Everybody Poops. Now Scientists Are Finding a Way to Reuse All That Human Waste
Some like to yuk it up at a good poop joke, while some scream in horror at the sight of an unruly turd, but then there’s those of us that see a better world reflected in a puddle of urine or secreted away in a pile of poop.
Consider these two problems: First, globally, we go a lot—on a daily basis, we produce about 14 to 17 ounces of poop at 0.8 inches of poop-per-second, per person. In places where sewage infrastructure isn’t available, dealing with waste can be a burden associated with the spread of disease and other human miseries. Second, we always need more raw material to make new stuff and humans are already burning through the planet’s resources like there’s no tomorrow. To some scientists, artists, and doctors, one way to address both of these problems at the same time is to find practical, productive new uses for human feces and urine.
It might seem weird to think of poop and pee as undervalued natural resources that can be used to build a house, or create medical treatments, or power a factory. But the search for better ways to utilize human waste has led to both innovative, high-tech applications, and a rediscovery of surprising implementations from eras when no resource of any value—even if it smelled really bad—could be spared.
“Urine-tricity/Pee Power” is a new project turning mellow yellow into liquid lightning. Ioannis Ieropoulos, professor of bioenergy and self-sustainable systems at the University of the West of England, who created the technology says, “we have experimented with various types of organic matter: municipal wastewater, activated sludge, cattle farm slurry, food waste, rotten fruit, prawn shells, dead insects, and grass clippings. It was inevitable that at some point we would start looking at human waste directly.” Urine, he says, “proved to be a very good fuel.”
Pee Power uses a microbial fuel cell, a kind of battery with two chambers. In one chamber, bacteria first consume elements in the urine, essentially “cleaning” it, and then excrete a substance that can be used as a balanced fertilizer. During this process, the microbes’ natural anaerobic respiration sends electrons along a wire or circuit into the second chamber of the cell, creating an electrical current.
The project has received funding from the Bill & Melinda Gates Foundation and the EU, and has been tested at schools in Uganda and Kenya. Ieropoulos says his university is spinning off a new nonprofit company called Robial, to make urine-tricity “available to those people who need it the most.” After that, he says, Robial will seek out other commercial applications.
Teeth are a depreciating asset—you’ll find the tooth fairy simply isn’t in the market for your secondhand grown-up molar, no matter how long you leave it under the pillow. And unlike when you lose a tooth as a kid, that missing chomper will never grow back. But whether you got that gap from decay or picking a fight with the wrong guy, these scientists believe they have the ability to grow you a new tooth from your own urine.
Teeth are “vital not only for a good smile, but also good health,” reads the abstract for a 2013 paper in the journal Cell Regeneration. According to the Chinese researchers, an “ideal solution” to tooth loss is growing new ones from patients’ own cells. Using cells derived from urine, along with mouse embryonic tissue, the researchers were able to grow “toothlike structures,” and concluded the method “can be used to regenerate patient specific dental tissues.”
The idea does have its critics. Speaking to the BBC in 2013, a stem cell scientist not involved in the experiment said he was baffled as to why the researchers chose urine, noting that the risk of contamination alone makes it “probably one of the worst sources” for raw material.
In a 2014 project that gave new meaning to the expression “shit a brick,” researchers at the Universiti Teknologi MARA in Malaysia experimented with using sewage sludge as an ingredient in concrete. According to a release on the school’s website, demand for concrete is high, and “disposing sludge left over from treating sewage water is a major challenge for wastewater plants in Malaysia.” A team led by Professor Kartini Kamaruddin first created a powder by drying and burning the sludge, and then grinding and sifting the remnants. The resulting material—rather than the usual sand or gravel—was combined with cement to form concrete.
The results of the experiment were mixed. While viable concrete was produced, higher concentrations of sewage powder led to weaker bricks. Still, the team concluded that sewage powder has “a potential role in the manufacture of concrete.”
