Recent developments in forward osmosis: Opportunities and challenges

Zhao, Shuaifei; Zou, Linda; Tang, Chuyang Y.; Mulcahy, Dennis

doi:10.1016/j.memsci.2011.12.023

Cited by 1,229 publications

(771 citation statements)

References 199 publications

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“…It is well known that the organic components in wastewater are liable to attach to membrane surfaces and block membrane pores resulting in a decline of membrane flux in conventional membrane filtrations, such as RO, ultrafiltration (UF) and microfiltration (MF). Although previous studies claimed that FO has less membrane fouling compared with conventional pressure driven membrane filtration process [13], membrane fouling could be an issue in the present study by taking into account of the high organic content in the sewage.…”

Section: Membrane Fluxmentioning

confidence: 90%

Processing municipal wastewaters by forward osmosis using CTA membrane

Zhang

Ning

Wang

et al. 2014

Journal of Membrane Science

112

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Direct sewage filtration by forward osmosis (FO) was investigated with the aim of concentrating organic matters in sewage into a small volume of energy source. The results showed that chemical oxidation demand (COD) in the feed sewage solution was concentrated by more than 300%. Although a gradual decline in membrane flux with filtration time occurred, a flux of 3-7.4 L m -2 h -1 was still produced satisfactorily. The membrane flux decline was caused by both membrane fouling and the decline of osmotic driving force due to the salinity change in both feed solution and draw solution. The membrane fouling analysis indicated that the fouling was mainly attributed to the formation of cake layer on the membrane surface in both membrane orientation, the active layer facing the feed side (AL-FS) and the active layer facing the draw solution side (AL-DS). However, AL-FS outperformed AL-DS in terms of membrane flux and fouling. This study may offer new insight into the development of lowenergy wastewater treatment processes and energy recovery. 2 HighlightsOrganic matters in sewage can be effectively concentrated to small volume by FO.Membrane flux decline is caused by both membrane fouling and the decline of osmotic driving force.Cake layer is the dominant contributor to the membrane fouling.This study offers new insight into the development of low-energy wastewater treatment.

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Section: Membrane Fluxmentioning

confidence: 90%

Processing municipal wastewaters by forward osmosis using CTA membrane

Zhang

Ning

Wang

et al. 2014

Journal of Membrane Science

112

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“…To further understand the liquid water flux and salt rejection properties of GO-Gr membranes, we have performed forward osmosis (FO) 31,32 experiments. FO is relatively a new alternative technology to the conventional pressure-driven reverse osmosis (RO) membrane process, where hydraulic pressure is not required for its operation 31,32 .…”

Section: Swelling-controlled Graphene Oxide-graphene (Go-gr)membranesmentioning

confidence: 99%

“…FO is relatively a new alternative technology to the conventional pressure-driven reverse osmosis (RO) membrane process, where hydraulic pressure is not required for its operation 31,32 . In FO, a concentrated solution of a salt or other molecules (draw solution) is used to generate high osmotic pressure, which pulls the water molecules across a semi-permeable membrane from the low-concentration salt solution (feed solution), effectively filtering the feed water.…”

Section: Swelling-controlled Graphene Oxide-graphene (Go-gr)membranesmentioning

confidence: 99%

Tunable sieving of ions using graphene oxide membranes

et al. 2017

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Graphene oxide membranes show exceptional molecular permeation properties, with a promise for many applications. However, their use in ion sieving and desalination technologies is limited by a permeation cutoff of 9 Å, which is larger than hydrated ion diameters for common salts. The cutoff is determined by the interlayer spacing d 13.5 Å, typical for graphene oxide laminates that swell in water. Achieving smaller d for the laminates immersed in water has proved to be a challenge. Here we describe how to control d by physical confinement and achieve accurate and tuneable ion sieving. Membranes with d from  9.8 Å to 6.4 Å are demonstrated, providing the sieve size smaller than typical ions' hydrated diameters. In this regime, ion permeation is found to be thermally activated with energy barriers of 10-100 kJ/mol depending on d. Importantly, permeation rates decrease exponentially with decreasing the sieve size but water transport is weakly affected (by a factor of <2). The latter is attributed to a low barrier for water molecules entry and large slip lengths inside graphene capillaries. Building on these findings, we demonstrate a simple scalable method to obtain graphene-based membranes with limited swelling, which exhibit 97% rejection for NaCl.Selectively permeable membranes with sub-nm pores attract strong interest due to analogies with biological membranes and potential applications in water filtration, molecular separation and desalination [1][2][3][4][5][6][7][8] . Nanopores with sizes comparable to, or smaller than, the diameter D of hydrated ions are predicted to show enhanced ion selectivity 7,9-12 because of dehydration required to pass through such atomic-scale sieves. Despite extensive research on ion dehydration effects 3,7,9-13 , experimental investigation of the ion sieving controlled by dehydration has been limited because of difficulties in fabricating uniform membranes with well-defined sub-nm pores. The realisation of membranes with dehydration-assisted selectivity would be a significant step forward. So far, research into novel membranes has mostly focused on improving the water flux rather than ion selectivity. On the other hand, modelling of practically relevant filtration processes shows that an increase in water permeation rates above the rates currently achieved (2-3 L/m 2 ×h×bar) would not contribute greatly to the overall efficiency of desalination 8,14,15 . Alternative approaches based on higher water-ion selectivity may open new possibilities for improving filtration technologies, as the performance of state-of-the-art membranes is currently limited by the solution-diffusion mechanism, in which water molecules dissolve in the membrane material and then diffuses across the membrane 8 . Recently, carbon nanomaterials including carbon nanotubes (CNT)

