Geospatial characterisation and determination of landfill sites impacts on groundwater resources in Buffalo City Metropolitan Municipality in the Eastern Cape, South Africa

Abstract

Globally, waste management challenges persist, especially in developing regions like South Africa where landfilling remains the key strategy for waste disposal. However, landfilling is a major concern because of the possible health and environmental impacts it poses. This research study examines the level of leachate contamination of adjacent water sources from the Roundhill and King William’s Town (KWT) landfills in the Buffalo City Metropolitan Municipality situated in the Eastern Cape Province, South Africa and the environmental implications of such landfill leachate on surface water and ground water near the two landfill sites. In addressing these aims, the physicochemical properties of leachate, surface water, and groundwater were assessed to identify potential contamination risks to water quality. Primary data gathering through water sample analysis and secondary data analysis from past monitoring reports were both considered in this study. Samples were collected during both dry and wet seasons and were tested for pH, electrical conductivity (EC), anions (chloride, nitrate, nitrite, sulphate, ammonia), and heavy metals (cadmium, chromium, arsenic, lead). The research also involved geospatial profiling to detect pollutant distribution patterns and correlations between the physicochemical properties of water. The results indicated a significant impairment of water quality in the vicinity of landfills. Nitrate concentrations in surface-water samples varied from 0 to 63.3 mg/L and reached maximum historical peak values at NR1 of 168–337 mg/L, which exceeded WHO and SANS limits of 50 mg/L. Nitrite levels generally ranged between 0 and 1.44 mg/L; however, experimental results revealed high nitrite values that further exceeded up to 6.89 mg/L at certain sites. There was a high variability in chloride concentrations, with the highest levels recorded in surface water (1 719.8 mg/L) that is well above the SANS guideline of 300 mg/L. Ammonia in the leachate from landfills was extremely high, with mean values of 614.3 ± 105.1 mg/L (Roundhill landfill) and 11.0 ± 51.4 mg/L (KWT landfill). The concentrations of ammonia were observed from 36.0 to 159.0 ± 207.8 mg/L in polluted water samples and from 10.5 to 23.1 m/L BPA with its contamination levels above WHO guidelines. Heavy metal analysis indicated that lead concentrations were highly elevated and leachate 94.2 μg/L (Roundhill), 56.7 μg/L (KWT) while surface water varies between 28.5-326. u g/L and reaches a groundwater concentration of 486;2 u g /L, well above WHO guide value of loug/1. Spatial profiling revealed that contamination from landfill leachate generally spreads from the landfill sites, with pollutants such as chloride, nitrite and ammonia showing negative concentration gradients as they moved further from the landfill site. It was concluded in this research that there are major problems related to leachate that require improved waste management practices and better landfill regulation compliance in the Buffalo City region.