A catalyst, a method for synthesizing the same, and a method and system for treating landfill leachate

Abstract

The present application relates to the technical field of landfill leachate treatment, and discloses a catalyst, a synthesis method thereof, a landfill leachate treatment method and a system, the synthesis method of the catalyst comprising the following steps: dipping spherical gamma-phase aluminum oxide into a cobalt chloride aqueous solution, taking out the solid and drying to obtain first spherical modified aluminum oxide; modifying the first spherical modified aluminum oxide using micro-bubbles and nanosecond pulse electric fields to obtain second spherical modified aluminum oxide; and calcining the second spherical modified aluminum oxide to obtain the catalyst. The catalyst provided by the present application has stable structure and outstanding catalytic performance. The catalyst is modified by the synergistic effect of micro-bubbles and nanosecond pulse electric fields, a firm Co-Al-O active interface is formed, the electron transfer efficiency is improved, the activity retention rate is high, the active metal dissolution amount is low, and the filler replacement cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of landfill leachate treatment technology, and in particular to a catalyst and its synthesis method, as well as a landfill leachate treatment method and system. Background Technology

[0002] Landfill leachate from aging landfills is characterized by high pollutant concentrations, extremely poor biodegradability, complex composition, and the presence of large amounts of humic substances and new pollutants. Conventional membrane filtration, biochemical, and flocculation sedimentation processes are difficult to achieve deep discharge compliance. At present, the industry mainstream adopts Fenton oxidation, ozone oxidation, and membrane separation coupling processes for end-of-pipe deep treatment, but existing technologies have many technical shortcomings that are difficult to overcome.

[0003] Existing cobalt-based alumina advanced oxidation catalysts generally suffer from the following defects: First, the support pretreatment process is simple, and dust and soluble impurities on the alumina surface occupy the active anchoring points in the pores, resulting in uneven loading of cobalt active components and a small number of catalytic active sites. Second, they are prepared solely through a simple impregnation-calcination process, lacking interfacial electron enhancement modification methods, resulting in low catalyst electron transfer efficiency and weak ability to activate peracetic acid to generate strong oxidizing free radicals. Third, during long-term water treatment operation, cobalt metal components are easily dissolved and lost, and the catalytic activity decays severely after hundreds of batches of continuous operation, leading to short catalyst replacement cycles and high maintenance costs. Fourth, the preparation process lacks atmosphere control, resulting in low bonding strength at the Co-Al-O composite active interface, making it difficult to achieve long-term stable degradation of new pollutants.

[0004] At the water treatment system level, traditional advanced oxidation equipment is mostly a split-type civil engineering tank, with low equipment integration, large footprint, and poor mobility, making it unsuitable for small and medium-sized landfills and emergency treatment scenarios. The reactors rely solely on oxidant oxidation, lacking a multi-field synergistic coupling mechanism of nanosecond pulse electric field, microbubble, and ultraviolet light, resulting in incomplete breakdown of recalcitrant large organic molecules and poor removal of new pollutants such as sulfonamides and trace endocrine disruptors. The internal electrode, water distribution, and limiting sieve structure parameters of the reactor lack precise matching ranges, leading to easy catalyst loss and low gas-liquid mass transfer efficiency. The logic of the self-controlled reflux system is imperfect, lacking a clear reflux endpoint and high / low liquid level interlocking control logic, resulting in weak tolerance to water quality shock loads, inability to degrade wastewater exceeding water quality standards in a closed-loop cycle, and large fluctuations in effluent water quality.

[0005] Existing treatment processes suffer from multiple drawbacks, including low catalyst activity, easy deactivation, difficulty in removing trace amounts of new pollutants, poor system integration, low matching degree of multi-field synergistic coupling, insufficient long-term operational stability, and high overall treatment costs. They cannot meet the stringent discharge standards for current advanced wastewater treatment. There is an urgent need to develop highly stable dedicated catalysts, multi-field synergistic integrated treatment systems, and supporting complete treatment processes. Summary of the Invention

[0006] The present invention aims to improve at least one technical problem in the prior art.

[0007] The first aspect of this invention provides a method for synthesizing a catalyst, comprising the following steps: Spherical γ-phase alumina was immersed in a divalent cobalt chloride aqueous solution, and the solid was dried to obtain the first spherical modified alumina. The first spherical modified alumina was modified using microbubbles and nanosecond pulsed electric fields to obtain the second spherical modified alumina. The second spherical modified alumina was calcined to obtain the catalyst.

[0008] Preferably, the mass ratio of cobalt ions in the divalent cobalt chloride aqueous solution to the spherical γ-phase alumina is 1:10.

[0009] Preferably, the spherical γ-phase alumina has a particle size of 2 mm-4 mm and a specific surface area greater than or equal to 220 m². 2 / g, porosity of 50%-60%, and average pore size of 30 nm-50 nm.

[0010] Preferably, in the modification of the first spherical modified alumina using microbubbles and a nanosecond pulsed electric field, the parameters of the microbubbles include: an average diameter of 30 μm-80 μm, an absolute value of a Zeta potential greater than or equal to 50 mV, and a bubble number density of 5 × 10⁻⁶. 8 5 x 10 units / L 10 Units / L; The parameters of the nanosecond pulse electric field include: voltage of 5 kV-30 kV, pulse width of 10 ns-100 ns, frequency of 100 Hz-1000 Hz, and field strength greater than or equal to 106 V / m; The modification time is 2 h-4 h.

[0011] A second aspect of the present invention provides a catalyst, which is prepared by the above-described catalyst synthesis method.

[0012] A third aspect of the present invention provides a method for treating landfill leachate, comprising the following steps: Pretreatment: The landfill leachate is pretreated to obtain the first treated liquid; Catalytic degradation: The first treatment liquid is brought into contact with the catalyst described above, and microbubbles and nanosecond pulse electric fields are applied to the first treatment liquid to perform the first pollutant degradation, resulting in the second treatment liquid; Ultraviolet degradation: Ultraviolet light is applied to the second treatment solution to degrade the pollutants for the second time, resulting in a third treatment solution; The water quality of the third treatment liquid is monitored online. According to the preset water quality compliance rules, when the water quality of the third treatment liquid meets the standards, the third treatment liquid is discharged. When the water quality of the third treatment liquid does not meet the standards, the pretreatment, catalytic degradation and ultraviolet degradation steps are repeated.

[0013] Preferably, in the process of simultaneously applying microbubbles and a nanosecond pulsed electric field to the first treatment liquid for the first pollutant degradation, the parameters of the microbubbles include: an average diameter of 30 μm-80 μm, an absolute value of zeta potential of 50 mV-80 mV, and a bubble number density of 5 × 10⁻⁶. 8 5 x 10 units / L 10 per L.

