Scaling in reverse osmosis seawater desalination: Mechanism and prevention-A literature review

There is currently a huge imbalance between the demand and supply of freshwater resources. The shortage of fresh water can be mitigated by seawater desalination. Reverse osmosis (RO) is currently the most popular desalination technology around the world. Despite its various advantages, fouling has been one of its major limitations of RO. Membrane fouling can be divided into four categories: colloidal fouling, inorganic fouling, organic fouling, and biofouling. Precipitation of inorganic salts of small solubility, among which CaCO3, CaSO4, BaSO4, and SiO2 are the most common ones, are the cause of inorganic fouling, which is commonly referred to as scaling. Pretreatment technologies for prevention or mitigation of scaling in the RO process can be classified as conventional pretreatment technologies, which include water softening and scale inhibitors, and membrane-based pretreatment technologies which include nanofiltration, forward osmosis, and membrane surface modification.