Urine-diverting dry toilets

Prototype de Low-tech with Refugees - Low-tech & Réfugiés | Catégories : Habitat, Hygiène

Low-tech with Refugees - Low-tech & Réfugiés

https://wiki.lowtechlab.org/wiki/Toilettes_s%C3%A8ches_%C3%A0_s%C3%A9paration_d%27urine/en

Dernière modification le 06/08/2024

Difficulté

Moyen

Durée

5 jour(s)

Coût

400 EUR (€)

Description

Eternal" urine-separating dry toilets, designed to compost dry matter directly under the toilet to avoid emptying. There are two main tools for achieving this: air circulation and vermicomposting.

Difficulté

Moyen

Durée

5 jour(s)

Coût

400 EUR (€)

Autres langues :

English • ‎español • ‎français • ‎العربية

Licence : Attribution (CC BY)

Introduction

This prototype is the fruit of a generous collaboration between Pierre Colombot, founder of Sanisphère, the association Low-Tech & Réfugiés and the association De Terreau et d'Embruns, which has been awarded the Low-Tech Explorer label and is the creator of this prototype.

The main features of this prototype are: the use of a recovery tarpaulin (such as a lorry or swimming pool) as a basic resource in addition to the wooden framework; urine/faeces separation; treatment of materials directly in situ by ventilation and vermicomposting of dry materials, as well as drainage of urine.

This model of urine-diverting dry toilet is designed to be adaptable to different user contexts, but its main constraint is that it needs to be installed outdoors, preferably on soil, in order to benefit from the advantages of natural ventilation and composting of faecal matter "in situ". Various options are available to best meet the needs of each context. Another major constraint is the social acceptance of urine separators, which are unknown to many people.

Note that this prototype is a summary of what we have learned and combines ideas that we found interesting. However, we are waiting for long-term feedback before we can confirm that it works 100% as intended.

Why urine-diverting dry toilets?

It goes without saying that, given the current climate issues, and in particular the increasing scarcity of drinking water, dry toilets are an obvious choice when it comes to sanitation. On average, a conventional toilet flush consumes 9 litres of drinking water each time it is used. An adult goes to the toilet approximately 4 times a day. That's equivalent to 13,000 litres of drinking water pollution per person per year. So we urgently need to rethink our habits, right down to the smallest corner.

What's more, in certain extreme contexts such as refugee camps (for which this prototype is potentially intended), water represents an even more precious resource that deserves to be safeguarded for other uses (hydration, nutrition and hygiene).

Conventional" dry toilets (without separation, known as "biolitter") are highly functional and extremely simple to design, provided you have an outdoor composting area and dry materials such as sawdust/ash or litter, added to the faeces to reduce the strong odours resulting from the urine-faeces mixture. The main disadvantage is that the faeces container has to be emptied on a regular basis, otherwise it will become heavy, have strong odours and attract flies. This makes their collective use rather cumbersome in terms of management/maintenance. They are still very practical for domestic/family use.

Urine-diverting dry toilets (or UDDTs) have the advantage of a lower operating odour, resulting in greater user acceptance, a reduced risk of fly proliferation and a reduction in pathogens through drying.

What's more, the significantly reduced weight of the receptacles is an advantage in terms of management and maintenance.

Lastly, separation facilitates the use of excreta in agriculture, since urine is sterile and does not need to be composted to be used as fertiliser.

The use of urine as a natural fertiliser requires certain precautions, however, and may be open to debate. (add discussion Raph).

Separation technology:

As far as the user/receptacle interface (the seat itself) is concerned, different hardware options are possible depending on budget, available resources and cultural context (in particular cleaning habits, with paper or water).

From the simple funnel fixed in front of the hole to prefabricated objects with triple urine/faeces/rinse water separation, the range is vast. Our model is adaptable to these different technologies. Note that the most basic technology (i.e. the one closest to the low-tech spirit) - the funnel - does not really respect the female anatomy and causes urine to leak into the part intended for dry matter.

Finally, it should be noted that this type of dry toilet requires a high level of awareness among the public who are going to use them, to ensure that they are used correctly.

The risk of errors, and therefore of malfunctioning toilets, linked to their originality, is their biggest weakness. In contexts where human pressure is high, such as refugee camps, this could represent a real problem.

The "eternal toilet", or the wager of the earthworms!

As well as separating urine from faeces, our prototype is designed to compost dry matter directly under the toilet cubicle. This avoids the time-consuming task of emptying the toilet. The challenge, of course, is to calibrate the size of the storage space according to the frequency of toilet use, so that the growth rate of the pile of dry matter (faeces + toilet paper) does not exceed its composting rate. (add the faeces reduction equation by Pierre).

Composting is made possible by a number of factors:

- la présence de lombrics, déposés à la mise en fonction des toilettes. Leur activité coprophage sera bien entendue épaulée par une diversité d'autres petits organismes vivants présents naturellement dans le sol. Le contact direct avec la terre est donc très important.

-la ventilation efficace de l'espace de stockage, rendue possible par une étanchéité à l'air la plus stricte possible, avec une unique entrée d'air basse via la lunette des toilettes et une sortie d'air haute par une cheminée.

-humidité optimale cf discussion Pierre.

Le risque de débordement et la qualité du compostage nécessiteront le contrôle régulier d'un responsable dans les premières semaines suivant l'installation. Une fois les paramètres du compostage maitrisés, l'entretien consistera comme toutes cabines de toilettes en un nettoyage fréquent de la partie utilisateur.

L'élimination des urines :

Concernant les urines, deux systèmes interchangeables sont proposés dans ce prototype.

L'évacuation de l'urine se fait par un tuyau connecté au séparateur. Afin d'éviter la charge de travail que représente l'évacuation manuelle d'un contenant d'urine, le tuyau s'enfonce directement dans le sol et relargue les urines dans le sol, à travers un drain en sable/graviers/pierres qui aura été creusé lors des fondations de la structure. Mais ce système, bien qu'avantageux sur le plan de l'entretien, n'est pas entièrement satisfaisant, et ce pour deux raisons.

D'un part nous ne pouvons pas identifier clairement si le drain va suffire pour éviter une pollution du sol et des nappes alentours. D'autre part, tirer une croix sur le potentiel fertilisant de "l'or liquide" au jardin est vraiment dommage.

Ainsi, nous proposons une option de connexion du tuyau d'évacuation des urines à un jerrican (ou autre contenant de votre choix) afin que cette possibilité puisse être offerte aux utilisateurs sans être obligatoire ni définitive.

Note d'intention :

De nombreux paramètres doivent pouvoir être optimisés voire modifiés pour permettre d'atteindre le "Graal" des toilettes éternelles ! Nous espérons que ce prototype pourra être enrichi par les expérimentations et conseils de tout un chacun. D'ors et déjà merci de vos remarques, commentaires et critiques constructives.

Une version détaillée de ce tutoriel sera disponible juste en dessous dans l'onglet "fichiers".