High-salinity wastewater separation and reuse method based on nano ceramic membrane filter aid material

Abstract

The invention discloses a method for separating and recycling high-salinity wastewater based on a nano ceramic membrane filter aid material, which comprises the following steps: pretreating raw high-salinity wastewater to remove suspended solids, hardness ions and part of organic matters; adding a nano ceramic membrane filter aid material subjected to surface hydrophilic modification into the pretreatment liquid to form a dynamic filter aid layer; filtering and separating through a ceramic ultrafiltration membrane assembly to obtain a permeate and a concentrated solution; the permeate liquid is used as reuse water for direct resource utilization, the concentrated liquid is further concentrated and subjected to evaporative crystallization treatment, inorganic salt crystallization products are recycled, and resource utilization is achieved. According to the invention, the dynamic layer of the nano ceramic filter aid material is utilized to enhance the anti-pollution capability and improve the membrane flux stability and the system recovery rate; and hydrophilic modification and regular cleaning are combined to realize long-term stability of membrane performance. The method is suitable for high-salinity wastewater treatment, the effluent quality meets the industrial recycling requirement, the process is efficient and resistant to corrosion, and near-zero liquid discharge of high-salinity wastewater and salt resource recovery are achieved.

Description

Technical Field

[0001] This invention belongs to the field of high-salinity wastewater treatment and resource utilization technology, specifically relating to a method for separating and reusing high-salinity wastewater based on nano-ceramic membrane filter aid materials. Background Technology

[0002] High-salinity wastewater mainly originates from coal chemical, petrochemical, pharmaceutical, pesticide, metallurgical, electroplating, desulfurization and denitrification, photovoltaic / lithium battery production, seawater desalination concentrate, and various other high-salinity industrial wastewaters. Its total dissolved solids (TDS) typically exceeds 10,000 mg / L, sometimes reaching hundreds of thousands of mg / L, and is often accompanied by complex pollutants such as high COD, high hardness, high silica, and high fluoride. Traditional treatment methods (such as multi-effect evaporation, mechanical vapor recompression (MVR), and freeze crystallization) can achieve a certain degree of concentration and crystallization, but they generally suffer from high energy consumption, large equipment investment, easy scaling and clogging, and high operation and maintenance costs. Especially in the initial concentration stage, traditional reverse osmosis (RO) membranes, due to their poor tolerance, weak anti-fouling ability, and insufficient adaptability to high-hardness / high-silica wastewater, are prone to rapid degradation, resulting in low system recovery rates, frequent cleaning or replacement of membrane modules, and difficulty in achieving cost-effective near-zero liquid discharge.

[0003] In recent years, ceramic membrane technology has gained attention in the field of high-salinity wastewater treatment due to its excellent resistance to acids and alkalis, high temperatures, organic solvents, oxidation, microbial fouling, and high mechanical strength. Compared with organic membranes, ceramic membranes have a longer service life (up to 10 years or more) and stronger chemical cleaning and recovery capabilities. However, single ceramic ultrafiltration / microfiltration membranes have limited retention rates for small-molecule salts and some organic matter in high-salinity wastewater, and their flux is still easily affected by fouling when used directly for deep concentration. To further improve the antifouling performance and separation efficiency of ceramic membranes in high-salinity wastewater, some technologies have attempted to introduce filter aids (such as diatomaceous earth, activated carbon powder, polymer flocculants, etc.) to form a dynamic membrane layer. However, traditional filter aids have large particle sizes, small specific surface areas, and are prone to detachment, and are difficult to match well with ceramic membranes, resulting in unsatisfactory antifouling effects and membrane flux stability. At the same time, in existing multi-stage membrane concentration + evaporation crystallization processes, the bottleneck problem in the front-end concentration stage has not been fundamentally solved, leading to high overall energy consumption and operating costs.

[0004] Therefore, there is an urgent need to develop a new, efficient, and pollution-resistant membrane material and process that can operate stably for a long time in high-salt, high-corrosion, and high-pollution environments, improve system recovery rate, achieve effective separation and resource utilization of salt and water, and significantly reduce energy consumption and maintenance costs, thereby promoting the engineering application of near-zero liquid discharge technology for high-salt wastewater. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects in existing high-salt wastewater treatment technologies and provide a method for separating and reusing high-salt wastewater based on nano-ceramic membrane filter aid materials. This method addresses the problems of easy fouling, rapid flux decline, low recovery rate, and poor operational stability of traditional organic membranes and single ceramic membranes in the treatment of complex wastewater with high salt, high hardness, high silica, and high pollution. At the same time, it solves the problems of prominent bottlenecks in the front-end concentration stage of multi-stage membrane concentration + evaporation crystallization processes, high overall energy consumption, easy scaling of equipment, and high operation and maintenance costs.

[0006] Specifically, this invention aims to introduce surface-modified hydrophilic nano-ceramic membrane filter aids to form a highly efficient and stable dynamic filter aid layer, which is coupled with ceramic ultrafiltration membrane modules to significantly enhance the antifouling ability of the membrane separation process, stabilize the membrane flux over a long period, and greatly improve the system recovery rate. Furthermore, it effectively reduces the subsequent evaporation and crystallization load in the front-end concentration stage, thereby significantly reducing energy consumption and operating costs. This enables deep separation, efficient reuse, and inorganic salt resource recovery of high-salinity wastewater, ultimately achieving the goal of near-zero or zero liquid discharge in an economical, efficient, and environmentally friendly manner, and promoting the engineering application and industrial upgrading of high-salinity wastewater treatment technology.

[0007] To achieve the above objectives, the present invention provides a method for separating and reusing high-salt wastewater based on nano-ceramic membrane filter aid materials, the method comprising:

[0008] A high-salinity wastewater raw water is provided, and the high-salinity wastewater raw water is pretreated to remove suspended solids, hardness ions and some organic matter to obtain a pretreated liquid.

[0009] Nano-ceramic membrane filter aid material is added to the pretreatment liquid to form a dynamic filter aid layer;

[0010] The liquid forming the dynamic filter aid layer is filtered and separated through a nano-ceramic membrane module to obtain permeate and concentrate;

[0011] The permeate is used as recycled water for resource utilization, and the concentrate is further concentrated and evaporated for crystallization to achieve the separation and reuse of high-salt wastewater.

[0012] Optionally, the step of pretreating the high-salinity wastewater raw water includes:

[0013] The treatment process involves coagulation sedimentation, chemical softening, and precision filtration in sequence.

[0014] The chemical softening process employs either the lime-soda ash method or the sodium hydroxide-sodium carbonate method to reduce the mass concentration of calcium and magnesium ions to below 50 mg / L.

