Water, Energy, and Cost: A Nexus Approach to Zero/Minimal Liquid Discharge Desalination Technologies

Desalination is increasingly essential to ensure water access as climate change and population growth stress fresh water supplies. Already in use in water-stressed regions around the world, desalination generates fresh water from salty sources, but forms a concentrated brine that requires disposal. There is a growing push for the adoption of zero/minimal liquid discharge (ZLD/MLD) technologies that recover additional water from this brine while reducing the liquid volumes requiring disposal. This analysis evaluates the cost, energy, and sustainability impacts of 7 overarching treatment trains with 75 different configurations. ZLD/MLD water recoveries are found to range from 32.6-98.6%, but with steep energy and cost tradeoffs that underscore the crucial role of ion-specific separations, heat integration, and clean energy sources. Ultimately, this analysis explores key tradeoffs between costs, energy, and water recovery, highlighting the increasingly tight connections at the central to the energy-water nexus and desalination.