A method and system for in-situ ex-situ repair of petroleum contaminated soil by multi-technology coupling

Abstract

The application relates to the technical field of contaminated soil remediation, and discloses a method and system for in-situ ex-situ remediation of petroleum-contaminated soil through multi-technology coupling. The method comprises the following steps: (1) collecting petroleum-contaminated soil and performing crushing treatment; (2) adding a glycolipid biological surfactant and an additive into the petroleum-contaminated soil obtained in step (1), and then performing ultrasonic treatment; (3) adding a microbial inoculum into the petroleum-contaminated soil obtained after the treatment in step (2); and (4) applying an electric field voltage to the petroleum-contaminated soil obtained in step (3) by using an electrodynamic treatment device. The method for in-situ ex-situ remediation of petroleum-contaminated soil through multi-technology coupling can significantly improve the remediation efficiency of the petroleum-contaminated soil, and specifically, the removal rate of petroleum hydrocarbon components C10-C40 can reach more than 85%, and the removal rate of polycyclic aromatic hydrocarbons can reach more than 65%.

Description

Technical Field

[0001] This invention relates to the field of contaminated soil remediation technology, specifically to a method and system for in-situ and ex-situ remediation of petroleum-contaminated soil using a combination of multiple technologies. Background Technology

[0002] During the extraction, storage, transportation, processing, and use of petroleum, petroleum hydrocarbon pollutants can enter the soil due to accidents, maintenance, improper operation, and leaks, altering the soil's physical and chemical properties and causing pollution and damage to the ecological environment. At the same time, aromatic hydrocarbons in petroleum hydrocarbon pollutants are highly toxic, posing a significant threat to human health.

[0003] Currently, remediation methods for petroleum hydrocarbon-contaminated soils include thermal desorption, chemical oxidation, gas-phase extraction, leaching, microbial remediation, and phytoremediation. Each remediation technology has different applicability and, to varying degrees, limitations such as damage to soil structure and properties, high treatment costs, secondary pollution, and low remediation efficiency.

[0004] Therefore, multi-technology coupled microbial remediation technology has become a research hotspot both domestically and internationally. For example, Chinese patent application CN113695369A discloses a method for in-situ remediation of petroleum hydrocarbon-contaminated soil using a multi-technology coupled process of multiphase extraction, chemical oxidation, and bioremediation; Chinese patent application CN112588814A discloses a method for in-situ remediation of contaminated soil using a combined electro-microbial process, which remediates petroleum hydrocarbon-contaminated soil using a synergistic electro-microbial process.

[0005] However, existing research results have significant limitations and are not conducive to engineering applications.

[0006] Taking Chinese patent application CN113695369A as an example, (1) this method is applicable to the remediation of soil containing NAPL-contaminated groundwater, but not suitable for the remediation of the main sources of pollution such as oily sludge / soil. However, the main source of pollution in the petrochemical industry is oily sludge / soil, which cannot be extracted in a multiphase manner; (2) chemical oxidants change the physical and chemical properties of the soil, which is not conducive to the subsequent degradation of petroleum functional bacteria, and there is a risk of secondary pollution; (3) after the petroleum degradation bacteria are put into place, the degradation conditions are not optimal, the degradation cycle is long and the efficiency is low.

[0007] Taking Chinese patent application CN112588814A as an example, (1) the texture, particle size, moisture content and other parameters of each piece of petroleum-contaminated soil and different parts of the same piece of soil are different, the degree of current enhancement stimulation is uneven, the degradation cycle is long and the efficiency is low; (2) the petroleum degradation bacteria liquid is lost quickly, the input is large and the environmental tolerance is poor, which affects the degradation efficiency.

[0008] As mentioned above, current in-situ remediation technologies that couple multiple technologies cannot meet the requirements of engineering applications. There is an urgent need for an efficient, rapid, and thorough in-situ remediation technology that couples multiple technologies to degrade petroleum hydrocarbon pollutants. Summary of the Invention

[0009] The purpose of this invention is to overcome the problems of long remediation cycles, low efficiency, and secondary pollution in existing bioremediation technologies for petroleum-contaminated soil. This invention provides a method and system for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach, which can significantly improve the remediation efficiency of petroleum-contaminated soil and improve soil quality. This multi-technology coupling system for in-situ and ex-situ remediation of petroleum-contaminated soil can meet the requirements of engineering applications.

[0010] To achieve the above objectives, the present invention provides a method for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach, the method comprising the following steps:

[0011] (1) Collect petroleum-contaminated soil, crush it to obtain petroleum-contaminated soil with a particle size of less than 5 mm;

[0012] (2) Add glycolipid biosurfactants and auxiliaries to the petroleum-contaminated soil obtained in step (1), and then perform ultrasonic treatment;

[0013] (3) Microbial agents are added to the petroleum-contaminated soil obtained after step (2), wherein the microbial agents include a wall material and a core material wrapped in the wall material, the wall material contains natural biodegradable materials, and the core material contains microorganisms capable of degrading petroleum hydrocarbons and biochar for adsorbing the microorganisms.

[0014] (4) An electric field voltage is applied to the petroleum-contaminated soil obtained in step (3) using an electro-powered treatment device, wherein the electro-powered treatment device includes a DC power supply, a control system and several graphite electrodes inserted into the petroleum-contaminated soil.

[0015] Preferably, in step (2), the amount of glycolipid biosurfactant used is 0.1-1 g / kg, and the amount of the auxiliary agent used is 0.1-1 g / kg.

[0016] Preferably, the weight ratio of the glycolipid biosurfactant to the adjuvant is 1:1-5.

[0017] Preferably, in step (2), the glycolipid biosurfactant is selected from one or more of rhamnolipin, trehalose, and sophorolipid.

