Optimization of Lithotrophic Activities of Acidithiobacillus ferrooxidans toward Significant Reduction of Sulfur and Ash from Low Rank Bitumen

Abstract

In the present study, the potential application of Acidithiobacillus ferrooxidans for elimination of ash and sulfur from bitumen was investigated in batch experiments. A comparison between the bioleaching and abiotic treatments indicated that A. ferrooxidans cells enhanced ash and pyritic sulfur removal by 20 and 59%, respectively. The X-ray diffraction profiles of the samples indicated the precipitation of some mineral elements inside of bitumen decreased the bioleaching performance after 9 days from beginning of the experiments. The effects of bitumen particle size (X 1 ), agitation speed (X 2 ) and initial pH (X 3 ) as interfacial factors each at three levels on the ash removal (Y 1 ) and pyritic sulfur removal (Y 2 ) were investigated by response surface methodology (RSM) as a statistical design of the experiment. On the basis of quadratic models applied to the performance of the bioleaching process, 66.42% of the pyritic sulfur and 50.88% of the ash could be removed after 9 days under optimal conditions, namely a bitumen particle size of 100 µm, an agitation speed of 80 rpm, and in initial pH of 2.

Biohydrometallurgy as an environmentally friendly approach in metals recovery from electrical waste: A review

“…Toxic effects of organic compounds in E-waste can decrease iron oxidation rates and may cause suppression of the CO 2 fixation enzymes in the bacteria. Also, experimental observations indicated that the rate of copper dissolution in the bioleaching process was controlled by external diffusion because of the iron hydrolysis and formation of jarosite precipitates on the surface of the material (Chen et al, 2005; Shamshiri Kourdestani et al, 2017). The formation of jarosite precipitate can be prevented by maintaining acidic conditions of the leaching medium at ambient temperature, however at high temperature jarosite precipitation is encouraged even at a pH lower than 2 (Rodrigues et al, 2015).…”