A leaching agent for remediation of severely petroleum-contaminated soil and a preparation method thereof

Abstract

The present application relates to a kind of biological eluent composition applied to severe oil-contaminated soil remediation and oil-containing sludge treatment, wherein, based on the total mass of the composition, it contains: (1) biological surfactant, content is 0.05-5.0wt%; (2) synergist, content is 0.02-5.0wt%; (3) ion regulator, content is 0.02-3.0wt%; (4) the rest is mainly water; the biological surfactant is selected from one or more of rhamnolipid, esterified modified sophorose ester and sulfonated modified sophorolipid, the synergist is peroxide, and the ion regulator is selected from nitrogen-phosphorus type inorganic salt. The eluent can effectively separate the oil phase in the severe oil-contaminated soil and the high oil-containing sludge, reduce the adhesion of the oil phase on the surface of soil particles, enhance the solubility of the oil phase in the solution, and has the advantages of high efficiency, short processing cycle and easy biodegradation.

Description

TECHNICAL FIELD

[0001] The present application relates to a biological eluent, in particular to a biological eluent for remediation of severely oil-contaminated soil and a preparation method thereof. BACKGROUND

[0002] Soil, as an important environment foundation for human beings, animals, plants and microorganisms, is an important place for material and energy in nature to participate in transformation, migration and accumulation, and other cycle processes. However, with the development of modern civilization, soil pollution problems have become increasingly prominent. At present, soil pollution is considered as one of the three major pollutions along with air pollution and water pollution, and has become a hot spot of attention of the society.

[0003] Pipeline transportation has been the main mode of oil transportation in China. However, due to the aging, corrosion, construction and human damage of oil pipelines, a large amount of oil is leaked due to pipeline damage and perforation, causing environmental pollution around the pipeline. If no effective measures are taken to deal with it in time, the leaked oil will enter the soil. More seriously, the toxic substances in the leaked oil will gradually accumulate in the bodies of animals and plants, and then pose a threat to human health. China has introduced the Action Plan for Prevention and Control of Soil Pollution in 2016, which further emphasizes the seriousness and importance of oil-contaminated soil remediation. With the continuous increase of overseas projects of China's oil industry, the requirements for environmental protection are more stringent. Governments of various countries attach great importance to soil pollution problems, and it is more urgent to study the problem of oil-contaminated soil. Therefore, it is of great significance to study the remediation technology for quickly and efficiently treating high-concentration oil-contaminated soil.

[0004] Currently, the common soil oil pollution remediation methods mainly include physical method, chemical method and biological and comprehensive method. Chemical remediation method is a commonly used method for soil remediation, mainly including solvent extraction method, oxidation removal method and chemical leaching method, etc. Extraction method is a method for extracting oil in contaminated soil samples with organic solvents based on the principle of similar solubility, transferring oil hydrocarbons in contaminated soil to solvents, and then separating. Common extractants include organic solutions, vegetable oils, supercritical fluids and subcritical fluids, etc. Extraction method is suitable for remediation of high-concentration contaminated soil, but it needs to be operated under high pressure conditions, and has high requirements for equipment, long processing flow, complex process, high cost and secondary pollution, and is not suitable for large-area pollution. Chemical oxidation method is a method for adding oxidizing agent to soil to react with pollutants to remove pollutants. Chemical oxidation technology has the characteristics of fast remediation speed and wide application, and is widely used in oil tank leakage site remediation. Chemical oxidation technology is to add chemical oxidants such as potassium permanganate and hydrogen peroxide to soil, so that they react with pollutants to oxidize and decompose organic pollutants in soil, thereby achieving the purpose of remediation. Chemical oxidation technology has the advantages of fast remediation rate, low application requirement for soil, wide application range for types and degrees of pollutants, etc.

[0005] [CN105772499A] discloses a kind of in situ combined remediation method of oil contaminated site soil, wherein, using sodium thiosulfate as oxidizing agent and sodium hydroxide as activator to chemically oxidize pollutants, then adding nitrogen, phosphorus and other nutrient salts to stimulate microbial remediation of oil contaminated soil. After 30 days of remediation of the actual contaminated soil with a petroleum concentration of 15000 mg / kg, the petroleum concentration is reduced to 5000 mg / kg.

