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Updated: Jun 19, 2026

Determination of the Settling Rate of Clay/Cyanobacterial Floccules
Published on: June 11, 2018
[Effects of fractal structure on settling velocities of flocs]
Run-sheng Zhong1, Xi-hui Zhang, Feng Xiao
1Research Center for Environmental Engineering & Management, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China. zrs04@mails.thu.edu.cn
Abstract:
Fractal structures of kaolin and humic flcos by the mass-size method based on the microbalance and free-settling method based on particle image velocimetry technique were investigated. The results showed that kaolin and humic flocs were characterized by fractal structure. The three-dimensional fractal dimensions of Fe flocs with more compact structure ranged from 2.14 to 2.28 are larger than those of alum flocs ranged from 1.75 to 1.83 by the mass-size method. The fractal dimensions of humic flocs are smaller than those of kaolin flocs. The fractal dimension has a close relationship with the settling velocity of flocs. The larger the fractal dimension, the higher the settling velocity. The fractal dimensions by the mass-size method are in good agreement with those by the free-settling method. The measured settling velocities of fractal aggregates do not follow with Stokes' law.
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