Researchers from the University of the Witwatersrand have come up with a method to clean mining-polluted water.
The acid mine drainage (AMD) is the runoff of pollutants like sulfuric acid and heavy metals that secrete into waterways, affecting wildlife and rural mining communities. It is often found at gold and coal mines, which are plentiful in South Africa. The new method aims to not only clean the water but captures polluting metals that can then be re-purposed.
Tamlyn Naidu, a post-doctoral research with her fellow researchers came up with an ion exchange filtration system that uses countless polystyrene beads, each the size of a pinhead, which the water passes through.
Unlike a coffee filter, which physically blocks coffee grounds from passing through with water, the beads grab the contaminants in the water chemically. The passing water, which can be scaled up to clean 1,000 liters an hour, then comes out clear.
“What we wanted to do is minimize environmental impact for a lot of these communities that are afflicted by AMD. They have been born into mining communities, they work in mining communities, they’re either scared to report it or to complain about it, because this is their livelihood. Ultimately, from this project, we want community members to be involved in something that’s easy for them to operate, that they can extract value from and start, you know, seeing the value that companies have been taking onto the land and taken away from them. And yeah, I guess adding to their quality of life,” said Tamlyn Naidu.
“This project though, does something extra. It also wants to extract from the water valuable materials. So what has been identified in some of these streams, especially coal mining streams, is that the acid that’s produced from the mine waters actually dissolves out some rare earth metals,” says Ed Hardwick, the owner of Cwenga Technologies, which is a partner in the research.