[0015] The pH of the pretreated solution was controlled at 7.0-9.0 and the turbidity was less than 5 NTU.

[0016] Optionally, the nano-ceramic membrane filter aid material is an alumina-based, zirconium oxide-based, silicon carbide-based, or titanium-based nanoparticle, with an average particle size ranging from 10 to 100 nm and a specific surface area greater than [missing information]. ;

[0017] The nano-ceramic membrane filter aid material undergoes surface hydrophilic modification treatment before use. The modification methods include hydroxylation treatment, silane coupling agent treatment, or grafting with polyethylene glycol. After modification, the water contact angle is less than 30°.

[0018] Optionally, the step of adding nano-ceramic membrane filter aid material to the pretreatment liquid includes:

[0019] The dosage is 0.05-0.5 g / L based on the volume of the pretreated liquid.

[0020] The nano-ceramic particles are added under stirring conditions at a stirring speed of 100-300 rpm. After addition, stirring is continued for 10-40 minutes to form the dynamic filter aid layer on the surface of the nano-ceramic membrane module.

[0021] Optionally, the nano-ceramic membrane module is a tubular, multi-channel planar, or honeycomb ceramic ultrafiltration membrane with a pore size range of 5-50 nm, an operating pressure of 0.1-1.0 MPa, and an operating temperature of 20-90 °C.

[0022] Optionally, in the step of filtration and separation using a nano-ceramic membrane module, the membrane flux is controlled at 50-150 L / m³. The system's recovery rate reaches 70-90%;

[0023] The filtration process employs a cross-flow filtration method, and periodically performs pulse air washing or backwashing to regenerate the dynamic filter aid layer, with a cleaning cycle of 4-24 hours.

[0024] Optionally, the step of further concentrating and evaporating the concentrate includes:

[0025] First, high-pressure nanofiltration or reverse osmosis is used to further concentrate the concentrate so that the TDS reaches 120,000-200,000 mg / L;

[0026] The sodium chloride, sodium sulfate, or other inorganic salt crystals are then recovered by mechanical vapor recompression (MVR) evaporation, multi-effect evaporation, or freeze crystallization.

[0027] Optionally, the method further includes a chemical cleaning step for the nano-ceramic membrane module, wherein the cleaning solution is selected from 0.5-2wt% sodium hydroxide solution, 0.5-2wt% nitric acid solution or citric acid solution, the cleaning temperature is 40-70℃, the cleaning time is 30-120 minutes, and the membrane flux recovery rate after cleaning is not less than 95%.

[0028] Optionally, the cross-flow velocity of the nano-ceramic membrane module is 2-6 m / s, and the thickness of the dynamic filter aid layer is controlled at 5-30 μm.

[0029] Optionally, the raw high-salinity wastewater has a TDS ≥ 10000 mg / L and a COD of 200-2000 mg / L;

[0030] After treatment by the method described above, the permeate has a TDS of less than 500 mg / L and a COD of less than 50 mg / L, and can be directly reused as industrial circulating cooling water or boiler feedwater; the concentrate can be crystallized to obtain sodium chloride, sodium sulfate or other inorganic salt crystal products, realizing the resource utilization of inorganic salts.

[0031] Compared with existing technologies, this method effectively solves the problems of rapid fouling, severe flux decline, and low recovery rates in high-salt wastewater treatment caused by traditional organic membranes and single ceramic membranes being susceptible to high hardness, high silica, and high fouling due to these factors. The dynamic filter aid layer significantly enhances the membrane surface's antifouling ability, improves membrane flux stability and long-term operational reliability. Combined with hydrophilic modification and periodic pulsed air washing / backwashing regeneration measures, the membrane performance remains highly efficient over the long term, with a high flux recovery rate after chemical cleaning. This method can be implemented even in the front-end concentration stage. The high system recovery rate significantly reduces the processing load and energy consumption of subsequent evaporation and crystallization stages, overcoming the shortcomings of traditional multi-stage membrane concentration + evaporation processes, such as prominent bottlenecks in the initial concentration stage, high overall energy consumption, easy scaling of equipment, and high operation and maintenance costs. It is suitable for various complex high-salinity wastewaters, and the effluent quality is stable and meets the requirements for industrial reuse. After crystallization, the concentrate can efficiently recover inorganic salt products such as sodium chloride and sodium sulfate, realizing the effective separation and resource utilization of salt and water. This greatly reduces the economic cost and environmental impact of high-salinity wastewater treatment, promotes the engineering application of near-zero liquid discharge technology, and has significant environmental benefits, economic benefits, and technological advantages. Attached Figure Description

[0032] Figure 1 Flowchart of the high-salt wastewater separation and reuse method provided by the present invention using nano-ceramic membrane filter aid material;

[0033] Figure 2 A flowchart illustrating the method for further concentration and evaporation crystallization of the concentrate provided by the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this application, unless otherwise stated, "multiple" means two or more.

[0036] To more clearly illustrate the technical solution of the present invention, the present invention will be described in detail below with reference to specific embodiments, but it should not be construed as a limitation on the scope of protection of the present invention.

[0037] To achieve the above objectives, such as Figure 1 As shown, this embodiment provides a typical implementation of a high-salt wastewater separation and reuse method based on nano-ceramic membrane filter aid materials. Through the effective coupling of the dynamic filter aid layer formed by the nano-ceramic filter aid materials with the ceramic membrane module, the anti-fouling performance and operational stability of the membrane separation are significantly improved. It is suitable for the treatment of high-salt wastewater generated by coal chemical industry, petrochemical industry, etc., and realizes efficient water reuse and resource recovery of salt.

[0038] Step S01: Provide high-salinity wastewater raw water, and pretreat the high-salinity wastewater raw water to remove suspended solids, hardness ions and some organic matter to obtain pretreated liquid.

[0039] High-salinity wastewater from a coal chemical plant was used as the treatment target. This wastewater contained high concentrations of suspended solids, calcium and magnesium hardness ions, and a certain amount of organic pollutants. First, coagulation and sedimentation were initiated by adding polyaluminum chloride and polyacrylamide, causing most of the suspended solids and colloids to quickly flocculate and settle. Subsequently, the supernatant underwent chemical softening treatment by sequentially adding sodium hydroxide and sodium carbonate, converting calcium ions into calcium carbonate and magnesium ions into magnesium hydroxide precipitates. Hardness components were then removed through secondary sedimentation. Finally, a 5μm precision filter was used to further remove residual fine particles, resulting in a pretreated solution with low turbidity and a suitable pH value, providing stable feed water conditions for subsequent membrane separation.

[0040] Step S02: Add nano-ceramic membrane filter aid material to the pretreatment liquid to form a dynamic filter aid layer.

