JPS61111109A - Flocculation controller - Google Patents

Abstract

PURPOSE:To form flocs having an excellent settling property with the minimum amt. of a flocculant to be injected by always measuring the density of flocs, and operating the amt. of the flocculant to be injected. CONSTITUTION:A camera device 100for transducing the brightness signal of the image of a floc 34 into an electric signal is arranged in a flocculation pond 30. Picture processing of the floc 34 is carried out in a picture processing device 110 and the grain diameter distribution Fd of the flocs 34 are calculated. Besides, the total volume Vt of the floc is calculated in an arithmetic unit 210 from said grain diameter Fd. Furthermore, the mean density rho of the floc is calculated inan arithmetic unit 220 of the floc density from the total weight M of the influent turbid materials and the total volume Vt of the floc. Besides, the amt. A of a flocculant to be injected is calculated by receiving the signal of said floc density rho in an arithmetic unit 200 of the amt. of the flocculant to be inject ed. The amt. of the flocculant to be injected is controlled by a flocculant injec tor 22 receiving the signal of the amt. A of the flocculant to be injected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for floc formation in a floc formation pond (mixing pond) of a water purification plant.

[Background of the Invention In Ko water purification plants, turbid substances in raw water are coagulated to form flocs, and these flocs are allowed to settle. For this reason, it is essential to monitor flocs in the floc formation pond (mixing pond).

Conventionally, in order to appropriately control the amount of coagulant injected, a method has been known in which the turbidity, particle size, and surface area of raw water suspension are measured and the coagulant is injected (Japanese Patent Publication No. 59-29281). However, the quality of floc formation is not determined only by the surface area of the flocculant and raw water suspension, but is also affected by temperature and agitation, so even if conventional techniques are applied, it may not actually be possible to form flocs. Ta.

For example, if the temperature is low or the stirring is not appropriate, flocculation cannot be achieved properly. For this reason, there was a problem in that the suspended particles that did not become flocs did not settle in the sedimentation basin and clogged the J suitable area.

Previously, water treatment plant maintenance managers visually monitored flocs several times a day to determine whether the amount of coagulant injected was appropriate. Because it relies on visual inspection, it is not possible to measure the density of flocs even though it is possible to qualitatively determine the size of the flocs. For this reason, it was not possible to know whether or not good flocs were formed that were easy to settle in the sedimentation basin.

On the other hand, recently, industrial television cameras (ITVs) have been used to monitor flocs in floc formation ponds.
As described in Japanese Patent Application No. 143296, a method has also been devised for monitoring the shape and size of flocs by extracting electrical signals according to the shape of flocs using a photoelectric conversion device.

However, the larger the particle size of the flocs is, the better. Therefore, even if the particle size and shape of the flocs are recognized based on known technology, it is not possible to form the flocs optimally. Even if the filter is large, if the density is low, the sedimentation speed in the sedimentation basin will be slow, and in addition, micro flocs will be left behind during the sedimentation process, and the micro flocs will flow into the filtration basin and become a load. On the other hand, even if the density of flocs is high, if the particle size is small, the flocs will be difficult to settle in the sedimentation basin, which will still cause a load on the filtration basin. As described above, there is a drawback that it is not possible to form flocs satisfactorily by simply knowing the particle size of the flocs based on known techniques.

[Object of the invention] The object of the present invention is to provide a floc formation control device that can form flocs with good sedimentation properties at a minimum coagulant injection rate when forming flocs in a floc formation pond (mixing pond) of a water treatment plant. It is about providing.

[Summary of the Invention] Although a method for determining the particle size by image processing flocs is known, there has been no concept of measuring the density of flocs.

The present invention applies turbidity measurement technology and image processing technology to measure floc density, calculates floc density based on these measured values, and controls floc formation status by %N based on this calculated density value. It is characterized by forming good flocs.

An outline of this will be explained below. The particle size of the flocs is determined using an industrial television camera and image processing, and the volume V of the flocs is calculated. Meanwhile, the turbidity of the raw water is measured using a turbidity meter. Turbidity is the weight of turbidity, correlation, ah. 1. Turbidity force, et al. 70. ,, (7) Weight Weight M can be determined. Therefore, the floc density ρ is M/V
It can be calculated by

If the floc density ρ is small, it indicates that the flocculant is being injected excessively, so the flocculant injection rate is reduced. Conversely, if the density ρ of the flocs is large, it indicates that the flocculant is insufficient, so the flocculant injection rate is increased. In this way, the flocculant injection rate and paddle rotation speed are controlled so that optimal flocs are formed.

