While working on a novel method to clean polluted water, Rob Nerenberg had a bright idea that
could light up the country. The Notre Dame assistant professor of civil engineering realized that
with a few easy tweaks his process could transform nearly every municipal wastewater treatment
plant into a power plant.
The key is something called "hollow fiber membranes," material that resembles limp
angel hair pasta, commonly used in industrial filtration processes. In earlier work, the Notre
Dame researcher demonstrated that when the strands are placed in wastewater tanks, they
become coated with a film of bacteria that can be harnessed to cleanse the water, removing
nitrogen. The process eliminates the need for bubbling air through sludge, potentially cutting a
plant's energy consumption by 60 percent.
It gets even better. He realized that if the hollow fiber membranes were pressurized with
air and coated with an electrically conductive material on the outside and inside, and the interior
and exterior were connected -- all easily done in theory -- you would have the equivalent of a
hydrogen fuel cell, a nonpolluting method for producing electric energy.
"This could be an ideal way to take an existing wastewater treatment plant that currently
uses a lot of energy and convert it to an energy source," Nerenberg says. He estimates that a
facility serving a city of 100,000 might provide enough power for up to 300 homes and says his
ongoing research will help determine whether the idea would be feasible for a full-sized plant.
(January 2008)
