Capacitive deionization-oxidation coupling high-salt industrial wastewater treatment process

Abstract

The invention relates to a wastewater treatment method, in particular to a capacitive deionization-oxidation coupling high-salt industrial wastewater treatment process, which comprises the following steps: firstly, carrying out micro-filtration to remove suspended matters and adjust the pH value, then carrying out low-voltage electro-adsorption desalination through a modified capacitive deionization unit, collecting electric energy released in a regeneration stage, converting the electric energy into electric energy of a catalytic oxidation unit through a converter, and carrying out high-salt industrial wastewater treatment. Desalted water enters a non-free radical catalytic oxidation unit, a UV-LED excitation catalyst activates persulfate, singlet oxygen is generated to degrade organic matter, an intelligent control system dynamically adjusts voltage, medicament and energy distribution according to the water inlet condition, finally, capacitive deionization regeneration liquid is subjected to multi-stage membrane concentration and crystallization, salt products are recycled, and waste water treatment and recycling are achieved.

Description

Technical Field

[0001] The present invention relates to industrial wastewater treatment methods, and more particularly to a capacitive deionization-oxidation coupled high-salinity industrial wastewater treatment process, belonging to the technical field of industrial wastewater treatment. This invention addresses the complex treatment issues associated with the coexistence of refractory organic matter and high salt concentrations in high-salinity industrial wastewater, achieving the synergistic treatment goals of efficient salt recovery and organic matter degradation. Background Art

[0002] High-salt industrial wastewater refers to industrial wastewater with a salt content exceeding 10,000 mg / L, primarily originating from the petrochemical, coal chemical, pharmaceutical, printing and dyeing, and coking industries. This type of wastewater not only contains high concentrations of salt but also contains large amounts of recalcitrant organic matter. In particular, even after biochemical treatment, the effluent still contains humic and fulvic acids. These substances, acting as typical free radical quenchers, significantly reduce the reaction efficiency of traditional oxidation processes.

[0003] Currently, the main treatment technologies for high-salinity industrial wastewater include evaporation and crystallization, membrane treatment, electrodialysis, and ion exchange. While evaporation and crystallization offer good results, they consume significant energy and are costly. Membrane treatment faces serious issues with membrane fouling and scaling. Electrodialysis consumes a lot of energy and requires stringent pretreatment. Ion exchange has a complex regeneration process and generates secondary pollution. None of these technologies can effectively and simultaneously remove both salt and organic matter from wastewater.

[0004] Through searching, we found the following documents that are closest to the present invention:

[0005] 1. "Treatment of industrial brine using capacitive deionization (CDI) toward zero liquid discharge–challenges and optimization" (Water Research, 2020) studied the feasibility of CDI technology for treating industrial brine, focusing on electrode materials and operating parameter optimization, but did not solve the problem of organic matter contamination of electrodes, nor did it involve energy recovery systems and coordinated treatment of organic matter.

[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-salt wastewater, but does not solve the problems of organic pollution and energy recovery.

[0007] 3. "Singlet oxygen-dominated non-radical oxidation process forefficient degradation of bisphenol A under high salinity conditions" (Water Research, 2018) proposed a non-radical oxidation pathway based on singlet oxygen under high salinity conditions, but it was not combined with CDI technology, nor did it 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) studied the fouling mechanism of humic acid on CDI electrodes, but did 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 implementation details of energy recovery system design and non-radical oxidation pathways.

[0010] The above-mentioned existing technologies generally have the following problems when treating high-salt industrial wastewater: first, the electrodes are easily contaminated by organic matter, resulting in reduced desalination efficiency and shortened lifespan; second, the traditional oxidation process is inefficient in high-salt environments; third, the energy consumption is high and there is a lack of an effective energy recovery and utilization system; fourth, it is impossible to achieve simultaneous and efficient removal of salt and organic matter.

[0011] Therefore, there is an urgent need for a treatment process that can simultaneously and efficiently remove salt and organic matter from high-salt industrial wastewater, has anti-pollution capabilities, and has low energy consumption. This is exactly the technical problem that the present invention aims to solve. Summary of the Invention

[0012] The present invention aims to provide a capacitive deionization-oxidation coupled high-salt industrial wastewater treatment process to address the problems existing in the prior art, particularly to achieve the following technical goals: simultaneous and efficient removal of salt and refractory organic matter from wastewater; achieving a salt recovery rate of over 80%; reducing treatment costs by over 50% compared to conventional evaporation methods; resolving the problem of organic contamination of electrodes in conventional CDI systems; and significantly reducing overall energy consumption through an energy recovery system.

[0013] To achieve the above object, the present invention provides a capacitive deionization-oxidation coupled high-salt industrial wastewater treatment process, comprising the following steps:

[0014] (1) High-salt industrial wastewater is microfiltered to remove suspended solids and the pH is adjusted to 6.5-7.5;

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

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

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

[0018] (5) The desalinated water is introduced into a non-radical catalytic oxidation unit, where the Fe / N co-doped g-C3N4 catalyst is excited by a UV-LED light source and persulfate is activated to produce non-radical active substances mainly composed of singlet oxygen to degrade organic pollutants;

[0019] (6) Dynamically adjust the capacitor deionization voltage, catalytic oxidant dosage, and energy distribution ratio through an intelligent control system based on the influent salinity and organic matter concentration;

[0020] (7) The capacitor deionized regeneration liquid is introduced into a multi-stage membrane concentration system and a crystallization process to recover the salt product.

