International Review of Waste Management Policy - Department of ...

The two processes have similar environmental impacts. Key differences between the
two are:
1017
� The use of biofilters in the in-vessel system to reduce ammonia (NH3) and VOC
emissions occurring during the process, resulting in additional N2O emissions;
� The nature of energy consumption (in vessel systems require the use of some
electricity, whilst the windrow facilities use more diesel).
The sections that follow discuss the environmental impacts of composting processes
with respect to air emissions of relevance to climate change and air quality. The use
of the compost results in other environmental benefits such as a reduction in the
requirement for the use of synthetic fertilisers. These benefits - relating to reductions
in soil and water pollution, as well as air pollution - are discussed in Section 63.8.4.
A summary of the damage costs associated with composting processes is provided in
Section 63.8.5.
63.8.1 Nitrogenous Emissions from Composting Processes
Nitrogenous emissions from composting processes impact on both climate change
and air quality. The NH3 emissions are determined by the quantity of ammonium ions,
urea, and organically bound nitrogen. The pH value, temperature, ventilation, and the
C/N-relation constitute other influencing factors. An increase in the pH value, higher
temperature, or better ventilation may all lead to greater emissions. High C/N
relations cause NH3 emissions to diminish. 1257
Nitrous oxide emissions are also determined by temperature, ventilation, nitrogen
content, the C/N relation, and other factors. 1258 Maximum N2O formation rates are
observed if the supply of oxygen during decomposition is insufficient. This may occur,
for example, if the partial pressure of oxygen in the rotting material drops to zero due
to very high rates of biological activity. 1259
1257 K. Csehi, J. Beck and T. Jungbluth (1996) Emissionen bei der Mietenkompostierung tierischer
Exkremente. Landtechnik 51, S. 218-219; K. Csehi (1977) Ammoniakemission bei der Kompostierung
tierischer Exkremente in Mieten und Kompostqualität. Diss. Universität Hohenheim 1977, MEG-
Forschungsbericht 311, 156 S; T. Maeda and J. Matsuda (1997) Ammonia Emissions from Composting
Livestock Manure (Ammoniakemissionen bei der Mistkompostierung), in A. M. Voermanns and G.
Montney (eds.) (1997) Ammonia and Odour Control from Animal Production Facilities (Ammoniak- und
Geruchskontrolle aus Tierproduktionsanlagen), Proceedings I, Vinkeloord, Niederlande, 6.-10. 10.
1997, S. 145-153.
1258 L. Hüther (1999) Entwicklung Analytischer Methoden und Untersuchung von Einflußfaktoren auf
Ammoniak-, Methan- und Distickstoffmonoxidemissionen aus Flüssig- und Festmist.
Landbauforschung Völkenrode, Sonderheft 200, Braunschweig (FAL) 1999, 225 S.
1259 H. J. Hellebrand (1998) Emission of Nitrous Oxide and Other Trace Gases During Composting of
Grass and Green Waste (Emission von Lachgas und anderen Spurengasen während der
Grüngutkompostierung). J. Agric. Engng Res. 69, S. 365-375; S. Zhou, H. Zaeid, and H. Van den Weghe
(1999) Kompostierung tierischer Exkremente - Einfluß der Sauerstoffkonzentration auf
Reaktionskinetik und Emissionsverhalten, Agrartechnische Forschung 5, S. 2-10
International Review of Waste Policy: Annexes