Repair system and repair method for organic polluted clay site

Abstract

The invention relates to a remediation system and a remediation method for an organic polluted clay site. The repairing system comprises a repairing liquid storage tank, a nutrition storage tank, a microbial fermentation tank, a peristaltic pump, a PVC pipe, an aeration device and an extraction device, the repairing liquid storage tank and the air compressor are connected with the PVC pipe, the repairing liquid storage tank injects high-pressure repairing liquid into clay through the air compressor, cracks are formed, and the aeration device is connected with the aeration device. Then the pressed repair liquid is in contact with the pollutants through migration in the cracks, the interfacial tension of the pollutants is reduced, and therefore the solubility of the pollutants is improved, and the nutrition storage tank and the microbial fermentation tank are connected with the peristaltic pump; the nutrient storage tank and the microbial fermentation tank inject nutrient substances and efficient degrading bacteria into soil through the PVC pipes correspondingly, the nutrient substances and the efficient degrading bacteria are promoted to rapidly reach a pollution source through cracks, and the remediation process is more efficient. The remediation efficiency of the organic contaminated clay site can be improved, and the remediation effect of the organic contaminated clay site is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of contaminated soil restoration, and in particular to a restoration system and a restoration method for an organic contaminated clay site. Background Art

[0002] The technologies currently developed can be divided into two types: in-situ remediation and ex-situ remediation, depending on the location of soil remediation. Among them, in-situ remediation technology refers to a remediation technology that uses physical, chemical and biological methods to repair soil pollution to a concentration below the standard without disturbing the structure of the polluted soil. It is widely recognized and used due to its considerable effects, simple operation, low cost and low secondary pollution to the soil. As one of the commonly used in-situ soil remediation technologies, gas phase extraction technology is mainly based on the in-situ physical removal of pollutants, enhancing the transformation of pollutants to the gas phase for recycling, and has achieved good remediation effects in unsaturated zones with relatively good uniformity and permeability. The biological ventilation method is based on changing the environmental conditions of biodegradation, such as ventilation conditions, adding nutrient solution, etc., thereby increasing the degradation activity of soil microorganisms, thereby achieving the purpose of pollutant degradation.

[0003] However, in actual engineering applications, these methods all have some problems: in organically contaminated clay sites with high groundwater levels, the clay layer is saturated and dense, with poor permeability, making it difficult for gas to escape. It is greatly affected by permeability and soil moisture content, which makes the gas phase extraction technology remediation effect easily reduced. At the same time, this technology has a long period of low recovery rate in the later stage, and there is a tailing phenomenon, making it difficult to achieve efficient remediation of organic pollutants. In other methods, nutrient solution is added to the soil layer and an aerobic or anaerobic environment is created, but the actual remediation effect is affected by many factors, the remediation process is long, and long-term monitoring is required.

[0004] In the prior art, a Chinese patent (application publication number: CN116159855A) discloses a contaminated soil remediation method and remediation system: a contaminated soil remediation method and remediation system, the remediation method includes: thermal desorption of the contaminated soil; grinding the contaminated soil; adding a stabilizing agent to the contaminated soil; applying a vibration force to the contaminated soil, and adding water to the contaminated soil so that the contaminated soil, water and stabilizing agent are combined to form a soil block; pressing the soil block to a target shape. By fully mixing the contaminated soil with the stabilizing agent, it is beneficial to improve the remediation effect, and at the same time provides a new idea for the coordination of contaminated soil remediation and comprehensive resource utilization. However, the technical solution provided by this patent does not belong to in-situ remediation technology, and cannot solve the pollution problem in saturated clay with high water content.

