Abstract
Ensuring safe drinking water is essential for public health and sustainability, particularly in regions with significant anthropogenic activities. This study aimed to assess the water quality of various water sources in the Steve Tshwete Local Municipality (STLM), Mpumalanga, South Africa, by analysing key water quality parameters over 5 years (2019–2023). The parameters assessed include pH, turbidity, electrical conductivity, total dissolved solids, fluoride, iron, nitrate, sulphate, manganese, alkalinity, suspended solids, ammonia, nitrate/nitrite, phosphate, and faecal coliform bacteria (FCB). Water samples were collected from boreholes, raw water treatment plants (WTP), final treated water, and wastewater treatment plants (WWTP) located within the municipality. The data evaluation was performed using the DyWaBM, a model that can be used for historical and predictive analysis of various water bodies.
In the study, it was found that most water quality parameters, such as pH (5-9.7) and TDS (0-1200mg/L), met the standards set by the South African National Standards (SANS 241:2015). However, certain parameters, including turbidity whereby the raw water treatment plant results are 5.28, 3.86, 6.56 and 5.49; the final water turbidity values are 1.32, 3.92, 1.15 and 3.32 these values are above the SANS 241:2015 limit of (0-1 NTU), fluoride, iron, manganese, ammonia, phosphate, and FCB, consistently exceeded the recommended limits. Elevated fluoride concentrations were found primarily in the boreholes at Bankfontein, with concentrations ranging between 2.5 and 3.5 mg/L exceeding the safe limits of 0-1.5 mg/L due to environmental contamination from mining, agricultural runoff, and coal combustion. High iron levels were observed in both raw and treated water, primarily attributed to abandoned mine shafts that leak into the local water systems. This study does not advocate changes to the SANS 241:2015 standard, but rather the importance of compliance. The DyWaBM can be used as an early warning tool for identifying trends in parameter exceedances, enabling proactive interventions.
The SANS 241:2015 limit for iron levels is 2000 ug/L or 2 mg/L. the concentrations measured at boreholes, they are 15.20 mg/L, 26.17 mg/L, 24.83 mg/L, and 7.94 mg/L. The raw water treatment plant results are 52.55 mg/L, 33.18 mg/L, 40.30 mg/L and 46.16 mg/L; the final water iron levels are 44.71 mg/L, 22.50 mg/L, 16.85 mg/L and 23.11 mg/L. The elevated ammonia SANS limit is 1.5 mg/L. The average measured values for downstream
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are 5.12 mg/L, 22.45 mg/L, 11.50 mg/L, 9.65 mg/L and upstream 0.96 mg/L, 6.74 mg/L, 8.80 mg/L, 1.93 mg/L and phosphate levels the SANS 241: 2015 limit is 0.025 mg/L, respectively. The measured values for downstream are 1.77 mg/L, 6.0 mg/L, 3.96 mg/L, 4.69 mg/L and upstream 0.43 mg/L, 2.49 mg/L,1.81 mg/L, 1.14 mg/were linked to agricultural runoff, with the rainy season exacerbating the contamination.
Manganese concentrations in both raw and treated water consistently exceeded the SANS 241:2015 limit of raw water treatment plant results of 58.97 mg/L, 34.95 mg/L, 65.39 mg/L and 33.17 mg/L. The final water treatment results of 50.42 mg/L, 22.50 mg/L, 16.85 mg/L, and 23.11 mg/L, highlighting inefficiencies in the treatment processes, particularly in the oxidation and precipitation of metal ions. In this study, it was identified that inadequate wastewater treatment processes were a significant source of microbial contamination, with faecal coliform bacteria levels far exceeding acceptable limits of 130 counts per 100ml, as the wastewater downstream FCB levels are 1695.92 mg/L, 1521 mg/L, 1498.20 mg/L and 1416.63 mg/L, the upstream results are 1275 mg/L, 996.8 mg/L, 1186.2 mg/L and 958.8 mg/L. The findings indicate that although treatment processes, such as flocculation and filtration, are in place, they are not fully effective in addressing all contaminants, particularly in the presence of complex pollutants like manganese, iron, and microbial pathogens.
This study underscores the need for improved water treatment infrastructure and management strategies to mitigate the impacts of mining activities, agricultural runoff, and wastewater contamination. The results suggest that targeted interventions, such as enhanced filtration systems, defluorination processes, and better management of wastewater discharge, are essential for ensuring the delivery of safe, potable water to the residents of STLM. Furthermore, the study highlighted the importance of ongoing monitoring and adaptive management strategies to address emerging water quality issues in the region.
Keywords: Anthropogenic activities; Dynamic Water Balance Model (DyWaBM); SANS 241:2015 Standards; Steve Tshwete Local Municipality (STLM); Water Quality Index (WQI); Water security