Traitement d'air de porcherie par biofiltration

International audience. A pilot-scale biofilter filled with wood chips was tested to treat ammonia emissions from a piggery located in Brittany (France). Two long-term tests ("summer" and "autumn" experiments) were carried out to improve biofilter applications for agriculture. The influence of climatic conditions on biofilter performance was taken into account. During summer 2012, the biofilter was operated for 74 days at different empty bed residence times (EBRTs) from 6 to 15 seconds. Significant NH3 reductions were achieved at EBRT = 12 s (removal efficiencies (RE) ranged between 90 and 100% for loading rates (LR) of around 4 g.m-3.h-1). At a lower EBRT (6 s), RE dropped to roughly 30-50%. This was mainly due to the dramatic increase in the loading rate (LR up to 12 g.m-3.h-1) but the results showed that the change in atmospheric conditions (temperature and relative humidity) also had a significant influence on biofilter performance. It was evidenced that the use of a humidifier upstream of the biofilter must be taken into account for large-scale biofilter design. During autumn 2012, the biofilter was operated for 116 days at EBRT = 12 s. RE were around 80% for LR of around 3 g.m-3.h-1. In such autumnal atmospheric conditions, a demister system should be installed upstream of the biofilter in order to avoid water accumulation in the bed material. Although biofiltration was suitable for NH3 treatment of piggery air, the need to control accurately the medium moisture content implies that biofilters would not be easily managed by a pig farmer.