagent and the buffer Means, an absorptiometer for measuring the absorbance of the reaction liquid mixed by the mixing means, and a conversion means for converting the absorbance of the reaction liquid measured by the absorptiometer into an aluminum concentration in the reaction liquid. The coagulation sediment separation means comprises a cylindrical tube provided with an inlet for the coagulated sediment treated water at the lower part and an outlet for the classified treated water at the upper part, Characterized in that an inclined tube installed inclined with respect to the direction of force.

  ADVANTAGE OF THE INVENTION According to this invention, the aggregation state detection apparatus which can detect the aggregation state of the treated water in a water purification process rapidly and correctly can be provided.

It is explanatory drawing which shows the structure of the aggregation state detection apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the inclination pipe | tube which concerns on embodiment of this invention. It is a graph which shows the component of the classification treated water classified by the inclination pipe. It is sectional drawing of the inclination pipe | tube (3rd modification) which concerns on embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

≪Aggregation state detection device≫
FIG. 1 is an explanatory diagram illustrating a configuration of an aggregation state detection device according to an embodiment of the present invention.
The aggregation state detection apparatus 10 includes an inclined pipe 100, a pump 200 (200a to 200g), a valve 300 (300a to 300h), a heater 400, a tank 500 (500a to 500c), a reaction tank 600, a water level sensor 700, a stirring means 800, It comprises an absorbance meter 900 and data recording means 1000.
The aggregation state detection device 10 detects the aggregation state of turbidity in the water purification process. Here, the flocculation state is the magnitude of the turbidity of the coagulation sedimentation treatment water at the outlet of the sedimentation basin. In the case of poor aggregation, the turbidity of the coagulation sedimentation treatment water becomes large.

  In the claims, the coagulating sediment separation means (inclined pipe) is the inclined pipe 100, the adding means is the pumps 200c and 200d, the valves 300c and 300d and the control means (not shown), the mixing means is the reaction tank 600 and the stirring means. 800, the absorbance meter corresponds to the absorbance meter 900, and the conversion means corresponds to the data recording means 1000, respectively.

  The coagulation sedimentation treatment water into which the coagulant (more specifically, the coagulant containing aluminum) is injected in the water purification treatment is supplied to the inclined pipe 100 by the classification treatment water pump 200a. Here, the classified water pump 200a may be any means that can be continuously supplied at a constant flow rate, such as a tubing pump or a plunger pump. In addition, the water sampled by the classified treated water pump 200a may be anywhere from the time when the flocculant is injected into the treated water in the water purification treatment to the outlet of the settling basin. It is desirable to collect water at the inlet (mixing basin outlet) side of the mixing basin or floc formation pond where water is injected and mixed.

<Inclined pipe>
FIG. 2 is a cross-sectional view showing the configuration of the inclined tube.
The inclined tube 100 is formed by inclining a cylindrical tube provided with an inlet 110 for the coagulated sediment treated water at the lower part and an outlet 120 for the classified treated water at the upper part by a predetermined angle θ with respect to the horizontal plane Ho. Installed. In other words, the inclined tube 100 is installed inclined with respect to the direction of gravity.
When the coagulated sediment treated water that has flowed in from the inlet 110 passes through the inclined tube 100, coarse flocs in the coagulated sediment treated water settle and deposit in the inclined tube 100. And the classification process water containing many micro flocs is obtained from the outflow port 120. FIG. The outlet 120 is a bottom surface B of the inclined tube 100 inclined obliquely with respect to the ground (the horizontal surface Ho in the case where the cylindrical portion of the inclined tube 100 is divided into two on the side close to the horizontal surface Ho and the side far from the horizontal surface Ho. It is desirable to attach to the top side T (the side far from the horizontal plane Ho), not the side close to the side. This is because the floc accumulated in the inclined pipe 100 does not flow out from the outlet 120. On the other hand, the inflow port 110 may be provided on either the top side T or the bottom side B.

