(43d) Building Structural Model for Biological Aggregate

The three-dimensional pore structures in waste activated
sludge floc were identified using the fluorescence in situ hybridization (FISH)
and confocal laser scanning microscope (CLSM) images.
The meshes of the three-dimensional porous
configuration of a sludge floc were constructed from the CLSM series images
(Fig. 1). The intrafloc flow field was simulated for the constructed floc model
when it was subjected to a uniform flow field, based on which the Darcy's
permeability was estimated. The permeability (k_DL) of original
floc was estimated as 8x10^-12 m². Flocculated flocs had
higher k_DL due to their large pore size, while the
corresponding values of k_DL of the freeze/thawed flocs were
lower. The calculated results indicate that a few large pores in the floc determine
the permeability. The fractal dimension and compactness, however, are not
correlated with the permeability of the flocs.

KEYWORDS: Structure, floc
model; pore;
CLSM; transport process