Coffee Grounds Could Clean Up Lead-Contaminated Water
Coffee is one of the most commonly consumed beverages in the world, which makes spent coffee grounds one of the most frequently tossed out waste products of your morning routine.
Over the years, people have found myriad uses for spent coffee grounds, ranging from fertilizer fodder to meat marinades, but scientists have found a way to use the discarded grounds to filter lead and mercury out of water.
The discovery could give residents dealing with harmful heavy metals in their water systems cheap and sustainable access to safer drinking water.
Scientist Despina Fragouli and her colleagues at the Italian Institute of Technology found that mixing spent coffee grounds with a silicone product creates a rubbery foam substance capable of separating out lead and mercury from water, according to a study published in the journal ACS Sustainable Chemistry & Engineering.
Other studies had shown that coffee in powder form is able to extract metals from water but often requires the use of synthetic materials.
“The proposed method is cheaper and more sustainable compared to other systems where synthetic materials are used,” Fragouli said.
Photograph of the bioelastomeric foam (upper left); images of the bioelastomeric foam with the spent coffee powder. (Photos: ‘ACS Sustainable Chemistry & Engineering’)
The potential benefits of this kind of sustainable technology are hard to overstate. According to the Centers for Disease Control and Prevention, there are an estimated 4 million U.S. households with children being exposed to high levels of lead. Short- and long-term effects of lead exposure include memory loss, abdominal pain, depression, lower IQ, and hearing problems.
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The team turned espresso coffee grounds into a powder, mixed it with silicone and sugar, and baked it to create brown foam blocks that act as water filters.
In still water, the foam removed 99 percent of lead and mercury traces. When water flowed through the foam—as would be the case in a real-world water filtration system operating in pipes—it removed 67 percent of lead.
Fragouli said the findings were surprising, as the foam blocks tested were natural products—made up of 60 to 70 percent recycled coffee grounds and biodegradable.
“The efficiency of the coffee was preserved,” Fragouli said. “In this way, the porous composites can be safely and easily utilized and disposed of, making possible large-scale utilization.”
She sees the coffee foam blocks being installed at industrial water sites and urban wastewater processing plants.
The ongoing Flint, Michigan, water crisis highlighted the threat of lead contamination in drinking water, and a CNN investigation discovered that more than 5,300 water systems in the United States are in violation of the Environmental Protection Agency’s lead and copper standards.
Replacing the lead pipes in Flint’s water system alone is estimated to cost $55 million, so cheap, disposable, small-scale fixes could help cities lower the cost of cleaning up their water.
Fragouli and her fellow researchers said more testing of the product’s durability and capacity to filter out acceptable levels of heavy metals in real-world conditions is needed.
“We are investigating if we can arrive to the acceptable limits for lead and mercury for drinkable water,” Fragouli said. “In order to arrive to a commercial product, we need to make further studies based on the exact application on which this material can be used.”