[Embodiment of the Invention] An embodiment of the present invention is shown in FIG. 1. In FIG. 1, a turbidity meter 11 measures the turbidity of a landing well 10. This turbidity meter value T
u is input to the floc weight calculation device 230. The floc weight calculation device 1230 calculates the total weight M of the inflowing suspended solids from the turbidity measurement value Tu. The total weight signal M is sent to the floc density calculation device i! 220.

The rapid mixing pond 20 is provided with an agitator 21 . A flocculant is injected into the rapid mixing pond 20 from a flocculant injector 22 . There are three stirring paddles 31A in the floc formation pond 30.
, 31B, and 31G are provided, and these stirring paddles 31A, 31B.

31C are stirring motors 32A and 32B, respectively.

Rotationally driven by 32G. Stirring paddle 3IA,
31B and 31C are partitioned by rectifying walls 33A and 33B.

The fine flocs flowing into the flocculation pond 3o from the rapid mixing basin 20 flow down the flocculation basin 30 one after another and are sequentially stirred by the stirring paddles 31A, 31B, 31G. *While the small flocs flow down in the floc formation pond 30, the floc density collides and coalesces to form a large floc 34. In this manner, the particle size of the flocs gradually increases while passing through the floc formation pond 30.

The floc formation pond 30 has an imaging bag that converts the luminance signal of the image of the floc 34 into an electrical signal! ! 100 are arranged. Imaging device! 100 is industrial/TV camera ITV
The image processing device 110 including the image processing device 110 performs image processing of the flock 34 based on the electric signal obtained by the imaging bag m1oo, and calculates the particle size arrangement and particle size distribution Fd. Arithmetic device 21
0 is an image processing bag! The total volume Vt of the floc is calculated from the particle size distribution Fd calculated in step 110. The total floc volume Vt calculated by the floc volume calculation device 210 is input to the floc density calculation device T11220.

The floc density calculation device 220 calculates the total weight M of the inflowing suspended solids.
The average density ρ of the flocs is calculated from the total floc volume Vt by the following formula.

ρ=M/Vt......Φ・(1) The flocculant injection amount calculation device 200 is a floc density calculation device! 220
The flocculant injection amount A is calculated based on the signal of the floc density ρ calculated in . The flocculant injection machine 22 receives the signal of the flocculant injection amount A and operates the flocculant injection amount.

The flocs 34 formed in the floc formation basin 3o flow into the settling basin 40 and are settled and removed. The supernatant water from which the flocs 34 have been removed flows into the filter basin 50. In 50 suitable lands,
The remaining minute flocs that were not removed in the settling tank 40 are filtered out and removed. The water that has passed through the filter pond 50 is supplied to consumers via a drainage pond (not shown), a reservoir (not shown), and the like.

FIG. 2 shows a detailed diagram of an example of the imaging device 100 and the image processing device 110. IT fixed in airtight container 120
V130 uses close-up lens 131.
An image of the flocs 34 in the floc formation pond 30 is enlarged and recognized through an Ill observation window 121 made of transparent material such as glass. The wiper 122 driven by the wiper drive unit W1123 is operated periodically to remove dirt from the surfaces of the observation window 121 and the pack screen 124.

The back screen 124 is provided to recognize flocks with high contrast and accuracy, and is airtight.
Back screen fixture 124A fixed to container 120
and 124B are installed in front of the 1llI observation window 121. The back screen 124 is preferably a dark color in order to accurately recognize white flocks with high contrast.

The light-shielding cover 142 is where the ITV 130 is placed.

The lamp 140 is provided to darken the surrounding area and maintain a constant illuminance due to only the lamp 140. By providing the light-shielding cover 142, the image of the flock group will not be affected by changes in surrounding illuminance. A plurality of lamps 140 are installed, and irradiate the flocks 34 from many sides. In addition, in FIG. 2, an illuminance controller 141 is provided to maintain the illuminance at a constant condition without providing the light-shielding cover 142, and the illuminance is controlled to be constant at appropriate times according to changes in illuminance around one area.

As the lamp 140, an instantaneous light-emitting stroboscope or the like may be used in order to accurately recognize flocs regardless of their movement.

The baffle plates 125A, 125B, and 125C are provided in the floc formation pond 30 so as to suppress the movement of water as much as possible and not to block the illumination.

Therefore, an image of a group of flocs in a flowing state can be recognized with high accuracy.

The brightness information of the flock image captured by ITV130 is provided by IT.
It is transmitted to the image recognition device 150 via the V controller 132. ITV controller 132 is ITV13
An image recognition control device that also has the function of giving a timing signal that determines the timing to extract luminance information to 0! 16o
controls the number of times the image recognition device 150 performs flock recognition.

Monitoring of the floc formation status using these devices is carried out about once every 10 minutes to every hour, since it rarely changes rapidly in a short period of time.

Next, the image information of the flock group is image recognized! ! 1150
The signal processing operation will be explained below.

