UBC Theses and Dissertations
Computational analysis of aerated stabilization basins Toma, Richard David
Simulations of aerated waste lagoons were done using computational fluid dynamics (CFD) techniques and the results were compared with experimental data. A computational model simulated the flow through a previously constructed model aerator and basin. A two-phase, axisymmetric simulation was developed specifically for computing the flow through the geometry of the experimental aerator. A velocity profile was computed at the exit of the aerator and applied to an assumed distribution of droplet diameters. A discrete phase, Lagrangian particle tracking model was then used with the assumed particle distribution, while computing the interactions between the droplets and the surrounding air. The results of the Lagrangian simulation provided an appropriate mass and momentum flux distribution induced by the aerator which could then be applied to a single phase lagoon simulation. A velocity distribution was calculated for the model basin with the same flow rates as in the previous experiments. Using the calculated velocity distribution, it was possible to do tracer studies and compute a residence time distribution for the aerated basin model with an unsteady, species transport model. Reasonable agreement between the simulation and experiments was found. Having validated a method of reproducing the hydrodynamic effects of the experimental aerator, simulations were also carried out on a geometry representative of a 75 horsepower aerator. A parametric study was performed where the volume and the inlet positions of the lagoon where varied. The effects of varying lagoon volume on the residence time distribution were also investigated.
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