• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.808-816
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• 2008

In the present paper, a study has been performed on remediating mine tailings around abandoned mine contaminated with high concentrations of arsenic and heavy metals using the technique of soil washing. Through the removal experiment of arsenic, the optimal conditions in the type and concentration of washing reagent, mixing ratio of mine tailings and washing reagent, and washing time were derived. Results showed that the most effective washing reagents to remove arsenic from mine tailings were oxalic acid(72% removal efficiency) and phosphoric acid(65%), while the oxalic acid(89%) was the most effective in removing the heavy metals containing Cu. In addition, the most economical and efficient washing concentration was 0.25 M and the most suitable washing time was 30 minutes. The optimal mixing ratio of mine tailings and washing reagent was 1 : 20(mass/vol) from the viewpoint of minimization of wastewater produced after the washing, as well as the washing effectiveness. Although the mixture of washing reagents did not help in removal of arsenic, it could lead to much elevated synergy effect on removing Cu and Zn, compared with the single reagent.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.52-61
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• 2004

In order to remediate soils contaminated with oxyanionic As and cationic Zn and Ni through the pilot-scale acid washing, the effectiveness of acid washing and the properties of contaminated soils, fine soil particle and dissolved contaminants were evaluated. $H_{2}SO_4\;and\;H_{3}PO_4$ washing at pH $2{\sim}3$ enhanced the removal of As by the presence of competitive oxyanions and HCl washing effectively removed simultaneously As, Zn and Ni. The effectiveness of soil washing was little enhanced above the critical reaction time, and the carbonate, Fe/Mn oxide and organic/sulfides associated fraction were dominantly removed. The washing of coarse soil particles was highly efficient, but that of fine soil particles($<74{\mu}m$) was recalcitrant due to the enrichment with contaminants. Moreover, the physical separation of fine particles($<149{\mu}m$) enhanced the overall efficiency of soil washing. Therefore, both chemical extraction and separation of fine soil particles showed the high effectiveness of soil washing in the intersection point to minimize the amount of fine soil particles and to maximize the chemical extraction of contaminants.

• Journal of Environmental Impact Assessment
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• v.30 no.4
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• pp.247-257
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• 2021

In this work, Iron Nano-Particles Impregnated BioChar/bead (INPBC/bead) soil amendment was developed to increase biochar's reactivity to As in soil and preventing possible wind loss. Prior to preparation of INPBC/bead, INPBC was produced utilizing lignocellulosic biomass and Fe(III) solution in a hydrothermal method, followed by a calcination process. Then, the bead type amendment, INPBC/bead was produced by cross-linking reaction of alginate with INPBC. FT-IR, XRD, BET, and SEM-EDS analyses were utilized to characterize the as-synthesised materials. The particle size range of INPBC/bead was 1-4 mm, and different oxygen-containing functional groups and Fe3O4 crystalline phase were produced on the surface of INPBC/bead, according to the characterization results. The soil cultivation test was carried out in order to assess the stabilization performance of INPBC/bead utilizing As and Pb-contaminated soil obtained from an abandoned mining location in South Korea. After 4 weeks of culture, TCLP and SPLP extraction tests were performed to assess the stabilization efficacy of the amendment. The TCLP and SPLP findings revealed that raising the application ratio improved stabilizing efficiency. The As stabilization efficiency was determined to be 81.56 % based on SPLP test findings for a 5% in (w/w) INPBC/bead treatment, and the content of Pb in extracts was reduced to the limit of detection. According to the findings of this study, INPBC/bead that can maintain pH of origin soil and minimize wind loss might be a potential amendment for soil polluted with As and heavy metals.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.477-481
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• 2004