[0006] [CN107057711B] discloses a method for degrading o-chloronitrobenzene in soil using soil chemical oxidation remediation additives, which uses potassium persulfate as an oxidizing agent, iron-containing compounds inherent in soil as a catalyst, and an additive with rich functional groups to degrade o-chloronitrobenzene in soil at a rate of 81.35%.

[0007] Leaching technology changes the interaction force between pollutants and soil particles through interfacial action, allowing pollutants to separate from the surface of soil particles, thereby achieving the purpose of soil remediation. Surfactants have hydrophilic groups and lipophilic groups, which can exist stably at the oil-water interface. When the mass concentration of surfactants is lower than the critical micelle concentration, the surface tension between the liquid-solid two phases can be reduced; when the mass concentration is higher than the critical micelle concentration, the solubility of the oil phase in the surfactant solution can be significantly enhanced, allowing the oil pollutants to be washed out of the soil.

[0008] Generally, the currently artificially synthesized surfactants contain environmental hormones, have certain biological toxicity, are easy to cause secondary pollution, and for the soil polluted by various types of oil, chemical leaching agents need to be developed to meet the removal of different types of oil pollutants. Especially, heavy oil pollution often has high content of gum and asphaltene, and the adhesion on the soil particles is strong, so it is difficult to separate the oil pollutants from the soil surface by the leaching effect of the surfactant alone. The pure chemical method needs to consume a large amount of chemical drugs, the processing cost is high, and the residual amount of the drugs is large, which is easy to cause secondary pollution. Therefore, it is necessary to develop a leaching agent for heavy oil contaminated soil and oil-containing sludge. SUMMARY

[0009] The purpose of the present application is to provide a biological leaching agent and a preparation method thereof for the remediation of heavy oil contaminated soil and the treatment of oil-containing sludge.

[0010] In a first aspect, the present application provides a biological leaching agent composition, which contains the following components based on the total mass of the composition: (1) a biological surfactant, the content being 0.05-5.0wt%; (2) a synergist, the content being 0.02-5.0wt%; (3) an ion regulator, the content being 0.02-3.0wt%; and (4) the rest is mainly water.

[0011] The biological surfactant is selected from one or more of rhamnolipid, esterified modified sophorolipid, sulfonated modified sophorolipid, etc., preferably lactone type modified sophorolipid and sulfonated modified sophorolipid, the content being 0.05-5.0wt%, preferably 0.2-3.0wt%.

[0012] The esterified modified sophorolipid has the following structure:

[0013]

[0014] The esterified modified sophorolipid can be obtained by esterification reaction of lactone type sophorolipid and monohydric alcohol in the presence of water under the catalysis of organic acid.

[0015] The esterified modified sophorolipid is preferably prepared by the following method (for detailed preparation method, refer to Chinese patent application 202010878388.0): (1) contacting and reacting lactone type sophorolipid solution with monohydric alcohol in the presence of a soluble long-chain sulfonic acid catalyst; (2) adjusting the pH of the reaction product to neutral by adding a base, to obtain an esterified modified sophorolipid composition, which contains esterified modified sophorolipid, soluble long-chain sulfonate and water.

[0016] wherein the monohydric alcohol is selected from the group consisting of C1-C8 alkyl monohydric alcohols, such as methanol, ethanol, isopropanol, allyl alcohol, isoamyl alcohol, benzyl alcohol, and the like, preferably one or more of C1-C6 linear or branched alkyl monohydric alcohols, preferably methanol, ethanol, isopropanol, n-butanol, and the like.

[0017] wherein the molar ratio of the lactone sophorolipid to the monohydric alcohol is 1:3-50, preferably 1:5-15.

[0018] The soluble long-chain sulfonate salt can be selected from one or more of C8-C 16 linear or branched alkyl sulfonate, C8-C 16 linear or branched alkyl benzene sulfonate, C2-C 12 linear or branched alkyl naphthalene sulfonate, preferably C8-C 16 linear or branched alkyl benzene sulfonate, most preferably C 12 linear or branched alkyl benzene sulfonate.

[0019] wherein the reaction temperature can be 30-100℃, preferably 40-80℃. The reaction time can be 1-8 hours, preferably 2-5 hours.

