Magnetic response coagulation-ultrafiltration coupling water treatment device and method

Abstract

The invention relates to the technical field of water treatment, in particular to a magnetic response coagulation-ultrafiltration coupling water treatment device and method. The device mainly comprises a coagulant adding unit, a coagulation reaction unit, an ultrafiltration unit, a sensing unit and a control unit which are sequentially communicated along the water flow direction. The coagulant adding unit is used for realizing accurate adding of a medicament, the coagulation reaction unit is a key place for regulating and controlling formation of flocs, the ultrafiltration unit is used for final solid-liquid efficient separation and actively controlling membrane pollution, and the magnetic response assembly can generate a magnetic field around a membrane assembly. The magnetic field can guide magnetic flocs in water to form a loose and high-permeability dynamic protection layer on the surface of the membrane in the filtering stage. The control unit is in signal connection with the sensing unit, and is used for dynamically adjusting the adding amount of the precise metering pump, the rotating speed combination of the stirring paddles in the gradient flocculation area, the magnetic field intensity of the magnetic response assembly and the like. The self-adaptive water treatment system is constructed by integrating intelligent feeding, gradient flocculation, magnetic response membrane separation and control.

Description

A magnetically responsive coagulation-ultrafiltration coupled water treatment device and method Technical Field

[0001] This invention relates to the technical field of water treatment, and specifically to a magnetically responsive coagulation-ultrafiltration coupled water treatment device and method. Background Technology

[0002] Coagulation-ultrafiltration (CO-UF) coupling technology transforms colloids, suspended solids, and some dissolved organic matter in water into easily separable flocs through a coagulation process. These flocs are then efficiently separated by an ultrafiltration membrane, and the technology has been widely applied in advanced municipal wastewater treatment, drinking water purification, and industrial wastewater pretreatment. However, current CO-UF coupling processes and devices suffer from several problems: First, coagulant dosing relies heavily on manual, timed sampling and experience-based adjustments, resulting in feedback lag and an inability to respond in real-time to sudden fluctuations in raw water turbidity or organic matter concentration, easily leading to insufficient or excessive dosing. Second, existing coagulation reactors often employ fixed or single-gradient stirring modes, resulting in a wide range of floc particle sizes. Flocs that are too small easily penetrate membrane pores, while those that are too large are more prone to compression into high-resistivity filter cakes due to their loose structure, both accelerating membrane fouling. Third, regarding membrane materials and fouling control, ultrafiltration membranes (such as PVDF membranes) often have hydrophobic surfaces, easily adsorbing humic acids, proteins, and other organic matter. This fails to dynamically synergize with the characteristics of the flocs formed during coagulation, leading to generally shorter membrane lifespans. Furthermore, the coagulation unit and the ultrafiltration membrane tank are often independent structures with long connecting pipelines. During transportation, the flocs are easily broken or deposited due to shearing, which not only reduces the floc utilization efficiency but also increases the complexity of maintenance. Ultimately, this results in severe membrane fouling, unstable treatment efficiency, and high operating energy consumption and maintenance costs. Summary of the Invention

[0003] The purpose of this invention is to solve at least one problem in the background art.

[0004] To address the above problems, this invention provides a magnetically responsive coagulation-ultrafiltration coupled water treatment system and method.

[0005] On one hand, the present invention provides a magnetically responsive coagulation-ultrafiltration coupled water treatment system, comprising: a coagulant dosing unit, the coagulant dosing unit including at least one reagent tank, a precision metering pump and a static mixer, the reagent tank, the precision metering pump and the static mixer being connected sequentially; a coagulation reaction unit, the cavity of the coagulation reaction unit being divided into a rapid mixing zone, a gradient flocculation zone and a steady flow zone along the water flow direction, the gradient flocculation zone being provided with at least two sets of stirring blades with different stirring intensities; and an ultrafiltration unit, the ultrafiltration unit including a membrane module and a magnetically responsive module, the... The membrane fiber surface of the membrane module is loaded with a magnetic composite modification layer, and the magnetic response component is used to generate an adjustable magnetic field in the space around the membrane module; the sensing unit includes online sensors respectively disposed at the raw water inlet of the coagulant dosing unit, the outlet of the coagulation reaction unit, and the outlet of the ultrafiltration unit; and the control unit is communicatively connected to the sensing unit and is used to dynamically adjust the dosing amount of the precision metering pump, the rotation speed of the agitator, and the magnetic field strength of the magnetic response component according to the monitoring data of the sensing unit.

