Money may not grow on trees, but gold can flow through sewers — at least that’s the case in Switzerland. Scientists recently determined that about $1.8 million worth of gold flows through the country’s wastewater from the refineries that process roughly 70 percent of the world’s gold. That’s approximately 95 pounds of gold stuck in Swiss sludge — an amount that scientists say, in some areas, is worth retrieving.
This gold revelation is part of a larger study conducted by scientists at the Swiss Federal Institute of Aquatic Science and Technology on trace elements found in digested sewage sludge. In a paper published in Environmental Science & Technology, the scientists explain that they pulled samples from 64 Swiss municipal wastewater treatment plants and nearby rivers and found concentrations of 69 different elements. Led by environmental chemists Bas Vriens, Ph.D., and Michael Berg, Ph.D., this study is the first systematic and quantitative assessments of discharged elements found in sewage waste.
Scientists pull out sewer sludge for analysis.
The trace elements found are assumed to come from the waste that emerges from the country’s chemical and medical industries, as well as its several gold refineries. For example, some of the other elements found were niobium and titanium, which are used in metal alloys and coatings, as well as gadolinium which is found in paints. Where the trace elements were identified typically corresponded to the types of industries in the region they were found — which is why it makes sense that elevated concentrations of ruthenium, rhodium, and gold were found in Jura because it is famously the hub of the country’s watchmaking industry.
While the scientists advise that for the most part, it’s not economically worthwhile to recycle many of the trace elements found, the region of Ticino is a different, gilded ballgame. This area is home to several gold refineries and at certain sites, the scientists write,…