JP2006272273A - Soil purification system and soil purification method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soil purification system and soil purification method which enable a rapid removal of contaminants contained in groundwater and gases of contaminants vaporized from soil. <P>SOLUTION: The soil purification system and soil purification method are provided. The soil purification system is provided with a purifying facility 1 having a recovery well 2 drilled on a contaminated zone due to the contaminants to recover the gases vaporized from the contaminants seeping in the recovery well, and the groundwater containing the contaminants leaching out in the recovery well to purify. The soil purification system is provided with a preheater 20 having a plurality of preheating openings 21 drilled within the contaminated zone of the circumference of the recovery well and a heater 3 installed in each of the preheating openings, and preheating the groundwater leaching out in the preheating openings and is characterized in that the heater 3 promotes the leaching out of the groundwater into the recovery well by preheating the groundwater leaching out in the preheating openings. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a soil purification system and a soil purification method.

  Conventionally, when purifying contaminated soil, for example, a well is excavated in a contaminated area contaminated with volatile organic compounds (VOC) such as dichloroethane and trichlorethylene, and the groundwater leached into the well is pumped up. A technique for purifying soil by sucking air under reduced pressure and treating the vaporized VOC gas or VOC contained in groundwater has been disclosed (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 11-10130

  However, the conventional method for remediating contaminated soil that removes pollutants contained in gas pumped from groundwater and soil has a slow groundwater leach rate when the soil in the contaminated area is non-permeable soil such as clay. However, since the amount of pumped water is small, there is a problem that it takes an enormous amount of time to remove contaminants.

  The present invention has been made in view of the above, and provides a soil purification system and a soil purification method that can quickly remove pollutants contained in groundwater and pollutant gases vaporized from soil. With the goal.

  In order to achieve the above object, a soil purification system according to claim 1 of the present invention includes a purification device having a recovery well excavated in a contaminated area due to a contaminant, and the contaminant leaking into the recovery well is A soil purification system for recovering and purifying groundwater containing vaporized gas and the contaminants leached into the recovery well, wherein a plurality of preheating holes excavated in the contaminated area around the recovery well, and the respective preheating A preheating device installed in the hole and preheating the groundwater leached into the preheating hole, and the preheating means preheats the groundwater leached into the preheating hole, whereby the recovery well It is characterized by promoting leaching.

  The soil purification system according to claim 2 is characterized in that, in the above-described invention, the purification device includes a heating unit provided in the recovery well and heating groundwater leached into the recovery well.

  Moreover, the soil purification system which concerns on Claim 3 WHEREIN: In said invention, the said preheating apparatus WHEREIN: The said preheating means by the said preheating means based on the detected water temperature and the water temperature detection means which detects the temperature of the said groundwater in each preheating hole Preheating temperature control means for controlling the preheating temperature of groundwater.

  Moreover, the soil purification system which concerns on Claim 4 of this invention is a heating tank which heats water and uses the water injection well excavated in the flow direction upstream of the said groundwater of the said recovery well in the said invention. And a water injection device for injecting the heated water into the water injection well.

  The soil purification system according to claim 5 is the above-described invention, wherein the purification device includes a water level detection means for detecting a level of the groundwater that has leached into the recovery well, and the contaminant leaked into the recovery well. Concentration detecting means for detecting the concentration of gas vaporized, and recovery control means for controlling recovery of the groundwater containing the gas and the contaminant based on the detected groundwater level and the gas concentration. It is characterized by having.

  Moreover, the soil purification system which concerns on Claim 6 WHEREIN: In said invention, the said purification apparatus is the temperature detection means which detects the temperature of the groundwater leached to the said recovery well, and the said heating means is based on the detected water temperature. Temperature control means for controlling the heating temperature of the groundwater.

  Moreover, the soil purification system which concerns on Claim 7 of this invention is a water level detection means which detects the water level of the heating water poured into the said water injection well, and the detected water level of the heating water in the said water injection apparatus in said invention. And a water injection control means for controlling the operation of the heating tank or the water injection means.

  In order to achieve the above object, a soil remediation method according to claim 8 of the present invention is a method for leaching the vaporized contaminants leaking into a recovery well provided in a polluted area and the recovery well. A soil purification method for recovering and purifying the groundwater containing the pollutant, the step of preheating the groundwater present in the contaminated area around the recovery well and promoting the leaching of the groundwater into the recovery well; Recovering and purifying the groundwater containing the pollutant that has been flowed down by preheated groundwater and leaked into the recovery well, and the pollutant that has leached into the recovery well. .

  The soil purification method according to claim 9 of the present invention is characterized in that, in the above invention, the soil purification method further includes a leachate heating step of heating the groundwater leached into the recovery well.

  The soil purification method according to claim 10 of the present invention is characterized in that, in the above invention, the soil purification method further includes a water injection step of injecting heated water to the upstream side of the recovery well in the flow direction of the groundwater. To do.

