A kind of DNAPLs contaminated site enhanced multiphase extraction equipment and method

Abstract

The present invention belongs to the field of soil and groundwater treatment of contaminated sites, and discloses a DNAPLs contaminated site enhanced multiphase extraction device and method, which realizes automatic control of the device and improves the treatment effect of DNAPLs contaminated sites. The device includes a control system, an extraction well, an auxiliary well, a pressure gauge, an inflatable airbag pump, an air suction airbag pump, a microbial agent injection pump, an extraction vacuum pump, an online monitoring device including a flow meter and a water level meter, an air compressor and a hot air blower.

Description

Technical Field

[0001] The present invention relates to the field of soil and groundwater treatment at contaminated sites, and in particular to an enhanced multiphase extraction device and method for DNAPLs contaminated sites. Background Art

[0002] Heavy non-aqueous phase liquids (DNAPLs) are insoluble in water and have a higher density than water. They are usually deposited at the bottom of monitoring wells. They have complex migration behaviors and are highly toxic and carcinogenic. The continuous release of heavy non-aqueous phase liquids pollutants harms the environment and has become a major problem in the field of contaminated site remediation.

[0003] In the remediation of contaminated sites, groundwater multiphase extraction technology is a method that uses vacuum extraction to extract soil gas and groundwater from underground contaminated areas to the ground and separate them to control and repair organic pollutants in soil and groundwater. However, due to the heterogeneity of the formation and the complexity of pollutants, this technology may encounter the phenomenon that pollutant concentrations are difficult to further reduce, or even the concentration may rise again, which is the so-called tailing and rebound effect. There are three main reasons for this. First, the formation itself is heterogeneous; second, the complexity of DANPLs pollutants; and third, residual pollutants are not completely removed. In addition, traditional groundwater multiphase extraction facilities mostly rely on manual control, and on-site decisions are mainly based on experience. This leads to low remediation efficiency and a significant increase in time and economic costs, which seriously restricts the need for precise remediation of contaminated sites. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a DNAPLs contaminated site enhanced multiphase extraction device and method, realize automatic control of the equipment, and improve the treatment effect of the DNAPLs contaminated site.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] In the first aspect, the present invention provides an enhanced multiphase extraction device for a DNAPLs contaminated site, including a control system, an extraction well, an auxiliary well, a pressure gauge, an inflatable airbag pump, an air suction airbag pump, a microbial agent injection pump, an extraction vacuum pump, an online monitoring device including a flow meter and a water level gauge, an air compressor and a hot air blower; wherein, the auxiliary well is provided with a microbial agent injection pipe, a first pump air pipe and a first airbag, the wall of the auxiliary well pipe is a first filter layer, the upper part of the auxiliary well pipe is a first sealing layer, and the top of the auxiliary well pipe is provided with a first sealing cover; one end of the first pump air pipe is located in the first airbag, the air inlet of the first pump air pipe passes through the first sealing cover and is located outside the auxiliary well; the inner cavity of the auxiliary well pipe forms a sealed cavity; the extraction well is provided with an extraction pipe, a second pump air pipe and a second airbag, the wall of the extraction well pipe is a second filter layer, the upper part of the extraction well pipe is a second sealing layer, and the top of the extraction well pipe is provided with a first sealing cover; A second sealing cover is provided on the part; one end of the second pump air pipe is located in the second air bag, and the air outlet of the second pump air pipe passes through the second sealing cover and is located outside the extraction well; the inner cavity of the extraction well pipe forms a sealed cavity; the pressure gauge is located outside the extraction well and is used to measure the air pressure in the inner cavity of the extraction well pipe; the control system is respectively connected with the pressure gauge, the inflation air bag pump, the suction air bag pump, the microbial agent injection pump, the air compressor, the hot air blower, the extraction vacuum pump and the online monitoring device; the extraction pipe is connected to the inlet of the extraction vacuum pump, and the outlet of the extraction vacuum pump is connected to the inlet of the online monitoring device; the air outlet of the second pump air pipe is connected to the suction air bag pump; the microbial agent injection pipe is connected to the microbial agent injection pump; the air outlet of the air compressor is connected to the air inlet of the hot air blower, the air outlet of the hot air blower is connected to the air inlet of the inflation air bag pump, and the air outlet of the inflation air bag pump is connected to the air inlet of the first pump air pipe.

[0007] As a preferred example, the air compressor provides an air pressure of 1 to 2.5 MPa and an air flow rate of 20 to 60 L / min; the hot air blower provides an air outlet temperature of 60 to 350°C.