[0006] Preferably, the coagulation reaction unit includes a vertically arranged cylindrical cavity; a first baffle and a second baffle are arranged sequentially along its axial direction in the cylindrical cavity to divide the cylindrical cavity from top to bottom into the rapid mixing zone, the gradient flocculation zone and the flow stabilization zone; both the first baffle and the second baffle are provided with multiple flow holes to guide water flow through each functional zone sequentially.

[0007] Preferably, the gradient flocculation zone is provided with a first-stage agitator, a second-stage agitator, and a third-stage agitator in sequence from top to bottom; the blade diameters of the first-stage agitator, the second-stage agitator, and the third-stage agitator increase in a gradient; the gradient flocculation zone is also provided with an adjustable-angle arc-shaped guide plate.

[0008] Preferably, the upper part of the rapid mixing zone is provided with a high-speed three-bladed agitator, the top of the gradient flocculation zone is provided with a jet nozzle, and the flow stabilization zone is filled with honeycomb packing.

[0009] Preferably, the ultrafiltration unit includes a cylindrical membrane housing, a membrane module disposed within the membrane housing, a magnetic response component disposed around the membrane housing, and a cleaning component disposed on the membrane housing; the membrane module is a vertically suspended hollow fiber membrane module; the magnetic response component includes at least one set of electromagnetic coils; the cleaning component includes an air inlet disposed above the membrane module, a backwash water inlet disposed at the bottom of the membrane housing, and a chemical cleaning dosing port disposed at the top or side wall of the membrane housing.

[0010] Preferably, the membrane module comprises multiple hollow fiber membrane filaments bundled together to form a membrane filament bundle, the upper and lower ends of the membrane filament bundle being sealed by epoxy resin casting to form an upper tube sheet and a lower tube sheet; the membrane module is sealed to the top of the membrane shell through the upper tube sheet, thereby being vertically suspended inside the membrane shell.

[0011] Preferably, the hollow fiber membrane filament is made of polyvinylidene fluoride with a magnetic composite modified layer loaded on its surface; the magnetic composite modified layer contains Fe3O4 nanoparticles and quaternized chitosan.

[0012] Preferably, it also includes a concentrate return pipeline, one end of which is connected to the concentrate outlet of the ultrafiltration unit, and the other end is connected to the rapid mixing zone of the coagulation reaction unit.

[0013] On the other hand, the present invention also includes a method based on the above-mentioned water treatment system, comprising the following steps: a monitoring step: real-time monitoring of the raw water quality parameters, the floc state parameters at the outlet of the coagulation reaction unit, and the operating parameters of the ultrafiltration unit through the sensing unit; a dynamic control step: the control unit calculates and outputs control commands based on the real-time data obtained in the monitoring step, to dynamically adjust the dosage of the coagulant dosing unit, adjust the rotation speed combination of the stirring paddles in the gradient flocculation zone, and adjust the magnetic field strength generated by the magnetic response component; a coagulation reaction step: the raw water and the added agent are rapidly mixed in the rapid mixing zone, and then flow sequentially through the gradient flocculation zone and the steady flow zone to form flocs with target particle size characteristics, and the supernatant is separated; a magnetic response ultrafiltration step: the supernatant is passed into the ultrafiltration unit and filtered and separated under the action of the magnetic field to obtain permeate; and a cleaning and maintenance step: the cleaning component is triggered to clean the membrane module according to the preset cycle of the ultrafiltration unit.

[0014] Preferably, in the coagulation reaction step, the average particle size of the formed flocs is controlled within the range of 150-200 μm by controlling the rotation speed of the stirring paddles at each stage in the gradient flocculation zone; in the magnetic response ultrafiltration step, the magnetic field strength is adjusted according to the average particle size of the flocs, and the larger the average particle size of the flocs, the higher the applied magnetic field strength.

[0015] The beneficial effects of this invention are as follows: This invention provides a magnetic response coagulation-ultrafiltration coupled water treatment system. Through a real-time closed-loop control system comprised of online sensors, control units, and precision metering pumps installed at the raw water inlet, it completely changes the extensive dosing mode that relies on manual experience. This achieves precise, on-demand dosing of coagulants, preventing a series of problems caused by insufficient or excessive dosage from the source, thus improving coagulation efficiency while reducing reagent consumption. Addressing the problem of poor floc quality, the system incorporates a gradient flocculation zone within the coagulation reaction unit, equipped with paddles of varying stirring intensities. Through flow field control, it can stably form ideal flocs with uniform particle size and dense structure. These flocs are neither easily penetrated by membrane pores nor easily compressed into a dense filter cake, thereby significantly reducing the load on subsequent membrane separation from the source of pollution. In terms of membrane fouling control, the system employs membrane modules with surface-loaded magnetic composite modified layers, combined with an external adjustable magnetic field, transforming the membrane separation process from passive interception to active collaboration. During the filtration stage, the magnetic field guides magnetic flocs to form a loose, dynamic protective layer. In the cleaning stage, altering the magnetic field effectively assists in the removal of pollutants, enhancing the system's anti-fouling capabilities and extending membrane lifespan. Furthermore, the system connects each process unit sequentially, achieving a high degree of integration. This significantly shortens the process flow, reduces floc breakage and deposition during transport, and lowers overall system energy consumption and maintenance complexity. The coordinated operation of each process unit through a control unit ensures stable and efficient long-term operation, achieving energy conservation and consumption reduction.

