KR20100085865A - Multi-functional well suitable for in-situ integrated treatment of soil and ground water - Google Patents

Abstract

PURPOSE: A multifunctional tube well for an integrated process of processing the subsurface water and soil underground is provided to increase the efficiency of a soil cleaning process on the soil layer of the pollution area. CONSTITUTION: A multifunctional tube well for an integrated process of processing the subsurface water and soil underground comprises a tube well casing and a horizontal pipe for injecting a surface active agent(400). The tube well casing comprises a connection pipe(100) for an aquifer, a connection pipe(200) for an unsaturated layer and an LNAPL extraction column(300). The horizontal pipe for injecting a surface active agent is extended vertically to the tube well casing. The horizontal pipe for injecting a surface active agent is located the unsaturated layer or a sand layer formed on the top of the unsaturated layer.

Description

Multi-functional well suitable for in-situ integrated treatment of soil and ground water}

The present invention relates to a multi-purpose well applicable to a complex or integrated process applied for in situ treatment of soil and groundwater contaminated with contaminants such as oils and chlorinated organic compounds. In addition, the present invention relates to a well structure that can improve the purification efficiency by allowing substances such as surfactants to be injected for the purification process to be uniformly transferred to the contamination point.

The main organic pollutants at home and abroad (soil and groundwater) are total petroleum hydrocarbon (TPH), benzene, toluene, ethylbenzene, xylenes (BTEX), and chlorinated aliphatic hydrocarbons (CAHs). Examples include Soil Flushing, Air Sparging, Soil Vapor Extraction, In Situ Bioremediation, and In Situ Advanced Oxidation.

Conventional contamination top floor (soil and groundwater) in situ restoration integrated process system is commonly composed of injection, well, extraction, monitoring, and extraction contaminant treatment system, each of which is characterized by contaminant characteristics, pollutant presence Combinations can be made according to the nature (weather, water soluble, solid, water insoluble), the location of contamination (soil, groundwater or smear zone) and process characteristics.

When conventional top-level restoration processes are applied to contaminated sites, single purpose injection wells or injection devices designed for the application of each single process (liquid or gaseous substances injection to induce physical, chemical, and biological removal of contaminants) ), Extraction wells or extraction equipment (such as liquid or gas residues remaining after removal of pollutants and liquid or gaseous water-insoluble pollutants) and observation wells have been installed and operated separately. Such well systems include commonly used well functions and devices (injection material storage and mixing tanks, extract storage and separation tanks, flow meters, pressure gauges, safety devices, etc.). However, until now, the wells, injection and extraction devices have been designed and constructed according to each process, and the number of installation wells is increased because other processes need to be applied or integrated facilities should not reuse existing wells or devices. The cost of installation and the maintenance and management of each well are redundantly used, resulting in increased restoration costs.

On the other hand, in the prior art, the wells have been developed for injecting surfactants through horizontal tubes, but most of them have been developed for the purpose of injecting surfactants. Therefore, research and development on the surfactant injection horizontal tube that can be linked with other processes is required.

In the conventional case where the surfactant is injected by using a horizontal tube, the transfer of the surfactant is greatly influenced by the permeability coefficient of the soil around the horizontal tube. In other words, if the surrounding soil is a soil with a high permeability coefficient, the surfactant is transported without any delay and there is no problem in the process application. However, when low permeability soils or soils with different permeability coefficients are mixed, the surfactant injected through the horizontal pipe is transferred only to the soil with a high permeability coefficient and is not transferred to the low permeability soil. There is a limit to injecting the surfactant homogeneously throughout. Even when the high permeability soil is present in the upper part of the horizontal pipe as well as when the low permeable soil is disturbed according to the horizontal pipe installation, the surfactant is not transported to the ground but rather to the ground surface. Therefore, a situation that needs to be able to supply a homogeneous surfactant to the contaminated area.

On the other hand, in the case of installing a conventional well, the permeability coefficient between the borehole and the well casing is filled with a good sand pack, and it is common to grout with bentonite, an impermeable layer only at the top. In this case, liquid / gases such as surfactants and electron donors that are injected through the screen for the purification process are transferred to the soil layer through the sand layer having a good permeability coefficient. There is a lot of difficulties in applying the process because it does not move to the permeable layer but only to the soil layer with a large permeability coefficient. Therefore, in order to overcome the limitations of processing efficiency and economics of the single treatment process, it is necessary to develop an integrated process system, and to this end, research and development on multi-purpose and multi-functional integrated judgment applicable to the integrated system is required.