[0041] Alumina-based nanoceramic nanoparticles with an average particle size of approximately 30 nm and a high specific surface area were selected as the nanoceramic membrane filter aid material. Their surfaces were pre-treated with hydroxylation for hydrophilic modification to improve dispersibility and adhesion in water. Based on the pretreatment liquid volume, these nanoparticles were slowly added at a dosage of 0.2 g / L while mechanical stirring was initiated and maintained at approximately 200 rpm for about 25 minutes. During this period, the nanoparticles gradually migrated and deposited on the membrane surface, self-assembling into a uniform porous dynamic filter aid layer. This structure effectively intercepts pollutants and possesses a certain degree of self-renewal capability, contributing to the long-term stability of membrane flux.

[0042] Step S03: The liquid forming the dynamic filter aid layer is filtered and separated through a nano-ceramic membrane module to obtain permeate and concentrate.

[0043] The pretreated solution with the formed dynamic filter aid layer was pumped to a tubular ceramic ultrafiltration membrane module (membrane pore size approximately 20 nm). Cross-flow filtration was employed, with the operating pressure controlled at 0.4–0.6 MPa, the cross-flow velocity at approximately 4 m / s, and the system temperature maintained at around 40°C. During filtration, the dynamic filter aid layer and the ceramic membrane worked together to effectively retain organic matter, colloids, and some multivalent ions. The resulting permeate was clear and transparent, while the concentration of pollutants in the concentrate gradually increased. To prevent excessive densification of the dynamic layer, a short-duration pulsed gas purging (lasting approximately 30 seconds) was performed every 8 hours to maintain the permeability and antifouling properties of the filter aid layer.

[0044] Step S04: The permeate is used as recycled water for resource utilization, and the concentrate is further concentrated and evaporated for crystallization to achieve the separation and reuse of high-salt wastewater.

[0045] The liquid water is stable and suitable for direct feeding into the plant's circulating cooling water system or as boiler feedwater, achieving closed-loop recycling of industrial water. The concentrate first enters a high-pressure nanofiltration system for further concentration, increasing the salt concentration before being sent to a mechanical vapor recompression (MVR) evaporation crystallization unit. Through forced circulation evaporation, high-purity sodium chloride crystals are separated. The mother liquor can be further processed according to actual needs or used as raw material for the recovery of other salts, thus completing the deep separation and resource reuse of high-salt wastewater. The overall process wastewater discharge is extremely low.

[0046] This embodiment effectively overcomes the shortcomings of traditional organic membranes and single ceramic membranes in high-salt wastewater treatment. These membranes are susceptible to fouling by high hardness, high silica, and high organic loads, leading to rapid degradation, severe flux decline, low recovery rate, and short operating cycles. The dynamic filter aid layer utilizes the porous structure and self-renewal properties of nano-ceramic particles to significantly enhance the membrane surface's antifouling ability, improve membrane flux stability, and enhance long-term operational reliability. Combined with pretreatment to remove most suspended solids and hardness ions, and subsequent concentration and crystallization for resource recovery of the concentrate, this approach effectively addresses these issues. The entire process achieves a high system recovery rate in the front-end membrane separation stage, significantly reducing the feed volume and energy consumption in the subsequent evaporation and crystallization stages. It overcomes the problems of prominent early-stage concentration bottlenecks, easy equipment scaling, high overall energy consumption, and high operation and maintenance costs in traditional multi-stage membrane concentration + evaporation processes. At the same time, this method produces stable effluent, allows direct reuse of permeate, and enables efficient classification and recovery of inorganic salts after crystallization of the concentrate. This not only significantly improves the resource utilization level of high-salinity wastewater but also greatly reduces waste liquid discharge, promoting the achievement of near-zero or zero-liquid discharge goals. It has outstanding environmental benefits, economic benefits, and technology promotion value.

[0047] In some embodiments, a complete pretreatment method suitable for high-salinity wastewater is provided. Through multi-stage physical-chemical combined treatment, suspended solids, hardness ions and some organic matter are effectively removed, providing high-quality feed water for subsequent nano-ceramic membrane filtration and membrane separation, significantly reducing the risk of membrane fouling and improving the overall system stability.

[0048] Specifically, the high-salinity wastewater raw water is pretreated by sequentially employing coagulation sedimentation, chemical softening, and precision filtration.

[0049] High-salinity wastewater from a petrochemical plant was used as the treatment target. The wastewater had a total dissolved solids (TDS) of approximately 28,000 mg / L and contained a large amount of suspended solids, colloidal particles, and a high concentration of calcium and magnesium ions. First, coagulation and sedimentation were performed. An appropriate amount of polyaluminum chloride (PAC) was added to the raw water as a coagulant, along with a small amount of polyacrylamide (PAM) as a coagulant aid. The mixture was rapidly stirred for 1–2 minutes, followed by slow stirring for 10–15 minutes to promote floc formation. The mixture was then allowed to settle for 30–60 minutes, effectively removing most of the suspended solids and some organic matter from the supernatant.

[0050] Furthermore, the chemical softening employs the lime-soda ash method or the sodium hydroxide-sodium carbonate method to reduce the mass concentration of calcium and magnesium ions to below 50 mg / L.

[0051] The supernatant after coagulation and sedimentation is chemically softened. This embodiment uses the sodium hydroxide-sodium carbonate method. First, sodium hydroxide is added to adjust the pH to 10.0–10.5, causing magnesium ions to precipitate primarily as magnesium hydroxide. Then, sodium carbonate is added to convert calcium ions into calcium carbonate precipitate. Gentle stirring is maintained during the addition process to avoid localized over-alkalinity, and the reaction time is approximately 30 minutes. After the reaction is complete, solid-liquid separation is performed using an inclined plate sedimentation tank or a high-efficiency sedimentation tank, and the settled sludge is periodically discharged. After softening treatment, the total mass concentration of calcium and magnesium ions in the wastewater is reduced to below 40 mg / L, effectively preventing the risk of scaling in subsequent membrane processes.

[0052] Furthermore, the pH value of the pretreated solution obtained after pretreatment is controlled at 7.0-9.0, and the turbidity is less than 5 NTU.

[0053] Understandably, the clarified liquid after softening and settling enters a neutralization and adjustment tank, where a small amount of dilute hydrochloric acid or industrial waste acid is added to slowly adjust the pH value back to the range of 7.5–8.5, avoiding the potential impact of excessively high pH on subsequent membrane materials. Finally, it undergoes terminal filtration through a precision filter (5μm filter cartridge precision) to further remove residual fine particles and incompletely settled micro-flocculations, resulting in a pretreated liquid with a turbidity of less than 3 NTU and a stable pH value of 7.0–9.0. This pretreated liquid is clear, has low hardness, and good stability, and can be directly used as feed water for the nano-ceramic membrane filter aid, ensuring uniform formation of the subsequent dynamic filter aid layer and efficient and stable membrane separation process.

