Decolourisation and detoxification in the fungal treatment of textile wastewaters from dyeing processes

Abstract

In this study a selected fungal strain, Bjerkandera adusta (Willdenow) P. Karsten MUT 3060, was tested in different culture conditions to assess its real potential for bioremediation of textile wastewaters in terms of both decolourisation and detoxification. The fungus efficiently decolourised (colour removal up to 96%) four simulated wastewaters that mimic the recalcitrance of real ones for pH values, concentration of dyes, additives and salts. In the culture condition with the lowest N content, the decolourisation was coupled with an important detoxification of two simulated effluents, underlining the important influence of the cultural medium composition not only on the degradation but also on the detoxification of industrial wastes. In the other cases, despite an extensive decolourisation, no detoxification was observed. The fungus was further tested against a real effluent, collected from a wastewater treatment plant before and after the tertiary treatment (ozonation) to compare the two technologies in terms of chemical and toxicological parameters. The fungal treatment, although less efficient than ozonation, caused a good decolourisation of the effluent, with colour values within the threshold limits of the Italian law; both the fungal and the ozone treatment caused a detoxification, but only towards one of the three organisms used for the ecotoxicological tests. These results underline the crucial importance of the ecotoxicological analysis in assessing the applicability of a wastewater treatment.