UP scientist issues urgent call for clean-up of toxic Krugersdorp mine dumps

Young children in Krugersdorp are breathing in uranium, arsenic and mercury fumes wafting over from abandoned legacy mines, while pollutants are seeping into the groundwater and nearby dams and lakes, cautions Dr Alseno Kagiso Mosai, a water remediation expert at the University of Pretoria’s (UP) Department of Chemistry.

“If this is not treated now, the effects of legacy mines will continue and the impact will be much more severe,” he says. “This means that the government will need large amounts of money to clean the water in order to bring it up to the standard needed for households.”

Dr Mosai says that while the mining companies responsible for the pollution are often nowhere to be seen, it is ultimately up to the government to fund acid mine drainage (AMD) clean-ups in order to protect the right of citizens to a healthy environment and clean water.

“Many AMD clean-up technologies do exist,” he adds. “Some are more or less expensive, while others are more or less effective, depending on the local context.”

To help authorities take urgent action in Krugersdorp and other parts of South Africa, Dr Mosai and fellow experts Dr Gebhu Ndlovu, of national mineral research organisation Mintek, and Professor Hlanganani Tutu, of the University of the Witwatersrand, authored a journal article in which they reviewed existing technologies, and recommended a combined approach that is both affordable and effective.

Communities at risk

“Krugersdorp is full of legacy mines, and most residents who live in the vicinity of the mine dumps have had serious health issues, such as asthma,” Dr Mosai says, noting that this is backed up by several research studies. 

“I’ve been there and I’ve seen it,” he adds. “It is not only kids – there are dams in this area that are used by older people for recreational activities like swimming, as well as religious activities like baptisms. We talk to them about the dangers, but they’re just doing these things innocently; it’s really sad for me and my colleagues to see.”

Dr Mosai explains that because the toxins can spread in both the air and in the water, even people who live some distance away from mine dumps may be affected. 

Call to action

The scientists are calling on authorities to make use of two technologies developed by South African researchers at Mintek: one precipitates unwanted toxins and the other uses microorganisms sourced from plant waste to “eat” heavy metal pollutants. The technologies are trademarked as SAVMINTM and CloSURETM respectively.

Dr Mosai explains that in the case of using microorganisms, there is the double benefit of recycling plant waste while saving costs on water treatment chemicals. Both technologies would also enable precious metals like cobalt, copper and nickel to be recovered for commercial use.

“It is therefore in the interest of municipal decision-makers, industry and other researchers to take note of the review article, so that South Africa doesn’t keep reinventing the wheel when it comes to researching new AMD clean-up technologies, and so that the benefits of mine remediation for governance, business and the safety of our children become clear,” he says.

On a positive note, Dr Mosai adds that UP experts like himself have been supporting remediation efforts by the national Department of Water and Sanitation, which has detected toxic mine elements in several areas. 

“If we don’t act now though, this issue is not going to go away,” he says.

Click on the gallery in the sidebar to see some of the effects of Acid Mine Drainage. 



Dr Alseno Mosai

July 4, 2024

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  • Dr Alseno Mosai

    Dr Alseno Mosai completed his undergraduate studies at the University of the Witwatersrand and joined the University of Pretoria (UP) as a lecturer and researcher in 2023.

    He has been evaluating the impact of mining and landfills on the environment, and formulating solutions to prevent further environmental pollution or damage. His work involves determining how pollutants are transported from mine and landfill sites to bodies of water, soil and air. Once this has been established, Dr Mosai investigates channels through which to protect natural resources such as the soil, surface water and groundwater from the impact of mining and landfills; this includes finding ways to create value from the waste that is produced.

    Dr Mosai explains that South Africa used to be major mining hub, and still is with regard to certain minerals. The mining and processing of precious elements led to the production of large amounts of solid and liquid waste that was released into the environment with no regulations in place.

    “As a result, natural resources were negatively affected, and the effects are felt today,” Dr Mosai says. “To make matters worse, mining companies, which are responsible for the pollution from decades ago, are nowhere to be found, or no one is taking responsibility. However, the waste must be taken care of, or else things will get worse. There is a large amount of waste that contains toxic elements such as arsenic, chromium, cadmium, mercury and uranium due to the legacy mines. These elements often end up in natural resources, including waterbodies. South Africa is a water-scarce country, and the available water resources must be protected. Landfills also contain toxic elements, which end up in the environment.”

    Dr Mosai is part of the environmental analytical chemistry research team, and is leading research into the following:

    • finding ways to treat mining waste, including mine dumps, acid mine drainage and high-density sludge;
    • developing and designing functionalised/modified adsorption materials for the selective recovery of valuable elements like the platinum group metals, rare earth metals, nickel and cobalt from mine waste;
    • developing adsorbents and methods/techniques for the removal of toxic and radioactive metals like chromium, cadmium, mercury, arsenic and uranium, as well as persistent organic pollutants from mining and industrial wastewater;
    • hydrogeochemical characterisation and modelling landfill leachates and mine dumps using various modelling techniques including speciation-solubility modelling, geochemical reaction modelling, reactive transport modelling, parameter estimation and chemometrics modelling; and
    • making use of machine learning/coding and computational modelling tools such as PHREEQC geochemical modelling (simulation and prediction), PHAST and parameter estimation (PEST) to simulate the transport of toxic pollutants from mine sites.

    A recent research milestone for Dr Mosai was finding a way to use hydrogeochemical modelling to simulate the migration of pollutants from mine sites and landfills.

    “The results are positive and show that computational modelling/programming can be used to simulate what is happening in the environment and to predict the future impact of mining on the environment if certain issues are not solved,” Dr Mosai explains.

    Dr Mosai says his PhD supervisor, Professor Hlanganani Tutu of the University of the Witwatersrand, is his academic role model.

    “He taught me a lot about research and how to be an expert, not only in environmental chemistry but in other fields like statistics, artificial intelligence, coding and hydrogeology.”

    Dr Mosai hopes to develop technology or a technique that is cheap and efficient for the removal of toxic waste from mining waste.

    “The technology should be suitable and attractive enough for the mining industry and governments around the world,” he says. “Many methods have been developed for the treatment of mining waste, but most of these are not suitable for large-scale application. I would like to close this gap. I would like the University of Pretoria to be the hub of consultation when it comes to mining waste treatment.”

    He says his research matters because it aims to come up with environmental solutions to what has been an issue for many years.

    “Many companies and governments are looking for affordable but efficient ways to remove toxic pollutants from waterbodies and soils. My research ensures that we make a breakthrough with affordable techniques and methods that are attractive to mining companies. Moreover, the research ensures that South Africa is on the map when it comes to environmental protection from mining waste.”

    To school learners or undergraduates who are interested in his field, Dr Mosai says that a lot is yet to be achieved in environmental analytical chemistry, and that the advancement of research comes about as a result of fresh ideas.

    “We should encourage the desire to protect our environment and our future by striving to prevent further damage to the environment caused by operating mines as well as closed and abandoned mines.”

    In his free time Dr Mosai enjoys reading, playing tennis, cooking, assisting people in need, and writing book chapters and articles.

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