[0021] Preferably, in one embodiment of the present invention, the modified capacitive deionization unit uses an activated carbon fiber electrode coated with a polyethyleneimine and nano-TiO2 composite coating, the polyethyleneimine coating has a thickness of 20-50 nanometers, the TiO2 nanoparticle size is 5-20 nanometers, and the loading amount is 0.5-2.0 mg / cm2.

[0022] Furthermore, the non-radical catalytic oxidation unit uses Fe / N co-doped g-C3N4 nanosheet catalyst with an Fe content of 1.5-3.0 weight percent and a N content of 30-40 weight percent. The catalyst is loaded on a porous SiC carrier, and the catalyst dosage is 2.0-5.0 g / L.

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

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

[0025] In addition, the operating parameters of the catalytic oxidation unit are adjusted with the influent organic matter concentration as follows: when the influent total organic carbon concentration 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 minutes; when the influent total organic carbon concentration 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 minutes; when the influent total organic carbon concentration 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 minutes.

[0026] Furthermore, the preparation method of the Fe / Ng-C3N4 catalyst is as follows: melamine and urea are uniformly mixed in 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°C for 12 hours; under an N2 atmosphere, the temperature is increased to 550°C at a rate of 2°C / min and maintained for 4 hours; the resulting product is washed with 3 mol / L hydrochloric acid and then washed with deionized water until neutral; and the Fe / Ng-C3N4 catalyst is obtained by drying at 80°C for 12 hours.

[0027] At the same time, 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 neutrality and dried; the pretreated activated carbon fiber is soaked in a 3 weight percent polyethyleneimine aqueous solution for 24 hours; ultrasonically treated for 15 minutes and then dried at 60°C for 8 hours; TiO2 nanoparticles are prepared by a sol-gel method and dispersed in anhydrous ethanol; TiO2 nanoparticles are loaded on the surface of the polyethyleneimine coating by a dip-spin coating method; and dried at 60°C for 4 hours to obtain a composite coating modified electrode.

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

[0029] On the other hand, the control system of this 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, an online total organic carbon analyzer, a UV-visible spectrometer and an oxidation-reduction potential sensor. The control algorithm dynamically adjusts the capacitor deionization voltage, adsorption / regeneration time, catalyst and oxidant dosage, and energy distribution ratio according to real-time water quality data to maximize the treatment effect and minimize energy consumption.

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

[0031] 1. The innovative anti-pollution electrode design solves the problem of organic matter contamination on CDI electrodes, prolongs the service life of the electrodes, and maintains efficient desalination performance;

[0032] 2. The non-radical catalytic oxidation pathway is adopted to effectively solve the problem of low free radical oxidation efficiency in high-salt environments;

[0033] 3. Introducing an energy recovery system to utilize the electrical energy released during the CDI regeneration phase for the catalytic oxidation process, significantly reducing overall energy consumption;

[0034] 4. Through the intelligent control system, it realizes real-time response to water quality changes, optimizes treatment parameters and improves treatment efficiency;

[0035] 5. Achieved simultaneous and efficient removal of salt and organic matter, with a salt recovery rate of over 80% and an organic matter removal rate of over 90%;

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

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

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

[0039] Figure 2 It is a schematic structural diagram of the anti-pollution electrode in the present invention;

[0040] Figure 3 It is a structural diagram of the energy recovery system of the present invention;

[0041] Figure 4 This is a comparison chart of the salt removal rates of different types of high-salt industrial wastewater treated by the present invention;

[0042] Figure 5 This is a comparison chart of organic matter removal rates when treating different types of high-salt industrial wastewater using the present invention;

[0043] Figure 6 This is a comparison chart of the energy recovery efficiency of the present invention and the energy consumption of the traditional process;

[0044] Figure 7 This is the electrode service life test result diagram, which shows the performance attenuation curves of modified electrodes and unmodified electrodes in high-salt wastewater containing organic matter. DETAILED DESCRIPTION

[0045] The following is combined with Figure 1-7 The present invention is further described in detail with reference to the accompanying drawings and Examples. It should be understood by those skilled in the art that these Examples are only used to illustrate the present invention and should not be construed as limiting the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without departing from the scope of the present invention are within the scope of protection of the present invention.

[0046] Reference Figure 1The capacitive deionization-oxidation coupled high-salt industrial wastewater treatment system provided by the present invention mainly consists of 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 includes an inlet pump, microfilter, pH regulator, and flowmeter. High-salinity industrial wastewater is first microfiltered to remove suspended solids to prevent clogging of subsequent treatment units. The pH regulator then adjusts the pH to the optimal range of 6.5-7.5 to improve subsequent treatment efficiency.

