Permeable biological reaction wall device and method for repairing polluted underground water and capable of rapidly forming film

Abstract

The invention discloses a permeable biological reactive barrier (Bio-PRB) system design of a coupled magnetization pretreatment rapid biofilm formation technology. According to the system, a magnetization function microorganism pretreatment method is adopted, meanwhile, magnetic small balls prepared by mixing neodymium iron boron powder, calcium peroxide and concrete are designed to serve as a main body function unit of filler, and the continuous Bio-PRB is formed through laying. A microbial agent with a magnetization function is injected through a microbial agent injection opening formed in the upstream of the Bio-PRB, and rapid and directional movement and enrichment of microorganisms on the surfaces of the magnetic beads are achieved under the action of magnetic attraction force. Then, flowing polluted underground water and target organic pollutants in the polluted underground water are used as a growth carbon source and an energy source of functional microorganisms, the functional microorganisms are promoted to rapidly proliferate and form a film in the Bio-PRB, and a formed biological film has high density and high activity of the functional microorganisms, so that rapid start of the Bio-PRB is realized; the long-term efficient degradation of target pollutants in underground water is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of groundwater pollution remediation, and particularly to a permeable biological reaction wall device and method for rapidly forming a biofilm for remediating polluted groundwater, and a permeable biological reaction wall technology for rapidly forming a biofilm by fixing microorganisms with magnetic suction force. Background Art

[0002] The permeable reactive barrier (PRB) technology is an in-situ groundwater remediation technology, which refers to a passive reaction system filled with an active reaction medium material in the vertical direction downstream of the groundwater pollution plume. When the polluted groundwater flows through the filled medium, a series of reactions such as precipitation, adsorption, catalytic oxidation-reduction, and biodegradation will occur, so as to achieve the purpose of blocking, removing pollutants, and controlling the diffusion of pollutants. Compared with the groundwater ex-situ treatment technology that uses pumps to pump the polluted groundwater to the ground and build ground treatment facilities and other high-energy-consuming measures, PRB is a technology that does not require an external power source and can save floor space, and has the advantages of small engineering measures and disturbance, low investment, and long-term treatment and control of pollutants. These advantages make this technology have a wide application prospect in the field of polluted groundwater treatment. However, due to the problems of adsorption saturation, inactivation, and blockage of the active medium of PRB, it is impossible to ensure the continuous and efficient remediation ability of PBR, and there are also problems such as high treatment cost and easy generation of secondary pollution. Therefore, it is urgent to develop a new type of PRB technology that is green, low-carbon, and sustainable.

[0003] The biological permeable reactive barrier (Bio-PRB) activates indigenous microorganisms or inoculates dominant degrading bacteria of target pollutants in the reaction zone by setting up an electron acceptor and a nutrient supply system to form a biologically active reaction wall to enrich and purify the polluted groundwater flowing through. Compared with the traditional PRB technology, Bio-PRB does not rely on the activation reaction of the filler medium, so it has the characteristics of environmental protection, low cost, long-term effectiveness, and strong operability in engineering applications. Therefore, it has a wide application prospect in in-situ groundwater remediation projects.

[0004] At present, the fillers for Bio-PRB have a rich selection, but for the problems of low microbial enrichment efficiency and long biofilm formation period in the actual application of the traditional permeable biological reaction wall (Bio-PRB) technology, the prior art has not proposed an effective solution.

[0005] Therefore, it is urgent to develop a new type of Bio-PRB pretreatment method to solve the problems of low microbial enrichment efficiency, long biofilm formation period, and easy blockage of the wall to increase its long-term effectiveness. Summary of the Invention

[0006] To address the above technical deficiencies, the present invention provides a design of a Biological Permeable Reactive Barrier (Bio-PRB) system for the treatment of contaminated groundwater, which couples a magnetization pretreatment and a rapid biofilm formation technology.

