CN110871213B - Lead-polluted soil stabilization/solidification remediation method - Google Patents
Lead-polluted soil stabilization/solidification remediation method Download PDFInfo
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- CN110871213B CN110871213B CN201911137548.XA CN201911137548A CN110871213B CN 110871213 B CN110871213 B CN 110871213B CN 201911137548 A CN201911137548 A CN 201911137548A CN 110871213 B CN110871213 B CN 110871213B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/08—Reclamation of contaminated soil chemically
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
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Abstract
The invention discloses a method for stabilizing/solidifying and repairing lead-polluted soil, which adds ferrous sulfate solution into heavy metal lead-polluted soil and leads the soil to be stabilized/solidifiedOver Fe2+By oxidation of+The pH value of the soil is reduced, and the transformation of unstable form lead in the soil to an effective form is promoted; adding biochar and phosphate into the heavy metal lead polluted soil again, and enabling the effective lead to further form a lead compound in a stable residue state through adsorption, complexation, cation exchange, precipitation and other modes between the biochar and the phosphate and lead ions; thereby reducing the bioavailability of heavy metal, reducing the content of effective heavy metal in the soil and realizing the adsorption and stabilization treatment of lead. The repairing method can lead the leaching concentration of the leachate in the lead-containing polluted soil to be lower than the class III water quality standard (0.01mg/L) in the ground water quality standard (GBT 14848-2017).
Description
Technical Field
The invention relates to the technical field of soil remediation, in particular to a remediation method for stabilizing/curing lead-polluted soil.
Background
With the development of economy in China, the industrial development is rapid, cities continuously expand the development scale for the development of economy, electroplating, chemical engineering and mechanical processing enterprises are gradually increased, more and more processing waste materials contain a large amount of heavy metal lead, and industrial wastewater is discharged into soil without being treated, so that the content of heavy metal lead in the soil is greatly increased. In addition, in the process of developing agriculture in China, the use of a large amount of pesticides increases the soil pollution degree to a certain extent, and heavy metal lead is continuously accumulated in soil, so that the heavy metal lead causes great harm to the healthy growth of crops, and the health of people is greatly threatened. In addition, in the process of mining nonferrous metals, a large amount of metals are accumulated, so that toxic metals enter soil, and the soil is polluted.
Lead (Pb) is one of the most toxic heavy metals reported at present, and researches find that lead and lead compounds are non-degradable environmental pollutants, are easy to accumulate in microbial communities and cause irreversible severe damage to the growth and intelligence development of children. The content of heavy metal in the human body exceeds the standard, obvious damage can be generated to the normal metabolism process of the human body, the normal operation of the body function of the human body is inhibited, and then various diseases are promoted to occur, such as the blood lead exceeding event is frequently exposed. After Pb enters brain tissues, the nervous system can be seriously damaged, and brain development is influenced. Therefore, the research and development of related technologies are needed to repair and treat the heavy metal lead contaminated soil.
The research on soil heavy metal restoration technology at home and abroad can be divided into the following steps according to principles and methods: physical repair methods, chemical repair methods, and biological repair methods. The chemical repairing stabilization/solidification repairing technology is a rapid soil repairing technology, and the curing agent/stabilizing agent is added into the polluted soil, and is fully mixed with the pollutants to generate physical and chemical effects, so that the polluted soil is sealed into a solidified body with a complete structure and a low permeability coefficient, or the pollutants are converted into a chemically inactive form, and the migration and diffusion of the pollutants in the environment are reduced. At present, the stabilization/solidification remediation technology becomes a soil remediation technology which is widely applied at home and abroad due to the advantages of low cost, quick response, high remediation efficiency and the like.
Although the stabilization/solidification remediation technology is an effective soil treatment technology, pollutants in soil are not extracted, and exposure of the pollutants and a source of migratory lead pollution are blocked by adding a medicament, and the technical bottleneck of the existing stabilization/solidification remediation technology is that the stability of remediation effect, the environmental friendliness of remediation medicament and the economical problem of remediation implementation need to be solved urgently.
