• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.29-32
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• 2004

Gaseous partitioning tracer test has been used for determining the volume and spatial distribution of residual non-aqueous phase liquid (NAPL) in the unsaturated soils. In this study, an experimental method for measuring the content of gas-exposed NAPL as well as that of total NAPL in a sand during air sparging was developed. Two different gaseous phase NAPL-partitioning tracers were used; n-pentane, with very low water solubility, was used as the tracer that partitions into NAPL that is only in contact with the mobile gas, and chloroform, with fairly good water solubility, was selected for detecting total NAPL content in the sand. Helium and difluromethanewere used as the non- reactive tracer and water-partitioning tracers, respectively. Using n-decane as a model NAPL (NAPL saturation of 0.018), 25.6% of total NAPL was detected by n-pentane at the water saturation of 0.68. Oniy 9.1% of total NAPL was detected by n-pentane at the water saturation of 0.84. This result implies that the quantity of gas-exposed NAPL increased about three times when the water saturation decreased from 0.84 to 0.68. At the water saturation of 0.68, more than 90% of total NAPL was detected by chloroform while 65.8% of total NAPL was detected by chloroform at the water saturation of 0.84. Considering that the removal rate of NAPL during air sparging for NAPL-contaminated aquifer is expected to be greatly dependent upon the spatial arrangement of NAPL phase with respect to the mobile gas, this new approach may provide useful information for investigating the mass transfer process during air-driven remedial processes fer NAPL-contaminated subsurface environment.

• Journal of Soil and Groundwater Environment
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• v.13 no.3
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• pp.45-51
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• 2008

Removal of nonaqueous phase liquid present in the soil column by using cosolvent floods was investigated. The first objective of the study was to elucidate the removal mechanism of cosolvent flooding for benzene-NAPL. The second objective of the study was to evaluate the effects of the alchohol partitioning type (NAPL swelling and non-swelling) and concentration on NAPL removal efficiency from the soil column. The main NAPL removal mechanism of swelling alcohol was mobilization, while that of non-swelling alcohol was NAPL dissolution. The NAPL removal efficiency of swelling alcohol was more effective than that of non-swelling alcohol. Removal of Benzene NAPL entrapped in the soil would be effective under the cosolvent flood condition of alcohol content greater than 40% in volume.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1095-1101
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• 2008

Nonaqueous phase liquids (NAPL) are the continuous source for soil and groundwater contamination. The first objective of the study was to verify the effect of co-injection of cosolvent and air on NAPL removal from soil-column system. The second objective of the study was to investigate the effect of alcohol-partitioning property on the NAPL removal by the co-injection process of cosolvent and air. Enhanced removal of benzene-NAPL by the co-injection process of ethanol and air was also verified within the soilcolumn system. However, the co-injection process of Tert-butanol (TBA) and air showed no enhancement of benzene-NAPL removal. This study found that the viscous pressure of TBA was so higher than the capillary pressure and TBA easily displaced the benzene-NAPL and air present in soil pores. Air of the coinjection process did not work for NAPL removal but hindered NAPL mobilization. NAPL partitioning property and viscous pressure of cosovlent should be considered for application of the co-injection process of cosolvent and air.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.3
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• pp.40-47
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• 2009

Coinjection of alcohol and air or alcohol flooding only were evaluated with 3-D soil tank for removal of nonaqueous phase liquid (NAPL) contaminant from soil. 70%-ethanol and 40%-isopropanol were used for non-NAPL-swelling alcohol and NAPL-swelling alcohol, respectively. 729 ml-benzene was placed in the 37 liter soil tank. Alcohols were respectively injected from the injection well placed near the bottom of the tank and mobilized free phase NAPL and aqueous phases were then recovered from the extraction well placed in the upper part of the soil tank. Approximately 50% of removed NAPLs were free-phase in all experiments. The results were completely different to the previous soil column experiment results and also implied that alcohol properties did not affect the NAPL removal efficiency in the 3-D soil tank experiment. Air was also co-injected with alcohol to evaluate co-injection effects on NAPL removal. Enhanced NAPL removal effect of co-injection of 70%-ethanol and air was also found even in the 3-D soil tank evaluation. However, co-injection effect of 40%-iso-propanol and air was less apparent. This study determined that the most important parameter governing alcohol flooding for NAPL removal would be extraction capacity to recover NAPL and aqueous phase flowing in the soil. More researches are required for improving recovery efficiency of extraction well in real soil contamination conditions.

• Journal of Korea Water Resources Association
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• v.30 no.5
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• pp.459-465
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• 1997

The possibility of NAPL removal from contaminated soil was studied using the steam injection technique. Both single (octane, toluene and xylene) and composite NAPL (gasoline) were used as contaminant. Soils used in this study were Chumunjin fine sand and weathered granitic soil, both of which are commonly found in Korea. Experimental results showed that with 1 pore volume steam injection, the NAPL removal rate was in the range of 66∼78% for sand and 45∼73% for weathered granitic soil. The steam injection technique seems to have high potential for soil remediation with advantages of relatively short operating time and no side-effect. Rise in the background temperature led to the delay of steam condensation and the increase of NAPL mobility, which resulted in the improvement of removal efficiency. In addition, water flooding after steam injection turned out to be a very efficient way of removing NAPL residual in the soil pores.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.176-179
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• 2001

