Rapidly biofilmable permeable wall apparatus and method for remediating contaminated groundwater

Abstract

The application discloses a Bio-PRB system design of coupling magnetization pretreatment and fast biofilm forming technology. The system adopts a magnetization functional microorganism pretreatment method, and a main functional unit of a magnetic ball made of neodymium iron boron powder, calcium peroxide and concrete is designed as a filler to form a continuous Bio-PRB. The magnetization functional microorganism agent is injected through a bacteria injection port arranged at an upstream of the Bio-PRB, and the magnetic attraction force is used to realize the fast and directional movement and enrichment of the microorganism on the surface of the magnetic ball. Then, the contaminated groundwater and the target organic pollutants in the contaminated groundwater are used as the growth carbon source and energy source of the functional microorganism to promote the fast proliferation of the functional microorganism in the Bio-PRB to form a biofilm, the biofilm has high density and high activity of the functional microorganism, and therefore, the fast start of the Bio-PRB is realized, and the long-term and high-efficiency degradation of the target pollutants in the groundwater is realized.

Description

Technical Field

[0001] This invention relates to the field of groundwater pollution remediation technology, and in particular to a permeable bioreactor device and method for remediating polluted groundwater, which enables rapid biofilm formation by magnetically immobilizing microorganisms to achieve rapid biofilm formation. Background Technology

[0002] Permeable reactive barrier (PRB) technology is an in-situ groundwater remediation technology. It involves placing a passive reaction system filled with an active reactive medium vertically downstream of a groundwater plume. When contaminated groundwater flows through this medium, a series of reactions occur, including sedimentation, adsorption, catalytic oxidation-reduction, and biodegradation, thereby achieving the goal of blocking, removing, and controlling the spread of contaminants. Compared to ex-situ groundwater treatment technologies that use pumps to extract contaminated groundwater to the surface and construct surface treatment facilities—all high-energy-consuming measures—PRB is a technology that requires no external power source and saves land area. It offers advantages such as minimal engineering intervention and disturbance, lower investment, and long-term control of contaminants, making it a promising technology for groundwater remediation. However, the active medium in PRB is prone to adsorption saturation, deactivation, and blockage, which cannot guarantee the continuous and efficient remediation capacity of PRB. Furthermore, it suffers from high treatment costs and the potential for secondary pollution. Therefore, there is an urgent need to develop a new, green, low-carbon, and sustainable PRB technology.

[0003] Bio-permeable reactive barriers (Bio-PRBs) utilize electron acceptors and nutrient supply systems to activate indigenous microorganisms or inoculate the reaction zone with dominant degrading bacteria targeting the pollutants, forming a bioactive reactive barrier to enrich and purify flowing contaminated groundwater. Compared to traditional PRB technologies, Bio-PRBs do not rely on the activation reaction of the packing medium, thus offering advantages such as being environmentally friendly, low-cost, long-lasting, and highly operable in engineering applications. Therefore, they have broad application prospects in in-situ groundwater remediation projects.

[0004] Currently, there is a wide selection of packing materials for Bio-PRB, but existing technologies have not yet proposed effective solutions to the problems of low microbial enrichment efficiency and long biofilm formation period in the practical application of traditional permeable bioreactor (Bio-PRB) technology.

[0005] Therefore, there is an urgent need to develop a novel Bio-PRB pretreatment method to address the problems of low microbial enrichment efficiency, long biofilm formation period, and easy clogging of the wall, so as to increase its long-term effectiveness. Summary of the Invention

[0006] To address the aforementioned technical deficiencies, this invention provides a design for a bio-permeable reactive barrier (Bio-PRB) system using coupled magnetization pretreatment and rapid biofilm formation technology for the treatment of contaminated groundwater.

