Validation of assisted forward osmosis (AFO) process: Impact of hydraulic pressure

Blandin, Gaëtan; Verliefde, Arne; Tang, Chuyang Y.; Childress, Amy E.; Le‐Clech, Pierre

doi:10.1016/j.memsci.2013.06.002

Cited by 112 publications

(60 citation statements)

References 48 publications

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“…8 that the SRSF generally decreases with the increase in the applied pressure for all the membrane samples tested in the study. Similar results have been confirmed through a previous study on the PAO process which is in contrast to the conventional FO process [9,12]. The reverse solute flux is basically a function of the effective concentration differences at the membrane surface and the membrane salt rejection properties.…”

Section: Performance Of Membranes Under the Pao Processsupporting

confidence: 88%

“…Recently, combined processes of applied hydraulic pressure and osmosis have been reported with an attempt to exploit the synergies of the two processes in a single stage to overcome low flux in the FO process even generating water flux beyond osmotic equilibrium point [9][10][11]. The concept of pressure assisted osmosis (PAO) is in fact a hybridisation of the FO process and the RO process where the intrinsic loss of osmotic driving force in the FO process is supplemented by the external hydraulic pressure applied to the FO system.…”

Section: Introductionmentioning

confidence: 99%

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Thin-film composite membrane on a compacted woven backing fabric for pressure assisted osmosis

et al. 2017

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TFC membrane supported on backing fabric was fabricated for PAO process.• RO and FO membrane casting methods were investigated. • PAO membrane had a higher S value compared to FO membranes. • PAO membrane had a higher water permeability compared to FO membranes. • Developed PAO membrane can sustain applied hydraulic pressure.The water flux in forward osmosis (FO) process declines substantially when the draw solution (DS) concentration reaches closer to the point of osmotic equilibrium with the feed solution (FS). Using external hydraulic pressure alongside the osmotic driving force in the pressure assisted osmosis (PAO) has been found effective in terms of enhancing water flux and even potentially diluting the DS beyond osmotic equilibrium. The net gain in water flux due to the applied pressure in the PAO process closely depends on the permeability of the FO membrane. The commercial flat sheet cellulose triacetate (CTA) FO membrane has low water permeability and hence the effective gain in water flux in the PAO process is low. In this study, a high performance thin film composite membrane was developed especially for the PAO process through casting polyethersulfone (PES) polymer solution on a compacted woven fabric mesh support followed by interfacial polymerisation for polyamide active layer. This PAO membrane possesses a water flux of 37 L m 2 h −1 using 0.5 M NaCl as DS and deionised water as the feed at an applied hydraulic pressure of 10 bar. Besides, the membrane was able to endure the external hydraulic pressure required for the PAO process owing to the embedded backing fabric support. While the membranes with low structural parameters are essential for higher water flux, this study shows that for PAO process, polymeric

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Section: Performance Of Membranes Under the Pao Processsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Thin-film composite membrane on a compacted woven backing fabric for pressure assisted osmosis

et al. 2017

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“…Various desalination technologies operate at elevated pressures: UF operates in the range of 0 to 0.5 MPa [6], NF from 0.035 to 4.0 MPa [7][8][9], brackish reverse osmosis operates in the range of 1.0 to 4.0 MPa [7], and seawater reverse osmosis (SWRO) in the range of 5.5 to 8.5 MPa [7]. Osmotically driven processes such as Pressure Retarded Osmosis (PRO) and the more recently introduced Assisted Forward Osmosis (AFO) may experience pressures above 4.7 MPa [10,11] and 0.6 MPa 7 respectively [12]. Unconventional reverse osmosis configurations have also recently been investigated for treating oil and gas produced water to salinities near saturation values of 260 g/kg and pressures near 30 MPa [13].…”

Section: Been Made By the International Association For The Propertiementioning

confidence: 99%

Thermophysical properties of seawater: A review and new correlations that include pressure dependence

et al. 2016

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In a previous paper, the authors have given correlations for seawater thermophysical properties as functions of temperature and salinity, but only for near atmospheric pressures. Seawater reverse osmosis (SWRO) systems operate routinely at pressures of 6 MPa or more; however, experimental data for seawater properties at elevated pressures (P = 0.1-12 MPa) are limited to a salinity of 56 g/kg. To accurately model and design SWRO and thermal desalination systems, a reliable method of estimating the effect of pressure on seawater properties is required. In this work, we present this method and new correlations for seawater thermophysical properties that are valid within the range: t = 0-120 °C, S = 0-120 g/kg, and P = 0-12 MPa. Seawater isothermal compressibility data, available until a salinity of 56 g/kg, were used to develop a correlation for compressibility that is extrapolated to 160 g/kg. Thermodynamic identities were then used to develop accurate pressure dependent correlations for seawater: density, isobaric expansivity, specific heat capacity, enthalpy, entropy and Gibbs energy. New correlations were proposed for 2 surface tension and osmotic coefficient were reviewed. Uncertainty bounds were calculated for each correlation.

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“…The PAO concept relies on the application of hydraulic pressure on the feed side of the membrane to enhance permeation flux through the synergistic effects of hydraulic and osmotic pressures [26][27][28]. It has been demonstrated that despite resulting in enhanced ICP, an important water flux improvement (up to 70% for feed pressure of 6 bar) was observed using pure water as feed, thanks to the direct impact of hydraulic pressure as an additional driving force and its indirect effect on membrane structure through deformation and stretching [26]. In this aspect, PAO could be implemented to compensate the decrease in osmotic driving force typically observed with increasing recovery, and thus to allow higher recovery of impaired water in the context of a PAO/RO hybrid process with wastewater as feed.…”

Section: Introductionmentioning

confidence: 99%

Pressure enhanced fouling and adapted anti-fouling strategy in pressure assisted osmosis (PAO)

Blandin

Verliefde

Le‐Clech

2015

Journal of Membrane Science

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Validation of assisted forward osmosis (AFO) process: Impact of hydraulic pressure

Cited by 112 publications

References 48 publications

Thin-film composite membrane on a compacted woven backing fabric for pressure assisted osmosis

Thin-film composite membrane on a compacted woven backing fabric for pressure assisted osmosis

Thermophysical properties of seawater: A review and new correlations that include pressure dependence

Pressure enhanced fouling and adapted anti-fouling strategy in pressure assisted osmosis (PAO)

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