• Journal of Environmental Science International
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• v.17 no.1
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• pp.97-105
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• 2008

This study examined the contaminated soils with an indicator of TPH using SVE (Soil Vapor Extraction) and biological treatments. Their results are as follows. Water content in the polluted soils slowly decreased from 15% during the initial experimental condition to 10% during the final condition. Purification of polluted soils by Bioventing system is likely to hinder the microbial activity due to decrease of water content. Removal rate of TPH in the upper reaction chamber was a half of initial removal rate at the 25th day of the experiment. The removal rate in the lower reaction chamber was 45% with concentration of 995.4 mg/kg. When the Bioventing is used the removal rate at the 14th day of the experiment was 53%, showing 7 day shortenting. Since the Bioventing method control the microbial activity due to dewatering of the polluted soil, SVE method is likely to be preferable to remove in-situ TPH. The reactor that included microbes and nutrients showed somewhat higher removal rate of TPH than the reactor that included nurtients only during experimental period. In general, the concentration showed two times peaks and then decreased, followed by slight variation of the concentration in low concentration levels. Hence, in contrast to SVE treatment, the biological treatment tend to show continuous repetitive peaks of concentration followed by concentration decrease.

• Journal of Soil and Groundwater Environment
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• v.25 no.2_spc
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• pp.1-15
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• 2020

Monitoring and assessing terminal electron accepting processes (TEAPs) are one of the most important steps to remediate contaminated sites via various in-situ techniques. TEAPs are a part of the microbial respiration reactions. Microorganisms gain energy from these reactions and reduces pollutants. Monitoring TEAPs enables us to predict degradability of contaminants and degradation rates. In many countries, TEAPs have been used for characterization of field sites and management of groundwater wells. For instance, US Environmental Protection Agency (EPA) provided strategies for groundwater quality and well management by applying TEAPs monitoring. Denmark has also constructed TEAPs map of local unit area to develop effective groundwater managing system, particularly to predict and assess nitrogen contamination. In case of Korea, although detailed soil survey and groundwater contamination assessment have been employed, site investigation guidelines using TEAPs have not been established yet. To better define TEAPs in subsurface environments, multiple indicators including ion concentrations, isotope compositions and contaminant degradation byproducts must be assessed. Furthermore, dissolved hydrogen concentrations are regarded as significant evidence of TEAPs occurring in subsurface environment. This review study introduces optimal sampling techniques of groundwater and dissolved hydrogen, and further discuss how to assess TEAPs in contaminated subsurface environments according to several contamination scenarios.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.2
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• pp.82-90
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• 2004

This study was conducted to evaluate in situ soil flushing and coagulation for naphtalenes-contaminated soil remediation. Mixed-surfactant of 1% POE12 and 1% SDS (1 : 1 by volume basis) was used as a flushing solution. When 5 pore volumes of mixed -surfactant were added to soil column, the flushing efficiencies of 2-methylnaphtalene and 1,5-dimethylnaphtalene with about 1,500 mg/kg(dry soil) were approximately 80% and 60% respectively. In adding 13 pore volumes of mixed-surfactant, the flushing efficiencies of 2-methylnaphtalene and 1,5-dimethylnaphtalene were 90% and 82%. However, considering in situ soil flushing with distilled water, about 42% and 71% were flushed for 2-methylnaphtalene and 1,5-dimethylnaphtalene by surfactant-only. For about 10,000 mg/kg(dry soil) diesel-contaminated soil, 40% and 70% of TPH were flushed-out in 5 pore volumes and 13 pore volumes addition. However, for naphtalenes in diesel TPH, 90% of flushing efficiency was discovered in adding only 5 pore volumes of flushing solution. There was not discovered significant difference among coagulation efficiencies of 6 kinds of polymers, and the coagulation efficiencies were near 50%.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.91-101
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• 1996

In recent years, phytoremediation, the use of plants to detoxify hydrocarbons, has been a promising new area of research, particularly in situ cleanup of large volumes of slightly contaminated soils. There is increasing need for a mathematical model that can be used as a predictive tool prior to actual field implementation of such a relatively new technique. Although a number of models exist for solute-plant interaction in the vegetated zone of soil, most of them have focused on ionic nutrients and some metals. In this study, we developed a mathematical model for simulation of bioremediation of hydrocarbons in soil, associated with plant root systems. The proposed model includes root interactions with soil-water and hydrocarbons in time and space, as well as advective and dispersive transport in unsaturated soil. The developed model considers gas phase diffusion and liquid-gas mass exchanges. For simulation of temporal and spatial changes in root behavior on soil-water and with hydrocarbons, time-specific distribution of root quantity through soil was incorporated into the simulation model. Hydrocarbon absorption and subsequent uptake into roots with water were simulated with empirical equations. In addition, microbial activity in the rhizosphere, a zone of unique interaction between roots and soil microorganisms, was modeled using a biofilm theory. This mathematical model for understanding and predicting fate and transport of compound in plant-aided remediation will assist effective application of plant-aided remediation to field contamination.

