Consider Energy-Smart Water Processing Through Advanced Membranes
Chemical facilities face mounting challenges in managing concentrated brines from diverse sources, including desalination, industrial effluents and resource recovery operations. The need for energy-efficient brine management solutions has become critical as energy costs rise and environmental regulations tighten.
While thermal methods like evaporative brine concentrators (EBC) and crystallizers (EBCr) can consume 20–100 kWh/m3 for brine concentration, membrane-based technologies offer more energy-efficient alternatives.
These innovations promise to slash energy consumption while enabling water recovery from increasingly concentrated brines — potentially transforming what was once considered waste into valuable resource streams.
Recent advances in membrane-based brine concentration demonstrate potential energy savings of up to 50% compared to evaporative brine concentrators, while achieving brine concentrations of up to 250 g/l. For example, ultra-high-pressure reverse osmosis operating at 120 bar can theoretically achieve a minimum specific energy consumption (SEC) of 3.33 kWh/m3.
The Energy Efficiency Paradigm
Depending on your application, compelling evidence for the energy advantages of membrane-based separations compared to conventional thermal methods can be more than convincing. In desalination applications, for instance, reverse osmosis (RO) technology achieves remarkable efficiency, requiring only 3-4 kWh/m³ of water produced.
This represents a dramatic reduction from the ~15-60 kWh/m³ consumed by various thermal desalination methods. This substantial difference stems from membrane technology's fundamental advantage: achieving separation without energy-intensive phase changes.
While not suitable for all separation requirements, the technology has demonstrated value in water treatment, gas separation and organic solvent recovery applications. Success in implementation requires careful attention to application-specific requirements, proper system design and diligent operation and maintenance practices. This month, we will look at water-based use cases.
Performance Analysis
Modern membrane distillation can achieve brine concentrations up to 250 g/l, while electrodialysis reversal (EDR) demonstrates enhancing fouling resistance and requires less pretreatment compared to conventional RO systems. For industrial applications, membrane-based crystallization has shown promise in mineral recovery, with successful extraction of compounds like magnesium hydroxide, calcium carbonate and lithium carbonate.
A quantitative comparison of brine concentration approaches shows significant differences in energy requirements (Table 2). The latest data highlights the significant energy advantage of ultra-high-pressure reverse osmosis (UHPRO) compared to conventional electrodialysis/electrodialysis reversal (ED/EDR) and evaporative brine concentrators (EBC), though each technology offers distinct operational benefits and limitations. The values represent theoretical minimums, with actual operational values typically higher due to various system inefficiencies and irreversible losses.
The maturity of membrane technology in water treatment applications is exemplified by modern RO plants. For example, the Sorek desalination facility in Israel produces 624,000 to 640,000 m³/day while consuming just 3.5 kWh/m³.
A back-of-the-envelope calculation shows that if a multi-stage flash using 25 kWh/m3 instead employs membrane technology for desalination, the required energy will be reduced by over 80%. Most new desalination plants use RO, though the achievement demonstrates the technology's capability to deliver large-scale, energy-efficient separation solutions.
Plant operators implementing membrane-based water treatment systems must focus on several critical operational parameters. Pretreatment of feed water is critical for preventing membrane fouling and maintaining long-term system performance. This includes removing suspended solids, controlling scaling potential and managing biological fouling risks.
Operating pressure optimization requires careful balance between energy consumption and water flux, while regular membrane cleaning and maintenance schedules prevent performance degradation. Additionally, monitoring and controlling concentration polarization helps maintain optimal separation efficiency.
Operating costs warrant particular attention, as they include energy consumption, membrane replacement (typically occurring every three to seven years), cleaning and maintenance requirements and labor costs.
Successful operation demands thorough operator training, development of standard operating procedures, integration with existing monitoring and control systems and implementation of regular maintenance schedules.
For plant managers considering membrane-technology implementation, thorough technical and economic evaluation coupled with proper planning for operation and maintenance will prove critical to realizing the potential benefits of these energy-efficient separation systems.
The continued advancement of membrane materials and designs suggests even greater potential for energy savings in future applications.
References
Dischinger, S. M., Miller, D. J., Vermaas, D. A., & Kingsbury, R. S. (2024). Unifying the Conversation: Membrane Separation Performance in Energy, Water, and Industrial Applications. ACS Es&t Engineering, 4(2), 277-289.
Osman, A. I., Chen, Z., Elgarahy, A. M., Farghali, M., Mohamed, I. M., Priya, A. K., ... & Yap, P. S. (2024). Membrane technology for energy saving: principles, techniques, applications, challenges, and prospects. Advanced Energy and Sustainability Research, 5(5), 2400011.
Tareemi, A. A., & Sharshir, S. W. (2023). A state-of-art overview of multi-stage flash desalination and water treatment: Principles, challenges, and heat recovery in hybrid systems. Solar Energy, 266, 112157.
Wu, J., & Hoek, E. M. (2025). Current opportunities and challenges in membrane-based brine management. Current Opinion in Chemical Engineering, 47, 101079.
