CN116396757A

CN116396757A - Eluent for repairing arsenic and benzopyrene in composite contaminated soil and repairing method

Info

Publication number: CN116396757A
Application number: CN202310369680.3A
Authority: CN
Inventors: 何泽琛; 朱航海; 魏甜; 尹光彩
Original assignee: Guangdong University of Technology
Current assignee: Guangdong University of Technology
Priority date: 2023-04-10
Filing date: 2023-04-10
Publication date: 2023-07-07

Abstract

The invention discloses a eluting agent for repairing arsenic and benzopyrene in composite polluted soil and a repairing method, wherein the eluting agent consists of organic acid and a biosurfactant, and the volume ratio of the organic acid to the biosurfactant is 1:1, a step of; the repairing method comprises the following steps: and repairing the arsenic and the benzopyrene in the composite polluted soil by adopting a compound leaching agent of organic acid and a biosurfactant in a certain volume ratio. The invention solves the technical problems of secondary pollution, limited removal efficiency and high treatment cost of the existing eluent; the compound leaching agent has higher removal rate of As and BaP in the composite polluted soil, and can meet the restoration requirement on the soil of an actual field.

Description

Eluent for repairing arsenic and benzopyrene in composite contaminated soil and repairing method

Technical Field

The invention relates to the technical field of restoring polluted soil by a compound leaching agent, in particular to a leaching agent for restoring arsenic and benzopyrene in the composite polluted soil and a restoring method.

Background

Soil is the most important natural resource for people to perform production activities. With the progress of urban and industrialized production, the types of soil pollutants are increased, the pollution forms are gradually complicated and diversified, and the simultaneous existence of heavy metals and Polycyclic Aromatic Hydrocarbons (PAHs) in construction lands gradually becomes the ubiquitous condition in soil environments. Heavy metals and PAHs are environmental pollutants commonly found in soil, and have toxicity and carcinogenicity. These contaminants often originate from industrial, traffic, combustion, etc. human activities, enter air, water and soil, jeopardize the ecosystem and human health. Arsenic (As) is a first type of pollutant in the environment and widely exists in construction land soil, and in south China, the content of As in the soil is generally higher than that in other areas because the soil is mostly red loam. And benzo (a) pyrene (BaP) is a pentacyclic PAHs, mainly from coke production, petroleum refining, garbage incineration, nonferrous metal smelting and the like, has poor solubility in water, and has the characteristics of long latency, large treatment difficulty and the like. As and BaP can enter soil sequentially or simultaneously through the paths of atmospheric sedimentation, sewage irrigation, waste residue and waste material diffusion, industrial leakage and the like to generate interaction, and the toxic effect of the As and the BaP is enhanced, so that the ecological environment and the human health are more seriously damaged. When As and BaP coexist in the soil, they may interact due to other factors such As pollutant concentration, soil pH and microbial flora, which have an influence on the chemical and biological properties of the soil, thereby increasing the ecological risk and enhancing the health risk to human bodies. As can reduce the biodegradability of BaP in soil by inhibiting some of the bacteria and fungi in the soil that are involved in biodegradation and decomposition in the soil. On the other hand, baP reduces the ability of soil microorganisms to reduce As, thereby reducing the bioavailability of As in the soil. As and BaP are soil pollutants, the ecological risks and health risks generated by the soil polluted by As and BaP are not negligible, and the importance and practical significance of repairing and treating the soil polluted by As and BaP are that the ecological environment of the soil is protected, the health risks generated by As and BaP to human beings are reduced, the utilization of land resources is improved, and the stable and healthy development of society is maintained. Therefore, the method has great necessity and importance for repairing As and BaP composite polluted soil.

