Membrane contactor control method combining ultrasonic monitoring and ultrasonic cleaning for membrane pollution

Abstract

The invention discloses a control method of a membrane contactor combining ultrasonic monitoring and ultrasonic cleaning for membrane pollution, and the control method comprises the following steps: combining ultrasonic monitoring and cleaning, transmitting ultrasonic waves to a membrane surface through a high-frequency probe for monitoring, collecting an ultrasonic reflection spectrogram in real time, and calculating the thickness of a membrane pollution layer according to the difference of signal arrival time. When the pollution degree affects the normal operation of the membrane contactor, the high-frequency ultrasonic probe is replaced, and the low-frequency probe is used for cleaning the membrane pollution by utilizing the ultrasonic cavitation effect. And the cleaning effect can be verified again through ultrasonic monitoring until the membrane pollution is thoroughly cleaned, and the membrane contactor is ensured to recover the optimal state. Different low frequencies are selected for pollutants of different degrees so as to achieve the optimal cleaning effect. According to the method, only the probe needs to be replaced, the monitoring and cleaning processes are continuously carried out, the work of the membrane contactor does not need to be interrupted, the operation efficiency and the equipment utilization rate are improved, meanwhile, membrane damage and operation complexity are reduced, and the monitoring and cleaning processes are coherent and concise.

Description

Technical Field

[0001] The technical solution provided by the present invention relates to the field of measurement, and specifically to a method for controlling membrane pollution of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning. Background Art

[0002] The membrane contactor is a membrane separation process that realizes gas / liquid or liquid / liquid phase mass transfer under the condition of two phases being immiscible. Its most important function is to provide a larger specific surface area for mass transfer, which makes it more superior than the conventional dispersed phase contact separator; another outstanding advantage is that the two-phase fluid separated by the membrane is relatively independent in the process, so it can effectively solve the common problems of conventional separators such as flooding, channeling or mist entrainment. However, this technology also has a significant disadvantage, namely membrane fouling. When membrane fouling occurs, the mass transfer resistance of the membrane increases significantly, and the dissolved oil, mineral salts or amphiphilic molecules in the wastewater reduce the liquid entry pressure of the membrane, which in turn causes membrane wetting, resulting in problems such as reduced membrane flux. Therefore, it is necessary to monitor the operation process of the membrane contactor in real time, detect membrane fouling and clean it in time, so that the membrane can be recycled and cost-saving. Therefore, it is necessary to monitor and clean the membrane contactor during its operation.

[0003] A commonly used combination of membrane fouling monitoring and water cleaning currently relies on changes in permeate flux to assess the fouling status. When the monitoring system detects that the membrane fouling has reached a certain level, the operator needs to manually interrupt the current monitoring process and then perform a water flushing step. This series of manual operations not only increases the complexity and time cost of the workflow, but also easily leads to human errors and inefficiency. In addition, the manual processing may cause additional physical damage or chemical erosion to the fragile membrane structure due to improper operation, uneven force control or improper timing. This damage may not only immediately affect the performance and life of the membrane, but may also gradually accumulate over the long term, resulting in a significant decrease in the stability and efficiency of the entire membrane system. In view of this, there is an urgent need to develop a more integrated and efficient joint monitoring and cleaning solution. Summary of the invention

[0004] In view of the shortcomings of the above existing technologies, the present invention innovatively integrates the in-situ ultrasonic monitoring and ultrasonic cleaning functions of membrane fouling, and establishes a direct correlation between the frequency of the ultrasonic probe and the degree of membrane fouling. This method allows real-time ultrasonic monitoring of membrane fouling conditions, and then seamlessly switches to a low-frequency ultrasonic probe, using the cavitation effect to efficiently clean membrane surface fouling, achieving continuity and convenience in the monitoring and cleaning process, and significantly improving the efficiency and effectiveness of membrane fouling management.

[0005] The technical solutions to achieve the above objectives include the following:

[0006] A method for controlling membrane contamination of a membrane contactor by combining ultrasonic monitoring and ultrasonic cleaning, the method comprising: combining ultrasonic monitoring and cleaning, using a high-frequency probe to transmit ultrasonic waves with preset parameters to a membrane surface, performing ultrasonic monitoring, and collecting corresponding ultrasonic reflection spectra in real time, and then calculating the thickness of the membrane contamination layer by the difference in ultrasonic signal arrival time in the ultrasonic reflection spectra; when it is detected that the actual detection value of the ultrasonic signal exceeds the monitoring threshold, replacing the original probe with a low-frequency ultrasonic probe, and using bubbles generated by the ultrasonic cavitation effect to clean the membrane contamination.