[0020] The inventors of the present application have unexpectedly found that long-chain sulfonic acid type catalysts can form mixed aggregates with sophorolipids in a core-shell structure, producing a hydrophobic core, which has a solubilizing effect on alcohol, solubilizes alcohol to the hydrophobic region, and is closely arranged with sophorolipids and long-chain sulfonic acid, so that the esterification reaction can be carried out in the hydrophobic region, thereby reducing the adverse effects of water on the esterification reaction, not only improving the yield of the product, but also avoiding the water removal step of the raw material, and the reaction can be directly carried out using industrial sophorolipid raw materials. On the other hand, long-chain sulfonic acid not only acts as a catalyst, but also becomes a long-chain sulfonate with interfacial activity after being neutralized by alkali at the end of the reaction, which can synergistically act with esterified sophorolipids to improve wetting and oil washing effects.

[0021] The sulfonated modified sophorolipid has the following structure:

[0022]

[0023] The sulfonated modified sophorolipid is prepared by heating and stirring the lactone sophorolipid in an organic solvent, then adding a sulfonating agent to carry out a sulfonation reaction to obtain the sulfonated modified sophorolipid. (The preparation method can refer to Chinese patent application 201910826201.X):

[0024] The synergist is a peroxide, which can be selected from hydrogen peroxide, CaO2, Na2O2, and the like, preferably hydrogen peroxide, and the content is 0.02-5.0wt%, preferably 0.2-3.0wt%.

[0025] The ion regulator is selected from the group consisting of ammonium chloride, diammonium hydrogen phosphate, dipotassium hydrogen phosphate, sodium phosphate and other nitrogen-phosphorus type inorganic salts, wherein the monohydrogen phosphate salt such as diammonium hydrogen phosphate and dipotassium hydrogen phosphate is preferred, and the content is 0.02-3.0 wt%, preferably 0.1-2.0 wt%.

[0026] In a second aspect, the present application provides a preparation method of the biological type elution agent composition, comprising:

[0027] (1) adding the biological surfactant and the ion regulator in water, and stirring until the surfactant is completely dissolved;

[0028] (2) adding the synergist aqueous solution in the modified biological surfactant solution obtained in step (1) to obtain the biological elution agent solution.

[0029] The concentration of the synergist solution can be 0.02-5.0 wt%, preferably 0.2-3.0 wt%.

[0030] Specifically, the preparation method can be as follows:

[0031] (1) adding the biological surfactant and the ion regulator in water in proportion, stirring at room temperature for 30-60 min, and stirring at a speed of 200-300 rpm until the surfactant is completely dissolved, and then sealing and storing at room temperature in the dark;

[0032] (2) adding the synergist solution in the modified biological surfactant solution obtained in step (1) before the soil pretreatment to obtain the biological elution agent solution.

[0033] The biological type elution agent composition of the present application can be used in the following method:

[0034] (1) preparing a new type of biological elution agent solution, and loading the soil contaminated by petroleum and the elution agent solution into a container at a mass ratio of 1:3-1:5, and oscillating or stirring to make the biological type elution agent fully contact with the heavily petroleum contaminated soil or oil sludge.

[0035] (2) mixing the contaminated soil and the elution agent solution in a constant temperature water bath at a temperature of 50-80℃, and oscillating or stirring for 2-30 min, preferably 5-10 min, and then standing and settling for 12 h, so that the crude oil or hydrocarbons in the soil are stripped from the soil and float to the surface of the solution, and then the supernatant is poured and centrifuged for solid-liquid separation.

[0036] The elution agent of the present application is suitable for the remediation of heavily petroleum contaminated soil and the treatment of oil-containing sludge, and the content of petroleum pollutants in the heavily petroleum contaminated soil is greater than 10 wt%.

[0037] The leaching agent provided by this invention enhances the wettability of the leaching agent on the soil surface through biosurfactants, increasing the contact between the leaching agent and oily soil; it enables the synergist to effectively act on the oil phase, breaking down the highly viscous asphaltic petroleum components into lighter components and reducing viscosity; and the microbubble effect during the reaction process gives it better properties for stripping soil particles from the surface; at the same time, under the action of highly efficient biosurfactants and ion regulators, through the interfacial interaction of the oil-water-solid phase, petroleum pollutants are effectively stripped from the soil and enter the aqueous phase, thereby purifying the oily soil.

