Prevention and treatment method for volatile organic compounds (VOCs) polluted site barrier layer edge flow-around spilling of gaseous pollutants

Abstract

The invention relates to the technical field of blocking-treatment of VOCs (volatile organic compounds) in polluted sites, in particular to a prevention and treatment method for edge flow-around overflow of gaseous pollutants in a blocking layer of a VOCs polluted site. A gas collection area is arranged along the edge of the barrier layer constructed by the HDPE film to enable VOCs flowing around the edge to be collected in the area, a ventilation pipeline is arranged in the area to be used for regulating and controlling oxidation reduction conditions in the area and enhancing the activity of VOCs degrading bacteria, and the ventilation pipeline and surface vegetation form a soil-microorganism-plant coupled degradation system. All interception and in-situ biodegradation of the VOCs flowing around the edge and overflowing are realized. The method has the advantages of being low in cost, easy to construct, environmentally friendly, capable of achieving the landscape function and the like, and is suitable for barrier engineering of the VOCs contaminated site.

Description

Technical Field

[0001] The present invention relates to the technical field of VOCs barrier-control in contaminated sites, and in particular to a method for preventing and controlling the edge circumferential diffusion of gaseous pollutants in a barrier layer in a VOCs contaminated site. Background Art

[0002] For VOC (volatile organic compound) contaminated sites where complete removal of the pollution source is difficult, in-situ risk management is an important solution. High-density polyethylene (HDPE) film barrier technology is a commonly used method. Constructing a barrier layer with HDPE film forms a physical barrier that effectively prevents pollutants from migrating downward or upward. However, the airtightness of the HDPE film can lead to an increase in air pressure beneath the film, causing soil gas to diffuse around the edge of the barrier film. This means that gaseous pollutants migrate laterally along the edge of the HDPE film, forming a high-concentration plume outside the barrier area, which then spills into the clean area and causes secondary pollution.

[0003] Currently, existing technologies focus primarily on the airtightness of the membrane itself, neglecting the active interception and degradation of VOCs flowing around the edges. This makes it difficult to precisely control the protection effect and lacks an integrated solution that is low-cost, easy to construct, and capable of long-term operation. Therefore, a VOC-contaminated site edge barrier system and construction method with active degradation capabilities and a multi-mechanism collaboration is urgently needed. Summary of the Invention

[0004] The present invention aims to provide a method for preventing and controlling VOCs from flowing around the edge of a HDPE barrier film.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A method for preventing and controlling the edge flow and dispersion of gaseous pollutants in a barrier layer of a VOCs-contaminated site. An air collection area is set along the edge of a barrier layer constructed of HDPE film to collect VOCs that flow and disperse at the edge in the area. Ventilation pipes are laid in the area to regulate the redox conditions in the area and enhance the activity of VOCs-degrading bacteria. A soil-microorganism-plant coupled degradation system is formed with surface vegetation to achieve complete interception and in-situ biodegradation of VOCs that flow and disperse at the edge.

[0007] Furthermore, the following steps are sequentially implemented along the edge of the HDPE film:

[0008] (1) Interception and collection: HDPE-geotextile curtains are set along the edge of the HDPE membrane and filled with functional materials to collect VOCs that escape along the edge and form a gas collection area;

[0009] (2) Microbial degradation: In the gas collection area, pipelines of the control unit are laid out to regulate the redox conditions in the gas collection area and enhance the activity of VOCs-degrading bacteria, thereby achieving in-situ initial degradation of VOCs;

[0010] (3) Soil-plant-microorganism degradation: VOCs that diffuse upward from the gas collection area are further intercepted and degraded by constructing a soil-microorganism-plant coupled degradation system.

[0011] The curtain is set along the edge of the HDPE membrane by opening a groove outward along the edge of the HDPE membrane, laying geotextile and HDPE membrane in the groove, and leaving a VOCs overflow port at the junction of the longitudinal HDPE membrane and the transverse HDPE membrane at the bottom of the groove to form an HDPE-geotextile curtain, and then filling the groove with functional materials and nutrient soil with a graded pore structure in sequence, planting restoration plants, inoculating functional microorganisms or injecting biostimulants to collect and degrade VOCs, and laying a ventilation duct for a unit for regulating the redox conditions in the groove and the activity of VOCs-degrading bacteria.