[0007] In one embodiment, the cleaning effect can be verified by performing ultrasonic monitoring again until the membrane contamination is completely cleaned, ensuring that the membrane contactor is restored to the optimal working state; then, under the condition of the same contamination layer thickness, low-frequency probes of different frequencies are used to clean the membrane contamination separately, and the maximum probe frequency that can completely clean the membrane contamination is found to prevent damage to the membrane due to excessive high frequency.

[0008] In one embodiment, the present invention only changes the frequency of the ultrasonic probe during the monitoring and cleaning conversion process, from high frequency to low frequency, without changing other factors. In the process of cleaning membrane contamination, only the influence of low-frequency ultrasonic probes of different frequencies needs to be considered.

[0009] In one embodiment, when ultrasonic waves are used to clean the membrane system, lower frequencies can usually produce larger bubbles, which helps to remove thicker layers of contaminants. However, for mild contamination, it may lead to energy waste, and too high a probe frequency may cause varying degrees of damage to the filter membrane. Therefore, it is particularly important to select a probe of appropriate frequency when using ultrasonic technology to clean and regenerate the filter membrane. For different degrees of membrane contamination, low-frequency probes of different frequencies are used for cleaning respectively, and the ultrasonic probe with the maximum frequency that can completely clean the membrane contamination is explored, thereby reducing damage to the membrane.

[0010] In one of the embodiments, the method is used to clean the membrane surface, and the method for calculating membrane contamination is consistent with that used for ultrasonic monitoring and cleaning. During the separation process of the membrane assembly, ultrasonic waves with preset parameters are emitted to the membrane surface, and the corresponding ultrasonic reflection spectrum is collected in real time; based on the ultrasonic reflection spectrum, the reception time difference between two adjacent groups of measured ultrasonic reflection signals at a specific position of the membrane with their respective emission times as reference points, and the interface acoustic impedance corresponding to the two adjacent groups of measured ultrasonic reflection signals are calculated in real time; based on the interface acoustic impedance, the reception time difference and the medium density of the membrane assembly, the real-time thickness of the contamination layer of the membrane assembly corresponding to the positions of the two adjacent groups of measured ultrasonic reflection signals is calculated in real time.

[0011] In one embodiment, the formula for the arrival time of the ultrasound from the deposition layer to the liquid / gas interface is:

[0012]

[0013] Wherein, t2 is the arrival time of ultrasound from the deposition layer to the liquid / gas interface, t0 is the arrival time of ultrasound when there is no deposition, t1 is the time when ultrasound reaches the deposition layer, ρ0 and ρ1 are the medium and deposition layer densities of the membrane assembly respectively, Z0 is the initial interface acoustic impedance of the membrane assembly when it is not contaminated, and Z1 is the interface acoustic impedance corresponding to the interface reflection coefficient state of the membrane assembly after contamination.

[0014] In one embodiment, the real-time membrane contamination formula for a specific position of the membrane is calculated based on the thickness of the contamination layer:

[0015]

[0016] Wherein, δ represents the thickness of the contamination layer, t2 is the arrival time of ultrasound from the deposition layer to the liquid / gas interface, t0 is the arrival time of ultrasound when there is no deposition, t1 is the time when ultrasound reaches the deposition layer, ρ0 and ρ1 are the medium and deposition layer densities of the membrane assembly respectively, Z0 is the initial interface acoustic impedance of the membrane assembly when it is not contaminated, and Z1 is the interface acoustic impedance corresponding to the interface reflection coefficient state of the membrane assembly after contamination.

[0017] In one embodiment, the calculation of the thickness of the membrane fouling layer can predict future membrane fouling trends based on historical data, further improving monitoring accuracy; according to the characteristics of different membrane materials and pollutants, the response speed and prediction accuracy to membrane fouling changes can be improved; in addition, the algorithm can also adjust the cleaning strategy according to real-time data to achieve the best cleaning effect.

