The impact of the leachate from the Botshabelo non-engineered landfill on groundwater, surface water and soil quality

Abstract

Introduction: Many countries around the world, including South Africa, faced significant challenges in managing urban solid waste. As such, the dumping of waste has been a constant phenomenon in the landfill sites that has impacted the environment. This has resulted in a decline in groundwater, surface water, and soil quality resources that are necessary for South Africa’s overall development. Aim: This study sought to explore the effects of leachate from the Botshabelo non-engineered landfill on groundwater, surface water, and soil quality. Methodology: Four groundwater, two soil and surface water, and one leachate samples were gathered for sampling in wet and dry seasons. The samples were examined for physicochemical characteristics and contrasted with domestic and global norms. The use Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and in-situ pH analyses were conducted for water samples, Wavelength Diffraction X-Ray Flourescence (WDXRF) and X-Ray Diffraction (XRD) for soil samples. Microsoft Excel was used for statistics, and Grapher Software for geochemical evolution of the water. The complicated data were simplified using both water quality indices and soil pollution indices which gave numerical representation of the qualities with subsequent classifications as well as parameters that posed contamination. Groundwater vulnerability was conducted to outline boreholes that were most susceptible to pollution around the landfill site and was plotted using the Geographical Information System (GIS) software. Results and discussion: The leachate was highly contaminated with Na, Cl, alkalinity, and total hardness. The mean EC for groundwater surpassed the DWAF standard and it was classified as hard. Only Mg surpassed the WHO and SANS limits. Surface water showed little to no pollution in all seasons and was moderately hard. The geochemistry of water samples revealed CaMgHCO3 and CaMgCl, dominant cation, and magnesium types of water. The water−rock interaction and carbonate weathering influenced the water chemistry in the landfill site. Acidic soil polluted with vanadium and chromium was discovered. Acording to pollution indices Mg, manganese, and uranium as contaminant sources in groundwater in all seasons. Surface water had only manganese. Groundwater was between poor and unsuitable except for surface water. Furthermore, contamination by vanadium, arsenic, copper, and chromium was found in soil, deeming it as severely contaminated. Groundwater vulnerability methods depicted very low and moderate vulnerabilities across the boreholes. Conclusion: The study found that the Botshabelo non-engineered landfill site had minor impact on water quality due to slightly higher contamination of certain parameters, while the soil was heavily impacted. Therefore, frequent monitoring of water and soil quality at the landfill site, with the installation of leachate collection systems, bottom liners, borehole drilling, and covering of opened boreholes are recommended. These will ensure monitoring, protection, and generation of more data.