  Moreover, since coarse flocs accumulate on the bottom of the inclined pipe 100 as time elapses, the inclined pipe valve 300a is periodically opened by a control means (not shown), and drainage including coarse floc is discharged from the discharge port 130. To do. The drainage may be drained with a normal drainage facility or may be returned to the sampling position.

  Generally, the particle size of flocs present in the coagulation sedimentation treated water varies from 1 to 100 μm. The flocs with poor sedimentation are small flocs having a particle size of 50 μm or less, particularly 15 μm or less. Therefore, the inclined tube 100 needs to have dimensions and operating conditions that can classify small flocs having a particle size of 50 μm or less, desirably 5 μm to 15 μm, and having a predetermined particle size or less.

  Next, an example of a method for determining the dimensions and operating conditions of the inclined pipe 100 for detecting the aggregation state of the water purification plant will be described. First, it is desirable that the quality of the classified treated water for measuring the aluminum concentration satisfies the following conditions. That is, when the flocculation treatment water is not sufficiently classified and the amount of floc (turbidity) contained in the classification treatment water is high, the floc adversely affects the measurement of absorbance. Therefore, the turbidity of the classified treated water is desirably 20 degrees or less. Moreover, the aluminum concentration of the classification treated water needs to be in a range that can be measured by an absorptiometry using an ECR reagent, and is desirably about 0.3 mg / L.

  Moreover, as for the flow volume of the classification treated water pump 200a for supplying classified treatment water to the aggregation state detection apparatus 10, it is desirable that an amount necessary for aluminum measurement can be supplied within at least one minute. Further, the supply amount of the classified treated water to the reaction tank 600 may be more than the amount necessary for the absorbance measurement with the absorbance meter 900, but is desirably 100 mL or less in order to reduce the necessary reagent amount.

  From this, the dimension of the inclined pipe 100 capable of classifying flocs having a particle size of 15 μm or less is determined by setting the supply amount of the classified treated water to the reaction tank 600 to 50 mL and the flow rate of the classified treated water pump 200a to 100 mL / min.

In order to settle the flocs, it is desirable to use a laminar flow of the coagulation sedimentation treated water in the inclined pipe 100. Here, when the inclined tube 100 has a simple circular tube shape as shown in FIG. 2, the Reynolds number: Ref of the fluid can be obtained by the following equation (1). In the following formula (1), D: inner diameter of the inclined tube, u: average flow velocity, μ: water viscosity, ρ: water density.
Ref = uDρ / μ (1)

Further, the average flow velocity u in the inclined pipe can be obtained by the following formula (2). In the following formula (2), M is a flow rate.
^{u = M / (πD 2/} 4) ··· (2)

Substituting equation (2) into equation (1) and considering the laminar flow condition: Ref <2300, the following equation (3) can be obtained.
D> (4Mρ) / (2300πμ) (3)

From the above conditions, if M = 100 mL / min, μ = 0.001 Pa · s, ρ = 1000 kg / m ³ , D> 9.2 × 10 ⁻¹ mm, that is, the inner diameter (diameter) of the inclined tube 100 is If it is 9.2 × 10 ⁻¹ mm or more, the flow of the coagulation sedimentation treated water can be a laminar flow. That is, the minimum inner diameter of the inclined tube 100 can be obtained by using the equation (3).

  Further, the inclined tube 100 is installed with a predetermined angle: θ with respect to the horizontal plane H (ground). In order to settle the floc, the terminal sedimentation speed of the floc may be increased with respect to the rising speed of the coagulation sedimentation treated water. When the inclined tube 100 is level with respect to the ground (θ = 0 degrees), the water rising speed is 0, which is convenient for the floc settling, but coarse floc accumulates on the inclined tube wall and is used for a long time. Then, there is a possibility of blocking the inclined pipeline. In order to deposit coarse floc on the bottom of the inclined tube and periodically discharge it, it is desirable that θ = 45 to 75 degrees.