[0054] In some embodiments, a specific method for material selection, parameter control, and surface modification is provided. By optimizing the particle size, specific surface area, and hydrophilicity of the filter aid material, the formation efficiency, antifouling performance, and compatibility with the ceramic membrane of the dynamic filter aid layer are significantly improved, enabling it to exhibit more stable interception capacity and flux retention rate in high-salt wastewater treatment.

[0055] Specifically, the nano-ceramic membrane filter aid material is alumina-based, zirconium oxide-based, silicon carbide-based, or titanium-based nanoparticles with an average particle size range of 10-100 nm and a specific surface area greater than 50 m² / g.

[0056] In this embodiment, alumina-based nanoparticles were selected as the nanoceramic membrane filter aid material. This material was prepared using the sol-gel method, with an average particle size controlled at 25–35 nm (measured using a laser particle size analyzer), and a specific surface area of ​​approximately [value missing] as determined by the BET method. This combination of particle size and specific surface area ensures good dispersion of particles in aqueous solution and rapid migration to the membrane surface, while also forming a sufficiently dense but non-clogging dynamic filter aid layer, effectively intercepting colloids, organic matter, and some multivalent ions in high-salt wastewater.

[0057] To further explain, if adjustments are needed for different wastewater characteristics, zirconia-based nanoparticles (average particle size approximately 40 nm, specific surface area approximately...) can be selected. To enhance acid and alkali resistance, or silicon carbide-based nanoparticles (average particle size approximately 15 nm, specific surface area approximately...) To improve high-temperature resistance and mechanical strength, titanium-based nanoparticles are more suitable for wastewater with high organic loads due to their high surface activity, which helps in the photocatalytic synergistic degradation of some organic pollutants. All materials are selected to ensure an average particle size in the range of 10-100 nm and a specific surface area greater than [missing information]. To maintain the porosity and self-renewal properties of the dynamic filter aid layer.

[0058] The nano-ceramic membrane filter aid material undergoes surface hydrophilic modification treatment before use. The modification methods include hydroxylation treatment, silane coupling agent treatment, or grafting with polyethylene glycol. After modification, the water contact angle is less than 30°.

[0059] Understandably, the above-mentioned alumina-based nanoparticles undergo surface hydrophilic modification treatment. This embodiment employs a combination of hydroxylation treatment and silane coupling agent grafting: first, the nanoparticles are placed in a 5 mol / L sodium hydroxide solution and stirred at 80°C for 2 hours to enrich the surface with a large number of hydroxyl groups. The group was then washed with water until neutral, dried and dispersed in ethanol. 3-Aminopropyltriethoxysilane (KH550) was added as a coupling agent, and the mixture was refluxed at 60°C for 4 hours to achieve silanization grafting and further introduce hydrophilic amino groups.

[0060] In practice, direct grafting of polyethylene glycol (PEG, molecular weight 2000-5000) can also be chosen: the hydroxylated particles are amidated with carboxyl-terminated PEG under EDC / NHS catalysis, with the grafting rate controlled at 15-25 wt%. After modification, the water contact angle of the modified particles after tableting is measured by a static water contact angle tester, and it decreases to [value missing]. It significantly improves the dispersion stability of particles in high-salt aqueous solutions and the uniformity of adhesion to the membrane surface, avoids agglomeration, and ensures that the dynamic filter aid layer is rapidly formed in the early stage of filtration and maintains a loose and porous structure, thereby enhancing the overall membrane separation process's antifouling ability and long-term flux stability.

[0061] In some embodiments, the step of adding nano-ceramic membrane filter aid material to the pretreatment liquid and forming a dynamic filter aid layer provides a way to precisely control the dosage, stirring conditions and dynamic layer formation, ensuring that the nano-ceramic particles are uniformly dispersed and a stable and regenerable dynamic filter aid layer is rapidly constructed on the ceramic membrane surface, thereby significantly improving the antifouling performance and flux stability of the membrane separation process.

[0062] The dosage is 0.05-0.5 g / L based on the volume of the pretreated liquid.

[0063] In this embodiment, the volume of the pretreatment liquid is 500L (which can be scaled up according to the system size in actual engineering), and an alumina-based nano-ceramic membrane filter aid material with surface hydrophilic modification (average particle size of about 30nm) is selected. After calculating the dosage, the total dosage for this batch is determined to be 100g (corresponding to a dosage of 0.2g / L, which is the middle value of the range of 0.05-0.5g / L specified in claim 4).

[0064] In practice, 100g of nanoparticles were accurately weighed using an electronic scale and pre-dispersed in a small amount of deionized water (approximately 5L). The dispersion was then ultrasonically dispersed for 30 minutes to form a uniform suspension, avoiding agglomeration caused by direct addition of dry powder. This pre-dispersion method helps the particles distribute more quickly and evenly in the pretreatment solution, laying the foundation for the rapid formation of the subsequent dynamic filter aid layer.

[0065] Furthermore, the nano-ceramic particles are added under stirring conditions at a stirring speed of 100-300 rpm, and stirring is continued for 10-40 minutes after addition, so that the nano-ceramic particles form the dynamic filter aid layer on the surface of the nano-ceramic membrane module.

[0066] Place the pretreated liquid in a dosing tank equipped with a mechanical stirrer, start the stirrer, and adjust the speed to 200 rpm (the middle value in the range of 100-300 rpm) to keep the liquid in a uniform turbulent state. Then slowly pump in the pre-dispersed nanoparticle suspension. The entire dosing process should be completed within 5 minutes to avoid excessively high local concentrations that could cause the particles to settle rapidly.

[0067] Understandably, after addition, continue stirring at 200 rpm for 25 minutes. During this process, the nano-ceramic particles gradually migrate towards the inner wall of the tubular ceramic ultrafiltration membrane module with the fluid flow. Under the combined action of cross-flow shear force and van der Waals force, they self-assemble and deposit on the membrane surface, forming a dynamic filter aid layer with a thickness of approximately 10-20 μm. This layer has a porous sponge-like structure, which can effectively intercept colloids, organic matter, and some multivalent ions in high-salt wastewater, while allowing water molecules and monovalent salt ions to pass through smoothly. It also has a certain self-renewal capacity—during the filtration process, after the outer layer of pollutants becomes saturated, it can be discharged with the concentrate, and the inner layer particles rearrange themselves to maintain long-term stable flux.

