Immission of Microorganisms from Composting Facilities
The dispersion and composition of microbial aerosols in the surrounding of three composting plants in central Germany were examined. Immission measurements were carried out at specifically chosen sampling points downwind to the plants including reference
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c. Jureit, A. Albrecht and A. Neefl
Abstract. The dispersion and composition of microbial aerosols in the surrounding of three composting plants in central Germany were examined. Imrnission measurements were carried out at specifically chosen sampling points downwind to the plants including reference points upwind. Only sampling days (nights) were chosen for which the meteorological situation allowed a minimum dilution of the bioaerosol emissions downwind to the plants. The samples were analysed for the presence of six groups of organisms by selective cultivation, including mesophilic bacteria and moulds, xerophilic moulds as well as thermophilic moulds and thermophilic actinomycetes. Determined concentrations of CFU showed marked differences in the imrnission situations around the three plants ranging from 0 to more than 106 cfu m-3 . Concentrations of microorganisms downwind to the composting plants correlated with distances of the sampling points from the plant. The specific meteorological conditions (especially drainage flow situations) during sampling and local topography obviously have a strong impact on the results of bioaerosol sampling. On the basis of these results a more general sampling strategy was developed.
Introduction Composting of organic material is an integral part of modern waste management based on a recycling approach. The aim is a mass and volume reduction of the biodegradable part of mainly municipal wastes. Compost as the product of the process can be used as organic fertiliser. In Germany around 550 full-scale composting plants process about 8 million tons of biological wastes (Kampfer and WeiBenfels 2001). The compost process comprises the degradation of organic materials containing high quantities of easily biodegradable carbohydrates, proteins and lipids. Within this complex process, spontaneous self-heating to 55-60°C is an inherent part of the process (Lacey and Crook 1988). Especially this part is responsible for the development of thermophilic and thermotolerant microorganisms, among them mucoraceous fungi and aspergilli, especially Aspergillus fumigatus. As a consequence, spores of these organisms can be released into the surrounding air during the various processing steps of biological waste treatment (ReiB 1995). Often, the biodegradable materials are initially shredded, repeatedly moved during the rotting iInstitut fOr Angewandte Mikrobiologie, IFZ fur Umweltsicherung, Justus-Liebig-Universitat Giessen, Heinrich-Buff-Ring 26-32,35392 Giessen, Germany H. Insam, N. Riddech, S. Klammer (Eds.) Microbiology of Composting © Springer-Verlag Berlin Heidelberg 2002
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Kampfer et al.
phase, and when the composting process is finished, the compost is sieved to remove large particles including materials which are not biodegradable. All these operation processes can lead to emissions of microorganisms into the air. Bioaerosols which originate from compost can contain various microorganisms, among them vegetative cells and spores from bacteria especially actinomycetes and fungi (Milln
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