This research focuses on the design of small protrusions (micromixers)
fabricated on reverse-osmosis membranes with the objective of reducing
biofouling by increasing the amount of turbulent mixing along the membrane
surface. Micromixers have been experimentally and computationally shown
to induce chaotic mixing and increase shear stress on the membrane
Membrane-based separation processes, such as reverse osmosis
(RO) and ultra- or nano-filtration, are commonly used in industrial
applications such as desalination, waste-water treatment, and
Major problems associated with membrane-based
separation processes include fouling and high pressure loss,
which decrease the efficiency of the filtration, decrease membrane
lifetime, and increase operation costs.
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Computational fluid dynamics models were developed to simulate flow
patterns and mass transfer in the feed channel with membranes consisting
of different patterns of micromixers.
3D mesh of membrane with micromixers
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|A design analysis was performed
to optimize the shape of micromixers to maximize scouring on
the membrane surface.
| The total simulated mass transfer
of a tracer from the surface of the membrane was used as a
metric to compare the scouring effectiveness among the various
The parameterization results indicate that the greatest scouring
occurs when the chevron angle and chevron protrusion depth
are maximized, while the chevron pattern wavelength and spacing
between chevrons are minimized.
Deeper chevron protrusions induce a larger flow acceleration
toward the membrane surface
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|Epoxy micromixers were printed directly onto membrane surfaces,
and different patterns were evaluated experimentally.
hyperspectral imaging results showed that regions of simulated
high shear stress on the membrane corresponded to regions
of lower bacterial growth in the experiments, while regions
of simulated low shear stress corresponded to regions of
higher bacterial growth.
Membrane printed with micromixers
The top image is the relative microbial concentration
as observed by hyperspectral imaging; the bottom image
is the simulated relative shear stress on the membrane
- Altman, S. J., H. D. T. Jones, L. K. McGrath, D. M. Haaland, M. B.
Sinclair, 2007, Testing of RO Membrane Biofouling Using Fluorescent
Hyperspectral Imaging, 2007 North American Membrane Society Conference,
May 12-16, 2007, Orlando, FL. [SAND2007-3234C]
- Clem, P.G., “Smart Materials for Integrated Microsystems,” 10th
Germany-American Frontiers of Engineering Symposium, National Academy
of Engineering and Alexander von Humboldt Society, Hamburg, Germany,
April 25-28, 2007.
- Cornelius, C. J., C. H. Fujimoto, L. He, D. Perahia, Interfacial Characteristics
of a Potentially Anti-biofouling Highly Rigid Ionomer, 2007 APS March
Meeting, Session X17: Structure and Dynamics of Polymer Films.
- He, L., E. B. Watkins, J. Majewski, C. H. Fujimoto, C. J. Cornelius,
D. Perahia, Water Diffusion in Ultrathin Ionomer Thin Films: Neutron
Reflectivity Study, 2007 APS March Meeting, Session A17: Charged and
Ion - Containing Polymers.
- Hibbs, M., C. J. Cornelius, 2007, Synthesis and Characterization of
Novel Ionomer Membranes for Water Treatment Applications, 2007
North American Membrane Society Conference, May 12-16, 2007, Orlando,
- Ho, C.K., S.J. Altman, H.D.T. Jones, S.S. Khalsa, L.K. McGrath, and
P.G. Clem, 2008, (in press), Analysis of Micromixers to Reduce
Biofouling in Reverse-Osmosis Membranes, Accepted for publication
in the "Desalination
- Outstanding Papers from NAMS 2007" special issue of Environmental
Progress. [SAND 2008-1239J]
- Ho, C.K., S.S. Khalsa, P. Clem, M. Niehaus, S. Brown, and W. Hart,
2007, Analysis of Micro-Mixers to Reduce Fouling on Membrane Surfaces,
2007 North American Membrane Society Conference,
May 12-16, 2007, Orlando, FL. [SAND2007-3022P]
- Jones, H. D. T., S. J. Altman, C. K. Ho, L. K. McGrath, P. G. Clem,
D. M. Haaland, M. B. Sinclair, and D. K. Melgaard, 2007, Hyperspectral
Fluorescence Imaging of Biological Samples, Pittsburgh Conference,
February 25 - March 1, 2007, Chicago, IL. [SAND2007-1155C]
- Khalsa, S.S. and C.K. Ho, 2008, Design Optimization of Anti-Fouling
Micromixers for Reverse Osmosis Membranes, Abstract accepted for
the 23rd Annual WateReuse Symposium, Dallas, TX, September 7-10,
- Webb, S. W., 2007, High-Fidelity Simulation of Fluid Flow and Species
Behavior in RO Membranes, 2007 North American Membrane Society Conference,
May 12-16, 2007, Orlando, FL. [SAND2007-2311A]
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