Abstract: Device for introducing a gas into a liquid, of the type which comprises a drive motor, a wind box, a gas intake pipe and a radial diffusion turbine coupled to an agitator turbine, the two turbines being immersed in the liquid mass and the gas being conveyed to the centre of the diffusion turbine and distributed between the vanes thereof, wherein the said diffusion turbine has a plurality of long radial vanes alternating with shorter radial vanes, the latter not extending as far as the shaft of the said turbine so as to leave a clear space between the said shaft and the respective internal edges of the said shorter radial vanes, these two sets of vanes being fixed under a plate driven in rotation by the said shaft and the said radial vanes of the diffusion turbine laterally extend the blades of the agitator turbine as far as a region of relative depression situated behind the turbine.