The change of NOM in a submerged UF membrane with three different pretreatment processes compared to an individual UF membrane

Three identical submerged ultrafiltration (UF) membranes with different pretreatment processes (coagulation, adsorption and ozonation) were compared with an individual UF membrane to investigate the performance of the process and characterize organic membrane foulants by natural organic matter (NOM) molecular weight distribution (MWD) and chemical fraction techniques. The results indicated that the preferred amount of organic matter removal was achieved in three integrated processes (coagulation/UF, adsorption/UF, ozonation/UF), and the trans-membrane pressure (TMP) increased at a rate much lower than that in an individual UF membrane. The ozonation pretreatment, with O3 as an oxidant, improved the > 10 kDa NOM fraction removal and hindered the < 3 kDa NOM fraction removal for raw water, while the adsorption pretreatment, with powdered activated carbon (PAC) as an adsorbent, improved the < 10 kDa NOM fraction removal. The total NOM content of internal foulants extracted from the three integrated processes was lower than UF, indicating that all three pretreatments could reduce the accumulation of NOM in the membrane pores. The PAC/UF had a distinct advantage for removing NOM in effluent. It is observed that the hydrophilic matter (HiM) chemical fraction removal rate of O3/UF was lower than in the other three processes.