Identification and analysis of the relationship between Per- and polyfluoroalkyl substances and physicochemical parameters in the leachate of municipal solid waste landfill in Tehran

Extended abstract

Introduction: Per- and polyfluoroalkyl substances (PFAS) are prevalent in a multitude of products landfilling in waste disposal sites and leachate emanating from these sites serving as the principal vectors for the introduction of these compounds into the environment. These substances can enter ecosystems through food chains and accumulate in the liver and kidney tissues of humans and animals, causing thyroid diseases, lung dysfunction, and liver, kidney, bladder, and testicular cancers. Also, the accumulation of these substances in mammals impairs their immune system and their reproduction and growth. Due to the stable nature and bioaccumulation of perfluorooctanoic acid (PFOS) and its salts and perfluorooctanesulfonyl fluoride (PFOSF) in 2009, these substances were added to the list of stable organic substances (POPs) in the Stockholm Convention. An approach for detecting per- and polyfluoroalkyl substances involves elucidating the relationship between these compounds and various physicochemical parameters. Some studies have been conducted for investigation of these relationships across multiple disciplines, providing a foundation for the potential association between these parameters.
Materials and Methods: The case study was conducted at the Aradkouh municipal solid waste landfill located in the southern region of Tehran. Sampling was conducted on numerous occasions at the waste landfill. Samples were sent to an accredited laboratory for measurement of per- and polyfluoroalkyl substances and physicochemical parameters. To measure the amount of different per- and polyfluoroalkyl substances, liquid chromatography mass spectrometry (LC-MS-MS) was used in this research. The lowest reporting limit for the liquid samples in the present study was 0.5 μg/L. The R statistical software was employed to scrutinize the collected data, facilitating the assessment of the correlation between the concentrations of per- and polyfluoroalkyl substances and the respective physicochemical parameters. Pearson correlation analysis and linear regression were used to evaluate the correlation and relationship between the concentration of per- and polyfluoroalkyl substances (PFAS) and proxy parameters.
Results and Discussion: This is the first study to find the relationship between physicochemical parameters such as total suspended solids (TSS) and redox potential (ORP) with PFAS concentration in waste leachate. The findings revealed a pronounced correlation between the concentration of per- and polyfluoroalkyl substances (PFAS) and chloride. Equations that incorporated the parameters of chloride (0.95), and chemical oxygen demand (0.58) showed the highest R2 values in comparison to other equations; notably, the exclusion of these parameters from the regression equations resulted in a diminished R2 value. Consequently, there exists a significant correlation pertaining to the inclusion of these parameters within the multivariate equations. In general, regression models showed a correlation and potential relationship between PFAS and physicochemical parameters in this study. The robust correlation discerned between the concentration of per- and polyfluoroalkyl substances and physicochemical parameters may be attributable to factors such as the moisture content of the waste (organic waste), the composition of the waste (including paper and food packaging), and the decomposition of organic materials presented in the waste.
Conclusion: The results of this study have potential utility for the evaluation of per- and polyfluoroalkyl substances concentration through the application of physicochemical parameters in landfill leachate. While the identification of per- and polyfluoroalkyl substances in leachate underscores their persistence and environmental transformation, it simultaneously accentuates the necessity for the enhancement of waste management strategies, particularly those emphasizing source separation, within Iran. Effective management strategies are imperative to avert landfill sites from contributing to the release of these substances.