JP2007155458A - Filtration membrane breakage detector, membrane filtration device and filtration membrane breakage detection method - Google Patents

Abstract

An inexpensive filtration membrane breakage detector, a membrane filtration device, and a filtration membrane breakage detection method capable of quickly detecting that a breakage or damage has occurred in a filtration membrane are provided.
A signal processing unit 20 outputs a high-frequency transmission signal, and an ultrasonic transducer 12 flows out an ultrasonic transmission wave obtained by converting the transmission signal from a membrane filtration module 4 including a filtration membrane. Send to permeate. Then, the ultrasonic transducer 12 receives the reflected wave from the transmitted water and converts it into a reflected signal, and the signal processing unit 20 determines the presence of particles in the transmitted water based on the reflected signal, and Based on the determination result, it is detected that the filtration membrane is broken or damaged.
[Selection] Figure 2

Description

  The present invention relates to a filtration membrane breakage detector, a membrane filtration device, a filtration membrane breakage detection method, and a leak detector for a filtration module, and in particular, an inexpensive filtration membrane breakage that can quickly detect that a filtration membrane is broken or damaged. The present invention relates to a detector, a membrane filtration device, a filtration membrane breakage detection method, a leak detector for an inexpensive filtration module that can quickly detect that a leak has occurred in a membrane filtration module, a membrane filtration device, and a leak detection method for a filtration module.

  Membrane filtration is a water treatment method in which raw water is filtered through a filtration membrane having predetermined pores to obtain filtered water having a low impurity content, and clear water can be obtained with relatively simple equipment. Many membrane filtration apparatuses are provided with a plurality of membrane filtration modules obtained by modularizing a large number of filtration membranes made of hollow fiber membranes, and the required filtration water amount is obtained by operating these membrane filtration modules in parallel.

  When raw water is subjected to a coagulation sedimentation process or a sand filtration process, relatively large solids are removed. However, fine particles (impurity particles) made of solid matter, bacteria, bacteria or their dead bodies and suspended or suspended in the raw water are not removed much. However, according to the membrane filtration treatment, by appropriately selecting the pores of the filtration membrane to be used, most of the impurity particles are removed, and clear filtered water suitable for purposes such as drinking and precision washing can be obtained. .

  However, the filtration membrane may be damaged or damaged (cutting, partial laceration, pitting corrosion, etc.) due to deterioration with time or operation mistake of the membrane filtration device. If the filtration membrane is left damaged or damaged, the raw water leaks to the filtered water side, causing impurity particles to enter the filtered water, and the quality of the filtered water deteriorates. Moreover, in a membrane filtration apparatus, the connection part etc. which divide raw | natural water and filtered water etc. deteriorate in a membrane-type filtration module, and a leak may arise.

  Therefore, in order to prevent deterioration of filtered water quality, it is necessary to quickly detect the occurrence of breakage or damage of the filtration membrane and always verify the integrity of the filtration membrane (no leakage due to breakage or damage). . If breakage or damage of the filtration membrane can be detected quickly, the membrane filtration treatment with this filtration membrane can be stopped immediately to prevent degradation of the filtered water quality, and furthermore, measures such as repair and replacement can be taken promptly. It also leads to maintenance. Further, in the membrane filtration module, it is preferable that leakage due to breakage or damage of the filtration membrane can be detected as well as leakage due to other causes.

Conventionally, for example, the following method is known as a method for testing the integrity of a filtration membrane module (see Non-Patent Document 1).
First method: A method of optically measuring the number (or number and size) of fine particles in filtered water (treated water) (“fine particle measurement method”, “fine particle observation method”).
Second method: A method of optically measuring the turbidity of filtered water using a turbidimeter ("turbidity observation method").
Third method: A method in which pressure is applied to one side of the filtration membrane and the behavior and changes at that time are observed (“pressure hold method”, “bubble point method”, “sonic wave survey method”).

  Conventionally, a part of the permeate flowing out from the membrane filtration device is introduced into the membrane module, and the number of fine particles per unit volume of the concentrated water flowing out from the membrane module is measured using a light scattering type optical particle meter. A film breakage detection device that counts and detects film breakage based on the counted number of fine particles is known (see Patent Document 1).

JP-A-8-252440 (paragraphs 0028 and 0031, FIG. 1) Supervised by the Membrane Separation Technology Promotion Association, Membrane Water Purification Committee, edited by the Water Purification Membrane Editorial Committee, "Purified Water Membrane", Gihodo Publishing, June 2003, pp.195-196

  However, since the first method described above optically captures particles, there is a problem in that it is difficult to align and adjust the light source, light receiving sensor, and optical system of the detector. In addition, there is a problem that the detection or inaccuracy may occur due to fogging due to impurities or the like adhering to the light projecting surface or the light receiving surface. Furthermore, since the light receiving sensor and the optical system are generally expensive, the detector is also relatively expensive.

  In general, the membrane filtration apparatus includes a large number of filtration membrane modules. However, it is expensive to install expensive detectors in all the filtration membrane modules. Therefore, when it is decided to provide a small number of detectors, it is necessary to search by changing the detection position or to change the sampling position of the filtrate water in order to identify the filtration membrane module in which the leak has occurred. In addition to the time and effort, there is a problem that rapid detection is not possible.

  Further, since the second method described above uses an optical method, there is a problem similar to that of the first method described above. Furthermore, since the amount of particles per unit volume in filtered water is indirectly observed by scattering and transmission of visible light, it takes time to obtain detection results, and the sensitivity is low in low turbidity regions. was there.

  In addition, in the third method described above, it is necessary to interrupt the membrane filtration every time the test is performed and to apply a pressure difference to the filtration membrane. Therefore, the filtration membrane cannot be continuously monitored for breakage or damage. There was a problem that it took time to discover breakage and damage. In addition, every time a test is performed, the membrane filtration process is interrupted, so it takes time to operate and restart the filtration device, and the supply of filtered water is suspended during the test. There was a problem of decreasing.

  Further, in the conventional membrane breakage detection device (described in Patent Document 1), a line for branching the permeate and a membrane module for obtaining the concentrate from the permeate are installed in order to obtain the concentrate for detection. ing. For this reason, there has been a problem that the configuration becomes complicated and management takes time. In addition, there is a problem that it takes time from the occurrence of leakage until the fine particles being concentrated for detection are concentrated to a concentration sufficient to detect the leakage. Further, since this film breakage detection apparatus uses a light scattering type optical particle meter, there is a problem similar to that of the first method described above.

