A device and method for repairing groundwater ammonia and nitrogen composite pollution

Abstract

The present invention discloses a device and method for remediating groundwater ammonia-nitrogen composite pollution, and relates to the technical field of groundwater pollution remediation. The device and method for remediating groundwater ammonia-nitrogen composite pollution include a pollution plume collection area and a circulation well system, wherein the circulation well system includes an output pipeline, a permeable grid is provided on the left side of the pollution plume collection area, and a reverse osmosis layer is provided on the left side of the permeable grid. The device and method for remediating groundwater ammonia-nitrogen composite pollution, through the pollution plume collection area, the permeable reaction wall, the circulation well system and the water quality monitoring system, form a groundwater ammonia-nitrogen pollution remediation method that integrates pollution collection, circulation remediation and online monitoring. Through the adaptive regulation of groundwater microorganisms and their living environment, the simultaneous removal of ammonia nitrogen and nitrate nitrogen can be achieved, which is convenient for regulation and control, and is suitable for sites where groundwater ammonia nitrogen and nitrate pollution is relatively serious, such as domestic waste landfills.

Description

Technical Field

[0001] The present invention relates to the technical field of groundwater pollution remediation, and in particular to a device and method for remediating groundwater ammonia-nitrogen composite pollution. Background Art

[0002] Groundwater is an integral part of the water resources system and plays a vital role in social life, economic development, and the ecological environment. With the rapid development of the economy and industry, the discharge of domestic sewage, industrial wastewater, and the leakage of leachate from solid waste have significantly increased the levels of harmful substances in groundwater, such as heavy metals, bacteria, inorganic salts, and "three nitrogen" pollution. Soil and groundwater pollution is becoming increasingly serious, threatening human health and ecological security and hindering sustainable economic development. Nitrogen pollution in groundwater is primarily composed of ammonia nitrogen and nitrate nitrogen. Ammonia nitrogen and nitrate nitrogen in drinking water can, under certain conditions, be converted into nitrite nitrogen, which then binds to proteins to form nitrosamines, a potent carcinogen that threatens human health. Therefore, remediation of groundwater ammonia nitrogen pollution is urgent.

[0003] Currently, there is a widespread risk of leachate leakage from municipal solid waste landfills, which can contaminate soil and groundwater. According to surveys, groundwater downstream of landfills exhibits typical complex pollution characteristics, with a wide range of sources and high uncertainty. Once these pollutants enter the groundwater, they will cause serious environmental pollution and ecological damage. Complex pollutants primarily include: (1) COD, which primarily comes from kitchen waste; (2) inorganic salts, such as ammonia nitrogen, total phosphorus, and nitrates, which primarily come from fertilizer or nutrient degradation; and (3) heavy metals, such as cadmium, lead, and mercury, which primarily come from industrial solid waste.

[0004] Permeable reactive barriers (PRBs) and microbial remediation are emerging and cost-effective in-situ groundwater remediation technologies. PRBs utilize specific active fillers within the walls to intercept or remove pollutants from groundwater through adsorption, precipitation, surface complexation, redox reactions, and biodegradation. They effectively remove inorganic salts, highly toxic heavy metals such as cadmium, chromium, and lead, as well as various pollutants such as COD and ammonia nitrogen. The filler provides high coverage of the entire contamination plume and comes into direct contact with the pollutants, achieving in-situ purification. PRBs can treat a wide range of pollutants for extended periods with minimal groundwater disturbance. They require no external power and are simple to construct. These technologies require comprehensive consideration of pollutant characteristics, hydrogeological conditions, economic benefits, and the environmental impact of on-site construction. Microbial remediation degrades groundwater pollutants through microbial enrichment and transformation, and can remediate ammonia nitrogen and nitrate nitrogen pollution.

[0005] Existing permeable reaction walls use single or multiple mixed fillers to remediate ammonia nitrogen pollution, which has the following main problems: (1) It mainly targets a single pollutant and removes the pollutant through traditional adsorption; (2) Nitrification and denitrification occur simultaneously in the contaminated area. During the microbial remediation process, it is necessary to repeatedly adjust the aerobic and anaerobic environment, changing the community structure of the dominant groundwater bacteria in the remediation area. This leads to complex operation, low operating efficiency, inability to remove pollutants simultaneously, and pollution rebound; (3) Groundwater is an oxygen-deficient and low-carbon environment. It is impossible to dynamically adjust the parameters of the microbial agent addition according to the parameters of the polluted water quality, groundwater environment, microbial growth, etc., resulting in poor remediation effect and waste of remediation reagents. How to achieve the simultaneous and efficient removal of pollutants such as COD, nitrogen and phosphorus, heavy metals, and inorganic salts in contaminated sites remains a huge challenge. Therefore, it is urgent to optimize and improve existing technologies and develop a groundwater ammonia nitrogen complex pollution remediation method that integrates pollution collection, circulation remediation, and online monitoring. Summary of the Invention

[0006] (1) Technical problems solved

[0007] In view of the deficiencies in the prior art, the present invention provides a device and method for repairing groundwater ammonia-nitrogen composite pollution, which solves the problems existing in the prior art.

[0008] (2) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions: a groundwater ammonia and nitrogen complex pollution remediation device, comprising a pollution plume collection area and a circulation well system, the circulation well system including an output pipeline, a permeable grid is provided on the left side of the pollution plume collection area, a reverse osmosis layer is provided on the left side of the permeable grid, an impermeable concrete partition is provided above the reverse osmosis layer, and the output pipeline is provided above the pollution plume collection area;

[0010] A permeable reaction wall is provided on the right side of the pollution plume collection area, a first unit nitrification area is provided on the right side of the permeable reaction wall, a second unit denitrification area is provided on the right side of the first unit nitrification area, a permeable grid is provided on the right side of the second unit denitrification area, a third unit adsorption area is provided on the right side of the second unit denitrification area, an extraction well group is provided on the right side of the third unit adsorption area, a water pump is provided above the extraction well group, and a water quality monitoring system is provided on the right side of the extraction well group;

[0011] An aeration device, a nutrient dosing device and nitrifying bacteria are arranged above the first unit nitrification zone, and denitrifying bacteria are arranged above the second unit denitrification zone.

