Reduction of Low-MW Model Compounds by Ozonation and O3/UV Processes

In this investigation, the low-molecular-weight organic matters, such as resorcinol, phloroglucinol, and p-hydroxybenzoic acid,
were selected as organic precursors during the ozonation and chlorination processes. The research work focused on evaluating the effects
of hydroxyl radical and ozone molecule on the reduction of organic precursors and disinfection by-products DBP formation, and
assessing the carcinogenic risk with respect to DBP formation potentials between ozonation and O3 /UV processes. The two-stages ozone
decomposition model, O3=O30Fe−K1·t+1−Fe−K2·t, was developed throughout this investigation. In addition, a linear correlation
between alkalinity and hydroxyl radical was found in the course of ozonation process. The destruction of organic precursors by hydroxyl
radical exhibits better performance than that by ozone. According to the risk assessment on the ozonation process, water samples treated
by the O3 /UV and O3 pH 5 process exhibit the lower risk. Therefore, both the O3 /UV and ozonation processes with proper operation
can reduce the organic precursors, thereby providing safe drinking water.