• Journal of Soil and Groundwater Environment
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• v.18 no.5
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• pp.7-14
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• 2013

The objectives of this study were to identify the characteristics of groundwater in the petroleum contaminated site and to evaluate the applicability of house-type landfarm facilities heated with briquette stoves in winter season. The six monitoring wells were installed at the site where pH, dissolved oxygen, and temperature were all measured. Also groundwater contaminants, benzene, toluene, ethylbenzene, xylene and total petroleum hydrocarbon, were analyzed twice. House-type two landfarm facilities ($12m{\times}40m{\times}4.8m$) each installed with four briquette stoves were constructed. During four rounds treatment process, VOCs, moisture, temperature were monitored and soil contaminants were analyzed. The pH was 6.37 and considered subacid and DO was measured to be 3.12 mg/L. The temperature of groundwater was measured to be $9.48^{\circ}C$. The groundwater contaminants were detected only in the monitoring wells within the contaminated area or close to it showing that the groundwater contaminated area was similar to the soil contaminated area. During the landfarm process, 73.3% of VOCs concentration in interior gas was decreased and moisture was lowered from 17.7% to 13.4%. In the morning, at 8:00 am, the temperature was decreased showing soil ($5.5^{\circ}C$) > interior ($4.8^{\circ}C$) > exterior ($3.5^{\circ}C$). In the afternoon, at 2:00 pm, the temperature was soil ($8.6^{\circ}C$) < interior ($9.9^{\circ}C$) < exterior ($11.5^{\circ}C$) with solar radiation. The temperature difference between interior and exterior was $0.7^{\circ}C$ in the morning, but it was $1.6^{\circ}C$ in the afternoon. A total of 130 days were taken for four round landfarm processes. Each process was completed within 33 days showing 80% of cleanup efficiency ($1^{st}$ order dissipation rate(k) = 0.1771).

• Journal of Soil and Groundwater Environment
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• v.7 no.3
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• pp.61-70
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• 2002

Direct electron beam irradiation experiments on artificially contaminated soil by polynuclear aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were performed to evaluate applicability of direct electron beam irradiation process for contaminated soil remediation. The removal efficiency of PAHs was about 97 % at 600 kGy and PCBs about 70 % at 800 kGy. PAHs were removed 27 % more, compared to PCBs although the absorbed dose was as low as 200 kGy. The contaminants decomposition was due predominantly to direct interaction of high-energy electrons and the target compounds rather than due to oxidation/reduction reaction by reactive intermediates. Radiolysis of electron beam may be able to decontaminate contaminated soil by toxic and recalcitrant organic compounds like as PAHs and PCBs effectively, but it may be economically uncompetitive. Thus, developments of post-treatment process of conventional site remediation technologies may be more practical and economical than direct radiolysis.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1372-1377
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• 2009

For the remediation of the subsurface contaminated by nonaqueous phase liquids(NAPLs), it is important to characterize the NAPL zone properly. Conventional characterization methods provide data at discrete points. To overcome the weak points of conventional characterization methods, the partitioning tracer method has been developed and studied. The average saturation of NAPL($S_n$), which is the representative and continuous saturation value within contaminated site, can be calculated by comparing the transport of the partitioning tracers to that of the conservative tracer in the partitioning tracer method. In this study, the application of the partitioning tracer method in heterogeneous media was investigated. To represent the heterogeneous condition of subsurface, a two-dimensional soil box was divided into four layers and each layer contained different sized soils. Soils in the soil box were contaminated by the mixture of kerosene and diesel, and partitioning tracer tests were conducted before and after the contamination using methanol as conservative tracer and 4-methyl-2-pentanol, 2-ethyl-1-butanol, and hexanol as partitioning tracers. The response curves of partitioning tracers from contaminated soils were separated and retarded in comparison with those from non-contaminated soils. The contamination of soils by NAPLs, therefore, can be detected by partitioning tracer method considering these retardations of tracers. From our experiment condition, the average saturation of NAPLs calculated by partitioning tracer method using the methanol as conservative tracer and hexanol as partitioning tracer showed the highest accuracy, though all results were underestimated. Further studies, therefore, were needed for improving the accuracy using the partitioning tracer test in heterogeneous media.

• Geophysics and Geophysical Exploration
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• v.19 no.2
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• pp.59-66
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• 2016

The electrical resistivity method is an effective geophysical tool to detect subsurface contamination because the contaminated zones show generally lower electrical resistivity. In this study, the electrical resistivity surveys were applied to a waste landfill site to image the subsurface structure around the landfill and to identify the contaminated zones. First, the dipole-dipole 2D resistivity surveys were conducted along the boundaries of landfill to define the developed contaminated zones. Then the crosshole resistivity tomography was applied to confirm the suspected contaminated zones at depth. The results of drilling and geochemical analysis of ground water supported that the low resistivity zones coincide well with the contaminated zones and the leachate pathways could be delineated effectively from the resistivity survey.

• Journal of Soil and Groundwater Environment
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• v.18 no.6
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• pp.32-37
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• 2013

The scope of this study was to develop, design, and build an ex-situ remediation system of using the heating and water sparging treatment for the highly volatile DNAPL (Dense Non-Aqueous Phase Liquid) contaminated groundwater, and to conduct pilot testing at the site contaminated with DNAPL. The TCE (Trichloroethylene) removal was at the highest rate of 94.6% with the water sparging at $70^{\circ}C$ in the lab-scale test. The pilot-scale remediation system was developed, designed, and fabricated based on the results of the lab-scale test conducted. During the pilot-scale testing, DNAPL-contaminated groundwater was detained at heat exchanger for the certain period of time for pre-heating through the heat exchanger using the thermal energy supplied from the heater. The heating system supplies thermal energy to the preheated DNAPL-contaminated groundwater directly and its highly volatile TCE, $CCl_4$ (Carbontetrachloride), Chloroform are vaporized, and its vaporized and treated water is return edback to the heat exchanger. In the pilot testing the optimum condition of the HWSRS was when the water temperature at the $40^{\circ}C$ and operated with water sparging concurrently, and its TCE removal rate was 90%. The efficiency of the optimized HWSRS has been confirmed through the long-term performance evaluation process.