[0012] Preferably, the fillers are all loaded in a loading unit, the loading unit comprises a gabion net and a loading frame, and a hanging ring is provided above the loading unit.

[0013] Preferably, the bottom of the plume collection area is an impermeable layer, 0.5-1m deeper than the groundwater plume. The inlet wall consists of a reverse osmosis layer composed of a sand-gravel-pebble composite layer and a permeable grid. The sand particle size is 1-3mm, the gravel particle size is 10-30mm, the pebble particle size is 20-50mm, and the thickness is 0.3-0.5m. The grid is welded with longitudinal and transverse steel bars to form a perforated grid, with a hole spacing of 2-5cm.

[0014] Preferably, the width of the plume collection area is 0.5-0.8m, creating a large flow cross-section that allows the entire plume to flow into the collection area. The outflow wall of the collection area is a permeable reaction wall, and an impermeable concrete partition is installed above the inlet and outlet walls of the collection area. The partition extends to the ground and is 0.3m above the ground.

[0015] Preferably, the inlet side of the permeable reaction wall is composed of a steel skeleton and a permeable geotextile, with the steel skeleton externally coated with the permeable geotextile. The steel skeleton is made of multiple stainless steel solid tubes welded together vertically and horizontally, with a diameter of 12 to 20 mm and a skeleton width of 30 to 50 cm. The permeable geotextile has a permeability coefficient greater than 5.0 x 10-4 m / s. The outlet side of the permeable reaction wall consists of an upper permeable wall and a lower impermeable watertight wall, with a length ratio of 1:2 between the permeable wall and the watertight wall. The bottom is an impermeable layer, the depth of which is flush with the bottom of the catchment area.

[0016] The permeable reactive wall is divided into three units, each 1.5 to 2 meters wide. A partition is installed between the first and second units, consisting of an upper permeable grid and a lower impermeable concrete partition. A partition is installed between the second and third units, consisting of an upper impermeable concrete partition and a lower permeable grid. The length ratio of the permeable grid to the concrete partition is 1:2.

[0017] Preferably, the first unit nitrification zone is a nitrification zone, filled with active fillers and nitrifying bacteria. The active filler is one of activated zeolite, anthracite, bioceramic aggregate, manganese sand, iron ore, corn cobs, slow-release oxygen granules, or a composite filler; the nitrifying bacteria agent comprises nitrate bacteria, nitrite bacteria, and a nutrient solution.

[0018] The second unit denitrification zone is a denitrification zone filled with active fillers and doped with denitrifying bacteria. The active fillers are selected from activated zeolite, anthracite, bioceramic aggregate, manganese sand, iron ore, corn cobs, slow-release oxygen granules, or a combination thereof. The denitrifying bacteria include Pseudomonas, Alcaligenes, and a nutrient solution.

[0019] The third unit adsorption zone is filled with a purification filter material. The purification filter material is a biochar composite filler, which is a spherical porous particle with a particle size of 2-4 mm. The biochar composite filler is a nano-zero-valent iron composite material of bentonite-modified biochar or a nano-zero-valent iron composite material modified with sulfurized activated carbon, and can be obtained using existing technologies.

[0020] Preferably, the circulation well system is located downstream of the permeable reaction wall, 3 to 5 meters away from the outlet wall, the depth of the extraction well group is 2 meters below the bottom of the permeable wall on the outlet side of the permeable reaction wall, and the well diameter is 0.3 to 0.5 meters.

[0021] Preferably, the water quality monitoring system includes multiple monitoring wells, which are arranged in the nitrification zone, denitrification zone, adsorption zone, and downstream of the circulation well system, 3-5 meters from the extraction well group. The monitoring wells are equipped with automatic sample detection and analysis devices for automated collection, detection, and analysis of multi-layer water quality samples.

[0022] Preferably, wetland plants are planted in the first and second nitrification zones, and heavy metal hyperaccumulators are planted in the third adsorption zone. Wetland plants include plants with strong sewage purification capabilities, such as reed, cattail, iris, loosestrife, lily of the valley, and canna. Heavy metal hyperaccumulators are highly tolerant to heavy metals such as Cr, Pb, Cu, and Cd, and include one or more of the following: Dianthus australis, alfalfa, Ligusticum chuanxiong, Phytolacca baoshanensis, cosmos, ryegrass, and centipede grass.

[0023] A method for repairing a groundwater ammonia-nitrogen composite pollution device, comprising the above-mentioned groundwater ammonia-nitrogen composite pollution repair device, specifically operates as follows:

[0024] A pollution plume collection area, a permeable reaction wall, a circulation well system, and a water quality monitoring system are set up along the seepage direction of the groundwater pollution plume. The water inlet side wall of the collection area consists of a sand-gravel-pebble reverse osmosis layer and a permeable grid, which is used to reduce the pressure and collect the pollution plume, and the captured pollution plume enters the permeable reaction wall. The permeable reaction wall adopts a three-unit baffle wall, which is divided into a nitrification zone, a denitrification zone, and an adsorption zone in sequence. An upper permeable grid and a lower impermeable concrete partition are set between the first and second units; an upper impermeable concrete partition and a lower permeable grid are set between the second and third units, and the length ratio of the permeable grid to the concrete partition is 1:2. The water outlet side wall of the permeable reaction wall consists of an upper permeable wall and a lower impermeable watertight wall, and the length ratio of the permeable wall to the watertight wall is 1:2.

