CN104384179A - In-situ restoration apparatus for heavy metal pollutants in soil and restoration method thereof - Google Patents

Abstract

The invention belongs to the technical field of in-situ restoration of soil polluted by heavy metals, in particular to a device for in-situ restoration of heavy metal pollutants in soil and a restoration method thereof. The device of the invention is composed of three parts: an electrodynamic repair system, a heavy metal recovery system, and an electrode liquid recycling system. The invention uses an in-situ repairing device for heavy metal pollutants in soil and a repairing method thereof, which is beneficial to improving the solubility of heavy metal pollutants in soil and reducing their ability to adhere to soil. Compared with the traditional electrokinetic remediation method, it has the advantage of increasing the migration rate of heavy metal ions in the soil, thereby reducing the remediation time.

Description

A device and method for in-situ restoration of heavy metal pollutants in soil

technical field

The invention belongs to the technical field of in-situ restoration of soil polluted by heavy metals, in particular to a device for in-situ restoration of heavy metal pollutants in soil and a restoration method thereof. the

Background technique

At present, the research on the application of chelating agents for the remediation of metal pollution in soil, on the one hand, focuses on the chemical extraction rate of heavy metals or the extraction rate of induced plants; on the other hand, it mainly focuses on the residue and migration of chelating agents and the possible soil and Secondary pollution of groundwater. Organic chelating agents can complex with heavy metals in soil to form soluble organometallic complexes, which can increase the availability and mobility of heavy metals. Therefore, chelating agents are widely used in soil leaching and remediation of heavy metal-contaminated soils and inducing plant In remediation, there are related patents that apply chelating agents to soil remediation, but there is no patent that uses chelating agents as electrode fluids for electrodynamic restoration methods. [S,S]-Ethylenediamine disuccinic acid (abbreviated as [S,S]-EDDS) is a strong metal chelating agent that is easily biodegradable and has received extensive attention in recent years. The present invention uses chelating agent [S, S] ethylenediamine disuccinic acid ([S, S]-EDDS) as the electrode liquid of electromotive force, has increased the solubility of heavy metal pollutant greatly, has reduced the adhesion of heavy metal pollutant in The amount in the soil can effectively reduce the time for the electrodynamic method to deal with heavy metal pollutants. At the same time, the remaining [S,S]-EDDS in the soil can be decomposed by microorganisms in the soil without secondary pollution to the soil. the

Contents of the invention

In order to overcome the deficiencies in the prior art, the present invention provides an in-situ repairing device for heavy metal pollutants in soil and a repairing method thereof. the

A device and method for in-situ repairing heavy metal pollutants in soil, the device is composed of three parts: an electrodynamic repair system, a heavy metal recovery system, and an electrode solution recycling system; the electrodynamic repair system includes an anode chamber and a cathode chamber , anode, cathode, power transformer, anolyte storage tank, catholyte storage tank, anode transfer pump, cathode transfer pump, anode monitor, cathode monitor; the heavy metal recovery system is connected with the anode recovery pipeline and cathode recovery pipeline respectively The anode chamber and cathode chamber of the electrodynamic restoration system are connected, and the heavy metal recovery system is composed of an anode recovery pipeline, a cathode recovery pipeline, an anode output pump, a cathode output pump, an anode heavy metal recovery treatment device, and a cathode heavy metal recovery treatment device; The liquid recycling system connects the anode heavy metal recovery processing device with the catholyte storage tank through the return pipeline. the

In the electrodynamic restoration system, the anode chamber and the cathode chamber are arranged underground, and the anode and the cathode are respectively inserted into the anode chamber and the cathode chamber; the positive pole of the power transformer is connected to the anode, and the negative pole of the power transformer is connected to the cathode; The anolyte liquid is pumped to the anode chamber through the anode transport, and the catholyte liquid in the catholyte storage tank is pumped to the cathode chamber through the cathode transport; the anode chamber and the cathode chamber are respectively equipped with an anode monitor and a cathode monitor. the

