KR100714402B1 - Apparatus for sensing precipitation density of sludge in waste water treatment tank - Google Patents

Abstract

The present invention relates to a concentration measuring device for measuring the concentration of sludge sedimented in the waste water treatment tank, the concentration measuring device of the present invention is made in the form of a cylinder with an open lower surface, the gas filled in the interior space A container immersed in the waste water inside the waste water treatment tank; A sensor installed in each of the inner spaces of the container, the light emitting part emitting light toward the water surface formed in the lower part of the container, and a light receiving part receiving light reflected from the light emitting part after being emitted from the light emitting part; It is electrically connected to the sensor, characterized in that configured to include a controller for measuring the sludge concentration by the amount of light incident on the light receiving unit.

According to the present invention, since the sludge concentration can be measured in a state in which the light emitting part and the light receiving part of the sensor for measuring the sludge concentration are not in direct contact with the waste water, the sludge does not adhere to the sensor, thereby preventing contamination. Thus, the sludge concentration measurement by the sensor can be made accurately, and there is no need to clean the sensor.

Wastewater treatment tank, sludge, concentration, concentration measuring device, concentration measuring sensor

Description

Apparatus for Sensing Precipitation Density of Sludge in Waste Water Treatment Tank}

1 is a cross-sectional view showing an example of the configuration of the water treatment system to which the sludge concentration measurement apparatus according to the present invention is applied.

Figure 2 is a sectional view showing the main part showing the sediment sludge concentration measuring apparatus of the wastewater treatment tank according to an embodiment of the present invention

Figure 3 is a sectional view showing the main part showing the sediment sludge concentration measuring apparatus of the wastewater treatment tank according to another embodiment of the present invention

Figure 4 is a sectional view showing the main part of the sediment sludge concentration measuring apparatus of the wastewater treatment tank according to another embodiment of the present invention

Explanation of symbols on the main parts of the drawings

1: wastewater treatment tank 2: inflow pipe

3: water discharge pipe 4: sludge discharge pipe

5: drawing pump 6: valve

10: concentration measuring device 20: controller

101: container 102: sensor

103: light emitting unit 104: light receiving unit

105: gas injection pipe 106: valve

107: light blocking film 108: vibration blocking plate

The present invention relates to a device for measuring the concentration of sludge precipitated in the waste water treatment tank, more specifically, sediment sludge concentration measurement of the waste water treatment tank that can accurately measure the concentration of sludge without being contaminated by sludge settled in the waste water treatment tank Relates to a device.

As is well known, organic matters contained in various kinds of domestic and industrial wastewater are environmental pollutants that pollute the water quality of rivers and lakes. Therefore, in order to reduce such water pollution, various wastewaters are properly treated in a purified water treatment system to lower biological oxygen demand (BOD) as much as possible and discharge only below the water discharge limit.

In general, the treatment step in the water treatment system can be divided into the first pre-treatment step, the second main treatment step, the third advanced processing step. In the first pretreatment step, suspended solids or suspensions are treated by screening and sedimentation flotation. In the second main treatment step, insoluble and poorly soluble colloidal substances and harmful organic substances (BOD, COD) are treated by coagulation sedimentation, electrolytic coagulation, neutralization, filtration, activated sludge, water filtration, stable paper, and oxidation paper. In the third advanced processing step, nitrogen, phosphorus, fine solids, organic matter, and inorganic salts are treated by denitrification tank, coagulation sedimentation, filtration, diatomaceous earth, activated carbon, evaporation, quenching, extraction, reverse osmosis, electrodialysis, ion exchange, and the like. .

In such a water treatment system, a unit operation called coagulation sedimentation is essential in the wastewater treatment tank in all the first to third treatment stages. In addition, most of the water pollutants are treated by physicochemical, biochemical, and other methods, and then precipitated through coagulation sedimentation and concentration tanks, and the precipitated pollutants are discharged to a dehydrator, dehydrated, and then incinerated or dumped at sea. Is handled by the method.

Typically, the wastewater treatment tank of the water treatment system is provided with a plurality of concentration measuring sensors for measuring the concentration of the flocculated sediment sludge at different heights. In addition, the lower part of the waste water treatment tank is configured with a sludge discharge device for discharging the sludge precipitated when the sludge concentration measured by the concentration measuring sensors is more than a predetermined value.