[0014] A fourth aspect of the present invention provides a landfill leachate treatment system, the landfill leachate treatment system being used to perform the above-described landfill leachate treatment method; the landfill leachate treatment system comprising: The container is provided with a pretreatment conditioning tank, a coupling reactor, an ultraviolet-assisted catalytic device and a clear water tank connected in sequence inside the container, and also has a reflux unit that connects the outlet of the clear water tank to the inlet of the pretreatment conditioning tank. The pretreatment equalization tank is used to intercept suspended particulate matter and large molecular flocs in landfill leachate and to balance water quality and quantity. The coupled reactor includes a first cavity, an electrode assembly, and a microbubble generating unit. A filling structure is installed inside the first cavity for filling a catalyst. The microbubble generating unit is used to deliver microbubbles into the first cavity. The electrode assembly is used to apply a nanosecond pulsed electric field to the first cavity. The ultraviolet-assisted catalytic device is used to apply ultraviolet light to landfill leachate for secondary pollutant degradation; The clear water tank is equipped with a water quality testing device, which is used to monitor the water quality of the liquid in the clear water tank online.

[0015] As a further improvement to the above technical solution, the ultraviolet-assisted catalysis device includes a second cavity and a plurality of ultraviolet lamps, the plurality of ultraviolet lamps being arranged at intervals on the second cavity, and the inner wall of the second cavity being provided with a photocatalytic coating; And / or, the water quality testing device includes a COD sensor, an ammonia nitrogen sensor, a conductivity sensor, and a pH sensor.

[0016] As a further improvement to the above technical solution, the pretreatment equalization tank includes a tank body, a screen, a stirrer, a sludge collection slope, and a sludge discharge valve. The screen, the stirrer, and the sludge collection slope are installed in the tank body from top to bottom. The screen is used to intercept suspended particulate matter and large molecular flocs in the landfill leachate. The sludge discharge valve is installed at the bottom of the tank body and is used to discharge sludge. And / or, the electrode assembly includes several sets of needle-plate electrode assemblies, each set of needle-plate electrode assemblies including a needle electrode and a plate electrode, wherein the needle electrode and the plate electrode are respectively installed inside the first cavity.

[0017] The beneficial effects of this invention are as follows: The catalyst provided by this invention has a stable structure and outstanding catalytic performance. Combined with the synergistic effect of microbubbles and nanosecond pulsed electric fields, a robust Co-Al-O active interface is formed, improving electron transfer efficiency, maintaining high activity, and reducing the amount of active metal leaching, thus lowering the cost of packing material replacement. It also exhibits broad-spectrum and thorough pollutant degradation, making it suitable for a wide range of applications.

[0018] The landfill leachate treatment method provided by this invention relies on the synergistic oxidation of high-energy electrons, multi-level active free radicals, and ultraviolet light to efficiently mineralize humic substances and recalcitrant macromolecular organic matter in aged landfill leachate, which is beneficial for the deep removal of trace new pollutants. It is also adaptable to the treatment of sulfonamide pharmaceutical wastewater containing sulfamethoxazole, and is resistant to high-pollution water quality shock loads. The multi-field coupled synergistic oxidation mechanism is well-developed, resulting in high treatment efficiency. It solves the problems of insufficient degradation and high reagent consumption associated with single oxidation processes.

[0019] The landfill leachate treatment system provided by this invention features integrated and modular equipment with strong engineering feasibility. The overall system adopts a container-integrated structure, requiring minimal space and allowing for hoisting and transportation. It is suitable for small and medium-sized landfills, decentralized pharmaceutical companies, and other scenarios without civil engineering support, minimizing the need for manual operation. It boasts low operating costs and is environmentally friendly. The process eliminates the need for large-scale addition of acids, alkalis, iron salts, or other reagents, resulting in a low risk of secondary pollution. Improved catalyst stability further reduces overall energy consumption, consumable costs, and maintenance costs, making it highly valuable for industrialization and promotion. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the synthesis method of the catalyst in Example 1; Figure 2 This is a schematic diagram of the leachate treatment system in Example 1; Figure 3 This is a schematic diagram of the pretreatment equalization tank of the leachate treatment system in Example 1; Figure 4This is a schematic diagram of the coupled reactor in the leachate treatment system of Example 1; Figure 5 This is a schematic diagram of the ultraviolet-assisted catalytic device in the leachate treatment system of Example 1; Figure 6 This is a schematic diagram of the clear water tank in the leachate treatment system of Example 1; Figure 7 XRD, FTIR, and SEM images of the catalyst in Example 1; Figure 8 The graphs show the SMX degradation performance of the catalyst in Example 4, the degradation performance under different anion additions, different pH values, different antibiotic types, and multiple cycle conditions. In the attached diagram: 1-Pretreatment equalization tank; 11-Inlet; 12-Bar; 13-Agitator; 14-Sludge collection slope; 15-Sludge discharge valve; 2-Coupled reactor; 21-Loading structure; 22-Needle plate electrode assembly; 23-Microbubble generating unit; 3-UV-assisted catalysis device; 31-UV lamp; 32-Photocatalytic coating; 33-Second chamber; 4-Clear water tank; 41-COD sensor; 42-Ammonia nitrogen sensor; 43-Conductivity sensor; 44-pH sensor; 5-Container. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. The described embodiments are only preferred embodiments of the present invention and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0022] This embodiment relates to a method for synthesizing a catalyst, including the following steps: Spherical γ-phase alumina was immersed in a divalent cobalt chloride aqueous solution, and the solid was dried to obtain the first spherical modified alumina. The first spherical modified alumina was modified using microbubbles and nanosecond pulsed electric fields to obtain the second spherical modified alumina. The second spherical modified alumina was calcined to obtain the catalyst.

[0023] The catalyst provided in this embodiment has a stable structure and outstanding catalytic performance. Combined with the synergistic effect of microbubbles and nanosecond pulsed electric fields, a robust Co-Al-O active interface is formed, with an electron transfer coefficient α ≥ 0.8. The electron transfer efficiency is more than 40% higher than that of ordinary commercial alumina catalysts. After 100 batches of continuous operation, the activity retention rate is ≥ 85%, and the amount of active metal leaching is extremely low, significantly reducing the cost of packing replacement.

[0024] In some embodiments, the mass ratio of cobalt ions in the divalent cobalt chloride aqueous solution to the spherical γ-phase alumina is 1:10.

[0025] In some embodiments, the spherical γ-phase alumina has a particle size of 2 mm-4 mm and a specific surface area greater than or equal to 220 m². 2 / g, porosity of 50%-60%, and average pore size of 30 nm-50 nm.

