Enzymatic Deinking Method of Old News Paper

Abstract

A new deinking method for old news paper was developed by using commercially available cellulase. About 300 g of old news paper was defibered at 4% pulp consistency by batch type pulper in the enzymeadded water in which pH was controlled at 4.7. And then the suspension was transferred to a laboratory floatation system. The following results were obtained with the deinked pulp from the above-described process.
(1) Handsheet from the DIP showed a satisfactory level of brightness.
(2) Defibering time was reduced significantly, compared to conventional method.
(3) The Canadian standard freeness showed a reduced value for the DIP compared with that from the conventional method. Consequently, an increase in sheet strength was obtained with handsheet from the DIP.
(4) During the defibering and floatating process by this enzymatic technique, no other additives than enzyme and buffer were required, such as NaOH, water glass, synthetic displector, carboxylic acid soap, hydrogen peroxide and DTPA. Therefore, the substantial reduction in operation cost and treating cost with the effluent liquor are estimated by adopting this enzymatic method.