[0025] The first unit is the nitrification zone, filled with active fillers and fed with nitrifying bacteria to remove ammonia nitrogen, COD, and other pollutants. The active filler is selected from activated zeolite, anthracite, bioceramic aggregate, manganese sand, iron ore, corn cobs, slow-release oxygen granules, or a combination thereof. The nitrifying bacteria agent comprises nitrate bacteria, nitrite bacteria, and a nutrient solution. The second unit is the denitrification zone, filled with active fillers and fed with denitrifying bacteria to remove total nitrogen. The denitrifying bacteria agent comprises Pseudomonas, Alcaligenes, and a nutrient solution. The third unit is the adsorption zone, filled with purification filter media to continuously remove residual pollutants such as heavy metals and deeply purify the effluent water quality. The purification filter media is a biochar composite filler consisting of spherical porous particles with a particle size of 2-4 mm. The biochar composite filler is a composite material of nano-zero-valent iron modified with bentonite-modified biochar or nano-zero-valent iron modified with sulfide-coated activated carbon.

[0026] After converging to the catchment area, the pollution plume enters the nitrification zone of the permeable reaction wall. Nitrifying bacteria form biofilms on the filler, adsorbing ammonia nitrogen and simultaneously oxidizing it to nitrite and nitrate. Residual pollutants enter the denitrification zone, where denitrifying bacteria form biofilms on the filler, adsorbing nitrite and nitrate, and simultaneously reducing them to gaseous nitrogen. Upstream water enters the adsorption zone, where zero-valent iron reduction removes residual pollutants. Simultaneously, activated biochar composite fillers adsorb heavy metals and inorganic salts. This enhanced treatment completely removes ammonia nitrogen, heavy metals, and other contaminants. Plants are also planted on the upper portion of the permeable reaction wall, leveraging their roots to absorb and decompose pollutants, deeply purifying the effluent and ensuring water quality meets standards.

[0027] (3) Beneficial effects

[0028] The present invention provides a device and method for remediating groundwater ammonia-nitrogen combined pollution. It has the following beneficial effects:

[0029] (1) The groundwater ammonia nitrogen complex pollution remediation device and method, through the pollution plume collection area, permeable reaction wall, circulation well system and water quality monitoring system, forms a groundwater ammonia nitrogen pollution remediation method integrating pollution collection-circulation remediation-online monitoring. Through the adaptive regulation of groundwater microorganisms and their living environment, the simultaneous removal of ammonia nitrogen and nitrate nitrogen can be achieved, which is easy to control and is suitable for sites with relatively serious groundwater ammonia nitrogen and nitrate pollution, such as domestic waste landfills.

[0030] (2) The pollution plume is intercepted in the catchment area and introduced into a relatively sealed wall for treatment. The buried depth of the wall can be optimized according to the actual situation of the site, which is highly flexible. The multi-unit permeable reaction wall with a folding structure extends the seepage path of the polluted water flow in both thickness and height directions, allowing the pollutants to fully contact the filler and its loaded microorganisms, significantly improving the utilization rate of the filler and the pollutant purification effect.

[0031] (3) Based on the suction action of the pumps in the extraction well group, a circulating water flow is formed in the catchment area-wall, reducing the diffusion of pollutants. Pollutants flow through the permeable reaction wall multiple times through the circulating water flow, causing repeated contact between pollutants and fillers, and achieving water purification through cumulative remediation. The water inlet section of the circulation well can be installed within a certain range of the wall outlet depth, reducing the buried depth and causing less disturbance to the formation and flow field.

[0032] (4) The water quality monitoring system enables online monitoring of groundwater target pollutants, reaction byproducts, water quality parameters, and other indicators. The monitoring results are input into the PLC control system. Through the PLC intelligent control of parameters such as the dosage and time of the microbial agent, the optimal conditions for microbial degradation are effectively guaranteed, the stability and utilization rate of the microorganisms are improved, and the problem of low pollutant removal rate is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a cross-sectional view of the groundwater ammonia-nitrogen combined pollution remediation device of Examples 1 and 2 of the present application;

[0034] Figure 2 (a) is a cross-sectional view of the groundwater ammonia-nitrogen combined pollution remediation device of Example 3 of the present application;

[0035] Figure 3 (b) is a cross-sectional view of the groundwater ammonia-nitrogen combined pollution remediation device of Example 3 of the present application;

[0036] Figure 4 Schematic diagram of the filler loading unit in the reaction wall.

[0037] In the figure: 1. Pollution plume collection area; 11. Reverse osmosis layer; 12. Permeable grid; 13. Impermeable concrete partition; 14. Aeration device; 15. Nutrient dosing device; 2. Permeable reaction wall; 21. First unit nitrification zone; 211. Nitrifying bacteria; 22. Second unit denitrification zone; 221. Denitrifying bacteria; 23. Third unit adsorption zone; 24. Loading unit; 241. Gabion net; 242. Loading frame; 243. Lifting ring; 31. Pumping well group; 32. Water pump; 33. Output pipeline; 4. Water quality monitoring system. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] See also Figure 1-4The present invention provides a technical solution: a groundwater ammonia and nitrogen complex pollution remediation device, comprising a pollution plume collection area 1 and a circulation well system, the circulation well system comprising an output pipe 33, a permeable grid 12 is provided on the left side of the pollution plume collection area 1, a reverse osmosis layer 11 is provided on the left side of the permeable grid 12, an impermeable concrete partition 13 is provided above the reverse osmosis layer 11, and the output pipe 33 is provided above the pollution plume collection area 1;

[0040] A permeable reaction wall 2 is provided on the right side of the pollution plume collection area 1, a first unit nitrification area 21 is provided on the right side of the permeable reaction wall 2, a second unit denitrification area 22 is provided on the right side of the first unit nitrification area 21, a permeable grid 12 is provided on the right side of the second unit denitrification area 22, a third unit adsorption area 23 is provided on the right side of the second unit denitrification area 22, an extraction well group 31 is provided on the right side of the third unit adsorption area 23, a water pump 32 is provided above the extraction well group 31, and a water quality monitoring system 4 is provided on the right side of the extraction well group 31;

[0041] An aeration device 14 , a nutrient dosing device 15 and nitrifying bacteria 211 are provided above the first unit nitrification zone 21 , and denitrifying bacteria 221 are provided above the second unit denitrification zone 22 .

[0042] The fillers are all loaded into a loading unit 24 . The loading unit 24 includes a gabion 241 and a loading frame 242 . A hanging ring 243 is provided above the loading unit 24 .

