Biological treatment of coal combustion wastes by Acidithiobacillus thiooxidans DSM 26636

The high levels of toxicity generated by the heavy metal content in industrial wastes has generated environmental and health concerns. One of the strategies to reduce the metallic load is the use of sulfur-oxidizing bacteria, due to its ability to produce sulfuric acid involved in the metal leaching. The aim of this research was to evaluate the growth of Acidithioobacillus thiooxidans DSM 26636 and its ability to leach metals from slags and ashes from coal combustion wastes. Microbial growth was monitoring by sulfate and sulfuric acid production. The metal content in slags and fly ashes was determined by ICP-OES. The experiments were carried out during 21 days at 30°C, 150 rpm in 125 mL Erlenmeyer flasks containing 30 mL of Starkey media added with 1% (w/v) of elemental sulfur and 1% (w/v) of slags or ashes. Results showed that Acidithioobacillus thiooxidans was able to leach V, Fe, Mg, Al, Si and Ni from slags. For fly ashes, metal leaching was Al, Ni, Sn, Mg, Zn and Si. Summarizing, Acidithioobacillus thiooxidans could be used for the leaching of different metals contained in wastes from carbon combustion plant.