Wizards of the water cycle

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S i nga p o r e ’ s s k y l i n eg l e a m s b e h i n d t h em a r i n a r e s e r voi r .T h e n e w ly e n c l o s e db ay i s f l a n k e d b ya t h r e e - p i l l a r e dr e s o rt b u i lt o nr e c l a i m e d l a n d.t i n y t e s t b e d ss i n g a p o r e n m a l t as p e c i a l r e p o r t n w a t e r v s . e n e r g yWizardsof theWater CycleSingapore’s toilet-to-taptechnology has saved thecountry from shortages—and a large electricity billb y s a n d r a U p s o np h o t o s b y D a r r e n S o hspectrum.ieee.orgjune 2010 • IEEE Spectrum • NA 57
3. t i n y t e s t b e d s n s i n g a p o r e n d e s a l i n a t i o n n m a l t as i N G a P o r e B e G a N i t s J o U r N e yto sovereignty with a mighty jolt. Theisland was still an exotic outpost of theBritish Empire when World War IIdelivered the shake-up. Japan’s armywas preparing to invade from the MalayPeninsula, and the British forces beat aretreat to Singapore across the one bridgeconnecting it to the mainland. To thwartthe Japanese troops, the Royal Engineersblew up the bridge behind them.The blast sealed the island’s doom, forit also ruptured a critical pipeline thatbrought water from Johor, a Malay state.The people of Singapore discovered theyhad only a few days’ water stored intheir meager reservoirs. The island wastruly defenseless. The Japanese swiftlyrepaired the bridge, bicycled across thestrait, and claimed victory.Sixty-eight years later, this port cityhas both gained territorial independenceand managed to bootstrap itsway to wealth in spite of a lack of waterand energy. And now, against all odds,complete water independence—fromboth Malaysia and even the weather—is within easy reach. Rather than flushingwaste into the sea, the water utilitycollects the country’s wastewater, cleansit to pristine levels, and returns it to thepublic supply. Singapore has thus shortcircuitedthe water cycle by reducing it toan island-ringing loop.At first, no one relished the idea ofdrinking wastewater. Rejuvenatingthe waste stream requires electricityto power an intensive cleaning process,and that investment makes the recycledwater more expensive than what’s usedby cities blessed with nearby freshwaterlakes, rivers, and aquifers. But presentedwith a set of tough choices, Singaporechose water recycling—and so far it hasworked admirably.W h e N S i N g a P o r e F i N a l ly S e Pa r at e dfrom Britain and then Malaysia in the1960s, water was at the top of the agenda.The government negotiated two treatieswith its mainland neighbor to guarantee awater supply, at a cost, for the next century.With a base supply in place, the waterutility went looking for more. The agencystarted with the one resource availabler e v e r S e - o S m o S i Sm e m b r a n e Sat a n e wat e rp l a n t, ov e r S e e nb y h a r r y S e a h[ t op r ight ] , p r o d u c et h e n e wat e r S a m p l e db y c h i l d r e n.to this tropical dollop of land, its amplerainfall—some 237 centimeters a year.It built dams to interrupt the flow of itsstreams and tiny rivers and built 15 reservoirsto store rain. Such reservoirsare crucial because they stand in for thegroundwater that Singapore lacks.Then the utility did a radical thing.After half a decade of research and tests ata pilot recycling plant, Singapore’s plannersunveiled their ultimate strategy forwater security. They would force wastewaterthrough filters under high pressureto remove all microbes, viruses, andlarger impurities. The utility called itsproduct NEWater, and it called the treatmentplant a factory. With great emphasison its sparkling newness, treatedwastewater made its public debut in 2003.The real work was about to start. Oneby one, the utility cajoled its customersinto accepting the water. Manufacturerswondered what residues the water mightNEWaterTASTETESTthree choices: NeWater,bottled water fromMalaysia, and a glass filled atthe tap. your correspondentsat down to drink. theNeWater was bland toa fault, like paper madepotable. the Malaysianwater delivered a cloying aftertaste—a perplexingblend of dryer lint and berries. the drink from thetap, however, was just right.leave in their factories, but Harry Seah, theutility’s director of technology and waterquality, pointed out that NEWater wascleaner than most drinking water. “At firstI had to convince them,” Seah recalls. Butsoon enough, he had signed on the island’s12 wafer-fabrication plants and other electronicsmanufacturers, and the utilitylaid dedicated pipes to deliver NEWater.Now Systems on Silicon ManufacturingCo., which uses ultrapure water to washits silicon wafers, champions NEWater.58 nA • ieee spectrum • june 2010 spectrum.ieee.org
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