[0016] The magnetic response coagulation-ultrafiltration coupled water treatment method of the present invention has the same beneficial effects as the above-mentioned magnetic response coagulation-ultrafiltration coupled water treatment system compared with the prior art, and will not be repeated here. Attached Figure Description

[0017] Figure 1 is a schematic diagram of a magnetic response coagulation-ultrafiltration coupled water treatment system according to an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached diagram: 1-Coagulant dosing unit; 11-Reagent tank; 12-Precision metering pump; 13-Static mixer; 2-Coagulation reaction unit; 21-Rapid mixing zone; 211-High-speed three-blade agitator; 22-Gradient flocculation zone; 221-First-stage agitator; 222-Second-stage agitator; 223-Third-stage agitator; 224-Arc-shaped guide plate; 225-Jet nozzle; 23-Stabilizing flow zone; 3-Ultrafiltration unit; 31-Membrane module; 311-Air inlet; 312-Backwash inlet; 313-Chemical cleaning dosing port; 314-Upper tube sheet; 315-Lower tube sheet; 32-Magnetic response component; 33-Membrane housing; 41-Online sensor; 5-Control unit; 6-Concentrate return pipeline. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0020] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or components, and are not intended to limit the order of functions performed by these devices, modules, or components or their interdependencies.

[0021] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0022] To address the problems existing in the aforementioned related technologies, this invention provides a magnetic response coagulation-ultrafiltration coupled water treatment system and method.

[0023] Referring to Figure 1, one embodiment of the present invention provides a magnetic response coagulation-ultrafiltration coupled water treatment system, which includes a coagulant dosing unit 1, a coagulation reaction unit 2, an ultrafiltration unit 3, a sensing unit, and a control unit 5. The coagulant dosing unit 1 includes at least one reagent tank 11, a precision metering pump 12, and a static mixer 13. The cavity of the coagulation reaction unit 2 is divided into a rapid mixing zone 21, a gradient flocculation zone 22, and a steady flow zone 23 along the water flow direction. The gradient flocculation zone 22 is equipped with at least two sets of stirring blades with different stirring intensities. The ultrafiltration unit 3 includes a membrane module 31 and a magnetic response component 32. The membrane fiber surface of the membrane module 31 is loaded with a magnetic composite modified layer. The magnetic response component 32 is used to generate an adjustable magnetic field in the space around the membrane module 31. The sensing unit includes online sensors 41 respectively installed at the raw water inlet of the coagulant dosing unit 1, the outlet of the coagulation reaction unit 2, and the outlet of the ultrafiltration unit 3. The control unit 5 is communicatively connected to the sensing unit and is used to dynamically adjust the dosing amount of the precision metering pump 12, the rotation speed of the stirring blade, and the magnetic field strength of the magnetic response component 32 according to the monitoring data of the sensing unit.

