Blog Post

Urine Collection Beats Composting Toilets for Nutrient Recycling

Human urine collection and use provides a better way to recycle nutrients than use of composting toilets.

Abe Noe-Hays of the Rich Earth Institute standing in front of a urine storage tank.

Photo: Alex Wilson
Just when you thought it was safe to enjoy this blog over a cup of coffee here’s an article on…urine?

Really?

Let me explain.

Urine is a largely sterile, nutrient-rich resource that can be used in fertilizing plants. In fact, according to the Rich Earth Institute, the urine from one adult in a year can provide the fertilizer for over 300 pounds of wheat—enough for nearly a loaf of bread per day.

The Rich Earth Institute is a Brattleboro, Vermont-based organization that’s at the leading edge of the little-known practice of urine collection and use—something that’s emerging in Sweden and a few other places. This past Friday night roughly 200 people gathered at the Strolling of the Heifers’ River Garden in downtown Brattleboro to hear Abe Noe-Hays and Kim Nace from the Rich Earth Institute, along with a New York City comedian/activist, Shawn Shafner, discuss the idea.

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Mixing waste and potable water

With conventional practice, human waste (urine and fecal matter) is mixed with large quantities of potable water and flushed down toilets. From there, it typically flows to municipal wastewater treatment plants where energy- and chemical-intensive processes use bacteria to break down organic wastes, separate out biosolids, kill pathogens, and release that water into rivers or aquifers.

Note that the dry mass of urine is actually greater than that of feces and that nitrogen and phosphorous levels in urine significantly exceed those of feces. 

Image: Swedish data from the Rich Earth Institute
For those living in rural areas not served by a municipal sewer system, that wastewater flows into septic tanks where solids settle out and the effluent then flows into the soil through leach fields—in most cases with most of the nutrients in that waste filtering down into the underground aquifers. I learned when researching onsite wastewater disposal years ago for Environmental Building News (see On-site Wastewater Treatment: Alternatives Offer Better Groundwater Protection, as well as the more recent Waste Water, Want Waterthat the aquifers under rural New England towns almost always have nitrate levels that significantly exceed federal drinking water standards.

At the same time, in the chemical industry, tremendous quantities of natural gas are used in the Haber-Bosch process (invented in 1915) to extract nitrogen from the atmosphere, which is made up of roughly 78% nitrogen gas (N2), to produce ammonia fertilizer, the mainstay of commercial agriculture.

Utilizing human urine

When most people think of creating fertilizer from animal waste, they think of manure. Composted cow manure, for example, is widely sold in garden centers. But there are actually far more nutrients in urine than in fecal matter.

In human waste, 88% of the nitrogen is contained in the urine, along with 66% of the phosphorous, according to Swedish research, while nearly all of the hazards—including bacterial pathogens—are contained in the fecal matter.

The idea that the Rich Earth Institute has been advancing for the past several years is to collect human urine, sanitize that urine to kill any bacteria that may be in it (from urinary tract infections, for example, or fecal contamination), and then apply it on fields as a fertilizer.

Abe Noe-Hays (who used to work for our company, BuildingGreen!), has been leading the charge with this idea in the U.S. The Rich Earth Institute secured funding from the U.S. Department of Agriculture, through the Sustainable Agriculture Research and Education (SARE) program to study urine collection and use as fertilizer, and the Institute is into its second year of this study.

Collecting urine

A urine-separating composting toilet.

Photo: Alex Wilson
Specialized urine-separating flush toilets are available in Scandinavian countries with front chambers for capturing urine. Abe Noe-Hays manufacturers a urine-separating composting toilet, and the Institute provides toilet insets for urine collection. On a larger scale, collection of urine from men’s rooms that have waterless urinals is particularly easy.

With the help of Best Septic Service in Brattleboro, the Institute collected 3,000 gallons of urine from over 170 participants in 2013.

Sterilization

According to most experts, simply storing urine for a while in a sealed container is enough to kill bacteria, due to the high alkalinity and ammonia from the urine. But the Rich Earth Institute is experimenting with faster pasteurization systems that heat the urine (including with solar systems that circulate solar-heated fluid through heat exchangers in the urine tanks). They are also testing various strategies for controlling odor—likely the biggest hurdle we face with urine collection and use.

Land application

In Sweden urine is being applied on food crops, but to date, with USDA support and permits from the State of Vermont, the Rich Earth Institute has stuck with less controversial applications on non-food crops—specifically hay fields.