[0012] The unit includes a main ventilation pipeline, an injection pipe, a gas storage tank, an air suction pump and a liquid storage tank. The main ventilation pipeline is connected to an injection main pipe with a control valve. Each injection main pipe is provided with multiple injection branches. The gas storage tank, air suction pump and liquid storage tank are respectively connected to the main pipeline through control valves. Among them, the gas storage tanks are divided into oxygen storage tanks and hydrogen storage tanks. The two gas storage tanks are respectively connected to the gas injection pump through pipelines, and then connected to the main pipeline through pipelines with control valves. A pneumatic liquid injection pump is provided between the liquid storage tank and the main pipeline.

[0013] The unit main ventilation pipe, injection main pipe and injection branch pipe are arranged in the groove; the distance between two adjacent injection main pipes is 2-20m, the perforated air guide pipe has a diameter of 50-100mm, an opening rate of 3%-5%, and is arranged along the edge of the membrane.

[0014] The unit is controlled by a PLC controller.

[0015] The redox conditions and the bacterial activity of VOCs degradation in the collection area are regulated by detecting the VOCs concentration in the environment through a unit, and then extracting, injecting gas or injecting liquid; according to the underground VOCs concentration, extraction (when the concentration is high) or injection of electron acceptors (e.g., oxygen) or electron donors (e.g., hydrogen) can be performed to regulate the environment to aerobic / anaerobic / facultative conditions, wherein when the VOC soil gas concentration is greater than the microbial degradable concentration, extraction treatment is performed to a lower concentration; when the VOCs are mainly halogenated hydrocarbons, hydrogen, degrading bacteria such as Dehalococcoides, and biostimulants such as acetate, polysaccharides, and oils are injected to promote the reduction and dehalogenation of halogenated hydrocarbons; when the VOCs are mainly hydrocarbons, oxygen, degrading bacteria such as Pseudomonas, and biostimulants such as polysaccharides and oils are injected to promote the aerobic degradation of organic hydrocarbons.

[0016] The biological functional material added to the liquid storage tank is a bacterial liquid and / or a biostimulant for degrading VOCs; wherein the biostimulant is a biostimulant of indigenous and / or exogenous VOCs degrading bacteria.

[0017] The functional materials filled in the groove are gravel and biochar, with a mass ratio of 70%-90%:10%-30%. The biochar particle size is 3mm-7mm and the pH is 6.5-8.5.

[0018] The gravel particle size is 5mm-10mm, the thickness of the filling functional material is ≥30cm, the total porosity is ≥35%, and the permeability coefficient is ≥1×10 -2 cm / s.

[0019] The bacterial liquid for degrading VOCs in the liquid storage tank and the VOC-degrading microbial liquid added to the nutrient soil can be the same or different and can be selected from one or more degradation bacteria with VOC degradation function, such as Pseudomonas, Bacillus, Rhodococcus, Acinetobacter, Comamonas, Dehalococcoides, and Dehalobacter; the biostimulant is one or more of acetate, lactate, formic acid, methanol, oils, sugars, nutrients, iron minerals, and zero-valent iron.

[0020] The amount of microorganisms added to the nutrient soil containing microorganisms capable of degrading VOCs is ≥10 7 CFU g -1 , nutrient soil is soil rich in organic matter, with an organic matter content of >2%.

[0021] The plant is a shallow-rooted shrub or herb suitable for growth.

[0022] Furthermore, high transpiration, pollution-tolerant herbs and shrubs are selected, specifically one or more of ryegrass, alfalfa, tall fescue, white clover, and astragalus.

[0023] When regulating the redox conditions in the collection area, the aerobic, anaerobic or facultative state of the degradation environment is regulated by injecting oxygen or hydrogen according to the type and concentration of the pollutants; and the VOCs concentration is reduced by extraction.

[0024] The in-situ degradation is achieved by adding microbial nutrient soil into the trench and injecting materials into the liquid storage tank in the unit to degrade the VOCs that are laterally collected in the trench, and by the combined degradation of plants and microorganisms planted in the nutrient soil (i.e., if the VOCs in the collection area diffuse upward, the plants planted in the nutrient soil will combine with the root microorganisms to degrade them); thereby achieving an in-situ plant-microorganism synergistic degradation process consisting of nutrient soil + indigenous / functional bacterial agents + repaired plant root zones.