[0008] As a preferred example, the equipment also includes a multiphase separation device, a waste gas treatment device, a waste gas exhaust pipe and a wastewater treatment device; the inlet of the multiphase separation device is connected to the outlet of the online monitoring device, the liquid outlet of the multiphase separation device is connected to the liquid inlet of the wastewater treatment device, the gas outlet of the multiphase separation device is connected to the gas inlet of the waste gas treatment device, and the gas outlet of the waste gas treatment device is connected to the waste gas exhaust pipe.

[0009] As a preferred example, the mesh density of the microbial agent injection tube is 10-25%; the inner tube diameter of the microbial agent injection tube is equal to the inner tube diameter of the extraction tube.

[0010] In a second aspect, the present invention also provides a method for multiphase extraction of DNAPLs contaminated sites, comprising the following steps:

[0011] S1. Arrange extraction wells and auxiliary wells at the contaminated site, where the contaminated site is a DNAPLs contaminated site;

[0012] S2, the control system controls the extraction vacuum pump to run for a period of time T0, and the online monitoring device feeds back the online monitoring data obtained within the time range of T0 to the control system in real time; during this process, the microbial agent injection pump, air compressor, hot air blower, inflation airbag pump and suction airbag pump are not running;

[0013] S3. The control system makes on-site control based on the acquired data to achieve the treatment of underground DNAPLs pollutants.

[0014] As a preferred example, the step S3 specifically includes: if the flow meter in the online monitoring device shows that the flow is zero, and the water level depth shown by the water level meter no longer changes, the control system controls the extraction vacuum pump to stop the extraction operation.

[0015] As a preferred example, the step S3 specifically also includes: after controlling the extraction vacuum pump to stop the extraction operation, the control system simultaneously starts the inflation airbag pump and the suction airbag pump to open up the heterogeneous strata, so that the pollutants flow into the extraction pipe with the groundwater.

[0016] As a preferred example, the step S3 specifically also includes: when the control system controls the inflation airbag pump and the suction airbag pump to turn on, if the pressure gauge shows an upward trend and the water level gauge of the online monitoring device shows a downward trend, the control system controls the extraction vacuum pump to turn on again to perform the extraction operation.

[0017] As a preferred example, the step S3 specifically also includes: while controlling the extraction vacuum pump to start again, and the inflation airbag pump and the suction airbag pump to run, if the online monitoring device shows that the site pollution characteristic index is no longer decreasing or the concentration rebounds and rises, the control system controls the microbial agent injection pump to inject the microbial agent, and the online monitoring device records the changes of the site pollution characteristic index over time.

[0018] As a preferred example, according to the change of the site pollution characteristic index recorded by the online monitoring device over time, the following processing is performed: if the online monitoring device shows that the site pollution characteristic index has reached the remediation target value, the microbial agent injection pump is shut down, and the extraction vacuum pump, the inflation airbag pump and the suction airbag pump are shut down at the same time; if the online monitoring device shows that the site pollution characteristic index first decreases and then stabilizes, but is still greater than the remediation target value, the control system controls the air compressor and the hot air blower to generate heat source air for transmission to the inflation airbag pump until the online monitoring device shows that the site pollution characteristic index has reached the remediation target value, stops the microbial agent injection, and shuts down the extraction vacuum pump, the inflation airbag pump, the suction airbag pump, the air compressor, the hot air blower and the microbial agent injection pump.

[0019] Compared with the prior art, the DNAPLs contaminated site enhanced multiphase extraction equipment and method of the present invention realize automatic control of the equipment and improve the treatment effect of DNAPLs contaminated sites. The equipment includes a control system, an extraction well, an auxiliary well, a pressure gauge, an inflatable airbag pump, an air suction airbag pump, a microbial agent injection pump, an extraction vacuum pump, an online monitoring device containing a flow meter and a water level meter, an air compressor and a hot air blower. The equipment realizes intelligent control by integrating characteristic indicators online monitoring through an online monitoring device, and controlling the inflatable airbag pump, the air suction airbag pump, the microbial agent injection pump, the extraction vacuum pump, the air compressor and the hot air blower through the control system. This breaks through the limitations of traditional reliance on on-site experience, effectively avoids unnecessary energy waste, and promotes the development of the repair process in the direction of green, low-carbon and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0021] The figure includes: control system 1, extraction well 2, auxiliary well 3, extraction pipe 4, microbial agent injection pipe 5, first pump air pipe 6, first air bag 7, first sealing layer 8, first filter layer 9, first sealing cover 10, pressure gauge 11, inflation air bag pump 12, suction air bag pump 13, microbial agent injection pump 14, extraction vacuum pump 15, online monitoring device 16, multi-phase separation device 17, exhaust gas treatment device 18, exhaust pipe 19, wastewater treatment device 20, second pump air pipe 21, second air bag 22, second filter layer 23, second sealing layer 24, second sealing cover 25, air compressor 26, and hot air blower 27. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0023] The technical solution of the present invention is applicable to heterogeneous strata. A heterogeneous strata refers to a strata in which the seepage coefficient of each point in the strata varies with the spatial coordinates, and a homogeneous strata refers to a strata in which each point in the strata has the same seepage coefficient.