Accordingly, an object of the present invention is to provide an inexpensive filtration membrane breakage detector, a membrane filtration device, and a filtration membrane breakage detection method that can quickly detect that a breakage or damage has occurred in a filtration membrane.
Furthermore, an object of the present invention is to provide an inexpensive filtration module leakage detector, a membrane filtration device, and a filtration module leakage detection method capable of quickly detecting that a leakage has occurred in the membrane filtration module.

  The filtration membrane breakage detector of the present invention transmits an ultrasonic transmission wave to the permeated water that has flowed out of a membrane filtration device that obtains permeated water by filtering raw water through a filtration membrane, and based on the reflected wave from the permeated water The presence of particles in the permeated water is determined, and it is detected that the filtration membrane is broken or damaged based on the determination result of the particles.

  The membrane filtration device of the present invention includes a plurality of membrane filtration modules including a filtration membrane that filters raw water to obtain permeated water, and a book provided with a communication device that is respectively inserted downstream of the plurality of membrane filtration modules. A plurality of filtration membrane breakage detectors of the invention, and a receiving device that receives a detection signal indicating that the filtration membrane is broken or damaged from the filtration membrane breakage detector, and performs control based on the detection signals And a control device.

  The filtration membrane breakage detection method of the present invention transmits an ultrasonic transmission wave to the permeated water that has flowed out of a membrane filtration device that obtains permeated water by filtering raw water through a filtration membrane, and is based on the reflected wave from the permeated water. The presence of particles in the permeated water is determined, and it is detected that the filtration membrane is broken or damaged based on the determination result of the particles.

According to the present invention, it is possible to provide an inexpensive filtration membrane breakage detector, a membrane filtration device, and a filtration membrane breakage detection method that can quickly detect that the filtration membrane is broken or damaged.
Further, according to the present invention, it is possible to provide an inexpensive filtration module leakage detector, a membrane filtration device, and a filtration module leakage detection method capable of quickly detecting that a leakage has occurred in the membrane filtration module.

Next, embodiments according to the present invention will be described in detail with reference to the drawings.
(First embodiment)
First, with reference to FIG. 1, the structure and process flow of the membrane filtration apparatus 100 of 1st Embodiment are demonstrated.

  The membrane filtration apparatus 100 filters raw water W1 taken from a river or the like with a filtration membrane to generate filtered water W2 to be used as supply water in the raw water W1. The raw water tank 1 and a water pump 2 And N valves 3, N membrane filtration modules 4, and N filtration membrane breakage detectors 10. Here, N is a natural number of 1 or more.

  The smaller the number (= N) of the valve 3, the membrane filtration module 4, and the membrane breakage detector 10, the simpler the membrane filtration device 100 and the lower the installation and maintenance costs. . As the number of sets (= N) is increased, the processing capacity of the membrane filtration device 100 is increased, and when the maintenance work is performed on some membrane filtration modules 4, the reduction rate of the processing capacity is small. I'll do it.

  The raw water tank 1 receives and stores raw water W1 from rivers and lakes outside the membrane filtration device 100. As described above, the raw water W1 contains impurity particles. If coagulation sedimentation processing or sand filtration processing is performed in advance before the raw water W1 is received in the raw water tank 1, relatively large solids are removed, and the load on the membrane filtration module 4 can be reduced.

  The water pump 2 is a power pump and has a function of sucking the raw water W1 from the raw water tank 1 and extracting it through the water pipe. The water pump 2 further includes a control panel (not shown) for controlling the operation of the water pump 2 and a communication device (not shown) connected to the control board.

  The water supply pipe from the water supply pump 2 is branched into N pipes 11 and converged again to one water discharge pipe. As will be described later, the raw water W1 pumped out from the water pipe of the water pump 2 is subjected to membrane filtration treatment by the membrane filtration module 4 inserted in each of the pipes 11 to become filtered water W2, and merges again. As supply water, water is sent out of the membrane filtration device 100 through a drain pipe.

  A valve 3, a membrane filtration module 4, and a filtration membrane breakage detector 10 are inserted in the N branched pipes 11 in the order of the water supply direction. In addition to the valve 3 or instead of the valve 3, a similar valve (not shown) may be inserted downstream of the membrane filtration module 4.

  The valve 3 is an open / close valve and has a function of opening and closing the pipe 11. The valve 3 further includes an actuator for switching the open / close state, a control panel for controlling the actuator, and a communication device (none of which is shown) connected to the control panel.

  The membrane filtration module 4 includes a filtration membrane (not shown), and has a membrane filtration function of filtering the pumped raw water W1 through this filtration membrane to remove impurity particles in the raw water W1 and generating filtered water W2. Have. The membrane filtration module 4 is typically a hollow fiber membrane module including a number of hollow fiber membranes, and the raw water W1 circulates in the hollow fiber membranes and permeates through the pores of the hollow fiber membranes. Is filtered out as filtered water W2, and a large amount of impurities and suspensions that cannot permeate the pores is discharged out of the treatment system as concentrated water. The filtration membrane is, for example, an MF membrane (microfiltration membrane) or a UF membrane (ultrafiltration membrane), and the form thereof may be any of a flat membrane, a spiral membrane, a pleated membrane, etc. in addition to a hollow fiber membrane. .

  Since the pores of the filtration membrane are small enough to remove most impurities and suspensions such as bacteria, according to the membrane filtration module 4, filtered water having suitable water quality, for example, for drinking water. W2 is obtained. This filtration membrane basically has few failures and high reliability, but may be broken or damaged due to deterioration over time or operational errors. If this breakage or damage is left untreated, the raw water W1 is mixed in the filtrate W2, and the quality of the filtrate W2 is deteriorated. Therefore, as described below, the filtration membrane breakage detector 10 is provided so that breakage and damage of the filtration membrane can be detected quickly.

  The filtration membrane breakage detector 10 has a function of detecting that breakage or damage has occurred in the membrane filtration module 4 by determining the presence of impurity particles in the filtered water W2. Since the raw water W1 contains impurity particles and the filtrate water W2 contains almost no impurity particles, the fact that the filtrate water W2 contains impurity particles significantly indicates that the filtration membrane of the membrane filtration module 4 Means that the product is broken or damaged.

