doi:10.1016/j.watres.2020.115636engMosteo, RosaVaron Lopez, A.Muzard, D.Benitez, N.Giannakis, S.Pulgarin, C.Visible light plays a significant role during bacterial inactivation by the photo-fenton process, even at sub-critical light intensitiesART-2020-117174The aim of this research is to clarify the contribution of sunlight wavelengths, irradiance and Fe2+/H2O2 during bacterial disinfection by the photo-Fenton process in clear surface waters. We considered different solar spectrum distributions (visible, UVA-Visible), sub-critical irradiances (0–400 W/m2), focusing on the action modes of E. coli inactivation by the constituents involved in the composite process, at low µM reactants concentration (Fe2+/H2O2) in in ultrapure (MQ) water. We report that solar disinfection improved with Fenton reagents (photo-Fenton process) is a reality from very low light irradiance values (200 W/m2), and made possible even without the presence of UVA radiation, even when using low quantities of the Fenton reagents (0.5 mg/L Fe2+, 5 mg/L H2O2). Under light exposure, H2O2 was found to augment the intracellular Fenton process and Fe2+ to initiate further, distinct oxidative actions. Finally, validation was performed in Lake Geneva water over a wider irradiance range, where the photo-Fenton process was found to be reagent-dependent in low irradiance, shifting to light-driven in the higher values.2020http://zaguan.unizar.es/record/16510310.1016/j.watres.2020.115636http://zaguan.unizar.es/record/165103oai:zaguan.unizar.es:165103info:eu-repo/grantAgreement/ES/DGA-FEDER/T51-17Rinfo:eu-repo/grantAgreement/ES/MCIU/RYC2018-024033-Iinfo:eu-repo/grantAgreement/ES/MICINN/PRX18/00107WATER RESEARCH 174 (2020), 115636 [14 pp.]All rights reservedhttp://www.europeana.eu/rights/rr-f/info:eu-repo/semantics/closedAccess