JP3557726B2 - Sludge interface measuring device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sludge interface measuring device for detecting an interface between a sludge phase and a supernatant liquid phase, and more particularly to an anaerobic sludge tank, particularly a UASB system (an upward-flow sludge blanket system using granular sludge). The present invention relates to an apparatus suitable for measuring the sludge interface inside the device.
[0002]
More specifically, the present invention relates to a sludge interface measuring device that determines a sludge interface based on shape information and number information of granular sludge that changes according to an operation state, and changes thereof.
[0003]
[Prior art]
In the UASB anaerobic sludge treatment apparatus, methane gas is generated in the form of colloidal fine bubbles and coarse bubbles in which the fine bubbles are associated. The presence state of the sludge in the treatment apparatus is as follows: a sludge phase in which granular sludge having a particle size of 0.5 to 3 mm is concentrated at a concentration of 20000 to 50,000 mg / l; The crushed sludge having a particle size of 0.5 mm or less obtained by crushing the sludge can be roughly classified into a supernatant liquid phase existing at an SS (sludge) concentration of 100 to 1000 mg / l. The interface between the sludge phase and the supernatant liquid phase (sludge interface) is not constant, and is constantly developing and flowing according to the amount of generated gas and the amount of inflowing raw water.
[0004]
If the sludge interface is abnormally high, granular sludge may flow out into the treatment water from the inside of the treatment apparatus, and a low sludge interface leads to a small amount of sludge retained in the treatment apparatus. Therefore, in the operation management of the anaerobic sludge treatment apparatus, it is important to continuously grasp the sludge interface in the apparatus.
[0005]
Generally, as a means for measuring a sludge interface in a settling tank of an activated sludge treatment apparatus or a settling tank of a coagulation settling treatment apparatus, a method using an ultrasonic sludge interface meter or an optical sludge concentration meter is used. The ultrasonic method is a method of emitting a sound wave to a sludge interface and measuring the distance from the time until the sound wave reflected at the sludge interface returns to the sludge. The method using an optical sludge densitometer is a method of determining the interface by using the fact that the amount of transmitted light differs between the sludge layer and the supernatant.
[0006]
[Problems to be solved by the invention]
As a result of measuring the sludge interface in the anaerobic sludge treatment apparatus using these methods, both methods were greatly affected by the generated methane gas, and reliable measurement was not performed. In particular, in the ultrasonic sludge interface meter, ultrasonic waves are not propagated normally due to bubbles of generated methane gas. In addition, the optical sludge densitometer was inadequate for distinguishing between fine methane gas generated and granular sludge.
[0007]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a sludge interface measurement device capable of stably measuring a sludge interface without being affected by generated bubbles in measuring a sludge interface inside a sludge tank. And
[0008]
[Means for Solving the Problems]
The sludge interface measurement device of the present invention is an imaging unit that captures an image of the suspension, and from among image information obtained from the imaging unit, an image processing unit that identifies granular sludge based on a shape pattern, A determination unit for determining an interface between the sludge phase and the supernatant liquid phase based on the shape information and the number information of the granular sludge output by the image processing means.
[0009]
In order to measure the sludge interface by the sludge interface measuring device of the present invention, for example, an image of the liquid is taken by an imaging means such as a CCD camera. By performing image processing on the image data, sludge and air bubbles are each recognized as a lump-shaped image. Among them, the image of the bubble is a circle or a shape approximating a circle, and moves at a relatively high speed in the liquid, whereas the image of the sludge is non-circular and irregular in shape, and moreover, Since the inside moves slowly, the sludge image and the bubble image in the lump-like image can be distinguished.
[0010]
The number of lumps and granules identified as the sludge image is counted. When the counted number exceeds a predetermined number, it is determined that the imaging point is in the sludge phase.
[0011]
By changing the depth of the imaging means or disposing a plurality of imaging means in advance at different installation depths in the liquid, imaging data at a plurality of depths is obtained, and each imaging point is located within the sludge phase. Is determined. It is determined that a sludge interface exists between the highest one of the points determined to be in the sludge phase and the lowest one of the points determined to be in the supernatant liquid phase.
[0012]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a cross-sectional view of a biological treatment tank 1 provided with an apparatus according to an embodiment, in which a supernatant liquid phase 2 and a sludge phase 3 are present. A CCD camera 4 and a projector 5 are suspended from a lifting device 6 provided above the tank 1 via a suspension member 7. The elevating device 6 can change the vertical position (depth) of the camera 4 and the projector 5 in water in the vertical direction, and can detect the depth to output depth information.
[0013]
The lifting device 6 is provided with a rack and pinion mechanism, and outputs depth information from the rotation speed of the motor for rotating the pinion; a screw nut is screwed into a rotation nut, and the screw is rotated by rotation of the nut. A screw mechanism for raising and lowering a rod, and outputting depth information from a rotation speed of a motor for rotating a nut; a winding machine for a wire for suspension; Various types such as output of depth information from the number of rotations can be used.
