Organic contaminated soil bioremediation device

Abstract

The embodiment of the invention discloses a bioremediation device for organic contaminated soil. The bioremediation device comprises a photovoltaic electrolysis assembly, a mass transfer transition assembly and a soil remediation assembly. The photovoltaic electrolysis assembly generates oxygen and hydrogen through solar electrolysis of water; the mass transfer transition component is used for conveying gas to a bionic root system main body of the soil remediation component in a partitioned manner, a hydrogen injection hole is formed in the tail end of a first-stage branch to form an anaerobic micro-region, and an oxygen injection hole with a hydrophobic membrane is formed in the tail end of a second-stage branch to maintain an aerobic environment; the surface of the bionic root system is coated with a composite layer, titanium dioxide nanofibers are excited through an ultraviolet LED to generate holes to oxidize organic matter, and electrons are subjected to heavy metal reduction strengthening through a graphene grid. According to the method, the traditional microbial remediation period is shortened and the organic matters and the heavy metals are synchronously removed through triple mechanisms of gas partitioned and graded controlled release, photocatalysis-electrochemistry cooperation and in-situ electron targeted delivery, the whole process is completed in situ, earthwork excavation and outward transportation risks are avoided, and the method has the advantages of high efficiency, stability and environmental protection.

Description

Technical Field

[0001] The present application relates to the technical field of organic contaminated soil remediation, and in particular to an organic contaminated soil bioremediation device. Background Art

[0002] As a byproduct of the development of the chemical industry, organic contaminated soil has attracted more and more attention. The existence of organic contaminated soil has limited the land use of the original site of the enterprise to a certain extent. Especially in the current situation of gradual urbanization, chemical enterprises in the urban area have been relocated one after another, and the remaining sites are in urgent need of development and reuse. However, the location of the site and the living environment of the surrounding residents determine that it is not easy to transport and dispose of contaminated soil on a large scale, which has a great risk of secondary pollution. In this regard, the use of skid-mounted mobile disposal equipment for on-site ex-situ disposal of contaminated sites is a feasible and convenient disposal method.

[0003] Existing soil remediation equipment is mainly based on soil cleaning process, chemical oxidation process and thermal desorption treatment process, and contaminated soil is repaired through physical or chemical treatment technology. However, the disposal of cleaning liquid in soil cleaning process is a more troublesome subsequent disposal work, especially in the remediation project of organic pollution sites in urban areas. The disposal of cleaning liquid has become a burden to increase the cost of contaminated soil disposal; and the greenhouse gases continuously emitted during the thermal desorption treatment process will limit the wider application of this technology in the future. At the same time, its high energy consumption load and disposal cost are also one of the unfavorable factors limiting its further large-scale application. In this regard, bioremediation has regained the attention of environmental workers due to its economic and friendly process characteristics. However, the defects of long cycle and unstable effect of microbial remediation are still negative factors in its engineering application. Summary of the invention

[0004] The embodiment of the present application provides a device for bioremediation of organic contaminated soil, which is used to improve the problem of long microbial remediation cycle.

[0005] In a first aspect, an embodiment of the present application provides an organic contaminated soil bioremediation device, comprising a photovoltaic electrolysis component, a mass transfer transition component, and a soil remediation component connected in sequence from top to bottom;

[0006] The photovoltaic electrolysis assembly comprises an electrolytic cell, a photovoltaic panel obliquely arranged above the electrolytic cell, and a positive electrode rod and a negative electrode rod inserted into an electrolyte, wherein the positive electrode rod and the negative electrode rod are electrically connected to the photovoltaic panel respectively;

[0007] The mass transfer transition component includes an oxygen tank, a hydrogen tank and a nutrient solution tank, wherein the oxygen tank and the hydrogen tank are respectively connected to an oxygen delivery pipe and a hydrogen delivery pipe with an air pump, and the oxygen delivery pipe and the hydrogen delivery pipe both extend above the liquid surface of the electrolyzer;

[0008] The soil remediation component comprises a bionic root system body and a composite layer, wherein the bionic root system body comprises a support column, a primary branch and a secondary branch; an oxygen pipe, a hydrogen pipe and a cable pipe are coaxially sleeved in the support column to form a nutrient solution channel, an oxygen channel and a hydrogen channel that are not connected to each other;

[0009] The primary branch is provided with a hydrogen flow channel, a first oxygen flow channel and a first nutrient solution flow channel which are not connected to each other, and are connected to the hydrogen channel, the oxygen channel and the nutrient solution channel respectively; the secondary branch is provided with a second oxygen flow channel and a second nutrient solution flow channel which are not connected to each other, the second oxygen flow channel is connected to the first oxygen flow channel, the second nutrient solution flow channel is connected to the first nutrient solution flow channel, and the nutrient solution in the first nutrient solution flow channel, the second nutrient solution flow channel and the nutrient solution channel can all flow into the composite layer;

[0010] The composite layer covers the surface of the bionic root system body and includes a biochar coating, a graphene conductive grid layer and a titanium dioxide nanofiber layer stacked from the inside to the outside;

[0011] The cable tube has an optical fiber with an ultraviolet LED chip and a wire connected to the negative electrode of the photovoltaic panel. The wire is used to extend to the soil and has a corrosion-resistant conductive contact at the end. The optical fiber extends to the titanium dioxide nanofiber layer.

[0012] A pulsed high-pressure hydrogen injection hole is arranged at the end of the primary branch, and an oxygen injection hole with a hydrophobic membrane is arranged at the end of the secondary branch.

[0013] In some embodiments of the present application, the aperture of the pulsed high-pressure hydrogen injection hole is 20-50 μm, the pulse frequency is 1-5 Hz, and the contact angle of the hydrophobic membrane is greater than 150°.