[0007] To achieve the above object, the solution of the present invention is as follows: A permeable biological reaction wall device for the rapid biofilm formation and the remediation of contaminated groundwater, the device comprising: a reaction wall water inlet area (1), which is filled with quartz sand filler and located at the forefront of the device for intercepting flocculent substances; followed by a biological reaction area (2) after the water inlet area (1), which is jointly composed of magnetic bead fillers and magnetized functional microorganisms; a preset well bacterial liquid injection port (3) is arranged at the upstream position on the top of the biological reaction area; a permeable biological reaction wall water outlet area (6) is arranged after the biological reaction area (2), which is filled with quartz sand filler for uniform water outlet; pressure detection areas (5) are respectively arranged upstream and downstream of the biological reaction area (2); and groundwater monitoring ports (3) are respectively arranged on the upper parts of the reaction wall water inlet area (1), the biological reaction area (2) and the reaction wall water outlet area (6).

[0008] A method for a permeable biological reaction wall for the rapid biofilm formation and the remediation of contaminated groundwater, the method can achieve the rapid biofilm formation of microorganisms and the efficient degradation of target pollutants in a relatively short time, and is applicable to various types of groundwater pollution remediation scenarios, and its steps include:

[0009] Step 1: Construct a biological reaction area and optimize the characteristics of the filler;

[0010] Step 2: Regulate the water chemical environment to promote the growth of microorganisms;

[0011] Step 3: Add magnetized functional microorganisms and achieve rapid biofilm formation;

[0012] Step 4: Maintain the microbial activity and monitor the operation status of the system.

[0013] Among them, Step 1 is specifically as follows:

[0014] Magnetic small ball fillers are arranged in the core biological reaction zone of the permeable biological reaction wall. Measured by a fluxmeter, this area has strong magnetism and will not experience magnetic attenuation when immersed in water for a long time. The small balls are prepared using magnetized concrete structural units. By mixing neodymium iron boron powder, curing agent, reactive diluent, and coupling agent in a ratio of 10:1:0.5:0.1 to prepare magnetic aggregates, ensuring that the neodymium iron boron powder can be evenly dispersed and reducing agglomeration. Then, the magnetic aggregates are mixed with silica sand, calcium peroxide, and cement in a ratio of 2:1:0.5:1 with an appropriate amount of water, and a high-speed rotary granulator or spray granulation equipment is used to make the mixture into spherical particles with a particle size of about 2 - 5 mm. The granulated magnetic small balls are placed in an environment of 40 - 60 °C and left to stand for 12 - 24 h for preliminary curing. Then, high-temperature curing (100 - 150 °C) treatment is carried out to improve the compressive strength and water resistance stability of the small balls. Finally, magnetization is carried out under a strong magnetic field (>2 T) to ensure that the remanent magnetic strength of the magnetic small balls meets the usage requirements. Compared with traditional concrete fillers or ordinary magnetic fillers, it has more superior microbial enrichment ability and mechanical durability and is suitable for long-term groundwater remediation projects. Among them, step 2 is specifically as follows: Calcium peroxide (CaO2) is pre-incorporated into the magnetic small balls, and after being arranged, it will react with groundwater to generate oxygen (O2) and calcium hydroxide (Ca(OH)2). Among them, oxygen can improve the microbial degradation efficiency, and calcium hydroxide can + undergo a neutralization reaction with H+ in the groundwater, reducing the acidity of the water body and making the pH value tend to be neutral, thereby constructing a more suitable environment for microbial growth.

[0015] Among them, step 3 is specifically as follows: Through the bacterial liquid injection port set upstream of the top of the biological reaction zone, magnetized functional microorganisms are regularly injected into the biological reaction zone. Relying on the strong magnetic field effect of the magnetic small balls themselves, the magnetized functional microorganisms are quickly adsorbed on the surface of the small balls and move and colonize directionally and expand to form a stable and efficient biofilm, ensuring that the system has long-term and efficient degradation ability.

[0016] Among them, step 4 is specifically as follows: In order to ensure that the number of microorganisms in the permeable biological reaction wall is maintained above 10 8 cells / mL, it is necessary to regularly supplement magnetized functional microorganisms through the bacterial liquid injection port to maintain the biodegradation activity of the system. At the same time, a fluxmeter is configured in the biological reaction zone to monitor the magnetic change of the filler in real time to ensure that its magnetic adsorption performance and microbial enrichment effect are always in an effective state during long-term operation.

