Water in Singapore

                                        Independent Research-Term 2

     Hi all, welcome to this post on Singapore's water.

      To start of, before you read this article, you may have started to think. Where does Singapore's water come from? Why do we say that Singapore's water is so clean that it can be drank directly from the tap?
     Well, these questions bothered me a little when I was tasked to do this article. Many would say that it's because of  NEWater. Very simple answer. However, I will be looking more deep into how Singapore manufactures its water and the Science that our water contains.
     We first have to start from basics. Singapore has four main sources of water, known as our Four National Taps. They are:
1)Water from local catchment areas(like reservoirs)
2)Imported Water(most from Malaysia)
3)Reclaimed Water(the famous NEWater)
4)Desalinated Water

      Great. We are now done with the basics. Now the science part. I will be focusing more on one of the National Taps today -NEWater as it covers on the method of Reversed Osmosis, one of the many methods of purifying water.

     What is reverse osmosis? Basically, contaminated water is forced through from one side to the other side of a semi-permeable membrane. Since the contaminants are kept on one side, we can obtain purified water on the other side of the membrane.(A pictorial explanation is shown on the left)

      Interestingly, reverse osmosis is not the only way to purify water. Other methods include Boiling water(Distillation Method), Ion Exchange(using the idea of positive and negative ion attraction to removed unwanted substances), Carbon Absorption(using carbon to take in impurities), Ultra Filtration(using molecular sieves), Ultraviolet treatment(ultraviolet light kills bacteria) and many more.
      

Ion Exchange

Distillation Method

    

Ultra Filtration

Carbon Absorption

Ultraviolet Light Filtration

        Why then does Singapore use Reverse Osmosis? For a start, organics with boiling points lower than 100 °C cannot be removed efficiently and can actually become concentrated in the product water. Distillation also requires large amounts of energy and water. Not cost effective! Next, Ion Exchange does not effectively remove most organics or microorganisms. Carbon Absorption  is usually used in combination with other treatment processes, which means that depending solely on this is not enough. Similar to Ion Exchange, Ultra Filtration membranes will retain most, but not necessarily all, molecules above their rated size. Lastly, Ultraviolet Light Filtration will kill bacteria but not necessarily filter off contaminants.

         So, comparing all the different filtration methods, seems like Reverse Osmosis still wins after all! 
Credits:
Michigan State University
esp water products
PUB-Public Utility Board
 LT Technology
 Pro Brewer.com
IJAPS 
Aid Gear
Emerald Insight
About.com