Heavy metal organic matter contaminated soil leaching remediation method

Abstract

The invention relates to the technical field of soil remediation, in particular to a heavy metal organic matter contaminated soil leaching remediation method which comprises the following steps that S1, heavy metal and organic matter contaminated soil to be remediated is screened and crushed; s2, carrying out pre-oxidation treatment; s3, preparing a leacheate; s4, the pretreated soil is mixed with leacheate, and leaching is conducted for multiple times; s5, suspended solids in the waste liquid are separated; s6, adding a flocculating agent into the separated waste liquid to precipitate and separate pollutants in the waste liquid; s7, the washed soil is washed with clear water; s8, the cleaned soil is subjected to drying treatment; s9, the repaired soil is detected; through combined application of the chelating agent, the surfactant and the oxidizing agent, heavy metal and organic pollutants in soil can be efficiently removed, secondary pollution is reduced through multi-step treatment, reutilization after soil remediation is achieved, and high efficiency, environment friendliness and economical efficiency are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and in particular to a method for leaching and remediating soil contaminated by heavy metal organic matter. Background Art

[0002] With the rapid development of industry and agriculture, soil pollution has become increasingly serious, especially the pollution of heavy metals and organic matter, which has become one of the major challenges of global environmental pollution. Heavy metals such as lead, cadmium, mercury and other substances are highly toxic and persistent, difficult to degrade through natural processes, and accumulate in the soil for a long time, causing serious harm to crops and ecosystems; at the same time, organic pollutants such as polycyclic aromatic hydrocarbons, polychlorinated biphenyls (PCBs) and other difficult-to-degrade organic compounds have strong residual and toxicity in the soil, affecting the soil microbial community and ecological balance, and thus threatening human health and food safety.

[0003] Existing soil remediation technologies such as physical, chemical and biological methods can remove some pollutants to a certain extent, but they have many shortcomings. For example, physical methods are difficult to completely remove deep pollutants, chemical remediation technology is prone to secondary pollution and has a high remediation cost, and biological remediation is limited by environmental conditions, has a long remediation cycle and low efficiency. Therefore, the existing technology urgently needs an efficient remediation method that can remove heavy metals and organic pollutants at the same time to solve the above problems. Summary of the invention

[0004] Based on the above purpose, the present invention provides a method for leaching and remediation of soil contaminated by heavy metal organic matter.

[0005] A method for leaching and remediating soil contaminated by heavy metal organic matter, comprising the following steps:

[0006] S1: Screen and crush the heavy metal and organic polluted soil to be remediated, and preliminarily detect the type and content of pollutants;

[0007] S2: Pre-oxidation treatment is performed on soils containing high concentrations of organic pollutants to promote the decomposition of some refractory organic matter by introducing oxidants;

[0008] S3: preparing an eluent containing a chelating agent and a surfactant, and adjusting the pH value of the eluent to a predetermined range, for removing heavy metals and organic pollutants from the soil;

[0009] S4: mixing the soil pretreated in S2 with the elution solution prepared in S3 according to a predetermined ratio, and eluting for multiple times by intermittent stirring;

[0010] S5: During the elution process, the suspended matter in the waste liquid is separated by a filtering device;

[0011] S6: adding a flocculant to the separated waste liquid to precipitate and separate the pollutants in the waste liquid, and the treated supernatant needs to be recycled and reused;

[0012] S7: Rinse the washed soil with clean water to remove residual elution and pollutants;

[0013] S8: drying the cleaned soil to remove excess water, and conditioning the soil to restore its physical and chemical properties;

[0014] S9: Test the repaired soil to confirm whether the heavy metal and organic matter content meets the standards.

[0015] Optionally, the S1 specifically includes:

[0016] S11: The heavy metal and organic polluted soil to be remediated is screened through a screening device, with the screen aperture set at 1 mm to 5 mm to separate larger particles and impurities;

[0017] S12: Using a crushing device to crush the sieved soil so that the soil particle size is controlled to be 0.1 mm to 5 mm;

[0018] S13: Use gas chromatograph to conduct preliminary detection of organic pollutants and obtain the type and concentration data of pollutants.