[0026] In some embodiments, in the modification of the first spherical modified alumina using microbubbles and nanosecond pulsed electric fields, the parameters of the microbubbles include: an average diameter of 30 μm-80 μm, an absolute value of a Zeta potential greater than or equal to 50 mV, and a bubble number density of 5 × 10⁻⁶. 8 5 x 10 units / L 10 Units / L; The parameters of the nanosecond pulse electric field include: voltage of 5 kV-30 kV, pulse width of 10 ns-100 ns, frequency of 100 Hz-1000 Hz, and field strength greater than or equal to 106 V / m; The modification time is 2 h-4 h.

[0027] This embodiment relates to a catalyst, which is prepared by the catalyst synthesis method described above.

[0028] This embodiment relates to a method for treating landfill leachate, including the following steps: Pretreatment: The landfill leachate is pretreated to obtain the first treated liquid; Catalytic degradation: The first treatment liquid is brought into contact with the catalyst described above, and microbubbles and nanosecond pulse electric fields are applied to the first treatment liquid to perform the first pollutant degradation, resulting in the second treatment liquid; Ultraviolet degradation: Ultraviolet light is applied to the second treatment solution to degrade the pollutants for the second time, resulting in a third treatment solution; The water quality of the third treatment liquid is monitored online. According to the preset water quality compliance rules, when the water quality of the third treatment liquid meets the standards, the third treatment liquid is discharged. When the water quality of the third treatment liquid does not meet the standards, the pretreatment, catalytic degradation and ultraviolet degradation steps are repeated.

[0029] The landfill leachate treatment method provided in this embodiment offers broad-spectrum and thorough pollutant degradation and is applicable to a wide range of scenarios. Utilizing high-energy electrons, multi-level active free radicals, and synergistic ultraviolet oxidation, it efficiently mineralizes humic substances and recalcitrant macromolecular organic matter in aged landfill leachate, and deeply removes trace amounts of new pollutants. Simultaneously, it is adaptable to the treatment of sulfonamide pharmaceutical wastewater containing sulfamethoxazole, and is resistant to high-pollution water quality shock loads. The multi-field coupled synergistic oxidation mechanism is well-developed, resulting in high treatment efficiency. The system allows for adjustment of microbubbles, pulsed electric fields, and ultraviolet conditions within a wide parameter range. The synergistic effect of the microbubble confined electric field, electron tunneling effect, and photocatalytic multi-oxidation system solves the problems of insufficient degradation and high reagent consumption associated with single oxidation processes.

[0030] In some embodiments, during the simultaneous application of microbubbles and a nanosecond pulsed electric field to the first treatment liquid for the first pollutant degradation, the parameters of the microbubbles include: an average diameter of 30 μm-80 μm, an absolute Zeta potential of 50 mV-80 mV, and a bubble number density of 5 × 10⁻⁶. 8 5 x 10 units / L 10 per L.

[0031] Reference Figures 2 to 6 This embodiment relates to a landfill leachate treatment system, which includes: Container 5, wherein a pretreatment conditioning tank 1, a coupling reactor 2, an ultraviolet-assisted catalytic device 3 and a clear water tank 4 are sequentially connected inside the container 5, and a reflux unit is also provided to connect the outlet of the clear water tank 4 with the inlet 11 of the pretreatment conditioning tank 1. The pretreatment equalization tank 1 is used to intercept suspended particulate matter and large molecular flocs in landfill leachate and to balance water quality and quantity. The coupled reactor 2 includes a first cavity, an electrode assembly, and a microbubble generating unit 23. A filling structure 21 is installed inside the first cavity for filling a catalyst. The microbubble generating unit 23 is used to deliver microbubbles to the first cavity. The electrode assembly is used to apply a nanosecond pulsed electric field to the first cavity. The ultraviolet-assisted catalytic device 3 is used to apply ultraviolet light to landfill leachate for secondary pollutant degradation; The clear water tank 4 is equipped with a water quality detection device, which is used to monitor the water quality of the liquid in the clear water tank 4 online.

[0032] The landfill leachate treatment system provided in this embodiment is integrated and modular, making it highly adaptable to engineering applications. The overall system adopts a container-like integrated structure, requiring minimal space and allowing for hoisting and transportation, making it suitable for small and medium-sized landfills, decentralized pharmaceutical companies, and other scenarios without civil engineering support. The entire process is automatically controlled, minimizing the need for manual operation. It boasts low operating costs and is environmentally friendly. The process does not require large-scale addition of acids, alkalis, iron salts, or other reagents, resulting in a low risk of secondary pollution. The catalyst is long-lasting and stable, and the overall energy consumption, consumables, and maintenance costs are reduced by more than 30% compared to the traditional Fenton + membrane treatment process, making it highly valuable for industrialization.

[0033] Specifically, the landfill leachate treatment system is a container-type integrated structure with a modular design. The components and connections can be configured as follows: Pretreatment equalization tank 1: Corrosion-resistant steel tank body, hydraulic retention time 6 h-12 h; equipped with a 1 mm-3 mm slit mechanical bar 12 at the top, and a submersible agitator 13 with a stirring power of 0.15 kW / m² inside the tank. 3 -0.3 kW / m 3 The bottom of the pool is equipped with a 10°-15° inclined sludge collection slope 14 and a sludge discharge valve 15 to achieve water quality homogenization and suspended solids interception.

[0034] Coupled Reactor 2: The cylinder of the first chamber is made of 316L stainless steel, with a hydraulic residence time of 1.5 h-3 h. It is internally equipped with an adjustable needle-plate electrode assembly. The needle electrode is a titanium-based platinum-plated electrode, and the plate electrode is a 316L stainless steel porous plate. The electrode working surfaces are mirror-polished with a surface roughness Ra≤0.8 μm, and the electrode spacing is adjustable from 0.5 mm to 2 mm. A perforated gas and water distribution plate is installed at the bottom of the first chamber. The filling structure 21 has two layers of limiting sieves arranged above and below, with sieve openings less than 2 mm in diameter to trap catalyst particles. The catalyst filling rate is 60%-70%. The microbubble generating unit 23 uses a multi-stage shear vortex microbubble generator, integrating electrolyte conditioning and electrostatic potential control modules. The generator pipeline connects to the bottom of the reactor, allowing for online closed-loop adjustment of microbubble particle size, potential, and density parameters, and is coupled with a nanosecond pulse electric field.

[0035] UV-assisted catalytic device 3: Located downstream of coupled reactor 2, it has a built-in 254 nm low-pressure UV mercury lamp with a single lamp power of 25 W-35 W and a lamp tube spacing of 12 cm-18 cm; the inner wall is sprayed with a 10 nm-30 nm thick nano-TiO2 reflective catalytic coating 32, which generates active free radicals in synergy with UV light, and deeply degrades trace amounts of new pollutants.

