Development of New Ultrafiltration Membranes for Mitigation of Fouling in Wastewater Filtration

The fouling rates were compared in two continuous membrane bioreactors to investigate the hydrophilic/hydrophobic characteristics of extracellular polymeric substances (EPS) and soluble microbial products (SMPs). This study concluded that membrane fouling is predominantly governed by the mixed liquor solids concentrations which affect SMP productions and characteristics. Two ultrafiltration membranes with different hydrophilic/hydrophobic properties were tested using activated sludge and SMPs. A modification of the resistance-in-series model was applied; the results showed that cake resistance was the main fouling mechanism for both membranes. The comparable observed fouling rates and permeability in the two membranes appears to dispel any advantages of hydrophilic membranes for sludge filtration.;Metal oxides entrapped membrane showed lower flux decline compared to that of neat polymeric membrane. The best load of metal oxides immobilized membranes for MBR application in terms of the lowest fouling rate and highest membrane permeability was the 5% weight fraction of metal oxides with PES. The ZrO2/PES membranes showed superior physical properties to both Al2O3/PES and neat PES membranes in terms of higher membrane thickness and higher maximum trans membrane pressure (TMP) sustained by the membrane. However, the Al2O3/PES membranes were superior in terms of fouling mitigation.;The newly synthesized (metal oxides/PES) membranes showed above 99% and 80% removal efficiencies for Pb (II) and Cr (III), respectively. The membrane operational conditions of neutral pH and low TMP (69 kPa) are advantageous over the adsorption technique.;Flat sheets metal oxides (Al2O3 or ZrO2) entrapped polyethersulfone (PES) ultrafiltration membranes were prepared via phase inversion and applied to activated sludge filtration and to synthetic wastewater laden with heavy metals in order to evaluate their fouling characteristics and their metal removal efficiencies. The best solvent evaporation time and polymer concentrations were found to be 15 s and 18% (w/w), respectively. The membranes morphologies were characterized using field emission scanning electron microscope (FESEM). The prepared metal oxides/ PES membranes were skin- type membranes and showed a structural change from a finger-to sponge-type structure. The finger structure was associated with high metal oxides percentage in the membrane matrix.