FIG. 3 shows an image plane of the flocks recognized by the ITV 130. Since the flock group is white, the brightness level is high. On the other hand, since the background back screen 124 is black, the brightness level of the water is low. Since the floc group is a gray-scale image, the boundary between the floc 34 and water is not clear in reality, but only the outline of the floc group is shown in FIG. 3 for simplicity.

FIG. 4 shows the distribution of brightness levels scanned by line AA' on the screen of FIG. The brightness level is displayed in 256 levels, for example, with lower brightness toward the top of the vertical axis and higher brightness toward the bottom. Since the flock 34 is white, the luminance is high. That is, the portion where the luminance level becomes a valley in the downward direction represents the floc.

In the brightness distribution of FIG. 4, binarization processing is performed based on the brightness threshold specified by the BB' line. Pixels at a brightness level higher than the @ value are set as 1111+ (flock),
On the other hand, pixels at a luminance level below a predetermined value are designated as "O" (water). FIG. 5 is a diagram obtained by binarization processing along line AA' in FIG.

Next, the number of pixels that each flock has (Ni, i = 1
The particle size (Di
, i = 1°2,...n) is calculated using the following formula.

Di=Hiro1fu τ (2) The signal of the calculated particle size is output from the image recognition device 150. Next, referring to FIG. 1, a procedure for calculating density from the particle size of flocs will be explained. The floc density calculation device 210 receives the floc particle size signal Di output from the image recognition device 150.
From the volume of floc (Vil i =1.2...
・Calculate n) using the following formula.

v1=4πDi1/3 ・ ・ ・ ・ ・ ・ ・
・(3) The total volume of the floc, Vt, is calculated using the following formula.

On the other hand, the floc weight calculation device 230 calculates the total weight M of turbidity from the turbidity measurement value Tu obtained from the turbidity meter 11 using the following formula. Here, k is a constant.

M = k-T u ・・・・・・・・・・・・ (
5) Floc density calculation device [220 is the floc volume calculation device 1! The average density ρ of the flocs is calculated from the total volume Vt of flocs outputted by the 210 and the total weight M of turbidity outputted by the floc weight calculation device @230. Calculate using equation (1).

O ρ=M/Vt ・・・・・・・・・・・・
・(1)1 The density of flocs is lower as the grain size of the flocs becomes larger, and conversely, the density of the flocs is higher as the grain size becomes smaller (variation range of density = 1°002 to 1.050). In a pond, grown flocs make up the majority, so the average density of grown flocs should be used to approximate the calculation.

The flocculant injection amount calculation MM200 is the floc weight calculation device 2.
The floc density ρ signal calculated in step 20 is received and converted as shown in FIG. 6 to calculate the flocculant injection amount A. That is, if the density ρ of the flocs becomes low, the amount of flocculant injected is excessive, so the flocculant injector 22 is operated to reduce the amount A of flocculant injected.

Conversely, if the density ρ of the flocs becomes high, the amount of coagulant injected is insufficient, so the flocculant injector 22 is operated to increase the amount A of coagulant injected.

[Effects of the Invention] According to the present invention, since the floc density is constantly measured and the flocculant injection amount is controlled, flocs with excellent sedimentation properties can be formed with the minimum flocculant injection amount. Therefore, it is possible to maintain a low load on the sedimentation tank and I overvoltage, and in turn, it is possible to save energy and labor in water purification plant maintenance and management, and to improve reliability. 1

[Brief explanation of the drawing]

1 and 2 are configuration diagrams showing one embodiment of the present invention, and FIG.
6 to 6 are diagrams for explaining the present invention in detail. [Brief explanation of symbols] 10... Water landing well, 11... Turbidity meter, 20... Rapid mixing pond, 22... Coagulant injection machine, 30... Floc formation pond, 31A, 31B , 31C... stirring paddle,
32A, 32B, 32C... Stirring motor, 100.
...Imaging device, 110...Image processing device, 200...
・Flock density calculation device, 210...Flock body eel 2
%3 Otachibana 40 Figure 5

Claims (1)

[Claims] 1. In a water purification plant, a means for measuring turbidity in raw water, a means for controlling the amount of coagulant to be injected, and an imaging means for converting luminance information of an image of a group of flocs in a floc-forming pond into an electrical signal; an image processing means for calculating the particle size and volume of the floc group based on the electric signal obtained from the imaging means; A floc formation control device comprising a floc density calculation means for calculating the density, and a flocculant injection amount control means for controlling the flocculant injection amount based on the density calculation value 2) In claim 1, When the floc density decreases, the flocculant injection amount control means decreases the flocculant injection amount, and when the floc density increases, the flocculant injection amount control means increases the flocculant injection amount. Characteristic floc formation control device