Mining is one of South Africa’s key drivers for economic growth and employment, yet the sector has also had a serious toll on the environment. Mining’s impact on water, particularly acid mine drainage, is one that the sector must contend with.

Raquel Nosie Mazwi, director of mine and industrial water quality regulation, Department of Water and Sanitation (DWS), says,

“Mpumalanga, Gauteng, Kwa-Zulu Natal, and Limpopo in particular are plagued by mine-impacted water pollution.”

Mpumalanga faces mine water problems due to abandoned mines and decaying controls meant to manage mine-impacted water. Gauteng’s geographical make-up contains elevated levels of pyrite associated with gold mining, which are known to pollute water. Kwa-Zulu Natal has many abandoned coal mines that have filled up with water. Limpopo, especially the Lephalale area, hosts active coal mines and produces water with high sodium levels. Mines in Limpopo impact the Olifants catchment.

Mazwi says, “Mining is regulated by the Department of Mineral Resources (DMR), but the impact of mining concerns the Department of Forestry and Fisheries (DFFE) as well as DWS. We at the DWS have a particular interest in mine water management, mines use massive quantities of water and threaten ground water and other supply sources when not managed properly.”

Mazwi explains that as South Africa focuses on sustainability, the issue of mine water becomes important in the context of ensuring environmental safety and circular economic practices. This necessitates a strong regulatory framework that encompasses the changing landscape of environmental law in South Africa.

Environmental regulatory framework

Mazwi highlights several sections of the constitution that are important when discussing mine water.

Section 24: Environment

Everyone has the right to an environment that is not harmful to their health or well-being, and to have the environment protected, for the benefit of present and future generations, through reasonable legislative and other measures that:

• Prevent pollution and ecological degradation;
• Promote conservation, and
• Secure ecologically sustainable development and use of natural resources while
• Promoting justifiable economic and social development.

Section 40

This section clearly defines the roles of government on a national, provincial, and local level and indicates that they are independent yet interrelated.

Section 27

This deals with health and says that everyone has the right to health care, food, and, importantly, water.

There are also several acts that govern South Africa’s water and are important in the context of mine-impacted water:

• National Water Act No 36 of 1998
• Hazardous Substances Act No. 15 of 1989
• Mineral and Petroleum Resources Development Act, No 28 of 2002 (MPRDA)
• National Environmental Management Act No 107 of 1998 (NEMA)
• National Environmental Management: Air Quality Act No.39 of 2004 (NEM: AQA)
• National Environmental Management: Biodiversity Act No 10 of 2004 (NEM:BA)
• National Environmental Management: Protection Areas Act No 57 of 2003 (NEM:PA)
• National Environmental Management: Waste Act No 59 of 2008 (NEM: WA).

Mazwi explains, “This regulatory framework guides the water management principles of South Africa. The national government is the custodian of water resources. The development, management and use of water is carried out in the interest of the public, which means there should be equity and quality among water users. All people have the right to potable water and sanitation.”

Mines must register for a water use license and therefore comply with all regulatory and legal requirements. It is also the responsibility of the mines to conform to local by-laws and self-regulation and must collect evidence to support their compliance.

How DWS enables the circular economy of mine-impacted water

The water pollution from mining contains heavy metals, chemicals, and acid and is not suitable for human consumption and agriculture. However, this does not need to be the case as Mazwi says, “If we manage this wastewater in a sustainable way by treating it, this water can be put back into use. It can be used for irrigation, industrial processes, and in some cases, domestic use after further treatment. Dewatering mines offers another way to use this water with less impact on the environment.”

DWS is already considering, and in some cases, actioning these processes. Part of this movement towards circularity is the mine water management policy document for 2022. This document sets the scope and policy of dealing with mine water, Mazwi adds, “this is guided by existing frameworks and works in conjunction with other legislation like the National Water Act and the constitution.”

This document specifically tackles mine closure, liabilities, and the use of technology for treating mine water, including acid mine drainage. This document also works in tandem with the regulation GN 704 of the National Water Act, which:

• Addresses impacts from mines and associated activities on the water resources
• Ensures that systems are in place at all mines to enable effective management of the impacts of mining on the water resources
• Ensures consistent and sustainable implementation of the water management hierarchy at all mining facilities that have the potential to impact the water resources over the full life cycle of the mine
• To give effect to the BPG and Mine Water Policy
• Encourage Re-use and desalination of mine-impacted water
• Enable piloting of research projects and technologies

Projects in place

Coaltech, a non-profit organisation that addresses the research needs of the South African coal industry, are using mine-impacted water for irrigation as part of the mine closure process.

Avhurengwi Nengovhela, CEO of Coaltech, says, “The research done by Coaltech is being used to treat mine water for irrigation of natrophile grass species, as well as establishing carbon farming models for rehabilitated land, carbon capture and footprint reduction through the post-closure process, as well as using Phyto mining, a process that uses plants to extract metals from the soil.”

They are also working with the Water Research Commission on reusing mine water in agriculture and green hydrogen production.

In the Witwatersrand area, the eastern, western, and central basins are all being tested to treat and reuse mine water.

Western basin

The Trans-Caledon Tunnel Authority (TCTA) refurbished an existing plant operated by Sibanye Stillwater. The treatment increases the pH and reduces heavy metals such as iron. The plant currently treats 35 Ml /d, which is released into Tweelopiesspruit. The current obstacles are high rainfall, illegal miners removing plugs, and not enough capacity. This plant has not been able to lower the water level in the mine void to an environmentally acceptable level.

Central basin

The plant in the central basin treats water using hydraulic dewatered stacking (HDS). This process involves dewatering the mine water and then stacking it for storage. This has been operational since 2014 and is managed by Nafasi Water. It treats 84 Ml/d at maximum operation but normally treats 72 ML/d. This is discharged into the Elsburgspruit. Currently, the discharge line has reduced capacity due to scaling. This plant has operated below its capacity, resulting in a rise in the water level of mine void.

Eastern basin

This treatment plant uses HDS and treats 108 Ml d at maximum operation and currently does 94 Ml /d. This plant has been in operation since 2016 and is managed by Nafasi Water. The treated water is released into the Blesbokspruit, and the sludge is deposited back into the mine shaft. Frequent equipment failures have meant that this plant has operated much lower than its long-term capacity.

There is groundwater contamination at all sites, and the water quality must continually be monitored. The DMRE has a project using ingress control to reduce water migration into the mine voids to minimise acid mine drainage.

New tech on the block

The private sector may hold some solutions for the government in terms of treating mine water and making a sizable positive impact on the environment. José Gomes, head of corporate development at Dornier Group, says,

“Water scarcity means we need to make use of all the water we have at our disposal, and mine water represents an opportunity to use the water that would otherwise remain contaminated.”

Dornier utilises freezing to extract fresh water from salt water in their desalination process, a task that is cheaper than reverse osmosis.

“Freezing water can also be used to crystallise minerals,” says Gomes. In their desalination process, the freezing begins at -2 degrees Celsius, which crystallizes fresh water from salt water and once frozen, floats and can be removed.

Mazwi adds, “Ideas from the private sector can be useful for government, and the growing use of public-private partnerships will certainly pave the way forward for us. Mazwi continues, “South African environmental legislation can help solve South Africa’s water quality challenges. There is a need to explore technologies and use the data from existing projects to better the efforts in fighting against mine water contamination.”