JOHANNESBURG (miningweekly.com) – The acid mine drainage (AMD) challenge in South Africa has been partially addressed, but a lot still needs to be done, Federation for a Sustainable Environment CEO Mariette Liefferink said on Wednesday.
Speaking to Mining Weekly Online on the sidelines of an integrated water management symposium, hosted by the DWS, in Centurion, she noted that government has recognised the threat AMD poses to the environment.
However, current treatment is incomplete, she said. “The water that is released from Gauteng’s Central and Eastern basins – up to 200-million litres a day – is highly saline, containing sulphate levels of about 2000 mg/l,” Liefferink noted, adding that the treated water had to be diluted to make it fit for use.
She noted that, within the eastern basin, some 110-million litres of AMD is being treated by means of neutralisation. “That water, which contains high levels of high levels of sulphate or highly saline water, is discharged into the Vaal river.”
Liefferink explained that during the neutralisation process, lime is added, which increases the pH level of the water.
As the water becomes more alkaline, a broad range of metals, including uranium, changes to solid metal sludge and gets dispersed into boreholes within the Eastern basin.
“There have been no environmental-impact assessments of the impact of those metals on groundwater or on downstream water uses.”
The impact of salinity on downstream water users, as well as the water security of the Vaal river, has also not been assessed, she said.
“Government needs to engage in public consultation both with the mining industry and with downstream water users. There are innovative technologies that can be implemented to mitigate the impact of AMD,” Liefferink said.