[0024] like Figure 1As shown, an enhanced multiphase extraction device for DNAPLs contaminated sites according to an embodiment of the present invention includes a control system 1, an extraction well 2, an auxiliary well 3, a pressure gauge 11, an air-filled airbag pump 12, an air-suction airbag pump 13, a microbial agent injection pump 14, an extraction vacuum pump 15, an online monitoring device 16 including a flow meter and a water level meter, an air compressor 26, and a hot air blower 27. Among them, the flow meter is used to detect the flow of water and air flow extracted by the extraction pipe 4. The water level meter is used to detect the depth of the water level in the extraction pipe 4. The water level depth refers to the distance from the surface to the groundwater level, so a decrease in the water level depth indicates that water has entered the extraction system. A microbial agent injection pipe 5, a first pump air pipe 6 and a first air bag 7 are provided in the auxiliary well 3. The wall of the auxiliary well 3 well pipe is a first filter layer 9, the upper part of the auxiliary well 3 well pipe is a first sealing layer 8, and the top of the auxiliary well 3 well pipe is provided with a first sealing cover 10; one end of the first pump air pipe 6 is located in the first air bag 7, and the air inlet of the first pump air pipe 6 passes through the first sealing cover 10 and is located outside the auxiliary well 3. The inner cavity of the well pipe of the auxiliary well 3 forms a sealed cavity. Due to the provision of the first sealing layer 8 and the first sealing cover 10, the inner cavity of the well pipe of the auxiliary well 3 forms a sealed cavity relative to the outside. The extraction well 2 is provided with an extraction pipe 4, a second pump air pipe 21 and a second air bag 22. The wall of the well pipe of the extraction well 2 is a second filter layer 23, the upper part of the well pipe of the extraction well 2 is a second sealing layer 24, and the top of the well pipe of the extraction well 2 is provided with a second sealing cover 25. One end of the second pump air pipe 21 is located in the second air bag 22, and the air outlet of the second pump air pipe 21 passes through the second sealing cover 25 and is located outside the extraction well 2; the inner cavity of the well pipe of the extraction well 2 forms a sealed cavity. Due to the provision of the second sealing layer 24 and the second sealing cover 25, the inner cavity of the well pipe of the extraction well 2 forms a sealed cavity relative to the outside. The pressure gauge 11 is located outside the extraction well 2 and is used to measure the air pressure in the inner cavity of the well pipe of the extraction well 2. The control system 1 is respectively connected to the pressure gauge 11, the inflation air bag pump 12, the suction air bag pump 13, the microbial agent injection pump 14, the air compressor 26, the hot air blower 27, the extraction vacuum pump 15 and the online monitoring device 16. The extraction pipe 4 is connected to the inlet of the extraction vacuum pump 15, and the outlet of the extraction vacuum pump 15 is connected to the inlet of the online monitoring device 16; the air outlet of the second pump air pipe 21 is connected to the suction air bag pump 13. The microbial agent injection pipe 5 is connected to the microbial agent injection pump 14, the air outlet of the air compressor 26 is connected to the air inlet of the hot air blower 27, the air outlet of the hot air blower 27 is connected to the air inlet of the air bag pump 12, and the air outlet of the air bag pump 12 is connected to the air inlet of the first pump air pipe 6. The parameters monitored by the online monitoring device 16 are related to the characteristic indicators of the contaminated site, including at least pH, flow rate, and characteristic indicators.