[0005] A Chinese patent (application number: CN202011551211.6) discloses a method for the combined in-situ remediation of contaminated soil by electrokinetic-microorganisms: by conducting a pollution analysis on the contaminated site to be treated, the soil is divided into high-concentration, medium-concentration and low-concentration petroleum hydrocarbon contaminated soil, and then the soils with different degrees of contamination are repaired by the anode encryption electrode group, the electrokinetic microbial cooperative electrode group and the biological enhancement electrode group, thereby realizing the in-situ remediation of the contaminated soil; the pollution analysis divides the high-concentration, medium-concentration and low-concentration petroleum hydrocarbon contaminated soil into high-concentration contaminated soil with a petroleum hydrocarbon concentration of >4%, medium-concentration contaminated soil with a content of 1-4% and low-concentration contaminated soil with a content of <1%. However, in this technology, there are fewer types of pollutants that can be treated, and the soil layer properties and groundwater conditions of the contaminated site are not involved.

[0006] That is, in the prior art methods for remediating contaminated soil, there is a problem that the remediation process is long and requires long-term monitoring. At the same time, the remediation efficiency of highly saturated organic contaminated clay sites is low due to poor permeability.

[0007] Therefore, the existing technology needs to be improved. Summary of the invention

[0008] In view of the problem in the prior art that highly saturated organically contaminated clay sites have low remediation efficiency due to poor permeability, the present invention provides a remediation system and a remediation method for organically contaminated clay sites to solve the above problem.

[0009] To achieve the above-mentioned purpose, in the first aspect, the present invention provides a remediation system for organically contaminated clay sites, which includes a remediation liquid storage tank, a nutrient storage tank, a microbial fermentation tank, a peristaltic pump, a PVC pipe, an aeration device and an extraction device. The remediation liquid storage container and the air compressor are respectively connected to high-pressure nylon pipes. The remediation liquid storage tank injects high-pressure remediation liquid into the soil through the air compressor to form cracks in the clay. Subsequently, the pressed remediation liquid begins to flow into the cracks, increasing the solubility of pollutants, reducing interfacial tension and promoting pollutant mobilization. The nutrient storage tank and the microbial fermentation tank are respectively connected to the peristaltic pump. The nutrient storage tank and the microbial fermentation tank inject nutrients and high-efficiency degradation bacteria into the soil through the PVC pipe, respectively. The cracks formed help nutrients and high-efficiency degrading bacteria to quickly reach the pollution source, making the remediation process more efficient. The aeration device includes an air compressor and an aeration plate, the air compressor and the aeration plate are connected through the PVC pipe, the aeration device is used to inject high-pressure air or oxygen into the soil, the extraction device includes an extraction well and a vacuum pump, and the extraction device is used to extract the pollutants out of the soil through the extraction well.

[0010] In one implementation, the aeration plates and the extraction wells are distributed in a cross-like manner.

[0011] In one implementation, the aeration plate is a plastic drainage plate, and the extraction well is a plastic drainage plate.

[0012] In one implementation, the extraction device also includes a gas-liquid separation unit, a tail gas treatment unit and a recovery liquid treatment unit, the vacuum pump is connected to the gas-liquid separation unit through the PVC pipe, and the gas-liquid separation unit is connected to the tail gas treatment unit and / or the recovery liquid treatment unit in turn through the PVC pipe.

[0013] In one implementation, the repair liquid is connected to a high-pressure machine through a PVC pipe, and the high-pressure repair liquid is injected into the soil through the PVC pipe. The repair liquid is 80% ethanol + 4wt% surfactant (SDS: Tween804:6) + 0.6wt% NaCl.

[0014] In one implementation, the microbial fermentation tank is used to propagate a large number of efficient degradation bacteria and then inject them into the soil through the PVC pipe by a peristaltic pump. The efficient degradation bacteria include any one of Bacillus subtilis, Sphingobacillus multivorans and Sphingobacillus thermophilus or a combination thereof.

[0015] In one implementation, the nutrient storage tank is used to transport nutrients into the soil and groundwater through the PVC pipe, and the nutrients include any one of nitrate nitrogen, amino nitrogen, humic acid and rhamnolipid or a combination thereof.

