Managing corrosion in desalination plants

Environment quality, clean energy and worldwide water scarcity have been established today as central disciplines in modern science, engineering and technology. The innovative desalination technology of saline water (SW) contributes to alleviate these problems by producing fresh water from SW, mainly seawater and brackish water. Desalination plants (DPs) have a high level of corrosion risk as they handle and process aggressive SW under severe operating conditions, which include filtration, heat exchange, distillation, evaporation, agitation and circulation and high flow velocities, often turbulent. These SW, that is, sea, brackish and brines, cause localized corrosion such as pitting, crevice, galvanic and stress corrosion. In addition, biological fouling and mineral scaling are frequent nuisances that alter the equipment surface performance and induce corrosion. Two main technologies are used to obtain potable water and a brine for disposal: thermal evaporation and membrane separation, called reverse osmosis. The main way to minimize corrosion is the correct selection of corrosion-resistant materials for the fabrication of DP equipment, structures, installations and machinery. To protect the DP materials, industrial paints, polymeric coatings and rubber linings compatible with the DP fluids are applied. Cathodic protection with sacrificial anodic metals and/or impressed direct electrical current and corrosion inhibitors are supplied.