JP2006275940A - Soil purification monitoring method - Google Patents

Abstract

A soil remediation monitoring method that can easily investigate the state of soil and the progress of soil remediation without requiring a particularly complicated apparatus configuration and without being affected by topography and distance.
A wireless network module 16c of each CO ₂ gas sensor network unit 16, 16 ... wirelessly connects another wireless network module 16c, 16c ... and a gateway 22 which is a communication means of a host computer 14, Establish an autonomous network indicated by broken lines. In this network, the CO ₂ gas concentration continuously measured by each CO ₂ gas sensor network unit 16, 16... Is relayed to other wireless network modules 16 c, 16 c. To the gateway 22. The host computer 14 analyzes the time series change from each received measurement value, and displays the time series change of the CO ₂ concentration in the soil on the monitor 20.
[Selection] Figure 3

Description

  The present invention relates to a soil purification monitoring method, and more particularly to a soil purification monitoring method that manages the progress of purification when soil or groundwater contaminated with oil is purified by the activity of microorganisms.

  In recent years, there has been a problem that pollutants such as oils and volatile organic compounds infiltrate into the soil due to the dumping of industrial waste and the discharge of industrial wastewater, thereby contaminating the soil. When the soil is contaminated, the contaminants are eluted into the groundwater, so that the soil contamination and the groundwater contamination spread over a wide area, which may affect the living environment. Therefore, soil environment standards and groundwater purification standards are established by the Basic Environment Law and the Water Pollution Control Law, and various substances are regulated.

  In the past, various efforts have been made to purify contaminated soil. In addition to digging up contaminated soil and groundwater to physically and chemically treat pollutants, the original location of contaminated soil A method of directly injecting a drug or the like for treating a pollutant has been proposed.

  In particular, the upstream side of contaminated soil contaminated with oil and other pollutants is directly purified by injecting substances that promote microbial degradation, such as oxygen sources, nitrogen sources, and phosphorus sources, and microorganisms that have a resolution of pollutants. The bioremediation method is a method that does not require large-scale equipment and construction methods, and it also eliminates the generation of by-products that cause secondary contamination due to the purification process. It is widely used as a possible method (see Patent Document 1).

  By the way, when soil purification is performed by the above-described method, first, investigation (that is, monitoring) of contaminated soil or groundwater is conducted, and soil purification work is started based on the investigation result. And even during soil remediation, it is necessary to constantly monitor the progress of soil remediation by regularly monitoring soil or groundwater.

  The monitoring (survey) method described above is performed by boring the contaminated area, sampling a part of the soil or groundwater, and detecting or analyzing the target pollutant with a detector tube or gas chromatography. The method is common.

In addition, as in Patent Document 2, soil gas collection pipes for collecting gas in soil are arranged at a plurality of locations, and connected to an analysis instrument for analyzing one soil gas. An apparatus for continuously monitoring (investigating) soil gas by switching and analyzing the supply of collected gas is also disclosed. Thereby, the sampling work can be saved.
Japanese Patent Laid-Open No. 11-262551 JP 2001-221725 A

  However, when soil or groundwater is contaminated with pollutants such as oil, the contamination range is wide according to the flow of groundwater, and buildings such as factory facilities may be located on the surface of the contaminated soil. Many. For this reason, the above-described monitoring method using boring requires a lot of time and labor for sampling and analysis, and cannot perform continuous measurement. Therefore, with the conventional method, it is extremely difficult to obtain accurate information regarding the state of the soil and the progress information of soil purification.

  Also in Patent Document 2, since it is necessary to install a wide range while avoiding a facility where a large number of sampling pipes are located, a lot of equipment costs are required and there are restrictions on the installation conditions. In addition, there is a drawback that the time and cost required to maintain the equipment increase.

  Moreover, since only one analytical instrument is provided in the apparatus of Patent Document 2, when there are a large number of measurement locations, it is difficult to continuously measure each location, and therefore accurate soil condition changes are possible. There was also a problem that information on the progress of soil purification could not be obtained.

  The present invention has been made in view of such circumstances, and when performing soil purification with aerobic microorganisms on soil contaminated with oil, it is not particularly required to have a complicated apparatus configuration, and is affected by topography and distance. It is an object of the present invention to provide a soil purification monitoring method that can easily investigate the state of soil and the progress of soil purification.

