A cascade treatment system and method for aquaculture wastewater based on photoelectrocatalytic degradation

Abstract

The present invention belongs to the field of wastewater treatment technology, and specifically relates to a cascade treatment system and method for aquaculture wastewater based on photoelectrocatalytic degradation. The system includes: a solid-liquid separation device, a photoelectrocatalytic decomposition device, and a capacitive deionization device; the solid-liquid separation device is used to perform solid-liquid separation on aquaculture wastewater to obtain solid waste residue and waste liquid; the photoelectrocatalytic decomposition device is used to perform photoelectrocatalytic degradation on the waste liquid to remove organic matter in the waste liquid. The anode of the photoelectrocatalytic decomposition device is a composite photocatalyst, and the cathode is a modified activated biochar. The anode is used to catalytically degrade the organic matter in the waste liquid during photoelectrocatalytic degradation, and the cathode is used to provide active sites during photoelectrocatalytic degradation; the capacitive deionization device is used to remove charged particles from the waste liquid discharged from the photoelectrocatalytic decomposition device to remove organic matter. The system described in the present invention can be used to separate aquaculture wastewater with high turbidity step by step, achieving more efficient and energy-saving sewage degradation.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and specifically to a cascade treatment system and method for aquaculture wastewater based on photoelectrocatalytic degradation, and in particular to a cascade treatment system and method for aquaculture wastewater combining photoelectrocatalytic degradation and capacitive deionization technology. Background Art

[0002] The organic matter (COD) concentration in aquaculture wastewater is as high as 3,000-12,000 mg / L, the ammonia nitrogen concentration is as high as 800-3,000 mg / L, the organic phosphorus content is as high as 20-500 mg / L, the suspended solids (SS) exceeds the standard by dozens of times, the color is dark, and it contains a large number of bacteria, with high protein and polysaccharide content. Aquaculture wastewater not only contains a large amount of nutrients such as nitrogen, phosphorus, and potassium required for plant growth, but also contains medium and trace elements such as calcium, magnesium, sulfur, iron, copper, manganese, and zinc. Anaerobic treatment and subsequent utilization of aquaculture wastewater is a good method for harmless treatment of aquaculture wastewater. However, the return of its liquid product, biogas slurry, to farmland needs to consider the carrying capacity of the land. Excessive application can lead to pollution of farmland soil and water bodies. Excessive aquaculture wastewater requires advanced treatment to meet emission standards in some regions. The main methods of advanced treatment include coagulation, electrolysis, chemical oxidation, photoelectrocatalytic degradation, and capacitive deionization technology. Among them, coagulation is the process of adding coagulants to aggregate substances that are difficult to precipitate naturally and fine suspended matter in wastewater into larger particles for separation. Its biggest disadvantage is that coagulation is difficult to remove soluble substances and trace organic matter, and coagulation generally requires chemical additives. Chemical oxidation requires the addition of various reagents to convert difficult-to-degrade organic matter into easily degradable organic matter, or to completely oxidize organic matter. Due to the addition of chemical reagents, the degradation cost will be greatly increased due to factors such as the amount of sewage and sewage concentration. Electrolysis degrades pollutants under the action of direct current, but it requires better catalytic performance support. At the same time, the preparation cost of the anode and cathode is high and the power consumption is large. Summary of the Invention

[0003] The purpose of the present invention is to address the defects of the prior art in the treatment of aquaculture wastewater, such as poor treatment effect and high treatment cost, and thus propose a cascade treatment system and method for aquaculture wastewater based on photoelectrocatalytic degradation. The present invention first removes particulate matter in aquaculture wastewater through a solid-liquid separation device, and then sends the waste liquid obtained by solid-liquid separation into a photoelectrocatalytic decomposition device with modified activated biochar as the cathode and a composite photocatalyst as the anode for treatment to remove organic matter in the wastewater. Finally, the wastewater that has undergone photoelectrocatalytic degradation is transported to a capacitive deionization device to further remove charged particles in the wastewater, thereby promoting the deep treatment and high-standard discharge of difficult-to-degrade aquaculture wastewater. Using the present invention to treat aquaculture wastewater can achieve a more efficient, more environmentally friendly, and more energy-saving sewage treatment effect.

[0004] Photoelectrocatalysis, as a novel chemical treatment technology, offers advantages in removing organic pollutants, such as high mineralization rates and rapid degradation rates. Capacitive deionization (CDI) is considered a promising method for removing charged particles from solutions due to its environmental friendliness, high energy efficiency, and convenient electrode regeneration.

[0005] The key to photoelectrocatalytic degradation and capacitive deionization technologies lies in the catalytic and enrichment properties of activated biochar. The pore structure of biochar is the primary reason for the varying photoelectrochemical properties of its corresponding devices. Ideal photoelectrocatalytic biochar materials require a well-developed pore structure, abundant surface active sites, and stable electrochemical performance. Nano-defective TiO2 not only meets these requirements but also exhibits excellent photocorrosion resistance, making it widely applicable in environmental treatment and photocatalytic organic synthesis. Compared to conventional TiO2 electrodes, composite photocatalyst BC-TiO2 anodes offer higher surface area and catalytic degradation activity, enabling more effective removal of organic compounds such as hydrocarbons, phenols, and heterocyclic compounds from wastewater. A variety of coexisting nutrient ions are present in aquaculture wastewater. Coexisting cations or anions of the same charge compete with target nutrient ions for capacitive adsorption, occupying active sites. This leads to common ion effects and cycling stability issues in biochar electrodes, limiting the industrial application of biochar flow electrode capacitive adsorption technology for aquaculture wastewater treatment. Biochar generally has a rich pore structure and a high specific surface area, and has good molecular adsorption capabilities. It can adsorb elements such as nitrogen and oxygen in the micropores to improve its catalytic performance. Compared with ordinary biochar, the pore structure of biochar doped with heteroatoms is significantly improved. At the same time, due to the introduction of heteroatoms, more active sites will appear on the surface of biochar, and the surface wettability will also be improved. Under the synergistic effect of these factors, the catalytic and capacitive adsorption properties of biochar will be greatly improved. The ideal capacitor biochar electrode material needs to have a large specific surface area, suitable pore size distribution, high conductivity, good hydrophilicity and stable electrochemical properties. However, through a series of modification methods, the performance of biochar can be regulated to meet the needs of capacitor materials.

