Will People Eat Urine-Fertilised Food

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French researchers think they may have found a unique natural alternative to chemical fertilisers.
Their discovery reduces environmental pollution and helps to feed a growing global population, all thanks to an unexpected ingredient – human urine.

The global system of food production is the largest human influence on the planet’s natural cycles of nitrogen and phosphorus.
But the majority of fertilisers are either made by converting nitrogen in the air to ammonia, which alone consumes 2% of the world’s energy and relies heavily on fossil fuels, or by mining finite resources, like phosphate rock.
A solution to this problem could be much closer than people realise.
Most of the nutrients we consume in food are passed in our urine, because our bodies already have enough.
But instead of being recaptured, these nutrients are flushed, diluted, and sent to wastewater treatment plants where they’re scrubbed out, leaving effluents that can be safely released into the environment.
The most nutrient-rich part of wastewater is human urine, which makes up less than 1% of the total volume but contains 80% of the nitrogen and 50% of the phosphorus.
Synthetic nitrogen fertilisers boost agricultural production but if used in excess, they pollute the environment. Their prices are also soaring, especially now with the war in Ukraine.
It has left scientists searching elsewhere for a solution to this combination of crises.
Human urine may seen like a crude way of fertilizing plants in the era of industrial agriculture, but as researchers look for ways to reduce reliance on chemicals and cut environmental pollution, some are growing increasingly interested in the potential of pee.

Going beyond preconceptions

Separating and collecting the urine at the source means rethinking toilets, the wastewater collection network – and overcoming certain preconceived ideas.
The separation of urine from toilets was first tested in Swedish eco-villages in the early 1990s, then in Switzerland or Germany. Experiments are now also being carried out in the United States, South Africa, Ethiopia, India and Mexico.
In France, projects are emerging in Dol-de-Bretagne, Paris, Montpellier.

Research suggests that people are open to the idea of recycling urine. A survey of nearly 3,800 people across 16 countries even revealed that people would buy and eat food grown using human urine.
With technology like this, ordinary people would have a safe and convenient way to make modern life more sustainable every time they go to the bathroom.

There are differences in attitude across the countries where urine-based fertilisers have been trialled. The acceptance rate is very high in China, France and Uganda, but low in Portugal and Jordan.
Since urine is not normally a major carrier of disease, it does not require heavy processing for use in agriculture. The World Health Organization (WHO) recommends letting it rest and itis also possible to pasteurise it.
Once collected, the urine must be transported to the fields. But the procedure is still expensive. Various techniques make it possible to reduce its volume and to concentrate, or even dehydrate it.
There are a lot of obstacles, with soaring gas prices and the desire of many countries to strengthen their food sovereignty. Despite this, researchers believe that urine is the future of natural fertilisers.

capture urine with special toilets that separate it from faeces after you flush.
Evaporating the water from urine: a fast-acting enzyme called urease is invariably present inside wastewater pipes and converts urea to ammonia.
When exposed to air, the ammonia quickly evaporates, taking the nitrogen from the urine with it and giving off a very pungent odour.
Using this technique, a process is developed that can reduce the volume of urine and transform it into a solid fertiliser. We call this process alkaline urine dehydration.
Fresh urine is collected from urinals or specially designed toilets and channelled into a dryer, where an alkalising agent, such as calcium or magnesium hydroxide, raises its pH.
Any water in the now alkaline urine is evaporated and only the nutrients are left behind. We can even condense the evaporated water and reuse it for flushing toilets or washing hands.

The early urine-diverting toilets were considered unsightly and impractical, or raised concerns about unpleasant odours.
But a new model — developed by the Swiss company Laufen and Eawag — should solve these difficulties, with a design that funnels urine into a separate container.
Once the pee is collected it needs to be processed.

Currently India imports about 90% of its requirement for phosphate fertilizers, 100% of potash fertilizers and 20% of urea.
China, Morocco, US, South Africa and Jordan are said to hold 90% of the world’s phosphate deposits.
With growing demand for fertilizers needed for food production, the demand for phosphate is only expected to rise, which in turn will have a profound effect on food prices
India has known the efficacy of urine as fertilizer for centuries. Why then, did we not take the lead in developing urine-based methods of irrigation?
India has followed the western model of using chemical fertilisers, which involves the mining of limited phosphate reserves.

Recently, in Amsterdam, a government initiative led to the setting up of urinals in a park with the aim of turning it into fertilizer for local farms.
Dutch officials said that Amsterdam’s pee alone could fertilize 10,000 football fields’ worth of plants.

Fertilisers using Synthetic Nitrogen

Fetilisers using synthetic nitrogen, in use for around a century, have helped drive up yields and boost agricultural production to feed a growing human population.
But when they are used in large quantities, they make their way into river systems and other waterways, causing choking blooms of algae that can kill fish and other aquatic life.

Agricultural ammonia

Meanwhile, emissions from this agricultural ammonia can combine with vehicle fumes to create dangerous air pollution, according to the United Nations.
Chemical fertilisers also create emissions of the potent greenhouse gas nitrous oxide, contributing to climate change.
But the pollution does not just come directly from the fields.
Modern-day sanitation practices represent one of the primary sources of nutrient pollution and urine is responsible for around 80 per cent of the nitrogen found in waste water and more than half of the phosphorus.