On the Origin of Specific Resistance to Filtration

Abstract

Specific resistance to filtration (SRF) is used extensively as a measure of dewaterability. The concept of specific resistance to filtration is based on Darcy's law and is usually interpreted as being of purely hydrodynamical character. This means that changes in electrokinetic properties, brought about by changes in pH and conductance, are not a priori expected to influence the specific resistance to filtration. It is shown that electrokinetic effects do indeed play an important role in the dewatering of bentonite suspensions as the measured values of SRF differ significantly when changing pH or conductance. A theory to understand the phenomena is proposed, but it is also shown that this theory is not adequate to understand the SRF measurements completely.