A method for repairing perfluoro and polyfluoro alkyl substance composite organic pollution in soil and underground water by coupling microorganisms with nanomaterials

Abstract

The present application belongs to the technical field of soil and groundwater pollution remediation, and particularly relates to a method for remediation of perfluoro and polyfluoro alkyl substance (PFASs) composite organic pollutants in soil and groundwater by microbial coupling with nanomaterials. The method provided by the present application promotes the growth of indigenous microorganisms by adding nutrient salts into the pollution system, so as to realize biodegradation of composite organic pollutants in soil and groundwater. The method provided by the present application also adds nanomaterials, i.e. layered double hydroxides (LDHs), into the pollution system to adsorb the composite organic pollutants, so as to improve the remediation effect by coupling with microorganisms. The method provided by the present application not only utilizes the high-efficiency degradation of microorganisms on composite organic pollutants, especially hydrocarbon substances, but also adds nanomaterials, i.e. LDHs, for adsorption, so as to effectively remediate PFASs composite organic pollutants in soil and groundwater by means of microbial coupling with nanomaterials.

Description

Technical Field

[0001] This invention belongs to the field of soil and groundwater pollution remediation technology, specifically relating to a method for remediating complex organic pollution of perfluorinated and polyfluoroalkyl substances in soil and groundwater using microbial coupled nanomaterials. Background Technology

[0002] Per- and polyfluoroalkyl substances (PFASs) are a class of synthetic organic compounds containing at least one perfluorinated carbon atom (i.e., at least one -CF2- or -CF3 aliphatic chain structural unit). They are persistent, bioaccumulative, and toxic. Petroleum hydrocarbons and benzene compounds are common naturally occurring hydrocarbons widely used as fuels, solvents, lubricants, and chemicals; excessive release into the environment has adverse effects on soil and groundwater. Due to their superior properties, PFASs can be used as surfactants in petrochemical and other industrial processes. Therefore, in soil and groundwater at similar industrial sites, there may be complex pollution from PFASs combined with petroleum hydrocarbons and benzene compounds. Currently, there is limited research on methods for removing such complex organic pollution from soil and groundwater.

[0003] Therefore, it is crucial to develop effective methods to remove complex organic pollution from PFASs, petroleum hydrocarbons, and benzene compounds to ensure environmental safety and human health. Summary of the Invention

[0004] The purpose of this invention is to provide a method for remediating complex organic pollution of perfluorinated and polyfluoroalkyl substances in soil and groundwater using microbial coupled nanomaterials. The method provided by this invention can simultaneously remediate PFASs, petroleum hydrocarbons and benzene series compounds in polluted soil and groundwater, and has the advantages of being safe, efficient, economical, simple and easy to implement and environmentally friendly.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for remediating complex organic pollutants in soil and groundwater using microbial-coupled nanomaterials, comprising the following steps:

[0007] Nutrients and layered bimetallic hydroxides are added to contaminated soil and groundwater systems. After adding nutrients, air is intermittently introduced into the contaminated soil and groundwater systems. Indigenous microorganisms and layered bimetallic hydroxides are used to remediate the complex organic pollutants in the contaminated soil and groundwater systems. The complex organic pollutants include perfluorinated and polyfluoroalkyl substances, petroleum hydrocarbons, and benzene compounds.

[0008] Preferably, the perfluorinated and polyfluoroalkyl substances include perfluorooctane sulfonic acid (PFOS) and trifluorobutyric acid (TFBA); the benzene series includes benzene and ethylbenzene.

[0009] Preferably, in the contaminated soil and groundwater system, the ratio of the mass of contaminated soil to the volume of contaminated groundwater is 30g:160mL.

[0010] Preferably, the content of perfluorinated and polyfluoroalkyl substances in the contaminated soil and groundwater system is calculated based on the content of perfluorinated and polyfluoroalkyl substances in the contaminated groundwater, and the content of perfluorinated and polyfluoroalkyl substances is 20 ppm.

[0011] The content of petroleum hydrocarbons in the contaminated soil and groundwater system is calculated based on the content of petroleum hydrocarbons in the contaminated groundwater, and the content of petroleum hydrocarbons is 1612.5 ppm;

[0012] The content of benzene compounds in the contaminated soil and groundwater system is calculated based on the content of benzene compounds in the contaminated groundwater, and the content of the benzene compounds is 200 ppm.

