Degradation of nitrogen-containing PPCPs: kinetic study, application, and balancing the toxicity of N-DBP and intermediates through bioassay

In recent years, due the extensive use of pharmaceutical and personal-care products (PPCPs) and the progress of analytical methods, many studies have indicated that some PPCPs may have an adverse impact on environmental as well as on human health. As in the source water the PPCP concentrations are very low, i.e., in μg/L or ng/L level, the conventional water treatment processes can not effectively remove these pollutants. Consequently, the uses of ozone or advanced oxidation process for the removal of PPCP have been gathering the focus in recent years. However, although ozonation can effectively degrade the PPCP, the intermediates as the precursor of nitrogen-containing disinfection by-products forming in the chlorination process should be taken into consideration simultaneously. In addition, the composition and toxicity of ozone intermediate itself have not been fully understood. Therefore, this two-year project is expected to choose representative PPCPs for the further study.. Five nitrogen-containing PPCPs, including acetaminophen, carbamazepine, sulfamethoxazole, diclofenac, and caffeine are used as the target compounds in ozone and chlorination processes. The removal mechanism, oxidation pathway and intermediates, are the key purposes of this study. On the other hand, for the generation of nitrogen-containing disinfection by-products, i.e., HAN, HK, TCNM, this research will further explore the nitrogen mass-balance in the process of ozonation and chlorination, to find the mechanism and pathway of both degradation and transforming of these PPCPs. Finally, this study will use biological toxicity tests (bioassay), coupled with the response surface model, to assess the risk of human health. Balancing the target pollutant removal, chlorination by-products generating, and the toxicity of ozonation intermediates, an optimization procedure can be then proposed.