[0038] The detergent of this invention can be applied to soils and oily sludge with high petroleum pollution. It can not only efficiently remove petroleum pollutants, but also has biocompatibility and can be biodegraded in soil. Furthermore, the pH of the solution after rinsing is around 7, which will not inhibit the activity of microorganisms and will not cause secondary pollution to the environment.

[0039] Furthermore, the novel biological rinsing agent provided by this invention has a small amount of oxidant added, leaves little residue, and is low in cost. The preparation process is simple, the reaction conditions are mild, and it is environmentally friendly. Detailed Implementation

[0040] The present invention will now be described in detail with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0041] Methods for detecting the removal rate of petroleum hydrocarbons in soil:

[0042] This experiment used the infrared spectrophotometric method for determining petroleum in soil, as published by the Ministry of Environmental Protection in 2019.

[0043] The concentration of petroleum pollutants C0 in the original contaminated soil was determined, and the concentration of petroleum pollutants C1 extracted from the leached soil was determined.

[0044] The formula for calculating the petroleum removal rate is:

[0045] In the formula:

[0046] η represents the petroleum removal efficiency (%)

[0047] C0 represents the petroleum content in the original soil, in mg / kg.

[0048] C1 represents the petroleum content in the soil after leaching, in mg / kg.

[0049] Unless otherwise specified, the instruments, reagents, and materials used in the following embodiments are all conventional instruments, reagents, and materials already available in the prior art and can be obtained through legitimate commercial channels. Unless otherwise specified, the experimental methods and detection methods used in the following embodiments are all conventional experimental methods and detection methods already available in the prior art. The water used in the following examples is all deionized water commonly used in laboratories.

[0050] In the following examples, rhamnolipids were purchased from Shanxi Zhongnuo Biotechnology Co., Ltd. Lactone-type sophorolipids were purchased from Shandong Qilu Biotechnology Group Co., Ltd.

[0051] Preparation Example 1

[0052] Sulfonated modified sophorolipids were prepared using the following method:

[0053] 68.88 g (100.0 mmol) of lactone-type sophorolipid was dissolved in 500 mL of N,N-dimethylformamide and stirred continuously at 50 °C until completely dissolved. Then, 0.2 mol of a sulfur trioxide pyridine complex was added, and the reaction was carried out at 80 °C for 4 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain sulfonated modified sophorolipid in 99% yield.

[0054] Preparation Example 2

[0055] Methylated modified sophorolipids were prepared using the following method:

[0056] Weigh 60g of industrial lactone-type sophorolipid with a water content of 50% into a reaction flask, then add 16g of methanol and 10g of dodecylbenzenesulfonic acid sequentially. React at 65℃ for 4 hours. After the reaction is complete, adjust the pH of the system to neutral with NaOH aqueous solution to obtain the methylated modified sophorolipid system containing sodium dodecylbenzenesulfonate. No purification is required, and it can be used for rinsing effect evaluation.

[0057] Example 1

[0058] (1) Add 0.3g of rhamnolipin and 0.1g of ammonium chloride to 97.6g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain a rhamnolipin surfactant solution with added ion regulator, and store in a sealed container away from light.

[0059] (2) Before soil pretreatment, 2g of hydrogen peroxide (30% concentration) solution was added to the above rhamnolipid surfactant and ammonium chloride solution to obtain a bioleaching solution.

[0060] In this rinsing agent, the content of the bio-type surfactant is 0.3 wt%, the content of the synergist is 0.6 wt%, the content of the ion regulator is 0.1 wt%, and the remainder is water.

[0061] Example 2

[0062] (1) Add 0.5g of lactone-type sophorolipid and 0.5g of ammonium chloride to 97.0g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain lactone-type sophorolipid surfactant solution with added ion regulator, and store in a sealed container away from light.

[0063] (2) Before soil pretreatment, 2g of sodium peroxide (concentration 97%) solution was added to the above rhamnolipin surfactant solution to obtain a bio-leaching solution.

[0064] In this rinsing agent, the content of the bio-type surfactant is 0.5 wt%, the content of the synergist is 1.94 wt%, the content of the ion regulator is 0.5 wt%, and the remainder is water.