[0018] Preferably, in step (2), the auxiliary agent is sodium sulfite and / or sodium carbonate.

[0019] Preferably, the conditions for ultrasonic treatment include: ultrasonic power of 50-80W, treatment time of 8-15min, temperature of 45-55℃, and number of treatments of 1-3.

[0020] Preferably, in step (3), the microorganisms capable of degrading petroleum hydrocarbons are Cellulomonas sp. and / or Pseudomonas sp., wherein the preservation number of Cellulomonas sp. is GDMCC No: 62343 and the preservation number of Pseudomonas sp. is GDMCC No: 62341.

[0021] Preferably, in step (3), the process of adding microbial agents includes: first adding a first microbial agent to the petroleum-contaminated soil, and then adding a second microbial agent, wherein the microorganisms contained in the core material of the first microbial agent are Cellulomonas sp., and the microorganisms contained in the core material of the second microbial agent are Pseudomonas sp.

[0022] Preferably, the dosage of the first microbial agent is 50-200g / kg, and the dosage of the second microbial agent is 50-100g / kg.

[0023] Preferably, the microbial agent is in granular form, with a bacterial load of Lg (CFU / g) ≥10, more preferably 10-12, and an encapsulation rate ≥90%, more preferably 90-95%.

[0024] Preferably, the method further includes preparing the microbial inoculant according to the following steps:

[0025] (1) Microbial inoculum and biochar are stirred, mixed and solidified to obtain microbial inoculum suspension;

[0026] (2) The natural biodegradable material, nitrogen source and phosphorus source are stirred and mixed in water to obtain a gel solution, and then heat-treated for sterilization to obtain a gel;

[0027] (3) Prepare a calcium chloride solution and then sterilize it by heat treatment;

[0028] (4) The microbial suspension obtained in step (1) and the gel obtained in step (2) are injected into the calcium chloride solution obtained in step (3), crosslinked, allowed to stand, filtered, and dried at low temperature to obtain granular microbial agent.

[0029] Preferably, the biochar is coconut shell biochar and / or crop biochar;

[0030] Preferably, the natural biodegradable material is at least one of sodium alginate, agar, and chitosan;

[0031] Preferably, the nitrogen source is at least one selected from urea, ammonium sulfate, ammonium nitrate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate;

[0032] Preferably, the phosphorus source is at least one selected from dipotassium hydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and sodium tripolyphosphate.

[0033] Preferably, in step (1), the amount of biochar used is 0.5-1.5 volumes relative to 100 volumes of the microbial inoculum, the mixing temperature is 30-37°C, and the curing time is 6-24 hours;

[0034] Preferably, in step (2), the weight ratio of the natural biodegradable material, the nitrogen source and the phosphorus source is 2-4:10-15:1, and the mixing time is 10-60 min; the heat treatment sterilization temperature is 115-130℃, and the time is 10-20 min.

[0035] Preferably, in step (4), the volume ratio of the microbial suspension to the gel is 1:8-12, the weight ratio of calcium chloride in the calcium chloride solution to the natural biodegradable material is 1:0.8-1.2, and the crosslinking time is 3-6 hours.

[0036] Preferably, in step (4), the applied electric field voltage is 80-120V / m, and the electric field is intermittently energized for 12 hours for 10-30 days.

[0037] A second aspect of the present invention provides a system for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach, the system comprising:

[0038] A soil collection device for collecting petroleum-contaminated soil;

[0039] A pretreatment device is used to crush the collected petroleum-contaminated soil to obtain petroleum-contaminated soil with a particle size of less than 5 mm.

[0040] An ultrasonic treatment device is used to mix and contact pre-treated petroleum-contaminated soil with glycolipid biosurfactants and auxiliaries, and then subject the mixture to ultrasonic treatment.

[0041] A microbial treatment device in which a soil mixture from an ultrasonic treatment device is mixed and contacted with a microbial agent, wherein the microbial agent comprises a wall material and a core material encapsulated in the wall material, the wall material containing a natural biodegradable material, and the core material containing microorganisms capable of degrading petroleum hydrocarbons and biochar for adsorbing the microorganisms;

[0042] An electro-dynamic treatment device, comprising a DC power supply, a control system, and several graphite electrodes inserted into petroleum-contaminated soil to which microbial agents have been applied, for electro-dynamic microbial treatment of petroleum-contaminated soil to which microbial agents have been applied;

[0043] The detection device is used to detect the content of petroleum hydrocarbons and aromatic hydrocarbons in pretreated petroleum-contaminated soil and soil treated with electrodynamic-microbial methods.

[0044] The method for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach, as described in this invention, significantly improves the remediation efficiency of petroleum-contaminated soil (remediation efficiency ≥ 85%) by utilizing ultrasound-microbial slow-release agent-electrodynamic multi-technology coupling in-situ and ex-situ remediation technology. In contrast, the remediation efficiencies of simple microbial remediation (remediation efficiency around 50%), ultrasound-microbial remediation (remediation efficiency around 60%), and electrodynamic-microbial remediation (remediation efficiency around 70%) are all significantly lower.

[0045] In a preferred embodiment, by combining two different microbial agents prepared separately in a specific order, not only can the remediation efficiency be further improved (up to 90% or more), but the removal rate of polycyclic aromatic hydrocarbons can also be significantly improved (up to 65% or more).

[0046] Moreover, the multi-technology coupled in-situ and ex-situ remediation system for petroleum-contaminated soil described in this invention can be manufactured as a mobile skid-mounted device, enabling mobile operation at multiple work sites, thereby improving the coverage and efficiency of bioremediation. Attached Figure Description

[0047] Figure 1 This is a flowchart of the multi-technology coupled in-situ and ex-situ remediation method for petroleum-contaminated soil described in this invention;

[0048] Figure 2 This is a schematic diagram of the system for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling method as described in this invention.

