Toward the Development and Optimization of a Solar Photo-Fenton Degradation Method for Natural Organic Matter Removal in Selected South African Drinking Water Treatment Plants

Natural organic matter (NOM) is one of the major pollutants of concern in drinking water. In this study, the photo-Fenton process was applied for enhanced removal of NOM in drinking water samples collected from four drinking water treatment plants (DWTPs) in the KwaZulu-Natal Province of South Africa. The photo-Fenton process for NOM degradation was performed at pH 3 and a 3:10 ratio of Fe-(II) to H₂O₂ under simulated solar light. Up to 73% UV₂₅₄ reduction and 54% DOC removal after 20 min of irradiation were achieved in batch experiments. A specific ultraviolet absorbance (SUVA) value of 0.89 L/mg·m was attained, which is characteristic of low-molecular-weight organic compounds. Ring-opened oxidation products were detected using the gas chromatography time-of-flight mass spectrometry (GC-TOF MS) multiresidue method. The photo-Fenton process attained 30-55% NOM removal higher than that achieved by the respective sand filters of the DWTPs. Furthermore, the photo-Fenton treatment achieved near-complete (up to 89.0%) removal of chromophoric dissolved organic matter (CDOM) in drinking water. This study presents a potent approach to degrade NOM in drinking water.