A water pollution efficient treatment method of an environmental protection special equipment

Abstract

The application discloses a kind of water pollution efficient treatment methods of special equipment for environmental protection, and the present application relates to pollution control technical field, after wastewater pretreatment, into the conductive separation membrane module with piezoelectric catalytic coating on the surface, pulsating fluid generating device applies periodic pressure pulsation to membrane, makes membrane surface produce microelectric field and generates hydroxyl radical, realizes self-cleaning while filtering, recycles high-pressure water supply pump and aeration fan waste heat, coupling low-pressure vacuum environment drives low-temperature low-pressure membrane distillation unit to concentrate concentrated water, realizes quality crystallization in sectional crystallization tank according to salt solubility difference, controller collects transmembrane pressure difference, conductivity and salinity signal, based on time series prediction model dynamic adjustment membrane module pulse frequency and pump pressure, realize the elastic adaptive operation of water quality and quantity fluctuation, relieve membrane pollution and reduce crystallization energy consumption.

Description

Technical Field

[0001] This invention relates to the field of pollution control technology, specifically to a method for efficient water pollution treatment using specialized environmental protection equipment. Background Technology

[0002] With the acceleration of industrialization and increasingly stringent environmental emission standards, the zero-discharge treatment of high-salt, high-chemical oxygen demand organic wastewater has become a key bottleneck restricting the development of industries such as chemical, printing and dyeing, and pharmaceutical. In the field of wastewater treatment, membrane separation technology is widely used in the wastewater pre-concentration stage due to its advantages such as high separation efficiency and small footprint. Evaporation crystallization technology is used to further treat the high-salt concentrate after membrane concentration, ultimately achieving solid-state recovery of salt and recycling of water. The organic combination of the above two types of technologies constitutes the technical basis of the current mainstream zero-discharge process route.

[0003] In existing practical production applications and environmental protection equipment, the treatment of high-salt and high-chemical oxygen demand wastewater usually adopts a combination process of pretreatment, reverse osmosis or forward osmosis membrane concentration, and mechanical steam recompression evaporation crystallization. The specific process is as follows: the wastewater first goes through pretreatment processes such as coagulation sedimentation and filtration to remove large particulate suspended solids and some organic matter.

[0004] The pretreated water then enters the reverse osmosis or forward osmosis membrane concentration unit, where the pressure difference or osmotic pressure difference across the membrane allows water molecules to selectively permeate through the membrane while salts and large organic molecules are retained and concentrated.

[0005] After membrane concentration, the high-salt concentrated water that reaches the osmotic pressure limit enters the mechanical vapor recompression evaporation crystallization system. The compressor performs work on the secondary steam to increase its temperature and pressure, and then uses it as a heat source to heat the concentrated brine in the evaporator, causing water to evaporate and salt to crystallize out, thereby achieving solid-liquid separation and water recovery. The existing technical solution mainly consists of three parts in terms of structure: a pretreatment device, a membrane concentration device, and an evaporation crystallization device. These parts are connected in series, and the material flows unidirectionally in the order of pretreatment, membrane concentration, and evaporation crystallization.

[0006] The aforementioned existing technical solutions have revealed several problems in long-term engineering applications:

[0007] Firstly, high-salt wastewater is usually accompanied by high concentrations of organic pollutants. These organic substances are very easy to aggregate and form a gel layer under the concentration polarization effect on the membrane surface, which leads to the gradual blockage of membrane pores, resulting in a decrease in membrane flux and a continuous increase in transmembrane pressure difference. On-site, the membrane performance can only be maintained by regular chemical cleaning, but chemical cleaning will introduce secondary pollution and cause irreversible damage to the membrane structure.

[0008] Secondly, due to the osmotic pressure limit of membrane concentration, the concentration ratio cannot be further increased. A large amount of high-salt concentrated water still needs to be evaporated and crystallized by consuming electricity through a mechanical steam recompression system, resulting in the power consumption of the evaporation and crystallization unit accounting for a large proportion of the total operating cost of wastewater treatment.

