Even as new policies are implemented and infrastructure developed to achieve our vision as a Zero Waste Nation, we will need to continually improve existing waste management technologies to enhance our treatment of waste and recovery of resources.
For decades, Singapore has invested in
infrastructure to collect, recycle and turn
our waste to energy. Our waste collection
infrastructure, such as refuse chutes, bin
centres and waste collection vehicles
have served us well in maintaining high
environmental public health standards by
ensuring that waste is properly collected and
sent for disposal. Our Waste-to-Energy (WTE)
plants, which reduce waste to ash, enable
extensive space savings at Singapore’s only
landfill while recovering energy from waste.
However, we want to go beyond converting
waste into energy, to produce greener forms
of energy such as syngas and recover other
valuable resources from waste, such as
turning waste into feedstock for the chemical
industry. At the same time, we want to
reduce the landfilling requirements from
any residue of the waste treatment process.
This will reduce our carbon footprint from
incineration and further extend the lifespan
of Semakau Landfill.
The Government has set our sights on closing
the waste loop by encouraging Singaporeans
to waste less and recycle more, developing
new policies, and investing in research and
development to find new ways to convert
waste into usable, and even marketable
products. This includes upgrading our waste
management infrastructure, from collection
to waste treatment and post-treatment
options. We want to make waste collection
more manpower-efficient, improve the energy
efficiency of our WTE plants, and create new
material out of incineration bottom ash (IBA).
Here is how we plan to do it.
PNEUMATIC WASTE CONVEYANCE SYSTEM
Waste collection today is often associated with
unpleasant odours and pests. Within many
developments, it is also manpower intensive for
waste to be transported from refuse chutes to
the bin centre.
The Pneumatic Waste Conveyance System
(PWCS) provides a solution to these problems. It
is an automated waste collection system which
conveys waste by air suction from individual
buildings through a network of pipes to a central
location for collection. This removes the need
for manual collection of waste from individual
refuse chutes. As an enclosed system, waste is
not exposed throughout the transfer process,
reducing odour and pest problems. Waste
collection can become more manpowerefficient.
PWCS will offer a cleaner and more
Illustration of a Pneumatic Waste Conveyance System Photo: Envac
To increase the adoption of PWCS, since
1 April 2018, new development applications
for non-landed private residential
developments with 500 Dwelling Units (DUs)
or more have been required to implement the
system. This adds to over 140 existing private
residential and commercial developments
Further economies of scale can be reaped by
implementing district-level PWCS (DPWCS).
Instead of bin centres for each development,
the district can share a central bin centre,
which can be located away from residents’
homes. This will also reduce refuse truck
traffic within the district, as refuse will
only be collected from one bin centre. HDB
has already introduced DPWCS in new
HDB estates such as Tampines North,
Punggol North and Bidadari and will also be
introducing it in the latest new town, Tengah.
The first DPWCS to serve multiple private
developments is being planned for the
Kampong Bugis precinct. It is expected
to serve commercial developments and
approximately 4,000 private residential DUs.
Through these efforts, the Government aims
to mitigate future challenges that the waste
collection industry will face due to increasing
manpower shortages and an ageing
PILOT MECHANICAL BIOLOGICAL TREATMENT FACILITY
Designed to recover materials from refuse,
a pilot Mechanical and Biological Treatment
(MBT) facility offers an alternative way to
treat Domestic and Trade Waste (DTW).
It will have a mechanical process to recover
recyclables like plastics, ferrous and nonferrous
metals, and an aerobic biological
treatment process to convert the waste into
Solid Recovered Fuel (SRF). Only a small
amount of residue will be left for disposal.
The pilot facility will be able to treat 500
tonnes of DTW daily. The mechanical
process will be able to recover up to 15%
of recyclables, or over 500,000 tonnes of
recyclables over 20 years. With this, we are
able to extract valuable recyclables from
waste that would otherwise be incinerated,
allowing the materials to re-enter the value
chain. Whatever is not recovered will undergo
a biological process which produces SRF as
an end product.