[0013] Preferably, the nutrient salts include Na2HPO4·12H2O, NH4Cl, KH2PO4, NaCl, MgSO4, and trace elements; the trace elements include one or more of NiCl2·6H2O, MnCl2·2H2O, H3BO3, CoCl2·6H2O, ZnCl2, CuCl2·2H2O, MnCl4·H2O, and Na2Mo4·2H2O.

[0014] Preferably, the dosage of each component in the nutrient salt is based on the content of each component in the polluted groundwater, with the following concentrations: Na₂HPO₄·12H₂O: 15–20 g / L; NH₄Cl: 0.8–1.2 g / L; KH₂PO₄: 2.5–3.5 g / L; NaCl: 0.5 g / L; MgSO₄: 0.8–1.2 mmol / L; NiCl₂·6H₂O: 0.05 mg / L. The mass concentrations of MnCl2·2H2O, H3BO3, CoCl2·6H2O, ZnCl2, CuCl2·2H2O, MnCl4·H2O, and Na2Mo4·2H2O were 0.0573 mg / L, 0.0775 mg / L, 0.125 mg / L, 0.525 mg / L, 0.075 mg / L, and 0.075 mg / L, respectively.

[0015] Preferably, the layered bimetallic hydroxide is a nitrate-magnesium-aluminum type layered bimetallic hydroxide.

[0016] Preferably, the ratio of the mass of the layered bimetallic hydroxide added to the volume of polluted groundwater in the polluted soil and groundwater system is 10 mg: 160 mL.

[0017] Preferably, the method of adding the nutrient salt and the layered bimetallic hydroxide includes method one or method two; method one is to add the nutrient salt and the layered bimetallic hydroxide together; method two is to add the nutrient salt first, and then add the layered bimetallic hydroxide, wherein the interval between adding the nutrient salt and the layered bimetallic hydroxide is ≤42 days.

[0018] Preferably, the interval between air introductions is 24 hours; the ratio of the volume of air introduced each time to the mass of contaminated soil in the contaminated soil and groundwater system is (50-100) mL:30g.

[0019] This invention provides a method for remediating complex organic pollutants in soil and groundwater using microbial-coupled nanomaterials, comprising the following steps: adding nutrients and layered bimetallic hydroxides to the contaminated soil and groundwater system; intermittently introducing air into the contaminated soil and groundwater system after adding nutrients; and using indigenous microorganisms and layered bimetallic hydroxides to remediate the complex organic pollutants in the contaminated soil and groundwater system; wherein the complex organic pollutants include perfluorinated and polyfluoroalkyl substances, petroleum hydrocarbons, and benzene compounds. The method provided by this invention utilizes nutrients to promote the growth of indigenous microorganisms in contaminated soil and groundwater systems. Indigenous microorganisms have a stronger adaptability compared to exogenous bacteria. Simultaneously, intermittent air introduction provides oxygen to the indigenous microorganisms, enabling effective degradation of petroleum hydrocarbons and benzene compounds in the contaminated soil and groundwater systems. Furthermore, this invention utilizes the layered structure of a layered bimetallic hydroxide, consisting of cation and anion layers, to achieve efficient removal of PFASs through electrostatic adsorption and anion exchange. Therefore, the method provided by this invention, employing the coupling of microorganisms and layered bimetallic hydroxides, can simultaneously remediate PFASs, petroleum hydrocarbons, and benzene compounds in contaminated soil and groundwater, and has the advantages of safety, high efficiency, economy, simplicity, and environmental friendliness. The results of the examples show that the microbial-coupled nanomaterials provided by this invention achieve removal rates of 96.4% and 82.65% for PFOS and 82.65% for TFBA in contaminated soil and groundwater, respectively; a degradation rate of 63.3% for petroleum hydrocarbons; and degradation rates of 38.1% and 27.3% for benzene and ethylbenzene, respectively. Attached Figure Description

[0020] Figure 1 The variations of PFOS in the embodiments and comparative examples of this invention are shown below;

[0021] Figure 2 The variations of TFBA in the embodiments and comparative examples of this invention are shown below;

[0022] Figure 3 This describes the changes in petroleum hydrocarbons in the embodiments and comparative examples of the present invention;

[0023] Figure 4 The variations of benzene in the embodiments and comparative examples of this invention are shown below;

