Capacitive deionization-oxidation coupled process for treating high-salinity industrial wastewater

Abstract

The present application relates to wastewater treatment method, especially to the capacitive deionization-oxidation coupling high-salt industrial wastewater treatment process, comprising the following steps: first microfiltration removes suspended solids and adjusts pH, then low-voltage electric adsorption desalination is carried out through modified capacitive deionization unit, the electric energy released in the regeneration stage is collected, is converted into the electric energy of catalytic oxidation unit through the converter, the desalted water enters the non-free radical catalytic oxidation unit, UV-LED excitation catalyst activates persulfate, generates singlet oxygen and degrades organic matter, the intelligent control system dynamically adjusts voltage, medicament and energy distribution according to the water inlet condition, finally, the capacitive deionization regeneration liquid is concentrated and crystallized through multistage membrane, and salt product is recovered, realizing wastewater treatment and resource utilization.

Description

TECHNICAL FIELD

[0001] The present application relates to an industrial wastewater treatment method, in particular to a capacitive deionization-oxidation coupled high-salinity industrial wastewater treatment process, and belongs to the technical field of industrial wastewater treatment. The present application solves the complex treatment problem of the coexistence of refractory organic matter and high-concentration salt in high-salinity industrial wastewater, and realizes the synergistic treatment goal of efficient salt recovery and efficient organic matter degradation. BACKGROUND

[0002] High-salinity industrial wastewater refers to industrial production wastewater with a salt content higher than 10,000 mg / L, mainly from petroleum chemical industry, coal chemical industry, pharmaceutical industry, dyeing industry, coking industry, etc. Such wastewater not only contains high-concentration salt, but also contains a large amount of refractory organic matter, especially humic acid and fulvic acid substances in the effluent after biochemical treatment. These substances, as typical free radical quenchers, greatly reduce the reaction efficiency of traditional oxidation processes.

[0003] At present, the treatment technologies for high-salinity industrial wastewater mainly include evaporation crystallization method, membrane treatment method, electrodialysis method and ion exchange method, etc. Among them, the evaporation crystallization method has good treatment effect, but the energy consumption is huge and the treatment cost is high; the membrane treatment method faces serious membrane pollution and scaling problems; the electrodialysis method has high energy consumption and strict requirements for pretreatment; the ion exchange method has a complex regeneration process and produces secondary pollution. These technologies are difficult to simultaneously and efficiently remove salt and organic matter in wastewater.

[0004] Through retrieval, the closest comparison file to the present application is found as follows:

[0005] 1. "Treatment of industrial brine using capacitive deionization (CDI) toward zero liquid discharge-challenges and optimization" (Water Research, 2020) studies the feasibility of CDI technology in treating industrial salt water, mainly focusing on electrode material and operation parameter optimization, but does not solve the problem of organic matter pollution of the electrode, and does not involve energy recovery system and organic matter synergistic treatment.

[0006] 2. "Flow Electrode Capacitive Deionization (FCDI): Recent Developments, Environmental Applications, and Future Perspectives" (Environmental Science & Technology, 2021) reviews the application prospects of FCDI technology in the environmental field, and proposes the possibility of treating high-salinity wastewater, but does not solve the problems of organic pollution and energy recovery.

[0007] 3. "Singlet oxygen-dominated non-radical oxidation process for efficient degradation of bisphenol A under high salinity condition" (Water Research, 2018) proposes a non-radical oxidation pathway based on singlet oxygen in high-salinity environments, but does not combine it with CDI technology and does not consider the design of an energy recovery system.

[0008] 4. "Mechanisms of Humic Acid Fouling on Capacitive and Insertion Electrodes for Electrochemical Desalination" (Environmental Science & Technology, 2018) studies the fouling mechanism of humic acid on CDI electrodes, but does not provide an effective anti-fouling solution.

[0009] 5. "Capacitive deionized hybrid systems for wastewater treatment and desalination: A review on synergistic effects, mechanisms and challenges" (Chemical Engineering Journal, 2020) reviews the application of CDI hybrid systems in wastewater treatment, but lacks details on the implementation of non-radical oxidation pathways and the design of energy recovery systems.

[0010] The prior art has the following problems in treating high-salinity industrial wastewater: 1. The electrodes are easily contaminated by organic matter, resulting in reduced desalination efficiency and shortened service life; 2. The traditional oxidation process has low efficiency in a high-salinity environment; 3. The energy consumption is high, and there is a lack of effective energy recovery and utilization system; and 4. The simultaneous and efficient removal of salt and organic matter cannot be achieved.

[0011] Therefore, there is an urgent need for a treatment process that can simultaneously and efficiently remove salt and organic matter from high-salinity industrial wastewater, has anti-pollution ability, and has low energy consumption, which is the technical problem to be solved by the present application. SUMMARY

[0012] The present application aims to provide a capacitive deionization-oxidation coupled high-salinity industrial wastewater treatment process to solve the problems in the prior art, and in particular to achieve the following technical objectives: simultaneous and efficient removal of salt and refractory organic matter from wastewater; salt recovery rate of more than 80%; treatment cost reduced by more than 50% compared with traditional evaporation method; solving the problem of electrode contamination by organic matter in traditional CDI systems; significantly reducing overall energy consumption through an energy recovery system.

[0013] To achieve the above-mentioned purpose, the present application provides a capacitive deionization-oxidation coupled high-salinity industrial wastewater treatment process, comprising the following steps:

[0014] (1) removing suspended solids from high-salinity industrial wastewater by microfiltration and adjusting the pH to 6.5-7.5;

[0015] (2) introducing the pretreated wastewater into a modified capacitive deionization unit to remove salt through an electric adsorption process at a low voltage of 0.8-1.2 V;

[0016] (3) collecting the electrical energy released by the capacitive deionization unit during the regeneration stage through an energy recovery system;

[0017] (4) converting the recovered energy into the required form of electrical energy for the catalytic oxidation unit through a bidirectional DC-DC converter;

[0018] (5) introducing the desalted water into a non-free radical catalytic oxidation unit, exciting the Fe / N co-doped g-C3N4 catalyst through a UV-LED light source, activating the persulfate, and generating non-free radical active substances dominated by singlet oxygen to degrade organic pollutants;

[0019] (6) dynamically adjusting the capacitive deionization voltage, the catalytic oxidation agent dosage, and the energy distribution ratio through an intelligent control system according to the salinity and organic matter concentration of the influent;

[0020] (7) introducing the capacitive deionization regeneration liquid into a multi-stage membrane concentration system and a crystallization process to recover salt products.