[0018] In one of the embodiments, during the ultrasonic monitoring and cleaning process, the probes used are equipped with a real-time data transmission function to quickly adjust the cleaning parameters and optimize the cleaning effect; the data transmission function includes both wireless transmission and wired transmission to ensure stable operation in different environments; and an intelligent control system is also provided to automatically adjust the ultrasonic emission frequency, power and cleaning time through real-time monitoring data analysis to adapt to changes in the thickness of the membrane fouling layer.

[0019] In one embodiment, the membrane contactor has a modular design, which facilitates the rapid replacement or adjustment of membrane components according to different application scenarios, thereby improving the flexibility and adaptability of the system; the modular design includes standardized interfaces and universal adapters, so that different types of membrane components can be freely switched in the same system; at the same time, the design also allows for rapid replacement of ultrasonic probes and other accessories according to actual usage, thereby ensuring efficient operation and convenient maintenance of the system, thereby reducing overall operating costs.

[0020] The technical solution provided by the present invention has the following advantages and effects:

[0021] The first aspect of the present invention provides a method for controlling membrane pollution in a membrane contactor by combining ultrasonic monitoring and ultrasonic cleaning. Combined with ultrasonic monitoring and cleaning, a high-frequency probe is used to transmit ultrasonic waves of preset parameters to the membrane surface for ultrasonic monitoring, and the corresponding ultrasonic reflection spectrum is collected in real time, and the thickness of the membrane pollution layer is calculated by the difference in the arrival time of the ultrasonic signal in the ultrasonic reflection spectrum. When it is detected that the degree of membrane pollution affects the normal operation of the membrane contactor, the original probe is directly replaced with a low-frequency ultrasonic probe, and the bubbles generated by the ultrasonic cavitation effect are used to clean the membrane pollution until the membrane pollution is cleaned and can work normally. The entire monitoring and cleaning process is carried out continuously without interrupting the workflow of the membrane contactor, which greatly improves the operating efficiency and equipment utilization. The cleaning effect can be verified by performing ultrasonic monitoring again until the membrane pollution is thoroughly cleaned to ensure that the membrane contactor is restored to the best working state. The method only needs to replace the ultrasonic probe, so that the entire monitoring and cleaning process is carried out continuously without interrupting the workflow of the membrane contactor. Avoid the disadvantages of damage to the membrane during the monitoring and cleaning conversion process and the cumbersome operation of the conversion process, and realize monitoring and cleaning of the membrane based on ultrasonic probes at different frequencies, so that the monitoring and cleaning process of membrane pollution is coherent and concise.

[0022] The second aspect of the present invention proposes to detect the optimal probe frequency for membrane cleaning. When using ultrasonic cleaning of the membrane system, excessive power may cause varying degrees of damage to the filter membrane, so choosing the right ultrasonic power is crucial in the cleaning and regeneration process of the filter membrane. According to the degree of membrane contamination, it can be roughly divided into three categories: mild contamination is manifested as the attachment of a small amount of particulate matter or organic matter, which is relatively easy to clean; moderate contamination is a significant increase in particulate matter and organic matter, which may form a preliminary contaminated film layer; severe contamination is a thick contaminated film layer with dense pollutants, which is difficult to clean. According to different degrees of membrane contamination, low-frequency ultrasonic probes of different frequencies are used for cleaning, and the most efficient frequency that can completely remove membrane contamination is gradually explored. This precise frequency selection not only helps to effectively remove pollutants, but also minimizes damage to the filter membrane, achieving an efficient and low-loss cleaning effect.

[0023] The third aspect of the present invention provides a membrane contamination quantification method. The method comprises: for ultrasonic monitoring and cleaning, consistent with the method for calculating membrane contamination used, emitting ultrasonic waves with preset parameters to the membrane surface during the separation process of the membrane assembly, and collecting the corresponding ultrasonic reflection spectrum in real time; based on the ultrasonic reflection spectrum, real-time calculation of the receiving time difference of two adjacent groups of measured ultrasonic reflection signals at a specific position of the membrane with each transmitting time as a reference point, and the interface acoustic impedance corresponding to the two adjacent groups of measured ultrasonic reflection signals; based on the interface acoustic impedance, the receiving time difference and the medium density of the membrane assembly, real-time calculation of the real-time contamination layer thickness of the membrane assembly corresponding to the two adjacent groups of measured ultrasonic reflection signal positions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings herein show specific examples of the technical solutions described in the present invention, and together with the specific implementation methods, constitute a part of the specification, and are used to explain the technical solutions, principles and effects of the present invention.