[0009] Third, the structure and control logic of existing integrated environmental protection equipment are mostly configured according to relatively stable design conditions. When faced with the impact load of instantaneous water volume or water quality fluctuations in industrial front-end sewage discharge, they lack dynamic adjustment capabilities, which can easily lead to membrane module overpressure damage or effluent water quality exceeding standards. Therefore, there is an urgent need for an efficient water pollution treatment method for environmental protection equipment that can take into account online control of membrane fouling, low-energy concentration and crystallization, and flexible adaptive adjustment of water quality and quantity. Summary of the Invention

[0010] The technical problem to be solved by this invention is that in the existing zero-discharge treatment process for high-salt, high-chemical-oxygen-demand industrial wastewater, the reverse osmosis or forward osmosis membrane concentration unit suffers from severe membrane fouling, frequent cleaning, and irreversible damage.

[0011] The energy consumption of the subsequent evaporation and crystallization unit accounts for too high a proportion of the total processing cost, making it difficult for enterprises to bear the operating costs.

[0012] Furthermore, integrated environmental protection equipment lacks dynamic adaptive adjustment capabilities when faced with instantaneous fluctuations in the quality and quantity of industrial wastewater, and is prone to system failures or excessive effluent standards.

[0013] To address the aforementioned technical problems, this invention provides a highly efficient water pollution treatment method for environmental protection equipment, comprising the following steps: Wastewater to be treated is sequentially passed through a pretreatment unit and a conductive separation membrane assembly for membrane concentration treatment. Simultaneously, a periodic pressure pulsation is applied to the conductive separation membrane assembly via a pulsating fluid generator. This causes the piezoelectric catalytic coating on the surface of the conductive separation membrane assembly to generate surface charges and induce a micro-electric field when subjected to the periodic pressure pulsation. The micro-electric field drives water molecules adsorbed on the surface of the conductive separation membrane assembly to undergo an oxidation-reduction reaction to generate hydroxyl radicals. These hydroxyl radicals are then used to oxidize and degrade pollutants attached to the surface of the conductive separation membrane assembly in situ, achieving simultaneous self-cleaning of the membrane surface during the filtration process.

[0014] Waste heat generated during the operation of the high-pressure feed water pump and aeration blower is recovered and transferred to a low-pressure environment formed by a vacuum pump and a low-pressure chamber through a heat exchanger array. The low-pressure environment and the waste heat are used to drive a low-temperature and low-pressure membrane distillation unit to further concentrate the high-salt concentrated water after it has been concentrated by the conductive separation membrane assembly to obtain a concentrated liquid.

[0015] The concentrate is transported to a segmented crystallizer, which is provided with a high-temperature zone and a low-temperature zone along the height direction. According to the solubility difference of different salts in the concentrate, the temperature of the high-temperature zone and the low-temperature zone are controlled respectively so that the corresponding salts reach the supersaturation state in sequence and precipitate out, thereby realizing fractional crystallization.

[0016] The controller collects transmembrane pressure difference signals, influent conductivity signals, and influent salinity signals in real time. The collected signals are then input into a pre-trained time series prediction model to obtain predicted values ​​of transmembrane pressure difference and influent salinity within a preset time window. These predicted values ​​are compared with preset benchmark reference values. When the deviation between the two values ​​exceeds a preset deviation threshold, the micro-electric field pulse frequency adjustment of the pulsating fluid generator and the pump pressure adjustment of the high-pressure feed pump are calculated based on the deviation. The operating parameters of the pulsating fluid generator and the high-pressure feed pump are adjusted accordingly to achieve an elastic adaptive response of the equipment to fluctuations in water quality and quantity.

[0017] Compared with the prior art, the beneficial effects of the present invention by adopting the above technical solution are as follows:

[0018] 1. This invention achieves a dynamic anti-fouling effect of filtering and self-cleaning simultaneously by coating a piezoelectric catalytic function onto the surface of a conductive separation membrane module. This is achieved by utilizing the fluid pulsation that naturally occurs during equipment operation to generate hydroxyl radicals on the membrane surface in situ. This eliminates the need for additional chemical cleaning agents, fundamentally reducing the frequency of chemical cleaning, extending the service life of the membrane module, and lowering membrane replacement costs.