[0017] The preparation technology of magnetic microspheres is as follows: Mix neodymium iron boron powder, curing agent, reactive diluent and coupling agent in a ratio of 10:1:0.5:0.1 to prepare magnetic aggregates, ensuring that the neodymium iron boron powder can be evenly dispersed and reducing the agglomeration phenomenon. Then mix the magnetic aggregates with silica sand, calcium peroxide, and cement in a ratio of 2:1:0.5:1 and mix with an appropriate amount of water. Use a high-speed rotating granulator or spray granulation equipment to make the mixture into spherical particles with a diameter of about 2-5 mm. Place the granulated magnetic microspheres in an environment of 40-60 °C and let them stand for 12-24 h to make them initially cured; then perform high-temperature curing (100-150 °C) treatment to improve the compressive strength and water resistance stability of the microspheres; finally, magnetize them under a strong magnetic field (>2 T) to ensure that the remanence intensity of the magnetic microspheres meets the usage requirements.

[0018] The prefabrication process of magnetized functional microorganisms is as follows: Heat and dissolve the special medium of magnetotactic bacteria in 100 mL of distilled water (1:100), add 0.02 mmol / L of ferric quinate, adjust the pH to 6.7, and the bottling volume is 75%. Sterilize at 116 °C under high pressure for 20 min. Then add the magnetotactic bacteria purchased from the ATCC bacterial library to the medium and culture it at 25 °C in a microaerobic environment; at this time, the OD 600 value of the magnetotactic bacteria reaches above 0.4.

[0019] Preferably, first mix the magnetotactic bacteria with lysozyme (3%) to act, and the magnetosomes are released into the culture environment as the bacterial cells are broken. Then use polyethylene glycol (PEG1200) to fuse the magnetosomes with the functional microorganisms that can degrade specific pollutants. At this time, the magnetosomes and the functional microorganisms are effectively combined to complete the magnetization process of the functional microorganisms.

[0020] Preferably, after the magnetotactic bacteria are acted on by lysozyme to release protoplasts and magnetosomes, the culture solution containing magnetosomes needs to be passed through a pipeline filled with 724 weakly acidic cation exchange resin to adsorb and extract lysozyme. The pipeline is equipped with a valve to control the inflow of the bacterial solution, and at the same time, the pH of the solution flowing out of the pipeline is monitored and adjusted.

[0021] The uniform water inlet area and water outlet area are composed of coarse sand and fine sand, so that the contaminated groundwater flows through the coarse sand and fine sand in turn under the action of the hydraulic gradient and then flows through the bioreaction area at a uniform flow rate. Moreover, the coarse sand and fine sand can filter the muddy water flocs in the groundwater and play a role in protecting the reaction wall.

[0022] The injection bacterial solution port is installed by the vertical hydraulic fracturing technology controlled by the azimuth angle and is distributed at the front end of the Bio-PRB. The bacterial solution can be periodically added from the injection port to maintain the required amount of microorganisms in the groundwater environment.

[0023] Preferably, magnetic microspheres of uniform size are made of materials such as neodymium iron boron powder. Increasing their specific surface area can provide more attachment points for magnetized functional microorganisms. The microspheres are found to have strong magnetism by a fluxmeter. After placing them at intervals in the uniform water inlet area, the water flow can contact the surface of the microspheres and slowly release oxygen.

[0024] The biological reaction zone is composed of magnetic microspheres of uniform size made of materials such as neodymium iron boron powder arranged in sequence. Magnetized functional microorganisms are injected at the inoculation port to make them fully contact with the magnetic microspheres. The magnetic microspheres achieve rapid adsorption of microorganisms through the magnetic attraction force on the magnetized functional microorganisms.

[0025] When the contaminated groundwater flows through the biological reaction zone under its own hydraulic gradient, the magnetized functional microorganisms consume the pollutants in the water as nutrients to maintain their own growth and reproduction. During this process, the pollutants are degraded or transformed, realizing the treatment of contaminated groundwater and reducing the harm of pollutants to the environment.

