Exploring the limitations of osmotically assisted reverse osmosis: membrane fouling and the limiting flux

Osmotically assisted reverse osmosis (OARO) has shown great potential for low-cost and energy-efficient brine management. However, its performance can be significantly limited by membrane fouling. Here, we performed for the first time a comprehensive study on OARO membrane fouling, explored the asso...

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Main Authors: Peters, Christian D., Li, Dan, Mo, Zijing, Hankins, Nicholas P., She, Qianhong
Other Authors: School of Civil and Environmental Engineering
Format: Article
Language:English
Published: 2022
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Online Access:https://hdl.handle.net/10356/162437
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Institution: Nanyang Technological University
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spelling sg-ntu-dr.10356-1624372022-10-19T02:16:52Z Exploring the limitations of osmotically assisted reverse osmosis: membrane fouling and the limiting flux Peters, Christian D. Li, Dan Mo, Zijing Hankins, Nicholas P. She, Qianhong School of Civil and Environmental Engineering Interdisciplinary Graduate School (IGS) Nanyang Environment and Water Research Institute Singapore Membrane Technology Centre Engineering::Environmental engineering Osmotically Assisted Reverse Osmosis Membrane Fouling Osmotically assisted reverse osmosis (OARO) has shown great potential for low-cost and energy-efficient brine management. However, its performance can be significantly limited by membrane fouling. Here, we performed for the first time a comprehensive study on OARO membrane fouling, explored the associated fouling mechanisms, and evaluated fouling reversibility via simple physical cleaning strategies. First, internal membrane fouling at the draw (permeate) side was shown to be insignificant. Flux behavior in short-term operation was correlated to both the evolution of fouling and the change of internal concentration polarization. In long-term operation, membrane fouling constrained the OARO water flux to a singular, common upper limit, in terms of limiting flux, which was demonstrated to be independent of operating pressures and membrane properties. Generally, once the limiting flux was exceeded, the OARO process performance could not be improved by higher-pressure operation or by utilizing more permeable and selective membranes. Instead, different cyclic cleaning strategies were shown to be more promising alternatives for improving performance. While both surface flushing and osmotic backwashing (OB) were found to be highly effective when using pure water, a full flux recovery could not be achieved when a nonpure solution was used during OB due to severe internal clogging during OB. All in all, the presented findings provided significant implications for OARO operation and fouling control. Nanyang Technological University This research was supported by the Start-up Grant (SUG #002195-00001) for Q.S. from Nanyang Technological University. Furthermore, C.D. Peters and N.P. Hankins are grateful to the University of Bahrain (in the Kingdom of Bahrain) for granting a full scholarship to C.D. Peters. 2022-10-19T02:16:51Z 2022-10-19T02:16:51Z 2022 Journal Article Peters, C. D., Li, D., Mo, Z., Hankins, N. P. & She, Q. (2022). Exploring the limitations of osmotically assisted reverse osmosis: membrane fouling and the limiting flux. Environmental Science and Technology, 56(10), 6678-6688. https://dx.doi.org/10.1021/acs.est.2c00839 0013-936X https://hdl.handle.net/10356/162437 10.1021/acs.est.2c00839 35475365 2-s2.0-85129489499 10 56 6678 6688 en SUG #002195-00001 Environmental Science and Technology © 2022 American Chemical Society. All rights reserved.
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Environmental engineering
Osmotically Assisted Reverse Osmosis
Membrane Fouling
spellingShingle Engineering::Environmental engineering
Osmotically Assisted Reverse Osmosis
Membrane Fouling
Peters, Christian D.
Li, Dan
Mo, Zijing
Hankins, Nicholas P.
She, Qianhong
Exploring the limitations of osmotically assisted reverse osmosis: membrane fouling and the limiting flux
description Osmotically assisted reverse osmosis (OARO) has shown great potential for low-cost and energy-efficient brine management. However, its performance can be significantly limited by membrane fouling. Here, we performed for the first time a comprehensive study on OARO membrane fouling, explored the associated fouling mechanisms, and evaluated fouling reversibility via simple physical cleaning strategies. First, internal membrane fouling at the draw (permeate) side was shown to be insignificant. Flux behavior in short-term operation was correlated to both the evolution of fouling and the change of internal concentration polarization. In long-term operation, membrane fouling constrained the OARO water flux to a singular, common upper limit, in terms of limiting flux, which was demonstrated to be independent of operating pressures and membrane properties. Generally, once the limiting flux was exceeded, the OARO process performance could not be improved by higher-pressure operation or by utilizing more permeable and selective membranes. Instead, different cyclic cleaning strategies were shown to be more promising alternatives for improving performance. While both surface flushing and osmotic backwashing (OB) were found to be highly effective when using pure water, a full flux recovery could not be achieved when a nonpure solution was used during OB due to severe internal clogging during OB. All in all, the presented findings provided significant implications for OARO operation and fouling control.
author2 School of Civil and Environmental Engineering
author_facet School of Civil and Environmental Engineering
Peters, Christian D.
Li, Dan
Mo, Zijing
Hankins, Nicholas P.
She, Qianhong
format Article
author Peters, Christian D.
Li, Dan
Mo, Zijing
Hankins, Nicholas P.
She, Qianhong
author_sort Peters, Christian D.
title Exploring the limitations of osmotically assisted reverse osmosis: membrane fouling and the limiting flux
title_short Exploring the limitations of osmotically assisted reverse osmosis: membrane fouling and the limiting flux
title_full Exploring the limitations of osmotically assisted reverse osmosis: membrane fouling and the limiting flux
title_fullStr Exploring the limitations of osmotically assisted reverse osmosis: membrane fouling and the limiting flux
title_full_unstemmed Exploring the limitations of osmotically assisted reverse osmosis: membrane fouling and the limiting flux
title_sort exploring the limitations of osmotically assisted reverse osmosis: membrane fouling and the limiting flux
publishDate 2022
url https://hdl.handle.net/10356/162437
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