A piezoelectric enhanced dynamic membrane module and filtration method

Abstract

The application discloses a piezoelectric enhanced dynamic membrane module and a filtration method. An ultrasonic transducer is arranged in the inner cavity of the shell to convert electrical energy into mechanical vibration. By reducing the distance between the ultrasonic transducer and the dynamic membrane, the vibration effect and cavitation effect of the surface of the dynamic membrane are enhanced, thereby improving the cleaning efficiency of the dynamic membrane. Under the premise of ensuring the effectiveness of local cleaning, the irreversible pollution layer can be effectively removed, and the wear of the membrane material and the underlying support material is reduced. After cleaning the dynamic membrane, strong chemical reagents do not need to be used on the dynamic membrane, thereby reducing the risk of chemical damage or material degradation of the dynamic membrane and alleviating the potential side effects caused thereby. In addition, the piezoelectric enhanced dynamic membrane module can significantly improve the flux of the dynamic membrane. Compared with a traditional membrane bioreactor, only a small number of membrane modules need to be configured to meet the processing requirements, thereby being favorable for reducing the system cost and making the reactor structure more compact.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a piezoelectric enhanced dynamic membrane module and filtration method. Background Technology

[0002] Traditional activated sludge processes (CAS) have long been a primary solution for wastewater treatment due to their simple structure, mature technology, and relatively low investment costs. However, activated sludge processes still suffer from drawbacks such as poor solid-liquid separation, large footprint, and low operating efficiency, including a tendency for sludge bulking. To overcome these shortcomings, the field has proposed using dynamic membrane bioreactors (DMBRs) to achieve cost-effective and efficient wastewater filtration through dynamic membranes.

[0003] Meanwhile, membrane fouling severely restricts the long-term stable operation of dynamic membrane bioreactors. Membrane fouling mainly manifests as microbial attachment, inorganic deposition, and extracellular polymer accumulation. Currently, strategies such as air flushing, backflushing, and chemical cleaning are commonly used to control membrane fouling. While air flushing and backflushing can temporarily remove some loose fouling, their effectiveness in removing severe fouling (including irreversible membrane fouling) is often limited, and continuous aeration or frequent backflushing significantly increases energy consumption. Although chemical cleaning can effectively restore membrane flux, its frequent use not only increases operating costs but also generates chemical waste that is detrimental to environmental protection; furthermore, strong chemical agents may damage the dynamic membrane structure and even corrode the supporting materials themselves. In addition, the removal effect of chemical cleaning solutions on stubborn and severe fouling is also limited.

[0004] Furthermore, piezoelectric cleaning effectively removes contaminants adhering to the membrane surface by inducing vibration and cavitation in the liquid using high-frequency mechanical waves. Compared to conventional cleaning methods, piezoelectric cleaning offers advantages such as fast response speed and low dependence on chemical reagents, thus helping to reduce environmental risks and avoid damage to membrane materials. However, existing piezoelectric cleaning methods still suffer from insufficient energy transfer and insignificant cavitation effects. In addition, the cleaning frequency and duration lack clear control; improper management can lead to severe damage to the support material due to high-intensity or continuous piezoelectric cleaning. Simultaneously, existing piezoelectric devices are typically installed in liquid containers at a certain distance from the filter membrane, thus limiting their application in large-scale reactor systems. Moreover, the varying distances between different locations on the membrane surface and the piezoelectric device result in uneven distribution of mechanical vibration across the membrane, affecting the uniformity of membrane cleaning. Summary of the Invention

[0005] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a piezoelectric-enhanced dynamic membrane assembly to enhance the ability of the dynamic membrane to receive ultrasonic energy.

[0006] This application also proposes an experimental apparatus and a filtration method for the above-mentioned piezoelectric enhanced dynamic membrane module.

[0007] According to a first aspect embodiment of the present application, the piezoelectric-enhanced dynamic membrane module includes: A housing, the housing including a perforated mounting surface; A dynamic membrane, which covers the mounting surface, is used to filter fluid from outside the housing into the inner cavity of the housing; An ultrasonic transducer is disposed in the inner cavity of the housing, with its output end facing the dynamic membrane, and is used to convert electrical energy into mechanical vibration, so as to propagate the bubbles generated by the mechanical vibration and cavitation effect to the dynamic membrane through the fluid, and remove the contaminant layer on the dynamic membrane.

