Effects of Fe(II)-activated persulfate/sodium percarbonate (PS/SPC) pretreatment on ultrafiltration membrane fouling control and mechanisms

Membrane fouling during the ultrafiltration (UF) is a key restricting factor in the treatment of drinking water. To control membrane fouling, a ferric ion activated dual oxidant (persulfate/sodium percarbonate (PS/SPC)) pretreatment method was employed to degrade natural organic matter (NOM) in drinking water sources. In this work, the quantity and properties of NOM in water sample before and after the Fe(II)/persulfate/sodium percarbonate(Fe(II)/PS/SPC) oxidation pretreatment were evaluated, and the changes in the morphology of the membrane and the accumulation characteristics of organic functional groups in the fouling on the membrane surface were analysed. The oxidation efficiency of system was compared by taking bisphenol A as the target pollutant, which is an important basis for its superior NOM removal compared with conventional treatment system. More importantly, adding part of SPC to the system while reducing the amount of PS can effectively solve the issue of pH reduction caused by PS decomposition. The extended Derjaguin–Landau–Verwey–Overbeek (xDLVO) theory analysed that with the relative increase in pH value, the Lewis acid-base interaction energy decreases, which is also the reason for the decline in irreversible pollution. The results showed that Fe(II) activated double oxidant (PS/SPC) pretreatment has a promising application in membrane fouling control. • Ferrous ion/persulfate/sodium percarbonate was used for membrane fouling control. • Dual oxidant system with proper molar ratio significantly mitigated member fouling. • Introducing low dose sodium percarbonate can solve pH problem caused by persulfate. • Total interfacial free energy decreased further after pH problem was solved.