[0007] To achieve the above objectives, the present invention provides the following solution: a permeable bioreactor device for rapidly attaching biofilms for remediating contaminated groundwater, comprising: a bioreactor inlet zone, located at the front end of the device and filled with quartz sand to intercept flocculent material; a bioreactor zone following the inlet zone, composed of magnetic microspheres and magnetized microorganisms; a pre-set well-bacterial agent injection port located upstream of the top of the bioreactor zone; a permeable bioreactor outlet zone following the bioreactor zone, filled with quartz sand for uniform water discharge; pressure detection zones located upstream and downstream of the bioreactor zone; and groundwater monitoring ports located at the upper parts of the bioreactor inlet zone, the bioreactor zone, and the bioreactor outlet zone.

[0008] A permeable bioreactor method for rapidly attaching microorganisms to remediate contaminated groundwater. This method enables rapid microbial attachment and efficient degradation of target pollutants within a short time, and is applicable to various types of groundwater pollution remediation scenarios. The steps include:

[0009] Step 1: Construct the bioreactor zone and optimize the packing material properties;

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

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

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

[0013] Step 1 is as follows:

[0014] Magnetic microspheres were placed in the core bioreactor zone of the permeable bioreactor wall. Flux meter measurements showed that this area exhibited strong magnetism and did not decay magnetically even after prolonged immersion in water. These microspheres were prepared using magnetized concrete structural units. A magnetic aggregate was prepared by mixing NdFeB powder, curing agent, reactive diluent, and coupling agent in a 10:1:0.5:0.1 ratio to ensure uniform dispersion of the NdFeB powder and reduce agglomeration. The magnetic aggregate was then mixed with silica sand, calcium peroxide, and cement in a 2:1:0.5:1 ratio with an appropriate amount of water. A high-speed rotary granulator or spray granulation equipment was used to form spherical particles with a diameter of approximately 2-5 mm. The granulated magnetic microspheres were then placed in a 40-60 °C environment and allowed to stand for 12-24 hours for initial curing; subsequently, high-temperature curing (100-150 °C) was employed. The microspheres are treated at °C to improve their compressive strength and water resistance; finally, they are magnetized under a strong magnetic field (>2T) to ensure that the remanent magnetization of the magnetic microspheres meets the requirements for use. Compared with traditional concrete fillers or ordinary magnetic fillers, they have superior microbial enrichment capacity and mechanical durability, making them suitable for long-term groundwater remediation projects.

[0015] Step 2 is as follows: Calcium peroxide (CaO2) is pre-doped into the magnetic spheres. After deployment, these spheres react with groundwater to generate oxygen (O2) and calcium hydroxide (Ca(OH)2). Oxygen enhances the efficiency of microbial degradation, while calcium hydroxide reacts with H+ in the groundwater. + A neutralization reaction occurs, reducing the acidity of the water and making the pH value more neutral, thereby creating a more suitable environment for microbial growth.

[0016] Step 3 is as follows: Magnetized functional microorganisms are periodically injected into the bioreactor zone through the microbial agent injection port located at the top upstream of the bioreactor zone. Relying on the strong magnetic field of the magnetic spheres themselves, the magnetized functional microorganisms are rapidly adsorbed onto the surface of the spheres and move and colonize in a directional manner to form a stable and efficient biofilm, ensuring that the system has a long-term and efficient degradation capability.

[0017] Step 4 is as follows: To ensure that the number of microorganisms in the permeable bioreactor wall is maintained at 10... 8 For systems with a cell / mL density of 1000 or higher, the magnetized functional microorganisms need to be replenished periodically through the bacterial agent injection port to maintain the system's biodegradation activity. Simultaneously, a fluxmeter should be installed in the bioreactor zone to monitor changes in the packing's magnetic properties in real time, ensuring that its magnetic adsorption performance and microbial enrichment effect remain effective throughout long-term operation.

[0018] The magnetic microsphere preparation technology is as follows: Neodymium iron boron powder, curing agent, reactive diluent, and coupling agent are mixed in a ratio of 10:1:0.5:0.1 to prepare magnetic aggregate, ensuring uniform dispersion of the neodymium iron boron powder and reducing agglomeration. Then, the magnetic aggregate is mixed with silica sand, calcium peroxide, and cement in a ratio of 2:1:0.5:1 with an appropriate amount of water. Using a high-speed rotary granulator or spray granulation equipment, the mixture is formed into spherical particles with a diameter of approximately 2-5 mm. The granulated magnetic microspheres are placed in an environment of 40-60 °C and allowed to stand for 12-24 hours to allow for preliminary curing. Subsequently, high-temperature curing (100-150 °C) is applied to improve the compressive strength and water resistance of the microspheres. Finally, magnetization is performed under a strong magnetic field (>2T) to ensure that the remanent magnetization of the magnetic microspheres meets the application requirements.

