An environmental engineer has found a way not only to cleanse contaminated wastewater with its own bacteria but to generate electricity from the funky flow. Lars Angenent, an assistant professor of chemical engineering at Washington University (St. Louis), has already prototyped his findings in a device the size of a thermos bottle � a variation on the hydrogen fuel cell � but he knows it will have to scale up dramatically to fill a commercial role. With scaled-up capacity, Angenent said, a large food-processing plant, which now must cleanse its water at a cost, would be able to turn that processing into a profit center. Industrial-scale wastewater treatment plants, he said, could produce enough electricity to power thousands of households while simultaneously cleansing their water. Angenent's microbial fuel cell design uses the bacteria from wastewater on its anode and cathode instead of platinum, enabling it to make a fuel from the water to create electricity while simultaneously neutralizing the biological matter that would otherwise have to be purged from the water.