[0065] Example 3

[0066] (1) Add 2g of lactone-type sophorolipid and 0.3g of diammonium hydrogen phosphate to 96.7g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain lactone-type sophorolipid surfactant solution with added ion regulator, and store in a sealed container away from light.

[0067] (2) Before soil pretreatment, 1g of calcium peroxide (75% concentration) was added to the above-mentioned solution of lactone-type sophorolipid surfactant with added ion regulator to obtain a biological leaching solution.

[0068] In this rinsing agent, the content of the bio-type surfactant is 2.0 wt%, the content of the synergist is 0.75 wt%, the content of the ion regulator is 0.3 wt%, and the remainder is water.

[0069] Example 4

[0070] (1) Add 0.5g of sulfonated modified sophorolipid and 1g of dipotassium hydrogen phosphate to 94.5g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain a lactone type sophorolipid surfactant solution, and store it in a sealed container away from light.

[0071] (2) Before soil pretreatment, 4g of hydrogen peroxide solution (concentration 30%) was added to the above sulfonated modified sophorolipid surfactant solution to obtain a bio-leaching agent solution.

[0072] The rinsing agent contains 0.5 wt% of the bio-surfactant, 1.2 wt% of the synergist, 1.0 wt% of the ion regulator, and the remainder is water.

[0073] Example 5

[0074] (1) Add 0.5g of sulfonated modified sophorolipid and 1g of ammonium chloride to 94.5g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain a lactone type sophorolipid surfactant solution, and store it in a sealed container away from light.

[0075] (2) Before soil pretreatment, 4g of hydrogen peroxide solution (30%) was added to the above sulfonated modified sophorolipid surfactant solution to obtain a biological rinsing agent solution.

[0076] In this rinsing agent, the content of the bio-type surfactant is 0.5 wt%, the content of the synergist is 1.2 wt%, the content of the ion regulator is 1.0 wt%, and the remainder is water.

[0077] Example 6

[0078] (1) Add 0.5g of sulfonated modified sophorolipid and 1g of sodium phosphate to 94.5g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain sulfonated modified sophorolipid surfactant solution, and store in a sealed container away from light.

[0079] (2) Before soil pretreatment, 4g of hydrogen peroxide solution (concentration 30%) was added to the above lactone-type sophorolipid surfactant solution to obtain a biological rinsing solution.

[0080] In this rinsing agent, the content of the bio-type surfactant is 0.5 wt%, the content of the synergist is 1.2 wt%, the content of the ion regulator is 1.0 wt%, and the remainder is water.

[0081] Example 7

[0082] (1) Add 0.5g of methylated modified sophorolipid and 1g of ammonium chloride to 94.5g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain lactone type sophorolipid surfactant solution, and store in a sealed container away from light.

[0083] (2) Before soil pretreatment, 4g of hydrogen peroxide solution (30%) was added to the above sulfonated modified sophorolipid surfactant solution to obtain a biological rinsing agent solution.

[0084] In this rinsing agent, the content of the bio-type surfactant is 0.5 wt%, the content of the synergist is 1.2 wt%, the content of the ion regulator is 1.0 wt%, and the remainder is water.

[0085] Comparative Example 1

[0086] This comparative example illustrates the effectiveness of the biological rinsing agent without the addition of a synergist. (Compared with Example 4)

[0087] (1) Add 0.5g of sulfonated modified sophorolipid and 1g of dipotassium hydrogen phosphate to 95.5g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain a sulfonated sophorolipid surfactant solution with added ion regulator, and store in a sealed container away from light.

[0088] The content of the bio-type surfactant in the rinsing agent is 0.5 wt%, the content of the synergist is 0 wt%, the content of the ion regulator is 1 wt%, and the remainder is water.

[0089] Comparative Example 2

[0090] This comparative example illustrates the effectiveness of the bio-rinsing agent without the addition of synergists and ion modifiers. (Compared with Example 4)

[0091] (1) Add 0.5g of sulfonated modified sophorolipid to 99.5g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain sulfonated modified sophorolipid surfactant solution, and store in a sealed container away from light.

[0092] The content of the bio-type surfactant in the rinsing agent is 0.5 wt%, the content of the synergist is 0 wt%, the content of the ion regulator is 0 wt%, and the remainder is water.

