Background and purpose: Presence of natural organic substances in surface water supplies could be harmful and have adverse effects on drinking water treatment due to many practical and hygiene reasons. This study aimed at investigating the efficiency of catalytic ozonation process in removal and mineralization of humic substances in water resources in north of Iran.
Materials and methods: Water treatment plants in Gorgan and Sari were studied (2017). First, the concentration of humic substances was measured in water. Then catalytic ozonation process (COP) of the water samples were performed using semi-continuous cylindrical reactor. The effects of some parameters such as reaction time (0-60 min) and catalyst dosage (0 and 3 g/L) on removal efficiency and mineralization of humic substances were investigated. After determining the kinetics constants of reactions, the removal efficiencies were compared between COP and single ozonation process (SOP).
Results: The concentrations of humic substances in water samples in Sari and Gorgan were 15.22 ± 5.39 and 18.62 ± 6.16 mg/L, respectively. The efficiency of removal of humic acid and its mineralization in the COP process under optimal conditions for Naharkhoran, Sari Salim Bahram, and Alangdare water treatment plants, were 100, 84.21, 88.18%, and 100, 83.4, and 78.03%, respectively. The reaction kinetics were first-order and their rates were 2.6, 2.9, and 3.7 folds more than those of the COP process, respectively
Conclusion: Using magnetic activated carbon catalyst coupled with ozonation process, compared to SOP, is 40% more efficient in removal of humic substances. Also, by reducing the ozonation time and the easy recovery of the catalyst and improving the process efficiency it reduces the costs.