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A Study on Characteristics of Sedimentation Rate of Suspended Fine Particles under Floc Size and Density  

Kim, Jong-Woo (경기대학교 공과대학 토목공학과)
Publication Information
Journal of the Korean Society of Hazard Mitigation / v.9, no.4, 2009 , pp. 107-113 More about this Journal
Abstract
This paper considers the influence of floc on the sedimentation rate for the cohesive material. The effects of floc density and size changes were also taking into consideration during the experiment. The settling velocity of a discrete floc was measured in a quiescent water column. Floc diameter and density were investigated using a modified Stokes equation with some constants such as water density, viscosity, material density and the floc fractal dimension $n_f$ obtained from the relationship between the floc diameter and the floc settling. The floc diameter of quartz and alumina increased at increasing initial concentrations. The floc size of quartz with increasing NaCl concentration varied between approximately 0.8 um to $10{\mu}m$. Floc density decreased as floc size increased. The floc settling velocity and the floc diameter have a straight line relationship on a logarithm. The floc fractal dimension nf was 2.65 with increasing of initial concentration and 2.93 with increasing of NaCl. The exponent n to predict the settling velocity was proposed and varied from 1 to 1.93.
Keywords
floc density; size; floc fractal dimension; sedimentation rate; settling velocity;
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Times Cited By KSCI : 3  (Citation Analysis)
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