CONTINUOUS MEASUREMENT OF NITROUS OXIDE AND METHANE EMISSION IN PIG UNITS BY INFRARED PHOTOACOUSTIC DETECTION

Emissions of CO2, NH3, N2O, and CH4 from pig units have been continuously measured by use of Infrared Photoacoustic Detection (IPD). The emission of all gases varied during the growth of the pigs. For example, the highest value of CH4 emission rate was four times as high as the lowest during the experimental period. In addition, all gas emissions have a typical diurnal fluctuation. The gas emission value observed at the peak hours (1:00-2:00 P.M.) was twice as high as that observed around 6:00 A.M., even though the room temperature was kept at around 17°C. Those variations may explain why the results presented by other authors differed so much. The CO2, NH3, N2O, and CH4 emissions from pig units during a full fattening period of 8 weeks were estimated to 5540, 181, 9.1, and 302 g/pig (reference units) and those were reduced slightly at 5440, 168, 8.4, and 268 g/pig (experimental units), respectively with weekly discharge of slurry. All CH4 and N2O data from IPD should be recalibrated for reference purposes by the GC method, as the IPD tended to overestimate both the CH4 and N2O values in the samples under normal conditions in the pig units.