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December 6, 2004 Vol. 75, no. 10F
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| CEE Professor David Sedlak
spent a year in Sydney, Australia, on a Fulbright fellowship looking
for inexpensive, low-tech ways to purify wastewater and safely reuse
existing water supplies. Along the way, he also learned to surf. |
During Fulbright
year in Australia, CEE professor helps uncover method for purifying
wastewater
For the last nine years, Australia has experienced the worst drought
in its history. Water has been rationed; car washing, swimming pools
and lawn watering have all been strictly regulated. But demand for water
hasn't decreased. Australia's population, for example, grew
1.3 percent from 1993 to 2003, according to the Australian Bureau of
Statistics. Down Under, with a finite water supply, needed ways to reuse
existing water.
The problem sounded familiar, thought CEE Professor David Sedlak, who
studies the behavior of chemical contaminants in wastewater and identifies
cost-effective methods to remove them. It sounded like the state of
California's own water struggles.
"California and Australia are pretty similar in terms of geography
and climate," says Sedlak. "I liked the connection between
the two in terms of drought and how the two places responded to the
challenges of providing a reliable water supply."
The similarity so intrigued him that he applied for and won a Fulbright
fellowship to spend a year at the University of New South Wales (UNSW)
in Sydney looking for an inexpensive, low-tech method that would augment
the country's existing water supply by safely reusing wastewater.
In July 2003, Sedlak relocated his family to a home across from one
of Sydney's beaches and, with a team of professors and graduate
students, launched into the lab work.
Together with UNSW graduate student Sung Hee Joo, Sedlak focused on
nano-sized particles of iron. For over a decade, elemental iron has
been used to destroy unwanted chemicals through reduction reactions,
says Sedlak. For example, it's the technique used to detoxify dry
cleaning chemicals discovered in groundwater at hazardous waste sites.
But Sedlak, Joo, and the team discovered something new: When iron reduces
oxygen, it produces a reactive intermediate that is capable of oxidizing
other chemicals. By studying iron nanoparticles in the lab, they found
that the organic compound (or pesticide) was wholly oxidized, meaning
the reaction process had broken it down, taking steps to purify the
contaminated water.
"The relative simplicity of this technique and the availability
of key reactants suggest that this method could be used to degrade agrochemical
contaminants and contaminants in water treatment," Joo told Uniken,
the UNSW magazine. The water would be suitable again for human use.
With the research going - well - swimmingly, Sedlak and his
family made sure Australia wasn't all work and no play. They took
advantage of the proximity of the beach, Sedlak says, where he snorkeled
and learned to surf. "Sydney Harbour is just like Finding Nemo.
It's full of fish, stingrays, and seahorses, and the water is 70
degrees."
Sedlak also relished learning new Australian expressions, even if they
were at his expense. His new friends christened him a "daggy dresser,"
which translates to messy or disheveled. Sedlak good-naturedly explains
the literal meaning: "The word, 'daggy,' is the unusable wool on the
rear of a sheep."
Despite the ribbing, Sedlak says he made some lifelong friends. "Plus,
I missed a year of construction in Davis Hall," he says with relish.
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