The Effect of Kaolin Concentration on Flock Growth Kinetics in an Agitated Tank

Radek Šulc, Ondřej Svačina


This paper reports on an investigation of the effect of initial solid particle concentrationon flock growth and flock shape characterized by the fractal dimension Df2. The experiments werecarried out in a baffled tank agitated by a Rushton turbine at mixing intensity 64W/m3 and constantdimensionless flocculant dosage DF/ck0 = 4.545 mg/g. The model wastewater (a suspension of tapwater and kaolin) was flocculated with Sokoflok 56A organic flocculant (solution 0.1% wt.). The size and shape of the flocks were investigated by image analysis. The flock growth kinetics was fitted according to a semi-empirical generalized correlation proposed by the authors. The dependences Af = 100.35ck01.532,  df,eq,max = 1.0474ck0-0.311 and (NtF)max = 1622ck0-0.393 were found. The fractal dimension Df2 was found to be independent of flocculation time and initial kaolin concentration, and its value Df2 = 1.470 ± 0.023 was determined as an average for the given conditions.


flocculation; flock growth; flock size; mixing; Rushton turbine; kaolin slurry; fractal geometry; image analysis

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ISSN 1210-2709 (Print)
ISSN 1805-2363 (Online)
Published by the Czech Technical University in Prague