KR20180120653A - An Ultrasound Apparatus for Measuring an Interface Surface and a Method for Same - Google Patents

Abstract

The present invention an ultrasound apparatus for measuring an interface surface and a method thereof and, more specifically, relates to an ultrasound apparatus for measuring an interface surface and a method thereof, which can measure an interface surface formed under the water such as activated carbon arranged in filter paper. In the ultrasound apparatus for measuring an interface surface and the method thereof, the ultrasound apparatus comprises: a plurality of ultrasound units (121 to 12N) of a first ultrasound group arranged in a predetermined difference height of a first linear member (11); a plurality of ultrasound units (221 to 22N) of a second ultrasound group arranged in a predetermined difference height of a second linear member (21); and a treatment unit (13) controlling transmission of an ultrasound wave of the ultrasound units (121 to 12N) of the first ultrasound group and the ultrasound units (221 to 22N) of the second ultrasound group, and treating a receiving signal. An ultrasound signal transmitted in the ultrasound units (121 to 12N) of the first ultrasound group is received in accordance with a position of an interface surface by the ultrasound units (221 to 22N) of the second ultrasound group, or receiving sensitivity is changed.

Description

TECHNICAL FIELD [0001] The present invention relates to an ultrasonic interface measuring apparatus and an ultrasonic interface measuring method using the same.

The present invention relates to an ultrasonic interface measuring apparatus and an interface measuring method therefor, and more particularly, to an ultrasonic interface measuring apparatus capable of measuring an interface formed in water, such as activated carbon placed on a filter paper, and an interface measuring method therefor.

The water purification plant for the supply of water is composed of a water intake point for the water supply of the water source, a mixed soil for mixing the water and the water purification agent, a sedimentation tank for precipitating and removing the foreign matter through the agglomeration process, A filtering paper to be removed, and a fixing paper for storing purified water from which impurities have been removed. Impurities in the filtering paper can be removed by the activated carbon, and if the activated carbon is used for a certain period of time, the foreign substances accumulated in the activated carbon itself must be removed for reuse. In order to remove impurities from the activated carbon, water must be backwashed by forcibly injecting water in the direction opposite to the flow of water in the purification process. During the backwashing process, the activated carbon expands, and the level of expansion of the activated carbon is detected, so that the backwashing process needs to be appropriately controlled. Various techniques for the process of backwashing such filter paper are known in the art.

Patent Publication No. 10-2009-0026693 relates to a measuring apparatus for measuring the expansion rate of a filter paper in a water treatment system, comprising: a support tube fixedly installed on one side of a filter paper or detachable; A sensor unit mounted on a lower end of the support tube and capable of measuring the concentration of the desorbed sediment from the sand or activated carbon upon backwashing of the filter paper; A screen operation unit for responding to the output of the sensor unit and calculating and storing the expansion rate of the filter paper by comparing the output position of the sensor unit with the reference point position of the support pipe; A data transfer unit mounted on an upper end of the support tube and outputting the calculated expansion rate and the output of the sensor unit to the outside; And a length adjuster mounted at the center of the support tube and adjusting the length of the support tube so as to fix the reference point of the support tube to the surface of the filter media.

Patent Publication No. 2001-0006614 discloses an activated carbon adsorption paper in which an activated carbon layer is formed to adsorb contaminants contained in treated water flowing through a pretreatment such as an outer sand filter or an ozone contact paper; First particle size measurement means for measuring the particle size of the process water loaded on the outlet side of the activated carbon adsorption paper and detecting microorganisms leaking from the activated carbon adsorption paper through the particle size analysis, micro activated carbon and suspended matter; And control means for receiving the particle size data measured by the first particle size measurement means to determine a backwash point and outputting a control signal.

The calculation of the expansion rate by the concentration measurement disclosed in the prior art can exhibit different concentrations depending on the positions at the same height in the backwashing process and thus has a disadvantage that it is difficult to measure the expansion ratio or the expansion interface substantially at the approximate scale. Interfacial measurements are required for measuring the height of a sand bed, an activated carbon bed, or a sediment bed formed or disposed in water, and it is advantageous that both the stationary interface and the moving interface can be measured. However, the prior art does not disclose an apparatus or a method for measuring the height of a stationary interface or a moving interface of a foreign matter layer formed in such a water.

The present invention has been made to solve the problems of the prior art and has the following purpose.

Prior Art 1: Patent Publication No. 10-2009-0026693 (Korea Institute of Construction Technology, published on Mar. 13, 2009) Real time measurement device and measurement method of sand filter paper expansion rate in water treatment process Prior Art 2: Patent Publication No. 2001-0006614 (published by Korea Institute of Construction Technology, Jan. 26, 2001) Automatic backwashing apparatus and method of activated carbon process

An object of the present invention is to provide an ultrasonic interface measuring apparatus and a method of measuring an ultrasonic interface therefrom, which enable the measurement of the interface of a foreign matter formed in a liquid.

Another object of the present invention is to provide an ultrasonic interface measuring apparatus and an ultrasonic interface measuring method for enabling the measurement of the expansion rate of activated carbon in backwashing of filter paper.

According to a preferred embodiment of the present invention, an ultrasonic interface measuring apparatus and an ultrasonic interface measuring method therefor according to the present invention is an apparatus for measuring an interface of a foreign object formed in a liquid, comprising: a first linear member A plurality of ultrasonic units of the group; A plurality of ultrasonic units of two ultrasonic groups arranged at predetermined predetermined heights of two linear members; And a processing unit for controlling the transmission of ultrasonic waves of the ultrasonic unit of the first ultrasonic group or the ultrasonic unit of the second ultrasonic group, or a processing unit for processing the received signal, wherein the ultrasonic signals transmitted by the respective ultrasonic units of the first ultrasonic group are two ultrasonic waves The receiving sensitivity or the reception sensitivity is changed according to the position of the interface by the ultrasonic unit of the group.

According to another preferred embodiment of the present invention, the foreign matter is activated carbon disposed inside the settlement paper, and the plurality of ultrasonic units in the first and second ultrasonic wave groups are disposed in the water of the settlement paper.

According to another preferred embodiment of the present invention, the one or two linear members have a hollow tube structure.

According to another preferred embodiment of the present invention, there is provided a method of transmitting ultrasonic waves, comprising the steps of: transmitting ultrasonic waves at different heights at different times in water; Detecting whether the ultrasonic signals of different heights are received; Determining a threshold height at which an ultrasonic signal is received; And determining a height of an interface or an interface that varies in the water formed in the water based on the limit height.

The ultrasonic interface measuring apparatus according to the present invention enables the ultrasonic wave detecting unit to accurately measure the level of activated carbon in the filter paper or the expansion rate in the course of backwashing. The interfacial measuring apparatus according to the present invention precisely determines whether the level or the expansion rate of activated carbon has reached a predetermined range in the backwashing process, thereby preventing the loss of activated carbon. The interface measuring apparatus according to the present invention makes it possible to perform interfacial measurement of various precipitates formed in water which are difficult to be measured by laser, microwave or other electromagnetic waves.

1 shows an embodiment of an ultrasonic interface measuring apparatus according to the present invention.
FIG. 2 shows an embodiment in which the ultrasonic interface measuring apparatus according to the present invention is applied to a backwashing process of filter paper.
FIG. 3 illustrates an embodiment in which the ultrasonic interface apparatus according to the present invention is installed on a filter paper.
4 shows an embodiment of the ultrasonic interface measuring method according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the accompanying drawings, but the present invention is not limited thereto. In the following description, components having the same reference numerals in different drawings have similar functions, so that they will not be described repeatedly unless necessary for an understanding of the invention, and the known components will be briefly described or omitted. However, It should not be understood as being excluded from the embodiment of Fig.

1 shows an embodiment of an ultrasonic interface measuring apparatus according to the present invention.

1, the ultrasonic interfacial measuring apparatus can be applied to the interface measurement of foreign matter formed in the liquid, and includes a plurality of one ultrasonic detecting units 121 to 12N ); A plurality of second ultrasonic detection units 221 to 22M arranged at predetermined predetermined heights of the two linear members 21; And a processing unit (13) for controlling the transmission of ultrasonic waves or processing the received signals of the ultrasonic wave detection units (121 to 12N) or the two ultrasonic wave detection units (221 to 22M) The ultrasonic signals transmitted from the units 121 to 12N may be received by the respective ultrasonic units 221 to 22M of the two ultrasonic groups or may vary in reception sensitivity.