In order to solve the problems of the prior art as described above, by conducting a study on the integrated wells that can be operated by integrating the wells that were installed and operated by each individual process, it can be used as injection / extraction wells, injection / tube measurements, or extraction / tube measurements. The technology has been developed to increase the efficiency of integrated process systems through the improvement of multifunctional integrated control and hydraulic flow.

Therefore, an object of the present invention is to provide a multi-functional well structure that can be operated by integrating the wells that were installed and operated by individual processes.

It is another object of the present invention to provide a method of installing the well so that the wells can achieve the efficiency of the soil cleaning process for the soil layer and aquifer in the contaminated area.

Functional wells according to the present invention for achieving the above object, the wells casing, including a connecting pipe for aquifer, unsaturated pipe connecting pipe, and LNAPL extraction pipe; And a horizontal pipe for injecting surfactant extending in the water direction relative to the well casing, wherein the horizontal pipe for injecting surfactant is positioned on an unsaturated layer of soil or a sand layer provided on the unsaturated layer. .

In addition, the installation method of the multi-purpose well structure for achieving another object of the present invention comprises the steps of forming a boring ball in the field; Installing a well casing including the aquifer connection pipe, the unsaturated layer connection pipe, and the NAPL extraction pipe in the boring hole; And extending the horizontal tube in the repair direction of the well casing.

According to the present invention, by improving a single well performing a single function into a multifunctional well that functions as injection, extraction and monitoring, the number of wells and the injection / extraction device can be greatly reduced compared to conventional wells. In addition, aquifers, unsaturated layers and LNAPL and the like can be simultaneously processed to greatly reduce the cost and duration of restoration of the top layer.

In addition, by installing a surfactant-injected horizontal pipe connected with a multi-functional well and a sand and impermeable layer around the horizontal pipe, which increases the equal supply of surfactants, it is easy to improve the efficiency of the soil cleaning process and to integrate the process with other processes. .

In addition, by adjusting the bentonite and sand layer installation positions around the well casing, the effect of injecting the material into the low permeable layer can be improved, thereby increasing the efficiency of the process.

1 is a cross-sectional view of a multifunctional composite well according to an embodiment of the present invention.
2 is a photograph of a multifunctional compound tablet of the present invention.
3 is a photograph of the multifunctional composite well of the present invention installed on a pilot scale model in which soil and groundwater layers are formed.
Figure 4 is the dissolved oxygen, toluene concentration changes in the soil layer (upper layer) / groundwater layer (middle layer and lower layer) before and after the injection of oxygen gas through the multi-function composite well of the present invention.
5 is a plan view of a multifunctional composite well according to an embodiment of the present invention, and is a photograph installed on the model.
6 is a toluene concentration distribution in the model soil layer gas before and after the injection of surfactant through a multifunctional composite functional horizontal pipe.
Figure 7 is an installation of the bentonite and sand layer of the well according to the prior art.
8 is an installation view of the bentonite, sand layer and Packer of the well according to an embodiment of the present invention.

Hereinafter, the technical configuration of the present invention to be described in more detail. As described above, the present invention relates to a multi-purpose well applicable to a complex or integrated process for applying in situ to contaminated soil and groundwater, and the functional well according to the present invention comprises a connector for aquifer, A connection pipe for an unsaturated layer, and a well casing including a LNAPL extraction tube, and a horizontal tube for surfactant injection extending in a direction perpendicular to the well casing casing.

In the above, LNAPL refers to a liquid organic compound that is relatively insoluble in water. NAPLs can be divided into light nonaqueous-phase liquids (LNAPLs) and heavy nonaqueous-phase liquids (DNAPLs) based on the density of water. do. Since LNAPLs are lighter than water, they are mainly distributed in unsaturated areas above the water table and include gasoline, kerosene, jet fuel, benzene, and toluene. In contrast, DNAPLs are more specific than water, contaminating not only saturated areas but also cracks in underground rocks. DNAPLs, in particular, have very low solubility but are very toxic and can be soil pollutants that can be contaminated over a large area even in small amounts. DNAPLs are generally chlorine solvents such as trichloroethylene, methylene chloride, trichloroethane and dichlorobenzene.