[0006] The first aspect of the present invention proposes a cascade treatment system for aquaculture wastewater based on photoelectrocatalytic degradation, which includes: a solid-liquid separation device, a photoelectrocatalytic decomposition device and a capacitive deionization device; the solid-liquid separation device is used to perform solid-liquid separation on aquaculture wastewater to obtain solid waste residue and waste liquid; the photoelectrocatalytic decomposition device is used to perform photoelectrocatalytic degradation on the waste liquid obtained in the solid-liquid separation device to remove organic matter in the waste liquid, the anode material in the photoelectrocatalytic decomposition device is a composite photocatalyst, and the cathode material is modified activated biochar, the anode is used to catalytically degrade the organic matter in the waste liquid during photoelectrocatalytic degradation, and the cathode is used to provide active sites during photoelectrocatalytic degradation; the capacitive deionization device is used to remove charged particles from the waste liquid for removing organic matter discharged from the photoelectrocatalytic decomposition device.

[0007] The second aspect of the present invention proposes a cascade treatment method for aquaculture wastewater based on photoelectrocatalytic degradation, the method comprising:

[0008] The aquaculture wastewater is separated into solid and liquid in a solid-liquid separation device to obtain solid waste residue and waste liquid;

[0009] The waste liquid is transported to a photoelectrocatalytic decomposition device, and a light source is applied to the photoelectrocatalytic decomposition device. The anode material of the photoelectrocatalytic decomposition device is a composite photocatalyst, and the cathode material is modified activated biochar. The anode is used to catalytically degrade organic matter in the waste liquid during photoelectrocatalytic degradation, and the cathode is used to provide active sites during photoelectrocatalytic degradation.

[0010] The waste liquid discharged from the photoelectrocatalytic decomposition device for removing organic matter is input into a capacitive deionization device for removal of charged particles to obtain treated wastewater.

[0011] The aquaculture wastewater cascade treatment system and method based on photoelectrocatalytic degradation described in the present invention has at least the following beneficial effects:

[0012] (1) In the present invention, a degradation method of solid-liquid separation and photoelectrocatalytic batch treatment is adopted to achieve the step-by-step separation of aquaculture wastewater with high COD and high turbidity, which can effectively ensure that the number of suspended particles in the electrolytic cell is small, effectively extend the service life of the electrode, and improve the photoelectrocatalytic degradation ability of the electrolytic cell. Finally, the charged particles remaining after the photoelectrocatalytic treatment are effectively treated by a capacitive deionization device, thereby further purifying the water quality at a low cost and ensuring the efficiency and stability of aquaculture wastewater treatment.

[0013] (2) In a preferred embodiment, the present invention uses modified activated biochar prepared by nitrogen-sulfur co-doping and oxygen introduction as the cathode material, which can greatly reduce the cost of photoelectrocatalysis and improve the ability to oxidize and degrade organic matter in aquaculture wastewater, thereby achieving more efficient and energy-saving wastewater degradation;

[0014] (3) In a preferred embodiment, the present invention uses a composite photocatalytic material BC-TiO2 prepared by a sol-gel method as an anode for photoelectrocatalytic degradation. Under the load of biochar with a good pore structure, it can effectively inhibit the recombination of photogenerated electron-hole pairs, while expanding the light absorption range, increasing the light absorption intensity, and greatly improving the photocatalytic performance, thereby achieving a more efficient, more environmentally friendly, and more energy-saving sewage treatment effect;

[0015] (4) In the preferred case, using zinc-loaded, nitrogen-boron co-doped activated biochar as the polar material in the capacitive deionization device can improve the ion removal efficiency, increase the stability, and have a higher specific capacitance and superior rate performance for the capacitive deionization device;

[0016] (5) Under optimal conditions, the friction angle principle is used to set up a preliminary solid-liquid separation device, and combined with the multi-stage filtration principle, it not only reduces the pressure of the aquaculture wastewater during the step-by-step filtration process and prevents the accumulation of solid residues, but also improves the efficiency of the filtration process, provides favorable conditions for the subsequent photoelectric degradation and deionization treatment, and achieves more efficient, energy-saving and stable sewage degradation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a structural diagram of a cascade treatment system for aquaculture wastewater based on photoelectrocatalytic degradation in the present invention.

[0018] Reference numerals

[0019] 1. Solid-liquid separation device; 2. Photoelectrocatalytic decomposition device; 3. Capacitive deionization device; 4. Primary solid-liquid separation component; 5. Secondary solid-liquid separation component; 6. First connecting pipe; 7. Screen; 8. Corundum layer; 9. Quartz sand layer; 10. Filter cloth layer; 11. Activated carbon layer; 12. Anode; 13. Cathode; 14. Ultraviolet light source; 15. Faraday electrode cathode; 16. Faraday electrode anode; 17. Cation exchange membrane; 18. Anion exchange membrane; 19. First diverter valve; 20. Pump; 21. Second connecting pipe; 22. Second diverter valve; 23. Valve. DETAILED DESCRIPTION

[0020] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0021] The first aspect of the present invention proposes a cascade treatment system for aquaculture wastewater based on photoelectrocatalytic degradation, such as Figure 1As shown, the system includes: a solid-liquid separation device 1, a photoelectrocatalytic decomposition device 2 and a capacitive deionization device 3; the solid-liquid separation device 1 is used to perform solid-liquid separation on aquaculture wastewater to obtain solid waste residue and waste liquid; the photoelectrocatalytic decomposition device 2 is used to perform photoelectrocatalytic degradation on the waste liquid obtained in the solid-liquid separation device 1 to remove organic matter in the waste liquid. The anode 12 material of the photoelectrocatalytic decomposition device 2 is a composite photocatalyst, and the cathode 13 material is modified activated biochar. The anode 12 is used to catalytically degrade the organic matter in the waste liquid during photoelectrocatalytic degradation, and the cathode 13 is used to provide more active sites in the photoelectrocatalytic degradation, and utilize catalytic performance to improve degradation efficiency; the capacitive deionization device 3 is used to remove charged particles from the waste liquid for removing organic matter discharged from the photoelectrocatalytic decomposition device 2.

