XRF analysis of coal bioleaching by chemolithoheterotrophic Alicyclobacillus HRM5 and chemolithoautotrophic Acidithiobacillus ferrooxidans

Abstract

Most studies on sulfur bioleaching from coal depend on an autotrophic microorganism with a low growth and a long leaching time. For this reason, heterotrophic heat and acidic pH-resistant <em>Alicyclobacillus</em> was used as the growing and resting cells for the sulfur and iron removal from coal. The results obtained were analyzed by XRF. The data showed that 26.71% of sulfur was removed by <em>Alicyclobacillus</em> in a few days; however, 49.07% of sulfur was removed by <em>Acidithiobacillus</em> in 30 days. This was interesting since the leachings of zinc, strontium, titanium, and iron by <em>Alicyclobacillus,</em> obtained in a few days, were almost the same as the leachings by <em>Acidithiobacillus</em> in 30 days. The results obtained also showed that the <em>Alicyclobacillus</em> cells growing at 55 ˚C removed most of the coal impurities without any change in the carbon content of this fuel. To the best of our knowledge, coal leaching by <em>Alicyclobacillus</em> is reported for the first time.