[0068] In subsequent practical verification, after the addition was completed, the membrane surface was sampled and observed (through a small sampling tube or a transparent test membrane module). It was observed that the dynamic filter aid layer was uniformly covered with no obvious exposed areas. The initial filtration flux was increased by about 30-50% compared with the absence of the filter aid layer, which proved the effectiveness of the addition and stirring conditions and provided a reliable anti-fouling basis for the subsequent filtration and separation steps.

[0069] In some embodiments, a specific selection, structural parameters, and operating conditions for a ceramic ultrafiltration membrane module suitable for high-salt wastewater separation are provided. By rationally selecting the membrane type, pore size range, and operating parameters, efficient collaboration with the dynamic filter aid layer is ensured to achieve high throughput, long-term stable operation, and good pollutant retention effect.

[0070] Specifically, the nano-ceramic membrane module is a tubular, multi-channel planar, or honeycomb ceramic ultrafiltration membrane with a pore size range of 5-50 nm.

[0071] In this embodiment, a tubular ceramic ultrafiltration membrane module is selected as the core separation unit. This module consists of multiple single-channel or multi-channel alumina-based ceramic membrane tubes (each tube has an outer diameter of 30 mm, an inner diameter of approximately 20 mm, and a length of 1200 mm). The membrane material is high-purity α-alumina, and the support layer is porous ceramic. The overall module exhibits excellent pressure resistance, temperature resistance, and acid and alkali resistance.

[0072] The membrane pore size, determined by the bubble point method and nitrogen permeation method, is 18–22 nm, falling within the 5–50 nm range specified in claim 5. This pore size effectively retains colloids, large organic molecules, and some multivalent ions in high-salt wastewater, while allowing monovalent salt ions and most water molecules to pass through smoothly. When combined with a dynamic filter aid layer, it further enhances the interception capacity for small-molecule organic matter and fine particles, avoiding the problems of insufficient retention rate due to excessively large membrane pore size or rapid flux decay due to excessively small pore size.

[0073] For larger-scale treatment or higher packing density applications, multi-channel flat-sheet ceramic membranes (19–37 channels, larger membrane area) can be selected. For wastewater with high viscosity or containing a large amount of fibrous material, honeycomb ceramic membranes can be considered to improve anti-clogging capabilities. All types ensure that the membrane pore size is controlled within the 5–50 nm range to match the dynamic layer enhancement effect of the nano-ceramic membrane filter aid.

[0074] Furthermore, the operating pressure is 0.1-1.0 MPa, and the operating temperature is 20-90℃.

[0075] During system operation, the operating pressure is controlled at 0.4 to 0.6 MPa (a medium to high value in the range of 0.1 to 1.0 MPa). A variable frequency pump is used to precisely adjust the transmembrane pressure difference (TMP) and keep it between 0.3 and 0.5 MPa to avoid excessive pressure that could lead to over-compaction of the dynamic filter aid layer or damage to the membrane tube.

[0076] The operating temperature is set at approximately 40℃ (maintained via heat exchanger or steam heating). This temperature reduces wastewater viscosity and increases flux without accelerating the adsorption of organic matter on the membrane surface or causing thermal agglomeration of nanoparticles. If the wastewater contains high levels of volatile components or requires energy-saving operation, the temperature can be lowered to 25–35℃; if the wastewater temperature is high and has good temperature resistance (such as some high-temperature process wastewater), it can be increased to 60–80℃ to further increase flux. The entire operating temperature range is strictly controlled within 20–90℃ to ensure the long-term structural stability of the ceramic membrane module and that the formation and regeneration of the dynamic filter aid layer are not affected by temperature fluctuations.

[0077] Understandably, under the conditions of this embodiment, the initial membrane flux can reach 80–120 L / m³. After 72 hours of continuous operation, the flux decay was less than 15%, which proved the good matching between the membrane module parameters and the dynamic filter aid layer, providing an efficient and reliable hardware foundation for the subsequent filtration and separation process.

[0078] In some embodiments, the step of filtration and separation using a nano-ceramic membrane module provides a way to achieve complete control of operating parameters and dynamic maintenance of the filter aid layer. By optimizing membrane flux, recovery rate and regular regeneration measures, the system can ensure high-efficiency separation performance during long-term continuous operation of high-salt wastewater, while effectively extending the service life of the membrane module and reducing the cleaning frequency.

[0079] In the step of filtration and separation using a nano-ceramic membrane module, the membrane flux is controlled at 50-150 L / m³. The system recovery rate reaches 70-90%.

[0080] In this embodiment, the aforementioned tubular ceramic ultrafiltration membrane module (membrane pore size approximately 20 nm) is used in conjunction with a pre-formed dynamic filter aid layer for filtration separation. During the initial operation phase, the transmembrane pressure differential (TMP) is precisely adjusted between 0.35 and 0.45 MPa using a variable frequency pump and a reflux valve, and the membrane flux is stabilized at 90–110 L / m³. Within the range (50-150L / (Above-average value).

[0081] As filtration progresses, the concentrate concentration gradually increases, and the flux will slowly decrease. At this point, the flux can be maintained at no less than 70 L / min by appropriately increasing the cross-flow rate or fine-tuning the TMP (not exceeding 0.6 MPa). The system recovery rate was set at 80% (within the 70-90% range), meaning that for every 100L of influent, 80L of permeate was produced and 20L of concentrate was discharged. This recovery rate achieves high water resource recovery while avoiding excessively rapid increases in concentrate salt concentration, which could lead to over-densification of the dynamic filter bed or exacerbate membrane fouling. During a 168-hour continuous operation test, the average membrane flux remained at 85L / m³. The recovery rate remained stable at 78-82%, demonstrating that the synergistic effect of the dynamic filter aid layer and the membrane module significantly improved the separation efficiency.

[0082] Furthermore, a cross-flow filtration method is adopted in the filtration process, and pulse air washing or backwashing is performed periodically to regenerate the dynamic filter aid layer, with a cleaning cycle of 4-24 hours.

[0083] The entire filtration process employs a cross-flow filtration mode, with the concentrate circulating within the membrane tube at a flow rate of 4–5 m / s, generating shear force to prevent excessive deposition of contaminants on the membrane surface.

[0084] To maintain the permeability and self-renewal capacity of the dynamic filter aid layer, pulse air washing regeneration is performed every 8 hours: compressed air (pressure 0.4-0.6 MPa) is injected into the membrane tube in short pulses (each pulse lasts 2-3 seconds, with an interval of 10 seconds, for a total of 10-15 pulses) to momentarily disturb the membrane surface, causing the outer layer of saturated pollutant particles to fall off. At the same time, some nano-ceramic particles are discharged with the concentrate, and new particles can be replenished from the feed water, realizing the natural renewal of the dynamic layer.

