CN107755415B - Device for repairing heavy metal contaminated soil and repairing method thereof - Google Patents

Abstract

The invention discloses a device and a method for restoring heavy metal contaminated soil, wherein the device comprises a rack and a container which is positioned below the rack, is used for containing contaminated soil and is provided with an opening at the top, an electric driving device for driving earthworms in the soil to the surface layer of the soil is arranged in the container, and a throwing device for throwing the earthworms into the container and a collecting device for collecting the earthworms which are driven to the surface layer of the soil are sequentially arranged above the container from top to bottom. According to the invention, by arranging the feeding device, the electric driving device and the collecting device and matching with the corresponding repairing method, clean earthworms are fed into the polluted soil, and the earthworms which are saturated and adsorbed with a large amount of heavy metal pollutants are stripped from the polluted soil, so that the heavy metal pollutants in the polluted soil are completely removed through multiple rounds of operations, and the repairing effect is obviously improved.

Description

Device for repairing heavy metal contaminated soil and repairing method thereof

Technical Field

The invention relates to the technical field of environmental protection, in particular to a device and a method for repairing heavy metal contaminated soil.

Background

The remediation of the heavy metal contaminated soil is a worldwide problem and is also a relatively urgent work. The repair techniques commonly used today include physicochemical and biological repair; wherein, the physical and chemical remediation comprises an electrokinetic remediation technology and a soil leaching technology, and the biological remediation comprises an animal remediation technology and a plant remediation technology.

The electric restoration technology is characterized in that a low-voltage direct current electric field is added into polluted soil, and the actions of electromigration, electrodialysis, electrophoresis and the like are generated under the action of low-strength direct current, so that pollutants on the surface layer of soil particles are desorbed with the soil and are directionally migrated, and the pollutants are degraded or removed in the migration process. Soil leaching technology, especially chemical leaching, refers to excavating polluted soil, washing the soil with water or a reagent solution, removing pollutants, then treating the washing wastewater or waste liquid containing the pollutants, and the clean soil can be backfilled or transported to other places for recycling. Animal and plant remediation refers to the absorption of various pollutants in contaminated soil by a remediating animal or a remediating plant to strip the pollutants from the contaminated soil.

At present, the invention and creations related to the device for repairing the heavy metal contaminated soil by adopting a physical and chemical repairing mode are more, for example:

The invention patent document with application publication number CN203875109U discloses equipment for repairing heavy metal contaminated soil, which comprises a tank body, wherein the top of the tank body is connected with a tank cover through a bolt, the tank cover is provided with an air vent, a support is arranged on the tank cover, a spray nozzle and a motor are fixedly arranged on the support, the spray nozzle penetrates through the tank cover and extends into the tank body, and a stirring blade is also arranged in the tank body and connected with the motor; the tank body is internally provided with two electrodes which are respectively connected with a direct current power supply, the electrodes are also respectively connected with an adsorption cavity, and the bottom of the tank body is provided with a discharge hole. The invention can realize the separation of heavy metals from soil, improve the soil and improve the efficiency of the soil remediation work of the whole field.

However, there are few devices designed specifically for animal remediation of heavy metal contaminated soil. Therefore, in order to further restore the effect of animals on the restoration of heavy metal contaminated soil, it is necessary to design a device and a method for specially performing an animal restoration method.

Disclosure of Invention

The invention provides a device and a method for repairing heavy metal contaminated soil, which are used for completely removing heavy metal pollutants in the contaminated soil and remarkably improving the repairing effect by adding clean earthworms into the contaminated soil and stripping the earthworms which are saturated and adsorbed with a large amount of heavy metal pollutants from the contaminated soil.

The utility model provides a device for repairing heavy metal contaminated soil, includes the frame and is located the frame below and is used for holding contaminated soil and open-top's container, be equipped with in the container and be arranged in driving the earthworm in soil to the device of driving that drives of electricity on soil top layer, the top-down of container be equipped with in proper order be used for to put in the container clean earthworm the input device and be used for collecting the collection device who is driven to the saturation adsorption heavy metal earthworm on soil top layer.

