Quirks & Quarks

Thar's Gold in That There Poo

Municipal sewage contains significant traces of precious metals.
Sewage in a settling tank at a treatment plant (John Rostron, cc-by-sa-2.0)
Our waste might be a lot more valuable than we thought. Municipal waste streams contain significant amounts of metals, like gold, platinum, zinc and copper, at concentrations comparable to low grade ore.

Dr. Paul Westerhoff, from the School of Sustainable Engineering and the Built Environment at Arizona State University, has found that samples of sewage from around the United States contained both valuable and toxic metals, mostly in the form of small particles.

It's difficult to know the source, but the fact that these metals were in most of the samples suggests that they come from a variety of sources - household, medical and industrial. Dr. Westerhoff thinks it's possible to harvest these resources and perhaps in doing so reduce releases of other toxins - organics and pathogens - into the environment.

Related Links

- Paper in Environmental Science and Technology
Science news story
Smithsonian story

image copyright John Rostron, cc-by-sa-2.0