DESCRIZIONE
The device has a flotation tower spaced from a water-receiving reactor and a foam collecting chamber and an injector (4) that has a water inlet side (15) and a water outlet side (16) within the reactor. The injector is provided at the water inlet side with a nozzle (11). The water inlet side is arranged above the flotation tower. A blocking unit (22) is arranged in the injector in the flow direction (S) behind the nozzle and above the flotation tower. The blocking unit is a ball valve. A pipe (19) is arranged at the water outlet side of the injector.