[0021] Preferably, in an embodiment of the present application, the modified capacitive deionization unit adopts activated carbon fiber electrodes coated with polyethyleneimine and nano-TiO2 composite coatings, the polyethyleneimine coating thickness is 20-50 nanometers, the TiO2 nanoparticle size is 5-20 nanometers, and the loading is 0.5-2.0 milligrams per square centimeter.

[0022] Further, the non-radical catalytic oxidation unit adopts Fe / N co-doped g-C3N4 nanosheet catalyst, the Fe content is 1.5-3.0 percent by weight, the N content is 30-40 percent by weight, the catalyst is loaded on a porous SiC carrier, and the catalyst dosage is 2.0-5.0 grams per liter.

[0023] In another embodiment of the present application, the energy recovery system includes a supercapacitor energy storage module, a bidirectional DC-DC converter, and an energy management control system, the bidirectional DC-DC converter is based on topology, the input voltage range is 0.8-1.5 volts, the output voltage range is 3.0-12.0 volts, and the conversion efficiency is 90-95%.

[0024] Preferably, the capacitive deionization unit operating parameters are adjusted as follows with the influent salinity: when the influent total dissolved solids concentration is less than 10,000 milligrams per liter, the voltage is 0.8 volts, and the adsorption time is 10-15 minutes; when the influent total dissolved solids concentration is 10,000-30,000 milligrams per liter, the voltage is 1.0 volt, and the adsorption time is 15-25 minutes; and when the influent total dissolved solids concentration is greater than 30,000 milligrams per liter, the voltage is 1.2 volts, and the adsorption time is 25-30 minutes.

[0025] In addition, the catalytic oxidation unit operating parameters are adjusted as follows with the influent organic matter concentration: when the influent total organic carbon concentration is less than 200 milligrams per liter, the catalyst dosage is 2.0 grams per liter, the persulfate dosage is 0.5 grams per liter, and the reaction time is 30 minutes; when the influent total organic carbon concentration is 200-500 milligrams per liter, the catalyst dosage is 3.0 grams per liter, the persulfate dosage is 1.0 grams per liter, and the reaction time is 45 minutes; and when the influent total organic carbon concentration is greater than 500 milligrams per liter, the catalyst dosage is 4.0 grams per liter, the persulfate dosage is 2.0 grams per liter, and the reaction time is 60 minutes.

[0026] Further, the preparation method of the Fe / N-g-C3N4 catalyst is as follows: melamine and urea are mixed uniformly at a weight ratio of 5:1; 0.1 mol / L FeCl3·6H2O aqueous solution is added to the mixture, so that the iron element accounts for 1.5-3.0 weight percent of the final product; the mixture is dried at 80℃ for 12 hours; the temperature is raised to 550℃ at a rate of 2℃ / min under N2 atmosphere and kept for 4 hours; the obtained product is washed with 3 mol / L hydrochloric acid and then washed with deionized water until neutral; and the Fe / N-g-C3N4 catalyst is obtained by drying at 80℃ for 12 hours.

[0027] Meanwhile, the preparation method of the modified electrode is as follows: the activated carbon fiber is soaked in 6 mol / L hydrochloric acid for 12 hours, washed to neutral and dried; the pretreated activated carbon fiber is soaked in a 3 weight percent polyethyleneimine aqueous solution for 24 hours; after ultrasonic treatment for 15 minutes, the activated carbon fiber is dried at 60℃ for 8 hours; TiO2 nanoparticles are prepared by a sol-gel method and dispersed in anhydrous ethanol; the TiO2 nanoparticles are loaded on the surface of the polyethyleneimine coating by an immersion-spin coating method; and the composite coating modified electrode is obtained by drying at 60℃ for 4 hours.

[0028] In the preferred embodiment of the present application, the energy management system dynamically adjusts the energy distribution ratio according to the water quality characteristics: in high-salt low-organic matter wastewater, the energy consumption of the capacitive deionization unit accounts for 70% of the total energy consumption, and the energy consumption of the catalytic oxidation unit accounts for 30%; in low-salt high-organic matter wastewater, the energy consumption of the capacitive deionization unit accounts for 40% of the total energy consumption, and the energy consumption of the catalytic oxidation unit accounts for 60%; and the energy recovery system preferentially provides energy for the catalytic oxidation unit, and the insufficient part is supplemented by the power grid.

[0029] On the other hand, the control system of the process includes a multi-parameter real-time monitoring module and a deep reinforcement learning-based control algorithm, the multi-parameter real-time monitoring module includes a conductivity sensor, a total organic carbon online analyzer, a UV-Vis spectrum analyzer and a redox potential sensor, and the control algorithm dynamically adjusts the capacitive deionization voltage, the adsorption / regeneration time, the catalyst and oxidant dosage and the energy distribution ratio according to the real-time water quality data, so as to maximize the treatment effect and minimize the energy consumption.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] 1. The pollution problem of organic matter to the CDI electrode is solved by the innovative anti-pollution electrode design, the service life of the electrode is prolonged, and the high-efficiency desalination performance is maintained;

[0032] 2. The non-free radical catalytic oxidation path is adopted, and the problem of low efficiency of free radical oxidation in a high-salt environment is effectively solved;

[0033] 3. Introducing energy recovery system, using the electrical energy released in CDI regeneration stage for catalytic oxidation process, greatly reducing the overall energy consumption;

[0034] 4. Through intelligent control system, real-time response to water quality changes is realized, treatment parameters are optimized, and treatment efficiency is improved;

[0035] 5. Simultaneous and efficient removal of salt and organic matter is realized, salt recovery rate is more than 80%, and organic matter removal rate is more than 90%;

[0036] 6. The treatment cost is reduced by more than 50% compared with traditional evaporation method, which has significant economic and environmental benefits. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the present application, the following will be described in detail with reference to the drawings, in which:

[0038] Figure 1 is the overall structure schematic diagram of the capacitive deionization-oxidation coupled high-salt industrial wastewater treatment system of the present application;

[0039] Figure 2 is the structure schematic diagram of the anti-pollution electrode in the present application;

[0040] Figure 3 is the structure schematic diagram of the energy recovery system in the present application;

[0041] Figure 4 is the salt removal rate comparison chart of the present application for treating different types of high-salt industrial wastewater;

[0042] Figure 5 is the organic matter removal rate comparison chart of the present application for treating different types of high-salt industrial wastewater;

[0043] Figure 6 is the energy recovery efficiency comparison chart of the present application with the energy consumption of traditional process;

[0044] Figure 7 is the electrode service life test result chart, showing the performance decay curve of modified electrode and unmodified electrode in organic matter-containing high-salt wastewater. DETAILED DESCRIPTION

[0045] The present application will be further described in detail below in combination with the drawings and examples. Those skilled in the art should understand that these examples are only used to illustrate the present application and should not be understood as limiting the present application. Based on the examples in the present application, all other examples obtained by those skilled in the art without departing from the scope of the present application belong to the scope of protection of the present application. Figures 1-7 The present application will be further described in detail below in combination with the drawings and examples. Those skilled in the art should understand that these examples are only used to illustrate the present application and should not be understood as limiting the present application. Based on the examples in the present application, all other examples obtained by those skilled in the art without departing from the scope of the present application belong to the scope of protection of the present application.

