Gold in that there sludge

Interesting to see renewed interest in metal extraction from sludge ash - albeit high value metal from source with clearly skewed discharge. I spent a lot of research time, with others, looking at the practicalities and economics of metal removal from sludge ashes in the UK. Not a topic likely to set the Royal Society alight, I grant you, but still...

Anyway, in the UK at least, with improved control/removal at source (where the effort was rightly placed) and the fact that water companies are in the drink and poo business, not the acid extraction, solvent concentration and metals business, nothing ever came of it.

Around the time I was doing all this I remember talking to a Japanese guy who explained how they vitrified sludge ash at one plant and sold the product as jewellery - pieces of this Craptonite adorn my office window ledge to this day. Looks a bit like jet, smells not at all.