Sea water transformation to drinking water

Last Updated on 22/06/2021 by VdB

Sea water transformation already supplies hotels in the Algarve with drinking water.

Sea water desalination is already used in the supply of drinking water by some hotel companies in the Algarve, in some cases to reduce public consumption and save resources, in others because it is the only possible solution.

Located on a cliff framed by the Algarvian coast, the Vila Vita Parc development, in Porches, Lagoa, began the desalination of seawater in 2015 and, although the project was idealized for the watering of the green spaces of the property, it quickly expanded to other sources of water consumption.

“Initially we started working only for the irrigation system and we verified that the capture, due to the need and dimensioning of our system, allowed us to reach the lakes and at this moment we are already supplying about seven pools, only with this water capture”, explained to Lusa André Matos, quality director of Vila Vita Parc.

With a dimension of 23 hectares, more than half of which are green spaces, the administration of the luxury tourist resort has launched itself into the construction of an underground desalination station, which operates under a tennis court, without guests being aware of its existence.

“At the moment, of the 100% that we were going to pick up from the network in 2014, we’re only going to pick up around 30% for everything else: accommodation, bathing and drinking water for restaurants”, quantifies André Matos, showing his satisfaction with the levels of savings achieved.

Convinced that, in the future, water will be a consumer good with “a high economic value”, he considered that, as “responsible polluters”, they should ensure that, like the future of the next generations, “the future of the business is sustained by solid pillars” and that they respect the environment.

The desalination system installed at Vila Vita Parc allows for the capture of 24 cubic metres of sea water per hour – which represents 24,000 litres.

Per day, it has the capacity to capture 440 cubic meters (440,000 liters), which “at the end of the year can represent about 900 pools of 650 cubic meters”.

With a much smaller size, but an older use, also the entrepreneur José Vargas installed, 12 years ago, a mini sea water desalination station under his restaurant built on stakes in the Deserta island, in Faro, which as the name indicates, does not have any houses.

Here too, reverse osmosis technology is used – a process of purifying water through membranes, in which the salt water is forced to pass through the membrane, which removes the particles of salts, turning the seawater into ‘pure’ water.

“We had to resort to that solution because there was no other. As there was no mains water and no wells for drinking water, we had to resort to desalination”, the businessman, who has been operating a restaurant there for more than 30 years, told Lusa.

The system has the capacity to capture 80 liters of sea water per hour, and although the system is not always working, “at the limit would be two thousand liters in 24 hours.

According to José Vargas – who used a desalination ‘kit’ used in yachts and adapted it to the restaurant’s installation – to ‘manufacture’ one litre of drinking water five litres of seawater are needed.

“We only consume this [desalinated] water for gastronomic consumption: ice, kitchens, dishwashers. Then we use another water that we collect from a well here, which we treat with chlorine, for the black waters in the bathrooms,” he explained.

Sea water desalination is also one of the proposals contained in a plan being drawn up for Culatra, another of the barrier islands of Ria Formosa, ‘neighbour’ of the Desert, but which, unlike this one, is a kind of village: it has a school, a social centre, a health centre and even a church.

“It is a key project for the island, in terms of drinking water resources. However, it is perhaps the most expensive solution. It’s the project that will collect the biggest investment,” André Pacheco, coordinator of the Culatra 2030 – Sustainable Energy Community project, told Lusa.

Since 2009, Culatra, in the borough of Faro, has begun to be supplied by the public grid – but “there’s a huge amount of energy going into pumping drinking water” for the island, as well as pumping wastewater into treatment plants, he noted.

One of the main concerns of the desalination project being designed for the island is the destination of the waste produced, a process that, according to the oceanographer at the University of the Algarve, still requires a lot of research.

“What our aim in the Culatra 2030 project is to study how this waste, that is, a hypersaline solution contaminated with sulphites, can be used in the circular economy as a raw material for another industrial process”, he stressed.

However, for André Pacheco the problem of water shortage is not solved by desalination alone, but, above all, with “a different way” of looking at water.

“We use drinking water for lots of uses that we don’t need: we wash cars with drinking water, we wash the dishes with drinking water”, he exemplified.

Drought: Desalination can help the Algarve but “doesn’t solve all the ills.

Sea water desalination can help combat drought in the Algarve, but “it won’t solve all the ills” and “integrated solutions” must be found that adapt to each local reality, a researcher told Lusa.

Manuela Moreira da Silva, a researcher at the University of the Algarve’s Centre for Marine and Environmental Research (CIMA), agrees with the solution of obtaining water through desalination admitted by the minister of the environment, but stressed that this should not be the only solution to combat drought in the region.

“I believe that [desalination] is an option, but it won’t solve all the ills, it has to be an integrated solution with others,” the lecturer in charge of the Urban Water Cycle Master’s degree at UAlg, questioned by João Pedro Matos Fernandes, told Lusa.

In February, during a conference in Loulé, in the district of Faro, the minister of the environment and climate action defended that the lack of water in the Algarve could not be resolved by building new dams – a solution defended by the municipalities, pointing to desalination as one of the bets to be followed in the future.

Manuela Moreira da Silva considered that the Algarve is experiencing a “moment in which the key words are efficiency and behavioural change”, since the current scenario is marked by a “decrease in average rainfall” and in the “natural underground or surface resources” available in dams or groundwater.

However, he warned, “a major investment” is needed for the region to adapt to a new reality, as well as look for water sources taking into account the “geographical situation”, as the situation of “São Brás de Alportel is not similar to that of Tavira, Faro or Lagos”, he justified.

“We need to realise in what situations it makes sense to invest in desalination, aware that the systems that are used most today – reverse osmosis – imply great energy consumption”, he said, recognising that the “use of renewable energy” can reduce the cost of the process, which makes water more expensive.

The same source also warned that “another of the difficulties of desalination” is the fate that is given to the waste created by the chemical process that removes salt from sea water.

“Sea water desalination is profitable between 45 and 55 percent and produces a large quantity of concentrate – a hypersaline solution – which, besides having a lot of salt, still has a set of chemical products that must be considered and have a great environmental impact,” he warned.

The researcher pointed to the example of the island of Culatra – a residential nucleus of the Ria Formosa barrier islands belonging to the borough of Faro – as a place where “desalination is already being considered” as part of a project to make it a “self-sustaining” island, and recognised that this process “could be a very interesting complementary solution”.

However, he admitted that “the best solution today, for half a dozen years, may not be the best”, giving as an example the construction of a dam in Foupana, in the Eastern Algarve, which has been demanded for years by mayors and farmers.

“[The dam] should have been built 20 years ago. With the data from 20 years ago, it was supposed to go ahead with construction, but today I have many doubts about this, because reality has changed completely”, he argued.

Instead of new dams, the researcher points to another possible solution for cities, which are confronted by “the effect of climate change” with “increasingly frequent extreme precipitation phenomena” and can “adapt so that, at these peaks of precipitation, they can retain water in reservoirs located close to the places where it will be needed”.

All solutions should be studied to “save energy, water and contribute to carbon neutrality”, said the UAlg researcher, considering that this is a “big challenge”, and that it involves “much more than building dams”.



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