Best of our wild blogs: 17 Feb 18

Why (the heck) did I study giant clams?
Mei Lin NEO

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The long road to ensuring that Singapore's waste doesn't go to waste

Expensive tunnels and facilities are being built to tackle mounting waste and help carve out a greener future. But current habits on the ground could end up costing the nation dear.
Derrick A Paulo and Daniel Heng Channel NewsAsia 17 Feb 16;

SINGAPORE: Deep below the surface, deeper than any MRT line, work has begun on a mega project that – within a decade from now – will carry whatever you flush down the toilet if you are in the western half of the island.

The 100km of tunnels and link sewers being built will then take all their contents to Tuas – where every effort will be made to give sewage a new lease of life, including turning it into energy.

This S$6.5-billion second phase of the Deep Tunnel Sewerage System (DTSS) is part of Singapore’s new, holistic approach to ensuring that waste does not go to waste. (It comes after a similar sewerage superhighway to serve the eastern half of Singapore was completed in 2008.)

And with the start of construction last November, the work to reach a turning point in Singapore’s waste management strategy is now in full swing.

The DTSS joins two other projects in the works: The Integrated Waste Management Facility (IWMF) and the Tuas Water Reclamation Plant (TWRP), which for the first time, will see two such facilities co-located on the same site.

This trifecta of projects will be wholly completed in 2027.

But much has already gone on behind the scenes, especially to make the co-located Tuas facility the centrepiece of an innovative and greener waste disposal system.


The S$3-billion IWMF, a solid-waste management facility, will sort household recyclables, treat food waste as well as incinerate trash and sludge – a by-product of treating used water – all on a single site.

This will get more bang for the buck and break new ground for Singapore, as the processing of these various waste streams has been done in separate locations until now.

Tests on the technology to be installed in the Tuas plant are now being conducted, such as the mixing of food waste with sludge from used water to increase energy production.

This requires machines called digesters, which process the organic matter in used water sludge and food waste, breaking it down into biogas and carbon dioxide.

The biogas is then used to generate electricity on site, with the excess power sent to the national energy grid.

Sludge collected from sewage treatment has long been processed in this way, for example at the Changi Water Reclamation Plant.

But it was only recently – after years of rising food wastage but a stagnant recycling rate – that food waste has been turned into fuel prior to incineration.

Singapore’s first co-digestion test facility, in Ulu Pandan Water Reclamation Plant, was completed just over a year ago, and is processing a few tonnes of food waste a day.

“The fat, oil, grease, carbohydrates and proteins that are in the food waste, when combined with the used water sludge, will help to generate more biogas,” explained the PUB plant’s general manager Kelvin Koh.

“(Testing) such a full-scale application will help us to gain operational experience, identify potential gaps as well as ... build up to a full-fledged facility, in the future, at Tuas," he added.

He was speaking on Channel NewsAsia’s two-part special Looking Ahead, which examines how Singapore’s mega infrastructure projects are positioning the nation for the future. (Watch the episode here.)


With a solid-waste and a used-water facility on the same site, sludge and food waste will be easily available to make biogas. But that will not be the site’s only energy capability.

Like the four existing incineration plants, in the process of incinerating waste, the facility will produce electricity to run its operations, for long-term sustainability. Its incineration capacity will be sufficient to power 300,000 four-room Housing and Development Board flats.

In comparison with that, the 1,600 megawatt hour produced each day by the Tuas South Incineration Plant – which is Singapore’s largest waste-to-energy plant now – is enough to power 125,000 four-room HDB flats, about the area of Ang Mo Kio estate.

The co-location of facilities will ensure energy efficiency too.

“The processing of multiple waste streams at the IWMF and the co-location with the TWRP will enable the two facilities to maximise energy and resource recovery, and optimise land,” said IWMF project director Joseph Boey, from the National Environment Agency.

“The co-location has marked a new chapter. For future projects, we’ll continue to explore such set-ups, look into more synergies and attain even greater environment sustainability.”


Planning for the future is not only about energy, but also about land use.

For example, to keep water reclamation compact in Tuas, relevant technology is being monitored at another test facility in the Ulu Pandan Water Reclamation Plant, while helping with Singapore’s long-term water demands.

