Optimization of C/N Ratio and Inducers for Wastewater Paper Industry Treatment Using Trametes versicolor Immobilized in Bubble Column Reactor

C/N ratio and MnSO4 and CuSO4 concentrations were optimized for decolorization and chemical oxygen demand (COD) removal of bleached Kraft pulp mill effluent by Trametes versicolor immobilized in polyurethane foam. Statistical differences (P<0.0001) at high C/N ratios (169), 2 mM CuSO4, and 0.071 mM MnSO4 were determined. Decolorization of 60.5%, COD removal of 55%, laccase (LAC) 60 U/L, and manganese peroxidase (MnP) 8.4 U/L were obtained. Maximum of decolorization (82%), COD removal (83%), LAC (443.5 U/L), and MnP (18 U/L) activities at C/N ratio of 405 (6.75 mM CuSO4 and 0.22 mM MnSO4) was achieved in step 7 at 4 d. Positive correlation between the decolorization, COD removal, and enzymatic activity was found (P<0.0001). T. versicolor bioremediation capacity was evaluated in bubble column reactor during 8 d. Effluent was adjusted according to optimized parameters and treated at 25°C and air flow of 800 mL/min. Heterotrophic bacteria growth was not inhibited by fungus. After 4 d, 82% of COD reduction and 80% decolorization were recorded. Additionally, enzymatic activity of LAC (345 U/L) and MnP (78 U/L) was observed. The COD reduction and decolorization correlated positively (P<0.0001) with enzymatic activity. Chlorophenol removal was 98% of pentachlorophenol (PCP), 92% of 2,4,5-trichlorophenol (2,4,5-TCP), 90% of 3,4-dichlorophenol (3,4-DCP), and 99% of 4-chlorophenols (4CP)