[0024] Figure 5 The variations of ethylbenzene in the embodiments and comparative examples of this invention are shown. Detailed Implementation

[0025] This invention provides a method for remediating complex organic pollutants in soil and groundwater using microbial-coupled nanomaterials, comprising the following steps:

[0026] Nutrients and layered bimetallic hydroxides are added to contaminated soil and groundwater systems. After adding nutrients, air is intermittently introduced into the contaminated soil and groundwater systems. Indigenous microorganisms and layered bimetallic hydroxides are used to remediate the complex organic pollutants in the contaminated soil and groundwater systems. The complex organic pollutants include perfluorinated and polyfluoroalkyl substances, petroleum hydrocarbons, and benzene compounds.

[0027] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0028] In this invention, the contaminated soil and groundwater system is a contaminated soil and groundwater system containing complex organic pollutants; the complex organic pollutants include perfluorinated and polyfluoroalkyl substances, petroleum hydrocarbons and benzene compounds.

[0029] In this invention, the preferred ratio of the mass of contaminated soil to the volume of contaminated groundwater in the contaminated soil and groundwater system is 30g:160mL.

[0030] In this invention, the perfluorinated and polyfluoroalkyl substances (PFASs) preferably include perfluorooctane sulfonic acid (PFOS) and trifluorobutyric acid (TFBA); the mass ratio of perfluorooctane sulfonic acid (PFOS) to trifluorobutyric acid (TFBA) is preferably 1:1.

[0031] In this invention, the benzene series preferably includes benzene and ethylbenzene. The mass ratio of benzene to ethylbenzene is preferably 1:1.

[0032] In this invention, the content of perfluorinated and polyfluoroalkyl substances (PFAS) in the contaminated soil and groundwater system is calculated based on the content of PFAS in the contaminated groundwater, and the content of PFAS is preferably 20 ppm. That is, assuming that all PFAS in the contaminated soil and groundwater system are concentrated in the groundwater, the content of PFAS in the contaminated groundwater is preferably 20 ppm. Specifically, the content of perfluorooctane sulfonic acid (PFOS) in the contaminated groundwater is preferably 10 ppm; and the content of trifluorobutyric acid (TFBA) in the contaminated groundwater is preferably 10 ppm.

[0033] In this invention, the content of petroleum hydrocarbons in the contaminated soil and groundwater system is calculated as the content of petroleum hydrocarbons in the contaminated groundwater, and the preferred content of petroleum hydrocarbons is 1612.5 ppm. That is, assuming that all the petroleum hydrocarbons in the contaminated soil and groundwater system are concentrated in the soil of the contaminated soil and groundwater system, the preferred content of petroleum hydrocarbons in the contaminated groundwater is 1612.5 ppm.

[0034] In this invention, the content of benzene compounds in the contaminated soil and groundwater system is calculated based on the content of benzene compounds in the contaminated groundwater, and the content of the benzene compounds is preferably 200 ppm. That is, assuming that all the benzene compounds in the contaminated soil and groundwater system are concentrated in the groundwater of the contaminated soil and groundwater system, the content of benzene compounds in the contaminated groundwater is preferably 200 ppm. Specifically, the content of benzene in the contaminated groundwater is preferably 100 ppm; the content of ethylbenzene in the contaminated groundwater is preferably 100 ppm.

[0035] In this invention, the nutrient salt preferably includes Na₂HPO₄·12H₂O, NH₄Cl, KH₂PO₄, NaCl, MgSO₄, and trace elements; the trace elements preferably include one or more of NiCl₂·6H₂O, MnCl₂·2H₂O, H₃BO₃, CoCl₂·6H₂O, ZnCl₂, CuCl₂·2H₂O, MnCl₄·H₂O, and Na₂Mo₄·2H₂O, more preferably NiCl₂·6H₂O, MnCl₂·2H₂O, H₃BO₃, CoCl₂·6H₂O, ZnCl₂, CuCl₂·2H₂O, MnCl₄·H₂O, and Na₂Mo₄·2H₂O. In this invention, the nutrient salt preferably also includes an oxygen indicator; the oxygen indicator is preferably resazurite.

[0036] In this invention, the nutrient salt is preferably a sterile nutrient salt.

[0037] In this invention, the nutrient salt is preferably sterilized before being added.

