CN115318821A

CN115318821A - Microbial electrochemical device and method for removing composite heavy metals in soil

Info

Publication number: CN115318821A
Application number: CN202210955306.7A
Authority: CN
Inventors: 李先宁; 魏钿; 高昕童
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2022-08-10
Filing date: 2022-08-10
Publication date: 2022-11-11
Anticipated expiration: 2042-08-10
Also published as: CN115318821B

Abstract

The invention relates to a microbial electrochemical device for removing composite heavy metals in soil, which comprises a cathode drawer, a multi-drawer type polluted soil layer, a cathode drawer and a lower soil drawer, wherein the multi-drawer type polluted soil layer is formed by sequentially stacking a plurality of upper soil drawers, a third metal soft net is arranged in a bottom port of each upper soil drawer, a liquid injection mechanism is arranged at the upper part of the third metal soft net, the bottom end of the cathode drawer can be embedded into the top end of the soil drawer on the topmost layer in an adaptive mode, a fourth metal soft net is arranged in a bottom port of the cathode drawer, the top end of the anode drawer is embedded into the bottom end of the soil drawer on the bottommost layer in an adaptive mode, a second metal soft net is arranged in the bottom port of the anode drawer, the bottom end of the anode drawer is embedded into the top end of the lower soil drawer in an adaptive mode, a first metal soft net is arranged in the bottom port of the lower soil drawer, a bottom shell is embedded into the bottom of the lower soil drawer in an adaptive mode, and a drain valve is installed at the bottom of the bottom shell. The device is based on the device, and the mobility of heavy metals is improved, so that electrochemical reaction can be efficiently and stably operated.

Description

Microbial electrochemical device and method for removing composite heavy metals in soil

Technical Field

The invention relates to the technical field of soil remediation, in particular to a microbial electrochemical device and a method for removing complex heavy metals in soil.

Background

A Microbial Electrochemical System (MES) is a new repairing technology, combines microbes with Electrochemical repair, provides faster and more effective repairing performance than other repairing technologies, and has been widely applied to the field of soil repair. The integrated soil MES has no expensive separating membrane, and has two-way electroosmosis and electromigration channel maintained to reach the broad-spectrum metal treatment of the heavy metal with negative ion material moving to the anode and positive ion reducing in the cathode.

But also has the limitations of itself, which are mainly shown in the following aspects:

in some cases, microbial remediation cannot remove all of the contaminants because when the contaminant concentration is too low to sustain a certain number of degrading bacteria, residual contaminants remain in the soil; the treatment effect of the polluted soil in cold and arid and semi-arid regions and the petroleum pollution in the sea is poor under the conditions of low temperature and low water content.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a microbial electrochemical device and a microbial electrochemical method for removing compound heavy metals in soil, and aims to improve the mobility of the heavy metals and enable the MES internal electrochemical reaction of the integrated soil to be carried out more efficiently and more stably.

The technical scheme adopted by the invention is as follows:

the utility model provides a get rid of little biological electrochemical device of compound heavy metal in soil, pollutes soil horizon, cathode steamer tray and lower soil steamer tray including cathode steamer tray, many steamer trays formula pollutes soil horizon and is formed by a plurality of last soil steamer trays from top to bottom stack in proper order, is equipped with the soft net of third metal in the bottom mouth of every last soil steamer tray for place pending soil, the upper portion that is located the soft net of third metal is equipped with annotates liquid mechanism, is used for evenly injecting auxiliary reagent into in the soil, the bottom of cathode steamer tray can the adaptation imbed the top of soil steamer tray on the top layer, is equipped with the soft net of second metal in the bottom mouth of cathode steamer tray, is equipped with the soft net of fourth metal in the bottom mouth of cathode steamer tray for place active carbon particle and bury the negative pole body, the bottom of soil steamer tray can the adaptation imbed the bottom on the bottom of anode steamer tray, the bottom mouth of anode steamer tray is inside to be equipped with the soft net of second metal for place active carbon particle, throw the mud that has the anaerobism electrogenesis fungus and bury the ponding body, the bottom of anode tray can the adaptation imbed the bottom of soil steamer tray, be equipped with the bottom of soil steamer tray, the bottom of soil steamer tray is equipped with the ponding, the bottom of drain pan is equipped with the ponding, and is used for the ponding of drain water drain and is handled the drain pan under the drain.