[0019] 2. This invention recovers the low-grade waste heat generated by the operation of the high-pressure feed water pump and aeration blower at the front end of the equipment, and drives the low-temperature and low-pressure membrane distillation unit to concentrate high-salt concentrated water by coupling a low-pressure vacuum environment. It abandons the traditional high-energy-consuming evaporation and crystallization method that relies on the compressor, and significantly reduces the power consumption of the system while achieving a considerable concentration effect.

[0020] 3. This invention overcomes the technical bias of existing technologies where membrane fouling control and crystallization energy consumption optimization are independent and isolated from each other. It innovatively links the micro-electric field pulse frequency adjustment of piezoelectric catalytic self-cleaning with the operating status of the waste heat-driven membrane distillation concentration unit through the same LSTM prediction model, so that the self-cleaning intensity of the membrane module can be adjusted synchronously according to the load prediction results of the concentration unit. While suppressing membrane fouling, it also reduces the energy consumption of the crystallization unit, achieving a linkage and synergistic effect that cannot be achieved by adjusting a single module. It avoids the problems of membrane module overpressure damage or effluent water quality exceeding standards caused by the lag of traditional control methods due to load changes, and realizes stable operation of the equipment without human intervention. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the overall system architecture of the environmental protection equipment in an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the waste heat recovery-driven membrane distillation and fractional crystallization process in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the time series prediction adaptive control logic flow in an embodiment of the present invention. Detailed Implementation

[0024] The following is in conjunction with the appendix Figure 1-3 The specific embodiments of the present invention will be further described below. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0025] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0026] The environmental protection equipment of this invention is composed of three major functional modules forming a closed-loop technology: a conductive separation membrane in-situ self-cleaning module, a waste heat-driven low-pressure membrane distillation and fractionation crystallization module, and a digital twin cross-unit dynamic adaptive control module. From left to right, the equipment includes a raw water inlet, a pretreatment unit containing a screen and coagulation sedimentation device, a high-pressure feed water pump, an aeration blower, a conductive separation membrane assembly with an embedded piezoelectric catalytic coating, a pulsating fluid generator connected to the conductive separation membrane assembly for generating periodic pressure pulsations, a micro heat exchanger array connected to the heat dissipation shells of the high-pressure feed water pump and the aeration blower for recovering the low-grade waste heat generated during their operation, and a vacuum... The system includes a pump and low-pressure chamber, a low-temperature and low-pressure membrane distillation unit, a segmented crystallizer with internal temperature gradient zones, a centrifugal separation and salt collection device, a controller connected to sensors and actuators in the pretreatment unit via signal lines, and a sensor group distributed and installed on the inlet and outlet of the conductive separation membrane module and on the pipelines of the membrane distillation unit. The sensor group includes a transmembrane differential pressure sensor, a conductivity sensor, a temperature sensor, and a flow sensor. The modules are connected sequentially via pipelines and signal lines. The material flow follows the sequence of pretreatment, membrane self-cleaning separation, waste heat recovery, membrane distillation concentration, and segmented crystallization. The control signal forms a two-way feedback closed loop between the controller and each sensor and actuator.

[0027] I. Conductive Separation Membrane In-situ Self-Cleaning Module

[0028] The conductive separation membrane assembly of the present invention uses commercial polyvinylidene fluoride or polyamide membrane as the base membrane layer, and loads a conductive intermediate layer on the surface of the base membrane layer through electrospinning or interfacial polymerization process. The conductive intermediate layer is a carbon nanotube network layer, which has both conductive pathway and mechanical support function.

[0029] A piezoelectric catalytic outer layer is further loaded on the surface of the conductive intermediate layer. The piezoelectric catalytic outer layer is composed of barium titanate nanoparticles uniformly dispersed on the surface of the conductive intermediate layer, forming piezoelectric active sites, so that the membrane itself has both separation function and piezoelectric catalytic function.

