A multiple biological infiltration reaction wall coupling ultrasonic wave and plant remediation in-situ groundwater remediation system and method

Abstract

The application provides a groundwater in-situ remediation system and method of multiple biological permeation reaction wall coupling ultrasonic waves and plant remediation, the groundwater in-situ remediation system comprises a multiple biological permeation reaction wall, a PLC control system and an artificial plant ecological remediation area, the multiple biological permeation reaction wall is arranged in a funnel-gate type engineering, the funnel part blocks the contaminated groundwater through a vertical cement curtain, an ultrasonic generator module is arranged in front of the gate part of the multiple biological permeation reaction wall, the multiple biological permeation reaction wall is divided into two layers, the filling material of the first layer permeation reaction wall is mainly composed of zero-valent iron, iron oxide and construction waste, the filling material of the second layer biological permeation reaction wall is mainly composed of high-performance biological adsorption zeolite and ORC slow-release material calcium peroxide, a microbial bacteria liquid injection pipe is arranged in the second layer biological permeation reaction wall, and monitoring wells are arranged on the two sides of the multiple biological permeation reaction wall and the artificial plant ecological remediation area.The application can treat and remediate multiple composite pollutants at a time, and the pollutant degradation efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of groundwater remediation technology, specifically to an in-situ groundwater remediation system and method that couples multiple biological permeable reactive walls with ultrasonic waves and phytoremediation. Background Technology

[0002] Industrial processes such as metal smelting, chemical production, and electronics manufacturing discharge wastewater and waste residue containing various heavy metals and organic matter. These pollutants can seep into groundwater aquifers via rainwater and surface runoff, harming the groundwater ecosystem along the affected waterways. Currently, groundwater remediation is categorized into ex-situ remediation and in-situ remediation based on the location of the treatment. Ex-situ remediation typically involves extensive excavation, transportation, and off-site treatment and transportation of pollutants, especially when dealing with toxic and hazardous wastes, resulting in longer construction periods and higher costs. In-situ remediation, on the other hand, does not require centralized treatment of pollutants, offers higher treatment efficiency, and provides better long-term results without the need for extensive external power. Furthermore, the diverse technologies available for in-situ remediation can address different types of pollution, making it a highly safe and effective environmental remediation method.

[0003] Permeable reactive walls (PRBs) are remediation technologies that utilize the passive migration of pollutant plumes through a media under a natural hydraulic gradient. The pollutants interact with the media through reactions (oxidation-reduction, adsorption, precipitation, dehalogenation mechanisms, and bioremediation), transforming them into compounds with lower biotoxicity or immobilizing them on the reactive material. PRB engineering is relatively simple and offers long-term effectiveness, achieving significant progress both domestically and internationally. However, the main drawbacks of single PRBs lie in their limited applicability to remediate a wide range of pollutants, clogging and maintenance issues, and limitations in remediation depth and time. Furthermore, the selection of reactive materials is determined by the specific pollutants to be removed, leading to limitations in the treatment of a single pollutant. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides a groundwater in-situ remediation system and method that combines multiple bio-infiltration reaction walls with ultrasonic waves and phytoremediation, solving problems such as the single pollutant treatment by a single infiltration reaction wall and the lack of oxygen and nutrients for aerobic microorganisms in the bio-infiltration reaction wall.

[0005] The technical solution provided by this invention is as follows: A groundwater in-situ remediation system combining a multi-layer bio-infiltration reactive wall with ultrasonic waves and phytoremediation, comprising a multi-layer bio-infiltration reactive wall, a PLC control system, and an artificial phytoremediation zone. The multi-layer bio-infiltration reactive wall is arranged in a funnel-gate type engineering configuration. The funnel section uses a vertical cement curtain to block and collect contaminated groundwater, which then undergoes reaction and remediation through the gate section. An ultrasonic generator module is installed in front of the gate section of the multi-layer bio-infiltration reactive wall. The gate section of the multi-layer bio-infiltration reactive wall is divided into two layers. The first layer of the reactive wall is filled with zero-valent iron, iron oxide, and... The second layer of the bio-permeable reaction wall is mainly composed of construction waste. The filling material is mainly calcium peroxide with high-performance bio-adsorbed zeolite and ORC slow-release material. Microbial liquid injection pipes are installed inside the second layer of the bio-permeable reaction wall. The microbial liquid injection pipes are connected to a vacuum pump, a microbubble generator, and a microbial culture reactor in sequence. Control valves are installed on the connecting pipes. Multiple sets of injection holes are set along the height direction of the microbial liquid injection pipes. Microbial liquid is injected into the second layer of the bio-permeable reaction wall through the injection holes. Monitoring wells are set on both sides of the multi-layer bio-permeable reaction wall and the artificial plant ecological restoration area.

[0006] Furthermore, the funnel portion of the multiple biological permeable reaction wall consists of two symmetrically arranged vertical cement curtains of PO 42.5, which are constructed as concrete walls using a single row of three-axis cement-soil mixing piles to provide vertical barrier function.

