CN116332417A

CN116332417A - Groundwater treatment system

Info

Publication number: CN116332417A
Application number: CN202310342994.4A
Authority: CN
Inventors: 王晓丽; 肖超; 付鹏程; 杨振; 衣桂米; 张婉秋; 王聪毛; 赵昱皓
Original assignee: Jereh Environmental Protection Technology Co Ltd
Current assignee: Jereh Environmental Protection Technology Co Ltd
Priority date: 2023-03-29
Filing date: 2023-03-29
Publication date: 2023-06-27

Abstract

The application provides a groundwater treatment system relates to environmental protection technical field, solves at present because the existence of nitrate leads to the not good technical problem of removal effect of heavy metal in the groundwater easily. The groundwater treatment system comprises a nitrate removal unit and a first permeable reactive barrier; wherein the nitrate removal unit is used for removing nitrate in a target pollution area, the first permeable reactive barrier is arranged at the downstream of the target pollution area, and the first permeable reactive barrier is filled with iron-based materials.

Description

Groundwater treatment system

Technical Field

The application relates to the technical field of environmental protection, in particular to a groundwater treatment system.

Background

Permeable reactive barrier is a common in situ treatment technique for groundwater remediation by blocking and remediating groundwater through permeable reactive barriers filled with a reactive media. The reaction wall is filled with iron-based materials to remove heavy metals, so that the method is a common means for treating heavy metal polluted underground water at present.

For example, CN106315816a discloses a permeable reactive barrier technology for removing various heavy metal ions from wastewater by filling a permeable reactive barrier with a mixture of zero-valent iron and zero-valent aluminum. As another example, CN111320216a discloses a groundwater heavy metal remediation reaction medium material for treating groundwater contaminated with various heavy metals by filling a reaction medium comprising quartz sand, iron powder and zeolite powder into a permeable reaction wall.

However, groundwater flowing through permeable reactive barriers contains not only heavy metal ions, but often also nitrates. The inventors have found that the presence of nitrate tends to deactivate the iron-based material in the permeable reactive barrier, resulting in poor removal of heavy metals from groundwater.

Disclosure of Invention

The application provides a groundwater treatment system, can be used for solving the present technical problem that the removal effect of heavy metal in groundwater is not good because of the existence of nitrate easily leads to.

In a first aspect, embodiments of the present application provide a groundwater treatment system including a nitrate removal unit and a first permeable reactive wall;

wherein the nitrate removal unit is used for removing nitrate in a target pollution area, the first permeable reactive barrier is arranged at the downstream of the target pollution area, and the first permeable reactive barrier is filled with iron-based materials.

Optionally, in one embodiment, the target polluted area includes in-situ nitrate-reducing bacteria therein, and the nitrate removal unit includes a first conveying unit for conveying a nutrient solution for promoting growth and propagation of the in-situ nitrate-reducing bacteria to the target polluted area.

Optionally, in one embodiment, the system further comprises an iodate removal unit for removing iodate in a target in situ reaction zone disposed between the target contaminated zone and the first permeable reactive wall.

Optionally, in one embodiment, the nutrient solution includes a calcium salt solution, and the iodate removal unit includes a second delivery unit; the second delivery unit is configured to deliver a carbonate solution to the target in situ reaction zone.

Optionally, in one embodiment, the first delivery unit includes a first injection well connecting the surface and the groundwater, and the second delivery unit includes a second injection well connecting the surface and the groundwater.

Optionally, in one embodiment, the system further comprises a water filtration unit disposed between the target in situ reaction zone and the first permeable reactive wall.

Optionally, in one embodiment, the system further comprises a second permeable reactive wall disposed downstream of the first permeable reactive wall, the second permeable reactive wall being filled with a carbon-based adsorbent material.

Optionally, in one embodiment, the carbon-based adsorption material comprises Ag-based ⁺ Modified carbon-based materials.

Optionally, in one embodiment, the system further comprises a water barrier unit disposed on top of the first permeable reactive wall and the second permeable reactive wall.