In order to achieve the above object, the invention according to claim 1, when soil is purified by biodegrading the oil by aerobic microorganisms with respect to soil contaminated with oil, in the soil remediation monitoring method for investigating the progress of soil remediation, continuously detectable CO ₂ gas sensor of CO ₂ gas concentration in the soil, and located at a plurality of the soil, the CO ₂ The gas sensor continuously measures the CO ₂ concentration at a plurality of locations in the soil, accumulates the measured values, transmits them to a host computer for analysis, and receives the measured values of the respective CO ₂ gas sensors. Then, the progress status of the soil purification is predicted from the time-series change of the CO ₂ concentration by the host computer.

  The “soil” described here includes not only the soil itself but also groundwater that exists in the soil and flows at a low speed in the soil.

According to the present invention, when an oil that contaminates soil or groundwater is aerobically biodegraded by aerobic microorganisms for soil purification, CO ₂ gas is generated during the decomposition process. The inventor of the present application pays attention to this point, and predicts the progress of soil purification by aerobic microorganisms by measuring the concentration of CO ₂ gas in the soil, and derives a method for monitoring the soil purification.

That is, if soil purification is in progress, oil in the soil is biodegraded and the microbial activity increases, so the CO ₂ concentration in the soil increases. On the other hand, when the soil purification is completed, the biodegradable oil decreases and the microbial activity decreases, so the CO ₂ concentration in the soil also decreases. Thus, since the CO ₂ concentration in the soil and the progress of soil purification are related, the progress of the soil purification can be accurately determined by analyzing the change in CO ₂ concentration at each point in time series. Can be predicted.

When performing soil monitoring in the present invention, first, a CO ₂ gas sensor is installed in the soil in the contaminated soil and in the vicinity thereof, and a host computer connected to each CO ₂ gas sensor is installed. Each CO ₂ gas sensor continuously measures the concentration of CO ₂ gas generated from the soil at the place where it is placed, and transmits the measured value to the host computer. The host computer accumulates and analyzes the continuous measurement values received from each CO ₂ gas sensor, and predicts the progress of soil remediation based on changes in these measurement values. As a result, when the soil contaminated with oil is purified by the bioremediation method, it is possible to easily investigate the status of the soil to be purified and the progress of the purification, so that efficient soil purification is performed in a short time. be able to. In addition, according to the present invention, since only a CO ₂ gas sensor is installed at each point to be measured, the equipment cost, equipment space, and labor required for monitoring soil purification can be greatly reduced.

According to a second aspect of the present invention, the CO ₂ gas sensor according to the first aspect includes a communication module that is a node capable of bidirectional data communication, and the host computer and the communication module relay other communication modules. It has a network function for autonomously building a pointed network. The invention according to claim 3 is characterized in that the CO ₂ gas sensor according to claim 1 or 2 performs data communication with the host computer wirelessly.

  The above-described “autonomous construction of the network” means that the host computer and each communication module transmit / receive data (ie, sensing) to each other in accordance with a command set in advance by software or the like. This refers to automatically building a network between each communication module.

According to the present invention, the communication module, which is a node provided in the CO ₂ gas sensor, performs data communication with the host computer wirelessly, and allows other CO ₂ gas sensor communication modules to function by constructing an autonomous network. Measurement values can be relayed and transmitted to the host computer. By networking sensors, even when the soil to be monitored is wide, or when the terrain is complex due to the location of buildings, etc., it is affected by the terrain and distance without using a particularly complicated device configuration. In addition, the CO ₂ gas sensor can be arranged at an arbitrary position over a wide range, and soil purification can be monitored efficiently.

In addition, since the data communication between the CO ₂ gas sensor and the host computer is possible in both directions, the operation of the CO ₂ gas sensor can be controlled by the host computer. Thus, management and maintenance of the CO ₂ gas sensor since it is possible to turn OFF the power of the CO ₂ gas sensors on the host computer, scattered over a wide range in the absence on, need to be able to constantly monitor the state of the CO ₂ gas sensor itself Can be simplified.