[0014] In some embodiments of the present application, the titanium dioxide nanofiber layer is doped with trivalent iron ions or nitrogen elements, so that the titanium dioxide nanofiber layer has visible light response characteristics, and the response wavelength range is 400-550nm.

[0015] In some embodiments of the present application, a spiral guide groove is provided on the surface of the support column, and the pitch of the spiral guide groove is 5-10 mm and the depth is 2-5 mm, which is used to enrich pollutants and guide them to migrate to the composite layer.

[0016] In some embodiments of the present application, the bifurcation angle between the primary branch and the secondary branch ranges from 60° to 80°, and the diameter of the secondary branch is 1 / 3 to 1 / 2 of the diameter of the primary branch.

[0017] In some embodiments of the present application, the device further includes an intelligent control unit, and the intelligent control unit includes:

[0018] Potential monitoring module, used to monitor soil redox potential in real time and adjust hydrogen injection pressure;

[0019] A spectrum analysis module, which feeds back the intensity of ultraviolet light through an optical fiber to control the power of the ultraviolet LED chip;

[0020] Dynamic liquid distribution module adjusts the nutrient solution release rate according to the soil pH value.

[0021] In some embodiments of the present application, the corrosion-resistant conductive contact is a platinum-plated ceramic sheet or a graphene-coated electrode, and the surface roughness of the corrosion-resistant conductive contact is in the range of Ra 0.8-1.6 μm.

[0022] In some embodiments of the present application, the organic contaminated soil bioremediation device also includes a microalgae reactor, which is connected to the electrolytic cell and is used to convert the carbon dioxide generated by electrolysis into biomass and regenerate the biochar coating after pyrolysis.

[0023] In some embodiments of the present application, a pulse backwash valve is provided at the end of the hydrogen pipe, the backwash pressure range of the backwash valve is 0.5-0.8 MPa, the flushing frequency is once every 24 hours, and each time lasts 10-30 seconds.

[0024] In some embodiments of the present application, the emission wavelength range of the ultraviolet LED chip is 360nm-370nm, and the power density range is 10-50mW / cm 2 , and a focusing lens is provided at the end of the optical fiber to focus the ultraviolet light onto the titanium dioxide nanofiber layer.

[0025] It can be seen that the embodiment of the present application converts solar energy into electrical energy to drive water electrolysis through a photovoltaic electrolysis component, and simultaneously generates high-purity oxygen and hydrogen in the electrolytic cell. The oxygen is transported to the hydrophobic membrane oxygen injection hole at the end of the secondary branch through the oxygen tank of the mass transfer transition component, and the dissolved oxygen concentration (2-4 mg / L) in the aerobic zone of the soil is accurately maintained through the micropore slow release mechanism, activating aerobic bacteria to rapidly mineralize organic pollutants such as benzene series and petroleum hydrocarbons; hydrogen is transported to the pulsed high-pressure injection hole of the primary branch through the hydrogen tank, and hydrogen is injected into the deep soil layer in the form of micron-sized bubbles through intermittent high-pressure pulses (1-5 Hz), and in the low permeability area The formation of stable anaerobic micro-areas (ORP<-200mV) provides continuous electron donors for dehalogenating bacteria, increasing the reduction and dechlorination rate of chlorinated hydrocarbons by 3-5 times; in the biochar-photocatalytic composite layer on the surface of the bionic root system, ultraviolet LEDs excite titanium dioxide nanofibers to produce highly active holes and free electrons. Holes directly oxidize the chain-breaking and difficult-to-degrade organic matter (such as polycyclic aromatic hydrocarbons) to generate easily degradable small molecule products, while electrons are transmitted to the pollution interface through the graphene conductive grid, and cooperate with the electrons released by hydrogen to enhance the reduction and precipitation of heavy metals; the nutrient solution channel continuously transports nitrates and phosphates to the microbial enrichment area to maintain the metabolic activity of the bacterial community. In general, through the triple mechanism of gas zoning and graded controlled release to accelerate microbial metabolism, photocatalytic-electrochemical synergistic pretreatment of pollutants, and in-situ electron targeted delivery, the traditional microbial remediation cycle is shortened from more than 120 days to 45-60 days, and the simultaneous removal of organic pollutants and heavy metals is achieved (comprehensive removal rate>90%), and the whole process is completed in situ without the risk of earthwork excavation and external transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 A perspective structural diagram of an organic contaminated soil bioremediation device provided by an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the side view structure of an organic contaminated soil bioremediation device provided by an embodiment of the present invention without a soil remediation component;

[0029] Figure 3 A schematic diagram of the structure of a soil remediation component in an organic contaminated soil bioremediation device provided by an embodiment of the present invention;

[0030] Figure 4A schematic diagram of the structure of the connection between the primary branch and the secondary branch in a device for bioremediation of organic contaminated soil provided by an embodiment of the present invention;

[0031] Figure 5 A schematic cross-sectional view of a composite layer in a device for bioremediation of organic contaminated soil provided by an embodiment of the present invention.

[0032] Description of reference numerals:

[0033] 1. Photovoltaic electrolysis component; 11. Electrolyzer; 12. Photovoltaic panel; 13. Positive electrode rod; 14. Negative electrode rod; 2. Mass transfer transition component; 21. Oxygen tank; 22. Hydrogen tank; 23. Nutrient solution tank; 24. Air pump; 25. Oxygen delivery pipe; 26. Hydrogen delivery pipe; 3. Soil remediation component; 31. Bionic root system body; 311. Support column; 3111. Nutrient solution channel; 3112. Oxygen channel; 3113. Hydrogen channel; 312. Primary branch; 3121. Hydrogen flow channel; 312 2. First oxygen flow channel; 3123. First nutrient solution flow channel; 3124. Pulse high-pressure hydrogen injection hole; 313. Secondary branch; 3131. Second oxygen flow channel; 3132. Second nutrient solution flow channel; 3133. Oxygen injection hole; 314. Cable tube; 3141. Wire; 3142. Optical fiber; 3143. Corrosion-resistant conductive contact; 32. Composite layer; 321. Biochar coating; 322. Graphene conductive grid layer; 323. Titanium dioxide nanofiber layer; 4. Intelligent control unit. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0035] In the description of this application, it should be understood that the words "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0036] See also Figures 1 to 5 An embodiment of the present application provides an organic contaminated soil bioremediation device, comprising a photovoltaic electrolysis component 1, a mass transfer transition component 2 and a soil remediation component 3 connected in sequence from top to bottom.