Disclosure of Invention
In order to solve the problem of secondary pollution possibly caused by the influences of re-dissolution after the heavy metal lead polluted soil in the soil is repaired and salinization and the like of the soil caused by traditional agents in the prior art, the invention provides a method for stabilizing/curing the lead polluted soil, which has the advantages of low cost and regulation and control effect on the soil by converting the combined heavy metal lead in the soil into an effective state and then into a residue state, and realizes the lasting and thorough mineralization and stabilization repair of the heavy metal lead in the soil.
The invention discloses a lead polluted soil stabilization/solidification repairing method, which comprises the following steps:
adding a ferrous sulfate solution into the heavy metal lead polluted soil to convert unstable lead in the soil into an effective state;
and adding biochar and phosphate into the heavy metal lead polluted soil again, and forming a lead compound in a stable residue state through adsorption, combination and precipitation between the biochar and the phosphate and lead ions.
As a further improvement of the invention, the heavy metal lead-polluted soil comprises five forms of lead in an effective state, a carbonate combined state, a ferro-manganese oxide combined state, an organic matter combined state and a residue state.
As a further improvement of the invention, the concentration of the ferrous sulfate solution is controlled to be (20-30) g/kg in terms of ferrous iron;
the ferrous sulfate solution is prepared by industrial ferrous sulfate heptahydrate with the content of 95 percent.
As a further improvement of the invention, after the ferrous sulfate solution is added into the heavy metal lead polluted soil,
and (3) uniformly stirring the soil, keeping the water content of the soil and adjusting the acid environment of the soil.
As a further improvement of the present invention,
continuously stirring the polluted soil for 5-10 min by magnetic stirring according to the soil property and the water content;
controlling the water content of the soil to be 4: 1-8: 1 in a solid-liquid ratio;
the pH value of the acid environment of the soil is controlled to be 5-6.5.
As a further improvement of the invention, the adding amount of the biochar is controlled to be 4-10 g/kg.
As a further improvement of the invention, the biochar is acidic biochar which is obtained by firing aquatic plants which adsorb heavy metals in a water culture mode in a muffle furnace at 680 ℃.
As a further improvement of the present invention, the phosphate is sodium dihydrogen phosphate;
the addition amount of the sodium dihydrogen phosphate is controlled to be 16-40 g/kg in terms of phosphate;
the sodium dihydrogen phosphate is prepared by granular solid with the industrial grade content of 98 percent.
As a further improvement of the invention, the biochar and the phosphate are added into the heavy metal lead polluted soil again, and then the mixture is fully and uniformly stirred for maintenance.
As a further improvement of the invention, the curing conditions are as follows:
and (5) storing the soil in a 4 ℃ thermostat in a sealed manner for 5-7 days.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, by changing the form distribution of heavy metal lead in soil, the unstable form is converted into the effective state and further converted into the stable residue state, so that the leaching rate of heavy metal is reduced, and the stability is more durable;
2. the invention uses the remediation agent of essential elements in the soil, not only has the effect of stabilizing/solidifying, but also has the function of regulating and controlling the physical and chemical environment of the soil, and the remediation agent is cheap and does not cause secondary pollution to the soil environment;
3. the invention is formed by burning the aquatic plants absorbing the heavy metal in the soil by using the biochar, further absorbs the heavy metal polluted soil, and has the advantages of changing waste into valuable and recycling.
Detailed Description
In order to make the objects, 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, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The invention is described in further detail below:
the invention provides a method for stabilizing/solidifying and repairing lead-polluted soil, which is characterized in that ferrous sulfate solution is added into heavy metal lead-polluted soil, and Fe is used for dissolving2+By oxidation of+The pH value of the soil is reduced, and the transformation of unstable form lead in the soil to an effective form is promoted; adding biochar and phosphate into the heavy metal lead polluted soil again, and enabling the effective lead to further form a lead compound in a stable residue state through adsorption, complexation, cation exchange, precipitation and other modes between the biochar and the phosphate and lead ions; thereby reducing the bioavailability of heavy metal, reducing the content of effective heavy metal in the soil and realizing the adsorption and stabilization treatment of lead. The repairing method can lead the leaching concentration of the leachate in the lead-containing polluted soil to be lower than the class III water quality standard (0.01mg/L) in the ground water quality standard (GBT 14848-2017). The method can realize the stabilization of heavy metal lead in the soil, has low leaching rate of the heavy metal lead in the soil after remediation, obviously enhances the stability of the heavy metal lead in the soil, and can be used for remediation treatment of the soil polluted by the heavy metal lead.