Experiments show that when the voltage is 3-9V (including 3V and 9V), the earthworm repellent can repel adult earthworms and does not react with young earthworms; when the voltage is 9V-15V (9V and 15V are not included), the earthworm repellent can repel adult earthworms, but can affect the growth of young earthworms; and when the voltage is less than 3V, the effect of driving the adult earthworms is not obvious.

The clean earthworms thrown into the polluted soil can adsorb heavy metals in the soil in the feeding process, a large amount of heavy metal pollutants are carried in the earthworms along with the progress of the soil remediation process, the earthworms reach the peak after the earthworms grow up, and the absorption capacity of the earthworms growing up to the heavy metals in the soil is obviously reduced. If the adult earthworms can be driven out of the soil, and a batch of new clean earthworms are put in again, the earthworms can be absorbed and transferred out of the soil in batch, the heavy metal absorption capacity of the earthworms in the soil is effectively improved, and the purpose of taking the heavy metals in the soil away from the polluted soil is finally achieved. Clean earthworms refer to young earthworms that do not contain heavy metals in their bodies.

The voltage control that will drive the device electrically drives is between 3 ~ 9V, can drive adult earthworm to the soil top layer (soil surface 0 ~ 1cm department), and collection that the rethread collection device carries out adult earthworm to throw in new clean earthworm through throwing in the device again, can realize the continuous cycle of soil and restore.

Preferably, a spraying device for spraying the chemical agent solution to the contaminated soil in the container is arranged above the dosing device. Before animal remediation, the soil is sprayed, so that the effective state of soil heavy metal can be improved, the heavy metal absorption capacity of the earthworms in the soil can be effectively improved, and the animal adsorption effect can be enhanced.

Preferably, the container is fixed with the spraying device, the throwing device and the collecting device through the rack; the rack consists of a support rod and a cross rod;

the supporting rod is vertically arranged on the edge of the top wall of the container; the cross rods are arranged between every two adjacent supporting rods and are horizontally arranged; the horizontal pole sets up for the multilayer, and the top layer horizontal pole is connected with spray set, and the middle level horizontal pole is connected with the input device, and the low level horizontal pole is connected with collection device. The device can be integrated by arranging the frame, and is beneficial to installation of all components and production and popularization of the device.

The support rod and the container can be fixedly connected or detachably connected, for example: a base for the support rod to be inserted and pulled is arranged on the top wall edge of the container; the supporting rod can be arranged to be telescopic, and installation of all parts and filling of polluted soil are facilitated.

Further, the spraying device comprises a plurality of spraying pipes, wherein two ends of each spraying pipe are fixed on the top layer cross rod, and the periphery of each spraying pipe is provided with a spraying opening. The spraying port faces to the polluted soil, and a spraying head can be arranged at the spraying port, so that the spraying liquid is sprayed more uniformly.

Further, put in the device and include that to support with rotating around horizontal rotating shaft the last filter screen of middle level horizontal pole is used for the drive the filter screen winds the driver of horizontal rotating shaft low-angle vibration can be rolled out around vertical pivot the tray under the filter screen.

The transverse rotating shaft is arranged between the two parallel middle-layer cross rods, can drive the filter screen to vibrate at a small angle and can also drive the filter screen to turn over, so that the earthworms on the filter screen fall into the container.

Furthermore, the mesh of the filter screen is 2.5-3.5 mm.

In order to ensure the efficient restoration of the polluted soil, the size of the earthworms is not too small, and the width of the earthworms is more than 3-3.5 mm; so the mesh that sets up the filter screen is 2.5 ~ 3.5mm, and individual earthworm that is less than this mesh diameter can drop to the tray along with the small-angle vibration of filter screen in, and the earthworm that meets the requirements then remains on the filter screen, can shift out the earthworm that does not meet the requirements through rotating the tray to realize the screening of earthworm size.

After the tray rotates out of the position under the filter screen around the vertical rotating shaft, the filter screen can rotate around the transverse rotating shaft through the driver, and accordingly earthworms on the filter screen are thrown into the container. The rotation of the tray can be driven by a driving device to rotate, and can also be manually rotated.

Furthermore, the collecting device comprises a plurality of guide rails, pulleys, sliding hooks and a driver, wherein the two ends of the guide rails are fixed on the bottom layer cross bar; the bottom end of the sliding groove extends into the position 1-2 cm below the surface layer of the polluted soil.

