Researchers at the United States Geological Survey have detected gold, silver, and other precious metals in human waste.

As Chemistry applicants will know, finding trace amount of elements is not in itself a significant discovery, but the amount discovered in human waste matches that of the levels in a mineral deposit – a level which would be profitable enough for traditional mining.

Dr. Kathleen Smith, the lead researcher, says that metals are plentiful in sewer drains, found in grooming products and deodorant and other chemical compositions, which collectivise and crop up in wastewater treatment plants. Discovering ways to utilise waste products wil decrease the need for mining, and reduce metals unintentionally being released into the environment. Geography students should read further on the environmental impacts of metal ore mining.

The recovery of these metals is performed through leaching, a process of extracting minerals from solid deposits by dissolving them in a liquid in an industrial setting. The study found that 7 million tonnes of biosolids, the name for the composite of human waste and debris from wastewater facilities, comes from the US alone, and being treated in this way will allow the collection of precious metals and the use of treated biosolids as fertilise.

Mathematicians and Economics applicants will be interested to review Dr. Smith’s estimated ‘waste-profit’; she estimates that $13 million could be recovered through the waste of a million Americans alone. Engineering applicants should also consider how innovations such as chemical leaching can be used to improve upon pre-existing engineering solutions to waste disposal.

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