Nitrogen Capture and Accumulation in Biofilters Treating Aerial Emissions From Swine Production Facilities.

Biofiltration is used to reduce ammonia (NH₃-N) and hydrogen sulfide (H₂S) emissions from livestock facilities. Current research evaluates the effectiveness of a biofiltration system as percentage total target gas removed from the inlet air.  Alternative loss pathways from a single-layer open biofiltration system operating under field conditions are not addressed.  The objectives are (1) to  compare the NH₃-N, nitrate (NO₃-N), total nitrogen (TN) and sulfur (S) content as well as the carbon to nitrogen ratio (C:N) of the straw and compost biofilter media and (2) to compare the NH₃-N, NO₃-N and TN and S present in the soil below and adjacent to the biofilters. Four replications of straw and compost media were sampled with the media divided into top half, bottom half, and soil surface litter.  The soil below and adjacent to the biofilter was sampled at the depths of 0- 5 cm, 5-10 cm and 10-15 cm.  All samples were analyzed for NH₃-N, NO₃-N, TN, S and total carbon (TC).  Straw media NH₄-N and NO₃-N, TN and S content increased while TC content decreased with depth.  The compost media had similar concentrations of NH₄-N throughout the media profile while NO₃-N concentration higher in the bottom half and soil surface litter.  The compost media has a stable TC and TN content.  Under both media the concentration of NH₃-N, NO₃-N and TN were greater than in the soil adjacent to the biofilter. Sulfur concentrations were higher adjacent to the biofilter than below the media.  The capacity of a media to capture and accumulate inorganic-N and S appears to be different based on the availability of carbon.  The inorganic-N concentration is significantly greater beneath the biofilter than outside the biofilter regardless of media, while S concentration was greater adjacent to the biofilter.