Optionally, in one embodiment, the first permeable reactive wall is also filled with clinoptilolite.

The beneficial effects brought by the embodiment of the application are as follows:

by adopting the scheme provided by the embodiment of the application, the underground water treatment system comprises a nitrate removal unit and a first permeable reaction wall; the nitrate removal unit is used for removing nitrate in a target pollution area, the first permeable reactive barrier is arranged downstream of the target pollution area, and the first permeable reactive barrier is filled with iron-based materials. Nitrate in the target polluted area upstream of the first permeable reactive barrier filled with the iron-based material is removed, so that nitrate in groundwater flowing to the first permeable reactive barrier can be greatly reduced, and the removal effect of heavy metals in the groundwater can be improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. In the drawings:

FIG. 1 is a schematic diagram of an underground water treatment system according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of another groundwater treatment system according to an embodiment of the disclosure;

FIG. 3 is a schematic diagram of another groundwater treatment system according to an embodiment of the disclosure;

FIG. 4 is a schematic diagram of another groundwater treatment system according to an embodiment of the disclosure;

fig. 5 is a schematic structural diagram of another groundwater treatment system according to an embodiment of the present application.

Reference numerals:

10-an underground water treatment system; 1011—nutrient solution storage tank; 1012-a first main conveying pipeline; 1013-a first transfer branch; 1014—a first flow meter; 102-a first permeable reactive barrier; 1031-a carbonate storage tank; 1032—a second main conveying line; 1033-a second transfer branch; 1034-a second flowmeter; 104, a water filtering unit; 105-a second permeable reactive barrier; 106-a water-blocking unit; 1061—a barrier hardened layer; 1062-fill layer.

Detailed Description

For the purposes, technical solutions and advantages of the present application, the technical solutions of the present application will be clearly and completely described below with reference to specific embodiments of the present application and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

As described in the background of the present application, groundwater flowing through permeable reactive barriers filled with ferrous materials contains not only heavy metal ions, but often also nitrates. The inventors found that the presence of nitrate tends to result in poor removal of heavy metals from groundwater. Nitrate can influence the oxidation-reduction potential in the groundwater environment on one hand, and further influence the reduction performance of the iron-based material. On the other hand, in the presence of nitrate, a passivation film (such as a passivated ferroferric oxide film formed on the surface of zero-valent iron) is easily formed on the surface of the iron-based material, so that the iron-based material is deactivated.

In view of this, the embodiment of the present application provides a groundwater treatment system 10, which can be used to solve the above-mentioned technical problem that the effect of removing heavy metals in groundwater is poor due to the existence of nitrate. Specifically, as shown in fig. 1, the groundwater treatment system may include a nitrate removal unit and a first permeable reactive wall 102; the nitrate removal unit is used for removing nitrate in a target pollution area A, the first permeable reactive barrier 102 is arranged downstream of the target pollution area A, and the first permeable reactive barrier 102 is filled with iron-based materials.

Wherein the groundwater treatment system 10 may be used for treating various types of wastewater such as groundwater, surface water, and the like. In order to facilitate the explanation of the solution provided in the embodiments of the present application, the following description will take the groundwater treatment object of the groundwater treatment system as an example. In the groundwater layer, groundwater often coexists with the soil, and groundwater flows through pores in the soil.

In the case where the treatment object is groundwater, the target polluted area a may be an area with a high nitrate content located upstream of the groundwater area. The number of target contaminated areas a may be one or more. In the implementation, the nitrate content detection can be performed on the water quality of each area located upstream of the underground water area, and the area with the nitrate concentration larger than the preset threshold value is determined as the target pollution area A. The preset threshold value can be set according to actual conditions.