[0026] Preferably, the fluxmeter is located above the magnetic microspheres, and the fixation effect of the magnetic microspheres on the magnetized functional microorganisms is ensured by long-term monitoring of the magnetic change of the magnetic microspheres.

[0027] The pressure gauges are located at the front and end of the entire reaction wall and are connected to the groundwater source through pipelines. The change in the permeability coefficient in the Bio-PRB is characterized by monitoring the pressure readings when flowing into the Bio-PRB and when flowing out of the Bio-PRB.

[0028] This process realizes the rapid adsorption of functional microorganisms in the permeable reactive wall, and at the same time provides a suitable growth environment for aerobic microorganisms in the groundwater.

[0029] The permeable biological reaction wall technology of the present invention effectively integrates functional microorganisms and magnetotactic bacteria. The magnetic microspheres achieve rapid adsorption of functional microorganisms through magnetic attraction force for the remediation of organically contaminated groundwater. It can not only play the role of functional microorganisms in remediating contaminated groundwater, but also greatly reduce the adsorption time of microorganisms on the packing, improving the efficiency of the permeable biological reaction wall technology in groundwater pollution remediation.

[0030] The beneficial effects of the present invention are:

[0031] 1. Coupling magnetization pretreatment and rapid biofilm formation technology. Through magnetic attraction, the pre-magnetized functional microorganisms can quickly move directionally and adsorb on the surface of the microspheres, thus shortening the biofilm formation time of microorganisms and significantly improving the reaction speed.

[0032] 2. After mixing magnetic aggregates with silica sand, calcium peroxide, and cement, magnetic spheres with a particle size of 2 - 5 mm are formed through high-speed rotational granulation or spray granulation. After pre-curing and high-temperature curing treatments, these spheres not only have high compressive strength but also do not experience magnetic attenuation or structural damage when soaked in water for a long time. Compared with traditional concrete fillers, their mechanical properties are more stable and their service life is longer.

[0033] 3. In the Bio-PRB system, a uniform water inlet area, a bacteria solution injection port, a biological reaction area, a fluxmeter, a pressure detection point, and a uniform water outlet area are arranged in sequence along the groundwater flow direction. The fluxmeter can monitor the magnetic changes of the magnetic spheres in real time to ensure the stability of their adsorption effect on magnetized functional microorganisms; while the pressure detection system monitors the water flow state and timely reflects the change of the permeability coefficient, which is beneficial to the dynamic regulation of the project operation. Brief Description of the Drawings

[0034] Figure 1 is a schematic structural diagram of the present invention;

[0035] Figure 2 is a schematic diagram of the magnetized functional microorganism process of the present invention;

[0036] Figure 3 is a distribution diagram of the engineering application of the wall, monitoring port, and bacteria agent recharge port of the present invention;

[0037] Figure 4 is a diagram of the magnetized spheres of the present invention;

[0038] In the figure: 1-1, 1-2, coarse sand; 2-1, 2-2, fine sand; 3, bacteria agent injection port; 4, magnetic spheres; 5, magnetotactic bacteria; 6, magnetosomes; 7, lysozyme; 8, magnetotactic bacteria protoplasts; 9, functional microorganisms; 10, polyethylene glycol; 11, magnetized functional microorganisms; 12, groundwater sampling and monitoring port; 13, bacteria agent recharge port; 14, biological permeable reaction wall; 15, groundwater flow direction; 16, pressure sensor; 17. neodymium iron boron powder; 18. concrete particles. Detailed Embodiments

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention.

[0040] Embodiment 1

[0041] As Figure 1, this embodiment provides a permeable biological reaction wall system for treating polluted groundwater by coupling magnetization pretreatment and rapid biofilm formation technology, which includes six parts: magnetic microsphere preparation technology, magnetization functional microorganism prefabrication, the influent area 1-1, 2-1 of the permeable biological reaction wall, the biological reaction area 3, the groundwater monitoring port 12, the bacterial liquid injection port 13, and the effluent area 1-2, 2-2 of the permeable biological reaction wall.