  Since the soil purification system and the soil purification method of the present invention preheat the groundwater in a plurality of preheating holes provided in the contaminated area around the recovery well to lower the kinematic viscosity coefficient of the groundwater and increase the soil permeability coefficient, Preheated groundwater can easily flow through the soil, and leaching into the recovery well is promoted. Therefore, the soil purification system and the soil purification method of the present invention can quickly remove and purify pollutants contained in groundwater and pollutant gases evaporated from the soil from the soil in the contaminated area. When applied to poorly permeable soils, contaminants can be quickly removed and purified. In the soil purification system and the soil purification method of the present invention, the pollutant gas polluted from the soil in the contaminated area and the pollutant vaporized from the soil are flowed down by the preheated ground water and collected in the recovery well. For this reason, the soil purification system and the soil purification method of the present invention can be applied over a wide range in which the concentration of contaminants in the groundwater is from a low concentration to a high concentration exceeding 10,000 times the environmental standard. The present invention can be applied not only to the purification of contaminated areas that are locally contaminated at high concentrations, but also to the purification of contaminated areas of low-concentration contaminated areas over a wide area where pollutants have diffused.

  Exemplary embodiments of a soil purification system and a soil purification method according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing a soil purification system using a soil purification method according to the present invention. FIG. 2 is a plan view showing an example of the arrangement of recovery wells, preheating holes and water injection wells that constitute the soil purification system of FIG. FIG. 3 is a cross-sectional view taken along the line CC of FIG.

  As shown in FIG. 1, the soil purification system is installed in a contaminated area Apo contaminated with a pollutant, for example, a volatile organic compound (VOC), and includes a purification device 1, a preheating device 20, and a water injection device 30. .

  The purification device 1 includes a recovery well 2, a steam separator 8, an aeration processing device 9, a recovery pump 10, a concentration sensor 11, a gas processing device 12, a recovery control device 13, and a temperature control device 14.

  The recovery well 2 is a well that is provided in the contaminated area Apo and collects the gas containing the VOC gas vaporized by the VOC and the groundwater containing VOC. As shown in FIG. 2, according to the horizontal extent of the contaminated area Apo. An appropriate number is drilled. As shown in FIG. 1, the recovery well 2 is formed by embedding a cylindrical body having a slit 2a at the bottom and a lid 2b at the top. The recovery well 2 is provided with a heater 3 for heating the groundwater leached from the surrounding soil through the slit 2a, a thermocouple 4 for detecting the temperature of the groundwater, and a water level meter 5 for detecting the water level of the groundwater.

  At this time, as shown in FIG. 3, the recovery well 2 has a depth from the unsaturated layer Lu on the surface of the contaminated area Apo to at least the boundary between the water permeable layer Lp and the water impermeable layer Af. , In the position indicated by the symbol W in the figure. Further, the recovery well 2 is connected to the steam separator 8 through the suction pipe 6 and the pumping pipe 7. Each of the steam separators 8 is connected to the aeration treatment device 9 and also connected to the gas treatment device 12 via the recovery pump 10 to purify the gas containing the separated VOC gas by the gas treatment device 12 to be groundwater. The contained VOC is purified by the aeration processing device 9.

  Here, each of the suction pipe 6 and the pumping pipe 7 is provided with a valve (not shown), and by switching the opening and closing of the valve, the suction of the gas containing the VOC gas and the suction of the groundwater containing the VOC by the recovery pump 10 are individually performed. Can be executed, or both can be executed simultaneously. In addition, the aeration treatment device 9 purifies the aerated groundwater containing VOC by aeration by adsorbing the vaporized VOC to activated carbon after vaporizing the VOC. The gas processing device 12 purifies the VOC gas by an adsorption process using activated carbon, a decomposition process using a catalyst, an incineration process by combustion, or the like.

  The suction pipe 6 collects a gas containing VOC gas leaked from the surrounding soil into the collection well 2. The pumping pipe 7 collects the leached ground water from the recovery well 2. The recovery pump 10 is a pump that separates and collects the gas containing the VOC gas and the groundwater containing the VOC by the air / water separator 8, and the groundwater containing the VOC is conveyed to the aeration treatment device 9, and the gas containing the VOC gas is gas-treated. It is conveyed to the device 12. A concentration sensor 11 that detects the concentration of the recovered VOC gas is provided between the recovery pump 10 and the gas processing device 12. The recovery control device 13 is configured to detect the temperature of groundwater detected by the thermocouple 4, the level of groundwater detected by the water level gauge 5, and the concentration of VOC gas detected by the concentration sensor 11 and the VOC gas containing VOC gas. Control the recovery of groundwater containing. The temperature control device 14 controls the heating temperature of the groundwater by the heater 3 based on the temperature of the groundwater detected by the thermocouple 4.

  At this time, the recovery control device 13 and the temperature control device 14 are realized by a CPU or the like, and the power on / off signal of the soil purification system is input. The recovery control device 13 stores an upper limit water level, a lower limit water level, and a target concentration of VOC gas in advance. For example, a normal water level of the recovery well 2 is set as the upper limit water level, and a lower limit value at which the groundwater can be pumped is set as the lower limit water level. The target concentration of the VOC gas is determined from the viewpoint of optimization of the recovery cycle based on the concentration of the VOC gas monitored in the recovery well 2. On the other hand, the temperature controller 14 stores in advance the target temperature of groundwater that is leached into the recovery well 2, inputs the temperature information of the groundwater detected by the thermocouple 4, and outputs the temperature information to the recovery controller 13. To do.