The first permeable reactive barrier 102 is filled with an iron-based material that can be used to remove heavy metals and organics from the groundwater flowing through the first permeable reactive barrier 102. The iron-based material has reducing performance, and can realize the removal of heavy metals and organic matters by reducing the valence state of the heavy metals and degrading the organic matters. In practical applications, the iron-based material in the first permeable reactive barrier 102 may further fix heavy metals and organic matters in the reactive barrier by adsorption, precipitation, etc., so as to remove the heavy metals and organic matters.

Wherein the iron-based material may include zero valent iron and/or ferrous hydroxide; the zero-valent iron may include iron powder, scrap iron, and the like. The heavy metals that the first permeable reactive wall 102 is capable of removing may include, but are not limited to, manganese, copper, zinc, arsenic, cadmium, lead, and the like.

The nitrate removal unit may be used to remove nitrate in the target contaminated area a. The nitrate removal unit may chemically, biologically, etc. remove nitrate in the target contaminated area a. In the specific implementation, the specific structure and the specific setting position of the nitrate removal unit may be set correspondingly according to the position of the target polluted area a and the specific mode adopted for removing the nitrate in the target polluted area a. For example, the nitrate removal units corresponding to target contaminated area a in groundwater may be different from the nitrate removal units corresponding to target contaminated area a in surface water.

In the embodiment of the present application, the first permeable reactive wall 102 is disposed downstream of the target polluted area a, and it is understood that the groundwater flow direction is from the target polluted area a to the first permeable reactive wall 102 (arrows in fig. 1 may be used to indicate the groundwater flow direction). In addition, while groundwater from the target contaminated area a flows toward the first permeable reactive wall 102, groundwater from various areas located upstream of the groundwater area may flow toward the first permeable reactive wall 102.

Then, the solution provided by the embodiment of the present application may be understood as: providing a first permeable reactive barrier 102 at a location downstream of the groundwater area, determining a target pollution area a in an area upstream of the groundwater area; groundwater flowing in regions upstream of the groundwater area (including target contaminated region a) flows toward the first permeable reactive wall 102. Under the action of the nitrate removal unit, the nitrate content in the target polluted area A is greatly reduced, and the nitrate content in other areas located upstream of the underground water area is originally lower, so that the nitrate in the underground water flowing to the first permeable reactive barrier 102 is greatly reduced.

It will be appreciated that with the groundwater treatment system 10 provided in an embodiment of the application, the groundwater treatment system includes a nitrate removal unit and a first permeable reactive wall 102; the nitrate removal unit is used for removing nitrate in a target pollution area A, the first permeable reactive barrier 102 is arranged downstream of the target pollution area A, and the first permeable reactive barrier 102 is filled with iron-based materials. By removing nitrate in the target contaminated area a upstream of the first permeable reactive barrier 102 filled with the iron-based material, nitrate in groundwater flowing toward the first permeable reactive barrier 102 can be greatly reduced, so that the removal effect of heavy metals in groundwater can be improved.

In addition, the iron-based material is typically filled in the first permeable reactive barrier 102 in the form of individual discrete particles, with groundwater flowing through the pores between the particles. In the presence of nitrate, a passivation film is easily formed on the surface of the iron-based material, and a plurality of particles are inevitably wrapped by the same passivation film at the same time, so that the iron-based material particles in the first permeable reactive barrier 102 are agglomerated, the first permeable reactive barrier 102 is blocked and is difficult to pass through groundwater, and the service life of the first permeable reactive barrier 102 is greatly shortened. In the solution provided in the above embodiment of the present application, nitrate in the groundwater flowing to the first permeable reactive barrier 102 can be greatly reduced by removing nitrate in the target polluted area a upstream of the first permeable reactive barrier 102 filled with the iron-based material, so that the formation of a passivation film can be reduced, the blocking condition of the first permeable reactive barrier 102 is relieved, and the service life of the first permeable reactive barrier 102 is prolonged.

To further alleviate the clogging of the first permeable reactive wall, in one embodiment, the first permeable reactive wall 102 is also filled with clinoptilolite.

Wherein the clinoptilolite may be used to support and disperse an iron-based material.

