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Not Going to Waste
The role of food waste disposers as part of a total waste management solution
Introduction
Waste generation, Population & GVA, 1997-2012
INDEX WASTE GENERATED POPULATION GVA
300
250
200
150
100
50
0
1997-98 1998-99 1999-00 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09 2009-10 2010-11 2011-12
In the face of a rapidly growing population, nding an
appropriate method of dealing with household waste
continues to be a matter of heightened importance. Food
waste accounts for more than 30% of the total rubbish
in household garbage bins therefore suitable treatment
reduce their dependency on unpredictable price uctuations
of fuels. From a waste management and environmental
impact perspective, state and local governments are
committed to the issue of climate change and proving
measures to avoid methane emissions from landlls.
options for this organic component could help alleviate a
global waste problem.
Therefore alternative methods of food disposal would
potentially impact signicantly. Food waste disposers while
At a global level countries are keen to reduce their reliance
on fossil fuels and provide alternatives to wood fuel. At a
national level, residents, commerce and industries want to
serving a practical function in terms of household hygiene
and convenience have the potential to provide a number of
benets on a far broader scale.
What happens to food that is thrown away?
Australia is heavily dependent on landll as a means of
waste management. In fact, the majority of non-recycled
waste will end up in landll sites.
Estimates suggest each household produces close to 1.5
tonnes of waste each year. And nearly half (47% in 2009-
10) of all household waste is organic – namely food scraps.
One concern is that waste generation has been growing
at a disproportionate rate. Between 1997 and 2012 – when
overall population growth was 22% – the volume of waste
production jumped by 145%.
3
The problem here is that landlls are effectively an ‘out of sight,
out of mind’ solution. They potentially have a detrimental impact
on surrounding air, water and land quality. There are, however,
better ways of managing wastes, especially food waste.
A by-product of anaerobic organic waste decomposition is
2
a gas which consists of around 50% methane. Methane in
the atmosphere is a strong contributor to climate change,
being over 20 times more potent in this regard than carbon
dioxide.
4
harnessed as a valuable renewable energy source. Using
a food waste disposer can facilitate just that without the
social dis-amenity associated with landlling.
1
However, if captured and ‘cleaned’, it can be
Source: Australian Bureau of Statistics Waste Generation, Population & GVA 1997-2012
Food waste and renewable energy
Instead of piling food waste into bins and, ultimately, landll,
food waste disposers can be used to grind food scraps
which is then sent via the sewerage system to a wastewater
treatment plant. Here appropriate facilities use a process
called ‘anaerobic digestion’, to convert waste to biogas.
Anaerobic digestion is a collection of processes by which
microorganisms break down biodegradable material such as
organic food waste in the absence of oxygen.
5
The anaerobic
digestion process produces a biogas methane.
When cleaned, the methane fraction can be stored,
pressurised and used to generate on-site power and heat.
The power can be used on-site with surplus fed into the
electricity grid. Methane can also be upgraded to natural
gas-quality biomethane, and a by-product of the digestion
process is a nutrient-rich digestate which can be used as
fertiliser
6
for areas such as golf courses, playing elds
and pasture lands.
5
Anaerobic Digestion in Australia
The concept of using anaerobic digestion to produce
valuable biogas and hence renewable energy has actually
existed for many years. However the technology has
continued to be rened and countries such as Denmark,
Sweden and the UK are now championing a true paradigm
shift in waste management. With that said, Australia’s
commitment to wastewater treatment is also growing.
Sydney Water is just one of many wastewater treatment
companies employing the process of anaerobic digestion,
boasting 14 plants with anaerobic digestion facilities. Eight
of the plants have cogeneration (biogas burned in engines
to generate electric power), producing over 53,000MWh of
electricity per year. Sydney Water aims to harness the natural
anaerobic digestion process to maximise its renewable energy
generation and possibly expand its services to customers
beyond traditional water industry services.
Anaerobic digester systems in Australia are continuing to
be embraced due to further understanding of their benets
and the development of technologies. Over and above the
7
numerous wastewater treatment plants currently employing
anaerobic digestion there are several organisations
providing grants for construction of biogas plants and
installation of digester systems. These organisations include
Low Carbon Australia and the Australian government’s
Clean Technology Investment Program.
Yarra Valley Water has this year completed designs on its
rst dedicated Waste to Energy facility in the northern
suburbs of Melbourne.
Maxcon, an Australian Company specialising in industrial
wastewater treatment and building is set to commence by
the end 2014.
Other Anaerobic Digestion plants processing food waste in
Australia include TPI/Veolia digestor at Camellia, Biogas
plant at Richgrow in Perth, plus several others. With more
and more companies announcing their plans to invest in the
construction of anaerobic digestion plants, adopting wasteto-energy technology, the way we view food waste disposal
is set to change.
8
They have partnered Aquatec-
Slurry and manure
Anaerobic
digester
Food and amenity waste
Digestate
Crops and residues Heat
InSinkErator® Food Waste Disposers
InSinkErator offers a quicker and more efcient way of
dealing with food waste. On a household level, food waste
disposers improve the convenience and hygiene of dayto-day kitchen function. Eliminating organic waste from
bins can improve household comfort and reduce the risk
of attracting vermin or causing odours, particularly when
temperatures climb in the summer.
On a broader scale, however, they can reduce the amount
of waste that goes into landll, with the potential to convert
food waste into renewable energy through anaerobic
digestion processes which capture the gas generated. As
we continue to embrace this technology as a nation, food
waste disposers will play an increasingly pivotal role in a
total waste management solution.
Power
Gas grid
BiomethaneBiogas
Transport fuel
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1
ABS – Waste Disposed to Landll (1370.0 – Measures of Australia’s Progress, 2010)
http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/1370.0~2010~Chapter~Landll%20(6.6.4)
2
Anaerobic Digestion of Biowaste in Developing Countries
http://www.eawag.ch/forschung/sandec/publikationen/swm/dl/biowaste.pdf
3
ABS – Waste Account, Australia, Experimental Estimates, 2013 – Waste Generation by Industry and Households
http://www.abs.gov.au/ausstats/abs@.nsf/Latestproducts/4602.0.55.005Main%20Features42013?opendocument
4
The Role of Methane
http://earthguide.ucsd.edu/virtualmuseum/climatechange1/03_3.shtml
5
Biogass – Anaerobic Digestion
http://www.biogass.com.au/anaerobic-digestion.html
6
Anaerobic Digestion of Biowaste in Developing Countries
http://www.eawag.ch/forschung/sandec/publikationen/swm/dl/biowaste.pdf
7
Water – Journal of the Australian Water Association
“Codigestion with Glycerole for Improved Biogas Production” M Dawson & S Fitzerald
8
Yarra Valley Water Turning Your Waste to Energy
http://www.yvw.com.au/Home/Aboutus/Ourprojects/Currentprojects/WastetoEnergyfacility/index.htm
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