Application of trickle-bed reactor and active carbon catalyst to catalytic wet air oxidation of phenolic pollutants is explored over a wide range of operating conditions. The study focuses on the assessment of key engineering aspects such as reactor start-up, gas-liquid flow directions and effects of temperature, pressure, phenol feed concentration and liquid flow rate on activity and stability performance of unsupported active carbon. Moreover, for analyzing the potential integration of CWAO as a pre-treatment in biological wastewater remediation, intermediate distribution and biodegradability enhancement of treated effluents are obtained from HPLC analysis and respirometry assays, respectively. Finally, since slow carbon burn-off is occurring at CWAO conditions, some promising options for improvement of catalyst stability are pointed out on both molecular (iron coating of active carbon) and reactor (periodic reactor operation) scale.