CN114769306A - Device and method for combined electromechanical-rinsing remediation of composite heavy metal polluted soil - Google Patents

Abstract

The invention discloses a device and a method for restoring composite heavy metal contaminated soil by an electric-leaching combined technology, and the device comprises a direct-current power supply, a first liquid storage chamber, a second liquid storage chamber, a third liquid storage chamber, a fourth liquid storage chamber, electrode chambers and a soil chamber, wherein the electrode chambers are arranged in the soil chamber, the number of the electrode chambers is multiple, the electrode chambers comprise a middle electrode chamber positioned in the soil chamber and peripheral electrode chambers arranged around the middle electrode chamber, electrode columns are respectively arranged in the electrode chambers, the electrode columns in the middle electrode chamber are connected with a cathode of the direct-current power supply, and the electrode columns in the peripheral electrode chambers are connected with an anode of the direct-current power supply 70 percent; by adopting the electric-leaching combined technology, leaching is carried out firstly, and then electric power is applied, so that the repairing time is greatly shortened, and the heavy metal removal rate is improved.

Description

Device and method for combined electromechanical-rinsing remediation of composite heavy metal polluted soil

technical field

The invention relates to the field of contaminated soil treatment and restoration, in particular to a device and method for combined electromechanical-rinsing restoration of composite heavy metal contaminated soil.

Background technique

With the development of society and economy, man-made activities such as mining, industrial production, and agricultural fertilization have caused the accumulation of heavy metal content in soil, which has exceeded the self-purification capacity of soil and seriously endangers the social environment and public health.

For heavy metal-contaminated soil, remediation treatment can be carried out by leaching, solidification-stabilization, chemical oxidation/reduction, phytoremediation, and electrodynamics. Electrodynamic remediation technology deploys electrodes on contaminated sites and applies voltage to the electrode terminals to resolve heavy metals from the surface of soil particles into pore water solution, and then migrate to the electrode chamber for removal under the action of electromigration, electrodialysis, electrophoresis, and diffusion. It has the advantages of less impact on soil structure, less secondary pollution, flexible use of in-situ or ex-situ repair methods, etc., and has good application prospects. The traditional electric remediation research is mainly based on one-dimensional electric field (ie, one cathode and one anode). The soil potential difference of the site is unstable, and the effective working area is small, which makes the remediation time long, the removal rate of heavy metals is poor, and the treatment cost is high. The use of two-dimensional electric field electrodynamic repair technology can significantly increase the effective working area of the electric field, shorten the repair time, and improve the removal rate of heavy metals. The leaching technology can significantly speed up the desorption time between heavy metals and soil particles, and has the advantages of short remediation cycle and high efficiency, but the remediation effect on low-permeability soils such as clay is poor. To sum up, there are many limitations in site remediation with a single electrodynamic or leaching remediation technology. Therefore, electromechanical-leaching combined remediation is used to remediate composite heavy metal-contaminated soil.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the technical solution provided by the present invention is: an electric-rinsing combined repairing device for composite heavy metal polluted soil, comprising a DC power supply, a first liquid storage chamber, a second liquid storage chamber, and a third liquid storage chamber , the fourth liquid storage chamber, the electrode chamber and the soil chamber, the electrode chamber is arranged in the soil chamber, and the number of the electrode chambers is multiple, including the middle electrode chamber located in the soil chamber and the peripheral electrodes arranged around the middle electrode chamber The electrode chamber is equipped with electrode columns, the electrode column in the middle electrode chamber is connected with the cathode of the DC power supply, the electrode column in the peripheral electrode chamber is connected with the anode of the DC power supply, and the first liquid storage chamber passes through the first liquid storage chamber. The liquid outlet pipe extends into the soil chamber and is connected to the sprinkler head, the second liquid storage chamber is connected to the peripheral electrode chamber through the second liquid outlet pipe, and the third liquid storage chamber and the fourth liquid storage chamber pass through the third outlet pipe respectively. The liquid pipe and the fourth liquid outlet pipe are connected with the intermediate electrode chamber.

Further, the electrode chamber is a porous column, and the electrode column is a graphite electrode column.

Further, filter paper is provided on the inner wall of the electrode.

Further, peristaltic pumps are respectively provided on the first liquid outlet pipe, the second liquid outlet pipe and the third liquid outlet pipe.

Further, an ammeter is connected to the cathode of the DC power supply.

Further, eluent is stored in the first liquid storage chamber, anode repair liquid is stored in the second liquid storage chamber, cathode repair liquid is stored in the third liquid storage chamber, and overflow liquid is stored in the fourth liquid storage chamber.

