The present study evaluated the ability of organic acids (leaching agent) produced by three filamentous fungi coded as MNSS-AH-5, MV-AH-2 and MV-AH-1 obtained from tailings samples to remove Ni and V from spent catalyst at 16 % (w/v) pulp density. Organic acids were produced in 500 mL Erlenmeyer flasks containing 150 mL of sucrose media where flasks were inoculated with 10% (1x107 conidia/mL) of each fungus and incubated during 6 days at 30°C, 150 rpm. The leaching agent produced by MNSS-AH-5, MV-AH-2 and MV-AH-1 in sucrose media were assayed to remove Ni and V from spent catalyst at 16% (w/v) pulp density during 7 days at 30°C, 150 rpm. At the end of incubation, Ni and V content was evaluated in bio treated catalyst samples by ICP-EOS. Controls containing sucrose media were included in order to evaluate the action of culture media on leaching; all experiments were done in duplicated. Results showed that after 7 days of incubation, the organic acids produced by MNSS-AH-5 were able to leach 2525 mg/Kg of Ni corresponding to 21 %, not significance difference was observed for organic acids of MV-AH-2 and MV-AH-1. In the case of V, all bioleaching treatments presented statistical difference observing a V leaching of 10921.8, 11099.3 and 4757.5 mg/Kg corresponding to 23.5, 24 and 10% for MNSS-AH-5, MV-AH-2 and MV-AH-1 respectively.
Isolate MNSS-AH-5 was identified as Acremonium sp., MV-AH-2 and MV-AH-1 were identified as belonging to genera Penicillium. Based on results, this study shows that leaching agent produced by fungi could be an excellent biological alternative for the removal of Ni and V spent catalyst.
Effect of pulp density on the bioleaching of metals from petroleum refinery spent catalyst
