Solid mechanics in colloidal and bacterial filtration
Permanent URL:
http://hdl.handle.net/2047/D20263653
Müftü, Sinan (Advisor)
Gu, April (Committee member)
Goluch, Edgar D. (Committee member)
This dissertation addresses this problem by developing a new microfluidic test method and a theoretical model based on contact mechanics. The new microfluidic test simplifies the physics behind microbial/colloidal filtration, and allows us to focus on the surface attachment/detachment due to inter-surface and hydrodynamic interactions. Filtration efficacy was directly measured using this new microfluidic test. The results of the tests were then compared with the conventional flow-through column test. The two show a good agreement with each other. This implies that surface adsorption is the dominant filtration mechanism in the column test. The coupled effect of flow rate, salt concentration and microbial properties were analysed using the classical DLVO theory, fluid mechanics and contact mechanics. The fundamental physics that control the microbial/colloidal attachment were suggested.
We further developed a theoretical model for microbial filtration in a porous medium based on a moment balance method. The fate of an adhered microbial cell after collision with a sand collector was determined by competition between the adhesive moment due to the surface adhesion and the detachment moment due to hydrodynamic interaction. The new model takes into account the effects of flow condition, salt concentration and bacterial micro-properties. The theoretical results agree well with the experimental results, and we believe the new model captures the fundamentals of the problem.
In summary, this dissertation shows the significance of fluid and contact mechanics in microbial/colloidal adhesion and transportation. It reveals the underlying physics and provides a valuable tool-the microfluidic test-for studying the microbial/colloidal filtration problem.
colloid and bacteria
microfluidics
porous medium filtration
solid mechanics
surface adhesion
Copyright restrictions may apply.