MS, University of Cincinnati, 2014, Engineering and Applied Science: Environmental Engineering

Surface water contains natural organic matter (NOM) that reacts with disinfectants creating disinfection byproducts (DBPs), some of which are USEPA regulated contaminants. Characterizing NOM can provide insight with respect to DBP formation and water treatment process adaptation to climate change as the nature of NOM varies. This study collected NOM from the Ohio River over 15 months (April 2010 to July 2011) in order to assess seasonal variability in NOM characteristics. The NOM was characterized using fluorescence spectroscopy, UV254, TOC, high performance liquid chromatography – size exclusion chromatography (HPLC-SEC), and elemental analysis. NOM was concentrated, freeze-dried (lyophilized), and validated with the source NOM creating a standardized lyophilized NOM that may be used in water treatment process evaluations investigating utility adaptation to seasonal changes. Additionally, NOM was concentrated at multiple concentration factors, lyophilized, and reconstituted allowing for the determination of optimal NOM concentration and reconstitution conditions. The NOM was characterized using UV254, TOC, HPLC-SEC, fluorescence spectroscopy, and DBP formation. Raw Ohio River water NOM was concentrated in the following order: ultrafiltration (UF), cation ion exchange, reverse osmosis (RO), sulfate removal, and lyophilization. Lyophilization allows for long-term storage of NOM while providing the ability to reconstitute at various NOM concentrations compared to liquid material with a short shelf-life. Lyophilized NOM was used for elemental analysis while UF effluent, concentrate, and reconstituted lyophilized NOM were employed for all other analyses. A single RO concentration factor (150X) was used during the 15-month study while 50X, 100X, 150X, 200X, and 250X were used to determine the optimal RO concentration factor versus reconstitution factor. Parallel factor ii analysis (PARAFAC) determined the locations of principle components within fluorescence excitatio (open full item for complete abstract)

Committee: Dominic Boccelli Ph.D. (Committee Chair); Jonathan Pressman Ph.D. (Committee Member); Margaret Kupferle Ph.D. P.E. (Committee Member) Subjects: Environmental Engineering

MS, University of Cincinnati, 2003, Engineering : Chemical Engineering

Characterization of a membrane is necessary to predict its performance under different operating conditions and to optimize a membrane separation process. In this study a novel technique to characterize nanofiltration and reverse osmosis membranes is developed. This technique combines a membrane transport model based on irreversible thermodynamics with the description of concentration polarization to describe the separation process in the flat disk membrane cell. The irreversible thermodynamics model describes the solute transport through nanofiltration and reverse osmosis membranes by diffusion as well as convection as opposed to the solution diffusion model that describes salt transport only by diffusive flux. Due to the symmetrical circular geometry of the disk membrane cell the hydrodynamics remains uniform over the entire surface of the membrane. This helps in describing concentration polarization more accurately as compared to hollow fiber and spiral wound modules where the concentration of solute changes in an unknown way as the mass transfer boundary layer thickness develops along the flow. The permeation data obtained by varying feed flow rates, feed concentration and applied pressures were best fit to the theoretical model to obtain the three phenomenological coefficients that characterize the membrane, namely: (1) the hydraulic permeability (2) the solute permeability, and (3) the reflection coefficient of the membrane. For the nanofiltration membrane dealing with NaCl, the reflection coefficient was determined to be 0.75, which shows that the contribution of advection could be significant to total salt flux through this nanofiltration membrane. The method also enabled determining the mass transfer boundary layer thickness that was subsequently used to calculate the concentration of solute at the surface of the membrane. The intrinsic solute rejection, which is based on the concentration of salt at the membrane surface, was correlated with the total volum (open full item for complete abstract)

Committee: Dr. William Krantz (Advisor) Subjects: Engineering, Chemical