Different approaches to improving the textile dye degradation capacity of Trametes versicolor

Trametes versicolor pellets were used in a pulsed fluidised bioreactor with laccase production media to decolourise the textile dye Grey Lanaset G. The effect of the enzyme on dye degradation was analysed. In a batch process, degrading the dye with the fungus results in a decolourisation percentage higher than 90% (initial dye concentration 150 mg/L) while the results were lower than 35% using enzymatic degradation. Although most of the decolourisation was initially due to an adsorption process, later on in both phases, the biomass and the culture broth became colourless. In order to check the possibility of improving the degradation capacity in the batch mode operation, after decolourising the initial dye solution, different pulse dye adding strategies were tested. Adding a large pulse resulted in fast enzymatic deactivation while adding a small pulse caused the system to operate below its optimum degradation capacity. There was a close correlation between the amount of laccase produced and the amount of dye degraded. The system worked in a bioreactor for one month without any operational problems. Finally, in the continuous mode the dye degradation has been demonstrated because it is possible to maintain the continuous production of the laccase enzyme.