[0007] Furthermore, the ultrasonic generator module consists of multiple ultrasonic generators, and the ultrasonic generator module is connected to the PLC control system to receive instructions transmitted by the PLC control system.

[0008] Furthermore, the intensity of the ultrasonic generator is between 1 and 3 W / cm. 2 The action time is 10 to 20 minutes, with an interval of 40 to 50 minutes, and a cycle of 1 hour. The spacing between each ultrasonic reactor is 0.5 to 1 meter.

[0009] Furthermore, the mass ratio of the first layer of permeable reactive wall filling material is as follows: zero-valent iron: 20-50%, iron oxide: 10-20%, construction waste: 30-60%, and the mass ratio of the second layer of biological permeable reactive wall filling material is as follows: zeolite: 25-75%, calcium peroxide: 25-75%.

[0010] Furthermore, the groundwater in-situ remediation system also includes photovoltaic panels. The PLC control system is powered by solar energy absorbed by the photovoltaic panels. The microbial culture reactor, microbubble generator, vacuum pump, and control valves are all connected to the PLC control system and are controlled by the PLC control system.

[0011] Furthermore, the upper part of the microbial inoculum injection pipe is 1.0 to 2 meters above the groundwater level, and the lower part is 0.5 to 1 meter above the impermeable layer. A group of injection holes, with four holes in each group, is arranged every 30 to 50 cm on the microbial inoculum injection pipe.

[0012] Furthermore, the permeability coefficient of the gate portion of the multiple bio-osmotic reaction wall remains constant or gradually increases, with a permeability coefficient range of 1.0 × 10⁻⁶. -4 Up to 3.0×10 -4 The flow rate is cm / s, and the permeable reactive walls are all 1.0 to 2 m above the groundwater level and penetrate 1.0 to 2.0 m into the impermeable layer. The width of the vertical cement curtain in the funnel section of the multi-biological permeable reactive wall is 1.5 to 1.8 times the width of the pollution plume. The width of the permeable reactive wall in the gate section is 0.7 to 1.0 times the width of the pollution plume. The angle between the funnel section and the gate section of the funnel-gate type permeable reactive wall is between 20 and 45°. The surface compacted backfill soil for the funnel-gate type multi-biological permeable reactive wall is selected as cohesive soil in layers, with a compaction degree >0.90.

[0013] Furthermore, the artificial plant ecological restoration area includes a short-cycle hyperaccumulating plant area and a long-cycle hyperaccumulating plant area. The short-cycle hyperaccumulating plants are sunflowers and yellow oleanders, while the long-cycle hyperaccumulating plants are willows. The short-cycle hyperaccumulating plant area is 3 to 5 meters away from the permeability reaction wall, with a width 1.2 to 1.5 times the width of the permeability reaction wall, a length of 10 to 20 meters, and a planting density of 20 to 30 centimeters per plant. The long-cycle hyperaccumulating plant area is 5 to 10 meters away from the permeability reaction wall, with a width 1.2 to 1.5 times the width of the permeability reaction wall, a length of 20 to 30 meters, and a planting spacing of 5 to 10 meters per plant.

[0014] Another technical solution provided by this invention: a method for in-situ remediation of groundwater using a multi-layer bio-permeable reactive barrier coupled with ultrasonic waves and phytoremediation, comprising the following steps:

[0015] (1) The polluted groundwater is blocked and diverted by the vertical cement curtain in the funnel part of the multi-biological infiltration reaction wall, and then flows through the multi-biological infiltration reaction wall in the gate part.

[0016] (2) The PLC control system controls the ultrasonic generator module to perform ultrasonic pretreatment on polluted groundwater, causing cavitation effect;

[0017] (3) When polluted groundwater flows through the first layer of the permeable reaction wall, the pollutants are mainly degraded by adsorption, chelation, reduction and precipitation. The PLC control system uses the microbial culture reactor 11 to cultivate microbial liquid at high density, and then transports it to the microbubble generator for aeration. Through the vacuum pump and the microbial liquid injection pipe, the high-density cultured microbial liquid treated by the microbubble generator is evenly injected from the injection hole and dispersed to the second layer of the biological permeable reaction wall. The pollutants continue to be degraded in the second layer of the biological permeable reaction wall.

[0018] (4) Residual pollutants in groundwater continue to flow into the artificial plant ecological restoration area. The root microorganisms of sunflowers and yellow oleanders in the short-cycle hyperaccumulation plant area and willows in the long-cycle hyperaccumulation plant area will adsorb, extract and detoxify the residual pollutants in the water system.

[0019] (5) The remediation effect of each component of the groundwater in-situ remediation system was monitored by monitoring wells 6 on both sides of the permeable reaction wall and the vegetation remediation area.

