Ammonia removal during biofiltration as affected by inlet air temperature and media moisture content

Biofiltration is a promising technology for minimizing odor and gas emissions from livestock buildings. A laboratory experiment investigated N accumulation and N transformations to better understand how biofilters remove airborne NH ₃. Total-N accumulated in the media accounted for only 29% of the N removed by the biofilter after 1160 h. The fate of the remaining N is unknown. Nitric oxide (NO) gas emission accounts for only a small part (<2%) of the difference, and no N was lost via leaching. Microsite denitrification to dinitrogen (N ₂), nitrogen dioxide (NO ₂), or nitrous oxide (N ₂O) may explain some of the discrepancy, but further research is needed. An attempt to determine N transformation rates was not successful due to continuous modeled circular N transformations. Despite these unexplained N fates, this experiment showed that biofiltration can effectively remove NH ₃ levels from exhaust air.