The invention also discloses a method for combined electrokinetic-rinsing repairing composite heavy metal polluted soil, comprising the following steps:

S1, leaching: According to the solid-liquid ratio of soil to leaching solution is 1g: 0.1~0.5ml, the leaching solution in the first liquid storage chamber is input into the soil chamber through the peristaltic pump, and the leaching and repairing time is 1-3 Days, after rinsing, drain the excess eluent;

S2. Electric: apply an electric field to the leached polluted soil chamber, the voltage is 1-3V/cm, and the initial current is 0.1-0.4A; The pump controls the flow rate, and controls the height of the liquid level in the anode chamber to be consistent with the soil remediation height; the remediation solution in the third liquid storage chamber is input into the cathode electrode chamber through the peristaltic pump, the liquid level in the cathode chamber is consistent with the soil height, and the liquid level exceeds the set The height is automatically input into the fourth liquid storage chamber; the electrolysis time is 8 to 20 days; the restoration of the heavy metal composite polluted soil is completed.

Further, in the step S1, the eluent is an EDTA-2Na solution and a citric acid solution, the molar concentration of the EDTA-2Na solution is 0.05-1.0 mol/L, and the molar concentration of the citric acid solution is 0.1-1.0 mol/L; the In step S1, the flow rate of the eluent is controlled by a peristaltic pump to be 0.5-1.0 mL/min.

Further, in the step S2, the anode repair solution is citric acid, and the molar concentration is 0.1-1.0 mol/L; the cathode repair solution is citric acid, and the molar concentration is 0.1-0.5 mol/L;

Further, after the step S2 is repaired until the soil near the cathode chamber is hardened, S1 can be started again, and the eluent in the first liquid storage chamber is input into the soil of the cathode area through a peristaltic pump, and the electrodynamic repair is carried out simultaneously.

The working principle of the invention is as follows: a repairing method of first rinsing and then electric power is adopted. First, through leaching, some heavy metals enter the soil pore water solution under the action of complexation/acidification, and then are discharged with the leaching solution. Secondly, under the condition of applying an electric field, the soil is further acidified, the heavy metals are further desorbed, and finally migrated to the electrode chamber under the action of the electric field to form precipitation and removal.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention provides a method for repairing composite heavy metal-contaminated soil with an electrokinetic-rinsing combined technology. The electrokinetic-rinsing combined technology is used to repair the heavy metal-contaminated soil. 80%, 70%.

(2) The two-dimensional electrodynamic repair technology adopted in the present invention greatly improves the effective working area of the electric field, so that the heavy metals in the soil to be repaired can be effectively removed.

(3) The present invention adopts the combined electric-rinsing technology, firstly rinsing, then electric power, which greatly shortens the repair time and improves the removal rate of heavy metals.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings required in the embodiments will be briefly introduced below. It should be understood that the following drawings only illustrate some embodiments of the present invention. Therefore, it should not be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is a schematic diagram of the connection of an electrode chamber, an electrode column and a DC power supply in a device for combined electrokinetic-rinsing repairing composite heavy metal-contaminated soil according to the present invention.

FIG. 2 is a schematic diagram of the connection between the electrode chamber and each liquid storage chamber in a device for combined electrokinetic-rinsing repairing composite heavy metal-contaminated soil according to the present invention.

FIG. 3 is a schematic view of the disassembly of a device of the present invention for a combined electrokinetic-rinsing repairing composite heavy metal-contaminated soil.

FIG. 4 is a schematic diagram of the distribution of electrode chambers in an apparatus for combined electrokinetic-rinsing repairing composite heavy metal-contaminated soil according to the present invention.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", The orientation or positional relationship indicated by "outside" is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that is usually placed when the product of the invention is used, which is only for the convenience of describing the present invention and simplifying the description, and It is not indicated or implied that the indicated device or element must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first", "second", "third", etc. are only used to differentiate the description and should not be construed as indicating or implying relative importance.

Furthermore, the appearance of the terms "horizontal", "vertical", "overhanging" etc. does not imply that the component is required to be absolutely horizontal or overhanging, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal than "vertical", it does not mean that the structure must be completely horizontal, but can be slightly inclined.

In the description of the embodiments of the present invention, "a plurality of" means at least two.

In the description of the embodiments of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. It can be a fixed connection, or a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