[0049] Biological Preservation

[0050] The Cellulomonas sp. of this invention was deposited on March 29, 2022, at the Guangdong Provincial Center for Microbial Culture Collection (Address: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, 510070, China) (abbreviation of depositary institution: GDMCC), with accession number GDMCC No: 62343.

[0051] The *Pseudomonas* sp. of this invention was deposited on March 29, 2022, at the Guangdong Provincial Center for Microbial Culture Collection (Address: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, 510070, China) (abbreviation of depositary institution: GDMCC), with accession number GDMCC No: 62341. Detailed Implementation

[0052] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0053] like Figure 1 As shown, the method for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach according to the present invention includes the following steps:

[0054] (1) Collect petroleum-contaminated soil, crush it to obtain petroleum-contaminated soil with a particle size of less than 5 mm;

[0055] (2) Add glycolipid biosurfactants and auxiliaries to the petroleum-contaminated soil obtained in step (1), and then perform ultrasonic treatment;

[0056] (3) Microbial agents are added to the petroleum-contaminated soil obtained after step (2);

[0057] (4) Apply an electric field voltage to the petroleum-contaminated soil obtained in step (3) using an electro-powered treatment device.

[0058] In the method described in this invention, when collecting petroleum-contaminated soil, soil samples are collected at different depths (0-30cm) and in batches (0-100kg / batch), depending on the extent of petroleum hydrocarbon contamination. In the specific implementation process, the petroleum-contaminated soil to be remediated is collected using a bucket and then fed into a receiving chamber via a chute. If the soil is silty / sandy, it is directly fed into a pretreatment chamber for crushing (i.e., pretreatment); if it is clayey soil, it needs to be mixed with fine sandy soil to adjust the properties of the clayey soil and improve pretreatment efficiency.

[0059] In the method described in this invention, during the crushing process, the collected petroleum-contaminated soil is crushed and sieved (e.g., the crushed soil is passed through a sieve with an aperture of 5 mm or less) to obtain petroleum-contaminated soil with a particle size of 5 mm or less. This crushing process can improve the treatment efficiency of petroleum hydrocarbon-contaminated soil. In this document, the term "particle size" refers to the maximum straight-line distance between any two distinct points on a particle; when the particle is spherical, the particle size refers to the diameter of the particle.

[0060] The method described in this invention may further include using infrared spectrophotometry to detect the content of C10-C40 petroleum hydrocarbons and aromatic hydrocarbons in pretreated petroleum-contaminated soil, as an indicator for evaluating the soil remediation effect.

[0061] In the method described in this invention, the purpose of ultrasonic treatment in step (2) is to reduce the viscosity between oil-contaminated soil particles, increase the porosity between particles, promote the separation of oil, mud, and water phases, and promote the decomposition and precipitation of oily substances therein.

[0062] In step (2), the glycolipid biosurfactant used can be one or more selected from rhamnolipids, trehaloses, and sophorolipids. These glycolipid biosurfactants are degradable and do not cause secondary pollution. The amount of the glycolipid biosurfactant used can be 0.1-1 g / kg, preferably 0.1-0.8 g / kg, and more preferably 0.2-0.6 g / kg. In this document, the unit "g / kg" for the amount of glycolipid biosurfactant used refers to the number of grams of the glycolipid biosurfactant required relative to one kilogram of petroleum-contaminated soil to be remediated.

[0063] In step (2), the adjuvant used may be sodium sulfite and / or sodium carbonate. The dosage of the adjuvant may be 0.1-1 g / kg, preferably 0.4-0.8 g / kg. In this document, the unit "g / kg" refers to the number of grams of the adjuvant required relative to one kilogram of petroleum-contaminated soil to be remediated.

[0064] In step (2), the weight ratio of the glycolipid biosurfactant to the adjuvant can be 1:1-5, preferably 1:2-3.

[0065] In the method described in this invention, the conditions for ultrasonic treatment may include: ultrasonic power of 50-80W, treatment time of 8-15min, temperature of 45-55℃, and number of treatments of 1-3.

[0066] In the method described in this invention, the microbial agent added in step (3) includes a wall material and a core material encapsulated within the wall material. The wall material contains natural biodegradable materials, and the core material contains microorganisms capable of degrading petroleum hydrocarbons and biochar for adsorbing the microorganisms. The microbial agent described in this invention is a slow-release agent, and this slow-release structure has a significantly better soil adsorption effect compared to directly adding microorganisms.

[0067] In this invention, various microorganisms known in the art capable of degrading petroleum hydrocarbons can be used. Preferably, to achieve better soil remediation results, the microorganisms used are *Cellulomonas* sp. and / or *Pseudomonas* sp., wherein the preservation number of *Cellulomonas* sp. is GDMCC No.: 62343, and the preservation number of *Pseudomonas* sp. is GDMCC No.: 62341. *Cellulomonas* sp. exhibits good effects in removing C1-C40 petroleum hydrocarbons, specifically including a total petroleum hydrocarbon (TPH) degradation rate of over 80%; *Pseudomonas* sp. exhibits good effects in removing polycyclic aromatic hydrocarbons (such as naphthalene, pyrene, etc.), specifically including a naphthalene degradation rate of over 65% and a pyrene degradation rate of over 65%. In a specific embodiment, the microbial bacteria in the microbial agent may be Cellulomonas sp. and / or Pseudomonas sp., that is, the microbial agent may contain only Cellulomonas sp., or only Pseudomonas sp., or a combination of Cellulomonas sp. and Pseudomonas sp.