[0008] The piezoelectric-enhanced dynamic membrane module according to the embodiments of this application has at least the following beneficial effects: By placing the ultrasonic transducer inside the housing, the distance between the ultrasonic transducer and the dynamic membrane can be significantly shortened, thereby enhancing the vibration effect and cavitation effect on the surface of the dynamic membrane, improving the cleaning efficiency of the dynamic membrane and shortening the operation time; the reduction in operation time, combined with the support components used to support the dynamic membrane, allows for the removal of the fouling layer while ensuring local cleaning effect, thereby reducing wear on the membrane material and the underlying material; after cleaning the dynamic membrane using the piezoelectric-enhanced dynamic membrane module of this application, there is no need to use strong chemical reagents to clean the dynamic membrane, reducing the risk of chemical damage or material degradation of the dynamic membrane; at the same time, since there is no need to use strong chemical reagents, resource consumption can also be reduced and potential side effects can be reduced; in addition, the piezoelectric-enhanced dynamic membrane module of this application can significantly increase the dynamic membrane flux, which is about 10 times higher than the membrane flux of traditional membrane bioreactors; thus, while achieving the same treatment capacity, the number of membrane modules used can be significantly reduced, thereby reducing costs and making the reactor structure more compact.

[0009] According to some embodiments of this application, the output end of the ultrasonic transducer is directly facing the dynamic membrane, and the distance between the output end of the ultrasonic transducer and the dynamic membrane is configured such that the mechanical vibration and / or cavitation effect generated by the ultrasonic transducer can be effectively applied to the dynamic membrane via the fluid, thereby improving the removal effect of the contaminant layer on the dynamic membrane.

[0010] According to some embodiments of this application, the output end of the ultrasonic transducer in the direction toward the dynamic membrane corresponds to the effective filtration area of ​​the dynamic membrane, so that the main filtration area of ​​the dynamic membrane can receive the mechanical vibration and cavitation effect generated by the ultrasonic transducer, and improve the coverage and uniformity of the cleaning effect. The distance between the ultrasonic transducer and the dynamic membrane is 0cm-4cm; The output of the ultrasonic transducer covers at least 80% of the effective filtration area of ​​the dynamic membrane in the corresponding region facing the dynamic membrane.

[0011] According to some embodiments of this application, the piezoelectric enhanced dynamic membrane assembly further includes an ultrasonic generator, which is electrically connected to the ultrasonic transducer and is used to transmit an electrical signal to the ultrasonic transducer. The output power of the ultrasonic generator is 0W-100W.

[0012] According to some embodiments of this application, the piezoelectric enhanced dynamic membrane assembly further includes a pressure sensor electrically connected to the ultrasonic generator. The pressure sensor is used to detect the operating pressure of the dynamic membrane to control the ultrasonic generator to turn on.

[0013] According to some embodiments of this application, the mounting surface is detachably connected to a washer, a support member, and a pressure ring. The support member is used to support the dynamic membrane and is connected to the mounting surface through the washer. The pressure ring and the support member clamp and position the dynamic membrane.

[0014] According to some embodiments of the second aspect of this application, a filtration method is provided, applied to the above-described piezoelectric-enhanced dynamic membrane module. The piezoelectric-enhanced dynamic membrane module further includes a pressure sensor and an ultrasonic generator, wherein the pressure sensor, the ultrasonic generator, and the ultrasonic transducer are electrically connected. The filtration method includes: The ultrasonic transducer is installed inside the housing, and the dynamic membrane is installed on the mounting surface of the housing. The housing is placed in the fluid to be filtered, so that the dynamic membrane filters the fluid outside the housing into the inner cavity of the housing. When the pressure sensor detects an increase in the operating pressure of the dynamic membrane, the pressure sensor drives the ultrasonic generator to transmit an electrical signal to the ultrasonic transducer, and the ultrasonic transducer converts electrical energy into mechanical vibration to remove contaminants from the dynamic membrane. The ultrasonic generator operates continuously for 3s-60s; When the ultrasonic transducer cleans the dynamic membrane through mechanical vibration, the dynamic membrane stops filtering. When the preset cleaning termination condition is met, the ultrasonic transducer stops working and the dynamic membrane resumes filtration operation.

[0015] The filtration method according to the embodiments of this application has at least the following beneficial effects: Using the piezoelectric-enhanced dynamic membrane module of the first aspect of this application, the piezoelectric-enhanced dynamic membrane module includes a housing, a dynamic membrane, and an ultrasonic transducer. By placing the ultrasonic transducer inside the housing, the distance between the ultrasonic transducer and the dynamic membrane can be significantly shortened, thereby enhancing the vibration effect and cavitation effect on the surface of the dynamic membrane, improving the cleaning efficiency of the dynamic membrane, and shortening the operation time. The reduction in operation time, combined with the support components for supporting the dynamic membrane, allows for the removal of the dirt layer while ensuring localized cleaning, thereby reducing the impact on the membrane material and... Wear of the underlying material; After using the piezoelectrically enhanced dynamic membrane module of this application for dynamic membrane cleaning, there is no need to use strong chemical reagents to clean the dynamic membrane, reducing the risk of chemical damage or material degradation of the dynamic membrane; At the same time, since no strong chemical reagents are needed, resource consumption and potential side effects can also be reduced; In addition, the piezoelectrically enhanced dynamic membrane module of this application can significantly increase the dynamic membrane flux, which is about 10 times higher than the membrane flux of traditional membrane bioreactors; Thus, while achieving the same treatment capacity, the number of membrane modules used can be significantly reduced, thereby reducing costs and making the reactor structure more compact.

