Sustainability Assessment of Desalination and Resource Recovery from Brines

Abstract

Desalination plays a vital role in addressing water scarcity, but its high energy consumption and brine, a saline waste stream, disposal pose significant environmental and economic challenges. Seawater is a rich source of valuable and scarce materials that are lost when brine is discharged, making resource recovery a promising approach to improve sustainability. Integrating multiple technologies to recover water and valuable materials improves technological performance, but it introduces technical, economic, and societal complexities.
While desalination with resource recovery offers an alternative source of water, salts, and chemicals, its sustainability depends on local conditions and necessitates a holistic evaluation. Assessing these systems is particularly complex when water, a primary good, is among the recovered products. This research aims to refine assessment methodologies and explore trade-offs in integrated desalination and brine treatment. It adopts an exploratory, mixed-methods approach, beginning with a systematic literature review and the development of a sustainability assessment framework that prioritizes stakeholder participation.
In Chapter 2, the current sustainability assessment frameworks in desalination, water treatment, and resource recovery were reviewed and analysed. The literature review identified critical shortcomings in current sustainability assessments for seawater desalination and brine treatment systems. These assessments notably neglect social aspects and stakeholder involvement. To address these deficiencies, we proposed a new Sustainability Assessment (SA) framework that integrates participatory multi-criteria analysis and value-sensitive design into the decision-making process.
An open-source software tool in Python was developed in Chapter 3 to simulate the desalination and mineral recovery processes, providing data that will inform later assessments. The outputs from this software directly support the analyses presented in Chapters 4–7, illustrating its integral role in this thesis and its potential for broader applicability.
The value-sensitive design (VSD) approach was applied in Chapter 4 to design and evaluate integrated seawater desalination and brine treatment, ensuring that technical scenarios align with societal values. Four configurations were assessed for trade-offs between resource recovery, energy consumption, and environmental impact. While maximizing water and salt recovery improves resource security, it increases energy use and CO₂ emissions. The study highlights the need for region-specific solutions and demonstrates how VSD fosters stakeholder dialogue, supporting sustainable and socially acceptable designs. These scenarios serve as the basis for analysis in subsequent chapters.
In Chapter 5, the economic performance of desalination systems focused on resource recovery was assessed using the levelized cost indicator. Allocation factors were used to fairly distribute costs and income from recovered products. A comparison of traditional Non-allocation and novel cost calculation methods revealed that the Non-allocation method overestimates production costs, resulting in inflated product prices. The Economic allocation approach, by redistributing costs to higher-value products, assigns a minimal percentage to water costs, unlike the heavy loading seen with Non-allocation.
Chapter 6 investigates the environmental performance of integrated desalination and brine treatment systems for resource recovery using Life Cycle Assessment (LCA). The study highlights how key methodological choices—like functional unit and treatment of waste heat—substantially affect results. Overall, resource recovery systems demonstrated superior performance compared to conventional production systems of the same product basket, highlighting the need for integrated practices.
Finally, the effect of interdependence among decision criteria in the multi-criteria decision-making process for sustainability assessment was evaluated in Chapter 7. By combining the Best-Worst Model and the Decision-Making Trial and Evaluation Laboratory technique, we proposed a novel weighting method that accounts for interdependencies. Applied to desalination and brine treatment, results showed that while numerical impacts are moderate, capturing interdependencies improves conceptual understanding—particularly in single-stakeholder settings.
In Chapter 8, a summary of the main findings of this thesis is provided, along with the limitations of this work and an outlook for future research directions based on these findings.