[0043] The bottom of the plume catchment area 1 is an impermeable layer, 0.5-1m deeper than the groundwater plume. The inlet wall consists of a reverse osmosis layer composed of a sand-gravel-pebble composite layer and a permeable grid. The sand particle size is 1-3mm, the gravel particle size is 10-30mm, the pebble particle size is 20-50mm, and the thickness is 0.3-0.5m. The grid is welded with longitudinal and transverse steel bars to form a perforated grid, with a hole spacing of 2-5cm.

[0044] The plume collection area 1 has a width of 0.5-0.8m, creating a large flow cross-section that allows the entire plume to flow into the collection area. The outflow wall of the collection area is a permeable reaction wall, and an impermeable concrete partition is installed above the inlet and outlet walls of the collection area. The partition extends to the ground and is 0.3m above the ground.

[0045] The inlet side of the permeable reaction wall 2 consists of a reinforced steel frame and a permeable geotextile, with the reinforced frame covered with the permeable geotextile. The reinforced frame is constructed from multiple solid stainless steel tubes welded together in a longitudinal and transverse manner, with a diameter of 12 to 20 mm and a width of 30 to 50 cm. The permeable geotextile has a permeability coefficient greater than 5.0 x 10-4 m / s. The outlet side of the permeable reaction wall consists of an upper permeable wall and a lower impermeable watertight wall, with a length ratio of 1:2 between the permeable wall and the watertight wall. The bottom layer is an impermeable layer, flush with the bottom of the catchment area.

[0046] The permeable reaction wall 2 is divided into three units, each 1.5-2 meters wide. A partition is installed between the first and second units, consisting of an upper permeable grid 12 and a lower impermeable concrete partition. A partition is installed between the second and third units, consisting of an upper impermeable concrete partition and a lower permeable grid 12. The length ratio of the permeable grid to the concrete partition is 1:2.

[0047] The first unit nitrification zone 21 is a nitrification zone filled with active fillers and nitrifying bacteria. The active fillers are selected from activated zeolite, anthracite, bioceramic aggregate, manganese sand, iron ore, corn cobs, slow-release oxygen granules, or a combination thereof. The nitrifying bacteria agent includes nitrate bacteria, nitrite bacteria, and a nutrient solution.

[0048] The second unit denitrification zone 22 is a denitrification zone filled with active fillers and doped with denitrifying bacteria. The active fillers are selected from activated zeolite, anthracite, bioceramsite, manganese sand, iron ore, corn cobs, slow-release oxygen granules, or a combination thereof. The denitrifying bacteria include Pseudomonas, Alcaligenes, and a nutrient solution.

[0049] The third unit adsorption zone 23 is an adsorption zone filled with a purification filter material. The purification filter material is a biochar composite filler, which is a spherical porous particle with a particle size of 2-4 mm. The biochar composite filler is a nano-zero-valent iron composite material of bentonite-modified biochar or a nano-zero-valent iron composite material modified with sulfurized activated carbon, which can be obtained using existing technology.

[0050] The circulation well system is located downstream of the permeable reaction wall 2, 3 to 5 meters away from the outlet wall. The depth of the extraction well group is 2 meters below the bottom of the permeable wall on the outlet side of the permeable reaction wall, and the well diameter is 0.3 to 0.5 meters.

[0051] The water quality monitoring system 4 includes multiple monitoring wells, which are located 3-5 meters downstream of the nitrification zone, denitrification zone, adsorption zone, and circulation well system. Each monitoring well is equipped with an automatic sample detection and analysis device for automated collection, detection, and analysis of multi-layer water quality samples.

[0052] Wetland plants are planted in the first nitrification zone 21 and the second denitrification zone 22, while heavy metal hyperaccumulators are planted in the third adsorption zone 23. Wetland plants include reeds, cattails, irises, loosestrife, lily of the valley, and cannas, all known for their strong wastewater purification capabilities. Heavy metal hyperaccumulators, such as those found in the plant family, are highly tolerant to heavy metals like chromium, lead, copper, and cadmium. These include one or more of the following: Dianthus acutus, alfalfa, Ligusticum chuanxiong, Phytolacca baoshanensis, cosmos, ryegrass, and centipede grass.

[0053] A method for repairing a groundwater ammonia-nitrogen composite pollution device, comprising the above-mentioned groundwater ammonia-nitrogen composite pollution repair device, specifically operates as follows:

[0054] A pollution plume collection area, a permeable reaction wall, a circulation well system, and a water quality monitoring system are set up along the seepage direction of the groundwater pollution plume. The water inlet side wall of the collection area consists of a sand-gravel-pebble reverse osmosis layer and a permeable grid, which is used to reduce the pressure and collect the pollution plume, and the captured pollution plume enters the permeable reaction wall. The permeable reaction wall adopts a three-unit baffle wall, which is divided into a nitrification zone, a denitrification zone, and an adsorption zone in sequence. An upper permeable grid and a lower impermeable concrete partition are set between the first and second units; an upper impermeable concrete partition and a lower permeable grid are set between the second and third units, and the length ratio of the permeable grid to the concrete partition is 1:2. The water outlet side wall of the permeable reaction wall consists of an upper permeable wall and a lower impermeable watertight wall, and the length ratio of the permeable wall to the watertight wall is 1:2.

[0055] The first unit is the nitrification zone, filled with active fillers and fed with nitrifying bacteria to remove ammonia nitrogen, COD, and other pollutants. The active filler is selected from activated zeolite, anthracite, bioceramic aggregate, manganese sand, iron ore, corn cobs, slow-release oxygen granules, or a combination thereof. The nitrifying bacteria agent comprises nitrate bacteria, nitrite bacteria, and a nutrient solution. The second unit is the denitrification zone, filled with active fillers and fed with denitrifying bacteria to remove total nitrogen. The denitrifying bacteria agent comprises Pseudomonas, Alcaligenes, and a nutrient solution. The third unit is the adsorption zone, filled with purification filter media to continuously remove residual pollutants such as heavy metals and deeply purify the effluent water quality. The purification filter media is a biochar composite filler consisting of spherical porous particles with a particle size of 2-4 mm. The biochar composite filler is a composite material of nano-zero-valent iron modified with bentonite-modified biochar or nano-zero-valent iron modified with sulfide-coated activated carbon.

