Plant-microorganism enhanced multiphase extraction organic pollution remediation method

Abstract

The invention discloses a plant-microorganism enhanced multiphase extraction organic pollution remediation method. The method comprises the steps of site evaluation, phytoremediation system construction, microbial remediation system construction, multiphase extraction enhancement, remediation process monitoring and adjustment, pollutant removal and ecological restoration. According to the method, a plant-microorganism enhanced multiphase extraction synergistic effect remediation system is constructed, the problem that the efficiency of a single plant remediation or microorganism remediation technology is low is effectively solved, degradation and removal of organic pollutants are accelerated, efficient treatment of refractory pollutants such as polycyclic aromatic hydrocarbons, polychlorinated biphenyls and organophosphorus pesticides is achieved, and the method has the advantages of being simple in process, low in cost and good in application prospect. In the remediation process, the influence on the ecological environment is small, secondary pollution is not likely to be generated, and the method has both economical efficiency and environmental friendliness and is suitable for treatment of multiphase pollutants in complex contaminated sites including soil, water and solid waste.

Description

Technical Field

[0001] The invention relates to the technical field of environmental restoration, and in particular to a plant-microorganism enhanced multiphase extraction method for restoring organic pollution. Background Art

[0002] With the rapid development of industrialization and urbanization, a large number of organic pollutants discharged by industries such as petrochemicals, pesticides, pharmaceuticals, and plastic manufacturing have become a major threat to the global ecological environment and human health. These organic pollutants include polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticide residues (such as organophosphorus pesticides), etc., which are highly toxic, persistent, and bioaccumulative. They are difficult to degrade naturally in soil and water, posing a long-term threat to the ecosystem and human health. Due to the strong chemical stability of these pollutants, traditional physical and chemical remediation methods face many technical challenges when dealing with complex contaminated sites.

[0003] At present, the remediation technologies for organic pollutants mainly include physical remediation, chemical remediation, biological remediation and other methods.

[0004] Physical remediation technology: Physical remediation includes methods such as excavation, solidification / stabilization and thermal treatment. These technologies usually achieve remediation by separating or immobilizing pollutants from the contaminated medium. For example, thermal desorption technology removes pollutants by vaporizing them by heating contaminated soil. However, these methods have the following disadvantages:

[0005] High cost: Physical remediation technology usually requires a large amount of mechanical equipment and energy input, and is suitable for small-scale, high-concentration pollution sites, but not for large-scale, low-concentration pollution control.

[0006] Severe ecological damage: Soil excavation and heat treatment, for example, will destroy the soil structure and microbial ecosystem, making it difficult for the land to restore its original function after restoration.

[0007] Prone to secondary pollution: Gaseous pollutants or solid waste may be released during the treatment process, requiring additional treatment.

[0008] Chemical remediation technology: Chemical remediation technology uses chemical agents (such as oxidants, reductants, surfactants, etc.) to promote the degradation or removal of pollutants, including chemical oxidation (such as Fenton reagent oxidation), chemical reduction and solidification. For example, surfactants can enhance the desorption of organic pollutants from the solid phase and transfer them to the liquid phase. However, these methods also have the following problems:

[0009] Limited scope of application: Chemical oxidation is less effective in treating low-concentration or diffuse pollutants, and has low degradation efficiency for certain complex organic pollutants (such as PCBs).

[0010] Cost and toxicity issues: The use of chemical reagents is costly, and some reagents such as oxidants and surfactants may introduce new pollutants, increasing the complexity of site remediation.

[0011] Unfriendly to the ecosystem: Chemical remediation often destroys the original ecological functions of the soil and may inhibit the activity of natural microorganisms in the soil.

[0012] Bioremediation technology: Bioremediation technology decomposes organic pollutants by utilizing the metabolic capacity of microorganisms or plants, including microbial remediation, phytoremediation and combined remediation technology. Bioremediation technology has low cost, environmental friendliness and wide application range, and has attracted much attention in recent years. However, single bioremediation technology still has the following shortcomings:

[0013] Limitations of microbial remediation: Many microorganisms have poor tolerance to high concentrations of pollutants, and environmental conditions in contaminated sites (such as soil pH and water content) can significantly affect the activity and colonization of microorganisms. In addition, the degradation efficiency of complex pollutants (such as PCBs and PAHs) by a single microorganism is low.

