A method for remediating contaminated soil

Abstract

The present application provides a method for remediating contaminated soil, which includes the following steps: precipitating the target plot and collecting the precipitated water as stored precipitation; loosening and turning over the soil at a target depth within the target plot, adding a remediation agent, and stirring to evenly mix the remediation agent with the soil, and then in-situ laying the soil; spraying the stored precipitation onto the in-situ laid target plot and recording the water application time. By first precipitating the target plot and collecting the precipitated water as stored precipitation, the groundwater within the target plot can be collected, reducing the water demand during subsequent remediation processes, reducing water resource waste, and at the same time reducing the water content within the target plot, facilitating the loosening and turning over of the soil within the target plot, facilitating the uniform mixing of the dry remediation agent with the soil, thereby improving the remediation efficiency.

Description

Technical Field

[0001] This application relates to the technical field of soil remediation, and particularly relates to a method for remediating contaminated soil. Background Art

[0002] For polycyclic aromatic hydrocarbon (PAH)-contaminated plots, traditional remediation methods are carried out in the form of in-situ jet grouting or ex-situ chemical oxidation. Among them, the in-situ jet grouting method has a low remediation efficiency. The effective range of each jet grouting operation is affected by the spraying radius, and it is necessary to set up water and electricity facilities, chemical dosing platforms and other facilities at the operation site, resulting in a relatively high operation difficulty. The ex-situ chemical oxidation method also requires setting up water and electricity facilities, chemical mixing areas and other facilities at the operation site. During the implementation process, the construction cost of water and electricity facilities is high and the construction period is long. The chemical dosing platform occupies a large area. The liquid oxidation agent not only has a complex preparation process, but also has high safety requirements, requires a large amount of water, has serious waste during the remediation process, has a low remediation efficiency, and has a fixed construction period, making it difficult to make flexible adjustments.

[0003] In view of this, there is an urgent need in the art for a method for remediating contaminated soil that can solve the above problems. Summary of the Invention

[0004] The purpose of this application is to provide a method for remediating contaminated soil to solve at least one of the technical problems described in the background art.

[0005] Specifically, this application provides a method for remediating contaminated soil, including the following steps:

[0006] Precipitate the target plot and collect the precipitation as stored precipitation;

[0007] Loosen and turn over the soil at the target depth in the target plot, add a remediation agent, and mix it to make the remediation agent evenly mixed with the soil, and then lay the soil in-situ;

[0008] Spray the stored precipitation on the target plot laid in-situ and record the water application time.

[0009] Adopting the above solution, by first dewatering the target plot and collecting the dewatered water as stored precipitation, the groundwater within the target plot can be collected, reducing the water demand during subsequent remediation processes, minimizing water resource waste, and at the same time reducing the water content within the target plot, facilitating the loosening and turning of the soil within the target plot, and facilitating the uniform mixing of the dry remediation agent with the soil, thereby improving the remediation efficiency. During the process of spraying the stored precipitation onto the target plot laid in-situ, excluding the pre-collected stored precipitation, the groundwater level within the target plot will also automatically recover over time. That is, the upper-layer agent within the target plot is dissolved by the stored precipitation, and the lower-layer agent within the target plot can also be dissolved through the recovery of the groundwater level. While achieving the soil remediation effect, it also meets the soil conservation requirements. Moreover, due to the in-situ remediation measures adopted in the solution of this application, it also avoids the waste caused by the transportation of contaminated soil, simplifies the construction process, and improves the remediation efficiency.

[0010] In some alternative embodiments of the present application, the soil at the target depth within the target plot is loosened and leveled, a remediation agent is added, and then mixed to make the remediation agent evenly mixed with the soil. During the step of laying the soil in-situ, the remediation agent includes the following components: sodium persulfate and sodium hydroxide. By weight, the proportions of sodium persulfate and sodium hydroxide are 3 - 7:1 respectively.