[0024] It should be noted that the coagulant dosing unit 1, the coagulation reaction unit 2, and the ultrafiltration unit 3 are process units arranged sequentially along the water flow direction. In the coagulant dosing unit, the reagent tank 11 is used to store the reagent, the precision metering pump 12 is used to accurately control the reagent dosage, and the static mixer 13 is used to rapidly premix the reagent with the raw water. The coagulation reaction unit 2 is used to regulate the floc formation process. The gradient flocculation zone 22 is equipped with at least two sets of stirring paddles. Through gradually decreasing stirring intensity, the micro-flocs are guided to collide, grow, and form flocs with uniform particle size and dense structure. The ultrafiltration unit 3 is used to achieve efficient solid-liquid separation and actively control membrane fouling. The ultrafiltration unit 3 includes a membrane module 31 and a magnetic response component 32. The membrane fiber surface of the membrane module 31 is loaded with a magnetic composite modification layer to give it magnetic response characteristics. The magnetic response component 32 (such as an electromagnetic coil arranged around the membrane module 31) can generate a magnetic field with adjustable intensity and mode around the membrane module 31. By controlling the magnetic field, magnetic flocs in the water can be guided to form a loose protective layer on the membrane surface, or to assist in the removal of pollutants during washing. The sensing unit acts as the sensory nervous system, including an online sensor 41 at the raw water inlet (for detecting turbidity, COD, Zeta potential, etc.), an online sensor 41 at the outlet of coagulation reaction unit 2 (for detecting floc particle size and turbidity), and online sensors 41 at the inlet and outlet of ultrafiltration unit 3 (for detecting transmembrane pressure difference, product water quality, etc.). The control unit 5 can employ an industrial-grade programmable controller with a built-in adaptive control algorithm model (e.g., a neural network-based model). Using raw water quality parameters, real-time floc particle size, and the rate of increase in transmembrane pressure difference as input, it calculates and outputs the optimal coagulant dosage, gradient stirring intensity, and magnetic field strength strategy. Therefore, the control unit 5 acts as the decision-making center and is signal-connected to the sensing unit. The control unit 5 receives real-time monitoring data from all online sensors 41, processes it through a built-in adaptive control algorithm, and outputs control commands. It can dynamically adjust the dosage of coagulant, the rotation speed of each agitator in the gradient flocculation zone 22, and the magnetic field strength and operating mode of the magnetic response component 32 in real time according to raw water quality parameters, real-time floc particle size, and transmembrane pressure rise rate. This enables closed-loop optimization control of various process parameters, ensuring that the system can maintain efficient and stable operation when faced with water quality fluctuations.

[0025] In summary, the magnetic response coagulation-ultrafiltration coupled water treatment system of the present invention optimizes each process unit, integrates each process unit, and achieves coordinated linkage through the control unit, which can ensure stable and efficient long-term operation and achieve the purpose of energy saving and consumption reduction.

[0026] In one embodiment of the present invention, the coagulation reaction unit 2 includes a vertically arranged cylindrical cavity; a first baffle and a second baffle are arranged sequentially along its axial direction in the cylindrical cavity to divide the cylindrical cavity from top to bottom into a rapid mixing zone 21, a gradient flocculation zone 22 and a flow stabilization zone 23; both the first baffle and the second baffle are provided with multiple flow holes to guide water flow through each functional zone sequentially.

[0027] It should be noted that the physical separation between the first and second baffles ensures that the flow field environments of the three functional zones—rapid mixing, gradient flocculation, and steady-flow settling—are relatively independent, avoiding short-circuiting and back-mixing of the water flow. Simultaneously, the design of the flow passages controls the water flow to enter the next zone at an appropriate velocity and flow pattern. This ensures the integrity of the flocs during transport, reduces breakage caused by severe shearing, and promotes effective pre-settling of the flocs in the steady-flow zone 23. This improves the coagulation effect while providing the subsequent ultrafiltration unit 3 with feed water that has better floc characteristics and a more stable load.

[0028] In one embodiment of the present invention, a first-stage agitator 221, a second-stage agitator 222, and a third-stage agitator 223 are arranged sequentially from top to bottom in the gradient flocculation zone 22; the blade diameters of the first-stage agitator 221, the second-stage agitator 222, and the third-stage agitator 223 increase in a gradient; an adjustable-angle arc-shaped guide plate 224 is also provided in the gradient flocculation zone 22.

[0029] It should be noted that the three arc-shaped guide plates 224 are uniformly distributed 120° circumferentially along the inner wall of the cylindrical cavity of the coagulation reaction unit 2. The arc-shaped guide plates 224 work together with the agitator with a gradient diameter to construct an optimized flow field within the gradient flocculation zone 22, thereby achieving efficient and controllable floc growth. Specifically, when the agitator drives the water flow to rotate, the water flow impacts the concave surface of the arc-shaped guide plates 224 under centrifugal force and is precisely guided along its tangential direction, thus converting part of the axial kinetic energy into stable horizontal swirling kinetic energy. The swirling flow generated by the three arc-shaped guide plates 224 superimposes and merges in the central region of the cylindrical cavity, ultimately forming a uniform and stable spiral downward flow field across the entire cross-section. This extends the effective hydraulic residence time and collision path of the floc particles, creating kinetic conditions for the flocs to grow and compact gradually through adsorption; the forced swirling flow also effectively eliminates dead zones in the water flow, preventing the deposition and accumulation of flocs on the cavity wall. Meanwhile, the design of a top-to-bottom gradient increase in impeller diameter, combined with a gradient decrease in rotational speed, achieves a gradual decrease in stirring intensity. This ensures sufficient shear force to form a large number of micro-floc nuclei in the early stages of flocculation, while providing gentler and wider-ranging agitation in the middle and later stages to promote floc growth rather than breakage. Therefore, the flow field constructed by the arc-shaped guide vane 224, together with the energy input from the gradient stirring, can actively control the floc particle size distribution within a narrower range (e.g., 150-200 μm) that is most favorable for subsequent membrane separation processes. Such flocs are neither prone to penetrating membrane pores nor easily compressed into a dense filter cake, thus significantly reducing the load on subsequent membrane separation from the source of contamination.

