Experiments and CFD simulation of ferrous biooxidation in a bubble column bioreactor

simulation using a commercially available computational fluid dynamics package (FLUENT) were adopted to investigate complex behavior involving hydrodynamics and ferrous biological oxidation in a gas–liquid bubble column reactor. By combining the hydrodynamics and chemical species transport equations, the velocity field, air volume fraction and ferrous biooxidation rate in the column were simulated. The kinetic model proposed by Nemati and Webb (1998) was used to simulate the biooxidation rate in the column. Gas-liquid interactions were modeled using an Eulerian model in three dimensions. The effects of inlet air velocity and initial substrate (Fe +2) concentration on the velocity field, air volume fraction and biooxidation rate of ferrous iron in the column were investigated. To validate the model, simulation was compared with the experimental data in the presence of Acidithiobacillus ferrooxidans in an aerated column where the superficial gas velocity was adjusted between 0 and 0.5 m/s. It was found that the initial ferrous concentration and the inlet air velocity had a pronounced effect on the ferrous biooxidation rate. The results indicated that the maximum biooxidation rate can be obtained at superficial air velocity of 0.1 m/s and initial ferrous concentration of 6.7 g/L. I. INTRODUCTION Bubble column reactors are attracting increasing academic and industrial research interest in view of their many potential applications. Bubble columns are widely used as gas–liquid contactors and as reactors in the chemical, petrochemical and biochemical industries. Effective mixing as well as high interfacial area between the phases, leading to improved heat and mass transfer characteristics, relatively cheap to install and the lack of moving parts, are the factors that render under bubble columns an attractive choice as reactors for the described processes. In chemical and biochemical process engineering, much works have been devoted to either kinetic modeling or fluid dynamics. Most works have been performed under the assumption of idealized conditions. Either the reactor was