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Reclaiming underground mine water to Blue Drop certified potable standards with high recovery plant.

Proxa reclaims underground mine water


The client, located in the heavy industrialised coal fields of South Africa, produces excess water as a result of their underground mining operations. This excess water is treated to potable standards and is supplied to the local municipality. The challenge is to achieve and maintain Blue Drop status (a South African certification programme that propels the country’s drinking water to excellence), which places stringent requirements on the compliance to drinking water standards and the management and operations of such water treatment facilities.


PROXA provided specialist start-up, commissioning, operation and maintenance of a 15 MLD mine water treatment plant. The plant met the stringent specifications required to achieve Blue Drop status at a recovery rate above 96%.


With world-leading expertise in design and treatment of heavily contaminated mine water – combined with proven expertise in the operations, maintenance and management of assets associated with advanced water treatment technology across 200 operations – PROXA is able to consistently meet its treatment regulatory and certification requirements. What’s more, our technology support team extracts on-going operational savings and passes these on to the potable water’s end-user.


The treatment process achieves a very high recovery rate, above 96%, of potable water to minimise brine and the corresponding pressure placed on storage ponds. One stage of the 3-stage process consists of the following:

  • Clarification and filtration of the feed to reduce suspended solids and heavy metals
  • Solids polishing with ultrafiltration
  • Desalination by Reverse Osmosis
  • Conditioning of recycled reject using lime
    for the 2nd and 3rd stage treatments
  • Final neutralisation with lime and disinfection
  • Softening of the Reverse Osmosis reject stream through slaked lime
  • Solid separation in dedicated clarifiers/ thickeners followed by hydrocyclones
  • Belt filtration to remove excess water in sludge
  • Handling and disposal of waste sludge, mainly containing metals hydroxides and gypsum


The product water is Blue Drop certified which requires compliance to South African drinking water standards above 99%.


The Blue Drop certification ensures that the client is able to continuously produce safe drinking water to the local municipality in a sustainable and responsible manner, which is critical in waterscarce countries where drought conditions are prevalent.

Client: A member of the coal mining industry

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