[0085] If the flux decreases rapidly during operation (e.g., more than 20%), an additional backwash can be performed: backwash the membrane tubes with permeate at a pressure of 0.3 MPa for 5-10 minutes, combined with air-water cleaning, to further remove deep-seated contaminants. The cleaning cycle can be flexibly adjusted according to the wastewater pollution load. Under the high-salinity wastewater conditions of this embodiment, pulse air washing is typically performed every 8-12 hours, and backwashing is performed every 24-48 hours. The membrane flux recovery rate can reach over 90%, achieving effective regeneration of the dynamic filter aid layer and long-term stable operation of the system.

[0086] In some embodiments, such as Figure 2 As shown, the steps of further concentrating and evaporating the concentrate provide a complete method for stepwise concentration and crystallization recovery. By coupling high-pressure membrane concentration and evaporation crystallization, the evaporation energy consumption is effectively reduced, the salt recovery rate is improved, and the high-purity resource utilization of inorganic salts such as sodium chloride and sodium sulfate is achieved, ensuring the economic efficiency and resource recovery value of high-salt wastewater treatment.

[0087] Step S71: First, use high-pressure nanofiltration or reverse osmosis to further concentrate the concentrate so that the TDS reaches 120,000-200,000 mg / L.

[0088] In this embodiment, the concentrated solution obtained from the nanoceramic membrane module has a TDS of approximately 80,000–100,000 mg / L, and is first pumped into a high-pressure nanofiltration system for further concentration. A high-pressure, corrosion-resistant composite nanofiltration membrane module (operating pressure 2.0–4.0 MPa) is selected, with the membrane element being a polyamide composite membrane or a dedicated antifouling nanofiltration membrane. The system employs a multi-stage series arrangement (3–4 stages), maintaining a cross-flow velocity of 3–5 m / s and a temperature control of 35–45°C.

[0089] By gradually increasing the recovery rate, the TDS of the concentrate gradually increased, eventually stabilizing at 150,000–180,000 mg / L (within the range of 120,000–200,000 mg / L). During this process, high-pressure nanofiltration effectively retained most divalent and multivalent ions (such as…). ), monovalent ions (such as Partial permeate occurs, resulting in significant salt enrichment in the concentrate. Simultaneously, a portion of the low-salt permeate can be incorporated into the preceding permeate for reuse. This concentration step significantly reduces the feed volume for subsequent evaporation processes, thereby lowering overall energy consumption.

[0090] Step S72: Then, use mechanical vapor recompression (MVR) evaporation, multi-effect evaporation, or freeze crystallization to process the product and recover sodium chloride, sodium sulfate, or other inorganic salt crystals.

[0091] The concentrated high-salt solution is then processed in an MVR evaporation crystallization unit. This embodiment uses an MVR evaporator equipped with a high-efficiency heat exchanger and a mechanical compressor. The evaporation temperature is controlled between 90 and 105°C. The compressor compresses the secondary steam and uses it as a heat source, achieving steam recycling. The power consumption per unit of evaporated water is approximately 40–60 kWh / t. During the evaporation process, as water continuously evaporates, the solution reaches sodium chloride saturation, and sodium chloride crystals begin to precipitate.

[0092] The crystallization slurry is separated by centrifugation to obtain sodium chloride crystals with a moisture content of approximately 5-8% and a purity of over 98%. After drying, it is sold as an industrial salt product. The mother liquor has a high concentration of other salts such as sodium sulfate, and can be further fed into a subsequent multi-effect evaporator or switched to a freeze crystallization unit (cooled to -5 to 5°C) to further separate sodium sulfate crystals (purity ≥99%) by utilizing the low-temperature precipitation characteristics of sodium sulfate decahydrate.

[0093] The entire crystallization process is automatically controlled by online monitoring of salinity, pH, and temperature. The crystals are uniform in size and easy to separate, ultimately achieving the classified recovery of major inorganic salts such as sodium chloride and sodium sulfate. The mother liquor is recycled or used as raw material for other by-products. The entire process generates extremely low wastewater discharge and achieves a salt resource recovery rate of over 90%, providing an efficient pathway for the resource utilization of high-salt wastewater.

[0094] In some embodiments, the chemical cleaning step for the nano-ceramic membrane module provides a systematic and operable chemical cleaning method. By selecting a suitable cleaning solution, controlling the cleaning conditions, and evaluating the recovery effect, it ensures that the membrane module's performance recovers rapidly after long-term operation, maintains the synergistic separation efficiency of the dynamic filter aid layer and the ceramic membrane, extends the overall equipment lifespan, and reduces maintenance costs.

[0095] Specifically, the method further includes a chemical cleaning step for the nano-ceramic membrane module, wherein the cleaning solution is selected from 0.5-2 wt% sodium hydroxide solution, 0.5-2 wt% nitric acid solution, or citric acid solution.

[0096] In this embodiment, after approximately 200–300 hours of continuous operation, when a decrease in membrane flux of approximately 30%–40% from the initial value is observed, a chemical cleaning procedure is initiated. A 1.0 wt% sodium hydroxide (NaOH) solution is preferentially used as the alkaline cleaning agent to remove organic matter, colloidal substances, and biological fouling. If significant inorganic scale (such as calcium carbonate or silicate scale) is present on the membrane surface, the process is switched to a 1.0 wt% nitric acid solution. For acid washing, a 1.5wt% citric acid solution can be used as a neutral / weakly acidic cleaning agent to reduce potential corrosion of ceramic membrane materials. For mixed contamination or mild cleaning requirements, a 1.5wt% citric acid solution can be used as a neutral / weakly acidic cleaning agent to reduce potential corrosion of ceramic membrane materials.

[0097] All cleaning solutions are prepared on-site using deionized water to ensure precise concentration control within the range of 0.5–2 wt%, avoiding damage to the membrane material due to excessively high concentrations or insufficient cleaning effect due to excessively low concentrations. In actual operation, alkaline washing is performed first to remove organic contaminants, followed by acid washing to remove inorganic scale. The two cleaning solutions can be used alternately and flexibly combined according to the type of membrane fouling.

[0098] Furthermore, the cleaning temperature is 40-70℃, and the cleaning time is 30-120 minutes.

[0099] The chemical cleaning process is carried out in a dedicated cleaning circulation system. The cleaning solution is heated to 55°C (the middle value of the 40-70°C range) and circulated in the membrane tube at a low flow rate (about 1-2 m / s) by a circulation pump to avoid excessive shedding of residual particles from the dynamic filter aid layer due to high-pressure flushing.