[0022] In the above technical solution, the top of the solid-liquid separation device 1 has an aquaculture wastewater inlet, and the interior of the solid-liquid separation device 1 is provided with a first-level solid-liquid separation component 4 and a second-level solid-liquid separation component 5 located below the first-level solid-liquid separation component. The aquaculture wastewater inlet is located directly above the first-level solid-liquid separation component 4, and the particle size of the solid waste residue filtered out from the first-level solid-liquid separation component 4 is larger than the particle size of the solid waste residue filtered out from the second-level solid-liquid separation component 5; the output end of the second-level solid-liquid separation component 5 is connected to the photoelectrocatalytic decomposition device 2 through a first connecting pipe 6, and the bottom of the solid-liquid separation device 1 has a solid waste residue outlet. During the specific operation process, the aquaculture wastewater enters from the aquaculture wastewater inlet at the top of the solid-liquid separation device 1, and first passes through the first-level solid-liquid separation component 4 located above for preliminary solid-liquid separation to obtain a mixed liquid containing small particles and solid particles. The solid particles are discharged from the solid waste residue outlet at the bottom and collected for utilization (the solid particle waste residue obtained by separation can be fermented and made into fertilizer, or roller-dried and made into fuel). Then, the mixed liquid containing small particles enters the second-level solid-liquid separation component 5 to complete more refined filtration to obtain solid waste residue and waste liquid. The solid waste residue continues to be discharged from the solid waste residue outlet at the bottom of the solid-liquid separation device 1 and collected for utilization, and the waste liquid enters the photoelectrocatalytic decomposition device 2 through the first connecting pipe 6.

[0023] The first-level solid-liquid separation component 4 includes multiple layers of screens 7 arranged in sequence from top to bottom, and the aperture of each layer of screen 7 gradually decreases from the upper layer to the lower layer. For example, the aperture of each layer of screen 7 is 30 mesh, 50 mesh and 70 mesh from the upper layer to the lower layer, and each layer of screen 7 forms an inverted V-shaped structure. Specifically, the angle of the inverted V-shaped structure can be 90-120°, for example, 90°, 100°, 110° or 120°. The interval between adjacent two layers of screen 7 is fixed. Specifically, the adjacent two layers of screen 7 are fixed. A spacing of 10-20 cm needs to be left between the screens 7 to ensure effective separation of solids and liquids. At the same time, the liquid will pass through the next layer of screens more smoothly, and the filtration effect will not be greatly reduced due to the accumulation of solid pollutants; the solid waste is drawn out from the inverted V-shaped slope of each layer of screen 7, and the aquaculture wastewater with the solid waste filtered out enters the secondary solid-liquid separation component 5; the secondary solid-liquid separation component 5 is sequentially provided with a corundum layer 8, a quartz sand layer 9, a filter cloth layer 10 and an activated carbon layer 11 from top to bottom. During the specific operation process, the aquaculture wastewater passes through the screen 7 with gradually decreasing apertures in turn to complete the step-by-step solid-liquid separation of the aquaculture wastewater. At the same time, since each screen 7 forms an inverted V-shaped structure, the solid waste residue separated by the screen 7 will roll along the inclined surface of the screen 7 to the bottom of the solid-liquid separation device 1 (that is, it is led out from the inverted V-shaped slope of each layer of screen 7 to the solid waste residue outlet) and discharged from the solid waste residue outlet. The mixed liquid containing small particles separated by the screen 7 will directly enter the secondary solid-liquid separation component 5, and pass through the corundum layer 8, quartz sand layer 9, filter cloth layer 10 and activated carbon layer 11 in turn to complete filtration to obtain solid waste residue and waste liquid. The solid waste residue is discharged from the solid waste residue outlet at the bottom of the solid-liquid separation device 1, and the waste liquid enters the photoelectrocatalytic decomposition device 2 through the first connecting pipe 6. The first-stage solid-liquid separation component 4 provided in the present invention utilizes the friction angle principle, and combines the first-stage solid-liquid separation component 4 and the second-stage solid-liquid separation component 5 to adopt a multi-stage filtration principle. This not only reduces the pressure of the fine filtration device, but also improves the efficiency of the filtration process while preventing the accumulation of solid residues.

[0024] In the above technical solution, the corundum layer 8 is used to remove solid particles with a particle size of 0.1-0.2 mm, the quartz sand layer 9 is used to remove solid particles with a particle size of 0.05-0.1 mm, the filter cloth layer 10 is used to remove solid particles with a particle size of 0.02-0.05 mm, and the activated carbon layer 11 is used to further filter tiny particles, while using micropores to adsorb nano-sized particles, pigments, organic matter, heavy metals, etc.

[0025] In this article, the thickness of the corundum layer 8 is 180-300 mm, and the particle size is 0.1-0.2 mm; the thickness of the quartz sand layer 9 is 70-100 mm, and the particle size is 0.04-0.08 mm; the thickness of the filter cloth layer 10 is 10-30 mm, and the mesh size is 250-700 mesh; the thickness of the activated carbon layer 11 is 100-200 mm, and the particle size is 0.18-2.75 mm.

[0026] In the above technical solution, the photoelectrocatalytic decomposition device 2 includes a composite photocatalyst BC-TiO2 as the electrode material of the anode 12, modified activated biochar as the electrode material of the cathode 13, and also includes a DC power supply and an ultraviolet light source 14; specifically, the ultraviolet light source 14 specifically refers to a UV-B ultraviolet lamp with a wavelength range of 280-320nm. The UV-B ultraviolet lamp can generate a large number of short-wave ultraviolet photons. The photon energy will excite electrons to jump from the valence band to the conduction band, forming photogenerated electrons and holes. These electrons and holes will migrate to the catalyst surface to participate in chemical reactions, which can further excite the catalytic ability of the composite photocatalyst BC-TiO2 anode to achieve a higher level of purification effect.

[0027] In the above technical solution, the modified activated biochar is prepared from biological activated carbon by nitrogen-sulfur co-doping and oxygen introduction.

