It turns out there's a lot of gold in your excrement

A team of brave researchers has discovered that sewage in major cities can be home to millions of pounds worth of gold and other metals.

After studying sludge - the "goo left behind when treating sewage" - in cities across the US, the team from Arizona State University found that a city with a million people can produce about £13 million (£8.65m) in precious metals each year.

It turns out our sewage is a treasure trove full of valuable elements like gold, silver, copper and platinum, according to the research published in the Environmental Science & Technology journal.

It's not exactly clear how all that metal gets in the system but the Smithsonian suggests it may be from "mining, electroplating, electronics and jewellery manufacturing".

While the Arizona State scientists do not estimate how costly it would be to extract this treasure, a Yale University engineer, Jordan Peccia, told Science that it could be worthwhile.

We’re not going to get rid of this sewage sludge. We need to make this push where we stop thinking about it as a liability and instead we think about it as a resource. And anything we can find in sewage sludge that’s valuable, it’s good.

• Jordan Peccia, Yale

Maybe you can polish a turd after all...

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