Date of Award


Degree Name

Bachelor of Science


Pulp and Paper Technology


The objective of this study was to determine the effect of dispersants on the centrifugal dewatering of a high ash, paper mill, primary clarifier underflow. By using dispersants a higher cake dryness and smaller sludge volume could save the paper industry money.

With this objective in mind, primary deinking sludge samples were defibered and evaluated as to the effect of a dispersant during centrifugal dewatering. The effect of fiber on the dispersants was determined by evaluating sludges with predetermined amounts of fiber fines added prior to centrifugation.

It was found that use of dispersants during centrifugal dewatering resulted in an increased cake dryness and volume reduction for underflows of low fiber concentrations. Also, fiber fines reduced the effectiveness of the dispersants. Therefore, the use of dispersants during centrifugal dewatering helped, but extensive plant trials should be performed before usage.