[0025] The advantages of the present invention are:

[0026] The present invention provides a method for preventing and controlling the edge flow and diffusion of gaseous pollutants in a barrier layer of a VOCs-contaminated site, which is to treat the diffused VOCs by setting up a "interception-regulation-degradation" three-in-one method along the edge of an HDPE film. The process conditions are regulated according to the degradation pathway of the pollutants. First, functional microbial preparations, biostimulants or gases are injected through pipelines to adjust the aerobic, anaerobic or facultative conditions in the collection area, and the pollutants undergo the first stage of degradation. Then, the second stage of VOCs reduction is completed by the collaboration of plants and microorganisms through the planting soil-plant root zone.

[0027] The present invention targets the edge flow and diffusion of HDPE membranes, spatially couples the VOCs "interception and collection - environmental regulation - biodegradation" functions, and achieves an edge flow gas interception rate of ≥95%. It adopts specific degradation pathways according to the types and concentrations of VOCs in the environment, and accurately regulates aerobic / anaerobic / facultative conditions. In addition, the full life cycle cost of the method of the present invention is reduced by ≥80% compared with traditional VOCs extraction and treatment processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A conceptual schematic diagram of a longitudinal section of a method according to an embodiment of the present invention is provided.

[0029] Figure 2 Schematic diagram of the site layout using the embodiment method provided by the embodiment of the present invention

[0030] Figure 3 Detailed diagram of the pipe connections and valve wells in the unit provided in an embodiment of the present invention; wherein, 1- oxygen storage tank, 2- hydrogen storage tank, 3- air injection pump, 4- PLC controller, 5- air extraction pump (containing activated carbon), 6- main pipeline, 7- injection main pipe, 8- injection branch pipe, 9- pneumatic injection pump, 10- liquid storage tank (containing bacterial solution and biostimulation), 11- control valve

[0031] Figure 4 This is the operating logic and PLC control flow chart for regulating the environment in the groove provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The present invention discloses an integrated "collection-control-reduction" system for preventing and controlling VOCs that circulate and escape from the edge of HDPE barrier membranes, and a construction method thereof. Specifically, an air collection area is provided along the edge of the barrier layer constructed by the HDPE membrane to collect VOCs that circulate and escape from the edge within the area, and ventilation ducts are laid within the area to regulate the redox conditions within the area and enhance the activity of VOCs-degrading bacteria. A soil-microorganism-plant coupled degradation system is formed with surface vegetation to achieve complete interception and in-situ biodegradation of VOCs that circulate and escape from the edge. The method of the present invention has the advantages of low cost, easy construction, environmental friendliness, and landscape function, and is suitable for various VOCs pollution barrier projects.

[0034] The present invention constructs a soil-microbe-plant coupled degradation system, which can achieve complete interception and efficient in-situ biodegradation of edge-flow VOCs, with an edge escape gas reduction rate of ≥95%. It does not require a dedicated vacuum station or vapor phase extraction (SVE) and can operate without power under normal circumstances, making it a green and low-carbon process. The method of the present invention has the advantages of low cost, easy construction, environmental friendliness, and landscape function, and is suitable for various VOCs pollution barrier projects.

[0035] Example 1: Horizontal barrier area of ​​a decommissioned gas station (circumference 300m)

[0036] At a decommissioned gas station, the primary soil pollutant was petroleum hydrocarbons (TPH), with concentrations ranging from 3500 to 5800 mg / kg. Volatile organic compounds (VOCs) were primarily low-carbon alkanes and olefins, with maximum concentrations ranging from 1.9 to 65 mg / kg. HDPE film was installed on the site for horizontal isolation.

[0037] (1) Construction of prevention and control system

[0038] A trapezoidal trench was excavated along the outer edge of the HDPE membrane, with a cross-sectional size of 80 cm at the upper bottom, 40 cm at the lower bottom, and a depth of 1.2 m. The angle between the hypotenuse and the bottom was 80°. Geotextile and HDPE membrane were then laid in the trench to form a HDPE-geotextile micro-curtain. A VOCs spill outlet was provided at the junction of the vertical HDPE and the horizontal HDPE membrane (see Figure 1 and Figure 2 ). Among them, the thickness of the HDPE film is 0.5mm, and the specification of the geotextile is 400g / m2.

[0039] Then, functional materials with a graded pore structure are filled into the trench to collect VOCs, and pipes of a control unit for regulating the redox conditions in the trench and the activity of VOCs-degrading bacteria are arranged in the trench.