According to the present invention, as shown in FIG. 1, by installing various tubes serving as injection, extraction, and monitoring in a single well, the number of wells can be significantly reduced compared to the well-bearing well-being wells system. . In addition, the treatment of aquifer, unsaturated layer and LNAPL and the like can be performed at the same time, thereby greatly reducing the cost and duration of restoration of the top layer.

1 is a cross-sectional view of the multi-function composite well according to an embodiment of the present invention, aquifer connection pipe, that is, liquid and gaseous substance injection / extraction and groundwater sampling monitoring tube 100 is installed in the target position of the aquifer bed liquid phase (Oxidants, electron donors, nutrients and microorganisms, etc.) and gaseous (oxygen, propane gas, etc.) materials can be supplied, or ground water can be extracted or used for sampling. To this end, the aquifer connection pipe may further include a pump for injection and extraction, and may include only a pump for extraction, and a vacuum pump may be used as the pump. In addition, the unsaturated layer connecting tube, that is, the unsaturated layer liquid and gaseous substance injection / extraction and surfactant injection tube 200 is installed on the unsaturated soil side of the liquid phase (surfactant, oxidant, nutrients and microorganisms, etc.) and gas phase ( Oxygen or the like) or, conversely, the gas phase (volatile contaminants, air, etc.) of the unsaturated layer can be extracted and used to monitor the state of the unsaturated layer. To this end, the unsaturated layer connection tube, like the aquifer connection tube, may be further provided with a pump for injection and extraction, may be provided with only the pump for extraction, a vacuum pump may be used as the pump.

The LNAPL extraction pipe 300 is installed for the purpose of extracting low-density water-insoluble substances present in the groundwater surface, and at the same time, it can also extract and remove high-concentration oil pollutants absorbed by the surfactant injected for purification of unsaturated soil layer. . Therefore, the LNAPL extraction tube 300 is configured to be located at the interface (ground surface) of the unsaturated layer and the aquifer layer. It is preferable that the LNAPL extraction tube also has an extraction pump.

According to the configuration described above, unlike the existing structure in which a single wells corresponding to the injection hole, the extraction hole and the observation hole must be installed separately, if only the use mode is changed on the ground, a well can play the role of the three holes. As a result, the number of wells can be greatly reduced. In addition, in the past, the well structure for aquifer (groundwater) treatment and unsaturated layer (soil layer) treatment was different from each other, and had to be installed and operated separately. However, if the multifunctional well is installed, a process capable of simultaneously purifying soil and groundwater can be applied. Not only the cost of installation and operation, but also the overall restoration costs and periods can be greatly reduced.

FIG. 2 is a photograph of a multifunctional composite functional well and tubes installed in the casing, which are manufactured for testing in a model of a pilot-scale soil / groundwater layer based on the design of FIG. 1. FIG. A picture of a multifunctional composite well installed on a model of soil / groundwater layers. Some results of testing the multifunctional composite functional tablet are presented in FIG. 4. FIG. 4 shows the dissolved oxygen in the groundwater intermediate layer (M4_2) and the lower layer (M4_3) dissolved in toluene around the composite functional well after 2.5 hours of injecting oxygen gas through the injection pipe for aquifer installed in the multifunctional composite well. , DO) and toluene concentration changes, and DO and toluene concentrations in the soil layer (M4_1). The dissolved oxygen concentration was about 5 mg / L before the start of oxygen gas injection in the integrated well, but after 7 hours of injection, the dissolved oxygen concentration was about 27 mg / L in the middle layer (M4_2) and about 16 mg / L in the lower layer. Dissolved oxygen concentrations increased.

Toluene concentrations in the middle and lower aquifers (M4_2 and M4_3) decreased by about 22% and 51%, respectively, after oxygen injection through the multifunctional integrated functional wells. The toluene concentration in the unsaturated layer (M4_1) was increased by transporting the aquifer toluene to the soil layer by the oxygen gas aquifer injection. These results indicate that the injection of oxygen gas from the multifunctional integrated functional well was effectively performed at the target of the aquifer, and that the multifunctional combined well performed well.

