A process for the primary clarification of feeds, including chemically treated flocculated feeds, containing the target biomolecules of interest such as mAbs, mammalian cell cultures, or bacterial cell cultures, using a primary clarification depth filtration device without the use of a primary clarification centrifugation step or a primary clarification tangential flow microfiltration step. The primary clarification depth filtration device contains a porous depth filter having graded porous layers of varying pore ratings. The primary clarification depth filtration device filters fluid feeds, including chemically treated flocculated feeds containing flocculated cellular debris and colloidal particulates having a particle size distribution of approximately about 0.5 μm to 200 μm, at a flow rate of about 10 litres/m2/hr to about 100 litres/m2/hr. Kits and methods of using and making the same are also provided.