  Further, the filtration membrane breakage detector 10 may be used as a leak detector for a filtration module that detects that a leak has occurred in the membrane filtration module 4 by determining the presence of impurity particles in the filtrate water W2. . Since the raw water W1 contains impurity particles and the filtrate water W2 contains almost no impurity particles, the fact that the filtrate water W2 contains impurity particles significantly means that the membrane filtration module 4 leaks. Means that it is happening

  The filtration membrane breakage detector 10 transmits ultrasonic waves (transmission waves) to the filtered water W2 flowing out from the membrane filtration module 4, analyzes the reflected waves to determine the presence of impurity particles, and based on the determination result. To detect the breakage or damage of the filter membrane. The filtration membrane breakage detector 10 further has a communication function, and transmits a detection signal indicating the detection result to the control device 6. A detailed configuration example and operation example of the filtration membrane breakage detector 10 will be described later with reference to FIG.

  The control device 6 has a control function for controlling each part of the membrane filtration device 100, and each of the water supply pump 2, the N valves 3, and the N filtration membrane breakage detectors 10 is wired or wirelessly, A communication device (not shown) capable of communicating on a separate channel is included.

  When the control device 6 receives a detection signal indicating breakage or damage of the membrane filtration module 4 from any one of the filtration membrane breakage detectors 10, the control device 6 moves to the valve 3 positioned on the upstream side of the filtration membrane breakage detector 10. Send a close order. When the valve 3 receives the closing command, the valve 3 enters a closed state and stops water supply through the pipe 11, so that the membrane filtration process in the membrane filtration module 4 located on the downstream side is stopped.

  Thus, the membrane filtration process in the membrane filtration module 4 that has been damaged or damaged is stopped, so that the raw water W1 is not mixed into the filtrate W2, and the filtrate W2 (feed water) flowing out from the membrane filtration device 100 is removed. Water quality deterioration is prevented. Further, the processing in the membrane filtration module 4 that has been damaged or damaged is stopped, but the processing in the other membrane filtration module 4 can be continued, so that the reduction in the processing capacity can be minimized. In this case, it is preferable to adjust the pressure applied to the other membrane filtration module 4 by adjusting the opening degree of the valve 3 other than the closed one.

  When the control device 6 detects a serious failure in the membrane filtration device 100 such as receiving a detection signal indicating breakage or damage from the filtration membrane breakage detector 10 exceeding a predetermined number, the control device 6 operates the water pump 2. A control signal indicating a stop command is transmitted. Thus, since the water pump 2 is stopped and the water supply of the raw water W1 is stopped, the membrane filtration process in the membrane filtration device 100 is stopped. Furthermore, when the control device 6 detects any failure including the above in the membrane filtration device 100, the control device 6 may transmit that fact to the outside of the membrane filtration device 100.

According to the membrane filtration device 100, the following effects can be obtained.
(1) By disposing the filtration membrane breakage detector 10 close to the membrane filtration module 4, it is possible to more quickly detect that the filtration membrane is broken or damaged.
(2) Since the filtration membrane breakage detector 10 can be manufactured at a low cost as described later, it can be attached to all the membrane filtration modules 4 at a low cost. Therefore, the membrane filtration device 100 that can quickly identify the membrane filtration module 4 in which breakage or damage has occurred can be constructed at low cost.
(3) Since the valve 3 on the upstream side of the membrane filtration module 4 in which breakage or damage has occurred is selectively closed, it is possible to locally reduce the processing capacity while preventing contamination of the filtered water W2 serving as supply water.
(4) The number of membrane filtration modules 4 can be increased to increase the processing capacity, and the number of membrane filtration modules 4 can be reduced to make a simple configuration.
(5) Since the filtered water W2 is constantly monitored, there is no need to stop the operation accompanying the inspection. For this reason, the occurrence of breakage or damage of the filtration membrane and the occurrence location thereof can be quickly identified, labor can be saved in the inspection, and the loss of processing capacity and the deterioration of water quality associated with the inspection and maintenance can be reduced.
(6) By using the filtration membrane breakage detector 10 as a leak detector for the filtration module, it is possible to more quickly detect that the membrane filtration module 4 has leaked, and the effects (2) to (5) described above. Is obtained in the same way.

  Next, the filtration membrane breakage detector 10 will be described in detail with reference to a cross section of the filtration membrane breakage detector 10 shown in FIG. 2 cut along the longitudinal direction of the pipe 11 (see FIG. 1) (appropriately, FIG. 1). In addition, in the piping 11 shown in FIG. 2, the filtrate W2 shall flow in from the left hand side (upstream side), and shall flow out to the right hand side (downstream side).

  The filtration membrane breakage detector 10 includes a part of the piping 11 on the downstream side of the membrane filtration module 4, an ultrasonic transducer 12, a signal processing unit 20 connected to the ultrasonic transducer 12, and a rectifier. 13. In order to quickly detect the occurrence of breakage or damage of the filtration membrane, the length of the pipe 11 from the membrane filtration module 4 to the filtration membrane breakage detector 10 is preferably short.

  The ultrasonic transducer 12 converts the high-frequency electrical signal (transmission signal) from the signal processing unit 20 into an ultrasonic wave (transmission wave) and outputs the ultrasonic wave (reflected wave) reflected from the filtered water W2. ) Is converted into a high-frequency electric signal (reflected signal) and output to the signal processing unit 20. For the ultrasonic transducer 12, for example, a piezoelectric ultrasonic transducer including a piezoelectric element can be used. Piezoelectric ultrasonic transducers are generally inexpensive, and can be immersed in the filtered water W2 for a long period of time, so that maintenance work can be saved. Furthermore, since an ultrasonic wave is used, unlike an optical sensor, there is no problem that the detection accuracy is lowered due to fogging of a light receiving window or the like. The ultrasonic transducer 12 is held in the pipe 11 by a support member (not shown) with the ultrasonic transmission / reception surface facing downstream.

  The ultrasonic transducer 12 is a converging type, and the transmission / reception beam of the ultrasonic transducer 12 is at a predetermined position (distance and direction) with respect to the transmission surface of the ultrasonic transducer 12. Focus on a certain focal point F. Therefore, at the focal point F, the energy density of the transmission wave is maximized. Further, when the particle P is located at the focal point F, the gain of the reflected signal is maximized. Specifically, the ultrasonic transducer 12 is of a converging type by making the transmission / reception surface concave or adding an ultrasonic lens.

