Seawater desalination is one of the most promising ways to solve the water shortage, providing and maintaining clean and safe water for drinking, daily public use, industrial processes, sanitary uses, etc.
Experience and skills gained in over 40 years allows Fisia Italimpianti to identify the best solution among all the available desalination technologies, capable to fit the specific needs of different owners, always considering the geographical framework.
The Company’s portfolio ranges from thermal to membrane (RO) desalination technologies, where there is a consolidated experience as EPC/DB contractor both in the contexts of Turn-key and Independent Water and Power Project (IWPP).
Total desalination production achieved is more than 4,800,000 m3/d (1,055 MIGD), mostly delivered in the Middle East.
Physical desalination processes allow to separate water from a saline solution using mechanical energy instead of thermal energy. The most diffuse method of physical desalination is the reverse osmosis (RO).
Since 1988, Fisia Italiampianti has completed several RO Desalination plants, both from seawater and brackish water, in several countries. The Company aims to contribute to sustainable growth of RO technology, improving know-how and competences. To this end, Fisia Italimpianti realized a pilot plant in Genoa Port for the optimization of the process and to control the fouling phenomena. RO system, become the preferred choice for the new installations, and is made up of the following four basic phases:
- Pretreatment
Fine filtration and the addition of acid or other chemicals to inhibit precipitation and the growth of microorganisms; - High-pressure pump
It supplies the pressure needed to enable the water to pass through the membrane and have the salts rejected. This pressure ranges from 15 to 25 bar (225 to 375 psi) for brackish water and from 54 to 80 bar (800 to 1,180 psi) for sea water. - Membrane assembly
It consists of a pressure vessel and a membrane that permits the feed water to be pressurized against the membrane. The membrane must be able to withstand the entire pressure drop across it. The semi-permeable membranes vary in their ability to pass fresh water and reject the passage of salts. - Post-treatment
The potable water quality required is reached by means of remineralization plant using CO2 and limestone.
The company has a vast experience in the main thermal technologies available for sea water desalination:
- Multi Stage Flash (MSF)
- Multiple Effect Distillation (MED)
The two processes are substantially based on the same physical / thermodynamic principles, but differ in some basic aspects and peculiarities.
Both technologies are well proven, and MSF is particularly suitable for large installations, where each unit can have a capacity between 60,000 m3/day (13.3 MIGD) and 90,000 m3/day (20 MIGD).