  Sterile filters incorporating endotoxin adsorption function emerged recently
to pretreat dialysate liquids fed to a hemodialysis filtration process. Their
application significantly enhances the survival rate during dialysis treatment
as they function as sterile filters as well as an endotoxin adsorber. Little is
known about the fluid flow distribution in such single use membrane modules. We
report a detailed analysis of the local 3D flow field distribution in such
membrane modules using magnetic resonance flow imaging. Next to pure water
filtration representing the application case of endotoxin adsorption from an
already pure liquid, we also used the module as a filtration device rejecting
for instance colloidal silica. Such experiments performed in-situ allow the
quantification of cake layer development and its concomitant redistribution of
the flow field. Particularly novel is the quantification of the time evolution
of local permeate flux distribution. These detailed insights of this study
encourage the use of flow-MRI when designing and applying new membrane module
configurations.