The interfacial measuring apparatus according to the present invention can be applied to a height measurement of a foreign matter layer such as a filtration layer or a sediment layer in the form of a solid formed artificially or naturally in a liquid. The foreign matter layer forms an interface with the liquid while forming a layer having a height inside the liquid such as water. The foreign matter may have fluidity, and the interface may be changed by the flow of the foreign matter. As described above, the interface formed by the foreign matter layer can be a stop interface or a moving interface, and the ultrasonic interface measuring apparatus can be applied to the measurement of the stop interface or the moving interface. Especially, .

The liquid such as water can be stored while forming the storage level WL inside the storage container R such as filter paper. An interface (CL) can be formed by disposing a foreign material such as activated carbon for filtering the water of the filter paper into the liquid and discharging it to the discharge unit (16). The interface CL can be made in a variety of shapes, for example, be inclined or wavy. The interface can also have fluidity or mobility due to various causes. 1 ultrasonic module 10 includes a linear member 11 extending linearly at least partially in the shape of a hollow tube and a plurality of ultrasonic units 11 arranged in a lower portion of one linear member 11, (121-12N). 1 linear member 11 may have a structure extending in the vertical direction from the bottom surface BL of the storage container R and the plurality of ultrasonic units 121 to 12N of the one ultrasonic group may be structured so as to extend in a direction perpendicular to the one linear member 11, At a predetermined height from below. For example, the ultrasonic units 121 to 12N of the first ultrasonic group may be arranged at regular intervals from the bottom of the activated carbon layer to the storage level WL above the interface CL. Ultrasonic waves may be transmitted in a predetermined direction by the ultrasonic units 121 to 12N of the first ultrasonic wave group, or ultrasound signals transmitted at certain positions may be received.

2 ultrasonic module 20 may be disposed at a position capable of receiving the ultrasonic signal transmitted from the ultrasonic module 10. For example, one ultrasonic module 10 may be disposed on one wall surface of the filter paper, and a second ultrasonic module 20 may be disposed on the opposite wall surface. The ultrasonic signal transmitted from the first ultrasonic module 10 may be received by the second ultrasonic module 20 through the liquid. The ultrasonic signal transmitted from the second ultrasonic module 20 may be received by the first ultrasonic module 10. In this way, the two ultrasonic module 20 can be made to have the same or similar structure as the one ultrasonic module 10. Specifically, the two-ultrasonic module (20) includes a two-linear member (21) extending linearly into a hollow tube structure; And a plurality of ultrasonic units 221 to 22M of two ultrasonic wave groups arranged at regular intervals from the lower side of the two linear members 21. [ The ultrasonic units 121 to 12N of the first ultrasonic group and the ultrasonic units 221 to 22M of the second ultrasonic group can be arranged at the same height but can be arranged in various ways depending on the properties of the storage container R or the interface CL And can be arranged in various numbers in the position.

The ultrasonic signals transmitted from the ultrasonic units 121 to 12N of one ultrasonic group may not be received by the respective ultrasonic units 221 to 22M of the two ultrasonic groups according to the height of the interface CL. For example, the ultrasonic signals transmitted by the ultrasonic units 121 to 12N of the first ultrasonic group located below the interface CL are not received by the ultrasonic units 221 to 22M of the second ultrasonic group. On the other hand, the ultrasonic signals transmitted by the ultrasonic units 121 to 12N of the one ultrasonic group located above the interface CL are transmitted to the ultrasonic units 221 to 22M of the two ultrasonic groups located above the interface CL Lt; / RTI > The ultrasonic wave passing through the foreign substance may differ from the ultrasonic wave receiving sensitivity not passing through the foreign substance depending on the characteristics of the foreign substance. In addition, the sensitivity of the ultrasonic signal may be different depending on the amount of foreign matter present. For example, washing water may be introduced into the inlet 15 for backwashing, whereby the activated carbon can be expanded. Thereby, the interface CL can be moved, and the interface CL can be made in various shapes. If the ultrasonic signals transmitted by the ultrasonic units 121 to 12N of the first ultrasonic group located below the interface CL are not received by the ultrasonic units 221 to 22M of the two ultrasonic groups or the reception sensitivity is weakened have. The number or height of the ultrasonic units 121 to 12N of the first ultrasonic wave group in which the ultrasonic signals are not received may vary depending on the change of the interface CL. As described above, the change in the height of the interface can be detected according to the change in the form in which the ultrasonic signals transmitted at different heights are received at different heights.