[0048] The modified CDI unit, one of the core treatment units of this invention, utilizes activated carbon fiber (ACF) electrodes coated with a polyethyleneimine (PEI) and nano-TiO2 composite coating, coupled with an ion exchange membrane (IEM) to form a capacitive deionization membrane (MCDI) configuration. Preferably, a conductive polymer spacer is placed between the electrodes to improve ion transfer efficiency. This unit removes ionic species from water through an electrosorption process at a low voltage of 0.8-1.2V.

[0049] One of the innovative highlights of this invention is the energy recovery system, which comprises a supercapacitor energy storage module, a bidirectional DC-DC converter, and an energy management and control system. This system collects the electrical energy released during the CDI regeneration phase and converts it into the electrical energy required by the catalytic oxidation unit via a bidirectional DC-DC converter, achieving efficient energy utilization and significantly reducing overall energy consumption.

[0050] The non-radical catalytic oxidation unit utilizes Fe / N co-doped g-C3N4 nanosheet catalysts to generate non-radical active species primarily composed of singlet oxygen (1O2). The catalyst is preferably supported on a porous SiC support and integrated with a UV-LED light source system and a persulfate (PS) oxidant dosing system. This unit is highly effective in degrading recalcitrant organic matter, particularly humic and fulvic acids, in desalinated water.

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

[0052] The salt recovery unit consists of a multi-stage membrane concentration system and a crystallization device, which is used to concentrate the salt in the CDI regeneration liquid and recover it as a solid salt product to achieve resource utilization.

[0053] The entire system operates as follows: high-salt industrial wastewater is pretreated and then enters a modified CDI unit for desalination. During the desalination process, the electrodes adsorb salt until saturation is reached. The CDI unit then switches to regeneration mode, and the released electrical energy is collected by an energy recovery system. The desalinated water enters a non-radical catalytic oxidation unit to treat organic pollutants. The CDI regenerated liquid enters a salt recovery unit to recover the salt product. The entire process is monitored and optimized in real time by an intelligent control system to ensure maximum treatment effect and energy efficiency.

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

[0055] First, commercial activated carbon fiber (ACF) was soaked in 6 mol / L hydrochloric acid for 12 hours to remove metal impurities and activate the surface. The choice of ACF is very important. It is preferred to use a high specific surface area ACF with a specific surface area greater than 2000 m2 / g, such as FR-20 activated carbon fiber produced by Kuraray Co., Ltd. of Japan or Kusano series activated carbon fiber of Toyo Soda Industry Co., Ltd. of Japan. After soaking, it was repeatedly washed with deionized water until neutral and dried at 80°C for 24 hours. Subsequently, it was heat treated at 500°C for 2 hours under a nitrogen atmosphere to further activate the electrode surface.

[0056] Next, prepare a 3% by weight aqueous solution of polyethyleneimine (PEI). Preferably, use branched PEI with a molecular weight of approximately 25,000, such as that from Sigma-Aldrich. Soak the pretreated ACF in the PEI solution for 24 hours and ultrasonicate for 15 minutes to promote uniform distribution of the PEI on the ACF surface. The soaked ACF is then dried at 60°C for 8 hours to form a PEI coating.

[0057] TiO2 nanoparticles were then prepared using a sol-gel method. The specific steps were: dissolving 10 ml of tetrabutyl titanate (TBOT) in 40 ml of anhydrous ethanol; adding 0.5 ml of concentrated nitric acid in a 20 ml water-ethanol mixture (volume ratio 1:4) dropwise under vigorous stirring; aging at room temperature for 24 hours to form a transparent sol; drying the sol at 80°C for 12 hours to obtain a gel; and finally calcining 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 a concentration of 10 mg / ml. The TiO2 nanoparticles were evenly loaded onto the PEI coating surface using a dip-spin coating method at 2000 rpm for 30 seconds. The TiO2 loading was controlled within the range of 0.5-2.0 mg / cm2, preferably 1.0-1.5 mg / cm2. Finally, the coating was dried at 60°C for 4 hours to form a PEI / TiO2 composite coating-modified electrode.

[0059] To assemble a CDI electrode, the modified ACF is cut to the desired size (typically 10 cm x 10 cm) and press-fitted to a titanium mesh current collector. A 250-micron-thick conductive polymer spacer is placed between the electrodes. Preferably, the edges are encapsulated with epoxy resin to prevent short circuits.

[0060] The design principle of this modified electrode is as follows: the PEI coating exhibits a positive charge under neutral and weakly alkaline conditions, generating electrostatic repulsion against negatively charged humic and fulvic acids. Simultaneously, the TiO2 nanoparticles provide a highly hydrophilic surface, forming a hydrated layer that blocks hydrophobic organic contaminants from contacting the electrode surface. This dual protective mechanism enables the modified electrode to exhibit excellent anti-fouling properties and long-term stability in organic-containing, high-salinity wastewater.

