Abstract: The invention relates to a ventilation element for the introduction of a gas into a liquid, having at least one gas port, having at least one carrier plate and having at least one elastically deformable diaphragm which is connected to the at least one gas port and/or to the at least one carrier plate. A space that can be formed between the at least one diaphragm and the at least one carrier plate is connected in terms of flow to the gas port. The at least one carrier plate has a multiplicity of gas outlet openings, and at least one diaphragm is composed at least in sections of a material with a lower density than water, or is equipped with at least one float body which has a lower density than water.

Abstract: The invention relates to a ventilation element for the introduction of a gas into a liquid, having at least one gas port, having at least one carrier plate and having at least one elastically deformable diaphragm which is connected to the at least one gas port and/or to the at least one carrier plate. A space that can be formed between the at least one diaphragm and the at least one carrier plate is connected in terms of flow to the gas port. The at least one carrier plate has a multiplicity of gas outlet openings, and at least one diaphragm is composed at least in sections of a material with a lower density than water, or is equipped with at least one float body which has a lower density than water.

Abstract: A screening device having screening panels which are oriented transversely to the flow direction of a stream of liquid and each have a screening surface and form a circulating continuous screening belt which can be immersed in the stream of liquid. The successive screening panels form a common screening surface in the sluice channel, wherein the circulatory motion of the continuous screening belt is kept substantially completely within a single plane. The pivot axes about which the screening panels are pivoted at return points of the continuous screening belt are perpendicular to the common screening surface. The screening surfaces of the screening panels have a plurality of recesses and/or elevations running adjacent to one another over the screening surface.