[0036] The water quality testing device is equipped with online sensors for COD, ammonia nitrogen, pH, and conductivity, with control thresholds of COD ≤ 50 mg / L, ammonia nitrogen ≤ 1.5 mg / L, and pH 6-9. If the water quality exceeds the standard, the variable frequency reflux pump automatically starts, with a reflux flow rate of 0.3-0.8 times the influent flow rate. Clear water tank 4 is equipped with a high-low level interlock device; a high level activates the reflux unit, returning the water to pretreatment equalization tank 1, and a low level shuts down the pump. Clear water tank 4 has two pipelines: one for compliant discharge and the other connected to the reflux unit to form a closed-loop circulation. New pollutants are sampled offline and quantitatively tested in the laboratory.

[0037] Reference Figure 5 In some embodiments, the ultraviolet-assisted catalytic device 3 includes a second cavity 33 and a plurality of ultraviolet lamps 31, the plurality of ultraviolet lamps 31 being arranged at intervals on the second cavity 33, and the inner wall of the second cavity 33 being provided with a photocatalytic coating 32; Reference Figure 6 And / or, the water quality detection device includes a COD sensor 41, an ammonia nitrogen sensor 42, a conductivity sensor 43, and a pH sensor 44.

[0038] Reference Figure 3 In some embodiments, the pretreatment equalization tank 1 includes a tank body, a grid 12, an agitator 13, a sludge collection slope 14, and a sludge discharge valve 15. The grid 12, the agitator 13, and the sludge collection slope 14 are installed in the tank body from top to bottom. The grid 12 is used to intercept suspended particulate matter and large molecular flocs in the landfill leachate. The sludge discharge valve 15 is installed at the bottom of the tank body and is used to discharge sludge. Reference Figure 4 And / or, the electrode assembly includes several sets of needle-plate electrode assemblies 22, each set of needle-plate electrode assemblies 22 including a needle electrode and a plate electrode, the needle electrode and the plate electrode being respectively installed inside the first cavity.

[0039] The following pilot-scale tests were conducted on leachate from three municipal solid waste landfills in Guangzhou, Shenzhen, and Huizhou, as well as wastewater from a sulfonamide pharmaceutical factory in Guangdong. The test samples were all pretreated and nanofiltration effluents, characterized by high COD, extremely poor biodegradability, enrichment of new pollutants (including pharmaceuticals and personal care products, perfluorinated and polyfluoroalkyl substances, endocrine disruptors, plasticizers, flame retardants, sweeteners, etc.), and poor water quality stability. The tests precisely verified the practical application effect of the catalyst and integrated treatment system of this invention.

[0040] Unified instructions for the detection of trace new pollutants: HLB solid-phase extraction enrichment-UPLC-MS / MS triple quadrupole mass spectrometry MRM mode was used for detection; the total concentration of trace new pollutants in the text is the arithmetic sum of the concentrations of characteristic substances; the remaining large amount of trace unknown organic matter in the leachate without standards can only be qualitatively identified and is not included in the total concentration statistics; for sulfonamide pharmaceutical wastewater, only the concentration of the characteristic new pollutant sulfamethoxazole monomer is quantified. Example 1

[0041] Test water sample: Leachate from aged waste at a municipal solid waste landfill in Guangzhou, original solution pH=8.9, COD Cr The concentration was 880 mg / L, the ammonia nitrogen concentration was 38 mg / L, the total concentration of trace new pollutants was 152 μg / L (only the characteristic substances that can be accurately quantified and controlled are counted, and low-concentration unknown trace organic matter is not included in the summation), and the biodegradable BOD / COD ratio was ≈0.14.

[0042] The catalyst preparation method in this embodiment is as follows: spherical γ-phase alumina is immersed in a divalent cobalt chloride aqueous solution, the solid is dried, and the first spherical modified alumina is obtained; The first spherical modified alumina was modified using microbubbles and nanosecond pulsed electric fields to obtain the second spherical modified alumina. The second spherical modified alumina was calcined to obtain the catalyst.

[0043] The specific parameters and processing steps are as follows: A particle size of 3 mm and a specific surface area of ​​240 m² are selected. 2 Pure spherical γ-phase alumina with a porosity of 55% and an average pore size of 40 nm was sieved, rinsed three times with deionized water, and drained for later use. The mass ratio of divalent cobalt ions to alumina was 1:10. The alumina was stirred and impregnated at 220 r / min at room temperature for 24 h, followed by drying at 120℃ for 4 h. During the modification stage, the average diameter of microbubbles was 50 μm, the absolute value of the Zeta potential was 55 mV, and the bubble density was 1×10⁻⁶. 9 The voltage of the nanosecond high-voltage pulse electric field is 18 kV, the pulse width is 50 ns, the frequency is 500 Hz, and the field strength is 1.2 × 10⁻⁶. 6 The modification process, with a V / m and a modification time of 3 h, involves using a coupled reactor 2 to modify the first spherical modified alumina using microbubbles and a nanosecond pulsed electric field. The coupled reactor 2 continuously introduces atmospheric air at a rate of 0.2 L / min. During the calcination stage, the temperature is increased by 5 °C / min and the catalyst is calcined at a constant temperature of 550 °C for 6 h to obtain the catalyst.

[0044] The parameters of the landfill leachate treatment system in this embodiment are as follows: hydraulic retention time of pretreatment equalization tank 1 is 9 h, screen 12 has a slit size of 2 mm, and stirring power is 0.2 kW / m³. 3The reactor consists of a 12° slope for the mud collection slope 14; a multi-stage shear vortex shear generator 23, equipped with electrolyte conditioning and electrostatic control modules; the first chamber of the coupled reactor 2 is made of 316L stainless steel, with a hydraulic residence time of 2 h; the needle electrode has a titanium substrate rod diameter of 1.0 mm and a platinum coating of 10 μm; the 316L porous electrode plate has a thickness of 4 mm, an opening diameter of 3 mm, an opening rate of 38%, an electrode working surface Ra=0.6 μm, and a needle-plate electrode spacing of 1 mm; the bottom water distribution plate of the reactor has an opening diameter of 2 mm and an opening rate of 28%; the limiting sieve plate has an opening diameter of 1 mm; and the catalyst filling rate is 65%; the ultraviolet-assisted catalytic device 3 uses 254nm, 30W ultraviolet lamps 31 with a lamp spacing of 15 cm and an inner wall nano-TiO2 coating thickness of 20 μm; the clear water tank 4 has an effective volume of 0.6 times the reactor volume and is equipped with high and low liquid level float switches; the online water quality detection device is set with thresholds of COD≤50 mg / L and ammonia nitrogen≤1.5 mg / L. mg / L, pH 6-9, reflux flow rate is 0.5 times the influent flow rate, variable frequency pump operating frequency is 25 Hz, solenoid valve response time is 1 s, and trace amounts of new pollutants are detected offline daily.