[0030] During operation, the pulsating fluid generator continuously applies periodic hydraulic pulses to the conductive separation membrane assembly. The direction of the pulsating pressure is indicated by arrows in the figure. This pulsating pressure acts on the outer layer of the piezoelectric catalyst, causing it to undergo periodic deformation. This induces a micro-electric field on the membrane surface, which is represented by electric field lines in the figure. The micro-electric field drives the water molecules adsorbed on the membrane surface to undergo redox reactions, generating hydroxyl radicals. These radicals are represented by radial symbols around the contaminants attached to the membrane surface. Under the strong oxidizing effect of the hydroxyl radicals, the contaminants in the organic gel layer attached to the membrane surface are oxidized and degraded in situ into small molecules, which are then removed from the membrane surface with the water flow. This achieves dynamic self-cleaning of the membrane surface during continuous filtration, maintaining stable membrane flux without relying on chemical cleaning agents.

[0031] The working mechanism of this module can be characterized by the following relationship between piezoelectric effect output voltage and deformation:

[0032] ;

[0033] In the formula, This represents the open-circuit voltage induced on the membrane surface by the piezoelectric catalytic outer layer under stress.

[0034] The piezoelectric voltage constant along the polarization direction represents the intrinsic parameter of the piezoelectric catalytic material, which is determined by the composition and crystal structure of the selected piezoelectric catalytic material.

[0035] It represents the instantaneous mechanical stress exerted by the pulsating fluid on the membrane surface, which is determined by the amplitude of the pulsating pressure output by the pulsating fluid generator;

[0036] This indicates the effective thickness of the piezoelectric catalytic outer layer, when the open-circuit voltage is... When the threshold voltage required for the catalytic reaction is reached, the local micro-electric field on the membrane surface can drive the interfacial water molecules to continuously undergo oxidation reaction, generating hydroxyl radicals to degrade attached pollutants, achieving a dynamic antifouling effect of filtering and self-cleaning simultaneously. By rationally selecting piezoelectric catalytic materials and coating thickness, the open circuit voltage can be continuously reached and maintained above the catalytic reaction threshold within the pulsating pressure range during normal equipment operation, ensuring the continuity of the self-cleaning effect.

[0037] II. Waste Heat Driven Low-Pressure Membrane Distillation and Separate Crystallization Module

[0038] This invention abandons the traditional high-energy-consuming mechanical vapor recompression evaporation crystallization process and proposes a technical solution for the recycling of kinetic and thermal energy: extracting low-grade waste heat generated during the operation of the high-pressure feed water pump and aeration blower at the front end of the equipment, with a temperature range of 40 to 60 degrees Celsius, recovering it through a micro heat exchanger array, and coupling the recovered heat to a low-pressure vacuum environment created by a vacuum pump and a low-pressure chamber, directly driving the low-temperature low-pressure membrane distillation unit to further concentrate the high-salt concentrated water after it has been concentrated by the conductive separation membrane module.

[0039] The process flow, from top to bottom, is as follows: waste heat collection from the high-pressure feed water pump and aeration blower, heat transfer from the heat exchanger array, establishment of the low-pressure vacuum chamber, transmembrane mass transfer of steam in the membrane distillation unit, the concentrated liquid entering the segmented crystallizer, sodium sulfate crystallization and sodium chloride crystallization are achieved sequentially according to the temperature gradient, solid salts are collected by centrifugation, and condensate is recycled.

[0040] In a membrane distillation unit, the transmembrane mass transfer flux of water vapor can be characterized by the following relationship:

[0041] ;

[0042] In the formula, This represents the transmembrane mass transfer flux of water vapor in a membrane distillation unit;

[0043] The mass transfer coefficient of a membrane distillation unit is determined by structural parameters such as membrane porosity, pore size, and thickness.