[0028] In a preferred embodiment, the modified activated biochar is prepared as follows: straw and bamboo cuttings biomass are carbonized at 400-500°C, and the carbonized product is pyrolyzed and activated at 600-700°C to obtain a first activated biochar having a porous structure; sodium bicarbonate and thiourea are fully mixed in a mass ratio of 1:0.5-2 to obtain a mixed activator, and the first activated biochar and the mixed activator are mixed and impregnated in a mass ratio of 1:0.5-2, and the impregnated product is activated at 575-675°C to obtain an activated product; the activated product is subjected to a low-temperature steam-air oxidation method, utilizing the residual heat of the medium-temperature pyrolysis activation in the previous step, i.e., cooling to 150-200°C during the cooling stage of the medium-temperature pyrolysis activation, and then a mixed gas containing 1-3% hydrogen peroxide vapor and air is introduced for low-temperature steam-air oxidation, wherein the mixing ratio of hydrogen peroxide vapor to air is 1:5-9, to obtain the modified activated biochar. The modified activated biochar is modified by nitrogen-sulfur co-doping and oxygen introduction to prepare modified activated biochar with good catalytic degradation performance as a cathode; after introducing more oxygen elements, the surface of the activated carbon will have more abundant oxygen-containing groups, which can enhance the hydrophilicity of the sample, expand the active surface area, and generate additional pseudocapacitance, which will be beneficial to the electrochemical performance in the aqueous electrolyte and have a higher capacitance. Nitrogen atoms can further change the physical or chemical properties of the carbon material, thereby improving the energy storage performance of the carbon material, and sulfur atoms can form highly oxidizing functional groups on the carbon surface, greatly improving the oxidation performance of the electrode. Heteroatom-doped porous activated biochar can greatly improve the oxygen reduction electrocatalytic activity because they have different electronegativity from carbon, polarizing adjacent carbon atoms and promoting the activation of adjacent carbon atoms during the electrocatalytic process.

[0029] In this article, modified activated biochar is composited with hot melt adhesive to prepare the cathode in the photoelectrocatalytic decomposition device 2 with good catalytic degradation performance, and the cathode mesh diameter is 20-30 mm.

[0030] Herein, the first activated biochar can be used in the activated carbon layer 11 as a carbon layer to adsorb pollutants.

[0031] In the above technical solution, the composite photocatalyst is BC-TiO2. In a preferred case, BC-TiO2 is processed by the sol-gel method, and its preparation method is: mixing butyl titanate, anhydrous ethanol, glacial acetic acid and biochar to prepare a sol, then aging it into a gel and drying and grinding it at about 105°C; keeping the dried product in a tubular furnace at 600-800°C for 2-3h to obtain BC-TiO2, wherein the amount of biochar added is 10-15% of the mass of TiO2 based on the mass of TiO2 in butyl titanate. The particle size of the composite photocatalyst BC-TiO2 is 2-5nm, and the specific surface area is 200-300m2 / g. Specifically, the biochar preparation method comprises: crushing straw or bamboo cuttings into a particle size of 0.2-0.5 mm, calcining the biomass in a tube furnace under an inert atmosphere (nitrogen condition) at 400-500°C, then acid-washing the calcined product with 1 mol / L hydrochloric acid, and finally soaking and filtering the acid-washed product with deionized water, rinsing it with suction filtration through a Buchner funnel, and drying it in an oven at 60-105°C to obtain the biochar.

[0032] The composite photocatalyst BC-TiO2 is a key active catalyst for generating strong oxidizing free radicals and activating medium-strength oxidants such as hydrogen peroxide, and can achieve deep treatment of difficult-to-degrade organic pollutants. The composite photocatalytic material BC-TiO2 anode prepared by the sol-gel method of the present invention can effectively inhibit the recombination of photogenerated electron-hole pairs under the load of biochar with a good pore structure, while expanding the light absorption range, increasing the light absorption intensity, and greatly improving the photocatalytic performance.

[0033] In this article, the composite photocatalyst BC-TiO2 is used as the electrode material of the anode in the photoelectrocatalytic decomposition device 2, and the anode mesh diameter is 10-20 mm.

[0034] In a preferred case, a first diverter valve 19 is provided on the first connecting pipe 6, the first interface of the first diverter valve 19 is connected to the output end of the secondary solid-liquid separation component 5, the second interface of the first diverter valve 19 is connected to the input end of the photoelectrocatalytic decomposition device 2, the pump 20 is used to draw the liquid from the second interface of the first diverter valve 19 into the photoelectrocatalytic decomposition device 2, the third interface of the first diverter valve 19 is connected to the first interface of the second diverter valve 22, the second interface of the second diverter valve 22 is connected to the output end of the photoelectrocatalytic decomposition device 2, and the third interface of the second diverter valve 22 is connected to the input end of the capacitive deionization device 3.

[0035] When the chemical oxygen demand content in the waste liquid for removing organic matter output from the output end of the photoelectrocatalytic decomposition device 2 is greater than 800 mg / L, the waste liquid for removing organic matter passes through the second diverter valve 22 and the first diverter valve 19 in sequence, and is pumped into the photoelectrocatalytic decomposition device 2 through the pump 20 for cyclic photoelectrocatalytic degradation.

[0036] When the content of chemical oxygen demand in the waste liquid for removing organic matter outputted from the output end of the photoelectrocatalytic decomposition device 2 is ≤800mg / L, the waste liquid for removing organic matter passes through the second diverter valve 22 and enters the capacitive deionization device 3 for removal of charged particles. In a more preferred case, when the content of chemical oxygen demand in the waste liquid for removing organic matter outputted from the output end of the photoelectrocatalytic decomposition device 2 is 500-800mg / L, the waste liquid for removing organic matter passes through the second diverter valve 22 and enters the capacitive deionization device 3 for removal of charged particles, and the treated wastewater can meet higher discharge standards. After photoelectric treatment, the sewage discharge standard is generally not met, so it is necessary to further remove the charged ions in the sewage through capacitive deionization equipment to reduce the content of pollutants such as COD (chemical oxygen demand), SS (suspended solids), and ammonia nitrogen. At the same time, water with lower chemical oxygen demand enters the capacitive deionization equipment, which can reduce the pressure of the capacitive deionization device and prevent excessive ions from reducing the degradation efficiency.

[0037] Since the sewage after photoelectrocatalytic degradation enters between electrodes with larger cross-sectional areas at the same flow rate, the sewage flow rate is reduced, and the cations in the sewage are adsorbed to the Faraday electrode cathode 15, while the anions are adsorbed to the Faraday electrode anode 16, further removing the charged particles in the sewage that have not been completely electrolytically treated. The sewage treated by the capacitive deionization device 3 becomes clean water and is discharged through the valve 23.