[0016] In a second aspect, the present invention further provides a method for remediating an organically contaminated clay site, which uses the remediation system for an organically contaminated clay site of the present invention, and specifically comprises the following steps: S1, injecting a remediation liquid into the soil by a high pressure machine, and as the resistance of the soil layer to the remediation liquid increases, the pressure in the wellbore increases accordingly, and cracks are formed in the clay, and then the injected remediation liquid begins to flow into the cracks, thereby increasing the solubility of pollutants, reducing interfacial tension and promoting pollutant mobilization;

[0017] S2. Inject nutrients and high-efficiency degradation bacteria from nutrient storage tanks and microbial fermentation tanks into the soil through a peristaltic pump. The cracks formed will help nutrients and high-efficiency degradation bacteria quickly reach the pollution source, making the remediation process more efficient.

[0018] S3, injecting air into the soil through an aeration device to create a living environment for microorganisms, promote the proliferation of degradation microorganisms, and decompose large molecular and highly volatile organic pollutants in the soil into small molecular pollutants under the action of the degradation microorganisms;

[0019] S4, generate negative pressure through a vacuum pump to extract gaseous and liquid pollutants out of the soil through the plastic drainage board;

[0020] S5, separating the extracted gas-phase and liquid-phase pollutants through a gas-liquid separation unit;

[0021] S6. The separated pollutants are respectively introduced into the tail gas treatment unit or the recovery liquid treatment unit.

[0022] In one implementation, the repair solution is 80% ethanol+4wt% surfactant (SDS:Tween804:6)+0.6wt% NaCl.

[0023] In one implementation, the efficient degradation bacteria include any one of Bacillus subtilis, Sphingobacterium multivorans and Sphingobacterium mesophilum, or a combination thereof.

[0024] In one implementation, the nutrients include any one or a combination of nitrate nitrogen, amino nitrogen, humic acid and rhamnolipid.

[0025] Beneficial effects: The repair system and repair method provided by the present invention combine gas phase extraction technology, biological ventilation technology and soft soil drainage consolidation technology by setting a repair liquid storage tank, a nutrient storage tank, a microbial fermentation tank, a peristaltic pump, a PVC pipe, an aeration device and an extraction device, introduce plastic drainage boards into the gas phase extraction-biological ventilation technology, and adopt a cross-arrangement. More drainage boards can be arranged in the same area, which can not only increase the seepage rate, but also effectively shorten the seepage path of bound water in the soil, accelerate the repair process, strengthen the degradation of pollutants and the infiltration effect of drainage consolidation, improve the repair efficiency of organic contaminated clay sites, increase the repair effect of organic contaminated clay sites, and can be applied to the remediation of pollutants in highly saturated organic contaminated clay sites. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The schematic diagram of the application of the remediation system for organic contaminated clay sites shown;

[0027] Figure 2 It is a schematic diagram of the site layout and unit layout of the aeration plates and extraction wells;

[0028] Figure 3 This is a schematic diagram of the cracks formed by the repair fluid passing through the high-pressure machine;

[0029] Figure 4 It is a flow chart of the steps of the repair method for an organically contaminated clay site provided by the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0031] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0032] Embodiment 1

[0033] Combined with reference Figure 1 , Figure 2 and Figure 3 , Figure 1 is a schematic diagram of the use of the repair system for organic contaminated clay sites provided by the present invention, Figure 2 yes Figure 1 The schematic diagram of the site layout and unit layout of the aeration plate and extraction well is shown, in which the injection plate and the extraction plate are cross-distributed, and a total of four extraction units are shown in the figure. Figure 3 yes Figure 1 The schematic diagram of the cracks formed by the repair liquid through the high pressure machine is shown. The present invention provides a repair system for an organic contaminated clay site, which includes a repair liquid storage tank, a nutrient storage tank, a microbial fermentation tank, a peristaltic pump, a PVC pipe, an aeration device and an extraction device. The repair liquid storage container is connected to the high pressure machine through a high pressure nylon pipe, and the repair liquid is injected into the soil through the high pressure machine to form cracks in the clay. Subsequently, the repair liquid pressed in begins to flow into the cracks, thereby increasing the solubility of pollutants and reducing interfacial tension to promote pollutant mobilization. The nutrient storage tank and the microbial fermentation tank are respectively connected to the peristaltic pump, and the nutrient storage tank and the microbial fermentation tank respectively inject nutrients and high-efficiency degradation bacteria into the soil through the PVC pipe, and the cracks formed help nutrients and high-efficiency explanation bacteria to quickly reach the pollution source, making the repair process more efficient. The aeration device includes an air compressor and an aeration plate, and the air compressor and the aeration plate are connected through the PVC pipe. The aeration device is used to inject high-pressure air or oxygen into the soil to create a good biological environment. The extraction device comprises an extraction well and a vacuum pump, and the extraction device is used to extract the pollutants out of the soil through the extraction well.