[0068] In a preferred embodiment, the process of adding microbial agents in step (3) includes: first adding a first microbial agent to the petroleum-contaminated soil, and then adding a second microbial agent. The microorganisms contained in the core material of the first microbial agent are Cellulomonas sp., and the microorganisms contained in the core material of the second microbial agent are Pseudomonas sp. More preferably, the dosage of the first microbial agent is 50-200 g / kg, more preferably 60-180 g / kg, and even more preferably 80-150 g / kg; the dosage of the second microbial agent is 50-100 g / kg, more preferably 60-90 g / kg, and even more preferably 65-80 g / kg. In this document, the unit "g / kg" for the dosage of microbial agents refers to the number of grams of microbial agent required relative to one kilogram of petroleum-contaminated soil to be remediated. In the above preferred embodiment, by combining two different microbial agents prepared separately in a specific order, not only can the remediation efficiency be further improved (the remediation efficiency is as high as 90% or more), but the removal rate of polycyclic aromatic hydrocarbons can also be significantly improved (the removal rate is as high as 65% or more).

[0069] In the method described in this invention, preferably, the microbial agent is in granular form, with a bacterial load (Lg / g) ≥ 10, more preferably 10-12; and an encapsulation rate ≥ 90%, more preferably 90-95%. In this document, the bacterial load is determined by colony counting; the encapsulation rate is indirectly determined by the N / P content test method in the agent granules, as detailed below:

[0070] (1) Determination of bacterial load

[0071] Take a certain amount of microbial agent granules, crush them, and place them in 10ml of sterile water. Shake well and mix according to 10... -2 10 -4 10 -6 10 -8 10 -10 After serially diluting the samples and incubating at 37°C for 24 hours, record the colony count and calculate the colony count using the following formula:

[0072]

[0073] (2) Encapsulation rate determination

[0074] Take a certain amount of microbial agent granules, crush (ultrasonically break), and place in 10ml of sterile water. Shake well. Determine the total nitrogen (HJ636-2012) or total phosphorus (GC / T11893-1989) according to the method of the Ministry of Environmental Protection, and calculate according to the following formula:

[0075] Total N or P content (m2) in finished microbial agent granules:

[0076]

[0077]

[0078] In this invention, the microbial agent with a slow-release structure can be prepared by adsorption followed by encapsulation. In a specific embodiment, the multi-technology coupled in-situ and ex-situ remediation method for petroleum-contaminated soil may further include preparing the microbial agent according to the following steps:

[0079] (1) Microbial inoculum and biochar are stirred, mixed and solidified to obtain microbial inoculum suspension;

[0080] (2) The natural biodegradable material, nitrogen source and phosphorus source are stirred and mixed in water to obtain a gel solution, and then heat-treated for sterilization to obtain a gel;

[0081] (3) Prepare a calcium chloride solution and then sterilize it by heat treatment;

[0082] (4) The microbial suspension obtained in step (1) and the gel obtained in step (2) are injected into the calcium chloride solution obtained in step (3), crosslinked, allowed to stand, filtered, and dried at low temperature to obtain granular microbial agent.

[0083] In this invention, the biochar can be coconut shell biochar and / or crop biochar.

[0084] In this invention, the natural biodegradable material can be at least one of sodium alginate, agar, and chitosan.

[0085] In this invention, the nitrogen source can be at least one of urea, ammonium sulfate, ammonium nitrate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate.

[0086] In this invention, the phosphorus source can be at least one of dipotassium hydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and sodium tripolyphosphate.

[0087] In the process of preparing microbial inoculants, in step (1), the amount of biochar used can be 0.5-1.5 volumes relative to 100 volumes of the microbial inoculant solution, the mixing temperature can be 30-37℃, and the curing time can be 6-24h.

[0088] In the process of preparing microbial agents, in step (2), the weight ratio of the natural biodegradable material, the nitrogen source and the phosphorus source can be 2-4:10-15:1, and the stirring time can be 10-60 min; the heat treatment sterilization temperature can be 115-130℃, and the time can be 10-20 min.

[0089] In the process of preparing microbial agents, in step (4), the volume ratio of the microbial suspension to the gel can be 1:8-12, the weight ratio of calcium chloride in the calcium chloride solution to the natural biodegradable material can be 1:0.8-1.2, and the crosslinking time can be 3-6h.

[0090] In the multi-technology coupled in-situ and ex-situ remediation method for petroleum-contaminated soil described in this invention, an electric field voltage is applied to the petroleum-contaminated soil containing microbial agents using an electrodynamic treatment device. This promotes the release of microorganisms and their interaction with petroleum hydrocarbons and polycyclic aromatic hydrocarbons in the soil, thereby achieving a better soil remediation effect. In this invention, the electrodynamic treatment device may include a DC power supply, a control system, and several graphite electrodes inserted into the petroleum-contaminated soil. In specific implementation, the applied electric field voltage can be 80-120V / m, with intermittent energization for 12 hours for 10-30 days.

[0091] The method described in this invention may further include using infrared spectrophotometry to detect the C10-C40 petroleum hydrocarbon and aromatic hydrocarbon content in the soil after electrodynamic-microbial remediation treatment to determine whether the soil remediation meets the standards. Typically, after remediation treatment of petroleum-contaminated soil using the multi-technology coupled in-situ and ex-situ remediation method described in this invention, the removal rate of C10-C40 petroleum hydrocarbon components can reach over 85%, and the removal rate of polycyclic aromatic hydrocarbons can reach over 65%.

[0092] In this invention, the oil-contaminated soil is remediated according to the above-mentioned multi-technology coupling method for in-situ and ex-situ remediation of oil-contaminated soil. After the oil-contaminated soil has been remediated to the required standard, the treated soil can be uniformly backfilled in situ, thereby realizing the ex-situ remediation and in-situ landfill of oil-contaminated soil.

