CN115401062A

CN115401062A - Be used for prosthetic electronic caisson reaction unit of groundwater and soil

Info

Publication number: CN115401062A
Application number: CN202211076233.0A
Authority: CN
Inventors: 廖译嘉; 王琪; 白雪; 袁开; 伍程程; 张亚玲; 谢鹏; 林匡飞
Original assignee: East China University of Science and Technology
Current assignee: East China University of Science and Technology
Priority date: 2022-09-05
Filing date: 2022-09-05
Publication date: 2022-11-29

Abstract

The invention discloses an electric caisson reaction device for repairing underground water and soil, which comprises a sinking well, a caisson reactor and a pulse system, wherein the caisson reactor and the pulse system are arranged in the sinking well; the sinking well is arranged below the ground and is arranged along the flow direction of the underground water; a plurality of caisson reactors are arranged in the lower open caisson, and a reduction unit, an oxidation unit and an adsorption unit are arranged in each caisson reactor through partition plates; each partition plate is provided with a sieve pore which is beneficial to liquid phase migration; the pulse system forms an electric field, and the caisson reactor is placed in the electric field. The invention utilizes a pulse system to form a stable electric field, and accelerates the migration rate of pollutants in the lower open caisson; the sinking well has simple structure construction and low cost; and the disturbance to the polluted site is small, and the original soil layer structure and hydrogeological conditions can not be changed.

Description

Electric caisson reaction device for repairing underground water and soil

Technical Field

The invention relates to the technical field of soil and underground water in-situ remediation, in particular to an electric caisson reaction device for underground water and soil remediation.

Background

The soil system is one of the major ecosystems upon which humans rely for survival and development. In recent years, with the development of industrialization and the progress of urbanization, many industrial enterprises originally near the urban area are reformed and moved, and many industrial sites are left, and the sites have different degrees of pollution. If the repair is not carried out in time, on one hand, the land is idle, and resources are wasted, and on the other hand, the diffusion of pollutants in the field can harm the body health of surrounding residents. Therefore, the development of soil and groundwater remediation technologies is imminent. Migration and diffusion of pollutants after entering soil are influenced by soil heterogeneity, the pollutants are unevenly distributed in the soil, and the pollutants are difficult to remove from the soil due to the adsorption capacity of the soil. The natural causes of the soil are different, so that the soil layers are complicated to distribute. Meanwhile, the water flow in the soil saturation zone is influenced by the topography and soil properties, the flow direction is complex, the flow speed is slow, and the soil and underground water pollution is difficult to find and control.

At present, the soil and groundwater remediation technology can be divided into in-situ remediation and ex-situ remediation, wherein the ex-situ remediation is to excavate all polluted soil and groundwater and then send the polluted soil and groundwater into responsive remediation equipment, and the in-situ remediation is to carry out in-situ remediation on a polluted land by using the characteristics of the remediation technology under the condition of disturbing the soil and groundwater as little as possible. Compared with ex-situ remediation, the in-situ remediation has the characteristics of low cost, small disturbance to soil, small secondary pollution, simple construction and the like.

Currently, common in situ repair techniques include: the raw materials include evaporation extraction, in-situ solidification/stabilization, in-situ bioremediation, in-situ chemical oxidation, permeable reactive barrier and the like. The permeable reactive barrier PRB technology is concerned by a large number of scholars at home and abroad due to the fact that engineering facilities are simple, later operation and maintenance costs are low, reaction media are consumed slowly, and the permeable reactive barrier PRB technology has processing capacity of several years or even dozens of years. The PRB technology is characterized in that a reaction wall vertical to the water flow direction of underground water is arranged on the cross section of an underground water flowing path of an underground water pollution area, the underground water of a polluted area is driven to pass through the reaction wall through a natural hydraulic gradient, and a series of physical and chemical reactions are carried out to convert pollutants into another form acceptable to the environment or enable the concentration of the pollutants to reach the environmental standard. The current important reason for restricting the application of PRB technology is its driving force is insufficient. The reactive driving force of the PRB technology depends on the natural hydraulic gradient of underground water, so that in areas with flat terrain or complicated underground water flow direction, pollutants are difficult to be completely intercepted by a reactive wall, and the repair efficiency is low, and the repair time is long. The electric coupling infiltration reaction wall is a novel green technology, an electric field is added on the basis of PRB, underground pollutants are directionally migrated to the reaction wall through electrodialysis, electromigration and electrophoresis, so that the pollutants can better participate in a series of reactions in the reaction wall, and finally the repair treatment of soil underground water is finished. The power supply parameter of the pulse power supply is higher, the energy is more concentrated, and the pulse power supply can act in a short time, so that the pulse power supply is selected as a pollutant migration mode.

