Phytoremediation of young landfill leachates using Chrysopogon zizanioides: evaluation of heavy metal removal and post-treatment toxicity

• Chrysopogon zizanioides effectively removes cadmium (Cd) and lead (Pb), and reduces COD from young landfill leachates. • Plant growth and morphology were evaluated under leachate concentrations ranging from 25% to 100%, with 75% showing optimal performance. • Maximum removal efficiencies of 98% for heavy metals and 53.2% for COD were achieved at 75% leachate concentration. • Ecotoxicological tests with Caenorhabditis elegans confirmed significant detoxification after vetiver treatment. • Combined morphological and toxicity analyses demonstrate the resilience and phytoremediation potential of C. zizanioides. Landfill leachates are highly complex and hazardous mixtures containing significant concentrations of heavy metals such as cadmium (Cd) and lead (Pb), alongside high chemical oxygen demand (COD). If not properly treated, these pollutants can infiltrate groundwater and surface water, causing severe environmental and health risks. The objective of this study was to evaluate the efficacy (instead of effectiveness ) of Chrysopogon zizanioides (vetiver grass) in the phytoremediation of young landfill leachates, focusing on the removal of Cd, Pb, and the reduction of COD, while assessing post-treatment toxicity. The experimental setup involved growing Chrysopogon zizanioides in synthetic landfill leachates at concentrations of 25%, 50%, 75%, and 100%. The leachates were analyzed before and after treatment to quantify the removal efficiencies of heavy metals and COD. Additionally, the treated leachates were subjected to ecotoxicological tests using the nematode Caenorhabditis elegans to assess toxicity levels after phytoremediation. The results demonstrated that Chrysopogon zizanioides achieved maximum removal efficiencies of 98% (were achieved) for Cd and Pb at 75% leachate concentration while also significantly reducing COD levels​file-uanu6k1gueymnetdxsrbsg. However, plant growth was inhibited at 100% leachate concentration, and the removal efficiency decreased. Ecotoxicological assessments revealed that leachates treated at 75% concentration had minimal toxic effects, indicating effective detoxification. In this sense, Chrysopogon zizanioides proved to be an efficient and environmentally friendly solution for the removal of heavy metals from landfill leachates, particularly at moderate concentrations. However, further optimization is needed for highly concentrated leachates, where plant growth inhibition reduces treatment efficiency. Specifically, aspects such as nutrient supplementation or staged treatment might be necessary to improve performance at 100% leachate.