Microscopic visualization of membrane pores and bacterial foulants
EMSL Project ID
17096
Abstract
My research is mainly centered on membrane technologies for municipal water purification. We (1) elucidate contaminant transport and membrane fouling mechanisms, (2) devise methods to enhance contaminant removal and reduce fouling, and (3) fabricate new kinds of membranes. Generally speaking, we perform mass transfer experiments and deduce mechanistic information from them by applying mathematical models. However, we are limited by our inability to perform direct microscopic measurements in our labs.For example, in two of the attached papers, we performed experiments at varying temperatures in the range 5 - 40 C and deduced that the nanofiltration membrane effective pore size increases with temperature. Of particular importance is that the actual pore diameters are very small, and of the order of 1 or 2 nm only. This is in accordance with the IUPAC definition of nanofiltration membranes. Direct microscopic measurements would lend stronger and more direct evidence of temperature-induced changes in polymeric membrane morphology. These measurements are crucial in developing a fundamental understanding of how seasonal variations in feed water temperature impacts membrane performance.
In other on-going work (see attached biofouling paper), we are studying virus and bacteria interactions with membranes. To date, we have only used an SEM to visualize the morphology of bacterial deposits on membranes. One limitation of using an SEM is the extensive sample preparation and drying that is necessary. It would be very instructive to visualize bacteria and viruses in wet conditions using an environmental SEM, AFM, and TEM.
The objectives of the proposed research are to (1) directly visualize polymeric membrane pores at varying temperatures and oxidant concentrations to provide direct evidence of changes in their sizes, and (2) obtain microscopic insights into the morphology of bacterial and viral deposits on membrane surfaces at varying operating conditions (filtration pressure and flux).
These measurements will greatly enhance my on-going research funded through a CAREER grant from the Division of Biological and Environmental Sciences of the National Science Foundation.
Project Details
Project type
Exploratory Research
Start Date
2006-06-05
End Date
2007-03-22
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Appala Raju Badireddy (2008). Interactions of Bacteria and Viruses with Membranes and Nanoparticles: Characterization of Extracellular Polymeric Substances and Photoinactivation of Bacteriophages by Fullerol Nanoparticles. Doctoral Dissertation, Department of Civil and Environmental Engineering, University of Houston, Houston, TX.
Badireddy AR, BR Korpol, S Chellam, PL Gassman, MH Engelhard, AS Lea, and KM Rosso. 2008. "Spectroscopic Characterization of Extracellular Polymeric Substances from Escherichia coli and Serratia marcescens: Suppression using Sub-Inhibitory Concentrations of Bismuth Thiols." Biomacromolecules 9(11):3079-3089. doi:10.1021/bm800600p
Badireddy AR, BR Korpol, S Chellam, PL Gassman, MH Engelhard, AS Lea, and KM Rosso. 2008. "Spectroscopic Characterization of Extracellular Polymeric Substances from Escherichia coli and Serratia marcescens: Suppression using Sub-Inhibitory Concentrations of Bismuth Thiols." Biomacromolecules 9(11):3079-3089. doi:10.1021/bm800600p
Badireddy, A.R., S. Chellam, S. Yanina, P.L. Gassman, and K.M. Rosso, (2007). Bismuth Dimercapto-propanol (BisBAL) Inhibits the Expression of Extracellular Polysaccharides and Proteins in Brevundimonas diminuta: Implications for Membrane Microfiltration. Biotechnology and Bioengineering, In press.
Badireddy AR, S Chellam, S Yanina, PL Gassman, and KM Rosso. 2008. "Bismuth Dimercaptopropanol (BisBAL) Inhibits the Expression of Extracellular Polysaccharides and Proteins by Brevundimonas diminuta: Implications for Membrane Microfiltration." Biotechnology and Bioengineering 99(3):634-643. doi:10.1002/bit.21615