Physicochemical Aggregation and Deposition in Aquatic Environments

Abstract

This chapter describes certain physical and chemical phenomena that affect aggregation and deposition in aquatic systems. Hydrodynamic interactions in aggregation by fluid shear are relatively small for monodisperse suspensions and become increasingly important as the systems become more heterodisperse, i.e., as the size ratio decreases. Surface and solution chemistry controls attachment in aggregation and deposition phenomena in aquatic environments. Modeling the fate of particles and particle-reactive pollutants in aquatic environments requires ability to predict aggregation and deposition rates. Particle deposition is often related to the depth or length of the porous medium within which suspended particles are removed from the flowing fluid. As deposition proceeds in a porous bed, the particles that are removed from suspension can act as new collectors. Hydrodynamic retardation has little effect on mass transport of submicron particles by convective diffusion; it does reduce the deposition of larger particles, and the effect can be described.