Freezing solutions for a water-stressed country

South Africa is among the driest countries in the world, receiving annual rainfall of just 492mm, half the Earth’s average. For this reason, processes used to treat industrial and wastewater can significantly improve the availability of water in the country.

Professor Alison Lewis, dean of the Faculty of Engineering and the Built Environment at University of Cape Town — the first woman to receive such an appointment at UCT, in 2015 — has devoted her career to developing pioneering waste water purification methods,specifically how freezing technology can be used in waste water treatment. Known as crystallisation, this allows the clean layer of ice to be removed from the rest of the water, thus reducing waste.

“Our research and development leads to cleaner products made by cleaner processes,” she says. “Through our precipitation and crystallisation research focused on extractive metallurgy, and particularly platinum group metals, we aim to improve the scientific understanding of these processes for scale-up, optimisation and control. The right technologies applied to these sectors can significantly improve processes and reduce waste.”

Lewis pioneered the fundamentals of crystallisation and its application in water treatment methods and detailed these in the book Industrial Crystallisation: Fundamentals and Applications. Her research efforts are aimed at addressing critical issues faced by industries tackling the water crisis, an issue that is of fundamental importance in South Africa.

She has also been involved in training, nurturing and mentoring students in the Crystallisation and Precipitation Research Unit at UCT, for which she has received much praise. She founded the unit in 2000, shortly after eminent scholar, Professor Gerda van Rosmalen from the Technical University of Delft, gave a two-day crystallisation and precipitation course in South Africa. Until then, there had been no dedicated research into this field in the country. The unit’s work has been applied to the recovery of water, metals and metal salts from hyper-saline brines, mining wastewaters and other industrial effluents.


What started as an idea, with a few eager students and a dedicated international collaborator, has evolved into a to a university-accredited research unit, which has graduated 170 PhD, MSc and BSc (honours) students, produced 71 co-authored papers, seven books and chapters in books, as well as numerous conference presentations. The unit has three laboratories, including two fully equipped, temperature-controlled ice labs to enable research at sub-zero temperatures.

Funding support has been extensive, and has enabled students in the group to be supported with full-cost bursaries and for the laboratory and the infrastructure to be built to international standards. In addition to collaborating with TU Delft, the unit has many other global partners, including the Universities of São Paolo, Minas Gerais, Toronto, Sheffield, Manchester, Lappeenranta-Lahti, Aalto, Tianjin, KTH Royal Institute of Technology, Swiss Federal Institute of Technology and the Norwegian University of Science and Technology.

“The scientific and technological uniqueness and novelty of our research is based on the fact that we work at the interface between two disciplines, hydrometallurgy and crystallisation, and that we work with industrial partners to formulate industrial problems as research questions,” she explains. “This ensures that we avoid pure ‘consulting’ and are constantly advancing knowledge in the field. At the same time, our industrial partners are empowered to implement change since they have been part of developing a deeper understanding of their processes from the start.”

Alongside the unit’s international publication record and the international funding received, Lewis has been praised by her students for her invaluable input into their professional development, as well as her successful drive to attract more women into the field of engineering.

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