Centrifuges

Centrifuges are machines used for the continuous dewatering of sludge through the process of centrifugation, a physical process that applies the force induced by the speed of rotation of a cylindrical structure on the sludge contained in it, in order to separate the solid phase from the liquid phase due to the different density of the two phases. The centrifugal decanter consists of a rotating drum with a horizontal axis inside which is a screw conveyor that rotates with differential speed compared to the drum itself. The sludge, by means of a progressive cavity pump and after the addition of a suitable polyelectrolyte, is fed into the decanter where, with the aid of very high acceleration (over 3000 G), the separation of the water from the solid parts takes place. Through adjustable overflow openings, the clarified water (centrate), separated from the solids, is discharged to the rear of the cylinder. The sludge enters from the same discharge side as the centrate; the separated solids are transported to the discharge point on the opposite side by the differential speed of the internal screw conveyor. A subject to a higher maintenance burden, can achieve significantly higher dewatering yields, especially for sludge that is easily dewatered and without the presence of abrasive compounds; it is typically applied to biological sewage sludge.