CN114101305A - In-situ low-temperature enhanced chemical oxidation remediation system and method for organic contaminated site - Google Patents
In-situ low-temperature enhanced chemical oxidation remediation system and method for organic contaminated site Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
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Abstract
The invention discloses an in-situ low-temperature reinforced chemical oxidation remediation system and method for an organic polluted site, wherein in the system, heating electrodes are distributed and inserted into soil and underground water of the organic polluted site to heat the soil and the underground water to 50-70 ℃; the delivery unit delivers the oxidizing agent prepared by the dispensing unit to soil and underground water in an organic pollution site; the intelligent monitoring and controlling device comprises a temperature monitoring sensor, a pH monitoring sensor, a water content monitoring sensor, a conductivity monitoring sensor and an oxidation-reduction potential monitoring sensor which are respectively distributed in the organic pollution site; the extraction device extracts gas or water generated in the repair process to the tail gas and wastewater treatment device through an extraction pipeline for centralized treatment. According to the technical scheme, the low-temperature heating and activation of the oxidant promotes solubilization and desorption of pollutants, reduces energy consumption, improves mass transfer of the oxidizing agent, and is high in automation degree, high in repairing efficiency and free of secondary pollution.
Description
Technical Field
The invention relates to the technical field of soil and underground water pollution remediation, in particular to an in-situ low-temperature enhanced chemical oxidation remediation system for an organic pollution site and an in-situ low-temperature enhanced chemical oxidation remediation method for the organic pollution site.
Background
According to incomplete statistics, about 30-50 ten thousand industrial pollution sites exist in China, wherein nearly 70% of the sites mainly contain volatile or semi-volatile organic pollutants, and great threats are caused to human habitation and ecological environment safety. Most of the developed restoration projects adopt modes of ex-situ excavation, ex-situ disposal landfill and the like, the disturbance to the surrounding environment is large, the restoration efficiency is low, the secondary pollution control difficulty is large, and the group events are easily caused.
Different repair technologies are gradually coupled and strengthened to be combined and applied to become the mainstream development direction of the current industry, and particularly, the method aims at sites with complex pollutant composition and water and soil combined pollution. The chemical oxidation repair technology is widely applied by virtue of the advantages of high repair efficiency, short repair period, flexible construction and the like. However, the chemical oxidation repair technology is greatly influenced by hydrogeological conditions, and application bottlenecks such as poor mass transfer of an oxidation material in a viscous stratum, difficulty in effective contact with pollutants, large consumption of an oxidation agent and the like exist. The in-situ electric heating restoration technology has strong adaptability to different hydrogeological conditions, has good application performance in low-permeability viscous stratum, but has the problems of strong limitation of medium-low temperature heating, high energy consumption and the like.
Disclosure of Invention
Aiming at the problems that the chemical oxidation repair technology is greatly influenced by hydrogeological conditions, the viscous stratum oxidation material has poor mass transfer, is difficult to effectively contact with pollutants, and has application bottlenecks with large consumption of oxidation agents, the invention provides an in-situ low-temperature reinforced chemical oxidation repair system and a method for an organic contaminated site, which are used for repairing the site with complex composition of pollutants and water-soil combined pollution or the contaminated site in a production enterprise, and through combining an in-situ thermal desorption technology and a chemical oxidation technology, the pollutants in soil and underground water are promoted to be solubilized and desorbed while an oxidant is activated by low-temperature heating to accelerate the oxidation reaction of the organic matters, compared with the traditional thermal repair technology, the energy consumption is reduced, the mass transfer of the oxidation agents in the soil and underground water is improved, and in addition, the low-temperature heating, the injection of the oxidation agents and the whole extraction process are automatically controlled, the process parameters are adjusted in real time through the intelligent monitoring and control device, and the method has the advantages of high automation degree, good mass transfer of the oxidizing agent, high repair efficiency, low energy consumption, no secondary pollution and the like.
In order to achieve the purpose, the invention provides an in-situ low-temperature reinforced chemical oxidation remediation system for an organic contaminated site, which comprises: the system comprises a low-temperature heating device, an oxidizing agent injection device, an intelligent monitoring and controlling device, a gas-water extraction device and a tail gas and wastewater treatment device;
the low-temperature heating device comprises heating electrodes which are distributed and inserted into soil and underground water in an organic pollution site so as to heat the soil and the underground water to 50-70 ℃;
the oxidizing agent injection device comprises a dispensing unit and a conveying unit, wherein the dispensing unit is used for preparing an oxidizing agent, and the conveying unit is used for conveying the oxidizing agent prepared by the dispensing unit to soil and underground water in the organic pollution site;
the intelligent monitoring and control device comprises a temperature monitoring sensor, a pH monitoring sensor, a water content monitoring sensor, a conductivity monitoring sensor and an oxidation-reduction potential monitoring sensor, and the sensors of the intelligent monitoring and control device are respectively distributed in soil and underground water of the organic pollution site;
the gas-water extraction device comprises an extraction device and an extraction pipeline, and the extraction device extracts gas or water generated in the repair process in the organic pollution site to the tail gas and wastewater treatment device through the extraction pipeline;
the tail gas and wastewater treatment device is used for carrying out centralized treatment on gas and wastewater generated in the repair process.