The end sedimentation velocity (v) of floc can be obtained from the Stokes equation (the following equation (4)) if the Reynolds number (Res) of the particles is 0.5 or less. In the following formula (4), d: particle diameter of flock, g: acceleration of gravity (= 9.8 m / s ² ), ρs: density of flock (2000 kg / m ³ ).
v = {g (ρs−ρ) d ² } / (18 μ) (4)

Further, the Reynolds number (Res) of the particles can be obtained from the following formula (5). In the following formula (5), u ′ is the rising speed (usin θ) of the coagulated sediment treated water.
0.5> Res = {(v + u ′) dρ} / μ (5)

  Using the equations (4) and (5), when D = 25 mm, θ = 60 degrees, and d = 15 μm, v = 0.12 mm / s and Res = 0.045.

The flocs are removed from the water if they sink a distance H from the top side T to the bottom side B of the inclined tube in the direction perpendicular to the ground (horizontal plane Ho), that is, do not flow out from the outlet 120. In the case of D = 25 mm and θ = 60 degrees, H = D / cos θ = 50 mm, and the required residence time (τ) is τ = H / v = 420 s. From the following equation (6), the inclined tube length: L = 1 .4 m can be obtained. The inclined tube length L here is a distance that the coagulated sediment treated water moves in the inclined tube 100 and is a distance from the inlet 110 to the outlet 120.
^{L = Mτ / (πD 2/} 4) ··· (6)

Here, by substituting τ = H / v, H = D / cos θ, and the equation (4) into the equation (6), as shown in the following equation (7), D: the inner diameter of the inclined pipe, L: length of inclined tube :, θ: angle of inclined tube with respect to horizontal plane, M: flow rate (flow rate of coagulated sediment treated water to inclined tube), d: particle size of floc, ρs: density of floc Can lead.
In addition, d of following formula (7) shows the maximum particle diameter of the floc in the classification process water which flows out out of the outflow port of an inclined pipe in detail. That is, according to the following equation (7), it is possible to determine what value should be set for each condition when classifying flocs smaller than the particle diameter d.
L = 72 Mμ / {g (ρs−ρ) d ² · cos θπD} (7)
In addition, said Formula (7) respond | corresponds to Formula (1) of a claim.

  The dimensions of the inclined tube 100 are desirably determined in accordance with the operating conditions based on the equations (1) to (6) or the equation (7). In addition, the inclined tube 100 may have another shape such as a rectangle instead of a circular tube shape.

  FIG. 3 is a graph showing components and turbidity of classified treated water classified by an inclined tube. In detail, the graph of FIG. 3 may be generated in an actual water treatment plant using the inclined pipe 100 having an inclined pipe diameter: D = 25 mm, an angle: θ = 60 degrees, and a length: L = 1 m. It is the result of classifying the coagulation precipitation treated water (turbidity of 300 degrees, polyaluminum chloride (PAC) 100 mg / L) under certain high turbidity conditions. In FIG. 3, the horizontal axis represents the residence time of the coagulated sediment treated water in the inclined tube 100, the right horizontal axis represents the turbidity of the classified treated water, and the left horizontal axis represents the aluminum concentration of the classified treated water.

  In the graph of FIG. 3, the aluminum concentration and the classification water turbidity are lowered as the residence time in the inclined tube 100 is longer. From this, by making the residence time in the inclined pipe 100 longer, it is possible to reduce the aluminum concentration and the classification treatment water turbidity, and to make it a desirable condition for judging the aggregation state. In addition, after determining the dimension of the inclined tube 100, it is desirable to confirm performance with the coagulation sedimentation treatment water of high turbidity conditions.

<Configuration other than inclined pipe and processing method after inclined pipe>
Returning to the description of FIG. 1, first, the classified water obtained by passing through the inclined tube 100 is heated by passing through the heater 400. By heating the classified water, the dissolution of the solid aluminum compound by the acid and the color reaction are promoted. Here, as heating temperature, 20-60 degreeC is desirable.