[0025] In the device of the above embodiment, the control system 1 is connected to the pressure gauge 11, the inflation airbag pump 12, the suction airbag pump 13, the microbial agent injection pump 14, the air compressor 26, the hot air blower 27, the extraction vacuum pump 15 and the online monitoring device 16 respectively. The control system 1 controls the inflation airbag pump 12, the suction airbag pump 13, the microbial agent injection pump 14, the extraction vacuum pump 15, the air compressor 26, and the hot air blower 27 to start or stop working according to the information transmitted by the online monitoring device 16 and the pressure gauge 11, and realizes the control of the entire device on site, reduces human intervention, and improves the treatment effect of the contaminated site. When the data transmitted by the online monitoring device 16 shows that there is no DNAPLs pollutant in the material extracted by the extraction pipe 4, the control system 1 controls to turn off the extraction vacuum pump 15. After turning off the extraction vacuum pump 15, the control system 1 simultaneously turns on the inflation airbag pump 12 and the suction airbag pump 13, so that the DNAPLs pollutants flow into the extraction pipe 4 with the groundwater flow. If the pressure gauge 11 shows that the air pressure in the inner cavity of the extraction well 2 is rising, and the water level gauge of the online monitoring device 16 shows a downward trend, the control system 1 controls the extraction vacuum pump 15 to start again and perform the extraction operation. If the online monitoring device 16 shows that the site pollution characteristic index is no longer decreasing or the concentration rebounds and rises, the control system 1 controls the microbial agent injection pump 14 to inject microbial agents, and the microbial agents react with the site pollutant DNAPLs until the online monitoring device 16 shows that the site pollution characteristic index reaches the remediation target value, stops injecting microbial agents, and shuts down the microbial agent injection pump 14, the extraction vacuum pump 15, the inflation airbag pump 12 and the suction airbag pump 13. If the online monitoring device 16 shows that the site pollution characteristic index first decreases and then stabilizes, but is still greater than the repair target value, the control system 1 controls the air compressor 26 and the hot air blower 27 to generate heat source air for transmission to the inflation airbag pump 12 until the online monitoring device 16 shows that the site pollution characteristic index reaches the repair target value, stops the microbial agent injection, and shuts down the microbial agent injection pump 14, the extraction vacuum pump 15, the inflation airbag pump 12, the suction airbag pump 13, the air compressor 26 and the hot air blower 27.

[0026] In the above embodiment, the control system 1 controls the start or stop of the extraction vacuum pump 15 according to the real-time data transmitted by the online monitoring device 16, controls the start and stop of the inflation airbag pump 12, the suction airbag pump 13, the air compressor 26 and the hot air blower 27, as well as the inflation and suction levels, the input air volume and the air heating level, and controls the start and stop and injection volume of the microbial inoculant injection pump 14.

[0027] As a preferred example, the air pressure provided by the air compressor 26 is 1-2.5Mpa, and the air flow rate is 20-60L / min. The working parameters of the air compressor 26 are intelligently controlled by the control system 1 according to the geological conditions. The outlet air temperature provided by the hot air blower 27 is 60-350°C. The hot air blower 27 heats the air generated by the air compressor 26. According to the characteristics of DNAPLs pollutants in the contaminated site and other comprehensive factors, the control system 1 intelligently controls the outlet air temperature of the hot air blower 27.

[0028] To achieve multiphase separation, as a preferred example, the device further includes a multiphase separation device 17, a waste gas treatment device 18, a waste gas exhaust pipe 19 and a wastewater treatment device 20. The inlet of the multiphase separation device 17 is connected to the outlet of the online monitoring device 16, the liquid outlet of the multiphase separation device 17 is connected to the liquid inlet of the wastewater treatment device 20, the gas outlet of the multiphase separation device 17 is connected to the gas inlet of the waste gas treatment device 18, and the gas outlet of the waste gas treatment device 18 is connected to the waste gas exhaust pipe 19. The mixture extracted from the extraction pipe 4 flows into the multiphase separation device 17 from the online monitoring device 16 after being detected by the online monitoring device 16. The mixture extracted from the extraction pipe 4 contains liquid and gas. Liquid is such as groundwater. Gas is such as volatile organic matter. The mixture is separated into liquid and gas by the multiphase separation device 17. The liquid flows into the wastewater treatment device 20 from the liquid outlet for treatment. The gas flows into the waste gas treatment device 18 from the gas outlet for treatment, and finally discharged from the waste gas exhaust pipe 19.

