Assessment of the impact of landfill leachate on surface and ground water sources; a case study of Kiteezi landfill, Wakiso.

Abstract

The influence of leachate from Kiteezi landfill (Kampala, Uganda) was investigated to quantify the variations of water quality during November 2021 to January 2022. Leachate and water Samples were collected from different sites around the landfill. Water sampling sites were established upstream and downstream. The effect of distance on the concentration of pollutants in the leachate discharge stream with respect to potential pollutant sources was investigated. Samples were analyzed for various Physical parameters; (turbidity, solids, EC, colour), Chemical parameters; (pH, nitrates, TN, TP, iron), Biochemical parameters; (BOD, COD), Microbial parameters; (E-coli, total coliform) and heavy metals (Mn, Cu, Zn, Pb, Cd, Cr). The result showed that the concentration of all parameters in the leachate will reduce as it flows downstream if not mixed with secondary sources of pollution as observed at SWP2. The secondary sources of pollution i.e. the community and the industries have significant effects on the concentration of BOD, EC TDS, TSS and turbidity at the different points of observation. These discharges increase the values of COD, BOD5, TDS, TSS, EC, and Turbidity between SWP2 and SWP4 by 10.1%, 17.9%, 39.3%, 16.5%, 27.1% and 34.1% respectively. The results of various parameters determined strongly suggested that Kiteezi landfill leachate had severe deleterious impact on the surface water though the walufumbe stream and would impose serious risks to the ecosystem downstream. The parameters including (turbidity, solids, EC, colour), Chemical parameters; (pH, nitrates, TN, TP, iron), Biochemical parameters; (BOD5, COD), Microbial parameters; (E coli, total coliform) exceeded the allowable limits of WHO, East African Community and National Environmental Quality Standards for Uganda. Heavy metals in the leachate were found in concentrations below the effluent discharge standard. The parameters such as nitrates showed no relationship with the quality of leachate, this implies that as leachate may be a threat to groundwater around Kiteezi landfill, there is significant pollution from the community on groundwater. The existence of numerous pit latrines and animal waste deposits have been found to have contributions in the pollution of groundwater. Analysis also showed that leachate, though in minimal quantities have more impacts on the shallower downstream sources closer to the landfill than the deeper sources, far from and in the upstream direction of the landfill, Water Integrated, multi-sector approaches are required to deal with the contamination problem and sustainable management of the Kiteezi landfill leachate to reduce the threat it possesses on the ecosystem downstream.