According to a fourth aspect of the present invention, the host computer according to at least one of the first to third aspects displays a CO ₂ concentration distribution in the soil based on a measurement value from the CO ₂ gas sensor. A display means is provided. Thereby, since the state of soil and the progress of soil purification can be easily visually recognized by the display means, it is possible to reduce labor and labor required for monitoring soil purification.

Incidentally, the display means preferably exhibits a CO ₂ concentration distribution of the soil by isolines. Further, the display means, it is preferable to chronologically display the changes in the CO ₂ concentration in the soil. Thereby, since it is possible to recognize the change in the state of the soil and the progress of the soil purification at a glance with the display means, it is possible to further reduce the labor required for monitoring the soil purification.

As described above, according to the soil purification monitoring method according to the present invention, the CO ₂ concentration in the soil is continuously measured by the CO ₂ gas sensor installed at each location of the contaminated soil, and the measured CO ₂ is measured. _{2 Since} the progress of soil remediation is predicted by the host computer from the continuous change in concentration, it is possible to accurately grasp the state of soil remediation at low cost. In addition, since the CO ₂ gas sensor and the host computer perform two-way data communication wirelessly using a communication module as a node and automatically construct an autonomous network, each CO ₂ gas sensor can be used as a relay point. Become. By forming a sensor network for monitoring at the purification site, efficient soil purification monitoring can be easily and widely performed without being affected by the topography and distance to be monitored.

  Hereinafter, preferred embodiments of a soil purification monitoring method according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a side sectional view showing an overall configuration of a soil purification monitoring system 10 according to an embodiment of the present invention.

  As shown in FIG. 1, a saturated layer 6 including groundwater is formed below the unsaturated layer 4 forming the ground surface 2, and the unsaturated layer 4 and a part of the saturated layer 6 are contaminated with oil. Contaminated soil 8 is present.

  The saturated layer 6 described here is a layer in which rock fractures and pores in the soil are saturated with groundwater, and in the saturated layer 6, a slow flow of saturated groundwater is generated. In addition to the soil itself, the contaminated soil 8 includes groundwater existing in the soil.

The soil remediation monitoring system 10 is disposed in the vicinity of the contaminated soil 8 and mainly includes a plurality of observation wells 12, 12..., A host computer 14 for monitoring soil remediation, and the interior of each observation well 12, 12. And CO ₂ gas sensor network units 16, 16... For measuring the CO ₂ concentration in the soil.

A plurality of observation wells 12 are arranged in the contaminated soil 8 and the vicinity thereof, and are formed by excavating from the ground surface 2 to a depth reaching the saturated layer 6 in a direction perpendicular to the contaminated soil 8. The shape and hole diameter of the observation well 12 are not particularly limited, but the CO ₂ gas sensor network unit 16 can be stably installed, and the structure does not release the gases inside the contaminated soil 8 into the atmosphere. Is preferred. The detailed structure of the observation well 12 will be described later with reference to FIG.

The host computer 14 is installed in a facility 18 installed on the upper surface of the ground surface 2 and includes a monitor 20 that is a communication unit and a display unit (not shown). The host computer 14 has a built-in software to build a wireless sensor network according to the CO ₂ gas sensor network unit 16, 16 ..., each CO ₂ gas sensor network unit 16, 16 ... of the measurement value or the like measured by the Soil remediation is monitored by collecting and analyzing data. Detailed descriptions of the host computer 14, the communication means, and the monitor 20 will be described later.

FIG. 2 is an enlarged cross-sectional view showing the structure of the observation well 12 and the CO ₂ gas sensor network unit 16 in the present embodiment.

The CO ₂ gas sensor network unit 16 includes a CO ₂ gas sensor 16a, a CO ₂ gas sensor control module 16b, a wireless network module 16c, and a conductor 16d.

The CO ₂ gas sensor 16 a is installed above the saturated layer 6 inside the observation well 12. The installation condition is preferably an installation state or structure in which part or all of the CO ₂ gas sensor 16a is not immersed in the ground water in the observation well 12 in order to accurately measure the CO ₂ concentration in the soil.