[0029] As a preferred example, the mesh density of the microbial agent injection pipe 5 is 10-25%. The mesh density of the microbial agent injection pipe 5 is set to 10-25% based on comprehensive factors such as geological and geotechnical conditions and microbial agent characteristics. Preferably, the inner diameter of the microbial agent injection pipe 5 is equal to the inner diameter of the extraction pipe 4. This can ensure the consistency of fluid flow, reduce the change in fluid velocity caused by changes in pipe diameter, thereby reducing the risk of blockage and improving extraction efficiency.

[0030] The embodiment of the present invention also provides a method for multiphase extraction of DNAPLs contaminated sites using the above-mentioned device, comprising the following steps:

[0031] S1. An extraction well 2 and an auxiliary well 3 are arranged at the contaminated site. The contaminated site is a DNAPLs contaminated site. The contaminated site is a heterogeneous stratum.

[0032] S2, the control system 1 controls the extraction vacuum pump 15 to run for a period of time T0, and the online monitoring device 16 feeds back the online monitoring data obtained within the time range of T0 to the control system 1 in real time. During this process, the microbial agent injection pump 14, the air compressor 26, the hot air blower 27, the inflation airbag pump 12 and the suction airbag pump 13 are not running. The wall of the well pipe of the extraction well 2 is the second filter layer 23. Groundwater flows into the extraction well 2 from the second filter layer 23. DNAPLs pollutants in the area around the extraction well 2 flow into the extraction well 2 with the groundwater. When the extraction vacuum pump 15 is running, the groundwater flow and airflow containing DNAPLs pollutants in the extraction well 2 are extracted to the online monitoring device 16 through the extraction pipe 4 for detection. The concentration of characteristic pollutants in the online monitoring device 16 shows a downward trend, the flow meter shows the change trend of water flow and air flow, and the water level meter shows the change trend of the water level depth in the extraction pipe.

[0033] S3, the control system 1 makes on-site control based on the acquired data to achieve the treatment of underground DNAPLs pollutants. The step S3 specifically includes:

[0034] Step S31: If the flow meter in the online monitoring device 16 shows that the flow rate is zero, and the water level depth shown by the water level meter does not change, it means that no DNAPLs pollutants are extracted from the extraction pipe 4. In order to avoid energy consumption and device loss, the control system 1 controls the extraction vacuum pump 15 to stop the extraction operation.

[0035] In step S31, no DNAPLs pollutants are extracted from the extraction tube 4 because the DNAPLs pollutants within the extraction influence range under the heterogeneous stratum have been extracted and the remaining residual DNAPLs pollutants cannot be extracted.

[0036] In step S32, after controlling the extraction vacuum pump 15 to stop the extraction operation, the control system 1 simultaneously starts the inflation airbag pump 12 and the suction airbag pump 13 to open up the heterogeneous strata, so that the DNAPLs pollutants flow into the extraction pipe 4 along with the groundwater.

[0037] Step S32 is set to break through the bottleneck problem of extraction behavior caused by heterogeneous formations. The inflation airbag pump 12 and the suction airbag pump 13 are turned on at the same time. The inflation airbag pump 12 inflates the first airbag 7 through the first pump air pipe 6. Since the inner cavity of the auxiliary well 3 well pipe forms a sealed cavity, the first airbag 7 expands and the inner cavity of the auxiliary well 3 well pipe forms a high pressure. The suction airbag pump 13 inhales air from the second airbag 22 through the second pump air pipe 21. Since the inner cavity of the extraction well 2 well pipe forms a sealed cavity, the second airbag 22 shrinks and the inner cavity of the extraction well 2 well pipe forms a low pressure. Under the pressure difference, the gas in the auxiliary well 3 passes through the first filter layer 9, the heterogeneous formation, and the second filter layer 22 in turn, and flows to the extraction well 2. During the gas flow process, the heterogeneous formation is opened up, allowing pollutants to flow into the extraction pipe 4 with the groundwater flow. Under the inflation effect of the first pump air pipe 6 and the first air bag 7, and the suction effect of the second pump air pipe 21 and the second air bag 22, the groundwater flow generates a pressure difference, thereby expanding the extraction influence range.

[0038] Step S32 breaks through the limitations of heterogeneous formations and uses an airbag pump system through an inflation and suction method. On the one hand, under the condition of enhanced air pressure, it overcomes the problem of inefficient pollution treatment capacity caused by heterogeneous formations and achieves the homogenization of the formation as much as possible. On the other hand, under the premise of opening up the formation, pollutants can enter the extraction well. In heterogeneous formations, groundwater only flows on the dominant flow path, and there is a "dead path" phenomenon. Pollutants cannot flow with the water in the "dead path". Under homogeneous formation conditions, groundwater can flow in all paths.

