Flow-Induced Intermittent Transport Shapes Colloid Filtration in Complex Media

Colloidal transport and filtration in porous media are commonly described by single-collector models that assume an underlying homogeneous structure. We use microfluidic experiments, particle tracking, and simulations to observe pore-scale and macroscopic filtration. We show that colloidal trajectories in heterogeneous porous structures are inherently intermittent and composed of flights far from grains and dives near their surfaces, where attachment can occur. We propose a stochastic continuous-time random walk model to link this intermittent behavior to macroscopic deposition profiles and breakthrough curves.