Effect of boron-doped diamond anode electrode pretreatment on UF membrane fouling mitigation in a cross-flow filtration process

Abstract In this study, ultrafiltration coupled with electrochemical oxidation using a boron-doped diamond (BDD) electrode prior to reverse osmosis was employed to treat the simulated sea water. It was found that BDD based anodic pre-oxidation effectively improved the removal efficiency of dissolved organic matters especially enhance the rejection of fluorescent substances when prolong the oxidation time. Based on the analysis of XAD resin adsorption, the fraction of hydrophilic components significantly increased after the electro-oxidation pretreatment. In addition, the BDD based oxidation pretreatment was found to reduce the disinfection byproduct formation potential. A two-stage fouling model and the interfacial free energy were employed to investigate the fouling mitigation mechanisms via electrochemical oxidation pretreatment. The results show that membrane fouling was mitigated with increasing repulsive interactions and decreasing attractive interactions between humic acid molecules and the membrane surface after electrochemical oxidation. With longer electrochemical oxidation time, the dominant mechanism of membrane fouling shifted from complete pore blocking and cake filtration, mainly caused by hydrophobic humic acid compounds with higher molecular weight, to standard blocking and pore blocking, caused by hydrophobic humic acid compounds with low molecular weight.