Biofouling in reverse osmosis processes : the roles of flux, crossflow velocity and concentration polarization in biofilm development
Author
Suwarno, S. R.
Chen, X.
Chong, T. H.
McDougald, D.
Cohen, Y.
Rice, S. A.
Fane, Anthony Gordon
Date of Issue
2014School
School of Civil and Environmental Engineering
School of Biological Sciences
School of Biological Sciences
Research Centre
Singapore Membrane Technology Centre
Version
Accepted Version
Abstract
Biofilm development in a spacer-filled reverse osmosis membrane channel can influence both trans-membrane pressure (TMP) and channel pressure drop (ΔPCH). While current pretreatment methods are unable to completely tackle the biofouling problem, more insights are required to provide strategies to minimize the problem. This study examined the role of operating parameters (i.e. flux and crossflow velocity) to minimize biofouling in RO processes. The experiments were conducted with a lab-scale high pressure flat sheet RO reactor where changes in pressure drop along the channel and across the membrane were measured. The impact of biofouling was measured at constant fluxes, where the TMP rise and ΔPCH rise and the biofoulant was quantified as biovolumes of live and dead bacteria on autopsied membrane and spacer samples by confocal laser scanning microscopy (CLSM).
The results show that TMP rise increased exponentially with increasing flux, and decreased with increasing crossflow velocity. The channel pressure drop, ΔPCH, increased when either flux or crossflow velocity was increased, and was more dependent on crossflow. The biofoulant volume on the membrane increased with flux and was less dependent on crossflow. The biofoulant associated with the spacer was much less than on the membrane and relatively insensitive to flux or crossflow velocity.
The TMP rise could be correlated with the estimated concentration of nutrient at the membrane surface, Cw,N, highlighting the combined roles of flux and crossflow velocity in solute concentration polarization. Previous TMP rise data could also be correlated to the estimated Cw,N values. This observation suggests a biofouling mitigation strategy by controlling both incoming nutrient concentration and operating conditions (flux and crossflow).
Subject
DRNTU::Science::Biological sciences
Type
Journal Article
Series/Journal Title
Journal of membrane science
Rights
© 2014 Elsevier. This is the author created version of a work that has been peer reviewed and accepted for publication by Journal of Membrane Science, Elsevier. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/ 10.1016/j.memsci.2014.04.052].
Collections
http://dx.doi.org/10.1016/j.memsci.2014.04.052
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