[0025] Unless otherwise specified or defined, the same figure marks in different drawings represent the same or similar technical features, and the same or similar technical features may also be represented by different figure marks.

[0026] Figure 1 is a flow chart of joint monitoring and cleaning of membrane fouling in one embodiment of the present invention;

[0027] Figure 2 It is a schematic diagram of the framework of a method for real-time monitoring of membrane fouling thickness in one embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present invention, specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

[0029] Unless otherwise specified or defined, the "first, second..." used in this article is merely used to distinguish names and does not represent a specific quantity or order.

[0030] Unless specifically stated or defined otherwise, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] It should be noted that when a component is considered to be "fixed to" another component, it can be directly fixed to the other component or there can be a central component; when an component is considered to be "connected to" another component, it can be directly connected to the other component or there can be a central component at the same time; when an component is considered to be "installed on" another component, it can be directly installed on the other component or there can be a central component at the same time. When an component is considered to be "set on" another component, it can be directly set on the other component or there can be a central component at the same time.

[0032] The present invention proposes a method for controlling membrane contamination of a membrane contactor by combining ultrasonic monitoring and ultrasonic cleaning. The method comprises: combining ultrasonic monitoring and cleaning, using a high-frequency probe to transmit ultrasonic waves with preset parameters to a membrane surface for ultrasonic monitoring, and collecting a corresponding ultrasonic reflection spectrum in real time, and then calculating the thickness of the membrane contamination layer by the difference in the arrival time of the ultrasonic signal in the ultrasonic reflection spectrum; when it is detected that the actual detection value of the ultrasonic signal exceeds the monitoring threshold, replacing the original probe with a low-frequency ultrasonic probe, and using bubbles generated by the ultrasonic cavitation effect to clean the membrane contamination.

[0033] Figure 1 In order to jointly monitor and clean the membrane fouling process, ultrasonic monitoring and cleaning are combined. A high-frequency probe is used to emit ultrasonic waves with preset parameters to the membrane surface for ultrasonic monitoring, and the corresponding ultrasonic reflection spectrum is collected in real time. The thickness of the membrane fouling layer is then calculated by the difference in the arrival time of the ultrasonic signal in the ultrasonic reflection spectrum. When it is detected that the degree of membrane fouling affects the normal operation of the membrane contactor, the original probe is directly replaced with a low-frequency ultrasonic probe, and the bubbles generated by the ultrasonic cavitation effect are used to clean the membrane fouling until the membrane fouling is cleaned and can work normally. The entire monitoring and cleaning process is carried out continuously without interrupting the workflow of the membrane contactor, which greatly improves the operating efficiency and equipment utilization. The cleaning effect can be verified by performing ultrasonic monitoring again until the membrane fouling is thoroughly cleaned to ensure that the membrane contactor is restored to its optimal working state.

[0034] By comparing the cleaning efficiency and membrane damage of probes with different frequencies, we can deeply explore the matching relationship between ultrasonic frequency and pollutant type and degree of pollution, so as to optimize the cleaning process. In addition, based on the experimental results, we can establish a relationship model between ultrasonic cleaning frequency and membrane pollution thickness, providing theoretical support for membrane pollution cleaning in actual industrial applications. This method not only helps to extend the service life of the filter membrane, but also improves the energy-saving efficiency of the cleaning process, reduces maintenance costs, and promotes the widespread application of membrane systems in the fields of environmental protection and energy conservation.

[0035] Ultrasonic cleaning technology mainly relies on its cavitation effect, that is, the violent vibration of microbubbles (cavitation nuclei) in the liquid under the action of the sound field to achieve cleaning. However, when faced with different degrees of pollution, the effect of ultrasonic cleaning varies significantly. For membrane surfaces with the same pollutants but different degrees of pollution, 25KHz, 50KHz, 100KHz, 200KHz and 500KHz ultrasonic probes can be used for cleaning experiments in sequence while keeping other conditions consistent. By measuring the thickness of the membrane pollution layer after cleaning and detecting whether the pollutants are completely removed, the ultrasonic frequency that can most effectively clean membrane pollution is gradually explored.