[0044] This indicates the partial pressure of water vapor at the membrane thermal side, i.e., the feed side interface, which is determined by the temperature provided by waste heat recovery.

[0045] The partial pressure of water vapor at the interface between the cold and permeate sides of the membrane is determined by the low-pressure environment maintained by the low-pressure vacuum chamber. As can be seen from this formula, without consuming a large amount of additional electrical energy, sufficient transmembrane vapor pressure difference can be obtained by relying solely on residual heat to increase the partial pressure of water vapor on the feed side and combining it with vacuum to reduce the partial pressure of water vapor on the permeate side, thereby achieving low-energy concentration.

[0046] The segmented crystallizer is divided into high-temperature and low-temperature zones along its height. The diagram shows the temperature gradient zones marked next to the crystallizer corresponding to each step. The high-temperature zone corresponds to the temperature range where the inflection point of the sodium sulfate solubility curve is located, and the low-temperature zone corresponds to the temperature range for saturated crystallization of sodium chloride. The segmented crystallization temperature is set based on the solubility difference between sodium sulfate and sodium chloride. The controller dynamically adjusts the crystallizer zone temperature according to the following solubility difference criterion based on the real-time conductivity and temperature feedback of the concentrate:

[0047] ;

[0048] In the formula, Indicates temperature The difference in solubility between sodium sulfate and sodium chloride under certain conditions;

[0049] Indicates temperature Solubility of sodium sulfate;

[0050] Indicates temperature The controller continuously tracks the solubility of sodium chloride. By analyzing the changing trends, the target temperature setpoints for each crystallization zone are determined, so that sodium sulfate preferentially reaches supersaturation and precipitates in the high-temperature zone, while sodium chloride subsequently reaches supersaturation and precipitates in the low-temperature zone. The precipitated solid salts are collected separately by centrifugation and salt collection devices, while the condensate is recycled. Thus, the segmented crystallization and fractional resource utilization of the two salts are achieved within the same equipment terminal.

[0051] III. Digital Twin Cross-Unit Dynamic Adaptive Control Module

[0052] The built-in controller of this invention collects multi-source sensor data such as transmembrane pressure difference, influent salinity and conductivity in real time, constructs a virtual operation image of the equipment, and predicts future short-term load fluctuations based on a long short-term memory network prediction model. Then, it dynamically adjusts the micro-electric field pulse frequency of the membrane module and the front-end pump pressure to achieve adaptive operation of the equipment under fluctuating water quality and quantity conditions.

[0053] The logical flow of the control algorithm includes the following steps: multi-source sensor data acquisition, corresponding to sensor groups such as transmembrane pressure difference, conductivity, salinity, and flow rate; data preprocessing and normalization; time series prediction, outputting the predicted load value for the future period; impact load determination, dividing into two branches based on the comparison result of the predicted value and the preset threshold: entering elastic regulation and maintaining normal operation; elastic regulation parameter calculation, calculating the micro-electric field pulse frequency and pump pressure adjustment amount; actuator action, driving the pulsating fluid generator and high-pressure feed water pump to act; normal operation maintenance, maintaining the current operating parameters and updating the operating status feedback, and feeding back the execution results to form a closed loop.

[0054] Specifically, the controller first collects transmembrane pressure difference signals, influent conductivity signals, influent salinity signals, and pipeline flow signals in real time during equipment operation. It then normalizes the collected raw data to eliminate the influence of numerical differences between sensor data of different dimensions, obtaining standardized time-series input data. Subsequently, the controller inputs the standardized time-series data into a pre-trained long short-term memory network prediction model to obtain predicted values ​​of transmembrane pressure difference and influent salinity within a preset time window. This prediction process can be characterized by the following relationship:

[0055] ;

[0056] In the formula, This represents the model's prediction of the transmembrane pressure difference or influent salinity at the next time step.

[0057] Represents the mapping function of a trained and converged Long Short-Term Memory network;

[0058] Indicates from From this moment to the present A historical normalized sensor data sequence at any given moment;

[0059] This indicates the length of the historical time window on which the prediction model relies.