Each of the ultrasonic units 121 to 12N of the one ultrasonic group and the ultrasonic units 221 to 22M of the two ultrasonic groups are connected to each other through a transmission cable CA disposed inside the linear members 11 and 21 And the processing unit 13 may be connected to the processing unit 13. The processing unit 13 may control the transmission of ultrasonic waves of the ultrasonic units 121 to 12N of one ultrasonic group or the ultrasonic units 221 to 22M of the two ultrasonic groups, Can be processed. For example, the processing unit 13 transmits ultrasonic signals in order from the lower side of the ultrasonic units 121 to 12N of one ultrasonic group, and transmits the ultrasonic signals at the corresponding heights of the ultrasonic units 221 to 22M of the two ultrasonic groups It can confirm whether or not it is received. In addition, the reception sensitivity of each ultrasonic signal can be confirmed. Then, a change in the height at which the ultrasonic signal transmitted by the ultrasonic wave units 121 to 12N of the first ultrasonic wave group is received, the initial height at which the ultrasonic wave is not received, or the height at which the ultrasonic wave can not be received can be confirmed and transmitted to the interface determination unit 14 . Thereafter, the interface determining unit 14 can determine the change in the height of the interface, the rate of change in height, or the rate of expansion of the activated carbon depending on the result processed in the processing unit 13. [ The processing unit 13 and the interface determination unit 14 may be disposed outside the storage container R and may include various types of central processing units or operating programs.

The ultrasonic interface measuring apparatus according to the present invention may be installed in various liquid storage containers to measure the height or height change of the stop interface or the moving interface.

FIG. 2 shows an embodiment in which the ultrasonic interface measuring apparatus according to the present invention is applied to a backwashing process of filter paper.

2, the processing unit 13 for controlling the operation of the ultrasonic interface measuring apparatus includes a control unit 21a for controlling the operation of the ultrasonic unit; A height setting unit (22) for determining the height of the ultrasonic unit from which the ultrasonic signal is generated; A transmission adjusting unit 23 for adjusting the ultrasonic signal to be generated in the ultrasonic unit determined by the height setting unit 22; A reception detection unit (24) for determining an ultrasonic unit for reception of an ultrasonic signal transmitted from an ultrasonic unit disposed at different heights; A reception sensitivity determination unit 25 for determining whether a signal is received by the reception detection unit 24 or the sensitivity of the received signal; And a confirmation unit (26) for confirming the operation of the ultrasonic unit when the ultrasonic signal of one of the signals transmitted from the ultrasonic unit disposed at the adjacent heights is received and the other ultrasonic signal is not received . And the result received and processed by the processing unit 13 may be transmitted to the interface determination unit 14. [

The interface determination unit 14 determines an interface at various positions according to the height calculated by the reception height calculation unit 27 and the reception height calculation unit 27 that determine the reception height in accordance with the processing result in the processing unit 13 And an interfacial calculation unit 28 that performs interfacial calculation.

During the backwashing of the filter paper, the interface of the activated carbon can be moved, and the interface can have different heights at different positions of the water surface. Therefore, an ultrasonic signal can be periodically generated from the ultrasonic units disposed at different heights, and the ultrasonic unit for periodically transmitting the ultrasonic waves can be determined by the period setting unit 211. The height setting unit 22 may determine the height of the ultrasonic unit that transmits the ultrasonic wave. For example, it is possible to prevent ultrasonic waves from being generated in the ultrasonic wave unit disposed below the interface. Also, it is possible to prevent ultrasonic waves from being transmitted from the ultrasonic unit disposed above the ultrasonic unit for the first time to receive ultrasonic waves. If the ultrasonic wave generating unit 22 determines that the ultrasonic wave generating unit should generate the ultrasonic wave, the connection and connection period of the ultrasonic wave generating unit, which should generate the ultrasonic wave by the transmission adjusting unit 23, can be determined. The reception detection unit 24 can confirm whether or not the ultrasonic wave is received in the ultrasonic unit disposed at a position corresponding to the height at which the ultrasonic wave is transmitted. In the backwashing process, the interface of activated carbon does not have a constant shape and the height of the interface may be different at different positions of the plane. Therefore, it is necessary to compare the sensitivity of the ultrasonic wave received in the state that the activated carbon is not inflated and the receiving sensitivity of the ultrasonic wave received at the specific height in the state that the activated carbon is expanded. When the reception sensitivity of the ultrasonic signal received and received at a specific position changes, an ultrasonic signal is transmitted by the ultrasonic unit arranged at the adjacent height by the confirmation unit 26, so that the height of the interface or the height change of the interface can be confirmed. The receiving height can be calculated by the receiving height calculating unit 27 based on whether the ultrasonic signal is received or the receiving sensitivity is changed. And the interface can be calculated by the interface calculation unit 28 at various plane positions.

