CAREER: Membrane Processes for DBP Precursor Control: Effects of Colloid Stability and Membrane Surface Chemistry on Flux and Rejection

Rensselaer Polytechnic Institute, Troy NY

Investigators

Abstract

9984709 Kilduff The use of synthetic polymer membranes in water treatment is increasing worldwide, especially for the removal of disinfection by-product (DBP) precursors and of pathogenic organisms and viruses. The microporous materials are vulnerable to fouling by organic macromolecules and other colloids and this fouling often contols the efficiency, reliability and costs of membrane processes in municipal and industrial applications. The goals of this research are to: (1) understand the interactions between organic macromolecules and other natural organic and inorganic colloids in membrane filtration systems and how colloid stability influences the performance of membrane processes and (2) understand how membrane flux and rejection are related to membrane surface chemistry and identify the efficacy of UV photomodification to produce filtration membranes more resistant to fouling. Fractionation and characterization will be required to identify the composition and reactivity of components of heterogeneous environmental colloid mixtures. Separation of mixtures will be done on the basis of size, using filtration, and chemical functionality, using adsorption chromatography and solvent precipitation. The effects of individual organic matter isolates and of colloid mixtures on membrane performance (fouling, rejection and cleaning) will be evaluated. Mixtures will include organic matter fractions and sub-micron inorganic colloids (clays, silica and iron oxides). Fouling will be related to colloid stability and fouling layer morphology using atomic force and confocal microscopy. Strategies to mitigate fouling effects will focus on tailoring surface chemistry to reduce the binding of organic molecules and colloids. The surfaces of polymeric membranes will be modified (made more hydrophilic) by UV radiation followed by monomer grafting and subsequent polymerization. Effects of monomer type, reaction time and UV radiation intensity will be evaluated. As-received and fouled membranes will be characterized by scanning electron microscopy, electron spectroscopy, contact angle, attenuated total reflection infrared spectroscopy, atomic force microscopy and fouling potential in bench-scale test cells. The education plan centers around the development of a new Membrane Processes course from which students will learn not only process fundamentals but also how fouling can cause treatment systems to exhibit time-dependent performance, and how to incorporate accurate parameter estimation into the design process to improve process reliability. ***