CFD modelling of transient performance of toluene emissions biodegradation in bubble column

A lab scale bubble column (BC) was utilized to treat waste gas containing toluene by free microorganism of Pseudomonas putida WQ-03. The bioreactor had a height to diameter ratio of 10 and a working volume of 17.3 L. The gas stream was injected from the bottom of the BC and then the pollutant was degraded by the bacteria. A complex three-dimensional transient computational fluid dynamic (CFD) model was established for detailed description of toluene treatment in the bioreactor. The model coupled three simultaneous aspects of gas–liquid multiphase flow, interphase mass transfer and intrinsic microbial kinetics. The Haldane's model was adopted for the inhibition of toluene on the growth of microbe and the kinetic constants were obtained experimentally. The simulation was validated by experimental data of the dissolved oxygen and toluene concentrations as well as the toluene removing efficiency. Good agreement between the experiments and the simulation was achieved. Mass transfer and bioreaction were compared to determine the rate-limiting step. The effects of operating parameters were discussed in simulation results and further predictions of the transient dispersions of toluene, oxygen and cell were also provided by the developed model.