COMPARISON OF SINGLE MECHANISM AND MULTI MECHANISM-BASED APPROACHES FOR KINETICS OF SEDIMENT REMOVAL

The process of cohesive particle sedimentation in aquatic environments is perceived as one of continuous formation of aggregates by coagulat ion and their separation from the water column by accumulation on the deposition bed. Over the temporal scales of practical interest for nat ural systems, many physical, chemical, and environmental factors gover n the rate of sedimentation, hence a purely physics-based description has not yet been developed. A new information-based model that uses ex perimental information to derive governing parameters, while predictin g removal through power law relationships, is proposed and tested. Ana lytical solutions derived for this model are shown to be applicable ov er large ranges of concentrations and to various fluid-sediment enviro nments. Comparisons with numerically derived and observed data show th at the analytical model is a versatile tool that improves fundamental understanding of the physical processes involved in sedimentation. The inverse problem of identification and quantification of model paramet er values from experimental results is discussed. Predictions based on average sediment kinetics are found to be in reasonable agreement wit h experimental observations in a variety of special cases examined.