In this embodiment, CO ₂ gas measurement concentration range: atmospheric concentration (about 400 ppm) to 80,000 ppm, output: 0 to 4 V, sensor accuracy: ± 20% (± 1000 ppm when converted to CO ₂ concentration), operating temperature and humidity conditions A CO ₂ gas sensor 16a having a performance of −10 to 50 ° C. and 5 to 95% RH is used. In the CO ₂ gas sensor 16a of this specification, the measured value of the measured CO ₂ concentration is converted into volts (V) and output as measured value data.

The CO ₂ gas sensor control module 16b is located above the CO ₂ gas sensor 16a and is stably fixed to the upper part of the observation well 12. CO ₂ gas sensor control module 16b is connected via the CO ₂ gas sensors 16a and conductor 16d, which receives a measurement value output from the CO ₂ gas sensors 16a, various relative CO ₂ gas sensors 16a and the wireless network module 16c Control the operation. The CO ₂ gas sensor control module 16b incorporates a power source (not shown) (for example, a DC 5V power source), and also performs ON / OFF control for the CO ₂ gas sensor 16a and the wireless network module 16c. Then, information on the CO ₂ gas sensor unit itself is transmitted together with the measurement value via the wireless network module. The wireless network module 16c is a communication node capable of constructing an autonomous wireless network, that is, a bidirectional communication node that autonomously transmits and receives data, and has a radio frequency of 902 to 928 MHz and conforms to IEEE 802.15.4. It is preferable that the specifications be

An upper lid 12A is installed above the wireless network module 16c, that is, on the upper surface of the observation well 12, and thereby the influence of the outside air flowing into the observation well 12 on the measurement result of the CO ₂ concentration in the soil. Can be prevented.

  FIG. 3 is a block diagram showing the system configuration of the entire network in the soil remediation monitoring system according to the embodiment of the present invention, and is a schematic view of the soil remediation monitoring system as viewed from above.

When the wireless network module 16c of each CO ₂ gas sensor network unit 16, 16,... Is turned on, the wireless network module 16c automatically starts wireless communication, and other wireless network modules 16c, 16c,. The gateway 22 which is a communication means of the host computer 14 is sensed. When connected to the other wireless network modules 16c, 16c... And the gateway 22, a wireless network as shown by the broken line in FIG. This network can exchange data in both directions. Even if the wireless network modules 16c, 16c,... Are missing or increased even after being constructed, the wireless network modules 16c, 16c,. Is always done, so the latest network is always rebuilt automatically.

In this way constructed network, continuously measured CO ₂ gas concentration in each CO ₂ gas sensor network unit 16, 16 ..., each wireless network module 16c that comes from 16c ..., other CO ₂ The wireless network modules 16c, 16c of the gas sensor network units 16, 16... Are transmitted to the gateway 22 as relay points or directly.

  As shown in FIG. 3, the host computer 14 can be connected to another PC 52, a portable terminal such as a PDA 54, another network 56, and a database 58 via a LAN / WAN 50 line or connection terminal. It is preferable. Thereby, information can be centrally managed and used also in other terminals and remote locations.

    FIG. 4 is a plan view showing the monitor 28 when a screen which is an example of a monitoring result of soil purification is displayed.

4. Each enclosure line 20a, 20a... In the monitor 20 shown in FIG. 4 is an isoline showing each CO ₂ concentration. On the monitor 20, a screen indicated by an isoline connecting each CO ₂ concentration is displayed by switching in time series. In this way, by displaying the CO ₂ distribution of the contaminated soil as viewed from above on the monitor 20, it is possible to easily recognize the progress of soil purification.

  Next, the operation of the soil purification monitoring system 10 according to the embodiment of the present invention configured as described above will be described.

  When purifying contaminated soil contaminated with oil, the bioremediation method, which purifies by decomposing oil by activating microorganisms in contaminated soil, can be purified with little impact on the environment. It is often adopted because it can be done.

  In general, when soil purification is performed, it is first necessary to conduct monitoring to investigate the contamination status of contaminated soil or groundwater, and the soil purification work is started based on the survey results. And even during soil purification, soil or groundwater can be monitored regularly, and the progress of soil purification can be constantly monitored, so that more effective soil purification can be performed.

  As the above-mentioned monitoring method, a method in which a polluted area is bored, a part of the soil or groundwater is sampled, and a target pollutant is detected by a detector tube or gas chromatography is generally performed. . However, this monitoring method not only requires a lot of cost and labor, but also has a drawback that timely monitoring cannot be performed.