It will be appreciated that by filling clinoptilolite for supporting and dispersing the iron-based material in the first permeable reactive barrier 102, agglomeration of the iron-based material may be reduced, thereby further alleviating the clogging of the first permeable reactive barrier 102. In addition, clinoptilolite also has an adsorption effect, and can further adsorb and fix heavy metals in the groundwater.

In the above embodiment, to enable the first permeable reactive barrier 102 to have both a better groundwater purification effect and a longer service life, the mass ratio of the iron-based material and clinoptilolite filled in the first permeable reactive barrier 102 may be (1:1) - (3:1).

In addition, to further improve the purification effect of the first permeable reactive barrier 102 on groundwater, the particle size of the iron-based material and the particle size of clinoptilolite may be set to be 3mm or less. In practical application, the particle size of the iron-based material and the particle size of the clinoptilolite can be adjusted according to the groundwater flow speed, specifically: the particle size of the particles may be set to a particle size that enables groundwater having a target flow speed to stay in the first permeable reactive wall 102 for a preset period of time. The target flow rate may be an actual flow rate of groundwater flowing to the first permeable reactive barrier 102, and the preset duration may be a duration required for the iron-based material and clinoptilolite in the first permeable reactive barrier 102 to be able to remove heavy metals and organic matters more fully.

In the above embodiments, it is mentioned that the specific structure and the specific setting position of the nitrate removal unit may be set accordingly according to the position of the target polluted area and the specific manner in which the nitrate in the target polluted area is removed, and the following will provide a specific manner in which the nitrate in the target polluted area a is removed, and a specific nitrate removal unit corresponding thereto:

in one embodiment, the target pollution area A comprises in-situ nitrate-reducing bacteria, and the nitrate removal unit comprises a first conveying unit, wherein the first conveying unit is used for conveying nutrient solution for promoting growth and propagation of the in-situ nitrate-reducing bacteria to the target pollution area A.

Wherein, the in-situ nitrate-reducing bacteria can be understood as nitrate-reducing bacteria originally existing in the water body in the target polluted area, or can be called indigenous nitrate-reducing bacteria. For example, in groundwater environments for mining, smelting and other projects, a large number of nitrate-reducing bacteria are typically present.

The nitrate-reducing bacteria may be used to denitrify nitrate in a target contaminated area. Specifically, the nitrate reducing bacteria can take nitrate as an electron acceptor to gradually reduce nitrogen in the nitrate into nitrogen, and the reduction process is as follows:

NO ₃ ^— →NO ₂ ^— →NO→N ₂ O→N ₂

wherein the nitrate-reducing bacteria may include pseudomonas and the like, and the pseudomonas may include rhodopseudomonas globosa, rhodopseudomonas and the like.

The components of the nutrient solution delivered by the first delivery unit to the target contaminated area A may include, but are not limited to, naCl, mgCl.6H ₂ O、CaCl ₂ ·2H ₂ O、KCl、KH ₂ PO ₄ 、NH ₄ Cl, naAC, etc. In the case that the nutrient solution comprises the above components, in order to make the nutrient solution more favorable for the growth and propagation of in-situ nitrate-reducing bacteria, the concentration of the components can be: 2.5g/L-5.0g/L NaCl, 0.1g/L-0.2g/L MgCl.6H ₂ O, 0.51g/L-1g/L CaCl ₂ ·2H ₂ O, KCl of 1.5g/L-3.0g/L, KH of 0.5g/L-1.0g/L ₂ PO ₄ NH 1.0g/L-1.5g/L ₄ Cl, naAC 1.0g/L-2.0 g/L. In practical application, the in-situ nitrate-reducing bacteria can be extracted from the target pollution area A, cultured to obtain external environmental conditions favorable for growth and propagation of the in-situ nitrate-reducing bacteria, and then the environment of the target pollution area A is controlled to be matched with the external environmental conditions.

