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Afewdays ago, I was quietly enjoying some delicious chocolates by the fire. Carelessly, I played with the red ribbon that surrounded the box, before noticing the label that had been affixed to it. The graphics may have been poorly chosen, but the chocolate was still of undeniable quality. I smiled in spite of myself, « This chocolate supports poop producers. » As I let the ganache melt on my tongue, I let that phrase echo in my mind, thinking of Victor Hugo.

« For you are dust, and to dust you shall return.« 
Genesis 3:19.

If we agree that our body is part of the great cycle of Life, that our death will make the life of other organisms, our modesty pushes us all the same to lock our empty flesh in hollow boxes, at the bottom of deep holes(1). Once dead, we are only a « waste », certainly tinged with a great symbolism, but a waste all the same. We bury our dead so that we don’t see what happens to their bodies, then we cover them with stones and flowers. To be sure.

Even if the symbolism is perhaps less profound, we do the same every time we go  » to the little corner « . With an ego flouting all eco, we chase away with pure water what our life does not need anymore, evacuating as fast as possible from our sight these taboo productions. The lid of the bowl is lowered, in a smell of flowers diffused by a potpourri reminding the smell of the cemetery and we leave, forgetting instantly what we have just parted (and sometimes, also, the light on).

Normal human stool weighs 150 to 200 grams per day. Multiplied by just over 7.55 billion people on the planet, humanity produces its share of 1,510,000 tons of fecal matter every day (that’s almost 17.5 tons per second). And that’s not counting the urine! But of all this, no dust. We simply do not want it in our life cycle. And yet…

 » This results in two things: impoverished land and stinking water. Hunger coming out of the furrow and disease coming out of the river. « 
Victor Hugo, Les Misérables, 1862.

In the early 19th century, sources of fertilizer were limited. The organic residues, and in particular the excrements, are recovered in the city to fertilize the fields of the periphery. In Brussels, the undertaking is carried out by the Ferme des Boues, a sector of the road cleaning service. Emptying of communal latrines and cesspools, the output is conducted north of the pentagon, along the canal. After partial evaporation of the excess water, the  » manure « (2) — human manure — is sold to local farmers, closing the loop.

Between 1831 and 1846, the population of Brussels increased from 140,000 to 232,000. With the demographic densification comes also the diseases. The middle of the 19th century saw successive waves of cholera and several epidemics in Brussels. Since Vibrio cholerae contamination occurs mainly through water contaminated with infected feces, hygiene measures are gradually becoming necessary. A major transformation of the management of fecal matter then begins.

As early as 1857, the  » all-to-the-sewer  » system was promoted, with the rainwater drainage network becoming a real sewage system. The sewers flow into the Senne, which carries away any source of contagion… and at the same time breaks the law of restitution. With the advent of synthetic fertilizers, the question did not last long and the part of human dejecta in the nutrient cycle was gradually forgotten: feces are now only pollution. The state of the Senne is denounced by the local authorities downstream of Brussels but, after many palavers leading to the vaulting of the river, a special commission of the city council declares in 1882  » that one of the roles assigned in nature to the watercourses is precisely to clean up their banks by carrying away all the putrescible matters which result from it. […]

The City of Brussels is simply using a natural right by discharging its sewage into the Senne « . Thus for 120 years, the Senne will remain the sewer of the capital.

Brussels now has two sewage treatment plants. The South station was inaugurated in 2000, after threats from Europe to initiate its construction, and it has just been massively renovated to meet European standards. It is responsible for approximately 25% of the treated water of the agglomeration. The North station, opened in 2007, treats the remaining 75%. 60 million m³ of drinking water are consumed each year in Brussels. 98% of wastewater is sewered. Mixed with rainwater and the sewage from the Maelbeek and other streams, 128 million m³ of wastewater are treated each year in the two Brussels wastewater treatment plants. However, this only represents between 90 and 95% of the sewage, the remainder always being discharged through the 14 main sewer overflow points into the Senne and the canal.

