A portable assembly for processing red blood cells RBCs including a disposable blood collection set including a blood bag, an anaerobic storage bag and an oxygen and/or oxygen and carbon dioxide depletion device disposed between the blood collection bag and anaerobic storage bag. The portable assembly further provides for a gas circulation device in fluid communication with the oxygen or oxygen and carbon dioxide depletion device. The gas circulation device includes a pressure source that is able circulate flushing gas through the depletion device as RBCs pass from the blood collection bag, through the depletion device and into the anaerobic storage bag.