[0019] The pre-preparation process for magnetized functional microorganisms is as follows: The special culture medium for magnetic bacteria is dissolved in 100 mL of distilled water (1:100) by heating, with 0.02 mmol / L ferric quinate added. The pH is adjusted to 6.7, and the solution is filled to 75% capacity. The mixture is then autoclaved at 116 °C for 20 min. Magnetic bacteria purchased from the ATCC bacterial bank are then added to the culture medium and cultured at 25 °C under a microaerobic environment. At this time, the OD of the magnetic bacteria... 600 The value reaches 0.4 or higher.

[0020] Preferably, the magnetic bacteria are first mixed with lysozyme (3%), and the magnetosomes are released into the culture environment along with the bacterial cells. Then, polyethylene glycol (PEG1200) is used to fuse the magnetosomes with functional microorganisms that can degrade specific pollutants. At this time, the magnetosomes and functional microorganisms are effectively combined to complete the magnetization process of functional microorganisms.

[0021] Preferably, after the magnetic bacteria release protoplasts and magnetosomes through the action of lysozyme, the culture solution containing magnetosomes needs to be passed into a pipe filled with 724 weakly acidic cation exchange resin for adsorption and extraction of lysozyme. The pipe is equipped with a valve to control the inflow of bacterial solution, and the pH of the solution flowing out of the pipe is monitored and adjusted at the same time.

[0022] The uniform inlet and outlet zones are composed of coarse and fine sand, allowing polluted groundwater to flow sequentially through the coarse and fine sand under the action of hydraulic gradient before flowing through the biological reaction zone at a uniform flow rate. The coarse and fine sand can also filter out mud and flocs in the groundwater, thus protecting the reaction wall.

[0023] The bacterial inlet is installed using azimuth-controlled vertical hydraulic fracturing technology and is located at the front end of the Bio-PRB. The bacterial solution can be periodically added from the inlet to maintain the required amount of microorganisms in the groundwater environment.

[0024] Preferably, magnetic spheres of uniform size are made using materials such as neodymium iron boron powder. Increasing their specific surface area can provide more attachment points for magnetized microorganisms. The spheres are determined to be strongly magnetic by a fluxmeter. After being placed in a uniform water immersion area at intervals, the water flow can contact the surface of the spheres and slowly release oxygen.

[0025] The bioreactor zone is composed of uniformly sized magnetic spheres made of materials such as neodymium iron boron powder, arranged in sequence. Magnetized functional microorganisms are injected into the bacterial inlet to ensure full contact with the magnetic spheres. The magnetic spheres achieve rapid adsorption of the microorganisms through magnetic attraction.

[0026] When polluted groundwater flows through the bioreactor zone under its own hydraulic gradient, magnetized microorganisms consume the pollutants in the water as nutrients to maintain their own growth and reproduction. In the process, the pollutants are degraded or transformed, thereby treating the polluted groundwater and reducing the harm of pollutants to the environment.

[0027] Preferably, the magnetometer is located above the magnetic sphere, and the long-term monitoring of the magnetic changes of the magnetic sphere ensures its fixation effect on magnetized microorganisms.

[0028] Pressure gauges are located at the front and rear of the entire reactive barrier and are connected to the groundwater source via pipes. The pressure readings when the water flows into and out of the Bio-PRB characterize the changes in the permeability coefficient within the Bio-PRB.

[0029] This process enables the rapid adsorption of functional microorganisms into the permeable reactive barrier, while also providing a suitable growth environment for aerobic microorganisms in groundwater.

