A South Australian scientist has worked out how to use ultrasound to clean up finely textured soils contaminated with DDT – once a widely-used pesticide, now banned because it causes cancer, attacks the nervous system and disrupts the hormonal system in humans.
Kandasamy Thangavadivel will tell the Pathfinders 2010: Challenge and Change Conference at the Alice Springs Convention Centre this week (May 26–28) that ultrasound can be used to dislodge molecules of the persistent chemical from fine soil particles.
“DDT was used widely in Australia and around the world for decades until it was banned in most developed countries in the 1970s and globally in 2004,” said Mr Thangavadivel, a chemical engineer at the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE).
DDT residues remained on Australian farms where it was used for stock dips, he said. Small on-farm stock dips and their associated waste sites were DDT hotspots and might cause groundwater contamination.
Based at the Mawson Lakes campus of the University of South Australia, Mr Thangavadivel built on the knowledge that various levels of acoustic energy can break down a range of complex organic molecules.
“By converting the affected soil to a slurry, and using 30 seconds of ultrasound at 20 kHz, we can break the DDT molecules off the finer soil particles such as clay, silt and organics,” he said.
“We were able to remove 80 per cent of the DDT from the soil in this way.”
The DDT can then be collected in pure form and destroyed by other means.
According to CRC CARE researchers, the relatively low amount of energy used is a breakthrough in the low-cost treatment of soils contaminated with DDT.
“This makes the technique accessible to many more locations around the world where the high cost of energy is prohibitive,” Mr Thangavadivel said.
Mr Thangavadivel is one of eight early career scientists invited to present their research results at the Pathfinders Conference, organised by the Cooperative Research Centres Association. The CRCA represents Australia’s 50 CRCs operating under a federal government program to drive public/private sector research.
See the conference program at www.crca.asn.au/conference
See the media releases at www.crca.asn.au/media/annual-conference
Kandasamy Thangavadivel Ph: 0430 056 933
Email: [email protected]
Laurelle Halford (Alice Springs Convention Centre, May 26–28)
Ph: 0417 222 211 Email: [email protected]
CRCA Media Ph: 0419 250 815 Email: [email protected]
Peter Martin, CRC CARE Communications Ph: 0429 779 228