Combined organic and colloidal fouling in forward osmosis: Fouling reversibility and the role of applied pressure

Kim, Y; Elimelech, M; Shon, HK; Hong, S

Combined organic and colloidal fouling in forward osmosis: Fouling reversibility and the role of applied pressure

Kim, Y Elimelech, M Shon, HK

Hong, S

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Publication Type:: Journal Article
Citation:: Journal of Membrane Science, 2014, 460 pp. 206 - 212
Issue Date:: 2014-06-15

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Field	Value	Language
dc.contributor.author	Kim, Y	en_US
dc.contributor.author	Elimelech, M	en_US
dc.contributor.author	Shon, HK https://orcid.org/0000-0002-3777-7169	en_US
dc.contributor.author	Hong, S	en_US
dc.date.issued	2014-06-15	en_US
dc.identifier.citation	Journal of Membrane Science, 2014, 460 pp. 206 - 212	en_US
dc.identifier.issn	0376-7388	en_US
dc.identifier.uri	http://hdl.handle.net/10453/122372
dc.description.abstract	In this study, we systematically investigated the propensity and reversibility of combined organic-colloidal fouling in forward osmosis (FO) under various solution chemistries (pH and calcium ion concentrations) and applied hydraulic pressure on the feed side. Alginate, silica colloids, and their mixture (i.e., combined organic-colloidal) were used as model foulants. Our findings demonstrate that combined organic-colloidal foulants caused more rapid flux decline than the individual foulants due to the synergistic effect of alginate and silica colloids. As a result, much lower flux recovery was achieved by physical cleaning induced by increasing the cross-flow rate, in contrast to single foulants of which the fouling layer was easily removed under all solution conditions. Interestingly, less flux decline was observed at neutral pH for combined fouling, while acidic conditions were favorable for alginate fouling and basic solutions caused more silica fouling, thereby providing clear evidence for the combined fouling effect. It was also found that calcium ions enhanced water flux decline and induced the formation of less reversible combined organic-colloidal fouling layers. Lastly, the role of applied hydraulic pressure on the feed side in FO was examined to elucidate the mechanism of fouling layer formation, fouling reversibility, and water flux recovery. Higher fouling propensity and lower fouling reversibility of combined organic-colloidal fouling were observed in the presence of applied hydraulic pressure on the feed side. This observation suggests that the lower fouling propensity and greater fouling reversibility in FO compared to reverse osmosis (RO), are attributable to unpressurized operating conditions in FO. © 2014 Elsevier B.V.	en_US
dc.relation.ispartof	Journal of Membrane Science	en_US
dc.relation.isbasedon	10.1016/j.memsci.2014.02.038	en_US
dc.subject.classification	Chemical Engineering	en_US
dc.title	Combined organic and colloidal fouling in forward osmosis: Fouling reversibility and the role of applied pressure	en_US
dc.type	Journal Article
utslib.citation.volume	460	en_US
utslib.for	090404 Membrane and Separation Technologies	en_US
utslib.for	0904 Chemical Engineering	en_US
utslib.for	03 Chemical Sciences	en_US
utslib.for	09 Engineering	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Civil and Environmental Engineering
pubs.organisational-group	/University of Technology Sydney/Strength - CTWW - Centre for Technology in Water and Wastewater Treatment
utslib.copyright.status	open_access
pubs.declined	1970-01-01T00:00:00.0+1000
pubs.deleted	1970-01-01T00:00:00.0+1000
pubs.publication-status	Published	en_US
pubs.volume	460	en_US

Abstract:

In this study, we systematically investigated the propensity and reversibility of combined organic-colloidal fouling in forward osmosis (FO) under various solution chemistries (pH and calcium ion concentrations) and applied hydraulic pressure on the feed side. Alginate, silica colloids, and their mixture (i.e., combined organic-colloidal) were used as model foulants. Our findings demonstrate that combined organic-colloidal foulants caused more rapid flux decline than the individual foulants due to the synergistic effect of alginate and silica colloids. As a result, much lower flux recovery was achieved by physical cleaning induced by increasing the cross-flow rate, in contrast to single foulants of which the fouling layer was easily removed under all solution conditions. Interestingly, less flux decline was observed at neutral pH for combined fouling, while acidic conditions were favorable for alginate fouling and basic solutions caused more silica fouling, thereby providing clear evidence for the combined fouling effect. It was also found that calcium ions enhanced water flux decline and induced the formation of less reversible combined organic-colloidal fouling layers. Lastly, the role of applied hydraulic pressure on the feed side in FO was examined to elucidate the mechanism of fouling layer formation, fouling reversibility, and water flux recovery. Higher fouling propensity and lower fouling reversibility of combined organic-colloidal fouling were observed in the presence of applied hydraulic pressure on the feed side. This observation suggests that the lower fouling propensity and greater fouling reversibility in FO compared to reverse osmosis (RO), are attributable to unpressurized operating conditions in FO. © 2014 Elsevier B.V.

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http://hdl.handle.net/10453/122372