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Forward Osmosis, Nanofiltration, and Carbon Nanotubes Applications in Water Treatment
Published in Francisco Torrens, A. K. Haghi, Tanmoy Chakraborty, Chemical Nanoscience and Nanotechnology, 2019
Forward osmosis is an osmotic process, which like reverse osmosis, uses a semi-permeable membrane to result in the separation of water from dissolved solutes. The driving force for this separation is an osmotic pressure gradient, such that a high “draw” solution of high-concentration, is used to induce a net flow of water through the membrane into the draw solution thus effectively separating the feed water from its solutes. Technological validation, deep scientific vision, and the futuristic vision of engineering science will all lead a long and visionary way in the true realization of novel separation processes such as forward osmosis and nanofiltration. In contrast to forward osmosis, the reverse osmosis process uses hydraulic pressure as the driving force for separation, which serves to counteract the osmotic pressure gradient. In forward osmosis process, there may be solute diffusion in both directions depending on the concentration of the draw solution and the feed water. Application areas are the processing of energy drinks, desalination, landfill leachate treatment, and feed water pretreatment for thermal desalination. The vision and the challenges of science and technology of membrane separation processes are vast and versatile. This chapter opens up new doors of scientific ingenuity in the field of forward osmosis and other membrane science areas with deep details.
The Capability of Forward Osmosis in Irrigation Water Supply
Published in Iqbal M. Mujtaba, Thokozani Majozi, Mutiu Kolade Amosa, Water Management, 2018
Alireza Abbassi Monjezi, Maryam Aryafar, Alasdair N. Campbell, Franjo Cecelja, Adel O. Sharif
The lack of freshwater resources, in conjunction with population growth, forms one of the main impediments to sustainable development, while agriculture is the main consumer of freshwater resources. Currently, the production of desalinated water is costly and its use has therefore been limited to the production of water for drinking purposes. Forward osmosis desalination promises to overcome most of the practical difficulties in the conventional reverse osmosis process such as scaling, chemical treatment, fouling and high power consumption. In addition, forward osmosis is capable of delivering higher throughput with lower environmental impact, including minimal chemical additives and less brine rejection. Hence, the forward osmosis process offers a more energy efficient, environmentally friendly and economically viable desalination method. This study presented the forward osmosis process with thermal depression regeneration, using DME as a draw solution, leading to a significantly lower energy consumption rate in comparison with conventional desalination processes. The process of modified integrated forward osmosis with thermal depression has the potential to achieve a sustainable and cost-effective desalination solution to address the increasing scarcity of water for irrigation. The specific energy consumption of the proposed process was estimated to be 2.7 KWh/m3.
Introduction to Membranes
Published in Mihir Kumar Purkait, Randeep Singh, Membrane Technology in Separation Science, 2018
Mihir Kumar Purkait, Randeep Singh
The future of desalination is bright with efficient processes like forward osmosis. This membrane system is capable of treating water with salt concentrations up to five times more than seawater. This system can achieve up to 85% water recovery. Forward osmosis is similar to osmosis in the way that water flows from lower concentrations to higher concentrations to attain equilibrium. Forward osmosis differs from reverse osmosis as osmosis differs from reverse osmosis in that in reverse osmosis water flows from higher concentration to lower concentrations leaving behind the solutes (salts) by virtue of an external pressure or force. Hence, forward osmosis is energy efficient as compared to reverse osmosis. Another important difference between the processes is in the resultant permeates from the two processes. The permeate from RO is mostly freshwater that is ready to use, but in the case of FO results in a permeate that may contains solutes of the draw solution (draw solution is the source of driving force for FO) and thus the concentration of solutes in the draw solution and the final use of the permeate decide the further process steps. In recent times, Gibraltar and Oman have installed forward osmosis desalination plants. In the year 2010, National Geographic magazine counted forward osmosis as one of the three promising technologies for reduction in the energy consumption for desalination. Present-day RO membrane technology is consistent and commoditized in terms of efficiency, productivity, durability, and life span. Nowadays, a number of manufacturers are producing excellent quality RO membranes with proven track records and performance. Leading manufacturers are extensively exploiting further options for the improvement of RO membranes. They are supporting both the desalination industry as well as advancement in membrane technology and playing a vital role in the field of membrane science. Today desalination plants are fully automated with full protection and safety systems. These advancements cut the labor costs and further cut the cost of the desalinated water.