[0046] Reference Signs List Figure 1The application provides a capacitive deionization-oxidation coupled high-salinity industrial wastewater treatment system, which mainly comprises six functional units: a water inlet system, a modified capacitive deionization (CDI) unit, an energy recovery system, a non-radical catalytic oxidation unit, an intelligent control system and a salt recovery unit.

[0047] The water inlet system comprises a water inlet pump, a microfilter, a pH adjusting device and a flow meter. The high-salinity industrial wastewater is first subjected to microfiltration to remove suspended solids, so as to prevent the subsequent treatment units from being blocked, and then subjected to pH adjustment by the pH adjusting device to a pH range of 6.5-7.5, so as to improve the subsequent treatment efficiency.

[0048] The modified CDI unit is one of the core treatment units of the application, which adopts activated carbon fiber (ACF) electrodes coated with polyethyleneimine (PEI) and nano-TiO2 composite coating, and is configured with ion exchange membrane (IEM) to form a membrane capacitive deionization (MCDI) configuration. Preferably, a conductive polymer spacer is arranged between the electrodes to improve the ion transmission efficiency. The unit removes ionic substances in water through an electric adsorption process at a low voltage of 0.8-1.2 V.

[0049] The energy recovery system is one of the innovative highlights of the application, which comprises a supercapacitor energy storage module, a bidirectional DC-DC converter and an energy management control system. The system can collect the electric energy released during the CDI regeneration stage, and convert it into the form of electric energy required by the catalytic oxidation unit through the bidirectional DC-DC converter, so as to realize efficient utilization of energy and significantly reduce the overall energy consumption.

[0050] The non-radical catalytic oxidation unit adopts Fe / N co-doped g-C3N4 nanosheet catalyst to generate non-radical active substances mainly in the form of singlet oxygen (1O2). Preferably, the catalyst is loaded on a porous SiC carrier, and a UV-LED light source system and a persulfate (PS) oxidant dosing system are integrated. The unit can efficiently degrade refractory organic matter in the desalinated water, especially humic acid and fulvic acid substances.

[0051] The intelligent control system comprises a multi-parameter online monitoring system and a control algorithm based on deep reinforcement learning. According to real-time water quality data, the system dynamically adjusts the CDI voltage, adsorption / regeneration time, catalyst and oxidant dosage and energy distribution ratio, so as to maximize the treatment effect and minimize the energy consumption.

[0052] The salt recovery unit is composed of a multi-stage membrane concentration system and a crystallization device, which is used for concentrating and recovering the salt in the CDI regeneration liquid into solid salt products, so as to realize resource utilization.

[0053] The workflow of the whole system is as follows: the high-salinity industrial wastewater is pretreated and then enters the modified CDI unit for desalination; during the desalination process, the electrode adsorbs salt until saturation; then, the CDI unit switches to the regeneration mode, and the released electrical energy is collected by the energy recovery system; the desalinated water enters the non-free radical catalytic oxidation unit for treatment of organic pollutants; the CDI regeneration liquid enters the salt recovery unit to recover salt products; the whole process is monitored and optimized in real time by the intelligent control system to maximize the treatment effect and energy efficiency.

[0054] The anti-pollution electrode in the application is the key to solving the problem of organic pollution of the CDI electrode. The preparation process of the modified electrode is as follows:

[0055] Firstly, the commercial activated carbon fiber (ACF) is soaked in 6 mol / L hydrochloric acid for 12 hours to remove metal impurities and activate the surface. The selection of ACF is very important, and high specific surface area ACF with a specific surface area greater than 2000 square meters per gram is preferably used, such as FR-20 type activated carbon fiber produced by Japan Kureha Corporation or Kusano series activated carbon fiber of Japan Toyo Soda Industrial Co., Ltd. After soaking, wash repeatedly with deionized water until neutral, and dry at 80°C for 24 hours. Then, heat treatment at 500°C for 2 hours under nitrogen atmosphere to further activate the electrode surface.

[0056] Secondly, a 3 wt% polyethyleneimine (PEI) aqueous solution is prepared, and PEI is preferably a branched PEI with a molecular weight of about 25,000, such as the product of Sigma-Aldrich Company. The pretreated ACF is soaked in the PEI solution for 24 hours and subjected to ultrasonic treatment for 15 minutes to promote uniform distribution of PEI on the surface of the ACF. Then, the soaked ACF is dried at 60°C for 8 hours to form a PEI coating.

[0057] Then, TiO2 nanoparticles are prepared by sol-gel method. The specific steps are as follows: 10 ml of tetrabutyl titanate (TBOT) is dissolved in 40 ml of anhydrous ethanol; under vigorous stirring, 20 ml of water-ethanol mixed solution (volume ratio 1:4) containing 0.5 ml of concentrated nitric acid is added dropwise; room temperature aging for 24 hours to form a transparent sol; the sol is dried at 80°C for 12 hours to obtain a gel; finally, calcination at 450°C for 4 hours to obtain anatase TiO2 nanoparticles with a particle size of 5-20 nm.

[0058] Next, the prepared TiO2 nanoparticles were dispersed in anhydrous ethanol to prepare a dispersion solution with a concentration of 10 mg / mL. The TiO2 nanoparticles were uniformly loaded on the surface of the PEI coating by using the dip-spin coating method at a rotation speed of 2000 rpm for 30 seconds. The loading amount of TiO2 was controlled in the range of 0.5-2.0 mg / cm2, preferably 1.0-1.5 mg / cm2. Finally, the PEI / TiO2 composite coating modified electrode was dried at 60°C for 4 hours.

[0059] To assemble the CDI electrode, the modified ACF was cut to the required size (usually 10 cm x 10 cm) and was connected to the titanium mesh current collector by pressing. A conductive polymer spacer with a thickness of 250 microns was placed between the electrodes. Preferably, the edges were sealed with epoxy to prevent short circuits.