In the above technical solution, preferably, the organic pollution site is provided with a multifunctional well, the heating electrode, the conveying unit, the sensor of the intelligent monitoring and control device, and the extraction pipeline are all disposed in the multifunctional well, and the depth of the multifunctional well extends to a pollution depth area of the organic pollution site.
In the above technical scheme, preferably, the low-temperature heating device further comprises an earth surface sealing layer, the earth surface sealing layer covers the organic pollution site, the thickness of the earth surface sealing layer is 10-100 cm, and the earth surface sealing layer extends 2-3 m to the outer side of the edge of the multifunctional well, so that the step voltage in the repair area is smaller than 15 v.
In the above technical solution, preferably, the oxidizing agent injection device further includes a medicine storage unit, and after the medicine dispensing unit prepares the solid oxidizing agent into a solution with a preset concentration or dilutes the liquid oxidizing agent into a solution with a preset concentration, the medicine storage unit stores the oxidizing agent obtained by the medicine dispensing unit;
the delivery unit comprises a medicament delivery power device and a medicament delivery pipeline, the medicament delivery power device is a diaphragm pump or a plunger pump, and the oxidation medicament stored in the medicament storage unit is delivered to soil and underground water at a specified position in the organic polluted site through the medicament delivery pipeline under the driving of the medicament delivery power device.
In the above technical scheme, preferably, the extraction device includes a water pumping device and an air pumping device, the extraction pipeline includes a water pumping pipeline and an air pumping pipeline, the water pumping device pumps the wastewater in the repair process through the water pumping pipeline and conveys the wastewater to the tail gas and wastewater treatment device, and the air pumping device pumps the gas in the repair process through the air pumping pipeline and conveys the gas to the tail gas and wastewater treatment device.
In the above technical solution, preferably, the low-temperature heating device further includes an electric power distribution device, and the electric power distribution device is composed of a plurality of independent single-phase transformers and a control cabinet, and is used for outputting a power-frequency alternating current to three-phase and single-phase automatic step modulation;
the power distribution device is respectively connected with the heating electrodes through control cables.
In the above technical solution, preferably, the in-situ low-temperature enhanced chemical oxidation remediation system for an organic contaminated site further comprises a control device, and the control device is respectively connected with the low-temperature heating device, the oxidizing agent injection device, the intelligent monitoring control device and the gas-water extraction device;
the control device adjusts the heating power of the low-temperature heating device, adjusts the injection flow of the oxidizing agent injection device and controls the extraction flow and the start and stop of the gas-water extraction device according to the monitoring data of the intelligent monitoring control device.
The invention also provides an in-situ low-temperature enhanced chemical oxidation remediation method for the organic contaminated site, which is applied to the in-situ low-temperature enhanced chemical oxidation remediation system for the organic contaminated site, and comprises the following steps:
heating the soil and the underground water in the organic pollution site to 50-70 ℃ by a heating electrode;
injecting an oxidizing agent into soil and underground water of the organic contaminated site;
monitoring the temperature, the pH value, the conductivity, the water content and the oxidation-reduction potential parameters of the organic pollution site in real time, and adjusting the power of the heating electrode and the injection flow of the oxidizing agent according to the real-time monitoring parameters in a feedback manner;
and extracting gas and water generated in the organic pollution site repairing process to a tail gas and wastewater treatment device until the organic pollutants in the organic pollution site reach a safe target value.
In the above technical solution, preferably, the in-situ low-temperature enhanced chemical oxidation remediation method for the organic contaminated site further includes:
arranging multifunctional wells in the organic pollution site in advance;
and arranging the heating electrode, a medicament conveying pipeline of the oxidizing medicament, a sensor for monitoring the parameters of the organic pollution site in real time and an extraction pipeline for extracting gas and water in the multifunctional well.
In the above technical solution, preferably, the generated gas and water are extracted while injecting the oxidizing agent into the organic contaminated site, so as to promote diffusion of the oxidizing agent in the organic contaminated site by using a pressure difference generated in an extraction process.