[0019] Optionally, the S2 specifically includes:

[0020] S21: For soils with organic pollutant concentrations higher than 500 mg / kg, pre-oxidation treatment is selected;

[0021] S22: adding sodium persulfate or hydrogen peroxide as an oxidant to the soil to be treated, wherein the amount of the oxidant added is 0.5% to 2% of the soil mass;

[0022] S23: stirring the soil and the oxidant in a stirring device, and the stirring time is 30 minutes to 90 minutes.

[0023] Optionally, the S3 specifically includes:

[0024] S31: adding a chelating agent, disodium edetate or sodium citrate, to water at a mass ratio of 0.1% to 0.5% of the weight of the soil;

[0025] S32: adding a surfactant, sodium lauryl sulfate, in an amount of 0.05% to 0.2% of the mass of the water;

[0026] S33: stirring and mixing the above solution at a stirring speed of 200 to 500 rpm for 10 to 30 minutes;

[0027] S34: Adjust the pH of the eluent to 4.5 to 7.0 by adding sodium hydroxide or hydrochloric acid.

[0028] Optionally, the S4 specifically includes:

[0029] S41: mixing the soil pretreated in S2 with the eluent prepared in S3 at a ratio of soil mass to eluent volume of 1:2 to 1:5;

[0030] S42: After mixing the soil and the elution solution, place the mixture in a stirring device and stir it intermittently, with each stirring lasting 10 to 20 minutes, the stirring interval being 5 to 15 minutes, and the stirring times being 3 to 6 times;

[0031] S43: After each stirring, let the mixture of soil and eluent stand for 5 to 10 minutes to allow the contaminants to fully contact the eluent and dissolve.

[0032] Optionally, the S5 specifically includes:

[0033] S51: During the elution process, the waste liquid is treated by a filtration device, wherein the filtration device is a microfiltration membrane or an ultrafiltration membrane, and the filtration pore size is 0.01 μm to 0.1 μm;

[0034] S52: the waste liquid passes through the filter device at a flow rate of 0.5 L / min to 2 L / min;

[0035] S53: Regularly clean the suspended matter on the filter membrane to prevent clogging. Clean the membrane after each filtration operation lasts 30 to 60 minutes.

[0036] Optionally, the S6 specifically includes:

[0037] S61: placing the separated waste liquid in a stirring device, and adding a flocculant at 0.01% to 0.05% of the volume of the waste liquid, wherein the flocculant is polyacrylamide or aluminum sulfate;

[0038] S62: After adding the flocculant, stirring is performed at a stirring speed of 50 to 150 revolutions per minute for a continuous stirring time of 10 to 30 minutes to ensure that the flocculant and the waste liquid are fully mixed;

[0039] S63: After stopping stirring, the waste liquid is allowed to stand for 30 to 60 minutes to allow the pollutant particles to settle and separate under the action of gravity to form a supernatant and a precipitate.

[0040] Optionally, the S7 specifically includes:

[0041] S71: placing the washed soil in a flushing device, and adding clean water in a ratio of soil mass to clean water volume of 1:1 to 1:3;

[0042] S72: Intermittent flushing is used, with a flushing time of 10 to 30 minutes and an interval of 5 to 10 minutes between each flushing;

[0043] S73: Collect the waste water after flushing through the drainage device and treat the waste water centrally to avoid secondary pollution.

[0044] Optionally, the S8 specifically includes:

[0045] S81: placing the cleaned soil in a drying device and treating it by hot air drying, with the drying temperature controlled at 40° C. to 80° C. for 12 to 48 hours, until the moisture content of the soil is reduced to less than 10%;

[0046] S82: After drying is completed, add an appropriate amount of organic fertilizer or mineral conditioner, the amount of the conditioner added is 0.1% to 1% of the soil mass, and mix evenly to restore the fertility of the soil.

[0047] Optionally, the S9 specifically includes:

[0048] S91: Take the restored soil samples and use atomic absorption spectrometer to detect the heavy metal content in the soil. The detected heavy metal elements include lead, cadmium and mercury. The heavy metal content is 0.1mg / kg to 1mg / kg;

[0049] S92: Use gas chromatography to detect organic pollutants in the soil. The organic matter detected includes polycyclic aromatic hydrocarbons and polychlorinated biphenyls, and the organic matter content is 1mg / kg to 10mg / kg;

[0050] S93: Compare the test results with the national or regional soil environmental quality standards to confirm whether the content of heavy metals and organic matter meets the safety standards after soil remediation, and ensure that the remediated soil can be used safely.

