NEWater is a high-grade reclaimed water produced in Singapore through advanced filtration and purification processes. It involves (1) waste water treatment to remove solids and organic matter, (2) microfiltration to remove bacteria and suspended particles through membrane filtration, (3) reverse osmosis to remove dissolved chemicals, salts, and other impurities through a semi-permeable membrane, and (4) ultraviolet disinfection to inactivate any remaining microorganisms. NEWater meets World Health Organization standards for drinking water and is part of Singapore's strategy to ensure a sustainable water supply.

1. How NEWater is obtained

2. NEWater is a high-grade reclaimed water which is obtained from used water which has been treated using the latest membrane and filtration technologies. NEWater has also surpassed the requirements set by the World Health Organisation, and thus, it is absolutely safe for consumption. NEWater is part of the “Four National Taps” of Singapore which aims to provide Singapore citizens with a safe and sustainable supply of drinking water. What is NEWater?

3. Obtaining NEWater requires 4 main steps, namely: Waste Water Treatment Microfiltration Reverse Osmosis Ultra- Violet Disinfection. The Processes Involved

4. What is Waste Water Treatment? Waste Water Treatment is the process whereby used water is treated to globally recognised standards. This is to prevent the further pollution of water sources after it is released into another body of water. How is Wastewater Treated? Wastewater is treated by levels, namely, the Preliminary, Primary, Secondary, and Tertiary level. The First Barrier: Waste Water Treatment

5. The Treatment Process Preliminary- The water which first enters the treatment plant is screened to remove any large solid objects which are present in the water. Then they are moved to a grit tank to separate smaller objects Primary- This stage allows for the physical separation of solids and greases. The water is then held in a tank to separate the water from the solids and the greases.

6. The Treatment Process Secondary- In this stage, the water is mixed with micro- organisms which use oxygen to consume the remaining organic matter left in the wastewater. The oxygen and micro- organisms are supplied by the aeration tank where the water is stored Tertiary- The wastewater is finally disinfected using chlorine and ultraviolet . The water can then be discharged to other water bodies as it has already been cleansed and is deemed safe to be released.

7. A Diagram of Wastewater Treatment

8. The Second Barrier: Microfiltration After going through the waste treatment process in the waste treatment plants, the treated water is used as a source to produce NEWater. This process basically forces the water is forced through membranes with hollow fibres to filter out solids which are suspended in the water, bacteria, and other harmful substances. The water after microfiltration would contain only dissolved salts and organic molecules.

9. The Second Barrier: Microfiltration So, basically, Microfiltration in NEWater is actually just normal filtration, but on a higher and more specific level. This is because we are not just trying to separate the suspended solids from the water, but also the harmful bacteria which are present in it. Thus, the holes in the membranes have to be smaller than the size of the bacteria to be able to trap them and prevent them from entering the next stage of purification. So, like normal filtration, where filter paper is used, Microfiltration makes use of the membranes to separate water from bacteria and other solids particles which are present. And the reason why filter paper is not able to be used in microfiltration is because its holes are too big and allows the bacteria to pass through.

10. After going through micro- filtration, the water would then move on to the next stage of the purification process. This process is known as Reverse Osmosis What is Reverse Osmosis? Reverse Osmosis is basically the process whereby the water is passed through a semi- permeable membrane. For this to happen, pressure must be applied to push the water through the membrane. This uses the concept of reversing the flow of water in normal osmosis and using the semi- permeable membrane as a filter. The Third barrier: Reverse Osmosis

11. Diagram of Normal Osmosis

12. Diagram of Reverse Osmosis

13. The Third barrier: Reverse Osmosis The Outcome of Reverse Osmosis In Reverse Osmosis, when the water passes through the semi- permeable membrane, only water molecules are allowed to pass through, thus impurities like chemicals drugs, viruses and dissolved salts are left behind. So, by the time the water has completed the process of Reverse Osmosis, the water is already of a high- grade quality.

14. The Fourth barrier: Ultraviolet disinfection This is the final stage of purification. After going through the process of Reverse Osmosis, the water would already be of a high- grade quality. However, as an added safety precaution, the water is then exposed to UV (Ultraviolet) radiation. This is to make sure that any micro- organisms left in the water are inactivated. After this stage, chemicals that restore the water's pH balance are added before the NEWateris ready for use.

15. Separation techniques Involved Some of the separation techniques involved in the process of purification are: 1) Filtration 2) Reverse Osmosis Filtration was used in the removal of bacteria and suspended solids from the water. This kind of filtration is known as Microfiltration as the holes are very small and are able to separate water from bacteria Reverse Osmosis was used in the separation of chemicals, drugs, viruses and dissolved salts so as to purify the water even further. After this stage of purification, the water would be of a very high- grade.

16. Diagram Of Microfiltration Filter Paper Retort Stand Filter Funnel Beaker

17. Diagram Of Microfiltration The previous diagram actually shows a simple filtration set- up, however, it encompasses the basic structure and concept of Microfiltration. The beaker in the set-up, represents the tank where water would be sent to the next stage of purification after Microfiltration. The filter paper in the set- up represents the membrane which is used to filter out the bacteria and suspended solids which are present in the water. The filter funnel represents the holding tank where the suspended solids and bacteria are kept after being trapped by the membrane.

18. Diagram of Microfiltration The picture on the right shows a hollow fibre which is used to make up the membrane used in microfiltration. This hollow fibre has many extremely fine and tiny holes and these holes are used to trap suspended solids and bacteria and prevent them from entering the next stage of purification. Thus, when the water is passed through this membrane made up of hollow fibres, bacteria and other solids would be left behind.

19. Diagram of Reverse Osmosis Water is of high- grade quality. Flow of water Semi- permeable Membrane

20. In reverse osmosis, a semi- permeable is used to purify the water. This semi- permeable membrane is similar to the one which is used in normal osmosis. In reverse osmosis, pressure has to be added to the water to force it to go through the semi- permeable membrane. After this stage, substances like chemicals, drugs, viruses and dissolved salts would be removed. Thus, after this stage of purification, the water would already be of a high- grade quality. Diagram of Reverse Osmosis

21. About Wastewater Treatment http://www.regulatorystaff.sc.gov/orscontent.asp?pageid=654 http://en.wikipedia.org/wiki/Sewage_treatment http://esa21.kennesaw.edu/activities/ww-treatment/ww-treat.pdf NEWater http://en.wikipedia.org/wiki/NEWater http://www.pub.gov.sg/about/historyfuture/Pages/NEWater.aspx http://infopedia.nl.sg/articles/SIP_1555_2009-08-11.html http://www.adb.org/Water/Actions/sin/NEWater-Sewage-Safe.asp bibliography

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