  The rectifier 13 has a funnel shape and provides a convergence function for converging the filtrate W2 and a rectification function for stabilizing the flow. The opening on the upstream side of the rectifier 13 opens with a diameter slightly larger than the diameter of the ultrasonic transducer 12 (the dimension in the same direction as the radial direction of the pipe 11). A part of the ultrasonic transducer 12 including the ultrasonic transmission / reception surface is inserted into the upstream opening, and an inlet channel 13 i is formed by a gap between the ultrasonic transducer 12 and the rectifier 13. The opening on the downstream side of the rectifier 13 is narrowed to such an extent that it does not substantially affect the intensity distribution of the focused ultrasonic wave, and an outlet channel 13o is formed in this opening. The rectifier 13 is held in the pipe 11 by a support member (not shown) so that the focal point F of the ultrasonic transducer 12 is located in the outlet channel 13o.

  In the filtration membrane breakage detector 10, a part of the filtered water W2 flows into the inlet channel 13i, converges and rectifies inside the rectifier 13, and flows out from the outlet channel 13o. For this reason, the flow and flow velocity of the filtrate water W2 are stabilized in the outlet channel 13o. Therefore, the particles P that have flowed in from the inlet flow path 13i together with the filtered water W2 are collected by the rectifier 13 into the outlet flow path 13o, and pass through the vicinity of the focal point of the ultrasonic transducer 12 with a constant moving direction and speed. Become.

  For this reason, when the membrane of the membrane filtration module 4 is broken or damaged, and the raw water W1 leaks to the filtered water W2, the impurity particles contained in the raw water W1 pass through the vicinity of the focal point F of the ultrasonic transducer 12. To do. Since the transmission wave from the ultrasonic transducer 12 is repeatedly transmitted, when the impurity particles pass near the focal point F, the transmission wave is reflected with strong energy. Then, the reflected wave of this transmission wave is received by the ultrasonic transducer 12.

  The signal processing unit 20 generates a transmission signal at a predetermined timing and transmits the transmission signal to the ultrasonic transducer 12, and analyzes the reflection signal from the ultrasonic transducer 12 to determine the presence of impurity particles. Based on the result, it has a function of detecting the occurrence of breakage or damage of the filtration membrane, is installed outside the pipe 11, and is electrically connected to the ultrasonic transducer 12.

  As shown in FIG. 3, the signal processing unit 20 includes a timing signal generator 201, a transmission waveform memory 211, a DA converter 212, an amplifier 213, a transmission / reception switch 221, a delay 231, and a reception The amplifier 241, the mixer 232, the A / D converter 233, the A / D converter 243, the mixed waveform memory 234, the reflected waveform memory 244, the analyzer 251, and the communication device 252 are configured. ing.

  The timing signal generator 201 generates a timing signal that serves as a reference for the operation timing of each unit in the signal processing unit 20 and supplies the timing signal to each unit. Hereinafter, the period in which the timing signal gives the operation timing is referred to as a timing period.

The transmission waveform memory 211 stores waveform data (transmission signal data) for at least one pulse, and outputs transmission signal data for one pulse to the DA converter 212 during one timing period. .
The DA converter 212 performs digital-analog conversion on the transmission signal data to generate a transmission signal.
The amplifier 213 amplifies the transmission signal to a level at which a sufficient ultrasonic output can be obtained by the ultrasonic transducer 12 (see FIG. 2), and outputs the amplified transmission signal to the transmission / reception switch 221.

  The transmission / reception switch 221 is a circuit for switching transmission / reception of ultrasonic waves. The transmission / reception switch 221 connects the amplifier 213 and the ultrasonic transducer 12 (see FIG. 2) when in the transmission state, and the ultrasonic transducer 12 (see FIG. 2) and the reception amplifier 241 when in the reception state. And connect. The transmission / reception switch 221 refers to the timing signal, and until a time corresponding to the pulse width Δt of the transmission signal elapses from the start of output of the transmission signal from the amplifier 213 (actually, there is some margin before and after these). During the added period). During other periods, the transmission / reception switch 221 is in a reception state. Thus, after the transmission / reception switch 221 enters the transmission state and the transmission wave is transmitted from the ultrasonic transducer 12, the transmission / reception switch 221 enters the reception state and is converted from the reflected wave by the ultrasonic transducer 12. A reflected signal is received.

  The reception amplifier 241 is a low-noise and low-distortion small-signal amplifier that amplifies the reflected signal input from the ultrasonic transducer 12 via the transmission / reception switch 221 to a level sufficient for subsequent processing, The data is sent to the mixer 232 and the reflected waveform memory 244.

  The delay unit 231 delays the transmission signal from the DA converter 212 by a predetermined delay time and outputs the delayed signal to the mixer 232. By performing the delay, the phase of the transmission signal (delayed transmission signal) input to the mixer 232 matches the phase of the reflected signal. The delay time can be obtained by calculating the time for the ultrasonic wave to reciprocate based on the distance from the ultrasonic transducer 12 to the focal point F and the sound speed in water, and adding the delay time of the circuit to this. You may obtain | require experimentally using the filtration membrane breakage detector 10 of.

  The mixer 232 mixes the delayed transmission signal and the reflected signal, and outputs a mixed signal obtained by extracting the low frequency to the AD converter 233. That is, the mixer 232 has a demodulation function for demodulating the reflected signal with reference to the delayed transmission signal, and the mixed signal represents the frequency difference of the reflected signal with respect to the frequency of the delayed transmission signal. In this way, the frequency change of the reflected wave is obtained, and this frequency change means the Doppler change of the ultrasonic wave due to the movement of the reflector.

The A / D converter 233 performs analog-digital conversion on the mixed signal to generate mixed waveform data, and outputs the mixed waveform data to the mixed waveform memory 234.
The mixed waveform memory 234 stores mixed waveform data for at least one pulse.
The AD converter 233 and the mixed waveform memory 234 are configured to process data in a reception time zone (a time zone in which the transmission / reception switch 221 is in a reception state) with reference to the timing signal, thereby reducing the circuit scale. Can be reduced.

The A-D converter 243 performs analog-digital conversion on the reflected signal to generate reflected waveform data, and outputs the reflected waveform data to the reflected waveform memory 244.
The reflected waveform memory 244 stores reflected waveform data for at least one pulse.
The AD converter 243 and the mixed waveform memory 234 are configured to process data in a reception time zone (a time zone in which the transmission / reception switch 221 is in a reception state) with reference to the timing signal, thereby reducing the circuit scale. Can be reduced.

  The mixed waveform memory 234 and the reflected waveform memory 244 refer to the timing signal and output mixed waveform data and reflected waveform data for one pulse to the analyzer 251 for each timing period.

