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Washington: An
innovative device as big as a washing machine kills two birds with
one stone - it harnesses bugs to clean up municipal sewage and
produces fuel.
Commercial versions of the two-in-one device, an aspect of
microbial fuel cell (MFC) being developed by Orianna Bretschger's
team at the J. Craig Venter Institute, could be a boon for the
developing world.
"Our prototype incorporates innovations so that it can process
five times more sewage six times more efficiently at half the cost
of its predecessors," said Bretschger, according to a Venter
statement.
Traditional fuel cells used on the Space Shuttles and envisioned
for cars in the future "hydrogen economy," convert fuel directly
into electricity without igniting the fuel. They react or combine
hydrogen and oxygen, for instance, and produce electricity and
drinking water.
MFCs use organic matter, such as the material in sewage, as fuel,
and microbes break down the organic matter. In the process, the
bugs produce electrons, which have a negative charge and are the
basic units of electricity.
"We've improved its energy recovery capacity from about two
percent to as much as 13 percent, which is a great step in the
right direction. That actually puts us in a realm where we could
produce a meaningful amount of electricity if this technology is
implemented commercially.
"Eventually, we could have wastewater treatment for free. That
could mean availability for cleaner water in the developing world,
or in southern California and other water-deficit areas of the US
through the use of more wastewater recycling technologies," she
said.
Bretschger said the MFC also is quite effective in treating sewage
to remove organic material, and data suggest a decrease in
disease-causing microbes.
"We remove about 97 percent of the organic matter," she said.
"That sounds clean, but it is not quite clean enough to drink. In
order to get to potable, you need 99.99 percent removal and more
complete disinfection of the water."
These findings were presented at 243rd National Meeting &
Exposition of the American Chemical Society (ACS).
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