  The classified water heated by the heater 400 is supplied to the reaction tank 600. The supply of classified treated water is controlled by a signal output from a water level sensor 700 installed in the reaction tank 600. For example, when a predetermined amount of classified treated water is supplied and a signal is output from the water level sensor 700, a control means (not shown) controls the classified treated water valve 300b, and the classified treated water is discharged as discharged water instead of the reaction tank 600. Switch to The supply of the classification treated water to the reaction tank 600 may be other than the above method as long as it can be controlled by a predetermined amount.

  Moreover, the hot water heated with the heater 400 circulates around the reaction tank 600 by the circulation pump 200b, and the reaction tank 600 is kept at a constant temperature. Here, the circulation pump 200b may be any means that can be continuously supplied at a constant flow rate, such as a tubing pump or a plunger pump, like the classified water pump 200a. Note that heating by the heater 400 may be performed only in either the classified water or the reaction tank 600.

  After a predetermined amount of classified water is supplied to the reaction tank 600, the ECR solution is supplied to the reaction tank 600 from the ECR solution tank 500a by the action of the ECR solution pump 200c. Here, the ECR solution pump 200c may be a tubing pump or a plunger pump, but has a function of stopping when a certain amount of ECR solution is supplied to the reaction vessel 600 by a control means (not shown). The ECR solution valve 300c has a function of opening when the ECR solution pump 200c is operated by a control means (not shown) and closing it when stopped.

  The ECR solution is prepared by adding a predetermined amount of ECR reagent to a solvent. Here, in the ECR solution, the constituent material changes to a reduced chemical species over time and discolors, so it is necessary to adjust the pH to 2.0 or less to prevent discoloration. Therefore, an acidic liquid such as hydrochloric acid can be used as the solvent. Further, the ECR solution has a role of dissolving aluminum as a solid component contained in the floc in addition to forming a complex with aluminum in the classified water. Therefore, when the ECR solution is added to the classification treated water, the pH and the addition rate of the ECR solution are determined so that the pH of the solid component aluminum can be dissolved.

  The concentration of the ECR reagent is set so that the absorbance is within the measurement range of the absorptiometer when the required aluminum concentration is reached. The concentration of the ECR reagent is 0.01 to 0.20 mg / mL, preferably 0.025 to 0.10 mg / mL after addition to the classified water. At this time, the quantitative range of the aluminum concentration is 0 to 0.5 mg / L, preferably 0 to 0.3 mg / L. In this range, the ECR is obtained so that a linear relationship is obtained between the absorbance and the aluminum concentration. Adjust the amount of reagent added.

  The ECR solution has a pH of 1.9, and the pH of the classified water is about 3 when added to the classified water by about 10%. If the pH is 4 or less, the aluminum compound in the floc can be dissolved. The pH of the ECR solution is 2 or less, preferably 1 to 2 in terms of preventing deterioration and dissolving the aluminum compound.

  The classified water and the ECR solution are stirred and mixed in the reaction vessel 600. Here, as the stirring means 800, any means capable of obtaining good stirring may be used, and examples thereof include a means using a stirrer and a magnetic stirrer. At this time, the residence time is within 5 minutes, preferably 1 to 3 minutes.

  After stirring and mixing the classified water and the ECR solution, a buffer solution is supplied to the reaction tank 600 from the buffer solution tank 500b using the buffer solution pump 200d. Here, similarly to the ECR solution pump 200c, the buffer solution pump 200d has a function of stopping when a certain amount of buffer solution is supplied to the reaction tank 600 by a control means (not shown). The buffer valve 300d has a function of opening when the buffer pump 200d is operated by a control means (not shown) and closing when the buffer pump 200d is stopped. The agitation / mixing operation is the same as that when the classified water and the ECR solution are agitated / mixed.

