• Analytical Science and Technology
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• v.21 no.4
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• pp.332-337
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• 2008

Purification of silica mineral was compared with various leaching methods such as shaking, stirring, ultrasonic with 2.5% HF/HCl solution. Among them, ultrasonic method showed a best leaching effect. From the leaching experiment, Na, K, Fe, Al exist as the major impurity elements. The removal rate of Al, Fe showed little difference with various leaching methods but Ca, Mn, Na were very different. Four kinds of silica mineral (>99% purity) after physical purification treatment were used for ultrasonic leaching experiment. Among them IN-Si had a highest impurity removal rate. Ca, Cr, K, Zn were removed above 80% using ultrasonic leaching method and Fe was also removed above 60%. But Al showed 10~60% removal rate with different samples.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.105-114
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• 2007

The most advanced oxidation processes (AOPs) are based on reactivity of strong and non-selective oxidants such as hydroxyl radical (${\cdot}OH$). Decomposition of typical DNAPL chlorinated compounds (TCE, PCE) using various advanced oxidation processes ($UV/Fe^{3+}$-chelating agent/$H_2O_2$ process, $UV/H_2O_2$ process) was approached to develop appropriate methods treating chlorinated compound (TCE, PCE) for further field application. $UV/H_2O_2$ oxidation system was most efficient for degrading TCE and PCE at neutral pH and the system could remove 99.92% of TCE after 150 min reaction time at pH 6($[H_2O_2]$ = 147 mM, UVdose = 17.4 kwh/L) and degrade 99.99% of PCE within 120 min ($[H_2O_2]$ = 29.4 mM, UVdose = 52.2 kwh/L). Whereas, $UV/Fe^{3+}$-chelating agent/$H_2O_2$ system removed TCE and PCE ca. > 90% (UVdose = 34.8 kwh/L, $[Fe^{3+}]$ = 0.1 mM, [Oxalate] = 0.6 mM, $[H_2O_2]$ = 147 mM) and 98% after 6hrs (UVdose = 17.4 kwh/L, $[Fe^{3+}]$ = 0.1 mM, [Oxalate] = 0.6 mM, $[H_2O_2]$ = 29.4 mM), respectively. We improved the reproduction system with addition of UV light to modified Fenton reaction by increasing reduction rate of $Fe^{3+}$ to $Fe^{2+}$. We expect that the system save the treatment time and improve the removal efficiencies. Moreover, we expect the activity of low molecular organic compounds such as acetate or oxalate be effective for maintaining pH condition as neutral. This oxidation system could be an economical, environmental friendly, and practical treatment process since the organic compounds and iron minerals exist in nature soil conditions.

• Journal of Soil and Groundwater Environment
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• v.10 no.5
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• pp.18-24
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• 2005

Water quality changes of wastewater effluent in the shallow aquifier condition was investigated using laboratory unsaturated and saturated SAT columns for over five months. Average DOC removal was 31.9% in the unsaturated SAT column whereas no removal occurred in the saturated SAT column. Under the shallow aquifer condition, nitrification was not completed in the unsaturated SAT column, releasing residual ammonium nitrogen into the saturated SAT column. Short retention time (one day) in the shallow unsaturated SAT column rendered DO of about 2 mg/L to the influent of the saturated SAT column. Phosphate was not removed at all in the unsaturated SAT column while complete removal was achieved in the saturated column. Consequently, organic and inorganic compounds were removed under the shallow aquifer condition as effectively as was in deep aquifer, except for the release of ammonium and relatively high DO into the saturated SAT column.

• Journal of Soil and Groundwater Environment
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• v.10 no.6
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• pp.75-80
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• 2005

Several metalliferous including Guedo mine, Manjung mine and Joil mine located at the upper watershed of Namhan river, were abandoned or closed since 1988 due to the mining industry promotion policy and thus disposed an enormous amount of mining wastes without a proper treatment facilities, resulting in soil pollution. In this research, total and fractional concentrations of heavy metals in mining wastes were analyzed and accordingly the degree of soil pollutions in the abandoned mine area were quantitatively assessed employing the several pollution indices. The mining waste samples from Guedo mine, Manjung mine and Joil mine recently abandoned were collected for the evaluation of the potential of water pollution by mining activities. Index of geoaccumulation fractional composition and removal efficiency of some heavy metals by different concentration of HCl treatment were analyzed. Index of geoaccumulation of Cd, Pb, Zn, Cu, Ni and Cr are 6, $4\~6,\;0\~6,\;4\~5$, 2 and 0 respectively. The index of geoaccumulation of Cd, Pb, Zn and Cu reveals the mining wastes has high pollution potential in the area. According to sequential extraction of metals in the mine wastes organic fraction of Cu, reducible fraction of Pb, residual fraction of Ni and Zn were the most abundant fraction of heavy metals in mining wastes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2B
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• pp.187-192
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• 2011

