In the jargon, we speak of “réut” for “reuse of treated wastewater.
The idea is to provide additional treatments to the water that comes out of the treatment plants so that it can be reused, rather than discharging it into the river.
In Israel, more than 90% of wastewater is reused in this way.
In Spain, it is 14%.
In France, we are at less than 1%.
But the historic drought of 2022 is prompting a reconsideration of this wastewater.
A plan to be announced this Wednesday morning by Christophe Béchu should go in this direction, allowing France to catch up.
Last summer, when the water restrictions were raining, the Bressuire golf course, in the Deux-Sèvres, displayed very green greens.
No miracle: it had to be watered.
But without drawing from the natural environment as 81% of the 740 French golf courses do, or pumping from the public drinking water network (10%).
On this site, since June, the courses have been watered in large part* with water from the local wastewater treatment plant, a few hundred meters away.
In the jargon, we speak of “reus” for “reuse of treated wastewater”, explains Thierry Trotouin, director of industrial markets at Veolia Water.
In France, the acronym remains little used, as we are lagging behind on this subject.
"Less than 1% of wastewater is treated and reused compared to more than 90% in Israel", we concede to the cabinet of Christophe Béchu, Minister of Ecological Transition.
It is also 8% in Italy and 14% in Spain.
Changing the way we look at our wastewater
The historic drought of 2022, which climate change may make more common in the future, invites us to take a fresh look at our wastewater.
This Wednesday morning, Christophe Béchu should go in this direction by announcing new regulations on water.
Without saying much, his cabinet nevertheless cites two key areas in this plan: “The fight against water leaks in the pipes, a major source of waste, but also, effectively, better management of waste water”.
At Veolia, we say we are ready to accelerate.
"The technology is mature, we have been developing it for twenty years**", assures Thierry Trotouin.
Traditionally, wastewater treatment plants treat wastewater biologically and clarify it before discharging it into the natural environment.
“There are still small quantities of suspended solids in this water, explains Veolia Water's director of industrial markets.
To be able to reuse it, we filter it again and apply additional disinfection systems to it that will ensure that we eliminate all bacteria.
Finally, we add chlorine, a product that will allow us to store this water by ensuring that no bacteria return.
Watering golf courses, cleaning roads, irrigating crops...
On the Bressuire golf course, this transformation is done in a container installed on the site and connected to the wastewater treatment plant.
This is one of the “reus” projects that Veolia launched in France last June.
The group already has around thirty and is aiming for a hundred by the end of the year.
When there is enough space, these containers are installed directly in the treatment plant.
Because Veolia is the first to use this treated wastewater.
“To clean wastewater treatment plants and prepare the reagents used to treat wastewater,” explains Thierry Trotouin.
With 100 stations equipped, we should save approximately 3 million m³ of drinking water each year, equivalent to the average annual consumption of a city of 180,000 inhabitants”.
These are only internal applications, far from exhausting the entire volume of this waste water.
Clearly: there is still extra money that could provide many services outside, always with the aim of relieving the natural environment and the public drinking water network.
Irrigation of golf courses is one such application.
"Thirty structures are now connected to a system of réut", it is estimated at the French golf federation.
In the same vein, Thierry Trotouin cites the watering of sports grounds, racetracks, green spaces, but also the cleaning of roads or pipes.
"And there are those thousands of trees that local communities are planting to cool cities in the face of climate change," he continues.
They have significant water needs in the first years.
Again, treated wastewater may be fine.
Uses also in agriculture
Nor should we forget agriculture and the irrigation of certain crops in the summer.
Another use of water that tenses many French people.
Once again, the reut can be useful.
“Especially since this treated wastewater still contains nitrogen and phosphorus, nutrients for the earth, points out Didier Guiral, from the national network “Water and aquatic environments” of France Nature Environnement (FNE).
In many cases, it is preferable that this water benefits crops and even allows farmers to reduce their use of synthetic fertilizers rather than being discharged into rivers.
In Auvergne, Limagne noir has already taken the plunge.
Since 1996, this collective of around fifty farmers has been using wastewater from the Clermont-Ferrand conurbation to irrigate 750 hectares of field crops.
But it is still very embryonic in France.
Nothing to do with what is happening, once again, in Israel.
To catch up, this plan on water unveiled on Wednesday should set objectives to be achieved on the "reut" as well as allocate public funding.
And simplify procedures?
The length of time it takes to examine applications is an obstacle often cited to explain the low recovery of wastewater in France.
“You have to wait twelve months, sometimes twice that for a project to be authorized and you have to put together a file for each use you want to make of this water, regrets Thierry Trotouin.
This discourages many municipalities, especially the smallest ones, from getting started.
“A difficulty also pointed out by the French golf federation.
However, Didier Guiral warns of too much relaxation of procedures.
“The danger is to open the floodgates wide on the “reut”, without looking too much at the uses that we make of it, he points out.
We would fall back into this illusion that water is an abundant resource and we would lose sight of the essential: the need to save it.
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* To water its greens, the golf course draws water from a basin on the site, supplied with rainwater.
But since June, the water treated in the container also feeds this small lake.
15,000 m3 were dumped there last summer.
** In Windhoek, the capital of Namibia, wastewater is treated in a closed loop to produce drinking water.
21,000 m3 per day.
Since 2001, this water recycling plant has been managed by a consortium which includes Veolia.