The further technical scheme is as follows:

get rid of microorganism electrochemical device of compound heavy metal in soil still includes the base, be equipped with a plurality of support rods of group along the direction of height interval on the base for hang respectively and put go up the soil steamer tray.

The base is further provided with a lifting platform, the accumulated water bottom shell is sequentially connected with the lower soil drawer and the anode drawer to form a lifting unit, and the lifting unit can be fixed and lifted by the lifting platform to be connected with the multi-drawer type polluted soil layer.

The structure of the liquid injection mechanism comprises a plurality of transverse water pipes which penetrate through the upper soil drawer, the inlet end of the liquid injection mechanism is connected with an external auxiliary reagent source through a valve, the outlet end of the liquid injection mechanism is connected with a plurality of longitudinal water pipes respectively, and liquid outlet holes are formed in the longitudinal water pipes and used for being buried in soil.

Each metal soft net is made of titanium metal.

The method for removing the complex heavy metals in the soil is based on the microbial electrochemical device for removing the complex heavy metals in the soil, and comprises the following steps:

filling soil polluted by heavy metal to be treated in the lower soil drawer and each upper soil drawer, filling activated carbon particles in the anode drawer and the cathode drawer, burying and compacting an anode body, adding sludge containing anaerobic electrogenic bacteria into the activated carbon particles of the anode drawer, injecting a certain amount of nutrient solution subjected to nitrogen blowing treatment to enable the anode body to be in an anaerobic environment, burying and compacting a cathode body in the activated carbon particles of the cathode drawer, sequentially assembling the microbial electrochemical devices, keeping the heavy metal polluted soil in each upper soil drawer, and enabling the activated carbon particles in the anode drawer and the cathode drawer to be in contact with the heavy metal polluted soil in the upper soil drawer respectively connected with the activated carbon particles in the anode drawer and the cathode drawer through corresponding metal soft nets, wherein the heavy metal concentration of the soil in each upper soil drawer is the same;

sequentially connecting the anode body, the external resistor and the cathode body in series to form a closed loop for carrying out microbial electrochemical reaction;

and slowly injecting auxiliary reagents into the upper soil drawers through the liquid injection mechanism.

The further technical scheme is as follows:

the method for removing the compound heavy metals in the soil further comprises the following steps: and after the reaction time reaches a set value, taking down the thick empty drawer positions from a plurality of upper soil drawers close to the anode drawer, sequentially moving the rest upper soil drawers down to the empty drawer positions, and finally completing the empty drawer positions by using a new upper soil drawer containing untreated soil, ensuring that the concentration of heavy metal ions in the soil in the upper soil drawer close to the cathode drawer is higher than that in the upper soil drawer close to the anode drawer, continuing the soil remediation treatment, and repeating the replacement operation of the upper soil drawer when the reaction time reaches the set value to realize continuous remediation.

The auxiliary reagent is one or more of acetic acid solution, citric acid solution and staphylococcus-containing microbial inoculum.

The invention has the following beneficial effects:

the device provided by the invention is convenient for timely replacement of the soil layer to be repaired so as to maintain a higher concentration difference, and improves the mobility of heavy metals, so that the internal electrochemical reaction is performed more efficiently and more stably.

According to the remediation method disclosed by the invention, the auxiliary reagent is added into the soil, so that the water saturation state of the soil is maintained, the conductivity of the soil is improved, the desorption of ionic heavy metals is promoted, and the remediation effect is enhanced.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

Fig. 1 is a schematic perspective view of an embodiment of the present invention.

Fig. 2 is a schematic view of a base structure according to an embodiment of the invention.

Fig. 3 is another view of the structure of fig. 1.

Fig. 4 is a schematic view of an internal structure of each drawer according to an embodiment of the present invention.

Fig. 5 is a schematic structural view of a lower soil drawer according to an embodiment of the present invention.

Fig. 6 is a schematic structural view of an upper soil drawer according to an embodiment of the present invention.

Fig. 7 is a schematic structural diagram of a cathode drawer according to an embodiment of the invention.

FIG. 8 is a simplified circuit diagram of an embodiment of the present invention.