[0030] In one embodiment of the present invention, a high-speed three-bladed agitator 211 is provided at the upper part of the rapid mixing zone 21, a jet nozzle 225 is provided at the top of the gradient flocculation zone 22, and honeycomb filler is filled in the flow stabilization zone 23.

[0031] It should be noted that the high-speed three-bladed agitator 211 operates at a high speed (e.g., 200-300 r / min), generating high-intensity turbulence in the rapid mixing zone 21. This ensures that the added coagulant mixes rapidly with the raw water within a short time, completing the initial destabilization of the colloidal particles. Next, the jet nozzle 225, located at the top of the gradient flocculation zone 22, utilizes the residual pressure of the inlet water to form a high-speed jet (flow velocity 1.5-2.0 m / s). Its function is to generate strong micro-scale shear and disturbance, further dispersing any remaining agent clusters and promoting frequent and effective collisions between the destabilized colloidal particles, thereby rapidly generating a large number of uniform, fine initial flocs (microflocs). The water carrying a large number of initial flocs enters the steady-flow zone 23. The honeycomb packing material filling this zone has high porosity and a regular parallel channel structure. Its core function is to efficiently break up large-scale vortices from the preceding zone, allowing the water flow to smoothly and rapidly transition from a highly turbulent state to a near-laminar state. It effectively protects the formed flocs from damage and promotes the initial sedimentation and separation of some of the larger, formed flocs.

[0032] In one embodiment of the present invention, the ultrafiltration unit 3 includes a cylindrical membrane housing 33, a membrane module 31 disposed within the membrane housing 33, a magnetic response component 32 disposed around the membrane housing 33, and a cleaning component disposed on the membrane housing 33; the membrane module 31 is a vertically suspended hollow fiber membrane module; the magnetic response component 32 includes at least one set of electromagnetic coils; the cleaning component includes an air inlet 311 disposed above the membrane module 31, a backwash water inlet 312 disposed at the bottom of the membrane housing 33, and a chemical cleaning dosing port 313 disposed at the top or side wall of the membrane housing 33.

[0033] It should be noted that the ultrafiltration unit 3 is the core component for achieving solid-liquid separation and anti-fouling operation. The membrane module 31 is vertically suspended in the middle of the membrane housing 33, and its structural design facilitates the formation of a uniform flow channel. During operation, the supernatant treated by the coagulation reaction unit 2 enters the membrane housing 33 and flows along the outer side of the vertically suspended hollow fiber membrane bundle under pressure. During this process, water molecules and dissolved substances smaller than the membrane pore size penetrate the membrane wall and enter its hollow inner cavity under the action of the transmembrane pressure difference, forming clean permeate water. The permeate water collects upward along the inner cavity of the membrane fibers and is finally discharged through the water collection channel in the center of the upper tube sheet 314. Most of the suspended particles, colloids, and high molecular flocs generated by coagulation in the water are completely retained on the outer side of the membrane fibers, forming concentrate (concentrated water) which is discharged from the corresponding outlet of the membrane housing 33.

[0034] The magnetic composite modified layer loaded on the membrane fiber surface works in conjunction with the controllable magnetic field generated by the magnetic response component 32 outside the membrane shell 33. During the filtration stage, the magnetic field can guide the magnetic flocs / particles in the water to arrange themselves in an orderly manner on the membrane surface, forming a dynamic protective layer with high porosity and good water permeability. This effectively slows down the dense adhesion of pollutants to the membrane surface while enhancing retention. During the cleaning stage (such as backwashing), by adjusting or turning off the magnetic field, the interaction force between pollutants and the membrane surface can be significantly weakened, thereby greatly improving the stripping efficiency of physical cleaning.

[0035] Furthermore, the air inlet 311 is located directly above the membrane module 31, and the backwash water inlet 312 is located at the bottom of the membrane housing 33, so that the compressed air and the backwash water flow form a strong reverse shear, effectively removing deposits on the membrane surface. The chemical cleaning dosing port 313 is located at the top or upper side of the membrane housing 33, providing convenience for regular deep chemical cleaning. A drain port can also be provided at the bottom of the membrane housing 33 for draining liquid or sludge from the membrane housing 33 after long-term shutdown or cleaning.

