Extracting water minerals and energy from seawater desalination brine – EXTRASEA

With more than 18,000 plants worldwide, seawater desalination is the most reliable and sustainable way to produce drinking water in Mediterranean countries under water stress. EXTRASEA’s challenge is to innovate in membrane desalination, to recover more water by consuming less fossil energy, reduce the ecological and toxicological impacts of rejected brines while enhancing the nutrients and energy of brines and finally promote access to water in remote areas, using solar energy.
EXTRASEA specific objectives are:

1) enhance thermal efficiency of Membrane Distillation/Crystallization (MDCr) via next-generation thermoplasmonic membranes operated under solar radiation, and applying MDCr at > 90% water recovery to
extract salts from hypersaline desalination brine;
2) develop next generation of silicon solar cells based on ultra-thin transparent conductive oxide (TCO) films with less solar cell base/low cost materials;
3) integrate Reverse Electrodialysis (RED), an innovative membrane technology able to extract electrochemical energy from Salinity Gradient Power, with MDCr unit to harvest salinity gradient power energy from desalination brine;
4) transfer innovation into a mobile solar-powered prototype for use in remote locations.
The implementation of the revolutionary technological concept of EXTRASEA will significantly contribute to the transition towards a Circular Economy, where raw materials and resources are cyclically generated and wastes minimized and valorized, in the logic of Process Intensification and Zero-Liquid Discharge (ZLD).
The contribution of INSA Toulouse in the project is mainly relative to objectives 1 and 4 and to dissemination.
A transnational team of leading institutions (University of Calabria, Italy; INSA Toulouse, France; University Center Belhadj Bouchaib, Algeria; Tubitak MRC, Turkey; University Hassan II Casablanca, Morocco; University of Carthage,Tunisia) and SMEs (Nanometer SrL, Italy; PC Cell GmbH, Germany) based on 7 European-Mediterranean countries has been assembled synergistically and complementarily.
Methodologies include : manufacturing of mixed membranes including thermoplamonic nanoparticles (NP), characterization of their properties,stability under operation and performances for MDCr, modelling of the effects of NPs on the membrane properties and the process, development and testing on site of new PV panels, implementation and testing of RED when coupled with MDCr, collective design of the solar –powered demo pilot plant, by assembling MDCr, RED and the new solar panels, thermo-economic analysis and Life cycle analysis of the integrated desalination system.

The expected results are :
- New knowledge and publications on membrane processes and their coupling when operated on saline and hypersaline waters (highly concentrated brines) for water, salt or energy recovery
- Advanced membranes for Membrane Distillation/Crystallization functionalized with nanoparticles to activate local heating via plasmon resonance, allowing both a good productivity and drinking water quality in compliance with WHO standards
- Adaptation of the Reverse Electrodialysis technology to energy production by using salinity Gradients, and its integration with MDCr.
- A mobile, solar-powered integrated desalination prototype, powered by TCO thin-film PV technology and with a water recovery factor > 90% - This prototype will be installed in Algeria.
- Proof of the interest of an integrated and intensified treatment route, based on the valorization of desalination brines, considered as a source of sea salts.