Impacts of morphological, physical and chemical properties of sludge flocs on dewaterability of activated sludge
Journal article, 2004

This study examined how the floc characteristics affect dewaterability of activated sludge. The floc properties were characterised by morphological parameters (floc size distribution, fractal dimension and filament index), physical properties (flocculating ability, surface charge, relative hydrophobicity and viscosity), and chemical constituents in sludge and extracted extracellular polymeric substances (EPS), including the polymeric compounds protein, humic substances, carbohydrates and the ions Ca2+, Mg2+, Fe3+ and Al3+. The dewaterability was defined in terms of the bound water content and capillary suction time (CST). The bound water and CST corresponded to a similar indication with respect to dewaterability of activated sludge. The floc physical parameters were the most important factors which effect significantly on the water binding ability of the sludge flocs. The morphological characteristics had relatively weak impact on the dewaterability. The polymeric components protein and carbohydrate had a significant contribution to enhance the water binding ability of the sludge flocs. The effect of humic substances in the sludge on the dewaterability was, however, insignificant. The CST had good statistical correlations with the polymeric constituents measured in both sludge and the extracted EPS, and the bound water was only correlated well with the individual polymers measured in the sludge. High concentration of Ca2+, Mg2+, Fe3+ and Al3+ had significant improvement for dewaterability.

hydrophobicity

EPS

bound water

CST

metallic ions

surface charge

activated sludge

filament index

polymer constituents

viscosity

dewaterability

fractal dimension

flocculating ability

Author

Britt-Marie Wilen

Chalmers, Department of Water Environment Transport, Water Chemistry and Process Technology

Chemical Engineering Journal

Vol. 98 1-2 115-126

Subject Categories

Other Environmental Engineering

More information

Created

10/8/2017