1 OPTIMISATION OF BIOBLEACHING PROCESS OF UNBLEACHED KRAFT PULP Acacia mangium BY USING CRUDE LACCASE

The importance of laccase role in lignin degradation has led to the use of laccase in bleaching processes of pulp. Crude laccase enzyme was used for pretreatment of bleaching processes on unbleached kraft pulp Acacia mangium. Optimisation of biobleaching was conducted by Response Surface Methodology (RSM). Three significant factors which were pH, temperature and reaction time were studied to evaluate the decrease of Kappa Number. The result showed that optimised decrease of Kappa Number of 5.37 points was achieved at pH, temperature and reaction time of 7, 30°C and 4 hours, respectively. Biobleaching at the optimised conditions was then followed by chemical process bleaching i.e chlordioxide (D0), alkaline extraction (E) and chlordioxide (D1). Pulp viscosity, fiber length, brightness and Adsorbable Organic Halide (AOX) content were investigated and compared to no biobleaching pretreatment. There were no significant effects to pulp viscosity, fiber length, and brightness on the biobleaching pretreatment. The reduction of AOX about 30 % was demonstrated by using crude laccase biobleaching pretreatment. Therefore, laccase biobleaching is promoted as bleaching treatment in order to be an environmental-friendly of bleached pulp production