Characteristics of permeate-side spacers of spiral wound membrane modules

• Published in: Desalination 2013-08, Vol.322, p.131-136
• Main Authors: Koutsou, C.P., Karabelas, A.J., Goudoulas, T.B.
• Format: Article
• Language: English
• Subjects: Applied sciences; artificial membranes; Chemical engineering; desalination; Drinking water and swimming-pool water. Desalination; Effective permeability; Exact sciences and technology; Hydrodynamics of contact apparatus; permeability; Permeate-side spacer; Pollution; pressure; SWM design and performance optimization; SWM module; Water desalination; Water treatment and pollution
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2013.05.015

Reliable estimates of the effective lateral permeability (k) of permeate-side spacers of spiral wound membrane (SWM) elements are required in order to design them and simulate module and plant performance. Such permeability data are not available at present. A straightforward approach is recommended for determining k of spacers under modest pressure, which involves pressure drop measurements in a spacer-filled channel coupled with separate accurate data on the effect of normal pressure on spacer thickness. Application of this approach to typical spacers from commercial SWM modules shows that k is at the level of 2 to 3.5×10−10m2, for measured thickness 0.20 to 0.25mm. The tested spacers exhibit modest compaction under pressure, with a tendency to approach asymptotically a minimum thickness at a pressure smaller than that prevailing in tightly wound membrane envelopes of commercial modules. Recommendations are also outlined regarding R & D directions on the selection of appropriate permeate spacers in the context of overall optimization of SWM module design and desalination process performance. •Methodology for accurate determination of permeate-side spacer permeability.•Typical effective lateral permeabilities of SWM spacers reported for the first time.•Spacer/fabric thickness variation with imposed pressure accurately measured.•Permeate-side permeabilities are essential for SWM design/performance simulation.