Danish Pig Research Centre Annual Report 2012: Local Air Extraction and Ventilation26 June 2013
The Pig Research Centre in Denmark has been investigating the extraction of noxious gases from the air extracted from pig buildings.
Local Extraction at Grønhøj
At experimental station Grønhøj, it was investigated how to develop efficient local air extraction in finisher pens with fully slatted floors. Using local extraction, the majority of the contaminated air is collected in a small percentage of air that is subsequently cleaned.
As the ventilation air moves in a pig facility, the highest concentrations of ammonia, hydrogen sulphide and odour are found in the slurry pit below or close to the lying area. which is exactly where local extraction of installed.
Recordings at Grønhøj demonstrated that a minimum of 70 per cent of ammonia emissions, 50 per cent of odour emissions and 90 per cent of hydrogen sulphide emissions were collected in what corresponds to 10 per cent of the ventilation capacity. The remaining part of the ventilation air was released traditionally through exhaust facilities in the ceiling.
The Pig Research Centre is currently testing local extraction in three finisher facilities, two gestation facilities and two farrowing facilities. The aim of full-scale testing is to establish how to install local extraction in different types of accommodation and to document whether it is possible to collect the same percentage of air as in the climate chambers at Grønhøj in terms of ammonia and odour emissions.
Results from one finisher facility demonstrated that 80 per cent of ammonia emissions and 50 per cent of odour emissions were successfully collected in the air emitted through local extraction. Ventilation output of the local extraction was approximately 20 cubic metres per hour and pig.
To document the results obtained at Grønhøj, the effect of emitting 10 cubic metres per hour and pig through local extraction is currently being investigated on the trial farms.
One of the finisher farms has 25 per cent solid floor. one has 33 per cent solid floor and the third has 50 per cent solid floor. In the gestation facilities. local extraction is installed in a facility with electronic sow feeding and in a facility with one crate per sow. One of the farrowing facilities is designed with traditional farrowing pens and the other with loose-housed lactating sows.
Cleaning of Extraction Air
PRC is currently investigating reductions in odour and ammonia emissions with a biological air cleaner and a chemical air cleaner, respectively, hooked up to the local extraction facility in a finisher facility and a gestation facility.
It is expected that air cleaners reduce odour and ammonia concentrations at the same level as seen in the trials that form the basis of acceptance of these technologies on the Environmental Protection Agency's Technology List. However, it is unclear how the air cleaners function when they are hooked up to the local extraction facility where the air output is high all year round and where odour and ammonia concentrations are significantly higher than in facilities with traditional ventilation systems.