Therefore, the inventor of the present application pays attention to the point that when an oil that contaminates soil or groundwater is aerobically biodegraded by aerobic microorganisms, CO ₂ gas is generated in the decomposition process, and the concentration of CO ₂ gas in the soil The soil condition and the progress of soil purification in soil purification by aerobic microorganisms were monitored, and a method for soil purification was derived based on the results.

That is, if soil purification is in progress, the oil in the soil is decomposed and the microbial activity in the soil increases, so the CO ₂ concentration in the soil increases. On the other hand, when the soil purification is completed, the oil to be decomposed disappears and the microbial activity in the soil decreases, so the CO ₂ concentration in the soil also decreases. In this way, the CO ₂ concentration in the soil and the progress of soil purification have a correlation, so the change in the CO ₂ concentration is analyzed in time series to predict the state of the soil and the progress of soil purification. It becomes possible to do.

The inventor of the present application conducted the first and second tests described below in order to verify the soil remediation monitoring method using the CO ₂ gas concentration described above.

First, in the first test, the accuracy of the CO ₂ gas sensor used in the present embodiment was verified using the first experimental apparatus 60 shown in FIG.

As shown in FIG. 5, the first experimental device 60 supplied CO ₂ from below to a cylindrical column 62 with high sealing performance of φ100 mm × h200 mm and was used in the cylindrical column 62 in this embodiment. A CO ₂ gas sensor 16a was installed. The CO ₂ gas sensor 16a includes a power supply 64 that supplies power and a digital panel 66 that displays measured values.

The first experimental apparatus 60 is provided with a CO ₂ concentration meter 68 for comparison and verification. The CO ₂ concentration meter 68 sucks the internal CO ₂ from above the cylindrical column 62 by the attached suction pump 70 and measures the CO ₂ concentration. Measurements by the CO ₂ concentration meter 68 is the NDIR method using non-dispersive infrared measurement of CO ₂ concentration is performed. The measured value of the CO ₂ concentration meter 68 is displayed by an attached indicator 72.

In the first experiment 60 having the above structure, by changing the CO ₂ concentration is supplied to the cylindrical column 62, a comparison was made of the measured values of the CO ₂ concentration in the CO ₂ gas sensors 16a and CO ₂ concentration meter 68. The result is shown in FIG. FIG. 6 is a graph showing the correlation between the measured value of the CO ₂ gas sensor 16a and the measured value of the CO ₂ concentration meter 68 in the first test. The vertical axis shows the measured value of the CO ₂ concentration meter 68, and the horizontal axis Indicates the measured value of the CO ₂ gas sensor 16a.

As shown in the graph of FIG. 6, the CO ₂ gas sensor 16a used in the present embodiment and the CO ₂ concentration meter 68 have a substantially direct relationship, and the correlation coefficient R ² is as high as 0.99. Correlation is shown. As a result, it was proved that the CO ₂ gas sensor 16a used in this example has a high measurement performance similar to that of the NDIR system measurement using non-dispersed infrared rays.

Next, as a second test, the second experimental apparatus 80 shown in FIG. 7 is used to measure the CO ₂ concentration generated from the soil by aerobic microorganisms using the CO ₂ gas sensor 16a used in this embodiment. A verification test was conducted.

  As shown in FIG. 7, the second experimental apparatus 80 includes a beaker 84 in which 25 g of a soil sample 82 is put in a wet weight inside a cylindrical column 62 having a high sealability of φ100 mm × h200 mm, and the soil sample About 82 mL of nutrient salt used for soil purification as a nutrient salt was dissolved in 82 in a proper amount of pure water. Furthermore, it left still in the state which added 50 microliters of machine oil to the soil sample 82 as a sample of contaminated oil.

Inside the cylindrical column 62, the CO ₂ gas sensor 16a used in the present embodiment was installed. The CO ₂ gas sensor 16a includes a power supply 64 that supplies power, and a data logger 96 that displays and records measured values.

  The second experimental device 80 is provided with an outside air temperature meter 88 and an in-column thermometer 90 for investigating the influence of temperature, and the measurement result is sent to the thermo recorder 92 for display and recording. .