  The purpose of adding the buffer solution is to make the pH range from 4.6 to 5.6 in which aluminum reacts with the ECR reagent to form a complex. Therefore, the pH of the buffer solution is determined in the range of 4.6 to 5.6. Moreover, it is necessary to determine the concentration and addition rate of the buffer so that the pH of the classified water after the addition of the ECR solution falls within the range of 4.6 to 5.6. Although it is important that the buffer solution has a predetermined pH range, it is desirable that the buffer solution is not subject to PRTR (Pollutant Release and Transfer Register) target substances, for example, acetic acid and An acetate buffer mixed with a sodium acetate solution may be used.

  The concentration of the acetate buffer is 0.2 to 5 mol / L, preferably 0.5 to 3 mol / L, in order to make the pH range in which aluminum reacts with ECR and forms a complex. After the addition of this acetate buffer, the addition amount is adjusted so that the pH of the classified water becomes 4.6 to 5.6. For example, the molar amount of the acetate buffer (concentration of acetate buffer × added amount) is 2 to 4 mol / L, preferably 3 to 3.5 mol / L with respect to the added amount of the ECR solution at pH 1.9.

  The reaction solution obtained by stirring and mixing the classified water, the ECR solution, and the buffer solution is supplied to the absorbance meter 900 by the reaction solution pump 200e. Here, similarly to the ECR solution pump 200c or the buffer solution pump 200d, the reaction solution pump 200e has a function of stopping when a certain amount of reaction solution is supplied to the absorbance meter 900 by a control means (not shown). Further, the reaction liquid valve 300e has a function of opening when the reaction liquid pump 200e is operated by a control means (not shown) and closing it when stopped.

  The absorbance meter 900 measures the absorbance of the reaction solution. Here, although the cell used for the measurement of absorbance is influenced by the amount of the reaction solution and the measurement accuracy, a cell having a commercially available size of 1 to 5 cm is desirable. The measurement wavelength needs to be determined from the range showing high absorbance. In the spectrophotometric method using an ECR reagent, the measurement wavelength is 490 to 550 nm, preferably 515 to 535 nm.

  The absorbance measured by the absorbance meter 900 is recorded by the data recording means 1000. The data recording means 1000 converts the absorbance value measured by the absorbance meter 900 into an aluminum concentration value. For this conversion, a calibration curve of absorbance-aluminum concentration prepared in advance is used. The conversion of the absorbance value into the aluminum concentration value may be performed in the data recording unit 1000 or may be performed using a data conversion unit (not shown). The aluminum concentration recorded in the data recording means 1000 is monitored by a water purification plant control device (not shown) or the like and used for correcting the flocculant injection rate.

  After measuring the absorbance of the reaction solution, the reaction solution in the absorbance meter 900 is discharged by opening the reaction tank valve 300f. The reaction tank valve 300f is opened by control means (not shown). Since the reaction solution is a weakly acidic solution having a pH of about 5, it is neutralized or diluted and drained with ordinary drainage equipment.

  Pure water as cleaning water is supplied to the reaction tank 600 by a pure water pump 200f. The pure water valve 300g has a function of opening when the pure water pump 200f is operated by a control means (not shown) and closing when the pure water pump 200f is stopped. Here, the pure water has a role of cleaning the reaction tank 600. At this time, the reaction pump 600e and the reaction valve 300e are operated by a control unit (not shown), so that the absorptiometer 900 is cleaned simultaneously with the reaction tank 600. Further, the zero point of the absorbance meter 900 is adjusted periodically. The calibration curve is updated when the zero point is adjusted.

