CN104973632A - Soil and underground water landfill leachate pollution in-situ remediation simulation device - Google Patents

Abstract

The invention discloses an in-situ restoration simulation device for landfill leachate pollution of soil and groundwater, which comprises a water inlet pool, a landfill leachate seepage tank, a multi-stage permeable reaction grid, an aquitard, an aquifer, and a water outlet pipe. There are several small holes at the bottom of the leachate seepage tank, and the multi-stage permeable reaction grid is provided with a pollution plume intercepting plate, an opening wall, a sieve plate and connecting pipes, and several outlet pipes are connected at the end of the device. The series number n of the permeable reaction grid is determined according to the physical and chemical characteristics of the landfill leachate and the restoration goal, and n is a natural number. The invention can narrow the gap between the laboratory simulation environment and the actual site remediation environment of soil and groundwater polluted by landfill leachate, and more closely reflect the state of in-situ restoration of landfill leachate pollution in soil and groundwater. The engineering application of leachate pollution in-situ remediation technology provides an objective theoretical reference.

Description

An in-situ remediation simulation device for landfill leachate pollution of soil and groundwater

technical field

The invention relates to a pollution treatment simulation device, in particular to an in-situ repair simulation device for soil and groundwater landfill leachate pollution.

Background technique

Soil and groundwater are precious resources for human survival. Since entering the industrialized society, the pollution of soil and groundwater has appeared, and it began to intensify in the 1960s and 1970s. In view of the seriousness of soil and groundwater pollution, developed countries such as Europe and the United States have invested a lot of manpower and material resources in the research of contaminated soil and groundwater remediation technology. Contaminated soil and groundwater remediation technologies can be divided into ex-situ remediation and in-situ remediation according to different treatment methods.

Commonly used soil pollution ex-situ remediation technology excavates, transfers, stacks, purifies and reuses contaminated soil. This kind of ex-situ remediation not only has high processing costs, but also is difficult to treat deep soil and sites where both soil and groundwater are polluted, and it is impossible to remediate polluted soil under buildings or polluted sites close to important buildings.

Early groundwater remediation employed ex situ treatments, such as pumping treatments. The technology works by capturing polluted plumes in groundwater and pumping them out of the ground, where the water is purified for use or re-introduced into the ground using other treatment techniques. The pumping treatment method can effectively control the polluted area of groundwater upstream of the pumping well, but the application results and research of groundwater treatment on site show that, in order to completely restore the polluted groundwater, the pumping treatment system often needs to be operated for several years or even decades. The cost of power consumption, equipment operation and maintenance required by it is extremely high. In addition, in order to prevent the ground subsidence caused by the large amount of pumping out of groundwater, it is necessary to adopt reverse irrigation technology, which increases the consumption of funds.

Therefore, the in-situ remediation technology of soil and groundwater pollution is currently a hot spot in the research of soil and groundwater pollution control technology. It not only saves the treatment cost, but also reduces the surface treatment facilities and reduces the disturbance to the environment.

The permeable reactive grid is a passive in-situ treatment area filled with reactive materials capable of degrading and retaining contaminated components in groundwater flowing through the wall, thereby achieving remediation purposes. Compared with other in-situ repair technologies, its biggest advantage is that it does not require any external power devices and ground treatment facilities, and the consumption of active reaction medium is very slow, which can effectively exert the repair performance for a long time, except for the initial installation and long-term monitoring to observe the repair effect In addition, there are almost no other costs.

At present, the in-situ remediation technology of soil and groundwater leachate pollution in developed countries such as Europe and the United States is relatively mature and has been put into production and use. However, the research in my country is still in the experimental research stage, and currently mainly includes site application research and laboratory research. Laboratory studies are an essential stage in the evaluation of a remediation technology prior to field application. Most laboratory studies have simulated the movement of contaminated groundwater in the aquifer through column tests and analyzed the removal efficiency of pollutants. However, there is still a large gap between the soil and groundwater in situ remediation environment simulated in this way and the actual environment.