[0038] In the above technical solution, the capacitive deionization device 3 includes a power supply, a Faraday electrode cathode 15, a Faraday electrode anode 16, a cation exchange membrane 17 and an anion exchange membrane 18, and the side walls at both ends of the capacitive deionization device 3 are respectively provided with a photoelectric degradation wastewater inlet and a clean water outlet; wherein, the materials of the Faraday electrode cathode 15 and the Faraday electrode anode 16 are both zinc-loaded and nitrogen-boron co-doped activated biochar; the negative pole of the power supply is connected to the Faraday electrode cathode 15, and the positive pole of the power supply is connected to the Faraday electrode anode 16, the cation exchange membrane 17 is laid on the Faraday electrode cathode 15, and the anion exchange membrane 18 is laid on the Faraday electrode anode 16, and the cation exchange membrane 17 and the anion exchange membrane 18 are arranged opposite to each other. The Faraday electrode cathode 15 and the Faraday electrode anode 16 can effectively adsorb anions and cations after photoelectric treatment to further purify the water quality; the cation exchange membrane 17 is used to prevent anions in the waste liquid from directly attaching to the Faraday electrode anode 16; the anion exchange membrane 18 is used to prevent cations in the waste liquid from directly attaching to the Faraday electrode cathode 15, avoiding competitive capacitive adsorption between coexisting ions with the same electrical properties as the electrode and the target ions, occupying the capacitive adsorption active sites, resulting in problems such as the common ion effect and capacitive cycle stability of the electrode, thereby improving the removal rate of charged particles by capacitive deionization.

[0039] In a preferred embodiment, the preparation method of the zinc-loaded, nitrogen-boron co-doped activated biochar is as follows:

[0040] The first activated biochar described above is mixed with ethanol at a ratio of 1 g: 40-60 mL and stirred for 30-40 minutes, and then a KOH solution with a mass fraction of 10-12% is added to the mixed product and stirred for 50-70 minutes to obtain a first mixed solution. The first mixed solution is dried and ground at 70-90° C., and then the ground product is calcined at 750-850° C., and then the calcined product is acid-washed with 1 mol / L hydrochloric acid. Finally, the acid-washed product is soaked and filtered with deionized water, and then filtered and rinsed through a Buchner funnel, and dried in an oven at 60-105° C. to obtain a second activated biochar;

[0041] The second activated biochar, ammonium borate and water are mixed, and the second activated biochar and ammonium borate are mixed in a mass ratio of 1:1.2 to obtain a second mixed solution, and then the second mixed solution is dried at 60-105° C., ground, and finally the ground product is calcined at 750-850° C., and the calcined product is washed with water and dried at 60-105° C. to obtain nitrogen-boron co-doped activated biochar, wherein the nitrogen-boron co-doped activated biochar has a porous structure and is recorded as BC-B / N;

[0042] The nitrogen-boron co-doped activated biochar (BC-B / N) is mixed with a zinc acetate solution with a concentration of 0.2-0.5 mol / L, and the mixed product is kept at 550-650°C for 1.5-2.5 hours, then pickled with 1 mol / L hydrochloric acid. Finally, the pickled product is soaked and filtered with deionized water, and rinsed with suction filtration through a Buchner funnel, and dried in an oven at 60-105°C to obtain zinc-loaded, nitrogen-boron co-doped activated biochar, which is recorded as BC-B / N-Zn.

[0043] In this paper, the capacitive deionization performance of biochar was significantly improved by introducing elements such as N and B and loading them with Zn. The numerous micropores and mesopores obtained through modification effectively increase active sites and shorten ion transport pathways, while Zn effectively expands the pores, further improving ion transport efficiency. The composite ZnO and biochar on the activated carbon surface enhances electrochemical performance while increasing stability, resulting in higher specific capacitance and superior rate capability.

[0044] The second aspect of the present invention proposes a wastewater cascade treatment method based on photoelectrocatalytic degradation, which includes: performing solid-liquid separation on aquaculture wastewater in the solid-liquid separation device 1 to obtain solid waste residue and waste liquid; transporting the waste liquid to the photoelectrocatalytic decomposition device 2, applying a light source to the photoelectrocatalytic decomposition device 2, the anode 12 material in the photoelectrocatalytic decomposition device 2 is a composite photocatalyst, and the cathode 13 material is modified activated biochar, the anode 12 is used to catalytically degrade organic matter in the waste liquid in the photoelectrocatalytic degradation, and the cathode 13 is used to provide more active sites in the photoelectrocatalytic degradation, and utilize catalytic performance to improve degradation efficiency; the waste liquid discharged from the photoelectrocatalytic decomposition device 2 to remove organic matter is input into the capacitive deionization device 3 for removal of charged particles to obtain treated wastewater.

[0045] In this article, the aquaculture wastewater includes pig farm wastewater and chicken farm wastewater. Specifically, the water quality of the pig farm wastewater is: COD (chemical oxygen demand) content is 9000-25000 mg / L, NH3-N (ammonia nitrogen) content is 800-1200 mg / L, SS (suspended solids) content is 7000-12000 mg / L, and BOD (biochemical oxygen demand) content is 7000-18000 mg / L; the water quality of the chicken farm wastewater is: COD content is 43000-77000 mg / L, NH3-N content is 25000-40000 mg / L, SS content is 1400-4000 mg / L, and BOD content is 10000-12000 mg / L.

