Background and Aims: Humic Acid (HA) is the most important combination of water humic materials. Removal of this compound leads to decreased production of chlorination by-products. This study set out with the aim of assessing the efficiency of O3, UV and UV/O3 in a plug-flow reactor in order to remove HA from water.Materials and Methods: The removal efficiency was assessed at three distinct steps through raw synthetic water samples containing specific concentrations of HA and treated water measurements of humic acid. Experiments were carried out in a laboratory scale plug-flow combined UV and ozonation system. The first question in this study sought to determine the compounded impact of ozone and UV on HA removal. The subsequent second and third questions in this research were to determine the separate effects of ozone andUV on the removal of target compound.Results: HA removal was slightly augmented in simultaneous presence of UV and ozone reaching 74.7% at initial HA concentration of 15 mg/L, pH 8, and reaction time of 25 min. However, on the question of separate effects of ozone and UV, this study found thatthe removal rate of HA, at similar situations, were 69% and 21%, respectively.Conclusion: Integrated application of UV and ozone outperformed conventional separate use of them in terms of HA removal. Higher removal efficiencies which achieved during ozone treatment, as compared with UV, might be due to higher oxidation power of ozone and OH radicals.Key words: Advanced Oxidation, UV, Ozonation, Humic Aci