Nitrate nitrogen is common contaminant in groundwater aquifers, its concentration is regulated many countries below 10 mg/L as N (As per WHO standards) in drinking water. An attempt was made to get optimal results for the treatment of nitrate nitrogen in groundwater by conducting various experiments by changing the experimental conditions for ZVI bipolar packed bed electrolytic cell. From the experimental results it is evident that the nitrate nitrogen removal is more effective when the reactor conditions are maintained in acidic range but when the acidic environment changes to alkaline due to the hydroxide formed during the process of ammonia nitrogen there by increasing the pH reducing the hydrogen ions required for reduction which leads to low effectiveness of the system. In the ZVI bipolar packed bed electrolytic cell, the packing ratio of 0.5~1:1 was found to be most effective for the treatment of nitrate nitrogen because ZVI particles are isolated and individual particle act like small electrode with low packing ratio. It is seen that formation of precipitate and acceleration of clogging incrementally for packing ratio more than 2:1, decreasing the nitrate nitrogen removal rate. When the voltage is increased it is seen that kinetics and current also increases but at the same time more electric power is consumed. In this experiment, the optimum voltage was determined to be 50V. At that time, nitrate nitrogen was removed by 94.9%.

• Journal of Soil and Groundwater Environment
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• v.17 no.3
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• pp.76-85
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• 2012

Geochemical and ecological properties of remediated soil and gas exhausted from a low-temperature thermal desorption (LTTD) process were analyzed to assess the environmental impact of LTTD treatment. Soil characteristics were examined with regard to the chemical (EC, CEC, and organic matter) and the ecological (dehydrogenase activity, germination rate of Brassica juncea, and growth of Eisenia andrei) properties. The exhaust gases were analyzed based on the Air Quality Act in Korea as well as volatile organic compounds (VOCs) and mixed odor. Level of organic Organic matter of the soil treated by LTTD process was slightly decreased compared to that of the original soil because the heating temperature ($200^{\circ}C$) and retention time (less than 15 minutes) were neither high nor long enough for the oxidation of organic matter. The LTTD process results in reducing TPH of the contaminated soil from $5,133{\pm}508$ mg/kg to $272{\pm}107$ mg/kg while preserving soil properties. Analysis results of the exhaust gases from the LTTD process satisfied discharge standard of Air Quality Law in Korea. Concentration of VOCs including acetaldehyde, propionaldehyde, butyraldehyde and valeraldehyde in circulation gas volatilized from contaminated soil were effectively reduced in the regenerative thermal oxidizer and all satisfied the legal standards. Showing ecologically improved properties of contaminated soil after LTTD process and environmentally tolerable impact of the exhaust gas, LTTD treatment of TPH-contaminated soil is an environmentally acceptable technology.

• Microbiology and Biotechnology Letters
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• v.26 no.1
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• pp.76-82
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• 1998

The feasibility of algae as means of removing nitrogen and phosphorus from secondary treated swine wastewater was studied. Among the tested 7 species of Chlorella vulgaris (UTEX 265), Chlorella sp. GE 21, Botryococcus braunii (UTEX 572), Botryococcus sp. GE 24, Scenedesmus quadricauda, Phormidium sp. GE 2, and Spirulina maxima (UTEX 2342), C. vulgaris was selected for its fast growth and abilities to remove nitrogen and phosphorus and to produce algal biomass from swine wastewater. C. vulgaris grew well at 35$^{\circ}C$, and the optimum initial pH for growth was 8.0. In the effect of light intensity, the growth of C. vulgaris was limited under a light intensity of less than 40 ${\mu}$E/$m^2$/s. The secondary treated swine wastewater contained 58.7 mg/l of total nitrogen and 14.7 mg/l of total phosphorus, and was diluted to 75, 50, and 25% with groundwater to be treated. Nitrogen and phosphorus were removed by C. vulgaris in all diluted swine wastewaters among which the most effective removal was in 75% swine wastewater (swine wastewater:groundwater=3:1). There was a tendency of linear increase in nitrogen and phosphorus removal time with increasing concentration of swine wastewater. Under the optimized culture condition, total nitrogen and total phosphorus were effectively removed to 95.3% and 96.0%, respectively, in 25% swine wastewater after 4-day incubation.