[0034] The repair system for organically contaminated clay sites provided by the present invention injects the repair liquid into the soil through a high-pressure machine to form cracks to provide a delivery channel. Subsequently, nutrients and high-efficiency degradation bacteria are injected into the soil through a nutrient storage tank and a microbial fermentation tank, and transported by connecting a peristaltic pump and a PVC pipe. Then, high-pressure air or oxygen is injected through an aeration device to increase the respiratory activity of microorganisms in the soil and accelerate the degradation process of organic pollutants. Finally, gaseous and liquid pollutants are extracted from the soil through an extraction device to achieve the purpose of repairing the site.

[0035] Specifically, the repair liquid storage tank and the air compressor are connected to PVC pipes respectively. The repair liquid storage tank injects high-pressure repair liquid into the soil through the air compressor to form cracks in the clay. Then the pressed repair liquid begins to flow into the cracks, increasing the solubility of pollutants, reducing interfacial tension and promoting pollutant mobilization. The repair liquid is 80% ethanol + 4wt% surfactant (SDS: Tween804:6) + 0.6wt% NaCl.

[0036] Specifically, the nutrient storage tank is used to transport nutrients into the soil through the PVC pipe to provide nutrients required for degradation of organic pollutants. The nutrients include any one of nitrate nitrogen, amino nitrogen, humic acid and rhamnolipid or a combination thereof.

[0037] Specifically, the microbial fermentation tank is used to cultivate and store efficient degradation bacteria, multiply the efficient degradation bacteria in large quantities, and inject them into the soil and groundwater through a PVC pipe by a peristaltic pump to provide microorganisms required for degradation of organic pollutants. The efficient degradation bacteria include any one of Bacillus subtilis, Sphingobacillus multivorans, and Sphingobacillus thermophilus, or a combination thereof.

[0038] Specifically, the peristaltic pump is used to transport nutrients and high-efficiency degradation bacteria from the nutrient storage tank and the microbial fermentation tank to the soil and groundwater. The PVC pipe connects various devices and is used to transport nutrients and high-efficiency degradation bacteria.

[0039] Specifically, the aeration device increases the respiratory activity of microorganisms in the soil by injecting high-pressure air or oxygen, promotes the degradation of organic matter in contaminated soil by microorganisms, and effectively decomposes macromolecular pollutants into small molecular pollutants that are easy to degrade, which is beneficial to subsequent extraction. Among them, the aeration plate and the extraction well are cross-distributed to achieve the best remediation effect. In this embodiment, the aeration plate is a plastic drain plate, and the extraction well is a plastic drain plate. The aeration device is connected to the plastic drain plate through an air compressor and inserted into the soil. The air compressor is started to inject air or high-content oxygen into the soil, increasing the soil porosity, while creating an oxygen-rich environment, improving the activity of microorganisms, and promoting microbial decomposition.

[0040] Wherein, the extraction well is a plastic drainage board, which is composed of a plastic core board and a water-permeable non-woven fabric wrapped around the outer periphery of the plastic core board. Several plastic drainage boards are inserted into the soil through a plate inserter. Under the action of the preload, the interstitial water in the soil passes through the non-woven filter membrane layer and is discharged from the soil through the drainage channel formed on the plastic core board. The seepage path of the bound water in the soil is effectively shortened, and the infiltration effect of pollutant degradation and drainage consolidation is enhanced. Through the cross-distribution of the aeration plate and the extraction well, nutrients and high-efficiency degradation bacteria can be uniformly injected at different positions, ensuring that the degradation of organic pollutants in the soil and groundwater is uniformly carried out, and the remediation efficiency is improved. Through the cross-distribution of the extraction well, the extracted pollutants can be evenly discharged to different positions, avoiding the risk of re-infiltration of pollutants in the soil, and at the same time, the centralized collection and treatment of pollutants can be ensured. Through the cross-distribution of the aeration plate and the extraction well, the injection of nutrients and the discharge of pollutants can be more uniform, which improves the overall efficiency and stability of the remediation system. Through the cross-distribution of aeration plates and extraction wells, more drainage plates can be arranged in the same area, which can not only increase the seepage rate, but also effectively shorten the seepage path of bound water in the soil and accelerate the repair process.