[0040] After the functional materials are filled in the above-mentioned trenches, nutrient soil containing VOCs-degrading bacteria is laid, and restoration plants are planted on the nutrient soil.

[0041] The filling height ratio of the above functional materials to nutrient soil is 1:3.

[0042] The unit includes a main ventilation pipeline, an injection pipe, a gas storage tank, an air suction pump and a liquid storage tank. The main pipeline is connected to an injection main pipe with a control valve, and each injection main pipe is provided with multiple injection branches. The gas storage tank, air suction pump and liquid storage tank are respectively connected to the main pipeline through control valves; wherein, the gas storage tanks are divided into hydrogen storage tanks and oxygen storage tanks, and the two gas storage tanks are respectively connected to the gas injection pump through pipelines, and then connected to the main pipeline through pipelines with control valves; a pneumatic liquid injection pump is provided between the liquid storage tank and the main pipeline, see Figure 3 .

[0043] The unit's main ventilation pipe, injection main pipe and injection branch pipe are laid in the trench; the distance between two adjacent injection main pipes is 10m, the distance between branches on each main pipe is 10cm, the injection main pipe has a diameter of 100mm, and the opening rate on the injection branch pipe is 5%.

[0044] The 30 cm layered backfill was graded biochar-gravel (mass ratio of coconut shell charcoal to gravel was 1:9, total porosity was 35%, and permeability coefficient was 3×10 -2 cm / s); 30 cm nutrient soil layer for absorbing VOCs gas; 60 cm nutrient soil layer (containing 10% organic matter, containing Pseudomonas sp., bacterial count 4×10 7 CFU g -1 ) and plant tall fescue in nutrient soil;

[0045] The unit is controlled by a PLC controller.

[0046] (2) Environmental regulation and in situ degradation

[0047] Since the pollutants in the land to be treated are mainly organic hydrocarbons, the collection area is regulated to a good growth condition, and the VOCs concentration in the environment is detected by the unit. The VOC degradation bacteria liquid Pseudomonas sp. is stored in the liquid storage tank of the unit. The unit is opened and 2000 mL of Pseudomonas liquid is injected into the gas collection area through the injection pipe. The bacterial content in the bacterial liquid is 1×10 9 CFU / ml; oxygen was injected into the collection layer for 30 minutes every 10 days at a rate of 0.1 L / min to ensure that the gas phase oxygen concentration was 5%-6% to maintain aerobic conditions. The entire system was run for 6 months to allow the VOCs gas in the gas collection area to be degraded in situ.

[0048] (3) Monitoring and effect evaluation

[0049] A gas flux box (50 cm × 50 cm) was placed in the surface vegetation area. Samples were taken at the beginning of the system operation and after 6 months to test the VOCs diffusion flux at the edge. At the same time, the injection pipe was controlled by the control unit to test the organic hydrocarbon concentration in the soil gas by the extraction method. The monitoring results showed that the hydrocarbon concentration in the soil gas increased from the initial 22.45 mg m -3 Reduced to <0.5 mg m -3 , the edge overflow flux is 2.3mg / (m 3 h) down to 0.08 mg / (m 3 h).

[0050] In the above examples, Pseudomonas was a commercially available strain, which was activated according to conventional methods and then inoculated into LB medium (Luria-Bertani) to set the medium in the logarithmic growth phase for later use.

[0051] Example 2: Isolation area of ​​a chlorinated hydrocarbon contaminated land

[0052] A plot of land contaminated by chlorinated hydrocarbons, with vinyl chloride as the primary pollutant, has concentrations ranging from 0.04mg / kg to 67.85mg / kg. The site has been covered with HDPE film.

[0053] (1) Barrier system construction

[0054] A trapezoidal trench with a width of 100 cm, a bottom edge of 40 cm, and a depth of 1.2 m was dug along the outer edge of the HDPE membrane around the plot, with a top angle of 75°. Geotextile and HDPE membrane were then laid in the trench to form a HDPE-geotextile curtain, and a VOCs overflow outlet was set at the junction of the vertical HDPE membrane and the horizontal HDPE membrane (see Figure 1 and Figure 2 ). Among them, the thickness of the HDPE film is 1mm and the specification of the geotextile is 400g / m2.

[0055] Then, functional materials with graded pore structures are filled into the trench to collect VOCs, and unit pipes are arranged in the trench to regulate the redox conditions in the gas collection area and the activity of VOCs-degrading bacteria.

