The effect of high frequency backflushing on the microfiltration of yeast homogenate suspensions for the recovery of soluble proteins

Periodic backflushing (backpulsing) of the membrane was used to improve the performance of a ceramic tubular membrane for the recovery of a soluble enzyme, yeast alcohol dehydrogenase (ADH), from a suspension of homogenised bakers' yeast cells. Suspensions from concentrations of up to 280 g/l packed cell weight were used. Short (0.1 s) pressure pulses were applied at high frequency (1 Hz) to the permeate side of the membrane by compressed air acting on a diaphragm, causing short periods of reverse flow through the membrane. The intention was that the reverse flow would disrupt the fouling layers on the membrane and enhance forward permeate flux and solute transmission. The result was an increase in solute transmission, by up to 5.4 times in the case of ADH, with a slight reduction in observed permeate flux. The increase in transmission during backpulsing was greater for ADH than for the background of total protein, so some additional product purification was achieved. The resultant effect was an increase in productivity for ADH recovery by backpulsing. (C) 1999 Elsevier Science B.V. All rights reserved.