Performance Analysis of Azo Dye Decolorization by Immobilized Trametes versicolor in a Sequencing Batch Reactor

摘要

Azo dyes represent the most important class of textile dyes and pose a serious environmental issue when released in wastewater. White rot fungi decolorize azo dyes efficiently; however, some difficulties arise when they are cultured as suspended pellets. This study analyzed decolorization performance of an azo dye by iTrametes versicolor immobilized on polyurethane foam in a sequencing batch reactor (SBR). The SBR was operated for 27 days with nine cycles of 73.25 h each and dye decolorization of ∼96% ± 1.39%, irrespective of initial dye concentration and the number of cycles. In the SBR, free biomass barely accounted for 5% of total biomass, which did not significantly (ip 0.05) contribute to the decolorization process or biomass conglomerate formation. Along the SBR culture, laccase, manganese, and lignin peroxidase activities were produced with a sustained increase, related to the decolorization process, reaching maximal activities (15.9, 40.4, and 14.4 U/L, respectively) at the end of the culture. Changes observed in the absorption spectrum showed that dye decolorization was related to a change in dye chemical structure, attributed to the action of enzymatic activity. The kinetic study of decolorization and enzymatic activity, by means of a first-order model, suggested that decolorization rates could decrease at higher dye concentrations as well as by increasing the cycle's number in the SBR. On the other hand, higher dye concentration could produce an increase in the total enzyme production rate, probably as a physiological response of the immobilized fungus.