[0011] Adopting the above solution, by including sodium persulfate and sodium hydroxide in the remediation agent, the strong oxidizing property of sodium persulfate can be utilized to effectively degrade and remove soil pollutants, and at the same time, the properties of sodium hydroxide can be used to improve the soil environment, assisting in enhancing the strong degradation and removal effect of sodium persulfate.

[0012] In some alternative embodiments of the present application, the pollutants in the target plot are one or several of polycyclic aromatic hydrocarbons and monocyclic aromatic hydrocarbons.

[0013] In some alternative embodiments of the present application, before the step of dewatering the target plot and collecting the dewatered water as stored precipitation, there is also a step

[0014] Receiving partitioning data, dividing the target area into multiple target plots, and numbering the multiple target plots;

[0015] Among them, the target plots are arranged at intervals.

[0016] Adopting the above solution, by receiving partitioning data, dividing the target area into multiple target plots, numbering the multiple target plots, and then selecting the target plots in the order of the numbers, different numbers of operation surfaces can be adopted according to the actual situation, making the construction period flexibly controllable and also reducing the demand for off-site construction sites.

[0017] In some alternative embodiments of the present application, the target plot includes at least one area to be repaired, and the area to be repaired is a polygon within the target plot, and the polygon is formed by repair inflection points.

[0018] In some alternative embodiments of the present application, the target plot includes at least one area to be repaired, and the repaired area is a polygon within the target plot, and the polygon is formed by repair inflection points.

[0019] In some alternative embodiments of the present application, at least one area to be repaired is located at the edge of the target plot.

[0020] In some alternative embodiments of the present application, a soil stacking area is set in the target plot, and the soil stacking area is arranged at an interval from the area to be repaired;

[0021] The interval between the soil stacking area and the area to be repaired is at least a first distance.

[0022] In some alternative embodiments of the present application, the soil stacking area is an area with variable area, and the first distance is obtained according to the area and depth of the area to be repaired.

[0023] In some alternative embodiments of the present application, after spraying the collected precipitation on the in-situ laid target plot and recording the water application time step, the following steps are further included: obtaining the current time and the water application time of the target plot with applied water, and determining whether the target time is met according to the difference between the current time and the water application time. If so, detecting the soil of the target plot. If not, selecting the target plot in the order of the numbers, and performing the steps of precipitating the target plot and collecting it as the collected precipitation. The target time is the length of time that the target plot needs to stand still after water application.

[0024] By adopting the above solution, it is possible to achieve sequential operations on multiple target plots and complete the overall target area.

[0025] In some alternative embodiments of the present application, the step of spraying the collected precipitation on the in-situ laid target plot and recording the water application time further includes: obtaining the target water application amount, comparing the collected precipitation with the target water application amount. If the collected precipitation is less than the target water application amount, then after spraying the collected precipitation on the in-situ laid target plot, supplement and spray the difference between the collected precipitation and the target water application amount to the target plot. If the collected precipitation is greater than or equal to the target water application amount, then normally spray the collected precipitation on the in-situ laid target plot.

[0026] In some alternative embodiments of the present application, the step of precipitating the target plot and collecting it as the collected precipitation further includes: at least one precipitation well is set in the area to be repaired, and the position of the precipitation well is marked, and the water level of the precipitation well is between the highest water level and the lowest water level of the repaired area.

[0027] In some alternative embodiments of the present application, the step of precipitating water in the target plot and collecting it for storing the precipitated water further includes: controlling the water surface in the foundation pit to drop at least a second distance below the excavation surface, and the second distance is not less than 0.5 meters.

[0028] In some alternative embodiments of the present application, when excavating the soil, a guardrail is set around the foundation pit for protection, and a skirting board is provided below.

[0029] Moreover, it includes the step of ensuring that there is no water in the foundation pit:

[0030] When there is local wet soil, surface water or drained water, drainage blind ditches with an interface size of 200 mm×200 mm - 600 mm×600 mm and sump pits with a cross-sectional size of 8000 mm×8000 mm - 15000 mm×15000 mm are set up, and a pump is used to drain the accumulated water.

