Device and process for the removal of air from flotation foam formed during the flotation of a paper-fiber-containing suspension. The device includes a driven rotor that includes a shaft and at least one rotor blade positioned on the shaft, and a non-rotating wall arranged to surround the rotor in a region of the rotor blade by a non-rotating wall. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.