  The preheating device 20 heats groundwater containing VOCs leached into the preheating hole 21 to increase the soil hydraulic conductivity, and includes the preheating hole 21 and the preheating connection device 24. The preheating hole 21 is configured in the same manner as the recovery well 2, and as shown in FIG. 1, the preheating hole 21 is formed by embedding a cylindrical body having a slit 21a at the bottom and a lid 21b at the top. As shown in FIG. 2, the preheating holes 21 are provided in the contaminated area Apo more densely than the recovery well 2. The preheating hole 21 is provided with a heater 22 for preheating the groundwater containing the leaching VOC and a thermocouple 23 for detecting the temperature of the groundwater. Further, the preheating hole 21 is provided with a preheating control device 24 that controls the heating temperature of the groundwater by the heater 22 based on the temperature of the groundwater detected by the thermocouple 23. The preheating control device 24 is realized by a CPU or the like, and inputs a power on / off signal of the soil purification system, and controls start and stop of preheating and water temperature monitoring by the heater 22 based on these signals. The preheating control device 24 stores a target temperature of groundwater preheated by the heater 22 in advance. As shown in FIG. 3, the preheating hole 21 has a depth from the unsaturated layer Lu on the surface of the contaminated area Apo to at least the boundary between the water permeable layer Lp and the water impermeable layer Af.

  Here, when the groundwater leached into the preheating hole 21 is preheated by the heater 22, the temperature of the groundwater in the preheating hole 21 is increased. As a result, the kinematic viscosity coefficient of the groundwater is decreased and the soil permeability coefficient is increased. For this reason, the preheated groundwater becomes easy to flow in the soil, and the leaching to the recovery well 2 including the VOC in the contaminated soil is promoted. For this reason, when the groundwater is preheated by the heater 22, the recovery efficiency of VOC in the contaminated soil is increased. In addition, by preheating the groundwater in the preheating hole 21, the soil around the preheating hole 21 is also heated by convection heat transfer, and as a secondary effect, VOCs contaminating the soil around the preheating hole 21 are vaporized. As a result, the vaporized VOC gas is easily moved in the soil, and leakage into the recovery well 2 is promoted.

  Accordingly, the heating temperature of the groundwater in the recovery well 2 and the preheating temperature of the groundwater in the preheating hole 21 are determined in consideration of both the decrease in the kinematic viscosity coefficient and the vaporization of VOC. However, since the heat transfer efficiency varies depending on the difference in specific heat of groundwater and soil existing in the contaminated area Apo, if the heating temperature of groundwater is set too high, heating energy may be wasted due to the difference in heat transfer efficiency. It is desirable to set a preheating temperature and a heating temperature for each contaminated area Apo.

  The water injection device 30 supplements the ground water to the recovery well 2 and the preheating hole 21 where the amount of groundwater has decreased due to pumping in the recovery well 2, and has a water injection well 31, a water injection pump 34, a heating tank 35, and a water injection connection device 36. is doing.

  The water injection well 31 is configured in the same manner as the recovery well 2, and as shown in FIG. 1, a slit 31a is provided in the lower part and a cylinder having a lid 31b is embedded in the upper part. As shown in FIG. 2, the water injection well 31 is provided on the upstream side of the contaminated area Apo when viewed from the direction of groundwater flow indicated by the arrow A. The water injection well 31 is provided with a water level gauge 32 for detecting the level of groundwater. At this time, as shown in FIG. 3, the water injection well 31 has a depth from the unsaturated layer Lu on the surface of the contaminated area Apo to at least the boundary between the water permeable layer Lp and the water impermeable layer Af.

  The water injection well 31 is connected to the water injection pump 34 via the water injection pipe 33, and the heated water in the heating tank 35 is injected by the water injection pump 34. The water injection control device 36 controls the operation of the water injection pump 34 or the heating tank 35 on the basis of the groundwater level detected by the water level gauge 32. The water injection control device 36 is realized by a CPU or the like, and receives a power on / off signal of the soil purification system. The water injection controller 36 controls the start and stop of water level monitoring and the start and stop of water injection based on the monitored water level based on these signals. The water injection control device 36 stores in advance a target water level for starting the injection of heated water.

  The soil purification system configured as described above purifies the soil in the contaminated area Apo as follows. First, when the power of the soil purification system is turned on, the purification device 1, the preheating device 20, and the water injection device 30 are activated. At this time, in the purification apparatus 1, under the control of the temperature connection apparatus 14, the heater 3 in the recovery well 2 heats the groundwater as shown in FIG. At the same time, in the preheating device 20, the heater 22 in the preheating hole 21 preheats the groundwater under the control of the preheating control device 24. Here, in the figures used in the description of FIG. 4 and subsequent figures, the groundwater level is indicated by W.

