Flotation plant for removal of impurities in water - has the tank under vacuum to accelerate bubble formation

摘要

The lower part of the relatively tall sealed flotation tank of a waste water purificn. plant is connected to a filling tank contg. liq. into which air is injected and dissolved at atmospheric pressure. In the upper zone of the flotation tank, pressure is so reduced by a vacuum pump that the surface of the liq. in the flotation tank is considerably higher than that of the filling tank, the reduced pressure accelerating the formation of air bubbles which attach to the impurities so that the sludge can be floated over a dam at one side and clear water drained off at the other.