In conventional water reclamation, dirty water passes through a settling tank followed by a microfiltration system. But that process can be combined using a membrane bioreactor.

“In that sense, we’re able to save space and have a more efficient footprint of our plant,” said PUB senior engineer Anne Marie Ang. She added that the membrane tank has been able to yield water of “clearer quality”.

This puts the Tuas Water Reclamation Plant, a key component of the DTSS, on course to have the largest membrane bioreactor facility in the world.

The space saved with such investments in waste management will also go beyond the walls of the Tuas compound.

Once the second phase of the DTSS is in place – with tunnels built to last 100 years – the water reclamation plants in Ulu Pandan and Jurong will be phased out progressively.

As the tunnel system is being constructed at a gradient, the used water will be carried to the Tuas plant by gravity – without the need for intermediate pumping stations. These, too, will be demolished.

The entire DTSS will halve the area taken up by used-water infrastructure, from 300 hectares in the 1990s to 150 ha in the long term. This land freed up for higher-value development is equivalent to about 214 football fields.


The roads are another space where efforts in waste management will make more of a difference, with the pneumatic waste conveyance system.

This automated system uses vacuum suction in an underground pipe network to collect household waste from multiple apartment blocks and deposit the waste in a bin centre.

With a central collection site, waste disposal lorries will not have to go from block to block. This will help to reduce traffic in housing areas, among other improvements to liveability, while residents can dispose of their rubbish as usual.

More than 100 private residential developments have become early adopters. And from April, installation of the system will be mandatory for new non-landed private developments with at least 500 homes.

Meanwhile, the HDB is implementing it in new developments where possible, including Tampines North, Punggol, Bidadari and Sengkang. The authority is also studying the pilot test of the system in Yuhua, before deciding on its feasibility for other existing estates.

Ease of transport is already a consideration elsewhere in the waste management loop.

At the Changi Water Reclamation Plant, after energy is extracted from sludge, the remainder is dried to reduce its volume and weight before it is incinerated in the western part of Singapore, and the ash taken to the Pulau Semakau landfill.

“We have about 13 trucks a day come to Changi to remove dewatered and dried sludge to our incineration plants. Without (the sludge dryers), we’d need 30 trucks a day,” said the PUB plant’s general manager Low Pei Chin.'


One problem that is getting bigger, however, is the amount of wastage in Singapore: In 2016 alone, enough rubbish to fill 15,000 Olympic-sized swimming pools. This includes everything from the junk tossed out of homes to construction debris.

“It’s an urgent issue,” said Ministry of the Environment and Water Resources director (Environmental Policy Division) Ng Chun Pin. “So it’s very important for us to push (for) a strong national consciousness among Singaporeans, towards zero waste.”

The overall recycling rate is 61 per cent. This includes industrial and commercial waste. But households are not doing enough.

“The domestic household recycling rate hasn’t improved for many years, hovering at about 21 per cent in the last decade. To put it simply, our recycling habits haven’t kept up with purchasing habits,” said Mr Ng.

“We change our clothes, laptops and mobile phones – and much more frequently, with little or no recycling. We don’t reuse, we don’t repair, and many of these items, unused (and) brand new, end up prematurely in our incinerators.”

Without a change in habits, there will be consequences. At the current rate, a new incineration plant would be needed every seven to 10 years to keep up with the increase in solid waste.

And that is not the investment Mr Ng hopes Singapore will have to make. He said: “We’d rather build HDB flats, hospitals and schools for Singaporeans, not expensive landfills and incinerators.”

Watch this episode of Looking Ahead here.

Source: CNA/dp

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Pair with sugar gliders busted at checkpoint

Straits Times 16 Feb 18;

Immigration officers at the Woodlands Checkpoint made a "sweet" find in the early hours of Valentine's Day - two sugar gliders hidden in a car coming into Singapore.

The two animals, which are small, omnivorous, nocturnal gliding marsupials that live in trees, were found inside a pouch.

Officers from the Immigration and Checkpoints Authority of Singapore (ICA) also found 44 cartons and 210 packets of duty-unpaid cigarettes, hidden inside the dashboard and centre console of the car.

