An electric field driven ultrafiltration membrane water inlet pipeline type anti-fouling device

Abstract

The application provides an electric field driven ultrafiltration membrane water inlet end pipeline type adhesion prevention and pollution prevention device, which comprises a dielectric pollution remover, the dielectric pollution remover comprises a dielectric pollution remover cylinder body, an inner tube is arranged in the dielectric pollution remover cylinder body, positive electrodes and negative electrodes are arranged on the outer wall of the inner tube in a staggered manner, a gradient electric field is formed between the inner tube and the inner wall of the dielectric pollution remover cylinder body when alternating current is applied, raw water enters the dielectric pollution remover cylinder body through a water inlet, under the action of the gradient electric field, pollutants in the raw water are directionally migrated to a low field intensity area near the inner wall of the dielectric pollution remover cylinder body, and the pollutants are migrated to a pollutant collection device in the water outlet area along a spiral flow channel, the water purified through separation flows out from the water outlet and enters an ultrafiltration membrane mechanism. The dielectric pollution remover is arranged in front, pollution is blocked from the source, no chemicals and no electrochemical reaction are needed, the device is safe and suitable for subsequent processes; the device is easy to be retrofitted to an existing system, has low operation and maintenance cost, is widely applicable to harsh water quality, and can improve system efficiency and water production.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane driven by an electric field. Background Technology

[0002] Ultrafiltration technology, due to its high efficiency in solid-liquid separation, stable product water quality, and compact footprint, has been widely used in areas such as advanced municipal wastewater treatment, industrial wastewater reuse, and surface and groundwater purification. However, membrane fouling remains a key bottleneck restricting its further cost reduction and efficiency improvement. In particular, the initial fouling layer occurring at the inlet of the membrane module is considered the root cause of the rapid decline in the overall system performance.

[0003] The inlet end of an ultrafiltration membrane module is a region of dramatic hydraulic change. Here, the raw water transitions from pipe flow to porous media seepage, resulting in a sharp drop in flow velocity and shear force, the highest level of turbulence, and peak pollutant concentration. Natural organic matter (such as humic acid, proteins, and polysaccharides), inorganic colloids, and microbial cells in the water readily adhere and deposit at the membrane end face and pore inlet, under the combined effects of concentration polarization, Brownian motion, and hydraulic drag. Once this initial fouling layer forms, it rapidly alters the local physicochemical properties of the membrane surface, inducing more pollutants to accumulate more quickly, forming a dense filter cake layer, leading to a sharp increase in transmembrane pressure in a short period. Studies have shown that over 50% of the filtration resistance of membrane modules originates from severe fouling within a few millimeters of the end face.

[0004] In response to the above problems, the existing antifouling technologies and their limitations are mainly reflected in the following aspects: (1) Conventional physical cleaning has limited effect. Although hydraulic backwashing and air scrubbing can remove some of the deposited layers, they have low efficiency in removing molecular-level adhering pollutants at the membrane pore inlet and end face. The end gel layer is difficult to effectively deconstruct, and the membrane performance recovery rate gradually decreases after cleaning. (2) Chemical cleaning is prone to membrane damage and secondary pollution. Although chemical agents such as acids, alkalis, and oxidants can dissolve pollutants, frequent use will accelerate the aging and cracking of membrane materials and shorten the membrane service life. At the same time, the cleaning waste liquid must be specially treated, which increases operating costs and environmental risks, and may also impact the subsequent biological treatment system. (3) Existing electrochemical-assisted antifouling technologies have inherent drawbacks and are difficult to modify. Technologies developed in recent years, such as conductive membrane modification, electrocatalytic oxidation, and electrolytic microbubble, inherently rely on electrochemical reactions and are prone to the following problems: direct energization of the membrane surface or catalytic reactions may generate highly reactive free radicals and disinfection byproducts; gas generation during electrolysis can easily form gas embolisms, affecting mass transfer efficiency; even slightly high current densities may damage the membrane substrate or catalytic coating; and they can interfere with the ionic composition and pH of the water, affecting the safety of feedwater for subsequent advanced treatment processes such as reverse osmosis. Furthermore, these technologies typically require specially designed conductive membrane components or significant modifications to existing membrane housings and pipelines, resulting in large engineering investments, long construction periods, and difficulties in rapid deployment on existing systems, severely hindering their widespread adoption.

[0005] In summary, there is an urgent need to develop a new antifouling process that can precisely suppress the formation of the initial fouling layer at the membrane end from the source, while having zero interference with the membrane fibers and subsequent processes, and can be used to upgrade existing systems quickly and at low cost through simple external mounting. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art by providing an electric field-driven pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane.