When the target contaminated area A is cultured in situ with the in situ nitrate-reducing bacteria, the first delivery unit may deliver the nutrient solution to the target contaminated area A in a 1h/d (delivery one hour per day) injection. In addition, in order to ensure that the in-situ nitrate-reducing bacteria in the target polluted area A can grow and reproduce smoothly, N for 30min can be introduced before the nutrient solution is injected each time ₂ To remove dissolved oxygen in the target contaminated area a and create an anaerobic environment that favors denitrification by nitrate-reducing bacteria.

It can be appreciated that the nutrient solution is conveyed into the target polluted area a by the first conveying unit, so that the in-situ nitrate-reducing bacteria in the target polluted area a can grow and propagate in large quantity, thereby removing more nitrate in the target polluted area a, and further reducing nitrate in the groundwater flowing to the first permeable reactive wall 102. Meanwhile, the embodiment of the application adopts a mode of culturing the original nitrate-reducing bacteria in the target pollution area A, and compared with a mode of introducing exogenous nitrate-reducing bacteria, the method is simpler and more convenient in practical operation and lower in investment cost.

Then, as shown in fig. 1, the first conveying unit adapted to the above-mentioned removal of nitrate by the in-situ nitrate-reducing bacteria in the target contaminated area a may specifically include a nutrient solution storage tank 1011, a first main conveying pipeline 1012 and a plurality of first branch conveying pipelines 1013, wherein the nutrient solution storage tank 1011 may be disposed above the ground surface, an inlet of the first main conveying pipeline 1012 is communicated with an outlet of the nutrient solution storage tank 1011, and the plurality of first branch conveying pipelines 1013 are disposed on the first main conveying pipeline 1012 uniformly along the liquid flow direction in the first main conveying pipeline 1012. The circles in fig. 1 may represent the range of influence of the nutrient solution. A first flow meter 1014 may be further provided on the first main conduit 1012 for controlling the flow of nutrient solution delivered.

In the case where the treatment object of the groundwater treatment system 10 is groundwater, the first transporting unit may further include first injection wells (not shown) connecting the surface and the groundwater, and the number of the first injection wells may be plural. The first injection well may be used to receive the nutrient solution exiting the first transfer branch 1013 and transfer the nutrient solution to the target contaminated area a in the groundwater.

It should be appreciated that the manner in which nitrate is removed from the target contaminated area a by the in situ nitrate-reducing bacteria in the above embodiments is merely one specific example. In practical applications, an exogenous nitrate-reducing bacteria may also be introduced to remove nitrate in the target contaminated area a, and accordingly, the nitrate removal unit may be a permeable reactive barrier filled with the nitrate-reducing bacteria disposed in the target contaminated area a.

Groundwater pollution is often highly complex, often contains iodides, has high mobility and bioaccumulation in the environment, and can cause persistent harm to ecological environment and human health. Thus, in one embodiment, as shown in fig. 2, the groundwater treatment system 10 provided in an example of the application further includes an iodate removal unit for removing iodate from a target in situ reaction zone B disposed between the target contaminated zone a and the first permeable reactive wall 102.

The target in situ reaction zone B is understood to be the zone in which iodate is removed.

Iodate in target in situ reaction zone B may include iodate that is originally present in that zone, and may also include iodate flowing to that zone from upstream target contaminated zone a and other zones.

Then, correspondingly, a target in-situ reaction zone B is disposed between the target contaminated zone and the first permeable reactive wall 102, and in particular, may be disposed at a target location between the target contaminated zone a and the first permeable reactive wall 102, the target location being a location where groundwater in both the upstream target contaminated zone a and other zones can flow through.

The iodate removal unit may be used to remove iodates in the target in situ reaction zone B. The iodate removal unit may chemically, biologically, etc. remove iodates in the target in situ reaction zone B. In a specific implementation, the specific structure and the specific setting position of the iodate removing unit may be set correspondingly according to the position of the target in-situ reaction region B and the specific mode adopted for removing the iodate in the target in-situ reaction region B.

