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Improved performance of gravity-driven membrane filtration for seawater pretreatment: Implications of membrane module configuration
- Source :
- Water research. 114
- Publication Year :
- 2016
-
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. EDB (Economic Devt. Board, S’pore) Accepted version
- Subjects :
- Environmental Engineering
Eukaryotes
0208 environmental biotechnology
Hydrostatic pressure
02 engineering and technology
010501 environmental sciences
Osmosis
01 natural sciences
law.invention
Water Purification
law
Seawater
Reverse osmosis
Waste Management and Disposal
Filtration
0105 earth and related environmental sciences
Water Science and Technology
Civil and Structural Engineering
Chromatography
Fouling
Chemistry
Ecological Modeling
Membrane fouling
Eukaryota
Membranes, Artificial
Permeation
Pollution
020801 environmental engineering
Membrane
Chemical engineering
Gravity-driven membrane filtration
Gravitation
Subjects
Details
- ISSN :
- 18792448
- Volume :
- 114
- Database :
- OpenAIRE
- Journal :
- Water research
- Accession number :
- edsair.doi.dedup.....4bdf28de126b62f9c6ff8adb309cc47f