Estudo do tratamento de lixiviado de aterro sanitário por um sistema foto-eletro-fenton integrado com oxidação biológica

Abstract

Due to its high polluting potential, toxic characteristics and recalcitrance, landfill leachates (LL) demand an adequate treatment before its disposal in the environment, in order to protect public health and conserve ecosystems. In face of the limited efficiency and applicability of conventional treatment processes in the treatment of LL, the investigation, characterization and improvement of advanced techniques become important, aiming to reduce the toxic effects and degrade recalcitrant compounds, increasing its biodegradability. This research investigated the performance of the photo-electro-Fenton (FEF) and aerobic biological oxidation (BO) processes integrated in the degradation of LL. Both processes were assessed in lab scale, using batch reactors. The best experimental conditions of H2O2 concentration, current intensity and flow rate of the PEF system, in 15 min of process, were obtained through a response surface methodology, resulting in 300 mg H2O2 L-1, 0.9 A and 0.6 L min-1, respectively. The BO processes was carried out for 72 hours, using activated sludge from a dairy industry. The strategy that applied the PEF process followed by BO showed the best performance, reaching reductions of 77.9%, 71.5% e 76.3%, in chemical oxygen demand (COD), total carbon (TC) and radiation absorbance in 254 nm (Abs 254 nm), respectively. Additionally, significant reductions in genotoxicity (Allium cepa) were observed by an increase of 131.5% in the mitotic index and a decrease of 47.8% in the abnormalities, besides reductions in the phytotoxicity (Lactuca sativa), verified by the increase in the germination rates and reduction in the plant growth inhibition. The integration of the systems promoted degradation of emerging contaminants identified in the raw LL, highlighting Bisphenol-A (BPA). Thus, the proposed system of PEF followed by BO is presented as a relevant alternative, having good efficiency in the removal of pollutants present in LL, with potential for application in the minimization of the environmental impacts caused by this effluent.