Tuas Seawater Desalination Plant

The plant at Tuas South (reclaimed land) will supply over 110,000m tonne per dday of product water - enough to meet around 10% of the national demand - using seawater reverse osmosis (SWRO) membranes. Hyflux Ltd were given the 20-year design-build-own-operate (DBOO) contract by the Public Utilities Board (PUB) in January 2003. The initial tendered water price will be $0.78 / mt in 2005, when the plant is scheduled to be operational, but it will vary monthly with prevailing fuel cost and annually with inflation, based on a pre-defined formula.

As the first desalination facility in the country, and one of the first and largest in the region, the Tuas SWRO plant has an important role to play in Singapore’s drive to achieve water self-sustainability. The country’s move towards making greater use of desalinated water - the so-called "fourth national tap" (The 4 National Taps are local catchment, imported water, NEWater and desalted water) - comes as a result of increasing demand and governmental targets to ensure the provision of sufficient potable water to meets future needs at affordable cost.

Desalination is a treatment process that removes dissolved salts from seawater. Two main processes are used for desalination of seawater, namely distillation and membrane processes. In the distillation process, a variety of methods are used to evaporate seawater, condense the vapour formed and obtain distilled water that is essentially free from salts. In the membrane process such as the reverse osmosis process, pre-treated seawater is pumped at high pressure through a semi-permeable membrane that separates the water from the dissolved salts.

The plant design uses an open seawater intake structure with two separate inlet channels, each equipped with mechanical rake coarse screens. Growth inhibitors will be added to the intake to reduce the potential for marine growth to accumulate around the screens, pipes and other structures. Chemical dosing systems are also to be installed to ensure adequate pH correction and for the addition of polymer coagulants.  The RO (reverse osmosis) treatment process itself consists of two passes through the installed membrane batteries. On the first pass, dissolved solids are removed from the flow; the purpose of the second is to enable the RO units to reduce the boron level in the treated water.

Plant under construction!

Updated On: 15.02.10