[0051] Beneficial effects of the present invention:

[0052] The present invention can effectively remove heavy metals and difficult-to-degrade organic pollutants in the soil by combining chelating agents, surfactants and oxidants, and ensures that the pollutants are fully dissolved and effectively separated through staged pretreatment, leaching, waste liquid treatment and soil regeneration steps, thereby greatly improving the remediation efficiency.

[0053] The present invention reduces secondary pollution and reduces resource waste and environmental burden in the repair process by recycling the leaching liquid and precipitating pollutants in the waste liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 This is a schematic diagram of a contaminated soil leaching and remediation method according to an embodiment of the present invention;

[0056] Figure 2 The figure is a schematic diagram of the process of preparing the eluent according to an embodiment of the present invention. DETAILED DESCRIPTION

[0057] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art may also adopt other alternatives to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0058] It should be noted that the references to "one embodiment", "an embodiment", "an exemplary embodiment", "some embodiments" and the like in the specification indicate that the embodiments described may include specific features, structures or characteristics, but not every embodiment may include the specific features, structures or characteristics. In addition, when a specific feature, structure or characteristic is described in conjunction with an embodiment, it should be within the knowledge of a person skilled in the art to implement such feature, structure or characteristic in conjunction with other embodiments (whether or not explicitly described).

[0059] In general, a term can be understood, at least in part, from its use in context. For example, depending, at least in part, on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in the singular sense, or can be used to describe a combination of features, structures, or characteristics in the plural sense. Additionally, the term "based on" can be understood as not necessarily intended to convey an exclusive set of factors, but can instead, depending, at least in part, on the context, allow for the presence of other factors that are not necessarily explicitly described.

[0060] Example 1

[0061] like Figure 1-Figure 2 As shown, a method for leaching and remediation of soil contaminated by heavy metal organics comprises the following steps:

[0062] S1: Screen and crush the heavy metal and organic polluted soil to be remediated, and preliminarily detect the type and content of pollutants;

[0063] S2: Pre-oxidation treatment is performed on soils containing high concentrations of organic pollutants. Oxidants are introduced to promote the decomposition of some refractory organic matter and improve the efficiency of leaching.

[0064] S3: preparing an eluent containing a chelating agent and a surfactant, and adjusting the pH value of the eluent to a predetermined range, for removing heavy metals and organic pollutants from the soil;

[0065] S4: mixing the soil pretreated in S2 with the elution solution prepared in S3 according to a predetermined ratio, and eluting for multiple times by intermittent stirring;

[0066] S5: During the elution process, the suspended solids in the waste liquid are separated by a filtering device to prevent pollutants from remaining in the liquid;

[0067] S6: adding a flocculant to the separated waste liquid to precipitate and separate the pollutants in the waste liquid, and the treated supernatant needs to be recycled and reused;

[0068] S7: Rinse the washed soil with clean water to remove residual elution and pollutants;

[0069] S8: drying the cleaned soil to remove excess water, and conditioning the soil to restore its physical and chemical properties;

[0070] S9: Test the repaired soil to confirm whether the heavy metal and organic matter content meets the standards to ensure the safety and suitability of the soil.

[0071] S1 specifically includes:

[0072] S11: The heavy metal and organic polluted soil to be remediated is screened by a screening device, the aperture of the screen is set at 2 mm, and larger particles and impurities are separated to make the soil particles uniform in size;

[0073] S12: Use crushing equipment to crush the sieved soil to control the soil particle size to 3 mm to ensure that the particles are fully in contact with the elution liquid during the subsequent elution process;

[0074] S13: Use gas chromatograph (GC) to conduct preliminary detection of organic pollutants to obtain the type and concentration data of pollutants.

[0075] S2 specifically includes:

[0076] S21: For soils with organic pollutant concentrations higher than 500 mg / kg, pre-oxidation treatment is selected;

[0077] S22: adding sodium persulfate as an oxidant to the soil to be treated, wherein the amount of the oxidant added is 1.5% of the mass of the soil;

[0078] S23: The soil and the oxidant are stirred in a stirring device for 60 minutes to ensure that the oxidant is in full contact with and reacts with the soil, thereby promoting the decomposition of some difficult-to-degrade organic matter.