[0014] Phytoremediation takes a long time: Phytoremediation mainly relies on the plant root system to adsorb, enrich and degrade pollutants. The process is relatively slow, and some plants have limited tolerance to severe pollution, resulting in low remediation efficiency.

[0015] Insufficient synergy: Microbial remediation and phytoremediation fail to fully synergize in many cases. For example, plant exudates (such as root exudates) fail to effectively activate rhizosphere microorganisms, resulting in limited remediation efficiency.

[0016] In summary, traditional physical and chemical remediation methods and single biological remediation methods have the following main problems when dealing with complex organic pollutants:

[0017] (1) Low remediation efficiency. For difficult-to-degrade organic pollutants (such as PAHs and PCBs), the degradation capacity of physical and chemical remediation is limited. They can only remove or fix pollutants, but cannot truly achieve complete degradation of pollutants. Therefore, a single microbial or plant remediation technology is difficult to fully play its role in a complex environment, with low degradation efficiency and a long remediation time.

[0018] (2) The cost of remediation is high. Technologies such as thermal treatment and chemical oxidation require a large amount of external energy or reagents, resulting in high remediation costs. Especially for large-scale low-concentration contaminated sites, the economic cost is not feasible.

[0019] (3) There are risks of ecological damage and secondary pollution. Physical and chemical restoration technologies are often accompanied by damage to the original ecological environment. For example, soil excavation destroys the soil structure, and chemical restoration introduces potentially toxic chemicals, making it difficult to restore the soil ecosystem after restoration.

[0020] (4) Lack of adaptability to complex contaminated sites. If multiple pollutants coexist or the pollutants are closely combined with soil components, existing technologies often find it difficult to achieve efficient remediation. For example, multiphase pollutants (solid, liquid and gaseous pollutants coexist) are difficult to effectively treat with a single remediation method. To this end, we designed a plant-microorganism enhanced multiphase extraction organic pollution remediation method to solve the above problems. Summary of the invention

[0021] The purpose of the present invention is to solve the above technical problems and provide a plant-microorganism enhanced multiphase extraction organic pollution remediation method. The plant-microorganism enhanced multiphase extraction organic pollution remediation method of the present invention should be able to adapt to the remediation of areas where multiphase pollutants are located, and improve the remediation efficiency and remediation results.

[0022] In order to achieve the purpose of the invention, the present invention is implemented by the following technical solutions:

[0023] A plant-microorganism enhanced multiphase extraction organic pollution remediation method comprises the following specific steps:

[0024] Contaminated Site Assessment:

[0025] a. Take soil and water samples from contaminated sites and use gas chromatography-mass spectrometry or high performance liquid chromatography to detect the types and concentrations of pollutants, including but not limited to polycyclic aromatic hydrocarbons, polychlorinated biphenyls and pesticide residues;

[0026] b. Determine the pH value, water content, aeration, temperature and heavy metal content of the soil environment. The determination methods include acid-base titration, heavy metal digestion method and soil density test;

[0027] c. Evaluate the scope of pollution based on the test results, identify high pollution points, divide the pollution areas and formulate zoning remediation targets. Specific targets include reducing the concentration of pollutants to below 50mg / kg;

[0028] Construction of phytoremediation system:

[0029] a. Select plant species that are tolerant to target pollutants based on the nature of the pollutants, including but not limited to willow, water hyacinth and ramie;

[0030] b. When planting, arrange the plants with a spacing of 30 cm between plants and 50 cm between rows, so that the plant coverage rate reaches more than 80%;

[0031] c. Apply appropriate amount of inorganic fertilizer in the planting area. The inorganic fertilizer uses nitrogen, phosphorus and potassium compound fertilizer with a concentration of 0.05-0.1% to provide the nutrients required for plant growth;

[0032] d. During the growth of plants, regularly monitor the root length and aboveground biomass;

