CN114273411A - Combined restoration system and restoration method for organic polluted site - Google Patents

Combined restoration system and restoration method for organic polluted site Download PDF

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CN114273411A
CN114273411A CN202210004548.8A CN202210004548A CN114273411A CN 114273411 A CN114273411 A CN 114273411A CN 202210004548 A CN202210004548 A CN 202210004548A CN 114273411 A CN114273411 A CN 114273411A
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well
layer
organic
soil
waste gas
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CN114273411B (en
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方华祥
苗竹
魏丽
闵玉涛
卫阿四
倪鑫鑫
刘泽权
陈征
方英
赵越
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Beijing Geoenviron Engineering and Technology Inc
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Beijing Geoenviron Engineering and Technology Inc
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Abstract

The invention discloses a combined remediation system and a remediation method for an organic contaminated site, belonging to the technical field of remediation of contaminated soil, and comprising a circle of vertical barrier walls which are arranged around the boundary of the organic contaminated soil; drilling a dewatering well, a heating well, a temperature detection well and a guide and drainage sand well; paving a permeable reaction layer, a drainage guide layer and a barrier layer on the surface of the organic polluted soil; starting a water pumping device to pump underground water in the organic polluted soil; and after the water pumping is finished, starting the heating device to heat and repair the organic contaminated soil. The invention fully utilizes waste gas afterheat to degrade organic pollutants through efficient chemical reaction by additionally arranging the guide-discharge sand well and the permeable reaction layer, solves the problems that gaseous pollutants are easy to cool and enrich on the surface layer, the waste gas treatment load is large, high-concentration polluted waste gas is difficult to reach the standard and the like in the conventional in-situ thermal desorption process, and realizes the high-efficiency safe civilized treatment and restoration of organic polluted sites to reach the standard.

Description

Combined restoration system and restoration method for organic polluted site
Technical Field
The invention belongs to the technical field of polluted soil remediation, and particularly relates to a combined remediation system and a remediation method for an organic polluted site.
Background
Global organic soil pollution has become more severe with the annual increase in global synthetic chemical production. The main categories of soil organic pollutants in China comprise: petroleum hydrocarbon pollutants, halogenated hydrocarbon pollutants, pesticide pollutants, polycyclic aromatic hydrocarbons, polychlorinated biphenyl, dioxin, phthalate esters and the like. The national soil pollution condition survey bulletin (2014) shows that the soil environment condition is not optimistic overall, the soil pollution in partial areas is serious, the soil environment quality of cultivated land is great, and the soil environment problem of industrial and mining waste land is prominent, wherein the overproof rate of the point positions of the 3 types of organic pollutants of hexachloro cyclohexane, dichlorodiphenyl trichloroethane and polycyclic aromatic hydrocarbon is 0.5%, 1.9% and 1.4% respectively. Because the organic pollutants in the soil have strong toxicity and can be widely spread, the organic pollutants can be concentrated and amplified along a food chain after being taken by organisms, some organic pollutants have carcinogenicity, teratogenicity and mutagenicity, and the organic polluted soil remediation gradually becomes the key point of site remediation along with the increasing attention of people on the harm of the organic pollutants in the soil, so that the research and development of the efficient organic polluted site soil remediation technology have important practical significance and huge market prospect.
At present, technologies used for repairing organic contaminated sites include chemical oxidation, leaching, thermal desorption, biodegradation and the like, wherein the thermal desorption technology directly or indirectly heats soil to a sufficient temperature to volatilize or separate pollutants from the contaminated soil, and then treats the volatilized pollutants to obtain clean soil. The thermal desorption technology is divided into an in-situ thermal desorption technology and an ex-situ thermal desorption technology in forms, and the in-situ thermal desorption technology has the advantages of no excavation of earthwork, no transportation, small interference to the surrounding environment, thorough pollutant removal, convenient operation, labor saving and the like, so the research and application range is gradually increased.