[0093] To implement the above-mentioned multi-technology coupled in-situ and ex-situ remediation method for petroleum-contaminated soil of the present invention, such as... Figure 2 As shown, the present invention also provides a system for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach, characterized in that the system comprises:

[0094] A soil collection device for collecting petroleum-contaminated soil;

[0095] A pretreatment device is used to crush the collected petroleum-contaminated soil to obtain petroleum-contaminated soil with a particle size of less than 5 mm.

[0096] An ultrasonic treatment device is used to mix and contact pre-treated petroleum-contaminated soil with glycolipid biosurfactants and auxiliaries, and then subject the mixture to ultrasonic treatment.

[0097] A microbial treatment device in which a soil mixture from an ultrasonic treatment device is mixed and contacted with a microbial agent, wherein the microbial agent comprises a wall material and a core material encapsulated in the wall material, the wall material containing a natural biodegradable material, and the core material containing microorganisms capable of degrading petroleum hydrocarbons and biochar for adsorbing the microorganisms;

[0098] An electro-dynamic treatment device, comprising a DC power supply, a control system, and several graphite electrodes inserted into petroleum-contaminated soil to which microbial agents have been applied, for electro-dynamic microbial treatment of petroleum-contaminated soil to which microbial agents have been applied;

[0099] The detection device is used to detect the content of petroleum hydrocarbons and aromatic hydrocarbons in pretreated petroleum-contaminated soil and soil treated with electrodynamic-microbial methods.

[0100] The multi-technology coupled in-situ and ex-situ remediation system for petroleum-contaminated soil described in this invention can be manufactured as a mobile skid-mounted device, enabling mobile operation at multiple work sites, thereby improving the coverage and efficiency of bioremediation.

[0101] The present invention will be described in detail below through examples and comparative examples.

[0102] The following examples are all in Figure 2 The system shown is implemented in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach, such as... Figure 2 As shown, the system includes a soil sampling device, a pretreatment device, an ultrasonic treatment device, a microbial treatment device, an electrodynamic treatment device, and a detection device. The detection device is used to detect the content of petroleum hydrocarbons and aromatic hydrocarbons in the pretreated petroleum-contaminated soil and the electrodynamic-microbial treated soil, respectively.

[0103] Example 1

[0104] This embodiment illustrates the method for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach as described in this invention.

[0105] The subject of this embodiment is: sandy soil contaminated by crude oil from an oil field. After sampling and analysis, the soil sample has an oil content of 4.2 wt%, including 69.7 wt% saturated hydrocarbons, 17.4 wt% aromatic hydrocarbons, 9.2 wt% colloids, and 3.7 wt% asphaltene.

[0106] (1) Collection and pretreatment of petroleum-contaminated soil

[0107] The depth of the oil-contaminated soil was 20cm. The collected soil entered the collection chamber through an inclined chute, and then it was crushed and screened with a screen aperture of 5mm to obtain soil to be treated with a particle size of less than 5mm.

[0108] (2) Ultrasonic treatment

[0109] Add 0.4 g / kg rhamnolipin (purchased from Xi'an Ruijie Biotechnology Co., Ltd., molecular weight 614.3) and 0.8 g / kg sodium sulfite to the soil to be treated, mix well, and then sonicate twice with an ultrasonic power of 65 W, an ultrasonic time of 12 min, and an ultrasonic temperature of 50 °C.

[0110] (3) Preparation and application of microbial agents

[0111] Preparation of the first microbial agent A1: 1% by volume of coconut shell charcoal was added to the bacterial suspension of Cellulomonas sp., stirred and mixed at 35°C, and solidified for 12 h to obtain a microbial suspension; 3 parts by weight of sodium alginate were dissolved in distilled water, 12 parts by weight of urea and 1 part by weight of dipotassium hydrogen phosphate were added, stirred and mixed for 30 min, and then heat-treated and sterilized at 121°C for 15 min, and a gel was obtained after cooling; 3 parts by weight of calcium chloride were prepared into a solution and heat-treated and sterilized, and then the microbial suspension and the gel were added to it, wherein the volume ratio of the microbial suspension to the gel was 1:10, crosslinked for 4 h, allowed to stand, filtered, and dried at low temperature (40°C) to obtain granular first microbial agent A1 with a bacterial load of 10 Lg (CFU / g) and an encapsulation rate of 90%.

[0112] Preparation of the second microbial agent B1: 1% by volume of coconut shell charcoal was added to the bacterial suspension of Pseudomonas sp., stirred and mixed at 35°C, and solidified for 12 h to obtain a microbial suspension; 3 parts by weight of sodium alginate were dissolved in distilled water, 12 parts by weight of urea and 1 part by weight of dipotassium hydrogen phosphate were added, stirred and mixed for 30 min, and then heat-treated and sterilized at 121°C for 15 min, and a gel was obtained after cooling; 3 parts by weight of calcium chloride were prepared into a solution and heat-treated and sterilized, and then the microbial suspension and the gel were added to it, wherein the volume ratio of the microbial suspension to the gel was 1:10, crosslinked for 4 h, allowed to stand, filtered, and dried at low temperature (40°C) to obtain granular second microbial agent B1 with a bacterial load of 11 Lg (CFU / g) and an encapsulation rate of 92%.

[0113] First, add 60 g / kg of the first microbial agent A1 to the ultrasonically treated petroleum-contaminated soil and stir for 10 min. Then, add 60 g / kg of the second microbial agent B1 and continue stirring for 10 min.

[0114] (4) Electrodynamic-microbial remediation and in-situ landfill

[0115] An electro-dynamic treatment device was used to apply an electric field voltage to petroleum-contaminated soil inoculated with microbial agents. The device included a DC power supply, a control system, and four cylindrical graphite electrodes inserted into the petroleum-contaminated soil. The applied electric field voltage was 100V / m, and the treatment was conducted intermittently for 20 days (12 hours per minute). Testing showed that the removal rate of petroleum hydrocarbons (C10-C40) was 93.8%, and the removal rate of polycyclic aromatic hydrocarbons such as naphthalene and pyrene was 67.9%, meeting the remediation requirements. The treated soil was then uniformly backfilled in situ.