  Further, if the reaction vessel 600 and the absorbance meter 900 are continuously used, it becomes difficult to remove the dirt and the attached dirt only by washing with pure water. Therefore, the cleaning liquid pump 200g and the cleaning liquid valve 300h are periodically controlled, and the cleaning liquid is supplied from the cleaning liquid tank 500c to the reaction tank 600. Here, any cleaning solution may be used as long as it can return the reaction tank 600 to a clean state, such as an acid. At this time, by operating the reaction liquid pump 200e and the reaction liquid valve 300e by a control means (not shown), the absorbance meter 900 is also cleaned simultaneously with the reaction tank 600.

  Aggregation state detection apparatus 10 repeats the same operation, and measures the aluminum concentration at regular intervals by a control means (not shown). When the operating condition of the aggregation state detection device 10 is determined once, it is desirable not to change it as much as possible.

  As described above, according to the aggregated state detection device 10 according to the embodiment, by obtaining classified treated water containing a large amount of micro flocs by the inclined tube 100, the micro flocs can be accurately quantified. Aggregation during the process can be detected quickly. Further, even when the coagulation sedimentation treated water has high turbidity, the absorbance can be stably measured by removing coarse flocs with the inclined tube 100.

  In addition, the inclined pipe 100 has a simple apparatus structure compared to other classification means such as a filter, so that maintenance is easy, it is possible to easily maintain accuracy, and the operation cost of the water purification plant is reduced. Can do. In addition, since the inclined pipe 100 is less expensive than other classification means such as a filter, the installation cost of the water purification plant can be reduced.

Below, the modification of the aggregation state detection apparatus 10 which concerns on embodiment of this invention is shown.
<< First Modification >>
In the first modified example, not only the classification treated water but also a certain amount of pure water (dilution water) is supplied to the reaction tank 600 to dilute the classified treated water. This is because flocs contained in the classification treated water have an influence on the absorbance measurement when the coagulated sediment treated water has high turbidity, and the influence of the floc is reduced by diluting the classified treated water. Is possible.

  In the first modification, after supplying a certain amount of classified water to the reaction tank 600 in the same manner as in the above-described embodiment, the pure water pump 200f is operated to supply a certain amount of pure water. Dilute. Thereafter, the ECR solution and the buffer solution are mixed and the absorbance is measured in the same manner as in the above-described embodiment. According to the first modification, compared with the case where the classified water is not diluted, it is possible to cope with the coagulated sediment treated water under the high turbidity condition.

<< Second Modification >>
In the second modification, a part of the classified treatment water supplied to the reaction vessel 600 is supplied to the absorptiometer 900 before adding the ECR solution, and the absorbance is measured, so that the influence of floc on the measurement, etc. Is to be removed. Specifically, before adding the ECR solution to the classified treated water, the classified treated water is supplied to the absorbance meter 900 and the absorbance: I ₀ is measured. Then added ECR solutions and buffers in the classification treatment water, the absorbance of the reaction solution was stirred and mixed: measuring the I _1.

From this I ₀ and I ₁ , the absorbance: I _{2 from} which the influence of floc and the like is removed can be obtained by the following formula (8). That is, the absorbance of the classified water after the addition of the aluminum measuring reagent and the buffer solution can be corrected based on the absorbance of the classified water before the addition of the aluminum measuring reagent and the buffer solution. In the following formula (8), α and β are values obtained by confirming the influence of floc and the like in advance. Also, the following formula (8) is not limited to the following description, and any formula may be used as long as the influence of floc and the like can be removed.
I ₂ = I ₁ −αI ₀ ^β (8)

  Compared with the case where only the absorbance of the classified water after the addition of the reagent for aluminum measurement and the buffer solution is measured, this second modification eliminates the influence of floc on the measurement and is highly accurate. Aluminum concentration can be measured.