The density measuring sensor includes a light emitting part for emitting light and a light receiving part in which light reflected by the sludge particles is emitted after being emitted from the light emitting part, and an optical sensor for measuring the concentration by the amount of light absorbed by the light receiving part is mainly used. Apply.

However, the conventional concentration measuring sensor for measuring the sludge concentration in the water treatment system as described above is installed so that the light emitting portion and the light receiving portion is in direct contact with the waste water in the waste water treatment tank, the sludge adheres to the light emitting portion and the light receiving portion of the sensor and grow. In this case, due to the sludge adhered to the sensor surface is not absorbed properly, there is a problem that the concentration measurement is made incorrectly.

Therefore, conventionally, the sensors for periodically measuring the sludge concentration were removed from the wastewater treatment tank, and the sludge accumulated on the surface was removed. Then, the sensors were reinstalled in the wastewater treatment tank.

However, the removal and re-installation of the sensor from the wastewater treatment tank is not only very difficult and time-consuming, but also has to be avoided because the worker has to work through the dirty sludge layer. Due to this problem, a sensor has been developed that has a rotary wiper attached to the surface of the sensor unit to be automatically cleaned in the sedimentation basin, but this sensor also has a problem in which accumulation of contamination is inevitable during long-term operation.

In addition, as a conventional method for measuring the concentration of sediment sludge, a method of directly collecting a sludge sample precipitated at a predetermined depth of a wastewater treatment tank and analyzing the concentration is used, but such a sampling method takes time, There is a problem in that it is not possible to accurately measure the concentration in real time because of contamination of the extraction tube and the sample container.

The present invention is to solve the above problems, an object of the present invention is to measure the sludge concentration in the light emitting portion and the light receiving portion of the sensor for measuring the sludge concentration in the waste water treatment tank to make accurate sludge concentration measurement, The present invention provides a device for measuring sediment sludge concentration in a wastewater treatment tank to eliminate the need for washing.

According to one embodiment of the present invention for achieving the above object, in the sludge concentration measuring device for measuring the concentration of sludge deposited in the waste water treatment tank, the lower surface is made of an open cylinder, A container which is immersed in the waste water inside the waste water treatment tank while the gas is filled; A sensor installed in each of the inner spaces of the container, the light emitting part emitting light toward the water surface formed in the lower part of the container, and a light receiving part receiving light reflected from the light emitting part after being emitted from the light emitting part; It is electrically connected to the sensor, there is provided a sewage sludge concentration measuring apparatus of the wastewater treatment tank comprising a controller for measuring the sludge concentration by the amount of light incident on the light receiving unit.

According to another aspect of the present invention, in the sludge concentration measuring apparatus for measuring the concentration of sludge precipitated in the waste water treatment tank, the lower surface is made of an open cylinder, the waste water in the state filled with gas An upper container immersed in the waste water inside the treatment tank; A lower container coupled to a lower portion of the upper container by a predetermined distance, and having a front surface closed to seal an inner space; A sensor comprising a light emitting part installed in the inner space of the lower container and emitting light upward, and a light receiving part installed in the inner space of the upper container and receiving light emitted from the light emitting part; It is electrically connected to the sensor, there is provided a sewage sludge concentration measuring apparatus of the wastewater treatment tank comprising a controller for measuring the sludge concentration by the amount of light incident on the light receiving unit.
According to still another aspect of the present invention, in a sludge concentration measuring apparatus for measuring the concentration of sludge deposited in a wastewater treatment tank, the wastewater inside the wastewater treatment tank is filled with a gas at a predetermined pressure. A container which is locked to form a waste water surface at a lower side thereof; The settling sludge concentration measuring apparatus of the wastewater treatment tank is provided, comprising a sensor installed in a space filled with the gas inside the container to measure the sludge concentration of the wastewater inside the container in a non-contact state with the wastewater.

Hereinafter, with reference to the accompanying drawings will be described in detail preferred embodiments of the sewage sludge concentration measuring apparatus of the wastewater treatment tank according to the present invention.

1 schematically shows a configuration of a water treatment system to which a sludge concentration measuring apparatus according to the present invention is applied, and an inlet pipe 2 through which waste water is introduced is formed at one upper portion of the wastewater treatment tank 1 and the other upper portion. In the waste water treatment tank (1) is formed a water discharge pipe (3) to discharge the purified water (上 澄 水). In addition, a sludge discharge pipe 4, a drawing pump 5, and a valve 6 for discharging the sludge settled out at one lower end portion of the wastewater treatment tank 1 to the outside are installed.

