Quality of leachate from the Oti Landfill Site and its effects on groundwater: a case history

Groundwater quality is an important factor used to determine the suitability of water for drinking, agricultural and domestic purposes. In this study, the effect of leachate from an open landfill site at the Oti community, Kumasi, Ghana, on the groundwater was investigated. A total of 42 water samples, 12 untreated leachate samples, and 6 treated leachate samples were analyzed for physicochemical and bacteriological parameters according to the Standard Methods for the Examination of Water and Wastewater. A comparison of leachate quality with respect to standard limits for wastewater shows that the concentrations of TDS, color, COD, BOD, turbidity, NH₃–N, and PO₄³⁻ were above the desirable limits. The concentrations of PO₄³⁻ and NH₃–N were found to be at considerable levels in the groundwater samples particularly closer to the waste disposal site and relatively reduced values away from the treatment site. The presence of bacteriological indicators in the groundwater samples indicates contamination from leachate sources. The multivariate analysis showed anthropogenic contaminants caused by leachates runoff and the use of chemical fertilizers. The Pearson correlation results showed a significant variation of TDS, NO₃–N, SO₄²⁻, EC, turbidity, and COD, indicating that high mobility of ions relies on the anthropogenic activities and mineral solubility. The water quality index showed more than 85% of the water samples have poor quality. Insight from this study may be useful to enhance the understanding of the distribution of physicochemical parameters in groundwater, as well as the management and uses of groundwater resources in the Oti community.