Oct 25, 20205 min read

Urine… The new golden liquid?

Updated: Apr 10, 2021

The best organic fertilizer… is free and abundant!… This is urine.

Farmers have always used manure to fertilize their soils, so why don’t we use human body waste in general, and urine in particular?

Manneken Pis

Urine is a valuable (body) waste stream that could be used to help organic agriculture within the framework of circular economy.

As a matter of fact, it obviates the production of synthetic fertilizer as it is a source of nutrients that plants need to grow, such as nitrogen, phosphorus, and potassium, and that we humans ingest when we eat these plants in the first place.

How much more organic could we possibly be?

Urine is a body waste

Almost 20 years ago, as a Ph.D. student, when my colleagues and I thought about recycling body waste, we were conflicted.

First, that seemed the perfect idea to enter into the circular economy.
Secondly, that seemed certainly a clever way to reduce the use of chemicals and maintain the quality of our soil.
And as a third point, what could be more organic than recycling body waste?

But there was a big problem as well.

No one of us wanted to carry out at least three years’ worth of lab work with urine, not to mention other excrements like faeces, earwax, nasal discharges, gas from people’s farts, carbon dioxide,…?

Body waste

I know, this is gross.

Carbon dioxide was seen as the more “respectable” waste to use, so I went into this area of research, but some body waste such as urine might be the perfect answer for a sustainable organic agriculture.

The importance of going to pee

Who hasn’t heard of urine as “the best fertilizer”?

Is there any man who has never been advised by a parent, a gardener, a friend, to go and water part of his plantations?

But what is urine?

Our pee is composed of 96% of water, but it also contains more than 3000 chemicals, mainly urea, but also trace elements such as P, Mg, Na, Cl, K, Mg, Ca, S.

Urea

What is our production of urine in one day?

An average adult produces around 1.4 l of urine per day (the range spans from 0.6 to 2.6 l per person per day).[1]

Why is it good for the agriculture?

What comes out of our bodies contains almost all the nitrogen and phosphorous we ingest.

Three of the elements found in urine are of much interest for agricultural purposes: N, P, K which are essential for plants to grow.

The three most important elements in urine

“When plants grow and produce food, that food is full of nitrogen and phosphorous. When we eat it, we rearrange the molecules, but the elements don’t go away; they come out dissolved in our urine. If we can return those elements to the soil, it really is giving back the very thing we took in the first place.” — Abe Noe-Hays, research director at the Rich Earth Institute.[2]

The history of using urine as fertilizer

In the XIXth century, urines from people living in Paris were collected and used to fertilise agricultural fields around the city.

This practice disappeared in the following century with the generalisation of sewage, the advent of chemistry in general and synthetic fertilizers in particular.

Since the 1990s, initially in Sweden, followed by Nordic and German-speaking Europe, awareness has been growing of the role of urine.

Urine is responsible for three-quarters of urban nitrogen excretions and is a safe substance. This new awareness has been followed by extensive experimentation and research on urine source separation.[3]

Isn’t that the best example of circular economy?

Circular economy

Why we should not let urine go to waste(water) [4]

Getting rid of urine through our toilet flushes inflicts four-fold damage on the environment.

1. It wastes drinking water

2. It gets rid of nutrients useful to our soils and enhance the development of synthetic fertilizers, which means emission of CO2.

As a matter of fact, nitrogen is produced by chemical synthesis, potassium and phosphorus require mining.

3. It increases the cost of wastewater treatment as nitrogen & phosphorus are not easily handled by treatment plants.

4. It damages the corals.

Although urine only makes up about 1% of wastewater entering treatment plants, it is the main source of pharmaceuticals in municipal wastewater and contributes 80% of the nitrogen and 50% of the phosphorus load.

These nutrients enter into the groundwater and streams that feed into lakes and oceans. Algae and other water plants ingest these nutrients and flourish just like crops.

These algal blooms deplete the oxygen that fish and aquatic organisms require, creating dead zones like those in the Gulf of Mexico and Chesapeake Bay.

Death coral in the Gulf of Mexico

Of course, urine is not the only reason for this eutrophication but it does play a significant role.

If urine were collected separately from other domestic wastewater streams, it could be treated to remove or destroy pharmaceutical products and recover nitrogen and phosphorus for reuse as fertilisers. [5]

So, what innovations are out there for the collect of urine?

Urine diversion, i.e. the separation of urine before it enters the municipal waste water systems, gained momentum across the Atlantic during the 1990s.

Sweden pioneered the NoMix toilet and now has about 700,000 on-site sanitation systems. One of them is showcased in Singapore.

No-mix vacuum toilet: the new generation of toilet

So, what happens to the body waste after it goes down the drain?

Liquid waste (urine) and solid waste (faeces) are separated. Urine goes to a processing facility where nitrogen, phosphorus and potassium are extracted for fertilizing purposes. The remaining grey water follows its course but ends up being treated as well.

In Paris, for a couple of years now, public urinals that turn pee into fertilizer have been installed.[6]

New Open-Air Urinals in Paris

Is there any other usages of urine?

Medicine

Urine was a key ingredient in the medicines of many ancient civilizations.

Manuscripts discovered by historians have revealed that in Ancient Rome urine was used as a mouthwash to clean and whiten teeth.[7]

Thirst

If you have watched the TV serie show “You vs the wild” by Bear Grylls [8], you know that you can use your pee to clean your wound or to quench your thirst, if you are alone in the desert, and no other alternative is available.

Bear Grylls in “You vs the wild”

Energy

In 2012, a urine powered generator has been developed in Lagos, Nigeria. Urine can now be used as a source of electric power. 1 l of urine could power a mobile phone for 6 hours.[9]

Urine powered generator

Textile

Urine has also be used to prepare textile before dyeing them, especially wool.[1]

To conclude, like the Manneken Pis, stop wasting your pee![10]

Your urine is too good to be wasted!

There is no alternative
to sustainable development

Urine… The new golden liquid?

Urine is a body waste