(30h) Simulation of Toluene Emissions Biodegradation in Bubble Column By Computational Mass Transfer

A computational mass transfer (CMT) model for simulating the bioreaction process in bubble column is proposed. In the proposed model, the conventional method of k-ε model is used for closing the momentum equation for the fluid dynamics; while for the closure of the turbulent mass transfer equation, the recently developed models of concentration variance c² and its dissipation rate ε_c are adopted, thus the turbulent mass transfer diffusivity can be determined without assuming the turbulent Schmidt number or using the experimental measured dispersion coefficient as did in a traditional method. With the proposed model, the species concentration distribution and turbulent mass diffusivity distribution along the bubble column can be predicted. To validate the proposed model, simulation is carried out for the biodegradation process of toluene emissions in a bubble column. The simulation results are compared with the experimental data in literature and satisfactory agreement is found between them. Furthermore, the simulations reveal that the turbulent mass transfer diffusivity varies along axial and radial directions, and the turbulent Schmidt number is not a constant throughout the bubble column. Thus, comparing to the traditional method with constant turbulent Schmidt number, the proposed method can fundamentally guarantee more reliable results on concentration distribution in the whole bubble column.