[0031] In some alternative embodiments of the present application, in the step of adding the remediation agent, it further includes the steps:

[0032] First, a small-scale test is carried out. According to the results of the small-scale test, the agent is prepared, and the final dosage of the agent is determined according to the pollution distribution in each block of the site and the pilot-scale test.

[0033] In some alternative embodiments of the present application, the remediation agent further includes a coating agent. By weight, the proportions of sodium persulfate, sodium hydroxide and the coating agent are 7 - 12: 2 - 3: 1 respectively.

[0034] Adopting the above scheme can ensure the efficient action of sodium persulfate and sodium hydroxide. At the same time, by utilizing the excellent physical and chemical properties of the coating agent, it can effectively adsorb pollutants such as organic substances and heavy metal ions in the soil, fix them, and promote the positive progress of the remediation work.

[0035] In some alternative embodiments of the present application, the coating agent is at least one of bentonite, kaolin and talc powder.

[0036] In some alternative embodiments of the present application, by weight, the proportions of sodium persulfate, sodium hydroxide and the coating agent are 10: 3: 1 respectively.

[0037] In some alternative embodiments of the present application, after the step of precipitating water in the target plot and collecting it for storing the precipitated water, before the step of loosening and turning over the soil at the target depth in the target plot, adding the remediation agent, stirring, and then laying the soil in place after making the remediation agent evenly mixed with the soil, it further includes the step of preparing the remediation agent. By weight, the proportions of sodium persulfate, sodium hydroxide and the coating agent are 10: 3: 1 respectively.

[0038] After crushing 1 part by weight of the coating agent, it is sieved through a 300-mesh sieve, dissolved in 3 parts of deionized water, and mixed evenly to obtain a coating agent suspension. Then, 1 part of sodium hydroxide is dissolved in the coating agent suspension and mixed evenly to obtain a mixed solution. Take 2 parts of sodium hydroxide and 10 parts of sodium persulfate, place them in a fluidized bed, use the mixed solution as a coating agent for spraying, granulate the materials in the fluidized bed, and after the spraying is completed, dry at 55°C and then sieve through a 50-mesh sieve to obtain the repair agent.

[0039] Adopting the above scheme, the repair agent obtained by adding the coating agent can control the steady release of the internal acting agent, and promote the efficient and positive progress of the repair work.

[0040] In some alternative embodiments of the present application, the step of spraying the collected precipitation on the target plot laid in situ and recording the water application time further includes applying the collected precipitation to the target plot laid in situ by means of drip irrigation, and recording the water application time when the water application is completed.

[0041] Adopting the above scheme, when necessary, the collected precipitation is applied by atomizing with a fog cannon, which can make full use of the structural characteristics of the coating structure repair agent, so that the internal acting agent can continuously act on the contaminated soil within a certain period of time, thereby improving the actual use effect of the repair agent.

[0042] In some alternative embodiments of the present application, in the step of applying the collected precipitation to the target plot laid in situ by atomizing and recording the water application time when the water application is completed, the speed of the fog cannon is 80 - 120 liters per hour.

[0043] In some alternative embodiments of the present application, the step of detecting the soil of the target plot further includes adding auxiliary agents. The auxiliary agents include complex A and complex B. By weight, the proportions of sodium persulfate, sodium hydroxide, coating agent, complex A and complex B are 7 - 12:2 - 3:1:0.1 - 0.5:1 respectively. Complex A includes at least one of Trichoderma viride and Pseudomonas putida. Complex B includes at least one of cellulose and lignin.

[0044] In some alternative embodiments of the present application, by weight, the proportions of sodium persulfate, sodium hydroxide, coating agent, complex A and complex B are 10:3:1:0.3:1 respectively.

[0045] Adopting the above scheme, by adding complex A and complex B, the biodegradation of contaminated soil can be fully realized, and the long-term restoration of soil performance can be promoted.

[0046] In some alternative embodiments of the present application, complex A includes Trichoderma viride and Pseudomonas putrefaciens. By weight, the proportions of Trichoderma viride and Pseudomonas putrefaciens are 1:1 - 5 respectively. Complex B includes cellulose and lignin. By weight, the proportions of cellulose and lignin are 1:1 - 2 respectively.

[0047] In summary, the present application has the following beneficial effects:

[0048] 1. By first reducing the water level in the target plot and collecting the collected precipitation, the groundwater in the target plot can be collected, reducing the water demand in the subsequent repair process and reducing water resource waste;

[0049] 2. Reducing the water content in the target plot facilitates loosening and mixing of the soil in the target plot, facilitating the uniform mixing of the dry repair agent with the soil, thereby improving the repair efficiency;

[0050] 3. The groundwater level in the target plot will automatically recover over time. That is, the upper-layer agent in the target plot is dissolved by the collected precipitation, and the lower-layer agent in the target plot can also be dissolved by the recovery of the groundwater level. While achieving the soil repair effect, it also meets the soil maintenance requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0052] Figure 1 It is a schematic diagram of the repair site in the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] Here, the exemplary embodiments will be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0054] The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "the", and "said" used in the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0055] The strains used in the following examples are publicly available, such as purchased from the China General Microbiological Culture Collection Center, Shanghai Culture Collection of Microorganisms, China Center for Agricultural Culture Collection of Microorganisms, or published in scientific and technological journals.

[0056] Specifically, the strain information applied in the examples of this application is as follows:

[0057] Trichoderma viride, from the Shanghai Culture Collection of Microorganisms, with the strain number SHBCC D22985;

[0058] Pseudomonas putida, from the Shanghai Culture Collection of Microorganisms, with the strain number SHBCC D50118.

[0059] In addition, the soil steady infiltration rate described in this application is measured by the method in the prior art and will not be elaborated here. Example 1

[0060] Preparation of the remediation agent:

[0061] Take 3 parts by weight of sodium persulfate and 1 part by weight of sodium hydroxide, crush them, pass through a 300-mesh sieve, and mix evenly to obtain the remediation agent. Example 2

[0062] Preparation of the remediation agent:

[0063] Take 5 parts by weight of sodium persulfate and 1 part by weight of sodium hydroxide, crush them, pass through a 300-mesh sieve, and mix evenly to obtain the remediation agent. Example 3

[0064] Preparation of the remediation agent:

[0065] Take 7 parts by weight of sodium persulfate and 1 part by weight of sodium hydroxide, crush them, pass through a 300-mesh sieve, and mix evenly to obtain the remediation agent. Example 4

[0066] Preparation of the remediation agent:

[0067] Take 1 part by weight of the coating agent, crush it, pass through a 300-mesh sieve, dissolve it in 3 parts by weight of deionized water, mix evenly to obtain the coating agent suspension, and then take 1 part by weight of sodium hydroxide and dissolve it in the coating agent suspension, and mix evenly to obtain the mixed solution. Among them, the coating agent is kaolin.

[0068] Take 1 part by weight of sodium hydroxide and 7 parts by weight of sodium persulfate, place them in a fluidized bed, spray with the mixed solution as the coating agent, granulate the materials in the fluidized bed, after the spraying is completed, dry at 55 °C, and then pass through a 50-mesh sieve to obtain the remediation agent. Example 5

[0069] Preparation of the remediation agent:

[0070] After crushing 1 part by weight of the coating agent, it is sieved through a 300-mesh sieve, dissolved in 3 parts of deionized water, and mixed evenly to obtain a coating agent suspension. Then, 1 part of sodium hydroxide is dissolved in the coating agent suspension and mixed evenly to obtain a mixed solution. Among them, the coating agent is kaolin.

