Enzymatic Deinking in Comparison with Conventional Deinking of Offset News, 1994 Pulping Conference Proceedings

H.-J. Putz, L. Göttsching, K. Renner, O. Jokinen

Several enzymatic treatment procedures for the production of deinked pulp from various waste paper grades have been described in publications and patents. Enzymatic deinking avoids the alkaline environment commonly required and is benefical for chemical savings as well as for minimum COD load of the white water system. The results achieved with offset printed news are related to those of standard alkaline deinking and to a reference trail without chemicals (except a collector). The optical parameters measured are brightness and ink particle area retained. Enzymatic deinking requires special conditions such as pH value, pulping consistency, soaking and reaction times, mechanical shear forces and place of enzyme addition. The procedure proposed for enzymatic deinking results in a deinked pulp quality which is at least comparable to that achieved by conventional alkaline deinking in terms of brightness but cleaner in respect to residual ink particle retained in filter pads.