Influence of Membrane Materials and Operational Modes on the Performance of Ultrafiltration Modules for Drinking Water Treatment

Polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polyacrylonitrile (PAN) were prepared to purify micropolluted source water via a pilot-plant test. Integrative devices of in-line coagulation/ultrafiltration (UF) were proposed. Then the treatment performance, operation stability, clean methods, and fresh water recovery rate were assessed. The results showed that the membrane materials and operational modes did not result in significant difference of the removal efficiency of turbidity, CODMn, and NH4-N. The uniform distribution porosity, better hydrophilicity, and higher thermal stability of the PES membrane made its specific flux (SF) more than double those of two other membranes; in addition, the transmembrane pressure (TMP) of PES membrane appeared to be the least influenced by temperature change. The hydrophilicity of UF membrane was not a conclusive factor with the critical flux. The inside-out module with higher fouling load presented higher decay rate of SF under fixed flux operation compared with outside-in modules in single filtration duration. The way of gas washing of outside-in modules as a supplement resulted in recovery improvement. The acid-base staggered method of inside-out module to carry out chemical enhanced backwash (CEB) can effectively intensify the effects of backwashing by water.