Production and emission of odours and gases from ageing pig waste

Emission rates of gases and compounds that cause odour (odorants) and their cumulative odour as perceived by a sensory panel were determined over a. 112 d storage period for pig slurry. Emission rates of H2S, volatile fatty acids, phenols and CO2 decreased over the storage period, while those of CH4 and NH3 increased. No correlation was found between the olfactory response and any individual odour component although there was correlation between individual odorants. Averaged emission rates were used to predict the annual production of gases and odorants based on the most recent UK ammonia emission inventory of emissions from pig production. Annual emissions from storage facilities were determined for individual odorants consisting of volatile fatty acids, phenols and indoles. They were generally less than 1 kt/yr apart from acetic acid which was estimated to be 1.1kt. Methane and CO2 emission rates were 16.6 and 486 kt per annum, respectively. Sulphide emissions were higher than expected at 393 kt per annum; possible reasons for this are discussed. (C) 1999 Silsoe Research Institute.