A low-cost treatment system for high-salinity wastewater in the steel industry

Abstract

The utility model discloses a kind of steel industry high-salinity wastewater low-cost treatment systems, including the adjusting pool connected in turn, electrochemical pretreatment device, halophilic biological reactor, catalytic Fenton oxidation reactor, nanofiltration concentration device, seed crystallization reactor, electrodialysis device, multistage adsorption system, intelligent control center and energy recovery system.Electrochemical pretreatment device uses scrap iron as anode;Catalytic Fenton reactor integrates photo-electric coupling technology and magnetic Fe3O4 catalyst;Nanofiltration device realizes different valence ion separation;Seed crystallization and electrodialysis recover calcium fluoride and sodium chloride respectively;Multistage adsorption system uses steel slag, biochar etc. for advanced treatment.The system makes full use of steel plant by-products, realizes waste treatment with waste, and the treatment cost is reduced by more than 60%;COD removal rate is >95%, desalination rate is >98%;High-purity salt product can be recycled, water reuse rate is >60%;System energy consumption is reduced by more than 30%, with significant economic and environmental benefits.

Description

Technical Field

[0001] This utility model relates to the field of industrial wastewater treatment technology, and in particular to a low-cost treatment system for high-salt wastewater from the steel industry. Background Technology

[0002] The steel industry is a pillar industry of my country's national economy, but it generates a large amount of industrial wastewater during production. With increasingly stringent environmental regulations and growing water scarcity, steel companies commonly employ reverse osmosis technology for advanced wastewater treatment and reuse. However, while reverse osmosis produces high-quality reclaimed water, it inevitably generates 20-30% high-salinity concentrate, which constitutes 20,000-40,000 mg / L of the treated water. This concentrate is characterized by high salinity, TDS typically ranging from 20,000 to 40,000 mg / L, high organic matter concentration (COD) reaching 500-1500 mg / L, and high concentrations of fluorides and chlorides. Due to the highly concentrated pollutants, this type of wastewater is extremely difficult to treat. Direct discharge would not only cause serious environmental problems such as soil salinization and groundwater pollution but also lead to the waste of valuable water and salt resources. Therefore, how to economically and effectively treat high-salinity wastewater from the steel industry has become a key technical challenge restricting the industry's sustainable development.

[0003] Currently, domestic and international technologies for treating high-salinity wastewater mainly include evaporation crystallization, membrane separation concentration, chemical precipitation, and advanced oxidation. While evaporation crystallization can achieve zero liquid discharge, it has extremely high energy consumption, with treatment costs typically ranging from 80 to 150 yuan per ton of water, and the resulting mixed salts are difficult to utilize as resources. Multi-stage reverse osmosis concentration technology suffers from severe membrane fouling, limited concentration ratios, and high operating costs. Traditional chemical precipitation methods are ineffective at removing organic matter, producing large amounts of sludge that are difficult to dispose of. Single advanced oxidation technologies, such as Fenton oxidation, while having good removal effects on organic matter, consume large amounts of reagents and have poor adaptability to high salinity. Furthermore, existing technologies often focus only on pollutant removal, neglecting resource recovery and energy utilization, resulting in persistently high treatment costs.

[0004] A comprehensive analysis of existing technologies reveals several key problems: First, the treatment process is simplistic and inadequate for addressing the complex water quality characteristics of high-salinity wastewater. Second, there is an over-reliance on purchased chemical reagents, resulting in high operating costs. Third, there is a lack of comprehensive utilization of byproducts from steel production, failing to achieve "waste-to-waste treatment." Fourth, the level of automation and intelligence is low, making it difficult to adjust operating parameters promptly based on changes in water quality. Fifth, energy recovery during the treatment process is neglected, leading to high system energy consumption. Therefore, there is an urgent need to develop a new type of high-salinity wastewater treatment system for the steel industry that is highly integrated, has low treatment costs, and high resource utilization rates to meet increasingly stringent environmental protection requirements and the needs of sustainable development for enterprises. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a low-cost treatment system for high-salt wastewater from the steel industry.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A low-cost treatment system for high-salt wastewater from the steel industry includes, in sequence, an equalization tank, an electrochemical pretreatment device, a halophilic bioreactor, a catalytic Fenton oxidation reactor, a nanofiltration thickener, a seed crystallization reactor, an electrodialysis device, a multi-stage adsorption system, an intelligent control center, an energy recovery system, and a sludge treatment system. The nanofiltration thickener has a concentrated water outlet and a desalinated water outlet. The concentrated water outlet is connected to the seed crystallization reactor and the electrodialysis device, respectively, and the desalinated water outlet is connected to the inlet of the multi-stage adsorption system.

