liquid or gaseous bleaching and hygiene chemicals such as peroxide caustic soda chlorine ozone or disperging agent fig3 is a view of fig2 according to the arrow marked iii the screw press 1 is linked to the plug screw 8 u2032 via a chute 2 the recycled fibre suspension is then brought to the conveying unit 9 particularly a feed screw where the plug screw 8 u2032 also acts as a vapour trap for the steam fed in through the pipe 10 the disperger 5 is then located behind the feed screw fig4 contains a sectional view through a device according to the invention the illustration shows where the plug screw 8 u2032 joins the feed section 9 of the endless screw to supply the steam connection pieces 11 can be provided at the casing 12 at the beginning of the endless screw or connection pieces 11 u2032 or 11 u2033 at the end section of the endless screw as an alternative chemicals can be fed in through these connection pieces if the conveying unit particularly a feed screw is designed with a hollow shaft 13 steam and or chemicals can also be fed in direction 14 through the hollow shaft it is a particular advantage if spikes 16 are provided between the screw flights 15 with this arrangement the steam can also be fed in easily distributed evenly over the cross section.