[0014]
The floodlight 5 is installed to irradiate the inside of the tank 1 that blocks external light, but can be omitted when the tank 1 is provided with a lighting window or lighting.
[0015]
The CCD camera 4 is arranged in a waterproof case (not shown). The CCD camera 4 has, for example, 256 × 256 pixels, and outputs image data to an image processing circuit 8 of a signal processing device 10.
[0016]
Note that if bubbles exist in the liquid as shown in FIG. 1 (c), the brightness of the pixel that has captured the bubble is higher than the brightness of the pixels that have captured the surrounding liquid. Further, when sludge is present in the liquid, the brightness of the pixel that has captured the sludge is lower than the brightness of the pixels that have captured the surrounding liquid.
[0017]
Therefore, in this image processing circuit, for example, the boundary between the granular material and the surrounding liquid is identified based on the brightness difference between adjacent pixels, and this process is performed on all the pixels, whereby the granular material (obtained by connecting the boundary) is obtained. A distinction is made between a liquid (continuous phase) and a liquid (closed area when the line is closed).
[0018]
In the present invention, as shown in FIG. 3, for example, imaging of a granular material having a diameter of 0.5 mm or more and not having a circular or circular approximate shape is determined as imaging of sludge.
[0019]
As this diameter D, it is preferable to take the average of the diameters in a plurality of directions. For example, the average of the maximum system D ₁ (FIG. 1C) and the diameter D _{2 in the} direction orthogonal to the maximum diameter direction is obtained. It is preferred to take.
[0020]
Even if the diameter is 0.5 mm or more, a shape having a circular shape or a circular approximate shape is determined as a bubble. The determination as to whether or not the shape is a circle or a circle approximate shape is made, for example, such that the outer peripheral length L of the image of the granular object is within a predetermined range with respect to 3.14 times the diameter D (the outer peripheral length of the circle). In other words, if L / 3.14D ≦ N (predetermined value), it is determined by determining that the shape is a circle or a circle approximate shape.
[0021]
As shown in FIG. 2, all sludges in one imaging screen at a certain depth are detected, and the number thereof is counted. When the counted number is equal to or more than a predetermined number, it is determined that the imaging point is in the sludge phase, and then the CCD camera 4 is moved upward by a predetermined distance to image the liquid at that point, and the sludge number is determined. Count. The imaging point is gradually raised to a point where the number of sludges is equal to or less than a predetermined number. If the number of sludges reaches a point exceeding the predetermined number, the interface determination circuit 9 determines that a sludge interface exists between the point and the highest point within the predetermined number of sludges, A signal (interface information) is output using the intermediate level as the sludge interface position.
[0022]
When it is determined that the point is in the supernatant liquid phase as a result of the analysis of the imaging data at a certain depth, the elevating device 6 is operated so that the imaging point is sequentially deepened from that point.
[0023]
In the above description, one CCD camera 4 is installed in the tank 1 so as to be able to move up and down, and the sludge interface is detected by changing the depth. However, a plurality of CCD cameras with different installation depths are provided. May be placed in the tank 1.
[0024]
In the above description, the granular material having a diameter equal to or larger than a predetermined value is determined to be sludge and air bubbles based on the outer peripheral length, but is imaged a plurality of times at the same point (depth) with different imaging times, Those having a large change in the position of the granular material on each captured image may be determined as bubbles. That is, the bubbles move quickly (especially, rise) in the liquid, but the sludge is almost stagnant, so that the sludge and the bubbles can be distinguished from the change in position over time. Needless to say, it is also possible to discriminate between air bubbles and sludge based on both the temporal change of the position (the temporal change of the shape pattern) and the outer peripheral length data.
[0025]
【The invention's effect】
As described above, according to the sludge interface measuring device of the present invention, it is possible to identify sludge and bubbles in the liquid and measure the sludge interface with high accuracy.
[Brief description of the drawings]
1A is a cross-sectional view of a biological treatment tank provided with an embodiment apparatus, FIG. 1B is a block diagram of the embodiment apparatus, and FIG. 1C is a schematic view showing sludge and bubbles in a liquid. It is.
FIG. 2 is a flowchart showing the operation of the embodiment device.
FIG. 3 is an explanatory diagram of a method for distinguishing between sludge and air bubbles.
[Explanation of symbols]
Reference Signs List 1 biological treatment tank 2 supernatant liquid phase 3 sludge phase 4 CCD camera 5 floodlight 6 lifting device

Claims (1)

Imaging means for photographing the suspension; image processing means for identifying granular sludge based on a shape pattern from image information obtained from the imaging means; A sludge interface measuring device comprising: a determination unit for determining an interface between a sludge phase and a supernatant liquid phase based on sludge shape information and number information.

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