[0036] In one embodiment of the present invention, the membrane assembly 31 includes a bundle of multiple hollow fiber membrane filaments to form a membrane filament bundle, and the upper and lower ends of the membrane filament bundle are sealed by epoxy resin casting to form an upper tube sheet 314 and a lower tube sheet 315; the membrane assembly 31 is sealed to the top of the membrane shell 33 through the upper tube sheet 314, thereby being vertically suspended inside the membrane shell 33.

[0037] It should be noted that epoxy resin can be cast to form the upper tube sheet 314 and the lower tube sheet 315. The upper tube sheet 314 and the lower tube sheet 315 not only achieve the sealing of the end of each membrane fiber, effectively preventing short circuits between raw water and product water, but the rigid support structure formed by the whole also ensures that the entire membrane module 31 can be stably and vertically suspended during operation and cleaning, laying the foundation for a uniform flow field and effective cleaning.

[0038] The arrangement of the membrane module 31, vertically suspended within the membrane housing 33, facilitates the detachment of trapped solid particles from the membrane surface under gravity during the filtration stage. Simultaneously, the magnetic field guides magnetic flocs to form a loose, highly permeable dynamic filtration layer on the vertical membrane surface. During the cleaning stage (especially combined air-water cleaning), the downward airflow and upward waterflow create a uniform and strong radial shear force along the membrane fiber length, efficiently stripping contaminants adhering to the membrane surface. Furthermore, adjusting the magnetic field can further weaken contaminant adhesion, achieving a simultaneous improvement in separation efficiency and antifouling capability in conjunction with the aforementioned hydraulic cleaning.

[0039] In one embodiment of the present invention, the hollow fiber membrane filament is made of polyvinylidene fluoride with a magnetic composite modified layer loaded on its surface; the magnetic composite modified layer contains Fe3O4 nanoparticles and quaternized chitosan.

[0040] It should be noted that, using polyvinylidene fluoride (PVDF) hollow fiber membrane as the matrix, surface composite modification overcomes the inherent defects of traditional PVDF membranes, such as hydrophobicity and easy adsorption of organic pollutants. Fe3O4 nanoparticles are uniformly dispersed in the modified layer, providing the membrane with stable and reliable superparamagnetism, enabling it to respond sensitively to the magnetic field generated by the external magnetic response component 32. This is a prerequisite for achieving dynamic control such as magnetic field-guided floc arrangement and assisted cleaning. Quaternized chitosan is a natural polymer modifier with both good hydrophilicity and cationic properties. Its introduction significantly improves the hydrophilicity of the membrane surface and reduces the pure water flux decay rate. Simultaneously, its cationic groups can adsorb negatively charged pollutants (such as humic acid) through electrostatic interactions, mitigating organic pollution to some extent. The Fe3O4 nanoparticles and quaternized chitosan are not simply mixed, but rather form an organic-inorganic composite structure through chemical bonding and tight encapsulation. This structure ensures the robustness and durability of the modified layer, preventing the magnetic particles from detaching during long-term operation and cleaning. This transforms the membrane itself from a passive filtration medium into a functional component that actively coordinates with external magnetic fields, influent water quality, and the coagulation process. In actual operation, it allows the system to flexibly alter the interfacial behavior of the membrane surface by adjusting the external magnetic field, thereby achieving optimal performance in different stages such as filtration, antifouling, and cleaning, fundamentally improving the long-term operational stability and antifouling capability of the membrane module 31.

[0041] In one embodiment of the present invention, a concentrate return pipeline 6 is further included, one end of which is connected to the concentrate outlet of the ultrafiltration unit 3, and the other end is connected to the rapid mixing zone 21 of the coagulation reaction unit 2.

[0042] It should be noted that when the raw water quality fluctuates (such as a sudden increase in pollutant concentration), increasing the reflux ratio can introduce more active flocs and residual coagulation capacity into the rapid mixing zone, which is equivalent to enhancing the buffering and shock load resistance of the system front end, helping to maintain the stable operation of the entire process. Simultaneously, through the intelligent adjustment of the reflux flow rate by the control unit 5, it can be dynamically matched with the real-time influent water quality and reagent dosing strategy, further optimizing the coagulation effect. On the other hand, this invention also includes a method based on the above-mentioned water treatment system, comprising the following steps: Monitoring step: Real-time monitoring of raw water quality parameters, floc state parameters at the outlet of coagulation reaction unit 2, and operating parameters of ultrafiltration unit 3 via the sensing unit; the above monitoring step is the basis for achieving adaptive operation. By deploying online sensors 41 at key nodes (raw water, after coagulation, and after membrane separation), water quality fluctuations (such as sudden changes in turbidity and COD) and process states (such as floc particle size and transmembrane pressure difference TMP) can be captured in real time and continuously.