[0036] In addition, the cleaning effect can be verified by performing ultrasonic monitoring again until the membrane contamination is completely cleaned, ensuring that the membrane contactor is restored to the optimal working condition; then, under the condition of the same contamination layer thickness, low-frequency probes of different frequencies are used to clean the membrane contamination separately, and the maximum probe frequency that can completely clean the membrane contamination is found to prevent damage to the membrane due to excessively high frequencies.

[0037] In addition, the present invention only changes the frequency of the ultrasonic probe in the monitoring and cleaning conversion process, from high frequency to low frequency, without changing other factors. In the process of cleaning membrane pollution, only the influence of low-frequency ultrasonic probes of different frequencies needs to be considered. In this embodiment, the high frequency is 1MHz~50MHz, and the low frequency is 25KHz~500KHz; on the basis of the above steps, the energy transfer and action mechanism of ultrasonic waves of different frequencies in the cleaning process are further analyzed. Low-frequency ultrasonic waves (such as 25KHz and 50KHz) can have a strong impact on stubborn pollution layers due to their strong cavitation effect, and are suitable for the removal of more serious pollutants. Low-frequency ultrasonic waves (such as 200KHz and 500KHz) are suitable for removing mild pollution due to their finer vibration effect, especially for the cleaning of fine organic matter or tiny particles.

[0038] In addition, when using ultrasound to clean the membrane system, lower frequencies usually produce larger bubbles, which helps to remove thicker layers of contaminants. However, for mild contamination, it may lead to energy waste. Too high a probe frequency will cause varying degrees of damage to the filter membrane. Therefore, it is particularly important to choose a probe with the appropriate frequency when using ultrasonic technology to clean and regenerate the filter membrane. For different degrees of membrane contamination, low-frequency probes of different frequencies are used for cleaning respectively, and the ultrasonic probe with the maximum frequency that can completely clean the membrane contamination is explored, thereby reducing damage to the membrane.

[0039] In addition, the calculation of the thickness of the membrane fouling layer can predict future membrane fouling trends based on historical data, further improving monitoring accuracy; according to the characteristics of different membrane materials and pollutants, the response speed and prediction accuracy to changes in membrane fouling can be improved; in addition, the algorithm can also adjust the cleaning strategy based on real-time data to achieve the best cleaning effect.

[0040] In addition, during the ultrasonic monitoring and cleaning process, the probes used are equipped with real-time data transmission function, so as to quickly adjust the cleaning parameters and optimize the cleaning effect; the data transmission function includes both wireless transmission and wired transmission to ensure stable operation in different environments; at the same time, it is equipped with an intelligent control system, which automatically adjusts the ultrasonic emission frequency, power and cleaning time through real-time monitoring data analysis to adapt to changes in the thickness of the membrane fouling layer.

[0041] In addition, the membrane contactor has a modular design, which facilitates the rapid replacement or adjustment of membrane components according to different application scenarios, thereby improving the flexibility and adaptability of the system; the modular design includes standardized interfaces and universal adapters, so that different types of membrane components can be freely switched in the same system; at the same time, the design also allows for rapid replacement of ultrasonic probes and other accessories according to actual usage, ensuring efficient operation and convenient maintenance of the system, thereby reducing overall operating costs.

[0042] See also Figure 2, the method for calculating membrane contamination used in ultrasonic monitoring and cleaning is consistent, and the method includes: emitting ultrasonic waves with preset parameters to the membrane surface during the separation process of the membrane assembly, and collecting the corresponding ultrasonic reflection spectrum in real time; based on the ultrasonic reflection spectrum, calculating in real time the receiving time difference of two adjacent groups of measured ultrasonic reflection signals at a specific position of the membrane with their respective emission times as reference points, and the interface acoustic impedance corresponding to the two adjacent groups of measured ultrasonic reflection signals; based on the interface acoustic impedance, the receiving time difference and the medium density of the membrane assembly, calculating in real time the real-time contamination layer thickness of the membrane assembly corresponding to the two adjacent groups of measured ultrasonic reflection signal positions.

