A device and method for simultaneous removal of multi-target pollutants in groundwater

Abstract

The application discloses a device and method for synchronously removing multi-target pollutants in underground water, and relates to the technical field of underground water pollution remediation. The device and method for synchronously removing multi-target pollutants in underground water comprise a permeable reaction wall, a first unit is arranged on the right side of the permeable reaction wall, a water-permeable grid is arranged on the right side of the first unit, and a sample automatic detection and analysis device is arranged above the water-permeable grid. The device and method for synchronously removing multi-target pollutants in underground water are based on the combined physical-chemical-plant remediation technology of electromotive force, and multi-stage reinforced treatment is performed on pollutants based on the synergistic effect of adsorption-electrochemistry-plant enrichment-microbial degradation, so that efficient and persistent removal of heavy metals, inorganic and organic compounds and other composite pollutants in underground water is realized, the problem of difficult collaborative management of multiple pollutants is solved, and the device and method have the advantages of simple construction, low installation cost, efficient remediation, strong applicability, ecological environmental protection and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of groundwater pollution remediation, in particular to a device and method for simultaneous removal of multiple target pollutants in groundwater. BACKGROUND

[0002] With the rapid development of economy and industry, the discharge of domestic sewage, industrial wastewater, and leachate from solid waste has significantly increased the harmful substances in groundwater, such as heavy metals, bacteria, inorganic salts, and organic matter. Soil and groundwater pollution is becoming increasingly serious, threatening human health and ecological safety, and hindering sustainable economic development. Therefore, soil and groundwater pollution remediation is imminent.

[0003] Currently, groundwater pollution remediation technologies mainly include physical, chemical, and biological technologies. Physical technologies include air stripping, air stripping, multi-phase extraction, in-situ thermal treatment, adsorption, and electrokinetics. Chemical technologies include oxidation-reduction, leaching, and extraction treatment. Biological technologies include plant and microbial methods. Phytoremediation is a process that uses plants to absorb, stabilize, and decompose and remove pollutants in contaminated soil or groundwater. Microbial remediation is a process that uses microbial enrichment and microbial transformation to degrade pollutants in soil. Plant remediation with adsorption of filled substrate, assimilation of plants, and microbial degradation can remove nitrogen, phosphorus, heavy metals, and organic matter in water. Due to differences in composition, type, and properties of underground water media, especially in the case of multiple pollutants, single remediation technology has obvious shortcomings and cannot achieve the remediation goal. Coupling multiple technologies is one of the effective measures to solve the problem of soil and groundwater pollution.

[0004] Permeable reactive barrier (PRB), electrokinetic remediation (EKR), and phytoremediation are emerging in-situ remediation technologies for soil and groundwater. Permeable reactive barrier is a technology that uses adsorption, precipitation, surface complexation, oxidation-reduction, and biodegradation to intercept or remove pollutants in groundwater by filling specific active fillers in the wall. It can effectively remove inorganic salts, highly toxic heavy metals such as cadmium, chromium, and lead, and various pollutants such as chloroethylene organic pollutants. PRB can treat multiple pollutants for a long time with little disturbance to groundwater, and has the advantages of no need for external power, simple construction, etc. However, factors such as pollutant characteristics, hydrogeological conditions, economic benefits, and environmental impact of on-site construction need to be considered. Electrokinetics is a technology that uses electrodes to apply a direct current voltage to the contaminated site to migrate pollutants to the two sides of the electrodes and thus remediate the pollution. The solubility of pollutants has a significant impact on the treatment effect. When there are a large number of metal ions and negatively charged acid ions in soil and groundwater, significant electro-migration will occur. Electrokinetic remediation is not effective for pollutants with poor solubility, weak desorption ability, and non-polar organic matter.

[0005] The combination of electrokinetic remediation and other remediation technologies is increasingly valued, and the combination of permeable reactive barrier-electrokinetic-phytoremediation (PRB-EKR-Phytoremediation) is becoming a research hotspot in the field of soil and groundwater environmental remediation at home and abroad. The combination of permeable reactive barrier-electrokinetic-phytoremediation combines the advantages of each technology, and comprehensively utilizes physical, chemical, electrochemical, biological and ecological effects, which can effectively improve the removal efficiency of pollutants and reduce the remediation cost. The basic principle is to remove heavy metals, inorganic salts and organic pollutants and other complex pollutants by PBR for primary pollution remediation; and to remove heavy metals, inorganic salts and organic pollutants by electrokinetic-phytoremediation coupling technology for secondary pollution remediation, under the action of electrokinetic force, the pollutants are removed by adsorption of filler matrix, microbial degradation and plant absorption.

[0006] The existing technology generally couples electrokinetic remediation with permeable reactive barrier, phytoremediation and other single technologies, mainly aiming at the removal of single pollutants, or achieving the removal of pollutants through traditional adsorption and plant absorption. How to simultaneously and efficiently remove COD, nitrogen, phosphorus, heavy metals, inorganic salts and organic matter in a contaminated site still faces great challenges. So far, the existing soil and groundwater remediation technology cannot effectively treat complex pollutants. SUMMARY

[0007] (I) Technical problems solved

[0008] In view of the deficiencies of the prior art, the present application provides a device and method for simultaneous removal of multiple target pollutants in groundwater, which solves the problems existing in the prior art.

