Golden Feces

American researchers at the 2015 national meeting of American Chemical Society outlined the details of an unexpected source of precious metals - sewage. That’s right. According to new research, organic materials (biosolids) generated by wastewater treatment plants may be an untapped source of precious metals and rare elements, including gold, silver, platinum, copper, palladium and vanadium that are used to make cell phones, computers, and other electronic devices.

American researchers at the 2015 national meeting of American Chemical Society outlined the details of an unexpected source of precious metals - sewage. That’s right. According to new research, organic materials (biosolids) generated by wastewater treatment plants may be an untapped source of precious metals and rare elements, including gold, silver, platinum, copper, palladium and vanadium that are used to make cell phones, computers, and other electronic devices.

Dr. Kathleen S. Smith, a research geochemist at the U.S. Geological Survey (USGS), writes that harvesting the valuable metals and other elements present a win-win situation. Wastewater treatment plants are not unfamiliar with the idea of viewing human waste as a resource rather than a waste product. In many plants across the world, nutrients like phosphorus and nitrogen are often removed from waste and repurposed into compounds like struvite for use in fertilizers.

According to Dr. Smith, recovering metals might be equally beneficial. There is a clear financial incentive for recovery.  Though Dr. Smith concedes that a full economic analysis would need to occur on a case-by-case basis, a previous study from the University of Arizona estimates that yearly waste from one million Americans contains nearly $13 million worth of metals.

Recovering metals from human waste has environmental benefits as well. Dr. Smith proposes that seven million tonnes of solid waste leaves US wastewater facilities each year as biosolid waste. Of that, nearly half of that is used as fertiliser on fields and in forests, while the other half is incinerated or sent to landfills. Some of the metals are often a limiting factor in deciding whether the waste can be repurposed as fertilizer. And some fertilizers still release the often toxic materials into the ecosystem.

Sources: Huffington Post, BBC