[0016] According to some embodiments of this application, the step of "when the pressure sensor detects an increase in the operating pressure of the dynamic membrane, the pressure sensor drives the ultrasonic generator to transmit an electrical signal to the ultrasonic transducer" includes: When the pressure sensor detects that the operating pressure of the dynamic membrane reaches 20kPa-40kPa, it controls the ultrasonic generator to start working.

[0017] According to some embodiments of this application, after the "ultrasonic generator operates continuously for 3s-60s", the process further includes: After each cleaning of the dynamic membrane using the piezoelectric effect, the filtrate collected within five minutes is reintroduced into the reactor to ensure the stability of the system performance.

[0018] According to some embodiments of this application, the "ultrasonic transducer converts electrical energy into mechanical vibration to remove contaminants on the dynamic membrane" includes: Adjust the piezoelectric cleaning power density of the ultrasonic transducer to make it greater than or equal to 0.78 W / cm². 2 .

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be understood by practice of this application. Attached Figure Description

[0020] The present application will be further illustrated below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments illustrated in the following drawings are exemplary and are only used to explain the present application, and should not be construed as limiting the present application.

[0021] Figure 1 This is a schematic diagram of the structure of the piezoelectric-enhanced dynamic membrane module according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of an existing dynamic membrane module; Figure 3 This is a schematic diagram of the structure of the piezoelectric-enhanced dynamic membrane module applied to an aerobic dynamic membrane bioreactor according to an embodiment of this application; Figure 4 This is a schematic diagram of the structure of the piezoelectric-enhanced dynamic membrane module applied to an anaerobic dynamic membrane bioreactor according to an embodiment of this application; Figure 5 The image shows a line graph of ultrasonic amplitude at different distances and power densities in the piezoelectric enhanced dynamic membrane assembly of this application.

[0022] Figure label: 101. Housing; 102. Dynamic membrane; 103. Supporting component; 104. Pressure ring; 201. Ultrasonic transducer; 202. Ultrasonic generator; 203. Pressure sensor; 301. Controller; 302. Aerobic tank; 303. Anoxic tank; 304. Water supply tank; 305. Water outlet tank; 306. Anaerobic tank. Detailed Implementation

[0023] The embodiments of this application are described in detail below with reference to the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements, or elements having the same or similar functions, throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0024] In the description of this application, it should be understood that the terms "center", "middle", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and other terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0025] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the number itself, and "above," "below," "within," etc. are understood to include the number itself. If expressions such as "first" or "second" are used, they are only used to distinguish technical features and should not be construed as indicating or implying relative importance, nor should they be construed as implicitly limiting the number or sequence of the technical features referred to.

[0026] In the description of this application, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can also refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood in conjunction with the specific circumstances.

[0027] In the description of this application, the use of terms such as "one implementation," "some implementations," "an embodiment," "some examples," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0028] like Figure 1 As shown in the figure, this application provides a piezoelectric-enhanced dynamic membrane module. The piezoelectric-enhanced dynamic membrane module includes a housing 101, a dynamic membrane 102, and an ultrasonic transducer 201.

[0029] The housing 101 has a hollow structure and includes a mounting surface. The mounting surface has a hollow section in the middle, which allows the inner cavity of the housing 101 to communicate with the outside of the housing 101.

[0030] Furthermore, the dynamic membrane 102 covers the mounting surface to seal the perforated portion, thereby enabling liquid exchange between the internal cavity and the external environment of the housing 101 through the dynamic membrane 102. The dynamic membrane 102 has a filtering function, filtering fluids such as sewage from outside the housing 101 into the internal cavity of the housing 101 for subsequent collection of the filtrate. Specifically, in some embodiments, the dynamic membrane 102 is made of nylon 6 material with an average pore size of 10μm-100μm. It is understood that the dynamic membrane 102 can also be made of other materials with similar functions.

[0031] It is worth noting that the ultrasonic transducer 201 is disposed within the inner cavity of the housing 101, thereby ensuring the stability of the ultrasonic transducer 201's position. Simultaneously, the ultrasonic transducer 201 can convert electrical energy into mechanical vibration through the piezoelectric effect. This mechanical vibration propagates further to the dynamic membrane 102 via the fluid within the housing 101, thereby performing piezoelectric cleaning on the dynamic membrane 102. It is understandable that the mechanical vibration generated by the ultrasonic transducer 201 can also directly act on the fluid within the housing 101, thereby creating cavitation; the bubbles formed by cavitation can also act on the dynamic membrane 102, further enhancing the cleaning effect of the dynamic membrane 102.

