Device for feeding a container for an installation for the heat treatment and conditioning of waste, comprising a sleeve having a lower opening to be docked with an upper opening of the container, a first line for feeding the waste to be treated connecting to the sleeve and penetrating therein, the sleeve containing a tool for scraping its inner face, wherein the scraping tool is a sheath of axis parallel to the sleeve and forming a terminal section of the first feed line, and the device comprises a support of the sheath, the support being provided with a motorised off-centring mechanism to which the sheath is suspended, the off-centring mechanism moving the sheath in orbits where it is adjacent to the inner face of the sleeve.