[0020] The beneficial effects of this invention are:

[0021] (1) This invention employs a funnel-gate type multi-stage biological permeable reactive wall. Compared with a fully underground permeable wall, the funnel-gate structure reduces the use of reactive materials because reactive materials only need to be filled in the gate area. By treating polluted water flow in a targeted manner, reactive walls can be concentrated in a smaller area, thereby saving materials and construction costs.

[0022] (2) The packing material of the permeable reactive wall in this invention uses iron oxide (Fe3O4 / Fe2O3), which can adsorb heavy metal ions and simultaneously catalyze the reduction reaction of zero-valent iron and extend its service life. Zeolite is a high-performance bio-adsorption porous material with good stability, which can effectively synergistically adsorb and remove pollutants with microorganisms. ORC slow-release material calcium peroxide (CaO2) can slowly decompose in water, continuously releasing oxygen, providing sufficient oxygen for aerobic microorganisms, and promoting the degradation of organic matter or the removal of certain inorganic pollutants. Construction waste, such as fly ash and slag, is also used. These materials have good porosity, chemical stability, and a large specific surface area, and they have the advantage of low cost, making them suitable for large-scale application and promoting resource recycling.

[0023] (3) This invention employs a multi-layered biological permeable reactive barrier to enhance pollutant degradation efficiency. It can treat and remediate multiple complex pollutants in a single treatment. Simultaneously, the addition of microorganisms degrades organic pollutants into small molecules, CO2, and H2O, thereby reducing the degree of packing blockage and maintaining permeability, thus increasing the service life of the permeable reactive barrier. Microorganisms can also dissolve metal minerals, slow down corrosion, and accelerate electron transfer, improving reaction rate and removal efficiency. However, in traditional microbial groundwater remediation, dissolved oxygen and nutrients are the main limiting factors. This invention increases dissolved oxygen through microbubble generator aeration and calcium peroxide decomposition, injecting microbial inoculum and nutrients into the permeable reactive barrier to synergistically treat and remediate pollutants.

[0024] (4) The present invention uses an ultrasonic generator module to pretreat polluted groundwater with ultrasound. Ultrasonic waves can accelerate the reaction between heavy metals and remediation materials (such as zero-valent iron, zeolite, etc.). Through reduction, adsorption and co-precipitation, heavy metal ions such as chromium and lead in the water are removed. This can enhance the reaction rate, promote the degradation of pollutants, avoid clogging of the reaction wall, and ensure long-term stable operation.

[0025] (5) The present invention uses a PLC control system to control the injection of microbial liquid, while providing sufficient nutrients and dissolved oxygen for microorganisms, which can effectively improve the efficiency of microbial degradation of pollution.

[0026] (6) The porous media, ORC slow-release materials and microbial liquids used in this invention are conducive to the enrichment and colonization of indigenous microorganisms that are resistant to pollutants, thereby improving species diversity and ecosystem stability and enhancing restoration efficiency.

[0027] (7) This invention establishes an artificial ecological phytoremediation zone. Phytoremediation is less expensive than other remediation technologies (such as chemical or physical methods) and is suitable for the remediation of large-scale contaminated sites. Many plants can not only absorb or stabilize heavy metals, but also degrade or transform organic pollutants. Enzymes and microorganisms secreted by plant roots can accelerate the degradation of organic matter. Plants can enrich microorganisms, promoting the diversity and stability of ecosystems. The sunflower, yellow oleander, and willow used in this invention are all hyperaccumulators with root depths reaching 2 to 6 meters, enabling them to enrich and absorb residual pollutants to the aboveground parts of the plants. At the same time, the microbial inoculum in the upstream groundwater of the artificial ecological phytoremediation zone contains nutrients, dissolved oxygen, and resistant microbial communities, which can promote the growth of hyperaccumulators and improve the efficiency of plant extraction and enrichment of pollutants.

[0028] (8) The structure and process of this invention are simple, no external power is required, the operation steps are simple, and it can run for a long time. Attached Figure Description

[0029] Figure 1A top view of a groundwater in-situ remediation system that combines multiple bio-permeable reactive walls with ultrasonic waves and phytoremediation.

[0030] Figure 2 for Figure 1 Cross-sectional view of the vertical cement curtain structure at section AA;

[0031] Figure 3 for Figure 1 Longitudinal section cross-section of the vertical cement curtain structure at section BB;

[0032] Figure 4 for Figure 1 Cross-sectional view of the first layer of the multi-layer bio-permeable reactive barrier structure in the CC section;

[0033] Figure 5 for Figure 1 Cross-sectional view of the second-layer multi-layer bio-permeable reactive barrier structure in the middle DD section;

[0034] In the diagram: 1—Vertical cement curtain, 2—First layer of infiltration reaction wall, 3—Second layer of biological infiltration reaction wall, 4—PLC control system, 5—Microbial inoculum injection pipe, 6—Monitoring well, 7—Short-cycle hyperaccumulating plant area, 8—Long-cycle hyperaccumulating plant area, 9—Vacuum pump, 10—Microbubble generator, 11—Microbial culture reactor, 12—Photovoltaic panel, 13—Control valve, 14—Injection hole, 15—Compacted backfill soil, 16—Ultrasonic generator module. Detailed Implementation