[0042] The biological reaction area is composed of Figure 4 the magnetic microspheres arranged as shown. The microspheres are prepared by mixing neodymium iron boron powder, curing agent, reactive diluent, and coupling agent in proportion to form magnetic aggregates, and then mixing the magnetic aggregates with sand, calcium peroxide, cement, and water, and making them through stirring and granulation mechanism; detected by a fluxmeter, the microspheres have good magnetism and can continuously release oxygen in water to maintain aerobic conditions in groundwater.

[0043] The magnetization functional microorganism prefabrication process is as Figure 2 shown. The magnetobacterium 5 is mixed with lysozyme 7 to break the magnetobacterium and release protoplasts 8 and magnetosomes 6; the functional microorganisms 9 that can degrade this pollutant screened according to specific pollutants are mixed with magnetosomes 6 under the action of polyethylene glycol 10 to effectively combine the functional microorganisms with the magnetosomes, and the morphology of the magnetization functional microorganisms 11 is observed under a transmission electron microscope.

[0044] Preferably, magnetic microspheres made of magnetic materials and calcium peroxide materials have a specific surface area of 203.1 m 2 / g measured by BET, which can provide more attachment points for magnetization functional microorganisms. Through the oxygen release experiment in water, it is determined that the microspheres have long-term oxygen release ability. After placing them at intervals in the uniform influent area, the water flow contacts the microspheres to provide a micro-oxygen environment and at the same time block soil particles from entering the biological reaction area.

[0045] After the magnetization functional microorganisms are poured from the injection port upstream of the biological reaction area, they are quickly and directionally adsorbed onto the surface of the microspheres under the magnetic suction of the magnetic microspheres. At this time, the magnetic microspheres are microscopically characterized, and it is observed that arc-shaped bacteria bodies are attached to the surface of the microspheres in a large area, indicating that the biological adsorption is completed.

[0046] When the polluted groundwater flows through the biological reaction area under its own hydraulic gradient, the magnetization functional microorganisms consume the pollutants in the water as nutrients to maintain their own growth and reproduction. During this process, the pollutants are degraded or transformed, realizing the treatment of polluted groundwater and reducing the harm of pollutants to the environment.

[0047] Example 2

[0048] In a chemical industrial decommissioned site, it is detected that due to the long-term illegal discharge of chlorine-containing pollutants by the chemical plant, the chlorinated hydrocarbon pollution in the groundwater exceeds the standard. A permeable biological reaction wall technology for treating organically polluted groundwater and coupling magnetization pretreatment and rapid biofilm formation technology is provided in this embodiment for the problems of excessive pollutants such as 1,2-dichloromethane, carbon tetrachloride, and chlorobenzene in the groundwater of this site.

[0049] As Figure 2 shown, the contaminated soil and groundwater of this site are taken for microbial domestication to obtain functional microorganisms 9 that can efficiently degrade chlorinated hydrocarbons in this water body; magnetotactic bacteria 5 and lysozyme 7 are mixed and fused, causing the magnetotactic bacteria to rupture and release protoplasts 8 and magnetosomes 6; the screened functional microorganisms 9 that can degrade chlorinated hydrocarbons are mixed and fused with magnetosomes 6 under the action of polyethylene glycol 10, enabling the effective combination of the functional microorganisms and the magnetosomes and completing the magnetization process of the functional microorganisms.

[0050] Furthermore, magnetic balls made of materials such as neodymium iron boron powder, calcium peroxide, cement, and water are as Figure 4 shown. This accessory has the advantages of the neodymium iron boron powder being not easily demagnetized and corroded, having a simple production process and a low price. This accessory uses the mechanism of calcium peroxide reacting with water to release oxygen to provide oxygen for aerobic microorganisms, and neutralizes the acidic components in the groundwater through calcium hydroxide substances to provide suitable conditions for the growth of microorganisms, and realizes the rapid adsorption process of microorganisms for the magnetized functional microorganisms 11 under the action of magnetic attraction.

