The influence of floc size, density and porosity on sediment and contaminant transport

This paper examines the influence of floc size, porosity and density on the transport of suspended sediment (flocs) and associated contaminants. Results demonstrate that as floc size increases the settling velocity increases. Settling velocity is also influenced by the relationship of floc density and porosity to floc size. As floc size increases, the density decreases and approaches that of water. This relationship is related to the concomitant increase in porosity, and therefore water content. The role of flow through flocs (pores) as a possible explanation for the settling of large low density flocs is discussed. Equations for describing the relationship of floc porosity and density to floc size are provided and discussed in relation to floc transport.