Browsing by Author "Kim, Sang-don"

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Comparative Study of Pb2+ Removals and Isotherms by Physically - and Chemically - Modified Agro - Wastes from Tanzania
(Gwangju Institution of Science and Technology, 2016) Rwiza, Mwemezi; Lee, Su-yeon; Kim, Sang-don
Materials and Methods Raw corn and rice husk were washed several times using DIW to remove extraneous dirt and contaminants. The husks were then dried at 110 ºC overnight to remove moisture. Dried husks were then ground and sieved only using the 35 mesh fraction. The ground husks were pyrolyzed into biochars. The biochars were in turn treated with either ZnCl2 or KOH. Biosorbents were characterized by BET, FTIR, SEM, pHPZC and CEC. Biosorption experiments were conducted using ground husks, biochars, and chemically-modified biochars. Equilibrium modeling was carried out using Langmuir, Freundlich, DR, and Temkin models.
Geochemical Distribution of Trace Elements in Groundwater from the North Mara Large-Scale Gold Mining Area of Tanzania
(Ground Water Monitoring and Remediation, 2016-05) Rwiza, Mwemezi; Kim, Kyoung-Woong; Kim, Sang-don
The infl uence of large-scale mining operations on groundwater quality was investigated in this study. Trace element concentrations in groundwater samples from the North Mara mining area of northern Tanzania were analyzed. Statistical analyses for relationships between elemental concentrations in the samples and distance of a sampling site from the mine tailings dam were also conducted. Eleven trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined, and averages of Fe and Al concentrations were higher than levels accepted by the Tanzanian drinking water guideline. Levels of Pb in three samples were higher than the World Health Organization ( WHO ) and United States Environmental Protection Agency ( USEPA ) drinking water guidelines of 10 and 15 µg/L, respectively. One sample contained a higher As level than the WHO and USEPA guideline of 10 µg/L. The correlation between element concentrations and distance from the mine tailings dam was examined using the hierarchical agglomeration cluster analysis method. A signifi cant difference in the elemental concentration existed depending on the distance from the mine tailings dam. Mann–Whitney U -test post hoc analysis confi rmed a relationship between element concentration and distance of a sampling site from the mine tailings dam. This relationship raises concerns about the increased risks of trace elements to people and ecosystem health. A metal pollution index also suggested a relationship between elemental concentrations in the groundwater and the sampling sites’ proximity from the mine tailings dam.