  The analyzer 251 refers to the timing signal, analyzes the mixed waveform data and the reflected waveform data for each transmission / reception of ultrasonic waves, and breaks or damages the filtration membrane of the membrane filtration module 4 (see FIG. 1). Filter membrane damage determination processing (described later with reference to FIG. 7) is performed to determine whether or not this occurs, and the determination result is output to the communication device 252. The filtration membrane damage determination process includes a Doppler frequency detection process and a particle diameter calculation process based on a reflection intensity calculation.

  The communication device 252 transmits a detection signal to the control device 6 or another external device when a determination result indicating that the filter membrane is broken or damaged is input. The communication device 252 may further have a function of receiving a signal from the control device 6 or another external device and setting parameters used for each process in the analyzer 251.

  Next, with reference to FIG. 4, the concept of obtaining the moving speed of the impurity particles will be described for each signal in the signal processing unit 20. The timing of each signal is shown in the horizontal axis direction.

  The transmission signal shown in FIG. 4A is transmitted from the transmission start times t1, t3, t5,... Almost coincident with the operation timing supplied by the timing signal until the pulse width Δt elapses. The interval between the transmission start times t1, t3, t5,... Is the same as the timing period.

  The reflected signal shown in FIG. 4B is the transmission start times t1 and t3 described above, which is the time obtained by adding the time required for the ultrasonic waves to reciprocate the filtered water W2 from the ultrasonic transducer 12 to the focal point F and the circuit delay. , T5,... From the reception time t2, t4, t6,... Delayed until the pulse width Δt elapses.

  The delayed transmission signal shown in FIG. 4 (c) is a signal obtained by delaying the transmission signal shown in FIG. 4 (a) by a delay time corresponding to the reflected signal shown in FIG. 4 (b).

  The mixed signal shown in FIG. 4D is an output from the mixer 232 (see FIG. 3), and the low frequency component is extracted by mixing the reflected signal and the delayed transmission signal. From the mixer 232, the level increases when there is a reflected signal, and the output changes with the movement of the impurity particles as the reflector. Each output value varies slightly depending on the amplitude of the reflected signal, but the reflected signals corresponding to a plurality of transmission / reception pulses are stored in the mixed waveform memory 234 (see FIG. 3) and the reflected waveform memory 244 (see FIG. 3). If the same processing is performed, the fundamental frequency becomes the Doppler frequency.

  In this embodiment, since the rectifier 13 is provided so that the flow of the filtrate W2 is constant near the focal point F of the ultrasonic transducer 12 (see FIG. 2), the impurity particles that move around the focal point F The moving speed and the moving direction are stable, and the Doppler frequency of the reflected wave from the impurity particles can be accurately detected.

  The analyzer 251 (see FIG. 3) uses the data regarding the reflector having the moving speed almost the same as the flow velocity in the outlet channel 13o (see FIG. 2) as the detection data of the impurity particles. By not using data related to the reflector as a detection target, erroneous detection of impurity particles can be reduced.

  The concept of calculating the particle size of the impurity particles will be described with reference to FIG. Each of FIGS. 5A to 5C is an example of a waveform for one pulse, and the timing is shown in the horizontal axis direction in the same manner as in FIG.

  As shown in FIG. 5A, the delayed transmission signal has a constant amplitude during the pulse width Δt, but its frequency changes with time, the frequency is low at the start of the pulse, and high before the end of the pulse. Become.

  When the amplitude of the reflected signal changes as shown in FIG. 5B, the mixed signal shown in FIG. 5C is obtained. In the graph shown in FIG. 5C, a point (inflection point) where the signal intensity rapidly increases can be confirmed. Since the frequency change of the delayed transmission signal is known, the frequency of the reflected wave at the inflection point is obtained. From the frequency at the inflection point, the size of the impurity particles can be obtained.

  The reflection intensity of a particle having a predetermined size (peripheral length) depends on the frequency of the transmission wave, and the reflection intensity becomes maximum when the circumference of the impurity particle is equal to the wavelength of the transmission wave. The frequency of the transmission wave (transmission signal) is initially lowered (longer wavelength) and gradually changed (higher wavelength shorter), so the wavelength of the transmitted wave is about the same as the length of the periphery of the particle. , A point (inflection point) where the reflection intensity increases rapidly appears. The analyzer 251 (see FIG. 3) calculates the size of the impurity particles based on this inflection point, and determines that the data indicating the size of the predetermined range is that of the impurity particles and selectively uses it. By eliminating data that is noise, false detection of impurity particles is reduced.

  With reference to FIG. 6, the relationship between the wavelength of an ultrasonic wave and the reflective cross-sectional area of spherical particles, that is, the reflection intensity will be described. The spherical particle is assumed to be a true spherical substance that imitates the impurity particles contained in the raw water W1.

The vertical axis direction of this graph indicates the size of a value obtained by dividing the reflection cross section of the spherical particles by the geometric cross section (hereinafter referred to as a normalized reflection cross section). That is, the normalized reflection cross section is based on the reflection intensity when the geometric cross section that is the projected area of the spherical particles is 1, and the detected reflection intensity is several times the geometric cross section. It means whether it is a value.
The horizontal axis direction of this graph indicates the size of a value obtained by dividing the circumferential length of the spherical particles by the wavelength of the ultrasonic wave (hereinafter referred to as a normalized circumferential length).

  From the sound velocity v in water and the frequency f of the ultrasonic wave to be used, the wavelength λ of the ultrasonic wave in water can be obtained by λ = v / f. Here, when the normalized circumferential length is 1.0, if the circumferential length (not normalized) of the spherical particles is L, there is a relationship of λ = L. Therefore, when the normalized circumferential length is 1.0, the relationship of λ = 2πr is derived from the radius r of the spherical particles and the circumferential ratio π.

  For example, when the frequency f of the ultrasonic wave to be used is 100 [MHz], the sound velocity v in water is 1500 [m / sec], so the wavelength λ of this ultrasonic wave is 15 [μm]. The diameter 2r of a spherical particle having a circumferential length equal to the wavelength λ is about 4.8 [μm]. At this time, the standardized circumferential length is 1.0.

  Referring to the graph of FIG. 6, when the normalized cross-sectional area of the spherical particle is 1 (for example, the frequency f of the ultrasonic wave used is 100 [MHz], the diameter 2r of the spherical particle is 4.8 [μm]). ), The reflection cross section (indicating the reflection intensity) of this spherical particle is found to be about 3.5 times the geometric cross section. The vertical axis indicates a relative value normalized by the geometric cross section, and does not indicate the absolute value of the reflection cross section.