[0030] The permeable bioreactor wall technology of this invention effectively integrates functional microorganisms with magnetic bacteria. Magnetic balls achieve rapid adsorption of functional microorganisms through magnetic attraction to remediate organic polluted groundwater. This not only gives full play to the remediation role of functional microorganisms in polluted groundwater, but also significantly reduces the adsorption time of microorganisms in the packing material, thereby improving the efficiency of permeable bioreactor wall technology in groundwater pollution remediation.

[0031] The beneficial effects of this invention are:

[0032] 1. The coupled magnetization pretreatment and rapid biofilm formation technology enables pre-magnetized functional microorganisms to move rapidly and adhere to the surface of microspheres through magnetic attraction, thereby shortening the biofilm formation time and significantly improving the reaction rate.

[0033] 2. Magnetic aggregates are mixed with silica sand, calcium peroxide, and cement, and then granulated by high-speed rotary granulation or spray granulation to obtain magnetic microspheres with a particle size of 2-5 mm. After pre-curing and high-temperature curing treatment, these microspheres not only have high compressive strength, but also do not experience magnetic attenuation or structural damage even when immersed in water for a long time. Compared with traditional concrete fillers, their mechanical properties are more stable and their service life is longer.

[0034] 3. In the Bio-PRB system, a uniform water inlet zone, a bacterial agent injection port, a bioreactor zone, a fluxmeter, a pressure monitoring point, and a uniform water outlet zone are sequentially set along the groundwater flow direction. The fluxmeter can monitor the magnetic changes of the magnetic spheres in real time, ensuring the stable adsorption effect on the magnetized microorganisms; while the pressure monitoring system monitors the water flow status and reflects changes in the permeability coefficient in a timely manner, which is beneficial for the dynamic control of the project operation. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the present invention;

[0036] Figure 2 This is a schematic diagram of the magnetization functional microbial process of the present invention;

[0037] Figure 3 This is a diagram showing the engineering application distribution of the wall structure, monitoring port, and microbial agent supply port of the present invention.

[0038] Figure 4 A diagram of the magnetized microspheres of this invention;

[0039] In the diagram: 1-1, 1-2, coarse sand; 2-1, 2-2, fine sand; 3, bacterial agent injection port; 4, magnetic spheres; 5, magnetic bacteria; 6, magnetic bodies; 7, lysozyme; 8, magnetic bacterial protoplasts; 9, functional microorganisms; 10, polyethylene glycol; 11, magnetized functional microorganisms; 12, groundwater sampling and monitoring port; 13, bacterial agent replenishment port; 14, bio-permeable reaction wall; 15, groundwater flow direction; 16, pressure sensor; 17, neodymium iron boron powder; 18, concrete particles. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0041] Example 1

[0042] like Figure 1 This embodiment provides a permeable bioreactor system for treating polluted groundwater using coupled magnetization pretreatment and rapid biofilm formation technology. It includes six parts: magnetic microsphere preparation technology, magnetized functional microorganism prefabrication, permeable bioreactor inlet zone, bioreactor zone, groundwater sampling and monitoring port 12, microbial agent replenishment port 13, and permeable bioreactor outlet zone.

[0043] The bioreactor zone is composed of Figure 4 The magnetic spheres shown are arranged in a series. These spheres are made by mixing neodymium iron boron powder, curing agent, reactive diluent and coupling agent in a certain proportion to prepare magnetic aggregate. The magnetic aggregate is then mixed with sand, calcium peroxide, cement and water, and then stirred and granulated. According to the magnetic flux meter test, the spheres have good magnetic properties and can continuously release oxygen in water to maintain aerobic conditions in groundwater.

[0044] The pre-preparation process of the magnetized functional microorganisms is as follows: Figure 2 As shown, magnetic bacteria 5 are mixed with lysozyme 7 to break down the magnetic bacteria and release magnetic bacterial protoplasts 8 and magnetosomes 6; functional microorganisms 9, which can degrade specific pollutants, are mixed with magnetosomes 6 under the action of polyethylene glycol 10, so that the functional microorganisms and magnetosomes can be effectively combined, and the morphology of the magnetized functional microorganisms 11 is observed under a transmission electron microscope.