[0039] In step S33, when the control system 1 controls the inflation airbag pump 12 and the suction airbag pump 13 to start, if the pressure gauge 11 shows an upward trend and the water level gauge of the online monitoring device 16 shows a downward trend, the control system 1 controls the extraction vacuum pump 15 to start again to perform the extraction operation.

[0040] In step S33, the air pressure in the extraction well 2 detected by the pressure gauge 11 shows an increase, indicating that gas has entered the extraction well 2 under the pressure difference between the first airbag 7 and the second airbag 22. The water level depth shown by the water level gauge of the online monitoring device 16 shows a downward trend, indicating that groundwater has entered the extraction system. Therefore, when the air pressure in the well pipe cavity of the extraction well 2 shown by the pressure gauge 11 shows an increase, and the water level depth shown by the water level gauge of the online monitoring device 16 shows a downward trend, it means that fluid has entered the extraction pipe 4. At this time, the extraction vacuum pump 15 is turned on again to perform the extraction operation.

[0041] Step S34: While controlling the extraction vacuum pump 15 to start again, and the inflation airbag pump 12 and the suction airbag pump 13 to operate, if the online monitoring device 16 shows that the site pollution characteristic index is no longer decreasing or the concentration rebounds and rises, the control system 1 controls the microbial agent injection pump 14 to inject the microbial agent, and the online monitoring device 16 records the changes of the site pollution characteristic index over time. Specifically, according to the changes of the site pollution characteristic index over time recorded by the online monitoring device 16, the following processing is performed:

[0042] If the online monitoring device 16 shows that the site pollution characteristic index reaches the remediation target value, the microbial agent injection pump 14 is shut down, and the extraction vacuum pump 15, the inflation airbag pump 12 and the suction airbag pump 13 are shut down at the same time;

[0043] If the online monitoring device 16 shows that the site pollution characteristic index first decreases and then stabilizes, but is still greater than the repair target value, the control system 1 controls the air compressor 26 and the hot air blower 27 to generate heat source air for transmission to the inflation airbag pump 12 until the online monitoring device 16 shows that the site pollution characteristic index reaches the repair target value, stops the microbial agent injection, and shuts down the extraction vacuum pump 15, the inflation airbag pump 12, the suction airbag pump 13, the air compressor 26, the hot air blower 27 and the microbial agent injection pump 14.

[0044] In step S34, the online monitoring device 16 shows that the site pollution characteristic index no longer decreases or there is a trend of concentration rebound. This means that even if the inflation airbag pump 12 and the suction airbag pump 13 are turned on, there is still the possibility of residual pollution. At this time, the control system 1 controls the microbial agent injection pump 14 to inject the medicine. The microbial agent injection pump 14 passes the agent into the auxiliary well 3 through the microbial agent injection pipe 5. Since the pressure in the inner cavity of the well pipe of the auxiliary well 3 is higher than the pressure in the inner cavity of the well pipe of the extraction well 2, the agent flows out from the first filter layer 9 of the auxiliary well 3 and flows to the soil around the auxiliary well 3, reacting with the DNAPLs pollutants in the soil to reduce the residual DNAPLs pollutants. The microbial agent decomposes the DNAPLs pollutants into harmless or low-toxic substances through biodegradation, transformation, etc. When the online monitoring device 16 shows that the site pollution characteristic index reaches the remediation target value, the microbial agent injection operation is stopped, and the extraction vacuum pump 15, the inflation airbag pump 12 and the suction airbag pump 13 are shut down at the same time. This means that groundwater pollutants within the control area of ​​the device have been completely extracted.

[0045] In step S34, if the online monitoring device 16 shows that the site pollution characteristic index first decreases and then stabilizes, but is still greater than the remediation target value, the control system 1 controls the air compressor 26 and the hot air blower 27 to generate heat source air and transmit it to the inflatable airbag pump 12 until the online monitoring device 16 shows that the site pollution characteristic index reaches the remediation target value, stops the microbial agent injection operation, and shuts down the extraction vacuum pump 15, the inflatable airbag pump 12, the suction airbag pump 13, the air compressor 26, the hot air blower 27 and the microbial agent injection pump 14. The online monitoring device 16 shows that the site pollution characteristic index first decreases and then stabilizes, but is still greater than the remediation target value, indicating that there are still residual DNAPLs pollutants in the formation, and the microbial activity is limited without taking any strengthening measures, so a heat source is needed to stimulate the microbial activity. In this process, the air compressor 26 and the hot air blower 27 generate heat source air and transmit it to the inflatable airbag pump 12, and the heat source air flows into the first airbag 7 through the first pump air pipe 6. The heat source air heats the microbial agent on the outside of the first airbag 7. At a suitable temperature, the microbial agent can improve its own degradation reaction activity, thereby improving the pollutant treatment efficiency. At the same time, the heat source air flows out of the auxiliary well 3 and is transferred to the soil and groundwater, which can promote the volatilization of more residual DNAPLs pollutants.

