Abstract: A decanter centrifuge which includes an annular bowl, a hollow tube on the axis of the bowl, and means for discharging from the bowl a first phase of an input sludge, the centrifuge being characterized by a fluid-activated airlift device which includes a discharge line radially supported from the hollow tube, and a fluid supply line for conveying fluid from within the hollow tube to an outer end portion of the discharge line to effect removal from the bowl through said line of another phase of the sludge.

Abstract: A decanter centrifuge for separation of light and heavy phase material and composed of a rotatable bowl with discharge orifices for the different phases and containing a screw conveyor with a hub supporting helical flights defining a helical chamber divided into a separating zone and a discharging zone by a baffle connected between an adjacent pair of the flights and providing a restricted passageway between the zones, the baffle comprising a flap hinged to the hub so as to be closed under centrifugal force during operation of the centrifuge.

Abstract: A centrifuge for the separation of materials having different densities such as solids and liquids or liquids of different densities has partitions therein disposed generally perpendicularly to the material flow within the centrifuge which form a series of chambers within the centrifuge for respectively retaining floating layers of materials of particular densities, with each chamber being equipped to discharge the material retained therein. Retention and transfer of the materials of different densities is achieved by selective termination of the partitions within the centrifuge at respective heights and depths to accommodate a desired material layer height. An improved separation is attained thereby so that the discharged phases are in substantially pure form.