E-waste contains metals such as gold, iron, silver, copper, platinum and palladium, as well as rare earth elements such as yttrium, lanthanum, terbium, neodymium, gadolinium and praseodymium; not to mention glass and plastic. And while the amounts in each phone are small – 0.034g of gold, for example – they quickly add up when you consider that around 42 million tonnes of e-waste were generated in 2014 alone, and the UN Environmental Program estimates that figure is increasing by 3-5% each year.

Currently, most of this waste is shipped around the world for processing in places such as Guiyu in south-eastern China – not coincidentally one of the most polluted places on Earth – because the industrial world has yet to come up with a way to efficiently and economically tease apart the tangled and tiny amounts of resources in each piece of e-waste.

Sahajwalla’s microfactory is designed to do just that. “Microrecycling is the new scientific paradigm,” she says. “Conventional recycling works for the macro-scale but we need to look at the micro-scale, for example where you have mixtures of copper and nickel and zinc together.”

In Sahajwalla’s vision of the microfactory, pre-programmed automated drones are used to pick out items such as circuit boards from a pile of smashed e-waste. These boards are then put into a tiny furnace which uses selective temperatures to extract the valuable resources, such as copper alloys. The glass and plastic can also be combined in this high-temperature smelter to produce silicon carbide nanoparticles, which have a range of industrial applications.

The approach also solves the challenge of extracting rare earth elements, which are called this not because they are necessarily hard to find – they are actually relatively abundant – but because they are fiendishly difficult to refine. In e-waste, particularly hard-drives, rare earths are commonly found combined with iron, which until now has presented an almost insurmountable recycling challenge. But again, Sahajwalla’s microfurnace is able to extract the rare earth oxides, as well as the iron droplets. Even CDs have been recycled into their more valuable components using the microfurnace approach.

Sahajwalla also wants to make the energy inputs into the microfactory as sustainable as possible. “What if we could bring together renewable energy and combination of solar energy along with these materials– that’s when we are truly sustainable,” she says.