Effect of removal of unattached cells on the bio-oxidation rate of pyrite in a fluidised bed reactor

Summary The relative significance of attached and unattached bacteria in bio-oxidation was assessed using a fluidised bed reactor. The unattached bacteria were removed from the system after different times in batch culture. Following wasout, the concentration of unattached bacteria recovered rapidly. This was ascribed to desorption of attached bacteria rather than growth of free, unattached bacteria. Throughout the cell depletion and repopulation phase, the rate of pyrite oxidation remained fairly constant.