JPH0921678A - Sludge-interface measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to measure the interface of sludge in high accuracy by discriminating the sludge and bubbles in liquid. SOLUTION: From a lifting device 6 providing at the upper part of a tank 1, a CCD camera 4 and a light projector 5 are suspended through a suspending member 7. The image of granular material, which has the diameter of 0.5mm or more and has the shape, which is not circular or not approximately circular, is judged at the image of sludge. All the sludges in one image plane at a certain depth are detected, and the number is counted. When the counter number is a specified number or more, it is judged that the image pickup point is located in the sludge phase. Then, the CCD camera 4 is moved upward by a specified distance. The image in the liquid is picked up at this point, and the number of the sludges is counted. The image point is made to rise up little by little (to the pint) until the number of the sludges becomes the specified number of less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. 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.
In particular, the present invention relates to an apparatus suitable for measuring a sludge interface in an anaerobic sludge tank, particularly a UASB method (upflow sludge blanket method using granular sludge).

More specifically, the present invention relates to a sludge interface measuring device which determines a sludge interface based on shape information and number information of granular sludge which changes depending on an operation state, and changes thereof.

[0003]

2. Description of the Related Art In an anaerobic sludge treatment apparatus of the UASB type, 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 has an SS (sludge) concentration of 100 to 1000 mg / l.
Can be roughly divided into the supernatant liquid phase that exists. 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 treated water from within the treatment equipment,
In addition, 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.

Generally, as a means for measuring the sludge interface of the settling tank of the activated sludge treatment device or the settling tank of the coagulating sedimentation treatment device,
A method using an ultrasonic sludge interface meter or an optical sludge densitometer is used. The ultrasonic method is a method of emitting a sound wave to the 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 for determining the interface by using the fact that the amount of transmitted light differs between the sludge layer and the supernatant.

[0006]

As a result of measuring the sludge interface in an anaerobic sludge treatment apparatus using these methods, both methods were greatly affected by the generated methane gas, and could not be reliably measured. In particular, in the ultrasonic type sludge interface meter, ultrasonic waves are not normally propagated due to bubbles of generated methane gas. In addition, the optical sludge densitometer failed to distinguish between the generated fine methane gas and granular sludge.

In view of the above problems, the present invention provides a sludge interface measuring device capable of stably measuring the sludge interface without being affected by bubbles generated in the sludge interface measurement inside the sludge tank. The purpose is to

[0008]

The sludge interface measuring device of the present invention is a granular device based on a shape pattern from an imaging device for imaging the inside of a suspension and image information obtained from the imaging device. An image processing unit for identifying sludge, and a determination unit for determining the 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 unit. is there.

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 subjecting the imaged data to image processing, sludge and air bubbles are recognized as lumpy images. Of these, the image of bubbles is a circle or something similar to a circle, and while moving in the liquid at a relatively high speed, the image of sludge is non-circular and irregularly shaped. Since the movement in the inside is slow, the sludge image and the bubble image in the lump-shaped image can be distinguished.

The number of lump particles identified as the sludge image is counted. When the count number exceeds the predetermined number, it is determined that the imaging point is in the sludge phase.

By changing the depth of the image pickup means or arranging a plurality of image pickup means in the liquid in advance with different installation depths, image pickup data at a plurality of depths can be obtained,
It is determined whether each imaging point is in the sludge phase. 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]

FIG. 1 is a cross-sectional view of a biological treatment tank 1 provided with an apparatus according to an embodiment of the present invention, in which a supernatant liquid phase 2 and a sludge phase 3 are provided.
And exists. Elevating device 6 provided above tank 1
The CCD camera 4 and the light projector 5 are suspended 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 output the depth information by detecting the depth.

The lifting device 6 is provided with a rack-and-pinion mechanism so that depth information can be output from the number of rotations of the motor for rotating the pinion; Equipped with a screwing mechanism that raises and lowers a screw rod by rotation, and outputs depth information from the number of rotations of a motor for rotating a nut; Various types can be used, such as those that output depth information from the number of rotations of the machine.

The light projector 5 is installed to irradiate the inside of the tank 1 that shields external light, but it can be omitted when the tank 1 is provided with a daylighting window or lighting.

