30 April 2012:
A green technique for capping and cleansing old urban landfill
sites and mine dumps has been successfully trialled in South
Australia.
Known as ‘phytocapping’, it uses green plants to
reduce rainwater flow into old dumps that could release pollution
into nearby groundwater and streams or greenhouse gases into the
atmosphere. The plants can later be harvested to produce clean
energy.
The CRC for Contamination Assessment and Remediation of the
Environment and technology firm FibreCell Pty Ltd announced today
the successful demonstration of the technique using a combination
of a clay cap and giant reeds to seal an old landfill at Salisbury,
SA.
The Leader of CRC CARE’s Prevention Technologies Program,
Professor Nanthi Bolan, explains: “The giant reed reduces the
amount of water which enters the old landfill. This is turn
reduces organic decomposition which leads to greenhouse emissions
from the landfill, and it prevents toxic chemicals and heavy metals
from leaching out of the landfill.”
However, he adds, the giant reeds grow so fast they can be
harvested for use in producing electricity or methanol for use as a
fuel, or biochar for use for carbon sequestration and as a soil
improver in agriculture.
“This makes the process of cleaning up an old toxic dump
useful and potentially quite profitable,” he says. “The
growing characteristics of Giant Reed are well known and understood
by Fibrecell Australia after 7 years of extensive research and
trials. This knowledge has enabled them to develop effective
management protocols that optimise the beneficial uses of Giant
Reed without adversely impacting on, or threatening, the
ecosystem.”
Australia has an estimated 160,000 contaminated sites, many of
them being old urban refuse dumps and landfills, which our
expanding cities have since grown over and around. Keeping toxic
chemicals dumped decades ago contained within these sites so they
do not affect surrounding communities or wetlands is a major
challenge faced by all municipal authorities, CRC CARE managing
director Prof. Ravi Naidu says.
In separate research, the ‘green cap’ of reeds has
also proved useful in preventing dust containing toxic minerals
from blowing from old mine and mineral processing tailings across
inhabited areas, Professor Bolan says.
The CRC has also tested a range of native Australian grasses and
plants to see which are most effective at extracting toxic minerals
for safe disposal, a form of clean up known as
phytoremediation.
A unique feature of the Salisbury project was the use of
biosolids – the solid residue left over from sewage treatment
– as a nutrient source for the green cap crops, the use of
wastewater to irrigate them, and the innovative use of industrial
wasteland to grow a product with real market value for energy
generation.
“Over time we expect the degraded land to be gradually
cleaned up and made safe for other uses, such as urban
development,” Prof Bolan says.
“Around Australia there are literally tens of thousands of
old landfills, dumps and factory sites that are too contaminated to
use in their present condition – but which can be cleansed
and turned back into high-value real estate by low cost techniques
such as green caps.
“This is one way that clean-up science can add billions of
dollars in value to Australia – by freeing up more land in
urban areas in a very affordable way.”
CRC CARE managing director Prof. Naidu says the successful
Salisbury and other trials have given Australian an international
edge in phytocapping, with major export potential.
“There isn’t a city in the world which doesn’t
have health and environmental risks caused by old waste dumps which
it has grown over. We expect that technologies like this can form
the basis of a highly profitable export industry, potentially worth
hundreds of millions of dollars.
“The fact that we are not just dealing with historical
contamination, but also prevent greenhouse emissions and generating
green power illustrates the creative thought that is going into
making Australia a world leader in clean-up science and
technology.”
CRC CARE, established by the Commonwealth Government under its
CRC program in 2005 and renewed for the period 2012-20, is
Australia’s leading R&D provider in the field of clean-up
science.
It is tackling contamination challenges in soil and groundwater
caused by hydrocarbon fuels, heavy metals, perfluoro chemicals,
industrial solvents and associated toxic volatile organic compounds
across Australia.
Its 25 partners include universities, leading industrial firms
and government agencies.
More information:
Prof. Nanthi Bolan, CRC CARE, +61 (0)8 830
26218begin_of_the_skype_highlighting
+61 (0)8 830
26218
end_of_the_skype_highlighting
or 0447 182 320
Prof. Ravi Naidu, Managing Director, CRC CARE, 08 8302
5041begin_of_the_skype_highlighting
08 8302 5041
end_of_the_skype_highlighting
or 0407 720 257
Peter Martin, Acting Communications Manager, CRC CARE, +61 (0)417
776 494