[0045] Preferably, the magnetic microspheres, made of magnetic materials and calcium peroxide, have a specific surface area of ​​203.1 m² as determined by BET. 2 / g can provide more attachment points for magnetized functional microorganisms. The oxygen release experiment in water shows that the microsphere has a long-term oxygen release capacity. After placing it in a uniform water immersion area at intervals, the water flow and the microsphere contact provide a micro-oxygen environment while blocking soil particles from entering the biological reaction zone.

[0046] After the magnetized microorganisms are poured into the injection port upstream of the bioreactor zone, they are rapidly and directionally adsorbed onto the surface of the magnetic spheres under the magnetic attraction. At this time, microscopic characterization of the magnetic spheres reveals that arc-shaped bacterial bodies are attached to the surface of the spheres over a large area, indicating that bioadsorption is complete.

[0047] When polluted groundwater flows through the bioreactor zone under its own hydraulic gradient, magnetized microorganisms consume the pollutants in the water as nutrients to maintain their own growth and reproduction. In the process, the pollutants are degraded or transformed, thereby treating the polluted groundwater and reducing the harm of pollutants to the environment.

[0048] Example 2

[0049] In a decommissioned chemical plant site, it was found that the plant's long-term illegal discharge of chlorine-containing pollutants had caused excessive levels of chlorinated hydrocarbons in the groundwater. In response to the problem of excessive levels of pollutants such as 1,2-dichloromethane, carbon tetrachloride, and chlorobenzene in the groundwater, this embodiment provides a permeable bioreactor wall technology for treating organically polluted groundwater by coupling magnetization pretreatment with rapid biofilm formation.

[0050] like Figure 2As shown, soil and groundwater contaminated with chlorinated hydrocarbons at the site were used for microbial domestication to obtain functional microorganism 9 that can efficiently degrade chlorinated hydrocarbons in the water body; magnetic bacteria 5 were mixed with lysozyme 7 to cause the magnetic bacteria to break down and release magnetic bacterial protoplasts 8 and magnetic bodies 6; the screened functional microorganism 9 that can degrade chlorinated hydrocarbons was mixed with magnetic bodies 6 under the action of polyethylene glycol 10 to effectively combine the functional microorganisms with the magnetic bodies and complete the magnetization process of the functional microorganisms.

[0051] Furthermore, magnetic spheres made from materials such as neodymium iron boron powder, calcium peroxide, cement, and water, such as... Figure 4 This accessory has the advantages of neodymium iron boron powder being resistant to demagnetization and corrosion, having a simple production process, and being inexpensive. It utilizes the mechanism of calcium peroxide reacting with water to release oxygen, providing oxygen for aerobic microorganisms. It also neutralizes acidic components in groundwater with calcium hydroxide, providing suitable conditions for microbial growth. Under the action of magnetic attraction, it achieves a rapid adsorption process for magnetized functional microorganisms 11.

[0052] Further investigation of the soil and water characteristics of the contaminated site revealed that the groundwater level was 1.5 m below the surface, and the soil structure consisted of an artificial fill layer, a sand layer, a silty clay layer, and a clay layer. A deep trench, 4 m long, 5.5 m deep, and 3 m wide, was excavated using deep trenching equipment. The first 0.5 m of the trench was lined with coarse and fine sand to create an inlet zone for the reactive barrier, ensuring a uniform water flow velocity and trapping mud and water flocs in the groundwater. This reduced the risk of physical-biological blockage caused by trapped mud and water flocs, thus enhancing the long-term effectiveness of the permeable reactive barrier.

[0053] Furthermore, magnetic spheres are placed after the water inlet area of ​​the reaction wall, fixed at the bottom with concrete, and supported and protected at the top with non-magnetic materials to form a bioreaction zone with good magnetic properties. The top is then covered with artificial materials.

[0054] Furthermore, a 0.5 m long effluent zone of the reaction wall was laid after the biological reaction zone using coarse and fine sand to correspond to the flow velocity of the influent zone of the reaction wall, thereby controlling the outflow and inflow velocities of the reaction wall to be consistent. Pressure sensors installed before and after the permeable reaction wall were used to observe that the flow velocity of the polluted groundwater inside the permeable reaction wall was uniform and stable.