[0033] Construction of microbial remediation system:

[0034] a. Screening functional microbial strains matching the target pollutants, including but not limited to Pseudomonas and degrading white rot fungi, the strains are obtained by laboratory culture;

[0035] b. Prepare microbial inoculants, use sodium alginate and calcium chloride to embed and immobilize microorganisms to form microbial beads with a diameter of 1-3 mm;

[0036] c. Apply 50-100g of glue beads per square meter of contaminated soil or water, and evenly distribute them to the root zone of plants through irrigation or spraying;

[0037] d. After the rhizosphere microorganisms are colonized, their metabolic activity is promoted by regularly applying 1% glucose solution or other carbon sources, and the carbon source concentration is controlled below 5 mg / L.

[0038] Multiphase extraction enhancement:

[0039] a. Apply surfactant to the soil in the remediation area at a concentration of 0.05%-0.1% to desorb organic pollutants from the surface of soil particles and transfer them to the liquid phase;

[0040] b. Use aeration devices in water remediation to convert pollutants into the gas phase to improve the migration of volatile organic compounds;

[0041] c. Add modified adsorbents such as modified diatomaceous earth to further improve the desorption efficiency of pollutants in the soil while reducing the risk of secondary migration;

[0042] d. Monitor the release concentration of volatile organic pollutants during the remediation process through portable gas samplers;

[0043] Repair process monitoring and adjustment:

[0044] a. Collect plant and soil samples regularly every 15 days to test the accumulated concentration of pollutants in plants and the residual concentration of pollutants in soil;

[0045] b. Detect the dehydrogenase and peroxidase activities in the soil through enzyme activity analysis (increase ≥ 30%);

[0046] c. Dynamically adjust plant varieties according to monitoring results and add plant growth regulators when necessary to improve plant absorption efficiency;

[0047] d. If the remediation efficiency is lower than the expected target concentration reduction rate ≤ 20%, additional surfactant and carbon source solution dosage may be added;

[0048] Pollutant Removal and Ecological Restoration:

[0049] a. After the restoration is completed, the polluted plants are harvested and their residues are burned in a centralized manner. The ash produced by the burning is stored in a centralized manner to avoid secondary pollution;

[0050] b. Planting local drought-tolerant and barren-tolerant plants such as alfalfa and white clover in the pollution remediation area to promote soil fertility recovery;

[0051] c. Regularly sample and test ecological indicators in the restoration area, including the restoration of the microbial diversity index in the soil to above the Shannon index of 2.5.

[0052] As a preferred technical solution of the present invention, the soil sample collection depth of the contaminated site is 0-20 cm, the sampling density is 1 sample per square meter, and every 5 samples are combined into 1 mixed sample for analysis.

[0053] As a preferred technical solution of the present invention, the planting area of ​​water hyacinth in the phytoremediation step is suitable for water pollution remediation, and the planting density is 25-50 plants per square meter.

[0054] As a preferred technical solution of the present invention, the preparation process of microbial gel beads includes mixing bacterial liquid with 2% sodium alginate solution in a 1:1 ratio, dripping into 0.1M calcium chloride solution using a syringe to form gel beads, and standing at 4°C for 24 hours to solidify.

[0055] As a preferred technical solution of the present invention, the added surfactant is cocoyl betaine, alkyl glucoside or sodium lauroyl glutamate, and the added amount of cocoyl betaine is controlled at 0.05%-0.2% of the mass of the contaminated soil.

[0056] As a preferred technical solution of the present invention, the addition of surfactant is combined with soil stirring, and a rotary tiller is used to stir the soil at a depth of 10-15 cm per square meter to enhance uniformity.

[0057] As a preferred technical solution of the present invention, during the remediation process, the total organic carbon content in the soil is measured in real time by a portable pollution detector, and its reduction rate reaches more than 50%.

[0058] As a preferred technical solution of the present invention, the plant residues after the pollutants are removed are treated by high-temperature incineration (the temperature is controlled at 800-1000° C.), and the ash after incineration is sealed by solid waste landfill.

