Backpulsing is a method for removing particles which have collected in the pores and on the surface of the membrane using a periodic reversal of the transmembrane pressure. This method is not unlike the back washing technique used to restore the flux through deep bed sand filters.
Clear (non-protein containing) fluid is periodically forced in
the reverse direction through the
membrane using gas to pressurize the backflush reservoir, thus
clearing collected particles out
the pores and lifting off the cake layer. The particles are then
removed by the tangential flow
of the solution across the surface of the membrane, as shown
below:
The average flux vs. time has experimentally been shown to be
higher for systems which
employ backflushing versus systems which do not. A
representative flux vs. time curve is
presented below:
