<p>The device is intended particularly for mounting in an oxidation channel (2) containing an intra-channel clarifier (8). The device includes skimming means (10) secured to a wall of the channel by a fixed portion (11) and having a pivotally movable deflector (12) movable between open and closed positions. A drain (18) in a wall of the channel can also be opened and closed so that floating matter can be directed into the drain.</p>
