The accumulation of deposit layers on synthetic membrane surfaces is an important phenomenon during the filtration of foods, pharmaceuticals and water. The deposit layers usually reduce the flow of permeate through the membrane and thereby limit the operation of the system. The deposits can be formed intentionally; as in cakes formed by rejected solids, or they can be undesirable, leading to loss of flux and performance.
Understanding the mechanisms involved in their formation (and removal, as in cleaning operations) is needed to select appropriate mitigation methods or optimal operating conditions. Fluid dynamic gauging (FDG) was originally developed for hard-surface applications. The technique has recently been successfully applied to the analysis of porous surfaces such as filters and membranes. This technique has been reported in the Membrane Technology newsletter (Volume 2007) as one of the ‘new research trends’ in the study of fouling and cleaning in membrane systems. Current membrane FDG research is being directed by Dr. John Chew at the University of Bath, UK.