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Title: Improved performance of gravity-driven membrane filtration for seawater pretreatment: Implications of membrane module configuration
Authors: Tan, Hwee Sin
Hochstrasser, Florian
Wu, Bing
Christen, Tino
Suwarno, Stanislaus Raditya
Liu, Xin
Chong, Tzyy Haur
Burkhardt, Michael
Pronk, Wouter
Fane, Anthony Gordon
Keywords: Eukaryotes
Gravity-driven membrane filtration
Issue Date: 2017
Source: Wu, B., Christen, T., Tan, H. S., Hochstrasser, F., Suwarno, S. R., Liu, X., et al. (2017). Improved performance of gravity-driven membrane filtration for seawater pretreatment: Implications of membrane module configuration. Water Research, 114, 59-68.
Series/Report no.: Water Research
Abstract: As a low energy and chemical free process, gravity-driven membrane (GDM) filtration has shown a potential for seawater pretreatment in our previous studies. In this study, a pilot submerged GDM reactor (effective volume of 720 L) was operated over 250 days and the permeate flux stabilized at 18.6 ± 1.4 L/m2h at a hydrostatic pressure of 40 mbar. This flux was higher than those in the lab-scale GDM reactor (16.3 ± 0.2 L/m2h; effective volume of 8.4 L) and in the filtration cell system (2.7 ± 0.6 L/m2h; feed side volume of 0.0046 L) when the same flat sheet membrane was used. Interestingly, when the filtration cell was submerged into the GDM reactor, the flux (17.2 L/m2h) was comparable to the submerged membrane module. Analysis of cake layer morphology and foulant properties indicated that a thicker but more porous cake layer with less accumulation of organic substances (biopolymers and humics) contributed to the improved permeate flux. This phenomenon was possibly associated with longer residence time of organic substances and sufficient space for the growth, predation, and movement of the eukaryotes in the GDM reactor. In addition, the permeate flux of the submerged hollow fibre membrane increased with decreasing packing density. It is thought that the movement of large-sized eukaryotes could be limited when the space between hollow fibres was reduced. In terms of pretreatment, the GDM systems effectively removed turbidity, viable cells, and transparent exopolymer particles from the feed seawater. Importantly, extending the reactor operation time produced a permeate with less assimilable organic carbon and biopolymers. Thus, the superior quality of the GDM permeate has the potential to alleviate subsequent reverse osmosis membrane fouling for seawater treatment.
ISSN: 0043-1354
DOI: 10.1016/j.watres.2017.02.022
Schools: School of Civil and Environmental Engineering 
Research Centres: Nanyang Environment and Water Research Institute 
Rights: © 2017 Elsevier. This is the author created version of a work that has been peer reviewed and accepted for publication by Water Research, 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: [].
Fulltext Permission: open
Fulltext Availability: With Fulltext
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NEWRI Journal Articles

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