The repair technology of the heavy metal and PAHs combined polluted soil is gradually mature, such As an electric repair technology, a biological repair technology, a leaching repair technology and a combined repair technology, but no repair technology specially aiming at the As and BaP combined polluted soil exists at present. Compared with other repair technologies, the leaching repair technology has the advantages of simple operation, reasonable cost, wide application and mature technology. The leaching repair technology is a physical and chemical process for treating heavy metals or organic pollutants in polluted soil, and is usually directed to injecting or spraying a solvent into the soil to wash the pollutants in pore media, and the effects of desorption, dissolution and removal of the pollutants are achieved by means of migration or solubilization of the pollutants by the solvent and the like. The action mechanism of leaching and restoring the heavy metal polluted soil is to reverse the reaction mechanism of the soil for holding heavy metal ions; the repair PAHs are released and migrated from soil particles into an aqueous phase by utilizing the solubilization of the eluent. The existing leaching agent is used for leaching and restoring the As polluted soil in the field, but the research on leaching and restoring the BaP polluted soil is less, and particularly the leaching agent for the As and BaP combined polluted soil is used for leaching and restoring the As polluted soil. For leaching and restoring the composite polluted soil, a compound leaching agent is often used, because a single leaching agent cannot give consideration to the restoring effect of various pollutants, the compound leaching agent can improve the pollutant removal rate and can also increase the types of removed pollutants. Therefore, the invention is compounded with the leaching agent which is green and environment-friendly, can simultaneously leach and remove As and BaP in the soil, and provides the corresponding leaching agent concentration, leaching step, leaching process parameters and the like so As to reduce the cost and improve the application of the leaching agent in engineering.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide the eluting agent and the repairing method for repairing the arsenic and the benzopyrene in the composite polluted soil, and the method solves the technical problems of secondary pollution, limited removal efficiency and high treatment cost of the existing eluting agent.

The aim of the invention is achieved by the following technical scheme:

an eluting agent for repairing arsenic and benzopyrene in composite polluted soil, which comprises the following components:

the leaching agent consists of organic acid and biosurfactant, wherein the volume ratio of the organic acid to the biosurfactant is 1:1, a step of;

the organic acid is at least one of oxalic acid, citric acid and malic acid;

the biosurfactant is at least one of saponin, sophorolipid, soapberry and rhamnolipid.

A restoration method for restoring arsenic and benzopyrene in composite polluted soil comprises the following steps:

step 1: adopting organic acid and biological surfactant in a certain volume ratio to compound the eluting agent;

step 2: mixing the eluent with the polluted soil, and oscillating at 20-30 ℃ through an oscillator;

step 3: centrifugally separating the leaching agent, and preserving supernatant to obtain a solid centrifugal material;

step 4: adding purified water into the solid centrifuge, oscillating again in an oscillator, centrifuging, and repeatedly cleaning for 2-3 times to obtain repaired soil.

One or more embodiments of the present invention may have the following advantages over the prior art:

(1) The eluent is suitable for As and BaP composite polluted soil and has a certain broad spectrum;

(2) In the screening and compounding process of the leaching agent, the leaching efficiency and the environmental friendliness are comprehensively considered. The heavy metals with combined pollution can be treated for reaching the standard once, so that the cost is reduced and the efficiency is improved; the leaching agent is green and biodegradable, has no secondary pollution, and is convenient for the recycling of the leached soil.

(3) The compound eluent has higher As and BaP removal rate on the composite polluted soil, and can meet the restoration requirement on the actual field soil.

Drawings

FIG. 1 is a repair flow chart for repairing arsenic and benzopyrene in a contaminated soil.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the following examples and the accompanying drawings.

The embodiment provides a eluting agent and a repairing method for repairing arsenic and benzopyrene in composite polluted soil, which solve the technical problems that the existing eluting agent has limited efficiency for removing As and BaP, secondary pollution after leaching the soil and high treatment cost.

In the embodiment, the experimental soil is selected to artificially simulate As polluted soil, the BaP polluted soil and the actual construction land As and BaP combined polluted soil to carry out leaching experiments. The type and the concentration of pollutants can be controlled by manually simulating the polluted soil, so that the restoring effect of the eluent on the soil is better studied; environmental conditions can be controlled in a laboratory, the experimental process can be repeated, and the experimental reliability is improved; the investigation cost can be reduced without the need of performing an in-field investigation. The compound leaching agent is mainly prepared by comparing and screening out a proper compound leaching agent in artificial simulated soil, and is used for leaching and restoring the construction land soil, wherein the pollution risk screening value and the control value of the construction land soil are shown in table 1:

TABLE 1

The physicochemical properties and pollutant content of each experimental soil are shown in table 2 below:

TABLE 2

Meanwhile, the embodiment also provides a repairing method (shown in figure 1) for repairing arsenic and benzopyrene in the composite polluted soil, which comprises the following steps:

Example 1

And (3) selecting artificial simulation As contaminated soil to carry out leaching experiments, and mixing the soil to be treated and the leaching agent into a centrifuge tube according to the volume of 1:12g/mL before the experiments. Wherein the concentration of oxalic acid in the eluent is 0.5mol/L, the concentration of saponin is 30g/L, and the volume ratio of the oxalic acid to the saponin is 1:1; placing the centrifuge tube on a constant temperature oscillator, oscillating for 14h at 200r/min, placing the centrifuge tube in a centrifuge, centrifuging for 10min at 4000r/min, taking a proper amount of supernatant fluid, passing through a 0.45 mu m filter membrane, and measuring the concentration of As in the supernatant fluid. And (3) after the residual eluent in the centrifuge tube is removed, adding ultrapure water, and oscillating and cleaning the soil for 3 times to obtain the repaired soil.

Example 2

In the embodiment, the artificial simulation As contaminated soil is selected to carry out leaching experiments, and the soil to be treated and the leaching agent are mixed in a centrifuge tube at a volume of 1:15g/mL before the experiments. Wherein, the concentration of oxalic acid in the eluent is 0.5mol/L, the concentration of sophorolipid is 40g/L, and the volume ratio of the two is 1:1; placing the centrifuge tube on a constant temperature oscillator, oscillating for 12 hours at 200r/min, placing the centrifuge tube in a centrifuge, centrifuging for 10 minutes at a rotating speed of 4000r/min, taking a proper amount of supernatant fluid, passing through a 0.45 mu m filter membrane, and measuring the concentration of As in the supernatant fluid. And (3) after the residual eluent in the centrifuge tube is removed, adding ultrapure water, and oscillating and cleaning the soil for 3 times to obtain the repaired soil.

Example 3

In the embodiment, the artificial simulation As contaminated soil is selected to carry out leaching experiments, and the soil to be treated and the leaching agent are mixed in a centrifuge tube at a volume of 1:15g/mL before the experiments. Wherein the concentration of oxalic acid in the eluent is 0.5mol/L, the concentration of rhamnolipid is 10g/L, and the volume ratio of the two is 1:1; placing the centrifuge tube on a constant temperature oscillator, oscillating for 12 hours at 200r/min, placing the centrifuge tube in a centrifuge, centrifuging for 10 minutes at a rotating speed of 4000r/min, taking a proper amount of supernatant fluid, passing through a 0.45 mu m filter membrane, and measuring the concentration of As in the supernatant fluid. And (3) after the residual eluent in the centrifuge tube is removed, adding ultrapure water, and oscillating and cleaning the soil for 3 times to obtain the repaired soil.

Example 4

In the embodiment, the artificial simulation As contaminated soil is selected to carry out leaching experiments, and the soil to be treated and the leaching agent are mixed in a centrifuge tube at a volume of 1:15g/mL before the experiments. Wherein, the concentration of citric acid in the eluent is 0.75mol/L, the concentration of saponin is 30g/L, and the volume ratio of the two is 1:1; placing the centrifuge tube on a constant temperature oscillator, oscillating for 12 hours at 200r/min, placing the centrifuge tube in a centrifuge, centrifuging for 10 minutes at a rotating speed of 4000r/min, taking a proper amount of supernatant fluid, passing through a 0.45 mu m filter membrane, and measuring the concentration of As in the supernatant fluid. And (3) after the residual eluent in the centrifuge tube is removed, adding ultrapure water, and oscillating and cleaning the soil for 3 times to obtain the repaired soil.

Example 5

In the embodiment, the artificial simulation As contaminated soil is selected to carry out leaching experiments, and the soil to be treated and the leaching agent are mixed in a centrifuge tube at a volume of 1:15g/mL before the experiments. Wherein the concentration of oxalic acid in the eluent is 0.75mol/L, the concentration of saponin is 30g/L, and the volume ratio of the oxalic acid to the saponin is 1:1; placing the centrifuge tube on a constant temperature oscillator, oscillating for 12 hours at 200r/min, placing the centrifuge tube in a centrifuge, centrifuging for 10 minutes at a rotating speed of 4000r/min, taking a proper amount of supernatant fluid, passing through a 0.45 mu m filter membrane, and measuring the concentration of As in the supernatant fluid. And (3) after the residual eluent in the centrifuge tube is removed, adding ultrapure water, and oscillating and cleaning the soil for 3 times to obtain the repaired soil.