[0116] Example 2

[0117] This embodiment illustrates the method for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach as described in this invention.

[0118] The subject of this embodiment is: sandy soil contaminated by crude oil from an oil field. After sampling and analysis, the soil sample has an oil content of 7.9 wt%, including 35.6 wt% saturated hydrocarbons, 25.6 wt% aromatic hydrocarbons, 22.5 wt% colloids, and 16.3 wt% asphaltene.

[0119] (1) Collection and pretreatment of petroleum-contaminated soil

[0120] The depth of the oil-contaminated soil was 20cm. The collected soil entered the collection chamber through an inclined chute, and then it was crushed and screened with a screen aperture of 5mm to obtain soil to be treated with a particle size of less than 5mm.

[0121] (2) Ultrasonic treatment

[0122] Add 0.2 g / kg trehalose lipid (purchased from Xi'an Boliante Chemical Co., Ltd., molecular weight 342.3) and 0.6 g / kg sodium sulfite to the soil to be treated, mix well, and then sonicate twice with an ultrasonic power of 50 W, an ultrasonic time of 15 min, and an ultrasonic temperature of 55 °C.

[0123] (3) Preparation and application of microbial agents

[0124] Preparation of the first microbial agent A2: 1% by volume of coconut shell charcoal was added to the bacterial suspension of Cellulomonas sp., stirred and mixed at 35°C, and solidified for 12 h to obtain a microbial suspension; 3 parts by weight of sodium alginate were dissolved in distilled water, 12 parts by weight of urea and 1 part by weight of dipotassium hydrogen phosphate were added, stirred and mixed for 30 min, and then heat-treated and sterilized at 121°C for 15 min, and a gel was obtained after cooling; 3 parts by weight of calcium chloride were prepared into a solution and heat-treated and sterilized, and then the microbial suspension and the gel were added to it, wherein the volume ratio of the microbial suspension to the gel was 1:10, crosslinked for 4 h, allowed to stand, filtered, and dried at low temperature (40°C) to obtain granular first microbial agent A2 with a bacterial load of 11 Lg (CFU / g) and an encapsulation rate of 92%.

[0125] Preparation of the second microbial agent B2: 1% by volume of coconut shell charcoal was added to the bacterial suspension of *Pseudomonas* sp., stirred and mixed at 35°C, and solidified for 12 h to obtain a microbial suspension; 3 parts by weight of sodium alginate were dissolved in distilled water, 12 parts by weight of urea and 1 part by weight of dipotassium hydrogen phosphate were added, stirred and mixed for 30 min, and then heat-treated at 121°C for 15 min to sterilize. After cooling, a gel was obtained; 3 parts by weight of calcium chloride were prepared into a solution and heat-treated for sterilization. Then, the microbial suspension and the gel were added to the solution, wherein the volume ratio of the microbial suspension to the gel was 1:10. Crosslinking was carried out for 4 h, and the solution was allowed to stand, filtered, and dried at low temperature (40°C) to obtain granular second microbial agent B2 with a bacterial load of 11 Lg (CFU / g) and an encapsulation rate of 93%.

[0126] First, add 100g / kg of the first microbial agent A2 to the ultrasonically treated petroleum-contaminated soil and stir for 10 minutes. Then, add 80g / kg of the second microbial agent B2 and continue stirring for 10 minutes.

[0127] (4) Electrodynamic-microbial remediation and in-situ landfill

[0128] An electro-dynamic treatment device was used to apply an electric field voltage to petroleum-contaminated soil inoculated with microbial agents. The device included a DC power supply, a control system, and four cylindrical graphite electrodes inserted into the petroleum-contaminated soil. The applied electric field voltage was 100V / m, and the treatment was conducted intermittently for 12 hours over 15 days. Testing showed that the removal rate of petroleum hydrocarbons (C10-C40) was 93.5%, and the removal rate of polycyclic aromatic hydrocarbons such as naphthalene and pyrene was 67.3%, meeting the remediation requirements. The treated soil was then uniformly backfilled in situ.

[0129] Example 3

[0130] This embodiment illustrates the method for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach as described in this invention.

[0131] The object of this embodiment is oily sludge from the bottom of a tank in a petrochemical plant. After sampling and analysis, the sludge has an oil content of 13.5 wt%, including 48.5 wt% saturated hydrocarbons, 20.8 wt% aromatic hydrocarbons, 20.3 wt% gum, and 10.4 wt% asphaltenes.

[0132] (1) Collection and pretreatment of petroleum-contaminated soil

[0133] The depth of the oil-contaminated soil was 30cm. The collected soil entered the collection chamber through an inclined chute, and then it was crushed and screened with a screen aperture of 5mm to obtain soil to be treated with a particle size of less than 5mm.

[0134] (2) Ultrasonic treatment

[0135] Add 0.3 g / kg sophorolipid and 0.7 g / kg sodium carbonate to the soil to be treated, mix well, and then sonicate twice with an ultrasonic power of 80 W, an ultrasonic time of 8 min, and an ultrasonic temperature of 45 °C.

[0136] (3) Preparation and application of microbial agents

[0137] Preparation of the first microbial agent A3: 1% by volume of coconut shell charcoal was added to the bacterial suspension of Cellulomonas sp., stirred and mixed at 35°C, and solidified for 12 h to obtain a microbial suspension; 3 parts by weight of sodium alginate were dissolved in distilled water, 12 parts by weight of urea and 1 part by weight of dipotassium hydrogen phosphate were added, stirred and mixed for 30 min, and then heat-treated and sterilized at 121°C for 15 min, and a gel was obtained after cooling; 3 parts by weight of calcium chloride were prepared into a solution and heat-treated and sterilized, and then the microbial suspension and the gel were added to it, wherein the volume ratio of the microbial suspension to the gel was 1:10, crosslinked for 4 h, allowed to stand, filtered, and dried at low temperature (40°C) to obtain granular first microbial agent A3 with a bacterial load of 12 Lg (CFU / g) and an encapsulation rate of 95%.

