• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.223-226
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• 2004

In this paper, removal of diesel hydrocarbons (C$_{10}$-C$_{22}$) for dry and moist soil was investigated so that microwave-enhanced soil vapor extraction(SVE) reduced soil treatment time and raised remediation efficiency. Kinetic constants of diesel hydrocarbons with microwave energy were 7 times on dry soil and 1580 times on moist soil as much as those of SVE process without microwave energy. The diesel removals were 67.7～78.4% for $C_{10}$ and $C_{12}$, and 0～18.5% for $C_{14}$～C$_{22}$ for dry and moist soil with SVE process only. On the other hand, dry soil with microwave-enhanced SVE process showed 89.3～99.4% removal for $C_{10}$ and $C_{12}$ and 35.6～67.0% for hydrocarbons over $C_{14}$. All hydrocarbons(C$_{10}$～C$_{22}$) studied were significantly removed (93.6～99.8%) for moist soil with microwave-enhanced SVE process. Almost all diesel hydrocarbons were usually considered as semi-volatile compounds(SVOCs). Microwave-enhanced SVE process might have a great potential for remediation of soils contaminated with SVOCs.OCs.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.382-388
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• 2005

Soil vapor extraction(SVE) is an effective and cost efficient method of removing volatile organic compounds(VOCs) and petroleum hydrocarbons from unsaturated soils. However, soil vapor extraction becomes ineffective in soils with low gas permeability, for example soils with air permeabilities less than 1 Darcy. Prefabricated vertical drains(PVDs) have been used for dewatering fine-grained soils for more than 25 years. Incorporating PVDs in and SVE system can extend the effectiveness of SVE to lower permeability soils by shortening the air flow-paths and ultimately expediting contaminant removal. The objective of the work described herein was to effectively incorporate PVDs into a SVE remediation system and to demonstrate a PVDs enhanced SVE system at full scale. The finding from this research will facilitate the design of field PVD-SVE systems in terms by providing insight into the optimal spacing between PVDs, the radius of influence of the wells and the flow rates to be used to capture and extract gas phase contaminants.

• Journal of the Korean Society of Hazard Mitigation
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• v.1 no.3 s.3
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• pp.83-92
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• 2001

Field investigations for subsurface soil and groundwater at a gas station showed that the site was severely contaminated and even petroleum compounds as free liquid state were observed. Pilot-scale soil flushing and soil vapor extraction process(SVE) were applied to evaluate the effectiveness of pollutants removal. Surfactant solution, Tween 80, was used to enhance the solubility of petroleum compounds and resulted in about 10 times increase on TPH(Total Petroleum Hydrocarbon) concentration. As for SVE method, maximum concentration of TPH and BTEX reached within 24 hours of extraction and then continuously decreased. Considerations on the groundwater level and the kinetic limitation for volatilization of contaminants have to be taken into account for the effective application of SVE process.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.04a
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• pp.80-81
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• 1999

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.354-355
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• 2003

In this study, a risk-based cleanup approach using the leaching potential was suggested for the soil vapor extraction (SVE) process. A multi-component model was adopted with local equilibrium assumption (LEA), and Raoult's law was applied to estimate the leaching potential for BTEX. Finally, a risk analysis was conducted based on the leaching pontential calculated. To complete the feasibility of this approach, more investigations and discussions will be required in future.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.9-18
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• 2007

Soil vapor extraction (SVE) is an effective and cost efficient method of removing volatile organic compounds (VOCs) and petroleum hydrocarbons from unsaturated soils. However, soil vapor extraction becomes ineffective in soils with low gas permeability, for example soils with air permeabilities less than 1 Darcy. Incorporating PVDs in an SVE system can extend the effectiveness of SVE to lower permeability soils by shortening the air flow-paths and ultimately expediting contaminant removal. The objective of the research described herein was to effectively incorporate PVDs into a SVE remediation system. The test results show that the gas permeability was evaluated for four different equivalent diameters, increasing the equivalent diameter results in a decrease in the calculated gas permeability. It was found that the porosity for the dry condition was greater than that of the wet condition and will allow flow rate for the same vacuum flow, offering a low resistance to the air flow.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.05a
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• pp.137-140
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• 2000

