Estimation of water footprint in seawater desalination with reverse osmosis process

An efficient data-driven desalination approach for the element-scale forward osmosis (FO)-reverse osmosis (RO) hybrid systems

Freshwater shortages are a consequence of the rapid increase in population, and desalination of saltwater has gained popularity as an alternative water treatment method in recent years. To date, the forward osmosis-reverse osmosis (FO-RO) hybrid technology has been proposed as a low-energy and environmentally friendly next-generation seawater desalination process. Scaling up the FO-RO hybrid system significantly affects the success of a commercial-scale process. However, neither the ideal structure nor the membrane components for plate-and-frame FO (PFFO) and spiral-wound FO (SWFO) are known. This study aims to explore and optimize the performance of SWFO-RO and PFFO-RO hybrid element-scale systems in the desalination of seawater. The results showed that both hybrid systems could yield high water recovery under optimal operating conditions. The prediction of the system performance (water flux and reverse salt flux) by artificial intelligence was considerably better (R > 0.99, root mean square error <5%) than that of conventional mass balance models. A Markov-based decision tree successfully classified the water flux level in hybrid systems. An optimal set of operational conditions for each membrane system was proposed. For example, in RO, a combination of the feed solution (FS) flow rate (≥17.5 L/min), FS concentration (<17,500 ppm), and operation pressure (<35 bar) would result in high water permeability (>40 LMH). In addition, five SWFO elements and four PFFO elements should be the optimal numbers of FO membranes in the hybrid FO-RO system for effective seawater desalination, especially for long-term operation.

Treatment of high-salinity brine containing dissolved organic matters by vacuum membrane distillation: A fouling mitigation approach via microbubble aeration

In this study, a laboratory-scale vacuum membrane distillation (VMD) system coupled with microbubble aeration (MBA) was developed for the treatment of high-salinity brine containing organic matters. Herein, at the beginning, feedwater only containing model organics such as humic acid (HA), bovine serum albumin (BSA) and sodium alginate (SA) was utilized to investigate the organic-fouling behavior, results indicated that the permeate flux was not affected by a thin and loose contaminated layer deposited on the membrane surface. Furthermore, dissolved organics in the feed brine inhibited the occurrence of membrane wetting due to the existence of a compact and protective crystals/organic-fouling layer, which can prevent the intrusion of scaling ions into membrane substrates. Besides, organics in the feedwater have a high tendency to adsorb on the membrane surface based on molecular dynamics simulations, thus, forming an organic-fouling layer prior to inorganic scaling. Finally, the effect of MBA on fouling alleviation was evaluated in VMD system, nearly 50% of salt precipitation from fouled membrane was effectively removed with the introduction of MBA, which can be ascribed to a combination of mechanisms, including surface shear forces and electrostatic attractions induced by microbubbles, meanwhile, about 2.2% of the total energy was only consumed, when using MBA. Together, these results demonstrated that MBA was a promising approach to alleviate membrane fouling in VMD.

Identification of cost and energy effective seawater membranes for use under hot climate conditions

Seawater desalination using a cost-effective reverse osmosis system is crucial for hot climate countries suffering from water scarcity. The most favorable seawater membrane characteristics were identified under typical Egyptian operating conditions. Twelve different commercially available membrane elements were investigated. A reverse osmosis system was designed and simulated using available software (e.g., ROSA and IMSDesign). The characteristics of the most promising membranes were identified for operation at Matruh (Mediterranean Sea) and Sharm El-Sheikh (Red Sea). The present work shows that the lowest cost of seawater desalination is obtained with membranes having high salt rejection, high permeate flow, high membrane active area, and permeate flux greater than 0.914 m³ /(d·m² ). Moreover, the cost of seawater desalination in summer is lower than in winter by 5% for Matruh and 2.7% for Sharm El-Sheikh. However, the impact of water salinity on the cost and specific energy consumption is higher than that of the seawater temperature. The cost of Mediterranean seawater desalination is lower than that of the Red Sea by 10.6%. Cost analysis at five different locations in Egypt shows that the highest cost takes place at Suez (Gulf of Suez), and the lowest cost occurs at Matruh (Mediterranean Sea). PRACTITIONER POINTS: Twelve different membranes were investigated for use under typical hot climate conditions. The cost of seawater reverse osmosis (RO) desalination is lower in summer by 2.7%-5% compared with winter. RO desalination costs up to 10.6% less for the Mediterranean Sea compared with the Red Sea. The optimum membrane element performance characteristics were identified for use under hot climate conditions.

Recent Development in Laminar Transition Metal Dichalcogenides-based Membranes Towards Water Desalination: A Review

Transition metal dichalcogenides (TMDCs)-based laminar membranes have gained significant interest in energy storage, fuel cell, gas separation, wastewater treatment, and desalination applications due to single layer structure, good functionality, high mechanical strength, and chemical resistivity. Herein, we review the recent efforts and development on TMDCs-based laminar membranes, and focus is given on their fabrication strategies. Further, TMDCs-based laminar membranes for water purification and seawater desalination are discussed in detail. Finally, present their merits, limits and future challenges needed in this area.