[0051] Furthermore, the soil and water characteristics of the polluted site are surveyed, and it is found that the groundwater level of this site is 1.5 m below the ground surface, and the soil structure consists of an artificial filling layer, a sandy soil layer, a silty clay layer, and a clay layer. A deep trench with a length of 4 m, a depth of 5.5 m, and a width of 3 m is dug using a deep trench excavation device. In the first 0.5 m of the deep trench, the reaction wall inlet area is paved with coarse sand and fine sand to equalize the inflow water flow velocity and intercept the muddy water flocs in the groundwater, reducing the occurrence of physical-biological blockage caused by the interception of muddy water flocs and enhancing the long-term effectiveness of the permeable reaction wall.

[0052] Furthermore, the magnetic balls are arranged after the reaction wall inlet area, fixed at the bottom with concrete, and supported and protected at the top with non-magnetic materials to form a biological reaction area with good magnetism, and the top is covered with artificial materials.

[0053] Furthermore, a 0.5 m long reaction wall outlet area is paved with coarse sand and fine sand after the biological reaction area to correspond to the flow velocity of the reaction wall inlet area, control the water velocity of the water flowing out of the reaction wall to be the same as that of the inflowing water, and it is observed through the pressure sensors arranged before and after the permeable reaction wall that the flow velocity of the polluted groundwater in the permeable reaction wall body is uniform and stable.

[0054] Furthermore, the prepared magnetized functional microorganism bacterial liquid (109 cells / mL) was poured from the bacterial agent injection port at one time, and water samples were taken from the groundwater sampling monitoring port for microbial counting observation. It was observed that the amount of microorganisms in the groundwater flowing out of the reaction wall was far less than 10 9 cells / mL, so it can be considered that the magnetized functional microorganisms have been adsorbed to the surface of the magnetic beads in large quantities.

[0055] Furthermore, the functional microorganism magnetization process was carried out every 5 days. The magnetized functional microorganisms were replenished from the bacterial agent replenishment port, and a DX-201 fluxmeter was installed on the top of the magnetic ball area to measure the magnetic flux changes in the biological reaction area. During the process, the fluxmeter was observed to fluctuate slightly around 2500GS, and the flux count value did not change significantly, indicating that the magnetic properties of the material in the biological reaction area were stable.

[0056] Furthermore, when the contaminated groundwater flows through the biological reaction zone, the pollutants in the groundwater come into contact with the magnetized functional microorganisms adsorbed on the magnetic balls. The magnetized functional microorganisms use pollutants such as 1,2-dichloromethane, carbon tetrachloride, and chlorobenzene as carbon sources for their own growth and metabolism. In the process, the chlorinated hydrocarbon pollutants are dechlorinated and degraded, which greatly reduces the content of pollutants in the groundwater flowing out of the biological reaction zone. After testing, the water quality meets the Class IV water standard in the "Groundwater Quality Standard" (GB / T 14848-2017).

[0057] Furthermore, in this example, the permeable biological reaction wall maintained good biosorption performance after 100 days of continuous operation during the risk control management of the contaminated site. No blockage of the wall was observed through the pressure sensor. The wall maintained a degradation rate of chlorinated hydrocarbons in contaminated groundwater at 90%, indicating that the system has long-term effectiveness in engineering applications.

[0058] Example 3

[0059] Petroleum hydrocarbons (C 10 -C 40 ) pollution exceeds the standard. To address the problem of excessive petroleum hydrocarbons in the area, this embodiment provides a permeable biological reaction wall technology that combines a coupled magnetic pretreatment and rapid biological film formation technology for removing petroleum hydrocarbon pollution in groundwater.

[0060] like Figure 3 As shown, soil and groundwater contaminated by petroleum hydrocarbons at the site are used for microbial acclimation to obtain functional microorganisms 9 that can efficiently degrade petroleum hydrocarbons in the water body; magnetic bacteria 5 are mixed with lysozyme 7 to dissolve the cell walls of the magnetic bacteria, releasing protoplasts 8 and magnetosomes 6; the screened functional microorganisms 9 that can degrade chlorinated hydrocarbons are mixed with the magnetosomes 6 under the action of polyethylene glycol 10, so that the functional microorganisms and the magnetosomes are effectively combined, completing the magnetization process of the functional microorganisms.