[0037] The photovoltaic electrolytic assembly 1 comprises an electrolytic cell 11, a photovoltaic panel 12 tilted above the electrolytic cell 11, and a positive electrode rod 13 and a negative electrode rod 14 inserted into an electrolyte, wherein the positive electrode rod 13 and the negative electrode rod 14 are electrically connected to the photovoltaic panel 12 respectively.

[0038] The mass transfer transition component 2 includes an oxygen tank 21, a hydrogen tank 22 and a nutrient solution tank 23. The oxygen tank 21 and the hydrogen tank 22 are respectively connected to an oxygen delivery pipe 25 and a hydrogen delivery pipe 26 with an air pump 24. The oxygen delivery pipe 25 and the hydrogen delivery pipe 26 both extend above the liquid surface of the electrolytic cell 11.

[0039] The soil remediation component 3 includes a bionic root system body 31 and a composite layer 32. The bionic root system body 31 includes a support column 311, a primary branch 312 and a secondary branch 313. An oxygen pipe, a hydrogen pipe and a cable pipe 314 are coaxially sleeved in the support column 311 to form a nutrient solution channel 3111, an oxygen channel 3112 and a hydrogen channel 3113 that are not connected to each other.

[0040] The first-level branch 312 is provided with a hydrogen flow channel 3121, a first oxygen flow channel 3122 and a first nutrient solution flow channel 3123 which are not connected to each other, and are respectively connected to the hydrogen channel 3113, the oxygen channel 3112 and the nutrient solution channel 3111; the second-level branch 313 is provided with a second oxygen flow channel 3131 and a second nutrient solution flow channel 3132 which are not connected to each other, the second oxygen flow channel 3131 is connected to the first oxygen flow channel 3122, the second nutrient solution flow channel 3132 is connected to the first nutrient solution flow channel 3123, and the nutrient solution in the first nutrient solution flow channel 3123, the second nutrient solution flow channel 3132 and the nutrient solution channel 3111 can all flow into the composite layer 32.

[0041] The composite layer 32 covers the surface of the bionic root system body 31 and includes a biochar coating 321 , a graphene conductive grid layer 322 and a titanium dioxide nanofiber layer 323 stacked from the inside to the outside.

[0042] The cable tube 314 has an optical fiber 3142 with a UV LED chip and a wire 3141 connected to the negative pole of the photovoltaic panel 12. The wire 3141 is used to extend to the soil and has a corrosion-resistant conductive contact 3143 at the end. The optical fiber 3142 extends to the titanium dioxide nanofiber layer 323.

[0043] A pulsed high-pressure hydrogen injection hole 3124 is provided at the end of the primary branch 312 , and an oxygen injection hole 3133 with a hydrophobic membrane is provided at the end of the secondary branch 313 .

[0044] Exemplarily, the photovoltaic electrolysis assembly 1 includes an electrolytic cell 11, a photovoltaic panel 12 fixed above the electrolytic cell 11 at an angle of 30°, and a positive electrode rod 13 and a negative electrode rod 14 inserted into the electrolyte. The positive electrode rod 13 is connected to the positive electrode of the photovoltaic panel 12 through a copper wire 3141, and the negative electrode rod 14 is connected to the negative electrode of the photovoltaic panel 12 through a graphene coated wire 3141 to form a closed loop. The electrolyte is a 0.5M sodium sulfate solution (to enhance conductivity and avoid chlorine side reactions). The photovoltaic panel 12 converts solar energy into electrical energy to drive the water electrolysis reaction:

[0045] Anode reaction (positive electrode 13): 4OH - →O2↑+2H2O+4e -

[0046] Cathode reaction (negative electrode rod 14): 4H2O+4e - →2H2↑+4OH -

[0047] The generated O2 and H2 are transported to the mass transfer transition component 2 through the oxygen delivery pipe 25 and the hydrogen delivery pipe 26 respectively.

[0048] The mass transfer transition component 2 has a container box, which is divided into an oxygen bin 21, a hydrogen bin 22, and a nutrient solution bin 23 located between the oxygen bin 21 and the hydrogen bin 22 by a vertical partition. The oxygen bin 21 is connected to the first air pump 24 and the oxygen delivery pipe 25, and the hydrogen bin 22 is connected to the second air pump 24 and the hydrogen delivery pipe 26. The two pipes extend to 10 cm above the liquid level of the electrolytic cell 11 to prevent liquid backflow. The nutrient solution bin 23 stores a slow-release solution containing potassium nitrate (0.1M) and sodium dihydrogen phosphate (0.05M), which is transported to the soil remediation component 3 through the nutrient solution channel 3111 by gravity to provide nitrogen and phosphorus nutrient sources for microorganisms.

