Further information: Interessengemeinschaft
Geruch **igG**

The second regulatory approach are model calculations of the separation distance using dispersion models. Following information has to be available: odour release (Martinec et al., 1998; Schauberger et al., 1999), a dispersion model (eg the normative Gauss model used in Austria, Kolb, 1981), calculation of the instantaneous odour concentration (Schauberger et al., 2000b) and validation of the instantaneous odour concentration taking into account the FIDO factors of odour sensation (frequency, intensity, duration and offensiveness) and reasonableness.

**Austrian
Odour Dispersion Model AODM**

The dynamic Austrian odour dispersion
model (AODM) consists of three modules: the first calculates the odour emission
of the livestock building, the second estimates mean ambient concentrations
by a regulatory dispersion model. The last module transforms the mean odour
concentration of the dispersion model to instantaneous values according to
wind velocity and stability of the atmosphere.

The emission module is based on a steady-state
balance of the sensible heat fluxes to calculate the indoor temperature and
the related volume flow of the ventilation system (Schauberger et al., 2000a).
The corresponding odour flow is assessed by a simple model of the odour release.
The consideration of the diurnal variation of the odour emission is the most
important feature of this module. Since odour is mainly released by the animals,
by polluted surfaces and by the feed, the diurnal variation of the emission
is assumed to be in phase with animal activity. Outdoor odour sources such
as slurry tanks or feed storage facilities are not taken into account. For
the model calculation presented here, a mean specific odour flow of 100 OU/s
LU (Martinec et al. 1998) and a mean live mass of 60 kg per fattening pig
(M = 0.12 LU) were used. The model has been described extensively in Schauberger
et al. (1999a and 1999b).

The model calculations were done for a
pig fattening unit of 1000 pigs with a forced ventilation. The livestock building
is moderately isolated, described by the U value (Tab. 1). The assumed space
per animal is 0.75 m² according to welfare guide lines. The chosen system
parameters for a livestock building with these specifications, typical for
middle Europe, are summarised in Table 1.

The odour concentration of the centre line
of the plume is calculated by the Austrian regulatory dispersion model (ÖNorm
M 9440, 1992/96; Kolb, 1981) by making use of a statistics of stability classes
representative for the Austrian flatlands north of the Alps. The model has
been validated internationally with generally good results (e.g. Pechinger
and Petz, 1995). The regulatory model is a Gaussian plume model applied for
single stack emissions and distances up to 15 km. Plume rise formulae used
in the model are a combination of formulae suggested by Carson and Moses
(1969) and Briggs (1975). The model uses a traditional discrete stability
classification scheme with dispersion parameters developed by Reuter (1970).

The regulatory model calculates half hour
mean concentrations. The sensation of odour, however, depends on the momentary
odour concentration and not on a mean value over a long time of integration.
The peak value is derived from the half our mean value using the relationship
of Smith (1973) depending on the stability of the atmosphere. These values
are only valid close to the odour source. Due to turbulent mixing, the peak-to-mean
ratio is reduced with increasing distance from the source using the wind
velocity and the stability of the atmosphere. This peak-to-mean ratio in
equation is modified by an exponential attenuation function (Mylne and Mason,
1991) using the time of travel with the distance x and the mean wind velocity
u, and the Lagrangian time scale as a measure of the stability of the atmosphere
(Mylne, 1992). This approach is described by Schauberger et al. (2000b).

Schauberger, G., M. Piringer (1997a): Assessment of the
protection distance to avoid annoyance by odour sensation caused by livestock
husbandry by the Austrian guide line. In: Voermans J.A.M., G.J. Monteny (Eds):
Ammonia and Odour Emission from Animal Production Facilities, NVTL, Rosmalen
(1997)

Schauberger, G., M. Piringer (1997b): Guideline to assess
the protection distance to avoid annoyance by odour sensation caused by livestock
husbandry. In: Bottcher R.W., Hoff S.J. (Eds): Livestock Environment V, ASAE,
St. Joseph, Michigan, 1997

Schauberger, G., M. Piringer, J. Eder, H. Fiebiger, M. Köck,
R. Lazar, F. Pichler-Semmelrock, T. Quendler, M. Swoboda, G. Thiemann, J.
Teufelhart (1997): Österreichische Richtlinie zur Beurteilung von Immissionen
aus der Nutztierhaltung in Stallungen. Gefahrstoffe - Reinhaltung der Luft
57,10:399-408.

Schauberger, G., Piringer, M., Petz, E. 1999. Diurnal and
annual variation of odour emission of animal houses: a model calculation for
fattening pigs. Journal of Agricultural Engineering Research 74, 3: 251-259

Schauberger, G., Piringer, M., Petz, E. 2000a. Steady-state
balance model to calculate the indoor climate of livestock buildings demonstrated
for fattening pigs. International Journal of Biometeorology, in print

Schauberger, G., Piringer, M., Petz, E. 2000b: Diurnal and
annual variation of the sensation distance of odour emitted by livestock buildings
calculated by the Austrian odour dispersion model (AODM) Atmospheric Environment,
submitted

**Links to other dispersion models**

- MISKAM - Dr. Eichhorn, Univ Mainz
- DASIM
- UK-ADMS Atmospheric Dispersion Modelling System - Link
- MPTER (Environmental Protection Agency - Air Quality Models)
- Ingenieurbüro Dr.-Ing. Lohmhttp://www.lohmeyer.de/ayer, Karlsruhe und Dresden
- European Environment Agency, European Topic Centre on Air Quality, Model Documentation System
- AODM Austrian Odour Dispersion Model
- IBJXodor - Ingineurbüra Janicke

Odour Reduction Technologies - Canada

Last modification: January 31, 2000 Webmaster