The NEA will monitor the operation of the pilot
facility and assess its viability for
TUASONE WASTE-TO-ENERGY PLANT
The TuasOne WTE plant – Singapore’s 6th
WTE plant – illustrates the circular economy
principle of resource efficiency. With a
treatment capacity of 750 tonnes of waste
per day per ha (t/d/ha), it will be the most
compact plant in the world. It will also be the
most energy-efficient among Singapore’s
existing WTE plants.
Built to meet part of our waste incineration
needs for the next 25 years, the plant –
developed on 4.8 ha of land – will have the
capacity to incinerate 3,600 tonnes of
waste per day.
Artist’s impression of TuasOne Waste-to-Energy plant
TUAS NEXUS: INTEGRATED WASTE MANAGEMENT FACILITY
By co-locating and integrating the treatment
of solid waste and used water, Tuas Nexus will
be able to recover resources from waste more
efficiently and with less space.
Tuas Nexus will comprise the NEA’s Integrated
Waste Management Facility (IWMF) and PUB’s
Tuas Water Reclamation Plant (TWRP).
Artist’s impressions of Tuas Nexus
The IWMF will use advanced technologies to
handle multiple waste streams and construction
will be completed over two phases. The first
phase of IWMF will be completed by 2024 while
the second phase is estimated to be completed
What makes the IWMF novel?
Expected to produce enough electricity to
power about 300,000 four-room apartments
a year, the IWMF comes with a slew of
Its combustion processes and boiler designs
will operate at high steam parameters of
about 440oC/55 bar as compared to
365oC/33 bar at our existing WTE plant.
The use of external biogas super heaters
will further boost the steam parameters at
IWMF from 440oC/55 bar to 480oC/55 bar to
achieve high overall plant energy conversion
efficiency of about 28% and maximise
To keep its environmental impact to the
minimum, the IWMF will adopt a Wet Flue
Gas Treatment (FGT) system that produces
the cleanest possible air emissions and
fulfils Singapore’s air emission requirements.
The Wet FGT system will also minimise the
amount of solid residue for disposal as less
fly ash is generated compared to conventional
dry FGT systems.
Processes within a Wet Flue Gas Treatment System
The IWMF will be designed as an iconic,
green development to showcase the
NEA’s vision as a leader in environmental
stewardship to achieve zero waste and
a circular economy. The Tuas Nexus
will integrate processes and systems to
optimise resources and achieve long-term
HARVESTING INCINERATION BOTTOM ASH FOR CONSTRUCTION
While we reduce our waste to just a fraction
of its original volume on a daily basis, the
resulting ash still takes up space on our
offshore Semakau Landfill.
Each year, about 500,000 tonnes of IBA and
200,000 tonnes of non-incinerable waste
are disposed of at the landfill. At this rate,
Semakau Landfill will be full by 2035.
To divert IBA from our landfill, we are
developing ways to use it in non-structural
construction such as road base/sub-base
materials or aggregates in non-structural
concrete as “NEWSand”. This is a key strategy
to maximise resource recovery and the
lifespan of current and future landfills.
The NEA is developing environmental
standards and guidelines to regulate the use
of NEWSand, and ensure that the environment
and public health are not compromised.
A tender for the demonstration of IBA
treatment methods was awarded in 2018 to
identify and validate treatment methods that
would render it suitable and environmentally
safe for use. Field trials will be conducted after
the demonstration. More details can be found
in Chapter 6.
If successful, the use of IBA in non-structural
applications, together with new waste
treatment facilities that maximise waste
recovery such as the MBT facility, TuasOne
WTE Plant and Tuas Nexus, will help us to
treat the waste disposed of more efficiently,
maximise resource recovery and reduce waste
residues sent to Semakau Landfill.
IBA pit at Tuas South Incineration Plant. NEA is studying the use of IBA for non-structural construction purposes