[ASC-media] Media release: cleaning up groundwater

JCA Media jca.media at starclass.com.au
Wed Aug 30 00:36:19 CEST 2006

CRC for Contamination Assessment and Remediation of the Environment

Media Release 06/07

August 30, 2006


A team of Australian scientists is trailblazing new ways to clean up cancer-causing chemicals that have been lurking in groundwater under the nation's cities for up to 50 years.

Researchers in the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment are pioneering a range of techniques to make safe chlorinated and petroleum compounds and other toxins produced by industries a generation and more ago.

"Virtually anywhere there has been a fuel dump, a munitions store, an old chemical factory or heavy manufacturing plant, there is potential for toxic substances to leak into groundwater underneath," says Associate Professor 'Megha' Mallavarapu, who leads CRC CARE's remediation research programme.  

"Today, with urban growth, these sites are often in the heart of our cities - prime residential real estate. And the water may be used to irrigate gardens and parks, sometimes for food production and even for drinking, exposing the population to a risk from the past."

CRC CARE researchers are now testing a range of methods for breaking down toxins underground, without the high cost and risk of having to excavate or pump and treat the site.

A range of techniques including manipulation of naturally-occurring microbes, introduction of specially-selected microbes, physical dispersal, physical lock-up, oxidation and volatilization are being tested at CRC CARE's labs at the University of South Australia.

"Every site presents unique challenges.  No two places are the same, either in the type of pollutants, the type of soil or the pattern of groundwater flow. This means we have to tailor a special solution from the range of techniques available," Megha explains.

A world-first development is the use of tracers and monitors to measure the 'flux' - or variation - in the polluted underground water in real time and over a long period.  This enables the researchers to predict accurately how the pollution will behave, what risk it poses to humans and to devise the best way to deal with it.

"The preferred solution is natural attenuation, in which microbes break down the chemical into harmless fractions or in which it is diluted into insignificance.

"However in cases where the pollution is very toxic, is relatively immobile or just not breaking down, we have to take other measures. These include stimulating the microbes with fertilizer or oxygen or introducing new mixes of microbes better able to handle the toxic substance.

The new approach to making pollution safe begins with establishing the history of what has gone on at the site over the previous century or so, the exact cocktail of pollutants and their byproducts which remains, and the soil, water and biological conditions that are working on them. The next step is to assess whether the contaminants can reach people via the water, air, soil or the food supply - their 'bioavailability'.

This done a tailored plan can be drawn up for the best way to treat the site and make it safe, he says.

"With the growth in our cities, demand for remediation services is growing very fast, as new suburbs overlap old industrial areas," Megha explains.  "The problem is even greater in Asia, where there are literally millions of polluted sites, many of them unknown."

CRC CARE scientists are already working with colleagues in China, Korea and the United States to develop ways to save populations round the world from the epidemic of disease which many now fear may be the outcome of prolonged exposure to toxic substances like TCE, PCBs, benzene and other carcinogens. 

One of the CRC's major efforts is to find ways to make safe the fluorine-based chemicals which are commonly used in fire-fighting foams. These compounds are highly persistent and very carcinogenic, yet still in wide use in many countries including Australia, Megha says.

"We are working on a permeable reactor technique that allows water to pass through but actively removes toxic substances," he says.

Research into techniques for cleaning up the mistakes of the past also means that industry in future will be far safer and cleaner - because the same techniques can be used to cleanse wastes before they enter the environment, he adds.

More information:
Associate Professor Megharaj Mallavarapu, CRC CARE and University of SA, ph 08 8302 5044 or 0411 035 757
Professor Ravi Naidu, CEO, CRC CARE, ph 08 8302 5041 or 0407 720 257
Kim Sinclair, CRC CARE communication, ph 08 8302 3933 or 0416 095 324
Kim.sinclair at crccare.com


CRC CARE is an Australian partnership of scientific, industry and government organisations set up to devise new ways of dealing with and preventing contamination of soil, water and air. 

Its goals include:
- Cleaner, safer food supplies, water  and living conditions leading to a reduced toll of disease due to toxic contamination of our food, water, air and living conditions
- Benefits of up to $1.8 billion per year from direct savings in remediation and improved values or remediated land
- A cleaner natural environment for Australia and its neighbours.

CRC CARE is part of the Australian Government's Cooperative Research Centres Program.

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