[0060] The design principle of this modified electrode is that the PEI coating has a positive charge under neutral and weak alkaline conditions, which produces electrostatic repulsion to the negatively charged humic acid and fulvic acid. At the same time, the TiO2 nanoparticles provide a highly hydrophilic surface to form a hydration layer, which blocks the contact of hydrophobic organic pollutants with the electrode surface. This dual protection mechanism enables the modified electrode to exhibit excellent anti-pollution performance and long-term stability in high-salinity wastewater containing organic matter.

[0061] Non-radical catalytic oxidation is another core technology of the present application, and the key lies in the preparation of the Fe / N co-doped g-C3N4 nanosheet catalyst. This catalyst can produce non-radical active substances dominated by singlet oxygen (1O2), which maintains high oxidation efficiency in a high-salt environment. The specific preparation process is as follows:

[0062] First, 10 grams of melamine and 2 grams of urea were mixed uniformly. This ratio (5:1) has been proven by multiple experiments to produce the best catalytic activity. Then, 0.5 grams of FeCl3·6H2O was dissolved in 5 milliliters of 0.1 mol / L aqueous solution, and the mixture was thoroughly stirred and then dried at 80°C for 12 hours to form a precursor mixture.

[0063] Secondly, the dried precursor was placed in an alumina crucible and put into a tube furnace. Under a nitrogen atmosphere, the temperature was raised to 550°C at a rate of 2°C / min and maintained for 4 hours. This heat treatment process promotes the thermal polymerization of melamine to form a g-C3N4 structure, and iron ions are doped into the skeleton of g-C3N4. After the heat treatment was completed, it was naturally cooled to room temperature.

[0064] Subsequently, the resulting product was ground into fine powder, washed with 3 mol / L hydrochloric acid to remove unstable iron species, and then washed repeatedly with deionized water until neutral. Finally, it was dried at 80°C for 12 hours. This post-treatment step ensures that the iron species in the catalyst are stably present in the g-C3N4 structure.

[0065] In order to improve the dispersion and stability of the catalyst, it is necessary to be loaded on the carrier. The porous SiC is used as the carrier in the present application, and the preparation method is as follows: SiO2 and sucrose are mixed in a molar ratio of 1:3, a small amount of iron catalyst (about 1% by weight) is added, and the mixture is thoroughly ground and uniformly mixed; the mixture is placed in a graphite crucible, heated to 1400°C at a rate of 5°C / min under argon atmosphere, kept for 2 hours and then naturally cooled; the unreacted SiO2 is removed by washing with 6 mol / L hydrofluoric acid solution, the metal catalyst is removed by washing with 6 mol / L hydrochloric acid, and the washing is neutralized with deionized water and dried at 120°C for 12 hours; finally, the SiC carrier with the target particle size (300-500 microns) is obtained by grinding and sieving.

[0066] Finally, the catalyst powder is ultrasonically dispersed in ethanol and loaded on the porous SiC carrier by impregnation method, and the loading amount is 20% by weight. After drying at 120°C for 6 hours, the final supported catalyst is obtained by activating at 300°C in nitrogen for 2 hours.

[0067] The special electronic structure of the Fe / N co-doped g-C3N4 catalyst enables it to preferentially produce singlet oxygen rather than traditional hydroxyl radicals, making the catalytic oxidation process not affected by chloride ions in high-salt environments. In addition, singlet oxygen has strong selective oxidation ability to the benzene ring structure of humic acid and other organic matter, and can efficiently degrade such difficult-to-treat organic pollutants.

[0068] The energy recovery system is an important innovation of the present application, which can collect the electrical energy released during the CDI regeneration stage and convert it into the form of electrical energy required for the catalytic oxidation process, significantly reducing the overall energy consumption. The system mainly includes three parts: supercapacitor energy storage module, bidirectional DC-DC converter and energy management control system.

[0069] The supercapacitor energy storage module uses commercial supercapacitors, such as the BCAP series of Maxwell Technologies Company or the electric double-layer capacitor of Panasonic Company, with a capacity in the range of 1-5 farads and a maximum operating voltage of 2.7 volts. Preferably, multiple supercapacitors are combined in series and parallel to meet the needs of different scale systems.

[0070] The bidirectional DC-DC converter is the core of the energy recovery system, which adopts topology, with the characteristics of low ripple and high efficiency. The input voltage range of the converter is 0.8-1.5 volts (corresponding to the discharge voltage of CDI), the output voltage range is 3.0-12.0 volts (corresponding to the demand of AOP system), and the conversion efficiency reaches 90-95%. The power range of the converter is 50-500 watts, and the operating frequency is 50-100 kilohertz.

[0071] The energy management control system is based on STM32 series microcontroller or TI's MSP430 series low-power microcontroller, equipped with current, voltage sensor and temperature monitoring module. According to the characteristics of wastewater quality and treatment demand, the system dynamically adjusts the energy allocation strategy: for high salt and low organic wastewater, increase the energy allocation of CDI system; for low salt and high organic wastewater, increase the energy allocation of AOP system. In addition, through the measures of pre-charge strategy, soft switching technology and capacitor array optimization, the energy recovery efficiency is further improved.

[0072] Example 1: Treatment of petrochemical wastewater

[0073] This example is aimed at the high-salt industrial wastewater of a certain petrochemical enterprise, which has the following characteristics: total dissolved solids (TDS) concentration of 25,000 mg / L, total organic carbon (TOC) concentration of 450 mg / L, main organic pollutants are petroleum hydrocarbons, benzene series and humic acid, pH value of 7.2.

[0074] The treatment system is configured as follows: the CDI unit uses 10 pairs of modified ACF electrodes with a total electrode area of 2 square meters. The catalyst is Fe / N-g-C3N4 with a Fe content of 2.5% by weight, and the loading is 3.0 g / L. The persulfate dosage is 1.2 g / L. The energy recovery system uses a 2.5 farad super capacitor. The system is designed to handle a flow rate of 2 cubic meters per hour.

[0075] First, the PEI and TiO2 composite coating modified electrode is prepared according to the method described in section 2.1. Specifically, FR-20 type activated carbon fiber with a specific surface area of 2500 square meters per gram is selected, after acid treatment and heat activation, it is immersed in a 3% by weight PEI aqueous solution with a molecular weight of 25,000 for 24 hours. After ultrasonic treatment for 15 minutes, it is dried at 60°C for 8 hours. Then, TiO2 nanoparticles with a particle size of 15 nanometers are prepared by sol-gel method, and TiO2 is loaded on the surface of PEI coating by dip-coating method, the loading amount is controlled at 1.2 mg / cm2.

