Mass transfer in the membrane concentration polarization layer under turbulent cross flow

Gekas, Vassilis; Hallström, B.

doi:10.1016/s0376-7388(00)81349-6

Cited by 370 publications

(45 citation statements)

References 35 publications

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“…They attributed this negative flux to the osmotic pressure created by the localized high salinity at the membrane surface on the feed side due to the deposited salt layer. Franken et al [114] observed a 30% decay in DCMD flux over a period of one month and postulated that this must be a result of membrane wetting and possibly "back flow." Laganá et al [115] has also reported a similar phenomenon.…”

Section: Wetting and Permeate Water Quality Changementioning

confidence: 99%

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Scaling and fouling in membrane distillation for desalination applications: A review

et al. 2015

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Section: Wetting and Permeate Water Quality Changementioning

confidence: 99%

“…Gryta [28,114] reported the efficacy of HCl rinsing in restoring flux back to original value in the case of membranes with CaCO3 scale layer. However, after repeating the washing procedure with 2-5% HCl, Gryta found that maximum restored flux declined [111].…”

Section: Membrane Cleaningmentioning

confidence: 99%

Scaling and fouling in membrane distillation for desalination applications: A review

et al. 2015

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“…The mass transfer coefficient is commonly calculated using Sherwood (Sh) number relations which are empirical correlations as a function of Reynolds Schmidt numbers [13]. The Sh number relationships available in the literature were either adapted from the analogy between heat and mass transfer or were derived for flow in non-porous smooth [13][14][15]. These relations were later modified for the ultrafiltration (UF) experiments [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…The Sh number relationships available in the literature were either adapted from the analogy between heat and mass transfer or were derived for flow in non-porous smooth [13][14][15]. These relations were later modified for the ultrafiltration (UF) experiments [13,14]. UF is a pressure-driven process with a different flow hydrodynamics from FO process which is driven by the osmotic pressure gradient.…”

Section: Introductionmentioning

confidence: 99%

Effect of Internal and External Concentration Polarizations on the Performance of Forward Osmosis Process

Bhinder¹,

Shabani²,

Sadrzadeh³

2018

Osmotically Driven Membrane Processes - Approach, Development and Current Status

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Forward osmosis (FO) as an osmotically driven membrane process is severely affected by the concentration polarization phenomenon on both sides of the membrane as well as inside the support layer. Though the effect of internal concentration polarization (ICP) in the porous support on the draw solution side is far more pronounced than that of the external concentration polarization (ECP), still the importance of ECP cannot be neglected. The ECP becomes particularly important when the feed flow rate is enhanced to increase the permeation flux by increasing the agitation and turbulence on the membrane surface. To capture the effect of ECP a suitable value of mass transfer coefficient must be determined. In this chapter, an FO mass transport model that accounts for the presence of both ICP and ECP phenomena is first presented on the basis of solution-diffusion model coupled with diffusion-convection. Then, three methods for the estimation of mass transfer coefficient based on empirical Sherwood (Sh) number correlations, pressure-driven reverse osmosis (RO), and osmosis-driven pressure retarded osmosis (PRO) are proposed. Finally, a methodology for the prediction of water flux through FO membranes using the theoretical model and calculated/measured parameters (hydraulic permeability, salt resistivity of the support layer, and mass transfer coefficient) is presented.

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“…Manipulating the operating conditions can lessen the severity of concentration polarization [Gekas and Hallstrom, 1987;Cheryan, 1998;Hargrove and Ilias, 1999]. The membrane fouling refers to the deposition of some feed components on the membrane surface and within the network of membrane pores.…”

Section: Introductionmentioning

confidence: 99%

Flux Enhancement in Crossflow Membrane Filtration: Fouling and It's Minimization by Flow Reversal

Ilias¹

2005

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Fouling problems are perhaps the single most important reason for relatively slow acceptance of ultrafiltration in many areas of chemical and biological processing. To overcome the losses in permeate flux associated with concentration polarization and fouling in cross flow membrane filtration, we investigated the concept of flow reversal as a method to enhance membrane flux in ultrafiltration. Conceptually, flow reversal prevents the formation of stable hydrodynamic and concentration boundary layers at or near the membrane surface. Further more, periodic reversal of the flow direction of the feed stream at the membrane surface results in prevention and mitigation of membrane fouling. Consequently, these advantages are expected to enhance membrane flux significantly.A crossflow membrane filtration unit was designed and built to test the concept of periodic flow reversal for flux enhancement. The essential elements of the system include a crossflow hollow fiber membrane module integrated with a two-way valve to direct the feed flow directions. The two-way valve is controlled by a controller-timer for periodic reversal of flow of feed stream. Another important feature of the system is that with changing feed flow direction, the permeate flow direction is also changed to maintain countercurrent feed and permeate flows for enhanced mass transfer driving force (concentration difference).Three feed solutions (Bovine serum albumin (BSA), apple juice and citrus fruit pectin) were studied in crossflow membrane filtration. These solutes are well-known in membrane filtration for their fouling and concentration polarization potentials. Laboratory-scale tests on a hollow-fiber ultrafiltration membrane module using each of the feed solutes show that under flow reversal conditions, the permeate flux is significantly enhanced when compared with the conventional unidirectional flow. The flux enhancement is dramatic (by an order of magnitude) with increased feed concentration and operating transmembrane pressure. Thus, flow reversal technology seems an attractive alternative to mitigate fouling problem in crossflow membrane filtration.iv

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Mass transfer in the membrane concentration polarization layer under turbulent cross flow

Cited by 370 publications

References 35 publications

Scaling and fouling in membrane distillation for desalination applications: A review

Scaling and fouling in membrane distillation for desalination applications: A review

Effect of Internal and External Concentration Polarizations on the Performance of Forward Osmosis Process

Flux Enhancement in Crossflow Membrane Filtration: Fouling and It's Minimization by Flow Reversal

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