[0056] After converging to the catchment area, the pollution plume enters the nitrification zone of the permeable reaction wall. Nitrifying bacteria form biofilms on the filler, adsorbing ammonia nitrogen and simultaneously oxidizing it to nitrite and nitrate. Residual pollutants enter the denitrification zone, where denitrifying bacteria form biofilms on the filler, adsorbing nitrite and nitrate, and simultaneously reducing them to gaseous nitrogen. Upstream water enters the adsorption zone, where zero-valent iron reduction removes residual pollutants. Simultaneously, activated biochar composite fillers adsorb heavy metals and inorganic salts. This enhanced treatment completely removes ammonia nitrogen, heavy metals, and other contaminants. Plants are also planted on the upper portion of the permeable reaction wall, leveraging their roots to absorb and decompose pollutants, deeply purifying the effluent and ensuring water quality meets standards.

[0057] In summary, the groundwater ammonia nitrogen complex pollution remediation device and method, through the pollution plume collection area, permeable reaction wall, circulation well system and water quality monitoring system, forms a groundwater ammonia nitrogen pollution remediation method that integrates pollution collection-circulation remediation-online monitoring. Through the adaptive adjustment of groundwater microorganisms and their living environment, the simultaneous removal of ammonia nitrogen and nitrate nitrogen can be achieved, which is easy to control and is suitable for sites with serious groundwater ammonia nitrogen and nitrate pollution, such as domestic waste landfills.

[0058] The pollution plume is intercepted in the catchment area and directed into a relatively sealed wall for treatment. The wall's depth can be optimized based on site conditions, offering high flexibility. The multi-unit permeable reaction wall, with its foldable structure, extends the seepage path of the polluted water in both thickness and height, allowing for full contact between pollutants, the filler, and the microorganisms it carries, significantly improving filler utilization and pollutant purification effectiveness.

[0059] The suction action of the pumps in the extraction wells creates a circulating water flow within the catchment area and the wall, reducing pollutant diffusion. Pollutants flow through the permeable reaction wall multiple times through the circulating water, allowing repeated contact between pollutants and the filler, resulting in water purification through cumulative remediation. The inlet section of the circulation well can be installed within a certain depth range of the wall outlet, reducing the buried depth and minimizing disturbance to the formation and flow field.

[0060] The water quality monitoring system enables online monitoring of groundwater target pollutants, reaction byproducts, water quality parameters, and other indicators. The monitoring results are input into the PLC control system. Through the PLC's intelligent regulation of parameters such as the dosage and time of the inoculant addition, optimal conditions for microbial degradation are effectively guaranteed, improving the stability and utilization of microorganisms and addressing the issue of low pollutant removal rates. Example Example 1

[0061] from Figure 1As can be seen, the groundwater ammonia and nitrogen combined pollution remediation device of this embodiment includes a pollution plume collection area 1, a permeable reaction wall 2, a circulation well system, and a water quality monitoring system 4. The pollution plume collection area 1 is located along the seepage direction of the groundwater pollution plume and is used to decompress and collect the pollution plume, allowing the captured pollution plume to enter the permeable reaction wall 2. The bottom of the collection area 1 is an impermeable layer, 0.5 to 1 meter deeper than the depth of the groundwater pollution plume. The wall on the water inlet side consists of a reverse osmosis layer 11 composed of a sand-gravel-pebble composite layer and a permeable grid 12. The sand particle size is 1 to 3 mm, the gravel particle size is 10 to 30 mm, and the pebble particle size is 20 to 50 mm, with a thickness of 0.3 to 0.5 m. The grid is welded with longitudinal and transverse steel bars to form a perforated grid with a hole spacing of 2 to 5 cm. The width of the collection area is 0.5 to 0.8 m, which can form a large flow cross-section, allowing the entire pollution plume to flow into the collection area. The outlet side wall of the collection area is the inlet side wall of the permeable reaction wall 2. An impermeable concrete partition 13 is also provided on the upper part of the inlet and outlet side walls of the collection area. The partition extends to the ground and is 0.3m above the ground to prevent pollutants from overflowing to the ground.

[0062] Permeable reaction wall 2 utilizes a three-unit baffled wall structure, sequentially divided into nitrification zone 21, denitrification zone 22, and adsorption zone 23. The wall is filled with active materials, resulting in a reaction zone with a permeability coefficient 2 to 6 times higher than that of the aquifer. The inlet side of permeable reaction wall 2 consists of a reinforced steel frame and a permeable geotextile, with the reinforced frame covered with the geotextile. The reinforced frame is constructed by welding multiple solid stainless steel tubes, with a diameter of 12 to 20 mm and a width of 30 to 50 cm. The permeable geotextile has a permeability coefficient greater than 5.0 x 10-4 m / s. The outlet side of the permeable reaction wall consists of an upper permeable wall and a lower impermeable barrier wall, with a length ratio of 1:2. The bottom layer is an impermeable layer, flush with the bottom of the catchment area. Permeable reaction wall 2 is divided into three units, each 1.5 to 2 meters wide. A partition is set between the first unit and the second unit, and the partition consists of an upper permeable grille and a lower impermeable concrete partition; a partition is set between the second unit and the third unit, and the partition consists of an upper impermeable concrete partition and a lower permeable grille, and the length ratio of the permeable grille to the concrete partition is 1:2.

