N Faraghi - ۱Biotechnology Group, Chemical Engineering Department, Sahand University of Technology, Tabriz, Iran
S Ebrahimi - Biotechnology Group, Chemical Engineering Department, Sahand University of Technology, Tabriz, Iran

This article presents a model based evaluation of ferrous iron oxidation in chemostat and biofilm airlift reactor, inoculated with a mixed culture of T. ferrooxidans and L. ferrooxidans bacteria. The competition between the two types of bacteria in the chemostat and in the biofilm airlift reactors alongside the distribution of both bacteria along the biofilm thickness at different time sections have been studied. The model results demonstrate times when very low dilution rates applied in chemostat reactor; L. ferrooxidans outcompete T. ferrooxidans due to higher affinity of L. ferrooxidans for the substrate than that of T. ferrooxidans. The bacterial distribution profiles along the biofilm in the airlift reactor at different time scales show that in the beginning, T. ferrooxidans bacteria are dominant but when the reactor operates for long time the desirable L. ferrooxidans species outcompete T. ferrooxidans as a result of the low Fe2+ and high Fe3+ concentrations. The optimal treatment performance in airlift reactor is achieved at the loading rates below 140 mol Fe2+/m3.hr and a conversion efficiency of >98%.. This model results are in good agreement with the experimental results in the literature [1].

L. ferrooxidans, T. ferrooxidans, AQUASIM software, H2S removal, Ferrous iron, biofilm airlift reactor, chemostat reactor