It will be appreciated that with the above-described arrangement, by providing the target in-situ reaction zone B between the target contaminated zone B and the first permeable reactive barrier 102 and providing the iodate removal unit, it is possible to further remove iodide in groundwater, thereby further improving the purification effect of groundwater.

In the above embodiments, it is mentioned that the specific structure and the specific arrangement position of the iodate removing unit may be set accordingly according to the position of the target in-situ reaction region B and the specific manner in which the iodate in the target in-situ reaction region B is removed, and a specific manner in which the iodate in the target in-situ reaction region B is removed and a specific iodate removing unit corresponding thereto will be provided below:

in one embodiment, the nutrient solution comprises a calcium salt solution, and the iodate removal unit comprises a second delivery unit; the second conveying unit is used for conveying carbonate solution to the target in-situ reaction area B.

Wherein the nutrient solution comprises a calcium salt solution, it is understood that the nutrient solution comprising the calcium salt may be delivered when the nutrient solution is delivered to the target contaminated area a by the first delivery unit. And, the calcium salt is excessive and cannot be fully utilized by the in-situ nitrate-reducing bacteria, so that the calcium salt flows from the target pollution area A to the target in-situ reaction area B.

The target in situ reaction zone B also includes a carbonate solution transported by the second transport unit after the calcium salt flows from the target contaminated zone a to the target in situ reaction zone B. Further, in the target in-situ reaction zone B, calcium salt reacts with carbonate to generate calcium carbonate precipitate, IO in iodate ₃ ^— The iodide is fixed or adsorbed in the calcium carbonate precipitate in a coprecipitation form, so that the iodide is removed, and the purification effect on the groundwater is improved.

In particular, the calcium salt may be a soluble calcium salt, such as CaCl, for smooth reaction of the calcium salt with the carbonate ₂ 、C ₁₂ H ₂₂ O ₁₄ Ca, etc.; the carbonate may be K ₂ CO ₃ 、Na ₂ CO ₃ Etc.

Then, as shown in fig. 2, the second transfer unit adapted to the removal of iodate in the target in-situ reaction region B may specifically include a carbonate storage tank 1031, a second main transfer line 1032, and a plurality of second branch transfer lines 1033, where the carbonate storage tank 1031 may be disposed above the ground, and an inlet of the second main transfer line 1032 is connected to an outlet of the carbonate storage tank 1031, and the plurality of second branch transfer lines 1033 are disposed on the second main transfer line 1032 uniformly along a liquid flow direction in the second main transfer line 1032. The circles in fig. 2 may represent the range of influence of the nutrient solution. A second flow meter 1034 may be further provided on the second main transfer line 1032 for controlling the flow rate of the transferred carbonate solution.

In the case where the treatment object of the groundwater treatment system 10 is groundwater, the second transporting unit may further include a second injection well (not shown) connecting the surface and the groundwater, and the number of the second injection wells may be plural. The second injection well may be used to receive the carbonate solution exiting the second transfer main 1032 and transfer the carbonate solution to the target in situ reaction zone B in the groundwater.

It should be understood that the manner in which the iodide in the target in-situ reaction zone B is removed by adding the calcium salt to the nutrient solution and delivering the carbonate solution to the target in-situ reaction zone B by the second delivery unit such that the iodate in the target in-situ reaction zone B forms a co-precipitate with the calcium carbonate in the above embodiment is only one specific example. In practice, the iodate removal unit may also be a permeable reaction wall disposed in the target in situ reaction zone B and filled with a reaction medium capable of removing iodide.

In practical applications, in order to avoid clogging of the first permeable reactive barrier 102 caused by sediment, silt, etc. in the groundwater flowing to the first permeable reactive barrier 102, in one embodiment, the groundwater treatment system 10 provided in this embodiment further includes a water filtering unit 104, as shown in fig. 3, the water filtering unit 104 is disposed between the target in-situ reaction area B and the first permeable reactive barrier 102.