This interface calculation process is described below.

FIG. 3 illustrates an embodiment in which the ultrasonic interface apparatus according to the present invention is installed on a filter paper.

Referring to FIG. 3, one ultrasonic module 10 in which ultrasonic units 121, 122, and 123 are disposed in a lower portion may be disposed on the wall surface of the filter paper 31. The two ultrasonic modules can be disposed at positions where the ultrasonic signals transmitted to the ultrasonic units 121, 122 and 123 disposed at different heights of the ultrasonic module 10 can be received. For example, It may be disposed on another wall surface. A plurality of troughs 32a, 32b and 32c can be arranged in the filter paper 31 and activated carbon can be arranged on the bottom surface of the filter paper 31. [ After being purified in the filter paper 31 for a certain period of time, the activated carbon should be washed backwashing to remove impurities accumulated in the activated carbon. For backwashing, the wash water may flow backward from the bottom of the filter paper. As a result, the activated carbon may expand and the interface may change. Activated carbon is located in the water in the filter paper, and the interface of the expanding activated carbon is not observed from the outside due to the scale of the filter paper. If the interface of the activated carbon is out of the predetermined level in the backwashing process, the activated carbon may be lost through the troughs 32a, 32b, and 32c for draining the washing water. In order to prevent this, the expansion rate of activated carbon needs to be detected. The ultrasonic interface measuring apparatus according to the present invention can detect the expansion rate of the activated carbon in the backwashing process, and thus the backwashing process can be controlled.

4 shows an embodiment of the ultrasonic interface measuring method according to the present invention.

Referring to FIG. 4, the ultrasonic interface measuring method includes: (P41) transmitting ultrasonic waves at different times at different heights of water; Detecting whether the ultrasonic signals of different heights are received (P42); Determining a limit height at which the ultrasonic signal is received (P43); And a step (P44) of determining a height of an interface which changes in the water or the water formed in the water based on the limit height.

The ultrasonic interface measuring method according to the present invention may have a function of measuring the interface of the fluid material disposed inside the liquid and having fluidity and forming an interface at different heights of the inside of the liquid. For example, activated carbon or granular activated carbon for preventing impurities may be arranged at a predetermined height from the bottom surface of a filtering paper of a water treatment plant. Activated carbon placed on the filter paper has the function of removing fine contaminants and needs to be backwashed, for example, on a weekly or monthly basis. Backwashing can be done with air and water, and the activated carbon expands during backwashing. The expansion of the activated carbon needs to be maintained at 20 to 70%, for example. If the expansion rate deviates from a predetermined level during backwashing, it may be lost through a trough installed for drainage of backwash water. Therefore, in the course of backwashing, the expansion rate of the activated carbon or the interface of the activated carbon must be accurately detected, and thus the backwashing process needs to be controlled. The ultrasonic interface measurement method according to the present invention is applied to the interface measurement of the activated carbon disposed on the filter paper, but is not limited thereto.

The interface measuring method according to the present invention can be applied to the interface measurement of various solid or solid similar materials formed in a liquid. Therefore, the present invention can be applied to various interface measurements formed inside a liquid, including the expansion rate of activated carbon, and is not limited to the embodiments shown.

A plurality of ultrasonic units may be arranged at a predetermined height from below the interface, and a plurality of ultrasonic units may be arranged using, for example, the linear member described above. Ultrasonic waves can be transmitted in water from the respective ultrasonic units sequentially at predetermined time intervals (P41). The ultrasonic signals transmitted from the ultrasonic units at different heights at different times can be received by the receiving ultrasonic units arranged at different positions (P42). The receiving ultrasonic wave unit can be arranged to correspond to the height of the transmitting ultrasonic wave unit, and the transmitting ultrasonic wave unit can be detected whether or not the transmitting ultrasonic wave wave is received by the receiving ultrasonic wave unit disposed at a predetermined height via the liquid (P42). If the ultrasonic signal generated by the transmitting ultrasonic wave unit arranged at the 1-height is received by the receiving ultrasonic wave unit arranged at 1-height, the interface can be predicted to be located below the 1-height. On the other hand, if the ultrasonic signal is not received by the receiving ultrasonic wave unit disposed at the first height, or if the ultrasonic signal is received very weakly, the interface may be estimated to be higher than at least one height.

