The Precious Gold Trapped in E-Waste Can Be Filtered by Fungi

Finnish researchers find that nature's recyclers make for capable gold diggers.

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In 100,000 cell phones, it's estimated that there is 2.4 kilograms of gold, more than 900 kilograms of copper, 25 kilograms of silver, and more. Depending on the market prices, that's about $250,000 dollars worth of metals, spread in small amounts across 100,000 nigh disposable devices. To more easily recover those rare, expensive, or potentially harmful materials from cell phones and other forms of e-waste, researchers are looking for help from nature's own decomposition specialists: fungi.

The VTT Technical Research Centre of Finland has developed a biological filter made of mushroom mycelium mats that could recover as much as 80 percent of the gold in electronic scrap. Gold adhered to the biosorbents, such as fungal and algae biomass, far better than when just chemical preparations were used, which typically recover 10 to 20 percent of the gold.

Recycling electronics is a difficult process. Ruediger Kuehr, the executive secretary of the Solving the E-Waste Problem Initiative, told Motherboard's Stephen Leahy that each mobile phone is "made up of 40 to 60 different elements," all of which require processing.

And for myriad reasons, you don't want those elements to reenter the ecosystem. Some of the elements are heavy metals that could be harmful if they seep into the groundwater; some are environmentally taxing to mine and collect. And some, like copper, silver, and gold, are rare and valuable. In addition to the environmental concerns, recycling phones could keep the price of future electronics down.

As part of the Associated European Research and Technology Organizations' “Value from Waste” project, the team from VTT engineered biological filters that were aimed at recovering gold in a less environmentally hazardous way that the current methods of smashing, separating, and smelting. Much like how one makes an omelet, though, the first step was still to break all the phones.

“Because it is difficult to remove the components from the circuit boards, the first step in most recycling processes is to crush everything into particulates and that’s how we start too," Jarno Mäkinen, Research Scientist at VTT Technical Research Centre, told EE Times Europe.

“But then, using non-toxic water-based solutions, we have managed to engineer mycelium-based biomass that acts as a biosorbent specifically targeted at gold complexes,” Mäkinen said. The researchers didn't want to go into too much detail on biomass engineering, which relied on organic chemistry and ionic liquids to dissolve the gold particulates and form new complexes, but they did explain that they envision one day creating particular layers designed for recovering particular elements.

The VTT team isn't the only one tapping nature's own recyclers. A team of Indian and South Korean researchers researched using biomaterials to filter lead out of wastewater from an e-waste recycling facility.

E-waste is a growing problem, increasing at a rate of 3 to 5 percent a year, which is three times faster than any other solid waste stream. Stemming the tide of electronics flowing into dumps is important, but thus far even e-waste recycling processes are energy intensive and ecologically questionable. But fungi have been in the waste disposal game for a long time. It seems only natural that eventually we'd take a cue from them.