Fouling characteristics of pressurized and submerged PVDF (polyvinylidene fluoride) microfiltration membranes in a pilot-scale drinking water treatment system under low and high turbidity conditions

Performance and fouling characteristics of two pilot-scale polyvinylidene fluoride hollow fiber microfiltration membranes for drinking water treatment were studied under the same flux and physical cleaning conditions. It is expected that this paper can provide insights into the functions of operation mode (one pressurized and one submerged) of the membrane in process performance and fouling evolution. As a result, it was found that the two membranes showed similar performance in terms of removal efficiencies of organic and inorganic substances. However, the pressurized membrane showed relatively more severe membrane fouling than the submerged membrane because the cake compressibility and thickness seemed to have been increased due to the hard-to-remove cake layer of the pressurized membrane containing relatively large amounts of humic substances, carbohydrate, and Fe than that of the submerged membrane, especially under high turbidity conditions without any pre-treatment. Under low turbidity conditions with pre-coagulation/sedimentation, the two membranes showed similar behaviors for increase of transmembrane pressure. After the chemical cleaning that was carried out after removing the cake layers from the membrane, surface flux restoration of the two membranes was not much different.