[0063] The first unit is the nitrification zone 21, filled with active fillers and dosing with nitrifying bacteria 211 to remove ammonia nitrogen, COD, and other substances. The nitrifying agents include nitrifying bacteria, nitrite bacteria, and a nutrient solution. The second unit is the denitrification zone 22, filled with active fillers and dosing with denitrifying bacteria 221 to remove total nitrogen. The denitrifying agents include Pseudomonas, Alcaligenes, and a nutrient solution. The active fillers are selected from the group consisting of activated zeolite, anthracite, bioceramic aggregate, manganese sand, iron ore, corncobs, and slow-release oxygen granules, or a combination thereof. The inorganic fillers, such as activated zeolite, anthracite, and bioceramic aggregate, have a particle size of 3-10 mm, while the organic filler, corncob granules, have a particle size of 3-6 mm. The slow-release oxygen material comprises 10-20% by mass of nano-calcium peroxide or magnesium peroxide, 15-25% sodium montmorillonite bentonite, 40% zeolite, 1-3% potassium dihydrogen phosphate, and 10-15% polylactic acid. The zeolite particles are 2-5 mm in size and are obtained using existing technology. Nano-CaO2 or MgO2 slowly releases oxygen when in contact with water, providing an oxygen source for microorganisms. This oxygen release process produces alkaline substances. KH2PO4, used as a pH buffer, effectively controls the pH value to 6.5-8.5, providing a suitable living environment for microorganisms. Pollutants enter the reaction zone and are adsorbed by the active filler. Simultaneously, microorganisms form biofilms on the filler surface. The corn cobs and slow-release oxygen particles release carbon and oxygen as nutrients, promoting microbial growth and accelerating the degradation of pollutants such as COD and ammonia nitrogen.

[0064] The third unit, the adsorption zone 23, is filled with purification filter media for the continuous removal of residual pollutants such as heavy metals, deeply purifying the effluent water quality. The purification filter media is a biochar composite filler, consisting of spherical porous particles with a particle size of 2-4 mm. The biochar composite filler is a composite material of nano-zero-valent iron (ZVI) modified with bentonite-modified biochar or nano-ZVI modified with sulfurized activated carbon, and can be obtained using existing technologies.

[0065] Specifically, plants are planted on the upper portion of the permeable reaction wall 2. The first and second units are planted with wetland plants, while the third unit is planted with heavy metal hyperaccumulators. These include plants with strong sewage purification capabilities, such as reeds, cattails, irises, loosestrife, lilyturf, and cannas. Heavy metal hyperaccumulators are highly tolerant to heavy metals such as chromium, lead, copper, and cadmium, and include one or more of the following: Dianthus acutus, Coreopsis grandiflora, alfalfa, Ligusticum chuanxiong, Phytolacca scabra, Viola baoshanensis, cosmos, ryegrass, and centipede grass.

[0066] Specifically, the fillers are loaded into a loading unit 24, which includes a gabion mesh 241 and a loading frame 242 positioned within the mesh. The loading frame is filled with active fillers and purified filter material. The gabion mesh is made of highly galvanized steel wire, measuring 0.5m*0.5m*0.3m, with a mesh diameter of 20mm. A lifting ring 243 is fixed to the top of the gabion mesh. The steel ring is 10cm long and allows lifting equipment to easily access the gabion mesh. Loading unit 24 facilitates stacking, lifting, and replacing fillers, offering advantages such as easy operation and maintenance and minimal environmental impact.

[0067] The circulation well system includes multiple in-situ extraction wells 31, water pumps 32, and water pipelines 33. The extraction wells 31 are located downstream of the permeable reaction wall, 3 to 5 meters from the outlet wall, and 2 meters below the bottom of the permeable wall on the outlet side of the permeable reaction wall. The wells have a diameter of 0.3 to 0.5 meters. If the water quality in the outlet area does not meet the standards, the extraction wells will pump the contaminated water to the pollution plume catchment area for circulation treatment until the effluent quality meets the standards.

[0068] The water quality monitoring system 4 includes multiple monitoring wells equipped with automated sample detection and analysis equipment for automated collection, testing, and analysis of multi-layer water quality samples. The monitoring wells are located 3-5 meters downstream of the extraction wells in the nitrification zone 21, denitrification zone 22, adsorption zone 23, and the circulation well system. The water quality monitoring system 4 is used to monitor the groundwater remediation process and determine the progress of the remediation and the operational status of the permeable reaction wall.

[0069] Specifically, the circulation well system, water quality monitoring system 4, and microbial agent dosing are all automatically controlled by a PLC system, achieving automated and intelligent operation. The automatic sample detection and analysis device primarily uses detectors and sensors to sample and analyze various water indicators, including groundwater level, pH, dissolved oxygen, conductivity, COD, NH3-N, nitrite nitrogen, nitrate nitrogen, heavy metals, and microorganisms (BOD). Water quality information is input into the PLC control system via an A / D converter. The PLC control system evaluates the remediation system's performance based on water quality monitoring information and promptly adjusts microbial agent dosing, such as the type and timing of dosing. Furthermore, the pumping wells are regulated based on water quality monitoring information. If water quality meets standards, remediation is completed. If not, contaminated water from the outlet is pumped out and transported to a catchment area for recirculation treatment until the effluent meets standards. In the later stages of remediation, the permeable reactive wall filler replacement cycle is determined based on water quality monitoring information to improve remediation efficiency. If the filler becomes ineffective in removing pollutants after a long period of use, it can be replaced with a new one.

[0070] After converging to the catchment area, the pollution plume enters the nitrification zone of the permeable reaction wall. Nitrifying bacteria form biofilms on the filler, releasing oxygen and carbon sources to promote microbial growth. Some ammonia nitrogen is adsorbed on the filler, and the microorganisms simultaneously oxidize the ammonia nitrogen into nitrite and nitrate. Residual pollutants enter the denitrification zone, where denitrifying bacteria form biofilms on the filler. Nitrite and nitrate are adsorbed by the filler and simultaneously reduced to gaseous nitrogen by the microorganisms. Upstream water enters the adsorption zone, where zero-valent iron reduction removes residual pollutants. Simultaneously, activated biochar composite fillers absorb heavy metals and inorganic salts. This enhanced treatment completely removes ammonia nitrogen, heavy metals, and other contaminants. Plants are also planted on the upper part of the permeable reaction wall, using their roots to absorb and decompose pollutants, deeply purifying the effluent and ensuring water quality meets standards. Example 2

[0071] from Figure 2 As can be seen, water quality monitoring system 4 includes multiple monitoring wells equipped with automated sample detection and analysis equipment for automated collection, testing, and analysis of multi-layer water quality samples. These monitoring wells are located 3-5 meters from the extraction wells, located in catchment area 1, nitrification area 21, denitrification area 22, adsorption area 23, and downstream of the circulation well system. They monitor water quality and determine the progress of groundwater remediation and the operational status of the permeable reaction wall. The automated sample detection and analysis equipment primarily uses detectors and sensors to sample and analyze various water indicators, including groundwater level, pH, dissolved oxygen, conductivity, COD, NH3-N, nitrite nitrogen, nitrate nitrogen, heavy metals, and microbial (BOD) levels. This water quality information is fed into the PLC control system via an A / D converter. This water quality monitoring information is used to assess the microbial habitat in the groundwater and to adjust the dosage of dissolved oxygen and microbial nutrients in a timely manner.

