Abstract: The invention relates to an apparatus for the treatment of contaminated media, comprising a rotatable housing having at least one inlet (28) for gas emerging in the stirrer housing, and at least one suction opening (10; 32) for the medium to be treated. The housing is provided with a plurality of outlet openings (25; 27) arranged along its periphery. A plurality of vanes (22; 23) are arranged in the outlet openings (25; 27). A rotation transferring means (24) is provided to transfer a rotational movement to the stirrer. A method according to the invention comprises generating a vortex in the medium in such a way that an under-pressure occurs in the center of the vortex, and that a nitrogen containing gas is introduced in the center of the vortex.