[0041] Specifically, the extraction device also includes a gas-liquid separation unit, an exhaust gas treatment unit and a recovery liquid treatment unit. The vacuum pump is connected to the gas-liquid separation unit through the PVC pipe, and the gas-liquid separation unit is connected to the exhaust gas treatment unit and the recovery liquid treatment unit in sequence through the PVC pipe. The extraction device extracts pollutants out of the soil through the extraction well and the vacuum pump, so as to achieve the purpose of repairing the organically contaminated clay site at the groundwater level. When in use, the extraction device generates negative pressure through the plastic drain board inserted into the soil through the vacuum pump, and extracts gas-phase and liquid-phase pollutants out of the soil through the plastic drain board. The vacuum pump is connected to the gas-liquid separation unit through a PVC pipe, and the pollutants enter the exhaust gas treatment unit and the recovery liquid treatment unit through the PVC pipe after passing through the gas-liquid separation unit.

[0042] See also Figure 4 , Figure 4 The present invention also provides a method for repairing an organic contaminated clay site, which specifically includes the following steps:

[0043] S1. The repair liquid in the repair liquid storage tank is injected into the soil through a high-pressure machine to form cracks in the clay. Then the pressed repair liquid begins to flow into the cracks, increasing the solubility of pollutants, reducing interfacial tension and promoting pollutant mobilization;

[0044] S2. Inject nutrients and high-efficiency degradation bacteria from nutrient storage tanks and microbial fermentation tanks into the soil through a peristaltic pump. The cracks formed will help nutrients and high-efficiency degradation bacteria quickly reach the pollution source, making the remediation process more efficient.

[0045] S3, injecting air into the soil through an aeration device to create a living environment for microorganisms, promote the proliferation of degradation microorganisms, and decompose large molecular and highly volatile organic pollutants in the soil into small molecular pollutants under the action of the degradation microorganisms;

[0046] S4, generate negative pressure through a vacuum pump to extract gaseous and liquid pollutants out of the soil through the plastic drainage board;

[0047] S5, separating the extracted gas-phase and liquid-phase pollutants through a gas-liquid separation unit;

[0048] S6. The separated pollutants are respectively introduced into the tail gas treatment unit or the recovery liquid treatment unit.

[0049] Among them, in S3, air is injected into the soil through an aeration device to create an optimal living environment suitable for microorganisms, and then the optimal living environment is used to promote the massive reproduction of degradation microorganisms. Under the action of degradation microorganisms, large-molecular and highly volatile organic pollutants in the soil are decomposed into small-molecular pollutants.

[0050] The remediation method for organic contaminated clay sites provided by the present invention combines vapor phase extraction technology (SVE) and biological ventilation technology (BV) and soft soil drainage consolidation technology to solve the problem of low remediation efficiency caused by poor permeability of highly saturated organic contaminated clay sites, and provides a remediation method with better remediation effect.

