The Science of Sustainability

The Living Machine: A Flush Worth Following

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Greenhouse plants are used to help filter wastewater from toilets at an Oberlin College building.

On the small liberal arts campus of Oberlin College in Northeast Ohio, you would expect to see some funky hairdos, a smattering of fixed-gear bikes, and certainly some people strolling barefoot to class. But you might not expect to find their bathroom stalls peppered with “Poop Haikus.”

At the Adam Joseph Lewis Center for Environmental Studies, musings on human excrement dominate the toilet landscape.Living Machine 033

One student writes:

"Normally I hate
Pooping in a public place
Here I feel proud"

Why the sense of pride?  Because the building is a Living Machine.  Literally.

It’s an in-house wastewater treatment and reuse system that mimics the processes of natural wetlands. Student (and faculty) poop fuels the machine, and the water used to flush it down is recycled over and over, after passing through an elaborate cleaning system.

An electronic dashboard displays the amount of recycled vs. city water used at any given moment in the building.

I toured "the machine" with biologist John Peterson and building manager Sean Hayes.  We set out to follow the flush.

The first stop is an underground tank, full of—you guessed it—poop.“I think I just saw something coming in!” exclaimed Peterson after lifting the lid of the tank, and Hayes crouched down to confirm the turd sighting.  This first tank is where the anaerobic action happens—microbes that don’t dig oxygen live here and start breaking down and converting the organic waste.

Then the sludge travels to another underground tank, this one with a bubbler that aerates the system.  A different set of bacteria hang out here and greedily munch on the carbs and proteins, further breaking down the mess.  They’re also helping convert a key element, nitrogen, into a plant-friendly form.

Biologist John Peterson describes how the tropical plants suck up nitrogen and house beneficial bacteria in their roots.

Biologist John Peterson describes how the tropical plants suck up nitrogen and house beneficial bacteria in their roots.

After this, the mixture heads indoors, into a series of open tanks in a greenhouse.  You can watch the greenhouse live on a webcam (though I can’t say it’s compelling television).  Big tropical plants sprout from the tanks; Calla Lilies are in bloom during my visit.  The plants suck up nitrogen and their roots house more beneficial bacteria.  In addition to burning up organic matter and removing pathogens, it’s important for wastewater treatment schemes to remove nutrients like nitrogen and phosphorous, which if released into the environment, contribute to harmful algal blooms.

Next stop is a gurgle through the clarifier basin—where the sludge settles and is sent back to the underground tanks to keep the microbe levels high—and then the clear water is piped underneath the gravel bed of the greenhouse.  This is referred to as the “marsh.”  Here, more anaerobic microbes finish the cleaning job.

When a toilet needs refilling—or the landscaping needs watering—the clean, treated water is passed through an ultraviolet light to kill any lingering pathogens, and then it’s put into action.

The water in the building’s toilets is slightly brown, but Peterson says it’s cleaner than much of the world’s drinking water.

The water in the building’s toilets is slightly brown, but Peterson says it’s cleaner than much of the world’s drinking water.

The Living Machine technology was invented by biologist John Todd in the late nineties (hear him talk about it), and versions of it are now in place in several buildings across the country.

The usefulness of the technology here in Oberlin, where water isn’t scarce, is less about its practical benefits and more about the educational ones. Local schools organize field trips to see the machine at work, and college students organize campaigns to promote on-campus pooping. Even internet gazers get involved with interactive tools and webcams.

It introduces the concept of internal recycling and systems-thinking, says Peterson. "It challenges people to think: what’s waste vs. what’s resource?"

Peterson says coming to this building is an experience—an experience that starts with a trip to the bathroom.  As a friend of mine who had visited the campus proudly told me, “Yep, I made a contribution.”

 

Explore a waterless way to deal with human excrement:  the composting toilet

 

 

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Category: Biology, Chemistry, Education, Engineering, Environment, Water

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Anne Glausser

About the Author ()

Anne Glausser is the Coordinating Producer for QUEST Ohio. Before taking on this role, she was WCPN 90.3 FM & WVIZ/PBS ideastream’s health reporter and produced award-winning radio pieces. She’s spent time on both coasts (her college mascot was the banana slug!), but grew up in the Midwest and is happy to be back home. She got started in radio at PRI’s Living on Earth, and has also spent time as a researcher at the Harvard School of Public Health. Anne got her SM from MIT’s Graduate Program in Science Writing.
  • http://www.unctv.org David Huppert

    solid waste piece!

  • Joe DiGiorgio

    Interesting, but many unanswered questions:

    Where are the salts going?? Can't keep building up or the plants would die, so there must be some unstated discharge to the sewer, or separation process to remove them.

    Also seems like this process vaporizes alot of water; and, in an arid environment, perhaps not the best solution for maximizing the resource. Is the vapor recovered via the AC system??

    Are the building managers licensed as wastewater operators?? If someone gets sick (ie becasue the UV tubes weren't cleaned), who is responsible??

    Very cool demonstration of wastewater treatment plants' functions…. I just don't get how it is more efficient/beneficial than centralized treatment….in fact, per my first point, it probably requires a discharge to centralized treatment or directly to the environment, to handle its wastes. And these wastes may be stronger (gallon for gallon) thereby putting a disproportionate (non-organic) load on the centralized system/environment…higher sewer bills??

  • Lindsey Hoshaw

    Love this: "recycled water fills the building's toilets…and it comes out of their water fountains! Just kidding." Informative article that is playful and handles a somewhat "gross" topic in an engaging way.

    I'm from Arizona and waterless toilets are hugely popular at Univ of AZ sporting events. We haven't reached the point of drinking effluent water in Tucson either, but that day is coming…

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