  Next, when the water temperature of the groundwater in the recovery well 2 detected by the thermocouple 4 is heated to the target temperature, the purification device 1 is based on the temperature information output from the temperature control device 14 by the recovery control device 13. An activation signal is output and the collection pump 10 is activated. Thereby, in the state which heated the groundwater with the heater 3, as shown in FIG. 5, the collection | recovery pump 10 attracts | sucks the gas containing the VOC gas leaked to the upper part of the collection | recovery well 2 with the suction pipe 6, and a gas processing apparatus 17 is introduced. At this time, the recovery control device 13 monitors the concentration of the VOC gas based on the concentration signal input from the concentration sensor 11 and sucks the gas containing the VOC gas until a preset target concentration is reached. Further, the gas containing the sucked VOC gas is purified by the gas processing device 12.

  When the concentration of the VOC gas in the recovery well 2 is reduced to the target concentration due to the suction of the gas containing the VOC gas, the recovery control device 13 instructs the concentration control device 19 to stop the heating of the groundwater by the heater 3 and the pumping pipe 7 Is switched to the pumping of groundwater containing VOC, and the groundwater is introduced into the aeration treatment device 9 via the steam separator 8. Thereby, the groundwater containing VOC is purified by the aeration processing device 9. On the other hand, the recovery well 2 is lowered to the lower limit water level WL where the groundwater level W cannot be heated by the heater 3, as shown in FIG. Due to the pumping of the groundwater, the internal pressure of the recovery well 2 decreases, and the groundwater easily enters from the surrounding soil. When the groundwater level W drops to the lower limit water level WL, the recovery control device 13 outputs a control signal to the recovery pump 10 based on the water level information input from the water level gauge 5 and stops the water level. Information is output to the temperature controller 14. Thereby, the temperature control apparatus 14 outputs a control signal to the heater 3 and stops heating.

  Next, the recovery control device 13 outputs a control signal to the temperature control device 14 and the recovery pump 10, and as shown in FIG. 7, suction of gas including VOC gas by the suction pipe 6 and heating of groundwater by the heater 3 are performed. Resume. As a result, the internal pressure of the recovery well 2 further decreases, the temperature of the preheating hole 21 and the surrounding soil increases due to the preheating of the groundwater, and the groundwater containing VOC has a high permeability coefficient together with the gas containing VOC gas. It is forcibly sucked from the surrounding soil as shown by the arrow. For this reason, in the recovery well 2, the groundwater level W and the concentration of VOC gas rise. However, the rising speed of the water level W and the rising speed of the VOC gas concentration in this case are several times faster than when the groundwater in the preheating hole 21 is not preheated.

  Then, as the water level in the recovery well 2 rises due to the ingress of groundwater from the surroundings, the groundwater level in the preheating hole 21 and the water injection well 31 located on the upstream side of the recovery well 2 as viewed from the flow direction of the groundwater. Will go down. For this reason, as shown in FIG. 8, under the control of the water injection control device 36, the heated water in the heating tank 35 is injected into the water injection well 31 from the water injection pipe 33. The heated water injected into the water injection well 31 in this way penetrates the soil having a higher permeability coefficient at a higher speed than the low-temperature water while involving the VOC, and passes through the preheating hole 21 or directly. Leach in recovery well 2. Therefore, the groundwater is heated or preheated by the heater 3 or the heater 22 to increase the recovery efficiency of VOC in the contaminated soil. At this time, the VOC gas vaporized by the heated water also moves quickly with the gas in the soil and leaks into the recovery well 2.

  Then, after the groundwater in the recovery well 2 has risen to the upper limit water level, the soil in the contaminated area is purified by repeating the suction of the gas containing the VOC gas and the groundwater pumping cycle again. In the soil purification system and the soil purification method of the present invention, the ground water is preheated while repeating the suction of the gas containing the VOC gas and the pumping cycle of the ground water, and the ground water containing the VOC in the recovery well 2 and the gas containing the VOC gas. Are quickly collected and recovered under high recovery efficiency to purify VOCs. At this time, as shown in FIG. 4, if the ground water in each preheating hole 21 is preheated by the heater 22, the suction of the gas containing the VOC gas in the recovery well 2 shown in FIG. 5 and the heating of the groundwater by the heater 3. The operations of the pumping of the groundwater containing VOC by the pumping pipe 7 shown in FIG. 6 and the re-suction of the gas containing the VOC gas by the suction pipe 6 and the reheating of the groundwater by the heater 3 shown in FIG. You may replace it.

  Next, with reference to the flowchart shown in FIG. 9, the procedure of the temperature control process of the groundwater containing VOC in the washing | cleaning apparatus 1 of the soil purification system of this invention, the suction process of the gas containing VOC gas, and the pumping-up process of the groundwater containing VOC Will be described.

  When the power of the soil purification system is turned on, the temperature control device 14 executes a temperature control process for heating the groundwater containing the VOC in the recovery well 2 to the target temperature by the heater 3 as shown in FIG. 9 (step S102). .

