Pharmaceuticals and personal care products (PPCPs) have attracted growing concerns due to their ubiquitous occurrence in aquatic environment as well as the potential adverse effects on human health. Conventional water treatment technologies in wastewater treatment plants (WWTPs) are considered to be effective to eliminate these compounds but not the transformation products formed during the PPCPs removal. Moreover, the toxicity associated with the intermediates and transformation products remains largely unknown. The selected PPCPs, DEET, diclofenac and triclosan are the target compounds in this study. Three technologies including ozonation, chlorination and photodegradation, which are commonly used in conventional WWTPs, are employed as the treatment methods in this work. This study aims at elucidating the transformation characteristics of the selected PPCPs with ozonation, chlorination and photodegradation. The emphases are laid on by-products identification, transformation mechanism speculation and bioactivity measurement. The identification of the transformation products were carried out with the aid of ultra-performance liquid chromatography (UPLC) equipped with mass spectrometer Triple Time of Flight (TripleTOF). The bioactivity including microtoxicity, genotoxicity, estrogenic effect and anti-estrogenic effect was monitored and measured with Microtox®, SOS/umu, Yeast Estrogenic Screen (YES) and Yeast Anti-estrogenic Screen (YAS), respectively.

The results demonstrated that the selected parent compounds were readily removed with three different degradation methods. The transformation products were discovered along with the degradation of the parent compounds. However, the biological concerns were not eliminated even though the parent compounds were completely removed. The elevation of the bioactivity was attributed to the formation of the toxic transformation products or intermediates. The positive findings from the bioactivity assays indicated that ozonation, chlorination and photodegradation in WWTPs increased the toxicity potentials of the treated water posing a real hazard to human and environmental health and well-being.