[0061] Further, magnetic balls made of materials such as NdFeB powder, calcium peroxide, cement and water are Figure 4 The accessory has the advantages of NdFeB powder not being easy to demagnetize and corrode, simple production process and low price. The accessory uses magnetic attraction to quickly adsorb magnetized functional microorganisms 11 to start the biofilm formation process.

[0062] Further hydrogeological surveys of the contaminated site revealed a groundwater level approximately 6.5 meters below the surface. The geological structure consists of a shallow sandy aquifer (0-3 meters), a middle clay-sand aquifer (3-8 meters), and a deep sandy aquifer (8-20 meters). A 9-meter-long, 14-meter-deep, and 1.8-2.4-meter-wide permeable bioreaction wall system was installed using azimuthally controlled vertical hydraulic fracturing technology. The first 2 meters of the wall were paved with coarse and fine sand to create a uniform influent flow rate and retain groundwater flocs. This reduced the risk of physical and biological clogging caused by these flocs and enhanced the long-term effectiveness of the permeable reaction wall.

[0063] Furthermore, magnetic balls are placed in a removable mesh frame after the water inlet area of the reaction wall, and the bottom is fixed with sand to form a mesh frame with good magnetic properties. The top is covered with artificial materials. The mesh frame can be extracted and replaced according to the degradation of organic matter. By measuring the DO of the effluent, it was found that the DO of the effluent in this area is >2mg / L, which is suitable for the growth of aerobic microorganisms.

[0064] Furthermore, the reaction wall outlet area paved with coarse sand and fine sand 2m behind the mesh frame is used to correspond to the flow rate of the reaction wall inlet area, controlling the water flow rate of the outflowing water in the reaction wall to be consistent with the water flow rate of the inflowing water. The pressure sensors arranged before and after the infiltration reaction wall are used to observe that the flow rate of the contaminated groundwater in the infiltration reaction wall is uniform and stable.

[0065] Furthermore, considering the deep groundwater depth, the prepared magnetic functional microbial liquid (10 9 The bacteria solution was injected from the inlet through high-pressure rotary spraying technology, so that the bacteria solution could penetrate deeper into the wall. Water samples were taken from the groundwater sampling monitoring port for microbial counting observation. It was observed that the amount of microorganisms in the groundwater flowing out of the reaction wall was far less than 10 9 cells / mL, so it can be considered that the magnetized functional microorganisms have been adsorbed to the surface of the magnetized beads in large quantities.

[0066] Furthermore, the functional microorganism magnetization process was carried out every 5 days. The magnetized functional microorganisms were replenished from the bacterial agent filling port, and a TD-8900 fluxmeter was installed on the top of the bioreaction area to measure the magnetic flux changes in the bioreaction area. During the process, the fluxmeter was observed to fluctuate slightly around 3100GS, and the flux count value did not change significantly, indicating that the magnetic properties of the material in the bioreaction area were stable.

[0067] Furthermore, the contaminated groundwater flows through the bioreaction zone, where the pollutants in the groundwater come into contact with the magnetized functional microorganisms adsorbed on the magnetic microspheres. The magnetized functional microorganisms use the petroleum hydrocarbon pollutants as a carbon source for their own growth and metabolism, and degrade the chlorinated hydrocarbon pollutants during this process, significantly reducing the content of pollutants in the groundwater flowing out of the bioreaction zone. After detection, the water quality meets the standard of Class IV water in the "Groundwater Quality Standard" (GB / T 14848-2017).

[0068] Furthermore, in this example, the permeable bioreaction wall of the present invention continued to operate for 260 days during the risk control of the petroleum hydrocarbon contaminated site in this industrial area and still maintained good biodegradation performance. No blockage phenomenon of the wall was observed through the pressure sensor, and the concentration of petroleum hydrocarbons in the groundwater decreased from the initial 51.3 ± 2.31 mg / L to 2.37 ± 1.22 mg / L, indicating that the present invention has achieved the long-term effectiveness of bioremediation of petroleum hydrocarbon contaminated groundwater.

