• Economic and Environmental Geology
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• v.44 no.6
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• pp.485-492
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• 2011

Sorption of cyanide on granular activated carbon and attenuation of the cyanide by UV-light over a wide range of conditions such as pH and concentration were investigated through batch experiments. Cyanide uptake by activated carbon is much effective at $[CN]_{ini}$ < 2 mg/L. The sorption of cyanide on activated carbon at pH 7.0 is greater than that of pH 9.0. It is found that the ratio of CN uptake to CN in solution increases at pH 9.0 whereas at pH 7.0 the ratio decreases, suggesting that reactivity of activated carbon increases as a function of pH. The sorption of cyanide rapidly increases during the first 30 min, followed by sharp desorption until 3hr, and then the sorption increases and reaches the maximum sorption during the duration of experiments, implying that the sorption mode could be changed through conformational change during the initial stage of the cyanide uptake by activated carbon. Total amount of cyanide desorbed from the activated carbon during the period of desorption experiments is less than 1.5% of total sorbed cyanide, indicative of strong and stable sorption of cyanide on the activated carbon. The sorption with mixture of activated carbon and Ham-Baek sludge shows less effective on the removal of the cyanide. It is noted that UV-light is much effective on the removal of cyanide but also the attenuation is achieved until $[CN]_{tot}$ is up to 10 mg/L. Our findings demonstrate that both activated carbon and UV-light are very effective on the attenuation of cyanide over a wide range of environmental conditions.

• KSBB Journal
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• v.7 no.4
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• pp.247-251
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• 1992

The effect of biomass concentration of Saccharomyces cerevisiae ATCC 24858 on specific growth rates, biomass yields, ethanol yields and productivity in the batch fermentation of rotary shaker was investigated. The specific growth rate decreased according to the increase in the biomass density and finally became zero at a biomass concentration, 55g/L. The ethanol yield $Y_{p/s}$ represented a constant value, 0.43, regardless of the change of biomass concentrations. However, the biomass yield $Y_{x/s}$ showed a trend to diminish in values with augmentation of biomass density and ultimately to reach zero at 55g/L of biomass concentration. The ethanol productivity increased linearly with biomass concentration so that, in case of initial sugar concentration, 170g/L, the productivity for 55g/L of biomass density rose up to 30g/L$\cdot$hr for all the batch fermentations. And also the ethanol concentration inhibiting completely the growth was verified 95g/L by applying experimental data to Luong's equation.

• Journal of the Korean GEO-environmental Society
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• v.7 no.3
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• pp.43-54
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• 2006

In this paper, the uniaxial, triaxial compression tests and consolidation tests on the clay sample substituted initial pore water for pollutant were performed to evaluate the change in geotechnical properties of the contaminated clay. The contaminant transport analysis on embankment type landfill using the MT3D model was also performed to evaluate the extent of transport and diffusion. There was tendency that strength, compressibility and permeability has increased with the increase in the concentration of NaCl solution. The increase in the strength and compressibility of sample saturated with leachate was higher than samples saturated with NaCl solution, but in the permeability coefficient was lower. As the result of contaminant transport analysis, the predicted concentration was in high with the increase in the initial concentration of $Cl^-$ ion and increased in a non-linear form. The transportation distance calculated with use of regression equation between the distance from contaminant source and the concentration of $Cl^-$ ion was increased with the increase in the initial concentration.

• Journal of Life Science
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• v.10 no.3
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• pp.247-253
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• 2000

The effects of acute of marine toxicants on early life of coastal olive flounder were investigated. An increasing order of acute toxicity on embryo- and larva-stages of Paralichtys olivaceus was CdCl2$\mu\textrm{g}$/L and 29 $\mu\textrm{g}$/L, respectively, and those values at larva-stage were estimated 3.5 ng/L, 16.0 nL/L, 10.5 $\mu\textrm{g}$/L and 15.0 $\mu\textrm{g}$/L, respectively.

• Journal of the Korean GEO-environmental Society
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• v.23 no.10
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• pp.5-12
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• 2022

In this study, we investigated the UV/H₂O₂ process to treat organic compound-spilled water. In consideration of usage and properties, benzene, toluene, phenol, and methyl ethyl ketone were selected as representative organic compounds. The selected material was first removed by natural volatilization and aeration that simulated the pretreatment of the prcoess. After that, UV/H₂O₂ oxidation experiments were conducted under various H₂O₂ concentration conditions. Benzene and toluene were mostly volatilized before reaching the oxidation process due to high volatility. Considering the volatility, oxidation experiments were performed at an initial concentration of 5 mg/L for benzene and toluene. The UV/H₂O₂ oxidation process achieved 100% of benzene and toluene removal after 20 minutes under all hydrogen peroxide concentration conditions. The phenol was rarely removed from the volatile experiments and oxidation tests were performed at an initial concentration of 50 mg/L. The process showed 100 % phenol removal after 30 minutes under 0.12 v/v% of hydrogen peroxide concentration condition. Methyl ethyl ketone was removed 58 % after 2 hours of volatile experiments. The process showed 99.7% Methyl ethyl ketone removal after 40 minutes under 0.08 v/v% of hydrogen peroxide concentration condition. It was confirmed that the UV/H₂O₂ process showed high decomposition efficiency for the four selected organic compounds, and identified the amount of hydrogen peroxide in classified organic contaminants.