The caisson type reaction wall is a new form of a permeable reaction wall combination proposed on the basis of PRB; therefore, it is highly desirable to design an electric caisson reaction apparatus for groundwater and soil remediation.

Disclosure of Invention

The invention aims to provide an electric caisson reaction device for groundwater and soil remediation, which solves the problems in the prior art, can realize that passive remediation of a permeable reaction wall is changed into active remediation, and reduces maintenance cost by using a caisson reactor.

In order to achieve the purpose, the invention provides the following scheme: the invention provides an electric caisson reaction device for repairing underground water and soil, which comprises a sinking well, a caisson reactor and a pulse system, wherein the caisson reactor and the pulse system are arranged in the sinking well;

the sinking well is arranged below the ground and is arranged along the flow direction of underground water;

a plurality of caisson reactors are arranged in the sinking well, and reduction units, oxidation units and adsorption units are arranged in the caisson reactors through partition plates; each partition plate is provided with a sieve pore which is favorable for liquid phase migration;

the pulse system forms an electric field within which the caisson reactor is placed.

The sinking well comprises an injection well and a horizontal well; the horizontal well is arranged in a saturation zone of soil; the two ends of the horizontal well are fixedly connected with the bottom of the injection well; the top of the injection well is arranged on the bottom surface.

And a well cover is arranged on the top surface of the injection well.

The horizontal well adopts a polyethylene screen pipe, and is used for supporting a structure and enabling underground water to permeate into the caisson reactor.

The pulse system comprises an anode plate, a cathode plate and a pulse power supply; the anode plate and the cathode plate are respectively arranged at two ends of the horizontal well and are electrically connected with the pulse power supply; and water holes are formed in the anode plate and the cathode plate.

The caisson is characterized in that a sliding rail is fixedly installed in the caisson, and the caisson reactor is arranged on the sliding rail in a sliding mode.

The caisson reactor is of a cylindrical structure, and the partition plates are also fixedly arranged on two end faces of the caisson reactor; the partition board is provided with a plurality of sieve pores with the diameter of 8-12 mm.

The reaction medium of the reduction unit is nano zero-valent iron.

The reaction medium of the oxidation unit is calcium peroxide.

The reaction medium of the adsorption unit is nitrogen modified biochar.

The invention discloses the following technical effects: (1) The invention adopts an active repair technology, and utilizes a pulse system to form a stable electric field to accelerate the migration rate of pollutants in a reaction well. The traditional permeable reactive barrier is a passive repair technology and depends on the flow of underground water, but the flow of the underground water is complex, slow and unfixed, so that the repair effect is greatly influenced by environmental factors. The invention provides a stable electric field, which can enable pollutants to flow along the horizontal well direction without being influenced by the flow direction and the flow speed of underground water, and has high restoration efficiency and low cost.

(2) The sinking well structure adopted by the invention is simple in construction and low in cost; and the disturbance to the polluted site is small, and the original soil layer structure and hydrogeological conditions can not be changed.

