We present new approaches to flocculation strategies for the removal of cells and impurities during primary separation for mAb production. The succeeded in reducing the necessary filtration area during depth filtration of the harvest while gaining additional benefits without adding additional process steps. We tested three different flocculation agents, a salt flocculation by Calcium Chloride and polymer based flocculations using Polydiallyldimethylammonium Chloride (pDADMAC) or benzyl modified Polyallylamine (mPAA). All three were combined with Clarisolve® filters optimized for flocculated harvest material. All three options were successful in reducing the necessary filtration area, the most beneficial effect showed pDADMAC. On closer inspection each of the methods revealed additional benefits besides the reduction of filtration area. While pDADMAC and CaCl2 removed virtually all DNA during flocculation given the right condition, mPAA and CaCl2 were able to remove aggregates with little yield losses. We followed the kinetics of CaCl2 and pDADMAC flocculations by Focus Beam Reflectance Measurements (FBRM) and video microscopy. This data can be used if equilibrium conditions are necessary for the further downstream, or can be used to identify pre-steady-state conditions beneficial to the filtration. We demonstrated the suitability of in line continuous flocculation for batch and for perfusion processes by parallelization of the depth filtration. We continuously induced flocculation in a feed stream, included a hold step of fixed length, and the diverted the stream onto one of two filters. Using in line flocculation opens up the opportunity of using pre-steady-state flocculation conditions with fixed time for floc evolution to optimize the filtration. Using three scenarios, classical centrifugation, depth filtration without flocculation and depth filtration, sized and based on our lab scale results, we evaluated the economic benefits of in-line flocculation.

Continuous in line flocculation, new opportunities for primary separation and economic impact

253rd National Meeting (2017)

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