[0007] The present invention adopts the following technical solution:

[0008] This invention provides a pipeline-type antifouling device for the inlet of an ultrafiltration membrane based on an electric field driven system. It includes a dielectric separator disposed at the front end of the ultrafiltration membrane assembly. The dielectric separator comprises a dielectric separator cylinder with an inner tube inside. The outer wall of the inner tube is provided with staggered positive and negative electrodes, which form a gradient electric field between the inner tube and the inner wall of the dielectric separator cylinder. One end of the dielectric separator cylinder has an inlet, and the other end has an outlet. Raw water enters the dielectric separator cylinder through the inlet. Under the action of the gradient electric field, pollutants in the raw water are directionally migrated to a low-field region near the inner wall of the dielectric separator cylinder, separating the pollutants. The purified water flows out from the outlet and enters the ultrafiltration membrane assembly.

[0009] Furthermore, the inner wall of the dielectric cleaning cylinder is provided with a spiral flow channel, which is distributed along the axial direction of the dielectric cleaning cylinder. Under the continuous push of the water flow, the pollutants accumulated on the inner wall of the dielectric cleaning cylinder can migrate along the spiral flow channel and reach the pollutant collection device in the outlet area.

[0010] Furthermore, the pollutant collection device includes an annular collection pipe; the annular collection pipe is fixedly installed at the outlet of the dielectric cleaning cylinder and distributed at the end of the spiral flow channel. The top of the annular collection pipe is provided with a number of collection holes distributed in a circumferential direction, and pollutants from the spiral flow channel can enter the annular collection pipe through the collection holes.

[0011] Furthermore, a drain pipe is provided on the side of the annular collecting pipe, which is connected to the annular collecting pipe. The drain pipe extends through the cylinder wall to the outside of the dielectric cleaning cylinder and is connected to the negative pressure mechanism.

[0012] Furthermore, both the positive and negative electrodes are attached to the outer wall of the inner tube, and the lengths of the positive and negative electrodes are the same as the length of the inner tube, generating a gradient electric field when alternating current is applied.

[0013] Furthermore, the cross-sections of both the positive and negative electrodes are arc-shaped, and the difference in arc length between adjacent positive and negative electrodes is 1 to 5 mm.

[0014] Furthermore, both the positive and negative electrodes are covered with an insulating layer; the insulating layer is a polyimide or alumina ceramic coating with a thickness of 100 nm to 500 μm.

[0015] Furthermore, a self-cleaning filter and a wastewater collection and separation mechanism are also provided. The inlet of the self-cleaning filter is connected to the upstream water pipe, and the outlet of the self-cleaning filter is connected to the inlet of the dielectric separator. The upstream water is first pretreated by the self-cleaning filter and then enters the dielectric separator for further purification. The clean water outlet of the dielectric separator is connected to the inlet of the ultrafiltration membrane mechanism, and the wastewater outlet of the dielectric separator is connected to the wastewater collection and separation mechanism. The clean water obtained after purification by the dielectric separator enters the ultrafiltration membrane mechanism for ultrafiltration treatment, and the wastewater obtained after purification by the dielectric separator enters the wastewater collection and separation mechanism for further filtration and separation. The wastewater collection and separation mechanism is provided with a liquid outlet and an impurity outlet. The liquid outlet is connected to the self-cleaning filter. The separated liquid re-enters the self-cleaning filter for further treatment, and the separated impurities are discharged through the impurity outlet.

[0016] Furthermore, the positive and negative electrodes are made of stainless steel or titanium alloy.

[0017] Furthermore, the axis of the dielectric cleaning cylinder coincides with the axis of the inner tube.