Compared with the prior art, the invention has the beneficial effects that: through combining together normal position thermal desorption technique and chemical oxidation technique, when utilizing low temperature heating activation oxidant in order to accelerate organic matter oxidation reaction, promote the solubilization of pollutant in soil and the groundwater, the desorption, compared in traditional heat restoration technique and reduced the energy consumption, the mass transfer nature of oxidation medicament in soil and groundwater has been improved, in addition with low temperature heating, the oxidation medicament is injected into, extract full process automation control, through the instant adjustment process parameter of intelligent monitor control device, it is high to have degree of automation, the oxidation medicament mass transfer nature is good, repair efficiency is high, the energy consumption is low, no secondary pollution, etc.
Drawings
FIG. 1 is a cross-sectional view of the overall structure of an in-situ low-temperature enhanced chemical oxidation remediation system for an organic contaminated site according to one embodiment of the present invention;
FIG. 2 is a schematic flow chart of an in-situ low-temperature enhanced chemical oxidation remediation method for an organic contaminated site according to an embodiment of the present invention;
fig. 3 is a schematic view of a specific implementation flow of the in-situ low-temperature enhanced chemical oxidation remediation method for an organic contaminated site according to an embodiment of the present invention.
In the drawings, the correspondence between each component and the reference numeral is:
11. heating the electrode; 12. surface sealing layer; 13. a power distribution device; 2. an oxidizing agent injection device; 21. a medicine storage unit; 22. a medicament delivery line; 3. an intelligent monitoring control device; 41. an extraction device; 42. an extraction pipeline; 5. a tail gas and wastewater treatment device; 6. soil; 7. ground water; 8. and a control device.
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.
The invention is described in further detail below with reference to the attached drawing figures:
as shown in fig. 1, the in-situ low-temperature enhanced chemical oxidation remediation system for an organic contaminated site provided by the present invention comprises: a low-temperature heating device, an oxidizing agent injection device 2, an intelligent monitoring and controlling device 3, a gas-water extraction device 41 and a tail gas and wastewater treatment device 5;
the low-temperature heating device comprises heating electrodes 11, wherein the heating electrodes 11 are distributed and inserted into soil 6 and underground water 7 of an organic pollution site to heat the soil 6 and the underground water 7 to 50-70 ℃;
the oxidizing agent injection device 2 comprises a dispensing unit and a conveying unit, wherein the dispensing unit is used for preparing the oxidizing agent, and the conveying unit is used for conveying the oxidizing agent prepared by the dispensing unit to soil 6 and underground water 7 of an organic pollution site;
the intelligent monitoring and control device 3 comprises a temperature monitoring sensor, a pH monitoring sensor, a water content monitoring sensor, a conductivity monitoring sensor and an oxidation-reduction potential monitoring sensor, and the sensors of the intelligent monitoring and control device 3 are respectively distributed in soil 6 and underground water 7 of the organic pollution site;
the gas-water extraction device 41 comprises an extraction device 41 and an extraction pipeline 42, and the extraction device 41 extracts gas or water generated in the remediation process in the organic pollution site to the tail gas and wastewater treatment device 5 through the extraction pipeline 42;
the tail gas and wastewater treatment device 5 is used for carrying out centralized treatment on gas and wastewater generated in the repair process.
In this embodiment, through combining together normal position thermal desorption technique and chemical oxidation technique, utilize low temperature heating activation oxidant in order to accelerate organic matter oxidation reaction, promote the solubilization of pollutant in soil 6 and groundwater 7, desorption, compared with traditional thermal remediation technique and reduced the energy consumption, the mass transfer of oxidation medicament in soil 6 and groundwater 7 has been improved, in addition with low temperature heating, the oxidation medicament is injected into, extract full process automation control, through the instant adjustment process parameters of intelligent monitoring controlling means 3, have the degree of automation height, the oxidation medicament mass transfer is good, it is efficient to restore, the energy consumption is low, no secondary pollution, etc.
Specifically, by inserting the heating electrode 11 into the soil 6 and underground water 7 medium, the current can be controlled to be transmitted between the electrodes in a targeted manner by utilizing the graded modulation technology, and the polluted soil 6 and underground water 7 at different depths are heated to 50-70 ℃ by utilizing the resistance characteristics of the soil 6 and the underground water 7. The oxidizing agent injection device 2 is configured with the oxidizing agent and accurately delivers the oxidizing agent to the target contaminated area. By utilizing the sensors for various parameters in the intelligent monitoring and control device 3, the heating power of the low-temperature heating device and the injection flow of the oxidizing agent injection device 2 can be accurately regulated and controlled in real time according to various parameters, and energy conservation and consumption reduction are effectively realized. For example, after the soil 6 and groundwater 7 are monitored to be heated to 50 ℃, the heating power of the heating motor is reduced.
