(187e) Determination of the Effect of Humic Acid Aggregation On Membrane Fouling By Zeta Potential and Dynamic Light Scattering

While natural organic matter and specifically humic acids (HA) have been studied extensively, the aggregation of these materials in solution is not well understood. In this study, the effects of time, concentration, and filtration; Dissolve Organic Carbon – Total Organic Carbon; (through a 0.45 micron Millipore filter) were examined by monitoring changes in zeta potential and dynamic light scattering. The effects of concentration were studied at 2, 5, 8, 45, 100, 250, and 500 ppm. At lower concentrations of Humic Acid higher variation of aggregation size was observed compared to higher concentration. Residence time does not affect the stability of aggregate specifically at higher concentration. Zeta potential decreased—became more negative—as concentration increased. Aggregates of total organic carbon (before filtration) are more stable over time than dissolved organic carbon (after filtration).  Finally, the effects of concentration and humic acid size ( DOC-TOC ) at fouling on synthetic Polysulfone ultrafiltration were determined