Currently, there are over 20,000 desalination plants globally, and this number is expected to rise in the coming years. Climate change, persistent droughts, and increasing population demands are exerting immense pressure on the availability of drinking water. Desalination, particularly reverse osmosis, is addressing these challenges effectively. As desalination gains traction as a viable alternative, the focus has shifted to enhancing its processes.
Firstly, in terms of energy consumption, advancements are being made toward more efficient desalination technologies and integrating renewable energy sources. Secondly, brine processing, which involves the concentrated salt left over after desalination, is gaining attention. How can this waste be transformed into a valuable resource?
This article will cover the following topics:
What exactly is brine?
For this article, we’re focusing on brine from seawater desalination, which is essentially water with a high salt concentration. However, it can also be found in olive jars, seafood cooking water, and salt pans where seawater evaporates to produce sea salt.
Brine is also rich in minerals, some of which have significant value and could be recovered for reuse in various industries, paving the way for sustainable “mining.” But what minerals can be obtained from brine, and what processes are ideal for extracting them? Let’s explore this further.
What resources can be extracted from brine?
In line with the principles of the circular economy, recent research has focused on extracting raw materials from brine. For instance, a study by MIT highlighted the potential to produce caustic soda from brine.
Brine contains numerous elements, including minerals like calcium, lithium, magnesium, and boron, as well as rare, high-value metals like rubidium, vanadium, gallium, and molybdenum. Another research avenue is the indirect production of compounds like beta-carotene by cultivating microalgae in brine solutions.
MINERALS: An R&D project moving from lab to reality
Projects aiming to valorize brine have moved beyond theoretical exercises and have been tested under real-world conditions. One of the most promising examples is the MINERALS project, “Selective extraction of high-value elements from seawater brine,” a collaboration between ACCIONA and the LEITAT Technology Center.
MINERALS will apply advanced technologies to recover critical raw materials from brine that are not only highly useful but also scarce.
ACCIONA is actively researching this field with a pilot project that will employ techniques like liquid membranes, nanofiber adsorbents incorporating selective nanoparticles, and gravity precipitation processes.
The project aims for efficiencies ranging from 90% for monovalent ions like lithium, rubidium, and boron to 65% for calcium. Efficiencies for magnesium and potassium are targeted at 80% and 70%, respectively.
A pilot plant is expected to be set up at a reverse osmosis desalination facility to demonstrate the feasibility of this technological approach. Once scaled, this sustainable process could offer a new revenue stream for desalination plants, enhancing their competitiveness in providing drinking water for all.
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