[0035] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the present invention. In order to better illustrate the specific embodiments of the present invention, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the actual product size. It is understandable for those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In the description of this invention, it should be noted that the terms "front", "rear", "upper", "lower", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] like Figures 1 to 5 As shown, the in-situ groundwater remediation system designed in this invention mainly includes an ultrasonic generator module 16, a multi-stage biological infiltration reaction wall, a PLC control system 4, and an artificial plant ecological restoration zone. The multi-stage biological infiltration reaction wall is arranged in a funnel-gate type engineering configuration. A vertical cement curtain 1 blocks contaminated groundwater, which is then diverted through the gate to the multi-stage biological infiltration reaction wall for adsorption and purification. The PLC control system 4 controls the ultrasonic generator module 16 for ultrasonic waves, the microbubble generator 10 for aeration, microbial culture, and injection. The groundwater passing through the infiltration reaction wall is further detoxified by super-accumulating plant extraction in the above-ground artificial plant ecological restoration zone.

[0039] The in-situ groundwater remediation system is located along the path of the groundwater contamination plume. The funnel section of the infiltration reaction wall uses a vertical cement curtain 1 to block contaminated groundwater, which is then diverted through a multi-layered biological infiltration reaction wall at the gate section. An ultrasonic generator module 16 is placed in front of the multi-layered infiltration reaction wall to perform ultrasonic pretreatment of the contaminated groundwater. The groundwater sequentially passes through the first layer of infiltration reaction wall 2 and the second layer of biological infiltration reaction wall 3. A PLC control system 4 controls the microbial culture reactor 11, microbubble generator 10, vacuum pump 9, microbial inoculum injection pipe 5, and control valve 13 to inject microbial inoculum into the biological infiltration reaction wall 3. Simultaneously, the PLC system 4 also controls the ultrasonic generator module 16. The PLC control system 4 is powered by solar energy absorbed by photovoltaic panels 12. After purification, the groundwater sequentially passes through the above-ground artificial plant ecological restoration zone (short-cycle hyperaccumulating plant zone 7 and long-cycle hyperaccumulating plant zone 8) for extraction and detoxification. Monitoring wells 6 are located on both sides of the multi-layered biological infiltration reaction wall and the plant restoration zone to monitor the groundwater. A layer of compacted backfill soil 15 covers the surface of the multi-layered biological infiltration reaction wall.

[0040] The funnel-gate type multi-stage biological permeable reactive barrier's vertical cement curtain 1, part of the funnel engineering, employs a single-row, three-axis mixing pile process to construct the cement curtain, which serves as a vertical barrier to divert contaminated groundwater. The vertical cement curtain 1 uses PO 42.5 cement with a cement content of 20% and a cement usage of 360 kg per cubic meter of concrete, with a water-cement ratio of 0.55 to 1.5. The vertical cement curtain 1 is 1.0 to 2 m above the groundwater level and penetrates 0.8 to 1.5 m into the impermeable layer (impermeable layer permeability coefficient <1.0 × 10⁻⁶). -7 (cm / s) to avoid contaminating groundwater that failed to be diverted to the gate for repair of the multi-bioreactor wall.

[0041] The ultrasonic generator module 16 is located before the gate section of the funnel-gate type multi-stage biological permeable reactor wall, and performs ultrasonic pretreatment on contaminated groundwater. The ultrasonic generator module 16 consists of multiple ultrasonic generators. When ultrasonic waves propagate in a liquid, they induce cavitation, which enhances the reaction rate, promotes the breakdown and degradation of organic matter, and induces the precipitation of heavy metals. Simultaneously, the vibration of the ultrasonic waves helps maintain the permeability of the permeable reactor wall, avoids clogging problems, and ensures long-term stable operation.

[0042] The ultrasonic generator module 16 is controlled by a PLC control system 4. The ultrasonic generator intensity is between 1 and 3 W / cm². 2 The ultrasonic intensity should be moderate to avoid damaging the reactive barrier or causing excessive cavitation. The action time should be 10 to 20 minutes, with intervals of 40 to 50 minutes, for a 1-hour cycle to ensure effective contaminant treatment and a long service life for the equipment. The spacing between each ultrasonic reactor should be 0.5 to 1 meter to ensure that the ultrasonic waves cover the entire effective area of ​​the permeation reactive barrier.

[0043] The gate engineering part of the funnel-gate type multi-layer biological osmotic reaction wall is a multi-layer biological osmotic reaction wall, including a first layer of osmotic reaction wall 2 and a second layer of biological osmotic reaction wall 3.