The CCD camera 4 is a waterproof case (not shown).
Is located within. This CCD camera 4 is, for example, 2
It has 56 × 256 pixels and outputs the image pickup data to the image processing circuit 8 of the signal processing device 10.

When air bubbles are present in the liquid as shown in FIG. 1C, the brightness of the pixels that image the air bubbles is higher than the brightness of pixels that image the surrounding liquid. Further, when sludge is present in the liquid, the brightness of the pixels that image the sludge is lower than the brightness of the pixels that image the surrounding liquid.

Therefore, in this image processing circuit, for example, the boundary between the granular material and the liquid around the granular material is identified from the difference in brightness between adjacent pixels, and this processing is performed for all the pixels so that the granular material (the boundary is connected). When the line obtained in (1) is closed, a closed area) is distinguished from a liquid (continuous phase).

In the present invention, as shown in FIG. 3, for example, an image of a granular material having a diameter of 0.5 mm or more and having a shape not a circle or a circular approximate shape is determined as an image of sludge.

As the diameter D, it is preferable to take an average of diameters in a plurality of directions. For example, the maximum system D ₁ (see FIG. 1).
It is preferable to take the average of (c)) and the diameter D _{2 in the} direction orthogonal to the maximum radial direction.

Even if the diameter is 0.5 mm or more, if the shape is a circle or a circle approximate shape, it is judged as a bubble.
Whether or not the shape is a circle or a circle approximate shape is determined, for example, when the outer peripheral length L of the image of the granular material is within a predetermined range with respect to 3.14 times the diameter D (the outer peripheral length of the circle). That is, L / 3.1
If 4D ≦ N (predetermined value), it is determined to be a circle or an approximate circle shape.

As shown in FIG. 2, all sludges in one image pickup screen at a certain depth are detected and the number thereof is counted. When this count number is equal to or greater than the predetermined number, it is determined that the image pickup point is in the sludge phase, then the CCD camera 4 is moved upward by a predetermined distance, and the inside of the liquid is imaged at that point, and the sludge number is determined. To count. The imaging point is gradually raised to a point at which the number of sludges becomes a predetermined number or less. When the sludge number 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 where the sludge number is within the predetermined number, A signal (interface information) is output with the intermediate level as the sludge interface position.

When it is determined that the point is in the supernatant liquid phase as a result of the analysis of the imaged data at a certain depth, the elevating device 6 is operated so as to sequentially deepen the imaged point from that point.

In the above description, one CCD camera 4 is used as the tank 1.
The sludge interface is detected by changing its depth, but a plurality of CCD cameras having different installation depths may be fixed in the tank 1.

In the above description, the granular material having a diameter of a predetermined value or more is discriminated into sludge and bubbles based on the outer peripheral length thereof. However, at the same point (depth), the imaging time is varied and the plural times. It is also possible to pick up an image and determine as a bubble the one in which the position change of the granular material on each picked-up image is large. That is, the bubbles move (especially rise) in the liquid rapidly, but the sludge is almost stagnant, and therefore the sludge and the bubbles can be discriminated from the change in position over time. Of course, it is possible to discriminate between air bubbles and sludge based on both the position change with time (change of shape pattern with time) and the outer circumference length data.

[0025]

As described above, according to the sludge interface measuring device of the present invention, it is possible to discriminate between sludge and bubbles in the liquid and measure the sludge interface with high accuracy.

[Brief description of drawings]

FIG. 1A is a cross-sectional view of a biological treatment tank equipped 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. Is.

FIG. 2 is a flowchart showing the operation of the embodiment device.

FIG. 3 is an explanatory diagram of a method for discriminating sludge from bubbles.

[Explanation of symbols]

 1 Biological treatment tank 2 Supernatant liquid phase 3 Sludge phase 4 CCD camera 5 Light projector 6 Lifting device

Claims (1)

[Claims] 1. An image pickup means for photographing the inside of a suspension, an image processing means for identifying granular sludge based on a shape pattern from image information obtained from the image pickup means, and the image processing means. The sludge interface measuring device, comprising: a determination unit that determines the interface between the sludge phase and the supernatant liquid phase based on the shape information and the number information of the granular sludge that is output by.