[0093] Comparative Example 3

[0094] This comparative example illustrates the effectiveness of the bio-rinsing agent without the addition of modified sulfonated sophorolipids (compared to Example 4).

[0095] (1) Add 1g of dipotassium hydrogen phosphate to 95.0g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain a lactone-type sophorolipid surfactant solution, and store it in a sealed container away from light.

[0096] (2) Before soil pretreatment, 4g of hydrogen peroxide solution (30%) was added to the above lactone-type sophorolipid surfactant solution to obtain a bio-rinsing agent solution.

[0097] The content of the bio-type surfactant in the rinsing agent is 0 wt%, the content of the synergist is 1.2 wt%, the content of the ion regulator is 1.0 wt%, and the remainder is water.

[0098] Comparative Example 4

[0099] This comparative example illustrates the effectiveness of biological rinsing agents when the ion regulator is a non-nitrogen / phosphorus salt (compared to Example 4).

[0100] (1) Add 0.5g of sulfonated modified sophorolipid and 1g of sodium sulfate to 94.5g of aqueous solution, stir at room temperature and at 300rpm for 25min until fully mixed to obtain a lactone type sophorolipid surfactant solution, and store it in a sealed container away from light.

[0101] (2) Before soil pretreatment, 4g of hydrogen peroxide solution (30%) was added to the above lactone-type sophorolipid surfactant solution to obtain a bio-rinsing agent solution.

[0102] In this rinsing agent, the content of the bio-type surfactant is 0.5 wt%, the content of the synergist is 1.2 wt%, the content of the ion regulator is 1.0 wt%, and the remainder is water.

[0103] Test Example 1

[0104] 10g of high-oil-content soil (from Shengli Oilfield, petroleum content 106000mg / kg) was taken, and 50g of the leaching agent prepared in the above examples and comparative examples were added respectively. The mixture was placed in a constant-temperature water bath at 60℃ to ensure thorough contact and mixing of the contaminated soil and leaching agent solution. After shaking or stirring for 30 minutes, the mixture was allowed to settle for 12 hours to allow crude oil and hydrocarbon pollutants in the soil to be stripped from the soil and float to the surface of the solution. The supernatant was then poured off and centrifuged for solid-liquid separation. The petroleum content of the separated soil was determined, and the petroleum removal rate was calculated. The petroleum removal rate results for each example and comparative example are shown in Table 1.

[0105] Test Example 2

[0106] 10g of soil with ordinary oil content (taken from Shengli Oilfield, petroleum content 8457mg / kg) was taken, and 50g of the leaching agent prepared in the above examples and comparative examples were added respectively. Leaching was carried out according to the method of Test Example 1. The petroleum content of the separated soil was determined, and the petroleum removal rate was calculated. The results are shown in Table 2.

[0107] Table 1. Results of petroleum removal rate test in high-oil-content soils

[0108]

[0109] Table 2. Test results of petroleum removal rate in ordinary oily soils.

[0110]

[0111]

[0112] The results in Tables 1 and 2 show that the leaching agent and method provided by the present invention have significant leaching effects on both ordinary oil-contaminated soil and heavily oil-contaminated soil, especially on heavily oil-contaminated soil.

[0113] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A biological rinsing agent composition, based on the total mass of the composition, comprising: (1) a biological surfactant in a content of 0.2 to 3.0 wt%; (2) a synergist in a content of 0.2 to 3.0 wt%; (3) an ion regulator in a content of 0.1 to 2.0 wt%; and (4) water as the remainder; wherein the biological surfactant is selected from sulfonated modified sophorolipid, the synergist is selected from hydrogen peroxide, and the ion regulator is selected from dipotassium hydrogen phosphate.

2. A method for preparing the biological rinsing composition according to claim 1, comprising the following steps: (1) Add biological surfactants and ion regulators to the water; (2) Add an aqueous synergist solution to the modified biological surfactant solution obtained in step (1) to obtain a biological rinsing solution.

3. The application of the biological leaching agent composition of claim 1 in the remediation of petroleum-contaminated soil and the treatment of oily sludge.

4. The application according to claim 3, wherein the content of petroleum pollutants in the petroleum-contaminated soil is greater than 10 wt%.

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