[0044] The first layer of the permeable reactive wall 2 is filled with a combination of zero-valent iron (ZVI), iron oxide (Fe3O4 / Fe2O3), and construction waste (fly ash and slag). Zero-valent iron (ZVI) is mainly used to reduce and remove pollutants from groundwater, especially heavy metals (such as chromium, arsenic, cadmium, and lead) and organic pollutants (such as halogenated hydrocarbons). Iron oxide (Fe3O4 / Fe2O3) mainly plays an adsorption and catalytic role, adsorbing heavy metal ions while simultaneously catalyzing and promoting the reduction reaction of ZVI and extending its service life. Construction waste (fly ash and slag) is porous, capable of adsorbing pollutants, neutralizing acidic wastewater, and facilitating waste resource utilization.

[0045] The packing composition of the first layer of the bio-permeable reactive wall 2 is as follows: Zero-valent iron (ZVI): 20-50%, iron oxide (Fe3O4 / Fe2O3): 10-20%, construction waste (fly ash, slag): 30-60%. The second layer of the bio-permeable reactive wall 3 is primarily filled with high-performance biosorbent zeolite and ORC slow-release material calcium peroxide (CaO2). Zeolite has good stability and can effectively synergistically adsorb and remove heavy metals and organic pollutants with microorganisms. Calcium peroxide (CaO2) can slowly decompose in water, continuously releasing oxygen, providing sufficient oxygen for aerobic microorganisms, promoting the degradation of organic matter or the removal of certain inorganic pollutants. The packing composition of the second layer of the bio-permeable reactive wall is as follows: Zeolite: 25-75%, Calcium peroxide: 25-75%.

[0046] The microbial community injected into the second layer of the bioreactive wall (layer 3) originated from the natural environment of the contaminant plume. Groundwater and soil samples containing contaminants were taken. Under simulated underground temperatures in the laboratory, various culture media containing different nutrients were selected, and the degradation rate of contaminants was measured under different aeration rates and incubation times. Based on the results showing the highest contaminant degradation rate, the optimal resistant microbial community, culture medium, and aeration conditions were obtained. Aerobic conditions were chosen to screen for resistant microbial communities because aerobic microorganisms have high metabolic efficiency and strong contaminant tolerance, which is beneficial for improving the remediation efficiency of the bioreactive wall.

[0047] For screening resistant microbial communities, the following three media were selected: LB medium (Luria-Bertani Broth), M9 salt medium, and NB medium (Nutrient Broth). LB medium formulation: Yeast extract: 0.5%-1%, peptone: 0.5%-1%, sodium chloride: 0.5%-1%, water: to a final volume of 1L. M9 salt medium: Sodium chloride: 0.5g / L, calcium chloride: 0.01g / L, magnesium chloride: 0.1g / L, potassium dihydrogen phosphate: 3.0g / L, ammonia (NH4Cl): 1.0g / L, glucose: 0.2%-1%, water: to a final volume of 1L. NB medium: Peptone: 0.5%-1%, yeast extract: 0.3%-0.5%, sodium chloride: 0.5%-0.8%, water: to a final volume of 1L. By selecting the same aeration rate and incubation time, and simulating the types and concentrations of pollutants in the pollution source, the experimental group of culture medium with the highest pollutant degradation rate was selected to obtain the preferred culture medium.

[0048] For screening resistant microbial communities, dissolved oxygen (DO) was selected as the indicator, with the DO concentration ranged from 2 to 6 mg / L. Under optimized culture conditions and for the same culture time, the types and concentrations of pollutants within the pollution source were simulated to select the experimental group with the highest and most economical pollutant degradation rate, thus obtaining the optimal aeration conditions.

[0049] For screening the culture time of resistant microbial communities, the culture time conditions were selected within the range of 3-7 days. Under the optimized culture medium and aeration conditions, the types and concentrations of pollutants in the pollution source were simulated to select the experimental group with high pollutant degradation rate and economical culture time, thus obtaining the optimal culture time.

[0050] To screen for resistant microbial communities, under optimized culture medium, aeration rate, and culture time conditions, the types and concentrations of pollutants within the pollution source were simulated to stress and screen for microorganisms with strong resistance and pollutant degradation capabilities. After 3-9 subcultures, once the pollutant degradation rate was roughly stable, the optimized microbial community was obtained. Simultaneously, the optimized microbial community was expanded and stored as a seed culture at -80℃.

[0051] After determining the preferred microbial community, culture medium, aeration rate, and culture time, the microbial culture solution is cultured, aerated, and injected into the bio-osmotic reaction wall 3 through the PLC control system 4. The PLC control system 4 is powered by absorbing solar energy through the photovoltaic panel 12.

[0052] The PLC control system 4 inoculates a selected resistant microbial community into the microbial culture reactor 11, sets the culture temperature and aeration rate, and cultivates a resistant microbial solution for treating polluted groundwater. The resistant microbial solution obtained through screening and high-density cultivation exhibits good resistance to pollutants and has a stronger remediation efficiency than native microorganisms.