Conventionally, a bioslurping process tube or the like for removing the LNAPL has to be separately installed, but according to the present multi-function well structure, such process tube installation is unnecessary. In addition, conventionally, a high concentration of oil pollutant extraction wells generated when the unsaturated layer is treated by using a surfactant has to be separately installed, but it is possible to extract by the multifunctional wells of the present invention having the structure as described above.

In order to restore pollution of soils and aquifers contaminated with high concentrations of oil, including LNAPL, LNAPL is usually used for soil flushing or bioslurping, while high concentrations are for oil vapor extraction and air sparging. In order to treat low concentration oils sequentially using In Situ Bioremediation, in conventional well systems, surfactant injection wells, NAPL extraction tubes, air extraction wells, air injection wells and liquids (nutrients, etc.) Injection wells, groundwater wells and observation wells should be installed and operated separately. However, in the present invention, the liquid and gaseous substance injection / extraction and groundwater sampling monitoring tube for aquifer (100, briefly referred to as' aquifer for aquifer), unsaturated layer liquid and gaseous substance injection / extraction and surfactant injection tube 200 And it is designed to include both the LNAPL extraction tube 300 can be greatly reduced the number of wells. Although not limited, preferably, the surfactant solution may be selected from the group consisting of sorbitan mono oleate among nonionic surfactants satisfying both biodegradability, efficiency, economy, and workability.

The well structure according to the present invention is provided with a horizontal pipe 400 for surfactant injection in connection with the well, so that it is not necessary to separately install a surfactant injection pipe only for a soil flushing process, and the soil using the horizontal pipe. After the cleaning process, it becomes easy to apply the integrated process with other processes using the multi-functional crystal. The surfactant injection horizontal pipe may be located directly on the unsaturated layer of the soil, and artificially inserting sand having a high permeability coefficient (for example, 6.0 cm / min or more) on top of the unsaturated layer to form a sand layer. After making it, it is also preferable to be located in the sand layer. On the other hand, two or more surfactant injection holes are formed in the horizontal pipe for surfactant injection along the longitudinal direction of the horizontal pipe, so that the surfactant can be effectively supplied to the unsaturated layer of the soil.

Method for installing a multi-function well structure according to the present invention comprises the steps of forming a boring ball in the pollution site; Installing a well casing including the aquifer connection pipe, the unsaturated layer connection pipe, and the NAPL extraction pipe in the boring hole; And extending the horizontal tube in the direction of repair of the well casing. According to the method, preferably, the method may further include filling sand between the boring hole and the well casing.

As shown in Figures 1 and 5, the surfactant injection horizontal tube is installed extending in the water direction in the direction of the wells casing, when installed, the coarse sand (500) having a large permeability coefficient is injected around the horizontal tube, the horizontal The tube is buried by sand 500.

By the above configuration, the permeability coefficient around the horizontal pipe can be increased, and an impermeable aberration membrane 600 is installed outside the coarse sand layer except the lower portion of the injected sand layer so that the surfactant is evenly injected into the soil layer. The main direction of movement of the surfactant is induced to be perpendicular.

Figure 6 shows the distribution of toluene concentration in the model soil layer before and 27 hours after injection when the surfactant was injected through the multifunctional integrated functional well horizontal tube. Analysis of soil gas sample before surfactant injection showed an elliptic concentration distribution and high concentration at the point of artificial toluene injection. The maximum concentration of initial toluene was measured at 28. 5 mg / L and the toluene concentration decreased over time, and the toluene concentration in the soil layer was 4.5-7.4 mg / L after 27 hours of surfactant injection. This result indicates that toluene in the soil layer was removed relatively evenly by surfactant injection through the horizontal pipe, which means that the horizontal pipe for surfactant injection effectively performed the intended function.

On the other hand, push-pull transport experiments were carried out by injecting tracers of bromide and surfactant into the soil layers with different permeability coefficients at similar concentrations and flow rates, and bromide was found in soils with relatively high permeability coefficients (2.23 cm / min). Nearly 95% was recovered, but only about 40% was recovered in low permeability soils (0.04 cm / min). In the case of surfactants, the recovery rate in low permeability soils was very small. As such, when soils having different permeability coefficients are mixed, the injected material is mainly moved to the soil having a large permeability coefficient, thus making it difficult to supply a homogeneous material.