Further, in the second experimental apparatus 80, in order to investigate the influence of external air CO ₂ concentration, the outside air CO ₂ concentration meter 94 is provided. The outside air CO ₂ concentration meter 94 sucks outside air by the attached suction pump 70 and measures the CO ₂ concentration. As the outside air CO ₂ concentration meter 94, measurement is performed by the NDIR method using non-dispersed infrared rays, as with the CO ₂ concentration meter 68 of the first experimental apparatus 60. The measured value of the outside air CO ₂ concentration meter 94 is displayed by an attached indicator 72.

In the second test, the second experimental apparatus 80 described above was operated for 135 hours, and changes in the temperature and CO ₂ concentration were verified. The result is shown in FIG. FIG. 8 is a graph showing changes in each CO ₂ concentration and each temperature in the second test. In the graph of FIG. 8, ■ indicates the measured value of the CO ₂ gas sensor 16 a installed in the cylindrical column 62, ▲ indicates the measured value of the outside air CO ₂ concentration meter 94, and □ indicates that installed in the cylindrical column 62. The measured value of the in-column thermometer 90 is shown, and Δ shows the measured value of the outside air temperature meter 88. In addition, the description of "heating operation period" and "heating stop period" in the graph of FIG. 8 has shown the heating operation time in the laboratory used by the 2nd test.

As shown in the graph of FIG. 8, the average of the CO ₂ concentration in the outside air was 433 ± 40 ppm. On the other hand, the CO ₂ concentration in the cylindrical column 62 tended to increase although there was some attenuation, and the maximum value of the CO ₂ concentration was 2,220 ppm. On the other hand, the temperature change depends on the temperature variation of the laboratory due to the heating operation and is periodic.

From the graph of FIG. 6, the microbial activity increases in the soil sample 54 as the environmental temperature rises in the relationship between the temperature change and the CO ₂ concentration change, so that the CO ₂ concentration in the cylindrical column 52 increases. On the other hand, it was found that the microbial activity decreased as the environmental temperature decreased, and that the CO ₂ concentration did not change until the environmental temperature increased again.

Based on the results of the first and second tests, if the change in CO ₂ concentration is analyzed and investigated by adopting the soil remediation monitoring method of the present invention, the state of soil contaminated with oil and the soil by the bioremediation method It was proved that the progress of purification can be predicted easily and accurately.

In the embodiment of the present invention, the network is autonomously constructed by the wireless network modules 16c, 16c attached to the respective CO ₂ gas sensor network units 16, 16 .... The so-called node-based wireless network construction method is employed.

In a conventional network construction method using radio, that is, a so-called client / server type network, as shown in FIG. 9A, the host computer 14 and each CO ₂ gas sensor unit 16, 16. It is constructed by performing data communication. Accordingly, when there are obstacles 100, 100 such as buildings between the host computer 14 and the obstacles 100, 100, the wireless communication is hindered, so that the CO ₂ gas sensor unit 16 cannot transmit the measured value. ', 16' ... exists. In addition, if the distance from the CO ₂ gas sensor network unit 16 to the host computer 14 exceeds a predetermined distance that allows wireless communication, wireless data communication becomes difficult.

Therefore, conventionally, it has been considered to deal with a method of providing a data communication relay point or a method of connecting each CO ₂ gas sensor network unit 16, 16,... In addition, since the installation space must be secured, there is a problem in that the installation conditions of the monitoring equipment are limited.

On the other hand, in the network construction method of the present invention, as shown in FIG. 9B, each CO ₂ gas sensor network unit 16, 16... Autonomously senses and relays each CO ₂ gas sensor network unit 16, 16. A point network can be automatically constructed. Therefore, even if the obstacles 100, 100 exist linearly between the CO ₂ gas sensor network unit 16 and the host computer 14, each CO ₂ gas sensor network unit 16, 16,. As described above, each measurement value can be transmitted to the host computer 14. Further, even if the distance from the CO ₂ gas sensor network unit 16 to the host computer 14 is more than a predetermined distance capable of wireless communication, the optimum CO ₂ gas sensor network unit 16, 16. The relay point can be automatically selected and the measured value can be transmitted to the host computer 14. In addition, even if a new CO ₂ gas sensor network unit 16 is added or removed, sensing is performed through bidirectional data communication that is always performed in this network, so it is always up-to-date. Network can be rebuilt automatically. As a result, the labor required to construct the network can be greatly reduced.