[0076] Secondly, the Fe / N-g-C3N4 catalyst is prepared according to the method described in section 2.2. Melamine and urea are mixed in a weight ratio of 5:1, FeCl3 solution is added to make the iron content reach 2.5% by weight, and the catalyst is obtained after thermal polymerization and post-treatment, and is loaded on a porous SiC carrier with a particle size of 400 microns, the loading amount is 20% by weight.

[0077] The system operating parameters are set as follows: CDI voltage 1.0 V, adsorption time 20 minutes, regeneration time 10 minutes; catalytic oxidation reaction time 45 minutes; the energy recovery system preferentially provides energy for the catalytic oxidation unit, and the insufficient part is supplemented by the power grid.

[0078] After 30 days of continuous operation test, the treatment effect is as follows: salt removal rate 92%, salt recovery rate 85%, TOC removal rate 95%, energy recovery efficiency 78%, total energy consumption 1.8 kWh / m3, saving energy 65% compared with traditional evaporation method. The modified electrode still maintains 91% of the initial salt adsorption capacity after 500 hours of operation, showing excellent anti-pollution performance.

[0079] Example 2: Treatment of high-salt wastewater in coal chemical industry

[0080] This example is aimed at the high-salt wastewater of a coal chemical enterprise, which has the following characteristics: TDS concentration 45,000 mg / L, TOC concentration 680 mg / L, main pollutants are phenols, heterocyclic compounds and humic acid, pH value 6.8.

[0081] The treatment system is configured as follows: the CDI unit uses 15 pairs of modified ACF electrodes, with a total electrode area of 3 square meters. The catalyst is Fe / N-g-C3N4 with a Fe content of 3.0 wt%, and the loading is 4.0 g / L. The persulfate dosage is 1.5 g / L. The energy recovery system uses a 4.0 farad super capacitor. The system treatment flow is 1.5 m3 / h.

[0082] The modified electrode is prepared by the same method as in Example 1, but the TiO2 loading is increased to 1.5 mg / cm2 to enhance the anti-pollution ability. In the catalyst preparation, the iron content is increased to 3.0 wt% to cope with higher concentrations of organic pollutants.

[0083] The system operation parameters are set as follows: CDI voltage 1.2 V, adsorption time 25 minutes, regeneration time 12 minutes; catalytic oxidation reaction time 55 minutes; energy distribution ratio is dynamically adjusted according to water quality characteristics, initially set to CDI 60% and AOP 40%.

[0084] After continuous operation test, the treatment effect is as follows: salt removal rate 88%, salt recovery rate 82%, TOC removal rate 93%, energy recovery efficiency 75%, total energy consumption 2.2 kWh / m3, saving energy 58% compared with traditional evaporation method. It is worth noting that even under such high salinity conditions, the non-radical oxidation path still shows good organic matter degradation efficiency, verifying the technical advantage of the present application.

[0085] Example 3: Treatment of high-salt wastewater in printing and dyeing industry

[0086] This example is aimed at the high-salt wastewater of a printing and dyeing enterprise, which has the following characteristics: TDS concentration 15,000 mg / L, TOC concentration 350 mg / L, main pollutants are dyes, surfactants and humic acid, pH value 8.5.

[0087] The processing system is configured as follows: the CDI unit uses 8 pairs of modified ACF electrodes with a total electrode area of 1.5 square meters. The catalyst selected is Fe / N-g-C3N4 with a Fe content of 2.0% by weight, and the loading is 2.5 g / L. The persulfate dosage is 0.8 g / L. The energy recovery system uses a 2.0 farad super capacitor. The system processing flow rate is 2.5 cubic meters / hour.

[0088] In this embodiment, due to the large size of the dye molecules and the presence of charged groups in the printing and dyeing wastewater, the thickness of the PEI coating of the modified electrode is increased to 40 nanometers to enhance the electrostatic repulsion effect. The particle size of the TiO2 nanoparticles is controlled in the range of 5-10 nanometers to improve the specific surface area and hydrophilicity.

[0089] The system operating parameters are set as follows: CDI voltage 0.9 volts, adsorption time 15 minutes, regeneration time 8 minutes; catalytic oxidation reaction time 35 minutes; initial energy distribution ratio set as CDI 50% and AOP 50%, adjusted by the intelligent control system according to real-time water quality data.

[0090] After continuous operation test, the treatment effect is as follows: salt removal rate 95%, salt recovery rate 88%, TOC removal rate 97%, energy recovery efficiency 82%, total energy consumption 1.5 kWh / m3, saving energy by 72% compared with traditional evaporation method. Especially worth mentioning is that the system shows excellent removal effect on the refractory dye molecules in the printing and dyeing wastewater, and the colority of the effluent is reduced by more than 99%.

[0091] Example 4: Parameter optimization research of capacitive deionization unit

[0092] This embodiment aims to study the influence of different voltages and electrode coating parameters on the performance of CDI. The experimental wastewater is artificially prepared high-salinity water with a TDS concentration of 20,000 mg / L, and 100 mg / L of sodium humate is added to simulate organic pollution.

[0093] Four modified electrodes with different parameters are prepared:

[0094] Electrode A: PEI coating thickness 20 nanometers, TiO2 loading 0.5 mg / cm2;

[0095] Electrode B: PEI coating thickness 50 nanometers, TiO2 loading 0.5 mg / cm2;

[0096] Electrode C: PEI coating thickness 20 nanometers, TiO2 loading 2.0 mg / cm2;

[0097] Electrode D: PEI coating thickness 50 nanometers, TiO2 loading 2.0 mg / cm2;

[0098] The salt adsorption capacity, current efficiency, and anti-fouling performance of the four electrodes were tested at 0.8 volts, 1.0 volts, and 1.2 volts, respectively. The results showed that electrode D performed best at 1.0 volts, with a salt adsorption capacity of 15.2 mg / g, a current efficiency of 85%, and a performance retention rate of 93% after 200 consecutive cycles. This indicates that a thicker PEI coating and a higher TiO2 loading can provide better anti-fouling performance, while an operating voltage of 1.0 volts achieves the best balance between salt adsorption capacity and energy consumption.

[0099] Example 5: Catalyst composition optimization study

[0100] This example studies the effect of Fe content on the performance of Fe / N-g-C3N4 catalysts. Four catalysts with Fe contents of 1.5%, 2.0%, 2.5%, and 3.0% were prepared according to the method described in Section 2.2, and are denoted as catalysts A, B, C, and D, respectively.