  Considering the actual cross-sectional area, it can be seen that the following characteristics are obtained. In the graph of FIG. 6, the case where both the horizontal axis and the vertical axis are 1 is used as a reference. When the frequency f to be used is not changed (that is, the wavelength is not changed) and the diameter 2r of the spherical particles is changed, the value on the vertical axis is normalized by the geometric cross-sectional area and hardly changes. However, the non-normalized reflection cross section varies with the geometric cross section. Since the geometric cross-sectional area is proportional to the square of the diameter 2r of the spherical particles, the non-normalized reflection cross-sectional area also changes in proportion to the square of the diameter 2r of the spherical particles.

  For example, consider a case where the diameter 2r of the spherical particles is 10 times the standard. Since the value on the vertical axis is a value normalized by the geometric cross-sectional area, it remains almost 1. However, in this case, since the diameter 2r of the spherical particles is 10 times the standard, the non-standardized reflection cross-sectional area is 100 times the standard. That is, in a region where the value of (circumferential length / wavelength) of spherical particles is 1 or more, the cross-sectional area becomes 100 times when the particle diameter becomes 10 times.

  On the other hand, when the value of (circumferential length / wavelength of spherical particles) is 1 or less, the cross-sectional area decreases rapidly. For example, if the value of (circumferential length / wavelength of spherical particles) is 0.1, the reflection cross section normalized by the geometric cross section is 0.001, but if not normalized, 1/100. From the above considerations, it can be seen that the value of (circumferential length / wavelength of spherical particles) has an abrupt change in the actual reflection cross-section when the value is around 1.

  In this way, by appropriately selecting the frequency f of the ultrasonic wave to be used, a reflected wave having a predetermined amplitude or more is obtained from an impurity particle having a certain size or more, thereby selectively detecting such impurity particles as a detection target. can do. Furthermore, if pulsed ultrasonic waves (chirp pulses) in which the frequency of the ultrasonic wave used changes continuously, the size of the impurity particles can be determined from the inflection point of the reflection intensity and the wavelength of the ultrasonic wave at that time. Can be estimated.

Next, the filtration membrane damage determination process by the analyzer 251 will be described in detail with reference to FIG.
First, the analyzer 251 sets each parameter used in this process, and initializes a process variable (step S1). This parameter includes an ultrasonic frequency f (or frequency range) to be used, a Doppler frequency setting range, and a particle diameter setting range.

  If no timing signal is input from the timing signal generator 201, the process waits until it is input (No in step S2). When the timing signal is input (Yes in step S2), waveform data is obtained from the mixed waveform memory 234 and the reflected waveform memory 244 (step S3).

Then, based on the reflected waveform data and the mixed waveform data, the Doppler frequency of the reflected signal is calculated (step S4).
Furthermore, the increase point (inflection point) of the reflection amplitude is detected based on the mixed waveform data, and the diameter of the reflector is calculated from the ultrasonic frequency at that time (step S5).

If the detected Doppler frequency is within the set range (that is, if the moving speed of the reflector is within the predetermined range), the process proceeds to the next process (Yes in step S6). If not within the set range, the process proceeds to step S2. Return.
If the particle diameter of the reflector calculated in step S5 is within the set range, the process proceeds to the next process (Yes in step S7), and if not within the set range (No in step S7), the process returns to step S2. Alternatively, when the calculated particle diameter of the reflector exceeds a predetermined value (lower limit value of the setting range), the process proceeds to the next process (step S8) (that is, it is determined that the particle is an impurity particle to be detected) and is calculated. When the particle diameter of the reflector is less than or equal to a predetermined value, the process may return to step S2.

  Thus, if it is determined that both the detected Doppler frequency and the particle diameter are within the set range, this reflector can be determined to be an impurity particle. Therefore, 1 is added to the leakage accumulation value to update this value. Alternatively, the amount (volume) of the detected impurity particles may be obtained and added to the leakage accumulation value, and this value may be updated (step S8).

  If the accumulated leakage value is equal to or less than the allowable leakage value set in step S1 (No in step S9), the process returns to step S2. The leakage accumulation value may be determined as to whether or not the increase number (increase amount) per hour is less than or equal to leakage tolerance.

  However, when the leakage accumulation value exceeds the leakage allowable value set in step S1 (No in step S9), it is determined that the filtration membrane of the membrane filtration module 4 has been broken or damaged (step S10). The determination result is output to the communication device 252 (step S11).

  Then, if any termination factor exists such as when the filtration membrane breakage detector 10 is terminated (step S12), the process is terminated. If not, the process returns to step S2, and the above-described process is performed. repeat.

In Step 11, when a determination result indicating that the filtration membrane is broken or damaged is output to the communication device 252, a detection signal is transmitted from the communication device 252 to the control device 6 (see FIG. 1). The device 6 closes the upstream valve 3 and stops the filtration in the membrane filtration module 4 where the leakage has occurred.

According to the filtration membrane breakage detector 10 of the first embodiment, the following effects are obtained.
(1) Since ultrasonic waves are used to detect the particles P, there are no obstacles such as clouding of the light projection window and light reception window unlike the optical sensor, maintenance is free, and the decrease in detection accuracy is suppressed. it can.
(2) Since the detection operation is always performed on the filtered water W2, the occurrence of breakage or damage of the filtration membrane of the membrane filtration module 4 can be detected without delay. For this reason, a countermeasure can be taken quickly without substantially reducing the quality of the filtered water W2.
(3) Even if the ultrasonic transducer 12 is installed in the pipe 11, no maintenance is required, and the number of management operations can be reduced.
(4) When the ultrasonic transducer 12 including a piezoelectric element is used, it is inexpensive and maintenance is not required.
(5) Since the ultrasonic transducer 12 converges the ultrasonic transmission / reception beam, even if it is low turbidity filtered water W2 or the particle size of impurity particles to be detected is small, filtration is performed. Impurity particles leaking from the film can be detected with high sensitivity.
(6) Since the filtration membrane breakage detector 10 can be manufactured at low cost, even if it is attached to all the membrane filtration modules 4, the cost can be reduced. For this reason, the membrane filtration apparatus 100 which can identify rapidly the membrane type filtration module 4 which the fracture | rupture and damage generate | occur | produced can be constructed | assembled at low cost.
(7) Since the signal processing unit 20 can be configured by a general-purpose IC, the filtration membrane breakage detector 10 can be manufactured at a very low cost.
(8) Since a reflector having a preset particle size is determined as an impurity particle, detection accuracy can be improved.
(9) Since a reflector in a predetermined speed range is determined as an impurity particle using the Doppler effect, noise is separated, the signal-to-noise ratio for detection is improved, and false detection and detection omission are prevented. Can be reduced.
(10) Since a transmission wave having a continuously changing frequency is used, the size of the reflector can be calculated, and erroneous detection of impurity particles can be reduced.
(11) Since the water flow of the filtered water W2 flowing into the inlet channel 13i of the rectifier 13 is converged, and the impurity particles are also converged and pass through the outlet channel 13o, the impurity particles can be detected with high accuracy.
(12) Since the water flow of the filtered water W2 is rectified in the outlet channel 13o of the rectifier 13, the moving speed and moving direction of the impurity particles are constant, and the detection accuracy can be improved.

