Switzerland discovers 43 kg gold and 3 t silver flow into sewers each year

A study by the Swiss Federal Institute of Aquatic Science and Technology (Eawag) for the Federal Office for the Environment (FOEN) measured metal residues in 64 wastewater‑treatment plants across Switzerland. The researchers found that, on average each year, about 43 kilograms of gold and 3 tonnes of silver enter the sewer system, together with roughly 1,070 kg of gadolinium, 1,500 kg of neodymium and 150 kg of ytterbium. These metals originate from industrial activities such as gold refining, watch making, pharmaceuticals, electronics, magnets and medical imaging devices.

Because the cost of extracting the metals exceeds their market value, large‑scale recovery is deemed uneconomic nationwide, although limited recovery might be viable in the gold‑refinery‑dense Ticino region. The study’s purpose is environmental monitoring rather than treasure hunting, aiming to track how valuable elements disperse in the environment and to inform future ecological risk assessments.