The volatilized organic pollution gas or gas-water mixture is extracted to the ground by the gas-water extraction device 41 and is transmitted to the tail gas and wastewater treatment device 5 through a pipeline for centralized treatment, so that secondary pollution to the surrounding environment is avoided, and meanwhile, the diffusion of the oxidant in the stratum is promoted by the pressure difference generated by extraction.
In the repairing process, the oxidant is activated at a low temperature of 50-70 ℃, so that the activity and mass transfer of the oxidant are improved, the generated oxidizing free radicals such as OH and the like can oxidize organic pollutants into low-toxicity or non-toxicity substances, and the ecological environment risk of a site is reduced; in addition, the low temperature condition of 50-70 ℃ can improve the capability of the pollutant for desorbing soil particles, and can also improve the solubility of the pollutant in underground water, thereby accelerating the contact reaction rate of the oxidant and the pollutant and greatly improving the oxidation efficiency. The oxidation reaction of the oxidation medicament is heated and activated at low temperature, the solubilizing and desorbing capability of pollutants is enhanced, the energy consumption is only 1/3 of the traditional thermal remediation technology, the consumption of the oxidant can be reduced by more than 30% compared with the traditional chemical oxidation remediation technology, and the remediation energy consumption is reduced by more than 50% compared with the traditional thermal remediation technology.
Specifically, the heating electrode 11 is a novel composite electrode, and the heating electrode 11 can be arranged in layers according to the depth of the polluted stratum.
In the above embodiment, preferably, the organic pollution site is provided with a multifunctional well, the heating electrode 11, the conveying unit, the sensor of the intelligent monitoring and control device 3, and the extraction pipeline 42 are uniformly distributed in the multifunctional well, and the depth of the multifunctional well extends to the pollution depth area of the organic pollution site. Through the setting of multi-functional well, optimized heating well, extraction well, moisturizing well structure, "three well unifications", utilize electric current to add heat-conduction and eliminate the temperature difference, the homogeneity of stratum heating is showing and is improving.
In the above embodiment, preferably, the low-temperature heating device further includes a surface sealing layer 12, the surface sealing layer 12 covers the organic pollution site, the thickness of the surface sealing layer 12 is 10-100 cm, and the surface sealing layer 12 extends 2-3 m to the outer side of the edge of the multifunctional well, so that the step voltage in the repair area is less than 15 v.
In the above embodiment, preferably, the low-temperature heating device further includes a power distribution device 13, where the power distribution device 13 is composed of a plurality of independent single-phase transformers and a control cabinet, and is used for outputting a three-phase single-phase automatic step-by-step modulation to the power-frequency alternating current; the power distribution devices 13 are connected to the heating electrodes 11 through control cables, respectively. Under the control of the power distribution device 13 with automatic grading modulation, the current is transmitted between the heating electrodes 11 in a targeted mode, so that the soil and the underground water in the designated area of the organic pollution field are heated.
In the above embodiment, preferably, the oxidizing agent injection device 2 further includes a drug storage unit 21, and after the drug dispensing unit prepares the solid oxidizing agent into a solution with a preset concentration or dilutes the liquid oxidizing agent into a solution with a preset concentration, the drug storage unit 21 stores the oxidizing agent obtained by the drug dispensing unit;
the delivery unit comprises a medicament delivery power device and a medicament delivery pipeline 22, the medicament delivery power device is preferably a diaphragm pump or a plunger pump, and the oxidation medicament stored in the medicament storage unit is delivered to the soil 6 and the underground water 7 at the appointed position in the organic pollution site through the medicament delivery pipeline 22 under the driving of the medicament delivery power device. The agent delivery pipeline 22 is preferably made of stainless steel or polypropylene which is resistant to oxidation and corrosion, and the oxidizing agent is preferably persulfate.
In order to deliver the oxidizing agent to the designated areas of the soil 6 and the groundwater 7, the agent delivery pipeline 22 may be a main pipeline and a branch pipeline, and the oxidizing agent is delivered to the designated areas of the multifunctional wells or pressurized injection devices in a divided manner and then injected into the soil 6 and the groundwater 7.
In the above embodiment, preferably, the extraction device 41 includes a water pumping device and an air pumping device, preferably a centrifugal pump and an air compressor, the extraction pipeline 42 includes a water pumping pipeline and an air pumping pipeline, preferably made of heat-resistant and corrosion-resistant high-density polyethylene, stainless steel, and the like, the water pumping device pumps the wastewater in the repairing process through the water pumping pipeline and conveys the wastewater to the tail gas and wastewater treatment device 5, the wastewater can be recycled after being treated to reach the standard, and the air pumping device pumps the gas in the repairing process through the air pumping pipeline and conveys the gas to the tail gas and wastewater treatment device 5, and the gas is discharged after being treated to reach the standard.