The purpose of this study is to see the effect of SVE (Soil Vapor Extraction) and Bioventing (biostimulation) hydrocarbon contaminated areas. The removal rate of VOC for three weeks were 17.43 kg on 3.6 ㎥/hr at steady-state. In the application of Bioventing, every flow rate were tested, and it was found that 4.0 ㎥/hr were adequate for best control of the system. At this stage, the addition of microbial agent accelerated the biodegradation of the hydrocarbon.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.137-147
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• 2008

Soil Vapor Extraction (SVE) has been extensively used to remove volatile organic compounds (VOCs) from the vadoze zone. In order to investigate the removal mechanism during SVE operation, laboratory modeling experiments were carried out and tailing effect could be observed in later stage of the experiment. Tailing effect means that removal rate of contaminants gets significantly to decrease in later stage of SVE operation. Also, mathematical model simulating the tailing effect was used, which considers rate-limited diffusion in a water film during mass transfer among gas, liquid, and solid phases. Measurement data obtained through the experiment was used as input data of the numerical analyses. Sensitivity analysis was performed to examine the effect of each parameter on required time to reach final target concentration. Finally, it was found that the concentration in the soil phase decreased significantly with a liquid and gas diffusion coefficient larger, actual path length shorter, and water saturation smaller.

• Journal of Soil and Groundwater Environment
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• v.9 no.2
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• pp.28-40
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• 2004

Box experiments were performed to evaluate the removal efficiency of SVE (soil vapor extraction) for gasoline in soil. An activated carbon sorption tower and a biofilter were operated as post-treatment processes to remove VOCs extracted from extraction wells of SVE. An acrylic resin box (65 cm${\times}$20 cm${\times}$30 cm) was used to make artificial soil layers and two injection wells and one extraction well were built for SVE process in the box. Gases from extraction wells flew into the activated carbon sorption tower or the biofilter. Gasoline concentrations of VOCs emitted from the extraction well were compared with those after post treatments. More than 92% of initial gasoline mass in soil were removed by SVE within few days, suggesting that SVE is very available to remove VOCs from contaminated soils. To treat VOCs from extraction wells of SVE, an activated carbon sorption tower and a biofilter were attached to SVE process and their gasoline removal efficiencies were measured. These post treatment systems lowered gasoline concentrations to below 1.0 ppm within few days. Average remediation efficiency was 98% of gasoline for the activated carbon sorption tower and 84.1% for the biofilter. The maximum removal capacity of a biofilter was 10.7 g/L/hr, which was ten times higher than general biofilter removal capacity. Results from the study suggest that the activated carbon sorption tower and the biofilter would be available for the post treatment process to remove VOCs generated from SVE process.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.250-252
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• 2002

The goals of environmental monitoring are to locate and quantify the significant contamination, estimate the fate and transport, estimate the potential exposure and risks to humans and the environment, and track the performance of various remedial technologies. In this study, ceramic gas sensor system is proposed to enhance the effectiveness of soil vapor extraction (SVE) process by monitoring the effluent gas. SVE is a technique that is widely used to remediate unsaturated soils contaminated with volatile organic contaminants. The sensor response for benzene, toluene, and xylene, the representative effluent gas compositions of SVE process, was evaluated using the proposed sensor system. As a result, it was verified that the response of sensor was increased or decreased very sensitively according to the change of the effluent gas concentration. Besides, the sensor could detect the difference over a wide range of concentration and it was more sensitive in order of xylene, toluene, and benzene. It is expected that this VOC analysis method results in field monitoring costs saying and appropriate immediate action for process control. More detailed experiments are being conducted in our research group.