22nd October

Today is a busy day. We booked a visit at the Newater plant for noon, and meet a researcher in Energy in the afternoon. After a little swim in the morning (who could have resisted?), we head towards the Newater plant. It is in the East of the city, very near the airport. As we left a little late, we arrive a little late, but we manage to have the visit as expected. We accompany some professionals from Japan and Indonesia for the visit.

In Singapore, part of the waste water (grey + yellow + brown) is recycled into NEWater. Currently, half of Singapore waste water goes to NEWater, through the Deep Tunnel Sewerage System. In the years to come, the whole city will be connected. Every drop of water is used more than once. The technology allowing that was developed to overcome lack of natural water. The idea of reclaimed water started in the early 1970s, but it was only in 2000 that technology became stable and economically viable. When NEWater was first introduced in Singapore, reusing reclaimed water was a new concept.

They define NEWater as high-grade reclaimed water produced from treated used water. It is purified with advanced membrane technologies, making it ultra-clean and safe to drink. The technology has been developed by PUB (Public Utility Board) after three decades and has passed more than 65 000 scientific tests. The NEWater does not contain any minerals.

The NEWater is used in two ways. The first one is the direct non-potable use, for around 95% of NEWater production. It is supplied to wafer fabrication, electronics and power generation industries for process use. It is also piped to commercial and institutional buildings for air conditioning cooling purposes. One could wonder why the industry gets such an important part of this ultra-clean water: it’s because in many process, they need water without minerals, and previously, they had to treat the tap water to use it. Now with NEWater, the water they receive is directly what they use. The second usage is the direct potable use. Less than 5% of the water produced is blended with raw water in the reservoir, so that it is re-mineralized. The raw water then goes through treatment at the waterworks before it is supplied to consumers as tap water.

Since its launch, demand for NEWater has grown 15-fold from 4 mgd (million gallon per day) in 2003 to some 60 mgd in 2012. Currently, NEWater meets 30% of Singapore’s water needs. By 2060, NEWater’s capacity will be tripled so that the NEWater can meet half of the demands.

They are three steps in the purification process for the production of NEWater: 1) microfiltration / ultrafiltration 2) reverse osmosis 3) ultraviolet disinfection. Microfiltration/ultrafiltration is done with a microfilter which pores measure 0,04 µm, thus blocking many particles, bacterias and even most of the viruses. The filters can be seen as straws (or empty spaghetti) where the water can enter from the sides, through pores, and is pumped through the straw.

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On the second step, the water goes through a membrane which pores measure 0,0004 µm, as part of the reverse osmosis process. This reverse osmosis is the main technological advance of the NEWater plant. There, oestrogen endocrine disrupters, and viruses and bacteria that may have passed, are separated from the water. The negative aspect is that the membrane also retains minerals. Only water molecules can go through.

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At the end of this step, 75% of the water has been treated, and the 25% remaining is reinjected inside the waste water to be retreated. Nothing is lost. Finally, the water goes through a last stage of ultraviolet disinfection. This step is not really needed since the water is already ultra-clean after step two, and has been certified as drinkable by WHO at step two already, but it is intended to break psychological barrier and as a double safety. The water spends less than 1s around the UV lamp. This lamp is heated at 800ºC but placed in vacuum so that it does not heat the water to more than 60ºC, and its UV emission is 100 times what we receive from the Sun. At the end of the process, the water may be stored. In contact with the aire, the water can become a bit acidic, by dissolving carbon dioxide, which produces carbonic acid (H2CO3). This is why, sodium hydroxide is added in order to correct the pH. Therefore, the NEWater produces contains nothing else but 5 mg/L of Sodium.

At the end, we are offered a bottle of NEWater for a small degustation of this water. The water tastes a little like a medicine, or like swimming pool water, maybe due to the sodium.

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