In the figure: 1. a base; 2. a lifting platform; 3. a lifting rod; 4. connecting a resistor externally; 5. water accumulation bottom shell; 6. a soil drawer is arranged; 7. a first metal soft net; 8. an anode drawer; 9. a second metal soft net; 10. a soil drawer is arranged; 11. ear muffs; 12. a transverse water pipe; 13. a valve; 14. a longitudinal water pipe; 15. a third metal soft net; 16. a cathode drawer; 17. a fourth metal soft net; 18. a support rod.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings.

As shown in fig. 1, the embodiment of the present application provides a microbial electrochemical device for removing composite heavy metals in soil, including a cathode drawer 16, a multi-drawer type contaminated soil layer, a cathode drawer 16 and a lower soil drawer 6, the multi-drawer type contaminated soil layer is formed by sequentially stacking a plurality of upper soil drawers 10 from top to bottom, a third metal soft net 15 is disposed in a bottom port of each upper soil drawer 10 as shown in fig. 6, and is used for placing soil to be treated, an injection mechanism is disposed on the upper portion of the third metal soft net 15, and is used for uniformly injecting an auxiliary reagent into the soil, a bottom end of the cathode drawer 16 is fittingly embedded into a top end of the soil drawer 10 on the topmost layer, a fourth metal soft net 17 is disposed in a bottom port of the cathode drawer 16 as shown in fig. 7, and is used for placing activated carbon particles and embedding a cathode body, a top end of the anode drawer 8 is fittingly embedded into a bottom end of the soil drawer 10 on the bottommost layer, a bottom port of the anode drawer 8 is internally disposed with a second metal soft net 9, and is used for placing activated carbon particles, and anaerobic sludge is added, a bottom end of an anode is embedded into a bottom pan 6, a bottom drain valve is disposed on the bottom end of the lower soil to be treated, and is disposed on the bottom pan 6, and is disposed with a drain valve 5, and is disposed on the bottom end of the bottom pan and is disposed on the bottom of the soil to be used for draining water collecting water valve for collecting tank.

Specifically, the water accumulation bottom shell is used for receiving water generated in the microbial electrochemical reaction process.

Specifically, each metal soft net is made of titanium metal.

As shown in fig. 2, the microbial electrochemical device for removing complex heavy metals from soil of the above embodiment further includes a base 1, and a plurality of support rods 18 are arranged on the base 1 at intervals along the height direction and used for respectively hanging the upper soil drawer 10.

Specifically, the ear sleeves 11 are installed above the two sides of the upper soil drawer 10, and during installation, the supporting rods 18 are correspondingly and adaptively embedded into the ear sleeves 11 and are limited through bolts.

As shown in fig. 3 and 5, the base is further provided with a lifting platform 2, the ponding bottom case 5 is sequentially connected with the lower soil drawer 6 and the anode drawer 8 to form a lifting unit, and the lifting unit can be fixed and lifted by the lifting platform 2 to be connected with the multi-drawer type polluted soil layer.

Specifically, elevating platform 2 slidable mounting all installs lifter 3 in the horizontal installation face of

base

1, 2 bottom both sides of elevating platform, and the bottom of lifter 3 corresponds respectively and installs in the mesa both sides of base 1, and the top at elevating platform 2 is installed to the bottom of ponding drain pan 5, and the through-hole has been seted up at the middle part of elevating platform 2 for holding the blowoff valve.

Specifically, the external resistor 4 is mounted on the base 1.

As shown in fig. 6, the liquid injection mechanism may include a plurality of horizontal water pipes 12 penetrating through the upper soil drawer 10, an inlet end connected to an external auxiliary reagent source through a valve 13, an outlet end connected to a plurality of vertical water pipes 14, and liquid outlet holes provided on the vertical water pipes 14 for being buried in soil.