[0043] Dynamic control steps: Based on real-time data acquired during the monitoring process, control unit 5 calculates and outputs control commands to dynamically adjust the dosage of coagulant in coagulant dosing unit 1, the rotation speed combination of the agitator in gradient flocculation zone 22, and the magnetic field strength generated by magnetic response component 32. For example, when the turbidity of the raw water increases, the dosage of coagulant can be increased simultaneously, the rotation speed combination of gradient flocculation zone 22 can be finely adjusted to maintain the target floc particle size, and the magnetic field strength can be appropriately increased to cope with the possible increase in particle load. This multi-parameter linkage control achieves dynamic matching and overall optimization of process conditions.

[0044] Coagulation reaction steps: The raw water and the added reagent are rapidly mixed in the rapid mixing zone 21, and then flow sequentially through the gradient flocculation zone 22 and the steady flow zone 23 to form flocs with the target particle size characteristics, and the supernatant is separated. Under different influent conditions, relatively ideal flocs with uniform particle size and dense structure (such as 150-200μm) can be stably produced, creating the optimal influent conditions for subsequent membrane separation.

[0045] Magnetic response ultrafiltration steps: The supernatant is passed into ultrafiltration unit 3 and filtered and separated under the action of a magnetic field to obtain product water; the intensity of the magnetic field can be adjusted according to the characteristics of the flocs, and during filtration, it guides the formation of a highly permeable dynamic filter layer, transforming the fouling layer into a loose dynamic protective layer, which significantly slows down the rise of TMP and achieves a unified improvement in separation efficiency and anti-fouling ability.

[0046] Cleaning and maintenance procedures: According to the preset cycle of ultrafiltration unit 3, the cleaning component is triggered to clean membrane module 31. Cleaning can be performed on demand based on real-time parameters such as the rate of increase of transmembrane pressure difference (TMP) and permeate water quality. During cleaning, the combined effect of gas-water linkage and possible magnetic field switching (such as shutting down or changing direction) significantly improves cleaning efficiency and reduces energy consumption and chemical reagent consumption.

[0047] In one embodiment of the present invention, in the coagulation reaction step, the rotation speed of each stage of the stirring paddle in the gradient flocculation zone 22 is controlled to keep the average particle size of the formed flocs within the range of 150-200 μm; in the magnetic response ultrafiltration step, the magnetic field strength is adjusted according to the average particle size of the flocs, and the larger the average particle size of the flocs, the higher the applied magnetic field strength.

[0048] It should be noted that the average particle size of the flocs is controlled within the range of 150-200 μm, as flocs within this range exhibit better separation characteristics. The larger the average particle size of the flocs, the greater their mass, and the greater the magnetic force they experience under the same magnetic field strength (related to mass and magnetic susceptibility). Therefore, appropriately increasing the magnetic field strength can more effectively control the movement of these larger flocs, allowing them to arrange themselves more orderly on the membrane surface, forming a more stable and highly porosity dynamic filtration layer, thereby maximizing membrane flux while enhancing retention.

[0049] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A magnetically responsive coagulation-ultrafiltration coupled water treatment system, characterized in that, include: A coagulant dosing unit (1) includes at least one reagent tank (11), a precision metering pump (12), and a static mixer (13), which are connected sequentially; a coagulation reaction unit (2) is divided into a rapid mixing zone (21), a gradient flocculation zone (22), and a steady flow zone (23) along the water flow direction, with at least two sets of stirring paddles with different stirring intensities in the gradient flocculation zone (22); and an ultrafiltration unit (3) includes a membrane module (31) and a magnetic response module (32), which are connected sequentially. The membrane fiber surface of the component (31) is loaded with a magnetic composite modified layer, and the magnetic response component (32) is used to generate an adjustable magnetic field in the space around the membrane component (31); the sensing unit includes online sensors (41) respectively disposed at the raw water inlet of the coagulant dosing unit (1), the outlet of the coagulation reaction unit (2) and the outlet of the ultrafiltration unit (3); and the control unit (5), which is communicatively connected to the sensing unit and is used to dynamically adjust the dosing amount of the precision metering pump (12), the rotation speed of the stirring paddle and the magnetic field strength of the magnetic response component (32) according to the monitoring data of the sensing unit.