A plurality of guide rails can be arranged between the bottom cross rods, each guide rail is provided with a pulley, and a sliding hook is fixed below each pulley, so that earthworms on the soil surface and in the surface layer of 1-2 cm are all driven to one side of the container. The pulley is driven by the driver and moves along the track of the guide rail, so that the earthworms are driven automatically.

Further, the collecting device further comprises: a collection port and a collection tank; the collecting opening is formed in the side wall of the container, which is on the same side as the moving tail end of the pulley, and the bottom of the collecting opening is located 1-2 cm below the surface layer of the polluted soil; the collecting groove is fixed on the side wall outside the container and is positioned below the collecting opening. In the prior art of adopting earthworms to restore heavy metal soil, earthworms are not driven after being thrown into the polluted soil, and a special automatic collecting device is not provided.

Further, the electric driving device comprises a positive plate, a negative plate and a power supply connected with the positive plate and the negative plate, wherein the positive plate and the negative plate are respectively arranged at the upper part and the bottom of the polluted soil and are arranged in parallel.

The pole plate on the upper part of the container can not be too close to the soil surface, and can be prevented from being pulled by the sliding groove. The positive and negative polar plates are formed by a plurality of leads in a staggered manner, so that the earthworms can easily pass through the polar plates when being electrically stimulated to move to the surface layer of the soil. The soil is electrified, so that the effective state of heavy metals in the soil can be improved, the absorption of the earthworms is promoted, and the earthworms can be driven to the surface of the soil under specific voltage, so that the absorption of the earthworms is facilitated.

The invention also provides a method for repairing heavy metal contaminated soil by using the device, which comprises the following steps:

(1) placing the heavy metal contaminated soil in a container, and spraying chemical spraying liquid into the container to spray the soil;

(2) after spraying is finished, placing the young earthworms into a feeding device for screening, and feeding the screened young earthworms into a container through the feeding device for soil remediation;

(3) after 2-3 months of remediation, electrifying the polluted soil through an electric driving device, wherein the voltage is 5-9V, so that the adult earthworms are driven to the surface layer of the polluted soil; then, collecting earthworms driven to the surface layer of the soil by a collecting device;

(4) After the collection is finished, the soil spraying is carried out again, and the steps (2) and (3) are repeated;

(5) and (5) repeating the step (4) until the remediation of the heavy metal contaminated soil is completed.

Preferably, in the step (3), the electrifying time is 1-2 days, the electrifying is carried out twice every day, the electrifying time is 30-40 min each time, and the interval between the electrifying time and the electrifying time is 3-4 h. The interval electrification is beneficial to improving the driving effect of the adult earthworms and ensuring that all the adult earthworms in the container are completely driven.

Preferably, in the step (2), after spraying is finished, earthworms are added when the water content of the soil is measured to be 20-40%. The effective state of heavy metals can be influenced by the water content of the soil, and the absorption and utilization of the heavy metals by the earthworms are further influenced.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, the earthworms carrying a large amount of heavy metal pollutants are stripped from the polluted soil by arranging the feeding device, the electric driving device and the collecting device and matching with the corresponding repairing method, so that the heavy metal pollutants in the polluted soil are completely removed, and the repairing effect is obviously improved.

(2) The invention is also provided with a spraying device, the effective state of the heavy metal in the soil is improved through chemical spraying, the earthworm adsorption effect is enhanced, the combination of chemical remediation and biological remediation is realized, and the soil remediation effect is improved.

(3) According to the invention, the spraying device, the feeding device and the collecting device are fixed above the container by arranging the frame, so that the integration of the device is realized, and the production, popularization and utilization of the device are facilitated.

Drawings

Fig. 1 is a schematic structural view of the device for remediating heavy metal contaminated soil of embodiment 1.

Fig. 2 is a left side view of the device of fig. 1.

FIG. 3 is a schematic view of the apparatus shown in FIG. 1 in a state of screening and feeding earthworms.

Fig. 4 is a top plan view of the spray assembly of the apparatus of fig. 1.

Fig. 5 is a top view of the screen plane of the device of fig. 1.