[0043] The calculation corresponds to the interface acoustic impedance of the membrane interface of two adjacent groups of measured ultrasonic reflection signals, which is specifically implemented as follows: real-time calculation of the interface acoustic pressure reflection coefficient of the membrane assembly, and calculation of the interface acoustic impedance of the membrane interface based on the interface acoustic pressure reflection coefficient; wherein the calculation formula of the reflection coefficient is as follows:

[0044]

[0045] A1 represents the amplitude of the ultrasonic sound pressure after the membrane is contaminated, A2 represents the amplitude of the reflected ultrasonic wave when the membrane assembly is not contaminated, and R0 represents the interface reflection coefficient when the membrane assembly is not contaminated.

[0046] Furthermore, the formula for calculating the interface acoustic impedance of the membrane interface based on the interface acoustic pressure reflection coefficient is:

[0047]

[0048] Wherein, Z0 is the initial interface acoustic impedance of the membrane assembly when it is not polluted, and Z1 is the interface acoustic impedance corresponding to the interface reflection coefficient state of the membrane assembly after pollution.

[0049] The arrival time of ultrasound from the deposition layer to the liquid / gas interface is calculated based on the corresponding impedance of the interface. The specific formula is:

[0050]

[0051] Wherein, t0 is the arrival time of ultrasound when there is no deposition, t1 is the time when ultrasound reaches the deposition layer, and ρ0 and ρ1 are the medium and deposition layer densities of the membrane assembly, respectively.

[0052] The formula for calculating the real-time pollution at a specific position of the membrane based on the real-time pollution layer thickness is:

[0053]

[0054] Wherein, δ represents the thickness of the contamination layer, t2 is the arrival time of ultrasound from the deposition layer to the liquid / gas interface, t0 is the arrival time of ultrasound when there is no deposition, t1 is the time when ultrasound reaches the deposition layer, ρ0 and ρ1 are the medium and deposition layer densities of the membrane assembly, respectively.

[0055] When quoting drawing descriptions, new features that appear are described; in order to avoid repeated quotations of drawings resulting in less concise descriptions, features that have been described clearly will not be quoted in the drawings one by one.

[0056] The purpose of the above embodiments is to exemplarily reproduce and deduce the technical solution of the present invention, and to fully describe the technical solution, purpose and effect of the present invention. Its purpose is to make the public understand the disclosed content of the present invention more thoroughly and comprehensively, and it does not limit the protection scope of the present invention.

[0057] The above embodiments are not exhaustive enumerations of the present invention, and there may be multiple other implementations not listed. Any replacement and improvement made without violating the concept of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for controlling membrane fouling of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning, characterized in that: The method comprises: combining ultrasonic monitoring and cleaning, using a high-frequency probe to transmit ultrasonic waves with preset parameters to the membrane surface for ultrasonic monitoring, and collecting the corresponding ultrasonic reflection spectrum in real time, and calculating the thickness of the membrane contamination layer by the difference in the arrival time of the ultrasonic signal in the ultrasonic reflection spectrum; when it is detected that the actual detection value of the ultrasonic signal exceeds the monitoring threshold, the original probe is replaced with a low-frequency ultrasonic probe, and the bubbles generated by the ultrasonic cavitation effect are used to clean the membrane contamination.

2. The method for controlling membrane pollution of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning as claimed in claim 1, characterized in that: The cleaning effect is verified by performing ultrasonic monitoring again until the membrane contamination is completely cleaned to ensure that the membrane contactor is restored to the optimal working condition; then, under the condition of the same contamination layer thickness, low-frequency probes of different frequencies are used to clean the membrane contamination separately, and the maximum probe frequency that can completely clean the membrane contamination is calculated to prevent damage to the membrane caused by excessively high frequencies.

3. The method for controlling membrane pollution of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning as claimed in claim 2, characterized in that: In the monitoring and cleaning conversion process, the frequency of the ultrasonic probe is changed from high frequency to low frequency without changing other factors. In the process of cleaning membrane fouling, only the influence of low-frequency ultrasonic probes of different frequencies needs to be considered.