  Next, the temperature control device 14 determines whether or not the groundwater in the recovery well 2 is equal to or higher than the target temperature based on the temperature information input from the thermocouple 4 (step S104). When the groundwater is not equal to or higher than the target temperature (No at Step S104), the temperature control device 14 returns to Step S102 and executes temperature control processing until the groundwater becomes equal to or higher than the target temperature. On the other hand, when the ground water in the recovery well 2 is equal to or higher than the target temperature (step S104, Yes), the recovery control device 13 outputs a start signal to start the recovery pump 10 (step S106).

  Next, the recovery control device 13 performs a pre-suction process for a gas containing VOC gas (step S108). In the pre-suction process of the gas containing the VOC gas, the gas containing the VOC gas sucked through the suction pipe 6 is introduced into the gas processing device 12 and purified.

  Thereafter, the recovery control device 13 determines whether or not the concentration of the VOC gas in the sucked gas detected by the concentration sensor 11 is equal to or lower than the target concentration (step S110). When the concentration of the VOC gas exceeds the target concentration (No at step S110), the recovery control device 13 returns to step S108 and pre-suctions the gas containing the VOC gas until the concentration of the VOC gas becomes equal to or lower than the target concentration. Execute the process. On the other hand, when the concentration of the VOC gas is equal to or lower than the target concentration (step S110, Yes), the recovery control device 13 performs a pumping process of groundwater including VOC by the pumping pipe 7 (step S112). Groundwater containing VOCs pumped by the pumping pipe 7 is introduced into the aeration treatment device 9 via the air / water separator 8, and clean groundwater with purified VOC is discharged from the aeration treatment device 9.

  Next, the collection control device 13 determines whether or not the groundwater level is the lower limit level based on the water level information input from the water level gauge 5 (step S114). When the groundwater level is not the lower limit water level (step S114, No), the recovery control device 13 returns to step S112 and executes the pumping process until the groundwater level reaches the lower limit water level. On the other hand, when the groundwater level is the lower limit water level (step S114, Yes), the recovery control device 13 performs a post-suction process of the gas containing the VOC gas (step S116).

  The post-suction treatment of the gas containing the VOC gas is executed in a state where the pressure inside the recovery well 2 due to the groundwater pumping is lowered, the temperature of the groundwater is increased by preheating and heating, and the soil permeability is increased. . For this reason, in the post-suction process, the groundwater containing VOC is forcibly sucked out from the surrounding soil to the recovery well 2 together with the gas containing the VOC gas, as compared with the pre-suction process in step S108. For this reason, in the post-suction process, the VOC gas concentration increases while the groundwater level in the recovery well 2 slowly rises from the lower limit water level. At this time, the gas containing the sucked VOC gas is introduced into the gas processing device 12 to purify the VOC gas.

  Next, the recovery control device 13 determines whether or not the groundwater level is equal to or higher than the upper limit level based on the water level information input from the water level gauge 5 (step S118). When the water level of the groundwater does not exceed the upper limit water level (No at Step S118), the recovery control device 13 returns to Step S116 and executes the post-suction process of the gas containing VOC gas until the groundwater level becomes equal to or higher than the upper limit water level. To do. On the other hand, when the groundwater level is equal to or higher than the upper limit water level (step S118, Yes), since the groundwater level is restored to the original state, the recovery control device 13 outputs a stop signal and stops the recovery pump 16. (Step S120).

  Thereafter, the collection control device 13 determines whether or not the power of the soil purification system is turned off (step S122). Whether or not the power is turned off is determined by the collection control device 13 from the input power off signal of the soil purification system. When the power supply is not turned off (No at Step S122), the recovery control device 13 returns to Step S102 and performs temperature control processing of groundwater containing VOC, suction processing of gas containing VOC gas, and pumping of groundwater containing VOC. Repeat the procedure. On the other hand, when the power is turned off (step S122, Yes), the collection control device 13 ends the collection control.

  Next, the temperature control process of groundwater containing VOC shown in FIG. 9 is demonstrated. FIG. 10 is a flowchart showing the procedure of the temperature control process for the groundwater containing the VOC shown in FIG.

  As shown in FIG. 10, the temperature control device 14 outputs a start signal to turn on the heater 3 (step S202). Next, the temperature control device 14 acquires water temperature information related to the temperature of the groundwater detected by the thermocouple 4 (step S204).

  Next, the temperature control device 14 determines whether or not the groundwater is equal to or higher than the target temperature from the acquired water temperature information (step S206). If the groundwater in the recovery well 2 does not exceed the target temperature (No at Step S206), the temperature control device 14 returns to Step S204 and acquires water temperature information until the groundwater reaches the target temperature or higher. On the other hand, when groundwater is more than target temperature (Step S206, Yes), temperature controller 14 outputs a stop signal and turns off heater 3 (Step S208). Thereby, in the recovery well 2, the heating of the groundwater by the heater 3 is stopped, the groundwater containing VOC in the preheated preheated hole 21 is leached, and the vaporized VOC gas leaks out.