In-situ thermal desorption inputs heat energy to underground, heats soil and underground water, changes the saturated vapor pressure and solubility of target pollutants, promotes the volatilization or dissolution of the pollutants, and realizes the treatment process of removing the target pollutants through soil vapor extraction or multiphase extraction, including heat conduction heating, resistance heating, steam enhanced extraction and the like. A treatment process of transferring heat conduction heating (TCH) from a heat source to a polluted area in a conduction mode so as to heat soil and underground water, wherein a heating well can be heated in a direct electric heating mode, and can also be heated by media such as high-temperature flue gas generated by energy sources such as fuel gas and the like; a treatment process in which electric current is passed through a contaminated area by Electrical Resistance Heating (ERH) to heat soil and groundwater by the thermal effect of the electric current; steam Enhanced Extraction (SEE) is a treatment process in which high-temperature steam is injected into a contaminated area to heat soil and groundwater, thereby enhancing the extraction effect of a target pollutant. Generally, the SEE can only heat the soil to the maximum temperature of the boiling point of water (100 ℃, 1 atm), the ERH can heat the soil to 100-120 ℃, and the TCH can heat the soil to the maximum temperature of 800 ℃. For SVOCs which have boiling points higher than 100 ℃ and cannot generate azeotropic phenomenon, only TCH technology can be adopted for removing in a short time. However, the existing TCH in-situ thermal desorption process also has the difficulties that gaseous pollutants are easy to enrich on the surface layer, the waste gas treatment load is large, high-concentration polluted waste gas is difficult to reach the standard and the like, and the existing TCH in-situ thermal desorption process patent comprises the following steps:
a system (CN 214235567U) for repairing an organic polluted site by combining in-situ thermal desorption with chemical oxidation is disclosed, wherein the chemical oxidation treatment system comprises a plurality of injection wells, adjustable sleeves, medicament injection pumps, a medicament mixing tank, a medicament storage tank and the like, and is used for injecting in-situ chemical oxidation medicaments. The patent realizes the in-situ chemical oxidation treatment of the waste gas containing organic pollutants to a certain extent, but because of the existence of the extraction system, the total transfer path of the waste gas generated by heating is from underground to above ground, and is difficult to be completely captured by the chemical oxidation medicament injected in situ, and the difficulty that the waste gas is easy to be enriched on the surface layer in the traditional TCH in-situ thermal desorption process is not solved.
A contaminated soil strengthening in-situ thermal desorption additional heating device and a method (CN 112517622A) realize that a plurality of groups of heating pipes and extraction pipes are alternately arranged in a contaminated soil body layer by layer in the horizontal direction by additionally arranging an installation tunnel, so that a micro-circulation is formed, and the remediation efficiency is improved. Set up the installation gallery and carry out normal position horizontal drilling installation heating pipe and extraction pipe, be difficult to realize that the filter material packing all around of extraction pipe is closely knit, lead to waste gas extraction efficiency not high, and do not solve current TCH normal position thermal desorption technique exhaust-gas treatment load big, high concentration pollution waste gas difficult to difficult point up to standard etc..
A distributed in-situ thermal desorption waste gas treatment method (CN 112569780A), a self-sustaining oxidation extraction system of in-situ thermal desorption waste gas used in the soil remediation field and a method thereof (CN 112496018A), adopts the distributed in-situ waste gas treatment method, has the problems of more investment of in-situ waste gas treatment equipment, complex daily operation and maintenance and the like, and does not solve the problem that the waste gas is easy to enrich on the surface layer in the traditional TCH in-situ thermal desorption process.
In conclusion, aiming at the difficulties that the existing TCH in-situ thermal desorption process is easy to enrich gaseous pollutants on the surface layer, large in waste gas treatment load, difficult to reach the standard of high-concentration polluted waste gas and the like, a more efficient in-situ thermal desorption repair process for the organic polluted site is developed.
Disclosure of Invention
In order to solve the problems, the invention provides a combined remediation system and a remediation method for an organic contaminated site, wherein the system comprises:
the vertical separation wall is arranged at the boundary of the organic contaminated soil, and the bottom of the vertical separation wall is deep into the relatively impervious layer;
the dewatering well is arranged in the organic polluted soil, and a water pumping device is arranged in the dewatering well and used for pumping underground water in the organic polluted soil;
the heating well is arranged in the organic contaminated soil, and a heating device is arranged in the heating well and used for heating the interior of the organic contaminated soil;
the guide and drainage sand well is arranged in the organic polluted soil;
the permeable reaction layer is laid on the surface of the organic contaminated soil in a covering manner;
the guide and exhaust layer is laid on the permeable reaction layer in a covering manner, an extraction well is buried in the guide and exhaust layer, and an extraction device is arranged in the extraction well and used for extracting waste gas in the organic contaminated soil;
the barrier layer is laid on the guide and discharge layer in a covering manner;
wherein the components of the permeable reactive layer comprise middlings and chemical agents for carrying out redox reactions with the exhaust gas.
