New used water and waste treatment plant in Tuas to expand water supply and landfill lifespan

National water agency PUB's booth at the World Cities Summit, one of three sustainability events taking place at Marina Bay Sands this week. ST PHOTO: KHALID BABA

SINGAPORE - More than $5 billion in tenders will be called for a new plant in Tuas that will utilise waste to expand the Republic's water supply and extend the lifespan of its one and only landfill on offshore Semakau Island.

The tenders, which will be called over the next five years, involve civil, mechanical and electrical engineering works. They are for a novel, first-of-its kind facility in Tuas, which will incorporate both used water and waste treatment plants in one facility, said national water agency PUB and the National Environment Agency (NEA) on Monday (July 9).

Construction of the facility is expected to start next year (2019), and will be completed in phases from 2023. It is expected to be fully ready by 2027.

Tuas Nexus will be the first plant that enables PUB to reclaim industrial used water, for use by industries on Jurong Island and Tuas. Traditionally, industrial used water is treated before being discharged into the sea.

Tuas Nexus will also be the first to treat both used water and food waste in the same plant to produce biogas.

Used for electricity generation, biogas is produced when organic material in food waste or sludge from used water react with bacteria.

By combining used water sludge with food waste, Tuas Nexus will be able to increase the amount of biogas produced by 10 per cent. This is because of the higher organic content in food waste, said PUB principal engineer Mark Wong.

Coupled with other renewable energy sources at Tuas Nexus - including solar panels and the conversion of heat produced by the incinerators to electricity - the plant will be completely energy self-sufficient.

This means it will not need to draw fossil fuel-generated electricity from the grid to power its operations, said NEA and PUB in a statement.

In fact, excess electricity - enough to power up to 300,000 homes - will be exported back to the national grid.

Said Mr Yong Wei Hin, director for PUB's deep tunnel sewerage system phase 2: "The Tuas Nexus is a bold innovation in the action for climate change and sustainability. This pioneering facility... marks a new way in which used water and solid waste will be treated in Singapore."

He was speaking to the media at the Tuas Nexus showcase at the Singapore International Water Week and CleanEnviro Summit Singapore conferences held at the Marina Bay Sands.

The integration of both water and waste treatment plants in Tuas Nexus will result in overall carbon savings of more than 200,000 tonnes of carbon dioxide emissions every year - equivalent to taking 42,500 cars off the roads.

The new plant, which will also allow incineration bottom ash (IBA) to be extracted from waste, will enable Singapore to expand the lifespan of Semakau Landfill, said Mr Joseph Boey, project director at NEA's integrated waste management facility.

Some 20 per cent of every tonne of incinerable waste comprises incineration bottom ash.

"If we are able to extract this IBA for use in other areas, such as in construction, we will be able to reduce the amount that goes into the landfill and expand the lifespan."

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