Comparison of fouling behavior in forward osmosis (FO) and reverse osmosis (RO)

Lee, Sangyoup; Boo, Chanhee; Elimelech, Menachem; Hong, Seungkwan

doi:10.1016/j.memsci.2010.08.036

Cited by 683 publications

(445 citation statements)

References 30 publications

(35 reference statements)

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“…Many fouling studies are concerned with comparisons, such as the relative fouling propensity of FO vs. RO [5], pressurized vs. unpressurized FO [6,7], or new membrane coatings vs. commercial membranes [8]. Although flux decline comparisons often keep initial flux constant because of the dependence of fouling rate on flux [9], differences in membrane properties and solution composition can lead to differences in flux decline between experiments even if the foulant layers are identical in size and structure.…”

Section: Limitations Of Flux Declinementioning

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: Limitations Of Flux Declinementioning

confidence: 99%

“…As an example, Lee et al [5] compare fouling with colloidal silica and various dissolved organics in FO and RO, and find that FO has more severe flux decline in most cases.…”

Section: Limitations Of Flux Declinementioning

confidence: 99%

Quantifying osmotic membrane fouling to enable comparisons across diverse processes

Tow

Lienhard

2016

Journal of Membrane Science

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“…For example, FO is reported to be more resistant to fouling than RO [2,29,30], and it has been shown that membrane fouling is more easily reversible in FO than in RO operated under similar conditions [31].…”

Section: Assessment Of Technologiesmentioning

confidence: 99%

Raising forward osmosis brine concentration efficiency through flow rate optimization

2015

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An exergetic efficiency is defined in order to compare brine concentration processes including forward osmosis (FO) across a wide range of salinities. We find that existing FO pilot plants have lower efficiency than reverse osmosis plants in the brackish and seawater salinity ranges. High salinity FO, in its current form, is still less efficient than mechanical vapor compression. We show that efficiency is the product of FO exchanger and draw regenerator efficiencies, and therefore FO system energy efficiency benefits from improvements to both. The mass flow rate ratio (between draw and feed flow rates) is identified as a crucial parameter in the design of efficient FO systems because of its effect on exchanger efficiency. We demonstrate a method of thermodynamically balancing an FO system by choosing flow rates that lead to equal osmotic pressure differences at both ends of the exchanger, and show the method's potential to increase efficiency by 3-21% based on current system designs.

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“…FO operates at virtually zero (or very low) hydraulic pressure. As a result, it has a lower membrane fouling propensity and the fouling is much more controllable than pressure-driven membrane processes such as nanofiltration and reverse osmosis (Lee et al, 2010). The configuration of an FO system can be very simple because only minimal hydraulic pressure is required in the FO process to overcome flow resistance in the membrane module.…”

Section: Introductionmentioning

confidence: 99%

Performance of a novel osmotic membrane bioreactor (OMBR) system: Flux stability and removal of trace organics

Alturki

McDonald

Khan

et al. 2012

Bioresource Technology

169

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. b s t r a c tResults reported here highlight the potential and several challenges in the development of a novel osmotic membrane bioreactor (OMBR) process for the treatment of municipal wastewater. Following the initial gradual decline, a stable permeate flux value was obtained after approximately four days of continuous operation. There was evidence of continuous deterioration of biological activity of the OMBR system, possibly due to the build-up of salinity in the reactor. The removal of 25 out of 27 trace organic compounds with molecular weight higher than 266 g/mol was above 80% and was possibly governed by the interplay between physical separation of the FO membrane and biodegradation. In contrast, the removal efficiency values of the other 23 trace organic compounds with molecular weight less than 266 g/mol were very scattered. The removal efficiency of these low molecular weight compounds by OMBR treatment appears to depend mostly on biological degradation. Crown

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Comparison of fouling behavior in forward osmosis (FO) and reverse osmosis (RO)

Cited by 683 publications

References 30 publications

Quantifying osmotic membrane fouling to enable comparisons across diverse processes

Quantifying osmotic membrane fouling to enable comparisons across diverse processes

Raising forward osmosis brine concentration efficiency through flow rate optimization

Performance of a novel osmotic membrane bioreactor (OMBR) system: Flux stability and removal of trace organics

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