Municipal Solid Waste Landfill Leachate Characteristics and Their Treatment Options in Tropical Countries

This review assesses the leachate quality from waste disposal sites in tropical climate zone. Through this review, data from 228 leachate samples from 145 waste disposal sites from 18 countries in the tropical region were analyzed. The 12 types of sites were considered for the analysis based on the climatic conditions, age, and the operating condition of the site. Tropical rainforest, tropical monsoon, and tropical savanna climates were identified for the climatic zone classification. Age of site was classified as young and old. The operating conditions were classified as engineered landfill and open dump site. Eighteen leachate quality parameters were included in the analysis. Leachate pollution index indicated that young sites from tropical rainforest zone and tropical monsoon zone have higher pollution potential, while the pollution potential in tropical savanna zone did not demonstrate considerable difference in pollution potential in terms of age of the landfill. Considering the operating method of the sites, open dumpsites pose higher pollution potential. Positive correlation could be seen among biological oxygen demand, chemical oxygen demand, total dissolved solids, and total Kjeldahl nitrogen. pH negatively correlated with organic pollutants as well as heavy metals. Analysis of emerging contaminants present in landfill leachate is limited in tropical region; thus, it is recommended to conduct studies on emerging contaminants. Further, the leachate treatment options considered in tropical region are discussed in this review.