[0009] (II) Technical solutions

[0010] In order to achieve the above purpose, the present application is realized by the following technical solutions: a device and method for simultaneous removal of multiple target pollutants in groundwater, comprising a permeable reactive barrier, a first unit is arranged on the right side of the permeable reactive barrier, a water permeable grid is arranged on the right side of the first unit, a sample automatic detection and analysis device is arranged above the water permeable grid, a second unit is arranged on the right side of the water permeable grid, a waterproof wall and a grid filter screen are arranged on the right side of the second unit, the waterproof wall is arranged below the grid filter screen, a phytoremediation zone is arranged on the right side of the grid filter screen, a pool bottom is arranged at the bottom of the phytoremediation zone, a cathode and an anode are arranged in the phytoremediation zone, a deep purification module is arranged on the right side of the phytoremediation zone, the deep purification module comprises a pool, a biomimetic filler is arranged on the right side of the pool, a water outlet pool is arranged on the right side of the biomimetic filler, the water outlet pool comprises a pool, and a pool bottom is arranged at the bottom of the pool.

[0011] Preferably, the permeable reaction wall is 1m deeper than the groundwater pollution plume, the distance between two adjacent walls is 2-5m, and a water-permeable grid is arranged in the middle of the wall to divide the reaction zone into a first unit and a second unit. The grid is a hole-shaped grid welded by longitudinal and transverse steel bars, and the hole distance is 2-5cm.

[0012] Preferably, the first unit wall is composed of a steel framework and a water-permeable geotextile, and the steel framework is coated with the water-permeable geotextile. The steel framework is formed by longitudinally and transversely welding a plurality of stainless steel solid pipes, the pipe diameter is 12-20mm, the framework width is 30-50cm, and the water-permeable geotextile has a permeability coefficient greater than 5.0*10-5m / s.

[0013] Preferably, the second unit wall is composed of a water-impermeable cutoff wall and a grid filter, and the top of the cutoff wall is located in the middle of the first unit wall, and the top is provided with the grid filter, and the grid hole size is 1cm-2cm.

[0014] Preferably, the first unit is filled with adsorbing filler, which is one of iron ore, activated zeolite, volcanic rock, and ceramic ball, or a composite filter material, and the particle size is 2-8mm; and the second unit is filled with active filler, which is a biochar composite filler, and the filler is a spherical porous particle with a particle size of 2-4mm. The material filling needs to make the permeability coefficient of the wall and the reaction zone higher than 2-5 times the permeability coefficient of the aquifer.

[0015] The biochar composite filler includes 40%-50% of bentonite modified biochar, 20%-25% of zero-valent iron, 10%-15% of clay, 7%-15% of diatomite, and 3%-5% of ammonium bicarbonate. The clay is used as a bonding raw material, the diatomite is used as a high-permeability raw material, and the ammonium bicarbonate is used as a pore-forming agent. The bentonite modified biochar is prepared by mixing and standing montmorillonite bentonite and biochar and then pyrolyzing them. The particle size of the montmorillonite bentonite is 0.05-0.1mm, the particle size of the biochar is 0.15-0.18mm, the mass ratio of the bentonite to the biochar is 1:8-20, the pyrolysis temperature is 500-800℃, and the pyrolysis time is 30-60min.

[0016] Preferably, the bottom surface of the plant remediation zone pool body and the deep purification module pool is a water-impermeable wall, and the bottom surface is flush with the top of the water-impermeable wall of the permeable reaction wall. The water outlet side wall is composed of a steel framework and a water-permeable geotextile.

[0017] The plant remediation zone pool body is filled with a substrate, which is one of gravel, sandstone, zeolite, anthracite, biological ceramic ball, manganese sand, steel slag, waste wood block, and corn cob particle, or a composite filler. Plants are planted on the upper part of the substrate. The combination ratio of the plant remediation zone substrate needs to be selected according to the water quality of the pollution plume and the standard requirement to select the most economical ratio.

[0018] The inorganic filler particle size of the gravel, sand, zeolite, etc. is 2-10 mm, and the organic filler particle size of the waste wood block, corn cob particle, etc. is 3-6 mm.

[0019] Preferably, the plant restoration zone is provided with an electrically powered restoration cathode and anode pair on both sides of the pool body, and under the action of a direct current electric field, the charged heavy metals or polar organic pollutants in the soil are removed by adsorption of the substrate, absorption of the plants, and microbial decomposition in the process of moving to the electrode with opposite charge by electromigration.

[0020] The cathode electrode and the anode electrode are any one of graphite rods, titanium, stainless steel, conductive metal organic framework materials, iron, or porous carbon materials.

[0021] The low-voltage direct-current power supply is a solar photovoltaic device, and when a direct current voltage is applied to the electrodes, a direct current electric field will be formed between the electrodes to drive the electrically powered restoration, and the voltage range is 0-50V.

[0022] Preferably, the deep purification module pool body is filled with biomimetic materials as microbial carriers, which are one or both of polypropylene ball fillers or carbon fiber water grass, for microbial biofilm formation.

[0023] Preferably, the pool bottom of the effluent pool is flush with the bottom surface of the deep purification module pool body, and the pool bottom is made of a strong permeability material as a drainage layer to make the purified water quickly infiltrate into the groundwater environment, and the effluent side wall is composed of a steel reinforcement frame and a water-permeable geotextile, and the pool body size is 0.5-0.8m;

[0024] The strong permeability material is a gravel and crushed stone composite layer, with a gravel particle size of 20-50 mm and a crushed stone particle size of 10-30 mm, and a thickness of 0.5-0.6m;

[0025] The plant restoration zone is added with plant growth-promoting bacteria (PGPB) to enhance the plant's tolerance to heavy metals, promote the plant's absorption of heavy metals and nutrients, and thus improve the plant restoration efficiency, and the plants include wetland plants and heavy metal hyperaccumulating herbaceous plants. The wetland plants include reed, cattail, iris, willow herb, lily, and other plants with strong purification ability, and the heavy metal hyperaccumulating plants have strong tolerance to Cr, Pb, Cu, Cd, etc., and include one or more of Dianthus acicularis, Pyrethrum, alfalfa, Lee's grass, pokeweed, Viola baoshanensis, Konjac, ryegrass, and Equisetum arvense.