Fig. 6 is a top plan view of the plane of the tray in the apparatus of fig. 1.

Fig. 7 is a top view of the plane of the guide rail in the device of fig. 1.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples.

Example 1

As shown in fig. 1 and 2, the device for remediating heavy metal contaminated soil mainly comprises a container 1, a spraying device 2, a throwing device 3, a collecting device 4 and an electric driving device 5.

The top of the container 1 is provided with an opening, contaminated soil 6 is filled in the container 1, the top wall of the container 1 is provided with four support rods 7, and the four support rods 7 are vertically fixed at four corners of the top wall of the container 1. The supporting rod 7 is telescopic, the height can be adjusted, and the contaminated soil can be conveniently added; the side wall of the top of the container can be provided with a base for plugging and unplugging the supporting rod, so that the supporting rod is movably connected with the container. The bottom of the container 1 is provided with a plurality of filtering holes for discharging spraying liquid so as to adjust the water content of the soil.

As shown in fig. 1, 2 and 4, the spraying device 2 is composed of a spraying pipe 21 and a liquid storage tank, the spraying pipe 21 is connected with the liquid storage tank through a pipeline, a pressure pump is arranged on the pipeline, chemical spraying liquid is contained in the liquid storage tank, and the spraying liquid is pumped into the spraying pipe from the liquid storage tank through the pressure pump and the pipeline.

In order to facilitate the installation of the spray pipe, a top layer cross rod 22 is arranged between every two adjacent (non-diagonal) support rods 7, and the top layer cross rods 22 are arranged in parallel and are connected in sequence through the support rods to form a square. Two ends of the spray pipes 21 are respectively fixed on two parallel top-layer cross rods, and eight spray pipes 21 which are positioned on the same plane and are arranged in parallel are fixed between the two top-layer cross rods. Eight spray openings are formed in the periphery of the tube of the spray tube 21, spray heads 23 are installed on the spray openings, and the spray heads 23 face the polluted soil.

As shown in fig. 1, 2 and 5, the dosing device 3 consists of a screen 31, a drive and a tray 32.

In order to facilitate the installation of the filter screen 31, a middle layer cross bar 33 is arranged between every two adjacent support bars, and the middle layer cross bars 33 are arranged in parallel and are connected in sequence through the support bars to form a square. A transverse rotating shaft is arranged between the two middle-layer cross bars 33, and the filter screen 31 is fixed on the transverse rotating shaft. The filter screen 31 is driven by the driver to vibrate around the transverse rotating shaft at a small angle and turn over when earthworms need to be added

In order to ensure the efficient restoration of the polluted soil, the size of the earthworms is not too small, and the width of the earthworms is more than or equal to 3-3.5 mm; so the mesh that sets up the filter screen is 2.5 ~ 3.5mm, and the earthworm that the width is less than this mesh diameter can drop to the tray along with the small-angle vibration of filter screen in, and the earthworm that accords with the requirement then remains on the filter screen, can shift out the earthworm that does not accord with the requirement through rotating the tray to realize the screening of earthworm size.

As shown in fig. 1, 2 and 6, the tray 32 is located under the filter screen 31 for receiving the earthworms screened by the filter screen 31, which are not qualified, and the tray 32 is connected with the support rod 7 through a connecting rod and rotates around the support rod.

After the tray rotates out of the position under the filter screen around the vertical rotating shaft, the filter screen can rotate around the transverse rotating shaft through the driver, and accordingly earthworms on the filter screen are thrown into the container.

As shown in fig. 1, 2 and 7, the collecting device 4 comprises a guide rail 41, a pulley 42 arranged on the guide rail 41, a slip hook 43 fixed to the pulley 42 for driving the earthworms, and a driver for driving the pulley 42 to move along the guide rail.

In order to facilitate the installation of the guide rail 41, parallel bottom layer cross bars 44 are arranged between every two adjacent support bars, and the bottom layer cross bars 44 are arranged in parallel and are connected in sequence through the support bars to form a square. The two ends of the guide rail 41 are respectively fixed on two parallel cross bars 44, and ten guide rails 41 which are positioned on the same plane and are parallel to the bottom of the container are fixed between the two bottom cross bars 44. A pulley 42 is fixed to each rail. The bottom end of the slip hook 43 extends 1cm below the surface of the contaminated soil for driving earthworms moving to the surface of the soil to one side of the container. The earthworm expulsion device 4 is controlled to be opened by a driver.

