Chemical analysis of odorants from poultry facilities

Abstract

Population growth has increased pressures on primary producers, including poultry producers, to competitively produce greater amounts of produce, whilst reducing environmental impact. In addition; the resulting rural encroachment has substantially reduced the buffer distance between primary producers and neighbouring properties, yielding increased odour related complaints. This research project aims to improve understanding of the emission of odorous compounds from poultry facilities by benchmarking analytical methodologies. In particular this thesis focuses on methodologies for speciation of Non-Methane Volatile Organic Compound (NMVOC) and odorant emissions from mechanically ventilated poultry houses in Australia. Laboratory analysis methods (dilution olfactometry) have been established to quantitatively assess odour intensity. However assigning a numerical value to an odour does not provide information relating to its chemical composition or character. An understanding of the chemical composition of the odour is required to better manage the emissions from an operation. While identifying the emitted chemical species provides useful information; the key to understanding the odour is establishing which of the chemical species are odorants. The use of gas-chromatography with simultaneous mass spectral and olfactory detection provides a method of identifying the chemical species present along with their odour potential. Extensive field sampling of broiler and layer facilities was performed to develop an understanding of the emissions of poultry houses. The broiler houses yielded greater chemical diversity and abundance than the layer houses. NMVOCs identified within the emissions included alcohols, aldehydes, ketones, carboxylic acids and terpines. Gains were made in understanding the fate of specific odorants and NMVOCs and the potential impact on emissions. Although beyond the initial scope of the research, interpreting the presence of disulphide species within the emissions was essential to interpreting the overall odour profile. Experimental results reflected a plausible correlation between disulphide presence in samples and thiol presence in the field. Whilst significant laboratory analysis methodological developments were made and an extensive database of results established; the variety of chemical species and abundances between sampling campaigns was a significant result. This variability has identified the need to further investigate litter material of broiler houses as a potential source of nuisance odour emissions.