[0049] The support column 311 is coaxially sleeved with an oxygen tube, a hydrogen tube and a cable tube 314 from outside to inside, forming a nutrient solution channel 3111, an oxygen channel 3112 and a hydrogen channel 3113 that are not connected to each other. A plurality of primary branches 312 are provided in the radial direction of the support column 311 to form a primary branch 312 group, and a plurality of primary branch 312 groups are arranged at intervals along the axial direction of the support column 311. The primary branch 312 is provided with three layers of flow channels that are not connected to each other, specifically a hydrogen flow channel 3121, a first oxygen flow channel 3122, and a first nutrient solution flow channel 3123, which are connected to the hydrogen channel 3113, the oxygen channel 3112 and the nutrient solution channel 3111 respectively. The first nutrient solution flow channel 3123 is located in the outermost layer, the first oxygen flow channel 3122 is located in the middle layer, and the hydrogen flow channel 3121 is located in the innermost layer, so that the nutrient solution in the nutrient solution flow channel can be closest to the composite layer 32. The second branch 313 is provided with a second oxygen flow channel 3131 and a second nutrient solution flow channel 3132, which are respectively connected to the first oxygen flow channel 3122 and the first nutrient solution flow channel 3123 of the first branch 312. Here, hydrogen and oxygen are effectively isolated by the first branch 312 and the second branch 313, and the hydrogen flow channel 3121 and the first oxygen flow channel 3122 in the first branch 312, which are not connected to each other, to avoid subsequent interference with the reduction reaction and the oxidation reaction.

[0050] See also Figure 3 and Figure 5 The composite layer 32 includes a biochar coating 321, a graphene conductive mesh layer 322, and a titanium dioxide nanofiber layer 323. The biochar coating 321 covers the surface of the primary branch 312, the secondary branch 313, and the support column 311, the graphene conductive mesh layer 322 covers the biochar coating 321, and the titanium dioxide nanofiber layer 323 covers the graphene conductive mesh layer 322. The biochar coating 321 is made of pyrolyzed crop straw (500°C anoxic pyrolysis), has a thickness of 200-500μm, a porosity of ≥80%, and is used to adsorb heavy metals (such as Pb 2 +、Cd 2 +) and hydrophobic organic matter (such as polycyclic aromatic hydrocarbons). The graphene conductive grid layer 322 is grown on the surface of biochar by chemical vapor deposition, with a grid aperture of 50-200nm and a conductivity of >106s / m, serving as a high-speed channel for electron transfer. The titanium dioxide nanofiber layer 323 is prepared on the graphene surface by electrospinning, with a fiber diameter of 50-100nm and a specific surface area of ​​more than 200m2 / g, and generates strong oxidizing holes (h + ) and free electrons (e - ).

[0051] A pulsed high-pressure hydrogen injection hole 3124 is provided at the end of the primary branch 312, with a hole diameter of 20-50 μm, connected to a 0.3-0.5 MPa air pump 24, which intermittently releases hydrogen at a frequency of 1-5 Hz to form a localized anaerobic micro-zone (ORP<-200 mV).

[0052] The end of the secondary branch 313 is provided with an oxygen injection hole 3133 with a PTFE hydrophobic membrane (contact angle>150°), with a pore size of 5-10 μm, which slowly releases oxygen to maintain the dissolved oxygen concentration in the aerobic zone to 2-4 mg / L.

[0053] The wavelength of the UV LED chip is 365nm and the power is 10-50mW / cm 2 , ultraviolet light is transmitted to the titanium dioxide nanofiber layer 323 through the optical fiber 3142, exciting electron-hole pairs, the holes directly oxidize the organic matter, and the electrons are transmitted to the contaminated interface through the graphene to strengthen the reduction reaction.

[0054] Exemplarily, the electron transfer path is: the negative electrode of the photovoltaic panel 12 → the wire 3141 → the anti-corrosion conductive contact 3143 → the soil → the graphene conductive grid layer 322 → the pollutant interface. The electrons drive the Cr6+ reduction (Cr 6+ +3e - →Cr 3+ ↓) and dechlorination reaction (C2HCl3+2e - →C2H2Cl+HCl).

[0055] The path of dynamic release of nutrient solution is: nutrient solution is slowly released to soil through the nutrient solution flow channel of the primary branch 312 → the nutrient solution microchannel of the secondary branch 313 → the micro-permeable pores (pore size 1-5 μm) of the composite layer 32, maintaining the carbon-nitrogen ratio and metabolic activity of microorganisms. It should be noted that a plurality of first permeable micropores are provided on the surface of the support column 311, and the plurality of first permeable micropores are arranged at intervals along the surface of the support column 311. The biochar coating 321 is also covered on the first permeable micropores because it covers the surface of the support column 311, so that part of the nutrient solution in the support column 311 can directly penetrate into the biochar coating 321 through the first permeable micropores. Similarly, a plurality of second permeable micropores are provided on the surface of the primary branch 312, and a plurality of third permeable micropores are provided on the surface of the secondary branch 313, so that the nutrient solution in the first nutrient solution flow channel 3123 can penetrate into the biochar coating 321 through the second permeable micropores, and the nutrient solution in the second nutrient solution flow channel 3132 can penetrate into the biochar coating 321 through the third permeable micropores.

[0056] In summary, the technical solution provided by the present application converts solar energy into electrical energy to drive water electrolysis through the photovoltaic electrolysis component 1, and simultaneously generates high-purity oxygen and hydrogen in the electrolytic cell 11. The oxygen is transported to the hydrophobic membrane oxygen injection hole 3133 at the end of the secondary branch 313 through the oxygen chamber 21 of the mass transfer transition component 2, and the dissolved oxygen concentration (2-4 mg / L) in the aerobic zone of the soil is accurately maintained through the micropore slow release mechanism, activating aerobic bacteria to rapidly mineralize organic pollutants such as benzene series and petroleum hydrocarbons; hydrogen is transported to the pulsed high-pressure injection hole of the primary branch 312 through the hydrogen chamber 22, and the hydrogen is injected into the deep soil in the form of micron-sized bubbles through intermittent high-pressure pulses (1-5 Hz). , forming a stable anaerobic micro-zone (ORP<-200mV) in the low permeability area, providing continuous electron donors for dehalogenating bacteria, and increasing the reduction and dechlorination rate of chlorinated hydrocarbons by 3-5 times; in the biochar-photocatalytic composite layer 32 on the surface of the bionic root system, the ultraviolet LED excites the titanium dioxide nanofibers to produce highly active holes and free electrons. The holes directly oxidize the chain-breaking and difficult-to-degrade organic matter (such as polycyclic aromatic hydrocarbons) to generate easily degradable small molecule products, while the electrons are transmitted to the pollution interface through the graphene conductive grid, and cooperate with the electrons released by hydrogen to enhance the reduction and precipitation of heavy metals; the nutrient solution channel 3111 continuously transports nitrates and phosphates to the microbial enrichment area to maintain the metabolic activity of the bacterial community. In general, the triple mechanism of gas zoning and graded controlled release to accelerate microbial metabolism, photocatalytic-electrochemical synergistic pretreatment of pollutants, and in-situ electron targeted transfer can shorten the traditional microbial remediation cycle from more than 120 days to 45-60 days, while achieving simultaneous removal of organic pollutants and heavy metals (comprehensive removal rate > 90%). The entire process is completed in situ without the risk of excavation and transportation.

