Photodegradation of pharmaceuticals and personal care products during UV and UV/H2O2 treatments

Photodegradation characteristics of pharmaceuticals and personal care products (PPCPs) and the effectiveness of H2O2 addition for PPCPs photodegradation during UV treatment were examined in this study. Average k (1st order rate constant) value for all the PPCPs investigated increased by a factor of 1.3 by H2O2 addition during UV treatment using biologically treated water (TW) spiked with the 30 PPCPs. Therefore, the effectiveness of H2O2 addition for PPCPs removal during UV treatment in real wastewater treatment process was expected. It could be also known that H2O2 addition would improve photodegradation rates of PPCPs highly resistant for UV treatment such as DEET, ethenzamide and theophylline. UV dose required for 90% degradation of each PPCP was calculated from k values obtained in UV and UV/H2O2 treatment experiments using TW spiked with 30 PPCPs. For UV treatment, UV dose required for degrading each PPCP by 90% of initial concentration ranged from 38 mJ cm−2 to 5644 mJ cm−2, indicating that most of PPCPs will not be removed sufficiently in UV disinfection process in wastewater treatment plant. For UV/H2O2 treatment, all the PPCPs except seven PPCPs including cyclophosphamide and 2-QCA were degraded by more than 90% by UV irradiation for 30 min (UV dose: 691 mJ cm−2), indicating that H2O2 addition during UV treatment will be highly effective for improving the degradation of PPCPs by UV, even though much higher UV dose is still necessary comparing to for UV disinfection.