Preferably, the material of the vertical barrier wall is a cement soil material, and the depth of the bottom of the vertical barrier wall penetrating into the relative impervious layer is not less than 0.9 m.
Preferably, precipitation well, heating well, temperature detection well and the equal vertical setting of drainage guide sand well, just drainage guide sand well interval is located in the middle of the heating well.
Preferably, be equipped with quartz gravel in the sand drainage guide well, just the permeability coefficient of sand drainage well is 3~10 times of aquifer medium permeability coefficient.
Preferably, the wellhead of the sand guiding and draining well is communicated with the permeable reactive layer, and the inlet end of the extraction well is communicated with the permeable reactive layer, so that the sand guiding and draining well and the permeable reactive layer form an exhaust passage.
Preferably, the extraction well and the drainage sand well are vertically on the same straight line.
Preferably, the chemical agent is 10% by volume of the permeable reaction layer, and the chemical agent includes sodium persulfate, sodium percarbonate, and zero-valent iron.
Preferably, the permeability coefficient of the permeability reaction layer is between the permeability coefficient of an aquifer medium and the permeability coefficient of the drainage and guide sand well.
Preferably, the barrier layer includes foaming cement heat preservation layer and plain concrete surface course from the bottom up in proper order.
Preferably, a temperature detection well is drilled in the organic contaminated soil, and the start and stop of the extraction device are controlled by temperature and pressure signals monitored by the temperature detection well.
Preferably, the vertical barrier walls and the barrier layer are connected to form an enclosed space.
The invention also provides a repairing method of the combined repairing system for the organic polluted site, which comprises the following steps:
determining the range of the organic contaminated soil to be repaired according to the site risk assessment report and the repair scheme;
a circle of vertical separation wall is arranged along the boundary of the organic contaminated soil in an enclosing manner, and the bottom of the vertical separation wall extends into the relatively impervious layer;
drilling a dewatering well, a heating well and a guide and drainage sand well on the organic contaminated soil, wherein a water pumping device is arranged in the dewatering well, and a heating device is arranged in the heating well;
after drilling, sequentially covering and paving a permeable reaction layer, a guide and drainage layer and a barrier layer on the surface of the organic contaminated soil from bottom to top, burying an extraction well in the guide and drainage layer, wherein an extraction device is arranged in the extraction well;
in the laying process, the water pumping device, the heating device and the extraction device are connected with an external power system, and the outlet end of the extraction device and the outlet end of the water pumping device are respectively and correspondingly communicated with an external waste gas treatment system and an external wastewater treatment system;
after the laying is finished, starting the water pumping device to pump the underground water in the organic polluted soil into the wastewater treatment system;
after the water pumping is finished, starting the heating device again to heat and repair the organic contaminated soil;
simultaneously starting the extraction device, and conveying the waste gas formed by the heated organic contaminated soil to the waste gas treatment system;
wherein the permeable reactive layer comprises medium sand and chemical agent for oxidation-reduction reaction with the waste gas
Compared with the prior art, the invention has the beneficial effects that:
the permeable reaction layer, the drainage guide layer and the blocking layer are sequentially arranged above the organic polluted soil, so that the organic polluted soil is well insulated, the problem of insufficient surface temperature rise in the conventional in-situ thermal desorption process is solved, organic pollutants in the surface area of the organic polluted soil can be desorbed and volatilized to be separated, and the problem of recondensation and enrichment of semi-volatile gaseous pollutants volatilized and separated in a deep layer on the surface layer due to insufficient surface temperature rise is avoided; meanwhile, the waste gas must pass through the permeable reaction layer, and the chemical agent in the permeable reaction layer can effectively capture and chemically react to degrade the organic pollutants in the waste gas, so that the in-situ efficient chemical reaction degradation of the organic polluted waste gas is realized, and the difficulty that the high-concentration polluted waste gas in the conventional in-situ thermal desorption process is difficult to reach the standard is solved.
