Abstract: A hollow body through which a fluid passes that comprises at least one of the following materials:

Abstract: Aerator with a basic body (10) that can be connected to an air feed (50) pipe and with a diaphragm (20), which can be attached to the basic body (10) and whose edge (20r) can be fixed to the circumferentail surface (10r) of the basic body (10) by a static fastening part (30) for the diaphragm (20), which fastening part is designed such that it surrounds the edge (20r) of the diaphragm (20) in a positive-locking manner and can be fixed itself to the basic body (10) wherein the basic body (10) has, on its side facing a way from the said diaphragm (20), a centrally arranged air inlet area (12, 14), on which the fastening part (30) can be placed with a corresponding connection part (36).

Abstract: A sewage treatment plant for the purification of waste water includes a chamber container (1) divided by partitions (4) into different sections (6, 7, 8) for pretreatment, biological treatment, chemical treatment, intermediate or retreatment of waste water, each section (6, 7, 8) having several chambers (6a through f, 7a through f, 8a through f) separated from one another by dividing walls (4, 5), chambers (6a through f, 7a through f, 8a through f) being linkable, with regard to inflow technique, in any pre-selectable association depending on the quantity and type of waste water to be treated, and at least one installation for removal of deposited treatment sludge in each of the areas for pretreatment, intermediate treatment and retreatment.

Abstract: The invention refers to an aeration installation for introducing a gas, in which a cover is arranged on a foundation, through which the gas is able to penetrate this covering through individual, delimitable sections.