[0100] The cleaning time should be controlled between 60 and 90 minutes: the first 30 minutes are the static soaking stage, allowing the cleaning solution to fully penetrate the contaminant layer; the following 30 to 60 minutes are the dynamic circulation stage, with continuous circulation to enhance the dissolution and removal of contaminants. If the contamination is light, the time can be shortened to 40 minutes; if there is a large amount of silica scale or stubborn organic matter, the time can be extended to about 100 minutes. Throughout the process, the cleaning endpoint is determined by online monitoring of changes in the pH, turbidity, and conductivity of the cleaning solution. Cleaning ends when the rate of contaminant dissolution decreases significantly.

[0101] Furthermore, the membrane flux recovery rate after cleaning is no less than 95%.

[0102] After cleaning, the membrane module is thoroughly rinsed with deionized water or permeate until the effluent pH is close to neutral and the conductivity is stable. The filtration system is then restarted, and the recovery of the initial flux is monitored. In this embodiment, after alkali-acid combined cleaning, the membrane flux recovered to 96%–102% of its initial value, with an average recovery rate of over 98%, demonstrating the effectiveness of the cleaning scheme.

[0103] Understandably, in actual verification, after multiple chemical cleaning cycles (more than 10 times in total), the membrane module still maintained good performance, and the flux decline rate was significantly lower than that of the uncleaned cycle. This fully verified the rationality of the cleaning solution concentration, temperature and time, and provided a reliable maintenance guarantee for the long-term stable operation of high-salt wastewater.

[0104] In some embodiments, the cross-flow velocity and dynamic filter aid thickness control of the nano-ceramic membrane module provide a way to optimize hydrodynamic conditions and filter aid structural parameters. By precisely controlling the cross-flow velocity and dynamic filter aid thickness, a balance is achieved between effective flushing of pollutants on the membrane surface, stable adhesion of the dynamic filter aid, and controllable regeneration, thereby significantly improving the antifouling ability, flux retention rate, and long-term operational reliability of the membrane separation process.

[0105] Specifically, the cross-flow velocity of the nano-ceramic membrane module is 2-6 m / s.

[0106] In this embodiment, the tubular ceramic ultrafiltration membrane module of claim 5 is used, and the circulation pump is a high corrosion-resistant centrifugal pump with frequency conversion control, and the cross-flow velocity is set to 4.0 m / s (the middle value in the range of 2-6 m / s).

[0107] The cross-flow velocity is controlled by adjusting the opening of the return valve and the pump speed: in the initial stage, a higher flow velocity (about 5 m / s) is set to quickly establish a dynamic filter aid layer; after stable operation, it is reduced to about 4 m / s to maintain sufficient shear force to prevent excessive deposition of pollutants, while avoiding excessive scouring and shedding of nano-ceramic particles due to excessive flow velocity.

[0108] In actual operation, excessively low flow rates (below 2 m / s) cause rapid accumulation of contaminants on the membrane surface, densification of the dynamic filter aid layer, and accelerated flux decline. Excessively high flow rates (above 6 m / s) may make it difficult for the filter aid layer to adhere stably, resulting in the loss of some nanoparticles with the concentrate and affecting the fouling removal effect. Under the conditions of this embodiment, at a cross-flow velocity of 4 m / s, the membrane surface shear force is moderate, the dynamic filter aid layer maintains a uniform porous state, and the flux decline is less than 18% after 120 hours of continuous operation, demonstrating the rationality of this flow rate range.

[0109] Furthermore, the thickness of the dynamic filter aid layer is controlled between 5-30 μm.

[0110] The thickness of the dynamic filter aid layer is achieved through comprehensive control of the dosage, addition time, cross-flow velocity, and running time. In this embodiment, combined with the addition conditions of claim 4 (0.2 g / L, stirring for 25 minutes) and the cross-flow velocity of 4 m / s, the dynamic filter aid layer forms rapidly in the initial stage of filtration (first 30-60 minutes), and the thickness stabilizes at 12-18 μm (within the range of 5-30 μm).

[0111] Thickness monitoring is conducted indirectly: through online transmembrane pressure difference (TMP) monitoring and periodic sampling observation (small transparent test membrane tube or SEM analysis), when the TMP rise rate accelerates or the flux decreases significantly, it indicates that the thickness is too thick (approaching or exceeding 25 μm). At this time, the outer saturated particles can be washed away by briefly increasing the crossflow velocity to 5.5 m / s and combining it with short-term pulsed gas washing, so that the thickness drops back to about 15 μm.

[0112] Conversely, if the thickness is too thin (below 5 μm), the fouling interception capacity is insufficient, and contaminants directly contact the ceramic membrane, leading to irreversible fouling. In this case, a small amount of nanoparticles can be added (0.02–0.05 g / L) or the crossflow velocity can be reduced to 3 m / s to promote particle deposition. In actual operation, when the thickness is controlled within the range of 10–20 μm, the average system flux remains at 90 L / L. The above-mentioned membrane has the best anti-fouling performance. The dynamic filter aid layer can effectively intercept pollutants and has good permeability and self-renewal ability, ensuring the high efficiency and stability of the entire membrane separation process.

[0113] In some embodiments, the characteristics of raw high-salinity wastewater and the effects after treatment provide a typical implementation method for the entire process of high-salinity wastewater treatment. This method is used to completely treat high-concentration saline wastewater, verifying that the effluent quality meets industrial reuse standards and that the inorganic salts can be recovered by crystallization of the concentrate. It demonstrates the adaptability of the process to high-TDS wastewater and its effectiveness in resource utilization.

[0114] Specifically, the raw high-salinity wastewater has a TDS ≥ 10000 mg / L and a COD of 200-2000 mg / L.

[0115] In this embodiment, a typical high-salinity wastewater source from a coal chemical project was selected as the treatment target. This wastewater has a TDS of approximately 42,000 mg / L (far exceeding 10,000 mg / L), a COD of approximately 850 mg / L (within the range of 200-2000 mg / L), and contains high concentrations of sodium chloride, sodium sulfate, calcium and magnesium ions, silicates, and small amounts of organic pollutants. Its pH value is approximately 7.2–8.0, and its turbidity is high. It is a typical high-salinity, high-hardness, and complex industrial wastewater, making efficient separation and reuse difficult using traditional treatment methods.

[0116] Furthermore, after treatment by the method described above, the permeate has a TDS of less than 500 mg / L and a COD of less than 50 mg / L, and can be directly reused as industrial circulating cooling water or boiler feedwater.

[0117] Following the complete process described in claims 1-9 (including pretreatment, addition of nano-ceramic membrane filter aid material and formation of dynamic filter aid layer, filtration and separation by ceramic ultrafiltration membrane module, and regular regeneration and maintenance), the quality of the permeate produced by the system is significantly improved. Actual operating data shows that the permeate TDS is stable at 280-420 mg / L (far below 500 mg / L), COD is reduced to 25-45 mg / L (below 50 mg / L), turbidity is <1 NTU, pH is 7.0-8.0, and the permeate is essentially colorless and transparent with no obvious odor. The quality of this permeate fully meets the requirements for industrial circulating cooling water makeup water or medium-pressure boiler feed water, and can be directly connected to the plant's recycled water network to achieve closed-loop recycling, reducing fresh water consumption and conserving water resources.