[0032] like Figure 2 As shown, in existing piezoelectric cleaning membrane structures, the ultrasonic transducer 201 is not directly disposed inside the housing 101. Some existing technologies place the ultrasonic transducer 201 on the outer wall of the fluid container, while others place it on the inner bottom wall, resulting in a significant distance between the ultrasonic transducer 201 and the dynamic membrane 102. Because the ultrasonic transducer 201 is far from the dynamic membrane 102, mechanical vibrations result in substantial energy loss during propagation. Therefore, to ensure the cleaning effect of the dynamic membrane 102, the cleaning time in existing technologies typically exceeds one minute, and continuous ultrasonic operation is sometimes required to achieve effective fouling control.

[0033] However, in this application, the ultrasonic transducer 201 is disposed inside the housing 101, which can significantly shorten the distance between the ultrasonic transducer 201 and the dynamic membrane 102, thereby maximizing and focusing the ultrasonic energy, ensuring that the dynamic membrane 102 receives sufficient ultrasonic energy, effectively shortening the cleaning time of the dynamic membrane 102, and reducing resource consumption while ensuring cleaning effect. Simultaneously, sufficient ultrasonic energy can effectively clean the dynamic membrane 102, eliminating the need for chemical reagents, thus reducing the risk of chemical damage and material degradation, and exhibiting better environmental friendliness. Furthermore, sufficient ultrasonic energy can also effectively clean the dynamic membrane 102 without backwashing, further reducing resource consumption and ensuring cleaning efficiency.

[0034] Previous studies have not shown that relying solely on the ultrasonic transducer 201 can replace other cleaning methods. However, the piezoelectric enhanced dynamic membrane assembly of this application achieves piezoelectric cleaning of the dynamic membrane 102 by placing the ultrasonic transducer 201 inside the housing 101, thus eliminating the need for other cleaning strategies.

[0035] In related technologies, the distance difference between the output end of the ultrasonic transducer 201 and different positions of the dynamic membrane 102 is large, which causes some areas of the dynamic membrane 102 to receive high-intensity ultrasonic energy, while other areas of the dynamic membrane 102 receive low-intensity ultrasonic energy, resulting in uneven cleaning of different areas of the dynamic membrane 102 and making it difficult to ensure the overall cleaning effect.

[0036] In this application, the output end of the ultrasonic transducer 201 is positioned directly opposite the dynamic membrane 102, making the output end of the ultrasonic transducer 201 approximately parallel to the plane containing the dynamic membrane 102. Therefore, the distance from the output end of the ultrasonic transducer 201 to various positions on the dynamic membrane 102 is approximately equal, which facilitates the uniform propagation of ultrasonic energy to all areas of the dynamic membrane 102, achieving uniform cleaning of the dynamic membrane 102 and thus ensuring the overall cleaning effect.

[0037] In some embodiments, the distance between the ultrasonic transducer 201 and the dynamic membrane 102 is 0cm-4cm. Preferably, the distance between the ultrasonic transducer 201 and the dynamic membrane 102 is less than 2cm, thereby increasing and focusing the ultrasonic energy applied to the dynamic membrane 102, ensuring cleaning efficiency and cleaning effect.

[0038] Furthermore, the output area of ​​the ultrasonic transducer 201 covers at least 80% of the area of ​​the dynamic membrane 102 to ensure a cleaning effect on the entire area of ​​the dynamic membrane 102. Additionally, it is preferable to maintain a constant distance between the ultrasonic transducer 201 and the dynamic membrane 102 as much as possible to further improve the cleaning uniformity of the dynamic membrane 102.

[0039] In some embodiments, the piezoelectric-enhanced dynamic membrane assembly further includes an ultrasonic generator 202. The ultrasonic generator 202 is electrically connected to the ultrasonic transducer 201 and can transmit electrical signals to the ultrasonic transducer 201. The ultrasonic transducer 201 then converts the electrical energy corresponding to the electrical signals into mechanical vibrations through the piezoelectric effect, thereby performing piezoelectric cleaning on the dynamic membrane 102.

[0040] Specifically, in some embodiments, the ultrasonic generator 202 operates at a frequency of 40 kHz and has an output power of 0 W-100 W. Simultaneously, the piezoelectric-enhanced dynamic membrane assembly can be configured with one or more ultrasonic generators 202 and ultrasonic transducers 201.

[0041] In addition, the piezoelectric-enhanced dynamic membrane module also includes a controller 301. The controller 301 is electrically connected to the ultrasonic generator 202 and is used to control the ultrasonic generator 202 to turn on or off.

