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.