Abstract: In order to produce pellets or agglomerates in an economically feasible manner from clarified sludge which contains disease-causing bacteria and which is dewatered in a solid mantle worm-gear centrifuge (11) and is subsequently thermally dried in the centrifuge housing (14), and which satisfy the conditions of being hygienically unremarkable and also storage-stable, according to the invention it is proposed that the clarified sludge pellets (25), still hot or warm due to thermal clarified sludge drying, are held at their temperature in a sanitizing apparatus (26) for a dwell time of at least 10 min and thus sanitized and additionally dried.

Abstract: According to the present invention, plastic waste mixture is first comminuted, and if required, subjected to magnetic separation and/or eddy-current separation, by which separable metals are removed. The comminuted plastic waste mixture is then mixed with a separation liquid in a mixing tank which has an outlet for heavy phase impurities. This suspension is directed to a hydrocyclone for a first separation procedure. The hydrocyclone is optimally adjusted in such a manner that any remaining unwanted heavy phase impurities together with the heavy phase undesirable plastics, such as the PVC fraction of the plastic waste mixture, is separated from the balance of the plastic waste materials as hydrocyclone underflow. The heavy underflow of the mixing tank and the hydrocyclone underflow may be further reprocessed separately or jointly.

Abstract: The present invention pertains to the separation of mixtures of plastics, contaminated with, among other things, mineral heavy materials such as e.g. sand or metal refuse. Separation occurs according to density in a separating liquid in the centrifugal field of the rotating suspension. The present invention provides the connection of a hydrocyclone before a separating centrifuge. The mineral heavy materials are separated in advance in the hydrocyclone and the plastic mixture is further separated in the centrifuge. Wear on components of the separating centrifuge caused by these heavy materials can be avoided, and in some applications a second separating stage at a higher separation density can be eliminated.

Abstract: A worm centrifuge for separating solids/liquid mixtures is disclosed for overcoming the problems during start-up and shut-down processes that occur when quantity of a liquid is located or remains in the centrifuge drum, particularly the problem of the emergence of liquid at the solids discharge openings during the shut-down process. The inventive centrifuge includes at least one, preferably a plurality of, drum emptying openings distributed over the circumference of the face wall of the centrifuge drum and being positioned radially outside of the liquid discharge openings. The drum emptying openings are each radially crossed by a bore. The bores each include a centrifugal force valve having a spring-loaded closing member adapted to close the drum emptying opening at high drum speed (operating speed) and to open the drum emptying opening at low drum speed.