[0101] The catalytic oxidation performance of the four catalysts was tested in simulated wastewater containing 30,000 mg / L NaCl and 200 mg / L humic acid. The experimental conditions were: catalyst dosage 3.0 g / L, persulfate dosage 1.0 g / L, UV-LED light intensity 100 mW / cm2, and reaction time 60 minutes.

[0102] The results showed that as the Fe content increased, the catalytic activity first increased and then stabilized. Catalyst C (Fe content 2.5%) performed best, with a humic acid removal rate of 96% and the highest amount of singlet oxygen produced. Further increasing the Fe content to 3.0% slightly decreased the catalytic activity, which may be due to the destruction of the g-C3N4 structure caused by excessive Fe.

[0103] In particular, electron paramagnetic resonance (EPR) tests confirmed that the active oxygen species produced by catalyst C were mainly singlet oxygen, with very low content of hydroxyl radicals, which explained why it could still maintain high catalytic activity in a high-salt environment.

[0104] Example 6: Energy recovery system optimization study

[0105] This example studies the effect of different supercapacitor capacities and DC-DC converter parameters on the energy recovery efficiency. The experimental setup is as follows: the CDI unit uses 10 pairs of modified electrodes with a total area of 2 square meters; the tested supercapacitors have capacities of 1.0, 2.0, 3.0, 4.0, and 5.0 farads; the DC-DC converter uses a topology with an operating frequency varying from 50 kHz to 100 kHz.

[0106] The experimental results show that the supercapacitor capacity needs to be matched with the CDI electrode capacity to achieve the best energy recovery efficiency. For a CDI unit with an electrode area of 2 square meters, a supercapacitor with a capacitance of 2.5 farads shows the best performance, with an energy recovery efficiency of 78%. In addition, the DC-DC converter has the highest efficiency of 94% at an operating frequency of 70 kHz. The optimized energy recovery system can provide 78% of the electrical energy in the CDI regeneration stage to the catalytic oxidation unit, significantly reducing the external energy demand.

[0107] Example 7: Treatment of low-salinity high-organic wastewater

[0108] This example is directed to a special chemical wastewater with a TDS concentration of 8,000 mg / L and a TOC concentration of 800 mg / L. Due to the high concentration of organic matter and relatively low salinity, the energy management system automatically adjusts the energy distribution ratio to 40% for CDI and 60% for AOP.

[0109] The CDI unit uses electrode D (PEI coating thickness 50 nm, TiO2 loading 2.0 mg / cm2), with an operating voltage of 0.8 V and an adsorption time of 12 minutes. The catalytic oxidation unit uses catalyst C (Fe content 2.5%), with a dosage of 5.0 g / L, a persulfate dosage of 2.0 g / L, and a reaction time of 65 minutes.

[0110] The treatment results show that the salt removal rate is 97%, the TOC removal rate is 92%, the energy recovery efficiency is 75%, and the total energy consumption is 2.1 kWh / m3. Especially in the case of high concentration of organic matter, the advantage of non-radical oxidation path is more obvious, avoiding the problem of radical quenching by a large amount of organic matter.

[0111] Example 8: Treatment of ultra-high salinity wastewater

[0112] This example is directed to a petrochemical industry concentrated brine with a TDS concentration of up to 65,000 mg / L and a TOC concentration of 300 mg / L. For wastewater with such high salinity, traditional CDI technology is difficult to effectively treat, and the present application achieves efficient desalination by optimizing the modified electrode and operating parameters.

[0113] The system is configured as follows: the CDI unit uses 20 pairs of modified ACF electrodes with a total electrode area of 4 square meters; the catalyst is Fe / N-g-C3N4 with a Fe content of 3.0 wt%, with a loading of 3.5 g / L; the persulfate dosage is 1.2 g / L; and the energy recovery system uses a supercapacitor with a capacitance of 5.0 farads.

[0114] The operating parameters were set as follows: CDI voltage 1.2 V, adsorption time divided into two stages, the first stage 15 min, the second stage 15 min, and a short break of 1 min for releasing surface charge in between; regeneration time 15 min; catalytic oxidation reaction time 50 min; and energy distribution ratio CDI 75% and AOP 25%.

[0115] The treatment results showed that, despite the extremely high salinity, the system achieved a salt removal rate of 84%, a salt recovery rate of 78%, and a TOC removal rate of 96%. The energy recovery efficiency was 72%, and the total energy consumption was 2.8 kWh / m3, saving about 55% of energy compared to traditional evaporation methods. This result proves the unique advantages of the present application in treating ultra-high salinity wastewater.

[0116] Comparative Example 1: Unmodified electrode

[0117] To verify the anti-pollution performance of the modified electrode, this comparative example used a common ACF electrode that was not modified with PEI and TiO2, and the other conditions were exactly the same as in Example 1.

[0118] The results showed that, when treating the same petrochemical wastewater, the initial salt adsorption capacity of the unmodified electrode was 13.8 mg / g, which was close to that of the modified electrode (14.5 mg / g). However, after 120 hours of continuous operation, the salt adsorption capacity of the unmodified electrode decreased to 7.2 mg / g (retention rate 52%), while that of the modified electrode remained at 12.9 mg / g (retention rate 89%). After 500 hours of operation, the salt adsorption capacity of the unmodified electrode was only 43% of the initial value, while that of the modified electrode remained at 91%.

[0119] This result clearly demonstrates the significant effect of the PEI / TiO2 composite coating on preventing organic pollution of the electrode. Surface analysis of the electrode showed that the surface of the unmodified electrode was covered with a thick layer of organic matter such as humic acid, resulting in a significant reduction in specific surface area and porosity; while the modified electrode had very little organic matter attached to its surface, maintaining good electro-adsorption performance.

[0120] Comparative Example 2: Traditional Fenton oxidation system

[0121] To verify the advantages of the non-free radical catalytic oxidation path in a high-salt environment, this comparative example used a traditional Fenton oxidation system (FeSO4 / H2O2) to treat the desalinated wastewater, and the other conditions were exactly the same as in Example 2.

[0122] The experimental results show that the degradation efficiency of traditional Fenton system for humic acid in wastewater containing 45,000 mg / L salt is only 55%, while the degradation efficiency of Fe / N-g-C3N4 / PS system of the present application is 93%. This is because high concentration of chloride ions has a strong quenching effect on hydroxyl radicals, significantly reducing the efficiency of Fenton reaction. While the non-radical oxidation pathway of the present application mainly produces singlet oxygen, which is not affected by chloride ions, so it can still maintain high efficiency in high salt environment.