[0026] A method for synchronously removing multiple target pollutants in groundwater by using the device, which comprises the device for synchronously removing multiple target pollutants in groundwater, and the specific operation is as follows:

[0027] The permeable reaction wall, the plant remediation zone, the deep purification module and the water outlet pool are arranged along the seepage direction of the groundwater pollution plume, and the modules are sequentially connected. The permeable reaction wall is filled with adsorption filter material and biochar composite filler. The plant remediation zone is filled with a substrate, plants are planted on the upper part of the substrate, and a pair of electric remediation anode and cathode electrodes are arranged in the substrate. The substrate is one of gravel, sandstone, zeolite, anthracite, biological ceramsite, manganese sand, steel slag, waste wood block and corn cob particles or a composite filler. The deep purification module is filled with biomimetic filler, and the biomimetic filler is used as a microbial carrier for microbial biofilm formation and is polypropylene ball filler or carbon fiber water grass. The pollution plume flows into the reaction zone of the permeable reaction wall, the filter material adsorbs heavy metals to remove part of the pollutants, and the active biochar composite filler adsorbs heavy metals, and zero-valent iron reduces and removes part of the organic pollutants. Residual pollutants enter the plant remediation zone, part of the pollutants are degraded by microorganisms in the filler substrate, and the other part of the heavy metal and other pollutants are absorbed and degraded by plants. Through two-stage intensified treatment, heavy metals and inorganic salt pollution are completely removed. The upstream water enters the deep purification module, high-efficiency microbial strains form biofilm on the biomimetic filler, residual organic matter and inorganic pollutants such as ammonia nitrogen are continuously degraded by microorganisms, and the water is deeply purified to meet the water quality standard.

[0028] (Three) beneficial effects

[0029] The application provides a device and method for synchronous removal of multiple target pollutants in groundwater.

[0030] The device and method for synchronous removal of multiple target pollutants in groundwater, through the combination of electromotive force and physical-chemical-plant remediation technology, based on the synergistic effect of adsorption-electrochemistry-plant enrichment-microbial degradation, multiple-stage intensified treatment is carried out on the pollutants, realizing efficient and persistent removal of heavy metals, inorganic and organic compounds and other complex pollutants in groundwater, solving the problem of collaborative governance of multiple pollutants, and having the advantages of simple construction, low installation cost, efficient repair, strong applicability, ecological environmental protection and the like.

[0031] Through the synergistic effect of the permeable reaction wall, electromotive force combined with plant remediation and deep purification module, multiple-stage intensified treatment is carried out, realizing integrated deep treatment of heavy metals, ammonia nitrogen, inorganic salt and organic compounds and other complex contaminated groundwater, and expanding the application range of electromotive force-plant coupled remediation technology.

[0032] The electromotive force-plant coupled remediation technology can accelerate the flow speed of groundwater and pollutants, and heavy metals, cations and polar organic pollutants in the soil migrate to the cathode under the action of a direct current electric field, and the pollutants are adsorbed by the substrate, absorbed by the plants and degraded by the microorganisms. At the same time, plant growth-promoting bacteria and substrate slow-release carbon sources are added to stimulate the growth of microorganisms, which can significantly improve the efficiency of plant remediation without causing secondary pollution.

[0033] The deep purification module is used for continuously degrading residual pollutants by microorganisms, so that the groundwater pollutants are efficiently and durably removed, and the PLC control system is used for determining the adding type, dosage and time of the microorganisms according to the water quality monitoring information, so that the automatic and intelligent operation is realized, the stability and utilization rate of the efficient degradation bacteria agent are effectively improved, and the problem of low pollutant removal rate is solved.

[0034] The zero-valent iron in the biochar composite filler is used for reducing heavy metals and pollutants, Fe2+ generated is absorbed by microorganisms and plants as nutrients and strengthens the growth and metabolism capacity of the microorganisms and plants, and the absorption and degradation of the pollutants are promoted. BRIEF DESCRIPTION OF DRAWINGS

[0035] Fig. 1 A cross-sectional view of the device and method for simultaneous removal of multi-target groundwater pollutants according to the embodiment of the present application;

[0036] Fig. 2 A plan view of the device and method for simultaneous removal of multi-target groundwater pollutants according to the embodiment of the present application;

[0037] Fig. 3 A schematic diagram of electrode arrangement according to the embodiment of the present application.