[0071] Take 1 part of sodium hydroxide and 10 parts of sodium persulfate, place them in a fluidized bed, spray with the mixed solution as the coating agent, granulate the materials in the fluidized bed, and after the spraying is completed, dry at 55 °C and then sieve through a 50-mesh sieve to obtain the repair agent. Example 6

[0072] Preparation of the repair agent:

[0073] After crushing 1 part by weight of the coating agent, it is sieved through a 300-mesh sieve, dissolved in 3 parts of deionized water, and mixed evenly to obtain a coating agent suspension. Then, 1 part of sodium hydroxide is dissolved in the coating agent suspension and mixed evenly to obtain a mixed solution. Among them, the coating agent is kaolin.

[0074] Take 2 parts of sodium hydroxide and 10 parts of sodium persulfate, place them in a fluidized bed, spray with the mixed solution as the coating agent, granulate the materials in the fluidized bed, and after the spraying is completed, dry at 55 °C and then sieve through a 50-mesh sieve to obtain the repair agent. Example 7

[0075] Preparation of the repair agent:

[0076] After crushing 1 part by weight of the coating agent, it is sieved through a 300-mesh sieve, dissolved in 3 parts of deionized water, and mixed evenly to obtain a coating agent suspension. Then, 1 part of sodium hydroxide is dissolved in the coating agent suspension and mixed evenly to obtain a mixed solution. Among them, the coating agent is kaolin.

[0077] Take 2 parts of sodium hydroxide and 12 parts of sodium persulfate, place them in a fluidized bed, spray with the mixed solution as the coating agent, granulate the materials in the fluidized bed, and after the spraying is completed, dry at 55 °C and then sieve through a 50-mesh sieve to obtain the repair agent. Example 8

[0078] In some embodiments, the contaminated soil remediation method described in the present application includes:

[0079] S100, receiving the division data, dividing the target area into multiple target plots, where the target plots are arranged at intervals; in some embodiments, the intervals of the target plots are immovable facilities, such as rivers, roads, etc., excluding the above immovable facilities from the target plots can reduce the exploration work of the land in the target area.

[0080] S200, select the working plot as the target plot in the order of the numbers, conduct precipitation on the target plot and collect it as the received precipitation.

[0081] Among them, in some embodiments, the target plot includes at least one area to be repaired, and the area to be repaired is a polygon within the target plot, and the polygon is formed by repair inflection points; as Figure 1 shown, where areas A, B... K are multiple areas to be repaired.

[0082] In some embodiments, the target plot includes at least one area to be repaired, and the repaired area is a polygon within the target plot, and the polygon is formed by repair inflection points, where at least one area to be repaired is located at the edge of the target plot, such as Figure 1 below area A and below area B in. Adopting this solution, setting the area to be repaired at the edge of the target plot can assist in repeatedly verifying the division accuracy of the target area during actual exploration, and avoid the situation where some plots are not explored due to inaccurate division of the target area.

[0083] In some embodiments, a soil stacking area is set in the target plot, and the soil stacking area is arranged at an interval from the area to be repaired; the interval between the soil stacking area and the area to be repaired is at least a first distance. More specifically, the soil stacking area is an area with variable area, and the first distance is obtained according to the area and depth of the area to be repaired. Since soil needs to be placed in the soil stacking area and soil placement is likely to cause secondary pollution, in order to avoid this situation, the first distance is set in advance as a buffer zone, and the soil stacking area can be appropriately expanded when the soil in the soil stacking area is too high, and the expanded soil stacking area is based on the prior soil stacking area.

[0084] In some embodiments, for the steps of precipitating the target plot and collecting the precipitated water for storage, it further includes: at least one precipitation well is set in the area to be repaired, and the position of the precipitation well is marked, and the water level of the precipitation well is between the highest water level and the lowest water level of the repaired area. The applicant found that precipitation below the lowest water level is likely to cause excessive precipitation, that is, it may pump out the water in other areas to be repaired or non-repaired areas, affecting the repair or use of other areas.