Example

A device for combined electromechanical-rinsing repairing composite heavy metal polluted soil, comprising a DC power supply 1, a first liquid storage chamber 2, a second liquid storage chamber 3, a third liquid storage chamber 10, a fourth liquid storage chamber 11, and an electrode chamber 4 and the soil chamber 5, the electrode chamber 4 is arranged in the soil chamber 5, and the number of the electrode chambers 4 is multiple, including the middle electrode chamber 401 located in the soil chamber 5 and the peripheral electrode chamber 402 arranged around the middle electrode chamber 401, Electrode columns 6 are respectively arranged in the electrode chamber 4. In this embodiment, the electrode chamber 4 is a porous column, the electrode column 6 is a graphite electrode column, the electrode column 6 in the middle electrode chamber 401 is connected to the cathode of the DC power supply 1, and the peripheral electrode chamber The electrode column 6 in 402 is connected to the anode of the DC power supply 1, the ammeter 15 is connected to the cathode of the DC power supply 1, the first liquid storage chamber 2 extends into the soil chamber through the first liquid outlet pipe 7 and is connected to the shower head 8, and the second liquid storage chamber The chamber 3 is connected to the peripheral electrode chamber 402 through the second liquid outlet pipe 9, and the third liquid storage chamber 10 and the fourth liquid storage chamber 11 are respectively connected to the intermediate electrode chamber 401 through the third liquid outlet pipe 12 and the fourth liquid outlet pipe 13. ; The first liquid outlet pipe 7, the second liquid outlet pipe 9, and the third liquid outlet pipe 12 are respectively provided with a peristaltic pump 14, and the inner wall of the electrode chamber 4 is provided with filter paper.

In this embodiment, the eluent is stored in the first liquid storage chamber 2 , the anode repair liquid is stored in the second liquid storage chamber 3 , the cathode repair liquid is stored in the third liquid storage chamber 10 , and the overflow is stored in the fourth liquid storage chamber 11 liquid.

The method of utilizing the above-mentioned device to repair the composite heavy metal polluted soil comprises the following steps:

S1, leaching: According to the solid-liquid ratio of soil to leaching solution is 1g: 0.1~0.5ml, the leaching solution in the first liquid storage chamber is input into the soil chamber through the peristaltic pump, and the leaching and repairing time is 1-3 Days, after the rinsing is completed, empty the excess eluent; wherein, the eluent is EDTA-2Na solution and citric acid solution, the molar concentration of EDTA-2Na solution is 0.05-1.0mol/L, and the molar concentration of citric acid solution is 0.1-1.0 mol/L; in step S1, the flow rate of the eluent is controlled by a peristaltic pump to be 0.5-1.0 mL/min.

S2. Electric: apply an electric field to the leached polluted soil chamber, the voltage is 1-3V/cm, and the initial current is 0.1-0.4A; The pump controls the flow rate, and controls the height of the liquid level in the anode chamber to be consistent with the soil remediation height; the remediation solution in the third liquid storage chamber is input into the cathode electrode chamber through the peristaltic pump, the liquid level in the cathode chamber is consistent with the soil height, and the liquid level exceeds the set The height is automatically input into the fourth liquid storage chamber; the electrolysis time is 8 to 20 days; the restoration of heavy metal composite contaminated soil is completed, wherein the anode repair solution is citric acid, and the molar concentration is 0.1 to 1.0mol/L; the cathode repair solution is lemon acid, the molar concentration is 0.1-0.5mol/L; in addition, after repairing until the soil near the cathode chamber is compacted, S1 can be started again, and the eluent in the first liquid storage chamber is input into the soil of the cathode area through the peristaltic pump, Concurrent with electrodynamic restoration.

Example 1

The method for repairing composite heavy metal polluted soil includes the following steps: adding a 0.1mol/L citric acid solution of the eluent to the polluted soil according to a certain water-soil ratio of 0.5:1, stirring evenly, placing it for 24 hours, and discharging the excess solution. The porous electrode column is placed in the repair device, the inner wall of the electrode column is covered with a layer of filter paper, and then the columnar electrode is placed inside; the soil after leaching is moved to the electrodynamic repair device, and the anode repair solution is 0.3 mol/mol/L through a peristaltic pump. L citric acid solution was added to the anode chamber, and 0.1mol/L citric acid solution of cathodic repair solution was added to the cathode chamber. is 8d. Complete the remediation of heavy metal complex polluted soil. Take 20 soil points to measure the residual Pb and Cd content in the soil. The average removal rate of Pb was 72.2%, and the average removal rate of Cd was 60.9%.

Embodiment 2

The method for repairing composite heavy metal polluted soil includes the following steps: adding a 0.1mol/LEDTA-2Na solution of eluent to the polluted soil according to a certain water-soil ratio of 0.5:1, stirring evenly, placing it for 24 hours, and discharging excess solution. The porous electrode column is placed in the repair device, the inner wall of the electrode column is covered with a layer of filter paper, and then the columnar electrode is placed inside; the soil after leaching is moved to the electrodynamic repair device, and the anode repair solution is 0.3 mol/mol/L through a peristaltic pump. Add L citric acid solution to the anode chamber, add 0.1mol/L citric acid solution of cathodic repair solution to the cathode chamber, keep the same height as the soil to be repaired, turn on the power, the voltage is 2V/cm, the initial current is 0.8A, the repair time is 8d. Complete the remediation of heavy metal complex polluted soil. After restoration, 20 soil sites were taken to measure the residual Pb and Cd contents in the soil. The average removal rate of Pb was 81.3%, and the average removal rate of Cd was 71.6%.

