13 Feb 2018

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Clean Water from Left-Over Coffee Grains

The world dumps around 6 billion tons of left-over coffee grains annually, which can be used to produce clean water rather than being discarded in the garbage.

Scientists have found a new use for left-over coffee grains. The grains left after the coffee is served can be used to remove heavy metals, such as lead and mercury, from polluted water. It can also be used in gardens, biofuels, and animal feeds, but much is simply thrown away.

The experts found that coffee could be mixed with silicone, to make it easier to use in filtration, and could remove much of the mercury and lead in contaminated water. They are now figuring out how this technique could be more widely applied. The study is summarized in the New York Times. A more technical summary of their study was published in ACS Sustainable Chemistry and Engineering.

However, this method does not seem to remove the heavy metals entirely. The coffee-based water filter seems to become saturated after removing two-thirds of the poisonous metals. In addition, the technique seems to work best in still water and appears to be less effective with running water.