TECH KNOWLEDGEY
EVENTS, ADVANCES, AND NEWS
2010
■ BY JEFF ECKERT
ADVANCED TECHNOLOGY
WASTEWATER PRODUCES ELECTRICITY
AND DESALINATION
There is, of course, a scarcity of clean water for drinking, washing, and other critical uses in many parts of the world, so
it would be pretty nice if we could accomplish desalination
without relying on reverse osmosis or energy-hogging
electrodialysis. It turns out that Bruce Logan, an environmental
engineering professor at Penn State ( www.psu.edu), along with a
cadre of researchers from China's Tsinnghua University, have
found a way — at least in theory. The team accomplished the
feat with a modified microbial fuel cell which uses bacteria to
simultaneously clean the water and generate electricity. A typical
cell consists of two chambers — one holding the wastewater and
the other just plain water — with an electrode in each one. Naturally occurring bacteria in the former consume organic
materials and generate a current. The Penn version adds a third chamber in between with ion-specific membranes (i.e.,
membranes that allow either positive or negative ions — but not both — to pass through) between the central chamber
and the electrodes. Salty water is placed in the central chamber. As the bacteria consume the water, negative ions move
from the salty water to the wastewater chamber, and positive ions move to the other electrode chamber, thereby
desalinating water in the central one. "When we try to use microbial fuel cells to generate electricity, the conductivity of
the wastewater is very low," said Logan. "If we could add salt, it would work better. Rather than just add in salt, however,
in places where brackish or salt water is already abundant, we could use the process to additionally desalinate salty
water, clean the wastewater, and dump it and the resulting salt back into the ocean." Before you get too excited, though,
note that there is a catch. It took 200 mL of wastewater (in this case, acetic acid in water) to desalinate 3 mL of saltwater.
As Logan observed, "This is not a practical system yet, as it is not optimized, but it is proof of concept." ▲
■ Three-chambered microbial desalination cells in the
laboratory. Photo courtesy of David Jones, Penn State.
BYE-BYE BLOODHOUNDS
It may sound a bit morbid, but the National Institute of Standards and Technology (NIST, www.nist.gov) recently demonstrated a new technique for locating grave sites. In the past, cadaver-sniffing dogs or ground penetrating radar
has been used for such things, but neither is all that effective at finding bodies that are hidden by concrete or otherwise
disguised. As described by NIST, the new process "uses an alumina-coated porous-layer open tubular (PLOT) column
with a motorized pipette that pulls in air samples at ambient temperatures. The device detects trace amounts of
ninhydrin-reactive nitrogen (NRN) that collects in air pockets above and close to grave soil. Previously, this process
involved the tedious and expensive process of solvent extraction of soil samples. Now, a simple probe slightly thicker
than a human hair can be inserted into the ground to detect decaying flesh." If you need to locate a stiff under a
concrete floor, all you have to do is drill a 1/8 inch hole for probe insertion. To confirm the tester's efficacy, two NIST
chemists buried dead rats and took samples over a period of 20 weeks, at which time the decomposing rodents were
still detectable. No word yet as to whether they're going to look for Jimmy Hoffa. ▲
CUSTOM GAMING COMPUTER
Late last year, some former executives of Alienware got together and formed Origin PC ( www.originpc.com) with the aim of assembling "the best parts and
technology the computer gaming industry has to offer." The result is the Genesis line
of highly customized laptop, desktop, and 3D machines that you "build" from the
ground up. The first job is to choose the case you want which will run you $189 to
10 October 2010
COMPUTERS AND NETWORKING ■ Origin Genesis desktop PC with
optional True
Fire finish.
