Our 2-cent-worth Evaluation

From an amateur’s point of view, Singapore has done well to upgrade its purification system to membrane technology. Not only is this a good water management practice as they anticipate for lower quality water from Marina Bay Barrage, it is also to be ahead in technology. Singapore as a Water Hub must have the courage to try on new technology even though it may be more costly than the traditional purification system.

However other technology can be explored especially if it will produce water at a lower cost. Membrane requires electricity to run and rising fuel cost may cause this technology to not look as promising as it is now. Therein lies the solar-powered water purification system yet unexplored. Other developed countries like United States have tested such system in order that each household may become a self-sufficient water purification unit.

In conclusion, it is good that Singapore keeps abreast of water technology. However we hope Singapore will continue to explore different water purification technology, and perhaps even water management.

Membrane Purification Process

The membrane water purification process can be seen in the below figure:1. Reservoir
Similar to the conventional purification process, the water is gently mixed by aeration process in the reservoir.

Then, the water is fed to the waterwork through pipe for purification.

2. Screening
Screening trapped large objects to ensure there is no damage done on the membrane that is used to purify the water.

3. Coagulation and flocculation
Chemical substances such as alum and lime are added to the water.

However, in membrane purification process, the amount of the alum that is needed is smaller compared to that in the conventional purification process.

The reason for this difference is while the conventional purification process requires the settling down of the sediment for easy removal, the membrane purification process is able to filter them.

4. Immersed ultra filtration
In this process, water is being sucked out through a semi-permeable membrane (i.e. many tiny holes on the surface of membrane).

Clean water will be sucked into the membrane, leaving behind the impurities. This clean water is then pumped out from the membrane.

In the filtration process, not all the water is subjected to the further purification, as 5% of the water is rejected.

This process is done in membrane tanks. Chestnut Avenue Waterworks in Singapore has 16 membrane tanks, each of them has 5 cassettes, and each cassette consists of 64 modules. Each one of the modules consists of more than 2000 membranes. Therefore each tank will have 640000 membranes. So cool!

This is the picture of the cassette:

5. Re-lift pumping station
In this process the water is pumped to the next station, which is the chlorine contact tank.

6. Chlorine contact tank
Same as the conventional purification process, fluorine and chlorine are added to the water,when it is broght to the chlorine contact tank.

Chlorine plays important role in the purification of water as it acts as disinfectant and it also helps to take care of the water's colour.

7. Clear water tank
Lime is added to the water in the process of going to the clear water tank.

Lime plays a role in the adjustment of pH of the water.

8. To supply network
Ammonia is added also to the water fr the same aim that is mentioned in conventional purification process above.

This purification , unlike the conventional purification, does not require that much space.

It is also able to purify water from lower quality, and thus this purification act as a preparation for the opening of Marina Bay Barrage, which is located at an urban area, and predicted to contain more polluted water.

Moreover, using membrane technology makes Singapore stays advanced in its water purification technology and keeps up with world's development.

However, membranes have shorter lifespan compared to the machines in the conventional purification process, for example the sand in the filter needs to be replenished every ten years, while the membranes have seven years of lifespan.

This purification also need more electricity and the maintenance fee is also higher as it needs more regular maintenance than the conventional way. Thus it has higher operating cost, reaching 30% more than that of conventional purification.

Conventional Purification Process

The conventional water purification process can be seen in the below figure:1. Reservoir
Water from the reservoir are mixed with the imported water from Malaysia. Here, water is mixed by pumping air into the reservoir to create convection currents. The Aeration described above will promote homogeneity and control odour.

The water is then fed to the waterwork for purification process.

2. Coagulation and Flocculation
Chemical substances are added to water in this stage:

a. Lime: used to control the pH of the water.
b. Aluminium sulphate (Alum): cause impurities in the water to clump together as flocs. As the size of flocs becomes larger, it becomes easier for them to be deposited in the next process.
c. Chlorine: act as disinfectant.

3. Sedimentation
The particle that coagulate will settle down in this process.

4. Sand Filtration
An example of a sand filter:

5. Chlorine Contact Tank
Before sending to the chlorine contact tank, fluorine and chlorine are added to the water.

Fluorine helps in the development of strong teeth and bones for children. It is added in under the instruction of Ministry of Health.

6. Clear Water Tank
In the process of going to the clear water tank, lime is added to the water for the pH correction.

7. Supply Network
Before the water is sent to the supply network, ammonia is added to the water.

Ammonia will react with chlorine to become chloramine. Chloramines are weaker disinfectants than chlorine, but are more stable, thus extending disinfectant benefits throughout a water utility's distribution system.

This purification process is done by most reservoirs in Singapore. Conventional purification actually needs a lot of space for the equipment used. In both Bedok and Chestnut Avenue Waterworks, all the processes are clearly segmented. One low-rise structure is designated as the sedimentation station, another one as the chlorine contact tank, and so on. Wow!

Introduction

NeWater in Singapore has caught hold of the international attention but that is not all it is to the changes made in local water scene. Singapore in anticipation of the completion of Marina Bay Barrage, sets out to upgrade technology in local waterworks where the main aim is to purify water for consumption.

We have conducted some research and visited Bedok Reservoir and Chestnut Avenue Waterworks in order to obtain first-hand information about two current water purification system implemented in Singapore.

Singapore and Water
Singapore is a small country that has won respects from other countries for its economic success despite the lack of natural resources. She is also leading in water technology in South East Asia.

With a population of over 4.35 million people living on a land area of 697.1 km² Singapore is one of the most densely populated countries in the world. The current demand for the potable water is up to 1.3 million m³ per day. Up to now, there have been several policy made by the government to meet the challenges.

Four National Taps of Singapore sums up the four sources of consumable water, mainly:
1. Local Catchment Water
2. Desalinated Water
3. NeWater
4. Imported Water from Johor

Water from local catchment areas will be channeled to various waterworks in the island. It will then undergo purification and sent to service reservoir for storage and distribution.

Two water purification systems used locally are:
1. Conventional Purification Process
2. Membrane Purification Process

We will furthermore explain the different water purification processes in separate postings. We hope you enjoy our blog and we are very happy to be able to share our knowledge! :)

Welcome to Our Blog! :)

Welcome everyone! :D We are Secondary 3 students from Convent of Holy Infant Jesus (CHIJ) Toa Payoh Secondary School Singapore, namely Charissa, Kantheera, Maria Natasha, Nadia and Theresia.

We are here to share our knowledge about Singapore's water management and purification system. Do share with us what you know about your country's water purification system too.