The present invention relates to a device for treating a gas/liquid mixture, comprising: an inlet opening for the mixture; an outlet for the mixture located downstream; rotating means arranged in the tube for setting the mixture into rotating movement; one or more outlet openings arranged downstream relative to the rotating means for allowing a part of the mixture to flow laterally out of the tube; a return conduit arranged in axial direction through the rotating means for reintroducing into the tube the flow which has exited via the outlet openings; and divergence means arranged close to the outlet opening of the return conduit for allowing the reintroduced flow to diverge laterally.