[0059] As a preferred technical solution of the present invention, when planting alfalfa in the ecological restoration stage, the sowing amount per square meter is 15-20g, combined with microbial agents to promote the improvement of soil fertility.

[0060] As a preferred technical solution of the present invention, the remediation target is to reduce the concentration of polycyclic aromatic hydrocarbons in the soil to below 10 mg / kg, or reduce the concentration of volatile organic pollutants in the water to below 0.5 mg / L.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] 1. The present invention constructs a plant-microorganism synergistic restoration system, utilizes the adsorption, enrichment and metabolic capabilities of plants, and the efficient degradation performance of rhizosphere microorganisms, effectively makes up for the low efficiency of single plant restoration or microbial restoration technology, stimulates microbial activity through plant secretions, and combines multiphase extraction technologies such as surfactants to promote the transfer of pollutants from the solid phase to the liquid phase, accelerates the degradation and removal of organic pollutants, and achieves efficient treatment of difficult-to-degrade pollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organophosphorus pesticides.

[0063] 2. Although plants, microorganisms, and multiphase extraction can all be used alone to repair organically contaminated soil, the combination of the three complements each other, with an effect of 1+1+1 greater than 3. Specifically, plant roots provide assistance for the growth of microorganisms, such as transporting oxygen and nutrients deep into the soil, and microorganisms can decompose organic matter to make it easier for plants to absorb and utilize. Multiphase extraction can guide the direction of groundwater and soil air flow, creating conditions for the growth of plants and microorganisms.

[0064] 3. The present invention has little impact on the ecological environment during the restoration process, is not prone to secondary pollution, and is both economical and environmentally friendly. The present invention is suitable for complex polluted sites, including the treatment of multiphase pollutants in soil, water and solid waste. By dynamically monitoring and regulating plant growth, microbial activity and environmental conditions during the restoration process, the restoration efficiency and applicability are further improved. After restoration, the ecosystem function can be quickly restored to ensure the recovery of soil fertility and biodiversity, and it has broad application prospects and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 The present invention is a schematic flow chart of a plant-microorganism enhanced multiphase extraction method for organic pollution remediation. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] The following is combined with Figure 1 With reference to the accompanying drawings and a number of embodiments, specific embodiments of the present invention are described in detail.

[0068] Embodiment 1:

[0069] This embodiment is used to repair farmland soil contaminated with polycyclic aromatic hydrocarbons;

[0070] 1. Contaminated site assessment

[0071] (1) Surface soil from farmland near an industrial park (sampling depth 0-20 cm) was collected at a sampling density of one point per square meter, and every five samples were combined into one mixed sample;

[0072] (2) The samples were analyzed using gas chromatography-mass spectrometry (GC-MS), and the total concentration of PAHs in the soil was detected to be 350 mg / kg, with phenanthrene, anthracene, and pyrene as the main components;

[0073] (3) Determination of basic soil properties: pH value is 7.3, water content is 25%, and soil aeration is poor;

[0074] (4) Based on the nature and distribution of pollutants, establish remediation targets: PAHs concentration is reduced to below 30 mg / kg.

[0075] 2. Construction of phytoremediation system;

[0076] (1) Choose the pollution-tolerant willow tree, which has strong pollutant absorption capacity and stress resistance;

[0077] (2) Planting is carried out according to the pattern of 30 cm plant spacing and 50 cm row spacing, and the coverage rate reaches more than 80%;

[0078] (3) Apply nitrogen, phosphorus and potassium compound fertilizer after planting (concentration of 0.05%, dosage of 50g / m 2 ), ensuring adequate nutrition for plants;

[0079] (4) During the restoration process, regular irrigation was performed to keep the soil moist, and the growth status of the plants was monitored every 15 days, including root length (2-5 cm per week) and aboveground biomass (≥1.5 kg per square meter).