The embodiment of the application also provides a method for removing compound heavy metals in soil, and the microbial electrochemical device for removing the compound heavy metals in the soil comprises:

filling soil polluted by heavy metal to be treated in the lower soil drawer 6 and each upper soil drawer 10, filling activated carbon particles in the anode drawer 8 and the cathode drawer 16, burying and compacting an anode body, adding sludge containing anaerobic electrogenic bacteria into the activated carbon particles of the anode drawer 8, and injecting a certain amount of nutrient solution subjected to nitrogen blowing treatment to enable the anode body to be in a strict anaerobic environment, burying and compacting a cathode body in the activated carbon particles of the cathode drawer 16, sequentially assembling microbial electrochemical devices, keeping the soil polluted by heavy metal in each upper soil drawer 10, and enabling the activated carbon particles in the anode drawer 8 and the cathode drawer 16 and the soil polluted by heavy metal in the upper soil drawer 10 respectively connected with the activated carbon particles to be in contact with each other through corresponding metal soft nets, as shown in fig. 4;

auxiliary reagents are slowly injected into the upper soil drawers 10 through the liquid injection mechanism.

The method of the above embodiment, wherein the assembled microbial electrochemical device further comprises:

hanging each upper soil drawer 10 on a corresponding bearing rod 18 on the base 1 by using an ear sleeve 11 arranged on the side surface of the upper soil drawer to form a multi-drawer type polluted soil layer piece with a soil layer compacted tightly in sequence from top to bottom;

with ponding drain pan 5 and lower soil steamer tray 6, positive pole steamer tray 8 links to each other in proper order and forms a lift unit, fix on elevating platform 2 of base 1, start the lifter 3 of 2 bottoms of elevating platform, and then the bearing through elevating platform 2 makes on lift unit and the bottom soil steamer tray 10 adjacent each other, make the inside active carbon particle of positive pole steamer tray 8 can with on the bottom form good electricity intercommunication through the soft net of second metal between the inside heavy metal pollution soil of soil steamer tray, with in the top port of soil steamer tray on the top layer of negative pole steamer tray 16 embedding, then the compaction is so that the inside active carbon particle of negative pole steamer tray 16 can with on the top layer form good electricity intercommunication through the soft net of fourth metal between the inside heavy metal pollution soil of soil steamer tray.

The method of the above embodiment further comprises: and when the reaction time reaches a set value, taking down a plurality of upper soil drawers 10 close to the anode drawer 8 to form empty drawer positions, sequentially moving the rest upper soil drawers 10 down to the empty drawer positions, completing the empty drawer positions by using new upper soil drawers 10 containing untreated soil, ensuring that the concentration of heavy metal ions in the soil in the upper soil drawer 10 close to the cathode drawer 16 is higher than that in the upper soil drawer 10 close to the anode drawer 8, continuously performing soil remediation treatment, and repeating the replacement operation of the upper soil drawer 10 when the reaction time reaches the set value to realize continuous remediation.

The replacement of the upper soil drawer can be specifically realized based on the operation of the lifting table, the ear sleeves and the bearing rods.

The auxiliary reagent is one or more of acetic acid solution, citric acid solution and staphylococcus-containing microbial inoculum so as to maintain the water saturation state of the soil and improve the conductivity of the soil.

Referring to fig. 8, the working mechanism of the method for removing the complex heavy metals in the soil according to the above embodiment is as follows:

the electrogenesis bacteria in the anode drawer decompose organic matters and nutrient substances in the polluted soil, electrons and protons are generated in the process, the electrons reach the cathode body through the anode body and the external circuit, the protons reach the cathode body through the soil under the action of the electric field, the cathode body takes oxygen as an electron acceptor, the electrons and the oxygen react to generate water through an electrode, a loop is formed, current and voltage are generated, the generation of the current and the voltage in the loop enables metal ions with electric property to synchronously migrate from the anode to the cathode under the action of the internal electric field and to be reduced at the cathode body, the metal ions return to the cathode body and intensively process the soil close to the cathode, and the whole device utilizes the reduction characteristic of the microbial electrochemical cathode unit to enable heavy metals in the soil to migrate and be reduced at the cathode, so that the remediation treatment of the composite heavy metal polluted soil is realized.

And water produced in the reaction process flows downwards to the water accumulation bottom shell under the action of gravity and is discharged from the drain valve.

Because in the repair process, along with the enrichment of metal to the negative pole, go up the heavy metal ion that the concentration descends in the soil steamer tray, the migration power will reduce, and then influences the treatment effeciency. This application is through setting up a plurality of soil drawers of going up, can make things convenient for in time to change the soil drawer after the reaction, makes it can remain a suitable concentration difference all the time to maintain a great migration effort, respectively go up the heavy metal ion concentration top-down (from negative pole drawer to positive pole drawer direction promptly) in the soil drawer promptly and be the trend that reduces, through constantly changing the soil drawer, can realize continuous, the high-efficient restoration of soil.