[0061] Non-radical catalytic oxidation is another core technology of this invention, the key of which lies in the preparation of Fe / N co-doped g-C3N4 nanosheet catalysts. This catalyst can produce non-radical active species mainly composed of singlet oxygen (1O2), maintaining efficient oxidation ability in high-salt environments. The specific preparation process is as follows:

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

[0063] Next, the dried precursor was placed in an alumina crucible and placed in a tube furnace. Under a nitrogen atmosphere, the temperature was raised to 550°C at a rate of 2°C / minute and held for 4 hours. This heat treatment process caused the melamine to undergo thermal polymerization, forming a g-C3N4 structure, while iron ions were doped into the g-C3N4 skeleton. After the heat treatment was completed, the product was allowed to cool naturally to room temperature.

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

[0065] In order to improve the dispersibility and stability of the catalyst, it is necessary to load it on a carrier. The present invention uses porous SiC as a carrier, and its preparation method is: SiO2 and sucrose are mixed with a molar ratio of 1: 3, a small amount of iron catalyst (iron content is about 1 weight percentage) is added, and the mixture is fully ground and mixed; the mixture is placed in a graphite crucible, heated to 1400°C at 5°C / minute under an argon atmosphere, and naturally cooled after keeping for 2 hours; unreacted SiO2 is removed by washing with 6 mol / L hydrofluoric acid solution, the metal catalyst is removed with 6 mol / L hydrochloric acid, washed with deionized water to neutrality, and dried at 120°C for 12 hours; finally, the SiC carrier with a target particle size (300-500 microns) is obtained by grinding and sieving.

[0066] Finally, the catalyst powder was ultrasonically dispersed in ethanol and loaded onto a porous SiC support by impregnation at a loading of 20 weight percent. After drying at 120°C for 6 hours, it was activated at 300°C in nitrogen for 2 hours to obtain the final supported catalyst.

[0067] The unique electronic structure of this Fe / N co-doped g-C3N4 catalyst enables it to preferentially generate singlet oxygen over traditional hydroxyl radicals, making the catalytic oxidation process unaffected by chloride ion interference in high-salt environments. Furthermore, singlet oxygen exhibits strong selective oxidation activity against the benzene ring structure of organic compounds such as humic acid, enabling efficient degradation of these difficult-to-treat organic pollutants.

[0068] The energy recovery system is a key innovation of this invention. It collects the electrical energy released during the CDI regeneration phase and converts it into the energy required for the catalytic oxidation process, significantly reducing overall energy consumption. The system primarily consists of three components: a supercapacitor energy storage module, a bidirectional DC-DC converter, and an energy management and control system.

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

[0070] The bidirectional DC-DC converter is the core of the energy recovery system. The topology features low ripple and high efficiency. The converter's input voltage range is 0.8-1.5V (corresponding to the CDI discharge voltage), and its output voltage range is 3.0-12.0V (corresponding to AOP system requirements), with a conversion efficiency of 90-95%. The converter's power range is 50-500W, and its operating frequency is 50-100kHz.

[0071] The energy management and control system is based on an STM32 series microcontroller or TI's MSP430 series low-power microcontroller, equipped with current and voltage sensors and temperature monitoring modules. This system dynamically adjusts energy allocation based on wastewater quality and treatment requirements: for high-salinity, low-organic wastewater, energy allocation to the CDI system is increased; for low-salinity, high-organic wastewater, energy allocation to the AOP system is increased. Furthermore, energy recovery efficiency is further improved through pre-charging strategies, soft switching technology, and capacitor array optimization.

[0072] Example 1: Petrochemical wastewater treatment

[0073] This example is for high-salt industrial wastewater from a 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, major organic pollutants including petroleum hydrocarbons, benzene series and humic acid, and pH value of 7.2.

[0074] The treatment system is configured as follows: The CDI unit utilizes 10 pairs of modified ACF electrodes, with a total electrode area of 2 square meters. The catalyst is Fe / Ng-C3N4 with an Fe content of 2.5 weight percent and a loading of 3.0 g / L. The persulfate dosage is 1.2 g / L. The energy recovery system utilizes a 2.5 Farad supercapacitor. The system is designed to process 2 cubic meters per hour.

[0075] First, a modified electrode coated with a PEI and TiO2 composite coating was prepared according to the method described in Section 2.1. Specifically, FR-20 activated carbon fibers with a specific surface area of 2500 m2 / g were selected. After acid treatment and thermal activation, they were immersed in a 3% by weight aqueous solution of PEI (molecular weight 25,000) for 24 hours. After ultrasonic treatment for 15 minutes, the fibers were dried at 60°C for 8 hours. Next, TiO2 nanoparticles with a particle size of 15 nm were prepared using a sol-gel method. The TiO2 loading was controlled at 1.2 mg / cm2 on the PEI coating surface by dip-spin coating.

[0076] Next, an Fe / Ng-C3N4 catalyst was prepared according to the method described in Section 2.2. Melamine and urea were mixed in a 5:1 weight ratio, and FeCl3 solution was added to bring the iron content to 2.5 weight percent. The catalyst was then thermally polymerized and post-treated to obtain a catalyst loaded on a porous SiC support with a particle size of 400 μm at a loading of 20 weight percent.

[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 prioritizes providing energy to the catalytic oxidation unit, and the shortfall is supplemented by the power grid.

