MICROBIOLOGICAL LEACHING OF 'URANIUM FROM SOME EGYPTIAN ORES ALLOGA AREA, SOUTH WESTERN SINAI

Abstract

Seven fungal spec1es were isolated from two uranium ore samples taken from the Alloga region, South Western Sinai, Egypt. They were identified as Aspergillus flavus, Penicillium brevicompactum, P. oxalicum, P. purpurescens, P. lividum, A. terreus and P. spinulosum. They were tested for their bioleaching activity of uranium from the studied ore materials. A. terreus and P. spinulosum showed a high leaching activity . The amount of uranium solubilized by A.terreus and P. spinulosum was increased with increasing the ore concentration in the growth media, reaching its maximum value at 4% (w/v) of the ore. Whereas, the highest percentage of uranium released by both fungi was obtained at 1% (w/v). At this concentration, the released uranium by A. terrues and P. spinulosum was 75 and 81.5% for the ore OS1respectively, and 72.8 and 77.6% for OS2 respectively. The best leaching occured when the final pH

was shifted toward acidity. Biosorption of the released uranium by the fungal mycelium was also increased with increasing ore concentration in the growth media. A. terreus and P. spinulosum secreted some organic acids such as ascorbic, nicotinic, malonic and citric acids. The amount of these organic acids decreased with increasing the ore concentrations. Oxalic acid was secreted only by A. terreus at an OS1 1% concentration of ore. The optimum parameters for uranium solubilization by the two

fungi were 30°C, 6 days of incubation, pH 4, sucrose as carbon the source, NILtCl as the nitrogen source, 0.2 mm particle size and 1% ore concentration . The application of all of these optimum conditions for uranium solubilization by A. terreus and P. spinulosum was studied. A. terreus solubilized approximately 88.8 and 77.2% of the uranium found