A sequential process for water treatment involving usual adsorption on activated carbon (AC) followed by wet air catalytic oxidation of the adsorbed pollutants has been carried out in a fixed bed reactor with a mixture of two model pollutants. The first step achieves water purification while the second one reduces the organic pollution but also, more importantly, performs some AC in situ regeneration. The experimental work has been done with AC yet extensively used and stabilized by long range continuous oxidation. The two steps have been analysed successively showing very important drop of adsorption capacity with respect to fresh AC but efficient oxidative partial regeneration. As expected with used AC no more evolution occurs in between two consecutive runs. The first step of competitive adsorption has been simulated by a model leading to higher diffusivities than estimations based on correlations. The main features of the complex second step, involving simultaneous non isothermal desorption and three phase catalytic reaction, are qualitatively explained.

Catalytic Wet Air Oxidation (CWAO) has been investigated for the treatment of water contaminated by 4-hydroxybenzoic acid (4HBA) and equimolar mixture of phenol-4HBA. Both batch measurements for kinetics determination and continuous fixed bed operation have been performed on the same Activated Carbon (AC). After a fast initial deactivation AC was proved stable and efficient at moderate temperature and oxygen pressure, like for phenol degradation.The kinetic study in the case of highly adsorbing material as AC may require complex approach to account for the variation of adsorbed reactants during batch oxidation. Adsorption isotherms at reaction temperature and with aged AC have been obtained according to Langmuir equation and used in 4HBA mass balance to derive more significant kinetic parameters. At high catalyst loading and relatively low pollutant concentration, the variation of 4HBA during the batch may be even higher on the solid than in the aqueous phase.

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