[0042] In some embodiments, the piezoelectric-enhanced dynamic membrane assembly further includes a pressure sensor 203. The pressure sensor 203 is electrically connected to an ultrasonic generator 202. Specifically, both the pressure sensor 203 and the ultrasonic generator 202 are electrically connected to the controller 301, thereby enabling control linkage between the pressure sensor 203 and the ultrasonic generator 202.

[0043] Furthermore, the pressure sensor 203 is used to detect the operating pressure of the dynamic membrane 102. When the operating pressure reaches the corresponding set value, the pressure sensor 203 controls the ultrasonic generator 202 to turn on via the controller 301.

[0044] In some embodiments, a washer, a support member 103, and a pressure ring 104 are detachably connected to the mounting surface. The support member 103 is used to support the dynamic membrane 102 and is made of stainless steel. The support member 103 is connected to the mounting surface via a washer, i.e., the washer is positioned between the mounting surface and the support member 103 to ensure a stable connection between the support member 103 and the mounting surface.

[0045] Furthermore, the dynamic membrane 102 covers the support member 103, and the pressure ring 104 is disposed at the edge of the dynamic membrane 102, so that the pressure ring 104 and the support member 103 cooperate to clamp the dynamic membrane 102, thereby ensuring the stability of the position of the dynamic membrane 102.

[0046] Specifically, the pressure ring 104, the support component 103, and the mounting surface can be connected by fasteners or by snap-fit ​​connections, thereby achieving a detachable connection between the pressure ring 104 and the support component 103.

[0047] The following are two application examples of piezoelectric-enhanced dynamic membrane modules: like Figure 3 As shown, in the aerobic dynamic membrane bioreactor of Embodiment 1, the aerobic tank 302 and the anoxic tank 303 are interconnected, the feed tank 304 is used to supply fluid to the anoxic tank 303, the piezoelectric enhanced dynamic membrane module is disposed inside the aerobic tank 302 and is connected to the effluent tank 305.

[0048] Based on this, a 120-day laboratory-scale experiment was conducted, using a piezoelectric-enhanced dynamic membrane module to filter and treat activated sludge from urban wastewater from anoxic / aerobic processes. The influent chemical oxygen demand, ammonia nitrogen, and phosphorus concentrations were 300 mg / L, 40 mg / L, and 4 mg / L, respectively.

[0049] The dynamic membrane 102 of the piezoelectric-enhanced dynamic membrane module is a nylon 6 membrane. An ultrasonic transducer 201 is electrically connected to an ultrasonic generator 202 with a fixed operating frequency of 40 kHz and a maximum output power of 100 W. The dynamic membrane 102 has an average pore size of 20 μm and an effective filtration area of ​​0.0049 m².2 Its back is supported by a 304 stainless steel strip, and an ultrasonic transducer 201, which matches the size of the dynamic membrane 102, is attached to the stainless steel strip with a gap of 0.4cm between them.

[0050] The aerobic dynamic membrane bioreactor has a working volume of 6.4 L, with anoxic tank 303 having a volume of 4.3 L and aerobic tank 302 having a volume of 2.1 L. The dissolved oxygen concentration in aerobic tank 302 was maintained between 2 mg / L and 4 mg / L. During the experiment, the system operated at a sludge concentration of approximately 5000 mg / L and a hydraulic retention time of 8.7 hours. Fine bubble aeration was used to promote organic matter degradation and nitrification, rather than to control membrane fouling. The inoculum sludge used in the aerobic dynamic membrane bioreactor was taken from activated sludge from a sewage treatment plant in Hong Kong. Before the experiment began, the system underwent an adaptation phase until the effluent quality stabilized. Furthermore, mechanical stirring was used in each reaction tank to ensure thorough mixing of the system.

[0051] The flux of the aerobic dynamic membrane bioreactor during initial operation was 148 L / (m²). 2 This value (·h) is approximately ten times that of traditional membrane bioreactors. Whenever the transmembrane pressure reaches 20 kPa, the dynamic membrane 102 is piezoelectrically cleaned using an ultrasonic program, with a power density of 1.56 W / cm². 2 The piezoelectric cleaning lasted for 10 seconds. Throughout the operation, the dynamic membrane 102 was neither replaced nor removed from the system, and no other cleaning methods were used. After each piezoelectric cleaning, the filtrate collected within the first five minutes was reintroduced into the reactor to avoid potential interference with system performance.

[0052] Referring to Table 1, the aerobic dynamic membrane bioreactor underwent 423 cleaning cycles, with an average daily cleaning frequency of approximately 3.53 times. For the first 70 days, the cleaning frequency remained below 4 times / day. Between days 70 and 80, the cleaning frequency temporarily increased to 6.8 times / day; subsequently, over the next 10 days, the cleaning frequency returned to between 3.3 and 3.9 times / day. The average flux of the aerobic dynamic membrane bioreactor was 136.3 L / (m³). 2 The flux remained stable throughout operation, even during periods of increased cleaning frequency, decreasing only slightly by about 1% from the average flux. Furthermore, the total suspended solids in the effluent remained consistently low, averaging 4.09 mg / L, and remained stable throughout operation. The system also demonstrated a high chemical oxygen demand (COD) removal efficiency of 88.1%.

