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arXiv · 1809.00217

Rough or Wiggly? Membrane Topology and Morphology for Fouling Control

Bowen Ling·Ilenia Battiato
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Abstract

Reverse Osmosis Membrane (ROM) filtration systems are widely applied in wastewater recovery, seawater desalination, landfill water treatment, etc. During filtration, the system performance is dramatically affected by membrane fouling which causes a significant decrease in permeate flux as well as an increase in the energy input required to operate the system. Design and optimization of ROM filtration systems aim at reducing membrane fouling by studying the coupling between membrane structure, local flow field, local solute concentration and foulant adsorption patterns. Yet, current studies focus exclusively on oversimplified steady-state models that ignore any dynamic coupling between the fluid dynamics and the transport through the membrane, while membrane design still proceeds through trials and errors. In this work, we develop a model that couples the transient Navier-Stokes and the Advection-Diffusion-Equations, as well as an adsorption-desorption equation for the foulant accumulation, and we validate it against unsteady measurements of permeate flux as well as steady-state spatial fouling patterns. Furthermore, we analytically show that, for a straight channel, a universal scaling relationship exists between the Sherwood and Bejam numbers. We then generalize this result to membranes subject to morphological and/or topological modifications. We demonstrate that universal scaling behavior can be identified through the definition of a modified Reynolds number, that accounts for the additional length scales introduced by the membrane modifications, and a membrane performance index, which represents an aggregate efficiency measure with respect to both clean permeate flux and energy input required to operate the system.

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BibTeXRIS

Bowen Ling, Ilenia Battiato. 2018-09-01. Rough or Wiggly? Membrane Topology and Morphology for Fouling Control. https://doi.org/10.1017/jfm.2018.965

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