Wherein the water filtering unit 104 may be used to filter sediment, silt, etc. in the groundwater flowing toward the first permeable reactive wall 102. The precipitate may in particular be a precipitate obtained in the target in situ reaction zone B. Because groundwater tends to coexist with soil in the groundwater layer, some silt may be carried with the first permeable reactive wall 102 as the groundwater flows to the first permeable reactive wall.

In the present embodiment, the water filtering unit 104 may be a permeable wall filled with quartz sand.

It will be appreciated that by adopting the above-described scheme, by disposing the water filtering unit between the target in-situ reaction region B and the first permeable reactive barrier 102, sediment, silt, etc. in the groundwater flowing to the first permeable reactive barrier 102 can be filtered, so that the first permeable reactive barrier 102 can be prevented from being blocked.

To further enhance the groundwater treatment effect, in an embodiment, the groundwater treatment system 10 provided in this embodiment further includes a second permeable reactive wall 105, as shown in fig. 4, the second permeable reactive wall 105 is disposed downstream of the first permeable reactive wall 102, and the second permeable reactive wall 105 is filled with a carbon-based adsorbing material.

The second permeable reactive barrier 105 is filled with a carbon-based adsorption material, and can be used for adsorbing and removing pollutants such as fluoride, cyanide, iodide, heavy metal, and the like, which remain in the groundwater flowing from the first permeable reactive barrier 102 to the second permeable reactive barrier 105.

The carbon-based adsorption material can be coal activated carbon, coconut activated carbon and the like.

In particular embodiments, the carbon-based adsorbent material may comprise Ag-based catalyst for further enhancing the effect of the second permeable reactive barrier 105 on the residual iodides in groundwater ⁺ Modified carbon-based material made of Ag ⁺ And generating a precipitate with iodine to further remove the residual iodide in the groundwater.

It can be appreciated that with the above-described scheme, by providing the second permeable reactive barrier 105 filled with the carbon-based adsorbing material downstream of the first permeable reactive barrier 102, various contaminants remaining in the groundwater can be further removed, so that the purification effect of the groundwater can be further improved.

In this embodiment of the present application, in the case where the treatment object of the groundwater treatment system is groundwater, each of the reaction walls in the above embodiment includes a first permeable reaction wall, a second permeable reaction wall, and a permeable wall filled with quartz sand (i.e., a water filtering unit), the construction process may be as follows:

the foundation pit is excavated to the groundwater waterproof bottom plate by adopting a mechanical grab bucket machine, filling materials corresponding to each reaction wall are sequentially downwards arranged by adopting a gravity filling method, and the filling depth is matched with the groundwater level.

For example, after the foundation trench is excavated to the underground water-proof bottom plate, the filling material corresponding to the water filtering unit, the filling material corresponding to the first permeable reactive barrier and the filling material corresponding to the second permeable reactive barrier are sequentially arranged under the foundation trench according to the flow direction of the underground water, so as to form corresponding walls respectively.

In one implementation, the groundwater treatment system 10 provided in an embodiment of the present application further includes a water isolation unit 106, the water isolation unit 106 being disposed on top of the first permeable reactive wall 102 and the second permeable reactive wall 105 as shown in fig. 4.

Wherein, the water isolation unit 106 may be used to prevent rainwater, surface water, etc. from migrating downwards to the first permeable reactive barrier 102 and the second permeable reactive barrier 105, so as to prevent impurities in the rainwater and the surface water from affecting the filling materials and reactions in the first permeable reactive barrier 102 and the second permeable reactive barrier 105.

The water blocking unit 106 may include a barrier hardening layer 1061 and a filler layer 1062 disposed from top to bottom. In a specific implementation, to further improve the barrier effect, the barrier hardening layer 1061 may be a C25 concrete facing layer, and the thickness may be set to 200mm; the fill layer 1062 may be a degree of compaction>95% and permeability coefficient<10 ^-7 Is a clay of the formula (I).