[0053] Furthermore, the control valve 13 is opened via the PLC control system 4 to deliver the high-density cultured resistant microbial solution to the microbubble generator 10. The microbubble generator produces smaller bubbles, providing a higher gas-liquid interface area and increasing the solubility of oxygen in water, thereby promoting the metabolic activity and chemical reaction rate of the microorganisms. The aeration rate of the microbubble generator 10 is adjusted by the PLC control system 4 to mix the resistant microbial solution, and then it is injected under pressure via the vacuum pump 9.

[0054] The PLC control system 4 regulates the microbial inoculum injection pipe 5. The upper part of the microbial inoculum injection pipe 5 is 1.0 to 2m above the groundwater level, and the lower part is 0.5 to 1m above the impermeable layer. The microbial inoculum injection pipe 5 has injection holes 14, arranged in groups of 4 holes every 30 to 50cm, to ensure that the injected microbial inoculum is evenly distributed within the bio-permeable reaction wall 3.

[0055] For the injection parameters of the microbial culture infusion tube 5, the injection volume, injection rate, and injection cycle for each injection well 14 were screened. The selected injection volume range was 150-300 mL, the injection rate range was 50-100 mL / h, and the injection cycle range was 20-40 days. The determination of the injection well parameters required small-scale and pilot-scale tests in the laboratory to simulate the hydrogeological conditions of the pollutant strata, obtaining the optimal injection parameters when the injected microbial culture achieved the best remediation efficiency.

[0056] The permeability coefficient of the permeable reactive barrier in the gate engineering section should remain constant or gradually increase, with a permeability coefficient range of 1.0 × 10⁻⁶. -4 Up to 3.0×10 -4 cm / s, ensuring that contaminated groundwater can pass smoothly through the permeable reactive barrier.

[0057] The permeable reactive barriers are all 1.0 to 2 meters above the groundwater level and penetrate 1.0 to 2.0 meters into the impermeable layer (the permeability coefficient of the impermeable layer is <1.0 × 10⁻⁶). -7 (cm / s) to prevent polluted groundwater from entering downstream watersheds without remediation.

[0058] For the funnel-gate type multi-bio-permeable reactive wall, the surface compacted backfill soil is selected as 15. Cohesive soil is selected for layered backfilling with a compaction degree >0.90.

[0059] The width of the vertical cement curtain 1 in the funnel section is 1.5 to 1.8 times the width of the contaminant plume. The widths of the permeable reactive walls 2 and 3 in the gate section are 0.7 to 1.0 times the width of the contaminant plume. The angle between the funnel section and the gate section of the funnel-gate type permeable reactive wall ranges from 20 to 45°. By concentrating and guiding groundwater through the funnel to the more permeable gate section, the direction and velocity of groundwater flow are effectively controlled, ensuring that contaminants fully enter the reaction zone, reducing head loss, and improving remediation efficiency. Furthermore, only a small area around the gate needs to be filled with reactive material, saving material and construction costs.

[0060] The phytoremediation zone is mainly divided into a short-cycle hyperaccumulating plant zone 7 and a long-cycle hyperaccumulating plant zone 8. After the contaminated groundwater is purified by adsorption through multiple bio-infiltration reaction walls, the remaining pollutants in the groundwater will be extracted and detoxified again by the above-ground hyperaccumulating plants as they flow through the phytoremediation zone. The injected microbial solution contains nutrients to improve soil nutrient levels and promote the growth of hyperaccumulating plants. At the same time, the resistant microbial community in the microbial solution will accumulate near the plant roots, synergistically degrading and adsorbing pollutants.

[0061] The short-cycle hyperaccumulation plant zone 7 mainly grows sunflowers and yellow oleanders, which are more suitable for planting near the permeability reaction wall. Sunflowers have a taproot system and grow relatively quickly, usually completing their entire growth cycle in 3-4 months. Yellow oleanders are drought-resistant shrubs or small trees, and their root system can reach a depth of more than 2 meters within 3-4 years, gradually forming a stable deep root system.

[0062] For short-cycle hyperaccumulation plant zone 7, it is recommended to keep the distance from the infiltration reaction wall by 3 to 5 meters, the width of which is 1.2 to 1.5 times the width of the infiltration reaction wall, the length of which is 10 to 20 meters, and the planting density of each plant is 20 to 30 cm. Sunflowers and yellow oleanders should be intercropped.

[0063] The long-term hyperaccumulating plant zone 8 in the artificial plant ecological restoration area is mainly planted with willows. Willows have deep and wide-ranging root systems, which enhance their effectiveness in stabilizing soil and remediating pollutants. Willow roots can reach a depth of 3 to 6 meters within 3 to 5 years, especially in moist and well-drained soils.

