Biodecolourization of Direct Blue 15 by immobilized Phanerochaete chrysosporium

In vitro and in vivo biodecolourization of structurally different nine direct azo dyes by Phanerochaete chrysosporium immobilized on ZrOCl2-activated pumice was studied in stationary cultures. No lignin peroxidase activity was detected in the extracellular medium of P. chrysosporium. In order to support dye degradation, ligninolytic culture filtrate from fungus, containing mainly manganese peroxidase, was treated with dye. Direct Blue 15 (DB15, 120 mg/l) was determined as the best decolourized dye and its decolourization by immobilized P. chrysosporium was studied in a small-scale packed-bed reactor (PBR). The colour removal efficiency in repeated batches was found as 95-100%. Kinetic analysis of enzymatic decolourization of DB15 indicate that the process is time dependent and follows first-order kinetics with respect to initial concentrations of dye. The rates of colour removal (k values) decrease to a significant extent with increasing initial concentrations of dye. In this decolourization process, it was observed that MnP played an important role while there was no obvious role for LiP and adsorption was determined as a minor mechanism in decolourizing DB15.