A new Reverse Osmosis (RO) plant in the Aeolian Islands desalinates seawater quicker, more efficiently and at a lower cost than previously, providing tourists and natives with an abundance of potable water while reducing energy consumption to less than one-third of former levels.
For more than six centuries, visitors have been drawn to the beauty and mystery of Italy’s Aeolian Islands, a volcanic archipelago that lies about 40 kilometres north of Sicily.
The popularity of the islands increased after 2000 when they were designated a World Heritage site by the United Nations Educational, Scientific and Cultural Organization, the first nature site in Italy to receive this recognition. Since then, the scarcity of potable water on Lipari, the largest island and main entrance point for tourists, has become increasingly pressing.
Lipari has a permanent population of about 11,000 and no source of fresh water (read more under the tab "Thirsty islands" at the top of this story). For years, water was shipped from Sicily and Naples to satisfy the needs of locals and visitors. At a reported cost of more than EUR 10 per metric cube of shipped water, this solution was feasible – although costly – during winter months.
In the summer, however, the island’s population and water needs grow dramatically. Official figures cite 200,000 tourists throughout the season; Lipari’s mayor, Marco Giorgianni, suggests twice as many may arrive over the August peak.
A simple plant
To cope with this demand, in 1988 the regional government of Sicily initiated plans for a desalination facility on Lipari. The plant began operating in 1998, using an evaporation system with high-pressure pumps. It produced 162 cubic metres per hour of potable water, which was just about enough to satisfy the needs of the locals during winter months. On the other hand, it was not energy efficient, requiring 15 kilowatt hours to produce each cubic metre of water.
In recent years, the need for both more drinking water and greater energy savings prompted the region of Sicily to invite bids for the construction of a modern desalination plant. The winning bid came from the Italian firm Sled Costruzioni Generali S.pA., signing the contract in 2011. The company’s bid was for a EUR 15 million project, including a desalination plant, a photovoltaic system to supply energy during daylight hours and other features. Sled in turn contracted Euro Mec (read more under the tab "Euro Mec - a Grundfos partner" at the top of this story), a world leader in water treatment plants, to handle the EUR 4 million desalination system. Euro Mec agreed to supervise the installation and start-up of the plant, plus training and on-going support to local operators.
Elena Bonadei is the manager of this project. She is a process engineer for water treatment plants, and has worked on more than 30 of them all over the world since joining Euro Mec in 2003. While this is her company’s first project with Sled, she knows Grundfos pumps well and is confident in using them in Euro Mec projects because, she says, “They are world leaders in pumps for desalination systems.”
Elena Bonadei and her team planned the Lipari plant in a series of stages.
The new system will save around 36,000 litres of diesel a day during peak season, equal to 79 tons of carbon dioxide emissions or 42 round trips by plane from London to New York.
The plant uses a skid-mounted reverse osmosis (RO) system to convert seawater into potable water. The skid mount facilitates transportation and access by mounting the RO equipment onto a frame. The RO process removes salt and other substances from water molecules by applying pressure to the solution when it is on one side of a semipermeable membrane. Undesirable contaminants, such as salt, are retained on the pressurised side of the membrane while the purified water passes to the other side.
The desalination units installed at the Lipari plant have two Grundfos BME pumps (read more under the tab "Grundfos Supplied" at the top of this story) each as standard supply, to drive the seawater through the membranes. The higher the pressure, the larger the driving force required, thus the pump is subjected to demanding operating conditions. Grundfos’ dedicated high-pressure pumps, such as the BME, have been reinforced to generate up to 65 bar pressure. At the plant in Lipari, the pumps generate up to 65 cubic metres per hour at 62 bar.
Drinking in the benefits
Not only is the system capable of generating almost three times more potable water than the old evaporating system, but it does so more efficiently and economically, lowering the energy consumption to less than a third. It incorporates an energy recovery device that recovers up to 96 percent on the brine side. Estimations show that the new system will save around 36,000 litres of diesel a day during peak season, equivalent to 79 tons of carbon dioxide emissions or 42 round trips by plane from London to New York.
Upon completion of all three sections in 2013, the total flow rate of the desalination plant will be 450 cubic metres per hour. Each of the three sections can be managed independently. All three will operate together during peak season, while one section alone can handle the island’s needs during winter months.
"When complete, the desalination plant’s total flow rate will be 450 cubic metres per hour."
Founded in 1999, Euro Mec s.r.l. is headquartered in Mantua in Northern Italy. It specialises in the design and construction of a wide range of water treatment plants, and its more than 50 full-time employees work on six continents. Euro Mec has completed projects for the oil and gas industries, textile companies, industrial corporations and the United Nations.
The company's technical design team develops water treatment plants, equipment and technology for the purification of industrial and civil waste water (including water recovery and reuse), and for desalination and drinking water treatment around the world.
Grundfos has trained and certified Euro Mec staff for commissioning and service of Grundfos products.
“Our cooperation with Euro Mec – from the starting point of design through system development and evaluation – is the key to our mutual success,” says Henning Vester, Global Senior Product Specialist of Grundfos.
"Our cooperation with Euro Mec − from the starting point of design through system development and evaluation − is the key to our mutual success."
Henning Vester, Global Senior Product Specialist of Grundfos
The touristy Aeloian Islands lack naturally potable water
More than 1.1 billion people in the world lack access to clean drinking water. Many factors account for this shortage: contaminants from industry and agriculture, naturally occurring elements in the ground, climate, and often it is simply geography. Islands, for example, are surrounded by water, but unless they have natural springs, they may lack access to potable water.
This problem is common to almost all seven of the small and medium-sized Aeloian islands – Alicudi, Filicudi, Panarea, Stromboli, Salina, Lipari and Volcano – off the coast of Italy. According to Euro Mec engineer Elena Bonadei, drinking water is normally shipped to these islands by boat, at a minimum cost of EUR 10 per cubic metre. “Very few of these locations have locally-based water purification plants,” she says.
Lately, however, this trend has been reversing itself (read more under the tab "Goodbye evaporation, hello RO" at the top of this story). Lipari has a desalination plant and soon Volcano will have its own autonomous water treatment facility.
Says Elena Bonadei: “At first the Ministry of the Environment thought that the water created in Lipari would be transported by boat to Volcano, but they decided to construct an independent plant on Volcano. Bids on the construction of this second facility have already been made.”
She adds that Sicily’s regional government is evaluating the possibility of a third plant on Salina. Like Volcano, Salina’s population increases dramatically in summer months.
“The solution for such localities,” she says, “is increasingly to opt for smaller, locally-based facilities due to their reduced environmental footprint and lower production costs.”
"The solution is increasingly to opt for smaller, locally-based desalination facilities due to their reduced environmental footprint and lower production costs."
Elena Bonadei, Euro Mec engineer
Grundfos provided to Euro Mec for the reverse osmosis (RO) desalination plant on Lipari:
* 6 complete Grundfos BMEX pump systems
* 12 CRN 45-2 pumps
* 4 Grundfos Hydro MPC booster systems to distribute drinking water to Lipari after RO treatment.