[0051] In summary, the repair system and repair method provided by the present invention, by setting a repair liquid storage tank, a nutrient storage tank, a microbial fermentation tank, a peristaltic pump, a PVC pipe, an aeration device and an extraction device, combines gas phase extraction technology, biological ventilation technology and soft soil consolidation drainage technology, effectively decomposes macromolecular pollutants into small molecular pollutants that are easier to degrade, performs gas phase extraction, and the extracted gas is discharged into the atmosphere after being treated by removing water vapor and adsorption, or according to the different pollutants, adopts corresponding gas treatment technology. At the same time, the plastic drain board is introduced into the gas phase extraction-biological ventilation technology, and a cross-type arrangement is adopted. More drain boards can be arranged in the same area, which can not only increase the seepage rate, but also effectively shorten the seepage path of bound water in the soil, accelerate the repair process, strengthen the degradation of pollutants and the infiltration effect of drainage consolidation, improve the repair efficiency of organic polluted clay sites, increase the repair effect of organic polluted clay sites, and can be applied to the remediation of pollutants in highly saturated organic polluted clay sites.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A remediation system for highly volatile organic polluted clay sites, characterized in that: It includes a repair liquid storage tank, a nutrient storage tank, a microbial fermentation tank, a peristaltic pump, a PVC pipe, an aeration device and an extraction device. One end of the repair liquid storage tank is provided with an air compressor connected by a PVC pipe. The nutrient storage tank and the microbial fermentation tank are respectively connected to the peristaltic pump. The aeration device includes an air compressor and an aeration plate. The air compressor and the aeration plate are connected by the PVC pipe. The extraction device includes an extraction well and a vacuum pump.

2. The remediation system for a highly volatile organic polluted clay site according to claim 1, characterized in that: The aeration plates and the extraction wells are distributed in a cross-type manner.

3. The remediation system for a highly volatile organic polluted clay site according to claim 2, characterized in that: The aeration plate is a plastic drainage plate, and the extraction well is a plastic drainage plate.

4. The remediation system for a highly volatile organic polluted clay site according to claim 1, characterized in that: The extraction device also includes a gas-liquid separation unit, a tail gas treatment unit and a recovery liquid treatment unit. The vacuum pump is connected to the gas-liquid separation unit through the PVC pipe, and the gas-liquid separation unit is connected to the tail gas treatment unit and / or the recovery liquid treatment unit in turn through the PVC pipe.

5. The remediation system for a highly volatile organic polluted clay site according to claim 1, characterized in that: The repair liquid is connected to the high-pressure machine through a PVC pipe, and the high-pressure repair liquid is injected into the soil through the PVC pipe. The repair liquid is 80% ethanol+4wt% surfactant+0.6wt% NaCl.

6. The remediation system for a highly volatile organic polluted clay site according to claim 1, characterized in that: The microbial fermentation tank is used to propagate a large number of efficient degradation bacteria and then inject them into the soil through the PVC pipe by a peristaltic pump. The efficient degradation bacteria include any one of Bacillus subtilis, Sphingobacillus multivorans and Sphingobacillus mesophilus or a combination thereof.

7. The remediation system for a highly volatile organic polluted clay site according to claim 1, characterized in that: The nutrient storage tank is used to transport nutrients into the soil and groundwater through the PVC pipe, and the nutrients include any one of nitrate nitrogen, amino nitrogen, humic acid and rhamnolipid or a combination thereof.

8. A method for remediating a highly volatile organic polluted clay site, characterized in that: A remediation system for a highly volatile organic polluted clay site according to any one of claims 1 to 6 is used, which specifically comprises the following steps: S1. The repair fluid is injected into the soil through a high-pressure machine to form cracks in the clay. Then the injected repair fluid begins to flow into the cracks, increasing the solubility of pollutants, reducing interfacial tension and promoting pollutant mobilization; S2. Inject nutrients and high-efficiency degradation bacteria from nutrient storage tanks and microbial fermentation tanks into the soil through a peristaltic pump. The cracks formed will help nutrients and high-efficiency degradation bacteria quickly reach the pollution source, making the remediation process more efficient. S3, injecting air into the soil through an aeration device to create a living environment for microorganisms, promote the proliferation of degradation microorganisms, and decompose large molecular and highly volatile organic pollutants in the soil into small molecular pollutants under the action of the degradation microorganisms; S4, generate negative pressure through a vacuum pump to extract gaseous and liquid pollutants out of the soil through the plastic drainage board; S5, separating the extracted gas-phase and liquid-phase pollutants through a gas-liquid separation unit; S6. The separated pollutants are respectively introduced into the tail gas treatment unit or the recovery liquid treatment unit.

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