Meet the ‘pee recyclers’, alternative to chemical fertilizers

When Kate Lucy saw a poster in town inviting people to learn about something called “peecycling”, she was stunned – pee recycling? “Why would someone pee in a jar and put it away?” she wondered. “Sounds like a crazy idea.”

She had to work the night of the briefing, so she sent her husband, Jon Sellers, to satiate her curiosity. He came home with a pitcher and funnel.

Human urine, Sellers discovered that night seven years ago, is full of the nutrients needed for plants to flourish. In fact, it has much more than “number two” with almost none of the pathogens (disease-causing bacteria).

Farmers typically apply these nutrients – nitrogen, phosphorus and potassium – to crops in the form of chemical fertilizers. But this comes at a high environmental cost, in fossil fuels and mining.

The local nonprofit group that ran the session, the Rich Earth Institute, was working on a more sustainable approach: plants feed us; we feed them. Initiatives like these are increasingly urgent, experts say.

Russia’s invasion of Ukraine has exacerbated global fertilizer shortages, which are driving farmers to despair and threatening food supplies. Scientists also warn that feeding a growing global population in a changing world will become increasingly difficult.

Today, after donating nearly 4,000 liters of urine, Lucy and her husband are part of a global movement that seeks to address a range of challenges – which include food security, water shortages and inadequate sanitation – by not wasting our waste.

At first, collecting urine in a pitcher was “a little unpleasant,” Lucy said. But she was a nurse and he was a preschool teacher; peeing didn’t scare them. They would drop off a few containers every week at an organizer’s house, but later install tanks at their house, which are professionally pumped.

Now Lucy feels a pang of remorse when she uses a regular bathroom. “We make this amazing fertilizer with our bodies and then we dispose of it with gallons of another precious resource,” Lucy said. “That’s really crazy to think about.”

Bathrooms are in fact the biggest source of water use inside homes, according to the Environmental Protection Agency. More rational management could save vast amounts of water, an urgent need as climate change worsens drought in many places.

It can also help with another deep problem: Inadequate sanitation systems – including leaky septic tanks and aging sewage infrastructure – overload rivers, lakes and coastal waters with nutrients from urine. Chemical fertilizer runoff makes the situation worse.

The result is algal blooms that trigger the mass death of animals and other plants.
In one dramatic example, manatees in Florida’s Indian River Lagoon are starving after sewage-fed algae blooms destroyed the seagrass mammals depend on.

“Urban and aquatic environments become horribly polluted, while rural environments are depleted of what they need,” said Rebecca Nelson, professor of plant science and global development at Cornell University.

In addition to the practical benefits of turning urine into fertilizer, some people are also drawn to a transformative idea included in the venture.

By reusing something that used to be discarded, they say they are taking a revolutionary step towards addressing the biodiversity and climate crises: moving away from a system that constantly extracts and discards, towards a more circular economy that reuses and recycles continuously.

Chemical fertilizer is far from sustainable. Commercial production of ammonia, which is primarily used in fertilizers, consumes fossil fuels in two ways: first as a source of hydrogen, which is needed for the chemical process that converts nitrogen from the air into ammonia, and then as a fuel to generate the intense heat needed. .

By one estimate, ammonia manufacturing contributes 1% to 2% of global carbon dioxide emissions. Phosphorus, another essential nutrient, is extracted from rock, whose supply is dwindling.

Across the Atlantic, in rural Niger, another urine fertilization study was created to address a more local problem: how can female farmers increase crop yields? Often relegated to fields farther from the city, women struggled to find or transport enough animal manure to replenish their soils. Chemical fertilizer was very expensive.

A team that includes Aminou Ali, director of the Federation of Maradi Farmers’ Unions in south-central Niger, guessed that the relatively fertile fields closest to people’s homes were getting help from villagers who relieved themselves outside.

They consulted with doctors and religious leaders about whether it would be appropriate to attempt urine fertilization and were given approval. “So we said, ‘Let’s test this hypothesis,'” Ali recalled.

It took a while, but in the first year, 2013, they had 27 volunteers who collected urine in jars and applied it to plants along with animal manure; no one was willing to risk their crop on pee alone.

“The results we got were fantastic,” said Ali. The following year, approximately 100 more women were fertilizing this way, then 1,000. Her team’s research found that urine, with animal manure or alone, increased the production of millet, the staple crop, by about 30%.

This could mean more food for a family or the ability to sell the surplus in the market and get money for other needs. It was taboo for some women to use the word “urine”, so they renamed it to “oga”, which means “boss” in the Igbo language.

To pasteurize the pee, it sits in the jar for at least two months before the farmer applies it, plant by plant. Urine is used neat if the soil is moist, or, if it is dry, diluted with an equal part of water so that the nutrients don’t burn the crops. Scarves or masks are advised to reduce the smell.

At first, the men were skeptical, said agronomist Hannatou Moussa, who works with Ali on the project. But the results spoke for themselves, and soon they too began to store urine. “Now it’s become a home competition,” Moussa said.

Understanding the dynamics, some children began asking for money or candy in exchange for the service, he added. Children aren’t the only ones who see the economic potential. A few enterprising young farmers have started collecting, storing and selling urine, Ali said, and the price has skyrocketed in the past two years, from about $1 for a gallon to $6.

“You can pick up your urine like you’re picking up a gallon of water or a gallon of fuel,” Ali said. So far, research into the collection and packaging of nutrients from urine has not advanced far enough to resolve the current fertilizer crisis. Urine collection at scale would, for example, require transformative changes to plumbing infrastructure.

One of the biggest problems, however, is that it makes no environmental or economic sense to transport urine, which is mostly water, from cities to faraway farms.

To address this, the Rich Earth Institute is working with the University of Michigan on a process to make a sanitized pee concentrate. And at Cornell, inspired by efforts in Niger, Nelson and colleagues are trying to link nutrients in urine to biochar, a type of charcoal made from faeces.

(It’s important not to forget about poop, Nelson noted, because it contributes carbon, another important part of healthy soil, along with smaller amounts of phosphorus, potassium, and nitrogen.)

Similar experiments and pilot projects are underway around the world. In Cape Town, South Africa, scientists are finding new ways to collect nutrients from urine and reuse the rest.

In Paris, authorities plan to install pee-separating toilets in 600 new apartments, treat the urine and use it in tree nurseries and the city’s green spaces.

^{Translated by Luiz Roberto M. Gonçalves}