11. Fouling Mechanisms in Nanofiltration Membranes

Nanofiltration (NF) membranes have been attaining research interest since the late 1980s, especially in water purification applications; they are very efficient and can selectively remove undesired ions and other organic substances. Various applications of nanofiltration such as treatment of surface and groundwater, removal of organic contaminants and pathogens from water for its reuse are discussed in this chapter. However, a significant disadvantage of any membrane separation process is the fouling phenomenon, adversely affecting membrane efficiency. The fouling phenomenon is majorly dependent on the properties of the membrane and interactions between the solutes and membranes. The present chapter discusses various fouling phenomena such as gel formation, adsorption, deposition, pore blocking, and cake formation in NF membranes. To better understand the fouling, mechanisms involved and various mathematical models to describe fouling are necessary. Therefore, Hermia's models to describe fouling, such as standard pore blocking, complete pore blocking, intermediate pore blocking, and cake filtration models, are discussed in detail. In addition, many researchers are working on fouling mitigation of nanofiltration membranes to avoid fouling. Consequently, this chapter described the various fouling mitigation methods.