[0060] The controller further modifies the predicted values The system compares the load with a pre-set threshold to determine whether the equipment is about to face a water quality and quantity impact load. The determination criteria can be expressed as follows:

[0061] ;

[0062] In the formula, This represents the baseline reference value for transmembrane pressure difference or influent salinity under normal and stable operating conditions of the equipment;

[0063] This represents a pre-set allowable deviation threshold. If the above inequality holds, it is determined that an impact load is about to occur.

[0064] Otherwise, the operating condition is determined to be normal, and the controller maintains the current micro-electric field pulse frequency and pump pressure and other operating parameters unchanged.

[0065] When an impending impact load is detected, the controller dynamically calculates the adjustment amount of the micro-electric field pulse frequency of the membrane module based on the predicted deviation amplitude. The calculation method can be expressed as follows:

[0066] ;

[0067] In the formula, This represents the adjustment increment of the micro-electric field pulse frequency;

[0068] This represents a pre-set proportional control coefficient used to map the prediction deviation into a pulse frequency adjustment. The controller simultaneously calculates the pressure adjustment increment of the high-pressure feed water pump according to a similar proportional relationship; this proportional coefficient is denoted as... Meaning and Similarly, only the objects being regulated are different. The controller sends the calculated regulation amount to the pulsating fluid generator and the high-pressure feed water pump, respectively increasing the pulse frequency of the micro-electric field on the surface of the membrane module to enhance the in-situ self-cleaning effect, and adjusting the inlet water pressure to smooth out the instantaneous pressure impact on the membrane module caused by the shock load. Whether it is flexibly regulated or maintains normal operation, the controller continuously feeds back the actual operating status data of the equipment after execution to the data acquisition link, forming a complete closed-loop control loop of acquisition, prediction, judgment, regulation, and feedback, so as to realize the continuous dynamic adaptive operation of the equipment.

[0069] IV. Examples

[0070] Example 1: For a high-salt, high-chemical oxygen demand (COD) wastewater from a dyeing and printing industry, with a COD concentration of approximately 4,000 to 6,000 mg / L and a salt content of approximately 6% to 10%, the wastewater is pretreated by a pretreatment unit to remove large particulate suspended solids and some organic matter. Then, it is pressurized by a high-pressure feed water pump and enters a conductive separation membrane module for membrane concentration. At the same time, a pulsating fluid generator continuously applies periodic pressure pulsations to the membrane module, keeping the membrane surface in a state of simultaneous filtration and self-cleaning. Compared with conventional membrane modules without piezoelectric catalytic coatings, under the same influent water quality and operating conditions, the chemical cleaning cycle of the membrane module in this example is extended from 15 days to more than 45 days, and the membrane flux decay rate is reduced from 3% per day to less than 1% per day.

[0071] Compared to the traditional mechanical steam recompression process, the power consumption per ton of water treated in this embodiment is reduced from more than 8 kWh to less than 3 kWh.

[0072] Example 2: Based on Example 1, the piezoelectric catalytic outer layer is replaced with a composite coating of doped lead zirconium titanate and graphene oxide, or with a composite coating of polyvinylidene fluoride-trifluoroethylene copolymer and metal oxide nanoparticles. The remaining structure and process flow are consistent with Example 1. The above-mentioned alternative materials also have piezoelectric effect and catalytic activity. They can generate a micro-electric field on the membrane surface under the action of fluid pulsation and catalyze the generation of active free radicals, achieving an in-situ self-cleaning effect on the membrane surface comparable to that of Example 1. They can be used as a supplementary implementation method for piezoelectric catalytic coating materials.

[0073] Example 3: Based on Example 1, a solar thermal collector module or low-temperature waste heat generated by other processes in the industrial park is integrated into the equipment as a supplementary heat source. The supplementary heat source is fed into the heat source side of the low-temperature and low-pressure membrane distillation unit through a heat exchanger array and the waste heat generated by the high-pressure feed water pump and aeration fan. Under the condition that the waste heat supply of the front-end equipment is insufficient, the transmembrane vapor pressure difference driving force required by the membrane distillation unit is maintained. The rest of the structure and process flow are consistent with Example 1, which can be used as a supplementary implementation method for waste heat acquisition.

