Natural organic matter (NOM) is frequently cited as the primary cause of chronic fouling of membranes. Dr. Makdissy studied the characteristics of NOM and the interactions between the organic foulant and the membrane. This project is for improving the performance of membrane filtration in drinking water treatment.
The experimental approach was based on flat sheet cell membrane tests conducted under a constant transmembrane pressure of 1 bar. Two 100 KDa flat sheet membranes were selected for this study. NOM including hydrophobic (HPO), transphilic (TPI) and colloids were isolated from natural waters. Analytical tools such as FTIR, C 13 NMR, pyrolysis GC/MS were used for identifying characteristics of NOM.
From the study, she found that a hydrophilic fraction, consisting mostly of residue from the bacterial cell wall, showed very severe fouling properties as compared to humic materials. She also used a sequential filtration process to help elucidate colloidal fouling mechanisms. The retention of small molecules was confirmed by performing a filtration test with colloids that were prefiltered through a 100 KDa UF membrane. The results indicated that the colloids could adhere to the membrane through interactions between the solute and the membrane. Membrane surface examination revealed morphological changes of the fouled membrane compared to the clean one. These results demonstrate the role of surface coverage .