Contents of the invention

In view of the above technical problems, the main purpose of the present invention is to provide a soil and groundwater landfill leachate pollution in-situ restoration simulation device to narrow the gap between the simulated environment and the actual environment for in-situ restoration of contaminated soil and groundwater, and more appropriately Reflecting the status of in-situ remediation of landfill leachate pollution in soil and groundwater, it can provide an objective theoretical reference for the engineering application of in-situ remediation technology of landfill leachate pollution in soil and groundwater.

In order to achieve the above object, the present invention adopts the following technical solutions:

The invention provides an in-situ restoration simulation device for landfill leachate pollution of soil and groundwater. layer and outlet pipe, characterized in that,

The water inlet pool is separated from other parts of the simulation device by a sieve plate, and a high-density nylon screen is stuck on the surface of the sieve plate;

said aquitards and aquifers formed in said simulation device other than an intake basin;

The landfill leachate seepage tank is located at the front end of the simulation device except the water inlet, and the bottom is provided with a number of small holes for the landfill leachate to permeate through;

A plurality of monitoring wells are dispersedly arranged in the simulation device except the water inlet pool, and are used to monitor the simulation device;

Several multi-level permeable reaction grids are arranged on the water flow direction in the simulation device except the water inlet pool, and the multi-level permeable reaction grids are composed of pollution plume intercepting plates, first-stage permeable reaction grids , the second-level permeable reaction grid, until the nth-level permeable reaction grid, wherein the number n of the multi-level permeable reaction grid is determined according to the physical and chemical characteristics of landfill leachate and the restoration target, and n is a natural number ;

Several water outlet pipes are located at the end of the simulation device.

Wherein, the landfill leachate seepage tank is filled with landfill leachate taken from the site, or artificially prepared landfill leachate according to the leachate components.

Wherein, the monitoring well is equipped with online monitoring equipment to dynamically monitor water level, flow rate, temperature, pH, dissolved oxygen, conductivity and redox potential, and sampling tubes are set at different depths of the monitoring well.

Among them, other areas of the simulation device except the water inlet pool are successively upper, middle and lower layers from the top, and the upper and lower layers are filled with clay with a particle size less than 0.25mm to form an aquitard, and the middle layer is filled with Sand particles with a particle size of 0.5 to 2.0 mm form an aquifer.

Wherein the water head height of the water outlet pipe is adjusted according to actual needs.

Wherein, the pollution plume intercepting plate is made of a water-proof material with stable physical and chemical properties, and the pollution plume intercepting plate is sealed and connected with the outer wall of the first-stage permeable reaction grid, and is vertically inserted into the bottom of the aquifer. In the impermeable layer.

Wherein, the first-stage permeable reaction grid is provided with a number of small holes in the curved wall area less than 180° between the pollution plume intercepting plates, and a high-density nylon screen is glued on the surface of the curved wall area net; the rest of the first-stage permeable reaction grid wall is a water-proof material with stable physical and chemical properties;

Two sieve plates are vertically inserted inside the first-stage permeable reaction grid, and the reaction packing is between the sieve plates; and

The whole front-end sieve plate is provided with several small holes, and the bottom third of the rear-end sieve plate is provided with several small holes, and the surface of the sieve plate is glued with a high-density nylon screen.

Wherein, the first-level permeable reaction grid is connected to the subsequent second-level permeable reaction grid through several connecting pipes;

Two sieve plates are vertically inserted inside the second-stage permeable reaction grid, and the reaction filler is between the sieve plates;

The whole of the two sieve plates is provided with some small holes, and the surface of the sieve plates is glued with a high-density nylon screen; and

In the second-stage permeable reaction grid, the rear-end sieve plate corresponds to a number of small holes in the arc-shaped wall area less than 180°, and the surface of the arc-shaped wall area is glued with high-density nylon mesh. The remaining area of the permeable reaction grid wall is a water-proof material with stable physical and chemical properties.

Among them, when the number n of multi-level permeable reaction grids is greater than 2, the second-level permeable reaction grids are used as the last-level grids; two adjacent permeable reaction grids are connected by several connecting pipes; The walls of the permeable reaction grids in the first and last stages are all impermeable materials, and two sieve plates are vertically inserted inside the permeable reaction grids, and the reaction filler is between the sieve plates; A number of small holes are provided, and a number of small holes are provided in the bottom third of the sieve plate at the rear end. The surface of the sieve plate is glued with a high-density nylon screen.