The collecting device 4 also comprises means for collecting earthworms moving to the side of the container, including a collecting port 45 and a collecting tank 46; wherein, collect mouthful 45 set up with on the container lateral wall of pulley removal terminal homonymy, the bottom of collecting mouthful is located and pollutes 1 ~ 2cm department below the soil surface layer. In the soil remediation process, the collection port 45 is in a closed state; when the earthworms are driven, the collection port 45 is opened. The collection trough 46 is fixed to the outer side wall of the vessel, below the collection port, 5cm wide and 5cm deep.

As shown in fig. 1 and 2, the electric driving device mainly comprises a positive plate 6 and a negative plate 6 and a power supply connected with the positive plate and the negative plate, wherein the positive plate 6 and the negative plate 6 are formed by connecting a plurality of criss-cross leads and are respectively placed at a position (positive pole) 10cm away from the bottom of the container and at a position (negative pole) 10cm away from the surface of the polluted soil at the upper part of the container. The positive and negative plates 6 are connected with a power supply, and are provided with electrode switchers capable of setting periodic electrode conversion.

The operation flow of the device for repairing heavy metal contaminated soil of the embodiment is as follows:

firstly, adding polluted soil into a container, and then starting a spraying device to add chemical spraying liquid; after spraying is finished, after the water content of soil is proper, cleaning earthworms to be screened are placed on a filter screen, the filter screen is driven by a driver to vibrate in a small amplitude and a small angle, so that the earthworms with smaller heads in the filter screen fall into a tray through meshes, after the filtering and screening are finished, the tray is rotated to be separated from the upper part of the filter screen, and the earthworms which do not meet the requirement are taken out; and then the filter screen is turned downwards through the driver, so that the earthworms meeting the requirements in the filter screen fall into the polluted soil in the container for remediation.

After the restoration is finished, the positive and negative electrode plates are switched on, so that the earthworms in the soil pass through the positive electrode plate to move to the surface of the soil; meanwhile, the collection device is started, the pulley moves along the track of the guide rail under the driving of the driver, the sliding groove moves along with the pulley and contacts with the earthworms on the surface of the soil to drive the earthworms to move towards the collection port; and finally, the earthworms can be pulled into the collecting tank through the collecting port, so that the earthworms can take the pollutants in the soil away from the polluted soil. The process can be continuously and repeatedly carried out, a new batch of clean earthworms are continuously added into the soil, and adult earthworms which are saturated and adsorb heavy metals are collected until the soil remediation work is completed.

Application example 1

The device of embodiment 1 is adopted to repair the heavy metal contaminated soil, and the concrete steps are as follows:

(1) selecting polluted soil containing heavy metals of mercury and cadmium, and transferring the polluted soil with the thickness of 0-30 cm on the surface layer into a container of the device in the embodiment 1, wherein the total mass of the polluted soil is 15 kg; and starting a spraying device to spray soil.

Wherein the content of heavy metal mercury in the heavy metal polluted soil is 1.2mg/kg, the content of heavy metal cadmium in the heavy metal polluted soil is 0.45mg/kg (both are higher than the secondary standard (pH 6.5-7.5) in the soil environmental quality standard (GB 15618-1995)), the content of organic matters in the soil is 12 percent, and the pH is 6.7; citric acid is adopted as a spray liquid, the concentration is 10m mol/kg, and the total volume of the diluted spray liquid is 3000 ml.

(2) After spraying is finished, the polluted soil is not treated, the soil is placed for a period of time, after the measured soil water content is 20-40%, clean earthworms are placed in a filter screen for screening, and screened earthworms (the adding amount is 1.5kg) meeting the size requirement are added into the polluted soil for soil remediation; the repair time was 2 months.

