The behavior of suspensions and macromolecular solutions in crossflow microfiltration: An update

More than two decades after the highly-cited review on microfiltration of suspensions and macromolecular solutions, it is time to revisit and update the fundamentals and applications of this topic. This includes addressing inevitable fouling phenomena, the description of fouling, fouling models, means to mitigate fouling and the modernization of membrane modules. Mass transfer limitations, related to concentration polarization and fouling, remain the Achilles' heel. Since empirical expressions that describe fouling offer limited predictive ability and mechanistic insight, there is an urgent need for more in-depth fundamental understanding. Elucidating interfacial interaction energies has gained much attention in recent years; the DLVO model (and its extension) has been validated for a wide range of foulants. The use of molecular dynamics simulations to model transport and fouling represents a major advance, providing insights not possible through experiments. Building on classical fouling mechanisms, new models hold promise to provide more realistic description of fouling phenomena. Fouling mitigation efforts have focused on high-throughput modification platforms and more energy-efficient unsteady-state shear methods. Finally, membrane modules can be modernized based on the knowledge accumulated to better improve their efficiency, and factoring in important considerations like feed type, mechanical stability, hydrodynamics, economics and application goals.