Process optimization and modeling of trichlorophenol degradation by Phanerochaete chrysosporium

The biodegradation of 2,4,6-trichlorophenol and 2,4,5-trichlorophenol by the white rot fungus Phanerochaete chrysosporium was studied in batch and continuous reactor systems. Experiments were conducted in shake flasks as well as in packed-bed reactors in which the fungus was immobilized. The degradation rates in the packed-bed reactors were found to be two orders of magnitude greater than those obtained in the shake flasks in which the fungus was just suspended. The degradation rate was found to be influenced by the concentrations of the carbon and nitrogen sources, pH, and fluid shear stress. Optimal ranges of these parameters to maximize biodegradation were determined. A mathematical model was developed in which the degradation process was assumed to consist of two sequential reaction steps, the first catalyzed by an extracellular enzyme system and the second requiring the presence of the mycelium. The deactivation of the extracellular enzyme system was also accounted for in the model. The Michaelis-Menten and the enzyme deactivation parameters were determined independently. Good agreement between the experimental data and the results produced by the regression was found.