[0057] Specific experimental examples:

[0058] In the presence of benzopyrene (50ppm) and Cr 6+ (200ppm) contaminated soil, after the device was operated for 45 days:

[0059] Benzopyrene degradation rate: 92% (traditional bioremediation takes 120 days to achieve the same effect);

[0060] Cr6+ reduction rate: 95% (traditional chemical reduction method takes 60 days and produces sludge).

[0061] In some embodiments, the aperture of the pulsed high-pressure hydrogen injection hole 3124 is 20-50 μm, the pulse frequency is 1-5 Hz, and the contact angle of the hydrophobic film is greater than 150°.

[0062] Exemplarily, the pulsed high-pressure hydrogen injection hole 3124 at the end of the primary branch 312 is made by laser precision machining technology, with an aperture range of 20-50 μm, specifically 30 μm in this embodiment, and is linked with the solenoid valve at the end of the hydrogen channel 3113 to release 0.4 MPa high-pressure hydrogen at a pulse frequency of 3 Hz (range 1-5 Hz) to form a micron-sized bubble group with a diameter of 50-100 μm, which penetrates the low-permeability clay layer (permeability coefficient <10-6 cm / s) and establishes an anaerobic micro-zone with an ORP <-200 mV in the soil pores, so that the dehalogenating bacteria are resistant to trichloroethylene. The dechlorination rate of olefins is increased to 0.8mmol / (L·h) (the traditional diffusion method is 0.2mmol / (L·h)); the oxygen injection hole 3133 at the end of the secondary branch 313 is covered with a PTFE hydrophobic membrane with a contact angle of 158°±2°, a film thickness of 50μm, and a pore size of 0.2μm. It is bonded to the branch shell through a chemical vapor deposition process. Under the condition of 30%-50% soil moisture content, the oxygen release rate is stabilized at 0.5L / min±5%, and the dissolved oxygen concentration is maintained at 2-4mg / L, ensuring that the degradation efficiency of aerobic bacteria to benzene series is greater than 90%. This embodiment solves the problem of repair cycle fluctuations caused by uneven traditional gas diffusion by breaking through capillary resistance and synergistic effects of super hydrophobic membrane anti-wetting properties through high-voltage pulses, while avoiding blockage of the flow channel caused by water and gas mutual channeling, so that the repair cycle of composite contaminated soil is shortened to 40-50 days.

[0063] It should be noted that a contact angle of >150° is an indicator of super-hydrophobicity, ensuring that the oxygen injection hole 3133 can still maintain the oxygen release function under heavy rain conditions (water content >60%). Micron-sized bubbles can increase the gas-liquid interface area, promote hydrogen dissolution and microbial uptake, and increase the electron utilization rate to 90%.

[0064] The end of the support column 311 inserted into the soil is set to a conical shape to provide greater insertion pressure, and the ends of the primary branch 312 and the secondary branch 313 are also set to a conical shape to assist the device in inserting into the soil. As for the oxygen injection hole 3133 and the hydrogen injection hole, the oxygen injection hole 3133 can be set on the side of the conical shape of the secondary branch 313, and the hydrogen injection hole can be set on the side of the conical shape of the primary branch 312.

[0065] In some embodiments, the titanium dioxide nanofiber layer 323 is doped with trivalent iron ions or nitrogen elements, so that the titanium dioxide nanofiber layer 323 has visible light response characteristics, and the response wavelength range is 400-550nm.

[0066] Exemplarily, the titanium dioxide nanofiber layer 323 is prepared by a sol-gel method and an electrospinning process: tetrabutyl titanate, ferric acetylacetonate or urea is dissolved in a molar ratio (TiO2:Fe=100:1 or TiO2:N=10:1) in an ethanol-acetic acid mixed solution, and electrospun (voltage 15kV, spinning distance 15cm) to form nanofibers with a diameter of 80-120nm, and then calcined in an air atmosphere at 500℃ for 2 hours to obtain anatase titanium dioxide fiber doped with trivalent iron ions or nitrogen elements. After doping, the band gap of the fiber is reduced from 3.2eV to 2.5-2.8eV (trivalent iron ion doping) or 2.3-2.5eV (nitrogen doping), and electron-hole pairs can be excited under irradiation with visible light of a wavelength in the range of 400-550nm (such as the blue-green region of the solar spectrum), and the photocatalytic activity is increased by 3 times compared with undoped titanium dioxide (in terms of methylene blue degradation rate). For example, the quantum efficiency of trivalent iron ion doped fiber under 450nm illumination is 12%. The trivalent iron ions in its lattice act as electron traps to suppress carrier recombination, while the interstitial states introduced by nitrogen doping broaden the light response range. The technical solution of this embodiment can efficiently degrade pollutants under natural lighting conditions (without the need for additional ultraviolet light sources), and the applicable scenarios are expanded to indoor or weak light areas, with an overall energy efficiency improvement of 40%.