In the above embodiment, preferably, the in-situ low-temperature-enhanced chemical oxidation remediation system for the organic contaminated site further includes a control device 8, where the control device 8 is respectively connected to the low-temperature heating device, the oxidizing agent injection device 2, the intelligent monitoring and control device 3, and the gas-water extraction device 41;
the control device 8 adjusts the heating power of the low-temperature heating device, adjusts the injection flow of the oxidizing agent injection device 2, and controls the extraction flow and start and stop of the gas-water extraction device 41 according to the monitoring data of the intelligent monitoring control device 3.
Wherein, the control device 8 is equipped with a standard interface and can receive monitoring signals of various sensors of temperature, pH, water content, conductivity and oxidation-reduction potential, and control signals of the oxidation medicament injection device 2 and the gas-water extraction device 41.
Through the in-situ low-temperature reinforced chemical oxidation remediation system for the organic contaminated site, the whole processes of low-temperature heating, injection of oxidation agents and extraction are automatically controlled, soil 6 and underground water are integrally heated by the heating system to about 7-50-70 ℃, oxidants such as persulfate are activated by low-temperature heating to accelerate the oxidation reaction of organic matters, the solubilizing and desorption capacities of pollutants are enhanced, and the in-situ low-temperature reinforced chemical oxidation remediation system for the organic contaminated site has the advantages of high automation degree, good mass transfer of the oxidation agents, high remediation efficiency, low energy consumption, no secondary pollution and the like. The removal rate of the repaired organic pollutants is over 90 percent, the environmental risk of a polluted area is greatly reduced, and effective support is provided for the development and the reutilization of the land of the urban industrial enterprise.
As shown in fig. 2, the present invention further provides an in-situ low-temperature enhanced chemical oxidation remediation method for an organic contaminated site, which is applied to the in-situ low-temperature enhanced chemical oxidation remediation system for an organic contaminated site disclosed in any one of the above embodiments, and includes:
injecting an oxidizing agent into soil 6 and underground water 7 of the organic pollution site;
monitoring the temperature, pH value, conductivity, water content and oxidation-reduction potential parameters of the organic pollution site in real time, and adjusting the power of the heating electrode 11 and the injection flow of the oxidizing agent according to the real-time monitoring parameters in a feedback manner;
and extracting gas and water generated in the process of repairing the organic pollution site to a tail gas and wastewater treatment device 5 until the organic pollutants in the organic pollution site reach a safe target value.
In this embodiment, by inserting the heating electrode 11 into the soil 6 and groundwater 7 medium, the targeted transmission of current between the electrodes can be controlled using a step modulation technique, utilizing the electrical resistance characteristics of the soil 6 and groundwater 7 to heat the contaminated soil 6 and groundwater 7 at different depths to 50 ℃ to 70 ℃. The oxidizing agent injection device 2 is configured with the oxidizing agent and accurately delivers the oxidizing agent to the target contaminated area. By utilizing the sensors for various parameters in the intelligent monitoring and control device 3, the heating power of the low-temperature heating device and the injection flow of the oxidizing agent injection device 2 can be accurately regulated and controlled in real time according to various parameters, and energy conservation and consumption reduction are effectively realized. For example, after the soil 6 and groundwater 7 are monitored to be heated to 50 ℃, the heating power of the heating motor is reduced.
In the above embodiment, preferably, the in-situ low-temperature enhanced chemical oxidation remediation method for the organic contaminated site further includes:
arranging multifunctional wells in an organic pollution site in advance; in the multifunctional well are arranged a heating electrode 11, a medicament delivery line 22 for oxidizing medicaments, a sensor for real-time monitoring of parameters of the organic contaminated site and an extraction line 42 for extracting gas and water.
Through the setting of multi-functional well, optimized heating well, extraction well, moisturizing well structure, "three well unifications", utilize electric current to add heat-conduction and eliminate the temperature difference, the homogeneity of stratum heating is showing and is improving.
In the above embodiment, preferably, the generated gas and water are extracted while injecting the oxidizing agent into the organic contaminated site to promote diffusion of the oxidizing agent within the organic contaminated site using a pressure difference generated by the extraction process.
According to the in-situ low-temperature reinforced chemical oxidation remediation method for the organic contaminated site disclosed in the above embodiment, the remediation method is specifically described by the following specific examples.
