Sludge cleanup plant to ease water crisis
● South Africa’s first landfill effluent and leachate treatment plant, capable of turning millions of litres of liquid waste into relatively clean water, started up this week in a groundbreaking move towards environmental stewardship.
The R100m state-of-the-art facility in Delmas, Mpumalanga, is run by 10 people ranging from chemical engineers, analytical chemists and lab technicians through to managers and maintenance and cleaning staff.
The plant is the result of a partnership between waste management company Interwaste and French environment group Séché. Leachate is water that has percolated through a solid and leached out some of the constituents.
Managed by Moipone Maseko and Antoine Deffay of Séché, it is set to process 43million litres of liquid waste a year, transforming it into 39-million litres of water suitable for industrial use.
“The liquid waste is basically leachate from our leachate dam on the property, which is filled by the murky fluid that drains out from landfill and dump sites,” said Interwaste marketing director Kate Stubbs. “And then there’s also effluent, which is the industrial waste that’s trucked in from factories — basically anything that cannot be legally dumped because it is 40% or more liquidbased. So something like sludge or old yoghurt,” she said.
Speaking at the launch, Maseko said the project was the result of two years of hard work and construction. “We worked in collaboration with the French team but the majority of the equipment is locally sourced,” she said.
“We had identified a gap in leachate management in South Africa, and the need for circular economy solutions and contributions of clean water. We have that technology in Europe but it doesn’t simply work in Africa, so just buying a plant from overseas and setting it up here in a kind of plug-andplay situation wasn’t an option,” said Deffay, leader of the French contingent.
“It all started with a vision for South Africa. So we pulled in international resources, developed a design, came up with a project plan and took it to market. We had to balance the timeline and budget and eventually ended up with this treatment plant that serves the land,” said Interwaste CEO Jason McNeil.
“Serving land and life is the purpose of our business, so investing in effluent treatment is at the heart of what we do. It’ sa groundbreaking development that marks a significant leap forward in resource recovery and actively supports [solutions for] the country’s water shortage.”
Operations were temporarily shut down for this week’s launch as Maseko, who ditched her work overalls for elegant attire in honour of the occasion, took guests on guided tours.
Starting at the giant storage tanks where the black liquid waste is held for testing, she said it would be analysed in the site laboratory to determine its chemical makeup.
“Then it goes through a pre-treatment process that involves all the solids being filtered out of it, and an oil-removal process,” she said, pointing to the machinery doing the work.
Then it goes through “dissolved air flotation” where air bubbles are pumped through to lift remaining particles for removal at the surface, then homogenisation or pH balancing.
The final treatment involves the liquid passing through evaporators that pull all salts out into a concentrated brine. Then it is cooled and put through reverse osmosis — forcing it through fine tubes and membranes before treated water is pumped out.
“The water is clean but doesn’t meet the high standards for drinking or potable water
— but that is not what we are trying to do here,” Maseko said.
The treated water is used for dust suppression, cleaning at the plant and by local industries like the brick factory next door. It also meets standards allowing it to be discharged into wetlands and rivers. This will happen when the water produced exceeds the amount being used.
“We are taking something unusable and turning it into something that can free up boreholes for the community and many, many other uses. And the potable water that has been used for various purposes can now be spared for drinking.”
Once the relatively clean water has been processed out of the waste, the leftover 10%20% of residue is safely disposed in the landfill site with all the salts removed.
Stringent testing is done at every step while a system manager, operating everything by computer, watches from an office overlooking all the equipment.
The plant processes about 6,000 litres of water an hour, and every 50 hours is automatically cleaned with compressed air.
“It’s an exciting development signalling a turning point in the waste management landscape.
“It’s a glimmer of hope in the quest for a cleaner, healthier environment and a shining example of progress and possibility,” said McNeil.