Figure 1.

Typical harvest process flow diagram for a (A) continuous centrifuge harvest process, (B) MF harvest process, and (C) a flocculation harvest process. The harvested clarified supernatant is processed further by the downstream purification process to produce drug substance (not shown). A flocculation harvest processing involves: 1) flocculant addition and mixing, 2) flocculent settling, 3) clarified supernatant removal, and 4) a two-stage filtration train to prevent flocculent contamination of the harvested supernatant and clear cytotoxic flocculant from the process stream. A typical MF harvest process is performed by limiting the permeate flux in a trans-flow filtration mode to minimize filter fouling. A low shear disk stack centrifuge is routinely used to harvest mammalian cells.