It can be appreciated that by adopting the above scheme, by arranging the water-blocking unit 106 at the top of the first permeable reactive barrier 102 and the second permeable reactive barrier 105, rainwater, surface water and the like can be prevented from migrating and penetrating into the first permeable reactive barrier 102 and the second permeable reactive barrier 105, so that the treatment effect of the first permeable reactive barrier 102 and the second permeable reactive barrier 105 on the groundwater can be ensured.

In a specific embodiment, the object treated by the groundwater treatment system is groundwater, and the groundwater treatment system includes a first conveying unit, a second conveying unit, a water filtering unit 104, a first permeable reactive wall 102, and a second permeable reactive wall 105. The first conveying unit is used for conveying nutrient solution for promoting the growth and propagation of in-situ nitrate-reducing bacteria in the area to the target pollution area A; the second delivery unit is used to deliver the carbonate solution to the target in situ reaction zone B. Wherein the target polluted area a, the target in-situ reaction area B, the water filtering unit 104, the first permeable reactive barrier 102 and the second permeable reactive barrier 105 are sequentially arranged according to the groundwater flow direction.

Through detection, in the groundwater of a certain mining and smelting project, the concentration of each pollutant is as follows: 45.8mg/L of manganese, 3.04mg/L of copper, 14.8mg/L of zinc, 87 mug/L of arsenic, 11.4 mug/L of cadmium, 220 mug/L of lead, 4.3mg/L of fluoride, 0.148mg/L of cyanide, 31.8mg/L of iodide and 1090mg/L of nitrate.

After the groundwater treatment system 10 provided in the above embodiments of the present application is used to treat groundwater, the concentration of each contaminant in the groundwater is: 3mg/L of manganese, 1.5mg/L of copper, 5mg/L of zinc, 50 mug/L of arsenic, 10 mug/L of cadmium, 100 mug/L of lead, 2mg/L of fluoride, 0.1mg/L of cyanide, 1.0mg/L of iodide and 100mg/L of nitrate.

Therefore, by adopting the groundwater treatment system provided by the embodiment of the application, most of pollutants such as heavy metals, fluorides, cyanides, iodides and the like in groundwater can be removed, and the groundwater treatment system has a good purifying effect.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.

The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and changes may be made to the present application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. which are within the spirit and principles of the present application are intended to be included within the scope of the claims of the present application.

Claims

1. A groundwater treatment system, wherein the system includes a nitrate removal unit and a first permeable reactive wall;

2. The groundwater treatment system of claim 1, wherein the target contaminated area includes in situ nitrate-reducing bacteria therein, the nitrate removal unit includes a first delivery unit for delivering a nutrient solution to the target contaminated area that promotes growth and propagation of the in situ nitrate-reducing bacteria.

3. The groundwater treatment system of claim 2, further comprising an iodate removal unit for removing iodate in a target in situ reaction zone disposed between the target contaminated area and the first permeable reactive wall.

4. A groundwater treatment system according to claim 3 wherein the nutrient solution comprises a calcium salt solution and the iodate removal unit comprises a second delivery unit; the second delivery unit is configured to deliver a carbonate solution to the target in situ reaction zone.

5. The groundwater treatment system of claim 4, wherein the first transport unit comprises a first injection well connecting surface and groundwater and the second transport unit comprises a second injection well connecting surface and groundwater.

6. The groundwater treatment system of claim 4, further comprising a water filtering unit disposed between the target in situ reaction region and the first permeable reaction wall.

7. The groundwater treatment system of claim 1, further comprising a second permeable reactive wall disposed downstream of the first permeable reactive wall, the second permeable reactive wall filled with a carbon-based adsorbent material.

8. The groundwater treatment system of claim 7, wherein the carbon-based adsorbent material comprises Ag-based ⁺ Modified carbon-based materials.

9. The groundwater treatment system of claim 7, further comprising a water barrier unit disposed atop the first permeable reactive wall and the second permeable reactive wall.

10. The groundwater treatment system of claim 1 wherein the first permeable reactive wall is further filled with clinoptilolite.