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“…[32][33][34][35][36] Although FO exhibits a great potential in alleviating the issues caused by freshwater shortage, challenges, such as relatively low water permeability, high reverse solute diffusion, severe concentration polarization (CP), and membrane fouling, are still present in FO applications. [37][38][39] To eliminate these problems, exploration of appropriate semi-permeable FO membrane and draw solute is urgently needed. Great efforts have been made in the development of FO technology in recent years, and a wide range of powerful FO membranes and suitable draw solutes have been proposed to date.…”

mentioning

confidence: 99%

“…[35,37] Membrane fouling leads to a water flux decline as a result of the increase of water transport resistance when solutes attach on membrane surface or diffuse into membrane interior. [39,43] Properties of membrane surface, such as hydrophilicity, charged state, roughness and structure, are closely related to the membrane fouling formation. As most FO membranes are not perfectly semi-permeable, draw or feed solutes may diffuse to the opposite side during an FO process.…”

mentioning

confidence: 99%

Progress in Forward Osmosis Membrane Separation Process

Chen¹,

Xu²,

Ge³

2017

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Forward osmosis (FO) has been extensively investigated and demonstrated its advantages in a range of FO applications over the past decade. However, challenges still remain in terms of the lack of both efficient FO membranes and appropriate draw solutes for practical FO applications. To promote the advancement of FO technology, considerable efforts have been made in exploring novel FO membranes and draw solutes in recent years. This paper will provide a short review on the progress of both FO membranes and draw solutes. First of all, a brief overview on FO principle is given. Then the progress in FO technology related to FO membrane and draw solute is presented with specific examples. Finally, challenges and future directions of FO technology in exploring efficient FO membranes and promising draw solutes are also highlighted. This article may provide new insights into the future development of FO technology and promote practical FO applications.Keywords forward osmosis, draw solution, forward osmosis membrane, forward osmosis application IntroductionFreshwater shortage has been becoming a more and more severe problem globally. [1][2][3][4] To mitigate this problem, various technologies for clean water production have been explored worldwide recently. [5][6][7][8][9] Membrane technology has shown a great potential in water treatment in view of the advantages of no phase change, strong adaptability, relatively simple operation and low cost. [5,[10][11][12] A range of pressure-driven membrane processes, such as microfiltration (MF), [13][14][15][16] ultrafiltration (UF), [13,17,18] nanofiltration (NF), [19][20][21] and reverse osmosis (RO) [22][23][24][25][26] have been extensively used for clean water production through either wastewater reuse or brackish water/ seawater desalination. However, some issues, such as severe membrane fouling, low water recovery rate, intensive-energy consumption and relatively low quality of product water, occur frequently during these processes. [10,13,17,23,27] FO has been recognized as a promising membrane process because of the following characteristics: (1) no requirement of hydraulic pressure; (2) a relatively high water recovery rate; (3) low membrane fouling propensity due to the absence of hydraulic pressure; (4) environmental friendliness. Given these merits, FO technology has been applied to a wide range of fields, such as seawater/brackish water desalination, [4,24,28] wastewater treatment, [8,[29][30][31] and many other areas. [32][33][34][35][36] Although FO exhibits a great potential in alleviating the issues caused by freshwater shortage, challenges, such as relatively low water permeability, high reverse solute diffusion, severe concentration polarization (CP), and membrane fouling, are still present in FO applications. [37][38][39] To eliminate these problems, exploration of appropriate semi-permeable FO membrane and draw solute is urgently needed. Great efforts have been made in the development of FO technology in recent years, and a wide range of powerful FO membra...

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Recent developments in forward osmosis: Opportunities and challenges

Cited by 1,229 publications

References 199 publications

Processing municipal wastewaters by forward osmosis using CTA membrane

Processing municipal wastewaters by forward osmosis using CTA membrane

Tunable sieving of ions using graphene oxide membranes

Progress in Forward Osmosis Membrane Separation Process

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