FLOCCULATION AND ITS EFFECT ON THE VERTICAL TRANSPORT OF FINE-GRAINED SEDIMENTS

Recent experimental and theoretical work on flocculation and settling speeds of flocs is reviewed. On the basis of this work, an accurate and computationally efficient model of the aggregation and disaggregation of fine-grained sediments is proposed. This model is then used to predict flocculation times and steady-state floc sizes for a wide range of environmental conditions. The predicted flocculation times are smaller, sometimes by as much as two orders of magnitude, than those predicted by mono-disperse theory. The model is also used to show that the disaggregation of flocs due to increased shear near the sediment-water interface may be a possible mechanism for the increased concentrations often observed near this interface.