[0046] Example 1

[0047] A wastewater cascade treatment system based on photoelectrocatalytic degradation, such as Figure 1As shown, the system includes: a solid-liquid separation device 1, a photoelectrocatalytic decomposition device 2 and a capacitive deionization device 3; the top of the solid-liquid separation device 1 has an aquaculture wastewater inlet and the bottom has a solid waste residue outlet, the interior of the solid-liquid separation device 1 is provided with a primary solid-liquid separation component 4 and a secondary solid-liquid separation component 5 located below the primary solid-liquid separation component, the aquaculture wastewater inlet is located directly above the primary solid-liquid separation component 4; the primary solid-liquid separation component 4 is a 30-mesh wire mesh, 5 arranged in sequence from top to bottom. 0 mesh wire mesh and 70 mesh wire mesh, and the wire meshes of different mesh numbers all form an inverted V-shaped structure with an angle of 120°. The adjacent two layers of screen are fixed with a spacing of 15 cm. The solid waste is drawn out from the inverted V-shaped slope of each layer of screen 7, and the aquaculture wastewater with the solid waste removed enters the secondary solid-liquid separation component 5. The secondary solid-liquid separation component 5 is sequentially provided with a corundum layer 8 (thickness of 200 mm, particle size of 0.1-0.2 mm), a quartz sand layer 9 (thickness of 85 mm, particle size of 0 .04-0.08mm), a filter cloth layer 10 (with a thickness of 20mm and a mesh size of 250-700 mesh) and an activated carbon layer 11 (the activated carbon layer uses the first activated biochar prepared in Example 1, with a thickness of 150mm and a particle size of 0.18-2.75mm); the bottom of the secondary solid-liquid separation component 5 is communicated with the photoelectrocatalytic decomposition device 2 through a first communicating pipe 6; a first diverter valve 19 and a pump 20 are provided on the first communicating pipe 6, a first interface of the first diverter valve 19 is communicated with the output end of the secondary solid-liquid separation component 5, a second interface of the first diverter valve 19 is communicated with the input end of the photoelectrocatalytic decomposition device 2, the pump 20 is used to draw the liquid from the second interface of the first diverter valve 19 into the photoelectrocatalytic decomposition device 2, the third interface of the first diverter valve 19 is communicated with the first interface of the second diverter valve 22, the second interface of the second diverter valve 22 is communicated with the output end of the photoelectrocatalytic decomposition device 2, and the third interface of the second diverter valve 22 is communicated with the input end of the capacitive deionization device 3;

[0048] The photoelectrocatalytic decomposition device 2 includes a composite photocatalyst BC-TiO2 as an anode 12, a modified activated biochar as a cathode 13, a DC power supply and an ultraviolet light source 14, wherein the ultraviolet light source 14 is a UV-B ultraviolet lamp with a wavelength between 280-320nm. The bottom of the photoelectrocatalytic decomposition device 2 has a photoelectrolytic degradation wastewater outlet;

[0049] Among them, the preparation process of the composite photocatalyst BC-TiO2 is as follows: first, the straw and bamboo cuttings biomass with a particle size of 0.2-0.5 mm are crushed and calcined in a tubular furnace in an N2 environment at 450°C, and then the calcined product is pickled with 1 mol / L hydrochloric acid, and finally the pickled product is soaked and filtered with deionized water, and rinsed with a Buchner funnel, and dried in an oven at 85°C to obtain biochar; then, butyl titanate, anhydrous ethanol, glacial acetic acid and biochar are mixed to prepare a sol, which is then aged into a gel and dried and ground at 105°C, wherein the mass of TiO2 in butyl titanate is 100% by mass and the amount of biochar added is 12% by mass; finally, the dried product is kept at 700°C in a tubular furnace for 2h to obtain a composite photocatalyst BC-TiO2, the particle size of the composite photocatalyst BC-TiO2 is 2-5nm, and the specific surface area is 200-300m 2 The composite photocatalyst BC-TiO2 is used as the anode in the photoelectrocatalytic decomposition device 2, and the anode mesh has a pore size of 10-20 mm.

[0050] The modified activated biochar preparation process comprises: carbonizing biomass at 450°C, pyrolyzing and activating the carbonized product at 600°C to obtain a first activated biochar; thoroughly mixing sodium bicarbonate and thiourea in a mass ratio of 1:1.5 to obtain a mixed activator; then impregnating the first activated biochar with the mixed activator in a mass ratio of 1:1; and activating the impregnated product at 650°C to obtain an activated product; subjecting the activated product to low-temperature steam-air oxidation, utilizing the residual heat from the previous medium-temperature pyrolysis activation step, cooling it to 200°C during the cooling phase of the medium-temperature pyrolysis activation; and then introducing a mixture of 2% hydrogen peroxide vapor and air for low-temperature steam-air oxidation, with the hydrogen peroxide vapor to air ratio being 1:6, to obtain the modified activated biochar. The modified activated biochar is then composited with hot-melt adhesive to form a cathode in a photoelectrocatalytic decomposition device 2 with excellent catalytic degradation performance, the cathode mesh having a pore size of 20-30 mm.

[0051] The capacitive deionization device 3 includes a power supply, a Faraday electrode cathode 15, a Faraday electrode anode 16, a cation exchange membrane 17 and an anion exchange membrane 18. The side walls at both ends of the capacitive deionization device 3 are respectively provided with a photoelectric degradation wastewater inlet and a clean water outlet; wherein the materials of the Faraday electrode cathode 15 and the Faraday electrode anode 16 are both zinc-loaded, nitrogen-boron co-doped activated biochar, the negative pole of the power supply is connected to the Faraday electrode cathode 15, the positive pole of the power supply is connected to the Faraday electrode anode 16, the cation exchange membrane 17 is laid on the Faraday electrode cathode 15, the anion exchange membrane 18 is laid on the Faraday electrode anode 16, and the cation exchange membrane 17 and the anion exchange membrane 18 are arranged opposite to each other;

[0052] The preparation method of the zinc-loaded, nitrogen-boron co-doped activated biochar is as follows:

[0053] The first activated biochar and ethanol were mixed and stirred at a ratio of 1 g:50 mL for 40 minutes, and then a 12% by mass KOH solution was added to the mixed product and stirred for 60 minutes to obtain a first mixed solution. The first mixed solution was dried and ground at 80° C., and then the ground product was calcined at 800° C., and then the calcined product was acid-washed with 1 mol / L hydrochloric acid. Finally, the acid-washed product was soaked and filtered with deionized water, and then filtered and rinsed through a Buchner funnel, and dried in an oven at 90° C. to obtain a second activated biochar.

[0054] The second activated biochar, ammonium borate and water are mixed, and the second activated biochar and ammonium borate are mixed in a mass ratio of 1:1.2 to obtain a second mixed solution, and then the second mixed solution is dried at 75° C. and ground, and finally the ground product is calcined at 800° C., and the calcined product is washed with water and dried at 105° C. to obtain nitrogen-boron co-doped activated biochar, which has a porous structure and is recorded as BC-B / N;

[0055] The nitrogen-boron co-doped activated biochar (BC-B / N) was mixed with a 0.4 mol / L zinc acetate solution, and the mixed product was treated at 600°C for 2 hours, then pickled with 1 mol / L hydrochloric acid. Finally, the pickled product was soaked and filtered with deionized water, and rinsed with a Buchner funnel, and dried in an oven at 85°C to obtain zinc-loaded, nitrogen-boron co-doped activated biochar, which was recorded as BC-B / N-Zn.

