Phanerochaete chrysosporium immobilized in calcium alginate gel was used in a fluidized bed reactor for the biobleaching of black liquor. The alginate-entrapped mycelium was activated for 6-24 h in the bioreactor, and different flow rates (10-30 ml h-1) were studied for the continuous biobleaching of black liquor. All the activation periods with different flow rates, resulted in poor reduction in colour and chemical oxygen demand than batch system.