<< Third Modification >>
In the third modified example, the heating time of the classified water is increased by heating around the inclined tube.
FIG. 4 is a cross-sectional view of an inclined pipe (third modification) according to the embodiment of the present invention. The inclined pipe 100 ′ shown in FIG. 4 is a double pipe, and the coagulation sedimentation treated water (classified treated water) flows through the inner pipe portion 150 in the same manner as the inclined pipe 100 of FIG. On the other hand, warm water heated by the heater 400 passes through the outer pipe portion 151. Thereby, the coagulation sedimentation processing water (classification processing water) which flows the inner pipe part 150 can be heated. Therefore, in the third modification, the heating time of the classified treated water can be increased, and the dissolution and color reaction of the solid component aluminum compound by the acid can be further promoted.
Note that the heating means in the claims corresponds to the outer tube portion 151.

DESCRIPTION OF SYMBOLS 10 Aggregation state detection apparatus 100 Inclined pipe 110 Inlet 120 Outlet 130 Outlet 150 Inner pipe part (inclined pipe)
151 Outer tube (heating means)
200 (200a to 200g) Pump 300 (300a to 300h) Valve 400 Heater 500 (500a to 500c) Tank 600 Reaction tank 700 Water level sensor 800 Stirring means 900 Absorbance meter 1000 Data recording means

Claims (9)

A coagulation sediment separation means for classifying flocs in the coagulation sedimentation treated water to which a coagulant containing aluminum is added, according to the particle size of the flocs;
An adding means for adding a reagent for measuring aluminum and a buffer solution to the classification treated water obtained by the coagulation sediment separation means;
A mixing means for mixing the classified water, the aluminum measuring reagent, and the buffer;
An absorptiometer for measuring the absorbance of the reaction solution mixed by the mixing means;
Conversion means for converting the absorbance of the reaction solution measured by the absorptiometer into an aluminum concentration in the reaction solution,
The coagulation sediment separation means is provided with a cylindrical pipe provided with an inlet for the coagulated sediment treated water at the lower part and an outlet for the classified treated water at the upper part, and is inclined with respect to the direction of gravity. An agglomeration state detection device characterized by being an inclined tube.   The inner diameter (D) of the inclined tube, the length (L) of the inclined tube, the angle (θ) with respect to the horizontal plane of the inclined tube, and the supply flow rate (M) of the coagulated sediment treated water to the inclined tube The aggregation state detection device according to claim 1, wherein the aggregation state detection device is determined based on a maximum particle diameter (d) of the floc in the classified treated water flowing out from an outlet of the pipe and a density (ρs) of the floc. . 3. The aggregation state detection device according to claim 2, wherein when the D, the L, the θ, and the M are determined based on the d and the ρs, the following expression (1) is satisfied. .
L = 72 Mμ / {g (ρs−ρ) d ² · cos θπD} (1)
(In the above formula (1), μ is the viscosity of water, g is the acceleration of gravity, and ρ is the density of water)   The aggregation state detection device according to any one of claims 1 to 3, wherein a particle diameter of the floc in the classification treated water flowing out from the outlet of the inclined pipe is 50 µm or less.   The aggregation state detection device according to any one of claims 1 to 3, wherein a particle diameter of the floc in the classification treated water flowing out from the outlet of the inclined pipe is 5 to 15 µm.   The aggregation state detection device according to any one of claims 1 to 3, further comprising a heater that heats the classified water that is mixed by the mixing unit. The adding means further adds dilution water to the classified water.
The mixing means mixes the classified water, the dilution water, the aluminum measuring reagent, and the buffer solution,
The aggregation state detection device according to any one of claims 1 to 3, wherein the absorptiometer measures the absorbance of the reaction solution mixed with the dilution water. The absorbance meter further measures the absorbance of the classified water before the aluminum measurement reagent and the buffer are added,
The conversion means is configured to determine the classified treated water after the addition of the aluminum measuring reagent and the buffer solution based on the absorbance of the classified treatment water before the addition of the aluminum measuring reagent and the buffer solution. The agglutination state detection device according to any one of claims 1 to 3, wherein the absorbance is corrected.   The aggregation state detection apparatus according to any one of claims 1 to 3, further comprising heating means for the inclined tube.

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