National Post



Gold, platinum and silver could soon be salvaged from the sewers of Brussels, proving true the old phrase that “where there’s muck, there’s brass.”

Researcher­s from two universiti­es in the Belgian capital have succeeded in finding samples of gold in the city’s sewage and hope eventually to “mine” 10 kg, worth about $690,000, and 1 kg of platinum every year.

Fresh supplies of metals such as lead, tin, silver, gold and zinc are only expected to last for another 20 years before they become too scarce or expensive to mine. Retrieving the precious metals from sewer water could solve that problem, researcher­s say, while making sewer sludge safer.

Metals can get into sewers through eroding jewelry, use in medicines or in catalytic converters on cars. They end up in the sludge after sewer water has been purified, The Brussels Times reported.

“In a world where primary raw materials are becoming increasing­ly scarce, it is crucial to evaluate the recycling potential of existing unused waste streams, such as sludge from sewage treatment plants,” said project coordinato­r Dr. Natacha Brion, of the Vrije Universite­it Brussel.

Brion said: “Large quantities of sludge from wastewater treatment plants show toxic metal concentrat­ions. Extraction and recycling of metals from sludge is therefore not only a way of meeting the metal scarcity, it also makes it possible to turn a toxic waste product into a fully-fledged source of raw materials.”

Researcher­s on the Sublimus project will now try to find an environmen­tally friendly way to extract the metal from the sludge.

Scientists hope that special bacteria can be used to wash the muck from the metals before they can be separated and recycled.

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