The effects of coagulation pre-treatment on microfiltration process were investigated with the Nakdong River source water. In this study, the potential membrane-fouling materials presented in the raw water were mainly attributed to particulate matters and UV254-absorbing materials. Coagulation pre-treatment mitigated the effects of these components on membrane fouling because it induced a change in the characteristics of the cake layer and a decrease in the content of UV254-absorbing materials. Even though the coagulated suspensions were not removed before MF membrane filtration, their impact on resistance to filtration was insignificant when compared with that caused by the suspensions without pre-coagulation. However, insufficient dosages of coagulant or the improper controls of coagulation pH might cause severe membrane fouling in the treatment of low turbidity water (i.e. turbidity below 10 NTU). It appeared that a selection of coagulant dosage that focused on the reduction of specific cake resistance was possibly the best way to achieve the optimal condition in this study. Also, the coagulation pre-treatment process at pH values between 5.3 and 6.8 was found to be most effective in providing the lowest specific cake resistance as well as residual UV254 absorbance.

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