[0079] S3 specifically includes:

[0080] S31: adding chelating agent disodium ethylenediaminetetraacetate into water at a mass ratio of 0.3% of the weight of the soil;

[0081] S32: adding a surfactant, sodium dodecyl sulfate (SDS), the amount of which is 0.1% of the mass of water;

[0082] S33: stirring and mixing the above solution at a stirring speed of 300 rpm for 20 minutes to ensure that the chelating agent and the surfactant are completely dissolved and uniformly mixed;

[0083] S34: The pH value of the eluent is adjusted to 6.5 by adding sodium hydroxide to ensure that the eluent reaches the predetermined pH range.

[0084] S4 specifically includes:

[0085] S41: mixing the soil pretreated in S2 with the eluent prepared in S3 at a ratio of soil mass to eluent volume of 1:4;

[0086] S42: After mixing the soil and the elution solution, place them in a stirring device and use an intermittent stirring method. Each stirring lasts for 15 minutes, the stirring interval is 10 minutes, and the number of stirring times is 5 times;

[0087] S43: After each stirring, the mixture of soil and eluent was allowed to stand for 8 minutes to allow the pollutants to fully contact with the eluent and dissolve.

[0088] S5 specifically includes:

[0089] S51: During the elution process, the waste liquid is processed through a filtration device, the filtration device is a microfiltration membrane, and the filtration pore size is 0.05 μm;

[0090] S52: The waste liquid passes through the filter device at a flow rate of 1 L / min to ensure that the suspended matter in the waste liquid is effectively retained;

[0091] S53: Regularly clean the suspended matter on the filter membrane to prevent clogging. Clean the membrane after each filtration operation lasts 45 minutes to maintain filtration efficiency.

[0092] S6 specifically includes:

[0093] S61: placing the separated waste liquid in a stirring device, adding a flocculant at 0.03% of the volume of the waste liquid, wherein the flocculant is polyacrylamide;

[0094] S62: After adding the flocculant, stirring is performed at a stirring speed of 100 revolutions per minute for 20 minutes to ensure that the flocculant and the waste liquid are fully mixed;

[0095] S63: After stopping stirring, the waste liquid is left to stand for 45 minutes to allow the pollutant particles to settle and separate under the action of gravity to form a supernatant and a precipitate.

[0096] S7 specifically includes:

[0097] S71: placing the washed soil in a flushing device, and adding clean water in a ratio of 1:2 in volume of soil mass to clean water;

[0098] S72: Use intermittent flushing with a flushing time of 20 minutes and a flushing interval of 7 minutes to ensure that the clean water can fully penetrate the soil and remove the residual eluent and pollutants;

[0099] S73: Collect the wastewater after flushing through the drainage device and treat the wastewater centrally to avoid secondary contamination. Test the cleanliness of the soil after the cleaning operation to confirm that the residual leachate and contaminants are effectively removed.

[0100] S8 specifically includes:

[0101] S81: placing the cleaned soil in a drying device and treating it by hot air drying, with the drying temperature controlled at 60° C. for 24 hours, until the moisture content of the soil is reduced to 5%;

[0102] S82: After drying is completed, add an appropriate amount of organic fertilizer or mineral conditioner, the amount of the conditioner added is 0.5% of the soil mass, and mix evenly to restore the fertility of the soil and make it suitable for subsequent agricultural or ecological purposes.

[0103] S9 specifically includes:

[0104] S91: Take the repaired soil sample and use atomic absorption spectrometer to detect the heavy metal content in the soil. The heavy metal elements detected include lead, cadmium and mercury. The heavy metal content is 0.1 mg / kg;

[0105] S92: Organic pollutants in soil were detected using gas chromatography. The organic matter detected included polycyclic aromatic hydrocarbons and polychlorinated biphenyls, and the organic matter content was 1 mg / kg;

[0106] S93: Compare the test results with the national or regional soil environmental quality standards to confirm whether the content of heavy metals and organic matter meets the safety standards after soil remediation, and ensure that the remediated soil can be used safely.