[0080] 3. Construction of microbial remediation system;

[0081] (1) Screening functional microorganisms Pseudomonas sp., which has significant degradation ability for polycyclic aromatic hydrocarbons;

[0082] (2) Mix the bacterial solution with 2% sodium alginate solution in a 1:1 ratio and drip into 0.1 M calcium chloride solution using a syringe to form microbial gel beads with a diameter of 1-3 mm;

[0083] (3) Apply 50 g of microbial glue beads per square meter and evenly distribute them to the root zone of the willow tree;

[0084] (4) Apply 1% glucose solution (50 mL / m 2 ) as a carbon source and irrigate once every two weeks to enhance microbial activity.

[0085] 4. Enhanced multiphase extraction;

[0086] (1) Add surfactant alkyl glycoside to the remediation area at a concentration of 0.1% (based on soil mass) and stir with a rotary tiller to release pollutants from the soil solid phase to the liquid phase;

[0087] (2) Adding modified diatomaceous earth (5% by mass of soil) to the soil to further absorb the released pollutants and prevent secondary diffusion;

[0088] (3) The soil mixing depth is controlled at 10-15 cm to ensure uniform distribution of the surfactant.

[0089] 5.Monitor and adjust the repair process;

[0090] (1) Soil samples were collected every 15 days to test the residual concentration of PAHs, and the dehydrogenase activity and peroxidase activity in the soil were tested by enzyme activity analysis (the enzyme activity increased by more than 40% after 30 days of remediation);

[0091] (2) Regularly observe plant growth status, record aboveground biomass and root length, and adjust fertilizer concentration or supplement trace elements if plant growth stagnates;

[0092] (3) If the pollutant degradation effect does not meet expectations, increase the dosage of surfactant and carbon source (increase by 10%).

[0093] 6. Pollutant removal and ecological restoration;

[0094] (1) After 120 days of remediation, the PAHs concentration in the soil was reduced to 15 mg / kg, and the remediation goal was achieved;

[0095] (2) Harvest willow trees, transport plant residues to incineration equipment for incineration (incineration temperature 900°C), and safely seal the ash produced by incineration;

[0096] (3) Sow alfalfa in the repaired soil at a rate of 20 g per square meter to improve soil fertility and microbial diversity.

[0097] Repair effect data

[0098]

[0099] Embodiment 2:

[0100] This embodiment is used to remediate soil in industrial sites contaminated with polychlorinated biphenyls (PCBs);

[0101] 1. Assessment of contaminated sites;

[0102] (1) The surface soil of a chemical plant site (sampling depth 0-20 cm) was collected and analyzed by GC-MS. The results showed that the total concentration of polychlorinated biphenyls (PCBs) in the soil was 150 mg / kg, and the main components were trichlorobiphenyl and pentachlorobiphenyl;

[0103] (2) Determination of soil properties: pH value is 6.8, water content is 20%, and soil aeration is moderate;

[0104] (3) Establish remediation goals: Reduce PCBs concentration to below 10 mg / kg.

[0105] 2. Construction of phytoremediation system;

[0106] (1) Selecting Eichhornia crassipes as the restoration plant is suitable for the wetland area of ​​the site;

[0107] (2) The planting density was 30 plants per square meter, and 0.1% potassium dihydrogen phosphate solution (concentration 50 mL / m2) was added every two weeks. 2 ) to promote plant growth;

[0108] (3) During the restoration process, plant growth was recorded every 20 days, including leaf area (≥0.15 m per plant). 2 ) and wetland coverage (reaching more than 85%).

[0109] 3. Construction of microbial remediation system;

[0110] (1) White rot fungi were selected as functional microorganisms, and the culture solution concentration reached 10^8 CFU / mL;

[0111] (2) Mix the bacterial solution with 2% sodium alginate solution to prepare beads with a diameter of about 3 mm, and apply 100 g per square meter to the contaminated area;

[0112] (3) Apply 0.5% glucose solution through drip irrigation once every two weeks to activate microbial metabolism.

[0113] 4. Enhanced multiphase extraction;

[0114] (1) Adding the surfactant cocoyl betaine to the soil at a concentration of 0.1% (based on soil mass) to enhance the release of PCBs from soil particles;

[0115] (2) Combined with aeration device (aeration power 15W / m 2 ), promoting the transfer of volatile PCBs to the gas phase;

[0116] (3) Through mechanical tillage, the surfactant was evenly mixed to a soil depth of 10 cm.