To verify the leaching effect of the compound leaching agent of this example on As contaminated soil, comparative experiments #1-6 were also performed in this example, in which #1 used oxalic acid with a concentration of 0.5mol/L As a leaching solution, #2 used citric acid with a concentration of 0.75mol/L As a leaching solution, #3 used malic acid with a concentration of 0.75mol/L As a leaching solution, #4 used saponin with a concentration of 30g/L As a leaching solution, and #5 used oxalic acid with a volume ratio of 1:3 of 0.5mol/L and saponin with a volume ratio of 30g/L As a leaching solution, #6 used oxalic acid with a concentration of 3:1 of 0.5mol/L and saponin with a concentration of 30g/L As leaching solutions, and the same leaching steps As described above were adopted to leach the soil, respectively, and the As removal rate results after leaching are shown in table 3 below.

TABLE 3 Table 3

As can be seen from Table 3, the removal rate of As in the contaminated soil by the eluent of example 1 was 71.42% which is significantly higher than that of comparative tests #1-5 under the same conditions. Example 1 after leaching of simulated As contaminated soil, the As content in the soil was 48.72mg/kg, which was below the risk screening value for the second site of construction. Examples 2-5 demonstrate that the use of the selected organic acid and the selected biosurfactant in combination provides a good leaching effect on the soil contaminated with simulated As, better than single leaches. In the comparative experiments #1-4, the single organic acid solution and the saponin solution can effectively rinse As of the polluted soil, but the removal effect is also improved. According to the invention, in the comparative test #5-6, the oxalic acid and the saponin are compounded, so that the As removal rate is obviously improved, because the saponin has a solubilization function, the dissolution of As in water can be promoted, the leaching rate is accelerated, and simultaneously, characteristic groups such As hydroxyl, carboxyl and the like in the molecular structure of the saponin can be complexed with the As, so that the leaching effect is enhanced.

As can be seen from Table 3, in the process of removing As in the artificially simulated As contaminated soil, the oxalic acid and saponin compound eluent provided in the embodiment 1 of the invention can significantly improve the removal rate of the As in the soil by a single oxalic acid solution or saponin solution, and the content of the As in the treated soil is lower than the soil contamination risk screening value of the second type of land for construction.

Example 6

In the embodiment, manual simulation BaP contaminated soil is selected to carry out leaching experiments, and the soil to be treated and the leaching agent are mixed in a centrifuge tube at a volume of 1:15g/mL before the experiments. Wherein the concentration of oxalic acid in the eluent is 0.5mol/L, the concentration of saponin is 30g/L, and the volume ratio of the oxalic acid to the saponin is 1:1; placing the centrifuge tube on a constant temperature oscillator to oscillate for 8 hours at 200r/min, placing the centrifuge tube in a centrifuge to centrifuge for 10 minutes at the rotating speed of 4000r/min, taking a proper amount of supernatant fluid, passing through a 0.22 mu m filter membrane, and measuring the concentration of BaP in the supernatant fluid. And (3) after the residual eluent in the centrifuge tube is removed, adding ultrapure water, and oscillating and cleaning the soil for 3 times to obtain the repaired soil.

In order to verify the leaching effect of the compound leaching agent on the BaP contaminated soil, comparative experiments #6-7 are also carried out in the embodiment, wherein #6 uses oxalic acid with the volume ratio of 1:1 concentration of 0.5mol/L and rhamnolipid with the volume ratio of 30g/L as leaching solutions, #7 uses citric acid with the volume ratio of 1:1 concentration of 0.5mol/L and saponin with the volume ratio of 30g/L as leaching solutions, the soil is leached by adopting the same leaching steps as the above, and the leaching results of the BaP removal rate are shown in the following table 4.

TABLE 4 Table 4

As can be seen from Table 4, the removal rate of BaP in the soil by the oxalic acid and saponin compound eluent of example 2 is 31.62%, which is obviously higher than that of comparative test #7-8 under the same condition. Example 2 after leaching of an artificially simulated BaP contaminated soil, the BaP content in the soil was 4.12mg/kg, but the risk screening value for the second land of the construction land had not been reached. The oxalic acid and rhamnolipid compound eluent and the citric acid and saponin compound eluent in the comparative experiments #7-8 have a certain leaching effect on the BaP of the polluted soil, and the oxalic acid and the saponin are better in leaching effect on the BaP polluted soil.

From table 4, it can be seen that the oxalic acid and saponin compound eluting agent provided in the embodiment 6 of the present invention can significantly improve the removal rate of BaP in soil when used for eluting artificially simulated BaP contaminated soil.

