Everything flushed down the toilet eventually ends up at a sewage treatment plant where it is turned into sewage sludge. Each year in Germany some 200 million tons of the stuff is processed. Half of that is burned in power plants and the other half is used on fields as fertilizer. But farmers are using less and less due to a fear of pollutants. So what do we do with it all?

Scientists at the Institute for Environmental Technology and Management at the University of Witten/Herdecke are experimenting with a new building material made from lime sandstone mixed with sewage byproducts. The project – called EcoBrick – has worked in the lab. Whether it is usable on a larger scale will be proven over the next three years.

Report: Holly Fox