[0074] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for efficient water pollution treatment using specialized environmental protection equipment, characterized in that, include: The wastewater to be treated is sequentially passed through a pretreatment unit and a conductive separation membrane assembly for membrane concentration. Simultaneously, a periodic pressure pulsation is applied to the conductive separation membrane assembly through a pulsating fluid generator. When the piezoelectric catalytic coating on the surface of the conductive separation membrane assembly is subjected to the periodic pressure pulsation, a surface charge is generated and a micro electric field is induced. The micro electric field drives the water molecules adsorbed on the surface of the conductive separation membrane assembly to undergo an oxidation-reduction reaction to generate hydroxyl radicals. The hydroxyl radicals are used to oxidize and degrade pollutants attached to the surface of the conductive separation membrane assembly in situ, thereby achieving simultaneous self-cleaning of the membrane surface during the filtration process. Waste heat generated during the operation of the high-pressure feed water pump and aeration blower is recovered and transferred to a low-pressure environment formed by a vacuum pump and a low-pressure chamber through a heat exchanger array. The low-pressure environment and the waste heat are used to drive a low-temperature and low-pressure membrane distillation unit to further concentrate the high-salt concentrated water after it has been concentrated by the conductive separation membrane assembly to obtain a concentrated liquid. The concentrate is transported to a segmented crystallizer, which is provided with a high-temperature zone and a low-temperature zone along the height direction. Based on the difference in solubility between the first salt and the second salt in the concentrate, the temperature of the high-temperature zone is controlled to make the first salt reach a supersaturated state and precipitate, and the temperature of the low-temperature zone is controlled to make the second salt reach a supersaturated state and precipitate, thereby achieving fractional crystallization. The controller collects transmembrane pressure difference signals, influent conductivity signals, and influent salinity signals in real time. The collected signals are input into a pre-trained time series prediction model to obtain predicted values ​​of transmembrane pressure difference and influent salinity within a preset time window. The predicted values ​​are compared with preset benchmark reference values. When the deviation between the predicted values ​​and the benchmark reference values ​​is greater than a preset deviation threshold, the micro-electric field pulse frequency adjustment amount of the pulsating fluid generator and the pump pressure adjustment amount of the high-pressure feed pump are calculated based on the deviation. The operating parameters of the pulsating fluid generator and the high-pressure feed pump are adjusted according to the micro-electric field pulse frequency adjustment amount and the pump pressure adjustment amount, respectively.

2. The method according to claim 1, characterized in that, The conductive separation membrane assembly includes a base membrane layer, a conductive intermediate layer disposed on the surface of the base membrane layer, and a piezoelectric catalytic outer layer disposed on the surface of the conductive intermediate layer. The base membrane layer is made of either polyvinylidene fluoride or polyamide. The conductive intermediate layer is a carbon nanotube network layer. The piezoelectric catalytic outer layer is a composite coating doped with barium titanate nanoparticles. The barium titanate nanoparticles are dispersed on the surface of the conductive intermediate layer.

3. The method according to claim 1, characterized in that, The piezoelectric catalytic coating is selected from one of the following: a composite coating doped with barium titanate nanoparticles, a composite coating doped with lead zirconium titanate and graphene oxide, and a composite coating of polyvinylidene fluoride-trifluoroethylene copolymer and zinc oxide nanoparticles.

4. The method according to claim 1, characterized in that, The high-pressure feed pump and the aeration blower are each equipped with a heat dissipation shell. The heat exchanger array is connected to the heat dissipation shells of the high-pressure feed pump and the aeration blower, respectively, to recover the waste heat generated during the operation of the high-pressure feed pump and the aeration blower, which has a temperature range of 40 to 60 degrees Celsius. The water vapor partial pressure at the feed side interface of the low-temperature and low-pressure membrane distillation unit is increased by the waste heat, and the water vapor partial pressure at the permeate side interface of the low-temperature and low-pressure membrane distillation unit is decreased by the low-pressure environment. The water vapor transmembrane mass transfer is driven by the water vapor partial pressure difference between the feed side interface and the permeate side interface.