Similarly, toluene and oxygen were supplied at similar concentrations and flow rates under the same conditions as the above experiments. As a result of a push-pull transport experiment, 80% toluene and 75% oxygen were recovered in a soil with a relatively high permeability coefficient. Only about 30% of each was recovered in low permeability soils.

This may be related not only to the permeability coefficient of the soil around the well but also to the sand layer installed between the well borehole and the well casing. That is, the permeability coefficient of the sand layer installed in the conventional well as shown in Figure 7 is very large compared to the general aquifer permeability coefficient. Therefore, when the injected material is injected through the well, the solute introduced into the sand layer outside the well is moved vertically to the soil layer having high permeability, that is, a high permeability coefficient or head difference due to the high permeability of the sand. Therefore, the vertical movement of solutes in the sand layer is considered to be an important factor in increasing the difference of the solute concentrations in each soil layer and the solute preference flow of the aquifer. Therefore, it will be possible to move the material to the low permeable layer by preventing the flow of the material moving along the sand layer at the location where the low permeable layer is present.

Accordingly, as shown in FIGS. 1 and 8, the bentonite layer 700 around the well and the well of the well is disposed so that the bentonite layer 700 around the well may be disposed in the sand layer 800 generally provided around the well during injection / extraction. Preventing vertical movement of the injection / extract material facilitates movement to the low permeable layer.

As described above, the well provided according to the present invention is a multi-purpose well that can perform the injection, extraction, and monitoring functions required for each process in one well, and can greatly reduce the number of installation wells, thereby reducing installation and maintenance / management costs. It is possible to reduce the cost, and it is not necessary to design the wells separately according to the pollution site conditions, and the method can be changed without installing additional wells according to the degree of pollutant removal. In addition, the process of purifying soil and groundwater at the same time can be applied, which can greatly reduce the purification cost and purification period. In addition, it is possible to increase the treatment efficiency of the application process by improving the injection method of a substance such as a surfactant.

100: connector for aquifer 200: connector for unsaturated layer
300: LNAPL extraction tube 400: surfactant injection horizontal tube
500: coarse sand layer 600: impermeable liner

Claims (11)

Well casings, including aquifer connectors, unsaturated bed connectors, and LNAPL extraction tubes; And a horizontal pipe for surfactant injection, which extends in a direction perpendicular to the well casing, wherein the horizontal pipe for surfactant injection is located in an unsaturated layer of soil or a sand layer filled on the unsaturated layer. Multifunctional well structure made. The multifunctional well structure of claim 1, wherein the connection pipe for aquifer further comprises a pump for injecting, extracting, and monitoring liquid or gaseous substances in the aquifer. The method of claim 1, wherein the connection pipe for the unsaturated layer injects a liquid or gaseous material into the unsaturated layer, and extracts a sample of the soil and extract gas of the unsaturated layer in order to monitor the state of the unsaturated layer according to the injected material A multifunctional well structure, further comprising a pump for use. The multi-functional well structure of claim 1, wherein the well case further comprises at least one packer and a gas injection line for supplying nitrogen gas to the packer. The multifunctional crystal structure according to claim 1, wherein the surfactant injection horizontal tube is formed with two or more surfactant injection holes in the longitudinal direction of the horizontal tube. Forming a boring ball at the pollution site;
Installing a well casing including a connection pipe for aquifers, a connection pipe for unsaturated layers, and an LNAPL extraction tube in the boring hole; And
And a horizontal pipe extending in the direction of repair of said well casing. The method according to claim 6, wherein the method further comprises the step of filling sand between the boring ball and the well casing casing. The method of claim 6, further comprising the step of burying the coarse sand layer around the horizontal tube to bury the horizontal tube. The method of claim 8, further comprising the step of installing an impervious aberration membrane so as to surround the upper and side portions of the coarse sand layer. The method of claim 6, wherein at least one packer is further provided in the well case to separate the permeable layer. The method according to claim 10, wherein the position corresponding to the packer position in the space between the well case and the boring hole is filled with a bentonite layer.

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