The transmitting ultrasonic wave unit and the receiving ultrasonic wave unit are arranged at the corresponding heights of the activated carbon from the interface of the initial activated carbon so that the activated carbon expansion rates are 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% . At each position, the ultrasonic signals are transmitted at different times (P41), and the reception ultrasonic units disposed at positions corresponding to the respective heights can be detected (P42). If the height at which the ultrasonic signal is received and the height at which the ultrasonic signal is not received are determined in this way, it can be assumed that the interface is located therebetween. Therefore, the limit height at which ultrasonic waves are received can be determined to determine the range of the interface (P43). When the limit height is determined, the interface height at the current point of the activated carbon can be determined accordingly (P44).

During the backwashing process, the interface height continuously changes, and ultrasound signals can be periodically transmitted from different transmission ultrasonic units. The height of the interface can be determined according to whether ultrasonic signals arranged at adjacent heights are received or not, and such height can be measured and analyzed according to the change of time. Depending on the results of the analysis, the rate of introduction of the wash water can be determined, and thus the backwashing process can be appropriately controlled.

The ultrasonic interface measurement method according to the present invention can be applied to measurement of a stationary interface or a moving interface in various liquids, and the present invention is not limited to the embodiments shown.

The ultrasonic interface measuring apparatus according to the present invention enables the ultrasonic wave detecting unit to accurately measure the level of activated carbon in the filter paper or the expansion rate in the course of backwashing. The interfacial measuring apparatus according to the present invention accurately detects whether the level or the expansion rate of the activated carbon has reached a predetermined range in the backwashing process, thereby preventing the loss of activated carbon. The interface measuring apparatus according to the present invention makes it possible to perform interfacial measurement of various precipitates formed in water which are difficult to be measured by laser, microwave or other electromagnetic waves.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention . The invention is not limited by these variations and modifications, but is limited only by the claims appended hereto.

10: 1 ultrasonic module 11: 1 linear member
13: processing unit 14: interface determination unit
15: inlet 16: exhaust unit
20: 2 ultrasonic module 21: 2 linear member
21a: control unit 22: height setting unit
23: transmission control unit 24: reception detection unit
25: reception sensitivity determination unit 26: confirmation unit
27: reception height calculating unit 28: interface calculation unit
31: filter paper 32a, 32b, 32c:
121, 122, 123: Ultrasonic unit
121 to 12N: 1 ultrasonic detecting unit, 1 ultrasonic group ultrasonic unit
211: Period setting unit
221 to 22M: two ultrasonic detecting units, two ultrasonic wave group ultrasonic units
BL: Floor surface CA: Transmission cable
CL: Interface R: Storage container
WL: Storage level

Claims (1)

An apparatus for measuring an interface of a foreign matter formed in a liquid,
A plurality of ultrasonic units (121 to 12N) of one ultrasound group arranged at predetermined predetermined heights of one linear member (11) extending vertically from the bottom surface of the storage vessel at least partially in a hollow tube shape;
Linear members (11) and two linear members (21) vertically extending from the bottom surface of the storage vessel at least partially in a hollow tube shape. A plurality of ultrasonic units 221 to 22M; And
And a processing unit (13) for controlling transmission of ultrasonic waves of the ultrasonic units (121 to 12N) of one ultrasonic group or ultrasonic units (221 to 22M) of the two ultrasonic groups,
The ultrasonic signals transmitted from the respective ultrasonic units 121 to 12N of the one ultrasonic wave group are received or changed in sensitivity by the position of the interface by the ultrasonic wave units 221 to 22M of the two ultrasonic wave groups,
The foreign matter is activated carbon disposed inside the settlement paper, and the plurality of ultrasonic units 121 to 12N and 221 to 22M of the first and second ultrasonic wave groups are disposed in the water of the settlement paper,
The processing unit 13 includes a period setting unit 211 for determining an ultrasonic generation period of the ultrasonic unit and a height setting unit 22 for determining an ultrasonic unit to generate ultrasonic waves in accordance with the height of the interface,
Further comprising an interfacial determination unit (14) for determining an expansion rate of the activated carbon according to a result processed by the processing unit (13), wherein the washing water is used for controlling the backwashing process for the activated carbon so that the expansion rate does not exceed a predetermined level Is set to a predetermined value.

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