[0117] 5.Monitor and adjust the repair process;

[0118] (1) Collect soil samples every 20 days to test PCBs concentration and degradation efficiency;

[0119] (2) Regularly monitor plant growth and microbial activity. If the microbial degradation activity decreases, increase the amount of glucose carbon source by 10%-20%.

[0120] 6. Pollutant removal and ecological restoration;

[0121] (1) After 90 days of remediation, the PCBs concentration in the soil dropped to 8 mg / kg, achieving the remediation goal;

[0122] (2) Harvesting water hyacinths and burning them in a centralized manner;

[0123] (3) Plant white clover in the restored site, sowing 15g per square meter to promote soil ecological recovery.

[0124] Repair effect data

[0125]

[0126] Embodiment 3:

[0127] This embodiment is used to repair organophosphorus pesticide pollution in farmland;

[0128] 1. Assessment of contaminated sites;

[0129] (1) Collect the surface soil of an agricultural planting area (sampling depth 0-20 cm) at a sampling density of one point per square meter, and combine every 5 samples into one mixed sample;

[0130] (2) The soil samples were tested using high performance liquid chromatography (HPLC), and the results showed that the total concentration of organophosphorus pesticides was 100 mg / kg, with parathion and methyl parathion as the main components;

[0131] (3) Determination of basic soil parameters: pH value is 6.5, water content is 22%, and soil structure is loose;

[0132] (4) Restoration goal: Reduce the concentration of organophosphorus pesticides to below 5 mg / kg.

[0133] 2. Construction of phytoremediation system;

[0134] (1) Select reed as the restoration plant, as reed has a strong ability to absorb and metabolize organophosphorus pesticides;

[0135] (2) Planting with a spacing of 40 cm between plants and 60 cm between rows to ensure that the plant coverage rate reaches more than 80%;

[0136] (3) Apply nitrogen, phosphorus and potassium compound fertilizer (concentration of 0.05%, application amount of 30g / m 2 ), promoting rapid growth of plants;

[0137] (4) During the restoration process, plant growth status was monitored regularly, and aboveground biomass (≥1.5 kg per square meter) and root growth were recorded every two weeks.

[0138] 3. Construction of microbial remediation system;

[0139] (1) Screening Bacillus subtilis as the functional microorganism, which can efficiently degrade organophosphorus pesticides;

[0140] (2) adjusting the bacterial solution concentration to 10^8 CFU / mL and mixing it with 2% sodium alginate solution in a 1:1 ratio to prepare beads with a diameter of 1-2 mm;

[0141] (3) Apply 75 g of glue beads per square meter, spread the beads evenly on the root zone of the plants, and apply 0.5% sodium carbonate solution (concentration 50 mL / m) by irrigation. 2 ) to activate microbial metabolic activity;

[0142] (4) During the restoration process, rhizosphere soil samples were collected every two weeks to detect changes in microbial activity (using dehydrogenase activity as an indicator).

[0143] 4. Enhanced multiphase extraction;

[0144] (1) Add 0.1% of the surfactant sodium lauroyl glutamate (based on soil mass) to the soil to desorb the organophosphorus pesticide from the soil solid phase and transfer it to the liquid phase;

[0145] (2) Mechanically till the soil (depth 15 cm) to ensure that the surfactant is fully mixed with the soil;

[0146] (3) Add 5% activated carbon (based on soil mass) to the restoration area as an adsorbent to further reduce the risk of migration of free organic phosphorus.

[0147] 5.Monitor and adjust the repair process;

[0148] (1) Collect soil samples every 15 days to detect changes in pesticide residue concentrations and evaluate remediation efficiency;

[0149] (2) Through soil enzyme activity detection, observe the changes in dehydrogenase activity and peroxidase activity (dehydrogenase activity increased by more than 30%);

[0150] (3) If the repair progress is slow, adjust the amount of surfactant (increase 10%-20%) or the concentration of microbial agents applied.

