Investigating mixing in baffled ozone contactors using 3-D laser-induced fluorescence and reactive transport model
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Three-dimensional laser-induced fluorescence (3DLIF) was applied to visualize and quantitatively analyze hydrodynamics and mixing in a multi-chamber ozone contactor, the most widely used design for water disinfection. The results suggested that the mixing was characterized by extensive short-circuiting between chambers, internal recirculation within the chambers, and dead zones at the chamber centers. Due to these non-ideal mixing behaviors, the hydrodynamics in the entire reactor showed greater dispersion than a series of completely mixed reactors. These flow patterns could be diminished by decreasing the channel width, while the impacts of the flow rate and baffle gap were negligible within the range investigated. Accordingly, reactive transport model simulations suggested that the overall reactor performance could be significantly improved by preventing these flow behaviors. The 3DLIF technique developed and presented in this study is expected to provide a novel tool for existing reactor diagnosis and retrofitting as well as for new reactor design.