Harnessing bacteria that produce electricity and break down organic waste, a European research project is developing a new, environmentally friendly way to purify sewage water in small communities. It may look like a park, but an experimental plant in Carrión de los Céspedes, near Seville, is full of wastewater from the nearby town. Yet the air doesn’t smell like sewage. The water is purified the natural way, by underground microorganisms – a traditional method improved