The soil drawer replacement triggering condition can be the set time value of the reaction treatment, and the replacement operation can be carried out when the time value is one. Other trigger adjustments may also be set depending on the actual situation.

To verify the validity of the present application, the following two sets of tests were specified:

the first test: the soil layer is phi 350mm multiplied by 100mm multi-drawer type polluted soil unit layer phi 350mm multiplied by 1000mm multiplied by 5, the size of an anode body in an anode drawer 8 and a cathode body in a cathode drawer 16 is phi 350mm multiplied by 150mm, the particle size of activated carbon is 3-5mm, the specific surface area is 500-900m < 2 >/g, a stainless anode steel sheet body and a carbon felt cathode body are connected through a 1000 omega external resistor 4 to form a closed loop, 1200g of composite polluted soil containing heavy metals Cu and Pb and 1000mL of staphylococcus-containing microbial inoculum are added into the polluted soil layer when MES is built, 120mL of cultured and pretreated anaerobic sludge containing electrogenic bacteria is added into the anode drawer 8, and a certain amount of nutrient solution subjected to nitrogen blowing treatment is injected until the soil is in a water saturation state.

After the experiment is finished, the removal rates of the total Cu and the total Pb reach 34.25% and 14.54%, respectively, and therefore, the microbial electrochemistry can effectively and synchronously remove the composite heavy metals in the soil.

And (2) testing II: the method comprises the following steps of enabling the size of a soil layer to be 35mm multiplied by 10mm, enabling a multi-drawer type polluted soil unit layer to be 35mm multiplied by 100mm multiplied by 5mm, enabling the size of an anode body in an anode drawer 8 and a cathode body in a cathode drawer 16 to be 35mm multiplied by 15mm, enabling the particle size of activated carbon to be 3-5mm, enabling the specific surface area to be 500-900m & lt 2 & gt/g, enabling a stainless steel sheet anode body and a carbon felt cathode body to be connected through a 1000 omega external resistor 4 to form a closed loop, adding 120g of composite polluted soil containing heavy metals Cu and Pb and 100mL of citric acid solution into the polluted soil layer when MES is built, adding 12mL of cultured and pretreated condensed anaerobic sludge containing electrogenic bacteria into the anode drawer 8, and injecting a certain amount of nutrient solution subjected to nitrogen blowing treatment until the soil is in a water saturation state.

After the experiment is finished, the removal rates of the total Cu and the total Pb reach 34.25% and 4.54% respectively, and therefore the microbial electrochemistry can effectively and synchronously remove the composite heavy metals in the soil.

The invention utilizes the electrogenesis performance of microorganisms in MES to create an internal electric field, non-selectively drives heavy metals to directionally migrate under the action of the electric field force, can synchronously reduce and remove the heavy metals migrated to a cathode region, and removes microorganisms migrated to an anode region, such as: copper can be reduced and deposited on the cathode plate, in order to further promote the removal efficiency of heavy metals in soil, a bioremediation agent is added into the soil, the heavy metals in the soil activate the heavy metals in the soil under the action of staphylococcus, the heavy metals synchronously migrate under the action of an electric field inside soil MES and are removed, the remediation of the composite contaminated soil is realized, and good effects of synchronously removing the heavy metals in the soil and recovering metal resources are achieved.

