Recent developments in forward osmosis : opportunities and challenges.

Recent advances in membrane distillation processes: Membrane development, configuration design and application exploring

Selection of inorganic-based draw solutions for forward osmosis applications

In the rapidly developing shale gas industry, managing produced water is a major challenge for maintaining the profitability of shale gas extraction while protecting public health and the environment. We review the current state of practice for produced water management across the United States and discuss the interrelated regulatory, infrastructure, and economic drivers for produced water reuse. Within this framework, we examine the Marcellus shale play, a region in the eastern United States where produced water is currently reused without desalination. In the Marcellus region, and in other shale plays worldwide with similar constraints, contraction of current reuse opportunities within the shale gas industry and growing restrictions on produced water disposal will provide strong incentives for produced water desalination for reuse outside the industry. The most challenging scenarios for the selection of desalination for reuse over other management strategies will be those involving high-salinity produced water, which must be desalinated with thermal separation processes. We explore desalination technologies for treatment of high-salinity shale gas produced water, and we critically review mechanical vapor compression (MVC), membrane distillation (MD), and forward osmosis (FO) as the technologies best suited for desalination of high-salinity produced water for reuse outside the shale gas industry. The advantages and challenges of applying MVC, MD, and FO technologies to produced water desalination are discussed, and directions for future research and development are identified. We find that desalination for reuse of produced water is technically feasible and can be economically relevant. However, because produced water management is primarily an economic decision, expanding desalination for reuse is dependent on process and material improvements to reduce capital and operating costs.

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Desalination and reuse of high-salinity shale gas produced water: drivers, technologies, and future directions

Energy-efficient desalination and water treatment technologies play a critical role in augmenting freshwater resources without placing an excessive strain on limited energy supplies. By desalinating high-salinity waters using low-grade or waste heat, membrane distillation (MD) has the potential to increase sustainable water production, a key facet of the water-energy nexus. However, despite advances in membrane technology and the development of novel process configurations, the viability of MD as an energy-efficient desalination process remains uncertain. In this review, we examine the key challenges facing MD and explore the opportunities for improving MD membranes and system design. We begin by exploring how the energy efficiency of MD is limited by the thermal separation of water and dissolved solutes. We then assess the performance of MD relative to other desalination processes, including reverse osmosis and multi-effect distillation, comparing various metrics including energy efficiency, energy quality, and susceptibility to fouling. By analyzing the impact of membrane properties on the energy efficiency of an MD desalination system, we demonstrate the importance of maximizing porosity and optimizing thickness to minimize energy consumption. We also show how ineffective heat recovery and temperature polarization can limit the energetic performance of MD and how novel process variants seek to reduce these inefficiencies. Fouling, scaling, and wetting can have a significant detrimental impact on MD performance. We outline how novel membrane designs with special surface wettability and process-based fouling control strategies may bolster membrane and process robustness. Finally, we explore applications where MD may be able to outperform established desalination technologies, increasing water production without consuming large amounts of electrical or high-grade thermal energy. We conclude by discussing the outlook for MD desalination, highlighting challenges and key areas for future research and development.

https://par.nsf.gov/servlets/purl/10058665

C. Riziero Martinetti

Papers

High recovery of concentrated RO brines using forward osmosis and membrane distillation