Pollutant removal and acute toxicity assessment (Artemia salina) of landfill leachate treated by photo-Fenton process mediated by oxalic acid

In this research, the application of the organic complexing agent oxalic acid in photo-Fenton reaction was assessed in the treatment of landfill leachate, using a lab scale photoreactor with coupled UVvis - irradiation. The operational parameters [Fe3+] and initial pH were studied in central composite rotatable design, and assessed through a response surface methodology. The best operational conditions were observed at pH 7.8 and 90 mg Fe3+ L-1, with around 5.8 kJ L-1 accumulated energy and consumption of approximately 220 Mm of H2O2, obtaining reductions of 52.5 and 47.0% in color and Abs 254 nm, respectively. A high efficiency of the mediated photo-Fenton process as a function of the accumulated energy profile (0.0-9.8 kJ L-1) was observed, with significant reductions of biochemical oxygen demand, chemical oxygen demand, total dissolved carbon and dissolved organic carbon, as well as an increase in the biodegradability ratio. Additionally, a high degradation of several molecular structures present in the landfill leachate was observed via gas chromatography-mass spectrometry, which was associated with the low toxicity of the treated effluent (LC50 of 67%), showed by the Anemia sauna bioassays. Thus, the mediated photo-Fenton process presented a high efficiency in the reduction of the toxic effects of the landfill leachate, contributing with the minimization of the environmental impacts caused by its discharge in soils or water bodies.