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This work investigated the effect of floc microstructure (size and fractal structure) and shear forces on dewatering processes, which are crucial for environmental and economical aspects in many industries. Due to limitations inherent In experimental investigations, a numerical code using the discrete element method and including some novel force models (polymer bridging force, elastic bending moment and a modified concept of rolling friction torque) was developed to simulate the consolidation behavior of flocculated systems. The code showed good agreement with experimental results. The elastic behavior of aggregates is known to depend on the backbone structure (stress bearing structure of the aggregate). However, there is little known about backbone structure. It was found that backbone represents a fractal structure with a fractal dimension value close to 1 and increasing with increase of aggregate mass fractal dimension. The dewatering process was characterized by compressive and hindered settling behavior. The numerical study of compressive rheology with different aggregate microstructure showed that the compaction results from a reduction of the correlation length rather than increase in fractal dimension. The compressive behavior is consistent with theoretical models at higher compressive stresses but is not well described at low compressive stresses. A semi- empirical model is presented describing the compressive rheology in both regions via a correction factor derived using dimensional analysis. The hindered settling behavior was in good agreement with the theoretical model based on the assumption of self similar structure. The investigation revealed that shear effect is not due entirely to hydrodynamics and can arise from the particle bonding mechanism alone. The study showed that low shear increases compressibility but high shear is detrimental. At low shear, bond bending at local voids results in solid densification. High shear increases kinetic energy and kinetic repulsion of the particles. The effect of shear is analogous to the anomalous behavior of the water density- temperature function. At low temperature bond breakage increases the density and at high temperature thermal expansion decreases the density. The investigation showed that shear increases the permeability due to bending of the structure in the shear direction, resulting in large pores.

Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (M.S.)--Ohio University, August, 2001. / Title from PDF t.p.

Thesis (Ph. D.)--University of Adelaide, Dept. of Applied Mathematics, 1993. / Includes bibliographical references (leaves 117-126).

Thesis (Ph. D.)--University of Adelaide, Dept. of Civil and Environmental Engineering, 1998. / Errata slip inserted. Includes bibliographical references (p. 445-466).

Thesis (M.Eng.Sc.)--University of Western Australia, 2004.

Thesis (M.S.)--Missouri University of Science and Technology, 2009. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 18, 2009) Includes bibliographical references (p. 153-156).

Thesis (M.S.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M.S.)--University of Wyoming, 2007. / Title from PDF title page (viewed on Nov. 7, 2008). Includes bibliographical references (p. 91-92).