Direct microscopic observation of forward osmosis membrane fouling by microalgae: Critical flux and the role of operational conditions

Zou, Shan; Wicaksana, Filicia; Aung, Theingi; Wong, Philip Chuen Yung; Fane, Anthony G.; Tang, Chuyang Y.

doi:10.1016/j.memsci.2013.02.030

Cited by 130 publications

(88 citation statements)

References 49 publications

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“…These findings revealed a negative effect of using feed spacer on algae dewatering efficacy due to the easy accumulation of algal cells inside spacer. However, the beneficial effect of feed spacer is well known for both pressure-driven and osmotically driven membrane filtration thanks to the improved mass transfer (and thus the reduced external concentration polarization effect) over the membrane surface [44]. Hence, in the application FO for algae dewatering, feed spacer needs to be further optimized in terms of material and geometry to reduce the risk of cell accumulation into the spacer and enhance mass transfer over the membrane surface in the feed channel.…”

Section: Effect Of Feed Spacer On Algae Dewateringmentioning

confidence: 99%

Microalgae (Scenedesmus obliquus) dewatering using forward osmosis membrane: Influence of draw solution chemistry

Larronde-Larretche

Jin

2016

Algal Research

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Section: Effect Of Feed Spacer On Algae Dewateringmentioning

confidence: 99%

Microalgae (Scenedesmus obliquus) dewatering using forward osmosis membrane: Influence of draw solution chemistry

Larronde-Larretche

Jin

2016

Algal Research

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“…Previous attempts were made to observe FO fouling processes directly by optical microscopy, 4 involving various foulants, such as algae [18], latex particles [19], and gypsum-alginate mixture [20]. These observations provided information on surface coverage and morphology of FO fouling layers on the membrane surface.…”

Section: Introductionmentioning

confidence: 99%

Role of pressure in organic fouling in forward osmosis and reverse osmosis

Xie

Lee

Nghiem

et al. 2015

Journal of Membrane Science

181

108

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Fundamental understanding of membrane fouling in osmosis-driven membrane processes is important for further deployment of this emerging technology in desalination and wastewater reuse. In this study, we investigated the role of pressure in organic fouling and reversibility in forward osmosis (FO) and reverse osmosis (RO) using alginate as a model organic foulant. Varying contributions of pressure (i.e., osmotic versus hydraulic) to the overall driving force were realized in forward osmosis (FO), pressure-assisted FO (PFO), and reverse osmosis (RO) experiments, while the same total driving force for water permeation was applied. Confocal laser scanning microscopy was used to examine alginate fouling layer structure in the hydrated state, which informed two key parameters: fouling layer thickness and foulant volume. We observed that the resulting fouling layer became increasingly more compact in the order of FO, PFO, and RO experiments. Fouling layer reversibility followed the same trend, with the highest and lowest reversibility observed for the FO and RO fouling experiments, respectively. Possible mechanisms for fouling layer compaction in RO were discussed, including permeate drag force and foulant compressibility, as opposed to FO where only permeate drag force applies. Our findings suggest that pressure mechanistically alters the membrane fouling layer structure and fouling reversibility, leading to higher fouling reversibility in FO, where the driving force is osmotic pressure, than RO, where the driving force is hydraulic pressure. ABSTRACTFundamental understanding of membrane fouling in osmosis-driven membrane processes is important for further deployment of this emerging technology in desalination and wastewater reuse. In this study, we investigated the role of pressure in organic fouling and reversibility in forward osmosis (FO) and reverse osmosis (RO) using alginate as a model organic foulant.Varying contributions of pressure (i.e., osmotic versus hydraulic) to the overall driving force were realized in forward osmosis (FO), pressure-assisted FO (PFO), and reverse osmosis (RO) experiments, while the same total driving force for water permeation was applied. Confocal laser scanning microscopy (CLSM) was used to examine alginate fouling layer structure in the hydrated state, which informed two key parameters: fouling layer thickness and foulant volume.We observed that the resulting fouling layer became increasingly more compact in the order of FO, PFO, and RO experiments. Fouling layer reversibility followed the same trend, with the highest and lowest reversibility observed for the FO and RO fouling experiments, respectively.Possible mechanisms for fouling layer compaction in RO were discussed, including permeate drag force and foulant compressibility, as opposed to FO where only permeate drag force applies. Our findings suggest that pressure mechanistically alters the membrane fouling layer structure and fouling reversibility, leading to higher fouling reversibility in FO, where the driving fo...

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“…Membrane fouling in the FO process is a complex phenomenon which is affected by the combined effect of several factors including operating modes and hydrodynamics, membrane and foulant characteristics, feed water solution chemistry, and draw solution properties [10,11,[25][26][27][28][29][30]. In an early study by Mi and Elimelech [27], the role of various physical and chemical interactions, such as intermolecular adhesion forces, calcium binding, initial permeate flux, and membrane orientation, was first tackled in the organic fouling of FO membranes.…”

Section: Introductionmentioning

confidence: 99%

Organic fouling mechanisms in forward osmosis membrane process under elevated feed and draw solution temperatures

et al. 2015

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Direct microscopic observation of forward osmosis membrane fouling by microalgae: Critical flux and the role of operational conditions

Cited by 130 publications

References 49 publications

Microalgae (Scenedesmus obliquus) dewatering using forward osmosis membrane: Influence of draw solution chemistry

Microalgae (Scenedesmus obliquus) dewatering using forward osmosis membrane: Influence of draw solution chemistry

Role of pressure in organic fouling in forward osmosis and reverse osmosis

Organic fouling mechanisms in forward osmosis membrane process under elevated feed and draw solution temperatures

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