Occurrence and transport of per- and polyfluoroalkyl substances (PFAS) in the leachate of a municipal solid waste landfill in Tehran, Iran (a Middle-Eastern megacity).

Per- and polyfluoroalkyl substances (PFAS) are present in a variety of products that are disposed in landfills as waste and end up in landfill leachate which cause severe problems. The primary aim of this study was to detect PFAS in generated leachate in different sections of a process and disposal complex (called Aradkuh) located in Tehran, Iran. Due to techno economic limitations of measuring PFAS in Iran and easiness of measuring physicochemical parameters to determine PFAS concentration as well as better understanding of the mechanisms of these substances releases from landfills, this research aimed to evaluate the potential relationship between these parameters in landfill leachate. The results indicate the presence of higher PFAS in the aged leachate compared to the fresh one and 6 PFAS out of 34 were detected which perfluorohexane acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorobutanesulfonic acid (PFBS), and 6:2 fluorotriomersulfonate (6:2 FTS) were respectively the predominant compounds. PFAS was identified in all sections in the Aradkuh (except waste transportation vehicles' tank and compost site) and evaporation lagoons had the highest concentration level among the other sections for PFAS (20.2 μg/L). Significant correlations were found between PFAS levels and different physicochemical parameters such as chloride (R=0.95), electrical conductivity (EC) (R=0.88), oil and grease (R=0.87), and chemical oxygen demand (COD) (R=0.58). PFAS detection in landfill leachate highlights their environmental persistence and transformation and it also emphasizes the necessity for enhanced waste management strategies (focusing on source separation) in Iran.