Effects of airflow on odorants' emissions in a model pig house — A laboratory study using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS)

Identification of different factors that affect emissions of gasses, including volatile organic compounds (VOCs) is necessary to develop emission abatement technology. The objectives of this research were to quantify and study temporal variation of gas emissions from a model pig house under varying ventilation rates. The used model was a 1:12.5 scale of a section of a commercial finishing pig house. The VOC concentrations at inlet, outlet, and slurry pit of the model space were measured using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS). PTR-MS can measure the temporal variations of odor compounds' emission from the slurry pit in real time. The emissions of H2S and 14 VOCs were lower compared to real pig buildings except for ammonia, which indicated possible other sources of those compounds than the slurry in the slurry pit. The ventilation rate affected significantly on ammonia and trimethylamine emission (p < 0.05). The hydrogen sulfide (H2S) emission was independent of the ventilation rate. VFAs' emission dependency on ventilation rate increased with the increase of carbon chain. Phenols, indoles and ketones showed the positive correlation with ventilation rate to some extent. Generally, compounds with high solubility (low Henry's constant) showed stronger correlation with ventilation rates than the compounds with high Henry's constant.

► Proton-Transfer-Reaction Mass Spectrometry was used to measure odorants in real time.
► Ammonia, hydrogen sulfide and 14 volatile organic compounds (VOCs) were measured from pig slurry.
► Temporal variations of odorants were explained by four factors.
► The factors were surface pH, dry matter enrichment, depletion, and oxidation.
► Complex relations between ventilation rate and odorants' emissions were observed.