[0038] In this invention, the dosage of each component in the nutrient salt is based on the content of each component in the polluted groundwater. The preferred mass concentrations are: Na₂HPO₄·12H₂O 15–20 g / L; NH₄Cl 0.8–1.2 g / L; KH₂PO₄ 2.5–3.5 g / L; NaCl 0.5 g / L; MgSO₄ 0.8–1.2 mmol / L; and NiCl₂·6H₂O 0.05 mg / L. The preferred mass concentrations of MnCl2·2H2O are 0.0573 mg / L; H3BO3 is 0.0775 mg / L; CoCl2·6H2O is 0.09 mg / L; ZnCl2 is 0.125 mg / L; CuCl2·2H2O is 0.525 mg / L; MnCl4·H2O is 0.075 mg / L; and Na2Mo4·2H2O is 0.075 mg / L.

[0039] In this invention, the layered bimetallic hydroxide is preferably a nitrate-magnesium-aluminum type layered bimetallic hydroxide.

[0040] In this invention, the preferred ratio of the mass of the layered bimetallic hydroxide added to the volume of polluted groundwater in the polluted soil and groundwater system is 10 mg: 160 mL.

[0041] In this invention, the particle size of the layered bimetallic hydroxide is preferably ≤74μm.

[0042] In this invention, the nitrate-magnesium-aluminum type layered bimetallic hydroxide is preferably prepared by a supersaturated coprecipitation method.

[0043] In a specific embodiment of the present invention, the method for preparing the nitrate-magnesium-aluminum type layered bimetallic hydroxide preferably includes the following steps:

[0044] Magnesium nitrate hexahydrate and aluminum nitrate nonahydrate were dissolved in water to obtain a nitrate solution; the nitrate solution contained Mg 2+ And Al 3+ The molar ratio is 3:1;

[0045] The nitrate solution was added dropwise to ammonia water to carry out a coprecipitation reaction, resulting in a coprecipitation reaction solution.

[0046] The coprecipitation reaction solution was allowed to stand and age, and after solid-liquid separation, the nitrate-magnesium-aluminum type layered bimetallic hydroxide was obtained.

[0047] This invention dissolves magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in water to obtain a nitrate solution; the nitrate solution contains Mg 2+ And Al 3+ The molar ratio is 3:1. In this invention, the water is preferably ultrapure water; the nitrate solution contains Mg 2+ The molar concentration is 1.2M, Al 3+ The molar concentration is 0.4 M.

[0048] After obtaining the nitrate solution, the present invention adds the nitrate solution dropwise to ammonia water to carry out a coprecipitation reaction, obtaining a coprecipitation reaction solution. In the present invention, the molar concentration of the ammonia water is preferably 6M; the dropwise flow rate is preferably 10 drops / min; the dropwise addition is carried out under stirring conditions; during the dropwise addition, the pH of the reaction system is maintained above 10. After 1 hour of dropwise addition, a white suspension reaction solution is obtained, which is the coprecipitation reaction solution.

[0049] After obtaining the coprecipitation reaction solution, the present invention allows the coprecipitation reaction solution to stand for aging, and after solid-liquid separation, obtains the nitrate-magnesium-aluminum type layered bimetallic hydroxide. In the present invention, the standing aging temperature is preferably room temperature, and the time is preferably 24 hours. In the present invention, the solid-liquid separation is preferably centrifugation, the centrifugation speed is preferably 8000 rpm / min, and the centrifugation time is preferably 30 minutes. After removing the bottom precipitate obtained from the solid-liquid separation, the present invention preferably washes it repeatedly with ultrapure water and then dehydrates it in a vacuum freeze dryer for three days to obtain the nitrate-magnesium-aluminum type layered bimetallic hydroxide.

[0050] In this invention, the nitrate-magnesium-aluminum type layered bimetallic hydroxide prepared above is preferably ground and passed through a 200-mesh sieve, and then stored in a sealed bag for later use.

[0051] In this invention, the addition of the nutrient salt and the layered bimetallic hydroxide preferably includes method one or method two; method one is preferably: adding the nutrient salt and the layered bimetallic hydroxide together. Method two is preferably: adding the nutrient salt first, and then adding the layered bimetallic hydroxide, wherein the interval between the addition of the nutrient salt and the layered bimetallic hydroxide is preferably ≤42 days, more preferably 42 days.

[0052] In this invention, the interval between air introductions is preferably 24 hours; the ratio of the volume of air introduced each time to the mass of contaminated soil in the contaminated soil and groundwater system is preferably (50-100) mL:30g.

