Floe growth

Because polymer adsorption is effectively irreversible, and because adsorption and floe growth occur simultaneously, flocculation is a non-equilibrium process. As a result, performance is largely determined by the kinetics of adsorption and aggregation. Both of these can be regarded as collision processes involving solid particles and polymer molecules. In each case, collisions can arise due to either Brownian motion or agitation of the suspension. The collision frequency v between particles and polymer molecules can be estimated from °... 

Because polymer adsorption tends to be irreversible, inadequate mixing, with non-uniform distribution of polymer in the particle suspension, cannot be rectified by subsequent rearrangement. Locally high concentrations can lead to rapid floe growth, but with corresponding regions of starvation elsewhere in the... 

The concentration of the polymer solution added to the particle suspension has also been shown to affect process performance. The use of more dilute solutions appears to enhance floe growth. In concentrated solutions, intermolecular repulsion enhances coiling of the molecules, reducing their effective size. Because of the very high adsorption rates, there is insufficient time for relaxation of the molecules, and the surface covered by a molecule and its extension into solution are both reduced. 

High molecular weight polymers are not recommended for destabilisation but can be highly effective in promoting floe growth in already destabilised systems. The order of treatment - destabilisation followed by flocculant addition - is very important. 

Clarifier Rake Arm Mth Pickets (to promote floe growth)... 

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