Example 7

As and BaP composite polluted soil of a certain shipyard in xx city for moving a left place is selected, and the soil block before moving is mainly used for production activities such As container production and stacking, hull preassembling, hull outfitting sectional installation, permanent steel structure manufacturing and maintenance and the like. The experimental soil is pretreated before being used, naturally dried in air, removed with impurities such as sand and the like, and ground and screened by a 100-mesh sieve for standby. Prior to testing, the soil to be treated and the leaching agent are mixed in a centrifuge tube in a volume of 1:12 g/mL. Wherein the concentration of oxalic acid in the eluent is 0.5mol/L, the concentration of saponin is 30g/L, and the volume ratio of the oxalic acid to the saponin is 1:1; placing the centrifuge tube on a constant temperature oscillator, oscillating for 14 hours at 200r/min, placing the centrifuge tube in a centrifuge, centrifuging for 10 minutes at a rotating speed of 4000r/min, taking a proper amount of supernatant fluid, passing through a 0.45 mu m filter membrane, and measuring the concentration of As in the supernatant fluid; after passing an appropriate amount of the supernatant through a 0.22 μm filter, the concentration of BaP in the supernatant was determined. Finally, the residual eluent in the centrifuge tube is discarded, ultrapure water is added, and the soil is cleaned for 3 times by shaking, so that the repaired soil is obtained.

Example 8

According to the embodiment, as and BaP composite polluted soil of a shipyard moving leaving site in xx city is selected, and is subjected to pretreatment, natural air drying, removal of impurities such As sand and the like, grinding and sieving with a 100-mesh sieve for later use before experimental soil is used. Prior to testing, the soil to be treated and the leaching agent are mixed in a centrifuge tube in a volume of 1:12 g/mL. Wherein the concentration of oxalic acid in the eluent is 0.5mol/L, the concentration of saponin is 10g/L, and the volume ratio of the oxalic acid to the saponin is 1:1; placing the centrifuge tube on a constant temperature oscillator, oscillating for 14 hours at 200r/min, placing the centrifuge tube in a centrifuge, centrifuging for 10 minutes at a rotating speed of 4000r/min, taking a proper amount of supernatant fluid, passing through a 0.45 mu m filter membrane, and measuring the concentration of As in the supernatant fluid; after passing an appropriate amount of the supernatant through a 0.22 μm filter, the concentration of BaP in the supernatant was determined. Finally, the residual eluent in the centrifuge tube is discarded, ultrapure water is added, and the soil is cleaned for 3 times by shaking, so that the repaired soil is obtained.

Example 9

According to the embodiment, as and BaP composite polluted soil of a shipyard moving leaving site in xx city is selected, and is subjected to pretreatment, natural air drying, removal of impurities such As sand and the like, grinding and sieving with a 100-mesh sieve for later use before experimental soil is used. Prior to testing, the soil to be treated and the leaching agent are mixed in a centrifuge tube in a volume of 1:12 g/mL. Wherein the concentration of oxalic acid in the eluent is 0.25mol/L, the concentration of saponin is 30g/L, and the volume ratio of the oxalic acid to the saponin is 1:1; placing the centrifuge tube on a constant temperature oscillator, oscillating for 14 hours at 200r/min, placing the centrifuge tube in a centrifuge, centrifuging for 10 minutes at a rotating speed of 4000r/min, taking a proper amount of supernatant fluid, passing through a 0.45 mu m filter membrane, and measuring the concentration of As in the supernatant fluid; after passing an appropriate amount of the supernatant through a 0.22 μm filter, the concentration of BaP in the supernatant was determined. Finally, the residual eluent in the centrifuge tube is discarded, ultrapure water is added, and the soil is cleaned for 3 times by shaking, so that the repaired soil is obtained.

In order to verify the leaching effect of the compound leaching agent on the soil with the As and BaP combined pollution in the actual field, comparative experiments #9-10 are also carried out in the embodiment, wherein #9 uses oxalic acid with the concentration of 0.5mol/L As leaching agent, #10 uses saponin with the concentration of 30g/L As leaching agent, the soil is leached by adopting the same leaching steps, and the results of the removal rate of As and BaP after leaching are shown in the following table 5.

