Seawater desalination and the effective treatment of problematic wasterwaters mitigate the growing global water scarcity. In particular, processes which are facilitated by a semipermeable membrane have gained popularity for water treatment. Although, in recent years, the efficiency of such processes has increased significantly through progress in material engineering of the membranes and optimizing the hydrodynamic conditions in the membrane modules, there is still room for improvement. Especially colloidal deposition on the membranes and concentration polarization lower the processing volume and impede the continuous operation of such water treatment plants. This thesis, which is based on analogous experimental studies, numerically investigates particle transport in a forward osmosis module. By resolv- ing the forces which act on a particle in a fluid flow, the trajectories of the particles can be compared to the streamlines of the fluid flow. In this scope, the local variations in permeate water flux resulting from concentration polarization are incorporated into the model. While the particles in the main flow follow the streamlines of the channel flow with impermeable walls, the influence of the permeate water flux becomes increasingly important as the particle is transported closer to the membrane. In close proximity to the membrane local variations in permeate water flux resulting from concentration polarization also affect the particle trajec- tory. The resulting residence time distribution of the particles in the forward osmosis channel allows for the prediction of the deposition probability, which increases as the permeate water flux increases and as the crossflow velocity decreases. The local particle distribution within one spacer element can be attributed to the dominant particle transport mechanisms.
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Seawater desalination and the effective treatment of problematic wasterwaters mitigate the growing global water scarcity. In particular, processes which are facilitated by a semipermeable membrane have gained popularity for water treatment. Although, in recent years, the efficiency of such processes has increased significantly through progress in material engineering of the membranes and optimizing the hydrodynamic conditions in the membrane modules, there is still room for improvement. Especial...
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