Stress-Controlled Filtration with Compressible Particles

This paper documents a novel filtration technology that incorporates low-stiffness filter matrix particles. The application of isotropic stresses leads to the compression of particles and ensuing pore throat size reductions in the filter matrix. The filtration capacity of the matrix is improved with increasing confinement because the retention of filtrate particles increases due to particulate plugging and bridging on the reduced pore throats. Conversely, relaxing the applied stresses renders system expansion, increased pore throat sizes, and enhanced flushing of entrapped particles from the filter. Experimental results indicate that this technology is most efficient in cases where particle retention occurs due to geometrical constraints (i.e., bridging); however, the system can also render filtration by surface deposition due to the net electrical attraction between the filtrate and filter. Experimental results are analyzed by considering particle-scale filtration mechanisms.