  Thereafter, the temperature control device 14 acquires groundwater temperature information again (step S210), and ends the groundwater temperature control process.

  Next, a pre-suction process for a gas containing the VOC gas shown in FIG. 9 will be described. FIG. 11 is a flowchart showing the procedure of the pre-suction process for the gas containing the VOC gas shown in FIG.

  As shown in FIG. 11, the recovery control device 13 sucks the gas containing the VOC gas from the suction pipe 6 (step S222). For the suction of the gas containing the VOC gas, the recovery control device 13 outputs an operation signal, opens the valve of the signal suction pipe 6, closes the valve of the pumping pipe 7, and removes the gas in the upper part of the recovery well 2 from the suction pipe 6. Achieved by aspiration. As a result, the gas in the upper portion of the recovery well 2 is introduced from the suction pipe 6 to the gas processing device 12 via the steam separator 8, the recovery pump 10 and the concentration sensor 11. The gas processing device 12 discharges clean gas (air) obtained by purifying the VOC gas.

  Next, the recovery control device 13 acquires the concentration information of the VOC gas detected by the concentration sensor 11 (step S224), and ends the pre-suction process for the gas containing the VOC gas.

  Next, the pumping process of the groundwater containing VOC shown in FIG. 9 is demonstrated. FIG. 12 is a flowchart showing the procedure of the groundwater pumping process including the VOC shown in FIG.

  As shown in FIG. 12, the collection control device 13 pumps up groundwater containing VOC from the pumping pipe 7 (step S242). The pumping of the groundwater is achieved by the recovery control device 13 outputting an operation signal, closing the valve of the suction pipe 6, opening the valve of the pumping pipe 7, and sucking the groundwater in the recovery well 2 by the pumping pipe 7. Is done. The groundwater containing VOC pumped through the pumping pipe 7 is separated from the gas containing VOC gas by the air / water separator 8, and then introduced into the aeration treatment device 9, and clean groundwater purified by VOC is aerated. It is discharged from the device 9.

  Thereafter, the recovery control device 13 acquires the water level information input from the water level gauge 5 (step S244), and ends the groundwater pumping process.

  Next, a post-suction process for the gas containing the VOC gas shown in FIG. 9 will be described. FIG. 13 is a flowchart showing the procedure of the post-suction process for the gas containing the VOC gas shown in FIG.

  As shown in FIG. 13, the recovery control device 13 sucks the gas containing the VOC gas from the suction pipe 6 (step S262). The suction of the gas containing the VOC gas is executed in a state where the pressure inside the recovery well 2 due to the pumping of groundwater is reduced, the temperature of the groundwater is increased by preheating and heating, and the soil permeability is increased. For this reason, with the suction of the gas containing the VOC gas, the groundwater containing the VOC is forcibly sucked out from the surrounding soil to the recovery well 2 together with the gas containing the VOC gas. Accordingly, in the recovery well 2, the groundwater rises slowly from the lower limit water level, and the VOC gas concentration also rises slowly. The gas containing the VOC gas sucked in this way is purified by the gas processing device 12 and is discharged from the gas processing device 12 as a clean gas.

  Thereafter, the recovery control device 13 acquires the water level information input from the water level gauge 5 (step S264), and ends the post-suction process for the gas containing the VOC gas.

  Next, preheating control of groundwater including VOC by the preheating control device 24 in the preheating device 20 of the soil purification system of the present invention will be described. FIG. 14 is a flowchart showing a procedure of preheating control of groundwater including VOC by the preheating control device 24.

  When the power supply of the soil purification system is turned on, the preheating control device 24 turns on the heater 22 as shown in FIG. 14 (step S302) and starts preheating groundwater including VOC in the preheating hole 21. Next, the preheating control device 24 acquires water temperature information related to the temperature of the groundwater detected by the thermocouple 23 (step S304).

  Next, the preheating control device 24 determines whether or not the groundwater is equal to or higher than the target temperature from the acquired water temperature information (step S306). When the groundwater in the preheating hole 21 does not exceed the target temperature (No in Step S306), the preheating control device 24 returns to Step S304 and acquires water temperature information until the groundwater becomes equal to or higher than the target temperature. On the other hand, when groundwater is more than target temperature (Step S306, Yes), preheating control device 24 outputs a stop signal, and turns off heater 22 (Step S308). Thereby, the heater 22 stops the preheating of the groundwater in the preheating hole 21.

  Thereafter, the preheating control device 24 determines whether or not the power of the soil purification system is turned off (step S310). Whether or not the power is turned off is determined by the preheating control device 24 from the input power-off signal of the soil purification system. When the power is not turned off (No at Step S310), the preheating control device 24 returns to Step S302, turns on the heater 22, and starts preheating groundwater. On the other hand, when the power is off (step S310, Yes), the preheating control device 24 ends the preheating control of the groundwater.

  Next, water injection control of the heating water by the water injection control device 36 in the water injection device 30 of the soil purification system of the present invention will be described. FIG. 15 is a flowchart showing a procedure of water injection control by the water injection control device 36.