[0107] Example 2

[0108] Step 1: The soil contaminated with lead and PAHs was screened with a mesh size of 1 mm to separate large particles and impurities. The screened soil was crushed using a crushing device, and the soil particle size was controlled at 0.1 mm. The PAH content in the soil was detected by gas chromatography and was 650 mg / kg, and the lead concentration was detected by atomic absorption spectrometer and was 300 mg / kg.

[0109] Step 2: Pre-oxidation treatment is performed on soil with a PAH content higher than 500 mg / kg, by adding 0.5% hydrogen peroxide as an oxidant to the soil, and the stirring time of the stirring equipment is 30 minutes to promote the decomposition of some refractory PAHs;

[0110] Step 3: prepare an eluent containing 0.1% sodium citrate and 0.05% sodium dodecyl sulfate, and stir and mix for 10 minutes at a stirring speed of 200 rpm. The pH value of the eluent is adjusted to 4.5 by adding hydrochloric acid;

[0111] Step 4: Mix the pretreated soil with the eluent at a mass-to-volume ratio of 1:2, and stir intermittently. Each stirring lasts for 10 minutes, with a stirring interval of 5 minutes, and stir 3 times in total. After each stirring, let it stand for 5 minutes to allow the pollutants to fully contact and dissolve with the eluent.

[0112] Step 5: Filter the elution waste liquid through an ultrafiltration membrane with a pore size of 0.01 μm and a flow rate of 0.5 L / min. Wash the membrane once after each filtration operation lasts for 30 minutes to prevent clogging by suspended matter.

[0113] Step 6: In a stirring device, add 0.01% aluminum sulfate flocculant to the separated waste liquid, stir at a speed of 50 rpm for 10 minutes, and let the waste liquid stand for 30 minutes to promote the precipitation of pollutant particles;

[0114] Step 7: Rinse the washed soil in a ratio of 1:1 soil to clean water, with an intermittent flushing time of 10 minutes and a flushing interval of 5 minutes, and collect the wastewater through the drainage device for centralized treatment;

[0115] Step 8: The washed soil is dried in a drying equipment at 40°C for 12 hours until the soil moisture content is reduced to 7%, and then 0.1% of mineral conditioner is added and mixed evenly to restore the fertility of the soil;

[0116] Step 9: Use atomic absorption spectrometer to detect the lead content in the repaired soil, which is 0.5 mg / kg. Use gas chromatograph to detect the polycyclic aromatic hydrocarbon content, which is 5 mg / kg. After comparison, it is confirmed that it meets the safety standards.

[0117] Example 3

[0118] Step 1: The soil contaminated with lead and PAHs was sieved with a mesh size of 5 mm to separate large particles and impurities. The sieved soil was crushed using a crushing device, and the soil particle size was controlled at 5 mm. The PAH content in the soil was detected by gas chromatography and was 630 mg / kg, and the lead concentration was detected by atomic absorption spectrometer and was 330 mg / kg.

[0119] Step 2: Pre-oxidation treatment is performed on soil with a PAH content higher than 500 mg / kg, by adding 2% sodium persulfate as an oxidant to the soil, and the stirring time of the stirring equipment is 90 minutes to promote the decomposition of some refractory PAHs;

[0120] Step 3: prepare an eluent containing 0.5% disodium ethylenediaminetetraacetate and 0.2% sodium dodecyl sulfate, and stir and mix for 30 minutes at a stirring speed of 500 rpm. The pH value of the eluent is adjusted to 7.0 by adding sodium hydroxide;

[0121] Step 4: Mix the pretreated soil with the eluent at a mass-to-volume ratio of 1:5, and stir intermittently. Each stirring lasts for 20 minutes, with a stirring interval of 15 minutes, for a total of 6 times. After each stirring, let it stand for 10 minutes to allow the pollutants to fully contact and dissolve with the eluent.

[0122] Step 5: Filter the elution waste liquid through a microfiltration membrane with a pore size of 0.1 μm and a flow rate of 2 L / min. Wash the membrane after each filtration operation lasts for 60 minutes to prevent clogging by suspended matter.

