Singapore's Smart Moves About Water

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With water demand set to double by 2060, this water-stressed city-state is deploying innovative solutions to meet an urgent challenge

Water shortages, polluted rivers and widespread flooding used to be par for the course in Singapore, one of the most water-stressed cities in the world.

In recent years, the densely populated city-state has witnessed a gradual change for the better. But with water demand among Singapore’s 5 million residents set to double by 2060, the island-state’s challenge remains far from over.

So what’s being done to meet that challenge?

NEWater

Most bottled water comes with a picture of a mountain spring or glacial aquifer on the label. Not NEWater. Singapore’s answer to Evian or Volvic heralds from insalubrious origins: the city-state’s drains and sewers. It is “ultra-safe”, insists PUB, Singapore’s national water agency, which says the reclaimed water surpasses World Health Organisation standards.

The reclaimed water is treated conventionally first, then subjected to three additional purification processes: microfiltration, which provides a basic filter to weed out disease-causing bacteria and other nasties; “reverse osmosis” (common in desalination), which uses a semi-permeable membrane to eradicate further viruses, metals and the like; exposure to ultraviolet light, making doubly sure any remaining organisms are “inactivated”.

Introduced in 2003, NEWater isn’t used primarily as drinking water, although it is potable, but more in industrial and cooling applications. During dry months, it is also used to top up public reservoirs.

Currently, the city-state boasts four NEWater plants, which have a combined capacity to meet nearly 30% of overall water demand. PUB believes that figure can be nearly doubled to 55% over coming decades.

Vertical farming

Farming is a water- and land-intensive activity, and Singapore, with only 710 square kilometres to play with, is short of both. Currently a dismal 7% of vegetables are locally grown.

Enter Sky Greens Farm, the world’s first commercial vertical farm and the brainchild of local entrepreneur Jack Ng. Designed for the urban jungle, this greenhouse skyscraper minimises the inputs of both land and water by suspending plants in vertical racks rather than growing them in soil on the flat. The growing happens in modular, A-shaped towers (120 to date, and counting) that measure 9 metres tall and contain up to 32 tiers of growing troughs each. The latter rotate slowly to ensure the vegetables in this tropical urban farm get the requisite distribution of sunlight, airflow and irrigation.

A gravity-aided water-pulley system powers the rotation system using just one litre of water, which is collected in a rainwater-fed overhead reservoir. The “farmscraper” system also uses a low-volume flooding method for irrigation, with the water then recycled and reused. The organic waste from the farm is also recycled as compost, avoiding the potential pollution of local watercourses. 

Smart monitoring

Water loss, or “non-revenue water”, is a problem across the world. It’s not uncommon for countries to see a third of their treated water supply disappear in leaks and burst pipes. With a loss rate of one-fifth (20.7%), the UK performs relatively well. But it’s not a patch on Singapore, where non-revenue rates run at a mere 4.6%, one of the lowest levels in the world.

Helping the water-scarce city-state reduce losses even further is a new smart monitoring system, which uses multi-functional water sensors known as data sondes, developed by US-based water tech firm Xylem. The sensors feed data about pressure irregularities and other key factors into analytics software provided by local water monitoring firm Visenti, and this information is then sent to a central command centre by text message and apps.

Xylem and Visenti are currently co-developing a cloud-based service that will enable alerts to be sent via the internet to any device, even in remote areas. PUB uses the updates to adjust water flow and pressure in the water network, which cuts water losses due to leaks and clogged pipes.

Source: The Guardian

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