Those of ordinary skill in the art will understand that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A microbial electrochemical device for removing composite heavy metals in soil is characterized by comprising a cathode drawer (16), a multi-drawer type polluted soil layer, a cathode drawer (16) and a lower soil drawer (6), the multi-drawer type polluted soil layer is formed by stacking a plurality of upper soil drawers (10) from top to bottom in sequence, a third metal soft net (15) is arranged in a bottom port of each upper soil drawer (10), used for placing the soil to be treated, a liquid injection mechanism is arranged at the upper part of the third metal soft net (15), is used for uniformly injecting auxiliary reagents into soil, the bottom end of the cathode drawer (16) can be inserted into the top end of the soil drawer (10) on the topmost layer, a fourth metal soft net (17) is arranged in the bottom end opening of the cathode drawer (16), used for placing active carbon particles and embedded into a cathode body, the top end of the anode drawer (8) can be embedded into the bottom end of the soil drawer (10) on the bottom layer in a matching way, a second metal soft net (9) is arranged inside the bottom end opening of the anode drawer (8), is used for placing activated carbon particles and adding sludge with anaerobic electrogenic bacteria and is embedded into the anode body, the bottom end of the anode drawer (8) can be embedded into the top end of the lower soil drawer (6) in a matching way, a first metal soft net (7) is arranged in the bottom end opening of the lower soil drawer (6), a blowoff valve is installed to the bottom that is used for placing pending soil, but lower soil drawer's (6) bottom adaptation inlayed ponding drain pan (5), ponding drain pan (5).

2. The microbial electrochemical device for removing the composite heavy metals in the soil according to claim 1, further comprising a base (1), wherein a plurality of groups of support rods (18) are arranged on the base (1) at intervals along the height direction and are used for hanging the upper soil drawer (10) respectively.

3. The microbial electrochemical device for removing complex heavy metals in soil according to claim 2, wherein a lifting table (2) is further arranged on the base, the accumulated water bottom shell (5) is sequentially connected with the lower soil drawer (6) and the anode drawer (8) to form a lifting unit, and the lifting unit can be fixed and lifted by the lifting table (2) so as to be connected with the multi-drawer type polluted soil layer.

4. The microbial electrochemical device for removing the composite heavy metals in the soil according to claim 1, wherein the liquid injection mechanism comprises a plurality of horizontal water pipes (12) penetrating through the upper soil drawer (10), an inlet end of the liquid injection mechanism is connected with an external auxiliary reagent source through a valve (13), an outlet end of the liquid injection mechanism is connected with a plurality of longitudinal water pipes (14), and liquid outlet holes are formed in the longitudinal water pipes (14) and used for being buried in the soil.

5. The microbial electrochemical device for removing complex heavy metals in soil according to claim 1, wherein each metal soft net is made of titanium.

6. The method for removing the complex heavy metals in the soil is based on the microbial electrochemical device for removing the complex heavy metals in the soil as claimed in claim 1, and comprises the following steps:

filling soil polluted by heavy metals to be treated in a lower soil drawer (6) and each upper soil drawer (10), filling activated carbon particles in an anode drawer (8) and a cathode drawer (16), embedding anode bodies and compacting, adding sludge containing anaerobic electrogenic bacteria into the activated carbon particles of the anode drawer (8), injecting a certain amount of nutrient solution subjected to nitrogen blowing treatment to enable the anode bodies to be in an anaerobic environment, embedding cathode bodies in the activated carbon particles of the cathode drawer (16) and compacting, sequentially assembling the microbial electrochemical devices, keeping the heavy metal polluted soil in each upper soil drawer (10), and keeping the activated carbon particles in the anode drawer (8) and the cathode drawer (16) and the heavy metal polluted soil in the upper soil drawers (10) respectively connected with the activated carbon particles in the anode drawer (8) and the cathode drawer (16) to be in contact with each other through corresponding metal soft nets, wherein the heavy metal concentrations of the soil in each upper soil drawer (10) are the same;

auxiliary reagents are slowly injected into the upper soil drawers (10) through the liquid injection mechanism.

7. The method for removing complex heavy metals in soil according to claim 6, further comprising: when the reaction time reaches a set value, taking down a plurality of upper soil drawers (10) close to the anode drawer (8) and emptying drawer positions, then sequentially moving down the rest upper soil drawers (10) to the emptied drawer positions, finally completing the empty drawer positions by using a new upper soil drawer (10) filled with untreated soil, ensuring that the concentration of heavy metal ions in the soil in the upper soil drawer (10) close to the cathode drawer (16) is higher than that in the upper soil drawer (10) close to the anode drawer (8), continuing soil remediation treatment, and repeating the replacement operation of the upper soil drawer (10) when the reaction time reaches the set value to realize continuous remediation.

8. The method for removing the compound heavy metals in the soil according to claim 6, wherein the auxiliary reagent is one or more of acetic acid solution, citric acid solution and staphylococcus-containing microbial inoculum.