Reviewing the recent developments of using graphene-based nanosized materials in membrane separations
Published in Critical Reviews in Environmental Science and Technology, 2022
Roberto Castro-Muñoz, Angélica Cruz-Cruz, Yrenka Alfaro-Sommers, Luisa Ximena Aranda-Jarillo, Emilia Gontarek-Castro
Forward osmosis (FO) has been used in various wastewater treatment applications, sustainable power generation, desalination, and food processing due to its multiple advantages, including low fouling potential and its low-grade heat demand (Jin et al., 2018). Especially, thin-film composite (TFC) membranes for FO desalination were fabricated via interfacial polymerization (IP) of an aqueous mixture of polyethyleneimine (PEI) and GQDs onto modified polyacrylonitrile (PAN) ultrafiltration substrates. Chemical interactions and covalent bonds were observed between GQDs and PEI, which may allow the stability improvement of the GQDs-incorporated membranes during the filtration process as well as the hydraulic cleaning process. Through optimizing the fabrication protocol, the TFC membrane with 0.050 wt.% GQDs loading had a thin active layer of 50 nm, a surface roughness of 20 nm, a quite hydrophilic surface with a contact angle of 37.5°, and a neutrally charged membrane surface. These membranes exhibited an enhanced water flux of 12.9 kg m−2 hr−1 and a comparable reverse salt flux of 1.41 g m−2 hr−1 when deionized water and 0.5 M MgCl2 were used as the feed solution and draw solution, respectively. The optimized GQDs-incorporated TFC membrane also presented an acceptable anti-fouling performance (Xu et al., 2019).
UiO-66-NH2 nanocomposites incorporated cellulose acetate for forward osmosis membranes of high desalination performance
Published in Environmental Technology, 2022
Tong Li, Caixia Cheng, Kaifeng Zhang, Jie Yang, Guangshuo Han, Xiuju Wang, Zhongpeng Wang, Liguo Wang
The membrane can essentially be seen as a physical wall that isolates two phases and inhibits the transfer of different chemical substances in the process of individual selection [9]. Forward osmosis membrane can be applied to seawater desalination when it combines with appropriate draw solutions, and can also be used in other applications, such as wastewater treatment and heavy metal separation. In the case of desalination, the feed solution, seawater or brackish water, and the outlet solution are set in a reservoir but separated by semi-permeable membranes. Water flows from a lower concentration of feed solution to a higher concentration of extract solution through a semi-permeable membrane under high osmotic pressures. The water is then removed from the extract, usually by medium heat or membrane distillation, and the extract is recycled. Cellulose acetate (CA) has been widely used in membrane preparation due to its strong hydrophilicity, wide utilization and easy adjustment of chemical structure [10,11]. The application prospect of CA forward osmosis membrane is very broad, but it is very difficult to further promote. It is greatly affected by membrane fouling and internal concentration polarization (ICP) [12–14].
Uniqueness of biofouling in forward osmosis systems: Mechanisms and control
Published in Critical Reviews in Environmental Science and Technology, 2018
Qiaoying Wang, Meng Hu, Zhiwei Wang, Weijie Hu, Jing Cao, Zhi-Chao Wu
Osmotically driven membrane process (ODMP), as an emerging separation/desalination process, has attracted increasing attention in both academic research and industrial development in the past decade (Zhao, Zou, Tang, & Mulcahy, 2012). In a forward osmosis (FO) system, water molecules transport across a semi-permeable membrane from a feed solution to a concentrated draw solution driven by the osmotic pressure difference. Owing to the application of osmosis membrane and desuetude of external hydraulic pressure, ODMP has shown several advantages over pressure-driven membrane processes (PDMPs), such as low fouling propensity and salt rejection (Cath, Childress, & Elimelech, 2006). Therefore, ODMP technology is considered as a promising biological treatment process which is capable of treating various water and wastewater, including brackish groundwater desalination (Martinetti, Childress, & Cath, 2009), seawater desalination (Linares, Li, et al., 2014), wastewater treatment (Wang et al., 2015, Wang, Zheng, Tang, Wang, & Wu, 2016; Zhang et al., 2012), landfill leachate treatment (Dong et al., 2014), food processing (Lazarides, 2008), microalgae harvesting (Zou, Gu, Xiao, & Tang, 2011; Zou et al., 2013), and oil/gas exploration and production wastewater treatment (Hickenbottom et al., 2013).