AWWA WQTC57111

This research focused on membrane flux decline trends observed during ultrafiltration (UF). All filtration experiments were performed with a non-stirred cell unit equipped with flat sheet polyethersulfone UF membrane coupons under a constant transmembrane pressure of 1 bar. The study was conducted in two phases. The objective of the first phase of the study was to examine the fouling potential of various solutions containing natural organic matter (NOM) fractions isolated from surface waters. Results showed that the most significant flux decline was due to the organic colloidal fraction, a hydrophilic fraction consisting mostly of bacterial cell wall residues. The presence of calcium was found to significantly enhance the fouling properties of NOM. The objective of the second phase of the study was to examine the fouling properties of various bulk surface waters. Results confirmed the important role of the hydrophilic fraction of bulk NOM in membrane fouling. Fluorescence emission spectra (humic-like structures) of natural waters remained unchanged after ultrafiltration, but their light scattering properties are found to be significantly reduced organic compounds that are large in size and non-humic in character (absence of fluorophores), and contain protein and carbohydrate structures are considerd to be the main contributors to membrane fouling. Includes 7 references, tables, figures.