This study attempted to conduct a synthetic study on biological recovery of heavy metals from spent catalysts using Acidithiobacillus ferrooxidans. This bacterium produces sulfuric acid and helps recovering metals at the same time. It is easily adapted to growing concentrations of heavy metals under optimized conditions (temperature 30°C, Ph 1.9, pulp density 120 μm, rotation speed 160). This study measured Ph, Eh, cellular mass, ferrous and ferric iron concentrations during bioleaching and also bacterium-mediated bioleached content from the spent catalyst. The results revealed that the higher concentrations of spent catalysts could act as a reproduction inhibitor and as a result lower the growth rate of the bacterium. For example, at 200 g/L, bacterium’s cell division occurred once in 8 days and the kinetics of growth was 0.093 per day. Bacteria’s population rose to 504× 10 7 from the initial 1× 10 7 and then fell to 3.6× 10 7 following the death phase. Reaction rate of culture batch containing 200 mg/L Ni followed 2nd order rate (in the presence of Acidithiobacillus ferrooxidans) and the kinetics of reaction was the slope of the line (0.005). Also, reaction rate of culture batch containing 200 mg/L V followed 1st order rate (in the presence of Acidithiobacillus ferrooxidans) and the kinetics of reaction was the slope of the line (-0.086).
In this seminar, I will discuss bioleaching steps, hazards removal efficiency and kinetic of process.

Primary Author/Conference Presenter:
Roya Mafigholami
Assistant Professor
Islamic Azad University – West Tehran Branch
Tehran, Tehran
Iran