The invention provides a lead contaminated soil stabilization/solidification repairing method, which comprises the following steps:
s1, preparing a ferrous sulfate solution with a certain mass concentration, adding the ferrous sulfate solution into the heavy metal lead polluted soil, uniformly stirring the soil, keeping the water content of the soil, and adjusting the acid environment of the soil; wherein:
the heavy metal lead polluted soil comprises lead in five forms, namely an effective state, a carbonate combined state, a ferro-manganese oxide combined state, an organic matter combined state and a residue state.
The concentration of the ferrous sulfate solution prepared by the invention is controlled to be (20-30) g/kg in terms of ferrous;
the ferrous sulfate solution is prepared by ferrous sulfate heptahydrate with the industrial level content of 95 percent;
the soil water content is controlled to be 4: 1-8: 1 in a solid-liquid ratio;
the pH value of the acid environment of the soil is controlled to be 5-6.5.
S2, adding biochar in a certain mass ratio into the heavy metal lead polluted soil treated in the S1, and uniformly stirring; after stabilizing for a period of time, continuously adding phosphate with a certain mass proportion into the heavy metal lead polluted soil; fully and uniformly stirring and curing; wherein:
the adding amount of the biochar is controlled to be 4-10 g/kg.
The biochar of the invention is acidic biochar which is formed by firing aquatic plants (such as cattail, calamus, Siberian iris, reed and the like) which adsorb heavy metals in a water culture mode in a muffle furnace at 680 ℃.
The phosphate is preferably sodium dihydrogen phosphate, and the addition amount of the sodium dihydrogen phosphate is controlled to be 16-40 g/kg in terms of the phosphate;
the sodium dihydrogen phosphate is prepared by granular solid with the industrial-grade content of 98 percent.
The curing conditions of the invention are as follows: and (5) storing the soil in a 4 ℃ thermostat in a sealed manner for 5-7 days.
Based on the above repair method of the present invention, experiments were performed:
example 1
In a certain heavy metal lead polluted site in Shanghai, the average concentration of heavy metal lead pollution in soil is 10500mg/kg, and according to morphological analysis, the effective state content of heavy metal lead in the polluted soil is determined to be 37.4%, and the residue state content is determined to be 32.8%. The contaminated soil adopts a stabilization/solidification repairing process, and FeSO with the mass concentration of 40 percent is sprayed into the contaminated soil through a fog gun machine4Adding ferrous sulfate with the mass ratio of 2% into the polluted soil, stirring and turning by an excavator to keep the water content in the soil to be 40%, and then respectively adding 0.5% of biochar and sodium dihydrogen phosphate solid powder into the polluted soil, wherein the mass ratio of the biochar to the sodium dihydrogen phosphate is 1: and 4, turning and throwing the mixture for three times by using an ALLU screening crusher, stirring the mixture once every 24 hours, and maintaining the mixture for 7 days. The effective state content of heavy metal lead in the soil is determined to be 11.7 percent and the residue state content is determined to be 68.6 percent by adopting a Tessier five-step analysis method, and the effective state content of heavy metal lead in the soil is determined to be 11.7 percent by adopting a toxic leaching (TCLP) sulfuric acid-nitric acid method (HJ T29) of a solid waste leaching toxicity leaching method (TCLP)9-2007) testing the leaching concentration of heavy metal lead in soil to be less than 0.0042 mg/L.
Example 2
In a heavy metal polluted site of a lead-zinc mine field in Yunnan, the average heavy metal lead pollution concentration in soil is 21750mg/kg, the effective state content of lead in heavy metal morphological analysis accounts for 47.6%, the residue state content accounts for 21.9%, a stabilization/solidification repair process is adopted, and FeSO with the mass concentration of 50% is added through soil repair integrated equipment4Adding 1% of biochar and sodium dihydrogen phosphate solid powder into the solution, wherein the adding concentration of ferrous sulfate in the soil is 3%, the mass ratio of the biochar to the sodium dihydrogen phosphate is 1:2, and maintaining for 7 days. The effective state content of heavy metal lead in the soil is determined to be 14.8% and the residue state content is determined to be 72.4% by adopting a Tessier five-step analysis method, and the leaching concentration of the heavy metal lead in the soil is detected to be 0.0083mg/L by a toxicity leaching (TCLP) sulfuric acid-nitric acid method (HJ T299-2007) experiment of a solid waste leaching toxicity leaching method.