ICA officers referred the driver, a 25-year-old man, and the passenger, a 20-year-old woman, both Singaporeans, to the Agri-Food and Veterinary Authority of Singapore.

The duty-unpaid cigarettes and vehicle were handed over to Singapore Customs for further investigations.

In a Facebook post yesterday, the ICA reminded travellers not to import or keep wild animals as pets.

Under the Animals and Birds Act, it is an offence to bring into Singapore any animal without an import licence.

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Cleaning products a big source of urban air pollution, say scientists

Research shows paints, perfumes, sprays and other synthetic items contribute to high levels of ‘volatile organic compounds’ in air
Ian Sample The Guardian 15 Feb 18;

Household cleaners, paints and perfumes have become substantial sources of urban air pollution as strict controls on vehicles have reduced road traffic emissions, scientists say.

Researchers in the US looked at levels of synthetic “volatile organic compounds”, or VOCs, in roadside air in Los Angeles and found that as much came from industrial and household products refined from petroleum as from vehicle exhaust pipes.

The compounds are an important contributor to air pollution because when they waft into the atmosphere, they react with other chemicals to produce harmful ozone or fine particulate matter known as PM2.5. Ground level ozone can trigger breathing problems by making the airways constrict, while fine airborne particles drive heart and lung disease.

In Britain and the rest of Europe, air pollution is more affected by emissions from diesel vehicles than in the US, but independent scientists said the latest work still highlighted an important and poorly understood source of pollution that is currently unregulated.

“This is about all those bottles and containers in your kitchen cabinet below the sink and in the bathroom. It’s things like cleaners, personal products, paints and glues,” said Joost de Gouw, an author on the study at the University of Colorado in Boulder.

“When you think about how much of those products you use in your daily life, it doesn’t compare to how much fuel you put in the car. But for every kilogram of fuel that is burned, only about one gram ends up in the air. For these household and personal products, some compounds evaporate almost completely.”

Globally, the greatest source of volatile organic compounds are plants and trees, but the natural background levels are bolstered by vapours released from hairsprays and perfumes; cleaning products and pesticides; paints and lacquers, and substances such as formaldehyde, which is used in glues, plywood and other building materials. Yet more synthetic VOCs come from burning fuels such as gas and wood.

“It’s hard to say how much pollution is down to VOCs, but a rough estimate is that between one quarter and a third of all particles are made up of organic compounds that originate as VOCs,” said Alastair Lewis, professor of atmospheric chemistry at the University of York. In Britain, one of the most harmful air pollutants is nitrogen dioxide, which is unrelated to VOCs.

Writing in the journal Science, De Gouw and others report that the amount of VOCs emitted from household and industrial products is two to three times higher than official US estimates suggest. The result is surprising since only about 5% of raw oil is turned into chemicals for consumer products, with 95% ending up as fuel.

“This paper is interesting because it shows that domestic use of VOCs is beginning to dominate, displacing the traditional sources from vehicles and industry,” Lewis told the Guardian. “It’s a challenge for regulators since many of these sources, including cleaning and personal care products, aren’t controlled.

“If the paper is right then many countries will need to rethink how they plan to meet their international obligations to reduce emissions. The UK is already thinking about how to tackle and reduce domestic emissions,” he said.

William Bloss, professor of atmospheric science at the University of Birmingham, said the work highlighted a continuing need to understand real world emissions. But he added: “We have a much higher proportion of diesel traffic in the UK and we know that diesel use is associated with a lot of different hydrocarbons and particulates. I suspect that in the UK, traffic in the form of diesel vehicles is still the most important.”

Even so, De Gouw believes VOCs from household products should still be factored into policies on emissions. “London is a little different to LA because of the higher diesel use, but I expect that even in London a significant fraction of VOCs will come from these kinds of emissions,” he said.

David Green, who studies air pollution at King’s College London, said: “Organic aerosols, which are produced when these volatile chemicals react in the atmosphere contribute significantly to UK PM2.5 concentrations as they do all over the world. In London, where we measure these routinely, approximately a third of PM2.5s can be attributed to organic aerosols which come from a range of sources including vehicle emissions, wood burning and even cooking. This paper highlights a previously poorly understood source which is currently unregulated.”

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