(3) This caisson reactor adopts nested formula slide rail design, and its inside reaction unit can simply be changed, can adjust different adjustment reaction unit's order moreover, and different reaction agent can be changed in a flexible way to reaction unit inside, can save the cost of construction many times, reduces the maintenance cost.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic view of the overall structure;

FIG. 2 is a schematic perspective view of a caisson reactor;

wherein, 1, sinking the open caisson; 2. a well cover; 3. a caisson reactor; 4. an anode plate; 5. a cathode plate; 6. a horizontal well; 7. a partition plate; 8. a slide rail.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description thereof.

The invention provides an electric caisson reaction device for repairing underground water and soil, which comprises a lower caisson 1, a caisson reactor 3 and a pulse system, wherein the caisson reactor 3 and the pulse system are arranged in the lower caisson 1;

the lower open caisson 1 is arranged below the ground and along the flow direction of underground water;

a plurality of caisson reactors 3 are arranged in the lower open caisson 1, and reduction units, oxidation units and adsorption units are respectively arranged in the caisson reactors 3 through partition plates 7; each partition plate 7 is provided with a sieve pore which is beneficial to liquid phase migration;

the pulse system forms an electric field in which the caisson reactor 3 is placed.

In an embodiment of the invention, the caisson reactor 3 is a box structure, reaction walls for adsorbing different reaction media are arranged in the box, a single box or a plurality of box structures in series connection can be selected according to the size of a polluted site, and the caisson type reaction walls can also better treat underground water and remove pollutants according to the complexity of the flow direction of the underground water.

Furthermore, the reaction media in each reaction unit in the caisson reactor 3 can be freely combined so as to be convenient for dealing with different soil and underground water pollution conditions.

Further, the caisson reactor 3 shown in the figure comprises 3 reaction units which are not fixed, the reaction units are divided into an adsorption unit, a reduction unit and an oxidation unit according to functions, 1 reaction unit or a plurality of reaction units can be placed in the caisson reactor, and the reaction units can be freely combined in sequence, such as adsorption-oxidation-reduction, oxidation-adsorption-reduction, reduction-oxidation-adsorption and the like, wherein the specific sequence is determined according to the actual soil and groundwater pollution conditions.

The lower open caisson 1 comprises an injection well and a horizontal well 6; the horizontal well 6 is arranged in a saturation zone of soil; the two ends of the horizontal well 6 are fixedly connected with the bottom of the injection well; the top of the injection well is arranged on the bottom surface.

In one embodiment of the invention, the injection wells are arranged vertically and the horizontal wells 6 provide space for the caisson reactor 3 to facilitate the reaction exchange of the groundwater.

The top surfaces of the two injection wells are provided with well covers 2.

The horizontal well 6 is a polyethylene screen pipe for supporting the structure while allowing groundwater to permeate into the caisson reactor 3.

The pulse system comprises an anode plate 4, a cathode plate 5 and a pulse power supply; the anode plate 4 and the cathode plate 5 are respectively arranged at two ends of the horizontal well 6 and are electrically connected with the pulse power supply; the anode plate 4 and the cathode plate 5 are both provided with water holes.

In one embodiment of the invention, the anode plate 4 and the cathode plate 5 are fixed at two ends of the horizontal well 6, and pulse current is connected to the two ends of the horizontal well, so that pollutants in underground water are transferred from the anode to the cathode under the action of the current through the action of electrodialysis, electrophoresis and electromigration, a stable electric field is formed in the reaction well, the speed of water flow passing through the caisson reactor can be increased, and the repairing effect is enhanced. Water holes with the diameter of 1mm are uniformly distributed on the anode plate 4 and the cathode plate 5 to ensure that the underground water passes through at a constant speed to form stable water flow.

A slide rail 8 is fixedly arranged in the lower open caisson 1, and the caisson reactor 3 is arranged on the slide rail 8 in a sliding way.

The caisson reactor 3 is of a cylindrical structure, and the two end faces of the caisson reactor 3 are also fixedly provided with the partition plates 7; the clapboard 7 is provided with a plurality of sieve holes with the diameter of 8-12 mm.