Inside the wastewater treatment tank (1), the symbolic water layer (W1) formed by the clear water on the upper side where the sludge was settled largely, the floating layer (W2) in which the sludge that was not completely settled, and the lower side where the sludge was collected It consists of a precipitate sludge layer (W3).

In addition, a first concentration measuring device 10a, a second concentration measuring device 10b, and a third concentration measuring device 10c are installed in the wastewater treatment tank 1 to measure sludge concentration. The devices 10 are electrically connected to the controller 20 to transmit the measured values in real time.

The concentration measuring apparatuses 10 measure the sludge concentration by the amount of light incident on the light receiving portion of the optical sensor. Detailed configuration of the concentration measuring apparatus 10 will be described in detail with reference to FIGS. 2 to 4 below.

Among the concentration measuring devices 10, the first concentration measuring device 10a monitors the pollution degree of the symbol water, and the second concentration measuring device 10b and the third concentration due to the difference in the amount of light between day and night. It serves to prevent the concentration measurement error of the measuring device (10c). That is, during a day or a sunny day with a large amount of light, a large amount of light is incident on the light receiving units of the respective concentration measuring devices 10a, 10b, and 10c; Since the amount of incident light is small, an error may occur in the sludge concentration measured by the respective concentration measuring devices 10a, 10b, and 10c.

Therefore, the controller measures the concentration by correcting the measurement reference values of the second and third concentration measuring apparatuses 10b and 10c according to the amount of light measured by the first concentration measuring apparatus 10a.

On the other hand, when the wavelength of the used light source is in the visible light region, the influence of the external light source can not be avoided, but when using the light source in the infrared or ultraviolet light region, the influence of the external light source can be excluded. In addition, when the type of light source used is a diffused light bulb such as a general LED or a halogen lamp, the reflecting surface of the light source due to sludge increases, but the reflecting surface on the water surface also becomes relatively large, which is reflected even by relatively small water fluctuations. There is a disadvantage in that the probability that light is directly incident on the sensor of the light receiver is increased. On the other hand, when a laser-based light source is used, disturbance of the signal due to the surface reflection can be suppressed due to the high transmittance and uniform directionality of the light source. As a result, when composed of infrared or ultraviolet laser light source has the advantage that it is possible to more accurately measure the concentration of the sludge by reducing the influence of external light sources and disturbance due to the surface reflection.

In the following embodiment of the concentration measuring device illustrates that the LED light source is used.

Sludge concentration measurement and sludge discharge in the water treatment system as described above is made as follows.

When wastewater flows into the wastewater treatment tank 1 through the inflow pipe 2, sludge is precipitated to a lower portion through a predetermined treatment process. At this time, the second concentration measuring device 10b and the third concentration measuring device 10c measure the sludge concentration which is precipitated in real time.

As the wastewater treatment process proceeds, sludge is gradually precipitated from the bottom, and the sludge concentration measured by the second concentration measuring apparatus 10b increases.

When the sludge concentration measured by the second concentration measuring apparatus 10b is equal to or greater than a set value input to the controller 20, the controller 20 opens the valve 6 and operates the drawing pump 5. The sludge is discharged to the outside through the sludge discharge pipe (4).

As the sludge is discharged through the sludge discharge pipe 4, the height of the settling sludge layer W3 gradually decreases. The concentration measured by the concentration measuring apparatus 10c is drastically reduced.

Therefore, when the concentration measured by the third concentration measuring apparatus 10c becomes lower than the preset value input to the controller 20, the controller 20 closes the valve 6 and draw pump 5. The sludge is discontinued as the operation stops.

In the wastewater treatment tank 1, sludge discharge is performed while the concentration measurement and drawing pump 5 are repeated.

On the other hand, Figure 2 shows an embodiment of the configuration of the concentration measuring apparatus 10, the concentration measuring apparatus 10 and the container 101 of the cylindrical shape with the lower surface open; Sensor 102 is fixed to the interior space of the container 101, and the pressure holding means for maintaining a constant internal pressure by injecting gas into the container 101.

The container 101 is immersed in the wastewater in the wastewater treatment tank 1 while the gas is filled in the inner space. Therefore, a predetermined space is formed inside the container 101 by air pressure, and the water surface is formed at a predetermined height under the container 101.

