Evaluation of Metal Bioleaching Property of Actinomyces sp. in Waste Foundry Sand by In-vitro Methods

Abstract

Metals can be leached either directly (physical contact between microorganisms and solid material) or indirectly. The removal of metals from these industrial wastes brings out detoxification of the residues and thus improves the quality of the environment. The waste foundry sand was analyzed for the presence of toxic metals, as the plant uptakes these toxic metals through their food chain which in turn may be harmful to the human beings. In this study Hibiscus was grown on sand blends containing 50% of waste foundry sand (WFS) to assess the availability of Sio2, Al, Ca, Mg, Pb, Cu and Zn. The chemical properties of treated and untreated waste foundry sand were observed. The analysis shows the level of untreated WFS Fe (76.36%), Ca (43.65%) and K (37.49%). Actinomyces sp. was isolated and identified from WFS and was used to bioleach the sand (treated) and was observed to reduce the level of metals present in WFS [Fe (26.54%), Ca (27.67%) and K(5.84%)] and untreated foundry sand had metal levels of [Fe(49.82%), Ca (15.98%) and K(31.65%)]. The treated and untreated sand was later used for growing Hibiscus plant sapling under controlled conditions and was analyzed for the traces of metals absorbed by the plant. The presence of metals was calculated by Atomic Emission Spectroscopy technique that can determine the concentration of trace to major elements. Our observations provide a supportive document on bioleaching of WFS by Actinomyces sp. was adequate in the growth of ornamental plant Hibiscus rosa-sinensis.