(Second Embodiment)
As shown in FIG. 8, the filtration membrane breakage detector 10B of the second embodiment includes an ultrasonic transducer 12b and a rectifier 13b in addition to the filtration membrane breakage detector 10 of the first embodiment. Instead of the signal processing unit 20, a signal processing unit 20B is provided.

  The ultrasonic transducer 12b has the same configuration as the ultrasonic transducer 12, and is installed in the pipe 11 so that the transmission / reception surface faces the ultrasonic transducer 12 and the focal points F coincide with each other. And is electrically connected to the signal processing unit 20B.

  The rectifier 13 b has the same shape as the rectifier 13 and is installed in the pipe 11 so that the outlet flow path 13 o is connected in the opposite direction to the rectifier 13. The rectifier 13 and the rectifier 13b are installed so that the focal points F of the ultrasonic transducer 12 and the ultrasonic transducer 12b are positioned in the narrowed flow path of the connection portion.

  The signal processing unit 20B basically has the same configuration as the signal processing unit 20 (see FIG. 3) of the first embodiment. The signal processing unit 20B first (1) performs ultrasonic transmission / reception using the ultrasonic transducer 12, and (2) performs ultrasonic transmission / reception using the ultrasonic transducer 12b. Repeat steps (1) and (2). The transmission / reception switcher (not shown) of the signal processing unit 20 has a circuit for switching between the ultrasonic transmitter / receiver 12 and the ultrasonic transmitter / receiver 12b in addition to the configuration of the transmission / reception switcher 221 of the first embodiment. ing.

  In this way, by alternately and repeatedly using the ultrasonic transducer 12 and the ultrasonic transducer 12b, the Doppler frequency deviation amount is reversed between the ultrasonic transducer 12 and the ultrasonic transducer 12b. Become. Therefore, the analyzer 251 of the signal processing unit 20B performs the process in the same manner as in the first embodiment, but further compares the polarity of the Doppler frequency with its absolute value, and more strictly determines the impurity particles.

  According to the filtration membrane breakage detector 10B of the second embodiment, the detection results are compared by using the ultrasonic waves in the forward direction and the reverse direction with respect to the moving direction of the impurity particles, so that the detection accuracy is further improved. , The reliability for measurement can be improved.

  Impurity particles are contained in the raw water before filtration, and the presence of the impurity particles in the filtered water can be regarded as leakage due to breakage or damage of the filtration membrane. The filtration membrane breakage detector according to the present invention can detect a leak with high accuracy and is low in cost. If the membrane breakage detector according to the present invention is installed in each membrane filtration module, it is possible to quickly identify the leaking membrane filtration module at low cost. For this reason, it is very effective industrially from the viewpoint of ensuring the quality of filtered water and reducing the installation and maintenance costs.

It is a processing flow figure showing the membrane type filtration module of a 1st embodiment concerning the present invention. It is sectional drawing which shows the cross section cut | disconnected in the major axis direction of piping about the filtration membrane breakage detector of 1st Embodiment. It is a block diagram which shows a signal processing part in detail. It is a timing chart which shows the timing and waveform of each signal in a signal processing part. It is a graph which shows the waveform and timing about 1 pulse of the signal input-output to a mixer. It is a graph which shows the reflective cross section of the spherical particle with respect to the wavelength of an ultrasonic wave. It is a flowchart which shows the filter membrane damage determination process by an analyzer. It is sectional drawing which shows the cross section cut | disconnected in the major axis direction of piping about the filtration membrane breakage detector of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw water tank 2 Water supply pump 3 Valve 4 Membrane filtration module 6 Control device 10, 10B Filtration membrane breakage detector (filtration module leak detector)
DESCRIPTION OF SYMBOLS 11 Pipe 12, 12b Ultrasonic transmitter / receiver 13, 13b Rectifier 13i Inlet flow path 13o Outlet flow path 20, 20B Signal processing part 100 Membrane filtration apparatus 201 Timing signal generator 211 Transmission waveform memory 212 DA converter 213 Amplifier 221 Transmission / reception switching device 231 Delay device 232 Mixer 233, 243 A-D converter 234 Mixed waveform memory 241 Receiving amplifier 244 Reflected waveform memory 251 Analyzer 252 Communication device

Claims (25)