The sensor 102 is fixed to an interior space of the container 101 to emit light toward the water surface formed in the lower portion of the container 101, and the sludge of the lower after being emitted from the light emitting portion 103 The light sensor is composed of a light receiving unit 104 is incident to the light reflected by the hit. The sensor 102 is electrically connected to the controller 20 (see FIG. 1), and the controller 20 measures the sludge concentration by the amount of light incident on the light receiving unit 104.

The light emitting unit 103 is preferably installed to be inclined at a predetermined angle with respect to the light receiving unit 104, which is emitted through the light emitting unit 103, the light reflected by hitting the water surface without hitting the sludge particles (S), the light receiving unit This is to minimize the incident incident to 104.

Specifically, when the light emitted through the light emitting unit 103 hits the interface such as the water surface, the light is reflected at the same angle as the incident angle. Therefore, when the light emitting unit 103 and the light receiving unit 104 are installed side by side, the light emitted almost vertically through the light emitting unit 103 is likely to be incident on the light receiving unit 104 after being reflected by the water surface. However, when the light emitting unit 103 and the light receiving unit 104 have a predetermined angle, the possibility that the light emitted obliquely through the light emitting unit 103 is reflected by the water surface and then enters the light receiving unit 104 is significantly reduced. do.

In addition, the light blocking unit 104 may be provided so that the light blocking film 107 for blocking the light reflected from the side to extend downward.

As described above, the sensor 102 minimizes the incident of reflected light to the light receiving unit 104 by hitting the water surface and the inner wall surface of the container 101 among the reflected light emitted through the light emitting unit 103, and sludge It is preferable that the light reflected by the bump is selectively configured to be incident on the light receiving unit 104.

The sensor 102 may be configured using a light emitting diode (LED), a photodiode, or the like.

In addition, the container 101 preferably has a dark color such as black so as to minimize the influence of external light on the sensor 102. In addition, a material having low reflectivity or no reflection at all may be coated on the inner wall surface of the container 101, or the container 101 may be made of such a material.

On the other hand, since the gas inside the container 101 dissolves in water over time, the pressure inside the container 101 gradually decreases. Therefore, the surface of the water in the container 101 rises, and even the same sludge concentration may change the measured value.

Therefore, it is preferable to maintain a constant pressure inside the container 101 by periodically or continuously supplying gas into the container 101 through the pressure holding means.

The pressure holding means is forced through the gas injection pipe 105 connected to the container 101, the valve 106 for opening and closing the gas injection pipe 105, and the gas injection pipe 105 It may be configured to include a gas supply unit (not shown) for supplying gas. Here, the gas supply unit may be configured using, for example, a blower or an air pump.

In addition, a water level sensor 109 may be installed on the inner wall surface of the container 101 to detect the water level inside the container 101 to control the opening and closing operation of the valve 106. Therefore, when the pressure inside the container 101 is lowered and the water level is increased, the water level sensor 109 detects a change in the water level. Accordingly, the valve 106 is opened and the gas into the container 101 is opened. Is supplied to increase the internal pressure of the container 101 and lower the water level to the set water level. When the water level sensor 109 is installed in the container 101 as described above, not only can the water level inside the container 101 be maintained at an appropriate level but also the gas supply is excessively supplied into the container 101. It can be prevented.

The water level sensor 109 can be configured using a variety of sensors well known in the art, for example, it is possible to detect the change in the water level using a buoyancy level meter, and to control the opening and closing operation of the valve 106. have.

The concentration measuring apparatus 10 configured as described above acts as follows.

The light emitted through the light emitting unit 103 of the sensor 102 is reflected by hitting the water surface or by hitting the sludge particles (S) in the water. As described above, the light reflected by the surface of the reflected light at this time is the same angle of incidence and the angle of reflection, so most of the light is not incident to the light receiving portion 104, but is reflected off to the side or blocked by the light blocking film 107, the light receiving portion 104 ) Can not be incident. On the other hand, when the light hits the sludge particles (S), diffuse reflection occurs and is reflected at an angle not equal to the incident angle. At this time, light reflected substantially vertically among the light reflected by the sludge particles S passes through the light blocking film 107 below the light receiving unit 104 and is incident to the light receiving unit 104.

When there is a lot of sludge particles (S) precipitated in the waste water, the amount of light incident on the light receiving unit 104 is increased by such diffuse reflection, and when there is less sludge particles (S) precipitated in the waste water, the light receiving unit 104 is caused by diffuse reflection. The amount of incident light is small. That is, the amount of light incident on the light receiving portion 104 is proportional to the number of sludge particles.