[0008] Furthermore, the electrochemical pretreatment device includes an electrolytic cell body, iron scrap anodes, stainless steel cathodes, and a DC power supply; the iron scrap anodes are made by pressing and molding scrap iron from steel plants, and the electrolytic cell body is equipped with multiple sets of parallel-arranged plates with a plate spacing of 10-20 mm and a current density of 10-20 mA / cm².

[0009] Furthermore, the halophilic bioreactor adopts an upflow anaerobic sludge bed structure, which is filled with a modified polyurethane foam biological carrier with a specific surface area of ​​1500 m² / m³. A water distributor is installed at the bottom of the reactor and a three-phase separator is installed at the top. The reactor is inoculated with halophilic bacteria of the genera *Haloxylon* and *Haloxybacterium*.

[0010] Furthermore, the catalytic Fenton oxidation reactor includes a reactor body, a UV-LED light source system, a magnetic catalyst dosing system, and an iron-carbon micro-electrolysis packing layer; the UV-LED light source system uses LED lamps with a wavelength of 365nm and a power density of 20-30W / m³; the magnetic catalyst is nano-Fe3O4 with a particle size of 50-100nm, and the dosage is 0.5-1.0g / L; the iron-carbon micro-electrolysis packing layer is made by mixing and pressing iron filings and activated carbon in a mass ratio of 3:1.

[0011] Furthermore, the nanofiltration concentration unit uses a polyamide composite membrane with a molecular weight cutoff of 200-400 Da, achieving a rejection rate of >95% for divalent ions and <20% for monovalent ions; the seed crystallization reactor has a seed inlet at the bottom for adding calcium fluoride seed crystals with a particle size of 0.1-0.3 mm; the electrodialysis unit employs heterogeneous membrane electrodialysis technology, with the anion exchange membrane targeting Cl... - The selective transmittance coefficient is >0.9.

[0012] Furthermore, the multi-stage adsorption system includes three adsorption towers connected in series: the first-stage adsorption tower is filled with modified steel slag adsorbent, the second-stage adsorption tower is filled with biochar adsorbent obtained by co-pyrolysis of coke powder and residual sludge at 600°C, and the third-stage adsorption tower is filled with 13X molecular sieve; each adsorption tower is equipped with an online regeneration system.

[0013] Furthermore, the intelligent control center includes a data acquisition module, a predictive analysis module, and an automatic control module; the predictive analysis module uses an LSTM neural network model to predict the dosage of the reagent and operating parameters.

[0014] Furthermore, the energy recovery system includes a waste heat recovery device, a biogas power generation device, and a photovoltaic power generation system; the waste heat recovery device collects the reaction heat of the catalytic Fenton oxidation reactor for sludge drying; the biogas power generation device collects biogas produced by the halophilic bioreactor for power generation.

[0015] The beneficial effects of this utility model are as follows:

[0016] 1. It realizes the resource utilization of by-products of the steel industry, including scrap iron, pickling waste liquid, steel slag, coke powder, etc., truly achieving waste treatment with waste, reducing the cost per ton of water treatment by more than 60%, requiring only 12-15 yuan. It adopts a combined process for synergistic treatment, achieving a COD removal rate of over 95%, a desalination rate of over 98%, and fluoride and chloride removal rates of over 95%. The effluent water quality is stable and meets the standards, and can be directly reused or discharged in compliance with standards.

[0017] 2. It achieves the separate recycling of salts by quality and category. Calcium fluoride with a purity of over 95% can be used as a raw material for fluorochemicals, and sodium chloride can be sold as industrial salt. The water reuse rate is over 60%, truly realizing resource utilization and recycling. Through the application of intelligent control system, the operating parameters can be automatically optimized according to changes in influent water quality, reducing manual operation, improving system stability and treatment efficiency, and reducing the difficulty of operation and management.

[0018] 3. The integrated energy recovery system makes full use of reaction heat, biogas and solar energy, reducing system energy consumption by more than 30%, providing technical support for achieving the carbon neutrality goal. The system adopts a modular design and can be flexibly combined according to different water qualities and treatment scales, with good adaptability and prospects for promotion and application.

[0019] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] Figure 1This is a schematic diagram of the system process flow of a low-cost treatment system for high-salt wastewater in the steel industry proposed in this utility model.

