Odour emission from livestock buildings and guidelines for minimum distances in Germany

Abstract

The purpose of the investigations described in this paper was to develop guidelines to determine the minimum distance between animal farming houses and residential areas for regulatory procedures in Germany. The necessary ventilation of animal houses leads to emissions and air-borne pollution in the surrounding area. Dust, germs and gases are emitted together with the used air. Odours caused by certain gases can lead to annoyance in the neighbourhood of livestock buildings. A minimum distance rule between residential areas and livestock buildings is defined in Germany by the VDI-Guidelines 3471 and 3472 (Emission control - livestock management - pigs and hens). New developments in animal production demand an accommodation of the guidelines: updates are necessary. The basic question is how to deal with the requirement of increasing the validity of the guidelines. The answer is to combine measurements of odour relevant elements and dispersion modelling. Therefore basic research to the emission streams and the distribution behaviour of odour plumes in the surroundings of livestock buildings is carried out. The Institute of Agricultural Engineering Bornim (ATB) and the Federal Agricultural Research Centre (FAL) collaborate with other institutes in Germany. The immission (impact/nuisance) is a function of emission and transmission. The emission mass flow from real livestock buildings with natural and forced ventilation systems is the product of the volume stream and the odour concentration. The volume flow is measured by a special tracer gas technique by means of Krypton 85, the odour concentration by olfactometry. In parallel to this, the meteorological data (especially wind velocity, direction and turbulence) are recorded to describe the transmission conditions. On the immision side the frequency of odour recognition is determined. In combination with transmission and immission data a dispersion model is calibrated. By means of this the greatest distance dmax cattle of no-effect in the surrounding of the special animal house of interest is calculated. The results of several investigations lead to a distance function f(dmax cattle ). In comparison with the disctance rule between pig houses and residential areas as reference distance curve a so-called odour equivalence factor is determined. The advantage of this procedure is to integrate new research results without changing of the entire guideline. The guideline is used as screening model to make a first assessment of the minimum distance at low cost.