Accordingly, the controller 20 (see FIG. 1) can measure the sludge concentration in the waste water according to the amount of light incident into the light receiving unit 104.

On the other hand, as described above, when the concentration measuring device 10 is not completely immersed in the wastewater surface of the wastewater treatment tank 1 and the middle portion is covered, the wastewater treatment tank 1 while measuring the sludge concentration in the wastewater (FIG. 1). The waste water fluctuates due to factors such as the supply of waste water. The rocking of the waste water is transmitted to the water surface formed inside the container 101 to generate vibration.

When vibration occurs on the surface of the container 101, a change in the amount of light emitted from the light emitter 103 may be incident on the light receiver 104, and thus concentration measurement may not be accurately performed.

Therefore, as illustrated as a modification of the concentration measuring apparatus 10 described above with reference to FIG. 3, the vibration blocking plate 108 is formed below the inner circumferential surface of the container 101 at a predetermined distance below the inner space of the container 101. Thus, vibration may be minimized to the water surface formed in the container 101.

According to the present invention, since the light emitting unit 103 and the light receiving unit 104 of the sensor 102 for measuring the concentration is located in the empty space of the container 101 without waste water, the light emitting unit 103 and the light receiving unit 104 There is no phenomenon of directly contacting the waste water, and thus there is no phenomenon in which the sludge leaks in the light emitting portion 103 and the light receiving portion 104.

Figure 4 shows another embodiment of the concentration measuring device according to the present invention, the concentration measuring device 10 of this embodiment, the lower surface is made of a cylindrical shape, the waste water in a state filled with gas in the inner space An upper container 111 immersed in the waste water inside the treatment tank; The lower container 112 is coupled to the lower portion of the upper container 111 by a predetermined distance, and the front surface is closed to close the inner space.

A light emitting part 113 is disposed below the inner space of the lower container 112 to emit light upward, and the light emitted from the light emitting part 113 is incident on the upper inner space of the upper container 111. The light receiving unit 114 is installed.

In addition, an oil layer 118 having a specific gravity greater than water is formed at an upper portion of the lower container 112 at about 1.6. The oil layer 118 is formed to expose the upper surface of the light path to the outside. Therefore, even if the sludge particles S are close to the upper portion of the oil layer 118, the hydrophilic sludge particles do not stick to the hydrophobic oil layer 118, and thus the concentration measuring apparatus 10 does not need to be cleaned.

Since the oil layer 118 has a specific gravity greater than that of water, the oil layer 118 is not floated in water even if the entire or part of the upper surface thereof is opened, so that the oil layer 118 remains on the upper portion of the lower container 112.

The upper container 111 and the lower container 112 are coupled to each other by a connecting member 117 in the form of a bar of wire or rigid body.

In addition, similar to the concentration measuring apparatus of the above-described embodiment, the pressure holding means for maintaining a constant pressure by supplying gas to the upper container 111 inside the upper container 111, that is, the gas injection pipe 115 and the valve 116 and a gas supply unit (not shown) are installed.

The concentration measuring apparatus 10 configured as described above acts as follows.

Light emitted substantially vertically through the light emitting unit 113 travels toward the light receiving unit 114. At this time, if there is sludge particles (S) in the waste water between the upper container 111 and the lower container 112, some of the light emitted from the light emitting unit 113 is hit by the sludge particles (S) reflected and the light receiving unit 114 Is not incident to Therefore, as the number of sludge particles increases, that is, as the sludge concentration increases, the amount of light that hits and is reflected by the sludge particles increases, thereby reducing the amount of light incident on the light receiving unit 114.

Therefore, an inverse relationship is established between the amount of light incident on the light receiving unit 114 and the number of sludge particles, and the controller 20 (see FIG. 1) thus measures sludge concentration according to the amount of light incident on the light receiving unit 114. It will be possible.

Precipitation sludge concentration measuring apparatus according to the present invention will be possible in various ways and modifications within the spirit and scope of the invention defined by the claims of the present invention in addition to the above-described embodiments.

As described above, according to the present invention, since the light emitting part and the light receiving part of the sensor for measuring the sludge concentration can measure the sludge concentration without being in direct contact with the waste water, the sludge does not adhere to the light emitting part and the light receiving part of the sensor, thereby preventing contamination. Is prevented. Therefore, the sludge concentration measurement by the sensor can be made accurately, there is an advantage that does not need to clean the sensor even after a long time use.

