Desalination of sea water in Madeira

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While the Algarve is discussing the first desalination plant on the Portuguese mainland, in Porto Santo the system has been in place for 40 years and supplies the entire island.

In the late 1970s, the Madeira Archipelago pioneered a system that would meet the region’s needs for the next 40 years. Inaugurated in 1980, the Porto Santo desalination plant was an investment made by the regional government of Madeira due to the water shortage in Porto Santo – which worsened when the population grew and the first tourists arrived. began to arrive on the island.

Located in Vila Baleira, the Porto Santo desalination plant was one of five industrial units of its type in the world equipped with reverse osmosis technology. Currently, all the water that reaches consumers and agriculture comes from there. Indeed, it is the only source of drinking water used for the public supply of this island.

In 2019, the plant had a production capacity of around 6,500 m³ per day, which is enough to meet the needs of 5,000 permanent inhabitants which reach almost 20,000 during the summer months.

According to Águas da Madeira, “it was also the first to use an energy recovery system with a Pelton turbine, which became the technological standard for about 20 years. This important change reduced energy waste by 35 to 40% and has contributed to the deployment of this technology worldwide”.

advanced system

Nuno Pereira, administrator of Madeira’s Water and Waste Production, the company responsible for the desalination plant, told the Público newspaper that “for 100 liters of salt water that enters the system, 45 liters of drinking water come out” .

To this end, some desalination techniques can be used in this type of mechanism, but the one chosen by Madeira was reverse osmosis, which is a technology that removes most contaminants from water by pushing water under pressure to through a semi-permeable membrane.

According to Público, at that time most desalination plants in the world used thermal methods to remove salt from the water, which required greater energy consumption and since Porto Santo did not have enough capacity. energy for this, the solution was to use the pioneer process of reverse osmosis.

In fact, the Porto Santo desalination plant was one of the first reverse osmosis seawater desalination plants built in the world and the first in Europe. Currently, the entire process has a total consumption of 3.5 kW/m³.

Additionally, “the water that is rejected by the desalination process (which accounts for about 55 to 60 percent) is returned to the sea with about twice the concentration of mineral salts in the water.”

Good water quality

Despite the source of the water, its quality is not less than five stars, according to the company. “The water is of excellent quality”, they assure.

Prior to the construction of this desalination plant, Porto Santo suffered from serious water shortages, with natural water not being sufficient to meet the needs of the population in terms of quantity and quality. Low water levels from natural springs are a result of the island’s characteristics, where rainfall is 75% less than on Madeira Island.

While at the time it was urgent to act, today the water produced in this plant is more than enough to meet all needs. Without it, they admit, it would be impossible to grow economically and attract tourists, as Porto Santo has done in recent years.

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