• Korean Chemical Engineering Research
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• v.52 no.5
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• pp.652-656
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• 2014

Mercury amount in vapor phase from 3 types of CFL(compact fluorescent lamp) are estimated by measuring mercury concentration in vapor phase. The mercury concentration in vapor phase from CFL is sharply decreased during initial time and then the change in the mercury concentration is slightly decreased up to 24 hours. The mercury concentration in vapor phase is almost constant after 42 hours, which can be called by stabilized concentration. It can be estimated that the stabilized concentration is caused by the evaporation of mercury in the residues of broken CFL and can be affected by temperature and pressure in crushing apparatus. The mercury concentration for CFL manufactures are in the order of A < B < C as the same results of the initial mercury concentration and the stabilized concentration in vapor phase. As increased air flow rate, the partial pressure of mercury is decreased and the amount of mercury is reduced. Initially, the mercury concentration in vapor phase emitted from CFLs is higher than the regulatory level of $0.1mg/m^3$ in the specific facilities regardless of air flow rate. Hence, it is absolutely necessary that mercury in vapor phase should be controlled at the point of crushing campact fluorescent lamp.

• Korean Journal of Environmental Agriculture
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• v.16 no.2
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• pp.136-141
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• 1997

In this study, we can be obtained the following conclusions about the characteristics of leachate with passed time in the expired landfill. Compared with the expired landfilling H. and S., pH shows a tendency to increase in E., because $NH_3$ is created by anaerobic degradation and dissolved in leachate. The initial BOD and COD of E. and S. are high in similar concentration but H. is low, Since the organics of waste in H. are lower than in E. and S. during landfilling. SS of E. in concentration is increased and very altered, because food of combustible in E. is higher than it in H. and S.. According to passed time, T-N is high in concentration but T-P shows a similar tendency. Heavy metals of leachate is lower than threshold concentrations. If leachate is treated biologically, microbes are not inibitory.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.3
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• pp.377-384
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• 2009

The purpose of this study is to investigate the residual fluoride concentration of fluoride tape in oral cavity which made by spraying NaF on carboxymethylcellulose base. After 1, 3, 5, 7 hours and 1, 2, 3 days of applicating APF gel(60seconds $taste^{(R)}$, 1.23% APF gel, Group I), Fluoride varnish($CavityShield^{TM}$, 5% NaF, Group II) and Fluoride tape(SCMC-T-5, 5% NaF, Trial product, Group III) in oral cavity of 27 healthy adults in their twenties, the result of fluoride concentration in unstimulated whole saliva which measured by using fluoride sensitive electrode made up to following conclusion. 1. Until 7 hours after application in every group, it showed significantly higher fluoride concentration in saliva than baseline value but at 1, 2, 3 days after application, there were no significant differences between measurements and baseline value(p>0.05). 2. Until 7 hours after application at every time, mean fluoride concentration in saliva was higher in the order of Group II, I and III. 3. 1 hour and 3 hours after application, Group II revealed significantly higher fluoride concentration than Group III(p<0.05), but there were no significant differences between Group Ⅰ and Group III in every time.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.24-30
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• 2002

The laboratory adsorption batch tests were performed to investigate the adsorption characteristics of Pb on kaolinite. The characteristics such as adsorption equilibrium time, adsorption capacity, adsorption isotherm were studied, and also the effects of pH and the mixing ratio on the adsorption of Pb on kaolinite were investigated. Test results show that the adsorption equilibrium state was reached within 24 hours, and the adsorbed amount of Pb increased, but the adsorption efficiency over the initial concentration of 198 mg/l decreased, with increasing the initial concentration of Pb. And the adsorption constant, 1/n was obtained 0.9584 by Freundlich isotherm equation. Regardless of the initial concentration of Pb. the adsorbed amount of Pb as well as the adsorption efficiency were increased with increasing pH values and converged to a certain constant value above 8 of pH values. And also the adsorbed amount of Pb increased with the mixing ratio, but its efficiency increased with the mixing ratio up to 8 and then showed the decreasing tendency above that.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.78-85
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• 2008

Evaporation of selected toxic volatile chlorinated hydrocarbons was studied in laboratory soil columns. The evaporation values were obtained for the ten volatile chlorinated hydrocarbons at two different temperatures ($12^{\circ}C$ and $21^{\circ}C$) from columns filled with silty clay loam and sandy loam soils. 1,1,1-Trichloroethane, trichloroethylene and chloroform evaporated considerably (36.7~54.6% removal), carbon tetrachloride, 1,2-dichlorobenzene, tetrachloroethylene, 1,3-dichlorobenzene, dichlorobromethane and dibromochloromethane to a lesser extent (15.3~39.3% removal), and bromoform evaporated poorly (<10 percent removal) at both temperature. Volatile chlorinated hydrocarbons concentration did not affect evaporation, no statistically significant difference in evaporation between the soil types was found. However, temperature affected evaporation, the effect of concentration on the evaporation was not conclusive.