Further, the host computer 14 and each CO ₂ gas sensor network unit 16, 16,. Therefore, the state of each CO ₂ gas sensor network unit 16, 16... Can be grasped by the host computer 14 based on the data transmitted from the CO ₂ gas sensor control module 16b via the wireless network module 16c. In addition, each CO ₂ gas sensor network unit 16, 16... Itself can be controlled by the host computer 14. Thereby, management of the soil purification monitoring system 10 whole can be performed simply and at low cost.

  In the soil purification monitoring system 10 described above, the number, shape, material, and the like of each device and member used are not particularly limited.

In the soil purification monitoring system 10, each CO ₂ gas sensor network unit 16, 16... Is arranged inside the observation well 12, 12. A hole excavated in the soil may be used as the observation well 12, such as a water injection well that performs water injection into the soil or a water pump well that performs pumping. Further, as in the soil purification monitoring system 10 ′ shown in FIG. 10, each CO ₂ gas sensor network unit 17, 17... Is buried at a depth of 1 to 2 m from the ground surface without providing an observation well. The present invention can be applied. However, the measurement accuracy and the like in the CO ₂ gas sensor network units 17, 17... Are different from those of the present embodiment and need to be changed.

Side surface sectional view which showed the whole structure of the soil purification monitoring system which is embodiment in this invention Expanded sectional view showing the structure of the observation well and the CO ₂ gas sensor network unit in the present embodiment The block diagram which showed the structure of the whole sensor network in the soil purification monitoring system which is embodiment of this invention The top view which showed the monitor when displaying the screen which is an example of the monitoring result of soil remediation Schematic configuration diagram showing a first experimental apparatus for demonstrating the present invention Graph showing correlation between measured value of CO ₂ gas sensor and measured value of CO ₂ concentration meter in first test Schematic configuration diagram showing a second experimental apparatus for demonstrating the present invention Graph showing changes in each CO ₂ concentration and each temperature in the second test Block diagram showing an example of conventional wireless network construction The block diagram which showed an example of the network construction by the wireless sensor network in this invention Side surface sectional drawing which showed the whole structure of the soil purification monitoring system which is a modification of embodiment in this invention

Explanation of symbols

10 ... soil remediation monitoring system, 12 ... observation wells, 14 ... host computer, 16 ... CO ₂ gas sensor network unit, 16a ... CO ₂ gas sensors, 16b ... CO ₂ gas sensor control module, 16c ... wireless network module, 60 ... First experimental device, 80 ... second experimental device, 100 ... obstacle

Claims (6)

In soil purification monitoring method for investigating the state of the soil and the progress of soil purification, when biodegrading the oil by aerobic microorganisms and soil purification for soil contaminated with oil,
Continuously detectable CO ₂ gas sensor of CO ₂ gas concentration in the soil, and located at a plurality of said soil,
The CO ₂ gas sensor continuously measures the CO ₂ concentration at a plurality of locations in the soil, and collects the measured values and sends them to a host computer for analysis,
A soil remediation monitoring method, wherein the progress of soil remediation is predicted from a time-series change of the CO ₂ concentration by the host computer based on the received measurement values of each CO ₂ gas sensor. The CO ₂ gas sensor includes a communication module that is a node capable of bidirectional data communication.
The soil purification monitoring method according to claim 1, wherein the host computer and the communication module have a network construction function for autonomously constructing a network using another communication module as a relay point. The soil purification monitoring method according to claim 1 or 2, wherein the CO ₂ gas sensor wirelessly performs data communication with the host computer. The host computer is any one of the preceding claims, wherein based on measurements from CO ₂ gas sensor, characterized by comprising display means for displaying the CO ₂ concentration distribution of the soil The soil remediation monitoring method described in 1. The soil remediation monitoring method according to claim 4, wherein the display means indicates the CO ₂ concentration distribution in the soil by an isoline. The display means, soil remediation monitoring method according to claim 4 or 5, characterized in that chronologically display the changes in the CO ₂ concentration in the soil.

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