[0056] After the functional materials are filled in the above-mentioned trenches, nutrient soil containing VOCs-degrading bacteria is laid, and restoration plants are planted on the nutrient soil.

[0057] The filling height ratio of the above functional materials to nutrient soil is 1:2.

[0058] The unit includes a main ventilation pipeline, an injection pipe, a gas storage tank, an air suction pump and a liquid storage tank. The main pipeline is connected to an injection main pipe with a control valve, and each injection main pipe is provided with multiple injection branches. The gas storage tank, air suction pump and liquid storage tank are respectively connected to the main pipeline through control valves; wherein, the gas storage tanks are divided into hydrogen storage tanks and oxygen storage tanks, and the two gas storage tanks are respectively connected to the gas injection pump through pipelines, and then connected to the main pipeline through pipelines with control valves; a pneumatic liquid injection pump is provided between the liquid storage tank and the main pipeline, see Figure 3 .

[0059] The unit's main ventilation pipe, injection main pipe and injection branch pipe are laid in the trench; the distance between two adjacent injection main pipes is 10m, the distance between branches on each main pipe is 10cm, the injection main pipe has a diameter of 100mm, and the opening rate on the injection branch pipe is 4%.

[0060] The stratified backfill was 40 cm of graded biochar-gravel (bamboo charcoal, particle size 5 mm, gravel, diameter 10 mm, mass ratio of the two 3:7), with a total porosity of 40%; the nutrient soil layer (containing Dehalococcoides, bacterial count ≥ 4 × 10 7 CFU g -1 )80cm, plant ryegrass in nutrient soil;

[0061] The unit is controlled by a PLC controller.

[0062] (2) Degradation system startup and environmental regulation

[0063] Due to the high concentration of vinyl chloride in the land to be treated, the initial vinyl chloride diffusion concentration was about 43.26 mg / m 3 Therefore, a hierarchical control strategy is adopted (see Figure 4 ):

[0064] High concentration stage (>20mg / m 3 ), implement active exhaust, the exhaust volume is 0.3m 3 / (m 2 ·d)m 3 / (m 2 d) Maintain the negative pressure under the membrane at 0.4 kPa and reduce the soil gas concentration to 20 mg / m 3 the following;

[0065] Low concentration stage (≤20mg / m 3), 4000ml of a halogenated hydrocarbon-degrading bacterial solution (containing Dehalococcoides bacteria and sodium acetate as an electron donor) was injected into the gas collection zone. H2 was injected into the collection layer every 10 days to maintain an anaerobic environment (oxidation-reduction potential (ORP) <100mV) to complete the first stage of dechlorination. The dehalogenated gas continuously diffused into the upper soil-plant root purification zone, where it was degraded into carbon dioxide and discharged. The entire system operated for three months.

[0066] The degradation bacterial solution is a Dehalococcoides bacterial solution and sodium acetate as an electron donor, wherein the bacterial concentration is 2×10 9 CFU / ml, sodium acetate concentration is 2mmo / L.

[0067] (3) Monitoring and effect evaluation

[0068] A gas flux chamber (50 cm x 50 cm) was placed in the surface vegetation area. Samples were taken at the beginning of the system operation and again after three months to measure the VOC flux at the edge. Simultaneously, the concentration of vinyl chloride in the soil gas was measured by extraction using an injection pipe. Furthermore, after three months, soil samples were collected from three layers above the membrane to measure the concentration of vinyl chloride in the soil.

[0069] The monitoring results showed that the concentration of vinyl chloride in soil gas increased from the initial 43.26 mg m -3 Down to 0.4 mg m -3 , the edge overflow flux is 3.35mg / (m 3 h) down to 0.13 mg / (m 3 h), the edge escape flux was reduced by 95%; the concentration of vinyl chloride in the soil outside the membrane was 0.08mg / kg, 0.10mg / kg, and 0.05mg / kg from bottom to top, all lower than the first-class land use screening value of GB 36600 (0.12mg / kg); the whole life cycle cost was lower than that of traditional VOCs extraction treatment (from 43mg / m 3 Reduced to 0.4 mg / m 3 ) process has been reduced by more than 80%.

[0070] In the above examples, the Dehalococcoides bacteria were commercially available. After activation according to conventional methods, they were inoculated into a reducing mineral salt medium (DSMZ 195 medium) and cultured anaerobically to the logarithmic growth phase for later use.

