(702e) Combined QCM-D/MP-SPR for Early-Stage Membrane Fouling Detection with Unprecedented Senstivity

Membrane fouling can seriously affect membrane filtration processes and in particular membrane desalination. As fouling cannot be completely avoided, focus lies on optimizing membrane cleaning intervals in order to increase membrane lifetime while reducing process downtimes and cleaning-costs. Interviews with some of the major Spanish desalination operators revealed that until today operators lack a method sufficiently sensitive for detecting membrane fouling at an early-stage which would avoid significant drops in water flux and permit optimizing process operating conditions such as membrane cleaning protocols. Several methods have been proposed for membrane fouling detection but until today none has proven to be sensitive enough to handle membrane fouling in an anticipative way.

This work presents an approach of overcoming the limitations of conventional methods to detect membrane fouling by combining two advanced surface-sensitive techniques: quartz crystal microbalance with dissipation monitoring (QCM-D) and multi-parameter surface plasmon resonance (MP-SPR). The resulting device yielded an accurate, fast, and non-invasive fouling monitoring of unprecedented sensitivity.

Results on an integrated MP-SPR/QCM-D real-time monitoring device integrated into a RO system will be presented. We could successfully demonstrate that QCM-D/MP-SPR enables characterizing the build-up of even the very first fouling layers at the nanoscale and therefore possessed a sensitivity high enough such as to anticipate the need of membrane cleaning before the filtrated water flux decreases. QCM-D/MP-SPR furthermore allowed to test different membrane cleaning strategies in a time-efficient and material-extensive manner, maximizing in this way cleaning efficiency and prolonging membrane lifetime.

The implementation of the QCM-D/MP-SPR-based monitoring device on a industrial scale will be evaluated, and its potential to increase the process efficiency and mitigate membrane fouling will be critically discussed.