[0138] Preparation of the second microbial agent B3: 1% by volume of coconut shell charcoal was added to the bacterial suspension of *Pseudomonas* sp., stirred and mixed at 35°C, and solidified for 12 h to obtain a microbial suspension; 3 parts by weight of sodium alginate were dissolved in distilled water, 12 parts by weight of urea and 1 part by weight of dipotassium hydrogen phosphate were added, stirred and mixed for 30 min, and then heat-treated at 121°C for 15 min to sterilize. After cooling, a gel was obtained; 3 parts by weight of calcium chloride were prepared into a solution and heat-treated for sterilization. Then, the microbial suspension and the gel were added to the solution, wherein the volume ratio of the microbial suspension to the gel was 1:10. Crosslinking was carried out for 4 h, and the solution was allowed to stand, filtered, and dried at low temperature (40°C) to obtain granular second microbial agent B3 with a bacterial load of 10 Lg (CFU / g) and an encapsulation rate of 93%.

[0139] First, add 150g / kg of the first microbial agent A3 to the ultrasonically treated petroleum-contaminated soil and stir for 10 minutes. Then, add 75g / kg of the second microbial agent B3 and continue stirring for 10 minutes.

[0140] (4) Electrodynamic-microbial remediation and in-situ landfill

[0141] An electro-dynamic treatment device was used to apply an electric field voltage to petroleum-contaminated soil inoculated with microbial agents. The device included a DC power supply, a control system, and four cylindrical graphite electrodes inserted into the petroleum-contaminated soil. The applied electric field voltage was 100V / m, and the treatment was intermittently applied for 10 days over 12 hours. Testing showed that the removal rate of petroleum hydrocarbons (C10-C40) was 92.7%, and the removal rate of polycyclic aromatic hydrocarbons such as naphthalene and pyrene was 66.4%, meeting the remediation requirements. The treated soil was then uniformly backfilled in situ.

[0142] Example 4

[0143] This embodiment illustrates the method for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach as described in this invention.

[0144] The method of Example 1 was used to carry out in-situ remediation of petroleum-contaminated soil. The difference was that in step (3), only granular first microbial agent A1 was added to the ultrasonically treated petroleum-contaminated soil, and the amount added was 190g / kg.

[0145] Testing revealed that the removal rate of petroleum hydrocarbons (C10-C40) in the remediated soil was 90.4%, while the removal rate of polycyclic aromatic hydrocarbons such as naphthalene and pyrene was 52.8%.

[0146] Example 5

[0147] This embodiment illustrates the method for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach as described in this invention.

[0148] The method of Example 1 was used to carry out in-situ remediation of petroleum-contaminated soil. The difference was that in step (3), only granular second microbial agent B1 was added to the ultrasonically treated petroleum-contaminated soil, and the amount added was 190g / kg.

[0149] Testing revealed that the removal rate of petroleum hydrocarbons (C10-C40) in the remediated soil was 85.1%, while the removal rate of polycyclic aromatic hydrocarbons such as naphthalene and pyrene was 65.8%.

[0150] Comparative Example 1

[0151] The method of Example 1 was used to carry out in-situ remediation of petroleum-contaminated soil. The difference was that the ultrasonic treatment in step (2) was not carried out. Instead, microbial agents were directly added to the pretreated petroleum-contaminated soil and electrodynamic-microbial remediation was carried out.

[0152] Testing revealed that the removal rate of petroleum hydrocarbons (C10-C40) in the remediated soil was 70.2%, while the removal rate of polycyclic aromatic hydrocarbons such as naphthalene and pyrene was 45.3%.

[0153] Comparative Example 2

[0154] The method of Example 1 was used to carry out in-situ remediation of petroleum-contaminated soil. The difference was that step (4) electrodynamic treatment was not carried out. Instead, the microbial agent was directly added and stirred for 12 hours.

[0155] Testing revealed that the removal rate of petroleum hydrocarbons (C10-C40) in the remediated soil was 61.2%, while the removal rate of polycyclic aromatic hydrocarbons such as naphthalene and pyrene was 38.6%.

[0156] Comparative Example 3

[0157] The method of Example 1 was used to carry out in-situ remediation of petroleum-contaminated soil. The difference was that the ultrasonic treatment in step (2) and the electrodynamic treatment in step (4) were not carried out. Instead, microbial agents were directly added to the pretreated petroleum-contaminated soil and stirred for 12 hours.

[0158] Testing revealed that the removal rate of petroleum hydrocarbons (C10-C40) in the remediated soil was 49.8%, while the removal rate of polycyclic aromatic hydrocarbons such as naphthalene and pyrene was 21.5%.

[0159] As can be seen from the data in the above embodiments and comparative examples, the method of in-situ and ex-situ remediation of petroleum-contaminated soil using multi-technology coupling according to the present invention can significantly improve the remediation efficiency of petroleum-contaminated soil. Specifically, the removal rate of petroleum hydrocarbon components C10-C40 can reach more than 85%, and the removal rate of polycyclic aromatic hydrocarbons can reach more than 65%.