[0055] Furthermore, the prepared magnetized functional microbial culture solution (10 9 The microbial count (cells / mL) was poured in at once from the inlet, and water samples were taken from the groundwater sampling and monitoring port for microscopic counting. The observed microbial count in the groundwater flowing out of the reaction wall was far less than 10. 9 The number of cells / mL indicates that the magnetized microorganisms have been adsorbed onto the surface of the magnetic spheres in large quantities.

[0056] Furthermore, a functional microbial magnetization process was carried out every 5 days. The magnetized functional microorganisms were injected through the inoculum replenishment port, and a DX-201 fluxmeter was equipped on top of the magnetic sphere area to measure the change in magnetic flux in the bioreaction zone. During the process, the fluxmeter was observed to fluctuate slightly at around 2500 GS, and the flux count value did not change significantly, indicating that the material in the bioreaction zone was magnetically stable.

[0057] Furthermore, when the polluted groundwater flows through the bioreactor zone, the pollutants in the groundwater come into contact with the magnetized functional microorganisms adsorbed on the magnetic spheres. The magnetized functional microorganisms use pollutants such as 1,2-dichloromethane, carbon tetrachloride, and chlorobenzene as carbon sources for their own growth and metabolism. During the process, they dechlorinate and degrade chlorinated hydrocarbon pollutants, which greatly reduces the pollutant content in the groundwater flowing out of the bioreactor zone. The water quality was tested and found to meet the Class IV water standard in the "Groundwater Quality Standard" (GB / T 14848-2017).

[0058] Furthermore, in this case, the infiltration bioreactor wall maintained good biosorption performance after 100 days of continuous operation during the risk control management of the contaminated site. No blockage was observed in the wall through pressure sensors. The wall maintained a 90% degradation rate of chlorinated hydrocarbons in the contaminated groundwater, indicating that the system has long-term effectiveness in engineering applications.

[0059] Example 3

[0060] Petroleum hydrocarbons (C) were detected in the groundwater at the site of a former petroleum industrial zone. 10 -C 40 To address the issue of excessive petroleum hydrocarbons in the area, this embodiment provides a permeable bioreactor wall technology that combines coupled magnetization pretreatment with rapid biofilm formation to remove petroleum hydrocarbon pollution from groundwater.

[0061] like Figure 3 As shown, soil and groundwater contaminated with petroleum hydrocarbons at the site were used for microbial domestication to obtain functional microorganisms 9 that can efficiently degrade petroleum hydrocarbons in the water body; magnetic bacteria 5 were mixed with lysozyme 7 to dissolve the cell walls of magnetic bacteria, releasing magnetic bacterial protoplasts 8 and magnetosomes 6; the screened functional microorganisms 9 that can degrade chlorinated hydrocarbons were mixed with magnetosomes 6 under the action of polyethylene glycol 10, so that the functional microorganisms and magnetosomes could be effectively combined to complete the magnetization process of the functional microorganisms.

[0062] Furthermore, magnetic spheres made from materials such as neodymium iron boron powder, calcium peroxide, cement, and water, such as... Figure 4 This accessory has the advantages of neodymium iron boron powder being resistant to demagnetization and corrosion, having a simple production process, and being inexpensive. This accessory utilizes magnetic attraction to rapidly adsorb magnetized functional microorganisms 11, thus initiating the biofilm formation process.

[0063] Further hydrogeological investigation of the contaminated site revealed that the groundwater level was approximately 6.5 m below the surface, and the geological structure included a shallow sandy aquifer (0–3 m), a medium-layer clay-sand aquifer (3–8 m), and a deep sandy aquifer (8–20 m). A 9 m long, 14 m deep, and 1.8–2.4 m wide permeable bioreactor system was installed using azimuth-controlled vertical hydraulic fracturing technology. The inlet zone of the reactor was constructed by lining the first 2 m of the reactor with coarse and fine sand to uniformly distribute the influent flow velocity and trap mud flocs in the groundwater, reducing the risk of physical-biological blockage and enhancing the long-term effectiveness of the permeable reactor.

