The Volute Dehydrator dewatering drum consists of rings with a variable-pitch aguer running through the center. Every second ring is fixed to the barrel assembly and separated by spacers. Intermediary rings are free to move. The internal diameter of the fixed rings is larger than the diameter of the auger. The intermediarey rings have an ID slightly less than the auger and hence are moved in an orbital motion as the auger turns. The movement of the intermediary rings constantly cleans the barrel assembly allowing free drainage of water. This arrangement allows for an extremely low power draw. 

Dilute sludge is introduced into a flocculator tank at the rear of the unit and mixed with a polymer solution to produce flocs. The flocs then overflow into the barrel and free water is drained as they are transported along the auger.  Final compression of the sludge cake at the end of the auger is enhanced by decreasing both the pitch of the auger and the spacing between the fixed and intermediary rings.