Variability of leachate quality and polluting potentials in light of leachate pollution index (LPI) - A global...

From a holistic perspective, this review is the first to comprehensively assess and characterise leachate quality from waste disposal facilities (WDFs), landfills and dumpsites, located in 61 countries worldwide. A continent wise grouping approach was adopted to identify the variability of leachate quality and polluting abilities in light of leachate pollution index (LPI). The literature data on leachate quality included 428 samples, with eighteen leachate parameters, classified under, organic, inorganic, and heavy metals. Statistically significant differences in LPI were found between different continents and WDFs demographic data, i.e., type, status, age, rainfall, etc. A negative correlation was found between pH and the majority of studied parameters, especially for heavy metals such as Pb, Zn, As, Hg, Cy, as the decrease in pH intensifies heavy metals' solubility. Based on the studied worldwide leachate data and WDFs age, an LPI rating was identified, where high, intermediate, and low contaminated leachate are typically classified with having an average of 26.5, 23.6 and 17.5, respectively. The provided database in this review could be of great importance in establishing a more comprehensive global databank by including other countries- and site-specific factors that are vital in enhancing the accuracy of LPI and formatting a more representative leachate diagnosis index.