Publish at April 28 2022 Updated May 26 2022

Go pee in the rhubarb [Thesis]

Urban metabolisms in transition

While we are well informed that the "majority of activities in the Western world would be neither ecologically nor socially sustainable" and that the main reason comes back to the disconnection of natural systems and balances, we may nevertheless remain collectively devoid of solutions other than the simplistic "pee in the shower" and "sort your waste".

Research conducted by Fabien Esculier puts our hopes in their (imaginative and constructive) place by inviting us to divert urine from the current system of water disposal and excreta, and instead go, as his Gaspesian grandmother used to say, "pee in the rhubarb."

Metabolizing the City Differently

In a smart, fluid thesis that mobilizes many disciplines, we benefit from both height of vision and precision, and are invited to concretely measure what is possible to support and do.

One of the major interests of this thesis is to understand at all levels how the situation plays out, and to open up our imaginations (in this or other areas) :

  • At the level of the planet (macro) in its major vital exchanges,
  • At the level of cities(micro) and their metabolism, in particular that of the Parisian agglomeration for which a prospective simulation of a separate urine treatment system has been made. For urban planner Sabine Barles (source):
    "Urban metabolism refers [...] to the set of processes by which cities mobilize, consume and transform natural resources."

At the beginning of the 21st century, Western urban metabolism "induces intensive and widely open biogeochemical flows". There has been, during the industrial revolutions, the development of very intensive uses of materials and people (to increase productivity) and the disconnection of circular organizations of management of natural flows: thus an "opening" of the loops towards a linear economy.

With a friend director of a local agency of prevention and management of waste, we were talking together about "combing the hedgehog" and thus to recover the roundness of the sustainable modality of a circular ecology and economy.

Our urine, a natural fertilizer

Urine is salubrious and rich in nutrients. Very concretely, while the agricultural world imports inputs of fossil origin and excreta that contain nutrients useful to agriculture are processed outside the agricultural system, the proposed transition for the Paris metropolitan area by 2053 gives the following recycling rates:

  • Nitrogen (urine is the majority source of it at the excreta level): recycling rate of 62% instead of 4% currently.
  • Phosphorus (found more in feces): 89% recycling instead of 38% currently.
  • Potassium (almost exclusively in urine): 47% recycling rate for 2% today.

Squaring the Circularity

From the point of view of city organization, Asia is more situated in a circular modality than the West. Western travelers know this well.

The interest of the thesis is also to reposition the question for the West in its temporal modality. Indeed, from the 14th century onwards, a linear system of excreta management dominated in many French cities. And it was far from guaranteeing salubrity.

The organization of the food/excretion system turned around during the industrial revolutions:

  1. In the first stage of the industrial revolution, city-country mutualism and circularity developed.

  2. In the second phase, the industrial revolution operated a disconnection of town and country, "each sustaining itself for its operation, now industrial, from fossil resources perceived as inexhaustible and without impact".

  3. The third phase in which we are currently in is caught in the constraint (and also the ambivalence) that:
    "The intensive use of fossil resources leads to a notable alteration of the modalities of functioning of the Earth system, endangering the conditions of life of humanity. In particular, the major planetary biogeochemical cycles, to which the metabolism of human beings is fundamentally linked, are profoundly altered by the food/excretion systems of industrial cities. "

Taking the measure and measurements of the situation

The purpose of the dissertation is to investigate at all levels the extent to which the food/excretion system of Western cities is unsustainable in its linear modality, and how it can be reorganized to operate in a circular manner.

The work also considers how this system articulates with the other systems of urban metabolism: water, energy, waste, and transportation.

The scientific disciplines mobilized are directly or have been invited:

  • Directly: biogeochemistry, socioecology, territorial ecology, urban hydrology.
  • Invitational: physiology, process engineering, agronomy, history, geography, study of science and technology, sociology of innovation, rudology.

