A comparison of typical ultrafiltration processes in drinking water treatment: Implications for fouling control and disinfection performance

Despite the rapid proliferation of ultrafiltration (UF) membranes in drinking water treatment, the long-term operational performance of various hybrid UF processes remains inadequately understood. Herein, three typically applied hybrid UF processes were directly compared on a pilot scale, focusing on effluent quality, fouling control and subsequent disinfection performance. Water quality analysis revealed that the direct UF process exhibited significant removal of high molecular weight and hydrophobicity fractions, while the integration of UF with conventional water treatment processes further enhanced the removal of medium molecular weight and transition fractions, as well as fluorescent organic matter. The augmentation of pretreatment processes resulted in the hybrid UF process featuring enhanced anti-fouling properties, characterized by decreased reversible and irreversible resistances under the constant flux condition. This improvement was attributed to reduced interaction between the membrane and foulants. Furthermore, the subsequent disinfection performance of hybrid UF processes was evaluated using chlorine and chlorine dioxide as disinfectants. The chlorine decay rate and disinfection by-product formation indicated that chlorine dioxide was more suitable for the UF process, whereas chlorine was better for the hybrid UF process with low organic matter content in the effluent. These comprehensive comparisons offer valuable insights for making informed decisions in adopting suitable hybrid UF processes for practical water treatment applications.