The sewage sludge produced, mixing industrial and household discharges with organic matter, contains heavy metals, toxic substances and persistent pharmaceutical pollutants. As a result, following the mixing of nutrients with the city’s pollution, the resulting sludge is unfit for any agricultural use and, from the South plant, 6 to 10 containers of sludge are sent by truck each day for incineration in


 » A big city is the most powerful stercorary. Using the city to smoke the plain would be a sure success. If our gold is manure, then our manure is gold. What do we do with this manure gold? It is swept to the abyss. « 
Victor Hugo, Les Misérables, 1862.

Animal organic matter, mixed with a vegetable substrate, has always been used as manure to fertilize the fields, nourishing the soil and fertilizing the crops. The use of human nutrients — with the exception of the last century of Western history — has always been part of this. The application of untreated feces is not without risk (nor without odor), both for the farmer and the consumer(3). Cholera is a good demonstration of this. But if we know today that the disease is due to a bacterium, we also know that it never survives more than one month outside a human host. Nothing that can’t be overcome by composting.

Not the composting of sewage sludge, however, as the latter still poses the problem of pollution with heavy metals, toxic substances and pharmaceutical residues. The key is the  » bio-controlled dry toilet  » that puts an end to the aberration of dejecta in drinking water. Any farmer can demonstrate how good manure consists of his animals’ excrement (feces and urine mixed together) in a dry plant litter, with a ratio of one to three. Humans are just like any other animal: dry toilets do not use a flush but a carbon-rich plant litter — sawdust, hay, dead leaves, etc. — to cover any deposits and absorb liquids. The collected material can then be composted.

Anything that comes from a plant or animal would naturally compost in nature and will decompose all the better in a compost. Citrus fruits, meat or fat are just as perishable as feces and toilet paper, cotton tampons or the corpse of the old hamster, although eggshells, bones and branches will take longer to degrade. With sufficient moisture, oxygen trapped in the interstices of the substrate and a good C/N ratio between carbon (litter) and nitrogen (output)(4), most of the organic matter will be transformed into humus in less than a year. In the case of batch composting of large volumes, undertaken for example by communities, the main phases of decomposition can be carried out in a few months.

 » All the human and animal fertilizer the world loses, returned to the land instead of being thrown into the water, would be enough to feed the world. « 
Victor Hugo, Les Misérables, 1862.

The heterogeneity of regulations and the social taboo that the subject represents reflect a generalized coprophobia. In many countries, the composting of biosolids is highly regulated and their use in agriculture largely prohibited. In Europe, only urine that has been separated from faeces at source can be used, and only in conventional agriculture. However, domestic composting of human excrement is not legislated in Belgium, falling under the jurisdiction of the rules of good neighborliness of the civil code (article 544): one cannot prevent his neighbor from enjoying and disposing of his property by spreading nauseating odors. A well-managed compost doesn’t smell any more than an undergrowth in autumn, so those who have a garden are free to compost their  » manure « (5).

What about the dejecta of the majority of the urban population or those who do not want to manage a compost? If the 3,000 million tons of organic matter that all of humanity would produce if it universally used dry toilets were harvested, the world’s 1.4 billion hectares of arable land could be covered with more than two tons of compost per hectare each year.

While composting companies exist (mainly in Asia and Haiti(6)), biosolids are generally managed as waste, transformed into construction materials, biofuels or fuels. This management reduces aquifer pollution, but still turns its back on natural nutrient cycling. And if fertilization projects like those in Egypt allow desert areas to be transformed into wooded forests, how much arable land is excluded from the cycle in return?

 » Do you know what these heaps of garbage on the corner of the bollards, these heaps of mud bounced in the streets at night, these awful barrels of the roadway, these fetid flows of underground mire that the pavement hides from you? It’s meadow in bloom, it’s green grass, it’s thyme and sage, it’s game, it’s cattle, it’s the contented roar of the great oxen in the evening, it’s fragrant hay, it’s golden wheat, it’s bread on your table, it’s warm blood in your veins, it’s health, it’s joy, it’s life. « 
Victor Hugo, Les Misérables, 1862.