[0067] It should be noted that the visible light response characteristic refers to the property of the material to absorb photons in the visible light band (400-550nm) and produce a photocatalytic reaction, which reduces dependence on ultraviolet light and improves the utilization rate of solar energy. The doping of trivalent iron ions or nitrogen elements is to regulate the band structure of titanium dioxide through element doping. The trivalent iron ions act as electron acceptors to reduce recombination, and the nitrogen elements form oxygen vacancies to enhance light absorption. Anatase refers to one of the crystal phases of titanium dioxide, which has higher photocatalytic activity than the rutile phase, and its crystal face is the reaction active site.

[0068] In some embodiments, the surface of the support column 311 is provided with a spiral guide groove (not shown in the figure), the pitch of the spiral guide groove is 5-10mm, the depth is 2-5mm, and it is used to enrich pollutants and guide them to migrate to the composite layer 32. It should be noted that because the inner diameter of the spiral guide groove is small, when the composite layer 32 is covered on the surface of the support column 311, a cavity, that is, the groove space, can still be formed at the spiral guide groove. When the composite layer 32 is formed on the surface of the support column 311, special attention can be paid to the molding of the composite layer 32 to avoid it completely covering the spiral guide groove.

[0069] Exemplarily, the surface of the support column 311 is processed by a CNC milling machine to form a right-handed spiral guide groove with a pitch of 8 mm (and a depth of 3 mm. The surface of the groove is coated with polytetrafluoroethylene (friction coefficient <0.1) to enhance the sliding effect of pollutants. The rotation direction of the spiral guide groove is consistent with the rotation direction of the support column 311 when it is inserted into the soil. During the insertion process, the pollutants (such as polycyclic aromatic hydrocarbons and heavy metal colloids) dispersed and adsorbed on the soil particles are enriched in the groove by centrifugal force, and the pollutants are guided to migrate to the composite layer 32 along the spiral path in combination with the capillary action of the soil. Actual measurements show that the spiral guide groove increases the pollutant concentration 10 cm below the surface by 3.2 times (compared with the structure without grooves), the migration rate of PAHs (polycyclic aromatic hydrocarbons) in the clay layer is increased from 0.2 mm / h to 0.8 mm / h, and the enrichment efficiency of Cr6+ in the sand layer is 85%. This embodiment breaks the diffusion bottleneck of low-permeability soil through the physical enrichment-directional migration mechanism, increases the processing load of the composite layer 32 by 2.5 times, and shortens the repair cycle by 30%.

[0070] In some embodiments, the bifurcation angle between the primary branch 312 and the secondary branch 313 ranges from 60° to 80°, and the diameter of the secondary branch 313 is 1 / 3 to 1 / 2 of the diameter of the primary branch 312 .

[0071] Exemplarily, along the top-down direction, the bifurcation angle of the primary branch 312 and the secondary branch 313 is set to 70°, and the diameter of the secondary branch 313 is 1 / 2 of the primary branch 312. Through the 3D printing process, they are integrally formed to form a fractal structure that imitates plant roots. For example, the primary branch 312 has a diameter of 8mm, the secondary branch 313 has a diameter of 4mm, and the bifurcation angle is 70°. In sandy soil, a repair area with a radius of 30cm can be covered, which is conducive to improving the coverage efficiency. After the bifurcation angle and diameter ratio are optimized, the oxygen and hydrogen injection flow fields do not interfere with each other (spacing>5cm), and the thin diameter of the secondary branch 313 is adapted to the deep soil penetration requirements (penetration depth>1.5m), while ensuring that the branch structure bending strength>50MPa. Actual measurements show that this parameter combination improves the uniformity of oxygen diffusion by 35% in clay, reduces the hydrogen injection blind area by 60%, and achieves a comprehensive repair efficiency of 93%.

[0072] See also Figure 2 The device also includes an intelligent control unit 4, which includes:

[0073] Potential monitoring module, used to monitor soil redox potential in real time and adjust hydrogen injection pressure;

[0074] A spectrum analysis module, which feeds back the intensity of ultraviolet light through the optical fiber 3142 to control the power of the ultraviolet LED chip;

[0075] Dynamic liquid distribution module adjusts the nutrient solution release rate according to the soil pH value.

[0076] Exemplarily, the intelligent control unit 4 is integrated into the device control cabinet, wherein the potential monitoring module collects the soil redox potential (ORP) in real time through the platinum-silver chloride composite electrode buried at the end of the primary branch 312. When ORP>-150mV is detected, the PID controller increases the hydrogen injection pressure to 0.5MPa (default 0.3MPa) to reduce the ORP of the anaerobic zone to below -250mV to ensure the activity of dechlorinating bacteria; the spectral analysis module receives the reflection spectrum of the titanium dioxide layer through the optical fiber 3142. When the absorption peak shift at 520nm is detected to be>5nm (indicating catalyst deactivation), the ultraviolet LED power is automatically increased to 40mW / cm 2 (Default 30mW / cm 2 ), restore the photocatalytic efficiency; the dynamic liquid distribution module has a built-in pH sensor and a proportional valve. When the soil pH is less than 6, sodium dihydrogen phosphate buffer (0.1M) is released into the nutrient solution flow channel to stabilize the pH at 6.5-7.5. At the same time, the nitrate release rate is dynamically adjusted according to the ORP data (0.05-0.2mL / min). This unit reduces the volatility of the microbial degradation rate from ±18% to ±3% through multi-parameter closed-loop feedback, improves the photocatalytic efficiency by 25%, and shortens the comprehensive repair cycle to 40 days. It should be noted that the pH sensor in the dynamic liquid distribution module can be separately arranged near the bionic root body 31 inserted into the soil, and then connected to the processor signal in the intelligent control unit 4. The proportional valve can be arranged on a pipeline for conveying buffer, which can be connected to the nutrient solution tank 23. The buffer can be contained in a separate container, and the proportional valve is also connected to the processor signal in the intelligent control unit 4.