• Journal of Soil and Groundwater Environment
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• v.11 no.6
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• pp.43-52
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• 2006

Effectiveness of activated soil containing directly enriched atrazine-degrading soil microorganisms as an inoculant to bioaugment degradation of atrazine in soils was investigated. A Wooster silt loam (Typic Fragiudalf) was spiked with atrazine at a rate of 4 mg/kg soil three successive times to create activated soil. Atrazine degradation was significantly enhanced (p < 0.05) after the first treatment. After the second treatment, there was an increase in the number, based on MPN, of microorganisms utilizing atrazine as a C- and N-source by 3 logs and 1 log of magnitude, respectively. Inoculation of typical agricultural soils collected from Ohio with activated soil at a rate as low as 0.5% reduced the extractable atrazine remaining in soils to the level below 2% of that initially recovered (initially added at a rate of 4 mg/kg soil) after 4 days. Inoculation at a higher rate was required to achieve the same result in soils with non-typical properties (pH of 4.5 or organic matter of 43% w/w). Activated soil was stable, in terms of atrazine degradation activity, at least up to 6 months when it was kept at low temperature (< $10^{\circ}C$) and moistened (water content above 15%). The results of this study indicate that microorganisms capable of degrading atrazine are relatively easily enriched in soil to create activated soil. Use of activated soil can be a practical option for bioremediation of contaminated soils.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.24-31
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• 2004

A cold mix asphalt (CMA) treatment process was proposed as a tool to recycle soils contaminated with petroleum hydrocarbons. Experimental studies were conducted to characterize performances of the CMA process in treating soils contaminated with diesel or diesel compounds. From the screening experiments, it was found that performances of five types of asphalt emulsions that contained a cationic or an anionic or a nonionic surfactant were not substantially different. In consideration of higher affinity for soils and higher sorption coefficients obtained, an emulsion containing Lauryl Dimethyl Benzyl Ammonium Chloride (LDBAC) was selected as a promising asphalt emulsion for treating diesel-contaminated soils. When the asphalt emulsion LDBAC was applied to treat three compounds that originated from diesel, the removal efficiencies obtained in the order of decreasing efficiencies were as follows: docosane > pentadecane > undecane. Leaching experiments on the specimen formulated by the emulsion LDBAC found that the selected treatment method could treat soils with diesel concentrations as high as 10,000 mg/kg. Leaching of the diesel from the specimen was controlled by diffusion for the first four days and then leaching rate diminished substantially. The latter behavior was characterized as depletion, which represents that the contaminant released amounts to more than $50\%$ of the total amount of the contaminant that can be leached. The amounts of three diesel compounds leached from the specimen in the order of decreasing amount were undecane, pentadecane, and docosane. The curing of the soil contaminated with pentadecane was relatively slow.

• Journal of Korea Soil Environment Society
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• v.5 no.1
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• pp.97-108
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• 2000

A Gram-type negative bacteria that can utilize crude oil as the sole source of carbon and energy was isolated from an activated sludge of a local sewage treatment plant and identified tentatively as belonging to the genus Acinetobacter. The isolate could degrade n-alkanes and unidentified hydrocarbons in crude oil and utilize n-alkanes, hydrophobic substrates, as sole carbon and energy sources. n-Alkanes from tridecane (Cl3) to triacontane (C30) in crude oil were degraded simultaneously with no difference in degradation characteristics between the two close odd and even numbered alkanes in carbon numbers. The linear growth of the isolate and the degradation characteristics of Pr-alkanes suggested that the transport of substrates from the oil phase to the site where the substrates undergo the initial oxidation in microorganism might be the rate limiting in the biodegradation process of crude oil constituents. The remainder fraction of substrates after cultivation was considered to reflect the hydrocarbon inclusions in the cell mass, characteristics in Acinetobacter species, and to control the transport of substrates from crude oil phase. On the basis of the results, the isolate was considered to play an important role in the degradation study of hydrophobic environmental pollutants.