Drawings
FIG. 1 is a schematic flow diagram of the present invention for a combined remediation system for organically contaminated sites;
fig. 2 is a block diagram of the integrated remediation system for organically contaminated sites according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Referring to fig. 1 and 2, a combined remediation system and a remediation method for an organically polluted site,
the system comprises:
the vertical separation wall 1 is arranged at the boundary of the organic contaminated soil 18, and the bottom of the vertical separation wall 1 extends into the relatively impervious layer;
the dewatering well 2 is arranged in the organic polluted soil 18, and a water pumping device is arranged in the dewatering well 2 and is used for pumping underground water in the organic polluted soil 18;
the heating well 4 is arranged in the organic contaminated soil 18, and a heating device 5 is arranged in the heating well 4 and used for heating the interior of the organic contaminated soil 18;
the guide and drainage sand well 6 is arranged in the organic polluted soil 18;
the permeable reaction layer 17 is paved on the surface of the organic contaminated soil 18 in a covering manner;
the guide and exhaust layer 16 is laid on the permeable reaction layer 17 in a covering manner, the guide and exhaust layer 16 is embedded into the extraction well 8, and the extraction well 8 is internally provided with an extraction device for extracting waste gas in the organic contaminated soil 18;
the barrier layer 9 is laid on the guide and exhaust layer 16 in a covering manner;
wherein the permeable reactive layer 17 comprises the components of the middlings and the chemical agent for performing the oxidation-reduction reaction with the exhaust gas.
The system repairing method comprises the following steps:
determining the range of the organic contaminated soil 18 to be repaired according to the site risk assessment report and the repair scheme;
a circle of vertical separation wall 1 is arranged around the boundary of the organic polluted soil 18, and the bottom of the vertical separation wall 1 extends into the relatively impervious layer;
drilling a dewatering well 2, a heating well 4, a temperature detection well and a guide and drainage sand well 6 on the organic polluted soil 18, wherein a water pumping device is arranged in the dewatering well 2, and a heating device 5 is arranged in the heating well 4;
after drilling, a permeable reaction layer 17, a guide and drainage layer 16 and a blocking layer 9 are sequentially laid on the surface of the organic contaminated soil 18 from bottom to top in a covering manner, the guide and drainage layer 16 is embedded into an extraction well 8, an extraction device is arranged in the extraction well 8, and the vertical blocking wall 1 and the blocking layer 9 are connected to form a closed space;
in the laying process, the water pumping device, the heating device 5 and the extraction device are connected with an external power system 10, and the outlet end of the extraction device and the outlet end of the water pumping device are respectively and correspondingly communicated with an external waste gas treatment system 11 and an external waste water treatment system 12;
specifically, a dewatering pipeline 3 is arranged in the dewatering well 2, a water pumping device pumps underground water through the dewatering pipeline 3, is communicated with a wastewater treatment system 12 through a wastewater collection pipeline 13, and is connected with an electric power system 10 through cables 7 and 15; the extraction well 8 is communicated with the waste gas treatment system 11 through a waste gas collecting pipeline 14 and is connected with an extraction device through cables 7 and 15; the heating device is connected to the power system 10 by means of cables 7, 15.
After the laying is finished, starting a water pumping device to pump underground water in the organic polluted soil 18 into the wastewater treatment system 12;
after the water pumping is finished, starting the heating device 5 again to heat and repair the organic contaminated soil 18;
meanwhile, the start and stop of the extraction device are controlled by temperature and pressure signals monitored by the temperature detection well, and the waste gas extracted by the extraction device is conveyed to the waste gas treatment system 11;
wherein, the permeable reactive layer 17 comprises the components of the middlings and the chemical agent for generating the oxidation-reduction reaction with the waste gas. In the process that the waste gas passes through the permeable reaction layer 17, the waste gas is subjected to oxidation-reduction reaction with chemical agents under the reinforcement of waste gas preheating, and is degraded into nontoxic carbon dioxide and water; realizes the in-situ efficient chemical reaction degradation of the organic polluted waste gas and solves the difficulty that the high-concentration polluted waste gas in the existing in-situ thermal desorption process is difficult to reach the standard. And the waste gas degraded by the chemical reaction of the permeable reaction layer 17 is pumped to the ground through an extraction well 8 arranged in the guide and exhaust layer 16 for standard reaching detection: when the exhaust gas meets the emission requirement, the smoke directly passes through the exhaust gas treatment system 11 and is discharged in an organized manner; when the waste gas does not meet the emission requirement, the waste gas is further subjected to one or more processes of spraying, dust removal, catalytic combustion and the like through the waste gas treatment system 11 and then is subjected to organized emission through smoke flushing, so that the total amount of waste gas treatment is greatly reduced; solves the problem of large load of waste gas treatment in the existing in-situ thermal desorption process.