Example 1
In this example, a remediated organically contaminated site was selected and site survey results indicated: the pollutant medium is mainly underground water, the pollutant is mainly petroleum hydrocarbon, the total concentration of the petroleum hydrocarbon in the underground water is 80-500 mg/L, and the pollution depth is 7 meters underground.
As shown in fig. 3, the in-situ low-temperature enhanced chemical oxidation remediation system for an organic contaminated site provided in this embodiment is implemented by the following method:
(1) measuring and setting out in an area with a pollution range of 20 m multiplied by 20 m, determining the well point positions of a heating well, an injection well, an extraction well and a monitoring well, and arranging 30 multifunctional wells with the well depth of 7.5m, the well spacing of 5m and 12 monitoring wells.
(2) The construction of a multifunctional well and a monitoring well is carried out by using a drilling machine, a heating electrode 11, an extraction pipeline 42 and a medicament conveying pipeline 22 are respectively distributed in the multifunctional well, and sensors such as temperature, pH, conductivity, water content, oxidation-reduction potential and the like are respectively distributed in the monitoring well.
(3) Laying extraction and injection aboveground pipelines, and installing and debugging an in-situ electric heating device, an in-situ injection device, an extraction device, an intelligent monitoring and control device and a tail gas/wastewater treatment device.
(4) Controlling the electric power output heating rate to be 1-2 ℃/d, injecting a sodium persulfate solution through an in-situ injection device after the heating site temperature reaches 55 +/-5 ℃, wherein the mass concentration of the sodium persulfate solution is 10%, controlling the single-well injection pressure to be 0.2-0.4 MPa, and controlling the injection flow to be 0-3 m for cultivation/h; continuously heating to keep the temperature of the field at 55 +/-5 ℃; the volatile organic gas and the polluted underground water are extracted by the extraction device to form a hydraulic gradient, so that the migration and diffusion of the oxidizing agent in the underground are promoted.
(5) Monitoring the change of the concentration of the pollutants and the change of temperature, pH, conductivity, water content and oxidation-reduction potential for a long time, automatically regulating and controlling the power output of the heating device and the medicament injection flow of the in-situ injection device by combining with an intelligent control platform of feedback parameters, and stopping the operation of the device after the concentration of the pollutants is reduced to be below a target value.
(6) Organic pollution gas, waste water, generated construction waste water and the like extracted during the operation are led into a tail gas/waste water treatment device for centralized treatment.
The detection result shows that after the organic pollution site runs for 4 months, the total petroleum hydrocarbon concentration in the underground water is reduced from 483mg/L to below 2mg/L, the removal efficiency reaches more than 99 percent, and the petroleum hydrocarbon concentration in the underground water does not rebound; compared with other similar traditional chemical oxidation areas, after the operation for 4 months, the efficiency of removing the pollutant concentration in the underground water is about 70%, and the obvious sign of concentration rebound exists. Therefore, the implementation of the invention can greatly improve the remediation efficiency and reduce the environmental risk of underground water.
Example 2
In this example, a remediated organically contaminated site was selected and site survey results indicated: the pollutant medium mainly comprises soil and underground water, the pollutant mainly comprises chlorinated aromatic hydrocarbon, polycyclic aromatic hydrocarbon and benzene series, the total concentration of the pollutant in the soil exceeds 40 times, the pollution depth is 8 m underground, and the pollution has larger environmental risk.
As shown in fig. 3, the in-situ low-temperature enhanced chemical oxidation remediation system for an organic contaminated site provided in this embodiment is implemented by the following method:
firstly, measuring and setting out in an area with a pollution range of 10 meters multiplied by 10 meters, determining well point positions of a heating well, an injection well, an extraction well and a monitoring well, and arranging 8 multifunctional wells with the well depth of 8.5m, the well spacing of 5m and 4 monitoring wells.
Secondly, a drilling machine is used for building the multifunctional well and the monitoring well, the heating electrode 11, the extraction pipeline 42 and the medicament conveying pipeline 22 are respectively distributed in the multifunctional well, and sensors such as temperature, pH, conductivity, moisture content, oxidation-reduction potential and the like are respectively distributed in the monitoring well.
Laying extraction and injection ground pipeline, installing and debugging in-situ electric heating device, in-situ injection device, extraction device, intelligent monitoring and controlling device and tail gas/waste water treatment device.
Controlling the electric power output heating rate to be 1-2 ℃/d, injecting a sodium persulfate solution through an in-situ injection device after the heating site temperature reaches 60 +/-5 ℃, wherein the mass concentration of the sodium persulfate solution is 15%, controlling the single-well injection pressure to be 0.3-0.5 Mpa and the injection flow to be 0-3 m for cultivation/h; continuously heating to keep the temperature of the field at 60 +/-5 ℃; the volatile organic gas and the polluted underground water are extracted by the extraction device to form a hydraulic gradient, so that the migration and diffusion of the oxidizing agent in the underground are promoted.
