Filter made from coffee grounds pulls lead from water

A new study suggests an unconventional use for the millions of tonnes of used coffee grounds people discard every day: pulling lead out of contaminated drinking water.

Previous research has demonstrated that the chemical compounds of coffee bind to heavy metals like lead and mercury. But it's an inefficient method of water purification, because once you put coffee powder in water, it's hard to get it back out.

That's where researchers at the Italian Institute of Technology come in.

A team headed up by chemist Despina Fragouli created a filter made of 60 per cent used coffee grounds and 40 per cent sugar and silicone.

The coffee foam filter is able to remove 99 per cent of lead and mercury ions from still water over a 30-hour period, and 67 per cent from water that flows through it, according to a study published in the American Chemistry Society's Sustainable Chemistry & Engineering journal.

Finding practical and sustainable ways of decontaminating water is becoming increasingly important in light of the increasingly unsafe lead levels in tap water found in many in older homes and buildings, and the water crisis in Flint, Mich.

• Lead content still a problem in Brandon's drinking water
• Flint water crisis: 6 things to know about the toxic taps
• Lead found in Montreal school's drinking water

The filter isn't ready for the market just yet, but Fragouli told CBC News that it could one day provide a sustainable alternative to current water filters, both domestic and industrial. 

"I believe that this can be used in the future as an eco-friendly application," Fragouli said.