Further, the chemical agent accounts for 10% of the volume of the permeable reaction layer 17, and the chemical agent includes sodium persulfate, sodium percarbonate, and zero-valent iron. The permeability coefficient of the permeability reaction layer 17 is between the permeability coefficient of the aquifer medium and the permeability coefficient of the drainage and guide sand well 6.
In this embodiment, the material of the vertical separation wall 1 is a cement soil material, and the depth of the bottom of the vertical separation wall 1 penetrating into the opposite impermeable layer is not less than 0.9 m. The rock-soil layer with low water permeability is arranged relative to the impervious layer, and the permeability coefficient is not more than 10- 6cm/s。
Specifically, a rigid cement soil material is adopted to form the wall, the wall forming process is three-axis stirring or high-pressure rotary spraying, when the three-axis stirring process is adopted, the cement mixing amount is 30% -40%, and when the high-pressure rotary spraying process is adopted, the cement mixing amount is 18% -22%. The high-pressure rotary spraying process is used as a supplement of a triaxial stirring process and is used in an area where triaxial stirring equipment cannot enter and a final interface closure area.
In this embodiment, precipitation well 2, heating well 4, temperature detection well and the equal vertical setting of drainage guide sand well 6, and drainage guide sand well 6 interval is located in the middle of heating well 4.
Furthermore, after the sand drainage well 6 is formed into a hole through a long spiral drilling machine, quartz gravel is poured into the sand drainage well through the top end of the hollow spiral opening immediately, and the permeability coefficient of the sand drainage well is 3-10 times of that of a water-bearing stratum medium.
In this embodiment, the wellhead of the drainage sand well 6 is in communication with the permeable reactive layer 17, and the inlet end of the extraction well 8 is in communication with the permeable reactive layer 17, such that the drainage sand well 6 and the permeable reactive layer 17 form an exhaust gas passage.
Further, the extraction well 8 and the drainage guide sand well 6 are vertically positioned on the same straight line.
In this embodiment, barrier layer 9 includes foaming cement heat preservation layer and plain concrete surface course from the bottom up in proper order. The organic contaminated soil 18 is well insulated, the problem of insufficient surface temperature rise of the existing in-situ thermal desorption process is solved, the organic pollutants in the surface area of the organic contaminated soil 18 can be desorbed and volatilized to be separated, and the problem of recondensing and enriching the semi-volatile gaseous pollutants volatilized and separated in the deep layer on the surface layer due to insufficient surface temperature rise is avoided.
In this embodiment, the heating device 5, the water pumping device and the extraction device are all conventional devices, for example, the heating device 5 is a heating rod, a heating wire, etc., the water pumping device is a water pumping pump, etc., and the extraction device is a fan, etc.
Example 1
The technology for the in-situ thermal desorption and the combined restoration of the permeable reaction layer 17 in the organic pollution site disclosed by the patent is used for carrying out on-site pilot plant test on the organic pollution site in Anhui, wherein the main pollutants are sixty-six, the range of the pilot plant test is 10m by 10m, and the maximum pollution depth is 10 m. Supplementary investigation before the pilot test starts obtains that the average value of the six (total) in the field is as high as 40.68mg/kg, and the repair target value is 0.9mg/kg of the six (total).
S1, constructing the vertical barrier wall 1 along the polluted boundary until reaching the opposite impervious bed: the stratum in the pilot test area is filled with miscellaneous fill from top to bottom, the layer thickness is about 3.2m, the layer thickness of clay is 2.2m, the layer thickness of silty clay is 17.1m, and as no relative impervious layer exists near the bottom of the pollution depth, in order to guarantee the dewatering effect of the subsequent dewatering well 2, the vertical separation wall 1 is built to a depth of 15m, and the wall is formed by adopting three-axis stirring and high-pressure rotary spraying processes.
