Bioleaching of trace metals from coal ash using mixed culture of Acidithiobacillus albertensis and Acidithiobacillus thiooxidans

The bioleaching of zinc,manganese,chromium,iron and copper from coal ash (fly and bottom) from coal ash pond using mixed culture of acidithiobacillus albertensis and acidithiobacillus thiooxidans was studied. using the box- behnken experimental design,there are three variable parameters used namely: initial bacterial inoculum,% pulp density and weight of sulfur added. after fifteen days of bioleaching,the maximum percentage metals leached were 56.69% zn,70.68% mn,79.86% cr,70.74% fe and 69.32% cu at different variable parameters. also,the solution has an initial ph value of 2 was decrease from a range of 1.39 to 0.61 due to the oxidation of sulfur via microbial activity. based on the statistical analysis,the experimental data fit the quadratic model for all metal leached. moreover,using numerical optimization the significant parameters are pulp density and initial mass of sulfur. using the optimal parameters,the maximum percent metal leached were 56.38% zn,70.88% mn,85.01% cr,74.44% fe and 74.46% cu. © school of engineering,taylor’s university.