[0021] Figure 2 This is a schematic diagram of the electrochemical pretreatment device of a low-cost treatment system for high-salt wastewater in the steel industry proposed in this utility model.

[0022] Figure 3 This is a schematic diagram of the catalytic Fenton oxidation reactor structure of a low-cost treatment system for high-salt wastewater in the steel industry proposed in this utility model.

[0023] Figure 4 This is a schematic diagram of a multi-stage adsorption system for a low-cost treatment system of high-salt wastewater from the steel industry proposed in this utility model.

[0024] In the diagram: 1. Equalization tank; 2. Electrochemical pretreatment device; 3. Halophilic bioreactor; 4. Catalytic Fenton oxidation reactor; 5. Nanofiltration concentration device; 6. Seed crystallization reactor; 7. Electrodialysis device; 8. Multi-stage adsorption system; 21. Electrolytic cell body; 22. Iron scrap anode; 23. Stainless steel cathode; 24. DC power supply; 41. Reactor body; 42. UV-LED light source system; 43. Magnetic catalyst dosing system; 44. Iron-carbon micro-electrolysis packing layer; 81. First-stage adsorption tower; 82. Second-stage adsorption tower; 83. Third-stage adsorption tower. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0026] like Figure 1-4As shown, this utility model provides a low-cost treatment system for high-salt wastewater from the iron and steel industry, including an equalization tank 1, an electrochemical pretreatment device 2, a halophilic bioreactor 3, a catalytic Fenton oxidation reactor 4, a nanofiltration thickener 5, a seed crystallization reactor 6, an electrodialysis device 7, a multi-stage adsorption system 8, an intelligent control center, an energy recovery system, and a sludge treatment system. The outlet of the equalization tank 1 is connected to the inlet of the electrochemical pretreatment device 2 via a first connecting pipe. The outlet of the electrochemical pretreatment device 2 is connected to the inlet of the halophilic bioreactor 3 via a second connecting pipe. The outlet of the halophilic bioreactor 3 is connected to the inlet of the catalytic Fenton oxidation reactor 4 via a third connecting pipe. The outlet of the catalytic Fenton oxidation reactor 4 is connected to the inlet of the nanofiltration thickener 5 via a fourth connecting pipe. The nanofiltration thickener 5 has a concentrated water outlet and a desalinated water outlet, wherein the concentrated water outlet is connected to the seed crystallization reactor 6 and the electrodialysis device 7 respectively, and the desalinated water outlet is connected to the inlet of the multi-stage adsorption system 8.

[0027] The electrochemical pretreatment device 2 includes an electrolytic cell body 21, an iron scrap anode 22, a stainless steel cathode 23, and a DC power supply 24. The electrolytic cell body 21 contains multiple sets of parallel-arranged electrodes with a spacing of 10-20 mm, and the current density is controlled at 10-20 mA / cm². The iron scrap anode 22 is made from scrap iron from a steel plant through pressing and molding, possessing a high specific surface area and good conductivity. During electrolysis, the iron scrap anode 22 continuously dissolves to produce Fe. 2+ At the same time, OH is generated at the cathode. - This forms in-situ generated FeOH2 and FeOH3 flocculants, which effectively remove suspended solids and some organic matter from wastewater.

[0028] The halophilic bioreactor 3 adopts an upflow anaerobic sludge bed structure, internally filled with a biological carrier made of modified polyurethane foam with a specific surface area of ​​1500 m² / m³. The reactor is inoculated with acclimatized halophilic bacteria, mainly including *Halomonas* and *Halobacter* species, capable of normal growth and metabolism under salinity conditions of 3-8%. A water distributor is installed at the bottom of the reactor to ensure uniform influent distribution; a three-phase separator is installed at the top to achieve effective separation of gas, liquid, and solid phases. The reactor operating temperature is controlled at 30-35℃, the hydraulic retention time is 4-6 hours, and the dissolved oxygen is controlled at 2-4 mg / L.

[0029] The catalytic Fenton oxidation reactor 4 is an innovative photo-electric-Fenton coupled reaction system, comprising a reactor body 41, a UV-LED light source system 42, a magnetic catalyst dosing system 43, and an iron-carbon micro-electrolysis packing layer 44. The reactor body 41 is made of corrosion-resistant fiberglass, with its inner wall coated with a titanium dioxide photocatalytic coating. The UV-LED light source system 42 uses high-efficiency LED lamps with a wavelength of 365nm and a power density of 20-30W / m³. The lamps are protected by quartz sleeves and can be cleaned online. The catalyst in the magnetic catalyst dosing system 43 is nano-Fe3O4 extracted from steel slag, with a particle size of 50-100nm, and a dosage of 0.5-1.0g / L. After the reaction, it can be recovered and reused through magnetic separation. The iron-carbon micro-electrolysis packing layer 44 is made by mixing and pressing iron filings and activated carbon in a 3:1 mass ratio, with a filling height of 1 / 3 of the reactor height.

