Characterization of leachate, groundwater quality analysis, and evaluation of hydrogeochemical processes at the Kpone engineered landfill site, Ghana

Leachate from landfills can contain high levels of dissolved organic matter, inorganic materials, and toxic elements which can deteriorate the quality of groundwater. A comprehensive study was conducted at the Kpone engineered landfill site to characterize the landfill leachate and assess its impact on the chemical quality of the groundwater in terms of its suitability for drinking and irrigation purposes. The hydrochemical data was also analyzed to identify and better understand the processes controlling the hydrochemistry of the groundwater. The landfill leachate was found to be partially stabilized and showed values exceeding the recommended limit for most of the analyzed physico-chemical parameters, indicating that it must be treated before it is released into the environment. The groundwater samples were classified as fresh and brackish on the basis of their electrical conductivity (EC) (818–2223 µS/cm) and total dissolved solids (TDS) (518–1384 mg/L). The levels of heavy metals including copper, lead, chromium, cadmium, and zinc in the groundwater were all below the detection limit. The groundwater was characterized mainly by Ca–Mg–Cl and Na–Cl facies, which are a reflection of geogenic and anthropogenic processes (such as silicate weathering, direct/indirect base exchange mechanisms and mixing of leachate with groundwater) taking place in the study area. Groundwater in wells closer to the landfill appeared to be affected by leachate infiltration from the landfill, making it unsuitable for drinking and irrigation purposes. This study highlights the need for continuous quality monitoring and protection of groundwater against further pollution by the landfill leachate.