• Journal of Soil and Groundwater Environment
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• v.27 no.2
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• pp.76-86
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• 2022

Calcium (Ca) and potassium (K) were introduced to remove Sr and Cs in soil, respectively. Four factor and three level Box-Bhenken design was employed to determine the optimal washing condition of Ca- and K-based solutions, and the ranges tested were 0.1 to 1 M of Ca or K, L/S ratio of 5 to 20, washing time of 0.5 to 2 h, and pH of 2 to 7. The optimal washing condition determined was 1 M of Ca or K, L/S ratio of 20, washing time of 1 h, and pH of 2, and Ca-based and K-based solutions showed 68 and 81% removal efficiency for Sr and Cs, respectively in soil. For comparison, widely used conventional washing agents such as 0.075 M EDTA, 0.01 M citric acid, 0.01 M oxalic acid, and 0.05 M phosphoric acid were tested, and they showed 25 to 30% of Sr and Cs removal efficiency. Tessier sequential extraction was employed to identify the changes in chemical forms of Sr and Cs during the washing. In contrast to the conventional washing agents, Ca-based and K-based solutions were able to release relatively strongly bound forms of Sr and Cs such as Fe/Mn-oxide and organic matter bound forms, suggesting the involvement of direct substitution mechanism, probably due to the physicochemical similarities between Sr-Ca and Cs-K.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.2
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• pp.114-118
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• 1990

Water requirement for desalinization was studied in column experiment filled with a tidal saline soil treated with gypsum partially, one half of the gypsum was mixed to the top one tenth and the other half was spread on the surface of the column soil. Different doses of percolates were collected and analysed with sectionalized column soils after the last percolation. Results obtained are as follows ; 1. One point seven(1.7) times of percolate was enough to desaline sodium from the tidal saline soil to bring the activity ratio of $Na/{\sqrt{Ca+Mg)}}$ to 0.10 at which the mean % Na to the sum of cations was $1.64{\pm}0.57$, but for magnessium, twice as much the percalate as the saline soil was still not enough, so that the activity ratios, $(Na+{\sqrt{Mg}})/(K+{\sqrt{Ca}})$ of soil, at different depth were not contract to an equilibrium point. 2. Most free NaCl was washed out into 1.4 times of percolate to the saline soil There after which the leaching of K and Mg became obvious. 3. Iso ha lime curves of sodium were prepared for water requirement to desaline a tidal saline soil to a projected Na concentration and a predetermined soil depth.

• Journal of the Korean GEO-environmental Society
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• v.14 no.11
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• pp.25-31
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• 2013

Civil and military firing ranges are usually contaminated with heavy metals such as lead and copper and remediation is required. Acid washing and extraction are common remediation methods. Lead contaminated firing range soil samples were collected and a preliminary study was conducted to evaluate the characteristics of the contamination and the contribution of high specific gravity particles. Ethylenediamine tetra acetic acid(EDTA) extraction was applied for the removal of heavy metal but the extraction was not feasible for the firing range soil. Even after the repeated EDTA extraction, the contamination were still over the Korean environmental standard indicating that soil particles highly contaminated with heavy metal which release the heavy metal ion even after the repeated extraction. Some colored and higher specific gravity particles were separated from the soil samples and analyzed. The colored particles have specific gravity of 2.5-6.6. The saturation ratio of Pb and EDTA was 4.9-32%. After removal of these colored particles, the sandy soil showed moderate contamination which can be treated with soil washing. This was proved with the five-level sequential extraction and TCLP tests.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.1
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• pp.1-9
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• 2008

This study examined the effect of an electrokinetic-flushing remediation for a soil of a high permeability. The soil was sampled from the site around a research atomic reactor which had high hydro-conductivities due to a high content of sand in the soil. The flow rate of the washing reagent was fast at the beginning but it was reduced as time lapsed. In the case of using citric acid as a washing reagent, the flow rate was fastest, 78.7 ml/day. The removal efficiencies of $Co^{2+}$ and $Cs^+$ from a soil cell with acetic acid were the highest, which were 95.2% and 84.2% respectively. The soil waste-solution volume generated from the electrokinetic remediation was reduced to about 1/20 of that from the soil washing remediation. Meanwhile, the electrokinetic-flushing method enhanced the removal efficiencies of $Co^{2+}$ and $Cs^+$ from the soil by about 6% and 2% respectively, compared to those by the electrokinetic method. Consequently, it was found that the electrokinetic-flushing method was more effective for the remediation of a soil with a high permeability.

• Journal of Environmental Health Sciences
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• v.23 no.4
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• pp.82-90
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• 1997

This study was conducted to establish an ideal condition for obtaining maximum extraction efficiencies using an array of soil types and under a wide variety of conditions. Nine characteristic compounds were studied: benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene, n-propylbenzene, 1,2,4-trimethylbenzene, and n-butylbenzene which were found in gasoline. Increasing the moisture content resulted in decreased recovery, and recovery of hydrocarbons from wet soils was significantly lower than from dry soils. For the batch extraction process, 4 hours of extraction time was sufficient to give optimum recovery of the contaminants. With methanol as an extraction solvent, maximum recovery time appeared to be reached quicker for BTEX components than with 2-propanol. The 2 to 1 ratio of solvent/soil was chosen as a compromise to provide for the indicated minimum solvent use and high extraction efficiency. The 0.4 mg/g soil contamination was adequate to show quantitative recovery. The percent recovery of BTEX was concentration dependent more than the semivolatile compounds. Methanol and 2-propanol consistently gave higher efficiency than water. Methanol was superior to 2-propanol in removing contaminants from silty clay loam soil. Using the most efficient extraction procedure, the average recovery of the light hydrocarbons from the three soils was 66 percent. Recoveries were also dependent on soil type, solvent type, extraction time, solvent amount, contaminant concentration, and compounds volatility. This study provided a useful screening technique for procedures that can be used to remediate soils contaminated with light hydrocarbons.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.268-276
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• 2008