[0038] In the figure, 1 is a permeable reactive wall, 11 is a water-permeable grid, 12 is a first unit, 13 is a second unit, 14 is an impervious wall, 15 is a grid filter, 16 is a sample automatic detection and analysis device, 2 is a phytoremediation zone, 21 is a pool body, 22 is a cathode and anode, 23 is a pool bottom surface, 3 is a deep purification module, 31 is a pool body, 32 is a biomimetic filler, 4 is a water outlet pool, and 41 is a pool bottom. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0040] Please refer to Figs. 1-3The application provides a technical scheme: a device and method for synchronously removing multiple target pollutants in underground water, which comprises a permeable reaction wall 1, a first unit 12 is arranged on the right side of the permeable reaction wall 1, a water permeable grid 11 is arranged on the right side of the first unit 12, a sample automatic detection and analysis device 16 is arranged above the water permeable grid 11, a second unit 13 is arranged on the right side of the water permeable grid 11, a waterproof wall 14 and a grid filter screen 15 are arranged on the right side of the second unit 13, the waterproof wall 14 is arranged below the grid filter screen 15, a phytoremediation zone 2 is arranged on the right side of the grid filter screen 15, a pool bottom 23 is arranged at the bottom of the phytoremediation zone 2, a positive and negative electrode 22 is arranged in the phytoremediation zone 2, a deep purification module 3 is arranged on the right side of the phytoremediation zone 2, the deep purification module 3 comprises a pool body 21, a biomimetic filler 32 is arranged on the right side of the pool body 21, a water outlet pool 4 is arranged on the right side of the biomimetic filler 32, and the water outlet pool 4 comprises a pool body 31 and a pool bottom 41 is arranged at the bottom of the pool body 31.

[0041] The permeable reaction wall 1 has a depth greater than the depth of the underground water pollution plume 1m, the interval between two adjacent walls is 2-5m, the water permeable grid 11 is arranged in the middle of the wall to divide the reaction zone into the first unit 12 and the second unit 13, the grid is welded into a hole-shaped grid by longitudinal and transverse steel bars, and the hole interval is 2-5cm.

[0042] The wall of the first unit 12 is composed of a steel skeleton and a water permeable geotextile, and the steel skeleton is coated with the water permeable geotextile. The steel skeleton is composed of a plurality of stainless steel solid pipes welded longitudinally and transversely, the pipe diameter is 12-20mm, the skeleton width is 30-50cm, and the water permeable geotextile has a permeability coefficient greater than 5.0*10-5m / s.

[0043] The wall of the second unit 13 is composed of a water-impermeable waterproof wall and a grid filter screen, the top of the waterproof wall is located in the middle of the wall of the first unit, the grid filter screen is arranged at the top, and the grid hole size is 1cm-2cm.

[0044] The first unit 12 is filled with adsorbing filler, which is one of iron ore, activated zeolite, volcanic rock and ceramic ball or composite filter material, and the particle size is 2-8mm; the second unit 13 is filled with active filler, which is biochar composite filler, the filler is a spherical porous particle, and the particle size is 2-4mm. The material filling needs to make the permeability coefficient of the wall and the reaction zone be 2-5 times higher than the permeability coefficient of the aquifer.

[0045] The biochar composite filler component comprises bentonite modified biochar 40-50%, zero-valent iron 20-25%, clay 10-15%, diatomite 7-15%, ammonium bicarbonate 3-5%, clay as a binding raw material, diatomite as a high permeability raw material, and ammonium bicarbonate as a pore-forming agent.

[0046] The bottom surface of the plant remediation zone pool body 31 and the deep purification module pool bottom 41 is a water-impermeable wall, and the bottom surfaces are flush with the top of the water-impermeable wall of the permeable reaction wall.

[0047] The plant remediation zone 2 pool body is filled with a substrate, and the substrate is one or a composite filler selected from gravel, sandstone, zeolite, anthracite, biological ceramsite, manganese sand, steel slag, waste wood blocks, and corn cob particles, and plants are planted on the upper part of the substrate.

[0048] The particle size of the inorganic fillers such as gravel, sandstone, and zeolite is 2-10 mm, and the particle size of the organic fillers such as waste wood blocks and corn cob particles is 3-6 mm.

[0049] The plant remediation zone 2 pool body is provided with a pair of electric remediation cathode and anode electrodes 22 on both sides, and under the action of a direct current electric field, charged heavy metals or polar organic pollutants in the soil are removed by adsorption of the substrate, absorption of plants, and microbial decomposition in the process of moving to the electrode with opposite charges by electromigration.

[0050] The cathode electrode and the anode electrode are any one of a graphite rod, titanium, stainless steel, a conductive metal-organic framework material, iron, or a porous carbon material.

[0051] The low-voltage direct current power supply is a solar photovoltaic device, a direct current electric field is formed between the electrodes after a direct current voltage is applied to the electrodes, and the voltage range for driving the electric remediation is 0-50 V.

[0052] The deep purification module pool body 21 is filled with a biomimetic material as a microbial carrier, which is one or both of polypropylene ball fillers or carbon fiber water grass, for microbial biofilm formation.

[0053] The pool bottom 41 of the effluent pool is flush with the bottom surface of the deep purification module pool body 31, the pool bottom is a strong permeability material, as a drainage layer, so that the purified water body rapidly penetrates into the groundwater environment, the effluent side wall body is composed of a reinforced framework and a water-permeable geotextile, the pool body size is 0.5-0.8 m; the strong permeability material is a gravel and broken stone composite layer, the gravel particle size is 20-50 mm, the broken stone particle size is 10-30 mm, and the thickness is 0.5-0.6 m; the plant remediation zone 2 adds plant growth promoting bacteria PGPB to enhance the heavy metal resistance of the plants, promote the absorption of heavy metals and nutrient components by the plants, and thus improve the plant remediation efficiency, the plants include wetland plants and heavy metal hyperaccumulating herbaceous plants. The wetland plants include reed, cattail, iris, glasswort, impatiens, canna, and other plants with strong sewage purification capacity, the heavy metal hyperaccumulating plants have strong resistance to Cr, Pb, Cu, Cd and other heavy metals, and include one or more of Dianthus acicularis, Pyrrhopappus, alfalfa, Lee's grass, pokeweed, Viola baoshanensis, Impatiens balsamina, ryegrass, and Equisetum arvense.