[0077] In some embodiments, the corrosion-resistant conductive contact 3143 is a platinum-plated ceramic sheet or a graphene-coated electrode, and the surface roughness of the corrosion-resistant conductive contact 3143 is in the range of Ra 0.8-1.6 μm.

[0078] In one example, the corrosion-resistant conductive contact 3143 is a platinum-plated ceramic sheet connecting the wire 3141, with a 96% alumina ceramic as the substrate. After the surface is sandblasted, a 2-3μm platinum layer is deposited through an electroplating process. In soil with a pH of 2-12 (such as acidic mine wastewater or alkaline saline soil), the contact resistance is stable below 0.5Ω (traditional stainless steel contacts are >5Ω), and the annual corrosion rate is <0.01mm.

[0079] In another example, the corrosion-resistant conductive contact 3143 is a graphene coating, in which 3-5 layers of graphene are grown on a titanium alloy substrate by chemical vapor deposition, and the surface is laser etched to form a micro-nano structure of Ra0.8-1.6μm. The graphene coating increases the conductivity of the electrode to 106s / m, and enhances the ability to resist biofilm attachment (the amount of microbial attachment is reduced by 90%).

[0080] In some embodiments, the organic contaminated soil bioremediation device also includes a microalgae reactor (not shown in the figure), which is connected to the electrolytic cell 11 and is used to convert the carbon dioxide generated by electrolysis into biomass and regenerate the biochar coating 321 after pyrolysis.

[0081] Exemplarily, the microalgae reactor is connected to the carbon dioxide exhaust port of the electrolytic cell 11 through a pressure-resistant pipeline. As for the isolation of carbon dioxide from oxygen or hydrogen, a gas-liquid separation membrane can be used to separate carbon dioxide by utilizing the difference in gas density, and then the carbon dioxide is discharged from the carbon dioxide exhaust port. The separation of carbon dioxide during the electrolysis process belongs to the prior art and will not be described here. A columnar photobioreactor structure is used with a built-in grid culture unit to cultivate Chlorella vulgaris. Under the conditions of light intensity of 8000-10000 lux and temperature of 25-30°C, the carbon dioxide (concentration of 15-20%) produced by electrolysis is input into the reactor at a flow rate of 1.5L / min, and converted into biomass (yield 0.8g / L·d) through photosynthesis. The algae body is centrifugally dehydrated and mixed with aged biochar (adsorption saturated) at a mass ratio of 1:2, and co-pyrolyzed at 600°C in a nitrogen atmosphere for 2 hours to generate regenerated biochar (specific surface area increased from 300m of the original charcoal to 1.5L / min). 2 / g increased to 650m 2 / g, porosity>85%), and the algae-based carbon quantum dots loaded on its surface enhance the adsorption capacity of Cr6+ (from 45mg / g to 120mg / g). This embodiment realizes the closed-loop regeneration of carbon dioxide to biochar, with a carbon fixation efficiency of>90%, and at the same time, the abundance of functional groups (-COOH, -OH) of the regenerated carbon is increased by 2 times, strengthening the pollutant adsorption-photocatalytic synergistic effect.

[0082] In some embodiments, a pulse backwash valve is provided at the end of the hydrogen pipe, the backwash pressure range of the backwash valve is 0.5-0.8 MPa, the flushing frequency is once every 24 hours, and each time lasts 10-30 seconds.

[0083] Exemplarily, a pulse backwash valve is installed at the end of the hydrogen pipe. The valve body is made of 316L stainless steel and has a built-in piezoelectric ceramic driver (response time <1ms). The backwash program is triggered regularly by the intelligent control unit 4: it is started once every 24 hours, and high-pressure nitrogen (purity>99.99%) is reversely sprayed into the hydrogen pipe at a pressure of 0.65MPa for 20 seconds to flush the soil particles (particle size>10μm) and metal sulfides deposited in the flow channel out of the pipeline. The measured hydrogen flow recovery rate after flushing is>98%. The backwash nitrogen is recovered to the external gas tank through the branch end to avoid secondary pollution. This embodiment clears the flow channel blockages through regular high-pressure reverse pulses to ensure stable hydrogen transportation, extend the continuous operation cycle of the device, and reduce maintenance costs.

[0084] In some embodiments, the emission wavelength of the UV LED chip is in the range of 360nm-370nm, and the power density is in the range of 10-50mW / cm 2 , and a focusing lens is provided at the end of the optical fiber 3142 to focus the ultraviolet light onto the titanium dioxide nanofiber layer 323.

[0085] For example, the ultraviolet LED chip uses an aluminum gallium nitride chip with a peak wavelength of 365nm, and the power density is stabilized at 30mW / cm through a constant current drive circuit. 2 The chip is coupled to the end face of the quartz optical fiber 3142 through UV curing glue. The end of the optical fiber 3142 is fused with a hemispherical magnesium fluoride focusing lens to focus the ultraviolet light onto the surface of the titanium dioxide nanofiber layer 323. The spot diameter is reduced from 5mm to 1mm, and the light intensity density is increased to 120mW / cm 2 (30mW / cm when not focused 2 ). Actual measurements show that the technical solution of this embodiment increases the quantum efficiency of titanium dioxide from 0.8% to 2.5% (based on toluene degradation rate), and under the condition of 40% soil moisture content, the ultraviolet transmission loss is reduced from 50% to 15%, the photocatalytic reaction rate is increased by 3 times, and the comprehensive repair period is shortened to 35 days.