Wherein, the mesh of the high-density nylon mesh is between 200-800 mesh.

Based on the above-mentioned technical scheme, the present invention has the following advantages and beneficial effects: (1) the device of the present invention is simple and ingenious in structure, simple to manufacture, easy to operate, and low in cost; The reaction medium can be adjusted flexibly, and is suitable for research on in-situ remediation technology of groundwater polluted by landfill leachate of different properties; (3) The device of the present invention simulates the in-situ remediation environment of landfill leachate pollution of soil and groundwater, including the hydrology of the vadose zone aquifer Geological characteristics, groundwater seepage conditions, landfill leachate seepage pollution process, and the action form of permeable reaction grids can provide theoretical reference for the engineering application of landfill leachate pollution in-situ remediation technology for soil and groundwater.

Description of drawings

Fig. 1 is the plane view of the pollution in-situ remediation simulation device of the present invention;

Fig. 2 is the A-A sectional view of the pollution in-situ remediation simulation device of the present invention;

Fig. 3 is the 7,8-node diagram of the pollution in-situ remediation simulation device of the present invention;

Fig. 4 is a 9-node diagram of the pollution in-situ remediation simulation device of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The working principle of the pollution in-situ remediation simulation device of the present invention is as follows: the groundwater is injected into the water inlet pool at a certain flow rate, and the water level of the water inlet pool is controlled to simulate the confined water or the submerged aquifer. The landfill leachate is injected into the landfill leachate seepage tank at a certain flow rate, and the leachate seeps into the vadose zone and the aquifer. The groundwater enters the vadose zone and the aquifer from the intake tank in the form of seepage, mixes with the seepage landfill leachate to form a pollution plume, is then intercepted by the reaction grid, and finally flows out from the outlet pipe, thus completing the infiltration of the entire soil and groundwater waste. Simulation process for in situ remediation of filtrate contamination.

More specifically, the present invention discloses an in-situ restoration simulation device for soil and groundwater landfill leachate pollution, as shown in the plan view of FIG. 1 and the A-A section view of FIG. Seepage tank 3, monitoring well 2, pollution plume intercepting plate 4, multi-stage permeable reaction grids 5, 6, aquitard 12, aquifer 13 and outlet pipe 11. Wherein, the permeable reaction grid is provided with an opening wall 7 , sieve plates 8 , 9 and a connecting pipe 10 .

The water inlet pool 1 is separated from other parts of the device by a sieve plate, and the surface of the sieve plate 8-9 is bonded with a high-density nylon screen.

The bottom of the landfill leachate seepage tank 3 is provided with a number of small holes, which are filled with landfill leachate taken from the site, or artificially prepared landfill leachate according to the leachate components.

The monitoring well 2 is equipped with online monitoring equipment to dynamically monitor water level, flow rate, temperature, pH, dissolved oxygen, conductivity and redox potential. Sampling pipes are set at different depths in the monitoring well.

The other areas of the device except for the water inlet tank are divided into upper, middle and lower layers from the top. The upper and lower layers are filled with clay with a particle size of less than 0.25mm, and the middle layer is filled with coarse sand with a particle size of 0.5-2.0mm. .

The end of the device is connected with three water outlet pipes 11, and the height of the water outlet at the end of the water outlet pipeline can be adjusted.

The multi-level permeable reaction grid is composed of the pollution plume intercepting plate 4, the first-level permeable reaction grid 5, the second-level permeable reaction grid 6, and the nth-level permeable reaction grid. The number of stages of the multi-stage permeable reaction grid is determined according to the physical and chemical characteristics of the landfill leachate and the restoration goal.

The pollution plume intercepting plate 4 is made of a water-proof material with stable physical and chemical properties. The intercepting plate is sealed and connected with the outer wall of the first-stage permeable reaction grid, and vertically inserted into the aquitard at the bottom of the aquifer.

