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Several Advanced Oxidation Processes (AOPs) including O3/H2O2, O3/TiO2, O3/activated carbon (AC), O3/Al2O3, O3/Fe 2+ /H2O2 and UV/TiO2 have been investigated and compared for the removal of diethyl phthalate (DEP), an endocrine disrupting compound, in aqueous solutions. Hydroxyl radicals were the main species responsible for DEP degradation and this was supported by computational chemistry calculation, scavenger experiments, and LC/MS/MS analysis. The change of the abundance of reaction products over time was determined. Organic acids as well as anhydride and hydroxylated products were found to accumulate in solution even after long reaction time (2h). Careful choice of the operating parameters (pH, ozone concentration and catalyst dosage) was crucial to achieve enhanced performance of the combined processes above what each oxidant and catalyst can achieve alone. O3/AC process was found to reduce the oxidation efficiency of O3 at high ozone concentrations. Heterogeneous catalytic ozonation with Al2O3 was the most effective process for DEP removal (~100% removal in about 15 min) and based on pseudo-first-order kinetics at pH7, the studied oxidation processes followed the order: O3/Al2O3(0.093min-1)>O3/H2O2/Fe 2+ (0.076min-1)>O3/AC(0.069min-1)>O3/H2O2(0.053min-1)>O3/TiO2(0.050min-1)> O3 alone (0.039min-1)>UV/TiO2(0.009min-1).

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Heterogeneous catalytic ozonation (HCO) of wastewater is gaining both research and industrial interests. It is proved to be an advanced oxidation process since it involves hydroxyl radicals as oxidation species. Few studies have been carried out to test HCO in the treatment of landfill leachates. This work has been carried out to test three types of catalysts: activated carbon (AC), expanded perlite (EP) and titanium dioxide (TiO2) combined with ozone at 80 g/m3 gas concentration for the treatment of a leachate generated by Jebel Chakir landfill site near Tunis-capital of Tunisia. The work has shown a reduction in COD of about 45% and an increase in biodegradability (BOD5/COD) from 0.1 to 0.34. A catalyst concentration of 0.7 g/L was found optimal for the treatment of the leachate.