Claims

1. A method for preventing and controlling the edge flow and diffusion of gaseous pollutants in a barrier layer of a VOCs-contaminated site, characterized in that: Along the edge of the barrier layer constructed with HDPE film, an air collection area is set up to collect VOCs that flow around the edge and escape into this area. Ventilation pipes are laid in this area to regulate the redox conditions in the area and enhance the activity of VOCs-degrading bacteria. A soil-microorganism-plant coupled degradation system is formed with surface vegetation to achieve complete interception and in-situ biodegradation of VOCs that flow around the edge.

2. The method for preventing and controlling the edge flow and diffusion of gaseous pollutants in the barrier layer of VOCs contaminated sites according to claim 1, characterized in that: The barrier layer edge constructed along the HDPE film is sequentially implemented as follows: (1) Interception and collection: HDPE-geotextile curtains are set along the edge of the HDPE membrane and filled with functional materials to collect VOCs that escape along the edge and form a gas collection area; (2) Microbial degradation: In the gas collection area, pipelines of the control unit are laid out to regulate the redox conditions in the gas collection area and enhance the activity of VOCs-degrading bacteria, thereby achieving in-situ initial degradation of VOCs; (3) Soil-plant-microorganism degradation: VOCs that diffuse upward from the gas collection area are further intercepted and degraded by constructing a soil-microorganism-plant coupled degradation system.

3. The method for preventing and controlling the edge flow and diffusion of gaseous pollutants in the barrier layer of VOCs contaminated sites according to claim 1 or 2, characterized in that: The curtain is set along the edge of the HDPE membrane by opening a groove outward along the edge of the HDPE membrane, laying geotextile and HDPE membrane in the groove, and leaving a VOCs overflow port at the junction of the longitudinal HDPE membrane and the transverse HDPE membrane at the bottom of the groove to form an HDPE-geotextile curtain, and then filling the groove with functional materials and nutrient soil with a graded pore structure in sequence, planting restoration plants, inoculating functional microorganisms or injecting biostimulants to collect and degrade VOCs, and laying a ventilation duct for a unit for regulating the redox conditions in the groove and the activity of VOCs-degrading bacteria.

4. The method for preventing and controlling the edge flow and diffusion of gaseous pollutants in the barrier layer of VOCs contaminated sites according to claim 3, characterized in that: The unit includes a main pipeline, an injection pipe, a gas storage tank, an air suction pump and a liquid storage tank. The main pipeline is connected to an injection main pipe with a control valve, and each injection main pipe is provided with multiple injection branches. The gas storage tank, air suction pump and liquid storage tank are respectively connected to the main pipeline through control valves; among them, the gas storage tanks are divided into oxygen storage tanks and hydrogen storage tanks, and the two are respectively connected to the gas injection pump through pipelines, and then connected to the main pipeline through pipelines with control valves; a pneumatic liquid injection pump is provided between the liquid storage tank and the main pipeline.

5. The method for preventing and controlling the edge flow and diffusion of gaseous pollutants in the barrier layer of VOCs contaminated sites according to claim 3 or 4, characterized in that: The unit main pipeline, injection main pipe and injection branch pipe are arranged in the groove; the distance between two adjacent injection main pipes is 2-20m, the perforated air guide pipe has a diameter of 50-100mm, an opening rate of 3%-5%, and is arranged along the edge of the membrane.

6. The method for preventing and controlling the edge flow and diffusion of gaseous pollutants at the barrier layer of a VOCs-contaminated site according to claim 4, characterized in that: The biological functional material added to the liquid storage tank is a bacterial liquid and / or a biostimulant for degrading VOCs; wherein the biostimulant is a biostimulant of indigenous and / or exogenous VOCs-degrading bacteria.

7. The method for preventing and controlling the edge flow and diffusion of gaseous pollutants from the barrier layer of a VOCs-contaminated site according to claim 2, characterized in that: The functional materials filled in the groove are gravel and commercial biochar, and the mass ratio between the two is 70%-90%:10%-30%.

8. The method for preventing and controlling the edge flow and diffusion of gaseous pollutants from the barrier layer of VOCs contaminated sites according to claims 2 and 5, characterized in that: The redox conditions in the collection area are regulated according to the type and concentration of the pollutants, wherein the aerobic, anaerobic or facultative state of the degradation environment is regulated by injecting oxygen or hydrogen; and the VOCs concentration is reduced by extraction.

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