[0018] The beneficial effects of this invention are: (1) This invention sets up a dielectric scavenger at the front end of the ultrafiltration membrane mechanism, so that pollutants are continuously separated and discharged before entering the membrane module, which fundamentally avoids the formation of the initial fouling layer at the membrane end, significantly extends the chemical cleaning cycle, effectively suppresses the rapid rise of transmembrane pressure difference, and extends the membrane service life. The whole process does not involve electrochemical reactions, does not require any reagents, does not produce disinfection byproducts, has no impact on the quality of raw water, fully meets the feed water safety requirements of subsequent deep treatment processes such as reverse osmosis, and avoids all the inherent risks of traditional electrochemical technology; (2) The present invention adopts a pipeline structure, which can be directly connected in series with the existing water inlet pipeline. There is no need to modify the existing membrane modules or stop production for construction. The modification cost of a single unit is much lower than that of conductive membrane and other modification schemes. It is suitable for the rapid deployment and upgrading of all existing ultrafiltration systems. The equipment adopts a pulse intermittent operation strategy, with no vulnerable parts and no need to replace the filter media. Only the insulation status needs to be checked periodically. The operation and maintenance cost is much lower than that of traditional chemical cleaning and pretreatment schemes. (3) The present invention can be adapted to ultrafiltration membrane systems of various materials and has a stable anti-pollution effect on various water qualities such as mine water, municipal sewage, industrial wastewater and surface water. It is especially suitable for harsh water intake scenarios such as high colloid, high organic matter and high turbidity, and has good engineering applicability and promotion value. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the dielectric separator structure of the present invention; Figure 3 This is a schematic diagram of the spiral flow channel of the present invention; Figure 4 This is a schematic diagram of the annular sewage collection pipe of the present invention; The labels in the attached diagram are: 1-Dielectric separator, 11-Dielectric separator flow channel, 12-Dielectric separator cylinder, 13-Inner tube, 14-Annular collection and discharge pipe. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] like Figures 1-4As shown, the present invention provides an electric field driven pipeline-type antifouling device for the inlet of an ultrafiltration membrane, including a dielectric defouling device 1, which is disposed at the front end of the ultrafiltration membrane mechanism.

[0022] The dielectric separator 1 includes a dielectric separator cylinder with an inner tube 13 inside. The axis of the dielectric separator cylinder coincides with the axis of the inner tube, and an annular dielectric separator flow channel 11 connects the inner tube 13 and the dielectric separator cylinder. The outer wall of the inner tube 13 is provided with staggered positive and negative electrodes, forming a gradient electric field between the inner tube 13 and the inner wall of the dielectric separator cylinder. One end of the dielectric separator cylinder has an inlet, and the other end has an outlet. Raw water enters the dielectric separator cylinder through the inlet. Under the action of the gradient electric field, pollutants in the raw water are directionally migrated to a low-field region near the inner wall of the dielectric separator cylinder, separating the pollutants. The purified water flows out from the outlet and enters the ultrafiltration membrane mechanism. The diameter of the dielectric separator flow channel 11 matches the diameter of the existing inlet pipe to ensure no abrupt changes in hydraulic conditions.

[0023] More specifically, the positive and negative electrodes are made of stainless steel or titanium alloy, and both the positive and negative electrodes are covered with an insulating layer. The insulating layer is a polyimide or alumina ceramic coating with a thickness of 100 nm to 500 μm, which can completely isolate the electrodes from direct contact with the water.

[0024] Both the positive and negative electrodes are attached to the outer wall of the inner tube, and their lengths are the same as the inner tube 13. When an alternating current is applied, a gradient electric field is generated. The cross-sections of both the positive and negative electrodes are arc-shaped, with the difference in arc length between adjacent positive and negative electrodes being 1–5 mm. This design is used to create a stable, non-uniform electric field within the annular water flow channel, generating a sufficient dielectric force gradient. That is, by applying voltage through the insulated electrodes, a contactless, non-uniform electric field is formed within the annular flow channel, avoiding electrochemical reactions caused by direct contact between the electrodes and the water, while simultaneously providing the field strength gradient required for electric field driving.

[0025] In application, alternating current is applied to the positive and negative electrodes, creating a radially decreasing non-uniform electric field in the annular flow channel. Raw water enters the annular dielectric separator flow channel 11 through the inlet. Under the influence of the gradient electric field, all pollutants in the raw water with dielectric constants different from water (including micron-sized colloids, organic matter, microorganisms, fine-particle sediment, and calcium carbonate microcrystals) are subjected to a continuous electric field driving force. Particles in the non-uniform electric field spontaneously migrate from regions of high electric field strength to regions of low electric field strength. In this device, the electric field strength reaches its maximum on the surface of the inner tube 13, decreasing with distance from the inner tube wall, thus forming a field strength gradient decreasing from the inside to the outside. Therefore, various pollutants are continuously pushed away from the inner tube and directionally migrate to the low-field-strength enrichment region near the outer tube wall, thereby achieving pollutant separation. The separated and purified water flows out from the outlet and enters the ultrafiltration membrane mechanism.

[0026] like Figures 2-3 As shown, the inner wall of the dielectric cleaning cylinder is provided with a spiral flow channel, which is distributed along the axial direction of the dielectric cleaning cylinder. Under the continuous impetus of the water flow, the pollutants accumulated on the inner wall of the dielectric cleaning cylinder can migrate along the spiral flow channel and reach the pollutant collection device in the outlet area. During the entire migration process, the particles will continuously advance along the spiral pattern of the pipe wall under the action of the water flow, and will not accumulate on the inner side of the outer pipe wall, thus affecting the cleaning effect.