Jay Bailey spreading diluted urine on a hay field in Brattleboro.

Photo: Abe Noe-Hays
Initial results last year with undiluted urine and dilution rates of 1:1 and 3:1, dramatic improvement in hay production was seen (see photo).

Because urine may contain pharmaceuticals being filtered from the body by our kidneys, there is an important question about whether that could pose a problem for use of urine as fertilizer. This year, the Institute will begin an EPA-funded study to test whether residual pharmaceuticals in urine are taken up by vegetables grown on experimental plots.

Better than composting toilets?

I have long been a fan of composting toilets. I like the idea of not mixing human waste with potable water, and I’ve always felt that flushing away the nutrients in human waste was a lost opportunity. But when I learned about urine separation and use (believe it or not in a luncheon presentation on the topic at a conference in Houston, Texas in 2009), I began to see the benefits of urine separation over standard composting toilets.

With standard composting toilets, most of the nitrogen in the waste ends up being volatized as either nitrogen gas or ammonia—and lost into the atmosphere. With urine collection and use, the nutrients aren’t lost; they are recycled in a sustainable nutrient cycle. That's part of why EBN has called urine separation "the next wave of ecological wastewater management."

Urine application test plots; the darker-green strips were fertilized with diluted urine.

Photo: Abe Noe-Hays
This is something we’re considering for Leonard Farm, though we have not installed such a system yet. For more information or to participate in ongoing studies, contact the Rich Earth Institute.

Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. In 2012 he founded the Resilient Design Institute. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed.

Published April 2, 2014

Wilson, A. (2014, April 2). Urine Collection Beats Composting Toilets for Nutrient Recycling. Retrieved from https://www.buildinggreen.com/news-article/urine-collection-beats-composting-toilets-nutrient-recycling

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Comments

December 31, 2020 - 11:15 am

Is there any harm in urinating wherever I might be when I am not taking any prescription medications?

Is human urine any different then animal urine? If it is, why and how is it different?

January 12, 2020 - 11:33 am

Hi Luke,

Rich Earth Institute recently published a great manual detailing all of their lessons learned in urine collection, management, and beneficial use. It includes lots of info on pasteurization options (which I think is what you're after, but that depends on what you want to do with the urine). Sterilization would require much higher temps.

If that's too detailed for your needs, they also have a nice little document on "Using Urine as a Fertilizer in Home Gardens". It  lists these two options:

  • Storing the urine in an airtight container at 68°F (20°C) or higher for six months (WHO guideline)
  • Heating the urine to 176°F (80°C) degrees for 1.5 minutes (US EPA pasteurization method)
Happy fertilizing!
Nadav

January 11, 2020 - 2:39 pm

How long is urine sterilization time with sealed storage? And if you are using a solar heat exchanger to speed up the process, what temps are you aiming for/what's the time delta for sterilization?

Thank you for a thought provoking article.

September 30, 2019 - 9:26 am

Hi, Victor! As far as I know, this service is currently not available in your area.

September 29, 2019 - 3:47 pm

I live in the San Francisco Bay Area, and I do not have a restroom. Rather, I urinate in containers. When I need to go #2, I visit the nearest restroom. I would like to put my urine to good use. To whom in my area can I provide my urine collection? 

October 26, 2017 - 3:36 am

My thumbs-up to Alex and crew of BuildingGreen for a great concept, nice job.

March 19, 2017 - 2:04 pm

I think the applications, especially for use in third world environments is significant.  Often the human demands on soil have depleted its productivity.  Use of urine to replenish the nutrients in the soil could significantly improve the quality of life for millions.

March 13, 2015 - 12:58 pm

Some cultures use it to grow tomatoes that are the best you can find.
Let's face it......everything is recycled in some way.
Everything on this earth was here and will always be here.
The water on the planet is the same water that has been here since creation.

April 11, 2014 - 12:45 pm

I don't think it is a question of urine separating beating composting toilets; it can do both and in fact a urine-separating composting toilet works better than a normal one. It needs far less heat to dry stuff out and it smells far better because most of the odor is often from the ammonia and the pee. There are a couple on the market, including the biolan naturum http://www.treehugger.com/bathroom-design/more-hot-poop-composting-toile... and the recent Gates competition shows a great one. http://www.treehugger.com/bathroom-design/blue-diversion-develops-toilet...