Hansen M., Adamsen A., Jonassen K., Feilberg A., 2012, The Effect of Pit Ventilation on the Emission of Odorants from Pig Production, Chemical Engineering Transactions, 30, 229-234.
The aim of the present study was to investigate the effect of pit ventilation on the emission of odorants from pig production facilities. The study was conducted in four experimental facilities with 32 growing-finishing pigs (32–107 kg) in each. Facility A had partly slatted floor and only room ventilation, facility B had fully slatted floor and only room ventilation and facility C and D had fully slatted floor as well as room and pit ventilation. Over a period of six weeks in the middle of the production cycle four air samples were collected once a week from each outlet. The setting for the pit ventilation in facility C and D was alternated each week between 10 or 20 % of the maximum ventilation rate. The air samples were collected in 30 L polyethylene terephthalate (PET) bags. In one half of the samples the odour concentration was measured by dynamic olfactometry approximately 24 h after sampling and in the other half of the samples the concentrations of odorants were measured by Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) approximately 4 h after sampling. The results showed that the emission of odorants such as reduced sulphur compounds, trimethylamine, butanoic acid and 4-methylphenol was higher from the pit ventilation compared to the room ventilation when the pit ventilation was set at 20 %. The results for acetic acid and propanoic acid demonstrated an opposite trend with higher emissions from the room ventilation compared to the pit ventilation. Furthermore, the emission of acetic acid and propanoic acid was higher from the partly slatted facility A compared to the fully slatted facility B and it seems that the surfaces in the facilities also contribute to the emission of carboxylic acids. In conclusion, pit ventilation can be used to concentrate most of the odorants found in pig production facilities in a small part of the ventilation air. More research is needed to study how the emission of odorants from room and pit ventilation is dependent on the pit ventilation rate and the design of the pit ventilation (fouling or resting area of the pen).