[0160] 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 method for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach, characterized in that, The method includes the following steps: (1) Collect petroleum-contaminated soil, crush it to obtain petroleum-contaminated soil with a particle size of less than 5 mm; (2) Add glycolipid biosurfactants and auxiliaries to the petroleum-contaminated soil obtained in step (1), and then perform ultrasonic treatment. The glycolipid biosurfactants are selected from one or more of rhamnolipin, trehalose, and sophorolipid, and the auxiliaries are sodium sulfite. (3) First, a first microbial agent is added to the petroleum-contaminated soil obtained after step (2), and then a second microbial agent is added. The first and second microbial agents include a wall material and a core material encased in the wall material. The wall material contains a natural biodegradable material, which is at least one of sodium alginate, agar, and chitosan. The core material contains microorganisms capable of degrading petroleum hydrocarbons and biochar for adsorbing the microorganisms. The microorganisms contained in the core material of the first microbial agent are genus *Cyclomonella*. Cellulomonas sp. The accession number is GDMCC No: 62343, belonging to the genus *Cyclomonella*. Cellulomonas sp. The degradation rate of total petroleum hydrocarbons is over 80%; the microorganisms contained in the core material of the second microbial agent are Pseudomonas. Pseudomonassp. The accession number is GDMCC No: 62341, belonging to the genus *Pseudomonas*. Pseudomonassp. The degradation rate for naphthalene is over 65%, and the degradation rate for pyrene is over 65%. (4) Apply an electric field voltage to the petroleum-contaminated soil obtained in step (3) using an electro-powered treatment device, wherein the electro-powered treatment device includes a DC power supply, a control system and several graphite electrodes inserted into the petroleum-contaminated soil.

2. The method according to claim 1, characterized in that, In step (2), the amount of glycolipid biosurfactant used is 0.1-1 g / kg, and the amount of the adjuvant used is 0.1-1 g / kg.

3. The method according to claim 2, characterized in that, The weight ratio of the glycolipid biosurfactant to the adjuvant is 1:1-5.

4. The method according to any one of claims 1-3, characterized in that, The conditions for ultrasonic treatment include: ultrasonic power of 50-80W, treatment time of 8-15min, temperature of 45-55℃, and number of treatments of 1-3.

5. The method according to claim 1, characterized in that, The dosage of the first microbial agent is 50-200g / kg, and the dosage of the second microbial agent is 50-100g / kg.

6. The method according to claim 1 or 5, characterized in that, The first and second microbial agents are granular, with a bacterial load of Lg (CFU / g) ≥10 and an encapsulation rate ≥90%.

7. The method according to claim 6, characterized in that, The first and second microbial agents are granular, with a bacterial load of 10-12 Lg (CFU / g) and an encapsulation rate of 90-95%.

8. The method according to claim 7, characterized in that, The method further includes preparing microbial inoculants according to the following steps: (1) Microbial inoculum and biochar are stirred, mixed and solidified to obtain microbial inoculum suspension; (2) The natural biodegradable material, nitrogen source and phosphorus source are stirred and mixed in water to obtain a gel solution, and then heat-treated for sterilization to obtain a gel; (3) Prepare a calcium chloride solution and then sterilize it by heat treatment; (4) The microbial suspension obtained in step (1) and the gel obtained in step (2) are injected into the calcium chloride solution obtained in step (3), crosslinked, allowed to stand, filtered, and dried at low temperature to obtain granular microbial agent.

9. The method according to claim 8, characterized in that, The biochar is coconut shell biochar and / or crop biochar.

10. The method according to claim 8, characterized in that, The nitrogen source is at least one of urea, ammonium sulfate, ammonium nitrate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate.

11. The method according to claim 8, characterized in that, The phosphorus source is at least one of dipotassium hydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and sodium tripolyphosphate.

12. The method according to claim 8, characterized in that, In step (1), the amount of biochar used is 0.5-1.5 volumes relative to 100 volumes of the microbial inoculum, the mixing temperature is 30-37°C, and the curing time is 6-24 hours.

13. The method according to claim 8, characterized in that, In step (2), the weight ratio of the natural biodegradable material, the nitrogen source and the phosphorus source is 2-4:10-15:1, and the mixing time is 10-60 min; the heat treatment sterilization temperature is 115-130℃, and the time is 10-20 min.

14. The method according to claim 8, characterized in that, In step (4), the volume ratio of the microbial suspension to the gel is 1:8-12, the weight ratio of calcium chloride in the calcium chloride solution to the natural biodegradable material is 1:0.8-1.2, and the crosslinking time is 3-6h.

15. The method according to claim 1, characterized in that, In step (4), the applied electric field voltage is 80-120V / m, and the power is applied intermittently for 12 hours for 10-30 days.

16. A system for in-situ and ex-situ remediation of petroleum-contaminated soil using a multi-technology coupling approach, characterized in that: The system is used to implement the method according to any one of claims 1-15, the system comprising: A soil collection device for collecting petroleum-contaminated soil; A pretreatment device is used to crush the collected petroleum-contaminated soil to obtain petroleum-contaminated soil with a particle size of less than 5 mm. An ultrasonic treatment device, in which pretreated petroleum-contaminated soil is mixed and contacted with glycolipid biosurfactants and auxiliaries and subjected to ultrasonic treatment; A microbial treatment device in which a soil mixture from an ultrasonic treatment device is mixed and contacted with a microbial agent, wherein the microbial agent comprises a wall material and a core material encapsulated in the wall material, the wall material containing a natural biodegradable material, and the core material containing microorganisms capable of degrading petroleum hydrocarbons and biochar for adsorbing the microorganisms; An electro-dynamic treatment device, comprising a DC power supply, a control system, and several graphite electrodes inserted into petroleum-contaminated soil to which microbial agents have been applied, for electro-dynamic microbial treatment of petroleum-contaminated soil to which microbial agents have been applied; The detection device is used to detect the content of petroleum hydrocarbons and aromatic hydrocarbons in pretreated petroleum-contaminated soil and soil treated with electrodynamic-microbial methods.

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