  An ultrasonic transmission wave is transmitted to the permeated water that has flowed out of the membrane filtration device that obtains permeated water by filtering raw water through a filtration membrane, and the presence of particles in the permeated water is determined based on the reflected wave from the permeated water. A filtration membrane breakage detector for detecting that the filtration membrane is broken or damaged based on the determination result of the particles. A signal processing unit for outputting a high-frequency transmission signal;
An ultrasonic transducer for converting the transmission signal into the transmission wave and transmitting it into the permeated water;
Comprising
The ultrasonic transducer further receives the reflected wave and converts it to a reflected signal;
The signal processing unit further analyzes the reflected wave based on the reflected signal to determine the presence of the particle;
The filtration membrane breakage detector according to claim 1.   The filtration membrane breakage detector according to claim 2, wherein the ultrasonic transducer converges the beam of the transmitted wave and the reflected wave to a focal point located in the transmitted water. The filter membrane breakage detector according to claim 3, further comprising a rectifier that rectifies the filtered water in the vicinity of the focal point.   5. The Doppler frequency is calculated based on the transmitted wave and the reflected wave, and the presence of the particle is determined when the Doppler frequency is within a predetermined frequency band. The described filtration membrane breakage detector. The transmission wave has a predetermined change in frequency over time,
Based on the frequency of the reflected wave at the inflection point where the intensity of the reflected wave suddenly changes, the size of the reflector that is the wave source of the reflected wave is calculated, and the calculated size of the reflector is within a predetermined range. The filter membrane breakage detector according to any one of claims 1 to 5, wherein the presence of the particles is determined. Comprising an opposed ultrasonic transducer having the same configuration as the ultrasonic transducer and disposed so that the focal positions coincide so that the transmission directions of the transmission waves are opposed to each other;
The signal processing unit alternately switches between the ultrasonic transducer and the opposing ultrasonic transducer,
The transmission / reception of the transmission wave and the reflected wave by the ultrasonic transducer and the transmission / reception of the transmission wave and the reflection wave by the opposed ultrasonic transducer are alternately performed. The filtration membrane breakage detector in any one of Claim 6. The signal processing unit determines the presence of the particle with reference to both the reflected signal from the ultrasonic transducer and the reflected signal from the opposing ultrasonic transducer,
The filtration membrane breakage detector according to claim 7. A communication device that transmits a detection signal indicating that when it is detected that the filter membrane is broken or damaged,
The filtration membrane breakage detector according to any one of claims 1 to 8, characterized by comprising: A plurality of membrane filtration modules including a filtration membrane that filters raw water to obtain permeated water;
A plurality of filtration membrane breakage detectors according to claim 9, each inserted downstream of a plurality of the membrane filtration modules,
Including a communication device that receives a detection signal indicating that the filtration membrane is broken or damaged from the filtration membrane breakage detector, and a control device that performs control based on the detection signal;
The membrane filtration apparatus characterized by comprising. Comprising a plurality of valves that are inserted respectively upstream or downstream of the plurality of membrane filtration modules and can close the flow path of the raw water;
The control device closes the valve on the upstream side or the downstream side of the membrane filtration module that has been damaged or damaged based on the detection signal.
The membrane filtration apparatus according to claim 10. The control device, based on the detection signal, stops the operation of a water supply pump that supplies the raw water to each of the plurality of membrane filtration modules.
The membrane filtration device according to claim 10 or 11, characterized in that.   An ultrasonic transmission wave is transmitted to the permeated water that has flowed out of the membrane filtration device that obtains permeated water by filtering raw water through a filtration membrane, and the presence of particles in the permeated water is determined based on the reflected wave from the permeated water. A filtration membrane breakage detection method, comprising detecting that the filtration membrane is broken or damaged based on the determination result of the particles.   14. The filtration membrane breakage detection method according to claim 13, wherein the beams of the transmission wave and the reflected wave are converged on a focal point located in the permeated water.   The filtration according to claim 13 or 14, wherein a Doppler frequency is calculated based on the transmitted wave and the reflected wave, and the presence of the particle is determined when the Doppler frequency is within a predetermined frequency band. Film breakage detection method. The transmission wave has a predetermined change in frequency over time,
Based on the frequency of the reflected wave at the inflection point where the intensity of the reflected wave suddenly changes, the size of the reflector that is the wave source of the reflected wave is calculated, and the calculated size of the reflector is within a predetermined range. The method for detecting a membrane breakage according to any one of claims 13 to 15, wherein the presence of the particles is determined. Alternately transmitting the transmitted waves in opposing transmission directions and determining the presence of the particles with reference to both of the opposing reflected waves;
The filtration membrane breakage detection method according to any one of claims 13 to 16, wherein   Transmitting ultrasonic transmission waves to the permeated water that has flowed out from a plurality of membrane filtration modules including a filtration membrane that obtains permeated water by filtering raw water, and based on the reflected waves from the permeated water, A leak detector for a filtration module, characterized by determining the presence and detecting that a leak has occurred in the membrane filtration module based on a determination result of the particles. A signal processing unit for outputting a high-frequency transmission signal;
An ultrasonic transducer for converting the transmission signal into the transmission wave and transmitting it into the permeated water;
Comprising
The ultrasonic transducer further receives the reflected wave and converts it to a reflected signal;
The signal processing unit further analyzes the reflected wave based on the reflected signal to determine the presence of the particle;
The leak detector of the filtration module according to claim 18. Comprising a rectifier for rectifying the filtered water,
The leakage of a filtration module according to claim 19, wherein the ultrasonic transducer converges the beam of the transmitted wave and the reflected wave to a focal point located in the permeate rectified by the rectifier. Detector. The transmission wave has a predetermined change in frequency over time,
Based on the frequency of the reflected wave at the inflection point where the intensity of the reflected wave suddenly changes, the size of the reflector that is the wave source of the reflected wave is calculated, and the calculated size of the reflector is within a predetermined range. When or
The Doppler frequency is calculated based on the transmitted wave and the reflected wave, and the presence of the particle is determined when the Doppler frequency is within a predetermined frequency band. Leak detector for the described filtration module. Comprising an opposed ultrasonic transducer having the same configuration as the ultrasonic transducer and disposed so that the focal positions coincide so that the transmission directions of the transmission waves are opposed to each other;
The signal processing unit alternately switches between the ultrasonic transducer and the opposed ultrasonic transducer, and transmits and receives the transmission wave and the reflected wave by the ultrasonic transducer, and the opposed ultrasonic transducer. Alternately transmitting and receiving the transmission wave and the reflected wave by a transmitter, referring to both the reflected signal from the ultrasonic transducer and the reflected signal from the opposing ultrasonic transducer The leakage detector of the filtration module according to any one of claims 19 to 21, wherein presence of particles is determined. A communication device that transmits a detection signal indicating that the leakage has been detected;
The leakage detector of the filtration module according to any one of claims 18 to 22, characterized by comprising: A plurality of membrane filtration modules including a filtration membrane that filters raw water to obtain permeated water;
The leakage detectors of the plurality of filtration modules according to claim 23, which are respectively inserted downstream of the plurality of membrane filtration modules.
Including a communication device that receives a detection signal indicating that a leak has occurred in the membrane filtration module from a leakage detector of the filtration module, and a control device that performs control based on the detection signal;
The membrane filtration apparatus characterized by comprising.   Transmitting ultrasonic transmission waves to the permeated water that has flowed out of the membrane filtration module including a filtration membrane that filters raw water to obtain permeated water, and confirms the presence of particles in the permeated water based on the reflected waves from the permeated water. A method for detecting leakage of a filtration module, comprising: determining and detecting that leakage has occurred in the membrane filtration module based on a determination result of the particles.

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