Stinky Sewer Solution: Old Coffee Grounds

Posted by Cheryl Perkins on April 5, 2012

A box of coffee grounds in background with cof...Coffee grounds have been proven useful for new innovations in robot hands, biofuel engines for cars, warm sports clothing, and as printer ink. And now the latest: a team from The City College of New York has come up with a way to make an effective carbon filter out of coffee grounds that will soak up noxious sewer gases.

The grounds are an effective filter for hydrogen sulfide (H2S) gas, which smells like rotten eggs and can be dangerous. This is good news for those who work with sewage systems. Some workers have even died from overexposure to H2S as a result.

Why do old coffee grounds work so well as an odor filter? It’s the caffeine. It turns out that caffeine contains nitrogen, which can capture airborne sulfur. Most typical carbon-based sulfur filters require additives like ammonia, but the coffee grounds don’t need any such boost.

The filters are made by baking a slurry of coffee grounds, water, and zinc chloride at 1500 degrees, creating nitrogen-lined holes in the carbon particles ideal for trapping H2S. The New York team’s research could result in a commercially-available eco-friendly H2S filter.

Check out this paper on the research recently published in the Journal of Hazardous Materials.

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