Kinetic degradation of anti-inflammatory drugs in ozone combined free active chlorine system

In this study, free active chlorine (HOCl/OCl - , FAC) was employed as an activator of ozone (O 3 ) to remove typical non-steroidal anti-inflammatory drugs of aspirin (ASA) and phenacetin (PNT). The combination of FAC and O 3 significantly improved the removal of pollutants. O 3 molecules, hydroxyl radicals ( OH) and reactive chlorine species (RCS) contributed to the removal of target contaminants in O 3 /FAC system. By fitting the pollutant removal pattern with the experiment and model, the contribution of each oxidative species in O 3 /FAC system was measured. The average removal contribution of O 3 , OH, and RCS to ASA/PNT was 10.3%/8.4%, 53.8%/10.5%, and 35.9%/81.1%, respectively. Compared with O 3 alone system, the average mineralization of pollutant in O 3 /FAC system increased from 20.6% to 34.0%. The formation of five typical CX 3 R-type disinfection by-products (DBPs) was evaluated with post-chlorine system. The maximum concentration of total DBPs was achieved at pH 6.0 of 12.5 μM, in which trichloromethane (TCMs) was the main component (accounting for 55.3%). This study provides a new method to remove contaminants based on the combination of O 3 and FAC disinfectants.