The status of contaminated soils vary widely ; therefore, the techniques and equipment applicable to the soil concerned should be selected and used after careful consideration. Hyundai Soil Washing is physical-chemical separation based on mining and mineral processing principles for removing a broad range of organic and inorganic contaminants from soil. Mobile plant(capacity 15 tons./hr) was installed for this project. The goals of this project were 1) to verify the applicability of the washing process, which showed reliable results in the pilot plant with various kind of contaminated soils and 2) to promote recycling of the washed soil as a backfill on site. The results revealed that $F^-$ and $Pb^{2+}$ in the soil were effectively washed out to a certain level which washed soil was acceptable for recyeling.

• Journal of Environmental Health Sciences
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• v.33 no.1 s.94
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• pp.75-81
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• 2007

This research was conducted to estimate the effect of sonication and reducing agent addition on soil washing of heavy metals-contaminated soil. Sonication trained in soil washing did not significantly increased extraction efficiency of heavy metal compared to soil washing only. The extraction efficiency of sonication trained in soil washing was 12% increased for Pb in 0.01M EDTA leaching solution. Pb and Cd showed higher extraction efficiency in case of reducing agent treatment with mechanical shaking than that with sonication. However, the extraction efficiency of Cu and Zn in case of reducing agent treatment with sonication was over 2 times higher than that in with soil washing. Therefore, application of reducing agent addition with sonication or mechanical shaking should be decided differently for pretreatment of soil washing, according to the kind of heavy metal. It was estimated that sonication after adding reducing agent could increase removal efficiency of Zn or Cu-contaminated soil and shorten the treatment time.

• Journal of Food Hygiene and Safety
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• v.31 no.2
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• pp.99-106
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• 2016

This study was aimed to assess microbiological contamination level of Liriope platyphylla farms (A, B, and C) located in Cheongyang, Chungnam province. Specimens sampled from those farms and L. platyphylla tuberous roots were assessed for sanitary indication bacteria such as total aerobic bacteria, coliforms, and Escherichia coli and pathogenic bacteria such as Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus and Bacillus cereus, quantitatively and qualitatively. As a result, those farms are not contaminated by E. coli O157:H7, L. monocytogenes, Salmonella spp., at all. And S. aureus was only found qualitatively from workers' gloves at a farm. As a whole, those farms (soil, harvest container, harvester, cleanser, washing water and tray) were maintained in a low level of microbiological contamination. However a cleanser was contaminated by coliforms ($4.35log\;CFU/100cm^2$), and it is required to improve farm hygiene. Microbiological contamination level of L. platyphylla tuberous root was decreased in the postharvest process including washing and drying.

• Korean Journal of Microbiology
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• v.39 no.3
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• pp.181-186
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• 2003

This study was performed to analyze quantitatively the number of living bacteria in forest soil samples collected from Mt. Keryong using improved direct viable count (DVC) and plate count (PC) methods. The number of living bacteria by DVC comprised 18～44% of the total direct count (TDC), whereas the number of living bacteria by PC was less than 1% of TDC. These results showed that viable but non-culturable (VBNC) bacteria existed in the soil with high percentages. Besides, DVC was proved to make it possible to make a quantitative detection of the VBNC bacteria. On the other hand, upon measuring the value from the conventional nutrient broth (NB) and $10^{-2}$ folded diluted nutrient broth (DNB), the values from the DNB showed 5 to 10 times higher than those from the conventional NB medium. These results indicate that oligotrophic bacterial groups, which could multiply in the low nutrient broth, abundantly exist in the soil ecosystem. It would also be possible to apply this kind of method to other substrate to make a quantitative detection of soil bacterial groups.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.1-8
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• 2009

This research was performed to assess a Fenton-like oxidation using naturally present iron in the field to treat remained oils throughout silty clay residues which finally resided even after a series of soil washing process. Biodegradability was thus tested for reaction products to investigate a possible treatment of the Fenton-like oxidation coupled with a biological treatment process. For those purposes, two types of field soil samples (e.g., dewatered cake after conditioning with a polymer and not-dewatered residue) were tested to remove TPH by adding the various concentration of hydrogen peroxide ($H_2O_2$). Moreover the biodegradability of treated samples was observed based on the ratio of $BOD_5/COD_{Cr}$ after Fenton-like oxidation. The Highest removal of TPH was at 1% of hydrogen peroxide ($H_2O_2$) when hydrogen peroxide ($H_2O_2$) was continuously injected for a period of time rather than that of spot introduction with the same amount of it. For the dewatered cake, TPH was effectively treated when the ratio of solid and water was mixed at 1 : 2. Employing cooking oil could increase solubility of TPH due to enhanced surface-active escalating TPH desorption from silty clay. Nonetheless, the biodegradability was decreased as long as the oxidation duration being extended regardless of operational conditions. It was therefore proved that Fenton-like oxidation using $H_2O_2$ and natural iron minerals was able to remove adsorbed oils in silty clay but the removal efficiency of TPH was low. And if a biological treatment process followed after Fenton-like oxidation, microorganisms would need enough time for acclimation.