[0118] Understandably, the concentrate can be crystallized to obtain sodium chloride, sodium sulfate, or other inorganic salt crystals, thus realizing the resource utilization of inorganic salts.

[0119] The concentrated solution obtained from the nano-ceramic membrane module has a TDS of approximately 110,000–130,000 mg / L. It is then further concentrated to approximately 170,000 mg / L via high-pressure nanofiltration before being fed into an MVR evaporation crystallization system. During evaporation crystallization, high-purity sodium chloride crystals (purity ≥ 98.5%, uniform particle size, moisture content < 6%) are first precipitated and separated. After centrifugation, washing, and drying, these crystals are sold as industrial-grade sodium chloride. The remaining mother liquor has a high sodium sulfate concentration. It is then further processed through multi-effect evaporation or switched to a freeze crystallization unit to precipitate sodium sulfate decahydrate. This decahydrate is then melt-dehydrated to obtain anhydrous sodium sulfate crystals (purity ≥ 99%).

[0120] Ultimately, sodium chloride and sodium sulfate, the two main inorganic salts, were recovered separately, with a total salt recovery rate exceeding 92%. The crystalline product quality was stable and it can be used as a chemical raw material or de-icing agent, achieving the resource utilization of inorganic salts in wastewater. The entire process resulted in extremely low wastewater discharge, achieving the goal of efficient separation and resource reuse of high-salt wastewater.

[0121] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for separating and reusing high-salinity wastewater based on nano-ceramic membrane filter aid materials, characterized in that, The method includes the following steps: A high-salinity wastewater raw water is provided, and the high-salinity wastewater raw water is pretreated to remove suspended solids, hardness ions and some organic matter to obtain a pretreated liquid. Nano-ceramic membrane filter aid material is added to the pretreatment liquid to form a dynamic filter aid layer; The liquid forming the dynamic filter aid layer is filtered and separated through a nano-ceramic membrane module to obtain permeate and concentrate; The permeate is used as recycled water for resource utilization, and the concentrate is further concentrated and evaporated for crystallization to achieve the separation and reuse of high-salt wastewater.

2. The method for separating and reusing high-salt wastewater based on nano-ceramic membrane filter aid material as described in claim 1, characterized in that, The steps for pretreating high-salinity wastewater include: sequentially using coagulation sedimentation, chemical softening, and precision filtration. The chemical softening process employs either the lime-soda ash method or the sodium hydroxide-sodium carbonate method to reduce the mass concentration of calcium and magnesium ions to below 50 mg / L. The pH of the pretreated solution was controlled at 7.0-9.0 and the turbidity was less than 5 NTU.

3. The method for separating and reusing high-salt wastewater based on nano-ceramic membrane filter aid material as described in claim 1, characterized in that, The nano-ceramic membrane filter aid material is composed of alumina-based, zirconium oxide-based, silicon carbide-based, or titanium-based nanoparticles with an average particle size ranging from 10 to 100 nm and a specific surface area greater than [missing information]. ; The nano-ceramic membrane filter aid material undergoes surface hydrophilic modification treatment before use. The modification methods include hydroxylation treatment, silane coupling agent treatment, or grafting with polyethylene glycol. After modification, the water contact angle is less than 30°.

4. The method for separating and reusing high-salt wastewater based on nano-ceramic membrane filter aid material as described in claim 1, characterized in that, The step of adding nano-ceramic membrane filter aid material to the pretreatment liquid includes: The dosage is 0.05-0.5 g / L based on the volume of the pretreated liquid. The nano-ceramic particles are added under stirring conditions at a stirring speed of 100-300 rpm. After addition, stirring is continued for 10-40 minutes to form the dynamic filter aid layer on the surface of the nano-ceramic membrane module.

5. The method for separating and reusing high-salt wastewater based on nano-ceramic membrane filter aid material as described in claim 1, characterized in that, The nano-ceramic membrane module is a tubular, multi-channel planar, or honeycomb ceramic ultrafiltration membrane with a pore size range of 5-50 nm, an operating pressure of 0.1-1.0 MPa, and an operating temperature of 20-90 °C.

6. A method for separating and reusing high-salt wastewater based on nano-ceramic membrane filter aid material as described in claim 1 or 5, characterized in that, In the step of filtration and separation using a nano-ceramic membrane module, the membrane flux is controlled at 50-150 L / m³. The system's recovery rate reaches 70-90%; The filtration process employs a cross-flow filtration method, and periodically performs pulse air washing or backwashing to regenerate the dynamic filter aid layer, with a cleaning cycle of 4-24 hours.

7. The method for separating and reusing high-salt wastewater based on nano-ceramic membrane filter aid material as described in claim 1, characterized in that, The steps of further concentrating and evaporating the concentrate include: First, high-pressure nanofiltration or reverse osmosis is used to further concentrate the concentrate so that the TDS reaches 120,000-200,000 mg / L; The sodium chloride, sodium sulfate, or other inorganic salt crystals are then recovered by mechanical vapor recompression (MVR) evaporation, multi-effect evaporation, or freeze crystallization.

8. A method for separating and reusing high-salinity wastewater based on nano-ceramic membrane filter aid material as described in any one of claims 1-7, characterized in that, The method further includes a chemical cleaning step for the nano-ceramic membrane module. The cleaning solution is selected from 0.5-2wt% sodium hydroxide solution, 0.5-2wt% nitric acid solution or citric acid solution. The cleaning temperature is 40-70℃, the cleaning time is 30-120 minutes, and the membrane flux recovery rate after cleaning is not less than 95%.

9. A method for separating and reusing high-salinity wastewater based on nano-ceramic membrane filter aid material as described in any one of claims 1-7, characterized in that, The cross-flow velocity of the nano-ceramic membrane module is 2-6 m / s, and the thickness of the dynamic filter aid layer is controlled at 5-30 μm.

10. A method for separating and reusing high-salinity wastewater based on nano-ceramic membrane filter aid material as described in any one of claims 1-7, characterized in that, The raw high-salinity wastewater has a TDS ≥ 10000 mg / L and a COD of 200-2000 mg / L; After treatment by the method described above, the permeate has a TDS of less than 500 mg / L and a COD of less than 50 mg / L, and can be directly reused as industrial circulating cooling water or boiler feedwater; the concentrate can be crystallized to obtain sodium chloride, sodium sulfate or other inorganic salt crystal products, realizing the resource utilization of inorganic salts.

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