Feasibility studies: UV/chlorine advanced oxidation treatment for the removal of emerging contaminants

UV/chlorine (UV/HOCl and UV/ClO2) Advanced Oxidation Processes (AOPs) were assessed with varying process layout and compared to the state of the art UV/H2O2 AOP. The process comparison focused on the economical and energy saving potential of the UV/chlorine AOP. Therefore the experiments were performed at technical scale (250 L/h continuous flow reactor) and at process energies, oxidant and model contaminant concentrations expected in full scale reference plants. As model compounds the emerging contaminants (ECs): desethylatrazine, sulfamethoxazole, carbamazepine, diclofenac, benzotriazole, tolyltriazole, iopamidole and 17α-ethinylestradiol (EE2) were degraded at initial compound concentrations of 1 μg/L in tap water and matrixes with increased organic load (46 mg/L DOC).UV/chlorine AOP organic by-product forming potential was assessed for trihalomethanes (THMs) and N-Nitrosodimethylamine (NDMA). A process design was evaluated which can considerably reduce process costs, energy consumption and by-product generation from UV/HOCl AOPs.

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► UV/chlorine (UV/HOCl and UV/ClO2) Advanced Oxidation Processes (AOPs) were assessed.
► The UV/HOCl AOP yielded 30–75% energy savings compared to state of the art UV/H2O2 AOP.
► High organic load of the water (46 mg/L DOC) did not significantly reduce AOP yield.
► Assessed process design led to low by-products THMs (3.5 ± 0.4 μg/L), NDMA below detection limit.