Removal of Trihalomethanes in Tehran Drinking Water by an Advanced Oxidation Process

Due to growing population and increasing contamination of surface and groundwater, it is necessary to protect public health by drinking water disinfected with chlorine, the most common method of disinfection. Despite enormous benefits of the chlorination method, there are also disadvantages to human health. Disinfection by-products cause a variety of diseases like cancers in humans. The main group of these byproducts is Trihalomethanes (THMs). Different methods such as adsorption, air stripping packed-column, nano-filtration, and granular activated carbon have been applied to eliminate THMs from water resources. In this study, Advanced Oxidation Process (AOP) method is used to reduce the contamination of THMs in Tehran drinking water. EPA method 551/1 was used for quantifying the analysis of trihalomethane compounds applying a gas chromatography equipped with an ECD detector. AOP method was performed in a photoreactor equipped with 4 UV lamps. The effects of UV radiation, concentration of hydrogen peroxide, and amount of ZnO nanocatalyst on oxidation reaction of THMs have been investigated. Results show that an optimum amount of hydrogen peroxide with and without applying the catalyst was 5 mL of concentrated solution (30%), and the optimum amount of catalyst with this amount of hydrogen peroxide was 0.5 g in 100 mL of drinking water samples with constant reaction time (1hr) and UV irradiation. The yield of THMs removal reaction in these conditions has been determined 91.78 %. One of the most important superiority of this method, in comparison with other THMS removing methods, is the reduction of THMs contamination of drinking water in trace amounts.