[0151] 6. Pollutant removal and ecological restoration;

[0152] (1) After the remediation was completed, the pesticide residue concentration in the soil was reduced to 4 mg / kg, achieving the remediation goal;

[0153] (2) Burn the harvested reeds (burning temperature 850°C) and centrally treat the ash produced by the burning;

[0154] (3) sowing white clover in the restoration area at a rate of 15 g per square meter to improve soil fertility and microbial community diversity;

[0155] (4) The soil ecological restoration effect was tested. The results showed that the microbial diversity index (Shannon index) increased to 2.8 and the soil fertility was well restored.

[0156] Repair effect data

[0157]

[0158]

[0159] Through Examples 1, 2 and 3, the specific application of the technology of the present invention in different pollution types (soil pollution types are polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organophosphorus pesticides) is fully demonstrated, and the wide applicability, significant restoration effect and good ecological restoration ability of the plant-microorganism enhanced multiphase extraction and remediation technology are verified. These examples fully reflect the specificity and effectiveness of the technical solution.

[0160] The present invention uses plants, microorganisms, and multiphase extraction in combination to repair organically contaminated soil. The combination of the three complements each other and achieves twice the result with half the effort. Plant roots provide assistance for the growth of microorganisms, such as transporting oxygen and nutrients deep into the soil. Microorganisms can decompose organic matter to make it easier for plants to absorb and utilize it. Multiphase extraction can guide the direction of groundwater and soil gas flow, creating more favorable conditions for the growth of plants and microorganisms.

[0161] The present invention constructs a plant-microorganism synergistic restoration system, utilizes the adsorption, enrichment and metabolic capabilities of plants, and the efficient degradation performance of rhizosphere microorganisms, effectively makes up for the low efficiency of single plant restoration or microbial restoration technology, stimulates microbial activity through plant secretions, and combines multiphase extraction technologies such as surfactants to promote the transfer of pollutants from the solid phase to the liquid phase for enhanced effectiveness, thereby further accelerating the degradation and removal of organic pollutants, and achieving efficient treatment of difficult-to-degrade pollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organophosphorus pesticides.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Plant-microorganism enhanced multiphase extraction organic pollution remediation method, characterized in that: The specific steps include: Contaminated Site Assessment: a. Take soil and water samples from contaminated sites and use gas chromatography-mass spectrometry or high performance liquid chromatography to detect the types and concentrations of pollutants, including but not limited to polycyclic aromatic hydrocarbons, polychlorinated biphenyls and pesticide residues; b. Determine the pH value, water content, aeration, temperature and heavy metal content of the soil environment. The determination methods include acid-base titration, heavy metal digestion method and soil density test; c. Evaluate the scope of pollution based on the test results, identify high pollution points, divide the pollution areas and formulate zoning remediation targets. Specific targets include reducing the concentration of pollutants to below 50mg / kg; Construction of phytoremediation system: a. Select plant species that are tolerant to target pollutants based on the nature of the pollutants, including but not limited to willow, water hyacinth and ramie; b. When planting, arrange the plants with a spacing of 30 cm between plants and 50 cm between rows, so that the plant coverage rate reaches more than 80%; c. Apply appropriate amount of inorganic fertilizer in the planting area. The inorganic fertilizer uses nitrogen, phosphorus and potassium compound fertilizer with a concentration of 0.05-0.1% to provide the nutrients required for plant growth; d. During the growth of plants, regularly monitor the root length and aboveground biomass; Construction of microbial remediation system: a. Screening functional microbial strains matching the target pollutants, including but not limited to Pseudomonas and degrading white rot fungi, the strains are obtained by laboratory culture; b. Prepare microbial inoculants, use sodium alginate and calcium chloride to embed and immobilize microorganisms to form microbial beads with a diameter of 1-3 mm; c. Apply 50-100g of glue beads per square meter of contaminated soil or water, and evenly distribute them to the root zone of plants through irrigation or spraying; d. After the rhizosphere microorganisms are colonized, their metabolic activity is promoted by regularly applying 1% glucose solution or other carbon sources, and the carbon source concentration is controlled below 5 mg / L. Multiphase extraction enhancement: a. Apply surfactant to the soil in the remediation area at a concentration of 0.05%-0.1% to desorb organic pollutants from the surface of soil particles and transfer them to the liquid phase; b. Use aeration devices in water remediation to convert pollutants into the gas phase to improve the migration of volatile organic compounds; c. Add modified adsorbents such as modified diatomaceous earth to further improve the desorption efficiency of pollutants in the soil while reducing the risk of secondary migration; d. Monitor the release concentration of volatile organic pollutants during the remediation process through portable gas samplers; Repair process monitoring and adjustment: a. Collect plant and soil samples regularly every 15 days to test the accumulated concentration of pollutants in plants and the residual concentration of pollutants in soil; b. Detect the dehydrogenase and peroxidase activities in the soil through enzyme activity analysis; c. Dynamically adjust plant varieties according to monitoring results and add plant growth regulators when necessary to improve plant absorption efficiency; d. If the remediation efficiency is lower than the expected target concentration reduction rate ≤ 20%, additional surfactant and carbon source solution dosage may be added; Pollutant Removal and Ecological Restoration: a. After the restoration is completed, the polluted plants are harvested and their residues are burned in a centralized manner. The ash produced by the burning is stored in a centralized manner to avoid secondary pollution; b. Planting local drought-tolerant and barren-tolerant plants such as alfalfa and white clover in the pollution remediation area to promote soil fertility recovery; c. Regularly sample and test ecological indicators in the restoration area, including the restoration of the microbial diversity index in the soil to above the Shannon index of 2.