[0064] Furthermore, after the inlet area of ​​the reaction wall, magnetic balls were installed in a removable mesh frame and fixed at the bottom with sand to form a mesh frame with good magnetic properties. The top was covered with artificial materials. The mesh frame can be removed and replaced according to the degradation of organic matter. By measuring the DO in the effluent, it was found that the DO in the effluent of this area was >2 mg / L, which is suitable for the growth of aerobic microorganisms.

[0065] Furthermore, a reaction wall outlet zone paved with coarse and fine sand was constructed 2 m behind the mesh frame to correspond to the flow velocity in the reaction wall inlet zone, thereby controlling the outflow and inflow velocities of the reaction wall to be consistent. Pressure sensors installed before and after the permeable reaction wall were used to observe that the flow velocity of the polluted groundwater within the permeable reaction wall was uniform and stable.

[0066] Furthermore, considering the deep burial depth of the groundwater in this area, the prepared magnetized functional microbial solution (10 9 The bacterial solution (cells / mL) was injected through the injection port using high-pressure rotary jet technology, allowing it to penetrate deeper into the wall. Water samples were taken from the groundwater sampling monitoring port for microscopic counting, revealing that the amount of microorganisms flowing out of the reaction wall was far less than 10. 9 The number of cells / mL indicates that a large number of magnetized microorganisms have been adsorbed onto the surface of the magnetized spheres.

[0067] Furthermore, a functional microbial magnetization process was carried out every 5 days. The magnetized functional microorganisms were injected through the inoculum replenishment port, and a TD-8900 fluxmeter was installed at the top of the bioreactor zone to measure the change in magnetic flux in the bioreactor zone. During the process, the fluxmeter was observed to fluctuate slightly at around 3100 GS, and the flux count value did not change significantly, indicating that the material in the bioreactor zone was magnetically stable.

[0068] Furthermore, as the polluted groundwater flows through the bioreactor zone, the pollutants in the groundwater come into contact with the magnetized microorganisms adsorbed on the magnetic spheres. The magnetized microorganisms use petroleum hydrocarbon pollutants as a carbon source for their own growth and metabolism, and degrade chlorinated hydrocarbon pollutants in the process. This significantly reduces the pollutant content in the groundwater flowing out of the bioreactor zone, and the water quality meets the Class IV water standard in the "Groundwater Quality Standard" (GB / T 14848-2017) after testing.

[0069] Furthermore, in this example, the permeable bioreactor wall of the present invention maintained good biodegradation performance for 260 days during the risk management of the petroleum hydrocarbon contaminated site in the industrial area. No blockage was observed in the wall through pressure sensors. 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 achieves long-term bioremediation of petroleum hydrocarbon contaminated groundwater.

[0070] The specific embodiments shown above provide a detailed description of how the present invention solves the problems existing in the prior art, proposes solutions, and demonstrates its effectiveness. The above descriptions are merely specific embodiments of the present invention and should be understood as including any modifications, equivalent substitutions, and improvements made in accordance with the spirit of the invention within the scope of protection of the present invention.

Claims

1. A permeable bioreactor device for remediating contaminated groundwater, characterized in that, The device includes: a reaction wall inlet zone, located at the front end of the device and filled with quartz sand to intercept flocculent particles in the groundwater; a bioreactor zone following the inlet zone, composed of magnetic microspheres and magnetized functional microorganisms; a bacterial solution injection port located upstream of the top of the bioreactor zone to replenish the functional microorganisms; a permeable bioreactor outlet zone following the bioreactor zone, filled with quartz sand for uniform water discharge; pressure detection points located upstream and downstream of the bioreactor zone; and groundwater sampling and monitoring ports located at the upper parts of the reaction wall inlet zone, the bioreactor zone, and the reaction wall outlet zone. The magnetic microspheres are prepared using magnetized concrete structural units. A magnetic aggregate is prepared by mixing neodymium iron boron powder, curing agent, reactive diluent, and coupling agent in a ratio of 10:1:0.5:0.

