A pilot scale membraneless system using immobilized peroxidase on porous Celite beads was constructed for the catalytic oxidation of wastewater released from a petrochemical plant. This system was integrated with the electroenzymatic process for enzymatic catalysis using immobilized peroxidase and the electrochemical process for indirect bulk oxidation using generated hypochlorite (ClO(-)). As a result, the chemical oxygen demand (COD) removal efficiency of integrated system was two times higher than those of the discrete processes with lower power Consumption. Thus, by using the integrated system, aromatic compounds in wastewater were effectively degraded and converted into aliphatic organic compounds. During a 30-day operation, 85-93% of the removal efficiency was maintained with 1.99 W g(-1) COD of power Consumption Without severe deactivation of immobilized peroxidase. (c) 2008 Elsevier Ltd. All rights reserved.