[0078] After 30 days of continuous testing, the treatment results were as follows: 92% salt removal, 85% salt recovery, 95% TOC removal, 78% energy recovery efficiency, and a total energy consumption of 1.8 kWh / m³, representing a 65% energy saving compared to traditional evaporation methods. Even after 500 hours of operation, the modified electrode retained 91% of its initial salt adsorption capacity, demonstrating excellent anti-fouling performance.

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

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

[0081] The treatment system is configured as follows: The CDI unit utilizes 15 pairs of modified ACF electrodes, with a total electrode area of 3 square meters. The catalyst is Fe / Ng-C3N4 with an Fe content of 3.0 weight percent and a loading of 4.0 g / L. The persulfate dosage is 1.5 g / L. The energy recovery system utilizes a 4.0 Farad supercapacitor. The system has a treatment flow rate of 1.5 cubic meters per hour.

[0082] The modified electrode was prepared using the same method as in Example 1, except that the TiO2 loading was increased to 1.5 mg / cm2 to enhance pollution resistance. In the catalyst preparation, the iron content was increased to 3.0 weight percent to cope with higher concentrations of organic pollutants.

[0083] The system operating parameters are set as follows: CDI voltage 1.2 volts, 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, and the initial setting is CDI 60% and AOP 40%.

[0084] Continuous operation tests demonstrated the following results: 88% salt removal, 82% salt recovery, 93% TOC removal, 75% energy recovery, and a total energy consumption of 2.2 kWh / m³, representing a 58% energy saving compared to traditional evaporation methods. Notably, even under such high salinity conditions, the non-radical oxidation pathway demonstrated excellent organic matter degradation efficiency, demonstrating the technical advantages of this invention.

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

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

[0087] The treatment system is configured as follows: The CDI unit utilizes eight pairs of modified ACF electrodes, with a total electrode area of 1.5 square meters. The catalyst is Fe / Ng-C3N4 with an Fe content of 2.0 weight percent and a loading of 2.5 g / L. The persulfate dosage is 0.8 g / L. The energy recovery system utilizes a 2.0 Farad supercapacitor. The system has a treatment flow rate of 2.5 cubic meters per hour.

[0088] In this example, because the dye molecules in the printing and dyeing wastewater are large and carry charged groups, the thickness of the PEI coating on the modified electrode was increased to 40 nanometers to enhance the electrostatic repulsion effect. The particle size of the TiO2 nanoparticles was controlled in the range of 5-10 nanometers to increase 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; the energy distribution ratio is initially set to CDI 50% and AOP 50%, and is adjusted by the intelligent control system based on real-time water quality data.

[0090] After continuous operation testing, the treatment results are as follows: salt removal rate of 95%, salt recovery rate of 88%, TOC removal rate of 97%, energy recovery efficiency of 82%, and total energy consumption of 1.5 kWh / cubic meter, which saves 72% energy compared to traditional evaporation methods. Particularly noteworthy is that this system demonstrates excellent removal of difficult-to-degrade dye molecules in printing and dyeing wastewater, reducing effluent color by over 99%.

[0091] Example 4: Capacitive Deionization Unit Parameter Optimization Study

[0092] This example aims to study the effects of different voltages and electrode coating parameters on CDI performance. The experimental wastewater is artificially prepared high-salt 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 were prepared:

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

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

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

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

[0098] The salt adsorption capacity, current efficiency, and anti-fouling performance of the four electrodes were tested at voltages of 0.8 volts, 1.0 volts, and 1.2 volts. The results showed that electrode D performed best at 1.0 volt, with a salt adsorption capacity of 15.2 mg / g, a current efficiency of 85%, and a performance retention rate of 93% after 200 cycles. This indicates that thicker PEI coatings and higher TiO2 loadings provide better anti-fouling performance, while an operating voltage of 1.0 volt achieves the optimal 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 / Ng-C3N4 catalysts. Following the method described in Section 2.2, four catalysts with Fe contents of 1.5%, 2.0%, 2.5%, and 3.0% were prepared and designated 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 of 3.0 g / L, persulfate dosage of 1.0 g / L, UV-LED light intensity of 100 mW / cm², and reaction time of 60 minutes.

[0102] The results showed that with increasing Fe content, the catalytic activity initially increased and then stabilized. Catalyst C (Fe content 2.5%) performed best, achieving a 96% humic acid removal rate and the highest singlet oxygen production. Further increasing the Fe content to 3.0% resulted in a slight decrease in catalytic activity, likely due to structural damage caused by excessive Fe in the g-C3N4.

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

[0104] Example 6: Energy Recovery System Optimization Study

[0105] This example studies the effects of different supercapacitor capacities and DC-DC converter parameters on 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 test capacities are 1.0, 2.0, 3.0, 4.0 and 5.0 farad supercapacitors; the DC-DC converter uses topology, operating frequency varies from 50 kHz to 100 kHz.