[0086] Finally, it should be noted that in any of the aforementioned embodiments, before the device repairs the soil, it is necessary to first pre-treat the soil to be repaired by removing impurities, screen out debris and large gravel, and use an Allu bucket to crush the material, and try to crush the contaminated soil into a particle size of less than 2 mm to avoid difficulty in inserting the device into the soil, as well as excessive soil viscosity and excessive particle size that may cause blockage or even damage to the bionic root body 31 of the device.

[0087] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0088] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0089] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more application embodiments, in the above description of the embodiments of this application, multiple features are sometimes merged into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0090] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this application is hereby incorporated by reference in its entirety, except for application history documents that are inconsistent with or conflicting with the content of this application, and documents that limit the broadest scope of the claims of this application (currently or later attached to this application). It should be noted that if the descriptions, definitions, and / or use of terms in the attached materials of this application are inconsistent or conflicting with the content of this application, the descriptions, definitions, and / or use of terms in this application shall prevail.

[0091] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A bioremediation device for organically contaminated soil, characterized in that: It includes a photovoltaic electrolysis component, a mass transfer transition component and a soil remediation component which are sequentially connected from top to bottom; The photovoltaic electrolysis assembly comprises an electrolytic cell, a photovoltaic panel obliquely arranged above the electrolytic cell, and a positive electrode rod and a negative electrode rod inserted into an electrolyte, wherein the positive electrode rod and the negative electrode rod are electrically connected to the photovoltaic panel respectively; The mass transfer transition component includes an oxygen tank, a hydrogen tank and a nutrient solution tank, wherein the oxygen tank and the hydrogen tank are respectively connected to an oxygen delivery pipe and a hydrogen delivery pipe with an air pump, and the oxygen delivery pipe and the hydrogen delivery pipe both extend above the liquid surface of the electrolyzer; The soil remediation component comprises a bionic root system body and a composite layer, wherein the bionic root system body comprises a support column, a primary branch and a secondary branch; an oxygen pipe, a hydrogen pipe and a cable pipe are coaxially sleeved in the support column to form a nutrient solution channel, an oxygen channel and a hydrogen channel that are not connected to each other; The primary branch is provided with a hydrogen flow channel, a first oxygen flow channel and a first nutrient solution flow channel which are not connected to each other, and are connected to the hydrogen channel, the oxygen channel and the nutrient solution channel respectively; the secondary branch is provided with a second oxygen flow channel and a second nutrient solution flow channel which are not connected to each other, the second oxygen flow channel is connected to the first oxygen flow channel, the second nutrient solution flow channel is connected to the first nutrient solution flow channel, and the nutrient solution in the first nutrient solution flow channel, the second nutrient solution flow channel and the nutrient solution channel can all flow into the composite layer; The composite layer covers the surface of the bionic root system body and includes a biochar coating, a graphene conductive grid layer and a titanium dioxide nanofiber layer stacked from inside to outside; The cable tube has an optical fiber with an ultraviolet LED chip and a wire connected to the negative electrode of the photovoltaic panel. The wire is used to extend to the soil and has a corrosion-resistant conductive contact at the end. The optical fiber extends to the titanium dioxide nanofiber layer. A pulsed high-pressure hydrogen injection hole is arranged at the end of the primary branch, and an oxygen injection hole with a hydrophobic membrane is arranged at the end of the secondary branch.

2. The organic contaminated soil bioremediation device according to claim 1, characterized in that: The aperture of the pulsed high-pressure hydrogen injection hole is 20-50 μm, the pulse frequency is 1-5 Hz, and the contact angle of the hydrophobic membrane is greater than 150°.

3. The organic contaminated soil bioremediation device according to claim 1, characterized in that: The titanium dioxide nanofiber layer is doped with trivalent iron ions or nitrogen elements, so that the titanium dioxide nanofiber layer has visible light response characteristics, and the response wavelength range is 400-550nm.

4. The organic contaminated soil bioremediation device according to claim 1, characterized in that: The surface of the support column is provided with a spiral guide groove, the pitch of the spiral guide groove is 5-10mm, and the depth is 2-5mm, which is used to enrich pollutants and guide them to migrate to the composite layer.

5. The organic contaminated soil bioremediation device according to claim 1, characterized in that: The bifurcation angle between the primary branch and the secondary branch ranges from 60° to 80°, and the diameter of the secondary branch is 1 / 3 to 1 / 2 of the diameter of the primary branch.

6. The device for bioremediation of organic contaminated soil according to any one of claims 1 to 5, characterized in that: The device further includes an intelligent control unit, which includes: Potential monitoring module, used to monitor soil redox potential in real time and adjust hydrogen injection pressure; A spectrum analysis module, which feeds back the intensity of ultraviolet light through an optical fiber to control the power of the ultraviolet LED chip; Dynamic liquid distribution module adjusts the nutrient solution release rate according to the soil pH value.

7. The organic contaminated soil bioremediation device according to claim 1, characterized in that: The corrosion-resistant conductive contact is a platinum-plated ceramic sheet or a graphene-coated electrode, and the surface roughness of the corrosion-resistant conductive contact is in the range of Ra0.8-1.6 μm.

8. The organic contaminated soil bioremediation device according to claim 1, characterized in that: The organic contaminated soil bioremediation device also includes a microalgae reactor, which is connected to the electrolytic tank and is used to convert carbon dioxide generated by electrolysis into biomass and store it.

9. The organic contaminated soil bioremediation device according to claim 1, characterized in that: A pulse backwash valve is provided at the end of the hydrogen pipe. The backwash pressure range of the backwash valve is 0.5-0.8 MPa. The backwash frequency is once every 24 hours, and each time lasts for 10-30 seconds.

10. The organic contaminated soil bioremediation device according to claim 1, characterized in that: The emission wavelength range of the UV LED chip is 360nm-370nm, and the power density range is 10-50mW / cm 2 , and a focusing lens is provided at the end of the optical fiber to focus the ultraviolet light onto the titanium dioxide nanofiber layer.

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