[0054] A method of an underground water multi-target pollutant synchronous removal device, including the underground water multi-target pollutant synchronous removal device, and specifically operating as follows:

[0055] The permeable reaction wall, the plant remediation zone, the deep purification module and the effluent pool are arranged along the seepage direction of the groundwater pollution plume, and the modules are sequentially connected. The permeable reaction wall is filled with adsorption filter material and biochar composite filler; the plant remediation zone is filled with a substrate, plants are planted on the upper part of the substrate, and a pair of electric remediation anode and cathode electrodes are arranged in the substrate; the substrate is one or a composite filler of gravel, sandstone, zeolite, anthracite, biological ceramsite, manganese sand, steel slag, waste wood block and corn cob particles; the deep purification module is filled with biomimetic filler, which is used as a microbial carrier for microbial biofilm formation and is polypropylene ball filler or carbon fiber water grass; the pollution plume flows to the reaction zone of the permeable reaction wall, the filter material adsorbs heavy metals to remove part of the pollutants, and the active biochar composite filler adsorbs heavy metals while zero-valent iron reduces and removes part of the organic pollutants; the residual pollutants enter the plant remediation zone, part of the pollutants are degraded by microorganisms in the filler substrate, and another part of the heavy metal and other pollutants are absorbed and degraded by plants, so that the heavy metals and inorganic salts are completely removed through two-stage strengthening treatment; the upstream water body enters the deep purification module, high-efficiency microbial strains form a biofilm on the biomimetic filler, and residual organic matter and inorganic pollutants such as ammonia nitrogen are continuously degraded by microorganisms, so that the water is deeply purified to meet the water quality standard. Embodiment Embodiment 1

[0056] From Figs. 1-2It can be seen that the device and method for simultaneous removal of multi-target pollutants in groundwater of the embodiment, including the permeable reaction wall 1 and the filling material, the phytoremediation zone 2, the deep purification module 3 and the effluent tank 4, each module is sequentially communicated. The permeable reaction wall 1 is arranged along the seepage direction of the groundwater pollution plume, the wall depth is greater than the depth of the groundwater pollution plume by 1 m, the distance between the adjacent two walls is 2-5 m, and the water-permeable grid 11 is arranged in the middle of the wall to divide the reaction zone into the first unit 12 and the second unit 13. The grid is a hole-shaped grid welded by longitudinal and transverse steel bars, and the hole spacing is 2-5 cm. The first unit wall is composed of a steel framework and a water-permeable geotextile, and the steel framework is coated with the water-permeable geotextile outside. The steel framework is longitudinally and transversely welded by a plurality of stainless steel solid pipes, the pipe diameter is 12-20 mm, the framework width is 30-50 cm, the water-permeable geotextile has a permeability coefficient greater than 5.0*10 -5 m / s. The second unit wall is composed of a water-impermeable cutoff wall 14 and a grid filter 15, the top of the cutoff wall is located in the middle of the first unit wall, and the grid filter is installed at the top. The grid hole size is 1 cm-2 cm.

[0057] The first unit is filled with adsorbing filler, which is one of iron ore, activated zeolite, volcanic rock and ceramsite or a composite filter material, and the particle size is 2-8 mm. The iron ore is a divalent iron ore such as pyrite and siderite. The second unit is filled with active filler, which is biochar composite filler, the filler is a spherical porous particle, and the particle size is 2-4 mm. The material filling needs to make the permeability coefficient of the wall and the reaction zone higher than the permeability coefficient of the aquifer by 2-5 times. The active biochar composite filler is filled in a polyethylene mesh bag to prevent loss due to water flow impact, and the size of the polyethylene mesh bag is 0.5 m*0.3 m. The active filler can be filled on the ground first, sealed, then hoisted and placed in the second unit of the wall in layers. Specifically, the biochar composite filler composition includes bentonite modified biochar 40%-50%, zero-valent iron 20%-25%, clay 10%-15%, diatomite 7%-15%, ammonium bicarbonate 3%-5%, clay as a bonding raw material, diatomite as a high permeability raw material, and ammonium bicarbonate as a pore former. The bentonite modified biochar is prepared by mixing and standing montmorillonite bentonite and biochar and then pyrolyzing, the particle size of the montmorillonite bentonite is 0.05-0.1 mm, the particle size of the biochar is 0.15-0.18 mm, the mass ratio of the bentonite to the biochar is 1:8-20, the pyrolysis temperature is 500-800℃, and the pyrolysis time is 30-60 min.

[0058] The pollution plume converges to the reaction zone of the permeable reaction wall, the adsorbing filter material and the active biochar composite filler adsorb heavy metals, ammonia nitrogen, inorganic salts and organic pollutants, and the zero-valent iron reduces and removes part of the organic pollutants, and the preliminarily treated groundwater enters the phytoremediation zone.

[0059] The plant remediation zone 2 is composed of a pool body 21, a substrate, plants, and a cathode and anode 22. The bottom surface 23 of the pool body is a water-impermeable wall, the bottom surface is flush with the top of the water-resisting wall of the permeable reaction wall, and the water-outlet side wall is composed of a steel framework and a water-permeable geotextile. The pool body is filled with a substrate, the substrate is one of gravel, sandstone, zeolite, anthracite, biological ceramsite, manganese sand, steel slag, waste wood blocks, and corn cob particles, or a composite filler, and plants are planted on the upper part of the substrate. Specifically, the particle size of the inorganic fillers such as gravel and sandstone is 2-10 mm, the particle size of the organic fillers such as waste wood blocks and corn cob particles is 3-6 mm, and the organic fillers provide a carbon source for microorganisms. The combination ratio of the substrate needs to be selected according to the water quality of the pollution plume, the standard requirements, and the like to select the most economical ratio.