• Journal of Soil and Groundwater Environment
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• v.11 no.2
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• pp.22-37
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• 2006

The applicability of biobarrier or in situ microbial filter technology for the remediation of groundwater contaminated with chlorinated solvent was investigated through batch microcosm study. The efficiency and rates of reductive dechlorination of tetrachloroethylene (PCE) are known to be highly dependent on hydrogen concentration. In this study, the effect of electron donors on the reductive dechlorination of PCE was investigated using vermicompost (or worm casting) and peat as a biobarrier medium. The effect of organic acids (lactate, butyrate and benzoate), yeast extract and vitamin $B_{12}$ on the reductive dechlorination was investigated. In the absence of biobarrier medium (adsorbent), addition of electron donors stimulated the dechlorination rate of PCE compared to the control experiment (i.e., no electron donor added). Among the treatments, addition of lactate or lactate/benzoate as hydrogen donor exhibited the highest dechlorination rate ($k_1=0.0260{\sim}0.0266\;day^{-1}$). In case of using vermicompost as a biobarrier medium, amendment of lactate/benzoate exhibited the highest dechlorination rate following with a pseudo-first-order degradation rate constant of $k_1=0.0849\;day^{-1}$. In contrast, when Pahokee peat was used as a biobarrier medium, either butyrate or lactate addition exhibited the highest dechlorination rate with $k_1$ values of 0.1092 and $0.1067\;day^{-1}$, respectively. The results of this study showed the potential applicability of in situ biobarrier technology using vermicompost or peat as a barrier material for the remediation of groundwater contaminated with chlorinated solvent.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.2
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• pp.37-45
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• 2022

In-situ pilot experiment was carried out to establish a countermeasure on the soil loss from the hill side uplands that was rehabilitated by soil remediation method nearby abandoned mine sites for 2 years. It was considered that the affect of an inclination of cover surface, a stabilization treatment of cover layer by lime and steel refining slag (SRS) and a vegetation of soil surface as an effect factors in the experiment. It was constructed 4 lysimeters (plots, 22 m long, 4 m width) on the hilly side (37% inclination). One plot was control and two plots was treated by 1% lime and SRS. A remind one plot was modified a inclination to 27% to compare the affect of inclination on the amount of cover soil loss. It was attached a reservior tank and water level gauge in the end of lysimeters to measure the amount of the surface water flow and soil loss. It was also installed the automated sensors that could be collect the precipitation, soil moisture content, tension of cover layer in each plots. It was observed that the event of precipitation were caused the soil loss and it were related the physical and chemical properties of cover soil and inclination of surface layer of plots. During the experiment, it was exceeded the national regulation (50 t/ha/yr) in 37% inclination plots even though it was vegetated on the cover soil surface. However, in 27% inclination plot, it was shown that the amount of soil loss was maintained below the national regulation and, more ever, vegetation could reduce the the amount of soil loss. Therefore it was expected that such results could be applied to the future design of rehabilitation projects on the polluted farmland nearby abandoned mine sites.

• Journal of Soil and Groundwater Environment
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• v.25 no.1
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• pp.62-73
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• 2020

