Making salt water fresh on Lampedusa

News - 04 November 2022 - Communication TNW

Since last week, a large-scale demo installation in Lampedusa is producing drinking water, salts and chemicals from seawater in an environmentally friendly way. Project leader Dimitris Xevgenos: “This is the first time that we’re producing these marketable products at pre-commercial scale in Europe together with the right actors, including the use of waste heat. People can come and actually see it running.” 

The demo system will stay in Lampedusa until end of December this year.
If you wish to visit it, get in touch with us so that we can organise a visit and welcome you in our facilities!
– Dimitris Xevgenos

At the Southernmost part of Italy lies a beautiful island, Lampedusa. It is home to approx. 6,600 residents and more than 40,000 tourists visiting per year, while there’s also a large influx of refugees. To sustain its community and related economic activities, the island is 100% dependent on seawater desalination to provide its water needs. Thanks to SOFIP group a desalination facility is running since 1972 with a total capacity of 3,500 m3/day. This solution has secured water supply, but at the same time has put some pressure to the island’s environment; accounting for approximately 10% of the total energy consumption, as well as damage to the ecosystem through brine discharge back into the sea.

Renewable energy
In the pursuit of finding the most sustainable way to produce desalinated water, the power company in Lampedusa called SELIS (part of SOFIP group) has joined the WATER-MINING project, led by Dimitris Xevgenos, Mark van Loosdrecht and Patricia Osseweijer from Delft University of Technology. Together with PhD candidate Rodoula Ktori and postdoctoral researcher Marcos Rodriguez-Pascual, the Delft researchers have developed a large-scale demo with a total capacity of 50 m3/day. Xevgenos: “The demo system results in the recovery of high quality freshwater, salts and chemicals, while sourcing more than half of the energy requirements through waste heat recovered from the nearby power plant.” 

Project leaders Dimitris Xevgenos and Patricia Osseweijer during their visit to the WATER-MINING demo system on Lampedusa.

Creating a circular economy
Although there’s no industrial activity in Lampedusa, recovering salts and chemicals from seawater does make sense on larger islands like Cyprus. “With the aim of the social embedding and full-scale implementation of our innovative solution, we are engaging with local and regional stakeholders in what we call ‘Communities of Practice,’” Xevgenos says. “We’re looking into the possibilities of implementing a full-scale desalination system in Cyprus and giving materials back to the local economy, creating a circular economy.” Van Loosdrecht: “Seawater desalination generates brine which is discharged into the sea, where it leads to damage to the ecosystem. In Cyprus, we can use that brine to generate nutrients for agriculture and acid and base as a raw resource in the chemical industry.”

Andrea Cipollina, professor at the Università degli Studi di Palermo, holds up a piece of magnesium hydroxide, one of the salts that the installation extracts from seawater.

The desalination process integrates innovative technologies that enable a circular economy. TU Delft is partnering with 38 companies and universities from 12 different countries to not only decarbonise the process, but also recover salts and chemicals. The process works as follows:

The first step is a pretreatment stage to purify the seawater or brine with the help of nanofiltration, a technology supplied by the Dutch company LENNTECH. After the primary purification step, the brine is further concentrated with an extra nanofiltration step and a thermal evaporator that was designed by the Italian company SOFINTER – SWS Division and constructed by the Greek company THERMOSSOL STEAMBOILERS SA

The thermal evaporator

In the final step, the salts are retrieved using a crystallisation technology from TU Delft. Finally acid and base are produced from remaining salts by an electrodialysis process from the Università degli Studi di Palermo.

Dimitris Xevgenos

Senior Scientific Coordinator and Project leader

Mark van Loosdrecht

Full professor and Project leader

Patricia Osseweijer

Full professor and Project leader

Rodoula Ktori

PhD Candidate

Marcos Rodriguez-Pascual