[0045] Treatment process: The leachate stock solution is sent to the pretreatment equalization tank 1, where it passes through the screen 12, is stirred, homogenized, and stabilized to remove suspended impurities. Then, it flows by gravity into the coupled reactor 2, where the microbubble generator 23 and nanosecond high-voltage pulse electric field are activated simultaneously. The pollutants are degraded by relying on the electron enhancement effect of the catalyst micro-interface. The effluent enters the ultraviolet-assisted catalytic device 3 for further degradation and then flows into the clear water tank 4. The water quality monitoring device monitors the water quality in real time. If the indicators exceed the standards, the reflux unit is automatically activated to return the water to the pretreatment equalization tank 1 for recycling. Water samples are taken daily for offline verification of the removal effect of trace new pollutants.

[0046] Test results: After 10 hours of stable operation, the effluent COD... Cr =32 mg / L, ammonia nitrogen = 1.2 mg / L, total concentration of 26 trace new pollutants 0.3 μg / L; catalyst electron transfer coefficient α = 0.86. After 100 consecutive batches of operation, the catalyst activity retention rate was 88.1%. After 12 months of continuous operation, the system COD removal rate decreased from the initial 97.8% to 36.2%, and the new pollutant removal rate decreased from 100% to 17.5%. It is recommended to replace the catalyst every 12 months to ensure treatment effectiveness. Example 2

[0047] Test water sample: Leachate from aged waste at a municipal solid waste landfill in Shenzhen, original solution pH=8.5, COD CrThe concentration was 920 mg / L, the ammonia nitrogen concentration was 42 mg / L, the total concentration of 26 typical high-risk trace new pollutants was 165 μg / L (only the characteristic substances that can be accurately quantified and controlled are counted, and low-concentration unknown trace organic matter is not included in the summation), and the biodegradable BOD / COD ratio was ≈0.13.

[0048] The catalyst preparation method in this embodiment is as follows: spherical γ-phase alumina is immersed in a divalent cobalt chloride aqueous solution, the solid is dried, and the first spherical modified alumina is obtained; The first spherical modified alumina was modified using microbubbles and nanosecond pulsed electric fields to obtain the second spherical modified alumina. The second spherical modified alumina was calcined to obtain the catalyst.

[0049] The specific parameters and processing steps are as follows: Pure spherical γ-phase alumina with a particle size of 2 mm, a specific surface area of ​​220 m² / g, a porosity of 50%, and an average pore size of 30 nm is selected. After sieving, it is rinsed three times with deionized water and drained for later use. The mass ratio of divalent cobalt ions to alumina is 1:10. It is stirred and impregnated at room temperature at 200 r / min for 24 h, and then dried at 120 ℃ for 4 h. The microbubble average diameter is 30 μm, the absolute value of the Zeta potential is 50 mV, and the bubble density is 5×10⁻⁶. 8 Units / L, nanosecond high-voltage pulse electric field voltage 5kV, pulse width 10 ns, frequency 100 Hz, field strength 1×10 6 The modification process, with a V / m and a modification time of 2 h, involves using microbubbles and nanosecond pulsed electric fields to modify the first spherical modified alumina through a coupled reactor 2. The coupled reactor 2 continuously introduces atmospheric air at a rate of 0.1 L / min. During the calcination stage, the temperature is increased by 5 °C / min and calcined at 550 °C for 6 h to obtain the catalyst.

[0050] The parameters of the landfill leachate treatment system in this embodiment are as follows: hydraulic retention time of pretreatment equalization tank 1 is 6 h, screen 12 has a 1 mm gap, and stirring power is 0.15 kW / m³. 3The reactor consists of a 10° slope for the mud collection slope 14; a multi-stage shear vortex shear generator 23, equipped with electrolyte conditioning and electrostatic control modules; the first chamber of the coupled reactor 2 has a 316L stainless steel cylinder with a hydraulic residence time of 2 h; the needle electrode has a titanium substrate rod diameter of 0.8 mm and a platinum coating of 5 μm; the 316L porous electrode plate has a thickness of 3 mm, an opening diameter of 2 mm, an opening rate of 30%, an electrode working surface Ra=0.8 μm, and a needle-plate electrode spacing of 0.5 mm; the bottom water distribution plate of the coupled reactor 2 has an opening diameter of 1 mm and an opening rate of 20%; the limiting sieve plate has an opening diameter of 1 mm; and the catalyst filling rate is 60%; the ultraviolet-assisted catalytic device 3 uses a 254 nm, 25 W ultraviolet lamp 31 with a lamp spacing of 12 cm and an inner wall nano-TiO2 coating thickness of 10 μm; the clear water tank 4 has an effective volume of 0.4 times the reactor volume and is equipped with high and low liquid level float switches; the water quality detection device is set with a threshold COD≤50. mg / L, ammonia nitrogen ≤1.5 mg / L, pH 6-9, reflux flow rate is 0.3 times the influent flow rate, variable frequency pump operating frequency is 5 Hz, solenoid valve response time is 2s, and trace amounts of new pollutants are detected offline daily.

[0051] The equipment configuration and water treatment process are consistent with those in Example 1. Only the above-mentioned lower limit process parameters are adjusted. The catalyst ratio and basic preparation process are the same as those in Example 1 to verify the compatibility and stability of the catalyst and system under low parameter conditions of the present invention.

[0052] Test results: After 10 hours of stable operation, the effluent COD... Cr =42 mg / L, ammonia nitrogen = 1.8 mg / L, and the total concentration of 26 trace new pollutants was 0.48 μg / L, meeting the advanced emission standards; the catalyst electron transfer coefficient α = 0.81. After 100 batches of continuous operation, the catalyst activity retention rate was 85.3%. After 12 months of continuous operation, the system COD removal rate decreased from 96.5% to 34.8%, and the new pollutant removal rate decreased from 100% to 15.9%, showing good operational stability. Example 3

[0053] Test water sample: Leachate from aged waste at a municipal solid waste landfill in Huizhou, original solution pH=8.2, COD Cr The concentration was 1050 mg / L, the ammonia nitrogen concentration was 45 mg / L, and the total concentration of 26 typical high-risk trace new pollutants was 178 μg / L (only the characteristic substances that can be accurately quantified and controlled are counted, and low-concentration unknown trace organic matter is not included in the summation). The biodegradability BOD / COD ≈ 0.12, which is the highest level of pollution and the most difficult to treat.