The naturalism(7) western forgot the place of the man in the nature. By excluding human organic matter from the nutrient cycle for sanitary reasons before the understanding of how composting works — Pasteur was writing his first publications at the same time as the work on the vaulting of the Senne river was beginning in Brussels — history has taken the path of a social and multi-technical lock-in: social taboo, sewage infrastructure, (non) management of water and later of sewage sludge, but also sanitary laws and the synthetic fertilizer industry, etc.

However, another paradigm is possible. Fertilizing and pathogenic, the double nature of the fecal matter is easily reduced to a healthy fertilizing action by the composting of the manure, all the more when it is done in a collective way, allowing a natural pasteurization of the organic matter and an adequate sanitary control. Moreover, the company pays for itself: the price of removing the output, transporting it and treating it (taking into account its final market value) is less than 1/5th of the cost of transporting the wastewater and treating it in a wastewater treatment plant (not counting the management of the resulting sludge).

There is no way to escape it: the cycle of life does not produce waste, the excrement of one organism is the food of another. Our Earth is unique and the only way to live on it sustainably is by being part of the biosphere cycle, not beside it. Isn’t the very first principle of agroecology to  » allow recycling of biomass, optimize nutrient availability and balance nutrient flow « ? The question, highly interdisciplinary and social, should have been treated a thousand times. How can agroecology be claimed in a more central way than around the subject of human dejecta? Without these nutrients, there is no resilience, sustainability or self-sufficiency. No complete agri-food system. How can we support a short circuit that circulates only in one direction, how can we aspire to a circular economy without closing the loop? How to build a sustainable food agriculture without including it in the natural cycle of the biosphere. It is high time to think about the  » total ecosystem « (8) and finally close the loop. Go to the end of the logic. Yet no one talks about it. Do we wait until we’re up to our necks in shit before taking an interest?

Noé Vandevoorde

Notes et références
Cet article a été rédigé dans le cadre du cours théories et gestion des transitions agroécologiques. où les étudiants du master en agroécologie (ULg-ULB) ont rédigé chacun un essai, en guise de clôture de leur quadrimestre « Agroécologie et sciences sociales » au Campus d’Arlon de l’ULg. Autres sources:   
  1. On notera tout de même la mise en place d’humusation, un projet alternatif autorisé pour expérimentation en Belgique depuis aout dernier. Métamorphose. « Métamorphose pour mourir … puis donner la vie ! ». Fondation d’Utilité Publique, 2018 [En ligne :].
  2. L’expression est due à Joseph Jenkins dans son livre The Humanure Handbook. A Guide to Composting Human Manure. Inc., 3rd edition, 2005. [En ligne :].
  3. Des risques existent également pour les cultures, la forte concentration en azote des boues brûlant les végétaux et l’utilisation directe des excréments pouvant alors s’avérer contre-productive.
  4. L’équilibre nutritionnel des microorganismes est situé à un rapport C/N d’environ 25, les fèces pures ayant un rapport entre 5 et 10.
  5. À ce sujet, lire l’excellent ouvrage de Joseph Jenkins « The Humanure Handbook », traduit en français aux éditions Écosociété : « Le petit livre du fumain ». Cela n’exonère pas du raccordement à l’égout lorsqu’il existe, pour l’évacuation des eaux grises. Dans le cas où l’égout n’existe pas, il est obligatoire d’installer un système d’épuration autonome, qui peut être réduit de 30% en présence de toilette sèche.
  6. Voir par exemple l’ong Sustainable Organic Integrated Livelihoods (soil).
  7. Au sens de Philippe Descola, voir par exemple
  8. Clin d’œil à David Western, voir par exemple
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