Report - DCE - Nationalt Center for Miljø og Energi

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This category is a catch all for the waste sector. Emissions in this category
could stem from sludge spreading, compost production, accidental fires,
biogas production and other combustion without energy recovery.
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Sludge from waste water treatment plants is only spread out in the open
with the purpose of fertilising crop fields. Emissions that derive from this activity
are covered in Chapter 6.
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This section covers the biological treatment of solid wastes called composting.
Pollutants that escape from this treatment are ammonia (NH3) and carbon
monoxide (CO).
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Emissions from composting have been calculated according to a country
specific method.
In Denmark, composting of solid biological waste includes composting of:
• garden and park waste (GPW),
• organic waste from households and other sources,
• sludge and,
• home composting of garden and vegetable food waste.
In 2001, 123 composting facilities treated only garden and park waste (type 2
facilities), nine facilities treated organic waste mixed with GPW or other organic
waste (type 1 facilities) and 10 facilities treated GPW mixed with
sludge and/or “other organic waste” (type 3 facilities). 92 % of these facilities
consisted entirely of windrow composting which is a low technology
composting method with natural access to air. It is assumed that all facilities
can be considered as using windrow composting.
Composting is performed with low technology in Denmark this means that
temperature, moisture and aeration is not consistently controlled or regulated.
Temperature is measured but not controlled, moisture is regulated by
watering the windrows in respect to weather conditions and aeration is assisted
by turning the windrows (Petersen & Hansen, 2003).
During composting a fraction of the degradable organic carbon (DOC) in the
waste material is converted into CO. Even though the windrows are regularly
turned to support aeration, anaerobic sections are inevitable and will
probably cause a small emission of CH4. In the same manner, aerobic biological
digestion of N leads to an emission of NOX, while the anaerobic decomposition
leads to the emission of NH3. (IPCC Guidelines, 2006).
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All Danish waste treatment plants are obligated to statutory registration and
reporting of all wastes entering and leaving the plants. All waste streams are
weighed, categorised with a waste type and a type of treatment and registered
to the ISAG waste information system (Affaldsstatistik, 2006).