An imperforate bowl centrifuge for phase separation employing a rotatable outer cylinder having an interior wall with a plurality of indentations each with an orifice, and an outer wall with heavy phase waste routing channels leading from the orifices to a waste control valve. Separated heavy phase particles collect in the channels and flow by force of pressure, and exit through the waste control valve at one end of the outer cylinder when it is opened to release the waste. An outlet for the separated light phase fluid is disposed at another end of the outer cylinder. The channels in the outer wall may be axially or angularly disposed to force the separated heavy phase toward the waste control valve.