[0027] like Figure 2 and Figure 4 As shown, the pollutant collection device includes an annular collection pipe 14. The annular collection pipe 14 is fixedly installed at the outlet of the dielectric cleaning cylinder and distributed at the end of the spiral flow channel. Several circumferentially distributed collection holes are provided at the top of the annular collection pipe 14, allowing pollutants from the spiral flow channel to enter the annular collection pipe 14 through these holes. A drain pipe is provided on the side of the annular collection pipe 14, communicating with it. The drain pipe extends through the cylinder wall to the outside of the dielectric cleaning cylinder and connects to a negative pressure mechanism (low-pressure suction pump). Pollutants enriched in the outer pipe wall region, as they reach the drain pipe 14 in a spiral pattern, are continuously extracted under the action of the negative pressure mechanism. The extracted liquid accounts for 1% to 5% of the total influent volume and can be returned to the front-end sedimentation tank or treated separately. The purified water flows out from the outlet and directly enters the subsequent ultrafiltration membrane module, ensuring seamless connection between the front-end pretreatment and membrane separation processes. This continuous extraction system can promptly remove contaminants that are pushed against the outer tube wall by the electric field driving force, thereby completely blocking the path of contaminants into the subsequent ultrafiltration membrane module and eliminating the formation of the initial fouling layer at the membrane end from the root.

[0028] like Figure 1As shown, this system, based on the dielectric separator 1, also includes a self-cleaning filter and a wastewater collection and separation mechanism. The inlet of the self-cleaning filter is connected to the incoming water pipe, and its outlet is connected to the inlet of the dielectric separator 1. The incoming water first enters the self-cleaning filter for pretreatment to remove larger suspended particles and some impurities, and then enters the dielectric separator 1 for deep purification. The clean water outlet of the dielectric separator 1 is connected to the inlet of the ultrafiltration membrane mechanism, and its wastewater outlet is connected to the wastewater collection and separation mechanism. The purified water obtained after treatment by the dielectric separator 1 enters the ultrafiltration membrane mechanism for ultrafiltration; while the separated wastewater containing impurities is discharged into the wastewater collection and separation mechanism for further solid-liquid separation. The wastewater collection and separation mechanism has a liquid outlet and an impurity outlet, with the liquid outlet connected to the inlet of the self-cleaning filter or the incoming pipe. The liquid obtained after separation by the wastewater collection and separation mechanism can be returned to the self-cleaning filter to participate in the system treatment again, realizing the circulation and purification of the water. The separated impurities are discharged from the system through the impurity outlet to avoid secondary pollution. Through the above connection method, the self-cleaning filter, dielectric separator 1 and wastewater collection and separation mechanism are connected in series or partially recirculated to form a multi-stage, cyclical pretreatment and purification process, which effectively reduces the fouling load of the ultrafiltration membrane mechanism and extends its operating cycle and cleaning interval.

[0029] Working principle of this invention: This invention employs a coaxial annular pipe-type dielectric precipitator 1. Raw water enters the annular flow channel (dielectric precipitator flow channel 11) and flows through a non-uniform electric field region. All pollutants in the water with a dielectric constant different from water (including micron-sized colloids, organic matter, microorganisms, fine silt, calcium carbonate microcrystals, etc.) are driven by the electric field due to their lower dielectric constant compared to water. The electric field strength within the device exhibits a radial gradient distribution, with the highest field strength on the inner tube surface, decreasing with increasing distance from the inner tube wall, forming a field strength attenuation gradient from the inside out. Under this force field, pollutants are continuously pushed away from the inner tube wall and migrate towards the enrichment zone on the inner wall of the dielectric precipitator cylinder, remaining suspended throughout the process without contacting the tube wall or depositing. High-concentration pollutants enriched on the inner wall of the dielectric precipitator cylinder reach the annular collection and discharge pipe 14 with the water flow and are continuously extracted from the system by a low-pressure suction pump; the purified water then directly enters the subsequent ultrafiltration membrane module through the inner tube outlet.

[0030] The entire separation process of the dielectric separator 1 of this invention is purely physical-driven, relying solely on dielectric electrophoresis to achieve solid-liquid separation without involving any electrochemical reactions, redox processes, or gas evolution. This purely physical mechanism ensures that the treatment has no impact on the pH, ionic composition, or other chemical properties of the water, achieving true zero interference with downstream ultrafiltration membrane fibers and reverse osmosis processes. This technology breaks through the limitations of traditional separation methods, is not restricted by pollutant density or particle size, and can achieve effective separation as long as there is a difference in dielectric constant between the pollutant and water. It comprehensively covers the core pollutant types that cause membrane fouling, achieving a pollutant separation efficiency of over 90%, providing a reliable guarantee for the long-term and stable operation of the membrane system. Furthermore, the entire device of this invention has a pipeline modular structure, which can be directly connected in series in the inlet pipe of the ultrafiltration membrane module without modifying the internal structure of the existing membrane module or the original pipeline, enabling rapid upgrades to existing systems.