[0085] In some embodiments, during soil excavation, a guardrail is set around the foundation pit for protection, and a skirting board is provided below; and, it includes the step of ensuring that there is no water in the foundation pit:

[0086] When there is local wet soil, surface water or drained water, a drainage blind ditch with an interface size of 200 mm × 200 mm - 600 mm × 600 mm and a sump with a cross-sectional size of 8000 mm × 8000 mm - 15000 mm × 15000 mm are set, and a pump is used to drain the accumulated water.

[0087] S300, loosen and turn over the soil at the target depth in the target plot, add a repair agent, and stir to make the repair agent evenly mixed with the soil, and then lay the soil in place.

[0088] S400, spray the collected precipitation onto the target plot laid in situ and record the water application time.

[0089] S500, obtain the current time and the water application time of the target plot where water has been applied, determine whether the target time is met (i.e., whether the water consumption for water level recovery is met) according to the difference between the current time and the water application time. If so, detect the soil of the target plot. If not, conduct precipitation on the next target plot and use the groundwater obtained from the next target plot for the previous target plot to ensure the repair efficiency of the previous plot.

[0090] Continue to refer to Figure 1 , for a polycyclic aromatic hydrocarbon organic polluted plot in Tianjin, conduct soil pollution repair treatment. Divide the polluted plot (target plot) into 7 plots (areas to be repaired), and measure the soil steady infiltration rates of the above 7 plots as 1.88mm / min, 1.90mm / min, 1.85mm / min, 1.86mm / min, 1.90mm / min, 1.86mm / min, 1.85mm / min. Use the repair agents obtained from Example 1 to Example 7 respectively, and conduct repair work according to the above polluted soil repair method. In this example, the theoretical repair area is 31533m 2 , the agent reacts for 45 days, and measure the concentrations of polycyclic aromatic hydrocarbons in the soil before and after repair respectively, as shown in Table 1.

[0091] Table 1 Soil Pollution Repair Effect

[0092]

[0093] As shown in Table 1, the repair agent provided in this application performs excellently in the process of repairing polycyclic aromatic hydrocarbon organic polluted soil, and the concentration of polycyclic aromatic hydrocarbons decreases significantly before and after repair. Comparing the data of Example 1 - 3, it can be seen that the repair agent with the ratio provided in Example 1 has better effects; comparing the data of Example 3 with that of Example 4 - 7, it can be seen that after adding clay and adopting the coating process in the preparation of the repair agent, the removal effect of polycyclic aromatic hydrocarbons can be further improved, and the repair agent with the ratio provided in Example 6 has the best effect. Example 9

[0094] Preparation of auxiliary agent:

[0095] Take 0.3 parts by weight of Trichoderma viride and 1 part of cellulose, mix evenly to obtain the auxiliary agent. Example 10

[0096] Preparation of auxiliary agent:

[0097] Take 0.3 parts by weight of Pseudomonas putida and 1 part of lignin and mix them evenly to obtain an auxiliary agent. Example 11

[0098] Preparation of auxiliary agent:

[0099] Take 0.1 part by weight of Trichoderma viride, 0.2 part of Pseudomonas putida, 0.5 part of cellulose and 0.5 part of lignin, and mix them evenly to obtain an auxiliary agent. Example 12

[0100] Preparation of auxiliary agent:

[0101] Take 0.1 part by weight of Trichoderma viride, 0.3 part of Pseudomonas putida, 0.5 part of cellulose and 0.5 part of lignin, and mix them evenly to obtain an auxiliary agent. Example 13

[0102] Auxiliary remediation:

[0103] After the soil of the target plot is remediated and detected, add the auxiliary agent to the target plot. After the auxiliary remediation time, conduct detection again, aiming to continue to control the concentration of soil pollutants within a longer time range.

[0104] For the plot remediated in Example 6, divide it into 4 blocks again, and use the remediation agents obtained in Examples 9 to 12 respectively. Carry out the remediation work according to the above-mentioned contaminated soil remediation method. The auxiliary remediation time is 245 days. Measure the concentrations of polycyclic aromatic hydrocarbons in the soil before and after remediation respectively, as shown in Table 2.