S2, co-building a 436 th heating well, wherein the well depth is 10.5m, the aperture is 220mm, and the diameter of the casing is 65 mm; 4 mouths of the temperature monitoring well, the well depth is 10.5m, the aperture is 80mm, and the diameter of the casing is 32 mm; 22 mouths of dewatering wells, the well depth is 12m, the aperture is 220mm, and the diameter of the casing is 110 mm; and the opening of the sand guiding and draining well 614 is 10m in depth and 65mm in aperture. Wherein the heating well 4 and the temperature monitoring well casing are of solid wall structures, the dewatering well 2 is of a sieve wall structure, and quartz sand is backfilled around the casing and is densely filled; after the guide and drainage sand well 6 is formed into a hole by a long spiral drilling machine, quartz gravel is poured into the guide and drainage sand well 6 through the top end of a hollow spiral opening to form the gas guide and drainage sand well 6, and the permeability coefficient of the guide and drainage sand well 6 is 5 times that of an aquifer medium.
S3, the thickness of the horizontally laid permeable reaction layer 17 is 20cm, the structure is a framework-gap structure formed by mechanically and uniformly mixing medium sand, sodium persulfate, sodium percarbonate and zero-valent iron chemical agents, the permeability coefficient of the structure is between that of an aquifer medium and the drainage sand well 6, the ratio of the sodium persulfate, the sodium percarbonate and the zero-valent iron is 3:3:1, the volume ratio of the chemical agents is 10% of the volume of the permeable reaction layer 17, and the horizontally laid permeable reaction layer 17 is horizontally and loosely laid after being mechanically and uniformly mixed.
S4, horizontally paving the drainage guide layer 16 on the surface layer of the permeable reaction layer 17, and embedding the screened extraction well 8 in the drainage guide layer, wherein the underground part of the extraction well 8 is a screened metal pipe, and the pipe well is 65 mm.
S6, paving a horizontal barrier layer 9 consisting of a foamed cement heat-insulating layer and a plain concrete surface layer above the guide and exhaust layer 16 in sequence, wherein the thickness of the foamed cement heat-insulating layer is 10cm, and the thickness of the plain concrete surface layer is 15cm, and completing the connection of a power line, a signal line, a waste gas collecting pipeline, a waste water collecting pipeline and the like. Wherein the power line, the signal line are integrated into a Power Control Unit (PCU) and connected to the transformer output via the PCU. The waste gas collecting pipeline is connected to a waste gas treatment system 11 through a vacuum pump in an extraction way, and the treatment capacity is 5000m3And h, the wastewater collecting pipeline is connected to the wastewater treatment system 12 through a submersible pump, and the treatment capacity is 5 t/h. After the connection of the pipeline and the cable is completed and the test is completed, the process of the in-situ thermal desorption combined permeability reaction layer 17 enters an operation stage.
S7, in the operation stage, the water level of the underground water in the barrier wall 1 is reduced to 0.5m below the maximum depth of the quasi-in-situ thermal desorption restoration through the precipitation of the precipitation well 2, and 200m of the polluted underground water is pumped and treated in total3After the wastewater is treated by the integrated water treatment equipment, the concentration of target pollutants reaches the requirement of ground water quality standard (GBT-14848-2017), and then the clear water is temporarily stored in a support pond.
S8, after the heating rod is electrified and heated, starting a vacuum pump of the waste gas extraction well 8, extracting the waste gas which rises from the underground and passes through the permeable reaction layer 17 to the ground, and carrying out standard reaching detection on the waste gas which passes through the extraction well 8 to the ground: when the exhaust gas meets the emission requirement, the smoke directly passes through the exhaust gas treatment system 11 and is discharged in an organized manner; when the waste gas does not meet the emission requirement, the waste gas is further subjected to one or more processes of spraying, dust removal, catalytic combustion and the like through the waste gas treatment system 11 and then is discharged in an organized manner through smoke flushing. The heating lasts for 50 calendar days, wherein 20 calendar days are consumed at 19-100 ℃, 7 calendar days are consumed at 100 ℃ and 23 calendar days are consumed at 100-330 ℃.
S9, carrying out in-situ thermal sampling after heating is finished, carrying out drilling sampling by adopting a system point distribution method, carrying out layered sampling, wherein 4 point positions of drilled holes are totally counted, 20 soils are totally counted, and the total amount of sixty-six (six) in all the soils is lower than a first type land screening value of soil pollution risk control standards (trial) for soil environmental quality construction sites (GB 36600-2018).
