Thursday, 10 April 2008
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NEWater-Water purification in Singapore
Why does Singapore need NEWater? As a small island , we are dependent on our neighbour, Malaysia, for water. However, if hostilities were to occur, and have occurred in the past, we might find ourselves lacking the most basic and important resource neccessary to survive. Thus, Singapore has embarked on this project to gradually decrease our reliance on Malaysis for water and one day, we might be able to depend on ourselve alone for this natural resource.
Therefore, how does NEWater work? As of every water purification system, there are certain steps involved.
The second barrier is the first stage of the NEWater production process known as Microfiltration (MF). In this process, the treated used water is passed through membranes to filter out and retained on the membrane surface suspended solids, colloidal particles, disease-causing bacteria, some viruses and protozoan cysts. The filtered water that goes through the membrane contains only dissolved salts and organic molecules.
The third barrier or the second stage of the NEWater production process is known as Reverse Osmosis (RO). In RO, a semi-permeable membrane is used. The semi-permeable membrane has very small pores which only allow very small molecules like water molecules to pass through. Consequently, undesirable contaminants such as bacteria, viruses, heavy metals, nitrate, chloride, sulphate, disinfection by-products, aromatic hydrocarbons, pesticides etc, cannot pass through the membrane. Hence, NEWater is RO water and is free from viruses and bacteria and contains very low levels of salts and organic matters.
At this stage, the water is already of a high grade water quality. The fourth barrier or third stage of the NEWater production process really acts as a further safety back-up to the RO. In this stage, ultraviolet or UV disinfection is used to ensure that all organisms are inactivated and the purity of the product water guaranteed.
With the addition of some alkaline chemicals to restore the acid-alkali or pH balance, the NEWater is now ready to be piped off to its wide range of applications.
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