The dynamic emissions of NH3, CO2, H2S as influenced by the spatial and temporal variation in slurry addition

Abstract

It is widely recognized that livestock production is very important to humans because it provides us food, incomes, employment, nutrients and risk insurance. However, it also contributes to a range of serious environmental problems, including the climate changing emissions, acidification of natural environments and eutrophication. Since in different parts of Europe animal production is highly concentrated in certain areas, it is very important to accurately determine the gas release of the major air pollutants emitted from animal waste (i.e. ammonia, carbon dioxide and hydrogen sulphide) in order to ensure a safe workplace as well as to reduce the emission of these gases. Gas release behaviours of ammonia, carbon dioxide and hydrogen sulphide were studied when the slurry was disturbed. In a farm there are many disturbances which can affect the emission of these gases. This study focuses in the slurry addition disturbance, which tries to simulate the pig’s behaviour. That means that the slurry addition was performed randomly in space and time. Two types of slurry were studied: one from slaughtering pigs (30-95 kg) and the other from small pigs up to about 30 kg. Ammonia emissions showed a decrease right after performing each addition, followed by an increase while carbon dioxide emissions show an immediate increase followed by a sharp decrease. Hydrogen sulphide emissions were much higher during disturbances, showing an unpredictable pattern release. It was also investigated how the pH was affected by the slurry addition and how it changes during time by measuring the pH in the surface layers (at a depth of 0.5-1cm) and in the inner layers (at a depth of 4 and 6 cm). The results show an increase of the pH after disturbances and the formation of a pH gradient from deeper to top layers.