Kinetics of Fe2+oxidation in down flow packed bed fixed film reactors

Abstract
Thiobacillus ferrooxidans was immobilised on granular activated carbon and granular charcoal as supporting matrix in packed bed reactor for oxidation of ferrous sulphate to ferric sulphate. Both the material displayed favourable organisms hold up and immobilisation characteristics with the efficiency of ferrous oxidation around 99 per cent. However granular charcoal would be a preferable medium for immobilization as it is more economical compared to the granular activated carbon. These systems were operated at pH range of 2 to 2.5 in order to minimise the ferric iron precipitation. The kinetic studies have shown that the activated charcoal reactor can be operated at 40 g of Fe2+/1/hr with Ks of 0.293 g/l. SEM studies of the support matrices showed profuse growth of the bacterial film on the surfaces. In addition to attached growth, the bioreactors also supported dispersed growth of bacteria in the surface opening and interstices.