5.

2. The plant-microorganism enhanced multiphase extraction organic pollution remediation method according to claim 1 is characterized in that: The soil samples from the contaminated site were collected at a depth of 0-20 cm, with a sampling density of 1 sample per square meter, and every 5 samples were combined into 1 mixed sample for analysis.

3. The plant-microorganism enhanced multiphase extraction organic pollution remediation method according to claim 1 is characterized in that: The planting area of ​​water hyacinth in the phytoremediation step is suitable for water pollution remediation, and the planting density is 25-50 plants per square meter.

4. The plant-microorganism enhanced multiphase extraction organic pollution remediation method according to claim 1 is characterized in that: The preparation process of microbial gel beads includes mixing the bacterial liquid with 2% sodium alginate solution in a 1:1 ratio, dripping it into 0.1M calcium chloride solution using a syringe to form gel beads, and standing at 4°C for 24 hours to solidify.

5. The plant-microorganism enhanced multiphase extraction organic pollution remediation method according to claim 1, characterized in that: The added surfactant is cocoyl betaine, alkyl glucoside or sodium lauroyl glutamate, and the added amount of cocoyl betaine is controlled at 0.05%-0.2% of the mass of the polluted soil.

6. The plant-microorganism enhanced multiphase extraction organic pollution remediation method according to claim 5 is characterized in that: The surfactant addition is combined with soil mixing, using a rotary tiller to a mixing depth of 10-15 cm per square meter to enhance uniformity.

7. The plant-microorganism enhanced multiphase extraction organic pollution remediation method according to claim 1 is characterized in that: During the remediation process, the total organic carbon content in the soil was measured in real time using a portable pollution detector and was reduced by more than 50%.

8. The plant-microorganism enhanced multiphase extraction organic pollution remediation method according to claim 1 is characterized in that: The plant residues after pollutants are removed are incinerated at high temperature with the temperature controlled at 800-1000℃. The ash after incineration is sealed through solid waste landfill.

9. The plant-microorganism enhanced multiphase extraction organic pollution remediation method according to claim 1, characterized in that: During the ecological restoration stage, the sowing rate for alfalfa is 15-20g per square meter, combined with microbial agents to promote soil fertility.

10. The plant-microorganism enhanced multiphase extraction organic pollution remediation method according to claim 1, characterized in that: The remediation goal is to reduce the concentration of PAHs in the soil to below 10 mg / kg, or the concentration of volatile organic pollutants in the water to below 0.5 mg / L.

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