• Journal of Environmental Science International
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• v.9 no.5
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• pp.437-441
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• 2000

A study on the removal of Pb ion from Pb-contaminated soil was carried out using ex-site extraction process. Tartaric acid (TA) and iminodiacetic acid sodium salt(IDA) as a washing agent were evaluated as a function of concentration reaction time mixing ratio of washing agent and recycling of washing agent. TA showed a better extraction performance than IDA. The optimum washing condition of TA and IDA were in the ratio of 1:15 and 1:20 between soil and acid solution during 1 hr reaction. The total concentrations of Pb ion by TA and IDA at three repeated extraction were 368.8 ppm and 267.5 ppm respectively. The recovery of Pb ion from washing solution was achieved by adding calcium hydroxide and sodium sulfide form the precipitation of lead hydroxide and lead sulfide and optimum amounts of sodium sulfide and calcium hydroxide were 7 g/$\ell$ for the TA washing solution and 4 g/$\ell$, 5g/$\ell$ for the IDA washing solution respectively. The efficiency of recycle for TA and IDA washing solution were 78.8% , 95.1%, and 89.2%, 96.6% at third extractions under $Na_2S$ and $Ca(OH)_2$, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.261-266
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• 2001

Three innovative technologies to remediate trichloroethylene (TCE) in situ were (or currently are being) evaluated at a TCE-contaminated groundwater site at Edwards Air Force Base (AFB), California. The three technologies all make use of groundwater recirculation to obviate the need to pump contaminated groundwater to the surface fer treatment. The first technology, which implements aerobic cometabolic bioremediation to destroy TCE in situ, successfully reduced dissolved TCE concentrations from above 1 mg/L to 20-30 $\mu\textrm{g}$/L. The second technology, in-well vapor stripping (IWVS), is capable of treating dissolved TCE at concentrations in the tens to hundreds of mg/L. Finally, the third technology, bioenhanced in-well vapor stripping (BEHIVS): is a combination of the first two technologies, and is designed to reduce very high levels of TCE (tens to hundreds of mg/L) to concentrations that meet regulatory requirements 5 $\mu\textrm{g}$/L). Results of field evaluations of tile first two technologies are presented, and the design of the BEHIVS system. as well as model predictions of BEHIVS performance and the current status of the technology field evaluation. is discussed.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.72-75
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• 2004

The potential of electrokinetic (EK) technology has been successfully demonstrated for the remediation of heavy metal contaminated fine-grained soils through laboratory scale and field application studies. Arsenic contamination in soil is a serious problem affecting both site use and groundwater quality. The EK technology was evaluated for the removal of arsenic from two soil samples: kaolinite clay artificially contaminated with arsenic and arsenic-bearing tailing soil taken from the Myungbong (MB) mining area. The effect of cathodic electrolyte on the process was investigated using three different types of electrolyte: deionized water (DIW), potassium phosphate (KH$_2$PO$_4$) and sodium hydroxide (NaOH). The result of experiments on the kaolinite clay shows that the potassium phosphate was most effective in extracting arsenic, probably resulting from anion exchange of arsenic species by phosphate. On the contrary, the sodium hydroxide seemed to be most efficient in removing arsenic from the tailing soil, and it is explained by the fact that sodium hydroxide increased the soil pH and accelerated ionic migration of arsenic species through increase in desorption and dissolution of arsenic species into pore water.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.181-185
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• 2004

Electrokinetic bioremediation was conducted on phenanthrene-contaminated soil to study the effects of soil temperature and pH on microbial population and removal efficiency at different current densities from 0.63 to 3.13 mA cm$^{-2}$ . Microorganism used in the biodegradation of phenanthrene was Sphingomonas sp. 3Y, which was isolated from a diesel-contaminated site. The microorganism was successfully penetrated into the contaminated soil by electrokinetic phenomena and the highest microbial population was observed in the middle region of soil specimen where soil pH was near neutral. Therefore, phenanthrene removal occurred mainly at anode and middle parts of soil specimen due to a relatively high microbial population. Also, the highest removal efficiency of 68.8% was obtained at 1.88 mA cm$^{-2}$ while low degradation was detected at 3.13 mA cm$^{-2}$ . It was presumably because the soil temperature at 1.88 mAcm$^{-2}$ was close to the appropriate temperature of about 30'c while the temperature increase to above 45$^{\circ}C$ at 3.13 mA cm$^{-2}$ inhibited the microbial activity severely.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.819-835
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• 2009

In order to investigate the field application of selected stabilization methods(cover soil method, surface and total interval treatment of embankment method) on rice paddies contaminated by heavy metals, column test was carried out with heavy metal-contaminated soils collected from rice paddies around abandoned mine site. Columns were made by acrylic and filled with untreated soil, treated soil mixed with amendments(lime stone and steel refining slag) and uncontaminated cover soil according to the design report. Distilled water was discharged into the columns with the velocity of 1 pore volume/day. During test, pH, EC, and heavy metal concentration were measured in the regular term. The column test result showed that the selected stabilization methods were effective remediation method to stabilize heavy metals in paddy soils, but it was also expected that application of surface treatment methods was required the careful observation on pH variation due to the lowest increment.