[0056] A wastewater cascade treatment method based on photoelectrocatalytic degradation is implemented in the system described in Example 1. The aquaculture wastewater in this embodiment is a pig farm wastewater. The water quality of the pig farm wastewater is shown in Table 1. The pig farm wastewater enters from the aquaculture wastewater inlet at the top of the solid-liquid separation device 1, and then passes through a 30-mesh wire mesh, a 50-mesh wire mesh, and a 70-mesh wire mesh in sequence to complete the step-by-step solid-liquid separation of the pig farm wastewater. At the same time, since each wire mesh forms an inverted V-shaped structure with a certain angle, the solid waste residue separated by the wire meshes of different mesh sizes will roll along the inclined surface of the wire mesh to the bottom of the solid-liquid separation device 1 and be discharged from the solid waste residue outlet, and the waste liquid containing small particles separated by the wire mesh will directly enter the secondary solid-liquid separation component 5, and pass through the corundum layer 8, the quartz sand layer 9, the filter cloth layer 10, and the activated carbon layer 11 in sequence to complete the filtration to obtain solid waste residue and waste liquid, and the solid waste residue is discharged from the solid waste residue outlet at the bottom of the solid-liquid separation device 1;

[0057] Open the first interface and the second interface of the first diverter valve 19, and open the pump 20. The waste liquid is transported to the photoelectrocatalytic decomposition device 2 through the first connecting pipe 6. Ultraviolet light with a wavelength of 280-320nm is applied. The waste liquid undergoes photoelectrocatalytic degradation in the photoelectrocatalytic decomposition device 2. The COD (chemical oxygen demand) content in the degraded waste liquid is 960mg / L. Continue to open the first interface and the second interface of the second diverter valve 22, and open the third interface of the first diverter valve 19. The waste water that has undergone photoelectrocatalytic degradation circulates into the photoelectrocatalytic decomposition device 2 and continues to degrade until the COD content in the degraded waste water is 650mg / L. Close all interfaces and the pump 20 of the first diverter valve 19, and close the first interface and the second interface of the second diverter valve 22. Open the third interface of the second diverter valve 22. The waste liquid with organic matter removed is transported to the capacitive deionization device 3 for removal of charged particles to obtain clean water, which is discharged from the valve 23. The water quality of the treated clean water is shown in Table 1.

[0058] Example 2

[0059] The system of Example 1 was implemented, except that the wastewater from a pig farm was replaced by wastewater from a chicken farm. The water quality of the wastewater from the chicken farm is shown in Table 2. The water quality of the clean water after being treated by the system of the present invention is also shown in Table 2.

[0060] Table 1 Water quality indicators of pig farm wastewater before and after treatment

[0061]

[0062]

[0063] Table 2 Water quality indicators of chicken farm wastewater before and after treatment

[0064]

[0065] It can be seen from the results in Table 1 and Table 2 that the system of the present invention can separate aquaculture wastewater with high COD and high turbidity step by step, while improving the ability to oxidize and degrade organic matter in aquaculture wastewater, thereby achieving more efficient and energy-saving wastewater degradation.

[0066] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A cascade treatment system for aquaculture wastewater based on photoelectrocatalytic degradation, characterized in that: The system comprises: a solid-liquid separation device (1), a photoelectrocatalytic decomposition device (2) and a capacitive deionization device (3); The solid-liquid separation device (1) is used to separate the aquaculture wastewater into solid and liquid to obtain solid waste residue and waste liquid; The photoelectrocatalytic decomposition device (2) is used to perform photoelectrocatalytic degradation on the waste liquid obtained from the solid-liquid separation device (1) to remove organic matter in the waste liquid. The anode (12) material in the photoelectrocatalytic decomposition device (2) is a composite photocatalyst, and the cathode (13) material is modified activated biochar. The anode (12) is used to catalytically degrade the organic matter in the waste liquid during the photoelectrocatalytic degradation, and the cathode (13) is used to provide active sites during the photoelectrocatalytic degradation. The capacitive deionization device (3) is used to remove charged particles from the waste liquid for removing organic matter discharged from the photoelectrocatalytic decomposition device (2); The modified activated biochar is prepared by nitrogen-sulfur co-doping and oxygen introduction into biological activated carbon; The modified activated biochar is prepared as follows: Carbonizing the biomass at 400-500° C., and pyrolyzing and activating the carbonized product at 600-700° C. to obtain first activated biochar; Thoroughly mixing sodium bicarbonate and thiourea at a mass ratio of 1:0.5-2 to obtain a mixed activator, impregnating the first activated biochar with the mixed activator at a mass ratio of 1:0.5-2, and activating the impregnated product at 575-675° C. to obtain an activated product; The activated product is introduced into a mixed gas of hydrogen peroxide vapor and air at 150-200° C. for oxidation reaction to obtain modified activated biochar, wherein the concentration of hydrogen peroxide vapor is 1-3%, and the mixing ratio of hydrogen peroxide vapor to air is 1:5-9.

2. The wastewater cascade treatment system according to claim 1, characterized in that: The composite photocatalyst is BC-TiO2, and the preparation method of BC-TiO2 is: Butyl titanate, anhydrous ethanol, glacial acetic acid and biochar are mixed to prepare a sol, which is then aged and dried; The dried product was calcined at 600-800°C for 2-3h to obtain BC-TiO2; Among them, based on the mass of TiO2 in butyl titanate, the amount of biochar added is 10-15% of the mass of TiO2; The biochar preparation method comprises the following steps: crushing biomass with a particle size of 0.2-0.5 mm, calcining the biomass under an inert atmosphere at 400-500° C., and then sequentially acid-washing, water-washing, and drying the calcined product to obtain the biochar.

3. The wastewater cascade treatment system according to claim 1, characterized in that: The top of the solid-liquid separation device (1) is provided with an aquaculture wastewater inlet. The interior of the solid-liquid separation device (1) is provided with a primary solid-liquid separation component (4) and a secondary solid-liquid separation component (5) located below the primary solid-liquid separation component (4). The aquaculture wastewater inlet is located directly above the primary solid-liquid separation component (4). The particle size of the solid waste residue filtered out of the primary solid-liquid separation component (4) is larger than the particle size of the solid waste residue filtered out of the secondary solid-liquid separation component (5). The output end of the secondary solid-liquid separation component (5) is connected to the photoelectrocatalytic decomposition device (2) via a first connecting pipe (6).