[0060] Specifically, a pair of electrically remediated cathode and anode electrodes are arranged on both sides of the pool body. Under the action of a direct current electric field, the charged heavy metals or polar organic pollutants in the soil are removed by adsorption of the substrate, absorption of the plants, and decomposition of the microorganisms in the process of moving to the electrodes with opposite charges by electromigration. The cathode electrode and the anode electrode are any one of a graphite rod, titanium, stainless steel, a conductive metal-organic framework material, iron, or a porous carbon material. The low-voltage direct-current power supply is a solar photovoltaic device. When a direct current is applied to the electrodes, a direct current electric field will be formed between the electrodes to drive the electric remediation, and the voltage range of the electric remediation is 0-60 V.

[0061] The residual pollutants enter the plant remediation zone, and the composite pollutants are continuously removed. A part of the pollutants such as COD and ammonia nitrogen are degraded by the microorganisms in the filler substrate, and another part of the pollutants such as heavy metals are absorbed and degraded by the plants. After two-stage intensified treatment, the heavy metal pollution is completely removed, and the treated upstream water body enters the deep purification module.

[0062] The deep purification module 3 is composed of a pool body 31 and a biomimetic filler 32. The bottom surface of the pool body is a water-impermeable wall, the bottom surface is flush with the top of the water-resisting wall of the permeable reaction wall, and the water-outlet side wall is composed of a steel framework and a water-permeable geotextile. The pool body is filled with a biomimetic material as a microbial carrier, which is one or both of polypropylene ball filler and carbon fiber water grass, for microbial biofilm formation. Specifically, the polypropylene ball filler has a filling density of 0.9 g / cm3, a diameter of 0.5-1.0 cm, and a filling ratio of not less than 75%. The distance between the carbon fiber grasses is 20-30 cm, and a weight is hung at the bottom of the water grass to keep the water grass vertically stretched. High-efficiency microbial strains are biofilm-formed on the biomimetic filler, and residual organic matter and inorganic pollutants such as ammonia nitrogen are continuously degraded by the microorganisms, thereby achieving deep purification of groundwater pollutants.

[0063] The purified water body enters the outlet pool 4, the outlet pool bottom 41 is flush with the bottom surface of the deep purification module pool body, the pool bottom is a strong permeability material, serving as a drainage layer, so that the purified water body rapidly penetrates into the underground water environment, the outlet side wall body is composed of a steel reinforcement framework and a water permeable geotextile, and the pool body size is 0.5-0.8 m. The strong permeability material is a gravel and broken stone composite layer, the gravel particle size is 20-50 mm, the broken stone particle size is 10-30 mm, and the thickness is 0.5-0.6 m.

[0064] Specifically, the plants include wetland plants and heavy metal hyperaccumulating herbaceous plants. The wetland plants include reed, cattail, iris, spikerush, pickerelweed, canna, and other plants with strong sewage purification capacity, and the heavy metal hyperaccumulating plants are highly resistant to Cr, Pb, Cu, Cd, and the like, and include one or more of Dianthus spicatato, Pyrethrum speciosum, Medicago sativa, Leersia oryzoides, Phytolacca acinosa, Viola betoniculata, Tagetes patula, Lolium multiflorum, and Eupatorium fortunei. Example 2

[0065] From Figs. 1-2 It can be seen that the permeable reactive wall 1, the plant remediation zone 2, and the deep purification module 3 are each provided with a sample automatic detection and analysis device 16 for automatic collection, detection, and analysis of multi-layer water quality samples. The sample automatic detection and analysis device mainly collects and analyzes various indexes of the water body through a detector and a sensor, including a conductivity sensor, a dissolved oxygen sensor, a heavy metal sensor, a COD sensor, an NH3-N sensor, a microorganism (BOD) sensor, an organic matter detector, and an A / D converter. The underground water quality detection information is input into a PLC control system through the A / D converter. Maintenance personnel determine the permeable reactive wall filler replacement period according to the water quality monitoring information, and when the filler has been used for a long time and the pollutant removal effect is poor, the filler can be replaced with a new one.

[0066] Further, plant growth-promoting bacteria (PGPB) can be added to the plant remediation zone to enhance the heavy metal resistance of the plants, promote the absorption of heavy metals and nutrient components by the plants, and thus improve the plant remediation efficiency. Domesticated high-efficiency microbial strains can also be put into the plant remediation zone and the deep purification module pool body to degrade organic matter or inorganic matter and deeply purify the water body. The microbial strains include one or more of nitrifying bacteria, denitrifying bacteria, anaerobic dechlorination bacteria, and organic matter degrading bacteria. The addition of the microbial agents is automatically controlled by the PLC system, and the types and time of addition of the microbial agents to the plant remediation zone and the deep purification module are determined according to the water quality monitoring information, so as to realize automatic and intelligent operation. Example 3

[0067] As Fig. 3As shown, the plant repair zone with the anode-cathode electrode pair 22 can also take other arrangements: (a) anode-cathode, the anode-cathode electrode pair is arranged at a distance of 1m from the side of the pool body; (b) anode-cathode-anode, two anode electrodes are arranged on both sides of the pool body, and a cathode electrode is arranged in the middle; (c) cathode-anode-cathode, two cathode electrodes are arranged on both sides of the pool body, and an anode electrode is arranged in the middle or at the bottom. A plurality of electrodes are arranged in the plant repair zone, and each electrode pair is arranged in a row with a distance of less than 30cm between the electrode pairs. The electrodes are rod-shaped electrodes. The redox potential, conductivity and temperature of the environment in the effective range of the electrode pair are measured, a larger sustainable direct current is identified and supplied without affecting the normal operation of the electrode system, and the repair process of the composite pollutants is accelerated.