A methodology for characterizing urban food/excretion systems has been implemented in the thesis for the prospective part at the scale of the Paris conurbation. It considers the following items:

  • Knowledge of the quantities and fate of urine.
  • Circularity: rate of use of excreted nitrogen for agriculture.
  • Autonomy: link between the territory receiving the nitrogen and the agricultural feeder space (hinterland).
  • Sobriety of the system by deducting the total amount of nitrogen ingested.
  • Efficiency: assessment of the rate of bio-waste.
  • Pollution: rate of nitrogen excreted by the city that goes directly into the environment.
  • Agricultural footprint: amount of resources mobilized and pollution of the nourishing agricultural space.
  • Couplings of the feeding/excretion system with other subsystems.
  • Sanitation of the system.

Three very realistic cases

In practice, there is already a "wide variety of socio-technical systems of separate urine collection". Some of them have already been implemented in Sweden as early as the 1990s (in ecovillages) and then in Germany. Some of them are still in operation.

To approach the subject in an even more concrete way, the author exposes three cases of figure, in the form of invented dialogues, but very realistic (and bluff!). Reading them really makes you want to implement them at the individual level (1st case), at the level of a collective of inhabitants or workers (200 people, 2nd case), or even a small commune or neighborhood (2,000 inhabitants, 3rd case).

  1. The first case exposes the decision of one citizen to attach himself individually to a group of citizens, founded as an association, who no longer send their urine to the sewer. An individual collection system is connected to a 20-liter outre, which it fills in six weeks.

    In Paris, the issue of storage is crucial: apartments are small and the majority of Parisians do not have a car (often no driver's license either). The group approached a company that collects urine from public urinals in the metro and recycles it for agriculture. Every six weeks, the citizen goes to empty his outre.

  2. The second case is that of an organization of 200 people that reorganized its building to collect urine separately. The choice of toilets was discussed as a collective. Models that involved diluting urine were ruled out.

    This case finely exposes how the gendered issue of urine collection may have arisen. That is, at first, for ease, a solution had been found only for men (I add: or people with a penis, the use of the toilet being even more problematic for transgender people), but not for people with a vulva (ditto), who protested. Two morphological dry urinal modalities were selected, and dry toilets were added. The group organized with an organic farmer, who fertilizes 4 hectares of cereals with 25 m3 of urine per year.

    The imaginary cases were worked out in a very realistic way, and this one did not skip over the issue of organic certification, which must receive non-industrial inputs. The organization makes the users sign a charter: if people eat industrial food, they urinate in the common toilets, if they eat organic food, they can use the specific urinals. The approach is validated by the organic farming certifying bodies and is accepted at the European level.

  3. The third and final case involves a commune twinned with a Swedish commune in which selective collection has been practiced for over 20 years.

    The municipality worked with a toilet manufacturer to build a mixed system with flushing for feces and dry collection for urine. A collection network with consolidation and stabilization points was set up and the collected urine is delivered to 4 farms that fertilize 200 hectares.

    Funding from the Agence de l'eau and the Agence de l'environnement et de la maîtrise de l'énergie (Ademe, now renamed the Agence de la transition écologique) was introduced as part of a circular economy tax incentive scheme. The selective collection is done on the basis of a food payment, which is redistributed to the most precarious.

What can emerge from an informed imagination

These narratives also have the interest of highlighting three forms of emergence that allow for a better identification of the levers of a prospective socio-ecological transition.

Change often starts with local initiatives of mobilized and informed people, which spread by capillarity, and/or because they are supported by regulatory, economic and organizational devices that are more or less incentive-based.

Bref, you have to read this thesis. With this, everything should end well for the rhubarb and the hedgehog!"

Image source: Walkerssk from Pixabay.

To be read:

Fabien Esculier, The food/excretion system of urban territories: regimes and socio-ecological transitions, Sciences et Techniques de l'Environnement, Paris Est, 2018.

Thesis available at:


Émilie Hache, "What we value ":

"Urine, the new green gold? ":

See more articles by this author


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