1. This magnetic aggregate is then mixed with silica sand, calcium peroxide, and cement in a ratio of 2:1:0.5:1 with an appropriate amount of water. The mixture is then granulated into spherical particles with a diameter of 2-5 mm using a high-speed rotary granulator or spray granulation equipment. The granulated magnetic microspheres are then placed in an environment of 40-60℃ and allowed to stand for 12-24 hours for initial curing. A high-temperature curing treatment at 100-150℃ is then applied. Finally, the microspheres are magnetized under a strong magnetic field greater than 2T to ensure that the remanent magnetic strength meets the requirements for use.

2. A method for remediating contaminated groundwater, characterized in that, Using the permeable bioreactor device as described in claim 1, the method can achieve rapid biofilm formation and efficient degradation of target pollutants by microorganisms in a short time, and is applicable to various types of groundwater pollution remediation scenarios. The steps include: Step 1: Construct a bioreactor zone containing magnetic microsphere packing material within a permeable bioreactor wall; Step 2: Regulate the aquatic chemical environment within the bioreactor zone using calcium peroxide to maintain the metabolic activity of functional microorganisms; Step 3: Add magnetized functional microorganisms into the bioreactor zone, and promote the directional enrichment and rapid biofilm formation of functional microorganisms on the surface of magnetic spheres under the action of magnetic field; Step 4: After the magnetized functional microorganisms complete rapid directional colonization and form a biofilm on the surface of the magnetic spheres, the bioreactor zone establishes a stable pollutant degradation capacity in a short period of time.

3. The method according to claim 2, characterized in that: In step 1, the magnetic spheres include neodymium iron boron powder, accounting for 20-40% of the total mass of the magnetic spheres; this powder is used to maintain the structural stability of the magnetic spheres under groundwater seepage conditions, and its compressive strength is not less than 1 MPa. The slow-release oxygen supply component is calcium peroxide, accounting for 5-15% of the total mass of the magnetic spheres. After magnetization treatment, the magnetic spheres can form a stable magnetic field in the bioreactor zone with a magnetic flux density of 0.1-0.5 T. After culturing the magnetized functional microorganisms for 7 days under the same magnetic field strength conditions, their activity remains above 95% of the initial activity (CFU), indicating that the magnetic field treatment has no significant adverse effect on the activity of the microorganisms. Furthermore, after soaking the magnetic spheres in groundwater for 180 days, their magnetic flux density remains within the range of 0.1-0.5 T, which can continuously enhance the directional attachment of the magnetized functional microorganisms on the surface of the filler and the rapid formation of biofilm.

4. The method according to claim 2, characterized in that: In step 2, the calcium peroxide can continuously release oxygen in groundwater environments with dissolved oxygen concentrations below 0.5 mg / L, with an oxygen release rate of 0.05~0.3 mg / (L·d), and can maintain the dissolved oxygen concentration in the bioreactor zone at 1~4 mg / L, so as to maintain the survival of aerobic microorganisms and the degradation activity of pollutants.

5. The method according to claim 2, characterized in that: In step 3, magnetized functional microorganisms are added to the bioreactor zone through a bacterial inlet located upstream of the bioreactor zone. The concentration of the functional microorganisms is 10^8~10^9 cells / mL. The functional microorganisms are pretreated under a magnetic field of 0.1~0.5 T for 10~30 min before being added. The activity of the magnetized functional microorganisms remains above 95% of the initial activity. Under the stable magnetic field formed by the magnetic spheres, the functional microorganisms can migrate directionally to the surface of the packing material and attach rapidly. They complete the adsorption and colonization of the magnetic spheres within 8 h, and the secretion of extracellular polymers (EPS) is detected within 124 h of culture, thereby promoting the rapid formation of biofilm.

6. The method according to claim 2, characterized in that: In step 4, after the magnetized functional microorganisms rapidly colonize and form a biofilm on the surface of the magnetic spheres, the bioreactor zone can establish a stable pollutant degradation capacity in a short period of time, and the target pollutant removal rate reaches 60-90% within 7 days of startup.

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