Abstract: A washing device is provided which comprises at least one inclined wall or floor defining at least one orifice therein, means for causing a washing liquid to flow over the upper side of this wall, means for causing the polluted gas to flow from top to bottom of the device, at least one transverse wall situated below the orifice, and a flow channel having a vertical (or substantially vertical) axis surrounding the transverse wall. This device further comprises a connecting channel whose upper end terminates at the orifice, which has a downwardly divergent shape, and whose lower end is connected to the flow channel.