JOHANNESBURG (miningweekly.com) – Decanting acid mine drainage should be seen as an opportunity in the water-stressed Gauteng region, Professor Frank Winde from the North-West University said on Thursday.

Speaking at the yearly Sustainability Week in Johannesburg, Winde, who headed a research study into acid mine drainage (AMD) in 2011, said a range of opportunities had to be explored for the possible use of decanting mine water.

“Untreated acidic mine water has been used in the past by municipal sewage works in the Central Rand to aid nitrate digestion. Given the number of sewage works in Johannesburg and the volume of sewage to be treated, this alone could perhaps accommodate most, if not all, of the decanting water, resulting in no treatment costs while saving clean water otherwise used for this purpose.

“This is but one example from a range of other possibilities that should be explored,” he said.

Winde also reiterated that the mining industry and government had more time to find a solution for AMD in the Central basin than what has been reported over the past few years.

Citing his 2011 report, which downplayed the risk of AMD flooding in Johannesburg’s central business district, he said that there was a significantly slower rise of the underground mine-water table, a significantly lower volume of decant and a far less severe impact of untreated decant water on the quality of receiving streams than previously reported.

The research study called for a sustainable, low-cost, low-energy solution to the problem, rather than the proposed high-cost, high-energy, pump-and-treatment-option likely to be subsidised by society.

Mining companies argue that the responsibility of dealing with AMD, which is viewed as a mining legacy issue and an ownerless liability, should not be laid solely at the feet of mining companies.

Chamber of Mines head of environment Stephina Mudau said that ownerless and derelict mine sites were the sole responsibility of the State, which should manage the environmental impacts caused during historic mining operations and the effects thereof.

She pointed out that legislation, such as the Mineral and Petroleum Resources Development Act along with the National Environmental Management Act kept operational mines from repeating the mistakes from the past.

“There is also opportunity for partnership and cooperation in dealing with the legacies of acid mine drainage,” Mudau said.

AMD has already been decanting in the Western basin since 2002.