Described are systems, methods, and kits for compression sedimentation and whole blood separation. For example, a compression sedimentation system may include a compression stage configured to accept a flexible reservoir configured to contain a liquid mixture. The compression stage may include a base substrate and a compression substrate configured to apply a force to the flexible reservoir effective to create a pressure in the liquid mixture. An apparatus for whole blood separation may include a sedimentation system that separates whole blood into a supernatant including platelet rich plasma and a subnatant including red blood cells. At least one platelet-concentrating device may be included to receive the supernatant including the PRP and to separate a platelet concentrate and a platelet poor plasma from the supernatant.