The invention has the advantages that:
1. according to the invention, by changing the form distribution of heavy metal lead in soil, the unstable form is converted into the effective state and further converted into the stable residue state, so that the leaching rate of heavy metal is reduced, and the stability is more durable;
2. the invention uses the remediation agent of essential elements in the soil, not only has the effect of stabilizing/solidifying, but also has the function of regulating and controlling the physical and chemical environment of the soil, and the remediation agent is cheap and does not cause secondary pollution to the soil environment;
3. the invention is formed by burning the aquatic plants absorbing the heavy metal in the soil by using the biochar, further absorbs the heavy metal polluted soil, and has the advantages of changing waste into valuable and recycling.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. 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 (7)
1. A method for stabilizing/curing lead-contaminated soil, comprising:
step 1, adding a ferrous sulfate solution into heavy metal lead polluted soil to convert unstable-form lead in the soil into an effective state; wherein the concentration of the ferrous sulfate solution is controlled to be (20-30) g/kg in terms of ferrous;
step 2, uniformly stirring the soil, keeping the water content of the soil, and adjusting the soil to an acid environment with the pH of 5-6.5;
step 3, adding biochar and phosphate into the heavy metal lead polluted soil again, and forming a lead compound in a stable residue state through adsorption, combination and precipitation between the biochar, the phosphate and lead ions; the acidic biomass charcoal is formed by firing aquatic plants, which adsorb heavy metals in a water culture manner, in a muffle furnace at 680 ℃, wherein the addition amount of the biomass charcoal is controlled to be 4-10 g/kg, and the addition amount of phosphate is controlled to be 16-40 g/kg.
2. The remediation method of claim 1 wherein the heavy metal lead contaminated soil comprises lead in five forms, namely, available form, carbonate-bound form, iron manganese oxide-bound form, organic matter-bound form, and sludge form.
3. The method of claim 1, wherein the ferrous sulfate solution is formulated with a technical grade of 95% ferrous sulfate heptahydrate.
4. The repair method according to claim 1,
continuously stirring the polluted soil for 5-10 min by magnetic stirring according to the soil property and the water content;
the water content of the soil is controlled to be 4: 1-8: 1 in a solid-liquid ratio.
5. The repair method of claim 1, wherein the phosphate salt is sodium dihydrogen phosphate;
the sodium dihydrogen phosphate is prepared by granular solid with the industrial grade content of 98 percent.
6. The remediation method of claim 1 wherein the soil contaminated with heavy metal lead is maintained by adding biochar and phosphate to the soil again and stirring the mixture thoroughly.
7. The repair method according to claim 6, wherein the maintenance conditions are:
and (5) storing the soil in a 4 ℃ thermostat in a sealed manner for 5-7 days.
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CN111676022B (en) * | 2020-04-24 | 2021-03-02 | 浙江海洋大学 | Method for remedying heavy metal pollution of soil |
CN112692047B (en) * | 2020-12-08 | 2022-12-13 | 中国科学院沈阳应用生态研究所 | Soil heavy metal stabilization method based on morphological transformation |
CN112916607B (en) * | 2021-01-26 | 2022-10-04 | 广东中科碧城环境技术有限公司 | Stabilization restoration method for heavy metal contaminated soil |
CN113042001B (en) * | 2021-03-26 | 2022-01-14 | 维塔探索(广东)科技有限公司 | Porous biochar for improving severe pollution and preparation method thereof |
CN114393021B (en) * | 2021-12-27 | 2022-11-29 | 中国科学院沈阳应用生态研究所 | Thermal desorption and stabilization synergic remediation method for composite contaminated soil |
CN114525137A (en) * | 2021-12-27 | 2022-05-24 | 重庆中天海智生态环境科技有限公司 | Heavy metal lead polluted soil stabilizer and preparation method thereof |
CN114918240A (en) * | 2022-04-19 | 2022-08-19 | 四川轻化工大学 | Heavy metal soil remediation method based on biochar |
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CN109092878A (en) * | 2018-07-04 | 2018-12-28 | 北京高能时代环境技术股份有限公司 | It is a kind of for handling the stabilization agent and method of heavy-metal composite pollution soil |
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