CHARACTERIZATION OF DUMPSITE LEACHATE: A CASE STUDY OF OSOGBO, OSUN STATE

ABSTRACT This study investigates the characterization of leachate from four major dumpsites in Osun State: Osun Waste Management Board, Oleyo, Akilapa, and Onibu Eja. The aim of this research was to analyze the physicochemical properties of dumpsite leachate and compare the results with standards set by the World Health Organization (WHO, 2017) and the Nigerian Environmental Standards and Regulations Enforcement Agency (NESREA, 2011). Standard laboratory procedures were employed to determine key parameters such as pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Alkalinity, Dissolved Oxygen (DO), Turbidity, Colour, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and heavy metals including Lead (Pb), Zinc (Zn), Iron (Fe), and Copper (Cu). The obtained results were analyzed and compared with WHO and NESREA permissible limits to evaluate contamination levels. The findings revealed that most parameters exceeded safe limits, indicating significant leachate pollution. Total Alkalinity ranged between 205–500 ppm, while DO values (2.8–4.1 ppm) indicated organic pollution. Heavy metals such as Lead (1.98–2.89 ppm) and Copper (4.28–6.91 ppm) were also above acceptable limits, confirming potential environmental and health hazards. It is recommended that proper leachate treatment systems be established at each dumpsite. Sanitary landfill practices should replace open dumping, and regular environmental monitoring should be enforced. Public education on waste segregation and recycling should also be promoted to reduce leachate generation and protect groundwater quality in Osun State.