[0072] The catchment area 1 is also provided with an aeration device 17 and a nutrient dosing device 18. The water quality monitoring system 4, the aeration device 17 and the nutrient dosing device 18 are all automatically controlled by the PLC system to achieve automated and intelligent operation. When the dissolved oxygen concentration is lower than 1 mg / L, the aeration device 17 performs intermittent aeration and oxygenation to the catchment area to make the concentration of dissolved oxygen in the groundwater greater than 2 mg / L. The nutrient dosing device 18 intermittently adds nutrients to the catchment area to promote the growth and reproduction of microorganisms in the reaction area and improve the efficiency of pollutant degradation. Nutrients include carbon sources, nitrogen sources, phosphorus sources, metal ions and essential nutrients for microorganisms. Example 3

[0073] like Figure 2As shown, the bottom of catchment area 1 and permeable reaction wall 2 is an impermeable layer, 0.5 m deeper than the groundwater plume. The catchment area depressurizes and collects contaminated groundwater, capturing it and reducing the plume's spread. The entire plume in catchment area 1 is funneled into the reaction zone of permeable reaction wall 2, allowing for centralized plume treatment, saving costs and facilitating equipment management and maintenance. Two layouts are available for the bottom impermeable layer: (a) sloping in the direction of plume seepage; and (b) with a stepped bottom elevation. Layout (a) is suitable for slopes with a gradient of 1° to 10°. This gradient creates a large hydraulic gradient, enhancing the mobility of the groundwater plume, increasing contact between the plume and the reaction zone, and improving pollutant removal efficiency. Arrangement (b) can extend the seepage path of the polluted water flow, allowing the pollutants to fully contact the filler and its loaded microorganisms. Under the suction action of the extraction well group water pump, a circulating water flow is formed, which passes through the collection area 1 back and forth many times and enters the reaction area, so that the residual pollutants continue to contact the filler, and the water quality is purified through cumulative remediation.

[0074] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0075] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A groundwater ammonia and nitrogen composite pollution remediation device, comprising a pollution plume collection area (1) and a circulation well system, characterized in that: The circulation well system comprises an output pipe (33), a permeable grid (12) is provided on the left side of the pollution plume collection area (1), a reverse osmosis layer (11) is provided on the left side of the permeable grid (12), an impermeable concrete partition (13) is provided above the reverse osmosis layer (11), and the output pipe (33) is provided above the pollution plume collection area (1); A permeable reaction wall (2) is provided on the right side of the pollution plume collection area (1), a first unit nitrification area (21) is provided on the right side of the permeable reaction wall (2), a second unit denitrification area (22) is provided on the right side of the first unit nitrification area (21), a permeable grid (12) is provided on the right side of the second unit denitrification area (22), a third unit adsorption area (23) is provided on the right side of the second unit denitrification area (22), an extraction well group (31) is provided on the right side of the third unit adsorption area (23), a water pump (32) is provided above the extraction well group (31), and a water quality monitoring system (4) is provided on the right side of the extraction well group (31); An aeration device (14), a nutrient dosing device (15), and nitrifying bacteria (211) are provided above the first unit nitrification zone (21), and denitrifying bacteria (221) are provided above the second unit denitrification zone (22).

2. The groundwater ammonia and nitrogen combined pollution remediation device according to claim 1, characterized in that: The bottom of the pollution plume collection area (1) is an impermeable layer, the depth of which is 0.5 to 1 m greater than the depth of the groundwater pollution plume. The wall on the water inlet side is composed of a reverse osmosis layer composed of a sand-gravel-pebble composite layer and a permeable grid. The sand particle size is 1 to 3 mm, the gravel particle size is 10 to 30 mm, the pebble particle size is 20 to 50 mm, and the thickness is 0.3 to 0.5 m. The grid is welded by longitudinal and transverse steel bars into a perforated grid, and the hole spacing is 2 to 5 cm. The width of the pollution plume collection area (1) is 0.5-0.8 m, which can form a large flow section so that all the pollution plumes are collected and flow into the collection area. The water outlet wall of the collection area is a permeable reaction wall water inlet wall. The upper part of the water inlet and outlet wall of the collection area is also provided with an impermeable concrete partition, which extends to the ground and is 0.3 m above the ground.

3. The groundwater ammonia and nitrogen combined pollution remediation device according to claim 1, characterized in that: The permeable reaction wall (2) has an inlet side wall composed of a steel frame and a permeable geotextile, the steel frame is covered with the permeable geotextile, the steel frame is formed by welding a plurality of stainless steel solid pipes in the longitudinal and transverse directions, the pipe diameter is 12-20 mm, the frame width is 30-50 cm, the permeability coefficient of the permeable geotextile is greater than 5.0*10-4 m / s, the outlet side wall of the permeable reaction wall is composed of an upper permeable wall and a lower impermeable water-blocking wall, the length ratio of the permeable wall to the water-blocking wall is 1:2, the bottom is an impermeable layer, the depth of which is flush with the bottom of the catchment area; The permeable reaction wall (2) is divided into three units, each unit having a width of 1.5 to 2 m. A partition is provided between the first unit and the second unit, the partition consisting of an upper permeable grid (12) and a lower impermeable concrete partition; a partition is provided between the second unit and the third unit, the partition consisting of an upper impermeable concrete partition and a lower permeable grid (12), and the length ratio of the permeable grid to the concrete partition is 1:

2.