[0106] Experimental results demonstrate that optimal energy recovery efficiency requires a matching of supercapacitor capacity and CDI electrode capacity. For a CDI unit with a 2-square-meter electrode area, a 2.5-farad supercapacitor performs best, achieving an energy recovery efficiency of 78%. Furthermore, the DC-DC converter achieves peak efficiency of 94% at a frequency of 70 kHz. The optimized energy recovery system is able to provide 78% of the energy generated during the CDI regeneration phase to the catalytic oxidation unit, significantly reducing external energy requirements.

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

[0108] This example is for specialty chemical wastewater with a TDS concentration of 8,000 mg / L and a TOC concentration of 800 mg / L. Due to the high organic matter concentration 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 used electrode D (PEI coating thickness 50 nm, TiO2 loading 2.0 mg / cm2), operating voltage 0.8 V, and adsorption time 12 minutes. The catalytic oxidation unit used catalyst C (Fe content 2.5%) at a dosage of 5.0 g / L and a persulfate dosage of 2.0 g / L, with a reaction time of 65 minutes.

[0110] Treatment results showed a salt removal rate of 97%, a TOC removal rate of 92%, an energy recovery efficiency of 75%, and a total energy consumption of 2.1 kWh / m³. The advantages of the non-radical oxidation pathway are particularly evident in conditions with high organic matter concentrations, as it avoids the problem of free radical quenching by large amounts of organic matter.

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

[0112] This example targets concentrated brine from the petrochemical industry with a TDS concentration of up to 65,000 mg / L and a TOC concentration of 300 mg / L. Conventional CDI technology struggles to effectively treat such high-salinity wastewater. This invention achieves efficient desalination by optimizing modified electrodes and operating parameters.

[0113] The system configuration is as follows: the CDI unit uses 20 pairs of modified ACF electrodes with a total electrode area of 4 square meters; the catalyst uses Fe / Ng-C3N4 with an Fe content of 3.0 weight percent and a loading of 3.5 grams per liter; the persulfate dosage is 1.2 grams per liter; and the energy recovery system uses a 5.0 farad supercapacitor.

[0114] The operating parameters are set as follows: CDI voltage 1.2 volts, adsorption time is divided into two stages, the first stage is 15 minutes, the second stage is 15 minutes, and a short break of 1 minute in the middle to release the surface charge; regeneration time is 15 minutes; catalytic oxidation reaction time is 50 minutes; energy distribution ratio is CDI 75% and AOP 25%.

[0115] Treatment results show that despite extremely high salinity, the system achieved an 84% salt removal rate, a 78% salt recovery rate, and a 96% TOC removal rate. Energy recovery efficiency was 72%, and total energy consumption was 2.8 kWh / m³, representing approximately 55% energy savings compared to traditional evaporation methods. This demonstrates the unique advantages of this invention in treating ultra-high-salinity wastewater.

[0116] Comparative Example 1: Unmodified Electrode

[0117] In order to verify the anti-pollution performance of the modified electrode, this comparative example uses an ordinary ACF electrode that has not been modified with PEI and TiO2, and other conditions are exactly the same as those 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, similar 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 dropped to 7.2 mg / g (52% retention), while the modified electrode still maintained 12.9 mg / g (89% retention). After 500 hours of operation, the salt adsorption capacity of the unmodified electrode was only 43% of the initial value, while the modified electrode still maintained 91%.

[0119] This result clearly demonstrates the remarkable effectiveness of the PEI / TiO2 composite coating in preventing organic contamination of the electrode. Electrode surface analysis showed that the unmodified electrode surface was covered with a thick layer of organic matter, such as humic acid, resulting in a significant reduction in specific surface area and porosity. In contrast, the modified electrode surface had minimal organic matter attached, maintaining excellent electrosorption performance.

[0120] Comparative Example 2: Traditional Fenton Oxidation System

[0121] In order to verify the advantages of the non-radical catalytic oxidation pathway 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] Experimental results show that in wastewater containing 45,000 mg / L of salinity, the conventional Fenton system achieved only a 55% degradation efficiency for humic acid, while the Fe / Ng-C3N4 / PS system of the present invention achieved a 93% degradation efficiency. This is because high concentrations of chloride ions strongly quench hydroxyl radicals, significantly reducing the efficiency of the Fenton reaction. The non-radical oxidation pathway of the present invention, however, primarily produces singlet oxygen, which is unaffected by chloride ions and therefore maintains high efficiency even in high-salt environments.

[0123] In addition, the energy consumption of the conventional Fenton system is 6.5 kWh / kg TOC, which is much higher than the 3.8 kWh / kg TOC of the present invention, further demonstrating the energy efficiency advantage of the present invention in treating high-salinity organic wastewater.

[0124] Comparative Example 3: No Energy Recovery System

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

[0126] Experimental results show that the total energy consumption without an energy recovery system is 2.7 kWh / m³, 80% higher than the 1.5 kWh / m³ in Example 3. This result fully demonstrates the important role of energy recovery systems in reducing overall energy consumption. Notably, approximately 70-80% of the electrical energy generated during the CDI regeneration phase can be recovered and reused, a percentage far higher than conventional wisdom suggests, representing a significant breakthrough in energy management for electrochemical systems.