[0053] This invention provides a method for remediating complex organic pollution of per- and polyfluoroalkyl substances (PFASs) in soil and groundwater using microorganisms coupled with nanomaterials. The method promotes the growth of indigenous microorganisms by adding nutrients to the pollution system, thereby achieving the biodegradation of complex organic pollutants in soil and groundwater. Furthermore, it enhances the remediation effect by adding layered double hydroxides (LDHs) nanomaterials to the pollution system to adsorb the complex organic pollutants, thus coupling them with microorganisms. This invention not only utilizes the efficient degradation of complex organic pollutants, especially hydrocarbons, by microorganisms, but also incorporates LDHs nanomaterials for adsorption, effectively remediating PFASs complex organic pollutants in soil and groundwater through microbial coupling with nanomaterials.

[0054] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0055] (1) The microbial and LDHs coupling method selected in this invention can efficiently degrade PFASs complex organic pollution, overcome the drawbacks of microbial remediation of PFASs, and enhance the remediation efficiency and effect.

[0056] (2) The microbial and LDHs coupling method selected in this invention are both green and economical methods that will not cause secondary pollution to the environment.

[0057] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0058] Example 1

[0059] Mg was prepared by supersaturated coprecipitation method 2+ -Al 3+ -NO 3- To treat LDHs, the steps are as follows: Weigh 15.36g of magnesium nitrate hexahydrate and 7.5g of aluminum nitrate nonahydrate and dissolve them in 50mL of ultrapure water. At this point, Mg... 2+ And Al 3+ The concentrations were 1.2M and 0.4M, with a molar ratio of 3:1. 25 mL of 30% ammonia solution was taken and diluted to 50 mL to obtain a 6M ammonia solution. Under continuous stirring, the nitrate solution was added dropwise to the 6M ammonia solution at a flow rate of approximately 10 drops / min, maintaining the pH of the reaction system above 10. After 1 hour, a white suspension was obtained and allowed to age at room temperature for 24 hours. Subsequently, it was centrifuged at 8000 rpm / min for 30 minutes, and the bottom precipitate was removed. After repeated washing with ultrapure water, it was dehydrated in a vacuum freeze dryer for three days. After complete drying, it was ground through a 200-mesh sieve to obtain LDHs, which were stored in a sealed bag for later use.

[0060] First, soil and groundwater contaminated with PFASs, petroleum hydrocarbons, and benzene compounds were artificially prepared. The specific method was as follows: For petroleum hydrocarbon-contaminated soil, 6.5g of petroleum was dissolved in n-hexane and sprayed evenly onto the soil surface while continuously stirring. All the petroleum was added to the soil, and stirring continued for 10–20 minutes to complete the preparation of the petroleum hydrocarbon-contaminated soil. After 24 hours, the soil organic matter or particles reached adsorption equilibrium with the petroleum hydrocarbons, simulating actual petroleum hydrocarbon-contaminated soil. The concentration of petroleum hydrocarbons in the contaminated soil was 8600 mg / kg.

[0061] Subsequently, PFASs-contaminated water was prepared using sterilized nutrient salt solution as a solvent to simulate groundwater pollution. The two PFASs used were PFOS and TFBA, and the concentrations of both PFOS and TFBA in the prepared PFAS-contaminated water were 10 ppm. In the prepared PFASs-contaminated water body, the content of each component in the nutrients was calculated based on 1 L of PFASs-contaminated water body. That is, the nutrients in 1 L of PFASs-contaminated water body are 17.698 g / L Na2HPO4·12H2O, 1 g / L NH4Cl, 3 g / L KH2PO4, 0.5 g / L NaCl, 1 mmol SO4 1 mL, 2.5 mL of trace element aqueous solution, and 1 mg / L resazurin, which were sterilized. Among them, the 2.5 mL trace element aqueous solution contains 20 mg / L NiCl2·6H2O, 23 mg / L MnCl2·2H2O, 31 mg / L H3BO3, 36 mg / L CoCl2·6H2O, 50 mg / L ZnCl2, 210 mg / L CuCl2·2H2O, 30 mg / L MnCl4·H2O, and 30 mg / L Na2Mo4·2H2O, with pH=7.0.