[0068] In summary, the device and method for simultaneous removal of multiple target pollutants in groundwater can realize efficient and persistent removal of heavy metals, inorganic and organic compounds and other composite pollutants in groundwater through electrodynamic combined physical-chemical-plant repair technology, based on the synergistic effect of adsorption-electrochemistry-plant enrichment-microbial degradation, solve the problem of collaborative management of multiple pollutants, and has the advantages of simple construction, low installation cost, efficient repair, strong applicability, ecological environmental protection and the like. Through the synergistic effect of the permeable reactive wall, electrodynamic combined plant repair and depth purification module, the device and method can realize integrated depth treatment of heavy metals, ammonia nitrogen, inorganic salts, organic matter and other composite pollution in groundwater, and expand the application range of electrodynamic-plant coupled repair technology.

[0069] The electrodynamic-plant coupled repair technology can accelerate the flow speed of groundwater and pollutants. Heavy metals, cations and polar organic pollutants in the soil migrate to the cathode under the action of a direct current electric field, and the pollutants are adsorbed by the matrix, absorbed by the plant and degraded by the microorganism. The addition of plant growth-promoting bacteria and matrix slow-release carbon source can stimulate microbial growth, significantly improve the efficiency of plant repair, and do not produce secondary pollution.

[0070] The depth purification module can continuously degrade residual pollutants through microorganisms, realize efficient and persistent removal of groundwater pollutants, and determine the type, dose and time of microorganism addition according to water quality monitoring information through the PLC control system, realize automatic and intelligent operation, effectively improve the stability and utilization rate of the high-efficiency degradation agent, and solve the problem of low pollutant removal rate.

[0071] The zero-valent iron in the biochar composite filler can reduce heavy metals and pollutants, and the generated Fe2+ can be absorbed by microorganisms and plants as nutrients and strengthen their growth and metabolism, thereby promoting the absorption and degradation of pollutants.

[0072] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the same general inventive concepts embodied by the described embodiments. That is, although the present application is described in terms of particular embodiments and illustrative figures, it should be apparent that the scope of the present application is not limited to these specific embodiments.

[0073] While the embodiments of the application have been shown and described herein, it will be understood by those skilled in the art that many changes, modifications, substitutions and alterations to these embodiments can be made without departing from the principles and spirits of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for synchronously removing multiple target pollutants from groundwater, comprising a permeable reaction wall (1), characterized in that: A first unit (12) is provided on the right side of the permeable reaction wall (1), a permeable grille (11) is provided on the right side of the first unit (12), an automatic sample detection and analysis device (16) is provided above the permeable grille (11), a second unit (13) is provided on the right side of the permeable grille (11), a water-blocking wall (14) and a grille filter (15) are provided on the right side of the second unit (13), the water-blocking wall (14) is located below the grille filter (15), a plant remediation belt (2) is provided on the right side of the grille filter (15), and the plant remediation belt (2) is provided on the right side of the plant remediation belt (16). The bottom of the belt (2) is provided with a pool bottom surface (23), the plant remediation belt (2) is provided with a cathode and anode electrodes (22), the right side of the plant remediation belt (2) is provided with a deep purification module (3), the deep purification module (3) includes a deep purification module pool (21), the right side of the deep purification module pool (21) is provided with a bionic filler (32), the right side of the bionic filler (32) is provided with a water outlet pool (4), the water outlet pool (4) includes a plant remediation belt pool (31), and the bottom of the plant remediation belt pool (31) is provided with a pool bottom (41); The first unit (12) is filled with an adsorption filler, which is one of iron ore, activated zeolite, volcanic rock, ceramsite or a composite filter material, and has a particle size of 2 to 8 mm; the second unit (13) is filled with an active filler, which is a biochar composite filler, and the filler is a spherical porous particle with a particle size of 2 to 4 mm.

2. The device for simultaneous removal of multiple groundwater pollutants according to claim 1, characterized in that: The depth of the permeable reaction wall (1) is greater than the depth of the groundwater pollution plume by 1 m, and the distance between two adjacent walls is 2 to 5 m. A permeable grid (11) is set in the middle of the wall to divide the reaction area into a first unit (12) and a second unit (13). The grid is welded by longitudinal and transverse steel bars into a perforated grid, and the hole spacing is 2 to 5 cm.

3. The device for simultaneous removal of multiple groundwater pollutants according to claim 1, characterized in that: The wall of the first unit (12) is composed of a steel frame and a permeable geotextile. The steel frame is covered with the permeable geotextile. The steel frame is welded vertically and horizontally by multiple stainless steel solid pipes. The pipe diameter is 12~20mm, the frame width is 30~50cm, and the permeability coefficient of the permeable geotextile is greater than 5.0*10-5m / s.

4. The device for simultaneous removal of multiple groundwater pollutants according to claim 1, characterized in that: The wall of the second unit (13) is composed of a watertight partition wall and a grid filter. The top of the partition wall is located in the middle of the wall of the first unit. A grid filter is installed on the top, and the grid hole size is 1 cm to 2 cm.

