NAMS 2002 Workshop - ICOM 2008

Membrane Fouling - General Topics – 1 – Keynote
Monday July 14, 9:30 AM-10:15 AM, O’ahu
Protein Fouling of Polymeric Membranes: Modeling and Experimental
Studies Using Ultrasonic Frequency-Domain Reflectometry
E. Kujundzic, University of Colorado at Boulder Department of Mechanical Engineering, Boulder,
CO, USA
K. Cobry, University of Colorado at Boulder Department of Mechanical Engineering, Boulder, CO,
USA
C. Ho, University of Cincinnati, Department of Chemical and Materials Engineering, Cincinnati,
OH, USA
W. Li, University of Cincinnati, Department of Chemical and Materials Engineering, Cincinnati,
OH, USA
A. Greenberg, University of Colorado at Boulder Department of Mechanical Engineering, Boulder,
CO, USA
M. Hernandez (Speaker), University of Colorado at Boulder Department of Civil, Architectural
and Engineering, Boulder, CO, USA, mark.hernandez@colorado.edu
Biofouling is a major problem associated with membrane separation processes
that causes decreased performance and altered selectivity. Biofouling typically
occurs either on the membrane/feed solution (external) surface or within the
pores that are internal to the membrane structure. Accurate characterization of
protein fouling as it occurs is crucial for an improved understanding of fouling
mechanisms with respect to biofouling control and membrane cleaning
optimization. A promising approach for achieving these objectives involves the
application of fouling models, which can be validated using data from noninvasive,
real-time monitoring of relevant membrane separations. Clearly, there
are significant benefits in employing real-time, non- destructive methods that can
resolve changes in accumulating mass on membrane surfaces and/or to the
materials that fill membrane pores, where these markedly different fouling
mechanisms can be isolated from each other. The only practical methodology
that currently satisfies these criteria is ultrasonic reflectometry (UR). Recent
reports have described the ability of UR to monitor the development of biofilms
on the surfaces of flat- sheet and hollow-fiber membranes used for drinking water
treatment. We describe the use of novel signal-processing protocols to extend
the sensitivity of UR for real-time in-situ monitoring of MF membrane fouling
during protein separations and purification.
Different commercial MF membranes with a nominal pore size of 0.2µm were
challenged using bovine serum albumin (BSA) and well-characterized bacterial
amylase as model proteins. Biofouling induced by these proteins was observed
in flat- sheet cells operating in a laminar, cross-flow regime. Membranes were
fouled by challenging these units with solutions containing BSA or amylase at
levels high as 1g/L. Baseline conditions were established by running ultrapure
water thorough the system for at least 24h. In a series of independent trials, the