[0062] Petroleum hydrocarbon-contaminated soil and nutrient-rich PFAS-contaminated water were mixed in a 250mL anaerobic clamp-top flask, containing 30g of soil and 160mL of contaminated water. Benzene and ethylbenzene were added to bring the concentrations of benzene and ethylbenzene in the contaminated water to 100ppm and 1612.5ppm respectively, and the concentration of petroleum hydrocarbons to 1612.5ppm respectively. The flask was immediately capped with a butyl rubber stopper and the aluminum cap was pressed firmly to complete the preparation of the contaminated system. Three replicates were configured for the remediation system.

[0063] The remediation system was placed at 28℃ and 180 rpm / min and shaken for 24 hours, during which time the pollutants reached equilibrium in the soil, water, and gas phases. Samples were taken after standing for 2–5 hours and recorded as day 0 of the remediation system. Sampling details were as follows: 10 mL of aqueous phase was used for petroleum hydrocarbon determination (analytical method reference HJ 894-2017), 2 mL of aqueous phase was used for benzene series compound determination (analytical method reference HJ 639-2012), and 2 mL of aqueous phase was filtered through a 0.22 μm filter membrane for PFASs determination. Samples were taken at 14, 21, 28, 35, and 42 days to measure the changes in the concentration of composite pollutants and characterize the remediation effect. At day 42, 10 mg of the LDHs prepared in this example was added, and samples were taken at 6 hours and 24 hours to measure the concentration of each pollutant. Finally, the remediation was completed at day 60, and the changes in the concentration of each pollutant were measured.

[0064] Comparative Example 1

[0065] This comparative example is basically the same as Example 1, except that the soil was sterilized and no LDHs were added. This was repeated 3 times. All other conditions were the same as in Example 1.

[0066] Comparative Example 2

[0067] This comparative example is basically the same as Example 1, except that: the soil was sterilized, LDHs were added only to it, and PFASs were prepared to contaminate the water body using water as a solvent. This was repeated 3 times. All other conditions were the same as in Example 1.

[0068] Comparative Example 3

[0069] This comparative example is basically the same as Example 1, except that the soil is not sterilized and LDHs are not added to it, and the experiment is repeated 3 times. All other conditions are the same as in Example 1.

[0070] Example 1, Comparative Examples 1-3: Concentrations of PFASs, petroleum hydrocarbons, and benzene compounds were determined at each stage. Figures 1-5 As shown.

[0071] Depend on Figures 1-5 It can be known that:

[0072] In Example 1, after coupled remediation, the concentration of PFOS in soil and groundwater decreased from 2823.06 ppb to 102.6 ppb, achieving a removal rate of 96.3%. TFBA decreased from 8495.5 ppb to 1474.3 ppb, achieving a removal rate of 82.6%. Petroleum hydrocarbons decreased from 1872 mg / L to 535 mg / L, achieving a degradation rate of 71.4%. Benzene and ethylbenzene decreased from 78.73 ppm to 48.75 ppm and from 23.37 ppm to 16.98 ppm, respectively, achieving degradation rates of 38% and 27.3%.

[0073] In Comparative Example 1, in the group with sterilized soil and no LDHs added, the concentration of PFOS in soil and groundwater decreased from 2918.9 ppb to 2704.3 ppb, with a removal rate of 7.3%. TFBA decreased from 8296.4 ppb to 6721.5 ppb, with a removal rate of 18.9%. Petroleum hydrocarbons decreased from 1455 mg / L to 1337 mg / L, with a degradation rate of 8.1%. Benzene and ethylbenzene decreased from 74.43 ppm to 72.79 ppm and 20.44 ppm to 18.85 ppm, respectively, with degradation rates of 2.2% and 7.7%.

[0074] In Comparative Example 2, in the group where LDHs were added to sterilized soil, the concentration of PFOS in soil and groundwater decreased from 2623.5 ppb to 36.01 ppb, achieving a removal rate of 98.6%. TFBA decreased from 7701.1 ppb to 1447.5 ppb, achieving a removal rate of 81.2%. Petroleum hydrocarbons decreased from 1491 mg / L to 1326 mg / L, with a degradation rate of 11.1%. Benzene and ethylbenzene decreased from 81.58 ppm to 75.28 ppm and 18.45 ppm to 18.81 ppm, respectively, with degradation rates of 7.7% and 0%.

