Recycling will address acid mine drainage

Reverse osmosis plants will be used to 'clean' contaminated water, reduce reliance on potable water and address environmental concerns

- Sheree Bega

The government plans to install reverse osmosis units to treat toxic acid mine drainage (AMD) to optimise the use of water and to help alleviate water stress in Gauteng.

The department of water and sanitation has applied to the forestry, fisheries and the environment department to update its environmental management programme report for the Eastern and Central basins on the Witwatersrand.

The amendment entails the installation of a million-litre-a-day reverse osmosis plant at both basins as part of its immediate and short term interventions to treat acid mine drainage. AMD is harmful to humans, plants and animals because it is acidic and it carries heavy metals, atoms that emit radiation and salts in hazardous concentrations.

The mining waste is the toxic legacy of more than a century of gold mining on the Witwatersrand. During underground operations, water was pumped to the surface to enable the mining to take place. As mining stopped, the pumping of underground water ceased and the mine voids started filling with water.

The sulphide minerals in the rocks were exposed to water and oxygen, which resulted in the formation of acid mine drainage.

The voids were progressively filled with acidic water.