[0030] Nanofiltration concentration unit 5 employs a spiral wound nanofiltration membrane module made of polyamide composite membrane with a molecular weight cutoff of 200-400 Da. It exhibits a rejection rate of >95% for divalent ions and <20% for monovalent ions. The operating pressure is controlled at 1.5-2.5 MPa, and the recovery rate is set at 75-80%. The unit is equipped with an automatic backwashing system, performing backwashing every 4 hours of operation to effectively prevent membrane fouling.

[0031] The seed crystallization reactor 6 is specifically designed for treating high-concentration fluoride wastewater, employing a fluidized bed crystallization process. A seed inlet is located at the bottom of the reactor, where calcium fluoride seed crystals with a particle size of 0.1-0.3 mm are added at a rate of 5-10% of the theoretical yield. The reactor is equipped with a stirring device, with the rotation speed controlled at 100-150 rpm to ensure uniform suspension of the seed crystals. By precisely controlling the pH value between 8.5-9.5 and the supersaturation between 1.2-1.5, fluoride ions are directionally grown on the seed crystal surface, forming calcium fluoride particles with a particle size of 1-3 mm, which can be recovered as a raw material for fluorochemicals.

[0032] Electrodialysis units are used for the selective removal of chloride ions, employing heterogeneous membrane electrodialysis technology. The anion exchange membrane is used for chloride ion removal. - The selective permeability coefficient is >0.9. The electrodialysis membrane stack consists of 100-150 membrane pairs, with an effective membrane area of ​​0.2 m² / pair. The operating current density is 30-50 A / m², and the dechlorination rate can reach over 90%. The high-concentration sodium chloride solution produced in the concentration chamber can be evaporated and crystallized to obtain industrial-grade sodium chloride product.

[0033] The multi-stage adsorption system 8 comprises three adsorption towers connected in series. The first-stage adsorption tower 81 is filled with modified steel slag adsorbent, primarily removing heavy metal ions. The second-stage adsorption tower 82 is filled with biochar adsorbent, which is produced by co-pyrolysis of coke powder and residual sludge at 600℃, possessing a specific surface area of ​​800 m² / g, primarily adsorbing residual organic matter. The third-stage adsorption tower 83 is filled with 13X molecular sieves, selectively adsorbing residual inorganic ions. Each adsorption tower is equipped with an online regeneration system: the first stage uses acid washing for regeneration, the second stage uses thermal desorption combined with ozone oxidation for regeneration, and the third stage uses thermal regeneration. The adsorption system employs a dual-tower switching operation mode to ensure continuous processing.

[0034] The intelligent control center employs a deep learning-based AI predictive control system, comprising a data acquisition module, a predictive analysis module, and an automatic control module. The data acquisition module monitors in real-time parameters such as influent COD, salinity, pH, and temperature, as well as the operating status of each treatment unit. The predictive analysis module, based on historical and real-time data, uses an LSTM neural network model to predict the optimal reagent dosage and operating parameters. Based on the prediction results, the automatic control module automatically adjusts the operating parameters of each unit via a PLC system, including current density, aeration rate, and reagent dosage, achieving intelligent control throughout the entire process.

[0035] The energy recovery system comprises a waste heat recovery unit, a biogas power generation unit, and a photovoltaic power generation system. The waste heat recovery unit collects the heat generated by the Fenton reaction and transfers it to the sludge drying system via a heat exchanger, reducing the sludge moisture content from 80% to 40%. The biogas power generation unit collects biogas produced by the halophilic bioreactor, purifies it, and then feeds it into a biogas generator set, generating 30-50 kW of electricity. The photovoltaic power generation system utilizes monocrystalline silicon photovoltaic panels installed on the plant roof, with an installed capacity of 200 kW and an annual power generation of approximately 200,000 kWh. The three energy recovery systems operate in tandem, meeting more than 60% of the entire treatment system's electricity needs.

[0036] Example 1

[0037] A steel plant is treating reverse osmosis concentrate with a treatment capacity of 500 m³ / d. The influent water quality is as follows: COD 800 mg / L, TDS 25000 mg / L, fluoride 150 mg / L, chloride 8000 mg / L, pH 6.5.

