Abstract: A sewage ventilating basin of a sewage treatment plant comprises a sewage container which is sunk into the ground and into which project three vertical tubes which connect the surface water of the container with the deepest water thereof. By means of feed pumps, a downwardly-directed flow is produced in the tubes so that the sewage in the container circulates upwardly and recirculates in the tubes. Disposed in each tube in the upper part thereof are devices for the fine-bubble introduction of a ventilating gas. The flow velocity of the sewage in the tube and directly below this upper part is higher than the uplift velocity of the gas bubbles being introduced into the flow at the same point. Since the gas is introduced into the sewage not in the bottom zone of the container but instead in the upper part of the tube, the gas pressure is lower than in the case of the direct introduction of the gas into the bottom zone, and also the energy expenditure is smaller with a high effectiveness of the ventilation.

Abstract: A method of eliminating organic and inorganic bound nitrogen from domestic and industrial waste water in a biological waste water treatment plant consisting of two in series connected stages each containing an aeration tank and a subsequently connected settling basin. Waste water entering the treatment plant will be aerated in the first stage aeration tank and subsequently will be introduced for settling into the settling basin, where the overflow is removed free of oxygen and introduced into the second stage where it will be again aerated and subsequently introduced into the settling basin of the second stage.