PAHs commonly found in industrial sites such as manufactured gas plants (MGP) are potentially toxic, mutagenic and carcinogenic, and thus require immediate remediation. In-situ chemical oxidation (ISCO) is known as a highly efficient technology for soil and groundwater remediation. Among the several types of oxidants utilized in ISCO, persulfate has gained significant attention in recent years. Peroxydisulfate ion (S₂O₈^2-) is a strong oxidant with very high redox potential (E⁰ = 2.01 V). When mixed with Fe²⁺, it is capable of forming the sulfate radical (SO₄^-·) that has an even higher redox potential (E⁰ = 2.6 V). In this study, the influence of various iron activators on the persulfate oxidation of PAHs in contaminated soils was investigated. Several iron sources such as ferrous sulfate (FeSO₄), ferrous sulfide (FeS) and zero-valent iron (Fe(0)) were tested as a persulfate activator. Acenaphthene (ANE), dibenzofuran (DBF) and fluorene (FLE) were selected as model compounds because they were the dominant PAHs found in the field-contaminated soil collected from a MGP site. Oxidation kinetics of these PAHs in an artificially contaminated soil and the PAH-contaminated field soil were investigated. For all soils, Fe(0) was the most effective iron activator. The maximum PAHs removal rate in Fe(0)-mediated reactions was 92.7% for ANE, 83.0% for FLE, and 59.3% for DBF in the artificially contaminated soil, while the removal rate of total PAHs was 72.7% in the field-contaminated soil. To promote the iron activator effect, the effects of hydroxylamine as a reducing agent on reduction of Fe³⁺ to Fe²⁺, and EDTA and pyrophosphate as chelating agents on iron stabilization in persulfate oxidation were also investigated. As hydroxylamine and chelating agents (EDTA, pyrophosphate) dosage increased, the individual PAH removal rate in the artificially contaminated soil and the total PAHs removal rate in the field-contaminated soil increased.

• Journal of Soil and Groundwater Environment
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• v.14 no.4
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• pp.45-53
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• 2009

This study concerned remediation of heavy metal contaminated farmland soils near abandoned mine, using stabilization method, with particular emphasis on the remediating the soils contaminated with multi-elements. In this study, stabilizing heavy metals based on 'In-situ chemical fixation' has been applied to the soil collected from an abandoned mine in Korea, using column test, with various stabilizing agents, including $FeSO_4$, $KMnO_4$, sludge (collected from coal mine drainage treatment pond), zero-valent iron (ZVI), zeolite and $CaCO_3$. Sixty five-days operation of the flow-through columns yield $FeSO_4\;+\;KMnO_4$ and zeolite are efficient on reducing As leaching from the soil. ZVI and sludge are reducing the leaching of Cu. Although $FeSO_4\;+\;KMnO_4$ seem to be efficient for most heavy metals, high pH in the initial stage of test enabled high leaching of the heavy metals, whereas fixation of the heavy metals maintain throughout the rest of the test period, with increasing pH up to around 6. Addition of some alkaline agent may inhibit the low pH during the application. The column test was also run as two set: one set incubated with deionized water for 72 hours prior to starting the test, and the other without incubation. The incubated set demonstrated better stabilizing efficiency, indicating the potential optimized operation method.

• Journal of Soil and Groundwater Environment
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• v.19 no.6
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• pp.80-90
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• 2014

The laboratory and field studies were conducted to identify an optimal injection concentration of nanoscale zero-valent iron particles (NZVI) and to evaluate the applicability of NZVI-based reactive zone technology to the site contaminated with trichloroethylene (TCE) DNAPL (Dense Non-Aqueous Phase Liquid). The laboratory test found an optimal injection concentration of NZVI of 5 g/L that could remove more than 95% of 0.15 mM TCE within 20 days. Eleven test wells were installed at the aquifer that was mainly composed of alluvial and weathered soils at a strong oxic condition with dissolved oxygen concentration of 3.50 mg/L and oxidation-reduction potential of 301 mV. NZVI of total 30 kg were successfully injected using a centrifugal pump. After 60 days from the NZVI injection, 86.2% of the TCE initially present in the groundwater was removed and the mass of TCE removed was 405 g. Nonchlorinated products such as ethane and ethene were detected in the groundwater samples. Based on the increased chloride ion concentration at the site, the mass of TCE removed was estimated to be 1.52 kg. This implied the presence of DNAPL TCE which contributed to a higher estimate of TCE removal than that based on the TCE concentration change.

• Journal of the Korean Geotechnical Society
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• v.16 no.3
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• pp.23-28
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• 2000

초음파를 이용한 지반 세척의 효율을 높이기 위한 방법이 최근에 개발되었지만 그에 대한 연구는 아직 초기 단계인 실정이다. 본 연구는 초음파가 지반 정화에 미치는 영향에 대하여 실내 실험을 통해 고찰하였으며 특히 초음파 에너지의 강도, 시료의 종류 및 밀도, 그리고 수두의 변화가 지반 세척에 미치는 영향에 대하여 연구를 수행하였다. 상기의 연구 결과 지반 세척시 초음파가 세척 능력을 상당히 향상시키는 것으로 나타났으며 초음파에너지가 강할수록, 흐름 속도가 느릴수록 초음파의 효과가 크게 나타났다.