Water treatment has always been about separation. Capture what you want and reject the rest. This linear approach, epitomised by reverse osmosis and other advanced purification processes, is simple, linear, and historically efficient. Yet, in an era defined by climate volatility, tightening regulations, and fragile supply chains, this linear model is increasingly a strategic vulnerability.
The brine stream sits at the edge of this linear model. It contains a high concentration of salt, organic matter, and residual contaminants, depending on the source. For decades, brine has been managed as a liability to dilute, dispose of, or inject underground, budgeted as a compliance cost rather than viewed as a resource. Performance in desalination has therefore been measured by recovery percentage, specific energy consumption, and permeate quality. However, the next generation of water treatment facilities will not be defined solely by how efficiently they produce water, but by their ability to co-produce other valuable minerals.
Let’s consider the chemical dependency of modern plants. Municipal desalination and reuse facilities rely heavily on bulk chemicals such as sodium hydroxide, hydrochloric acid, and ferric salts to mitigate scaling and fouling. These chemicals are produced in centralised industrial hubs and transported long distances to treatment plants that depend on steady deliveries to keep membranes online. However, the very brine produced already contains concentrated sodium chloride, the precursor to acids and bases via electrochemical conversion. With the right configuration, a plant can convert part of its concentrate into sodium hydroxide and hydrochloric acid on-site. Generating key reagents on-site from brine does more than closing a chemical loop. It localises manufacturing and decentralises risk, reducing reliance upon external supply chains by transforming the brine streams into flexible on-site resources.
Water scarcity is now the defining constraint; in this context, brine is not simply a concentrated stream but represents diversified optionality
Critics will point to the cost and complexity of valorisation upgrades, which are valid concerns. Technologies such as electrochemical cell and advanced separation technologies do require capital investment, controls, and inclusion into already intricate treatment trains. However, the water treatment industry has successfully incorporated other complex processes, including advanced oxidation processes and membrane bioreactors, when public health and environmental standards demanded it. In this sector, innovation has rarely been optional; it has always been a response to constraints.
Real-world examples and existing initiatives clearly demonstrate the practical viability of brine valorisation. In Singapore, facilities such as the Tuas Desalination Plant are exploring bipolar membrane electrodialysis to generate sodium hydroxide from brine, citing the potential to reduce reliance on imported chemicals and minimise discharge volumes. In the United Arab Emirates, initiatives involving brine from plants like Taweelah are harnessing magnesium and calcium to produce materials such as aggregates or cement alternatives for construction. In California, projects such as those piloting lithium recovery from geothermal brines in areas like the Salton Sea are achieving promising extraction efficiencies.
Water scarcity is now the defining constraint. In this context, brine is not simply a concentrated stream but represents diversified optionality. The membrane revolution succeeded because engineers dared to separate salt from water. The next leap will require equal ambition: converting what we once discarded into assets that strengthen resilience so that desalination plants of the future will not be linear endpoints. They will be integrated resource hubs, producing water, reagents, and stability in a world that desperately demands all three.