Monitoring the change of the concentration of the pollutants and the change of temperature, pH, conductivity, water content and oxidation-reduction potential for a long time, automatically regulating and controlling the power output of the heating device and the medicament injection flow of the in-situ injection device by combining with a feedback parameter intelligent control platform, and stopping the operation of the device after the concentration of the pollutants is reduced to be below a target value.
And sixthly, introducing the organic pollution gas, the wastewater and the generated construction wastewater pumped out during the operation period into a tail gas/wastewater treatment device for centralized treatment.
In the same contaminated area, in order to create a control effect, the application of the traditional chemical oxidation technique was carried out by the following method:
firstly, measuring and setting out in an area with a pollution range of 10 meters multiplied by 10 meters, determining well point positions of an injection well and a monitoring well, and arranging 8 injection wells with the well depth of 8.5m, the well spacing of 5m and 4 monitoring wells.
Secondly, a drilling machine is used for constructing an injection well and a monitoring well, a medicament conveying pipeline is arranged in the injection well, and sensors such as pH, conductivity, moisture content, oxidation-reduction potential and the like are respectively arranged in the monitoring well.
Injecting a sodium persulfate solution through the in-situ injection device, wherein the mass concentration of the sodium persulfate solution is 15%, controlling the injection pressure of a single well to be 0.3-0.5 Mpa, controlling the injection flow to be 0-3 m/h, and keeping the injection frequency, the injection amount and the monitoring frequency of the oxidation medicament consistent with the in-situ low-temperature reinforced chemical oxidation repair system.
Fourthly, monitoring the concentration change and the pH, the conductivity, the water content and the oxidation-reduction potential change of pollutants for a long time, and leading construction wastewater and the like generated during the operation period into a tail gas/wastewater treatment device for centralized treatment.
The detection result shows that after the organic pollution field runs for 4 months, the pollutant removal efficiency reaches over 95 percent, and the pollutant removal rate is only 62 percent compared with the traditional chemical oxidation technology. Therefore, the implementation of the invention can greatly improve the remediation efficiency and reduce the environmental risk of soil and underground water.
In the repairing process, the in-situ electric heating technology is combined with the chemical oxidation technology, the sodium persulfate is activated by heating to the low temperature of about 50 ℃, the activity and mass transfer of the oxidant are improved, and the generated OH and SO4—The oxidizing free radicals can oxidize petroleum hydrocarbon into low-toxicity or non-toxic substances, so that the ecological environment risk of a site is reduced; in addition, the low temperature condition of about 50 ℃ improves the desorption capacity of the petroleum hydrocarbon from the soil particles, and simultaneously improves the solubility of the petroleum hydrocarbon in underground water, thereby accelerating the contact reaction rate of the sodium persulfate and the petroleum hydrocarbon and greatly improving the oxidative degradation efficiency.
Compared with a restoration method for restoring an organic polluted site by simply utilizing chemical oxidation or utilizing an in-situ current heating desorption technology, the restoration efficiency of the coupling strengthening restoration technology method is obviously improved, the consumption of the oxidant can be reduced by more than 30% compared with the traditional oxidation technology, and the restoration energy consumption is reduced by more than 50% compared with the traditional thermal restoration technology.
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. An in-situ low-temperature reinforced chemical oxidation remediation system for an organic contaminated site is characterized by comprising: the system comprises a low-temperature heating device, an oxidizing agent injection device, an intelligent monitoring and controlling device, a gas-water extraction device and a tail gas and wastewater treatment device;
the low-temperature heating device comprises heating electrodes which are distributed and inserted into soil and underground water in an organic pollution site so as to heat the soil and the underground water to 50-70 ℃;
the oxidizing agent injection device comprises a dispensing unit and a conveying unit, wherein the dispensing unit is used for preparing an oxidizing agent, and the conveying unit is used for conveying the oxidizing agent prepared by the dispensing unit to soil and underground water in the organic pollution site;
the intelligent monitoring and control device comprises a temperature monitoring sensor, a pH monitoring sensor, a water content monitoring sensor, a conductivity monitoring sensor and an oxidation-reduction potential monitoring sensor, and the sensors of the intelligent monitoring and control device are respectively distributed in soil and underground water of the organic pollution site;
the gas-water extraction device comprises an extraction device and an extraction pipeline, and the extraction device extracts gas or water generated in the repair process in the organic pollution site to the tail gas and wastewater treatment device through the extraction pipeline;
the tail gas and wastewater treatment device is used for carrying out centralized treatment on gas and wastewater generated in the repair process.
