Characterization of landfill leachate at the Karadiyana open dumpsite, Sri Lanka, and assessment of water pollution in its vicinity

Contamination of ground and surface waters by landfill leachate is a prime environmental concern. The present research assesses chemical composition of leachate generated in the Karadiyana open dumpsite in Sri Lanka and the groundwater pollution caused by the landfill. The leachate pollution index (LPI) of Karadiyana is 34.00, suggesting that it has the potential to contaminate the environment. The nitrate, ammonia, and total phosphate concentrations in leachate varied in the range of 20.70 to 167.80, 376.55 to 580.33 and 10.00 to 84.00 mg/L respectively. Four major groups, namely, tryptophan- and tyrosine-like protein fractions, and fulvic and humic fractions were identified in leachate using fluorescence data. The bio chemical oxygen demand (BOD) to chemical oxygen demand (COD) ratio of leachate in the present study varied between 0.39 and 0.49 which categorizes leachate into intermediate age with medium biodegradability. This observation was further verified by the average pH and COD values of leachate; 6.81 ± 0.08 and 2221 ± 45 mg/L, respectively. Only one out of ten dug wells located in a radius of about a kilometer from Karadiyana dumpsite can be classified as good water for drinking purposes though eight of ten are used for drinking at the moment. All ten dug wells exceeded the WHO recommended nitrate level.