[0064] Because the root system of willow trees extends over a large area, the long-cycle super-accumulation plant zone 8 should be 5 to 10 meters away from the permeability reaction wall. The width of the permeability reaction wall should be 1.2 to 1.5 times the width of the permeability reaction wall, and the length should be 20 to 30 meters. The planting spacing should be 5 to 10 meters per tree.

[0065] Monitoring wells 6 are arranged along the contaminated groundwater flow path, with one well on each side of the infiltration reactive barrier and the phytoremediation zone, for a total of three wells. Monitoring wells 6 are positioned 1.5-3 meters from the infiltration reactive barrier and the phytoremediation zone to detect changes in pollutants as they pass through various parts of the in-situ groundwater remediation system, thus assessing the remediation effect. The monitored pollutants include various heavy metals (chromium (Cr), arsenic (As), antimony (Sb), copper (Cu), zinc (Zn), manganese (Mn), etc.) and organic hydrocarbons (chlorinated hydrocarbons (CHC), benzene compounds (BTEX), etc.).

[0066] The specific repair method of this invention is as follows:

[0067] After contaminated groundwater enters the local in-situ groundwater remediation system, it converges through the gate section of the multi-stage biological infiltration reaction wall under the obstruction and diversion effect of the vertical cement curtain 1 in the funnel section. This reduces head loss, improves remediation efficiency, and saves on reaction wall materials and construction costs. An ultrasonic generator module 16 is installed before the gate section of the multi-stage infiltration reaction wall, controlled by a PLC control system 4 to perform ultrasonic pretreatment on the contaminated groundwater, inducing cavitation, which enhances the reaction rate and promotes the removal of organic matter and heavy metals. Simultaneously, it reduces reaction wall clogging, ensuring its long-term stable operation. As the contaminated groundwater flows through the first-layer infiltration reaction wall 2, pollutants are degraded primarily through adsorption, chelation, reduction, and precipitation. The PLC control system 4 utilizes a microbial culture reactor 11 to cultivate microbial culture solution at high density, then opens the control valve 13 to deliver it to the microbubble generator 10 for aeration, increasing the gas-liquid reaction area and dissolved oxygen, and enhancing the microbial pollutant degradation capacity. High-density cultured microbial solution, treated by microbubble generator 10, is uniformly injected through injection hole 14 via vacuum pump 9 and microbial solution injection pipe 5, dispersing it into the second layer of bio-permeable reaction wall 3. PLC control system 4 is powered by photovoltaic panel 12. In the second layer of bio-permeable reaction wall 3, pollutants are degraded primarily through adsorption, chelation, bio-oxidation, and precipitation. Residual pollutants in the groundwater continue to flow into the phytoremediation zone. Sunflowers, yellow oleanders, and willows in the short-cycle hyperaccumulating plant zone 7 and long-cycle hyperaccumulating plant zone 8 exhibit strong resistance to pollutants. Utilizing their rapid growth rate and deep-rooted root systems, they can enrich root microorganisms, adsorbing, extracting, and detoxifying residual pollutants in the water system. Monitoring wells 6 are constructed on both sides of the permeable reaction wall and the phytoremediation zone to monitor the remediation effects of each component of the in-situ groundwater remediation system.

[0068] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A groundwater in-situ remediation device using a multi-layered bio-permeable reactive wall coupled with ultrasonic waves and phytoremediation, characterized in that: The system includes a multi-layer biological infiltration reaction wall, a PLC control system (4), and an artificial plant ecological restoration area. The multi-layer biological infiltration reaction wall is arranged in a funnel-gate type. The funnel part is blocked and collected by a vertical cement curtain (1), and then the gate part is used for reaction and restoration. An ultrasonic generator module (16) is installed in front of the gate part of the multi-layer biological infiltration reaction wall. The gate part of the multi-layer biological infiltration reaction wall is divided into two layers. The mass ratio of the filling material of the first layer of the infiltration reaction wall (2) is as follows: zero-valent iron: 20-50%, iron oxide: 10-20%, construction waste: 30-60%. The filling material of the second layer of the biological infiltration reaction wall (3) is... The mass ratio is as follows: zeolite: 25-75%, calcium peroxide: 25-75%. A microbial liquid injection pipe (5) is set in the second layer of biological permeation reaction wall (3). The inlet of the microbial liquid injection pipe (5) is connected to the vacuum pump (9), microbubble generator (10), and microbial culture reactor (11). A control valve (13) is set on the connecting pipe. Multiple sets of injection holes (14) are set along the height direction on the microbial liquid injection pipe (5). Microbial liquid is injected into the second layer of biological permeation reaction wall (3) through the injection holes (14). Monitoring wells (6) are set on both sides of the multiple biological permeation reaction wall and the artificial plant ecological restoration area.

2. The in-situ groundwater remediation device according to claim 1, characterized in that: The funnel section of the multi-bio-permeable reactive wall consists of two symmetrically arranged sets of vertical cement curtains made of P.O42.5, which are constructed using a single row of three-axis cement-soil mixing piles to serve as a vertical barrier.

