TREATMENT OF KRAFT BLEACHING EFFLUENTS BY LIGNIN-DEGRADING FUNGI .1. DECOLORIZATION OF KRAFT BLEACHING EFFLUENTS BY THE LIGNIN-DEGRADING FUNGUS IZU-154

Three white-rot fungi (IZU 154, Phanerochaete chrysosporium Burds. and Coriolus versicolor (L. ex Fr.) Quel.) were tested for their abilitie s to decolorize kraft bleaching effluents from the first alkaline extr action stage. The fungus IZU-154 exhibited the effective decolorizatio n of not only hardwood but also softwood kraft pulp bleaching effluent . For the softwood bleach plant effluent containing 10000 color units (CU), treatment with IZU-154 in the presence of a small amount of gluc ose (0.5%) resulted in 78% and 89% reductions of the color after one- and two-day incubations, respectively. On the other hand, when the eff luent was treated under the same conditions, only 32% and 36% of the d ecolorization with C. versicolor and 49% and 72% of the decolorization with P. chrysosporium were observed within one- and two-day incubatio ns, respectively. In comparison with 53% and 78% of color reductions a chieved by IZU-154 with the softwood bleach plant effluent including g lucose, addition of glucono-delta-lactone to the effluent showed remar kable decolorizations of 83% and 94% within 12- and 24-hour incubation s, respectively. Furthermore, the color of the effluent was effectivel y removed by the addition of acetic acid as an additive. Therefore, a greater color reduction by IZU-154 can be expected for a possible biot echnological application.