It is a huge sewage treatment plant, as there are in all the big cities of Europe. Except that this one, positioned at the end of the Barcelona airport runways which run along the Mediterranean, very close to the mouth of the Llobregat river, is saving the inhabitants from the threatening water shortage. His particuliarity ? It recycles almost all (95%) of the wastewater collected by the sewerage networks. A precious tool, at a time when Spain is sticking out its tongue like never before, exhausted from the heat and thirsty.
In July, the Iberian Peninsula suffered two intense heat waves in quick succession, with a thermometer at 44°C in Andalusia, which aggravated the drought observed over three consecutive years. In Catalonia, it has hardly rained since the winter of 2022, and it is feared that the phenomenon will become structural. Despite some timid showers that occurred in the Pyrenean foothills in June, the dams that usually feed the Barcelona pipelines are two-thirds empty.
Reusable water to preserve drinking water
The Baix Llobregat plant is managed by the French operator Veolia. It is the largest water reuse unit in the country. Instead of being returned to the natural environment after conventional treatment, its effluents undergo a second, more advanced treatment: “Accelerated regeneration by coagulation, settling, microfiltration, UV treatment and finally reverse osmosis, a process consisting, at low pressure, in forcing water molecules to cross extremely fine membranes to rid them of the last impurities”, indicates Manuel Cermeron, Managing Director of Veolia Spain. This cutting-edge technology is essential because over the years new pollutants have been detected in wastewater: pesticides, drug residues, endocrine disruptors, etc.
Every day, the Catalan factory produces more than 300,000 cubic meters of “reusable” water. Not exactly drinkable, therefore, but allowing multiple uses, such as irrigation of market gardening, watering green spaces or washing sidewalks. Most of this water is actually sent by a large pipe towards the mountain, 15 kilometers away, upstream from Sant Joan Despi, the locality where one of the main drinking water production plants in Barcelona is located. “We are thus able to increase the flow of the river by 50%. Clearly, the water that we recycle allows this plant to operate at full speed, despite the drought”, specifies Estelle Brachlianoff, Chief Executive Officer of Veolia.
A protective barrier for groundwater
The wastewater treatment plant has another virtue: the water it recycles is also used to protect the groundwater in which the urban area pumps to meet the needs of its 5 million inhabitants. Along the coast, 15 wells 70 meters deep have been dug. Part of the recycled water is injected there, to recharge the aquifer and form, underground, a barrier of fresh water which prevents the intrusion of seawater.
At the forefront of global warming on the Old Continent, the Iberian kingdom is 75% in the process of desertification. In May, Teresa Ribera, Minister for Ecological Transition in the outgoing government of socialist Pedro Sanchez, announced an emergency plan of 2 billion euros. She notably underlined that “10% of wastewater” was already reused in the country, and that the objective was to increase this proportion “to 20% in 2027”.
The 5th most advanced country in the world in recycling
Currently, in Catalonia, a third of tap water comes from recycling. Further south on the Mediterranean coast, others do even better. In Tarragona, recycling allows more than 30 petrochemical companies to cope with seasonal water shortages. In the autonomous community of Valencia, the city of Alicante has a recycling rate of 72%, and hopes to reach 100% in the near future. In Murcia, a region of intensive agriculture despite an ultra-dry climate, 95% of wastewater is recycled for irrigation.
In installed capacity, we say at Veolia, Spain is already the fifth country in the world in this area, behind Israel, which recycles 89%, or Singapore (40%). “France, it recycles less than 1% of its wastewater, while a city like Lyon will experience the climate of Barcelona within fifteen years”, is surprised Estelle Brachlianoff, who deplores the slowness of the legislator to push this technology. For health reasons, French law prohibits the reuse of so-called gray domestic water, that which drains from kitchens and bathrooms. As a result, toilet flushes and washing machines run on drinking water, as do machines that clean the roads.
Spain was a pioneer by starting to adapt its regulations in 1986. “However, it took twelve years to see a concretization. It was the golf courses that were the first to switch to recycled water, near Alicante but also in Catalonia, around Barcelona and on the Costa Brava”, recalls Manuel Cermeron. A decade later, in 2007, a specific law was finally adopted to give a real legal framework to the recycling of wastewater, a law which was updated in April 2023 to align with the European standard.
France is still dragging its feet
Twenty-five years late, France will get started, slowly. Unveiled at the end of March, Emmanuel Macron’s Water plan plans to encourage the reuse of wastewater. But there are still many obstacles. In a report on water management published on July 17, the Court of Auditors finds that this track is “expensive”, that it “comes up against health considerations” and that its potential is “reduced”. According to Veolia, with an administrative simplification, France could however recycle “without real additional cost” 10% of its urban water and 25% of its industrial water within five years.
Desalination, another promising avenue
To meet the demand for drinking water, the Spanish state does not rely solely on recycling. It is preparing to finance three large seawater desalination plants, one in Catalonia and two in Andalusia. What relieve the two existing plants in Barcelona, including that of Baix Llobregat, adjoining the recycling plant of Veolia. Largest in Europe, it was inaugurated in 2009, a year after the great drought which had forced the city to bring water from Marseille by boat, a trauma that no one has forgotten. Since the summer of 2022, it has been running at 100% of its capacity, 2,000 liters per second, enough to meet 20% of the needs of the metropolitan area. Unheard of over such a long period.
Pumped into the Mediterranean, 2.2 kilometers from the shore and 30 meters deep, the seawater, conveyed by a long pipe, is decanted then filtered, before also undergoing reverse osmosis, under high pressure this time. 100 liters of salt water provide 45 liters of fresh water. The rest, a brine, is sent back to sea. “Previously, to reduce our energy bill, the Achilles heel of desalination, we recover the energy accumulated by this brine during the reverse osmosis stage, which allows us to save 55% on our electricity bill”, specifies on the spot Laia Hernandez, spokesperson for the public authority responsible for the site.
Waste in sight
From the point of view of supply, Catalonia considers itself capable of holding out all summer. “Unless there is a storm at the end of August, the state of emergency should not be declared, indicates Anna Barnadas, regional director of climate action. However, we must work on demand in order to avoid waste, without penalizing the different categories of consumers: residents, tourists or businesses.
The new socialist mayor of Barcelona, Jaume Collboni, elected at the end of June, has promised to launch an awareness campaign to reduce consumption. He estimates that by fighting against leaks in the network it could decrease by 100,000 cubic meters per year. Currently, a Spaniard consumes 120 liters of water per day on average. Not so bad, when you know that a Frenchman needs 149 liters.