The first-stage permeable reaction grid 5 is provided with a number of small holes in the arc wall area less than 180° between the pollution plume intercepting plates, and the surface of this area is glued with high-density nylon mesh; the remaining areas of the grid wall are stable in physical and chemical properties waterproof material. Two sieve plates 8-9 are vertically inserted into the first-stage permeable reaction grid, and the reaction filler is between the sieve plates; 8 are provided with some small holes as a whole, and some small holes are established in the bottom third of the rear-end sieve plate 9, and the surface of the sieve plate is bonded with high-density nylon screen.

The primary permeable reaction grid 5 is connected to the subsequent secondary permeable reaction grid 6 through three connecting pipes 10 . Two sieve plates 9 are vertically inserted inside the second-stage permeable reaction grid, and the reaction filler is between the sieve plates; several small holes are provided on the two sieve plates as a whole, and high-density nylon screens are stuck on the surface of the sieve plates. In the second-stage permeable reaction grid, a number of small holes are set in the area of the arc wall less than 180° corresponding to the rear sieve plate, and the surface of this area is glued with high-density nylon screen; the rest of the grid wall is water-proof with stable physical and chemical properties. Material.

When the number of stages of the multi-level permeable reaction grid is greater than 2, the second-level permeable reaction grid 6 is used as the last level of the grid. Adjacent two-stage permeable reaction grids are connected by three connecting pipes 10 . The grid walls between the first level and the last level are all impermeable materials, and two sieve plates 8-9 are vertically inserted inside the grid, and the reaction filler is between the sieve plates; A number of small holes are arranged in the bottom third of the sieve plate 9 at the rear end, and a high-density nylon screen is stuck on the surface of the sieve plate.

In the present invention, the other areas of the device except the water inlet pool are successively upper, middle and lower layers from the top, and the upper and lower layers are filled with clay with a particle size less than 0.25 mm, respectively simulating the aquitard with a smaller permeability coefficient 12 (air-entrained zone and waterproof bottom plate); the middle layer is filled with coarse sand with a particle size of 0.5-2.0mm, simulating an aquifer with a large permeability coefficient 13, and the aquifer is arranged unevenly along the gradient, so as to be closer to the actual site Aquifer characteristics.

Holes are evenly distributed on the wall and sieve plate with a hole diameter of 3-5mm and a hole spacing of 5-10mm; the surface of the hole wall and the sieve plate is glued with a nylon screen with a hole diameter of 200-800 mesh. The main function of the open-hole wall and sieve plate with nylon mesh is to prevent clay and coarse sand from entering the water tank and the reaction grid, and to prevent the reaction medium such as filler in the reaction grid from entering the aeration zone and the aquifer.

Different types of reactive fillers are added to the reaction grid, and the number of stages of the reaction grid and the type of reactive filler are determined by the physical and chemical characteristics of landfill leachate and the restoration target. The main function of the reaction grid is to use active media to remediate groundwater contaminated by landfill leachate.

In the present invention, the height of the water outlet of the water outlet pipe is adjustable, thereby adjusting the water level of the water inlet pool. When the water level of the inlet pond is higher than the top of the aquifer, the confined water level 14 is simulated; when the water level of the inlet pond is lower than the top of the aquifer, the diving water level 15 is simulated.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

Claims (10)

1. soil and a underground water Landfill Leachate Pollution in-situ immobilization simulator, described simulator comprises pump sump, percolate seepage groove, monitor well, multistage permeable reactive barrier, aquitard, waterbearing stratum and rising pipe, it is characterized in that,

The other parts of described pump sump and described simulator use sieve plate to separate, and described floor lever of sieve tray is stained with high-density nylon screen;

Described aquitard and waterbearing stratum, be formed in the described simulator except pump sump;

Described percolate seepage slot, in the front end of the described simulator except pump sump, is provided with some apertures, penetrates through for percolate bottom it;

Multiple monitor well, dispersed placement in the described simulator except pump sump, for monitoring described simulator;

Some multistage permeable reactive barriers, be arranged in the water (flow) direction in the described simulator except pump sump, described multistage permeable reactive barrier by Pollution Plume catching sheet, first step permeable reactive barrier, second stage permeable reactive barrier until n-th grade of permeable reactive barrier forms, the progression n of wherein said multistage permeable reactive barrier determines according to percolate physicochemical characteristic and reparation target, and n is natural number;

Some rising pipes, are positioned at the end of described simulator.

