Bacterially generated Fe2(SO4)3 from pyrite, as a leaching agent for heavy metals from lignite ash

Abstract

Investigations of heavy metals from lignite ash, which is a coal combustion by-product, have for years been very interesting from different aspects of environmental protection. In this study, the possibility of microbiological ash leaching, with a strong oxidation agent, bacterially generated Fe2(SO4)3 was investigated in order to minimize the concentration of toxic ash elements. Leaching experiment by the shake flask testing technique was performed during a period of 20 d at a temperature of 28 °C. The results obtained show 5- to 22-fold (for Cd and Ni approx. 5, Zn approx. 6, Mn approx. 8, Cr approx. 13 and Cu approx. 22) higher metal leaching efficicency in the suspension with bacterially generated Fe2(SO4)3 than in the control suspension.

Keywords

• Acidithiobacillus ferrooxidans
• heavy metals
• coal ash