Research & Innovation 2015-16 - Page 84

Water is high on UCT’s
research agenda
Removing pollution from water and turning waste into value
Research based on work done by Professor Alison Lewis and her team in the Crystallisation and Precipitation Unit
(CPU), is being used at Eskom’s R8.3 million pilot eutectic freeze crystallisation plant. The research, funded by
Eskom, removes all pollution from the water, solidifies it into pure salts and cleans the water so it can be reused in
the power plant.
Using a technique called eutectic
freeze crystallisation, Lewis and her
team, Hilton Heydenrych, Benita
Aspeling, Jemitias Chivavava and
Genevieve Harding, have pioneered
a way of turning contaminated mine
water into clean potable water and
individual salts.
This involves freezing out fresh
water from the hyper-saline brine
that makes up acid mine drainage,
before separating out the individual
salts by freezing them at individual
(eutectic) temperatures. It
produces hardly any toxic waste.
The outcome is water clean enough
to return to the environment, and
salts (such as gypsum, used in
building) that can be recycled.
“Acid mine drainage is talked about
as toxic waste, but it’s 98% water.
It’s about turning waste into value,”
says Lewis. She claims that 99.9%
of polluted water can be reused.
Lewis received a prestigious
Water Research Commission
(WRC) award in the category
of New Products and Services
for Economic Development.
“It is very exciting to see our
years of research being put to
use. Last year, Eskom consumed
298 billion litres of water; the
plant will allow it to improve
its consumption of fresh water,
and to start using polluted mine
water. It’s cost-effective and
environmentally friendly.”
Based on a story by Andrea Weiss.
Young researcher develops cost-effective solution for treating municipal wastewater
Wastewater management is integral to access to clean water and sanitation, and in preventing pollution.
Increasing levels of sewer pollution require sustainable wastewater treatment solutions.
Dr David Ikumi is committed
to tackling this challenge. ”The
struggle for a clean, ample
supply of water for sustaining
life continuously intensifies;
there is a necessity for effective
conservation, management
and distribution of our water
resources,” he says.
Ikumi’s research focuses on
the mathematical modelling
of wastewater treatment
systems, in particular,
bioprocess modelling, based
on the recurrent behaviour of
microorganisms that mediate
wastewater treatment in various
environments. This involves
attempting to virtually replicate
behavioural patterns in the
development of mathematical
models. “It’s similar to
assembling pieces of a puzzle,”
says Ikumi.
Biodegradability defines the
extent to which organics that
enter unit operations of the
wastewater treatment plant
can be broken down. In a unit
process, the unbiodegradable
particulate organics usually
become enmeshed with the
rest of the sludge mass. The
remaining biodegradable
particulate organics, when
broken down anaerobically,
provide energy in the form of
methane and carbon dioxide
production. The models can
aid the design of ideal
treatment systems and
may optimise operations.
Under the leadership
of Professor George
Ekama, the Water
Research Group
has been developing
mathematical models
and wastewater treatment
system configurations that
are used internationally.
“We are continuously asking
ourselves exactly what
the wastewater treatment
systems of the future should
look like”, says Ikumi.
Based on a story by Chido
Mbambe. Photo Michael Hammond.

 eutectic freeze crystallisation eutectic freeze crystallisation

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