Using bacterial culture supernatant for extraction of manganese and zinc from waste alkaline button-cell batteries

In the present study, the extraction of zinc and manganese from spent 'button-cell' batteries by culture supernatant of Acidithiobacillus ferrooxidans acidophilic bacteria has been investigated. Maximum recoveries of 99 and 53% have been obtained for manganese and zinc, respectively, using 10 g/L spent button-cell powder after 21 days at initial pH of 2 and temperature of 30 degrees C. The results of different analyses performed on spent button-cell powder, prior to and following bioleaching, prove the effectiveness of this bioleaching approach for heavy metals extraction. Chemical leaching of spent button-cell powder is also performed and the results show a higher efficiency of bioleaching. Moreover, it was shown that the bioleaching process is controlled by diffusion processes. Toxicity assessment tests show that the bioleached residue is a non-hazardous material, suitable for safe disposal and meets the environmental limitations. This study indicates the potential of this bioleaching approach to recover heavy metals from spent zinc-manganese button-cell batteries to environmental specifications.