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Millions of dollars in gold end up in Switzerland’s sewers every year

Swiss researchers detected 43 kg of gold and 3,000 kg of silver in effluent and sludge from waste water treatment plants.(Image: Chainarong Prasert | Shutterstock. )

It sounds like Switzerland’s gold refineries need to urgently start a recycling program, as local scientists have discovered that about $3 million of precious metals passes through the country’s wastewater every year.

Researchers at the Swiss Federal Institute of Aquatic Science and Technology (EAWAG) estimate that roughly 43 kg of gold — worth about $1.8 million at current prices — and  3,000 kg of silver (worth nearly $1.7 million) were flushed away last year.

Researchers also found that about 3,000 kg of silver — worth nearly $1.7 million — goes to waste every year.

In a study published this week, the team said that in some areas of Ticino in southern Switzerland, known for having several gold refineries, “concentrations of gold in sewage sludge are sufficiently high for recovery to be potentially worthwhile.”

There was also a high concentration of gold in the western Swiss region of Jura, where watchmakers use the precious metal to decorate their luxury products.

For the most part, however, the experts believe that recovering metals that end up in sewage sludge is not cost effective yet.

The analysis centered on 64 waste treatment plants across Switzerland and claims to be the first systematic wastewater survey for trace elements in the nation, which is a major gold-refining hub.

It’s estimated that the country’s refineries process about 70% of the world’s gold every year.

The study resembles a research published in the US in 2015, which found that at least $13 million in precious metals could be found each year in the country’s sewers.

Millions of dollars in gold end up in Switzerland’s sewers every year

Sampling at the Werdhölzli treatment plant in Zurich. (Photo: Eawag, Elke Suess.)