3. The in-situ groundwater remediation device according to claim 1, characterized in that: The ultrasonic generator module (16) consists of multiple ultrasonic generators. The ultrasonic generator module (16) is connected to the PLC control system (4) and receives instructions transmitted by the PLC control system (4).

4. The in-situ groundwater remediation device according to claim 3, characterized in that: The intensity of the ultrasonic generator is between 1 and 3 W / cm². 2 The action time is 10 to 20 minutes, with an interval of 40 to 50 minutes, and a cycle of 1 hour. The spacing between each ultrasonic reactor is 0.5 to 1 m.

5. The in-situ groundwater remediation device according to claim 1, characterized in that: The groundwater in-situ remediation system also includes a photovoltaic panel (12). The PLC control system (4) is powered by absorbing solar energy through the photovoltaic panel (12). The microbial culture reactor (11), microbubble generator (10), vacuum pump (9), control valve (13) and ultrasonic generator module (16) are all connected to the PLC control system (4) and are controlled by the PLC control system (4).

6. The in-situ groundwater remediation device according to claim 1, characterized in that: The upper part of the microbial liquid injection pipe (5) is 1.0 to 2 m above the groundwater level, and the lower part is 0.5 to 1 m above the impermeable layer. A set of injection holes (14) is arranged every 30 to 50 cm on the microbial liquid injection pipe (5), with 4 holes in each set.

7. The in-situ groundwater remediation device according to claim 1, characterized in that: The permeability coefficient of the gate portion of the multiple bio-osmotic reaction wall remains constant or gradually increases, with a permeability coefficient range of 1.0 × 10⁻⁶. −4 Up to 3.0×10 −4 cm / s, the permeable reaction wall is 1.0 to 2 m higher than the groundwater level and penetrates 1.0 to 2.0 m into the impermeable layer. The width of the funnel part of the multi-biological permeable reaction wall perpendicular to the cement curtain (1) is 1.5 to 1.8 times the width of the pollution plume. The width of the gate part of the permeable reaction wall is 0.7 to 1.0 times the width of the pollution plume. The angle between the funnel part and the gate part of the funnel-gate type permeable reaction wall is 20 to 45°. The compacted backfill soil (15) on the surface of the funnel-gate type multi-biological permeable reaction wall is selected to be cohesive soil backfilled in layers with a compaction degree >0.

90.

8. The in-situ groundwater remediation device according to claim 1, characterized in that: The artificial plant ecological restoration area includes a short-cycle hyperaccumulating plant area (7) and a long-cycle hyperaccumulating plant area (8). The short-cycle hyperaccumulating plant area (7) is planted with sunflowers and yellow oleanders, and the long-cycle hyperaccumulating plant area (8) is planted with willows. The short-cycle hyperaccumulating plant area (7) is 3 to 5 m away from the infiltration reaction wall, with a width 1.2 to 1.5 times the width of the infiltration reaction wall and a length of 10 to 20 m. The planting density is 20 to 30 cm per plant. The long-cycle hyperaccumulating plant area (8) is 5 to 10 m away from the infiltration reaction wall, with a width 1.2 to 1.5 times the width of the infiltration reaction wall and a length of 20 to 30 m. The planting spacing is 5 to 10 m per plant.

9. A method for in-situ groundwater remediation using a multi-layered bio-permeable reactive barrier coupled with ultrasonic waves and phytoremediation, implemented using the in-situ groundwater remediation device as described in any one of claims 1-8, characterized in that... Includes the following steps: (1) The polluted groundwater is blocked and diverted by the vertical cement curtain (1) in the funnel part of the multi-biological infiltration reaction wall, and then flows through the multi-biological infiltration reaction wall in the gate part. (2) PLC control system (4) controls ultrasonic generator module (16) to perform ultrasonic pretreatment on polluted groundwater, causing cavitation effect; (3) Polluted groundwater flows through the first layer of permeable reaction wall (2), and pollutants are degraded by adsorption, chelation, reduction and precipitation. The PLC control system (4) uses the microbial culture reactor (11) to cultivate microbial liquid at high density, and then transports it to the microbubble generator (10) for aeration. Through the vacuum pump (9) and the microbial liquid injection pipe (5), the high-density cultured microbial liquid treated by the microbubble generator (10) is evenly injected from the injection hole (14) and dispersed to the second layer of biological permeable reaction wall (3). Pollutants continue to be degraded in the second layer of biological permeable reaction wall (3). (4) Residual pollutants in groundwater continue to flow into the artificial plant ecological restoration area. The sunflower and yellow oleander in the short-cycle hyperaccumulation plant area (7) and the willow in the long-cycle hyperaccumulation plant area (8) enrich root microorganisms to adsorb, extract and detoxify the residual pollutants in the water system. (5) Monitor the remediation effect of each component of the groundwater in-situ remediation system through the monitoring wells on both sides of the infiltration reaction wall and the vegetation remediation area (6).

Images