In the heavy metal recovery system, the anode chamber is connected to the anode output pump, and the anode output pump is connected to the anode heavy metal recovery treatment device through the recovery pipeline. The position and connection relationship of the cathode chamber and its corresponding cathode output pump, recovery pipeline, and cathode heavy metal recovery and processing device are the same as those of the anode chamber and its corresponding anode output pump, recovery pipeline, and anode heavy metal recovery and processing device. The positions and connections are the same. the

In the electrode liquid recycling system, the electrode liquid recovered by the anode heavy metal recovery and treatment device is treated and then returned to the catholyte storage tank through the return pipeline. the

A device for repairing heavy metal pollutants in soil in situ and a repair method thereof, the specific steps are as follows:

(1) Turn on the electrodynamic repair system and prepare the anolyte and catholyte: use sodium nitrate (NaNO ₃ ) as the anolyte with a concentration of 0.01mol/L~0.05mol/L; use [S,S]-B Trisodium diaminedisuccinate (Na ₃ -[S,S]-EDDS) is used as catholyte, the concentration is 0.1mol/L~1mol/L;

(2) Inject the prepared anolyte solution and catholyte solution into the electrode solution storage tank respectively, turn on the anode transfer pump and the cathode transfer pump to inject the electrode solution into the anode chamber and the cathode chamber respectively; Value is adjusted at 8.0～9.0, and the anolyte liquid pH value is adjusted at 6.5～7.5, and described pH adjustment liquid is the NaOH solution that mass fraction is 1% and the HNO solution that mass fraction is ₁ %;

(3) Turn on the power transformer to supply power to the anode and cathode, and form a DC electric field in the polluted area. Under the action of the DC electric field, Na ₃ -[S,S]-EDDS is decomposed into ([S,S]-EDDS) ^3- and Na ⁺ , among them, ([S,S]-EDDS) ^3- enters the soil polluted by heavy metals under the action of an electric field and forms [metal-EDDS] ^n- ions with high solubility with heavy metals, [metal- EDDS] ^-ions continue to move to the anode under the action of a DC electric field; [metal-EDDS] ^n- ions are finally enriched in the anode area, and there are no heavy metal ions that chelate with ([S,S]-EDDS) ^3- It will be enriched in the cathode region under the action of a DC electric field;

(4) When the monitor detects that the electrode solution is saturated, the feedback controller stops the electrodynamic repair system, starts the heavy metal recovery system, and pumps out the anolyte and catholyte in the anode chamber and cathode chamber respectively and sends them to the corresponding Heavy metal recycling and processing equipment for processing;

(5) Turn off the heavy metal recovery system, turn on the electrodynamic repair system, make the anode transfer pump and cathode transfer pump pour new anode electrode solution and cathode electrode solution into the anode chamber and cathode chamber, and repeat the steps from the first to the fourth steps above;

(6) The electrode liquid recovered by the anode heavy metal recovery treatment device is treated and then returned to the catholyte storage tank through the return line;

(7) When the concentration of heavy metals recovered by the heavy metal recovery and treatment device reaches the processing target concentration, the device for in-situ restoration of heavy metal pollutants in the soil stops operating.

In order to reduce the electrodynamic restoration time and enhance the electrodynamic restoration effect, this method adopts the method of arranging the cathode electrode and the anode electrode at intervals to arrange the cathode electrode and the anode electrode in the soil area polluted by heavy metals. The specific arrangement is shown in Figure 2. the

The advantages of the present invention are:

1. The metal chelating agent [S,S]-EDDS is added on the basis of electrodynamic force, which is beneficial to improve the solubility of heavy metal pollutants in the soil and reduce their ability to adhere to the soil. Compared with the traditional electrodynamic remediation method, it has the advantage of increasing the migration rate of heavy metal ions in the soil, thereby reducing the remediation time;

2. The chelating agent [S,S]-EDDS is directly added to the catholyte, no need to add other dosing equipment and injection wells, the equipment is convenient and compact, simple and easy;

3. The present invention is applicable to geological conditions with various conditions, and has less secondary pollution to polluted soil. [S,S]-EDDS has strong biodegradability. After the treatment, the remaining [S,S]-EDDS in the soil can be decomposed by the degradation of microorganisms in the soil, and will not cause long-term damage to the soil. pollution, more environmentally friendly.