[0075] In Comparative Example 3, in the group of unsterilized soil without LDHs, the concentration of PFOS in the soil and groundwater decreased from 2843.9 ppb to 2896.6 ppb, with a removal rate of 0%. TFBA decreased from 7625.3 ppb to 6796.5 ppb, with a removal rate of 10.8%. Petroleum hydrocarbons decreased from 2028 mg / L to 788 mg / L, with a degradation rate of 62.1%. Benzene and ethylbenzene decreased from 72.65 ppm to 42.34 ppm and 22.87 ppm to 15.52 ppm, respectively, with degradation rates of 41.7% and 32.1%.

[0076] In summary, the method for remediating PFASs complex organic pollution in soil and groundwater using microbial coupling nanomaterials provided by this invention achieves good removal effects on PFASs, petroleum hydrocarbons and benzene series compounds in soil and groundwater through a coupled remediation approach. This method can solve the problem of PFASs complex organic pollution in a green and efficient manner.

[0077] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for repairing complex organic pollutants in soil and groundwater by coupling microorganisms with nanomaterials, characterized in that: Includes the following steps: Nutrients and layered bimetallic hydroxides are added to contaminated soil and groundwater systems. The nutrient salts include Na₂HPO₄·12H₂O, NH₄Cl, KH₂PO₄, NaCl, MgSO₄, and trace elements. The trace elements include one or more of NiCl₂·6H₂O, MnCl₂·2H₂O, H₃BO₃, CoCl₂·6H₂O, ZnCl₂, and CuCl₂·2H₂O. The layered bimetallic hydroxides are nitrate-magnesium-aluminum type layered bimetallic hydroxides. After adding the nutrient salts, air is intermittently introduced into the contaminated soil and groundwater systems to utilize indigenous microorganisms and layered bimetallic hydroxides. A bimetallic hydroxide is used to remediate complex organic pollutants in contaminated soil and groundwater systems. The complex organic pollutants include perfluorinated and polyfluoroalkyl substances, petroleum hydrocarbons, and benzene compounds. The perfluorinated and polyfluoroalkyl substances include perfluorooctane sulfonic acid and trifluorobutyric acid; the benzene compounds include benzene and ethylbenzene. The content of perfluorinated and polyfluoroalkyl substances in the contaminated soil and groundwater system is calculated based on the content of perfluorinated and polyfluoroalkyl substances in the contaminated groundwater, and the content of perfluorinated and polyfluoroalkyl substances is 20 ppm. The content of petroleum hydrocarbons in the contaminated soil and groundwater system is calculated based on the content of petroleum hydrocarbons in the contaminated groundwater, and the content of petroleum hydrocarbons is 1612.5 ppm. ppm; the content of benzene series compounds in the polluted soil and groundwater system is calculated based on the content of benzene series compounds in the polluted groundwater, and the content of benzene series compounds is 200 ppm; the dosage of each component in the nutrients is calculated based on the content of each component in the nutrients in the polluted groundwater, with the following mass concentrations: Na2HPO4·12H2O: 15~20 g / L; NH4Cl: 0.8~1.2 g / L; KH2PO4: 2.5~3.5 g / L; NaCl: 0.5 g / L; MgSO4: 0.8~1.2 mmol / L; NiCl2·6H2O: 0.05 mg / L; MnCl2·2H2O: 0.0573 mg / L; H3BO3: 0.0775 mg / L; CoCl2·6H2O: 0.09 mg / L; ZnCl2: 0.125 mg / L. mg / L; the mass concentration of CuCl2·2H2O is 0.525 mg / L; the ratio of the added mass of the layered bimetallic hydroxide to the volume of polluted groundwater in the polluted soil and groundwater system is 10 mg:160 mL; the interval for introducing air is 24 h; the ratio of the volume of air introduced each time to the mass of polluted soil in the polluted soil and groundwater system is (50~100) mL:30 g.

2. The method of claim 1, wherein, In the contaminated soil and groundwater system, the ratio of the mass of contaminated soil to the volume of contaminated groundwater is 30g:160mL.

3. The method according to claim 1, characterized in that, The method of adding the nutrient salt and the layered bimetallic hydroxide includes method one or method two; method one is to add the nutrient salt and the layered bimetallic hydroxide together; method two is to add the nutrient salt first, and then add the layered bimetallic hydroxide, with the interval between adding the nutrient salt and the layered bimetallic hydroxide being ≤42 days.

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