TABLE 5

As can be seen from Table 5, the removal rates of As and BaP in the soil by the oxalic acid and saponin compound eluent in the embodiment 7 of the invention are 55.57 and 33.4%, the contents of As and BaP in the leached soil are 35.01mg/kg and 1.43mg/kg respectively, and the repaired soil reaches the risk screening value of the second type of land for construction land, so that the eluent is suitable for the repairing application of the construction land. Examples 7-9 show that the oxalic acid and saponin compound has good leaching effect on the soil polluted by the As and BaP compound, and can remove the As and the BaP in the soil. The oxalic acid solution of the comparative test #9 has a good removal rate for As, the saponin solution of the comparative test #10 has a good removal rate for BaP in polluted soil, and the compound leaching agent provided by the invention can mutually promote the removal effect of pollutants.

Example 10

In examples 1-5 and comparative experiments #1-6 it can be seen that the organic acid contributes mainly to the leaching of As in contaminated soil, whereas the addition of biosurfactants increases the leaching rate of As, mainly biosurfactants reduce the surface tension and promote the dissolution of poorly soluble arsenics. In example 6 and comparative experiments #7-8, it can be seen that the organic acid and biosurfactant compound have a certain leaching effect on BaP in contaminated soil, but the leaching rate is only 31.62% at maximum, and a large lifting space is provided. Examples 7-9 and comparative experiments #9-10 show that the organic acid and the biosurfactant are compounded to have leaching effects on As and BaP in the soil polluted by the actual construction land, and can reach the risk screening value of the second kind of land of the construction land. In order to improve the leaching rate of As and BaP, the leaching conditions such As the selection of the leaching agent reagent, the compound volume ratio, the solid-liquid ratio and the like can be optimized in one step. It has been reported that the combination of two biosurfactants can effectively reduce the surface tension of the solution (Yaox Dan, 2021) at a smaller concentration, which not only saves the cost but also improves the leaching rate of pollutants in the soil. Based on the above, the embodiment provides the leaching agent for leaching and repairing the As and BaP composite polluted soil, wherein the leaching agent is prepared by compounding organic acid and a biosurfactant. Wherein the organic acid can be selected from one of common organic acids such as oxalic acid, citric acid, malic acid, etc., and the biosurfactant can be selected from at least one of common biosurfactants such as sophorolipid, rhamnolipid, saponin, soapberry, etc. The organic acid and biosurfactant compound leaches As and BaP technical scheme table 6.

TABLE 6

Although the embodiments of the present invention are described above, the embodiments are only used for facilitating understanding of the present invention, and are not intended to limit the present invention. Any person skilled in the art can make any modification and variation in form and detail without departing from the spirit and scope of the present disclosure, but the scope of the present disclosure is still subject to the scope of the appended claims.

Claims

1. The eluting agent for repairing the arsenic and the benzopyrene in the composite polluted soil is characterized by comprising organic acid and a biosurfactant, wherein the volume ratio of the organic acid to the biosurfactant is 1-3: 3 to 1;

the organic acid is at least one of oxalic acid, citric acid and malic acid;

2. The eluent for restoring arsenic, benzopyrene in composite contaminated soil according to claim 1, wherein the molar concentration of said organic acid is 0.5mol/L; the molar concentration of the biosurfactant is 30g/L.

3. The eluent for repairing arsenic and benzopyrene in composite contaminated soil according to claim 1, wherein the volume ratio of organic acid to biosurfactant is 1:1.

4. the repair method for repairing arsenic and benzopyrene in the composite contaminated soil is characterized by comprising the following steps of:

5. The method for repairing arsenic and benzopyrene in composite contaminated soil according to claim 4,

the organic acid is at least one of oxalic acid, citric acid and malic acid;

6. The method for repairing arsenic and benzopyrene in a contaminated soil according to claim 4, wherein the molar concentration of said organic acid is 0.5mol/L; the molar concentration of the biosurfactant is 30g/L.

7. The method for repairing arsenic and benzopyrene in composite contaminated soil according to claim 4, wherein the volume ratio of the organic acid to the biosurfactant is 1-3: 3 to 1.

8. The method for repairing arsenic and benzopyrene in composite contaminated soil according to claim 4, wherein the oscillation time of the oscillator in the step 2 is 8-16 h.

9. The method for repairing arsenic and benzopyrene in a composite contaminated soil according to claim 4, wherein the solid-to-liquid ratio of the contaminated soil to the eluent is 1g:10ml to 1g:15ml.