[0054] The catalyst preparation method in this embodiment is as follows: spherical γ-phase alumina is immersed in a divalent cobalt chloride aqueous solution, the solid is dried, and the first spherical modified alumina is obtained; The first spherical modified alumina was modified using microbubbles and nanosecond pulsed electric fields to obtain the second spherical modified alumina. The second spherical modified alumina was calcined to obtain the catalyst.

[0055] The specific parameters and processing steps are as follows: A particle size of 4 mm and a specific surface area of ​​235 m² are selected. 2 Pure spherical γ-phase alumina with a porosity of 60% and an average pore size of 50 nm was sieved, rinsed three times with deionized water, and drained for later use. The mass ratio of divalent cobalt ions to alumina was 1:10. The alumina was stirred and impregnated at 250 r / min at room temperature for 24 h, followed by drying at 120 ℃ for 4 h. During the modification stage, the average diameter of the microbubbles was 80 μm, the absolute value of the Zeta potential was 62 mV, and the bubble density was 5 × 10⁻⁶. 10 Units / L, nanosecond high-voltage pulse electric field voltage 30 kV, pulse width 100 ns, frequency 1000 Hz, field strength 1.5×10 6 The modification process, with a V / m and a modification time of 4 h, involved using a coupled reactor 2 to modify the first spherical modified alumina using microbubbles and a nanosecond pulsed electric field. The coupled reactor 2 continuously introduced atmospheric air at a rate of 0.3 L / min. During the calcination stage, the temperature was increased by 5 °C / min and calcined at 550 °C for 6 h to obtain the catalyst.

[0056] The parameters of the landfill leachate treatment system in this embodiment are as follows: hydraulic retention time of pretreatment equalization tank 1 is 12 h, screen 12 has a slit size of 3 mm, and stirring power is 0.3 kW / m³. 3 The reactor consists of a 14-stage mud collection slope with a 15° gradient; a microbubble generating unit 23, a multi-stage shear vortex shear generator, equipped with electrolyte conditioning and electrostatic control modules; the first chamber of the coupled reactor 2 is made of 316L stainless steel, with a hydraulic residence time of 2 h; the needle electrode has a titanium substrate rod diameter of 1.2 mm and a platinum plating of 15 μm; the 316L porous electrode plate has a thickness of 6 mm, an opening diameter of 5 mm, an opening rate of 45%, an electrode working surface Ra=0.5 μm, and a needle-plate electrode spacing of 2 mm; the bottom water distribution plate of the reactor has an opening diameter of 3 mm and an opening rate of 35%; the limiting sieve plate has an opening diameter of 1 mm; and the catalyst filling rate is 70%; the ultraviolet auxiliary zone uses 254 nm, 35 W ultraviolet lamps 31 with a lamp spacing of 18 cm and an inner wall nano-TiO2 coating thickness of 30 μm; the clear water tank 4 has an effective volume 0.8 times the reactor volume and is equipped with high and low liquid level float switches; the water quality detection device is set with thresholds of COD≤50 mg / L and ammonia nitrogen≤1.5 mg / L. mg / L, pH 6-9, reflux flow rate is 0.8 times the influent flow rate, variable frequency pump operating frequency is 50 Hz, solenoid valve response time is 1 s, and trace amounts of new pollutants are detected offline daily.

[0057] The processing procedure is the same as in Example 1.

[0058] Test results: After 10 hours of stable operation, the effluent COD... Cr =28 mg / L, ammonia nitrogen = 1.0 mg / L, and the total concentration of 26 trace new pollutants was 0.28 μg / L, indicating the best pollutant degradation effect; the catalyst electron transfer coefficient α = 0.89. After 100 batches of continuous operation, the catalyst activity retention rate was 86.7%. After 12 months of continuous operation, the system COD removal rate decreased from 98.2% to 37.5%, and the new pollutant removal rate decreased from 100% to 18.3%, making it suitable for high-concentration leachate treatment scenarios. Example 4

[0059] Test water sample: Wastewater from a pharmaceutical factory in Guangdong Province, mainly containing sulfamethoxazole, a typical new antibiotic pollutant, belonging to highly toxic and difficult-to-degrade pharmaceutical wastewater; the original solution has a pH of 8.3 and a COD of [missing information]. Cr The concentration was 820 mg / L, the ammonia nitrogen concentration was 32 mg / L, the total concentration of sulfamethoxazole monomer was 1460 ng / L, the biodegradability BOD / COD≈0.11, the organic matter structure was stable and difficult to degrade by conventional biochemical processes.

[0060] The catalyst preparation method in this embodiment is as follows: spherical γ-phase alumina is immersed in a divalent cobalt chloride aqueous solution, the solid is dried, and the first spherical modified alumina is obtained; The first spherical modified alumina was modified using microbubbles and nanosecond pulsed electric fields to obtain the second spherical modified alumina. The second spherical modified alumina was calcined to obtain the catalyst.

[0061] The specific parameters and processing steps are as follows: A particle size of 3 mm and a specific surface area of ​​240 m² are selected. 2 Pure spherical γ-phase alumina with a porosity of 55% and an average pore size of 40 nm was sieved, rinsed three times with deionized water, and drained for later use. The mass ratio of divalent cobalt ions to alumina was 1:10. The alumina was stirred and impregnated at 220 r / min at room temperature for 24 h, followed by drying at 120 ℃ for 4 h. During the modification stage, the average diameter of microbubbles was 50 μm, the absolute value of the Zeta potential was 55 mV, and the bubble density was 1×10⁻⁶. 9 The voltage of the nanosecond high-voltage pulse electric field is 18 kV, the pulse width is 50 ns, the frequency is 500 Hz, and the field strength is 1.2 × 10⁻⁶. 6 The modification process, with a V / m and a modification time of 3 h, involves using a coupled reactor 2 to modify the first spherical modified alumina using microbubbles and a nanosecond pulsed electric field. The coupled reactor 2 continuously introduces atmospheric air at a rate of 0.2 L / min. During the calcination stage, the temperature is increased by 5 °C / min and the catalyst is calcined at a constant temperature of 550 °C for 6 h to obtain the catalyst.