2. The in-situ low-temperature reinforced chemical oxidation remediation system for the organic contaminated site as claimed in claim 1, wherein a multifunctional well is formed in the organic contaminated site, the heating electrode, the conveying unit, the sensor of the intelligent monitoring and control device and the extraction pipeline are all arranged in the multifunctional well, and the depth of the multifunctional well extends to a contaminated depth area of the organic contaminated site.
3. The in-situ low-temperature-enhanced chemical oxidation remediation system for the organic contaminated site according to claim 2, wherein the low-temperature heating device further comprises a surface sealing layer, the surface sealing layer covers the organic contaminated site, the thickness of the surface sealing layer is 10-100 cm, the surface sealing layer extends 2-3 m to the outer side of the edge of the multifunctional well, and therefore the step voltage in the remediation area is smaller than 15V.
4. The in-situ low-temperature enhanced chemical oxidation remediation system for the organic contaminated site according to claim 1, wherein the oxidizing agent injection device further comprises a medicine storage unit, and after the medicine dispensing unit dispenses the solid oxidizing agent into a solution with a preset concentration or dilutes the liquid oxidizing agent into a solution with a preset concentration, the medicine storage unit stores the oxidizing agent obtained by the medicine dispensing unit;
the delivery unit comprises a medicament delivery power device and a medicament delivery pipeline, the medicament delivery power device is a diaphragm pump or a plunger pump, and the oxidation medicament stored in the medicament storage unit is delivered to soil and underground water at a specified position in the organic polluted site through the medicament delivery pipeline under the driving of the medicament delivery power device.
5. The in-situ low-temperature enhanced chemical oxidation remediation system for the organic contaminated site as claimed in claim 1, wherein the extraction device comprises a water pumping device and an air pumping device, the extraction pipeline comprises a water pumping pipeline and an air pumping pipeline, the water pumping device pumps the wastewater in the remediation process through the water pumping pipeline and transmits the wastewater to the tail gas and wastewater treatment device, and the air pumping device pumps the gas in the remediation process through the air pumping pipeline and transmits the gas to the tail gas and wastewater treatment device.
6. The in-situ low-temperature enhanced chemical oxidation remediation system for the organic contaminated site as claimed in claim 3, wherein the low-temperature heating device further comprises a power distribution device, the power distribution device is composed of a plurality of independent single-phase transformers and a control cabinet, and is used for automatically modulating the power frequency alternating current output in three phases and in a single phase in a grading manner;
the power distribution device is respectively connected with the heating electrodes through control cables.
7. The in-situ low-temperature-enhanced chemical oxidation remediation system for the organic contaminated site as claimed in any one of claims 1 to 6, further comprising a control device, wherein the control device is respectively connected with the low-temperature heating device, the oxidizing agent injection device, the intelligent monitoring and control device and the gas-water extraction device;
the control device adjusts the heating power of the low-temperature heating device, adjusts the injection flow of the oxidizing agent injection device and controls the extraction flow and the start and stop of the gas-water extraction device according to the monitoring data of the intelligent monitoring control device.
8. An in-situ low-temperature enhanced chemical oxidation remediation method for an organic contaminated site, which is applied to the in-situ low-temperature enhanced chemical oxidation remediation system for the organic contaminated site, according to any one of claims 1 to 7, and comprises the following steps:
heating the soil and the underground water in the organic pollution site to 50-70 ℃ by a heating electrode;
injecting an oxidizing agent into soil and underground water of the organic contaminated site;
monitoring the temperature, the pH value, the conductivity, the water content and the oxidation-reduction potential parameters of the organic pollution site in real time, and adjusting the power of the heating electrode and the injection flow of the oxidizing agent according to the real-time monitoring parameters in a feedback manner;
and extracting gas and water generated in the organic pollution site repairing process to a tail gas and wastewater treatment device until the organic pollutants in the organic pollution site reach a safe target value.
9. The in-situ low-temperature enhanced chemical oxidation remediation method for the organic contaminated site as recited in claim 8, further comprising:
arranging multifunctional wells in the organic pollution site in advance;
and arranging the heating electrode, a medicament conveying pipeline of the oxidizing medicament, a sensor for monitoring the parameters of the organic pollution site in real time and an extraction pipeline for extracting gas and water in the multifunctional well.
10. The in-situ low-temperature enhanced chemical oxidation remediation method for the organic contaminated site as claimed in claim 8, wherein the generated gas and water are extracted while the oxidizing agent is injected into the organic contaminated site, so as to promote the diffusion of the oxidizing agent in the organic contaminated site by using the pressure difference generated in the extraction process.
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