Vibrating Membrane Filters (VMF)

PallSep™ Vibrating Membrane Filtration Technology is an enabling technology for difficult processes where the security of a polymeric barrier process is required, but where feed materials are very high in complex mixtures of biomolecules and viscosities may be elevated. PallSep filtration units represent a significant innovation in membrane filtration.

In all membrane processes, shear forces are generated above the membrane surface to counteract the effects of membrane fouling. With PallSep technology, shear is generated by horizontal vibration of the membrane elements through the feed fluid over fifty times per second. The shear, which is higher than that typically generated in conventional tangential flow filtration (TFF), is limited to a small boundary layer above the membrane surface and not applied to the bulk of the fluid. This means that fluids may be processed in a very gentle manner, through an open flow path with minimal pressure-drop (even transmembrane pressure distribution) to high suspended solids levels (>60% w/v)*.

The Biotech PallSep PS 50 device consists of an encapsulated stack of 0.2 micron polyethersulfone (PES) membrane elements (0.2, 1 or 5 m2 membrane area), which are mounted on a torsion bar. Kinetic energy from a small motor is efficiently converted to vibrational energy in the stack whose oscillation is controlled by a frequency converter. The Biotech PallSep device is typically used for process-development work with fluid volumes between 2 and 100 L.

The principal applications for the Biotech VMF system involve characterization of cell homogenates and extracts from plants and animals sources that are difficult to process by either conventional TFF or centrifugation. Examples are direct processing of mycelial fermentation broths without pretreatment and recovery of cell wall fractions from chemically-lysed recombinant bacterial systems used to produce therapeutic vaccines.