Learn how poop can be recycled to produce fertilizer, heat, and electricity, in this episode of Gross Science from NOVA. At Jordan Dairy Farms in Massachusetts, poop is collected from cows to power and fertilize the farm. Animal poop contains microorganisms that produce an energy-filled gas called methane. On the farm, manure is pumped to a giant tank called an anaerobic digester, where the methane gets funneled into an electricity-producing engine. Methane is used to produce electricity, and the leftover digestate is used to make fertilizer. Human sewage can also be treated in huge anaerobic digesters, such as those at the Deer Island Treatment Plant, to produce heat, electricity, and fertilizer. This resource is part of the NOVA: Gross Science Collection.