Description of drawings

The content of the present invention is illustrated in conjunction with the accompanying drawings. Fig. 1 is a schematic diagram of the device structure of the present invention, and Fig. 2 is a schematic diagram of electrode layout in the polluted soil area

Labels in the figure: 101, 201-anolyte storage tank, catholyte storage tank, 201, 202-anolyte transfer pump, catholyte transfer pump, 301, 302-anode output pump, cathode output pump, 4-power transformer , 5-anode, 6-cathode, 7-anode chamber, 8-cathode chamber, 901, 902-anode monitor, cathode monitor, 1001, 1002-anode heavy metal recovery processing device, cathode heavy metal recovery processing device, 11-anode Recovery pipeline, 12-cathode recovery pipeline, 13-soil area contaminated by heavy metals, 14-return pipeline.

Detailed ways

The present invention provides a [S,S]-EDDS enhanced electrodynamic method for remediating heavy metal pollutants in soil. The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods. the

The specific device layout is shown in Figure 1. the

The direct current voltage used in the example is 20V, the chelating agent is Na ₃ -[S,S]-EDDS (C ₁₀ H ₁₃ N ₂ Na ₃ O ₈ ), the concentration is 0.625mol/L, and the electrode is made of platinum material. The heavy metal to be treated is lead, and the lead content in the soil is about 8.0×10 ^-4 mol/L. The main operation steps of the example are as follows:

1. Prepare 0.625mol/L Na ₃ -[S,S]-EDDS solution, and put it into the catholyte storage tank (201), prepare 0.01mol/L NaNO ₃ solution, and put it into the anode In the liquid storage tank (101);

2. Turn on the anolyte transfer pump (201) and the catholyte transfer pump (202), respectively feed the anolyte and catholyte into the anode chamber (7) and the cathode chamber (8); the anode liquid fills the anode chamber (7) After the cathode chamber (8), adjust the pH value of the electrode solution with a mass fraction of 1% NaOH solution and a mass fraction of 1% _HNO3 solution to adjust the pH value of the catholyte to 8.0 and adjust the pH value of the anolyte to 7.0;

3. Turn on the power transformer (4) anode (5) and cathode (6) to supply power to deal with heavy metal lead pollutants in the soil. When the monitor detects that the electrode solution is saturated, stop the electrodynamic recovery system, start the heavy metal recovery system, and pump out the anolyte and catholyte from the anode chamber and cathode chamber respectively and send them to the anode heavy metal recovery device (1001) and in the cathode heavy metal recovery device (1002);

4. Turn off the heavy metal recovery system, turn on the electrodynamic restoration system, and make the anode transfer pump (201) and the cathode transfer pump (202) pour new anode electrode solution and cathode electrode solution into the anode chamber (7) and cathode chamber (8) respectively , repeat the steps from the first to third steps above;

5. The electrode solution recovered by the anode heavy metal recovery treatment device is processed and then returned to the catholyte storage tank (201) through the return line (14);

6. When the accumulated electric power treatment time reaches 480 hours, stop the power supply and end the soil restoration process;

7. After the treatment, the content of heavy metal lead in the soil is about 7×10 ^-5 mol/L, and the results show that the effect of this method on the treatment of heavy metal lead pollution in soil can reach 91%.

Claims (3)

1. the device of in-situ immobilization heavy metal in soil pollutant and a restorative procedure thereof, is characterized in that: this device is made up of Electroremediation system, heavy metal recovery system, electrode solution circulation recycling system three parts; Electroremediation system comprises anode chamber, cathode chamber, anode, negative electrode, power transformer, anolyte storage box, catholyte storage box, anode transmission pump, cathode transport pump, anode monitor, negative electrode monitor composition; Heavy metal recovery system is connected with the anode chamber of Electroremediation system, cathode chamber respectively by anode reclaim line, negative electrode reclaim line, heavy metal recovery system by anode reclaim line, negative electrode reclaim line, anode spreads out of pump, negative electrode spreads out of pump, anode heavy metal recovery treating apparatus, negative electrode heavy metal recovery treating apparatus form; Anode heavy metal recovery treating apparatus is connected with catholyte storage box by return line by electrode solution circulation recycling system;