[0105] Table 2 Auxiliary remediation effect of soil pollution

[0106]

[0107] As shown in Table 2, the auxiliary agent provided by the present application can further remediate the soil contaminated by polycyclic aromatic hydrocarbons, significantly reducing the concentration of polycyclic aromatic hydrocarbons in the soil after the remediation work is completed to maintain the remediation effect. Comparing the data of Examples 9 - 12, it can be seen that the auxiliary agent provided in Example 11 has a better effect. Example 14

[0108] Conduct soil pollution remediation treatment on another two plots contaminated by polycyclic aromatic hydrocarbons in Tianjin (the soil steady infiltration rates are 2.08 mm / min and 2.10 mm / min respectively). The areas of the two plots contaminated by polycyclic aromatic hydrocarbons are approximately equal (about 500m 2 ), and use the remediation method provided by the present application and the in-situ jet grouting process remediation method in the prior art respectively. Compared with the in-situ jet grouting process remediation method, the construction period of the remediation method provided by the present application is about 50% shorter. Example 15

[0109] Apply the repair agent in Example 6 to another three experimental plots. The conditions of the three plots are as follows:

[0110] Plot A: The area is 500 m 2 , and the stable soil infiltration rate is 0.78 mm / min;

[0111] Plot B: The area is 500 m 2 , and the stable soil infiltration rate is 2.56 mm / min;

[0112] Plot C: The area is 500 m 2 , and the stable soil infiltration rate is 3.09 mm / min;

[0113] Carry out the repair work according to the contaminated soil repair method in Example 8. The repair duration is 45 days. Measure the concentrations of polycyclic aromatic hydrocarbons in the soil before and after repair, as shown in Table 3.

[0114] Table 3 Soil Pollution Repair Effect

[0115]

[0116] As shown in Table 3, when the repair agent in Example 6 is applied to plots with different soil infiltration rates, there are differences in the effects. Among them, the soil infiltration rate of Plot A is relatively low, resulting in a significant reduction in the repair effect. The applicant speculates that it is due to the low infiltration capacity inside the soil, which affects the infiltration of the active ingredients and causes the reduction in the repair effect.

[0117] Furthermore, to rule out the influence of the initial concentration of polycyclic aromatic hydrocarbons, the applicant tried another three experimental plots again. The conditions of the three plots are as follows:

[0118] Plot D: The area is 500 m 2 , and the stable soil infiltration rate is 1.28 mm / min;

[0119] Plot E: The area is 500 m 2 , and the stable soil infiltration rate is 2.05 mm / min;

[0120] Plot F: The area is 500 m 2 , and the stable soil infiltration rate is 2.80 mm / min;

[0121] Carry out the repair work according to the contaminated soil repair method in Example 8. The repair duration is 45 days. Measure the concentrations of polycyclic aromatic hydrocarbons in the soil before and after repair, as shown in Table 4.

[0122] Table 4 Soil Pollution Repair Effect

[0123]

[0124] As shown in Table 4, in plots DEF, the application effects of Example 6 are all relatively good, and there are no significant differences. The initial concentration of polycyclic aromatic hydrocarbons in the specification has little effect on the application effect of the agent; and in plots DEF, the soil steady infiltration rate is also greater than 1.0 mm / min.

[0125] Therefore, the applicant believes that applying the solution of the present application to plots with a soil steady infiltration rate greater than 0.78 mm / min, or preferably to plots with a soil steady infiltration rate greater than 1.0 mm / min, or preferably to plots with a soil steady infiltration rate greater than 1.28 mm / min, the use effect of the agent is better.

[0126] In summary, the present application provides a method for remediating contaminated soil, which solves the problems of high construction costs and long construction periods for hydropower facilities during soil remediation, large floor areas of dosing platforms, and large water resource demands. By adopting the technical solution of in-situ remediation, the remediation efficiency is improved, waste caused during the transportation of contaminated soil is avoided, the construction process is simplified, water resources are saved, and it has a very good application prospect.