[0123] Step 6: In a stirring device, add 0.05% polyacrylamide flocculant to the separated waste liquid, stir at a speed of 150 rpm for 30 minutes, and let the waste liquid stand for 60 minutes to promote the precipitation of pollutant particles;

[0124] Step 7: Rinse the washed soil at a ratio of 1:3 of soil to clean water, with an intermittent flushing time of 30 minutes and a flushing interval of 10 minutes, and collect the wastewater through the drainage device for centralized treatment;

[0125] Step 8: The washed soil is dried in a drying equipment at 80°C for 48 hours until the soil moisture content is reduced to 9%, and then 1% of mineral conditioner is added and mixed evenly to restore the fertility of the soil;

[0126] Step 9: Use atomic absorption spectrometer to detect the lead content in the repaired soil, which is 1 mg / kg. Use gas chromatograph to detect the polycyclic aromatic hydrocarbon content, which is 10 mg / kg. After comparison, confirm that it meets the safety standards.

[0127] Table 1 Comparison of finished product performance parameters

[0128] Compare Projects Example 1 Example 2 Example 3 Soil pH after restoration 7.2 6.5 7.8 Soil conductivity (μS / cm) 500 450 600 Organic matter content (%) 3.5 2.8 3.2 Heavy metal residue (mg / kg) 0.1 0.5 1 PAHs content after remediation (mg / kg) 1 5 10 Lead content after repair (mg / kg) 0.1 0.5 1 Soil moisture content (%) 5 7 9 Soil fertility after restoration (%) 90 85 80

[0129] According to Table 1 above, the pH value of the soil after restoration in Example 1 is 7.2, which is close to neutral, indicating that the acidity and alkalinity of the soil after restoration is moderate and more conducive to plant growth. In contrast, the pH value of Example 2 is 6.5, which is slightly acidic, and the pH value of Example 3 is 7.8, which is alkaline and will affect the growth of some plants. Therefore, the soil pH value of Example 1 is more in line with the requirements for agricultural use after restoration; the soil conductivity of Example 1 is 500 μS / cm, indicating that the salt content in the soil is moderate and can effectively ensure the normal growth of plants. The conductivity of Example 2 is lower at 450 μS / cm, indicating that the salt content in the soil is less, which will affect the nutrient absorption of plants, and the conductivity of Example 3 is 600 μS / cm, which is high in salt and will affect the water absorption capacity of plant roots. In comparison, Example 1 is more ideal in terms of soil conductivity; the organic matter content of Example 1 is 3.5%, which is higher than the other two groups of data (2.8% in Example 2 and 3.2% in Example 3), which shows that the soil organic matter of Example 1 is richer after restoration, the soil structure is improved, and there is more It is beneficial to plant growth and improves soil fertility; the heavy metal residue in Example 1 is only 0.1 mg / kg, which is significantly lower than 0.5 mg / kg in Example 2 and 1.0 mg / kg in Example 3, which shows that Example 1 has the best effect in removing heavy metals in the soil and can effectively reduce the potential harm of heavy metals to the environment and health; the content of polycyclic aromatic hydrocarbons after repair in Example 1 is 1 mg / kg, which is much lower than 5 mg / kg in Example 2 and 10 mg / kg in Example 3. Polycyclic aromatic hydrocarbons are a type of persistent organic pollutants and are difficult to degrade. Therefore, Example 1 shows great advantages in removing organic pollutants; the soil moisture content after repair in Example 1 is 5%, which is the lowest among the three examples, which means that the soil after repair is more suitable for planting, and the soil permeability will not decrease or the root growth will not be restricted due to excessive moisture content; the soil fertility of Example 1 is restored to 90%, which is significantly higher than 85% in Example 2 and 80% in Example 3, indicating that Example 1 not only performs outstandingly in pollutant removal, but also has significant effects in restoring soil ecological functions and fertility.

[0130] From Table 1, Example 1 performs best in multiple key performance parameters. The pH value, electrical conductivity, heavy metal residues, organic pollutant content and other indicators of the repaired soil are better than those of other examples, and the organic matter content and fertility of the soil are restored to the greatest extent. Therefore, Example 1 performs well in finished product performance and has a wider application prospect and higher ecological value.

