INVESTIGATION OF THE POSSIBILITY OF USING ACIDITHIOBACILLUS FERROOXIDANS JCM 3863 FOR BIOHYDROMETALLURGICAL RECOVERY OF RARE AND PRECIOUS METALS FROM SPENT CATALYTIC CONVERTERS
VYARA MAMATARKOVA1*, ELENA IVANOVA1, IRINA KARADJOVA2
1 – Department of Biotechnology, Faculty of Biology, Sofia University, “St. Kliment Ohridski”, Sofia, Bulgaria
2 – Department of Analytical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
*Corresponding author: vsavamama@yahoo.com
Keywords: biohydrometallurgy, Acidithiobacillus ferrooxidans, spent catalytic converter
Abstract: Precious metals like platinum, palladium, rhodium (PMG) and also copper have various industrial applications as catalysts. They play a crucial role in the automobile industry as components of the catalytic converter of vehicular tail gases. The iron oxidizing microorganisms Acidithiobacillus ferrooxidans demonstrate high resistance to heavy and toxic metals and has been largely implemented in biohydrometallurgy of copper, zinc, etc. Recently they have been used in the biotechnological treatment of secondary sources of metals, which make them potentially suitable for metal recovering from spent catalysts.
In this work, the experiments included 4 cycles of cultivation of Acidithiobacillus ferrooxidans JCM 3863 in batch in 100 ml original liquid media 9K with 1% inoculum and powder obtained from monolith formed of ceramics and metals from a spent catalytic converter, suitable for Citroen Saxo 2001 car, containing copper. Dynamics of ferrous iron oxidation were investigated in the presence of different amounts of the monolith powder in the range concentrations 10 - 30 g/l, at 28±0.5°C and 190 rpm. The average oxidation rates were estimated and compared with this one without monolith (biological control). Extension of the lag phase adaptation period and decrease of the average oxidation rate has been observed. The process wasn’t inhibited in this range of contents of monolith. The research also demonstrated the ability of Acidithiobacillus ferrooxidans JCM 3863 to leach copper from spent catalyst.