In-Situ Groundwater Bioremediation

The Challenge

A major smelter in the North West Province faced significant legacy groundwater contamination from decades of smelting operations. Elevated concentrations of carcinogenic hexavalent chromium (Cr⁶⁺ up to 4.73 mg/ℓ), nitrate (NO₃^– up to 43.7 mg/ℓ as N), and sulphate (SO₄^2- exceeding 1,300 mg/ℓ) were detected across the site’s borehole network. The complex fractured aquifer system and multiple contamination sources required an innovative, cost-effective approach beyond conventional pump-and-treat methods.

Our Approach

iWater deployed a phased in-situ bioremediation programme using electron donor infiltration to stimulate indigenous microbial communities. The strategy evolved from proof-of-concept to a comprehensive bio-barrier designed to intercept and treat the contaminated groundwater plume.

• EC profiling to identify fracture zones
• Slow-release electron donor calibrated to site-specific groundwater chemistry and contaminant loading
• Strategic bio-barrier positioning perpendicular to groundwater flow to intercept contaminated plume migration
• Four-round monitoring program (baseline, 1-month, 3-month, 6-month) with SANAS-accredited laboratory analysis

The Results

Consistent contaminant reduction to below accredited laboratory detection limits was achieved across all treatment campaigns, confirming the technology’s effectiveness and repeatability.