2. soil as claimed in claim 1 and underground water Landfill Leachate Pollution in-situ immobilization simulator, be marked with the percolate taken from on-the-spot percolate or manually prepare according to percolate composition in wherein said percolate seepage groove.

3. soil as claimed in claim 1 and underground water Landfill Leachate Pollution in-situ immobilization simulator, on-line monitoring equipment is provided with in wherein said monitor well, dynamic monitoring water level, flow velocity, temperature, pH, dissolved oxygen, specific conductivity and redox potential, described monitor well different depths place is provided with stopple coupon.

4. soil as claimed in claim 1 and underground water Landfill Leachate Pollution in-situ immobilization simulator, other region of described simulator wherein except pump sump is followed successively by upper, middle and lower-ranking from top, the clay that upper and lower two-layer filling particle diameter is less than 0.25mm forms aquitard, and middle layer is filled with the grains of sand formation waterbearing stratum that particle diameter is 0.5 ~ 2.0mm.

5. soil as claimed in claim 1 and underground water Landfill Leachate Pollution in-situ immobilization simulator, the head height of wherein said rising pipe regulates according to actual needs.

6. soil as claimed in claim 1 and underground water Landfill Leachate Pollution in-situ immobilization simulator, wherein said Pollution Plume catching sheet is made up of the water proof material that physicochemical property are stable, described Pollution Plume catching sheet and described first step permeable reactive barrier outer wall are tightly connected, and in the vertical described aquitard inserted bottom waterbearing stratum.

7. soil as claimed in claim 6 and underground water Landfill Leachate Pollution in-situ immobilization simulator, the arc wall area that be less than 180 ° of wherein said first step permeable reactive barrier between described Pollution Plume catching sheet is provided with some apertures, and described arc wall region surface is stained with high-density nylon screen; All the other regions of described first step permeable reactive barrier wall are the water proof material that physicochemical property are stable;

Described first step permeable reactive barrier internal vertical inserts two pieces of sieve plates, is reaction filler between described sieve plate; And

Front end sieve plate entirety is provided with some apertures, and bottom the sieve plate of rear end, 1/3rd regions are provided with some apertures, and described floor lever of sieve tray is stained with high-density nylon screen.

8. soil as claimed in claim 7 and underground water Landfill Leachate Pollution in-situ immobilization simulator, wherein said first step permeable reactive barrier is connected by several pipe connectings with follow-up second stage permeable reactive barrier;

Described second stage permeable reactive barrier internal vertical inserts two pieces of sieve plates, is reaction filler between described sieve plate;

Sieve plate entirety described in two pieces is equipped with some apertures, and described floor lever of sieve tray is stained with high-density nylon screen; And

What in the permeable reactive barrier of the described second stage, rear end sieve plate was corresponding be less than 180 ° of arc wall area is provided with some apertures, described arc wall region surface is stained with high-density nylon screen, and all the other regions of described second stage permeable reactive barrier wall are the water proof material that physicochemical property are stable.

9. soil as claimed in claim 8 and underground water Landfill Leachate Pollution in-situ immobilization simulator, wherein when multistage permeable reactive barrier progression n is greater than 2, uses second stage permeable reactive barrier as last step grid; Adjacent two-stage permeable reactive barrier is connected by several pipe connectings; Permeable reactive barrier wall between the first step and last step is impervious materials, and described permeable reactive barrier internal vertical inserts two pieces of sieve plates, is reaction filler between described sieve plate; Front end sieve plate entirety is provided with some apertures, and bottom the sieve plate of rear end, 1/3rd regions are provided with some apertures, and described floor lever of sieve tray is stained with high-density nylon screen.

10. soil as claimed in claim 9 and underground water Landfill Leachate Pollution in-situ immobilization simulator, the mesh of wherein said high-density nylon screen is between 200-800 order.