Date of Award


Degree Name

Bachelor of Science


Paper Science and Engineering


This is a study comparing the effectiveness of removing ink particles, consumption of water, and the retention of coating and/or filler pigments in deinked pulp between the flotation washing method and the counter-current sidehill washing method. Coated magazine waste paper was deinked using 5.3% Sodium Hydroxide at 190°F. The washing stage of both methods was carried out at a .9% consistency and a temperature of 30°C. The results of the study indicate that the flotation method of washing deinked pulp removed the majority of ink particles but did not remove the coating and filler pigments. The sidehill on the other hand, removed most of the coating and filler pigments while retaining more ink particles then the flotation method. The flotation method consumed less water than did the counter-current washing method.