AWWA ACE65396

Fouling mitigation has always been an important concern in membrane technology applications. One of the approaches used to improve performance and reduce the impact of fouling is the development of new membrane materials. With this objective, the authors have developed a number of different novel surface modified polyethersulfone (PES) ultrafiltration (UF) membranes via the addition of different hydrophiLic Surface Modifying Macromolecules (LSMMs). The objective of this study was to compare performance of the best experimental membrane (PES-LSMM) with nine commercial UF membranes manufactured using five different types of base polymers (polyethersulfone, polysulfone, cellulose acetate, polyacrylonitrile and cellulose). All membranes were characterized by using atomic force microscopy, contact angle measurement, solute transport analysis, charge measurement and then evaluated through fouling tests with Ottawa River water (ORW). Based on the small contact angles, high pore density, small pores and smooth surfaces, the modified cellulose acetate (CQ40) and polyethersulfone (PU40) membranes appeared to be the most promising in terms of fluxes. The PESLSMM experimental membrane however had the lowest long-term flux reduction (48%), comparable long term fluxes and the highest dissolved organic carbon (DOC) rejection (80%). For the commercial membranes, the range of flux reductions and DOC rejections were 52-61% and 66-79%, respectively. The high initial DOC removal (72%) of LSMM membranes makes it a promising material for hollow fiber membranes due to the frequent backwashing in this type of membrane module. Given a thorough study of membrane surface characteristics (porosity, hydrophilicity, charge and roughness), it was found that size exclusion was not a significant factor on natural organic matter (NOM) rejection. Electrostatic repulsion and morphology (surface roughness) had slight impacts on fluxes (J/Jo). The effect on membrane performance was greater for surface charge. Includes 22 references, tables, figures.