Fragmentation of wastewater sludge floc by planar ice front
Resource
Journal of Colloid & Interface Science 290(2005), 298–301
Journal
Journal of Colloid & Interface Science
Pages
-
Date Issued
2005
Date
2005
Author(s)
DOI
246246/2006111501275393
Abstract
Floc size has substantial impact on sludge dewaterability, which might be increased or reduced after freezing and thawing. It is commonly
assumed that floc size would be increased by low-speed freezing, with a planar ice front rejecting most flocs ahead of it to form large
aggregates. We demonstrate in this work that an advancing planar ice front can not only engulf an activated sludge floc of size 3030 μm, but
also fragment it. During floc freezing, when the ice engulfed a thin layer of floc, the latter would be pulled apart vertically by the action of
the former. This particular portion of floc was then axially elongated and fixed in the frozen layer, with accumulated force pushing upward.
In the present test the floc’s vertical length was increased by over 92% and its width decreased by 37% over freezing. The force measurement
and floc morphology tracking revealed that the force gradient that pulled apart the floc was 0.0027 N/m. The floc under investigation was
fragmented at the point where the normal stress acting on the interior network exceeded 8 Pa.
Subjects
Freezing
Thawing
Floc
Interface
Force
SDGs
Publisher
Taipei:National Taiwan University Dept Chem Engn
Type
journal article
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