4. The wastewater cascade treatment system according to claim 3, characterized in that: The first-level solid-liquid separation component (4) includes multiple layers of screens (7) arranged sequentially from top to bottom, and the aperture of each layer of screens (7) gradually decreases from the upper layer to the lower layer, and each layer of screens (7) forms an inverted V-shaped structure, and the interval between two adjacent layers of screens (7) is fixed; solid waste is drawn out from the inverted V-shaped slope of each layer of screens (7), and the aquaculture wastewater with the solid waste filtered out enters the second-level solid-liquid separation component (5); The secondary solid-liquid separation component (5) is provided with a corundum layer (8), a quartz sand layer (9), a filter cloth layer (10) and an activated carbon layer (11) in order from top to bottom.

5. The wastewater cascade treatment system according to claim 1, characterized in that: The capacitive deionization device (3) includes a power supply, a Faraday electrode cathode (15), a Faraday electrode anode (16), a cation exchange membrane (17), and an anion exchange membrane (18); Wherein, the materials of the Faraday electrode cathode (15) and the Faraday electrode anode (16) are both zinc-loaded, nitrogen-boron co-doped activated biochar; The negative electrode of the power supply is connected to the Faraday electrode cathode (15), the positive electrode of the power supply is connected to the Faraday electrode anode (16), the cation exchange membrane (17) is laid on the Faraday electrode cathode (15), the anion exchange membrane (18) is laid on the Faraday electrode anode (16), and the cation exchange membrane (17) and the anion exchange membrane (18) are arranged opposite to each other; The Faraday electrode cathode (15) is used to adsorb cations in the wastewater to remove organic matter; The Faraday electrode anode (16) is used to adsorb anions in the wastewater to remove organic matter; The cation exchange membrane (17) is used to prevent anions in the wastewater from directly adhering to the Faraday electrode anode (16); The anion exchange membrane (18) is used to prevent cations in the wastewater from directly adhering to the Faraday electrode cathode (15).

6. The wastewater cascade treatment system according to claim 5, characterized in that: The preparation method of the zinc-loaded, nitrogen-boron co-doped activated biochar is as follows: The first activated biochar and ethanol are mixed and stirred for 30-40 minutes, a 10-12% by mass KOH solution is added to the mixed product and the mixture is stirred for 50-70 minutes to obtain a first mixed solution, the first mixed solution is dried and ground at 70-90°C, and the ground product is calcined at 750-850°C, and the calcined product is then acid-washed, water-washed, and dried to obtain a second activated biochar; mixing ammonium borate and water with the second activated biochar to obtain a second mixed solution, drying and grinding the second mixed solution, calcining the ground product at 750-850° C., washing the calcined product with water, and drying it to obtain nitrogen-boron co-doped activated biochar; The nitrogen-boron co-doped activated biochar is mixed with a zinc acetate solution having a concentration of 0.2-0.5 mol / L, the mixed product is kept at 550-650° C., and then sequentially acid-washed, water-washed, and dried to obtain zinc-loaded, nitrogen-boron co-doped activated biochar.

7. The wastewater cascade treatment system according to claim 3, characterized in that: A first diverter valve (19) is provided on the first connecting pipe (6), a first interface of the first diverter valve (19) is connected to the output end of the secondary solid-liquid separation component (5), a second interface of the first diverter valve (19) is connected to the input end of the photoelectrocatalytic decomposition device (2), a pump (20) is used to pump liquid from the second interface of the first diverter valve (19) into the photoelectrocatalytic decomposition device (2), a third interface of the first diverter valve (19) is connected to the first interface of the second diverter valve (22), a second interface of the second diverter valve (22) is connected to the output end of the photoelectrocatalytic decomposition device (2), and a third interface of the second diverter valve (22) is connected to the input end of the capacitive deionization device (3); When the chemical oxygen demand content of the waste liquid for removing organic matter output from the output end of the photoelectrocatalytic decomposition device (2) is greater than 800 mg / L, the waste liquid for removing organic matter passes through the second diverter valve (22) and the first diverter valve (19) in sequence, and is pumped into the photoelectrocatalytic decomposition device (2) by the pump (20) for cyclic photoelectrocatalytic degradation; When the chemical oxygen demand content in the waste liquid for removing organic matter output from the output end of the photoelectrocatalytic decomposition device (2) is ≤800 mg / L, the waste liquid for removing organic matter passes through the second diverter valve (22) and enters the capacitive deionization device (3) for charged particle removal treatment.

8. A wastewater cascade treatment method based on photoelectrocatalytic degradation, characterized in that: The method includes: The aquaculture wastewater is subjected to solid-liquid separation in a solid-liquid separation device (1) to obtain solid waste residue and waste liquid; The waste liquid is transported to a photoelectrocatalytic decomposition device (2), and a light source is applied to the photoelectrocatalytic decomposition device (2). The anode (12) material in the photoelectrocatalytic decomposition device (2) is a composite photocatalyst, and the cathode (13) material is modified activated biochar. The anode (12) is used to catalytically degrade organic matter in the waste liquid during photoelectrocatalytic degradation, and the cathode (13) is used to provide active sites during photoelectrocatalytic degradation. The waste liquid discharged from the photoelectrocatalytic decomposition device (2) after removal of organic matter is input into the capacitive deionization device (3) for removal of charged particles to obtain treated wastewater; The modified activated biochar is prepared by nitrogen-sulfur co-doping and oxygen introduction into biological activated carbon; The modified activated biochar is prepared as follows: Carbonizing the biomass at 400-500° C., and pyrolyzing and activating the carbonized product at 600-700° C. to obtain first activated biochar; Thoroughly mixing sodium bicarbonate and thiourea at a mass ratio of 1:0.5-2 to obtain a mixed activator, impregnating the first activated biochar with the mixed activator at a mass ratio of 1:0.5-2, and activating the impregnated product at 575-675° C. to obtain an activated product; The activated product is introduced into a mixed gas of hydrogen peroxide vapor and air at 150-200° C. for oxidation reaction to obtain modified activated biochar, wherein the concentration of hydrogen peroxide vapor is 1-3%, and the mixing ratio of hydrogen peroxide vapor to air is 1:5-9.

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