[0062] The parameters of the landfill leachate treatment system in this embodiment are as follows: hydraulic retention time of pretreatment equalization tank 1 is 9 h, screen 12 has a slit size of 2 mm, and stirring power is 0.2 kW / m³. 3 The reactor consists of a 12° slope for the mud collection slope 14; a multi-stage shear vortex shear generator 23, equipped with electrolyte conditioning and electrostatic control modules; the first chamber of the coupled reactor 2 is made of 316L stainless steel, with a hydraulic residence time of 2 h; the needle electrode has a titanium substrate rod diameter of 1.0 mm and a platinum coating of 10 μm; the 316L porous electrode plate has a thickness of 4 mm, an opening diameter of 3 mm, an opening rate of 38%, an electrode working surface Ra=0.6 μm, and a needle-plate electrode spacing of 1 mm; the bottom water distribution plate of the reactor has an opening diameter of 2 mm and an opening rate of 28%; the limiting sieve plate has an opening diameter of 1 mm; and the catalyst filling rate is 65%; the ultraviolet-assisted catalytic device 3 uses a 254nm, 30W ultraviolet lamp 31 with a lamp spacing of 15 cm and an inner wall nano-TiO2 coating thickness of 20 μm; the clear water tank 4 has an effective volume of 0.6 times the reactor volume and is equipped with high and low liquid level float switches; the water quality detection device is set with a threshold COD≤50. mg / L, ammonia nitrogen ≤1.5mg / L, pH 6-9, reflux flow rate 0.5 times the influent flow rate, variable frequency pump operating frequency 25 Hz, solenoid valve response time 1 s, and daily offline monitoring of sulfamethoxazole residual concentration.

[0063] The equipment configuration and water treatment process are consistent with those in Example 1. The optimal process parameters of this invention are adopted, and the sulfamethoxazole benzene ring and sulfonamide bond are broken by utilizing the micro-interface electronic tunneling effect to achieve efficient degradation of special pharmaceutical recalcitrant pollutants, thus verifying the cross-border industrial wastewater adaptability of this invention.

[0064] Test results: After 10 hours of stable operation, the effluent COD... Cr =30 mg / L, ammonia nitrogen = 1.1 mg / L, sulfamethoxazole residual total concentration 25 ng / L, excellent degradation effect of special drug pollutants; catalyst electron transfer coefficient α = 0.85. After 100 batches of continuous operation, the catalyst activity retention rate was 87.5%. After 12 months of continuous operation, the system COD removal rate decreased from 97.5% to 35.8%, and the removal rate of new characteristic pollutants of sulfonamides decreased from 100% to 16.9%, which can be stably adapted to the deep treatment of sulfonamide pharmaceutical wastewater. Comparative Example 1

[0065] Test water sample: leachate from old waste at a municipal solid waste landfill in Guangzhou. The original liquid had a pH of 8.9, a CODcr concentration of 880 mg / L, an ammonia nitrogen concentration of 38 mg / L, and a total concentration of trace new pollutants of 152 μg / L (only the characteristic substances that can be accurately quantified and controlled are counted; low-concentration unknown trace organic matter is not included in the summation). The biodegradable BOD / COD ratio was approximately 0.14.

[0066] The comparative catalyst preparation method is as follows: spherical γ-phase alumina is immersed in a divalent cobalt chloride aqueous solution, the solid is dried, and the catalyst is obtained.

[0067] The specific parameters and processing steps are as follows: A particle size of 3 mm and a specific surface area of ​​240 m² are selected. 2 / g, pure spherical γ-phase alumina with a porosity of 55% and an average pore size of 40 nm was sieved, rinsed three times with deionized water, and drained for later use; the mass ratio of divalent cobalt ions to alumina was 1:10, and the mixture was stirred and impregnated at 220 r / min at room temperature for 24 h, followed by drying at 120 ℃ for 4 h to obtain the catalyst.

[0068] The parameters of this comparative landfill leachate treatment system are as follows: hydraulic retention time of pretreatment equalization tank 1 is 9 h, screen 12 has a 2 mm slit, and stirring power is 0.2 kW / m³. 3 The mud collection slope 14 has a slope of 12°; the catalyst filling rate is 65%; the ultraviolet-assisted catalytic device 3 uses 254 nm, 30 W ultraviolet lamps 31 with a lamp spacing of 15 cm and an inner wall nano-TiO2 coating thickness of 20 μm; the clear water tank 4 has an effective volume of 0.6 times the reactor volume and is equipped with high and low liquid level float switches; the online water quality detection device is set with thresholds of COD≤50mg / L, ammonia nitrogen≤1.5 mg / L, pH6-9, reflux flow rate of 0.5 times the influent flow rate, variable frequency pump operating frequency of 25 Hz, solenoid valve response time of 1 s, and daily offline detection of trace new pollutants.

[0069] Treatment process: The leachate stock solution is sent to the pretreatment equalization tank 1, where it passes through the screen 12, is stirred, homogenized, and stabilized to remove suspended impurities. The effluent then enters the ultraviolet-assisted catalytic device 3 for synergistic deep degradation and subsequently flows into the clear water tank 4. The water quality monitoring device monitors the water quality in real time. If the indicators exceed the standards, the reflux unit is automatically activated to return the water to the pretreatment equalization tank 1 for recycling. Water samples are taken daily for offline verification of the removal effect of trace new pollutants.

[0070] Test results: After 10 hours of stable operation, the effluent COD... Cr =548 mg / L, ammonia nitrogen = 33.6 mg / L, total concentration of 26 trace new pollutants 1.21 μg / L; catalyst electron transfer coefficient α = 0.31. After 100 consecutive batches of operation, the catalyst activity retention rate was 60.5%. After 12 months of continuous operation, the system COD removal rate decreased from the initial 37.7% to 17.3%, and the new pollutant removal rate decreased from 20.4% to 7.2%, indicating rapid catalyst deactivation, which could not meet the requirements for deep treatment of leachate.

[0071] Reference Figure 7 and Figure 8 , Figure 7The images shown are XRD, FTIR, and SEM images of the catalyst in Example 1. Figure 8 The graphs show the SMX degradation performance of the catalyst in Example 4, the degradation performance under different anion additions, different pH values, different antibiotic types, and multiple cycle conditions. Figure 7 Figures (a), (b), and (c) in the figure show the morphology and structural characteristics of the catalyst; Figure 8 Figure (a) shows the performance difference between the catalyst and Co-γ-Al2O3 without micro-interface electronic enhancement modification. Figure 8 Figures (b) and (c) show that the catalyst still exhibits strong catalytic degradation efficiency under different anion interference conditions. Figure 8 Figure (d) shows that the catalyst still has strong catalytic degradation efficiency under excessively acidic or alkaline conditions. Figure 8 Figure (e) shows that, in addition to SMX, the catalyst exhibits strong catalytic degradation efficiency for antibiotics or organic compounds such as sulfanilamide (SNZ), sulfadiazine (SMZ), sulfadimidine (SMT), sulfamethoxazole (SIX), norfloxacin (NOR), metronidazole (MTZ), carbamazepine (CBZ), rhodamine B (RhB), and methylene blue (MB). Figure 8 Figure (f) shows that the catalyst still has strong catalytic degradation efficiency after 100 cycles.

