In a new effort to not flush everything down the tubes, a team of researchers has found a new way to increase the amount of electricity that we can generate from toilet waste water.
After tracing bacteria, Xueyang Feng and Jason He at the Virginia Institute of Technology (Virginia Tech) found a collaborative relationship between two particular substrates. The latter are materials on which an enzyme reacts, possibly serving as food for an organism. Feng and He realized that this relationship allowed greater energy production than either of the two could manage working alone. This finding de-mystifies how bacteria that are electrochemically active can stir up energy and may also be helpful in making a new treatment system, a microbial fuel cell.
"Tracing the bacteria gave us a major piece of the puzzle to start generating electricity in a sustainable way," noted Feng, an assistant professor of biological systems engineering. "This is a step toward the growing trend to make wastewater treatment centers self-sustaining in the energy they use."
The study helped ferret out ways that certain organics can indeed perform the same job in a compatible way. Generally, some of them serve as food for bacteria that do the work of generating electricity; others conduct energy themselves.
In this case, the substrate lactate was, for the most part, part of a host bacteria's metabolic process in supporting cell growth, while another substrate (formate) oxidizes to send out electrons and produce higher electricity levels.
If the two are put together, they produce a far greater level of energy than when working alone. In this case, these organics work alongside fuel cell receptors. While it's true that microbial fuel cell use in research is not new, Feng and He's work with organics was unique because they managed to measure and catalog how these two organics work symbiotically.
Washington, D.C.'s wastewater treatment plants and other facilities are already drawing energy from waste. In Grand Junction, Colo., a plant is able to gather methane from solid sewage to produce energy. The town is the first city to fuel its vehicles with energy from human waste.
The new research builds on an earlier study by Mohan Qin, a doctoral student in He's lab who made a system that recovers ammonia and takes out other pollutants while producing electricity.
The new findings were published in the Feb. 12 issue of the journal Scientific Reports.
