Abstract: A device for separating inorganic material polluted by organic material from a fluid, especially of sand polluted by organic material in sewage devices, is provided with a circular shaped container (1), which in its upper region has a feed device (19) for the introduction of the fluid into the container (1), with an extractor device (32) for the inorganic material positioned in the lower region (7) of the container (1) and with an extractor device (29) to discharge the organic material and the fluid. A fluidized sand bed (14) is provided in the lower region (7) of the container (1) in order to separate the organic material from the inorganic material. The fluidized sand bed (14) is kept in motion by an upward flow of liquid distributed via a perforated base (8). A by-pass (38) is provided to transfer part of the sand from the fluidized sand bed (14) into the extractor device (32) in the lower region (7) of the container (1).

Abstract: A method for filtering and backwashing solid particles out of liquids is illustrated, with a filter drum (5) positioned completely below the liquid level (6) having a cylindrical surface (7) coated with a filter medium (8), the liquid flown through the outside of the filter drum to the inside. A backwashing device for removal of the filter cake from the filter medium is provided. At the beginning of each cycle of backwashing an air cushion (15) is introduced in the filter drum (5) and liquid in the filter drum (5) is displaced in such a manner so that liquid jets from an ejetion apparatus (19) containing a spraying head (17) and being arranged in the interior of the filter drum without being sealed on the filter drum penetrate through the air cushion (15) to the backside of the cylindrical surface (7) of the filter drum (5). The filter cake so removed from the filter drum is withrawn at the outside of filter drum (5) in a stream of liquid.