[0038] The treatment process is as follows: High-salinity wastewater first enters a 100m³ equalization tank 1, which is equipped with perforated aeration pipes for pre-aeration. Simultaneously, sodium hydroxide is added to adjust the pH to 7.0-7.5. The effluent from the equalization tank is then pumped into an electrochemical pretreatment unit 2. This unit has an effective volume of 20m³ and contains 50 sets of iron scrap anode plates and stainless steel cathode plates. The plate dimensions are 1000mm × 800mm × 10mm, and it is powered by a 15V, 500A DC power supply. Under a current density of 15mA / cm², the wastewater residence time in the electrolytic cell is 40 minutes, achieving a suspended solids removal rate of 85% and a COD removal rate of 30% in the effluent.

[0039] The pretreated wastewater from the electrochemical process enters halophilic bioreactor 3, which has a diameter of 3m, a height of 6m, and an effective volume of 35m³. The reactor is filled with 15m³ of modified polyurethane foam carrier and inoculated with acclimatized halophilic bacteria, maintaining a sludge concentration of 8-10g / L. Oxygen is supplied through a bottom-mounted microporous aeration system, controlling dissolved oxygen at 2.5-3.5mg / L, while the temperature is maintained at 32±2℃ via a jacketed heating system. Under a 5-hour heating time (HRT), the COD removal rate reaches 65%, with the effluent COD reduced to approximately 200mg / L.

[0040] The biologically treated effluent enters the catalytic Fenton oxidation reactor 4, which has an effective volume of 25 m³ and is equipped with 12 sets of 365 nm UV-LED lamps with a total power of 600 W. First, 0.8 g / L of nano-Fe3O4 catalyst is added, followed by 30% hydrogen peroxide at a COD:H2O2 ratio of 1:1. Under conditions of pH 3.0 and a reaction time of 60 minutes, the COD removal rate reaches 90%, with effluent COD <20 mg / L. After the reaction, over 95% of the Fe3O4 catalyst is recovered using a magnetic separation device.

[0041] After pH adjustment, the Fenton oxidation effluent enters nanofiltration concentration unit 5, which is equipped with four 8-inch spiral wound nanofiltration membrane elements with a total membrane area of ​​120 m². Under operating conditions of 2.0 MPa and an influent flow rate of 25 m³ / h, the permeate yield is 75%, and the concentrate TDS reaches 80,000 mg / L, with a fluoride concentration of 500 mg / L, requiring further treatment.

[0042] High-fluoride concentrated water enters seed crystallization reactor 6, with a reactor volume of 8 m³. First, 50 kg of calcium fluoride seed crystals with a particle size of 0.2 mm are added, followed by the addition of calcium chloride to achieve a Ca / F molar ratio of 1.2:1. The pH is controlled at 9.0 by adding sodium hydroxide. Under conditions of a stirring speed of 120 rpm and a reaction time of 2 hours, the fluoride removal rate reaches 95%, the fluoride content in the effluent is <10 mg / L, and the average particle size of the produced calcium fluoride crystals reaches 2 mm with a purity >95%.

[0043] The concentrated water containing high levels of chloride enters electrodialysis unit 7, which is equipped with 120 pairs of heterogeneous ion exchange membranes. Operating at a current density of 40 A / m², it achieves a chloride ion removal rate of 92%, reducing the chloride concentration in the desalination chamber effluent to below 600 mg / L. The 20% sodium chloride solution produced in the concentration chamber is sent to the evaporation and crystallization system, which can recover approximately 15 tons of industrial salt per day.

[0044] The desalination-treated wastewater finally enters the multi-stage adsorption system 8 for further treatment. The first stage is filled with 5 m³ of modified steel slag to remove residual heavy metal ions; the second stage is filled with 3 m³ of biochar to further remove organic matter; and the third stage is filled with 2 m³ of 13X molecular sieve to remove residual ions. The final effluent has a COD of <10 mg / L and a TDS of <500 mg / L, fully meeting the standards for reused water.

[0045] The entire treatment process is monitored and scheduled by the intelligent control center. The system automatically adjusts the operating parameters of each unit according to changes in the influent water quality. In the energy recovery system, the waste heat recovery device can recover 2.5 GJ of heat per day for sludge drying; the biogas generator set generates approximately 800 kWh of electricity per day; and the photovoltaic system generates an average of 550 kWh of electricity per day. These three components together provide 65% of the system's total energy consumption.

