In this study, in the P-purification plant located in Jeonju city, the membrane filtration water treatment facility sized 500 m³/d was installed and single and dual flocculation processes were combined. The observation of changes in the water quality and the membrane by the alteration of the supply flow rate according to the water temperature led to the following conclusions.
1. The temperature of the incoming water was relatively stable without the influence from outside and the average turbidity was 0.035NTU and it was proper for the water quality for drinking.
2. In case there was a flocculation process as a pretreatment of membrane filtration facility, as the amount of coagulant increased, TMP (Transmembrane Pressure) increased as well. When the concentration of coagulant was changed to 16ppm, TMP became unstable and approached the allowable pressure (0.5kgf/cm²). It was determined to be caused by the blockage of the flow path generated by the attachment of solids between submerged bundles due to the high concentration of floc. In addition, the long-term non-operation caused suspension materials precipitated in the membrane water tank to block the flow path.
3. As a result, MF (Microfiltration Membrane) was effective at the removal of turbidity regardless of injection of coagulant. The TMP that rose by the injection of high concentration of coagulant was shown not to be recovered even if the injection amount of coagulant was lowered. For the current research, in order to maintain the TMP stably less than 0.3 kgf/cm², it is determined to be proper to inject the coagulant less than 8ppm.