Reduction of ammonia and odor emissions from a piggery with biofilters

Long-term measurements were carried out in parallel on two biofilters under practical conditions to test their reduction potential for ammonia and odo r emissions. The average efficiency of the ammonia reduction calculated for the first measuring period (6.5-year-old filterbed material) was about 15% at biofilter 1 and 36% at biofilter 2, The average efficiency of the odor reduction calculated for the first measuring period was about 78% at biofil ter I and 80% at biofilter 2. The efficiency of ammonia reduction was mainl y influenced by the airflow rare. The odor reduction was mainly influenced by the odor concentration before the filterbed. The cleaning efficiency of the biofilters could be improved by increasing the moisture content of the filterbed material from 20% to 40%, or from 20% to 50%.