Analysis of energy, water, land and cost implications of zero and minimal liquid discharge desalination technologies

Desalination is increasingly essential to ensure access to water 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, and in doing so 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, thereby reducing the liquid volumes requiring disposal. In this analysis, we evaluated the cost, energy and sustainability impacts of 7 overarching treatment trains with 75 different configurations. We found ZLD/MLD water recoveries ranging from 32.6% to 98.6%, but with steep energy and cost trade-offs that underscore the crucial roles of ion-specific separations, heat integration and clean energy sources. We explored the key trade-offs between cost, energy and water recovery, elucidating the increasingly tight connections that are central to the energy–water nexus and desalination.