A model for flocculation in turbulent flow

A theoretical analysis was undertaken to predict the time dependence of the flocculation of colloids with polymers under the conditions that flocs were destroyed by hydro-dynamic forces and that floc destruction was partially irreversible. Calculations were based on the heteroflocculation of a mixture of large (3 μ radius) and small (0.1 μ radius) spheres. Irreversibility was introduced by postulating that the areas of the surfaces engaged in contact in a floc could not participate in further bond formation after the floc was broken down by shear forces. This treatment predicts that the fraction of small spheres attached to the large spheres increases with time to a maximum and subsequently falls to zero. Parameters affecting the degree of flocculation at a given time include the rate constants for floc formation and disruption, the particle concentrations, and the magnitude of deactivated area per detached particle.