The reaction medium of the reduction unit is selected from nano zero-valent iron.

In one embodiment of the invention, the nanoscale zero-valent iron is obtained by dropwise adding a sodium borohydride solution into a ferrous sulfate solution in a nitrogen atmosphere, slowly stirring and filtering.

Preferably, the concentration of ferrous sulfate used in the preparation process of the nano zero-valent iron is 0.2-0.5mol/L, and the molar concentration ratio of sodium borohydride to ferrous sulfate is 1:3-1:5, the dropping rate is 5-10ml/min.

The reaction medium of the oxidation unit is calcium peroxide.

In one embodiment of the invention, the calcium peroxide is obtained by dropwise adding hydrogen peroxide into a calcium oxide solution, adding a hydrochloric acid solution with a certain concentration, and slowly stirring and filtering.

Preferably, the proportion of the calcium peroxide in the calcium oxide solution used in the preparation process of the calcium peroxide is 0.5% -1%, and the proportion of the hydrogen peroxide and the calcium oxide solution is 2:1-3:1, the concentration of the hydrochloric acid is 15-20%.

The reaction medium of the adsorption unit is nitrogen modified biochar.

In one embodiment of the invention, the nitrogen modified biochar is obtained by mixing straw and urea and then burning the mixture under an oxygen-free condition.

Preferably, the mass ratio of the straw to the urea used in the preparation process of the nitrogen modified biochar is 1:5-1:10, the firing temperature is 600-800 ℃, and the firing time is 1-2 hours.

In one embodiment of the invention, the soil in the field left after the relocation of a certain dyeing plant has red, blue, orange and the like, and serious pollution conditions exist. After investigation, the soil and underground water in the field are seriously polluted, and the main pollutant is naphthalene sulfonic acid dye. After hydrogeological investigation, the area belongs to a alluvial plain, the terrain is flat, a water system is developed, the flow rate of underground water flowing to the area is complex and slow, the amount of clay in soil is large, and the permeability is poor. The sinking well structure is adopted to repair soil and underground water. According to the soil pollution condition, arranging a sinking well structure in a plurality of areas with serious soil pollution, arranging 2-3 sinking wells along the flow direction of underground water, wherein the diameter of an injection well of each sinking well is 1m, the length of an internal horizontal well is 5-10m, respectively filling a reduction unit, an oxidation unit and an adsorption unit into a caisson reactor 3 (the caisson reactor 3 is a cylinder with the diameter of 0.9m and the length of 0.5 m), wherein the reaction medium of the reduction unit is the nano zero-valent iron, the reaction medium of the oxidation unit is the calcium peroxide, and the reaction medium of the adsorption unit is the nitrogen modified biochar. Then, the reduction unit, the oxidation unit and the adsorption unit are sequentially conveyed into the horizontal well 6 by a slide rail along the water flow direction, and the underground water is ensured to sequentially pass through the reduction unit, the oxidation unit and the adsorption unit. Each horizontal well is sequentially provided with 3 reduction units, 3 horizontal units and 3 adsorption units.

And (3) utilizing a directional horizontal drilling technology in an area where the lower sunk well is arranged, driving the drill bit into the ground, adjusting the direction, drilling along the flow direction of the ground water, and then drilling from the other end to form a sunk well structure. The horizontal well 6 is then pre-installed on the drill bit, and the horizontal well 6 has been installed inside the lower open caisson as the drill bit is retracted. The high density polyethylene screen is then cased into the ground down the injection well. And finally, arranging electrode plates at two ends of the horizontal well 6 by using a drill, wherein the electrode plates are circular iron nets with the diameter of 1.2m, the upstream of the underground water is an anode plate 4, and the downstream of the underground water is a cathode plate 5, and the electrode plates are connected with a pulse power supply, the voltage of the pulse power supply is 0-50V, and the current of the pulse power supply is 0-3A.

