Avaliação da fitotoxicidade e da biodegradabilidade de um lixiviado de aterro sanitário tratado por foto-Fenton induzido por ferricitrato

Abstract

The phytotoxicity and biodegradability of the sanitary landfill leachate (SLL) samples treated by the ferricitrate reaction were evaluated. Thus, using the lab-scale photoreactor based on the batch system, an ferricitrate reaction with pH of the solution 6 and 100 mg Fe L -1 (1:3 of Fe:citric acid) was performed, and samples were taken during the treatment to follow bioassays. Biodegradability was evaluate by Zahn-Wellens test, while the phytotoxicity assays was performed using the Lactuca sativa germinations. Using different dilutions, variables responses such as germination index (GI), absolute and relative germination (AG and RG), relative growth of the hypocotyl and radicle (RGH and RGR) as well as its inhibitions (IRGH and IRGR); were analyzed. In addition, lethal concentrations of 50% tested organisms was calculated (LC 50 ). In such conditions, good responses of COD, BOD, DOC and absorbance at 254 nm reductions were obtained, as well as biodegradability conditions were increased (BOD/COD) confirmed by the biodegradability assays. According to the Zahn-Wellens test, the untreated SLL consist in a low portion of biodegradability compounds in terms of BOD/COD ratio (0.18), which can be increased during the ferricitrate treatment, leading a ≈ 0.26 ratio after ≈ 64 mM of H 2 O 2 consumed. However, the benefits of chemical oxidation of toxic compounds (LC 50 ≈ 15%) was confirmed by the phytotoxicity assays, once that the LC 50 increase to ≈ 53%.