[0127] Comparative Example 4: Traditional Evaporation Method

[0128] In order to comprehensively compare the differences between the present invention and the traditional process, this comparative example uses the evaporation crystallization method to treat petrochemical wastewater with the same characteristics as in Example 1.

[0129] Experimental results show that the energy consumption of the evaporation method for treating high-salinity wastewater is as high as 48 kWh / m³, 26.7 times that of the present invention (1.8 kWh / m³). Furthermore, some organic matter evaporates during the evaporation process, causing secondary pollution, while the recovered mixed salt contains a high level of impurities, limiting its commercial value. In contrast, the present invention not only reduces energy consumption but also achieves efficient organic matter degradation and selective salt recovery simultaneously, resulting in significant environmental and economic benefits.

[0130] To fully evaluate the technical effectiveness of this invention, we conducted systematic testing and comparative analysis of all examples and comparative examples. Key evaluation metrics included salt removal efficiency, salt recovery rate, TOC removal rate, energy recovery efficiency, total energy consumption, electrode life, and catalyst stability. The test results are summarized in Table 1 below:

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

[0132]

[0133]

[0134] *Indicates performance after 500 hours of operation

[0135] **Indicates that the organic matter is partially destroyed but there is volatilization loss

[0136] As shown in Table 1, the technology presented here demonstrates excellent performance in treating various types of high-salinity industrial wastewater: salt removal rates of 84-97%, salt recovery rates of 78-90%, and organic matter removal rates of 92-97%, all with energy consumption of only 1.5-2.8 kWh / m³. This technology offers significant advantages over existing technologies in terms of electrode life and energy efficiency.

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

[0138] The Fe / Ng-C3N4 catalyst with an Fe content of 2.5 weight percent performed best. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis showed that the Fe was primarily present in the g-C3N4 framework in an Fe-N4 coordination structure. This unique structure is the active center for singlet oxygen generation. When the Fe content exceeds 3.0 weight percent, iron oxide clusters form, which in turn reduces catalytic activity.

[0139] Energy recovery system optimization studies have shown that the capacity of the supercapacitor should match the capacity of the CDI electrode, with the highest energy recovery efficiency achieved when the capacity ratio is approximately 1.2:1. Furthermore, the operating frequency of the DC-DC converter significantly influences efficiency, with peak efficiency achieved in the 70-80 kHz range.

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

[0141] (1) Treatment of high-salt organic wastewater in the pharmaceutical industry: The wastewater in the pharmaceutical industry contains a large amount of difficult-to-degrade drug intermediates and high-concentration inorganic salts. This technology can achieve efficient degradation of drug intermediates and resource recovery of salt.

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

[0143] (3) Treatment of concentrated water in zero-emission systems: This technology can serve as the core unit of a zero-emission system to treat concentrated water produced by membrane processes such as reverse osmosis, thereby achieving near-zero emission goals.

[0144] (4) Reuse in farmland irrigation: The effluent treated by this technology has excellent water quality and can be directly used for farmland irrigation, thus alleviating the problem of water shortage.

[0145] In terms of economic benefits, the technology presented in this paper offers significant advantages over traditional processes. For example, for treating high-salinity industrial wastewater with a TDS of 25,000 mg / L and a TOC of 450 mg / L, the traditional evaporation method costs approximately 12-15 yuan per cubic meter, while this technology only costs 3-5 yuan per cubic meter, a cost savings of 60-75%. Furthermore, salt recovery generates additional economic benefits, with each cubic meter of wastewater producing a salt product worth 1-3 yuan.

[0146] Based on calculations based on a petrochemical company treating 1,000 cubic meters of high-salinity wastewater daily, this technology can save 3.28-4.38 million yuan in treatment costs annually, while generating 360,000-1.1 million yuan in salt product revenue. The investment payback period is approximately 1.5-2 years, significantly shorter than the 3-5 years required by traditional processes, offering significant economic advantages.

[0147] This invention provides an energy-recovery capacitive deionization-catalytic oxidation coupled process for treating high-salinity industrial wastewater. Through innovations such as modified electrode design, non-radical catalytic oxidation, and an energy recovery system, it achieves highly efficient, synergistic removal of salt and organic matter from high-salinity industrial wastewater. This process has the following notable features:

[0148] (1) The PEI / TiO2 composite coating modified electrode effectively solved the problem of organic matter contamination of CDI electrodes and significantly extended the electrode life;

[0149] (2) The Fe / Ng-C3N4 catalyst was used to generate a non-radical oxidation pathway dominated by singlet oxygen, overcoming the inhibitory effect of high-salt environment on traditional oxidation processes;

[0150] (3) An innovative energy recovery system is designed to utilize the electrical energy released during the CDI regeneration phase for the catalytic oxidation process, significantly reducing overall energy consumption.

[0151] (4) Accurately control and optimize the entire process through an intelligent control system, and dynamically adjust operating parameters according to changes in water quality;

[0152] (5) Achieve a technical goal of achieving a salt recovery rate of more than 80% and reducing treatment costs by more than 50% compared to traditional evaporation methods.

