Why we all divide between ATF and TFF

Both concepts – ATF and TFF - see use in the pharma industry. These are the conceptual differences.

Alternating-Tangential-Flow – ATF - a method for perfusion mode operation for continues cultivation under semi-steady-state conditions. Sequentially a broth portion (feed solution) is taken from the bioreactor and alternating (reciprocating) pass the porous membrane. The membrane insure cells in the broth is kept inside the broth (bioreactor) allowing the product to pass the membrane.

Tangential-Flow-Filtration – TFF - a separation method based on range of devices, which allow selected components under pressure to pass (tangentially) from one liquid volume into another liquid volume crossing the “membrane” (cross-flow-filter). In Tangential-Flow-Filtration, a pump drives the feed solution to constantly flow parallel to the surface of the porous membrane. Driven by pressure, some of the feed solution passes through the membrane filter as permeate. Most of the solution is circulated back to the feed tank as retentate.