[0131] Table 2 Comparison of other performance parameters

[0132]

[0133]

[0134] As can be seen from Table 2 above, the repair time of Example 1 is 48 hours, which is significantly shorter than 72 hours of Example 2 and 96 hours of Example 3, which means that Example 1 can complete the repair in a shorter time, saving time cost; the repair cost of Example 1 is 400 yuan / ton, which is significantly lower than 500 yuan / ton of Example 2 and 600 yuan / ton of Example 3, indicating that this method has obvious advantages in economy; the treatment efficiency of Example 1 is 95%, which is higher than 90% and 85% of other examples, showing a more efficient pollutant removal ability; the energy consumption of Example 1 is 100 kWh / ton, which is lower than that of Example 2 (150 kWh / ton) and Example 3 (20 0kWh / ton), indicating that it has higher energy efficiency and helps to save energy resources; the equipment wear rate of Example 1 is 1.0%, which is lower than that of other embodiments, indicating that the repair scheme has the least loss on the equipment, helps to extend the service life of the equipment and reduce maintenance costs; the water resource usage of Example 1 is 180L / ton, which is lower than that of Example 2 (200L / ton) and Example 3 (220L / ton), showing good water resource utilization efficiency; the secondary pollutant generation of Example 1 is 0.3kg / ton, which is significantly lower than that of Example 2 (0.5kg / ton) and Example 3 (0.8kg / ton), indicating that it performs best in reducing secondary pollutants and meets environmental protection requirements. It can be seen that Example 1 is superior to the other two examples in multiple key performance indicators such as repair time, repair cost, processing efficiency, energy consumption, equipment wear rate, water resource usage and secondary pollutant generation, so it can be regarded as the optimal solution with the highest practicality and economy.

[0135] The present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention. In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without the description of these details. In addition, in order to avoid unnecessary confusion about the essence of the present invention, well-known methods, processes, procedures, components and circuits are not described in detail.

[0136] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for leaching and remediation of soil contaminated by heavy metal organic matter, characterized in that: The following steps are involved: S1: Screen and crush the heavy metal and organic polluted soil to be remediated, and preliminarily detect the type and content of pollutants; S2: Pre-oxidation treatment is performed on soils containing high concentrations of organic pollutants to promote the decomposition of some refractory organic matter by introducing oxidants; S3: preparing an eluent containing a chelating agent and a surfactant, and adjusting the pH value of the eluent to a predetermined range, for removing heavy metals and organic pollutants from the soil; S4: mixing the soil pretreated in S2 with the elution solution prepared in S3 according to a predetermined ratio, and eluting for multiple times by intermittent stirring; S5: During the elution process, the suspended matter in the waste liquid is separated by a filtering device; S6: adding a flocculant to the separated waste liquid to precipitate and separate the pollutants in the waste liquid, and the treated supernatant needs to be recycled and reused; S7: Rinse the washed soil with clean water to remove residual elution and pollutants; S8: drying the cleaned soil to remove excess water, and conditioning the soil to restore its physical and chemical properties; S9: Test the repaired soil to confirm whether the heavy metal and organic matter content meets the standards.

2. The method for leaching and remediation of soil contaminated by heavy metal organics according to claim 1, characterized in that: The S1 specifically includes: S11: The heavy metal and organic polluted soil to be remediated is screened through a screening device, with the screen aperture set at 1 mm to 5 mm to separate larger particles and impurities; S12: Using a crushing device to crush the sieved soil so that the soil particle size is controlled to be 0.1 mm to 5 mm; S13: Use gas chromatograph to conduct preliminary detection of organic pollutants and obtain the type and concentration data of pollutants.

3. The method for leaching and remediation of soil contaminated by heavy metal organics according to claim 1, characterized in that: The S2 specifically includes: S21: For soils with organic pollutant concentrations higher than 500 mg / kg, pre-oxidation treatment is selected; S22: adding sodium persulfate or hydrogen peroxide as an oxidant to the soil to be treated, wherein the amount of the oxidant added is 0.5% to 2% of the soil mass; S23: stirring the soil and the oxidant in a stirring device, and the stirring time is 30 minutes to 90 minutes.

