Researchers
from the University of New South Wales (UNSW), located in Sydney, Australia, have
shown that they can safely destroy hazardous industrial toxins in ground water
arising from PVC plastic production by injecting naturally occurring bacteria
into a contaminated Sydney aquifer – an Australian first that raises hope of
cleaning up this and similarly polluted sites around the country.
The trial
has confirmed the bacteria's natural ability to degrade and clean up
chlorinated solvents that leaked many years ago from a former ICI Australia
chemical plant into the Botany Sands Aquifer, creating large plumes of
contaminated ground water.
ICI's
successor, Orica Australia Pty Ltd, presently pumps out the contaminated water
to prevent the plumes from spreading and entering Botany
Bay. That water then is piped to a special treatment plant for
decontamination. No other feasible option has been available.
"With
present technology, it was expected that it might take decades or perhaps
centuries before these toxic solvents are removed from the aquifer," says associate
professor Mike Manefield, a future fellow in the UNSW School of Biotechnology
and Biomolecular Sciences and deputy director of the Centre for Marine
BioInnovation, who led the research team.
"The
energy demands and hence the financial burden of operating the contaminant
containment system over this period of time is significant, but, with our
cultures in the ground, we have the potential to greatly reduce the cleanup
time and the cost and environmental footprint of containment.
"Our
tests showed that these bacteria effectively breathe these pollutants the way
we breathe oxygen. It's a big step forward. These cultures represent a greener
and cheaper tool we can use to clean up some of our contaminated sites. They
have not previously been available in Australia. The real appeal is that
they’re Aussie bugs.
"We're
now very hopeful that other contaminated industrial sites, such as at Altona,
in Victoria,
can be cleaned up relatively quickly in this way as well," he says.
The
researchers collected bacteria occurring naturally in the Botany aquifer, and
isolated three bacterial communities that live off the breakdown of pollutants,
including the first one known to degrade chloroform – a possible carcinogen
that has been banned for many years in consumer products.
It was
found that bacteria had not degraded more of the pollutants on their own
because they could not build up and sustain large populations in the aquifer
due to a lack of food. Further studies in which large volumes of the bacteria
were grown in beer kegs showed that they thrived on a variety of diets,
including ethanol, glucose and emulsified vegetable oils.
Cost-effective
methods for distributing and sustaining the bacteria in contaminated soil and
ground water have been developed internationally, and the Australian
environmental consulting sector has the expertise and capacity to do the same
on this continent.
The next
step will be to inject large numbers of the home-grown bacteria and a suitable
food supply into polluted ground water. The team soon will publish technical
details of the discovery of these cultures, and has received $1.14 million in
funding from industry and the Australian Research Council to carry out a large-scale
biological remediation of ground water at Botany and Altona.
"Cultures
for chlorinated solvent degradation have not been available in Australia before owing to our strict quarantine
laws, so this puts a new technology in the tool box of the remediation industry
in Australia,"
says Manefield. "We've also devised new ways for the technology to have
maximum impact when it is used.”
