The solid-wall bowl of separating decanter centrifuge has a cylindrical section for efficient separation and clarification of the liquids and a conical section for drying the solids. The product enters the decanter through the feed and passes through the distributor into the separation chamber. The liquid level in the bowl is adjustable via regulating tubes. Due to the centrifugal forces, the solid particles are flung onto the bowl wall. The hardfaced scroll conveys them to the solids discharge which is equipped with hard metal bushes. The liquid phases are separated in the separation zone. For one type decanter the layer thickness of the heavy phase is externally adjustable via regulating tubes; this changes the liquid level in the bowl. The light liquid phase moves in the direction of the bowl axis and is discharged under pressure via centripetal pump. The heavy liquid phase moves in the direction of the bowl shell and is gravity discharged through regulating tubes. In the another type decanter the heavy liquid phase is discharged via centripetal pump while the light liquid phase is gravity discharged through regulating tubes.