4. The method for leaching and remediation of soil contaminated by heavy metal organics according to claim 1, characterized in that: The S3 specifically includes: S31: adding a chelating agent, disodium edetate or sodium citrate, to water at a mass ratio of 0.1% to 0.5% of the weight of the soil; S32: adding a surfactant, sodium lauryl sulfate, in an amount of 0.05% to 0.2% of the mass of the water; S33: stirring and mixing the above solution at a stirring speed of 200 to 500 rpm for 10 to 30 minutes; S34: Adjust the pH of the eluent to 4.5 to 7.0 by adding sodium hydroxide or hydrochloric acid.

5. The method for leaching and remediation of soil contaminated by heavy metal organics according to claim 1, characterized in that: The S4 specifically includes: S41: mixing the soil pretreated in S2 with the eluent prepared in S3 at a ratio of soil mass to eluent volume of 1:2 to 1:5; S42: After mixing the soil and the elution solution, place the mixture in a stirring device and stir it intermittently, with each stirring lasting 10 to 20 minutes, the stirring interval being 5 to 15 minutes, and the stirring times being 3 to 6 times; S43: After each stirring, let the mixture of soil and eluent stand for 5 to 10 minutes to allow the contaminants to fully contact the eluent and dissolve.

6. The method for leaching and remediation of soil contaminated by heavy metal organics according to claim 1, characterized in that: The S5 specifically includes: S51: During the elution process, the waste liquid is treated by a filtration device, wherein the filtration device is a microfiltration membrane or an ultrafiltration membrane, and the filtration pore size is 0.01 μm to 0.1 μm; S52: the waste liquid passes through the filter device at a flow rate of 0.5 L / min to 2 L / min; S53: Regularly clean the suspended matter on the filter membrane to prevent clogging. Clean the membrane after each filtration operation lasts 30 to 60 minutes.

7. The method for leaching and remediation of soil contaminated by heavy metal organics according to claim 1, characterized in that: The S6 specifically includes: S61: placing the separated waste liquid in a stirring device, and adding a flocculant at 0.01% to 0.05% of the volume of the waste liquid, wherein the flocculant is polyacrylamide or aluminum sulfate; S62: After adding the flocculant, stirring is performed at a stirring speed of 50 to 150 revolutions per minute for a continuous stirring time of 10 to 30 minutes to ensure that the flocculant and the waste liquid are fully mixed; S63: After stopping stirring, the waste liquid is allowed to stand for 30 to 60 minutes to allow the pollutant particles to settle and separate under the action of gravity to form a supernatant and a precipitate.

8. The method for leaching and remediation of soil contaminated by heavy metal organics according to claim 1, characterized in that: The S7 specifically includes: S71: placing the washed soil in a flushing device, and adding clean water in a ratio of soil mass to clean water volume of 1:1 to 1:3; S72: Intermittent flushing is used, with a flushing time of 10 to 30 minutes and an interval of 5 to 10 minutes between each flushing; S73: Collect the waste water after flushing through the drainage device and treat the waste water centrally to avoid secondary pollution.

9. The method for leaching and remediation of soil contaminated by heavy metal organics according to claim 1, characterized in that: The S8 specifically includes: S81: placing the cleaned soil in a drying device and treating it by hot air drying, with the drying temperature controlled at 40° C. to 80° C. for 12 to 48 hours, until the moisture content of the soil is reduced to less than 10%; S82: After drying is completed, add an appropriate amount of organic fertilizer or mineral conditioner, the amount of the conditioner added is 0.1% to 1% of the soil mass, and mix evenly to restore the fertility of the soil.

10. The method for leaching and remediation of soil contaminated by heavy metal organics according to claim 1, characterized in that: The S9 specifically includes: S91: Take the restored soil samples and use atomic absorption spectrometer to detect the heavy metal content in the soil. The detected heavy metal elements include lead, cadmium and mercury. The heavy metal content is 0.1mg / kg to 1mg / kg; S92: Use gas chromatography to detect organic pollutants in the soil. The organic matter detected includes polycyclic aromatic hydrocarbons and polychlorinated biphenyls, and the organic matter content is 1mg / kg to 10mg / kg; S93: Compare the test results with the national or regional soil environmental quality standards to confirm whether the content of heavy metals and organic matter meets the safety standards after soil remediation, and ensure that the remediated soil can be used safely.

Images