The situation in poultry keeping


Poultry keeping has increased significantly in the last years. Poultry meat is low-cost, low in fat, healthy and its consumption is not restricted by religious taboos. The per capita poultry consumption increased from 12.4 kg (1989/1990) to 18.5 kg (2011/2012). But the increase in poultry keeping in Germany also results in environmental impacts via the emission of odorants, ammonia, particulate matter and bio-aerosols (Fig. 1).

Fig. 1: Large air volumes with undesired emissions are created in big stables with a high animal density (© aid infodienst/Peter Meyer)

Against this background we develop techniques for the cleaning of exhaust air from poultry keepings. The main problem in this connection is the large air volume flow which is required to meet the animal welfare demands within the stable and must be cleaned. In a typical broiler house with 40,000 full grown heads, a volume flow of 240,000 m³/h can occur during the summer time. These large volume flows result in a short residence time in the exhaust air treatment system. It makes matters worse that many typical odorants in the exhaust air of poultry keepings are hardly water soluble and therefore hardly open to washing-off. Particulate matter contributes to blockages of air scrubbers.   

Fig. 2: Multistage test facility for the cleaning of poultry exhaust air (© Thünen-Institut/AT)

Therefore it is aim of the work with different test facilities (Fig. 2) to develop an effective upstream dust removal and an increased odor reduction under practical conditions to economically feasible conditions. The upstream dust removal unit consists of a filter fleece to separate coarse particles. The pressure drops increase during this operation. The pressure drop is controlled and in the case of exceeding a set point, automatic working fleece regeneration starts with fleece cleaning and dust removal in a manageable form. The main advantage of upstream dust removal: Downstream process units will be protected against blockages and loss of operability.

Fig. 3 shows that particles with a diameter of at least 1.3 µm can be separated with an efficiency of more than 70 %. The separation efficiency increases analogue to the particle size. 

Fig. 3: Separation of particles as a function of the particle size range at the cleaning of poultry exhaust air (© Thünen-Institut/Jochen Hahne)

While more than 1,000 installations have been realized in pig keeping, only 179 are in poultry keepings (status: December 2013).