Variability of leachate characteristics and pollution potential in Asian disposal sites

Landfilling is a common method for disposing of municipal solid waste, but it generates landfill leachate, a significant environmental concern due to its potential ecotoxicity. Effective treatment of landfill leachate is essential to minimize environmental pollution. This study analysed 421 leachate samples from 257 disposal sites across 27 countries in Asia, examining the concentration and pollution potential of leachate pollutants in relation to site characteristics such as age, type, operational status, climatic conditions, mean annual temperature, and precipitation. The revised leachate pollution index (r-LPI) was used to quantify pollution potential, and statistical analyses were conducted to determine the influence of these factors on pollutant concentrations. The results indicated that the age of disposal sites is a significant factor, with older sites showing reduced concentrations of organic pollutants and heavy metals, while inorganic pollutant levels remained stable. Climatic conditions also significantly impacted leachate characteristics; arid regions produced more concentrated leachate with higher r-LPI values, while regions with higher rainfall produced more diluted leachate with lower r-LPI values. This study also gives the recommendation of treating leachate aiming to inform policy and regulatory frameworks for sustainable landfill management, contributing to the protection of environmental and public health.