Each year an incredible six billion tons of coffee waste is produced. Much of it ends up in a dump or in animal feed or biofuels but new research from Italy suggests there could be a higher use for coffee waste.
The Research
A study conducted by the Istituto Italiano in Italy has reported that if you infuse left over coffee grains into a porous foam they can remove heavy metals from polluted water. The science behind this is that the chemical components in coffee trap heavy metals like mercury and lead which are common water pollutants and can be poisonous when ingested in high doses. Interestingly coffee has in the past been used to remove lead from water but the problem was always getting the coffee powder out of the water afterwards. This hasn’t been the case in the latest research as the coffee was used as a foam rather than a powder.
The Methodology
The team in Italy literally took old espresso grounds from local coffee bars and mixed them with silicon and sugar. Once solidified this mixture was dipped in water to dissolve the sugar. What was left was dropped in water containg lead and mercury. The research found that when a small piece of the coffee foam was added to water with a metallic concentration of 16 parts per million, 99% of the metals disappeared within 30 hours.
It is important to note that the foam mixture wasn’t as effective in moving water, removing only 67% of the metals. What is clear is that the metal content in water needs time to react with the coffee foam. So for this to have a use going forward then the water would need to move slowly through the coffee foam or be immersed in a tank like structure for a period of time. However this could, if the application can be worked out, be a great answer to what to do with so much coffee waste and help purify drinking water around the world.
So, when you drink your favourite brew, do think about what you do with your left over coffee grains. One day they could hopefully be the answer to cleaner drinking water.