Comparative assessment of conventional and emerging desalination technologies: a holistic review for sustainable water solutions

Societal Impact StatementWith global weather patterns becoming more extreme and unpredictable, sourcing reliable irrigation water is vital for improving food security and conserving drinking water in drought‐prone areas. Emerging desalination technologies, which are still in the development phase, could potentially provide large quantities of slightly saline water for irrigation. However, we must first ensure that any benefits of alleviating drought using this water outweigh the negative impacts of salt stress. We examine the viability of such a system, using Tonga as a case study, with the aim of advocating for future use of emerging desalination technologies for irrigation in low‐ and middle‐income countries.SummaryEmerging desalination technologies have the potential to be a cheap and energy‐efficient source of irrigation water that could be used to alleviate short‐term droughts in low‐ and middle‐income countries. However, the water produced is unlikely to be completely salt‐free, potentially increasing the risk of salt stress in crops. In this review, we give an overview of the various emerging desalination technologies. We then use Tonga as a case study for assessing the viability of temporarily irrigating crops with moderately saline water (≤100 mM salt) and assess whether the benefits of alleviating drought outweigh the negative impacts of salt stress. We conclude that, in Tonga, important food security crops are likely to have higher survival and growth rates if they are provided with moderately saline water during drought, including taro, pumpkin and yam. Water derived using the new technologies would not be prohibitively expensive to produce. Moreover, it would minimise the need to divert a diminishing supply of water away from drinking to irrigation. The continued improvement of emerging desalination technologies, together with field trials, will help to optimise the use of moderately saline water for irrigation. This is likely to be especially beneficial for achieving and maintaining food security in low‐ and middle‐income countries in increasingly capricious conditions for agriculture.

Emerging desalination technologies: Current status, challenges and future trends

Several regions are confronting a severe scarcity of fresh water due to the gap between supply and demand. They strive to bridge that gap by depleting nonrenewable water aquifers and expanding centralized energy-intensive desalination technologies. Continuing to adopt the same unsustainable approach could deplete the water aquifers and increase the consumption of fossil fuel and the ecological impact on air, water, and land. However, the traditional paradigm of centralized desalination systems could be shifted by increasing the utilization of renewable distributed generation, which can be coupled with emerging desalination technology such as adsorption desorption desalination (ADD), which has autonomous and resilient attributes that can contribute to the sustainability of decentralized fresh water supply in the future. In this work, three commercialized desalination technologies were reviewed and compared with emerging ones to explore the most economically and environmentally efficient systems within the context of decentralized water production. The well-known configurations of ADD were evaluated and compared with sea water reverse osmosis (SWRO), which is recognized as the principal commercialized desalination technology worldwide. The quantitative case study methodology was used by investigating four centralized seawater desalination plants in Saudi Arabia (SA) with their associated pipeline systems from the energy consumption point of view to determine the applicability of implementing ADD technology in SA and similar arid areas. The study reveals that adopting decentralized ADD technology coupled with renewable energy sources could reduce the specific energy consumption from 4 kWh/m3 to less than 1.38 kWh/m3. Combining reduced energy consumption from desalination plants and elimination of supply pipelines could potentially result in a significant reduction in energy consumption and carbon emissions. Finally, the study may be useful for researchers working on enhancing ADD processes, as well as technology users who would like to implement the most efficient ADD configurations. Additionally, it may initiate a direction of utilizing the results of original critical reviews as a methodology to develop the applied technologies.

Environmental impact of emerging desalination technologies: A preliminary evaluation

Energy for desalination: A state-of-the-art review

Optimal Design of a Hybrid Membrane System Combining Reverse and Forward Osmosis for Seawater Desalination

Review on adsorption materials and system configurations of the adsorption desalination applications

Emerging desalination technologies for water treatment: A critical review

Renewable and sustainable approaches for desalination

Assessment of desalination technologies for treatment of a highly saline brine from a potential CO2 storage site

Towards attaining SDG 6: The opportunities available for capacitive deionization technology to provide clean water to the African population

Enhancing understandability and performance of flow electrode capacitive deionisation by optimizing configurational and operational parameters: A review on recent progress

Permeate Gap Membrane Distillation (PGMD) is an emerging desalination technology that offers a promising alternative for freshwater production, particularly in energy-efficient and sustainable applications. This review provides a comprehensive analysis of PGMD, covering its fundamental principles, heat and mass transfer mechanisms, and key challenges such as temperature and concentration polarization. Various optimisation strategies, including Response Surface Morphology (RSM), Differential Evolution techniques, and Computational Fluid Dynamics (CFD) modelling, are explored to enhance PGMD performance. The study further discusses the latest advancements in system design, highlighting optimal configurations and the integration of PGMD with renewable energy sources. Factors influencing PGMD performance, such as operational parameters (flow rates, temperature, and feed concentration) and physical parameters (gap width, membrane properties, and cooling plate conductivity), are systematically analysed. Additionally, the techno-economic feasibility of PGMD for large-scale freshwater production is evaluated, with a focus on cost reduction strategies, energy efficiency, and hybrid system innovations. Finally, this review outlines the current limitations and future research directions for PGMD, emphasising novel system modifications, improved heat recovery techniques, and potential industrial applications. By consolidating recent advancements and identifying key challenges, this paper aims to guide future research and facilitate the broader adoption of PGMD in sustainable desalination and water purification processes.

Evolution of polymeric hollow fibers as sustainable technologies: Past, present, and future

Due to substantial consumption and widespread contamination of the available freshwater resources, green, economical, and sustainable water recycling technologies are urgently needed. Recently, Faradic capacitive deionization (CDI), an emerging desalination technology, has shown great desalination potential due to its high salt removal ability, low consumption, and hardly any co-ion exclusion effect. However, the ion removal mechanisms and structure-property relationships of Faradic CDI are still unclear. Therefore, it is necessary to summarize the current research progress and challenges of Faradic CDI. In this review, the recent progress of Faradic CDI from five aspects is systematically reviewed: cell architectures, desalination mechanisms, evaluation indicators, operation modes, and electrode materials. The working mechanisms of Faradic CDI are classified as insertion reaction, conversion reaction, ion-redox species interaction, and ion-redox couple interaction in the electrolytes. The intrinsic and desalination properties of a series of Na+ and Cl- capturing materials are described in detail in terms of design concepts, structural analysis, and synthesis modulation. In addition, the effects of different cell architectures, operation modes, and electrode materials on the desalination performance of Faradic CDI are also investigated. Finally, the work summarizes the challenges remaining in Faradic CDI and provides the prospects and directions for future development.