Ecotoxicological Assessment of Landfill Leachate Treated by Coagulation-Flocculation-Sedimentation and Powdered Activated Carbon Adsorption

The isolated evaluation of physicochemical parameters of effluents in landfill leachate treatment is insufficient to determine reductions in acute or chronic toxicity to aquatic biota. Therefore, ecotoxicity tests are essential to assess environmental contamination. This study evaluated the ecotoxicological impacts, through acute and chronic tests on different organisms, of raw landfill leachate, leachate treated with ammonia stripping and activated sludge, and leachate post-treated by coagulation-flocculation-sedimentation (CFS) and adsorption using powdered activated carbon (PAC). Tests with P. subcapitata, C. dubia, D. magna, and A. salina indicated that biologically treated leachate exhibited lower toxicity than raw leachate. However, during post-treatment with CFS combined with PAC adsorption, despite the significant removal of recalcitrant compounds, toxicity increased for P. subcapitata, C. dubia, and D. magna, likely due to residual metals and chlorides from the coagulant and acidifier. Among the tested organisms, A. salina exhibited responses that differed from those of the other species, with a gradual decrease in toxicity observed after each treatment stage. This behavior may be partially associated with its marine origin and potential tolerance to chlorides.