[0046] The results show that the direct operating cost of the system for treating each ton of high-salt wastewater is only 12.5 yuan, which is more than 60% cheaper than the traditional evaporation and crystallization process. It also achieves resource recovery of salt and water, and has significant economic and environmental benefits.

[0047] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A low-cost treatment system for high-salinity wastewater from the iron and steel industry, characterized in that, The system includes, in sequence, an equalization tank (1), an electrochemical pretreatment device (2), a halophilic bioreactor (3), a catalytic Fenton oxidation reactor (4), a nanofiltration thickener (5), a seed crystallization reactor (6), an electrodialysis device (7), a multi-stage adsorption system (8), an intelligent control center, an energy recovery system, and a sludge treatment system; the nanofiltration thickener (5) is provided with a concentrated water outlet and a fresh water outlet, the concentrated water outlet is connected to the seed crystallization reactor (6) and the electrodialysis device (7) respectively, and the fresh water outlet is connected to the inlet of the multi-stage adsorption system (8).

2. The low-cost treatment system for high-salinity wastewater from the steel industry according to claim 1, characterized in that, The electrochemical pretreatment device (2) includes an electrolytic cell body (21), an iron scrap anode (22), a stainless steel cathode (23), and a DC power supply (24). The iron scrap anode (22) is made by pressing and molding waste iron scrap from a steel plant. The electrolytic cell body (21) is equipped with multiple sets of parallel plates with a plate spacing of 10-20 mm and a current density of 10-20 mA / cm².

3. The low-cost treatment system for high-salinity wastewater from the steel industry according to claim 1, characterized in that, The halophilic bioreactor (3) adopts an upflow anaerobic sludge bed structure, and is filled with a modified polyurethane foam biological carrier with a specific surface area of ​​1500 m² / m³. A water distributor is provided at the bottom of the reactor and a three-phase separator is provided at the top. The reactor is inoculated with halophilic bacteria of the genera *Haloxylon* and *Haloxybacterium*.

4. The low-cost treatment system for high-salinity wastewater from the iron and steel industry according to claim 1, characterized in that, The catalytic Fenton oxidation reactor (4) includes a reactor body (41), a UV-LED light source system (42), a magnetic catalyst dosing system (43), and an iron-carbon micro-electrolysis packing layer (44). The UV-LED light source system (42) uses an LED lamp group with a wavelength of 365nm and a power density of 20-30W / m³. The magnetic catalyst is nano Fe3O4 with a particle size of 50-100nm and a dosing amount of 0.5-1.0g / L. The iron-carbon micro-electrolysis packing layer (44) is made by mixing and pressing iron filings and activated carbon in a mass ratio of 3:

1.

5. A low-cost treatment system for high-salinity wastewater from the steel industry according to claim 1, characterized in that, The nanofiltration concentration device (5) uses a polyamide composite membrane with a molecular weight cutoff of 200-400 Da, achieving a rejection rate of >95% for divalent ions and <20% for monovalent ions; the seed crystallization reactor (6) has a seed inlet at the bottom for adding calcium fluoride seed crystals with a particle size of 0.1-0.3 mm; the electrodialysis device (7) uses heterogeneous membrane electrodialysis technology, with the anion exchange membrane for Cl... - The selective transmittance coefficient is >0.

9.

6. A low-cost treatment system for high-salinity wastewater from the steel industry according to claim 1, characterized in that, The multi-stage adsorption system (8) includes three adsorption towers connected in series: the first-stage adsorption tower (81) is filled with modified steel slag adsorbent, the second-stage adsorption tower (82) is filled with biochar adsorbent obtained by co-pyrolysis of coke powder and residual sludge at 600°C, and the third-stage adsorption tower (83) is filled with 13X molecular sieve; each adsorption tower is equipped with an online regeneration system.

7. A low-cost treatment system for high-salinity wastewater from the steel industry according to claim 1, characterized in that, The intelligent control center includes a data acquisition module, a predictive analysis module, and an automatic control module; the predictive analysis module uses an LSTM neural network model to predict the dosage of the reagent and operating parameters.

8. A low-cost treatment system for high-salinity wastewater from the steel industry according to claim 1, characterized in that, The energy recovery system includes a waste heat recovery device, a biogas power generation device and a photovoltaic power generation system. The waste heat recovery device collects the reaction heat of the catalytic Fenton oxidation reactor (4) for sludge drying, and the biogas power generation device collects the biogas produced by the halophilic bioreactor (3) for power generation.

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