Abstract: An apparatus for agitating and transforming settled sludges into slurries which are then capable of being pumped by conventional means. The apparatus comprises a housing immersible in the contents of a tank or chamber and containing separate variable drive means for an impeller and an impeller casing. The impeller casing forms an inlet to the impeller and has a plurality of radially directed outlet nozzles whereby rotation of the impeller effects circulation of the contents of the tank or chamber from the inlet to the outlets and rotation of the casing causes the discharge at the outlets to agitate the contents. The discharge at the outlets breaks up solid sediment at the bottom of the tank or chamber and a continuous recirculation of the contents results in the formation of a slurry.