(3) After 2 months, starting an electric drive device, electrifying the polluted soil, wherein the electrifying voltage is 7V, the electrifying time is 2 days, electrifying is carried out twice every day, each electrifying time is 35min, and the interval between the electrifying time of two times is 4 h; the adult earthworms are driven to the surface layer of the polluted soil; and starting the pulley, so that the sliding hook moves to the other side along one side of the container, drives the earthworms on the surface layer of the soil to be close to the collection port, and collects the earthworms into the collection tank through the collection port. The amount of the collected adult earthworms is 1.3kg, and the removal rate reaches 87 percent.

(4) After the collection is finished, the soil spraying is carried out again, and the steps (2) and (3) are repeated;

(5) and (5) repeating the step (4) for three times, taking a soil sample for detection every time, sampling for the third time, determining the content of the heavy metals in the repaired polluted soil to be 0.27mg/kg of cadmium element and 0.39mg/kg of mercury element respectively, and reducing the content to be within a standard range to finish the repair of the heavy metal polluted soil.

Claims (7)

1. A device for repairing heavy metal contaminated soil comprises a rack and a container which is positioned below the rack, is used for containing contaminated soil and is provided with an opening at the top, and is characterized in that the rack is provided with a plurality of grooves;

the electric driving device for driving the earthworms in the soil to the surface layer of the soil is arranged in the container, and the throwing device for throwing the earthworms into the container and the collecting device for collecting the earthworms driven to the surface layer of the soil are sequentially arranged above the container from top to bottom;

a spraying device for spraying chemical agents to the contaminated soil in the container is arranged above the feeding device;

the container is fixed with the spraying device, the throwing device and the collecting device through the rack; the rack consists of a support rod and a cross rod;

the supporting rod is vertically arranged on the edge of the top wall of the container; the cross rods are arranged between every two adjacent supporting rods and are horizontally arranged; the cross rods are arranged in a multilayer mode, the top cross rod is connected with the spraying device, the middle cross rod is connected with the throwing device, and the bottom cross rod is connected with the collecting device;

the collecting device comprises a plurality of guide rails, pulleys, sliding hooks and a driver, wherein the two ends of the guide rails are fixed on the bottom layer cross rod; the bottom end of the sliding hook extends into a position 1-2 cm below the surface layer of the polluted soil;

Parallel bottom cross rods are arranged between every two adjacent supporting rods and are connected in sequence through the supporting rods.

2. The device as claimed in claim 1, wherein the spraying device comprises a plurality of spraying pipes, two ends of each spraying pipe are fixed on the top cross bar, and the periphery of each spraying pipe is provided with a spraying port.

3. The apparatus of claim 1, wherein said dispensing means comprises a screen rotatably supported on said middle rail about a transverse axis, a drive for driving said screen to oscillate at a small angle about said transverse axis, and a tray rotatable about a vertical axis directly beneath said screen.

4. The apparatus of claim 1, wherein the collecting means further comprises: a collection port and a collection tank; the collecting opening is formed in the side wall of the container, which is on the same side as the moving tail end of the pulley, and the bottom of the collecting opening is located 1-2 cm below the surface layer of the polluted soil; the collecting groove is fixed on the side wall outside the container and is positioned below the collecting opening.

5. The apparatus according to claim 1, wherein the electric repelling means comprises positive and negative plates and a power supply connected to the positive and negative plates, the positive and negative plates being disposed in parallel on the upper and bottom of the contaminated soil, respectively.

6. A method for restoring heavy metal contaminated soil by using the device of any one of claims 1 to 5, comprising the steps of:

(1) placing the heavy metal contaminated soil in a container, and spraying a chemical agent into the container to spray the soil;

(2) after spraying is finished, the clean earthworms are placed in a throwing device for screening, and the screened earthworms are thrown into a container through the throwing device for soil remediation;

(3) after 2-3 months of remediation, electrifying the contaminated soil through an electric driving device, wherein the voltage is 3-9V, so that the adult earthworms are driven to the surface layer of the contaminated soil; then, collecting earthworms driven to the surface layer of the soil by a collecting device;

(4) after the collection is finished, the soil spraying is carried out again, and the steps (2) and (3) are repeated;

(5) and (5) repeating the step (4) until the remediation of the heavy metal contaminated soil is completed.

7. The method as claimed in claim 6, wherein in the step (2), clean earthworms are added when the water content of the soil is measured to be 20-40% after spraying is finished.

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