PURPOSE: To make the structure of this apparatus simple, to make the amt. of discharge of scum adjustable and to make installation of the apparatus easy by providing a feed well wherein an arm holding scum skimmer and a rear part movable in the up and down direction, a rotating and driving device for the arm and a skimmer vibrating device for the scum skimmer are provided.

CONSTITUTION: A scum skimmer 2 is held horizontally by means of an arm 10 and a skimmer vibrating part 9 of a feed well 6, and it collects scum floating on the water face while it is rotated by means of a driving motor 8. When the collected scum is taken in the scum skimmer 2, the rear part of the scum skimmer 2 is lowered below the water face by means of the skimmer vibrating part 9 and the collected scum is scooped in the scum skimmer from an inlet 5. When the scum is discharged, the rear part of the scum skimmer 2 is pushed upward by means of the skimmer vibrating part 9 and the taken-in scum is discharged in a scum discharge box from a discharge outlet 3. As described above, the scum skimmer 2 itself can be used in parallel as a scum discharge pipe.