Groundwater can enter the horizontal well 6 through the screen pipe of the injection well wall, and under the effect of the stable electric field, pollutants in the groundwater can move into the caisson reactor 3 along with the acceleration of water flow, and the pollutants pass through the reduction unit, the oxidation unit and the adsorption unit in the caisson reactor 3 in sequence, and all pollutants are removed. Meanwhile, a part of reducing medium and oxidizing medium can enter a horizontal well along with water flow, diffuse out of the horizontal well and enter soil, and remove pollution in the soil. The groundwater that has passed through the caisson reactor 3 will flow out of the horizontal well 6 with the groundwater.

And sampling and detecting the underground water in the repair area at intervals, and analyzing the result. And the reaction medium inside the caisson reactor is replaced within a prescribed time, a new caisson reactor is fed into the parallel pipe along the slide rail 8 of the injection well wall, and the old caisson reactor is withdrawn in the other direction.

And (5) detecting the soil and the underground water in the field again through a 6-month restoration process. The contents of the naphthalene sulfonic acid dyes in the soil and the underground water in the field are respectively reduced by 85.2 percent and 95.8 percent. Meanwhile, the groundwater color was found to change from red or blue to colorless.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. The utility model provides an electronic caisson reaction unit for groundwater and soil remediation which characterized in that includes: the device comprises a lower open caisson (1), a caisson reactor (3) arranged in the lower open caisson (1) and a pulse system;

the lower open caisson (1) is arranged below the ground and is arranged along the flow direction of underground water;

a plurality of caisson reactors (3) are arranged in the lower open caisson (1), and reduction units, oxidation units and adsorption units are respectively arranged in the caisson reactors (3) through partition plates (7); each partition plate (7) is provided with a sieve pore which is beneficial to liquid phase migration;

the pulse system forms an electric field in which the caisson reactor (3) is placed.

2. An electric caisson reaction apparatus for groundwater and soil remediation, according to claim 1, wherein: the sunk well (1) comprises an injection well and a horizontal well (6); the horizontal well (6) is arranged in a saturation zone of soil; the bottom of the injection well is fixedly connected with the two ends of the horizontal well (6); the top of the injection well is arranged on the bottom surface.

3. An electro caisson reaction apparatus for groundwater and soil remediation from claim 2, wherein: and the top surface of the two injection wells is provided with a well cover (2).

4. An electric caisson reaction apparatus for groundwater and soil remediation, according to claim 2, wherein: the horizontal well (6) adopts a polyethylene screen pipe, and is used for supporting a structure and enabling underground water to permeate into the caisson reactor (3).

5. An electric caisson reaction apparatus for groundwater and soil remediation, according to claim 2, wherein: the pulse system comprises an anode plate (4), a cathode plate (5) and a pulse power supply; the anode plate (4) and the cathode plate (5) are respectively arranged at two ends of the horizontal well (6) and are electrically connected with the pulse power supply; and water holes are formed in the anode plate (4) and the cathode plate (5).

6. An electro caisson reaction apparatus for groundwater and soil remediation from claim 1, wherein: the caisson is characterized in that a sliding rail (8) is fixedly installed in the lower caisson (1), and the caisson reactor (3) is arranged on the sliding rail (8) in a sliding manner.

7. An electro caisson reaction apparatus for groundwater and soil remediation from claim 1, wherein: the caisson reactor (3) is of a cylindrical structure, and the partition plates (7) are also fixedly arranged on two end faces of the caisson reactor (3); the partition plate (7) is provided with a plurality of sieve holes with the diameter of 8-12 mm.

8. An electro caisson reaction apparatus for groundwater and soil remediation from claim 1, wherein: the reaction medium of the reduction unit is nano zero-valent iron.

9. An electric caisson reaction apparatus for groundwater and soil remediation, according to claim 1, wherein: the reaction medium of the oxidation unit is calcium peroxide.

10. An electric caisson reaction apparatus for groundwater and soil remediation, according to claim 1, wherein: the reaction medium of the adsorption unit is nitrogen modified biochar.