Apparatus and method for centrifugal separation utilizing a movable collection assembly

The invention provides an apparatus for separating a multiphase mixture into discrete density phases, comprising a circular bowl rotatable about a central axis and having an opening through which the mixture is introduced into the bowl, whereby the rotation of the bowl separates the mixture to form annular columns of the discrete density phases; a delivery conduit inserted into the bowl through the opening for introducing the mixture into the bowl; and a collection assembly for removing the separated discrete density phases, comprising a collection conduit for collecting the annular columns, a waste collecting conduit, and a cleaning conduit. The collection assembly is movable as a single unit with respect to the bowl such that it can be positioned within the bowl to sequentially, selectively and individually remove the annular columns from the bowl while the bowl is rotating substantially without disturbing the remaining annular columns within the bowl.