4. The method for controlling membrane pollution of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning as claimed in claim 3, characterized in that: When using ultrasound to clean the membrane system, lower frequencies usually produce larger bubbles, which helps to remove thicker layers of contaminants. However, for mild contamination, it may lead to energy waste. Too high a probe frequency will cause varying degrees of damage to the filter membrane. Therefore, it is particularly important to choose a probe with the right frequency when using ultrasonic technology to clean and regenerate the filter membrane. For different degrees of membrane contamination, use low-frequency probes of different frequencies to clean them separately, and explore the ultrasonic probe with the maximum frequency that can completely clean the membrane contamination, thereby reducing damage to the membrane.

5. The method for controlling membrane contamination of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning as claimed in claim 4, characterized in that: The control method is used to clean the membrane surface. The method for calculating membrane contamination is consistent with that used for ultrasonic monitoring and cleaning. During the separation process of the membrane assembly, ultrasonic waves with preset parameters are emitted to the membrane surface, and the corresponding ultrasonic reflection spectrum is collected in real time. Based on the ultrasonic reflection spectrum, the receiving time difference between two adjacent groups of measured ultrasonic reflection signals at specific positions of the membrane with their respective emission times as reference points, as well as the interface acoustic impedance corresponding to the two adjacent groups of measured ultrasonic reflection signals are calculated in real time. Based on the interface acoustic impedance, the receiving time difference and the medium density of the membrane assembly, the real-time contamination layer thickness of the membrane assembly corresponding to the positions of the two adjacent groups of measured ultrasonic reflection signals is calculated in real time.

6. The method for controlling membrane fouling of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning as claimed in claim 5, characterized in that: The formula for the arrival time of the ultrasound from the deposition layer to the liquid / gas interface is: Wherein, t2 is the arrival time of ultrasound from the deposition layer to the liquid / gas interface, t0 is the arrival time of ultrasound when there is no deposition, t1 is the time when ultrasound reaches the deposition layer, ρ0 and ρ1 are the medium and deposition layer densities of the membrane assembly respectively, Z0 is the initial interface acoustic impedance of the membrane assembly when it is not contaminated, and Z1 is the interface acoustic impedance corresponding to the interface reflection coefficient state of the membrane assembly after contamination.

7. The method for controlling membrane pollution of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning as claimed in claim 6, characterized in that: The formula for calculating the real-time membrane fouling at a specific position of the membrane based on the fouling layer thickness is: Wherein, δ represents the thickness of the contamination layer, t2 is the arrival time of ultrasound from the deposition layer to the liquid / gas interface, t0 is the arrival time of ultrasound when there is no deposition, t1 is the time when ultrasound reaches the deposition layer, ρ0 and ρ1 are the medium and deposition layer densities of the membrane assembly respectively, Z0 is the initial interface acoustic impedance of the membrane assembly when it is not contaminated, and Z1 is the interface acoustic impedance corresponding to the interface reflection coefficient state of the membrane assembly after contamination.

8. The method for controlling membrane pollution of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning as claimed in claim 7, characterized in that: The calculation of the thickness of the membrane fouling layer can predict future membrane fouling trends based on historical data, further improving monitoring accuracy. According to the characteristics of different membrane materials and pollutants, the response speed and prediction accuracy to membrane fouling changes can be improved. In addition, the algorithm can also adjust the cleaning strategy according to real-time data to achieve the best cleaning effect.

9. The method for controlling membrane fouling of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning as claimed in claim 8, characterized in that: During the ultrasonic monitoring and cleaning process, the probes used are equipped with real-time data transmission function to quickly adjust the cleaning parameters and optimize the cleaning effect; the data transmission function includes both wireless transmission and wired transmission to ensure stable operation in different environments; at the same time, it is equipped with an intelligent control system, which automatically adjusts the ultrasonic emission frequency, power and cleaning time through real-time monitoring data analysis to adapt to changes in the thickness of the membrane fouling layer.

10. The method for controlling membrane fouling of a membrane contactor combined with ultrasonic monitoring and ultrasonic cleaning as claimed in claim 9, characterized in that: The membrane contactor has a modular design, which facilitates the rapid replacement or adjustment of membrane components according to different application scenarios, thereby improving the flexibility and adaptability of the system. The modular design includes standardized interfaces and universal adapters, so that different types of membrane components can be freely switched in the same system. At the same time, the design also allows for rapid replacement of ultrasonic probes and other accessories according to actual usage, thereby ensuring efficient operation and convenient maintenance of the system, thereby reducing overall operating costs.

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