EFFECT OF OZONATION ON THE TOXICITY OF LANDFILL LEACHATE EVALUATED BY ALLIUM CEPA BIOASSAY

Landfill leachate, also known as percolate, is a complex effluent characterized by high organic load, dark coloration, and the presence of recalcitrant and potentially toxic compounds, posing significant risks to soil and water resources when inadequately treated. Among the available treatment technologies, ozonation has emerged as a promising alternative due to its ability to oxidize complex organic substances through the application of ozone (O₃). However, excessive ozone dosage may promote the formation of intermediate by-products with residual toxicity, highlighting the need for complementary biological assessment of treated effluents. This study aimed to evaluate the efficiency of ozonation in reducing the toxicity of landfill leachate using phytotoxicity assays with Allium cepa seeds and the Germination Index (GI%) as a biological response indicator. Leachate samples were collected from a sanitary landfill located in Candiota, southern Brazil, and subjected to ozone doses of 75, 150, and 300 mg O₃ L⁻¹. Raw and treated samples were tested at dilutions of 1:10, 1:50, and 1:100 (v/v), along with a distilled water control. The results demonstrated that ozonation significantly reduced phytotoxicity, with the intermediate dose of 150 mg O₃ L⁻¹ combined with the 1:50 dilution presenting the highest germination index. These findings highlight the importance of optimizing ozone dosage and leachate dilution to enhance treatment efficiency and ensure greater environmental safety of the treated effluent.