Sequential Extraction/Fractionation of Selected Heavy Metals and Their Bioavailability in the Wastewater, Sewage Sludge and Soil Samples of Saygin Dima Textile and Nefas Silk Paint Factories
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Date
2014-06-06
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Addis Ababa University
Abstract
This study focuses on the sequential extraction/fractionation of some heavy metals from industrial wastes of Saygin Dima Textile and Nefas Silk Paint factories in Ethiopia. The investigated heavy metals were Cd, Cr, Cu, Ni, Pb and Zn. Both total concentration and fractional concentration level of the selected heavy metals were determined for comparison of their concentration level and their mobility in the soil. Digestion was used for sample preparation to determine the total concentration and the six step fractionation procedure developed by Tessier was followed for fractional concentration determination. Finally, the concentration level of selected heavy metals was determined by Flame Atomic Absorption Spectrometer (FAAS) and compared with permissible international standard concentration limit.
The experimental results indicated that, Cd was not detected in both total concentration level determination and fractionation. Ni was detected only in total concentration determination. Pb may be mobile in NPSP sample while Zn may be mobile in NPSD, NPSP and SPS samples. Both of these heavy metals are available for animals and plants from the soil polluted by the waste of Nefas Silk paint factory. In addition to this, Zn may be available for animal and plants from the soil polluted by the waste of Saygin Dima textile while the rest heavy metals are not bioavailable from the waste of both factories. The concentration of Cr in NPSD and NPSP, Ni and Cr in SSS, Pb in NSS, and both Ni and Pb in the soil samples of both factories is above permissible international standard concentration limit. Therefore, an appropriate treatment plant must be implemented to minimize the concentration of Ni in the Saygin Dima textile sewage sludge, Pb in Nefas Silk paint factories sewage sludge and both elements in the polluted soil samples of both factories.
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Sequential Extraction/Fractionation, Mobility, Bioavailability, Sewage Sludge, Wastewater, Heavy Metals, Soil Samples, Factory