Effect of coagulation on the size of MF and UF membrane foulants

Microfiltration (MF) and ultrafiltration (UF) have become common water treatment technologies for the removal of particles from natural waters. Many water utilities are now integrating MF/UF with other treatment processes to provide treatment for nonparticulate contaminants. Research is needed to understand the impact that other processes have on MF/UF performance. This study was conducted to investigate the interactions between water quality, coagulation, and membrane fouling. The study examined the fouling of MF/UF membranes by natural waters with and without coagulation by specific fractions of constituents in natural water, separated by size. This research found that the component of natural organic matter (NOM) smaller than 100 kDa contributes relatively little to fouling during filtration of either raw or coagulated water. The fraction between 1 mu m and 100 kDa contributes a significant portion of the fouling. After coagulation pretreatment, fouling due to various size fractions in the feedwater can change.