5. The method according to claim 1, characterized in that, The first salt is sodium sulfate, and the second salt is sodium chloride. The temperature of the high-temperature zone corresponds to the temperature range where the inflection point of the sodium sulfate solubility curve is located, and the temperature of the low-temperature zone corresponds to the temperature range where sodium chloride is saturated and crystallized. The controller calculates the difference in solubility between sodium sulfate and sodium chloride at the same temperature based on the conductivity and temperature feedback of the concentrate, and determines the temperature setpoints of the high-temperature zone and the low-temperature zone based on the changing trend of the solubility difference.

6. The method according to claim 1, characterized in that, The time series prediction model is a long short-term memory network model. The controller inputs the normalized sensor data sequence from the historical time to the current time into the long short-term memory network model to obtain the predicted values ​​of transmembrane pressure difference and influent salinity at the next time step. When the deviation between the predicted value and the reference value is not greater than the deviation threshold, the controller maintains the current operating parameters of the pulsating fluid generator and the high-pressure feedwater pump. The controller feeds back the adjusted actual operating status data of the pulsating fluid generator and the high-pressure feedwater pump to the data acquisition stage of the time series prediction model, forming a closed-loop control.

7. A special environmental protection equipment, characterized in that, The system includes a pretreatment unit, a high-pressure feed water pump connected to the pretreatment unit via pipeline, an aeration blower, a conductive separation membrane assembly connected to the high-pressure feed water pump via pipeline, a pulsating fluid generator mechanically connected to the conductive separation membrane assembly, a heat exchanger array connected to the high-pressure feed water pump and the aeration blower respectively, a vacuum pump and a low-pressure chamber connected to the heat exchanger array, a low-temperature and low-pressure membrane distillation unit connected to the low-pressure chamber and the conductive separation membrane assembly, a segmented crystallizer connected to the low-temperature and low-pressure membrane distillation unit, a centrifugal separation and salt collection device connected to the segmented crystallizer, and a controller electrically connected to the high-pressure feed water pump, the pulsating fluid generator, the conductive separation membrane assembly, and the low-temperature and low-pressure membrane distillation unit respectively. The conductive separation membrane assembly has a piezoelectric catalytic coating on its surface. The pulsating fluid generator is used to apply periodic pressure pulsations to the conductive separation membrane assembly. The heat exchanger array is used to recover the waste heat generated during the operation of the high-pressure feed water pump and the aeration blower and transfer the waste heat to the low-pressure chamber. The segmented crystallizer is provided with a high-temperature zone and a low-temperature zone along the height direction. The controller is connected to a sensor group, which includes a transmembrane differential pressure sensor, a conductivity sensor, a temperature sensor, and a flow sensor respectively installed at the inlet and outlet of the conductive separation membrane assembly and on the pipeline of the low-temperature and low-pressure membrane distillation unit.

8. The environmental protection equipment according to claim 7, characterized in that, The conductive separation membrane assembly includes a base membrane layer, a conductive intermediate layer disposed on the surface of the base membrane layer, and a piezoelectric catalytic coating disposed on the surface of the conductive intermediate layer. The base membrane layer is made of either polyvinylidene fluoride or polyamide, and the conductive intermediate layer is a carbon nanotube network layer.

9. The environmental protection equipment according to claim 7, characterized in that, The controller is used to dynamically adjust the micro-electric field pulse frequency of the pulsating fluid generator and the pump pressure of the high-pressure feed pump based on the transmembrane pressure difference signal, conductivity signal and flow signal collected by the sensor group, and to receive the adjusted operating status data of the pulsating fluid generator and the high-pressure feed pump to form a feedback closed loop.

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