[0031] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane based on an electric field driven method, characterized in that, Includes a dielectric separator (1), which is installed at the front end of the ultrafiltration membrane mechanism; The dielectric cleaner (1) includes a dielectric cleaner cylinder, and an inner tube (13) is provided inside the dielectric cleaner cylinder. The outer wall of the inner tube (13) is provided with alternating positive and negative electrodes, and the positive and negative electrodes form a gradient electric field between the inner tube (13) and the inner wall of the dielectric cleaner cylinder. One end of the dielectric cleaning cylinder is provided with a water inlet and the other end is provided with a water outlet. Raw water enters the dielectric cleaning cylinder through the water inlet. Under the action of the gradient electric field, pollutants in the raw water can be directionally migrated to the low field strength region near the inner wall of the dielectric cleaning cylinder, thus separating the pollutants. The purified water flows out from the water outlet and enters the ultrafiltration membrane mechanism.

2. The pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane based on electric field drive according to claim 1, characterized in that, The inner wall of the dielectric cleaning cylinder is provided with a spiral flow channel, which is distributed along the axial direction of the dielectric cleaning cylinder. Under the continuous push of the water flow, the pollutants accumulated on the inner wall of the dielectric cleaning cylinder can migrate along the spiral flow channel and reach the pollutant collection device in the outlet area.

3. The pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane based on electric field drive according to claim 2, characterized in that, The pollutant collection device includes an annular collection pipe (14). The annular collection pipe (14) is fixedly installed at the outlet of the dielectric cleaning cylinder and distributed at the end of the spiral flow channel. The top of the annular collection pipe (14) is provided with several collection holes distributed in a ring direction. Pollutants from the spiral flow channel can enter the annular collection pipe (14) through the collection holes.

4. The pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane based on electric field drive according to claim 3, characterized in that, A drain pipe is provided on the side of the annular collection pipe (14). The drain pipe is connected to the annular collection pipe (14). The drain pipe extends through the cylinder wall to the outside of the dielectric cleaning cylinder and is connected to the negative pressure mechanism.

5. The pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane based on electric field drive according to claim 1, characterized in that, Both the positive and negative electrodes are attached to the outer wall of the inner tube. The lengths of the positive and negative electrodes are the same as the length of the inner tube (13). When alternating current is applied, a gradient electric field is generated.

6. The pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane based on electric field drive according to claim 5, characterized in that, The cross-sections of both the positive and negative electrodes are arc-shaped, and the difference in arc length between adjacent positive and negative electrodes is 1 to 5 mm.

7. The pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane based on electric field drive according to claim 1, characterized in that, Both the positive and negative electrodes are covered with an insulating layer; the insulating layer is a polyimide or alumina ceramic coating with a thickness of 100 nm to 500 μm.

8. The pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane based on electric field drive according to claim 1, characterized in that, It is also equipped with a self-cleaning filter and a wastewater collection and separation mechanism; The inlet of the self-cleaning filter is connected to the front-end water pipe, and the outlet of the self-cleaning filter is connected to the inlet of the dielectric separator (1). The front-end water is first pretreated by the self-cleaning filter and then enters the dielectric separator (1) for further purification. The clean water outlet of the dielectric separator (1) is connected to the inlet of the ultrafiltration membrane mechanism, and the wastewater outlet of the dielectric separator (1) is connected to the wastewater collection and separation mechanism. The clean water obtained after purification by the dielectric separator (1) enters the ultrafiltration membrane mechanism for ultrafiltration treatment, and the wastewater obtained after purification by the dielectric separator (1) enters the wastewater collection and separation mechanism for further filtration and separation. The wastewater collection and separation mechanism is provided with a liquid outlet and an impurity outlet. The liquid outlet is connected to the self-cleaning filter. The separated liquid re-enters the self-cleaning filter for further treatment, and the separated impurities are discharged through the impurity outlet.

9. The pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane based on electric field drive according to claim 1, characterized in that, The positive and negative electrodes are made of stainless steel or titanium alloy.

10. The pipeline-type anti-fouling device for the inlet end of an ultrafiltration membrane based on electric field drive according to claim 1, characterized in that, The axis of the dielectric cleaning cylinder coincides with the axis of the inner tube (13).

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