지하수 수질자료의 분포가 광역적이고 자료의 수가 많은 지역과 자료의 분포가 국부적이고 갯수가 적은 지역을 선정하여, 모수적 통계기법인 정규크리깅과 비모수적 통계기법인 지시크리깅을 동시에 적용하였다. 베리오그램 분석은 각 수질자료의 원시 자료와 제한값을 적용하여 제한값 보다 낮거나 동일하면 '1' 의 값으로, 제한값 보다 높으면 '0' 의 값으로 변환된 자료에 대해 실시하였는데, 원시 염소이온 성분은 선형 모델이 선정되었으며, 비소 성분은 지수형 모델이 가장 적합한 것으로 선정되었다. 변환된 염소이온 성분과 비소 성분은 모두 구상형 모델이 가장 적합한 것으로 선정되었다. 정규크리깅과 지시크리깅 기법을 이용하여 지하수 오염 분포도를 작성하여 비교해 본 결과, 정규크리깅 기법은 연구지역의 자료 분포, 갯수와 범위의 영향을 크게 받는 것으로 나타났고, 지시크리깅 기법은 연구지역의 자료 분포와 특히 제한값에 따라 변환된 자료의 갯수의 영향을 크게 받는 것으로 나타났다. 정량적으로 나타낼 수 정규크리깅 기법과 정성적으로 나타낼 수 있는 지시크리깅 기법을 같이 적용한다면 지하수 오염 현황을 효과적으로 파악할 수 있을 것으로 판단된다.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.101-107
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• 2010

In order to deal with the problem that phytoremediation takes long time in achieving the practical effect, the enhanced phytoremediation by Barnyard grass (Echinochloa crus-galli) was conducted. In addition, we examined the synergistic effect by adding PSM (phosphate -solubilizing microbes) and EDTA (ethylenediaminetetraacetic acid) to the arsenic contaminated soil in the vicinity of the abandoned mine. The removal efficiency of arsenic in the site with PSM application increased about 16% when compared to control site, which was due to increase of plant biomass. The EDTA has been successfully utilized in respect of enhanced mobility and solubility of arsenic in the soil. As a result, BF (bioaccumulation factor) significantly increased but the inhibition of plant growth resulted in 20% reduction of arsenic removal efficiency. The application of PSM and EDTA may enhance the efficiency of phytoremediation. However, the time and method of EDTA application should be further examined to reach the maximum removal efficiency.

• Journal of Environmental Impact Assessment
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• v.29 no.5
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• pp.350-362
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• 2020

In this study, nano Fe°-impregnated biochar (INPBC) was prepared using pruning residues and one-pot synthetic method and evaluated its performance as an amendment agent for the stabilization of arsenic-contaminated soil. For the preparation of INPBC, the mixture of pruning residue and Fe (III) solution was heated to 220℃ for 3hr in a teflon-sealed autoclave followed by calcination at 600℃ under N₂ atmosphere for 1hr. As-prepared INPBC was characterized using FT-IR, XRD, BET, SEM. For the stabilization test of as-prepared INPBC, As-contaminated soils (Soil-E and Soil-S) sampled from agricultural sites located respectively near E-abandoned mine and S-abandoned mine in South Korea were mixed with different of dosage of INPBC and cultivated for 4 weeks. After treatment, TCLP and SPLP tests were conducted to determine the stabilization efficiency of As in soil and showed that the stabilization efficiency was increased with increasing the INPBC dosage and the concentration of As in SPLP extractant of Soil-E was lower than the drinking water standard level of Ministry of Environment of South Korea. The sequential fractionation of As in the stabilized soils indicated that the fractions of As in the 1st and 2nd stages that correspond liable and known as bioavailable fraction were decreased and the fractions of As in 3rd and 4th stages that correspond relatively non-liable fraction were increased. Such a stabilization of As shows that the abundant nano Fe° on the surface of INPBC mixed with As-contaminated soils played the co-precipitation of As leaching from soil by surface complexation with iron. The results of this study may imply that INPBC as a promising amendments for the stabilization of As-contaminated soil play an important role.

• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.63-69
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• 2004

Hematite-coated sand was examined for the application of the PRB (permeable reactive barrier) to the arsenic-contaminated subsurface in the metal mining areas. The removal efficiency of As in a batch and a flow system was investigated through the adsorption isotherm, removal kinetics and column experiments. Hematite-coated sand followed a linear adsorption isotherm with high adsorption capacity at low level concentrations of As (＜1.0 mg/L). In the column experiments, high content of hematite-coated sand enhanced the removal efficiency, but the amount of the As removal decreased due to the higher affinity of As (V) than As (III) and reduced adsorption kinetics in the flow system. Therefore. the amount of hematite-coated sand, the adsorption affinity of As species and removal kinetics determined the removal efficiency of As in a flow system.

