Floc Strength in Bridging Flocculation
The growth of flocs in flowing suspensions is limited by hydrodynamic forces responsible not only for floc formation but also for their destruction. New approaches for attaining the maximum stable floc size in turbulent flow have been derived taking into account both the influence of hydrodynamics and particle adhesion within the floc. Modeling is based on the assumption that fluid eddies of the scale of aggregate size are responsible for the destruction of this floc. The validity of this floc stability model was proved by studies on adhesion between glass beads and flocculation of suspensions of such monodisperse glass particles using high-molecular weight polyacrylamides as bridging agents. Batch flocculation experiments were carried out in the turbulent flow of a cylinder stirrer.
Adhesive forces as well as floc properties to a great extent depend on concentration, molecular weight and ionic charge of the polymer flocculant. The experimental results indicate a promoting effect of hydrodynamic forces on floe stability as a consequence of reconformation of the bridging molecules induced by definite stress.
KeywordsAdhesive Strength Adhesive Force Hydrodynamic Force Floc Size Particle Adhesion
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