[0127] It should be noted that for those of ordinary skill in the art, the technical features in the above embodiments can be freely combined, and the formed technical solutions also belong to the embodiments disclosed in the present application.

[0128] Furthermore, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A method for remediating contaminated soil, characterized in that, it includes the following steps, precipitate the target plot and collect the precipitation as stored precipitation; loosen and turn over the soil at the target depth in the target plot; add a remediation agent, mix, and after the remediation agent is evenly mixed with the soil; lay the soil in situ; spray the stored precipitation on the target plot laid in situ, and record the water application time; obtain the current time and the water application time of the target plot where water has been applied, and determine whether the target time is met according to the difference between the current time and the water application time. If so, detect the soil of the target plot; after the soil of the target plot is remediated and detected, add an auxiliary agent to the target plot; wherein, the stable infiltration rate of the soil in the target plot is greater than 1.28 mm / min, and the pollutant therein is polycyclic aromatic hydrocarbon; the remediation agent includes the following components: sodium persulfate, sodium hydroxide, coating agent; the coating agent is at least one of bentonite, kaolin and talc powder; the auxiliary agent includes complex A and complex B. Complex A includes Trichoderma viride and Pseudomonas putida, and complex B includes cellulose and lignin; by weight, the weight ratio of sodium persulfate, sodium hydroxide, coating agent, complex A and complex B is 7-12: 2-3: 1: 0.1-0.5: 1; wherein, the preparation method of the remediation agent includes the steps: take 1 part by weight of the coating agent, crush it, pass through a 300-mesh sieve, dissolve it in 3 parts of deionized water, mix evenly to obtain a coating agent suspension, then take 1 part of sodium hydroxide and dissolve it in the coating agent suspension, mix evenly to obtain a mixed solution, take 2 parts of sodium hydroxide and 10 parts of sodium persulfate, place them in a fluidized bed, use the mixed solution as the coating agent for spraying, granulate the materials in the fluidized bed, after the spraying is completed, dry at 55 °C, and then pass through a 50-mesh sieve to obtain the remediation agent.

2. The method for remediating contaminated soil according to claim 1, characterized in that, before the step of precipitating the target plot and collecting the precipitation as stored precipitation, there is also a step: receive partitioning data, divide the target area into multiple target plots, and number the multiple target plots; wherein, the target plots are arranged at intervals.

3. The method for remediating contaminated soil according to claim 2, characterized in that, the target plot includes at least one area to be remediated, and the area to be remediated is a polygon within the target plot, and this polygon is formed by remediation inflection points.

4. The method for remediating contaminated soil according to claim 3, characterized in that, a soil stacking area is set in the target plot, and the soil stacking area is arranged at intervals with the area to be remediated; the interval between the soil stacking area and the area to be remediated is at least a first distance.

5. The method for remediating contaminated soil according to claim 3, characterized in that: the step of precipitating the target plot and collecting the precipitation as stored precipitation further includes: at least one precipitation well is set in the area to be remediated, and the position of the precipitation well is marked, and the water level of the precipitation well is between the highest water level and the lowest water level of the remediation area.

6. The method for remediating contaminated soil according to claim 1, characterized in that: The steps of precipitating the target plot and collecting the precipitated water for storage also include: Controlling the water surface in the foundation pit to drop at least a second distance below the excavation surface, and the second distance is not less than 0.5 meters.

7. The contaminated soil remediation method according to claim 6, characterized in that: When excavating the soil, a guardrail is set up around the foundation pit for protection, and a skirting board is provided below. Moreover, it includes the step of ensuring that there is no water in the foundation pit: When there is local wet soil, surface water or drained water, drainage blind ditches and sump pits are set up, and pumps are used to drain the accumulated water.

8. The contaminated soil remediation method according to claim 1, characterized in that: In the step of adding the remediation agent, it further includes the steps of: First, conduct a small-scale test, prepare the agent according to the results of the small-scale test, and determine the final dosage of the agent according to the pollution distribution of each block on site and the pilot test.

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