And S10, after the pollutants in the target site are repaired to reach the standard, the clear water temporarily stored in the support water pool field is refilled underground through the precipitation well 2, the underground water level in the site is restored, and the repair engineering is finished.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A combined remediation system for an organically contaminated site, comprising:
the vertical separation wall is arranged at the boundary of the organic contaminated soil, and the bottom of the vertical separation wall is deep into the relatively impervious layer;
the dewatering well is arranged in the organic polluted soil, and a water pumping device is arranged in the dewatering well and used for pumping underground water in the organic polluted soil;
the heating well is arranged in the organic contaminated soil, and a heating device is arranged in the heating well and used for heating the interior of the organic contaminated soil;
the guide and drainage sand well is arranged in the organic polluted soil;
the permeable reaction layer is laid on the surface of the organic contaminated soil in a covering manner;
the guide and exhaust layer is laid on the permeable reaction layer in a covering manner, an extraction well is buried in the guide and exhaust layer, and an extraction device is arranged in the extraction well and used for extracting waste gas in the organic contaminated soil;
the barrier layer is laid on the guide and discharge layer in a covering manner;
wherein the components of the permeable reactive layer comprise middlings and chemical agents for carrying out redox reactions with the exhaust gas.
2. The integrated remediation system for organically contaminated sites of claim 1 wherein the material of said vertical barrier is a cemented soil material and the depth of said vertical barrier bottom into said relatively impervious bed is no less than 0.9 m.
3. The combined remediation system for an organically contaminated site as claimed in claim 1 wherein the dewatering well, the heater well and the drainage sand well are all vertically disposed with the drainage sand well spaced intermediate the heater well.
4. The combined remediation system for an organically polluted site as claimed in claim 3 wherein the sand drainage and guide well is provided with quartz gravel and has a permeability coefficient 3 to 10 times that of the aquifer medium.
5. The integrated remediation system for an organically contaminated site of claim 1 wherein the wellhead of the drainage sand well is in communication with the permeable reactive layer and the inlet end of the extraction well is in communication with the permeable reactive layer such that the drainage sand well and the permeable reactive layer form an exhaust gas pathway.
6. The integrated remediation system for an organically contaminated site of claim 1 wherein the chemical agent comprises 10% by volume of the permeable reactive layer and comprises sodium persulfate, sodium percarbonate, and zero-valent iron.
7. The integrated remediation system for an organically contaminated site of claim 6 wherein the permeability reactive layer permeability coefficient is between an aquifer media permeability coefficient and the drainage sand well permeability coefficient.
8. The combined remediation system for an organically contaminated site of claim 1 wherein the barrier layer comprises, in order from bottom to top, a layer of foamed cement insulation and a plain concrete facing.
9. The combined remediation system for an organically contaminated site as claimed in claim 1 wherein a temperature sensing well is drilled into the organically contaminated soil and the start and stop of the extraction device is controlled by temperature and pressure signals monitored by the temperature sensing well.
10. A remediation method for a combined remediation system for an organically contaminated site as claimed in any one of claims 1 to 9 including:
determining the range of the organic contaminated soil to be repaired according to the site risk assessment report and the repair scheme;
a circle of vertical separation wall is arranged along the boundary of the organic contaminated soil in an enclosing manner, and the bottom of the vertical separation wall extends into the relatively impervious layer;
drilling a dewatering well, a heating well and a guide and drainage sand well on the organic contaminated soil, wherein a water pumping device is arranged in the dewatering well, and a heating device is arranged in the heating well;
after drilling, sequentially covering and paving a permeable reaction layer, a guide and drainage layer and a barrier layer on the surface of the organic contaminated soil from bottom to top, burying an extraction well in the guide and drainage layer, wherein an extraction device is arranged in the extraction well;
in the laying process, the water pumping device, the heating device and the extraction device are connected with an external power system, and the outlet end of the extraction device and the outlet end of the water pumping device are respectively and correspondingly communicated with an external waste gas treatment system and an external wastewater treatment system;
after the laying is finished, starting the water pumping device to pump the underground water in the organic polluted soil into the wastewater treatment system;
after the water pumping is finished, starting the heating device again to heat and repair the organic contaminated soil;
simultaneously starting the extraction device, and conveying the waste gas formed by the heated organic contaminated soil to the waste gas treatment system;
wherein the permeable reactive layer comprises medium sand and chemical agents for carrying out oxidation-reduction reaction with the waste gas.
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