Water & Wastewater Asia March/April 2024

FOCUS
Sludge generated during wastewater
treatment is also typically high in moisture
content, which makes it bulky and
expensive to transport and dispose of.
Incineration helps to reduce the volume
of sludge — typically to 1% or less — by
evaporating the water content, making it
more cost-effective for disposal which in
turn helps to prolong the lifespan of our
limited landfill. Additionally, sludge can
produce unpleasant odours — including
methane gas emission, about 25 times
the global warming index of CO2 — due
to the decomposition of organic matter.
Incineration helps to eliminate these odours,
improving the environmental conditions
around the disposal site.
1
1 Innovatherm’s sludge
incineration in Lünen,
Germany, is said to
be the largest in the
world
2 The oldest
operating FBI sludge
incineration plant
since 1976 is in Visp,
Switzerland
3 IWMF at Tuas Nexus
Incineration of sludge can also help recover
energy from the organic materials present.
The heat generated during incineration can
be used for steam generation or electricity
production, offsetting some of the energy
requirements of the WWTP. In Lünen,
Germany — the largest single line FBI in
the world which was built by our team —
low calorific coal is mixed with the sewage
sludge to generate excess electricity to
power up the nearby township. Incineration
helps with landfill mining too, as the ashes
collected can be further processed to
useful construction materials.
2
Finally, governments in Europe are
pushing to ban co-incineration in
Municipal Solid Waste (MSW) incineration
plants and co-incineration in cement kiln
because of their low energy efficiency,
stringent phosphorous recycling and
ash collecting requirements. There is a
growing interest worldwide to recover
phosphorus from municipal WWTPs
for use in plant fertilisers. For instance,
Germany stipulates phosphorus recovery
from WWTPs with at least 100,000
population equivalents (PE) to be made
mandatory by 2029.
NOVEXX’S LATEST PROJECT IN
SINGAPORE
Tuas Nexus is the first of its kind facility that
is planned from ground up and is designed
to harness process on the concept of
achieving synergies between NEA IWMF
and PUB, Singapore’s National Water
Agency — Tuas Water Reclamation Plant
(WRP). Tuas Nexus is said to optimise
both energy and resource recovery in
solid waste and used water treatment
processes while further reducing the
environmental and land use footprint.
3
As part of the IWMF project, the facility
consists of two FBIs using the Raschka
technology.
Reference:
1 US EPA. Overview of greenhouse gases.
Images: Novexx
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