Assessment of NH₃ Reduction and N₂O Production during Treatment of Exhausted Air from Fattening Pigs Building by a Commercial Scrubber

Abstract

The use of air scrubbers to reduce ammonia (NH 3 ) emissions from buildings on pig farms is one of the most promising techniques in the GÖteborg protocol and other European regulations including the Industrial Emission Directive. In France, some air scrubbers are currently used on pig farms, mainly to reduce odours from livestock buildings. However, recent research revealed the production of N 2 O resulting from the treatment of air from pig buildings. In this context, a two-month study was conducted on a pig farm with 750 places for fattening pigs to check the abatement of NH3 emissions and to assess the possible production of N 2 O during treatment of exhausted air from buildings housing fattening pigs by a air scrubber. Concentrations of NH 3 and N 2 O in the inlet and outlet air of the scrubber were continuously monitored using an Innova 1412 infrared analyzer. With the scrubber operating parameters (airflow, design, size), our results confirmed the production of N 2 O in the order of 5% of NH 3 -N reduced. N 2 O was produced by biological nitrification and/or denitrification inside the air scrubber. Statistical analysis (Pearson’s test) showed that the production of N 2 O was strongly influenced by the rate of airflow and the outside temperature. The abatement of NH 3 emissions from the building was only 33%, i.e. much lower than the 70% - 90% usually cited in the literature.