Claims (20)

In the sludge concentration measuring device for measuring the concentration of sludge deposited in the waste water treatment tank, A container having an open lower surface, the container being immersed in the wastewater inside the wastewater treatment tank while the gas is filled in the internal space; A sensor installed in each of the inner spaces of the container, the light emitting part emitting light toward the water surface formed in the lower part of the container, and a light receiving part receiving light reflected from the light emitting part after being emitted from the light emitting part; And a controller electrically connected to the sensor and configured to measure the sludge concentration by the amount of light incident on the light receiving unit. The apparatus of claim 1, further comprising pressure holding means for injecting gas into the container so that the inner space of the container maintains a predetermined pressure. The gas supply pipe of claim 2, wherein the pressure holding means includes a gas injection pipe connected to the container, a valve for opening and closing the gas injection pipe, and a gas supply unit forcibly supplying gas through the gas injection pipe. Settling sludge concentration measuring device of the wastewater treatment tank, characterized in that configured. The apparatus of claim 3, wherein the pressure maintaining means further comprises a water level sensor for sensing the water level inside the container to control the opening and closing operation of the valve. The apparatus of claim 1, wherein the light emitting part of the sensor is inclined at a predetermined angle with respect to the light receiving part. The apparatus of claim 1 or 5, wherein a light shielding film for blocking light incident from the side of the light receiving part is extended so as to extend downward. The container according to claim 1, further comprising a vibration blocking plate disposed below the inner circumferential surface of the container and spaced apart from the inner circumferential surface of the container to prevent the surface of the container from vibrating due to rocking of the waste water. Settling sludge concentration measuring device of the wastewater treatment tank. The apparatus of claim 1, wherein the container has a color to prevent light penetration from the outside. In the sludge concentration measuring device for measuring the concentration of sludge deposited in the waste water treatment tank, An upper container having an open lower surface and being immersed in the waste water inside the waste water treatment tank with gas filled in the inner space; A lower container coupled to a lower portion of the upper container by a predetermined distance, and having a front surface closed to seal an inner space; A sensor comprising a light emitting part installed in the inner space of the lower container and emitting light upward, and a light receiving part installed in the inner space of the upper container and receiving light emitted from the light emitting part; And a controller electrically connected to the sensor and configured to measure the sludge concentration by the amount of light incident on the light receiving unit. 10. The apparatus of claim 9, further comprising pressure holding means for injecting gas into the upper container so that the inner space of the upper container maintains a predetermined gas pressure. The gas supply unit according to claim 10, wherein the pressure maintaining means includes a gas injection pipe connected to the upper container, a valve for opening and closing the gas injection pipe, and a gas supply unit for forcibly supplying gas through the gas injection pipe. Settling sludge concentration measuring device of the wastewater treatment tank, characterized in that configured to include. 12. The apparatus of claim 11, wherein the pressure maintaining means further comprises a water level sensor for sensing the water level inside the upper container to control the opening and closing operation of the valve. 10. The apparatus of claim 9, further comprising a plurality of connecting members for integrally connecting the upper container and the lower container. 10. The apparatus of claim 9, wherein an oil layer having a specific gravity greater than water and having an upper surface exposed to the outside is formed on an upper portion of the lower container. 10. The apparatus of claim 1 or 9, wherein the light emitting unit is configured by using a light source that emits light in the visible wavelength range. 10. The apparatus of claim 1 or 9, wherein the light emitting unit is configured using a light source that emits light in an infrared or ultraviolet wavelength band. 10. The apparatus of claim 1 or 9, wherein the light source of the light emitting part is a bulb type. 10. The apparatus of claim 1 or 9, wherein the light source of the light emitting unit is of a laser type. In the sludge concentration measuring device for measuring the concentration of sludge deposited in the waste water treatment tank, A container which is immersed in the wastewater inside the wastewater treatment tank in a state where the gas is filled at a predetermined pressure to form a wastewater surface on the lower side; The sewage sludge concentration measuring apparatus of the wastewater treatment tank, comprising: a sensor installed in a space filled with gas inside the container and measuring a sludge concentration of the wastewater inside the container in a non-contact state with the wastewater. 20. The apparatus of claim 19, further comprising pressure holding means for injecting gas into the container so that the inner space of the container maintains a predetermined pressure.

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