[0072] Five examples and comparative studies with different parameters and wastewater types clearly demonstrate that the cobalt-based catalyst prepared by micro-interface electronic enhancement modification in this invention has a wide parameter adaptation range, high catalytic efficiency, and excellent operational stability. The accompanying landfill leachate treatment system exhibits strong structural compatibility, a large adjustable operating range, and outstanding resistance to water quality shock loads. This invention can stably achieve deep degradation of recalcitrant organic matter and trace amounts of new pollutants in aged landfill leachate under all operating conditions (lower limit, optimal, and upper limit of parameters). It is also effectively adaptable to the deep treatment of recalcitrant pharmaceutical wastewater containing sulfamethoxazole, demonstrating strong versatility and wide applicability. Compared to traditional water treatment processes, this invention achieves thorough pollutant degradation, high electron transfer efficiency, and excellent long-term catalyst activity retention. It effectively solves the technical bottlenecks of existing technologies, such as poor adaptability to operating conditions, easy catalyst deactivation, and difficulty in completely removing trace amounts of new pollutants and special drug pollutants. The overall technical advantages are significant, the operational reliability is high, and it possesses extremely high engineering application value and industrialization prospects.

[0073] The preferred embodiments of the present invention have been described in detail above, but the present disclosure is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of the present disclosure.

Claims

1. A method for synthesizing a catalyst, characterized in that, Includes the following steps: Spherical γ-phase alumina was impregnated in an aqueous solution of divalent cobalt chloride, and the solid was dried to obtain the first spherical modified alumina. The first spherical modified alumina was modified using microbubbles and nanosecond pulsed electric fields to obtain the second spherical modified alumina. The second spherical modified alumina was calcined to obtain the catalyst.

2. The method for synthesizing the catalyst according to claim 1, characterized in that: The mass ratio of cobalt ions in the divalent cobalt chloride aqueous solution to the spherical γ-phase alumina is 1:

10.

3. The method for synthesizing the catalyst according to claim 1, characterized in that: The spherical γ-phase alumina has a particle size of 2 mm-4 mm and a specific surface area greater than or equal to 220 m². 2 / g, porosity of 50%-60%, and average pore size of 30 nm-50 nm.

4. The method for synthesizing the catalyst according to claim 1, characterized in that: The modification of the first spherical modified alumina is performed using microbubbles and nanosecond pulsed electric fields. The parameters of the microbubbles include: an average diameter of 30 μm-80 μm, an absolute value of Zeta potential greater than or equal to 50 mV, and a bubble number density of 5 × 10⁻⁶. 8 5 x 10 units / L 10 Units / L; The parameters of the nanosecond pulse electric field include: voltage of 5 kV-30 kV, pulse width of 10 ns-100 ns, frequency of 100Hz-1000 Hz, and field strength greater than or equal to 106 V / m; The modification time is 2 h-4 h.

5. A catalyst, characterized in that: The catalyst is prepared by the synthesis method of the catalyst according to any one of claims 1-4.

6. A method for treating landfill leachate, characterized in that, Includes the following steps: Pretreatment: The landfill leachate is pretreated to obtain the first treated liquid; Catalytic degradation: The first treatment liquid is contacted with the catalyst described in claim 5, and microbubbles and nanosecond pulse electric fields are applied to the first treatment liquid to perform the first pollutant degradation, thereby obtaining the second treatment liquid; Ultraviolet degradation: Ultraviolet light is applied to the second treatment solution to degrade the pollutants for the second time, resulting in a third treatment solution; The water quality of the third treatment liquid is monitored online. According to the preset water quality compliance rules, when the water quality of the third treatment liquid meets the standards, the third treatment liquid is discharged. When the water quality of the third treatment liquid does not meet the standards, the pretreatment, catalytic degradation and ultraviolet degradation steps are repeated.

7. The landfill leachate treatment method according to claim 6, characterized in that: In the process of simultaneously applying microbubbles and a nanosecond pulsed electric field to the first treatment liquid for the first pollutant degradation, the parameters of the microbubbles include: an average diameter of 30 μm-80 μm, an absolute value of zeta potential of 50 mV-80 mV, and a bubble number density of 5 × 10⁻⁶. 8 5 x 10 units / L 10 per L.

8. A landfill leachate treatment system, characterized in that, The landfill leachate treatment system includes: The container (5) is provided with a pretreatment conditioning tank (1), a coupling reactor (2), an ultraviolet-assisted catalytic device (3) and a clear water tank (4) connected in sequence inside the container (5). It is also provided with a reflux unit that connects the outlet of the clear water tank (4) with the inlet (11) of the pretreatment conditioning tank (1). The pretreatment equalization tank (1) is used to intercept suspended particulate matter and large molecular flocs in landfill leachate and to balance water quality and quantity. The coupled reactor (2) includes a first cavity, an electrode assembly and a microbubble generating unit (23). A filling structure (21) is installed inside the first cavity. The filling structure (21) is used to fill the catalyst. The microbubble generating unit (23) is used to deliver microbubbles to the first cavity. The electrode assembly is used to apply a nanosecond pulse electric field to the first cavity. The ultraviolet-assisted catalytic device (3) is used to apply ultraviolet light to the landfill leachate for secondary pollutant degradation; The clear water tank (4) is equipped with a water quality detection device, which is used to monitor the water quality of the liquid in the clear water tank (4) online.

9. The landfill leachate treatment system according to claim 8, characterized in that: The ultraviolet-assisted catalytic device (3) includes a second cavity (33) and a plurality of ultraviolet lamps (31). The plurality of ultraviolet lamps (31) are arranged at intervals on the second cavity (33). The inner wall of the second cavity (33) is provided with a photocatalytic coating (32). And / or, the water quality detection device includes a COD sensor (41), an ammonia nitrogen sensor (42), a conductivity sensor (43), and a pH sensor (44).

10. The landfill leachate treatment system according to claim 8, characterized in that: The pretreatment equalization tank (1) includes a tank body, a screen (12), a stirrer (13), a sludge collection slope (14), and a sludge discharge valve (15). The screen (12), the stirrer (13), and the sludge collection slope (14) are installed in the tank body from top to bottom. The screen (12) is used to intercept suspended particulate matter and large molecular flocs in the landfill leachate. The sludge discharge valve (15) is installed at the bottom of the tank body and is used to discharge sludge. And / or, the electrode assembly includes several sets of needle-plate electrode assemblies (22), each set of needle-plate electrode assemblies (22) includes a needle electrode and a plate electrode, the needle electrode and the plate electrode being respectively installed inside the first cavity.

Images