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Abstract

Analytical models of floc characteristics are developed as components of a comprehensive flocculation model. The models are derived for reactors with a high ratio of advective fluid transport relative to diffusion (i.e., high Peclet number) and batch reactors where the floc size distribution is expected to be relatively narrow compared with completely mixed flow reactors. High Peclet number flows are obtained in gravity-driven hydraulic flocculators without mechanical agitation. Hydraulic flocculators are an ideal technology for a low carbon footprint and where robust, low maintenance operation is required. The models, combined with measurements of floc sedimentation velocity and floc volume fraction, suggest that the fractal dimension of flocs is approximately 2.3 and that 0.65–1 μm is approximately the particle size beyond which fractal geometry is needed for description of floc properties.

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Fractal Models for Floc Density,Sedimentation Velocity,and Floc Volume Fraction for High Peclet Number Reactors

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