Degradation of 32 emergent contaminants by UV and neutral photo-fenton in domestic wastewater effluent previously treated by activated sludge

This study focuses on the removal of 32 selected micropollutants (pharmaceuticals, corrosion inhibitors and biocides/pesticides) found in an effluent coming from a municipal wastewater treatment plant (MWTP) based on activated sludge. Dissolved organic matter was present, with an initial total organic carbon of 15.9 mg L-1 and a real global quantity of micropollutants of 29.5 mu g L-1. The treatments tested on the micropollutants removal were: UV-light emitting at 254 nm (UV254) alone, dark Fenton (Fe-2+,Fe-3+/H2O2) and photo-Fenton (Fe-2+,Fe-3+/H2O2/light). Different irradiation sources were used for the photo-Fenton experiences: UV254 and simulated sunlight. Iron and H2O2 concentrations were also changed in photo-Fenton experiences in order to evaluate its influence on the degradation. All the experiments were developed at natural pH, near neutral. Photo-Fenton treatments employing UV254, 50 mg L-1 of H2O2, with and without adding iron (5 mg L-1 of Fe2+ added or 1.48 mg L-1 of total iron already present) gave the best results. Global percentages of micropollutants removal achieved were 98 and a 97% respectively, after 30 mm of treatments. As the H2O2 concentration increased (10, 25 and 50 mg L-1), best degradations were observed. UV254, Fenton, and photo-Fenton under simulated sunlight gave less promising results with lower percentages of removal. The highlight of this paper is to point out the possibility of the micropollutants degradation in spite the presence of DOM in much higher concentrations. (C) 2012 Elsevier Ltd. All rights reserved.