Separation Science and Technology, Vol.43, No.7, 1595-1609, 2008
Sludge dewatering and aggregate formation effects through Taylor vortex assisted flocculation
For polymer induced flocculation processes, the effects of flow patterns in a gap of a conical stirrer on aggregate formation and subsequent sludge dewatering efficiency were analysed. Different flow regimes were identified by lab scale investigations with model substances and summarized in a Ta and Re number plane. An enhancement of sludge dewaterability for polymer induced flocculation processes was identified through post-treatment of flocculated sludge aggregates by the specific flow pattern of stable and wavy Taylor vortices. Photo-optical image analysis of flocculated aggregates shows a clear change of aggregate size distribution with less small particles during aggregate forming by Taylor vortices compared to classical flocculation procedure by stirrer. Results from technical scale dewatering analyses confirmed enhancement of sludge dewatering efficiency for six different dewatering machines using the identified wavy and stable Taylor vortex flow pattern regime.