A process and a device for treating and upgrading raw manure. The method and the device comprise steps which consist in promoting agglomeration of solid constituents of the manure and precipitating the agglomerated particles by using a sedimentation agent. More particularly, the sedimentation agent used is based on natural stone and/or industrial derivative dusts. Sedimentation of the agglomerated particles enables the solid phase and the liquid phase to be separately treated, leading eventually to the production of a solid fertilizer, a liquid fertilizer and water corresponding to environmental standards and capable of being released into the environment or simply recycled.