(559c) Fouling of Microfiltration Membranes By Bidisperse Particle Solutions

Fouling of filtration membranes is a key process that degrades performance and reduces membrane lifetime. However, it remains challenging to obtain direct information about fouling mechanisms, especially fouling that occurs within the internal pore spaces. Here, we employed highly multiplexed single-particle tracking with alternating laser excitation, which enabled the direct visualization of nanoparticle transport within microfiltration membranes, where the advective motion and retention of 40 nm and 200 nm diameter particles was simultaneously imaged within filtration membranes with 650 nm nominal pore size, as membranes became increasingly fouled as a function of total particle throughput. We found that internal membrane fouling consisted of three stages, fouling site formation, fouling site growth, and fouling site coalescence. Larger particles were more likely to be retained initially, nucleating the fouling sites. These sites, tended to capture other particles passing through the membrane, causing the fouling sites to grow in size. Eventually, isolated fouling sites grew large enough to coalescence with neighboring sites, blocking a large area of membrane pores, leading to significantly fouling. This mechanistic information about internal membrane fouling will assist in the design and optimization of filtration process to reduce membrane fouling as well as advance the understanding of complex mass transport of polydisperse particle distributions.