• Economic and Environmental Geology
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• v.38 no.5 s.174
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• pp.571-577
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• 2005

Permeable reactive barrier using iron oxide coated sand is one of effective technologies for As(V) contaminated groundwater. However, this method is restricted to As(III), because As(III) species tends to be more weakly bound to adsorbent. In order to overcome the limitation of iron oxide coated sand application to As(III) contaminated groundwater, manganese oxide materials as promoter of As(III) removal were combined to the conventional technology in this study. For combined use of iron oxide coated sand and manganese oxide coated sand, two kinds of removal methods, sequential removal method and simultaneous removal method, were introduced. Both methods showed similar removal efficiency over $85\%$ for 6 hrs. However, the sequential method converted the As contaminated water to acid state (pH 4.5), on the contrary, the simultaneous method maintained neutral state (pH 6.0). Therefore, simultaneous As removal method was ascertained as a suitable treatment technology of As contaminated water. Moreover, for more effective As(III) remediation technique, polypropylene textile which has the characteristics of high surface area, low specific gravity and flexibility was applied as alternative material of sand. The combined use of coated polypropylenes by simultaneous method showed much more prominent and rapid remediation efficiency over $99\%$ after 6 hrs; besides, it has practical advantages in replacement or disposal of adsorbent for simple conventional removal device.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.141-144
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• 2003

청양 및 서보광산에서 채취한 광미 및 오염된 토양에 대한 산성비를 고려한 용출실험 결과, 아연, 카드뮴 및 망간 pH 6.2-5.8, 철 pH 5.2-3.2, 코발트 pH 4.4-3.2, 구리 pH 3.2-3.0, 납과비소 pH3.0-3.5의 용출조건에서 최초로 각 원소의 용출이 발생하였다. 반응용액의 최종 pH5.0-1.5사이에서 용출되는 중금속은 이온교환형태 및 탄산염광물형태와 수반된 것이 용해된 것이다. 반응용액의 최종 pH1.5이하에서 용출되는 중금속은 철과 밀접하게 수반된 것으로 해석되었다. 청양광산과 서보광산의 광미가 pH2.0이하로 유지되는 경우가 발생한다면, 청양광산은 비소(최대 6,006$\mu\textrm{g}$/g), 아연(최대 2,503$\mu\textrm{g}$/g) 및 납(최대 29,638$\mu\textrm{g}$/g), 서보광산은 납(최대 2,258$\mu\textrm{g}$/g)과 111소(최대 874$\mu\textrm{g}$/g)의 오염확산이 크게 우려되며, 이 결과는 광미에 대한 환경복원이 필요한 것을 지시한다. 서보광산의 오염된 토양은 pH3.0까지의 산성비와 반응하는 경우에는 중금속의 오염확산이 거의 우려되지 않으며, pH3.0이하의 강산 용액과 반응한다면 아연의 오염확산이 우려된다.

• Economic and Environmental Geology
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• v.55 no.4
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• pp.389-398
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• 2022

Many studies have been conducted to accurately predict the correlations between As and heavy metals content in contaminated soil and cultivated crops; however, due to the low correlation between the two, few clear results were obtained to date. This study aimed to create statistical models that predict the As content transferred from soil to polished rice, considering the physicochemical properties of the soil, as well as the total content and the single-extracted content of As in the soil. Predictive models were derived through regression analysis while sequentially classifying soil samples according to pH, soluble As content by single extraction, and organic matter content of the soil. The correlation coefficients between the As content in 80 polished rice and total As content and Mehlich soluble As content in the soil were low, 0.533 and 0.493, respectively. However, the models derived after sequential classification of the soil by pH, a ratio of total As content to Mehlich soluble As content, and organic matter content greatly increased the predictive power; ① 0.963 for 13 soils with a pH higher than 6.5, ② 0.849 for 15 soils with pH lower than 6.5 and a high ratio of As_Tot/As_Mehlich, ③ 0.935 for 30 soils with pH lower than 6.5, a high ratio of As_Tot/As_Mehlich, and organic matter content lower than 8.5%. The suggested prediction model of As transfer from soil to polished rice derived by soil classification may serve as a statistically significant methodology in establishing a rice cultivation standard for arsenic-contaminated soil.