4. The groundwater ammonia and nitrogen combined pollution remediation device according to claim 1, characterized in that: The first unit nitrification zone (21) is a nitrification zone, filled with active fillers and added with nitrifying bacteria, wherein the active filler is one of activated zeolite, anthracite, biological ceramsite, manganese sand, iron ore, corn cob, slow-release oxygen particles, or a composite filler; the nitrifying bacteria comprises nitrate bacteria, nitrite bacteria, and a nutrient solution; The second unit denitrification zone (22) is a denitrification zone, which is filled with active fillers and added with denitrifying bacteria, wherein the active fillers are a composite of one or more of activated zeolite, anthracite, biological ceramsite, manganese sand, iron ore, corn cobs, and slow-release oxygen particles; the denitrifying bacteria contain Pseudomonas, Alcaligenes, and a nutrient solution; The third unit adsorption zone (23) is an adsorption zone filled with a purification filter material, wherein the purification filter material is a biochar composite filler, the filler is a spherical porous particle with a particle size of 2 to 4 mm, and the biochar composite filler is a nano-zero-valent iron composite material of bentonite-modified biochar or a nano-zero-valent iron composite material modified by sulfide-synergistic activated carbon.

5. The groundwater ammonia and nitrogen combined pollution remediation device according to claim 4, characterized in that: The filler is loaded into a loading unit (24), wherein the loading unit (24) comprises a gabion net (241) and a loading frame (242), and a lifting ring (243) is provided above the loading unit (24).

6. The groundwater ammonia and nitrogen combined pollution remediation device according to claim 1, characterized in that: The circulation well system is located downstream of the permeable reaction wall (2), 3 to 5 meters away from the outlet wall, the depth of the extraction well group is 2 meters below the bottom of the permeable wall on the outlet side of the permeable reaction wall, and the well diameter is 0.3 to 0.5 meters.

7. The groundwater ammonia and nitrogen combined pollution remediation device according to claim 1, characterized in that: The water quality monitoring system (4) includes a plurality of monitoring wells, which are respectively arranged in the nitrification zone, denitrification zone, adsorption zone and downstream of the circulation well system, and are 3 to 5 meters away from the extraction well group. The monitoring wells are provided with automatic sample detection and analysis devices for the automatic collection, detection and analysis of multi-layer water quality samples.

8. The groundwater ammonia and nitrogen combined pollution remediation device according to claim 1, characterized in that: The first unit nitrification zone (21) and the second unit denitrification zone (22) are planted with wetland plants, and the third unit adsorption zone (23) is planted with heavy metal hyperaccumulator herbaceous plants. The wetland plants include reed, cattail, iris, loosestrife, lily of the valley, canna, which are plants with strong sewage purification capabilities. The heavy metal hyperaccumulator plants are extremely resistant to heavy metals such as Cr, Pb, Cu, and Cd, and include one or more of the following: Dianthus australis, alfalfa, Ligusticum chuanxiong, Phytolacca baoshanensis, cosmos, ryegrass, and centipede grass.

9. A method for repairing groundwater ammonia and nitrogen combined pollution, characterized in that: The device for remediating groundwater ammonia-nitrogen composite pollution according to claim 1 is specifically operated as follows: A plume collection area, permeable reaction wall, circulation well system, and water quality monitoring system are arranged along the seepage direction of the groundwater plume. The water inlet wall of the collection area consists of a sand-gravel-pebble reverse osmosis layer and a permeable grid, which is used to decompress and collect the plume. The captured plume enters the permeable reaction wall. The permeable reaction wall adopts a three-unit baffle wall, which is sequentially divided into a nitrification zone, a denitrification zone, and an adsorption zone. An upper permeable grid and a lower impermeable concrete partition are set between the first and second units. An upper impermeable concrete partition and a lower permeable grid are set between the second and third units, and the length ratio of the permeable grid to the concrete partition is 1:

2. The outlet side wall of the permeable reaction wall consists of an upper permeable wall and a lower impermeable watertight wall, and the length ratio of the permeable wall to the watertight wall is 1:

2. The first unit is a nitrification zone, filled with active fillers and added with nitrifying bacteria for removing ammonia nitrogen and COD. The active filler is one of activated zeolite, anthracite, biological ceramsite, manganese sand, iron ore, corn cob, slow-release oxygen particles, or a composite filler. The nitrifying bacteria contain nitrate bacteria, nitrite bacteria, and a nutrient solution. The second unit is a denitrification zone, filled with active fillers and added with denitrifying bacteria for removing total nitrogen. The denitrifying bacteria contain Pseudomonas, Alcaligenes, and a nutrient solution. The third unit is an adsorption zone, filled with purification filter material for continuously removing heavy metal residual pollutants and deeply purifying the effluent water quality. The purification filter material is a biochar composite filler, which is a spherical porous particle with a particle size of 2 to 4 mm. The biochar composite filler is a nano-zero-valent iron composite material modified with bentonite-modified biochar or a nano-zero-valent iron composite material modified with sulfide-synergistic activated carbon. After the pollution plume converges into the catchment area, it enters the nitrification zone of the permeable reaction wall, where nitrifying bacteria form biofilms on the filler, ammonia nitrogen is adsorbed by the filler, and simultaneously oxidized by microorganisms into nitrite and nitrate; residual pollutants enter the denitrification zone, where denitrifying bacteria form biofilms on the filler, nitrite and nitrate are adsorbed by the filler, and simultaneously reduced by microorganisms into gaseous nitrogen; upstream water enters the adsorption zone, where zero-valent iron reduction removes residual pollutants, while activated biochar composite fillers adsorb heavy metals and inorganic salts. After enhanced treatment, ammonia nitrogen and heavy metal pollution is completely removed. Plants are also planted on the upper part of the permeable reaction wall, and the plant roots are used to absorb and decompose pollutants, deeply purifying the effluent and ensuring that the water quality meets the standards.

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