Coffee grounds could be used to suck up sewer stench


February 13, 2012

Coffee grounds like these could be used to remove harmful hydrogen sulfide gas from the air (Photo: Steven Depolo)

Coffee grounds like these could be used to remove harmful hydrogen sulfide gas from the air (Photo: Steven Depolo)

Hopefully, you're not just throwing your used coffee grounds in the garbage ... are you? Not only are they compostable, but they can also be used in robot hands, biofuel engines for cars, warm sports clothing, and as printer ink. Now, it turns out that they have yet another use - a scientist from The City College of New York has discovered that they're good at soaking up stinky sewer gas.

Specifically, the grounds have been found to act as an effective filter for hydrogen sulfide (H2S) gas. Not only does H2S have a rotten-egg reek, but it can also be dangerous. The intense odor can overwhelm peoples' sense of smell, to the point that that they become desensitized to it - people working around the gas, such as sewer workers, have died from overexposure to H2S as a result.

City College professor of chemistry and chemical engineering Dr. Teresa Bandosz realized that coffee grounds could be made into a particularly H2S-hungry type of activated carbon filter, due to their caffeine content. Caffeine in turn contains nitrogen, and nitrogen increases carbon's ability to capture airborne sulfur. Existing carbon-based sulfur filters require the addition of chemicals such as ammonia, melamine, or urea to bring their nitrogen content up to scratch. Used coffee grounds, by contrast, are an abundant resource that don't require the expense of a nitrogen boost.

The grounds can't just be used straight out of the Mr. Coffee filter, however.

Dr. Bandosz and her team started by preparing a slurry of coffee grounds, water and a "chemical activator," zinc chloride. They dried the mixture, then proceeded to bake it at 800ºC (1,472ºF). The resulting carbon particles were found to contain a multitude of tiny nitrogen-lined holes, which are apparently perfect for trapping hydrogen sulfide molecules wafting through the material.

It is hoped that the research could result in a commercially-available eco-friendly H2S filter.

A paper on the project was recently published in the Journal of Hazardous Materials.

Source: The City College of New York

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

I have been desposing coffee n tea into toilet bowls for years. Now I have more reasons to.

Jyanzi Kong

Truckers have known about this for years. I once picked up a floor cleaning machine from a chicken proccessing plant, and they didn\'t drain the water, it spilled out in the trailer, and the stench was horrendous. Two 3lbs cans of coffee spread on the floor deordorized in a few hours.



Did you read the story? You\'d much be better off composting.


My mother already knew that the coffee is the best way to clean your thermocans. Clean and odeur free again!

Sometimes old news makes new news...

Douwe Jan Joustra

So Coffee is not Just good at confusing the dogs at the airport, also for the rats in the sewer...

The catch is that the dogs at the airport have sniffed coffee with the illegal drugs aroma and will probably be much more able to find the drugs because of the coffee\'s aroma. Some tricks only work for a short length of time. Jim Sadler

Coffee too washes the stomach and is also anti bacterial in the mouth.

Dawar Saify

Dawar Saify, Yes it makes your teeth nice and yellow too. yuck!

Denis Klanac
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