2. The magnetically responsive coagulation-ultrafiltration coupled water treatment system according to claim 1, characterized in that, The coagulation reaction unit (2) includes a vertically arranged cylindrical cavity; a first baffle and a second baffle are arranged sequentially along its axial direction in the cylindrical cavity to divide the cylindrical cavity from top to bottom into the rapid mixing zone (21), the gradient flocculation zone (22) and the flow stabilization zone (23); both the first baffle and the second baffle are provided with multiple flow holes to guide water flow through each functional zone sequentially.

3. The magnetically responsive coagulation-ultrafiltration coupled water treatment system according to claim 2, characterized in that, The gradient flocculation zone (22) is provided with a first-stage agitator (221), a second-stage agitator (222), and a third-stage agitator (223) from top to bottom; the blade diameters of the first-stage agitator (221), the second-stage agitator (222), and the third-stage agitator (223) increase in a gradient; the gradient flocculation zone (22) is also provided with an adjustable-angle arc-shaped guide plate (224).

4. The magnetically responsive coagulation-ultrafiltration coupled water treatment system according to claim 3, characterized in that, The upper part of the rapid mixing zone (21) is provided with a high-speed three-bladed agitator (211), the top of the gradient flocculation zone (22) is provided with a jet nozzle (225), and the flow stabilization zone (23) is filled with honeycomb packing.

5. The magnetically responsive coagulation-ultrafiltration coupled water treatment system according to claim 1, characterized in that, The ultrafiltration unit (3) includes a cylindrical membrane housing (33), a membrane module (31) disposed within the membrane housing (33), a magnetic response component (32) disposed around the membrane housing (33), and a cleaning component disposed on the membrane housing (33); the membrane module (31) is a vertically suspended hollow fiber membrane module; the magnetic response component (32) includes at least one set of electromagnetic coils; the cleaning component includes an air inlet (311) disposed above the membrane module (31), a backwash water inlet (312) disposed at the bottom of the membrane housing (33), and a chemical cleaning dosing port (313) disposed at the top or side wall of the membrane housing (33).

6. The magnetically responsive coagulation-ultrafiltration coupled water treatment system according to claim 5, characterized in that, The membrane module (31) includes multiple hollow fiber membrane filaments bundled together to form a membrane filament bundle. The upper and lower ends of the membrane filament bundle are sealed by epoxy resin casting to form an upper tube sheet (314) and a lower tube sheet (315). The membrane module (31) is sealed to the top of the membrane shell (33) through the upper tube sheet (314), thereby being vertically suspended inside the membrane shell (33).

7. The magnetically responsive coagulation-ultrafiltration coupled water treatment system according to claim 6, characterized in that, The hollow fiber membrane is made of polyvinylidene fluoride with a magnetic composite modified layer loaded on its surface; the magnetic composite modified layer contains Fe3O4 nanoparticles and quaternized chitosan.

8. The magnetically responsive coagulation-ultrafiltration coupled water treatment system according to claims 1 to 7, characterized in that, It also includes a concentrate return pipeline (6), one end of which is connected to the concentrate outlet of the ultrafiltration unit (3), and the other end is connected to the rapid mixing zone (21) of the coagulation reaction unit (2).

9. A treatment method based on the water treatment system according to any one of claims 1-7, characterized in that, Includes the following steps: Monitoring steps: The water quality parameters of the raw water, the state parameters of the flocs at the outlet of the coagulation reaction unit (2) and the operating parameters of the ultrafiltration unit (3) are monitored in real time by the sensing unit; Dynamic control steps: The control unit (5) calculates and outputs control commands based on the real-time data obtained in the monitoring steps, so as to dynamically adjust the dosage of the coagulant dosing unit (1), adjust the rotation speed combination of the stirring paddle in the gradient flocculation zone (22), and adjust the magnetic field strength generated by the magnetic response component (32); Coagulation reaction steps: The raw water and the added agent are rapidly mixed in the rapid mixing zone (21), and then flow through the gradient flocculation zone (22) and the steady flow zone (23) in sequence to form flocs with target particle size characteristics and separate the supernatant; Magnetic response ultrafiltration step: The supernatant is passed into the ultrafiltration unit (3) and filtered and separated under the action of the magnetic field to obtain product water; Cleaning and maintenance steps: According to the preset cycle of the ultrafiltration unit (3), the cleaning component is triggered to clean the membrane module (31).

10. The processing method according to claim 9, characterized in that, In the coagulation reaction step, by controlling the rotation speed of each stage of the stirring paddle in the gradient flocculation zone (22), the average particle size of the formed flocs is controlled within the range of 150-200 μm; In the magnetic response ultrafiltration step, the magnetic field strength is adjusted according to the average particle size of the flocs; the larger the average particle size of the flocs, the higher the applied magnetic field strength.

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