5. The device for simultaneous removal of multiple groundwater pollutants according to claim 1, characterized in that: The biochar composite filler comprises 40% to 50% bentonite-modified biochar, 20% to 25% zero-valent iron, 10% to 15% clay, 7% to 15% diatomaceous earth, and 3% to 5% ammonium bicarbonate. Clay is used as a bonding raw material, diatomaceous earth is used as a high-permeability raw material, and ammonium bicarbonate is used as a pore-forming agent. The bentonite-modified biochar is prepared by mixing montmorillonite bentonite and biochar and then pyrolyzing them. The particle size of the montmorillonite bentonite is 0.05 to 0.1 mm, the particle size of the biochar is 0.15 to 0.18 mm, the mass ratio of bentonite to biochar is 1:8 to 20, the pyrolysis temperature is 500 to 800°C, and the pyrolysis time is 30 to 60 minutes.

6. The device for simultaneous removal of multiple groundwater pollutants according to claim 1, characterized in that: The bottom surfaces of the plant restoration zone pool (31) and the deep purification module pool (21) are impermeable walls, and the bottom surfaces are flush with the top of the permeable reaction wall watertight wall. The outlet side wall is composed of a steel frame and a permeable geotextile. The plant restoration zone (2) is filled with a matrix in the pool, and the matrix is ​​one of gravel, sand, zeolite, anthracite, bioceramsite, manganese sand, steel slag, waste wood blocks, corn cob particles or a composite filler, and plants are planted on the top of the matrix. The combination ratio of the plant restoration zone matrix needs to be selected according to the polluted water quality and the standard requirements to select the most economical ratio; The particle size of the inorganic fillers such as gravel, sand, zeolite, anthracite, bioceramsite, manganese sand and steel slag is 2-10 mm, and the particle size of the organic fillers such as waste wood blocks and corn cob particles is 3-6 mm.

7. The device for simultaneous removal of multiple pollutants from groundwater according to claim 1, characterized in that: The plant remediation belt (2) is provided with a pair of electric remediation cathode and anode electrodes (22) on both sides of the pool body. A low-voltage DC power supply is provided in the pool body of the plant remediation belt (2). Under the action of the DC electric field, charged heavy metals or polar organic pollutants in the soil move to the electrodes with opposite charges by electric migration, and are adsorbed by the matrix, absorbed by the plants, and decomposed and removed by microorganisms. The cathode electrode and the anode electrode are any one of graphite rod, titanium, stainless steel, conductive metal organic framework material, iron or porous carbon material; The low-voltage DC power supply is a solar photovoltaic device. When a DC voltage is applied to the electrodes, a DC electric field will be formed between the electrodes, and the voltage range for driving electric repair is 0 to 50V.

8. The device for simultaneous removal of multiple groundwater pollutants according to claim 1, characterized in that: The deep purification module pool body (21) is filled with bionic materials as microbial carriers, which are one or both of polypropylene ball fillers and carbon fiber water plants for microbial biofilm formation.

9. The device for simultaneous removal of multiple groundwater pollutants according to claim 1, characterized in that: The bottom of the outlet pool (41) is flush with the bottom of the deep purification module pool. The pool bottom is made of highly permeable material and serves as a drainage layer to allow the purified water to quickly penetrate into the groundwater environment. The outlet side wall is composed of a steel frame and permeable geotextile. The pool size is 0.5~0.8m. The highly permeable material is a composite layer of pebbles and crushed stones, with a particle size of pebbles of 20 to 50 mm, a particle size of crushed stones of 10 to 30 mm, and a thickness of 0.5 to 0.6 m; The plant restoration belt (2) is added with plant growth-promoting bacteria to enhance the metal resistance of the plant, promote the plant's absorption of heavy metals and nutrients, and thus improve the plant restoration efficiency. The plants include wetland plants and heavy metal hyperaccumulator herbs. The wetland plants include one or more of reed, cattail, iris, loosestrife, lily of the valley, canna, and heavy metal hyperaccumulator plants with strong resistance to Cr, Pb, Cu, and Cd heavy metals, including one or more of acanthus, coreopsis, alfalfa, Li's grass, pokeweed, violet, cosmos, ryegrass, and centipede grass.

10. A method for using a device for synchronously removing multiple pollutants from groundwater, characterized by: The device for simultaneously removing multiple target pollutants from groundwater according to claim 1 is specifically operated as follows: A permeable reaction wall, a plant remediation zone, a deep purification module, and a water outlet pool are arranged along the seepage direction of the groundwater pollution plume, and each module is connected in sequence. The permeable reaction wall is filled with adsorption filter material and biochar composite filler; the plant remediation zone is filled with a matrix, plants are planted on the upper part of the matrix, and the matrix is ​​also provided with an electric repair cathode and anode electrode pair. The matrix is ​​one of gravel, sand, zeolite, anthracite, biological ceramsite, manganese sand, steel slag, waste wood blocks, corn cob particles, or a composite filler; the deep purification module is filled with bionic filler, which is a microbial carrier for microbial biofilm formation and is a polypropylene ball filler or carbon fiber water grass; the pollution plume converges into the reaction zone of the permeable reaction wall, the filter material adsorbs heavy metals to remove some pollutants, the activated biochar composite filler adsorbs heavy metals, and zero-valent iron is reduced to remove some organic pollutants. The residual pollutants enter the plant remediation zone, where part of the pollutants are degraded by the microorganisms in the filler matrix, and the other part of the heavy metal pollutants are absorbed and degraded by the plants. After two-stage enhanced treatment, the heavy metal and inorganic salt pollution are completely removed; the upstream water body enters the deep purification module, and the high-efficiency microbial strains form biofilms on the bionic filler. The residual organic matter and ammonia nitrogen inorganic pollutants are continuously degraded by microorganisms, and the effluent is deeply purified to meet the water quality standards.

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