4. Conclusions
Oxidation with enhanced mixing can improve the performance of membrane filtration in a hybrid chlorination-MF process for the removal of Fe and Mn from groundwater. With increased mixing intensity, cake resistance in membrane filtration is reduced because of the formation of smaller oxide particles with higher fractal dimension, resulting in higher permeate flux. In the presence of Mn ions, the Fe/Mn oxide cake layer formed is more hydrophobic, and more likely to foul the membrane. The irreversible fouling of the dead-end MF by the oxides is insensitive to mixing intensity during prechlorination. To effectively mitigate membrane fouling of the prechlorination/MF process, intensive mixing during prechlorination may be a solution because it promotes the formation of a permeable cake layer rather than lower irreversible fouling during filtration.