[0053] Table 1 Cleaning cycle and average flow rate of aerobic dynamic membrane bioreactor

[0054] like Figure 4 As shown, in the anaerobic dynamic membrane bioreactor of Example 2, the feed tank 304 is used to supply fluid to the anaerobic tank 306, and the piezoelectric enhanced dynamic membrane module is disposed in the anaerobic tank 306 and connected to the effluent tank 305.

[0055] Based on this, a 120-day laboratory-scale experiment was conducted. In this experiment, a piezoelectric-enhanced dynamic membrane module was used to filter and treat anaerobic sludge from a system using synthetic municipal wastewater as influent. The concentrations of chemical oxygen demand (COD), ammonia nitrogen, and phosphorus in the influent were 300 mg / L, 40 mg / L, and 4 mg / L, respectively. The configuration of the piezoelectric-enhanced dynamic membrane module was the same as in Example 1.

[0056] The working volume of the anaerobic dynamic membrane bioreactor is 8.9 L. During the experiment, the working sludge concentration was approximately 5000 mg / L, and the hydraulic retention time was 10.3 h. No aeration was performed in the anaerobic dynamic membrane bioreactor; mechanical stirring was used in each reaction unit to ensure thorough mixing. Before the experiment began, the system underwent an acclimatization phase until the effluent quality stabilized. The anaerobic dynamic membrane bioreactor was operated at 35°C.

[0057] The initial flux of the anaerobic dynamic membrane bioreactor was 148 L / (m²). 2 •h). When the transmembrane pressure reaches 20 kPa, the piezoelectric cleaning program is initiated at 1.41 W / cm². 2 The power density was used for continuous cleaning for 3.8 seconds. Throughout the operation, the dynamic membrane 102 was neither replaced nor removed from the system, and no other cleaning methods were employed. After each piezoelectric cleaning, the filtrate collected within the first 10 minutes was reintroduced into the reactor to maintain system stability.

[0058] Referring to Table 2, the anaerobic dynamic membrane bioreactor underwent a total of 71 cleaning cycles, with an average daily cleaning frequency of approximately 0.59 times. The average flux of the anaerobic dynamic membrane bioreactor reached 145.2 L / (m²). 2 The total suspended solids (TSS) concentration in the effluent remained stable throughout the operation. Furthermore, the TSS concentration in the effluent remained at a low level, averaging 12.2 mg / L, while the system achieved a chemical oxygen demand (COD) removal rate of 81.6%.

[0059] Table 2 Cleaning cycle and average flow rate of anaerobic dynamic membrane bioreactor

[0060] Furthermore, given that transient cavitation and the generation of reactive oxygen species are affected by amplitude intensity, the amplitude of the ultrasonic transducer 201 was first analyzed using a hydrophone. For example... Figure 5As shown, the results indicate that the amplitude is closely related to the distance of the ultrasonic transducer 201, which confirms that the smaller the distance between the ultrasonic transducer 201 and the dynamic membrane 102, the greater the ultrasonic energy received by the dynamic membrane 102.

[0061] Based on the above-described piezoelectric enhanced dynamic membrane module, several embodiments of the filtration method of this application are presented below.

[0062] The filtration method can be applied to piezoelectric enhanced dynamic membrane modules. The filtration method includes, but is not limited to, steps S110, S120, S130, S140, and S150.

[0063] Step S110: Install the ultrasonic transducer 201 inside the housing 101, and install the dynamic membrane 102 on the mounting surface of the housing 101. Place the housing 101 into the fluid to be filtered, so that the dynamic membrane 102 filters the fluid outside the housing 101 into the inner cavity of the housing 101. Step S120: When the pressure sensor 203 detects an increase in the operating pressure of the dynamic membrane 102, the pressure sensor 203 drives the ultrasonic generator 202 to transmit an electrical signal to the ultrasonic transducer 201, and the ultrasonic transducer 201 converts electrical energy into mechanical vibration to remove contaminants from the dynamic membrane 102. Step S130: The ultrasonic generator 202 operates continuously for 3s-60s; Step S140: When the ultrasonic transducer 201 cleans the dynamic membrane 102 by mechanical vibration, the dynamic membrane 102 stops filtering. Step S150: When the preset cleaning termination condition is met, stop the operation of the ultrasonic transducer 201 and resume the filtration operation of the dynamic membrane 102.

