Evaluating effective volume and hydrodynamic behavior in a full-scale ozone contactor with computational fluid dynamics simulation

An ozone reaction model combined with CFD (Computational Fluid Dynamics) technique was developed in this research. In the simulation of ozonation, hydrodynamic behavior caused by bubbling of ozone contacting-gas is important as well as reaction kinetics. CFD technique elucidated hydrodynamic behavior in the selected ozone contactor, which consisted of three main chambers. Back-mixing zone was found in each chamber. The higher velocities of water were observed in the second and third chambers than that in the first one. The flow of the opposite direction to the main flow was observed near the water surface. Based on the results of CFD simulation, each chamber was divided into small compartments, and hydrodynamic behavior and effective volume were discussed. Mass balance equations were also established in each compartment with reaction terms associated with DOC, odor compounds, bacteria, bromide ion and bromate ion. This reaction model was intended to predict dissolved ozone concentration, especially. We concluded that the model could predict favourably the mass balance of ozone, namely absorption efficiency of gaseous ozone, dissolved ozone concentration and ozone consumption. After establishing the model, we discussed the effects of hydrodynamic behavior on dissolved ozone concentration.

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