Experimental study of the immobilization of Acidithiobacillus ferrooxidans on carbon based supports

The effect of graphite surface roughness on the immobilization of Acidithiobacillus ferrooxidans was studied. It was found that the most appropriate surface roughness was obtained by polishing graphite discs with 1500 grit polishing paper. After 24 h of inoculation this roughness had coverage of 25 × 103 cells/mm2. The effects of different types of activated carbon fibers (felt versus fabric; both silicated and non-silicated) on the immobilization of A. ferrooxidans were also experimentally studied. In non-silicated samples the activated carbon fiber support with the greatest surface area per gram (felt) lead to the greatest number of immobilized microorganisms over a 12 h period (29 × 103 cells/mm2). The addition of SiO2 particles to the activated carbon fiber supports considerably enhanced cell adhesion on both activated carbon felt and fabric. Furthermore, the silicated felt exhibited the greatest number of immobilized A. ferrooxidans cells of all activated carbon fiber preparations studied (36 × 103 cells/mm2).