Advanced treatment in papermaking wastewater with crude laccase from Coriolus versicolor

Nowadays, most of the wastewater from domestic papermaking mill is treated by secondary process. It has been proved that this method can prominently reduce the pollution load to a certain extent. However, the content of contaminations treated by conventional procedure remains high. As a result, the secondary effluent affects the recipient water and the ecological environment seriously when it is discharged into rivers. Laccase is a kind of potential enzyme that is promising in pulp and papermaking industry. It can catalyze and oxidize lignin. The main effect of advanced. treatment on papermaking wastewater by using crude laccase from Coriolus versicolor has been investigated. The conditions such as treatment time, laccase dosage, pH value and temperature are also discussed. The results indicate that the crude laccase can achieve advanced treatment of papermaking wastewater effectively. The optimum conditions are following: 2.5 hours of treatment time, 5 IU/ml of laccase amount, pH 6, 55 degrees C. When the pollution index of incoming water is 268 mg/L of CODCr, 75 mg/l of lignin and 176 of color units, the pollution indices of the treated water decrease to CODCr 48 mg/L, 12 mg/l of lignin and 10 of color units. The removal ratios of CODCr, lignin content and color are 82.1%, 84% and 94.3% respectively.