Extraction efficiency of odorous compounds during a winter and summer period for partial pit ventilation in pig houses with diffuse ceiling inlet and wall inlets

Abstract

Partial pit ventilation is a strategy to concentrate a large part of the air pollutants from pig houses in a small part of the ventilation air that can be treated by an air cleaner. In this study, the effect of partial pit ventilation on odorant emissions from two experimental pig houses (32 pigs in each) with two different ventilation inlet systems (diffuse ceiling inlet and wall inlet) was evaluated in two seasons (winter and summer). The emission of ammonia and odorants was measured by proton-transfer-reaction mass spectrometry. At a set point of 10% of the maximum total ventilation, the pit ventilation air contained on average 20 to 50% by mass of the different odorants in summer. In winter, when the pit ventilation exceeds 10% of the ventilation rate, it contained 30 to 65% of the various odorants. The effect of increasing the percentage of pit ventilation (10, 20 and 30%) was tested under summer conditions. This resulted in increasing pit extraction efficiency for both inlet systems and all odorants. In the wall inlet system, it also led to an increase in total emission of most compounds, while in the diffuse ceiling inlet system this was only the case for some compounds. In conclusion, the diffuse inlet system seems more favourable for pit ventilation, with generally higher pit extraction efficiencies for important odorants and a lower tendency for higher emission with increasing pit ventilation percentage.