Avaliação da fitotoxicidade e genotoxicidade agudas de um lixiviado de aterro sanitário tratado pelo processo foto-eletro-fenton

Abstract

Leachate is one of the may byproducts of the degradation of solid waste in landfills. This effluent is characterized by having a large variety of pollutants, with high concentrations of organic matter, refractory components and compounds that are potentially toxic to the environment. Within this context, the aim of this research was to assess the acute toxicity and genotoxicity of landfill leachate treated by a photo-electro-Fenton oxidation process using Allium cepa e Lactuca sativa, respectively, as bioindicators. The photo-electro-Fenton oxidation process was conducted using soft iron electrodes, UV-C radiation O2 injection, under previously optimized experimental conditions of constant concentration of 300 mg H2O2 L-1, current intensity of 0.9 A and system flow rate of 0.6 L min-1. The system reached a removal of approximately 93% of absorbance at 254 nm and 94% of color in 60 minutes. However, the genotoxicity assays indicated a possible best condition at 15 minutes treatment time, presenting a mitotic index of 5.36% in Allium cepa cells. The phytotoxicity assays indicated a reduction of toxicity to the test organism in all the treatment times, in comparison with the raw leachate. Higher germination indexes and lower rates of growth inhibition of roots and hypocotyls were observed in the organisms exposed to treated samples, with emphasis on lethal concentrations 25.9 and 41.3% higher in comparison to the raw effluent in treatment times of 15 and 30 minutes, respectively. Under the applied conditions, the photoelectro-Fenton process showed to be efficient in the removal of a significant the pollutant load present in landfill leachate and moderately efficient in the reduction of genotoxicity and phytotoxicity for the tested organisms, becoming and alternative for the reduction of environmental impacts caused by the discharge of this effluent in soils and water bodies.