Something I missed earlier in the year was the discovery that when we sit on the toilet, we are literally sitting on a goldmine. US researchers found that the amount of gold in our faeces is about the same as that in mineral deposits. Another study estimated that, by extracting all metals, the annual excrement of a million Americans could be worth $13 million. There are over 300 million Americans, and a further 900 million plus living in OECD countries whose consumption patterns are broadly similar. You do the math.

In addition, extracting toxic metals such as lead would make it more viable to use composted human waste as fertiliser – maybe extracting gas first – turning a waste material into a potential product.

I love this kind of thinking – urban mining in the true sense of the word where everything from road-sweepings to our own poo is seen as a potential goldmine. Where there’s muck indeed…