# What are the microscopic events of colloidal membrane fouling?

## TL;DR

This paper uses CFD-DEM simulations to investigate the microscopic mechanisms of colloidal membrane fouling, revealing how particles overcome energy barriers, interact, and influence fouling behavior in microfiltration membranes.

## Contribution

It introduces a coupled CFD-DEM simulation approach to analyze microscopic fouling events, providing new insights into particle interactions and pore geometry effects.

## Key findings

- Particles transition from secondary to primary DLVO minima.
- Adsorbed particles can re-entrain or glide downstream.
- Inner pore geometry significantly influences fouling behavior.

## Abstract

Due to the complex interplay between surface adsorption and hydrodynamic interactions, representative microscopic mechanisms of colloidal membrane fouling are still not well understood. Numerical simulations overcome experimental limitations such as the temporal and spatial resolution of microscopic events during colloidal membrane fouling: they help to gain deeper insight into fouling processes. This study uses coupled computational fluid dynamics - discrete element methods (CFD-DEM) simulations to examine mechanisms of colloidal fouling in a microfluidic architecture mimicking a porous microfiltration membrane. We pay special attention to how particles can overcome energy barriers leading to adsorption and desorption with each other and with the external and internal membrane surface. Interparticle interaction leads to a transition from the secondary to the primary minimum of the DLVO potential. Adsorbed particles can show re-entrainment or they can glide downstream. Since particles mainly re-suspend as clusters, the inner pore geometry significantly affects the fouling behavior. The findings allow a basic understanding of microscopic fouling events during colloidal filtration. The methodology enables future systematic studies on the interplay of hydrodynamic conditions and surface energy contributions represented by potentials for soft and patchy colloids.