Development of a VUV-UVC/peroxymonosulfate, continuous-flow Advanced Oxidation Process for surface water disinfection...

Surface waters are often charged with high amounts of natural organic matter (NOM), organic contaminants and pathogens. In this work, a Vacuum UV/PMS process (VUV-UVC/PMS) was employed for treating river water, assessing the simultaneous NOM mineralization and bacterial disinfection. The VUV-UVC process (without PMS) decreased TOC concentration from 3.83 to 0.15 mg/L within 20 min, achieving complete disinfection. Adding 5 mg/L PMS increased the rate of TOC removal by 80%; complete removal of TOC was achieved in 15 min and disinfection was attained twice as fast. The mechanism of NOM mineralization was scrutinized; aeration played a considerable role due to oxygen supply, mixing, and inducing in-situ H₂O₂ production. HO^• and SO₄^•- were the main radical species involved, alongside an important contribution of the matrix; sulfate enhanced TOC removal, due to the formation of additional radicals, underlining its importance. Furthermore, over 99% TOC reduction and complete disinfection was achieved in the VUV-UVC/PMS process operated under continuous-flow mode with a 2-min hydraulic retention time. Finally, the use of Atrazine (ATZ) as a probe compound and a series of scavenging tests led to an integrated proposal for the mineralization of NOM. Accordingly, the VUV-UVC/PMS process is evaluated as an efficient and promising technology for surface water treatment.