JPH0938687A - Sludge floating predicting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to judge the floatability of sludge and to predict the floating of the sludge by photographing the inside of the suspension in an anaerobic reaction vessel, identifying the granular sludge in accordance with shape patterns and deciding the floatability of the sludge in accordance with the shape information and number information of the granular sludge. SOLUTION: An image pickup machine (CCD camera) 4 and a light projector 5 are hung via a suspending member 7 at a lifting device 6 disposed in the upper part of the vessel 1. The lifting device 6 is capable of changing the vertical positions of the camera 4 and the light projector 5 in the water and outputting the output depth information by detecting the depth thereof. An image processing circuit 8 identifies the boundary between the granular material and the surrounding liquid from the lightness difference of, for example, adjacent pixels, detects all the sludge larger than the prescribed size in the one picked up image screen at a certain depth and counts the number thereof by grain size ranges. If the count number of the prescribed range is above the prescribed number, the sludge at this image pickup point is judged to have the high floatability and a sludge floating prediction signal is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge flotation prediction device for predicting sludge floatability in an anaerobic reaction tank, and more particularly to a UASB method (upflow sludge using granular sludge). (Blanket method) The present invention relates to a device suitable for predicting the floating property of sludge inside.

More specifically, the present invention relates to a sludge flotation prediction device that determines the flotation property of sludge based on the shape information and the number information of granular sludge that changes depending on the operating state and the change.

[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.

If the floating property of the sludge is abnormally increased, granular sludge may flow out into the treated water from the inside of the treatment device, leading to a small amount of sludge retained in the treatment device. 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.

Further, even if the interface level is detected by these instruments, the result of sludge outflow can be detected, but the future outflow of sludge cannot be predicted.

In view of the above problems, the present invention provides a sludge flotation prediction device capable of determining the flotability of sludge in an anaerobic reaction tank and predicting the flotation based on this. With the goal.

[0009]

[Means for Solving the Problems] Generally, the sludge in the anaerobic reaction tank grows in a state in which the gas generated in the granular sludge is entrapped, becomes a large granular material, and is easily floated. Become. Therefore, by grasping that the number of large-sized sludges in the sludge layer increases, the floating property of the sludge can be predicted.

The sludge flotation prediction device of the present invention is based on such knowledge, and is composed of an image pickup means for photographing the inside of the suspension in the anaerobic reaction tank and image information obtained from the image pickup means. An image processing unit for identifying the granular sludge based on the shape pattern, and a determination unit for determining the floating property of the sludge based on the shape information and the number information of the granular sludge output by the image processing unit. It was done.

In order to predict the floating property of sludge by the sludge floating prediction device of the present invention, the inside of the liquid is imaged by an image pickup 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.

For example, the number of lumps and granules identified as this sludge image within a predetermined imaging range and having a predetermined size or more is counted. When the counted number exceeds the predetermined number, it is determined that the sludge in the imaging range has a floating property.

Further, the rate of increase in the number of sludges having a predetermined size or more may be obtained based on the time-dependent data of the number, and the sludge floating property may be determined from this rate of increase.

[0014]

1 is a cross-sectional view of an anaerobic biological treatment tank 1 equipped with an apparatus according to an embodiment, in which a supernatant liquid phase 2 and a sludge phase 3 are present. An image pickup device (CCD camera) 4 and a light projector 5 are suspended from a lifting device 6 provided at the top of the tank 1 via a suspension member 7. This lifting device 6
Can change the vertical position (depth) of the camera 4 and the light projector 5 in the water, and can detect the depth and output depth information.

The lifting device 6 is provided with a rack and pinion mechanism so that depth information is output from the number of revolutions 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 which is shielded from external light, but can be omitted when the tank 1 is provided with a daylighting window or illumination.

The CCD camera 4 is a waterproof case (not shown).
It is located inside. 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.

In the image processing circuit 8, when air bubbles exist 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 it is identified from the difference in brightness of the 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 (a), for example, the image pickup of a granular object having a diameter of 0.5 mm or more and the shape not being a circle or a circular approximate shape is determined as the image pickup of sludge.

As the diameter D, it is preferable to take the average of the 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, a circle or a circle approximate shape 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.

Further, since the moving speed of air bubbles is higher than that of sludge, images are taken twice, for example, once per second for a short time, and the two moving image data are compared to determine that the particles having large movement are air bubbles. good. The image processing circuit 8 identifies the granular sludge as described above, and outputs a number count for each range of the particle size D to the levitation determination unit 9. The range of the particle diameter D is, for example, 0.5 to 1.5 mm, 1.
It can be 5 to 3 mm, 3 mm or more.

As shown in FIG. 2, all sludges having a predetermined size or more in one image pickup screen at a certain depth are detected, and the number is counted for each particle size range. Then, when the count number of the predetermined range is equal to or more than the predetermined number, it is determined that the sludge at the imaging point has a high floating property, and the sludge floating prediction signal is output. For example, based on the data input from the image processing circuit 8, in the levitation determination unit 9, as shown in FIG. 3B, the number of sludge having a particle diameter D of 3 mm or more or 1.5 to 3 mm is a predetermined number. When it is above, it is predicted that the floating property will be high.

Next, the CCD camera 4 is moved upward or downward by a predetermined distance, the inside of the liquid is imaged at that point, the number of sludge having a predetermined size or more is counted, and the floating property of the sludge at that point is predicted. In this way, the sludge floatability is predicted at all depths in the anaerobic reaction tank or at a depth within a preset range.

In the above description, as shown in FIG. 3B, the floating property is immediately predicted from the number of sludges having a predetermined size or more. However, the same region is imaged at the same depth over time,
It is also possible to detect the change rate (increase rate or decrease rate) of the number of sludges having a predetermined size or more in that region, and to predict that sludge floatability is present when this increase rate is not less than a predetermined rate.

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. 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.

[0028]

As described above, according to the sludge flotation prediction device of the present invention, it is possible to predict sludge flotability with high accuracy by distinguishing sludge and bubbles in liquid. In addition, appropriate sludge treatment (sludge crushing, etc.) in response to the sludge floating prediction signal
By carrying out, it is possible to prevent the sludge from floating, and as a result, it is possible to prevent the sludge from flowing out to the treated water.

[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 and levitation determination.

[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 processing unit for capturing an image of the inside of a suspension in an anaerobic reaction tank, and an image processing unit for identifying granular sludge based on a shape pattern from image information obtained from the image capturing unit. A sludge flotation prediction apparatus comprising: a sludge flotation determination unit that determines the flotation property of the sludge based on the shape information and the number information of the granular sludge output by the image processing unit.