The present invention and its embodiments have been described above, and the description is not restrictive, and what is shown in the accompanying drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. All in all, if those of ordinary skill in the art are inspired by it, and without departing from the purpose of the present invention, any structural modes and embodiments similar to this technical solution are designed without creativity, and all should belong to the protection scope of the present invention.

Claims (10)

1. The utility model provides a device of compound heavy metal contaminated soil is jointly restoreed in electronic-drip washing, a serial communication port, including DC power supply, first stock solution room, second stock solution room, third stock solution room, fourth stock solution room, electrode compartment and soil chamber, the electrode compartment sets up in the soil chamber, the quantity of electrode compartment is a plurality of, including being located the indoor middle electrode compartment of soil and setting up the peripheral electrode compartment around the middle electrode compartment, the electrode compartment is interior to be established and to be set up the electrode post respectively, the indoor electrode post of middle electrode is connected with the DC power supply negative pole, the indoor electrode post and the DC power supply positive pole of peripheral electrode are connected, first stock solution room stretches into the soil chamber through first drain pipe and connects the shower head, second stock solution room is connected with peripheral electrode compartment through the second drain pipe, third stock solution room, fourth stock solution room are respectively through third drain pipe, The fourth liquid outlet pipe is connected with the middle electrode chamber.

2. The device for remediating composite heavy metal contaminated soil by combining electrokinetic elution and leaching as claimed in claim 1, wherein the electrode chamber is a porous column, and the electrode column is a graphite electrode column.

3. The device for remediating the composite heavy metal contaminated soil through combination of electric leaching and leaching as claimed in claim 1, wherein the inner wall of the electrode chamber is provided with filter paper.

4. The device for remediating complex heavy metal contaminated soil by combining electric elution and elution as claimed in claim 1, wherein peristaltic pumps are respectively arranged on the first liquid outlet pipe, the second liquid outlet pipe and the third liquid outlet pipe.

5. The device for remediating complex heavy metal contaminated soil by combining electrokinetic-leaching according to claim 1, wherein an ammeter is connected to a cathode of the direct current power supply.

6. The device for remediating complex heavy metal contaminated soil by combining electrokinetic elution and elution as claimed in claim 1, wherein an elution agent is stored in the first liquid storage chamber, an anode remediation liquid is stored in the second liquid storage chamber, a cathode remediation liquid is stored in the third liquid storage chamber, and an overflow liquid is stored in the fourth liquid storage chamber.

7. The method for restoring the soil polluted by the compound heavy metal by combining electric leaching and leaching is characterized by comprising the following steps of:

s1, leaching: according to the solid-liquid ratio of 1g of soil to leacheate: 0.1-0.5 ml of leacheate in the first liquid storage chamber is input into the soil chamber through a peristaltic pump, the leaching and repairing time is 1-3 days, and after the leaching is finished, redundant leacheate is drained;

s2, electric driving: applying an electric field to the washed polluted soil chamber, wherein the voltage is 1-3V/cm, and the initial current is 0.1-0.4A; inputting the repairing liquid in the second liquid storage chamber into the anode electrode chamber through a peristaltic pump, controlling the flow rate through the peristaltic pump, and controlling the liquid level height of the anode chamber to be consistent with the height of the repaired soil; the repairing liquid in the third liquid storage chamber is input into the cathode electrode chamber through a peristaltic pump, the liquid level height of the cathode chamber is consistent with the soil height, and the repairing liquid is automatically input into the fourth liquid storage chamber when the liquid level height exceeds a set height; the electrolysis time is 8-20 days; and finishing the restoration of the heavy metal composite polluted soil.

8. The method for remediating the composite heavy metal contaminated soil through combination of electric leaching and leaching according to claim 1, wherein the leaching solution in the step S1 is EDTA-2Na solution and citric acid solution, the molar concentration of the EDTA-2Na solution is 0.05-1.0 mol/L, and the molar concentration of the citric acid solution is 0.1-1.0 mol/L; and in the step S1, the flow rate of the leacheate is controlled to be 0.5-1.0 mL/min through a peristaltic pump.

9. The method for remediating complex heavy metal contaminated soil by combining electrokinetic leaching and leaching according to claim 1, wherein the anode remediation solution in the step S2 is citric acid, and the molar concentration is 0.1-1.0 mol/L; the cathode repairing solution is citric acid, and the molar concentration is 0.1-0.5 mol/L.

10. The method for remediating complex heavy metal contaminated soil by combining electro-leaching and washing as claimed in claim 1, wherein the step S2 is performed until soil hardening phenomenon near the cathode chamber occurs, and then the step S1 is performed again, and the leachate in the first liquid storage chamber is pumped into the soil in the cathode region through a peristaltic pump, and the electro-leaching and washing are performed simultaneously with the electro-kinetic remediation.

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