Amid scorching heat waves, a historic drought has rocked France since late July, causing water shortages in large parts of the country. Climate change is sure to make these droughts frequent, if not the new normal – so scientists are looking for technological solutions to find a way around the problem.
France’s worst drought since 1959 has drained water tables and dramatically reduced the flow of water in the country’s rivers. The French government had to restrict the unnecessary use of water. About 100 towns are running out of regular water supplies due to drought, necessitating water tanker deliveries and bottled water distributions.
This predicament has prompted many to consider new ways of providing water, such as reusing wastewater and desalinating seawater. These measures have already been put in place in some countries – but face regulatory hurdles and environmental concerns in France.
“France in particular, and EU member states in general, need to catch up with other countries when it comes to recycling wastewater,” said Julie Mendret, a water systems expert at the University of Montpellier. “Currently, less than 1% of treated water in France is reused. This figure is 8% in Italy and 14% in Spain. This is a far cry from the situation in some countries where a large portion of wastewater is recycled back into the system, including Gulf states like the United Arab Emirates, Kuwait and Qatar. Israel is a real pioneer in the field – (it) recycles 80% of its wastewater.
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Traditionally, the water that ends up in French taps is extracted from groundwater and then purified. After use, the water is treated in treatment plants before being discharged into the waterways. But if it is recycled, it will go straight back into the pipes to homes and businesses instead of back into the waterways.
France recycles 19,000 cubic meters of wastewater every day to irrigate crops and water golf courses. “We could extend this use to cleaning roads or watering green spaces,” Mendret said. “Indeed, why not go further and produce drinking water by recycling water?
In Vendee department (administrative unit) on the French Atlantic coast, the Jourdain project will soon be experimenting with this solution. Instead of being discharged into the sea, part of the water from the Sables-d’Olonne wastewater treatment plant will be recovered and treated before being reintroduced into the drinking water supply network. “It will be the first time that such a process will be used in Europe, after it has already been implemented in Singapore and Namibia,” Mendret stressed.
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France is held back by “overly strict regulations”, as well as other obstacles to the approval of projects at the local level. Nevertheless, the French government expanded the use of recycled water in March, allowing its use in firefighting and increasing reserves of parched groundwater. At EU level, Member States have agreed in principle to increase the use of recycled water.
“We won’t be able to recycle all the water,” Mendret said. “Sometimes it is necessary to release it to maintain the flow of nearby rivers and to protect biodiversity. You cannot solve one problem by creating another. However, it remains a very interesting option, especially for coastal areas where wastewater is often discharged into the sea. It is fresh water that has just been lost.
Desalination, boosting the use of rainwater
Widespread use of rainwater is also going to be needed, said Fabienne Trolard, research director at France’s National Research Institute for Agriculture and the Environment. “In France, the overwhelming majority of the water we use is drinkable; we can only use rainwater to water our plants,” Trolard said. “But in Belgium and Germany, households have long used dual-circuit systems, where drinking water is only there for drinking and showering and water for other uses comes in the form of tap water. rain, stored in individual tanks.”
If France implemented such a system, continues Trolard, “we could even reuse this gray [non-potable] water several times; they do it three or four times in some of our European neighbors and five or six times in Israel”.
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Two small towns, Rogliano in Corsica and the island of Groix in Brittany, are experimenting with another solution to drought: the desalination of seawater.
Like wastewater recycling, this technique is already widely used abroad. There are more than 17,000 desalination plants in the world, according to the International Desalination Association, which brings together scientists, industrialists and NGOs in favor of using the technique. In total, more than 300 million people depend on desalination for their water needs.
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“The main users of desalination are Saudi Arabia and Israel, but Maghreb countries have also invested heavily in it,” Trolard said. “It’s not hard to see why they’re doing it: these are arid countries where fresh water is scarce – and it’s one of the few solutions.”
In Jordan, a plant should be installed on the shores of the Red Sea in 2026, and should produce between 250 and 300 million cubic meters of drinking water per year, or 750 million liters of water per day.
However, desalination has its drawbacks. “These factories consume a lot of energy and are therefore not very economical,” said Trolard. “Above all, desalination produces brine that we don’t know what to do with.
On average, each liter of fresh water produced by desalination produces 1.5 liters of saline sludge, which is usually discharged into the ocean, disrupting ecosystems.
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A range of small-scale solutions are used elsewhere in the world. Chile, for example, harvests fog water every year. This technique has existed since pre-Columbian times and is very simple: Very tightly meshed nets are installed on foggy days. The droplets cling to the nets and then flow into containers. This is an inexpensive and environmentally friendly process, but of course only works in very specific weather conditions.
In the same vein, Laurent Royon, a researcher at the Interdisciplinary Laboratory for Future Energies in Paris, is studying the possibility of recovering dewdrops to use them as fresh water. “This technique could be used anywhere, even in deserts, where it’s actually quite cold at night,” Royon said, referring to ongoing experiments in India, Morocco and Benin. However, this technique is not very productive, with barely 0.5 liters per cubic meter harvested each night.
Some scientists want to develop new methods of supplying fresh water instead of adopting those already in use.
But some of these approaches are ultimately counterproductive, such as cloud seeding, which would trigger rain on command. Studied since the 1960s, particularly in China, the idea is to exploit the water present in the Earth’s atmosphere in the form of vapor in the clouds. Only 10-15% of the water in these clouds ends up falling as rain. By sending aerosols via small rockets or fireworks, for example, researchers are trying to increase the amount of rain. Not only is the effectiveness of this technique debated, but climate change could cause chain reactions elsewhere on the planet that would be difficult to anticipate.
Another unusual idea is to move icebergs, which are made up of fresh water. For nearly four decades, French engineer Georges Mougin has been researching ways to move these colossal blocks of ice to countries plagued by drought. In 2010, his experiments concluded that it would take five months and 4,000 tonnes of oil to transport an iceberg from Canada to the Spanish Canary Islands. This lunar idea therefore comes with an array of technological, ecological and financial headaches.
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This article is translated from the original in French.