[0069] The specific embodiments shown above have elaborated in detail on how the present invention solves the problems existing in the above-mentioned prior art, the proposed solutions and the implementation effects. The above are only specific embodiments of the present invention, and it should be understood that any modifications, equivalent replacements and improvements made substantially according to the spirit of the invention should be included within the protection scope of the present invention.

Claims

1. A permeable bioreaction wall device for repairing contaminated groundwater that can quickly form a biofilm, the device comprising: The reaction wall water inlet area (1) is formed by filling quartz sand fillers at the very front end of the device for intercepting flocculent substances; following the water inlet area (1) is the biological reaction area (2), which is jointly composed of magnetic ball fillers and magnetized functional microorganisms; a preset well bacterial liquid injection port (3) is set at the upstream position on the top of the biological reaction area; after the biological reaction area (2), a permeable biological reaction wall water outlet area (6) is set, which is formed by filling quartz sand fillers for uniform water outlet; pressure detection areas (5) are respectively arranged upstream and downstream of the biological reaction area (2); groundwater monitoring ports (3) are respectively arranged on the upper parts of the reaction wall water inlet area (1), the biological reaction area (2) and the reaction wall water outlet area (6).

2. A method of a permeable bioreaction wall capable of quickly forming a biofilm for repairing contaminated groundwater, characterized in that, The method can achieve rapid biofilm formation of microorganisms and efficient degradation of target pollutants in a short time, and is applicable to various types of groundwater pollution remediation scenarios. Its steps include: Step 1: Construct a biological reaction area and optimize the characteristics of the fillers; Step 2: Regulate the water chemical environment to promote the growth of microorganisms; Step 3: Add magnetized functional microorganisms and achieve rapid biofilm formation; Step 4: Maintain the activity of microorganisms and monitor the operation status of the system.

3. According to the permeable biological wall reaction method for rapid biofilm formation for repairing polluted groundwater as described in claim 2, step 1 is specifically as follows: Magnetic ball fillers are arranged in the core biological reaction area of the permeable biological reaction wall. Measured by a fluxmeter, this area has strong magnetism and will not undergo magnetic attenuation after being soaked in water for a long time. The balls are prepared using magnetized concrete structural units. By mixing neodymium iron boron powder, curing agent, reactive diluent and coupling agent in a ratio of 10:1:0.5:0.1 to prepare magnetic aggregates, ensuring that the neodymium iron boron powder can be evenly dispersed and reducing the agglomeration phenomenon. Then, the magnetic aggregates are mixed with silica sand, calcium peroxide, cement in a ratio of 2:1:0.5:1 and an appropriate amount of water, and a high-speed rotating granulator or spray granulation equipment is used to make the mixture into spherical particles with a particle size of about 2 - 5 mm. The granulated magnetic balls are placed in an environment of 40 - 60 °C and left standing for 12 - 24 h for preliminary curing; then high-temperature curing (100 - 150 °C) treatment is adopted to improve the compressive strength and water resistance stability of the balls; finally, magnetization is carried out under a strong magnetic field (>2T) to ensure that the remanent magnetic strength of the magnetic balls meets the usage requirements.

4. According to the permeable biological reaction wall method for rapid biofilm formation for repairing polluted groundwater as described in claim 2, step 2 is specifically as follows: Calcium peroxide (CaO2) is pre-incorporated into the magnetic balls, and after being arranged, it will react with groundwater to generate oxygen (O2) and calcium hydroxide (Ca(OH)2).

5. According to the permeable biological reaction wall method for rapid biofilm formation for repairing polluted groundwater as described in claim 2, step 3 is specifically as follows: Through the bacterial liquid injection port set at the upstream of the top of the biological reaction area, magnetized functional microorganisms are regularly injected into the biological reaction area.

6. The method of the permeable bioreaction wall capable of quickly forming a biofilm for repairing contaminated groundwater according to claim 2, and step 4 is specifically as follows: In order to ensure that the number of microorganisms in the permeable bioreaction wall is maintained above 10 8 cells / mL, it is necessary to regularly supplement magnetized functional microorganisms through the bacterial liquid injection port to maintain the biodegradation activity of the system.

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