Bioleaching for the Removal of Arsenic from Mine Tailings by Psychrotolerant and Mesophilic Microbes at Markedly Continental Climate Temperatures

This study investigated the biological removal of heavy metals from mine tailings in Kazakhstan using acidophilic microorganism strains Acidithiobacillus ferrivorans 535 and Acidithiobacillus ferrooxidans 377. The experiments were conducted in shake flasks at pH 1.6, various temperatures (28 degrees C, 18 degrees C, and 8 degrees C), and 10% solid concentration (w/v). The results of inductively coupled plasma optical emission spectroscopy and X-ray diffraction analyses showed that arsenic was particularly efficiently removed at 28 degrees C. At this temperature, A. ferrooxidans 377 was more efficient at removal than the other strain. Meanwhile, A. ferrivorans 535 was more efficient than A. ferrooxidans 377 at 8 degrees C. One of the more significant findings to emerge from this study is that arsenic can be removed at a low temperature and high solid concentration. The results of this study support the idea that microorganisms can be used for removing arsenic via a combination of biooxidation and chemical methods.