Direct Observations of Particle Behavior in a Porous Medium: Evidence of Particle Entrapment and Hindrance


Friday, February 4, 2005, 3:30PM

Room 825 SWM Building

Patricia J. Culligan

Associate Professor, Department of Civil Engineering & Engineering Mechanics Columbia University , New York

An understanding of how particles in the micron to submicron range behave in porous media is important to a number of environmental problems involving subsurface flow and contaminant transport, water and wastewater treatment and soil pedology. The behavior of particles in a porous medium is complex and influenced by factors such as the particle density, size and surface chemistry, the interstitial liquid chemistry, the interstitial velocity and the heterogeneity of the porous medium . The goal of this work was to provide new insight into the physical factors influencing particle movement and attachment in a uniform, saturated porous medium. To meet this goal, a technique for visualizing particle transport in the interior of a porous medium was developed. The technique, which includes the construction of a translucent medium and the use of laser induced fluorescence for particle tracking, was used to examine the behavior of a 50 mg/L suspension of negatively charged, micron-size, non-Brownian particles in the interior of 4 mm diameter glass bead packs. Particle behavior during transport through the beads was examined as a function of flow velocity, flow direction and bead surface roughness. The seminar will describe the visualization technique, present the results of the transport experiments, and discuss the insight gained from the results.