Biological oxidation of ferrous iron in high acid mine drainage by fluidized bed reactor

The biological oxidation of ferrous iron in high acid mine drainage was studied both in the batch experiment and in the fluidized bed reactor with the Amberlite IRA-938 as a support medium. From the batch experiment, the effects of initial ferrous iron and dissolved oxygen concentrations on the specific rate of ferrous iron oxidation could be expressed by Monod type equation. The fluidized bed reactor achieved the ferrous iron oxidation of over 90% within the flow rate region of 0.75 l/hr to 4.5 l/hr. The ferrous iron oxidation in the fluidized bed reactor was not so much influenced by the change in the water temperature. The fluidized bed reactor should be operated under the condition that the influent pH is not more than 2.0 because of the clogging by the ferric hydroxide. Based on the experimental results obtained, a mathematical model which describes the behaviour of ferrous iron concentration in the fluidized bed reaction was proposed. This mathematical model well predicted the effluent concentration of ferrous iron from the fluidized bed reactor at both steady and unsteady states.