While the level of the reservoirs continues to drop (and with a large part of the underground reserves in poor condition), the country is increasingly looking towards two other ways of obtaining water resources. 9% of the drinking water that comes out of the country’s taps already comes from the sea and a similar percentage of the wastewater from the toilets is treated with a quality that allows even lettuce to be eaten, according to the data. of the Spanish Association of Desalination and Reuse (AEDyR). Spain not only leads the European ranking for the number of large dams built, but also for desalination and reuse of reclaimed water (of a higher quality than conventional treated water), resources that are more expensive, but have the advantage that they do not decrease with drought. .
On the contrary, the forecast is that they will continue to gain prominence in the coming years. If the expansion of some of the large desalination plants was already planned (such as the one in Torrevieja, in Alicante, or the one in Águilas, in Murcia), royal decree law 4/2023 against drought approved last week by the Government with aid to Farmers also includes 440 million euros for the construction of three new desalination plants (in Blanes, Girona; in Almería and Malaga), 600 million to install solar parks in desalination plants already in operation, 180 million for improvements in two treatment plants in Alicante and other measures so that the reuse of reclaimed water grows by 150% between now and 2027, going from the current 400 hm³ to nearly 1,000 hm³.
Torrevieja desalination plant, in Alicante, the largest in Spain. ALFONSO DURAN
Far ahead in the development of these technologies, there are parts of the country – on the peninsular coast and the islands – where these other waters have been strategic for some time. As Domingo Zarzo, president of AEDyR, points out, “if we didn’t have desalination plants, right now there would be supply restrictions on the entire Mediterranean coast.” As regards the use of wastewater, the case of Murcia, which reuses 98% of what comes out of its treatment plants (compared to an average of 9% in Spain or 5% in Europe), or the Valencian Community, the European region with the largest volume of reused water (271.54 hm³).
These resources can exceed the quality of conventional water that is sometimes used in the country and represent an unquestionable relief for arid areas, especially at a critical time like the present. However, some experts warn of the danger of increasing the supply of water resources without also fixing the holes in the pipes of the system. In the opinion of Julia Martínez, technical director of the Fundación Nueva Cultura del Agua, “the key to adapting to climate change is to move from supply policies to demand management, which implies reducing the need for water in all uses, in human supply, in industries and, especially, in irrigation, which is currently drinking 80% of the water in Spain”. In addition, this biologist argues that reuse does not actually generate any new resource in the system as a whole, because if it is not reused, most of the water from the treatment plants is dumped into rivers to be diluted. She considers that it does imply a profit when the discharge from a treatment plant into the sea is avoided, but not when the treated water is stopped from being discharged into a river from which the same cubic meters will continue to be extracted further down the line.
“If we send out the message that we are capable of generating an additional resource and what it does is drive the demands out of control, what we are doing is sending out the exact signal that we did not want,” also highlights Gonzalo Delacámara, director of the Center for Water and Climate Adaptation from IE University, which believes that the increase in the availability of desalinated and reused water should be accompanied by a reduction in pressure on overexploited aquifers and natural ecosystems.
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General view of the osmosis plant where salt is separated from seawater in the Torrevieja desalination plant.ALFONSO DURAN
After the strong boost given by the central government between 2004 and 2011, the current desalination capacity in Spain is close to five million cubic meters per day, a potential only surpassed in the world by Saudi Arabia, other countries of the Persian Gulf and USA. According to AEDyR data, in the country there are more than 770 desalination plants with the capacity to generate more than 100 m³/day and one hundred of them with more than 10,000 m³/day. The largest plant is that of Torrevieja (240,000 m³/day), managed by the state company Acuamed, which is currently operating at full capacity to cover the requests processed by irrigators. Last April, this facility produced 6.7 hm³.
As Zarzo emphasizes, of all the desalinated water right now in the country, 21% is used for agriculture, which is “a rarity” in the rest of the world (where barely 3% is used to irrigate crops). “Many people come from Australia, Chile or other countries to see here desalination facilities for agriculture and crops irrigated with desalinated water, we are an example worldwide”, emphasizes the president of AEDyR, who explains that the barrier is no longer technological ( because although desalinated water is problematic because it contains boron —a nutrient that can be toxic for some crops—, this ensures that the large Acuamed plants are capable of removing it), but also economically, as it depends on the crops being sufficiently profitable to pay for this more expensive water.
