Bioleaching of heavy metals from wastewater sludge by ferrous iron oxidizing bacteria

Resumo

Experiments on bacterial leaching of heavy metals from aerobically stabilized surplus activated sludge at the Bortnichi aeration plant in Kiev have been conducted with addition of FeSO₄ • 7H₂O as a stimulant of iron-oxidizing bacteria. The mechanism of heavy metal leaching involving the ferrous iron oxidation by bacteria with subsequent formation of Fe(OH)₃ was confirmed. This process is accompanied by the reduction of pH level of wastewater sludge that results in leaching of heavy metals.