This Public Toilet Turns Pee Into Street Trees

Illustration for article titled This Public Toilet Turns Pee Into Street Trees

Public toilets are notorious for unsavory behavior and even more unsavory smells. The PPlanter is both a public toilet and a planter, composting the pee it collects to nourish pots of bamboo. And it's apparently odor-free.

This user-friendly, eco-centric design by Hyphae Design Laboratory in Oakland could also help cities in another important way: The PPlanter might be able to turn around Americans' aversion to peeing in public.

The toilet works pretty much like any typical urinal. You step inside a small semi-private booth which is kinda like the typical bathroom stall (except it's on a sidewalk), and pee into a basin. After relieving yourself, you wash your hands using a foot pump, and the small amount of water "flushes" the urine to begin the filtering process.

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The water and urine is run through a filter of charcoal and zeolite, which zaps the ammonia smell we usually associate with toilets. The cleansed wastewater is then deposited in the bamboo's planter, which further filters the urine with wood chips, straw, rock and styrofoam. By this point the urine is so diluted it's not damaging to the plant, only delivering the most helpful parts of our pee to the tree: nitrogen and phosphorus.

And there's good news for the ladies: Women can use a disposable funnel to pee standing up.

Hyphae tested their prototype last year in the Tenderloin neighborhood of San Francisco to good local feedback, estimating that 300 people used the toilet per day. Now the city has ordered a permanent outdoor restroom that consists of two urinals as well as a composting toilet.

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While there are plenty of public toilet prototypes out there with varying levels of privacy concerns and aesthetic challenges, even ones that gather urine for farming, this is probably the nicest-looking (and nicest-smelling) of them all. Plus it's a win-win situation for the community: Neighborhoods that need public toilets the most are also most likely to need shade and sidewalk foliage, and bamboo is a generally indestructible plant that will grow in pretty much any condition. The PPlanter can capture all that yellow and turn it into green. [New Scientist]

Top image by citymaus

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DISCUSSION

szielins
Stephan Zielinski

After relieving yourself, you wash your hands using a foot pump, and the small amount of water “flushes” the urine to begin the filtering process.

It may be a small amount of water to begin it, but it’s going to take a heck of a lot more water to keep the output from killing the plants. Human urine is highly saline and nitrogenous, and we are big animals— while a not atypical dog masses maybe 17 kilos, humans are usually around 70 kg, and so are about four times the size— so we’re talking about a lot of urine. And with Westerners eating a boatload of protein, that means a lot more urea in the mix... Nevius’ article includes the line “In the PPlanter the urine is sent through a 50-gallon drum of water and then pumped into a large plant container.” It’s not clear what he was trying to say— you don’t really send urine THROUGH water, but this is Chuck Nevius we’re talking about, God bless him— but it is in the ballpark for the correct levels of dilution we’re talking about before the output won’t kill the plants. Since San Francisco doesn’t have a greywater system— we just have the one set of water mains— that’s fifty gallons of treated DRINKABLE water we’re contaminating.

More ominously, another reason we use wastewater treatment plants is in the general case, Western urine contains metabolites from medication— and sometimes even the original compounds. Dealing with this requires some specialized knowledge and monitoring.

Amateur civil engineering gets you amateur results.