NEWater
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NEWater (Chinese: 新生水) is the brand name given to reclaimed water produced by Singapore's Public Utilities Board. More specifically, it is treated wastewater (sewage) that has been purified using dual-membrane (via microfiltration and reverse osmosis) and ultraviolet technologies, in addition to conventional water treatment processes. The water is potable and is consumed by humans, but is mostly used for industry requiring high purity water.
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[edit] History
Water recycling in Singapore began in 1974 but the experimental treatment plant was closed a year later due to cost and reliability issues. [1]
The Singapore Water Reclamation Study (NEWater Study) was initiated in 1998 by the Public Utilities Board (PUB) and the Ministry of the Environment and Water Resources (MEWR). The aim of this study was to determine if NEWater was a viable source of raw water for Singapore's needs. NEWater and desalination were explored as means to reduce reliance on water imported from Malaysia, which has been a source of friction over the years. Also, while the Malaysian government was treaty-bound to sell Singapore water until 2061, it was under no obligation to do so after this.
In 2001, PUB began an effort to increase water supplies for non-potable use. Using NEWater for these applications would reduce the demand on the reservoirs for potable water.
[edit] Production
Singapore has a total of four operational NEWater factories, at Bedok, Kranji, Ulu Pandan and Seletar Water Reclamation Plants, with the former two completed at the end of 2002, and the latter in February 2004 and the Ulu Pandan plant on March, 2007. There is a Visitor Centre near Tanah Merah MRT Station, which contains a working NEWater factory for educational purposes. Tours and a private shuttle from Tanah Merah MRT station may be booked through the Visitor Centre. [2]
[edit] Process
NEWater is the product from a multiple barrier water reclamation process:
- The first barrier is the conventional wastewater treatment process whereby the used water is treated in the Water Reclamation Plants.
- The second barrier, and first stage of the NEWater production process, uses microfiltration/ultrafiltration to filter out 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, and second stage of the NEWater production process, utilizes reverse osmosis (RO). In RO, a semi-permeable membrane filters out undesirable contaminants such as bacteria, viruses, heavy metals, nitrate, chloride, sulphate, disinfection by-products, aromatic hydrocarbons, and pesticides that cannot pass through the membrane. Hence, NEWater is free from viruses and bacteria and contains very low levels of salts and organic matter. At this stage, the water is of a very high quality.
- The fourth barrier, and third stage of the NEWater production process, acts as safety precaution. 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 pH balance, the NEWater is ready for use.
[edit] Applications
At present, the total capacity of the three factories is about 20 million US gallons per day (75,700 m³/day). About 6% of this is used for indirect potable use, which contributes 1% of Singapore's potable water requirements of 300 million US gallons per day (13 m³/s). The rest of the water is used at wafer fabrication plants and other non-potable applications in industries in Woodlands, Tampines, Pasir Ris, and Ang Mo Kio.
[edit] Potability
PUB claims that the main reason why NEWater is not used as potable water directly is the psychological barrier of consuming (treated) sewage. Adding treated NEWater into the reservoirs helps to ameliorate this problem. The second reason PUB gives is that NEWater lacks minerals removed during the reverse osmosis process, and this changes the taste of the water.[3]
The quality of NEWater consistently exceeds the requirements set by USEPA and WHO guidelines and is, in fact, cleaner than the other sources of Singapore's water.[3]
Plans are under way to increase the amount of NEWater in indirect potable use up to 2.5% by 2011.[3]
[edit] References
- ^ Water Management Issues in Singapore
- ^ NEWater
- ^ a b c Public Utilities Board, NEWater FAQ, accessed 8 Jan 2007.
