OH mineralization of norfloxacin in the process of algae bloom water treatment in a drinking water treatment system of 12,000 m3 per day

The accumulation of antibiotics in river watersheds and lakes could induce the spread of antibiotic-resistance genes in drinking water, causing damage to human health. An OH equipment, that produces OH by strong ionization discharge combined with water jet cavitation effect, was installed in a drinking water treatment system of 12,000 m3 per day in Xiang’an water plant, Xiamen of China. The NFX as a model antibiotic was mixed into a branched pipe at a flow rate of 1.0 m3 h−1 for OH mineralization. As a result, the OH after coagulation sedimentation at 1.0 mg L−1 and after sand filtration at 0.5 mg L−1 degraded NFX to not detected within only 20 s. Moreover, the OH mineralizes the NFX into CO2 and H2O by breaking the CF bond, and opening the piperizine, nalidixic, and benzene rings, while NaClO only opens the piperizine ring and adversely forms chlorinated intermediates. By OH disinfection at 0.5 mg L−1 in the main pipe of 500 m3 h−1, all algae blooms were inactivated; the tests of 106 drinking water quality indicators satisfied the Chinese Standards; any disinfection by-products, such as bromate and trihalomethanes (THMs) were not be detected. By NaClO disinfection, the total THMs increased to 190 μg L−1, which is 2.4 times higher than the limit regulated by Environmental Protection Agency (80 μg L−1). To prevent the spread of antibiotic-resistance genes in humans, OH advanced oxidation based on strong ionization discharge could be apply to mineralize antibiotics during practical drinking water treatment.