Toxicity evaluation of landfill leachate after treatment by simple distillation using Danio rerio biomarkers

Landfill leachate is an effluent characterized by a great heterogeneity in its composition, and may contain the most diverse types of organic and inorganic contaminants. Therefore, the leachate needs an efficient treatment before being released into the environment. For this, a lot of treatment processes are being developed and studied, such as simple distillation. To evaluate the efficiency of the treatment, the use of ecotoxicological assays with fish is a useful tool to determine the effects on the aquatic environment of the residual compounds present after the treatment. The aim of this study was to evaluate the efficiency of the simple distillation process in a landfill leachate. For this, in addition to the physical-chemical characterization, the presence of volatile organic compounds (VOC), metals, pharmaceuticals, hormones, and pesticides in the raw (RL) and distilled raw leachate (DRL) was evaluated. Finally, biochemical biomarkers were evaluated in Danio rerio fish exposed to different concentrations of RL and DRL. High concentrations of chemical (COD) and biochemical (BOD) demand for oxygen, nitrogen compounds, sulfates, and chlorides were detected, in addition to fatty acids, long-chain alkanes, alcohols and esters, heavy metals, and six pharmaceuticals. After the distillation process, most of these compounds were reduced by more than 90% and some were removed completely. The biomarkers showed greater changes in the groups exposed to LR and were influenced by the exposure concentration. Thus, the treatment of simple distillation of the leachate proved to be efficient because, in addition to reducing/removing the contaminants, it also reduced the toxicity in D. rerio.