[0153] The technology of the present invention has been pilot-tested in petrochemical, coal chemical, printing and dyeing industries, with good treatment effects, broad application prospects and significant economic and environmental benefits, and provides a new technical route for the resource-based treatment of high-salt industrial wastewater.

Claims

1. Capacitive deionization-oxidation coupled high-salt industrial wastewater treatment process, characterized by: The following steps are involved: High-salt industrial wastewater is microfiltered to remove suspended solids and the pH is adjusted to 6.5-7.5; The pretreated wastewater is introduced into a modified capacitive deionization unit, where the salt is removed by electrosorption at a low voltage of 0.8-1.2V. The energy recovery system collects the electrical energy released by the capacitive deionization unit during the regeneration phase; The recovered energy is converted into the electrical energy required by the catalytic oxidation unit through a bidirectional DC-DC converter; The desalinated water is introduced into a non-radical catalytic oxidation unit, where a UV-LED light source excites the Fe / N co-doped g-C3N4 catalyst and simultaneously activates persulfate to produce non-radical active substances, mainly singlet oxygen, to degrade organic pollutants. According to the influent salinity and organic matter concentration, the capacitor deionization voltage, catalytic oxidant dosage and energy distribution ratio are dynamically adjusted through the intelligent control system; The capacitor deionized regeneration liquid is introduced into a multi-stage membrane concentration system and a crystallization process to recover the salt product.

2. The treatment process according to claim 1, characterized in that The modified capacitive deionization unit adopts an activated carbon fiber electrode with a surface coated with a polyethyleneimine and nano-TiO2 composite coating, the polyethyleneimine coating has a thickness of 20-50 nanometers, the TiO2 nanoparticle size is 5-20 nanometers, and the loading amount is 0.5-2.0 mg / cm2.

3. The treatment process according to claim 1, characterized in that The non-radical catalytic oxidation unit uses Fe / N co-doped g-C3N4 nanosheet catalyst with an Fe content of 1.5-3.0 weight percent and a N content of 30-40 weight percent. The catalyst is supported on a porous SiC carrier and the catalyst dosage is 2.0-5.0 g / L.

4. The treatment process according to claim 1, characterized in that: 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, with an input voltage range of 0.8-1.5 volts, an output voltage range of 3.0-12.0 volts, and a conversion efficiency of 90-95%.

5. The treatment process according to claim 1, characterized in that: The operating parameters of the capacitive deionization unit are adjusted according to the inlet water salinity as follows: 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 minutes; 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 minutes; When the total dissolved solids concentration of the influent water is greater than 30,000 mg / L, the voltage is 1.2 V and the adsorption time is 25-30 minutes.

6. The treatment process according to claim 1, characterized in that: The operating parameters of the catalytic oxidation unit are adjusted according to the concentration of organic matter in the influent as follows: 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 minutes; 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 minutes; 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 minutes.

7. The treatment process according to claim 3, characterized in that: The preparation method of the Fe / Ng-C3N4 catalyst is: Mix melamine and urea in a weight ratio of 5:1; Adding a 0.1 mol / L FeCl3·6H2O aqueous solution to the mixture so that the iron element accounts for 1.5-3.0 weight percent of the final product; The mixture was dried at 80°C for 12 hours; Under N2 atmosphere, the temperature was raised to 550°C at 2°C / min and maintained for 4 h; The obtained product was washed with 3 mol / L hydrochloric acid and then washed with deionized water until neutral; The Fe / Ng-C3N4 catalyst was obtained by drying at 80°C for 12 hours.

8. The treatment process according to claim 2, characterized in that: The preparation method of the modified electrode is: The activated carbon fiber was soaked in 6 mol / L hydrochloric acid for 12 hours, washed to neutrality and dried; The pretreated activated carbon fibers were immersed in a 3 weight percent polyethyleneimine aqueous solution for 24 hours; After ultrasonic treatment for 15 min, the mixture was dried at 60 °C for 8 h; TiO2 nanoparticles were prepared by sol-gel method and dispersed in anhydrous ethanol; TiO2 nanoparticles were loaded on the surface of polyethyleneimine coating by dip-spin coating method; The composite coating modified electrode was obtained by drying at 60°C for 4 hours.

9. The treatment process according to claim 1, characterized in that: The energy management system dynamically adjusts the energy distribution ratio according to the influent water quality characteristics: In high-salt, low-organic wastewater, the energy consumption of the capacitive deionization unit accounts for 70% of the total energy consumption, and the catalytic oxidation unit accounts for 30%; In low-salt, high-organic wastewater, the energy consumption of the capacitive deionization unit accounts for 40% of the total energy consumption, and the catalytic oxidation unit accounts for 60%; The energy recovery system provides energy to the catalytic oxidation unit first, and the shortfall is supplemented by the power grid.

10. The treatment process according to claim 1, characterized in that: The control system of this 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, an online total organic carbon analyzer, a UV-visible spectrometer and an oxidation-reduction potential sensor. The control algorithm dynamically adjusts the capacitor deionization voltage, adsorption / regeneration time, catalyst and oxidant dosage, and energy distribution ratio according to real-time water quality data to maximize the treatment effect and minimize energy consumption.

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