Material designer Sinae Kim produced pee-glazed ceramics and tiles for This is Urine, a 2018 project that exploring “the potential of human urine.” Kim asks why many modern societies fail to utilize this plentiful resource, which was once collected and used for anything from tanning leather to making gunpowder. Kim says the project “started with a question: can we redefine the meaning of urine in our society by discovering the aesthetic and functionality of it that no one has expected?”
According to a project overview on Kim’s site, she first distilled urine by evaporation, leaving behind a thick, reddish, mineral-rich paste, which she then applied to a series of clay pieces. When heated, the silica in the clay “merges with the minerals in the urine, creating a glossy coating,” writes Kim. The resulting ceramics, a series of bulbous beige vessels, are meant to resemble both laboratory flasks and the human bladder.
“I’m generally fascinated by shapes and textures of human organs, especially [the] human bladder, because it is simply beautiful,” says Kim. The designer adds that her Urine Ware will be traveling to different cities for upcoming art exhibitions, and she has continued to experiment with the pee glaze “under different conditions and temperatures,” since the initial project.
In late 2018, a team at the University of Cape Town led by civil engineering student Suzanne Lambert made the world’s first bio-bricks from urine. In a story on the university’s site, an engineering professor described microbial carbonate precipitation, the process by which the bricks are made, as similar to how seashells are formed. Aside from urine, the bricks incorporate loose sand and bacteria, which breaks down the urine and produces calcium carbonate which can be cemented into any shape. According the article, “The process for making the bricks is designed to create no waste, and its byproducts, like nitrogen and potassium, can be used as fertilizer.”
But it takes a lot of urine for just one bio-brick—about five gallons, or 100 trips to the bathroom. Researchers say urine acquisition is one of the biggest logistical problems that needs to be solved before the bricks could be mass produced.
Not all poop is created equal. Some people’s feces is worth a lot more than others. In 2015, CNN spoke with an MIT research assistant who had made about $1,000 selling his poop to a laboratory. According to CNN, the assistant is among the 3 percent of people who have the “fairly close to perfect" poop required to produce fecal transplant treatments, which, as the name implies, involve transplanting poop from one person to another.
While having someone else’s poop inside your body might sound pretty gross, the treatment can be a literal lifesaver for people with conditions like C. difficile, a stubborn, sometimes-fatal bacterial infection. C. difficile often pops up after a round of antibiotics, which can deplete other, helpful bacteria that live in your gut and help stave off disease. An infusion of poop from a healthy person comes along with a dose of “good” bacteria, which can then repopulate an infected person’s gut and shut down the C. difficile.
Fecal transplants are now also being tested as a treatment for diseases like Crohn’s. And in good news for the squeamish, if you do require a fecal transplant, it may no longer require a literal transfer of poop—“poop pills” containing bacterial samples from healthy stool have proved effective in clinical trials.
The alleged “Poopsteak”
Of course, they can’t all be winners. We may never know for sure whether the legend of the turd burger was a mere hoax, but in 2011 the story captured imaginations and turned stomachs around the world. Outlets like Fox News and Digital Trends reported that a Japanese researcher named Mitsuyuki Ikeda had successfully synthesized an edible, meat-like product from feces. Ikeda, the story went, was recruited by Tokyo Sewage to find productive uses for the never-ending supply of human waste, and the scientist decided to tackle worldwide hunger at the same time. After extracting proteins from the poop, Ikeda supposedly processed the material, combined it with soy to make the stuff palatable, and added red food dye so it would more closely resemble meat. Kind of like those new veggie burgers, only not at all.
However, soon after the tale surfaced, other reporters smelled something foul. For one thing, the story’s source was a single YouTube video, and the university Ikeda mentions in the clip didn’t seem to exist. Forbes, for one, concluded the story was “almost certainly” a prank, but noted there were outstanding questions about the video that prevented a definitive verdict.
But perhaps if there’s one thing we don’t need human waste to cure, it’s hunger.