  When the power of the soil purification system is turned on, the water injection control device 36 acquires water level information related to the groundwater level detected by the water level gauge 32 as shown in FIG. 15 (step S322).

  Next, the water injection control device 36 determines whether or not the groundwater is equal to or lower than the target water level from the acquired water level information (step S324). When the water level of the water injection well 31 is not below the target water level (No at Step S324), the water injection control device 36 returns to Step S322 and acquires the water level information until the groundwater becomes below the target water level. On the other hand, when the groundwater level is equal to or lower than the target water level (step S324, Yes), the water injection controller 36 injects water into the water injection well 31 (step S326). This water injection is performed when the water injection control device 36 outputs an activation signal and activates the water injection pump 34. Thereby, as for the water injection well 31, the heating water of the heating tank 35 is injected from the water injection pipe 33, and a water level rises slowly. As the water level rises, the injected heated water leaches out from the water injection well 31 and flows down in the soil along the groundwater flow direction. During this flow, the heated water engulfes VOC from the soil in the contaminated area Apo and leaches into the adjacent preheating hole 21 and the recovery well 2. For this reason, groundwater collects VOCs in contaminated soil with high efficiency.

  Next, the water injection control device 36 determines whether or not the water level of the water injection well 31 has exceeded the target water level by water injection (step S328). When the water level of the water injection well 31 does not exceed the target water level (No at Step S328), the water injection control device 36 returns to Step S326 and acquires water level information until the groundwater becomes equal to or higher than the target water level. On the other hand, when the water level of the groundwater exceeds the target water level (step S328, Yes), the water injection control device 36 outputs a stop signal to stop the water injection pump 34, and stops water injection to the water injection well 31 (step). S330). Even if the water injection to the water injection well 31 is stopped, the recovery well 2 repeats the suction of the gas containing the VOC gas and the pumping cycle of the groundwater, so that the groundwater containing the VOC and the gas containing the VOC gas are recovered and purified. is doing.

  Thereafter, the water injection control device 36 determines whether or not the power of the soil purification system has been turned off (step S332). When the power is not turned off (No at Step S332), the water injection control device 36 returns to Step S322 and starts acquiring the water level information. On the other hand, when the power supply is turned off (step S332, Yes), the water injection control device 36 ends the water injection control of the heated water.

  In the soil purification system and the soil purification method of the present invention, the pollutant gas that has flowed down by the preheated ground water in the plurality of preheating holes provided in the contaminated area around the recovery well and leaks into the recovery well, and the recovery well Collect and purify the groundwater containing the pollutants that leach into the water. For this reason, the preheated groundwater has a low kinematic viscosity coefficient and a high soil permeability coefficient, so that it easily flows in the soil and promotes leaching into the recovery well. For this reason, the soil purification system and the soil purification method of the present invention have high recovery efficiency of pollutants in the contaminated soil, and can quickly remove and purify the pollutants from the contaminated area. When applied to poorly permeable soils, contaminants can be quickly removed and purified.

  In the soil purification system and the soil purification method of the present invention, the pollutant gas polluted from the soil in the contaminated area and the pollutant vaporized from the soil are flowed down by the preheated ground water and collected in the recovery well. For this reason, the soil purification system and the soil purification method of the present invention can be applied over a wide range in which the concentration of contaminants in the groundwater is from a low concentration to a high concentration exceeding 10,000 times the environmental standard. The present invention can be applied not only to the purification of contaminated areas that are locally contaminated at high concentrations, but also to the purification of contaminated areas of low-concentration contaminated areas over a wide area where pollutants have diffused.

  Here, in the above-described embodiment, the case where the contaminant is VOC has been described. However, the soil purification system and the soil purification method of the present invention are not limited to VOCs as purification targets as long as they are pollutants flowing down by preheated groundwater. For example, heavy metals, gasoline, oils such as light oil, It can be applied to the purification of various pollutants regardless of whether they are water-soluble or water-insoluble.

  In addition, the soil purification system and the soil purification method of the present invention preheat the groundwater in the contaminated area and flow down the pollutants with the preheated groundwater. For example, hydrogensulfite such as sodium bisulfite is added to the groundwater in the preheated hole. The aqueous solution may be neutralized and injected. In this case, the neutralized bisulfite aqueous solution acts as a reducing agent that reductively decomposes VOC, which is a pollutant, by reductive dechlorination, and it is necessary to collect groundwater containing the pollutant in order to purify VOC. There is no.

