Attachment efficiency among fine sediment considering surface heterogeneity

Abstract

Interactions among natural fine sediment particles are essential to the flocculation process, and are affected significantly by surface heterogeneity. In this study, a series of mathematical sediments are generated to characterize the natural particles with different sizes and surface heterogeneities of micro-morphology and charge distribution. The total particles interactions are calculated with Derjaguin–Landau–Verwey–Overbeek (DLVO) theory to theoretically estimate the attachment efficiency (α), where the irreversible and reversible attachment are distinguished. The results show that approaching particles are easier to attached to after collision with increasing particle size (with a fixed size ratio between particles) or increasing similarity in size of both particles. Meanwhile, the electrostatic interactions increase significantly with the presence and enlargement of surface heterogeneities, especially at large separations, which reduces the more approachable reversible attachment, and thus mitigates the flocculation in aquatic systems. This study gives an insight into the mechanism of attachment among sediment considering surface heterogeneities, and provides a quantitative estimation of attachment efficiency which is adaptable for sediment flocculation modelling.