AWWA ACE60017

Natural organic matter (NOM) fractions; colloids, and hydrophobic (HPO), transphilic (TPI), and hydrophilic (HPI) fractions, isolated from a natural surface water as an allochthonous source, and in the form of algal organic matter (AOM) derived from blue green algae as an autochthonous source, were investigated in low pressure membrane filtration. The most significant flux decline was caused by organic colloids, with an intermediate flux decline caused by AOM derived (isolated) from ground and sonicated blue green algae. 3-D EEM analyses indicated that colloids and AOM contain protein-like substances, and FTIR analyses showed overlapping peaks associated with the peptide bonds in proteins and alcohols in polysaccharides. HP-SEC results also support a high content of apparently macromolecular compounds in the colloid fraction. The presence of a divalent cation (Ca²⁺), hypothesized to enhance fouling by NOM and acids by a reduction in molecular charge, showed little effect. Morphological analyses indicated that the surface topography of fouled ultrafiltration (UF) membranes was elevated, presumably due to deposition of NOM on the membrane surface. The pores of microfiltration (MF) membranes were reduced, suggesting pore blockage by NOM aggregates. Includes 18 references, tables, figures.