[0046] The equipment of the above embodiment, by controlling the inflation airbag pump 12, the suction airbag pump 13, the air compressor 26 and the hot air blower 27 by the control system 1, intelligently adjusts the expansion degree of the first airbag 7 and the second airbag 22, optimizes the dominant flow path of groundwater, overcomes the problem of formation heterogeneity, ensures that soil and groundwater can achieve more sufficient contact with pollutants, and expands the extraction range. The equipment avoids the tailing and rebound effects caused by heterogeneous formations.

[0047] The equipment of the above-mentioned embodiment intelligently controls the injection time and injection amount of the microbial agent through the microbial agent injection device and control system, further ensuring sufficient reaction between the pollutant DNAPLs and the microbial agent. At the same time, under the action of the heat source air, the activity of the microbial agent can be further stimulated, and the reaction with the DNAPLs pollutants is more thorough, thereby achieving complete removal of residual DNAPLs pollutants and making the repair effect more thorough.

[0048] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above specific embodiments. The above specific embodiments and the description in the specification are only for further illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of the present invention to be protected is defined by the claims and their equivalents.

Claims

1. An enhanced multiphase extraction device for DNAPLs contaminated sites, characterized in that: It comprises a control system (1), an extraction well (2), an auxiliary well (3), a pressure gauge (11), an air-filling airbag pump (12), an air-suction airbag pump (13), a microbial agent injection pump (14), an extraction vacuum pump (15), an online monitoring device (16) including a flow meter and a water level meter, an air compressor (26) and a hot air blower (27); wherein: The auxiliary well (3) is provided with a microbial agent injection pipe (5), a first pump air pipe (6) and a first air bag (7); the wall of the auxiliary well (3) well pipe is a first filter layer (9); the upper part of the auxiliary well (3) well pipe is a first sealing layer (8); the top of the auxiliary well (3) well pipe is provided with a first sealing cover (10); one end of the first pump air pipe (6) is located in the first air bag (7); the air inlet of the first pump air pipe (6) passes through the first sealing cover (10) and is located outside the auxiliary well (3); the inner cavity of the well pipe of the auxiliary well (3) forms a sealed cavity; The extraction well (2) is provided with an extraction pipe (4), a second pump air pipe (21) and a second air bag (22); the wall of the extraction well (2) is a second filter layer (23); the upper part of the extraction well (2) is a second sealing layer (24); the top of the extraction well (2) is provided with a second sealing cover (25); one end of the second pump air pipe (21) is located in the second air bag (22); the air outlet of the second pump air pipe (21) passes through the second sealing cover (25) and is located outside the extraction well (2); the inner cavity of the extraction well (2) forms a sealed cavity; the pressure gauge (11) is located outside the extraction well (2) and is used to measure the air pressure in the inner cavity of the extraction well (2); The control system (1) is respectively connected to a pressure gauge (11), an inflation airbag pump (12), an air suction airbag pump (13), a microbial agent injection pump (14), an air compressor (26), a hot air blower (27), an extraction vacuum pump (15), and an online monitoring device (16); The extraction tube (4) is connected to the inlet of the extraction vacuum pump (15), and the outlet of the extraction vacuum pump (15) is connected to the inlet of the online monitoring device (16); the outlet of the second pump air pipe (21) is connected to the suction airbag pump (13); The microbial agent injection pipe (5) is connected to the microbial agent injection pump (14); the air outlet of the air compressor (26) is connected to the air inlet of the hot air blower (27); the air outlet of the hot air blower (27) is connected to the air inlet of the inflation airbag pump (12); the air outlet of the inflation airbag pump (12) is connected to the air inlet of the first pump air pipe (6); After the extraction vacuum pump (15) is controlled to stop the extraction operation, the control system (1) simultaneously starts the inflation airbag pump (12) and the suction airbag pump (13); the inflation airbag pump (12) inflates the first airbag (7) through the first pump air pipe (6), the first airbag (7) expands, and a high pressure is formed in the inner cavity of the well pipe of the auxiliary well (3); the suction airbag pump (13) sucks air from the second airbag (22) through the second pump air pipe (21), the second airbag (22) contracts, and a low pressure is formed in the inner cavity of the well pipe of the extraction well (2); under the pressure difference, the gas in the auxiliary well (3) passes through the first filter layer (9), the heterogeneous formation, and the second filter layer (23) in sequence, and flows to the extraction well (2); during the gas flow process, the heterogeneous formation is opened up, so that the pollutants flow into the extraction pipe (4) along with the groundwater flow.

