SUSTAINABILITY AND THE ENVIRONMENT: ENVIRONMENTAL ENGINEERING
Circular economy spins waste into a resource
Dr Fay Couceiro is trialling technology that cleans up
the environment and boosts agriculture by extracting
a valuable nutrient from an unlikely source – human waste.
Too much phosphorous in the
environment can be damaging.
In waterways it can cause
eutrophication, where nutrient
overload results in algal blooms, reduced
oxygen and suffocated fish.
However, in the right place phosphorous
– a naturally occurring chemical – is
incredibly useful. It helps promote plant
growth and vigour, and is a critical fertiliser
needed by farmers to grow our food.
Worryingly, the world is running out
of phosphorous; there are very few
phosphorous-rich rock deposits left to
mine. As stocks dwindle, fertiliser prices will
rise and crop yields will fall. Another source
of the element has to be found.
Enter the University of Portsmouth’s
Dr Fay Couceiro, whose cross-disciplinary
research is addressing these issues –
environmental threats and resource
depletion – simultaneously. She is trialling
technology that not only removes excess and
damaging phosphorous from waterways, but
also potentially repurposes it for agriculture.
And unlike the current, finite
phosphorous resource, the alternative
source will be around for as long as humans
are around; it will come from human waste.
Dr Couceiro, from the University’s
Department of Civil Engineering and
Surveying, explains how there is a lot
of phosphorous in sewage –
Fay Couceiro
sewage that, once treated, is expelled into
waterways.
“There’s only so much phosphorous on
the planet and we are throwing it down the
toilet, quite literally, and out into the rivers,”
she says. “So we need to capture and use it.”
Working with Southern Water, at a
Petersfield trial site, Dr Couceiro is using
absorptive media – a filter bed of specially
engineered media that adsorb phosphorous
as treated sewage flows through the bed at
discharge points.
“We are working on low-tech methods for
removing phosphorus because many sewage
treatment works are unmanned,” she says.
“This technology doesn’t need any energy to
operate, and the only difference between the
water entering the media and coming out the
other side is it contains less phosphorus.”
Dr Couceiro can’t disclose the
composition of the media due to
commercial confidentiality, but has trialled
several variations, and the most successful
is now being developed.
Nutrition cycle
Once the media have extracted it, the
phosphorous could either be ground into
a fertiliser if it is of high enough quality,
or sold for use in other high-end products
such as light-emitting diodes (LEDs).
Research on end uses for the
extracted phosphorous is
ensuring its effectiveness
and safety.
ILLUSTRATION: 123RF
The science is creating a serendipitous
circular economy, reflecting an interconnectedness
that has long been at the
heart of Dr Couceiro’s research.
As a biogeochemist she looks at biology,
geology and chemistry together, analysing
how the disciplines interact in aquatic
settings for better environmental outcomes.
“There’s a gap in our knowledge about
how these things interact with one another.
If you only focus on the biology or the
chemistry you tend to lose how they’re
connected. So it’s those connections that
I look at,” she says. “Biology affects the
geology; it affects how the seabed forms
and then the seabed affects the chemistry
because it affects how the nutrients get
into the water, and then the nutrients
affect the biology because that decides
how many algae will form for the following
year. So, it’s that circular session.”
Dr Couceiro’s broad body of
research that revolves around removing
contaminants from aquatic environments
has led to cleaner waterways in a variety of
places, from the once-toxic Mersey Estuary
to the Caribbean Sea.
While she is the first to admit that
working with sewage is not as spectacular
as some of her other work, such as diving
off volcanoes in the Caribbean looking
for heavy metals expelled from vents, it is
potentially more impactful.
“We’re talking about a huge reduction
of phosphorus going into rivers, hopefully
less eutrophication, less algal bloom
incidences, less fish deaths from low oxygen
levels,” she says. “And if that phosphorus
can instead go to farmers or other end
users, we are transforming wastewater
from a waste to a resource.”
Dr Couceiro says she is driven by a
desire to leave the world “a little bit better”
than she found it.
“I want to stop anything from
microplastics and phosphorus, nitrogens,
pesticides, pharmaceuticals – all these
things coming out into the environment
that are damaging wildlife – and if I can, in
any way, help, I would like to.”
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ISSUE 1 / 2020