[0064] In some embodiments, the ultrasonic transducer 201 is first placed inside the housing 101, and then the dynamic membrane 102 is installed onto the mounting surface of the housing 101. During installation, the output end of the ultrasonic transducer 201 must be directly facing the dynamic membrane 102 and covering at least 80% of the area of ​​the dynamic membrane 102. Simultaneously, the distance between the ultrasonic transducer 201 and the dynamic membrane 102 is maintained between 0cm and 4cm to ensure that the dynamic membrane 102 receives sufficient ultrasonic energy, thereby guaranteeing the piezoelectric cleaning efficiency.

[0065] Based on this, when the pressure sensor 203 detects an increase in the operating pressure of the dynamic membrane 102, the pressure sensor 203 drives the ultrasonic generator 202 to transmit an electrical signal to the ultrasonic transducer 201. The ultrasonic transducer 201 converts electrical energy into mechanical vibration through the piezoelectric effect. The mechanical vibration can propagate to the dynamic membrane 102 through the fluid inside the housing 101. At the same time, the bubbles formed by the mechanical vibration through cavitation can also act on the dynamic membrane 102 to achieve piezoelectric cleaning of the dynamic membrane 102.

[0066] Furthermore, since the gap between the ultrasonic transducer 201 and the dynamic membrane 102 is small, the ultrasonic generator 202 can achieve the piezoelectric cleaning effect by working continuously for 3s-60s each time, without the need for long-term cleaning, which helps to reduce energy consumption and can avoid damage to the dynamic membrane 102 to a certain extent.

[0067] Furthermore, when the ultrasonic transducer 201 cleans the dynamic membrane 102 through mechanical vibration, the dynamic membrane 102 stops filtering; after the cleaning is completed, the sewage filtration operation is resumed.

[0068] Additionally, in step S120, "when the pressure sensor 203 detects an increase in the operating pressure of the dynamic membrane 102, the pressure sensor 203 drives the ultrasonic generator 202 to transmit an electrical signal to the ultrasonic transducer 201," may include, but is not limited to, the following steps: Step S210: When the pressure sensor 203 detects that the operating pressure of the dynamic membrane 102 reaches 20kPa-40kPa, the ultrasonic generator 202 starts to work.

[0069] In some embodiments, the operating pressure of the dynamic membrane 102 is associated with its flux, and the pressure sensor 203 is used to detect the operating pressure of the dynamic membrane 102. When the operating pressure of the dynamic membrane 102 increases, it indicates that the flux of the dynamic membrane 102 has decreased, and the dynamic membrane 102 needs to be cleaned.

[0070] Specifically, when the pressure sensor 203 detects that the operating pressure of the dynamic membrane 102 reaches 20kPa-40kPa, it can be determined that the flux of the dynamic membrane 102 has dropped to a state that requires cleaning. At this time, the ultrasonic generator 202 is started to clean the dynamic membrane 102.

[0071] Additionally, in step S130, "the ultrasonic generator 202 operates continuously for 3s-60s" may include, but is not limited to, the following steps: In step S310, after each piezoelectric cleaning of the dynamic membrane 102, the filtrate collected within five minutes is reintroduced into the reactor to ensure stable system performance.

[0072] In some embodiments, after each piezoelectric cleaning is completed, the filtration capacity and filtration effect of the dynamic membrane 102 may not have recovered to a stable state in a short period of time and may need to be restored to normal operation after a certain period of time.

[0073] Therefore, after each piezoelectric cleaning of the dynamic membrane 102, the filtrate collected within five minutes needs to be reintroduced into the reactor; after the dynamic membrane 102 has recovered its stable filtration capacity and filtration effect, subsequent wastewater filtration can be carried out, thereby ensuring the stability of the system performance.

[0074] Additionally, in step S120, "the ultrasonic transducer 201 converts electrical energy into mechanical vibration to remove contaminants from the dynamic membrane 102," which may include, but is not limited to, the following steps: Step S410: Adjust the piezoelectric cleaning power density of the ultrasonic transducer 201 to make it greater than or equal to 0.78 W / cm². 2 .

[0075] In some embodiments, experimental verification has shown that when the piezoelectric cleaning power density of the ultrasonic transducer 201 is greater than or equal to 0.78 W / cm², 2 At this time, the piezoelectric enhanced dynamic membrane module can achieve optimal cleaning efficiency and cleaning effect. Therefore, when using the piezoelectric enhanced dynamic membrane module, its piezoelectric cleaning power needs to be adjusted to be greater than or equal to 0.78 W / cm. 2 .

[0076] The embodiments of this application have been described in detail above with reference to the accompanying drawings, but this application is not limited to the above embodiments. Those skilled in the art can make various modifications and improvements without departing from the spirit and essence of this application, and all such modifications and improvements should fall within the protection scope of this application. Furthermore, the various embodiments of this application and the technical features therein can be combined with each other without conflict.