비 수용성 유기오염물(NAPL; non-aqueous phase liquid)로 오염된 불균질 토양을 계면활 성제를 이용하여 정화할 경우 효율성을 알아보기 위해 칼럼 및 박스 실험을 실시하였다. 불 균질한 지하 내부구조는 정화효과에 커다란 영향을 끼치는 것으로 알려져 있으나 이에 대한 연구는 매우 미비한 형편이다. 2차원 불균질 분포를 잘 나타내주는 박스실험을 통하여 실제 지하매질에 가까운 조건에서 실험을 실시하였다. PCE(tetrachloroethylene)와 xylene이 NAPL로 올리에마이드(01eamide)가 비이온-계면활성제로 이용되었으며, 1%용액과 증류수를 주입하여 NAPL을 세정하였고 가스크로마토그래피를 이용하여 NAPL의 농도를 분석하였다. 계면활성제를 주입할 경우가 증류수를 주입할 때보다 최대유출농도가 약 200배 정도가 높게 나타났으며 빠른 시간 내에 대부분의 NAPL이 정화되었다. 본 실험을 통하여, 불균질 매질에서의 계면활성제를 이용한 토양세정방법의 효율성이 정량화 되었으며, 계면활성제를 이용한 채수주입법의 현장 적용가능성을 확인하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1B
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• pp.97-103
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• 2009

The decompostion characteristics of NAPL TCE in cement/slag/Fe(II) system were studied with various TCE concentration and amounts of binders (cement/slag) For analyses of the TCE degradation by cement/slag/Fe(II), TCE solution injected using gas-tight syringe after TCE solution dissolved a methanol. Initial concentrations of TCE are 0.42 mM, NAPL condition 11.7 mM and saturated condition 16.8 mM respectively. The result showed that the cases of 8.4 mM and 4.2 mM are decreased 88% of total TCE concentration within 18 days. NAPL condition 11.7 mM was decreased 84% within 50 days and saturated condition 16.8 mM was decreased 60% of total TCE concentration within 60 days respectively. This showed that degradations of TCE in various concentrations were in one kind reaction as pseudo-first-order. TCE was dissolved as aqueous solution before degraded. The reaction rate was increased $0.12day^{-1}$, $0.24day^{-1}$, $0.31day^{-1}$ when the mass of media 0.1, 0.2, 0.3 S/L rate was increased. TCE reaction speed is affected by cement/slag surface ares in this system. When HDTMA, experimental facter, was added, TCE decomposition rate was high despite the high concentration of NAPL. and The decompostion characteristics of NAPL TCE in cement/slag/Fe(II) system were studied by using modeling.

• Journal of Soil and Groundwater Environment
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• v.13 no.6
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• pp.40-49
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• 2008

Matrix diffusion from planar fractures was studied mathematically and through physical model experiments. Mathematical models were developed to simulate diffusion from 2D and 3D instantaneous disk sources and a 3D continuous disk source. The models were based on analytical solutions previously developed by Carslaw and Jaeger (1959). The mathematical simulations indicated that the 2D scenario produces significantly different results from the 3D scenario, the time for mass disappearance is significantly larger for continuous sources than for instantaneous sources, the normalized concentration generally decreased over time for instantaneous sources while it increased over time for continuous sources, diffusion rates decrease significantly over time and space, and the normalized mass loss from the source zone never reaches 1 for continuous sources due to the semi-infinite integral. The simulations also showed that disappearance times increase exponentially with increasing source radii and matrix porosity, and decrease with increasing aqueous-phase NAPL solubilities.

• Food Science and Preservation
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• v.4 no.3
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• pp.323-330
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• 1997

Changes in antioxidative substance levels in eleven different cultivars of persimmon leaves during growth were investigated. In general, the contents of soluble phenols, L-ascorbic acid and flavonoids in astringent persimmon leaves(APL) were higher than those of nonastringent persimmon leaves(NAPL). The soluble phenol contents in APL and NAPL showed a tendency to decrease throughout leaf growth. L-ascorbic acid content in APL decreased rapidly during growth, whereas its content in NAPL reached its highest value at the late of July, and then decreased rapidly. Major flavonoids in APL and NAPL were quercetin and Kaempferol which were present in conjugate forms. Before acid hydrolysis, the contents of kaempferol and quercetin in APL and NAPL remained at a relatively constant level until the late of July, and then decreased slightly. After acid hydrolysis, kaempferol contents in APL and NAPL varied significantly by cultivar and growth stage, while quercetin contents decreased slowly until the late of July, and then increased drastically, reached a maximum at the early of August, afterward continuously decreased. These results suggest that APL harvested at the early of June may be useful as potential sources of natural antioxidants.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.159-162
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• 2002

Innovative and nondestructive characterization techniques have been developed to locate and quantify nonaqueous phase liquids (NAPLs) in the vadose and saturated zones in the subsurface environment. One such technique is the partitioning interwell tracer test (PITT). The PITT is a simultaneous displacement of partitioning and non-partitioning tracers through a subsurface formation. Partitioning tracers will partition into the NAPL during their transport through NAPL-contaminated formations. Mean travel times of partitioning and non-partitioning tracers are used to estimate the quantity of NAPL encountered by the displaced tracer pulse. Travel times are directly proportional to the partitioning coefficient and the volume of NAPL contacted in the subsurface environment. This paper discusses the conceptual background, design and implementation of PITTs. (This document has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency, and no official endorsement should be inferred.)