A STUDY OF THE DECOLOURIZATION OF STRAW SODA-PULPING EFFLUENTS BY TRAMETES-VERSICOLOR

The decolourization of straw alkaline-pulping liquors by Trametes versicolor has been studied of the ligninolytic fungi screened, T. versicolor was found to be the most effective microorganism for removing colour from effluents. Fungal biomass immobilized on a plastic surface and fungal pellets were used in flask decolourization assays. The influence of agitation, temperature, type of support and organic and mineral supplementation was evaluated Maximum decolourization was obtained for immobilized biomass and effluents supplemented with 10 g/l of glucose, where about 70% of the initial colour (measured as absorbance at 465 nm) was removed after 4 days. The addition of an inorganic nitrogen source to the effluent reduced significantly the efficiency of decolourization. The possibility of reusing the immobilized biomass to decolourize effluents was examined in three successive cycles. The results showed percentages of decolourization of almost 80% of the initial value for every cycle. The decolourization process by T. versicolor, under the assay conditions, was characterized by a considerable decrease in the pH and an elevated adsorption of lignin-derived products on to the biological matrix accumulated on the plastic support (measured as colour and alkali-soluble lignin content).