It is sectional drawing which shows the soil purification system using the soil purification method concerning this invention. It is a top view which shows an example of arrangement | positioning of the collection | recovery well, preheating hole, and water injection well which comprise the soil purification system of FIG. It is sectional drawing along CC line of FIG. In the soil purification system of FIG. 1, while the heater in a recovery well heats groundwater, it is sectional drawing which shows a mode that the heater in a preheating hole preheats groundwater. It is sectional drawing which shows typically a mode that the gas containing VOC gas is attracted | sucked from a suction pipe in the state which heated the groundwater of the recovery well to target temperature, and heated the groundwater with the heater. It is sectional drawing which shows typically a mode that the water level of groundwater fell to the minimum water level by pumping up groundwater with a pumping pipe. In FIG. 6, it is sectional drawing which shows typically a mode that the suction by a suction tube and the heating of groundwater by a heater were restarted. It is sectional drawing which shows typically a mode that the level of the groundwater of an upstream water injection well falls and a heating water is inject | poured into a water injection well as the water level of the recovery well of FIG. 6 rises. It is a flowchart explaining the procedure of the temperature control process of the groundwater containing VOC in the washing | cleaning apparatus of the soil purification system of this invention, the suction process of the gas containing VOC gas, and the pumping-up process of the groundwater containing VOC. It is a flowchart which shows the procedure of the temperature control process of the groundwater containing VOC shown in FIG. It is a flowchart which shows the procedure of the pre-aspiration process of the gas containing VOC gas shown in FIG. It is a flowchart which shows the procedure of the pumping-up process of the groundwater containing VOC shown in FIG. It is a flowchart which shows the procedure of the post-aspiration process of the gas containing VOC gas shown in FIG. It is a flowchart which shows the procedure of the preheating control of the groundwater containing VOC by the preheating control apparatus in the preheating apparatus of the soil purification system of this invention. It is a flowchart which shows the procedure of the water injection control by the water injection control apparatus in the water injection apparatus of the soil purification system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Purification apparatus 2 Recovery well 2a Slit 2b Lid 3 Heater 4 Thermocouple 5 Water level meter 6 Suction pipe 7 Pumping pipe 8 Air-water separator 9 Aeration processing apparatus 10 Recovery pump 11 Concentration sensor 12 Gas processing apparatus 13 Recovery control apparatus 14 Temperature control Device 20 Preheating device 21 Preheating hole 21a Slit 21b Lid 22 Heater 23 Thermocouple 24 Preheating control device 30 Water injection device 31 Water injection well 31a Slit 31b Lid 32 Water level meter 33 Water injection pipe 34 Water injection pump 35 Heating tank 36 Water injection control device Af Water impermeable layer Apo polluted area Lu unsaturated layer Lp permeable layer

Claims (10)

A purification device having a recovery well excavated in an area contaminated with pollutants is collected and purified by collecting the gas vaporized by the contaminant leaking into the recovery well and the groundwater containing the contaminant leaching into the recovery well. A soil purification system,
A plurality of preheating holes excavated in the contaminated area around the recovery well;
Preheating means installed in each preheating hole and preheating groundwater leached into the preheating hole;
Equipped with a preheating device having
The soil purification system, wherein the preheating means promotes leaching of the groundwater into the recovery well by preheating the groundwater leached into the preheating hole.   The soil purification system according to claim 1, wherein the purification device includes a heating unit that is provided in the recovery well and heats groundwater that is leached into the recovery well. The preheating device is:
Water temperature detecting means for detecting the temperature of the groundwater in each preheating hole;
Preheating temperature control means for controlling the preheating temperature of the groundwater by the preheating means based on the detected water temperature;
The soil purification system according to claim 1 or 2, characterized by comprising: A water injection well drilled on the upstream side of the recovery well in the direction of flow of the groundwater;
A heating tank that heats the water to make heated water;
Water injection means for injecting the heated water into the water injection well;
The soil purification system according to any one of claims 1 to 3, further comprising a water injection device having The purification device comprises:
A water level detection means for detecting the level of the groundwater leached into the recovery well;
A concentration detection means for detecting the concentration of the gas that the pollutant leaking into the recovery well is vaporized;
A recovery control means for controlling the recovery of the groundwater containing the gas and the pollutant based on the detected water level of the groundwater and the concentration of the gas;
The soil purification system according to any one of claims 1 to 4, characterized by comprising: The purification device comprises:
Water temperature detecting means for detecting the temperature of groundwater leached into the recovery well;
Temperature control means for controlling the heating temperature of the groundwater by the heating means based on the detected water temperature;
The soil purification system according to claim 5, further comprising: The water injection device is
Water level detecting means for detecting the level of heated water poured into the water injection well;
Water injection control means for controlling the operation of the heating tank or the water injection means based on the detected water level of the heated water,
The soil purification system according to any one of claims 4 to 6, further comprising: A soil purification method for recovering and purifying the gas vaporized by the pollutant leaking into a recovery well provided in a contaminated area caused by the contaminant and the groundwater containing the contaminant leached into the recovery well,
Preheating groundwater present in the contaminated area around the recovery well and promoting leaching of the groundwater into the recovery well;
Recovering and purifying the groundwater containing the pollutant that has been flown down by preheated groundwater and leaked into the recovery well, and the pollutant that has leached into the recovery well;
A soil remediation method comprising:   The soil purification method according to claim 8, further comprising a leachate heating step of heating groundwater leached into the recovery well.   The soil purification method according to claim 9, further comprising a water pouring step of pouring heated water on the upstream side of the groundwater in the downflow direction of the recovery well.

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