Hydrodynamics of porous flocs in aggregation and sedimentation
Aziz, Julia Joanne
Master of Science thesis
Contaminants in aquatic systems tend to associate with particles and colloidal material and their impact on the environment is dependent on the nature and behavior of these carrier particles. This study investigates the role of aggregation and sedimentation in the fate and transport of particles and aggregates. Computational fluid dynamics modeling illustrates the significance of the hydrodynamics of porous aggregates on aggregation. Aggregation numerical modeling incorporating the porous fractal nature of aggregates results in accurate representations of particle size distribution evolutions compared to laboratory experiments. Settling velocities of aggregates that show non-Stoke's like behavior can be modeled taking into consideration the drag coefficient correction and the fractal porous density of the flocs. Applying the new aggregation and sedimentation model to a resuspension event suggests that the risk of exposure to contaminants in the water column is minimal as a consequence of washout and larger settling velocities of porous fractal aggregates.
Environmental science; Environmental engineering