2. The device according to claim 1, characterized in that The air compressor (26) provides an air pressure of 1 to 2.5 MPa and an air flow rate of 20 to 60 L / min; the hot air blower (27) provides an air outlet temperature of 60 to 350°C.

3. The device according to claim 1, characterized in that It also includes a multiphase separation device (17), a waste gas treatment device (18), a waste gas exhaust pipe (19) and a waste water treatment device (20); the inlet of the multiphase separation device (17) is connected to the outlet of the online monitoring device (16), the liquid outlet of the multiphase separation device (17) is connected to the liquid inlet of the waste water treatment device (20), the gas outlet of the multiphase separation device (17) is connected to the gas inlet of the waste gas treatment device (18), and the gas outlet of the waste gas treatment device (18) is connected to the waste gas exhaust pipe (19).

4. The device according to claim 1, characterized in that The mesh density of the microbial agent injection tube (5) is 10-25%; the inner tube diameter of the microbial agent injection tube (5) is equal to the inner tube diameter of the extraction tube (4).

5. A method for multiphase extraction of DNAPLs contaminated sites based on the device according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Arranging an extraction well (2) and an auxiliary well (3) at a contaminated site, wherein the contaminated site is a DNAPLs contaminated site; S2, the control system (1) controls the extraction vacuum pump (15) to operate for a period of time T0, and the online monitoring device (16) feeds back the online monitoring data obtained within the time range T0 to the control system (1) in real time; during this process, the microbial agent injection pump (14), the air compressor (26), the hot air blower (27), the inflation airbag pump (12) and the suction airbag pump (13) are all not in operation; S3, control system (1) based on the acquired data, makes on-site control to achieve the treatment of underground DNAPLs pollutants; The step S3 specifically includes: If the flow meter in the online monitoring device (16) shows that the flow rate is zero, and the water level depth shown by the water level meter no longer changes, the control system (1) controls the extraction vacuum pump (15) to stop the extraction operation; After the extraction vacuum pump (15) is controlled to stop the extraction operation, the control system (1) simultaneously starts the inflation airbag pump (12) and the suction airbag pump (13) to open up the heterogeneous strata, so that the pollutants flow into the extraction pipe (4) along with the groundwater flow; When the control system (1) controls the inflation airbag pump (12) and the suction airbag pump (13) to start, if the pressure gauge (11) shows an upward trend and the water level gauge of the online monitoring device (16) shows a downward trend, the control system (1) controls the extraction vacuum pump (15) to start again to perform the extraction operation; While the extraction vacuum pump (15) is controlled to be turned on again, and the inflation airbag pump (12) and the suction airbag pump (13) are running, if the online monitoring device (16) shows that the site pollution characteristic index is no longer decreasing or the concentration rebounds and rises, the control system (1) controls the microbial agent injection pump (14) to inject the microbial agent, and the online monitoring device (16) records the changes in the site pollution characteristic index over time.

6. The method according to claim 5, characterized in that According to the changes in the site pollution characteristic indicators recorded by the online monitoring device (16) over time, the following processing is performed: If the online monitoring device (16) shows that the site pollution characteristic index reaches the remediation target value, the microbial agent injection pump (14) is shut down, and the extraction vacuum pump (15), the inflation airbag pump (12) and the suction airbag pump (13) are shut down at the same time; If the online monitoring device (16) shows that the site pollution characteristic index first decreases and then stabilizes, but is still greater than the remediation target value, the control system (1) controls the air compressor (26) and the hot air blower (27) to generate heat source air for transmission to the inflation airbag pump (12) until the online monitoring device (16) shows that the site pollution characteristic index reaches the remediation target value, stops the microbial agent injection, and shuts down the extraction vacuum pump (15), the inflation airbag pump (12), the suction airbag pump (13), the air compressor (26), the hot air blower (27) and the microbial agent injection pump (14).

Images