Characterizing Seasonal Variation in Landfill Leachate Using Leachate Pollution Index (LPI) at Nam Son Solid Waste Landfill in Hanoi, Vietnam

The improper treatment of landfill leachates is one of the major problems associated with waste landfilling and causes serious environmental pollution at waste landfill sites and their surroundings. To develop a suitable landfill leachate treatment system and to minimize the risk of environmental pollution, it is important to characterize seasonal and temporal variations of landfill leachates. This study investigated the leachate quality of the Nam Son waste landfill in Hanoi, Vietnam in 2017–2019 and characterized the potential risks of landfill leachate using a leachate pollution index (LPI). The results of this study showed that the seasonal and temporal variation of the overall LPI during the monitoring period was small and in the range of 20–25 (values 2.5 times higher than the maximum permissible limits of Vietnam National Technical Regulation on Industrial Wastewater). The LPI sub-indices attributed to organic and inorganic pollutants were major components of the LPI. Especially, the annually averaged values of LPI of inorganic pollutants were 7.7 times higher than the maximum permissible limits, suggesting that the treatment of inorganic pollutants, such as ammonium-nitrogen (NH4+–N) and total nitrogen (TN), is highly required at Nam Son landfill to prevent environmental pollution surrounding the landfill site.