Sarah Wild
NEW technology‚ developed at the University of the Witwatersrand in conjunction with a professor from the National Aeronautics and Space Administration (Nasa) in the US‚ could be used to clean acid mine water as well as in medical processes such as dialysis.
The research was published on Friday‚ which is also World Water Day and the start of South Africa’s National Water Week.
Acid mine water — which is contaminated water flowing from metal mines‚ such as gold mines — causes ecological harm and compromises human and animal health. Last year‚ the Mpumalanga town of Carolina lost its municipal water supply when acid mine water polluted its dam.
In 2009‚ the auditor-general estimated the bill for cleaning up existing abandoned mines would top R30bn. Acid mine drainage is often found at derelict mines in South Africa because pumping and water treatment cease when the mine closes. According to the Department of Mineral Resources‚ there are 5‚858 derelict and ownerless mines in the country.
"The technology … will make it easier to filter pure water from waste produced during mining‚ oil and gas exploration and production‚ and nuclear production‚” Wits University said on Friday.
The research was headed by Sunny Iyuke‚ head of the Wits School of Chemical and Metallurgical Engineering‚ and two doctoral students who were co-supervised by a professor at Nasa.
"It is a nanocomposite membrane‚” Prof Iyuke said on Friday‚ noting that the membrane was made out of carbon nanotubes.
Nanotechnology involves managing and manipulating matter on an atomic level and deals with structures between one and 100 nanometres. A nanometre is one-billionth of a metre.
"We allow the water to go through the membrane (which is like a very thin sheet of paper) on the one side‚ rejecting oil and every other contaminant‚” Prof Iyuke said.
Bhekie Mamba‚ head of the Nanomaterials Science Research Group at the University of Johannesburg‚ told Business Day last year that a problem with nanomembranes for water purification — something on which he was also working — was that the membranes became clogged with impurities and had to be cleaned or replaced.
Prof Iyuke said this was not a problem with the new membrane because of the materials used that "sucked” through the membrane.
There are a number of technologies being developed to treat acid mine water in South Africa‚ such as freezing the water‚ heating it and chemically processing it.
When asked how this technology was different‚ Prof Iyuke said: "A membrane is quite easy — you get hold of the polluted water‚ pass it through the membrane module and then get the water.… (Other processes) are more expensive.”
However‚ he was unable to estimate the cost of the membranes‚ saying research was under way to scale up the project.
He also said he would not patent the technology‚ preferring to go straight to the commercialisation phase. "Once people get the concept‚ they’ll quickly use it. It is easier to commercialise it‚” he said. © BDlive 2013
