When most people think of wastewater they think of toxic, foul-smelling water. But the reality is that sewage also contains a plethora of precious metals and materials, such as silver and phosphorous, that can be recycled.

Safeguarding human health and the future of our planet requires societal transition from the current model of a linear economy to a circular economy. All commercial products created and used should be designed for cradle-to-cradle rather than cradle-to-grave. For example, treated wastewater constitutes raw drinking water. Valuable components of wastewater and municipal sludge can be targeted by urban mining. For example, the sewage sludge generated by a U.S. city of one million people contains phosphorus and precious metals of a value equivalent to about $13 million dollars annually.

Opportunities exist to recover precious metals (e.g., silver, gold), other useful elements and nutrients (e.g., phosphorus, nitrogen) from wastewater streams. At the HHO, we monitor these elements in sewage, in an effort to highlight potential opportunities for responsible material reuse.