PARTICLE TRANSPORT IN POROUS MEDIA: THEORY AND APPLICATION

摘要

For the transport of particles in water flowing through a saturated porous medium, mass-balance particle transport equations and explicit, analytical solutions are developed to define the combined effect of specific transport processes, i.e., advection, filtration, and longitudinal dispersion for both steady-state and transient transport with a constant filter coefficient. The defined transport framework and equations were verified via particle suspension breakthrough experiments. Particle advective velocity was shown to be greater than the carrier fluid and closely matched the theoretical model. Particle longitudinal dispersion was shown to be both similar to solute dispersion and dependent only on the particle advective velocity and media grain diameter, supporting a dimensional analysis model. Particle filtration was shown to transition from favorable to unfavorable filtration gradually and more closely matched a dimensional analysis model developed herein than a previously developed concept. This work has shown that general particle transport in porous media follows the same theory and displays the same behavior as solutes. Furthermore, it was shown that the chemistry of the transport system can have a profound, yet definable, impact on filtration. Historical filtration work has shown that filtration is less favorable for particles with a diameter on the order of 0.1 to 1 micron, for particles with surface charges similar to the media surface charge, and for low ionic strength systems. Thus, a given type of particle would transport further in porous media under these conditions. Some pathogens and some groundwaters possess these properties – these systems may yield long distance transport, similar to those referenced earlier.