[0123] In addition, the energy consumption of the traditional Fenton system is 6.5 kWh / kg TOC, which is much higher than the 3.8 kWh / kg TOC of the present application. This further proves the energy efficiency advantage of the present application in treating high-salt organic wastewater.

[0124] Comparative Example 3: No energy recovery system

[0125] In order to verify the effect of the energy recovery system, the energy recovery system is removed in this comparative example, and the electrical energy in the CDI regeneration stage is directly released without being collected and utilized, and the other conditions are exactly the same as Example 3.

[0126] The experimental results show that the total energy consumption of the system without energy recovery system is 2.7 kWh / m3, which is 80% higher than 1.5 kWh / m3 of Example 3. This result fully proves the important role of the energy recovery system in reducing the overall energy consumption. It is worth noting that about 70-80% of the electrical energy in the CDI regeneration stage can be recycled, which is much higher than the traditional understanding, representing a major breakthrough in energy management of electrochemical systems.

[0127] Comparative Example 4: Traditional evaporation method

[0128] In order to fully compare the differences between the present application and the traditional process, this comparative example uses evaporation crystallization method to treat the petroleum chemical wastewater with the same characteristics as Example 1.

[0129] The experimental results show that the energy consumption of evaporation method for treating high-salt wastewater is as high as 48 kWh / m3, which is 26.7 times of the present application (1.8 kWh / m3). In addition, part of the organic matter is volatilized during the evaporation process, causing secondary pollution, and the recovered mixed salt has many impurities, with limited commercial value. In contrast, the present application not only has low energy consumption, but also can realize efficient degradation of organic matter and selective recovery of salt, with significant environmental and economic benefits.

[0130] In order to fully evaluate the technical effect of the present application, we have carried out systematic testing and comparative analysis on all examples and comparative examples. The main evaluation indexes include: salt removal rate, salt recovery rate, TOC removal rate, energy recovery efficiency, total energy consumption, electrode service life and catalyst stability. The test results are shown in the following Table 1:

[0131] Table 1 Performance comparison of various embodiments of the present application and comparative examples

[0132]

[0133]

[0134] * indicates performance after 500 hours of operation

[0135] ** indicates that the organic matter part is destroyed but there is a volatile loss

[0136] As can be seen from the data in Table 1, the present technology exhibits excellent performance in treating various types of high-salinity industrial wastewater: salt removal rate of 84-97%, salt recovery rate of 78-90%, organic matter removal rate of 92-97%, and energy consumption of only 1.5-2.8 kWh / m3. In particular, in terms of electrode life and energy efficiency, the present technology has a significant advantage over the prior art.

[0137] Further analysis shows that the anti-pollution performance of the modified electrode is closely related to the thickness of the PEI coating and the TiO2 loading. When the thickness of the PEI coating is 40-50 nm and the TiO2 loading is 1.5-2.0 mg / cm2, the electrode exhibits the best anti-pollution performance and long-term stability. This is because a thicker PEI coating provides stronger electrostatic repulsion, while a higher TiO2 loading provides a more complete hydrophilic protective layer, both of which work together to prevent organic adsorption and electrode pollution.

[0138] In terms of catalyst, the Fe / N-g-C3N4 catalyst with a Fe content of 2.5 wt% performs best. Analysis by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) shows that at this time Fe mainly exists in the form of Fe-N4 coordination structure in the g-C3N4 framework, and this special structure is the active center for generating singlet oxygen. When the Fe content exceeds 3.0 wt%, iron oxide clusters are formed, which reduces the catalytic activity.

[0139] Optimization studies of the energy recovery system show that the capacity of the supercapacitor should match the capacity of the CDI electrode, and the capacity ratio of the two is about 1.2:1 for the highest energy recovery efficiency. In addition, the operating frequency of the DC-DC converter has a significant impact on efficiency, and the efficiency reaches the highest in the range of 70-80 kHz.

[0140] In addition to being applicable to the petrochemical, coal chemical and dyeing and printing industry wastewater treatment in the aforementioned embodiments, the present technology can also be applied to the following fields:

[0141] (1)Pharmaceutical industry high-salt organic wastewater treatment: The pharmaceutical industry wastewater contains a large amount of refractory pharmaceutical intermediates and high-concentration inorganic salts, and the present technology can realize efficient degradation of pharmaceutical intermediates and resource recovery of salt.

[0142] (2) Coking industry wastewater treatment: Phenols, cyanide and sulfide pollutants in coking wastewater can be effectively removed by the present technology, while valuable salts such as ammonium sulfate are recovered.

[0143] (3) Concentrated water treatment of zero-emission system: The present technology can be used as the core unit of the zero-emission system to treat concentrated water generated by membrane processes such as reverse osmosis, achieving the goal of near-zero emission.

[0144] (4) Farm irrigation reuse: The treated effluent has excellent water quality and can be directly used for farm irrigation, alleviating water resource shortage.

[0145] In terms of economic benefits, the present technology has significant advantages over traditional processes. Taking the treatment of high-salt industrial wastewater with TDS of 25,000 mg / L and TOC of 450 mg / L as an example, the treatment cost of traditional evaporation method is about 12-15 yuan / m3, while the treatment cost of the present technology is only 3-5 yuan / m3, saving 60-75% of the cost. In addition, salt recovery can generate additional economic benefits, with a value of 1-3 yuan per cubic meter of wastewater.

[0146] According to the calculation of a certain petrochemical enterprise with 1000 cubic meters of high-salt wastewater treated per day, the present technology can save treatment cost of 3.28-4.38 million yuan per year, while creating salt product revenue of 3.6-11 million yuan. The payback period is about 1.5-2 years, which is much lower than the 3-5 years of traditional processes, and has significant economic advantages.

[0147] The present application provides an energy recovery type capacitive deionization-catalytic oxidation coupled high-salt industrial wastewater treatment process, which realizes efficient and synergistic removal of salt and organic matter in high-salt industrial wastewater through innovations such as modified electrode design, non-free radical catalytic oxidation and energy recovery system. The process has the following significant features:

[0148] (1) The PEI / TiO2 composite coating modified electrode effectively solves the problem of organic matter pollution of CDI electrode, greatly prolonging the service life of the electrode;

[0149] (2) The Fe / N-g-C3N4 catalyst generates a non-free radical oxidation path dominated by singlet oxygen, overcoming the inhibitory effect of high-salt environment on traditional oxidation processes;

[0150] (3) The energy recovery system is innovatively designed to use the electrical energy released during the CDI regeneration stage for catalytic oxidation process, significantly reducing the overall energy consumption;

[0151] (4) Through the intelligent control system to realize the accurate control and optimization of the whole process, and dynamically adjust the operation parameters according to the water quality change;

[0152] (5) Achieve the technical target of salt recovery rate of more than 80%, and the treatment cost is reduced by more than 50% compared with the traditional evaporation method.

