In this Toulouse laboratory, researchers imagine the toilets of the future
Through Lucie Fraissé
Published on
Since 2019, at Toulouse, researchers are working on toilets of the future. At the very serious Toulouse Biotechnology Institute (CNRS / Insa / Inra), they are considering toilets that allow stool to be separated from urine in order to transform the latter into agricultural fertilizers.
To replace chemical fertilizers
“Nothing intended us to optimize the toilets,” explains Etienne Paul, researcher within the Symbiose team which manages this project. But one of our main work objectives is to recover nitrogen and phosphorus, the use of which is decisive for agriculture: it is a crucial issue. “
The idea is therefore to replace chemical fertilizers, made from fossil fuels, used in agriculture by recovering nutrients present in urine to fertilize crops. “80% of the nitrogen that we ingest while eating comes out in the urine,” emphasizes Etienne Paul. “Recycling urine is nothing new: it’s about going back to what we did before 1900, ie recovering waste for spreading in the fields. “
Source separation
But to still benefit from the nutrients of urine, it must be separated from the stool.
“We quickly identified that it was more interesting to make a separation on the scale of the toilets and not in a wastewater treatment plant. Other researchers are working in this field, especially in northern Europe, and they are also converging on this. diagnostic.”
A technique of separation of waste “at source”, which should also make it possible to reduce the cost – including environmental – of purification.
Toilets that can be used exclusively while seated
Toulouse researchers are therefore looking at models of toilets with existing partitions. But were not convinced by what existed on the market. They then decided to invent their own model of toilet: stainless steel, with a small grid that separates stool and urine and to evacuate them by two different channels. And which is used exclusively seated.
“We tested our model at Garorock in 2019,” says Etienne Paul. By partnering with a Toulouse SME, we installed a toilet with a separator in the VIP area of the festival. »More than 600 people have tested the toilets of the future. “On one had no complaints!” We also tested it at the Cirque de Noël in Toulouse and there too the reliability was good ”.
Model with vacuum suction, as in trains
The model imagined by the researchers of the Symbiose laboratory is designed with vacuum suction, like the toilets trains and planes, which saves less water.
But also to facilitate the work of researchers to develop fertilizers. Fertilizers have also been tested in the field by INRAE with success.
Work on a ceramic prototype
Toulouse researchers are now hoping to develop a ceramic prototype of these toilets of the future, which can be used in the private sector. “The Regional Center for Innovation and Technology Transfer we met in relation to manufacturers who might be interested in the project,” explains Etienne Paul. “One of them would be interested in producing these toilets in small quantities. “Toilets which could, for example, soon be installed in an Insa building.
Soon at individuals?
But will we one day see these toilets that separate urine and stool at the source in homes? “Today certain districts are being built with this system of separation at the source of waste in the toilets, with dedicated basins,” explains Etienne Paul. This is particularly the case of the Saint-Vincent-de Paul eco-district, in Paris. Ultimately, the urine collected in this future district of 600 inhabitants should make it possible to produce 47 m3 fertilizer per year.
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