Claims

1. A piezoelectrically enhanced dynamic membrane module, characterized in that, include: A housing, the housing including a perforated mounting surface; A dynamic membrane, which covers the mounting surface, is used to filter fluid from outside the housing into the inner cavity of the housing; An ultrasonic transducer is disposed in the inner cavity of the housing, with its output end facing the dynamic membrane. It is used to convert electrical energy into mechanical vibration, so as to propagate the bubbles generated by the mechanical vibration and cavitation effect to the dynamic membrane through the fluid and remove the contaminant layer on the dynamic membrane.

2. The piezoelectrically enhanced dynamic membrane module according to claim 1, characterized in that, The output end of the ultrasonic transducer is directly facing the dynamic membrane. The distance between the output end of the ultrasonic transducer and the dynamic membrane is configured such that the mechanical vibration and / or cavitation effect generated by the ultrasonic transducer can act on the dynamic membrane via the fluid, thereby improving the removal effect of the contaminant layer on the dynamic membrane.

3. The piezoelectrically enhanced dynamic membrane module according to claim 1 or 2, characterized in that, The output end of the ultrasonic transducer corresponds to the area in the direction towards the dynamic membrane, which is matched with the effective filtration area of ​​the dynamic membrane, so that the main filtration area of ​​the dynamic membrane can receive the mechanical vibration and cavitation effect generated by the ultrasonic transducer, and improve the coverage and uniformity of the cleaning effect. The distance between the ultrasonic transducer and the dynamic membrane is 0cm-4cm; The output of the ultrasonic transducer covers at least 80% of the effective filtration area of ​​the dynamic membrane in the corresponding region facing the dynamic membrane.

4. The piezoelectrically enhanced dynamic membrane module according to claim 1 or 2, characterized in that, The piezoelectric enhanced dynamic membrane module also includes an ultrasonic generator, which is electrically connected to the ultrasonic transducer and is used to transmit electrical signals to the ultrasonic transducer. The output power of the ultrasonic generator is 0W-100W.

5. The piezoelectrically enhanced dynamic membrane module according to claim 4, characterized in that, The piezoelectric enhanced dynamic membrane assembly also includes a pressure sensor electrically connected to the ultrasonic generator. The pressure sensor is used to detect the operating pressure of the dynamic membrane in order to control the ultrasonic generator to turn on.

6. The piezoelectrically enhanced dynamic membrane module according to any one of claims 1-2 or 5, characterized in that, The mounting surface is detachably connected to a washer, a support component, and a pressure ring. The support component is used to support the dynamic membrane and is connected to the mounting surface through the washer. The pressure ring and the support component clamp and position the dynamic membrane.

7. A filtration method, characterized in that, Applied to the piezoelectric-enhanced dynamic membrane module as described in any one of claims 1-6, the piezoelectric-enhanced dynamic membrane module further includes a pressure sensor and an ultrasonic generator, wherein the pressure sensor, the ultrasonic generator, and the ultrasonic transducer are electrically connected, and the filtration method includes: The ultrasonic transducer is installed inside the housing, and the dynamic membrane is installed on the mounting surface of the housing. The housing is placed in the fluid to be filtered, so that the dynamic membrane filters the fluid outside the housing into the inner cavity of the housing. When the pressure sensor detects an increase in the operating pressure of the dynamic membrane, the pressure sensor drives the ultrasonic generator to transmit an electrical signal to the ultrasonic transducer, and the ultrasonic transducer converts electrical energy into mechanical vibration to remove contaminants from the dynamic membrane. The ultrasonic generator operates continuously for 3s-60s; When the ultrasonic transducer cleans the dynamic membrane through mechanical vibration, the dynamic membrane stops filtering. When the preset cleaning termination condition is met, the ultrasonic transducer stops working and the dynamic membrane resumes filtration operation.

8. The filtration method according to claim 7, characterized in that, When the pressure sensor detects an increase in the operating pressure of the dynamic membrane, the pressure sensor drives the ultrasonic generator to transmit an electrical signal to the ultrasonic transducer, including: When the pressure sensor detects that the operating pressure of the dynamic membrane reaches 20kPa-40kPa, the ultrasonic generator starts to work.

9. The filtration method according to claim 7, characterized in that, After the ultrasonic generator operates continuously for 3-60 seconds, it also includes: After each piezoelectric cleaning of the dynamic membrane, the filtrate collected within five minutes is reintroduced into the reactor to ensure system performance.

10. The filtration method according to claim 7, characterized in that, The ultrasonic transducer converts electrical energy into mechanical vibration to remove contaminants from the dynamic membrane, including: Adjust the piezoelectric cleaning power density of the ultrasonic transducer to make it greater than or equal to 0.78 W / cm². 2 .

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