[0153] The present application has been verified in petrochemical, coal chemical industry, printing and dyeing and other industries, and the treatment effect is good, which has wide application prospect and significant economic and environmental benefits, and provides a new technical route for the resource treatment of high-salinity industrial wastewater.

Claims

1. A process for the treatment of high-salinity industrial wastewater by capacitive deionization-oxidation coupling, characterized in that, The method comprises the following steps: high-salinity industrial wastewater is subjected to microfiltration to remove suspended solids and pH adjustment to 6.5-7.5; the pretreated wastewater is introduced into a modified capacitive deionization unit to remove salt through an electrosorption process at a low voltage of 0.8-1.2 V; the electrical energy released by the modified capacitive deionization unit in the regeneration stage is collected through an energy recovery system; the recovered energy is converted into the required form of electrical energy for the non-radical catalytic oxidation unit through a bidirectional DC-DC converter; the desalinated water is introduced into the non-radical catalytic oxidation unit, in which Fe / N co-doped g-C3N4 catalyst is excited by a UV-LED light source to activate persulfate and generate non-radical active substances dominated by singlet oxygen to degrade organic pollutants; the capacitive deionization voltage, the dosage of catalytic oxidant, and the energy distribution ratio are dynamically adjusted by an intelligent control system according to the salinity and organic matter concentration of the influent; the capacitive deionization regeneration liquid is introduced into a multi-stage membrane concentration system and a crystallization process to recover salt products; the modified capacitive deionization unit adopts activated carbon fiber electrodes coated with a polyethyleneimine and nano-TiO2 composite coating, the polyethyleneimine coating has a thickness of 20-50 nm, the nano-TiO2 particles have a size of 5-20 nm, and the loading amount is 0.5-2.0 mg / cm2.

2. The process of claim 1, wherein, The non-radical catalytic oxidation unit adopts Fe / N co-doped g-C3N4 nanosheet catalyst, the Fe content is 1.5-3.0 wt%, the N content is 30-40 wt%, the catalyst is loaded on a porous SiC carrier, and the catalyst dosage is 2.0-5.0 g / L.

3. The process of claim 1, wherein, The energy recovery system comprises a super capacitor energy storage module, a bidirectional DC-DC converter and an energy management control system, the bidirectional DC-DC converter is based on Topology, input voltage range 0.8-1.5 volts, output voltage range 3.0-12.0 volts, conversion efficiency 90-95%.

4. The process of claim 1, wherein, The operating parameters of the modified capacitive deionization unit are adjusted as follows according to the salinity of the influent: when the total dissolved solids concentration of the influent is less than 10,000 mg / L, the voltage is 0.8 V, and the adsorption time is 10-15 min; when the total dissolved solids concentration of the influent is 10,000-30,000 mg / L, the voltage is 1.0 V, and the adsorption time is 15-25 min; when the total dissolved solids concentration of the influent is greater than 30,000 mg / L, the voltage is 1.2 V, and the adsorption time is 25-30 min.

5. The process of claim 1 wherein, The operating parameters of the non-radical catalytic oxidation unit are adjusted as follows according to the organic matter concentration of the influent: when the total organic carbon concentration of the influent is less than 200 mg / L, the catalyst dosage is 2.0 g / L, the persulfate dosage is 0.5 g / L, and the reaction time is 30 min; when the total organic carbon concentration of the influent is 200-500 mg / L, the catalyst dosage is 3.0 g / L, the persulfate dosage is 1.0 g / L, and the reaction time is 45 min; when the total organic carbon concentration of the influent is greater than 500 mg / L, the catalyst dosage is 4.0 g / L, the persulfate dosage is 2.0 g / L, and the reaction time is 60 min.

6. The process of claim 2, wherein, The preparation method of the Fe / N co-doped g-C3N4 catalyst is as follows: melamine and urea are mixed uniformly at a weight ratio of 5:1; 0.1 mol / L FeCl3·6H2O aqueous solution is added to the mixture so that the iron content in the final product is 1.5-3.0 wt%; the mixture is dried at 80℃ for 12 hours; Raising temperature to 550℃ at 2℃ / min under N2 atmosphere and keeping for 4 hours; The obtained product is washed with 3 mol / L hydrochloric acid and then deionized water until neutral; Drying at 80℃ for 12 hours to obtain Fe / N co-doped g-C3N4 catalyst.

7. The process of claim 1 wherein, The preparation method of the electrode is: After soaking the activated carbon fiber in 6 mol / L hydrochloric acid for 12 hours, washing to neutral and drying; Soaking the pretreated activated carbon fiber in 3 wt% polyethyleneimine aqueous solution for 24 hours; Drying at 60℃ for 8 hours after ultrasonic treatment for 15 minutes; TiO2 nanoparticles are prepared by sol-gel method and dispersed in anhydrous ethanol; TiO2 nanoparticles are loaded on the surface of polyethyleneimine coating by dip-spin coating method; Drying at 60℃ for 4 hours to obtain the composite coating modified electrode.

8. The process of claim 3, wherein, The energy management control system dynamically adjusts the energy distribution ratio according to the water quality characteristics: In high-salinity low-organic wastewater, the energy consumption of the modified capacitive deionization unit accounts for 70% of the total energy consumption, and the non-radical catalytic oxidation unit accounts for 30%; In low-salinity high-organic wastewater, the energy consumption of the modified capacitive deionization unit accounts for 40% of the total energy consumption, and the non-radical catalytic oxidation unit accounts for 60%; The energy recovery system preferentially provides energy for the non-radical catalytic oxidation unit, and the insufficient part is supplemented by the power grid.

9. The process of claim 1, wherein, The intelligent control system of the process includes a multi-parameter real-time monitoring module and a control algorithm based on deep reinforcement learning, the multi-parameter real-time monitoring module includes a conductivity sensor, a total organic carbon online analyzer, a UV-visible spectrum analyzer and a redox potential sensor, the control algorithm dynamically adjusts the capacitive deionization voltage, adsorption / regeneration time, catalyst and oxidant dosage and energy distribution ratio according to real-time water quality data, realizes the maximization of treatment effect and minimization of energy consumption.

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