Although prices can vary greatly, according to Delacámara, a cubic meter of reused water can cost around 35-50 euro cents at the exit of the treatment plant and a cubic meter of desalinated water around 90 cents (not counting transport to the area to irrigate), while pumping a cubic meter of conventional water in a plot can only cost 10 cents. “Sometimes irrigators prefer to pay less and irrigate their lemons or lettuces with what they pump from an overexploited aquifer, even if it has high salinity levels or may be contaminated by nitrates,” says this economist, who considers that incentives are needed to promote make irrigation more sustainable. “If what you want is not just to solve the problem in the short term, but to guarantee water security in the long term in a context of climate adaptation, you need a price system that allows more expensive options to enter the market, as did with renewables to displace fossil fuels”, he argues. “Provided, of course, that they are really more sustainable, if it is a desalination plant that does not treat its brine [residuo salino generado por estas instalaciones]So it’s better not to use it.
Biological treatment area of the Alguazas WWTP, one of the hundred purification plants in Murcia.
In the case of reuse, the Spanish Association for Water Supply and Sanitation (AEAS) estimates that 61.9% of reclaimed water is used in agriculture, 18% in gardens and leisure areas, 2% in industry, sewage cleaning and street washing, and 0.82% in aquifer recharge. Current technology is already capable of purifying toilet water with a quality that is also sufficient to drink. However, Spanish legislation does not allow it at the moment, which does happen in places like Singapore.
In Murcia, almost all of its 121 hm³ reused per year are dedicated to agriculture. In fact, 15% of all the water used to irrigate in this community comes from the treatment plants, according to Esamur, the public company in charge of sanitation in the region. As Pedro Simón, its technical director, explains, although today almost all the urban water in the country is purified, that which is going to be reused must undergo additional treatment to also eliminate pathogens. This has higher costs than normal purification, which, as occurs in the Valencian Community or Catalonia, is covered by a sanitation fee paid by all citizens. The particularity of Murcia is that this higher quality treated water is now free for farmers, something that may change due to the entry into force in June of a new European regulation that further increases the requirements (and costs) for reuse. “For me, the main problem is trust,” explains Simón about the misgivings that still exist about the use of a resource derived from wastewater. However, as the technical director of Esamur emphasizes, well-purified water from a conventional plant that is discharged into rivers can have between 10,000 and 100,000 Escherichia coli units per 100 milliliters, but the water that is reused right now in Murcia does not. It can exceed 100 units and with the new regulations it has to go down to 10.
Aerial view of the tertiary ponds of the Alguazas treatment plant.
“This is a source of water that can be very beneficial and that can be used to protect aquifers, of course, at the moment in which we are living, we cannot disdain any,” says Simón, who thinks that it would already be perfectly viable to use it for the supply of cities if the law allows it. “The water could be regenerated over and over again, it would be like a closed circuit, which is what astronauts have. Maybe in the future it will have to be done, today it is better to reuse it for other less compromised uses so that it is less expensive”, he comments.
Before drinking this water, for Pascual Fernández, president of AEAS, there is still a lot of room to increase its reuse in the country, in other territories and in other sectors. “There is a lot of potential for development in the industry, many industries can function perfectly with recycled water and with this, in the end, what we are doing is taking pressure off the whole system”, he indicates.
The reservoirs, half empty
The level of the reservoirs in Spain fell again this week and the water reserves are currently at 27,033 cubic hectometres (hm³), well below the 38,356 hm³ average of the last 10 years at this time of year. This does not happen because works of this type have been destroyed for storage purposes (as a hoax circulating on the internet affirms), but because of the prolonged scarcity of rain and the greater evaporation due to the heat, which reduce the availability of a resource that is already subdued for good. yes in some areas under great pressure. With more than a thousand, Spain continues to be the country with the largest dams in Europe, and has even expanded some to increase their storage capacity; The problem is that many of these infrastructures are now half or almost empty: according to the most up-to-date data from the Ministry for Ecological Transition, at the moment the reservoirs are on average at 48.2% of their capacity. A situation that is expected to get worse in the long run due to global warming.
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