Estimation of the interior permeability of polymer-flocculated sludge flocs.pdf

Advances in Environmental Research 4Ž. 2000 163᎐167
Estimation of the interior permeability of
polymer-ulated sludge flocs
. Wu, . Tsou, . LeeU
Department of Chemical Engineering, National Taiwan Uni¨ersity, Taipei 10617, Taiwan
Accepted 21 April 2000
Abstract
This study estimates the polymer-ulated waste activated sludge floc interior permeability by observing the
motion of individual flocs moving vertically towards an impermeable flat plate. The fluid flow fields surrounding and
inside the flocs were modeled numerically and served as the basis for calculating the hydrodynamic drag force.
Experimental data correspond to the numerical solutions regardless of the floc Reynolds number. According to our
results, polymer ulation produces large flocs with the same global interior structure as the original sludge flocs.
The permeability range for flocs was also estimated based on the floc size investigated. ᮊ 2000 Elsevier Science Ltd.
All rights reserved.
Keywords: Polymer ulation; Permeability; Sedimentation; Settling experiments; Drag calculation
1. Introduction tion or centrifugation of sludge flocsŽ. Wu et al., 1998 .
A non-porous sphere moving through an infinite New-
Floc size and density significantly influence the per- tonian fluid would experience a hydrodynamic resis-
formance of ulation processes. The free-settling tance of FS, as is well documented in th