A general, resistance-in-series, salt- and water flux models for forward osmosis and pressure-retarded osmosis for energy generation

Nagy, Endre

doi:10.1016/j.memsci.2014.02.021

Cited by 85 publications

(63 citation statements)

References 24 publications

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“…We take an approach similar to Nagy's model for flux in unfouled FO membranes [14], but incorporate the presence of a porous foulant layer with gradients in both hydraulic and osmotic pressure. We reduce the problem of quantification to two parameters: cake structural parameter (analogous to the support layer structural parameter in FO membranes) and pore hydraulic diameter.…”

Section: Existing Methods Of Quantifying Foulingmentioning

confidence: 99%

“…Real membranes and foulant layers may have indistinct and/or rough interfaces, but this model divides the flow path into distinct, planar layers, each with its own transport model. In many ways, the model developed here parallels the model of Nagy [14] for FO without fouling. Like Nagy, we model transport of a single salt in one dimension through several layers with their own appropriate models, but we add a layer of porous foulant on the feed-facing side of the membrane and also account for dispersion in the FO membrane support layer.…”

Section: Layered Transport Model For Fouled Ro and Fomentioning

confidence: 99%

“…We then describe transport through the remaining layers in FO, utilizing the approach of Nagy [14], and develop a similar model for fouled RO. Finally, we suggest a method for solving these systems of equations.…”

Section: Solutiondiffusionmentioning

confidence: 99%

“…Having defined a cake structural parameter, salt transport by convection and diffusion through the foulant layer can be modelled the same way as it is in the support layer in FO by Nagy [14]. The cake layer salt transport equation is given in Sec.…”

Section: Cake Structural Parametermentioning

confidence: 99%

“…Using stagnant film theory, Nagy [14] models salt transport through both feed and draw boundary layers in FO with the 1-D equation for mass transport by convection and diffusion: Incorporating a mass transfer coefficient and assuming quasi-steady flow and conserving species (i.e., prescribing constant, spatially uniform J s and J w ), Nagy [14] finds the following equations for salt transport in the feed and draw mass transfer boundary layers in FO:…”

Section: Fo Modelmentioning

confidence: 99%

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Quantifying osmotic membrane fouling to enable comparisons across diverse processes

Tow

Lienhard

2016

Journal of Membrane Science

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In this study, a method of in situ membrane fouling quantification is developed that enables comparisons of foulant accumulation between desalination processes with different membranes, driving forces, and feed solutions. Unlike the conventional metric of flux decline, which measures the response of a process to fouling, the proposed method quantifies the foulant accumulation. Foulant accumulation is parameterized by two variables, cake structural parameter and hydraulic diameter, that are calculated from flux measurements using a model for salt and water transport through fouled reverse osmosis (RO) and forward osmosis (FO) membranes, including dispersive mass transfer in the FO membrane support layer. Model results show that pressure declines through the foulant layer and can, in FO, reach negative absolute values at the membrane. Experimental alginate gel fouling rates are measured within a range of feed ionic compositions where cake hydraulic resistance is negligible. Using both flux decline and cake structural parameter as metrics, the effect of feed salinity on RO fouling is tested and RO is compared to FO. When RO is fouled with alginate, feed salinity and membrane permeability affect flux decline but not foulant accumulation rate. Between FO and RO, the initial rates of foulant accumulation are similar; however, FO exhibits slower flux decline, which causes greater foulant accumulation over time. The new methodology enables meaningful quantification and comparison of fouling rates with the aim of improving fundamental understanding of fouling processes.

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Section: Existing Methods Of Quantifying Foulingmentioning

confidence: 99%

Section: Layered Transport Model For Fouled Ro and Fomentioning

confidence: 99%

Section: Solutiondiffusionmentioning

confidence: 99%

Section: Cake Structural Parametermentioning

confidence: 99%

Section: Fo Modelmentioning

confidence: 99%

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