In described Electroremediation system, anode chamber and cathode chamber are arranged at underground, and anode and negative electrode insert anode chamber and cathode chamber respectively; The positive pole of power transformer is connected with anode, and the negative pole of power transformer is connected with negative electrode; Anode electrode liquid in anolyte storage box delivers to anode chamber by anode transmission pump, and the cathode electrode liquid in catholyte storage box is pumped to cathode chamber by cathode transport; Anode chamber and cathode chamber arrange anode monitor and negative electrode monitor respectively;

In described heavy metal recovery system, anode chamber and anode spread out of pump and are connected, and anode spreads out of pump and is connected with anode heavy metal recovery treating apparatus with through reclaim line; Described cathode chamber negative electrode corresponding thereto spreads out of pump, reclaim line, the position of negative electrode heavy metal recovery treating apparatus and annexation, spreads out of pump, reclaim line, the position of anode heavy metal recovery treating apparatus and annexation identical with anode chamber's anode corresponding thereto;

In described electrode solution circulation recycling system, the electrode solution that anode heavy metal recovery treating apparatus reclaims is back to catholyte storage box through return line after treatment.

2. the device of a kind of in-situ immobilization heavy metal in soil pollutant as claimed in claim 1 and restorative procedure thereof, it is characterized in that, concrete steps are as follows:

Open Electroremediation system, allotment anode electrode liquid and cathode electrode liquid: use sodium nitrate (NaNO ₃) as anode electrode liquid, concentration is 0.01mol/L ~ 0.05mol/L; Use [S, S]-EDDS trisodium (Na ₃-[S, S]-EDDS) as cathode electrode liquid, concentration is 0.1mol/L ~ 1mol/L;

By in deployed anode electrode liquid and cathode electrode liquid difference injecting electrode liquid storage bin, open anode transmission pump, electrode solution is injected anode chamber and cathode chamber by cathode transport pump respectively; With pH regulator solution, cathode electrode liquid pH value is regulated 8.0 ~ 9.0, anode electrode liquid pH value is regulated 6.5 ~ 7.5, described pH regulator solution to be mass fraction be 1% NaOH solution and mass fraction be the HNO of 1% ₃solution;

Power-on transformer antianode and negative electrode are powered, and form DC electric field at Polluted area, under the effect of DC electric field, and Na ₃-[S, S]-EDDS is decomposed into ([S, S]-EDDS) ^3-and Na ⁺, wherein, ([S, S]-EDDS) ^3-under the effect of electric field, enter into contaminated by heavy metals soil and form dissolubility higher [metal-EDDS] with heavy metal ^n-ion, [metal-EDDS] ^-ion continues anode and moves under the effect of DC electric field; [metal-EDDS] ^n-ion is finally enriched in anode region, not with ([S, S]-EDDS) ^3-the heavy metal ion that chelatropic reaction occurs can be enriched to cathodic region under the effect of DC electric field;

When monitor monitors is saturation state to electrode solution, feedback controller, stop Electroremediation system works, open heavy metal recovery system, by anode chamber and cathode chamber anode electrode liquid and cathode electrode liquid extract out respectively and deliver to corresponding heavy metal recovery treating apparatus and process;

Close heavy metal recovery system, open Electroremediation system, make anode transmission pump and cathode transport pump anode room and cathode chamber pour into new anode electrode liquid and cathode electrode liquid, repeat the step of above first to fourth step;

The electrode solution that anode heavy metal recovery treating apparatus reclaims is back to catholyte storage box through return line after treatment;

After during heavy metal recovery treating apparatus reclaims, heavy metal concentration reaches processing target concentration, the device of in-situ immobilization heavy metal in soil pollutant is out of service.

3. the device of a kind of in-situ immobilization heavy metal in soil pollutant as claimed in claim 1 and restorative procedure thereof, it is characterized in that, in order to reduce the Electroremediation time, strengthen Electroremediation effect, this method adopts the method for yin, yang electrode gap arrangement that cathode electrode and anode electrode are arranged in contaminated by heavy metals soil region.